Receptors for the major inhibitory neurotransmitter, gamma- aminobutyric acid (GABA), are divided into two main classes: (1) GABAA receptors, which are members of the ligand-gated ion channel superfamily; and (2) GABAB receptors, which may be members of the G-protein linked receptor superfamily. Since the first cDNAs encoding individual GABAA receptor subunits were cloned the number of known members of the mammalian family has grown to thirteen (six a subunits, three p subunits, three y subunits and one 6 subunit). It may be that further subunits remain to be discovered; however, none has been reported since 1993.

Although knowledge of the diversity of the GABAA receptor gene family represents a huge step forward in our understanding of this ligand- gated ion channel, insight into the extent of subtype diversity is still at an early stage. It has been indicated that an a subunit, a (3subunit and a y subunit constitute the minimum requirement for forming a fully functional GABAA receptor expressed by transiently transfecting cDNAs into cells. As indicated above, a 6 subunit also exists, but is apparently uncommon in the native receptor.

Studies of receptor size and visualisation by electron microscopy conclude that, like other members of the ligand-gated ion channel family, the native GABAA receptor exists in pentameric form. The selection of at least one a, one p and one y subunit from a repertoire of thirteen allows for the possible existence of more than 10,000 pentameric subunit

combinations. Moreover, this calculation overlooks the additional permutations that would be possible if the arrangement of subunits around the ion channel had no constraints (i.e. there could be 120 possible variants for a receptor composed of five different subunits).

Receptor subtype assemblies which do exist include alp2y2, a2P2/3y2, a3py2/3, a2 yl, a5P3y2/3, a6py2, a6 6 and a4 6. Subtype assemblies containing an al subunit are present in most areas of the brain and account for over 40% of GABAA receptors in the rat. Subtype assemblies containing a2 and a3 subunits respectively account for about 25% and 17% of GABAA receptors in the rat. Subtype assemblies containing an a5 subunit are primarily hippocampal and represent about 4% of receptors in the rat.

A characteristic property of some GABAA receptors is the presence of a number of modulatory sites, of which the most explored is the benzodiazepine (BZ) binding site through which anxiolytic drugs such as diazepam and temazepam exert their effect. Before the cloning of the GABAA receptor gene family, the benzodiazepine binding site was historically subdivided into two subtypes, BZ1 and BZ2, on the basis of radioligand binding studies. The BZ1 subtype has been shown to be pharmacologically equivalent to a GABAA receptor comprising the al subunit in combination with 2 and y2. This is the most abundant GABAA receptor subtype, representing almost half of all GABAA receptors in the brain.

A number of dementing illnesses such as Alzheimer's disease are characterised by a progressive deterioration in cognition in the sufferer. It would clearly be desirable to enhance cognition in subjects desirous of such treatment, for example for subjects suffering from a dementing illness.

It has been reported by McNamara and Skelton in Psychobiology, 21:101-108, that the benzodiazepine receptor inverse agonist p-CCM enhanced spatial learning in the Morris watermaze. However, p-CCM and other conventional benzodiazepine receptor inverse agonists are

proconvulsant or convulasnt which makes it clear that they cannot be used as cognition enhancing agents in humans.

However, we have now discovered that it is possible to obtain medicaments which have cognition enhancing effects which may be employed with less risk of proconvulsant effects previously described with benzodiazepine receptor partial or full inverse agonists.

It has now been discovered that use of an a5 receptor partial or full inverse agonist which is relatively free of activity at al and/or a2 and/or a3 receptor binding sites can be used to provide a medicament which is useful for enhancing cognition but in which proconvulsant activity is reduced or eliminated. Inverse agonists at a5 which are not free of activity at al and/or a2 and/or a3 but which are functionally selective for a5 can also be used. Inverse agonists which are both selective for a5 and are relatively free of activity at a1 , a2 and a3 receptor binding sites are preferred.

European Patent Applications 0085840 and 0134946 describe related series of 1,2,4-triazolo[3,4-a]phthalazine derivatives which are stated to possess antianxiety activity. However, there is no disclosure nor any suggestion in either of these publications of the compounds of the present invention, nor that the compounds disclosed in the Applications have any cognition enhancing properties.

The present invention provides a compound of the formula I: wherein: R1 is hydrogen, halogen or CN or a gour CF3, OCF3, C1-4alkyl, C2-4alkyenyl, C2-4alkynyl, C1-4alkoxy, C2-4alkenyloxy or C2-4alkynyloxy, each

of which groups is unsubstituted or substituted with one or two halogen atoms or with a pyridyl or phenylring each of which rings may be unsubstituted or independently substituted by one or two halogne atoms or nitro, cyano, amino, methyl or CF3 groups; R2 is hydrogen, halogen or CN or a group CF3, OCF3, C1-4alkyl, C2-4alkyenyl, C2-4alkynyl, C1-4alkoxy, C2-4alkenyloxy or C2-4alkynyloxy each of which groups is unsubstituted or substituted with one or two halogen atoms; L is O, S or NR" where Rn is H, C1-6alkyl or C3-6cycloalkyl; X is a 5-membered heteroaromatic ring containing 1, 2, 3 or 4 heteroatoms independently chosen from oxygen, nitrogen and sulphur, at most one of the heteroatoms being oxygen or sulphur, or a 6-membered heteroaromatic ring containing 1, 2 or 3 nitrogen atoms, the 5- or 6-membered heteroaromatic ring being optionally fused to a benzene ring and the heteroaromatic ring being optionally substituted by RX and/or R-' and/or Rz, where Rx is halogen, R3, OR3, OCOR3, NR4R5, NR4COR5, tri(Cl.calkyl)silylCI~calkoxyC14alkyl, CN or R9, RY is halogen, R3, OR3, OCOR3, NR4R5, NR4COR5 or CN and Rz is R3, OR3 or OCOR3, where R3 is C1-6alkyl, C2-6alkyenyl, C2-6alkynyl, C3-6cycloalkyl, hydroxyC16alkyl and R3 is optionally mono, di- or tri-fluorinated, R4 and R5 are each independently hydrogen, C1-6alkyl, C26alkenyl, C2-6alkynyl, C3-6cycloalkyl or CF3 or R4 and R5, together with the nitrogen atom to which they are attached, form a 4-7 membered heteroaliphatic ring containing the nitrogen atom as the sole heteroatom, and R9 is benzyl or an aromatic ring containing either 6 atoms, 1, 2 or 3 of which are optionally nitrogen, or 5 atoms, 1, 2 or 3 of which are independently chosen from oxygen, nitrogen and sulphur, at most one of the atoms being oxygen or sulphur, and R9 is optionally substituted by one, two or three substituents independently chosen from halogen atoms and C1-4alkyl, C2-4alkenyl, C2-4alkynyl, C1-4alkoxy, C2-4alkenyloxy and C2-4alkynyloxy groups each of which groups is unsubstituted or substituted by one, two or three halogen atoms, and

when X is a pyridine derivative, the pyridine derivative is optionally in the form of te N-oxide and providing that when X is a tetrazole derivative ot is protected by a C1-4alkyl group; or X is phenyl optionally substituted by one, two or three groups independently selected from halogen, cyano, C1- 6alkyl, C2-6alkenyl, C2-6alkynyl and C3-6cycloalkyl; Y is optionally branched Cl 4alkylidene optionally substituted by an oxo group or Y is a group (CH2)jO wherein the oxygen atom is nearest the group X andj is 2,3 or 4 ; Z is a 5-membered heteroaromatic ring containing 1, 2 or 3 heteroatoms independently selected from oxygen, nitrogen and sulphur, at most one of the heteroatoms being oxygen or sulphur and providing that when one of the atoms is oxygen or sulphur then at least one nitrogen atom is present, or a 6-membered heteroaromatic ring containing 2 or 3 nitrogen atoms, Z being optionally substituted by Rv and/or Rw, where Rv is halogen, R6, NR7R8, NR7COR8, CN, furyl, thienyl, phenyl, benzyl, pyridyl or a 5-membered heteroaromatic ring containing at least one nitrogen atom and optionally 1, 2 or 3 other heteroatoms independently selected from oxygen, nitrogen and sulphur, at most one of the other heteroatoms being oxygen or sulphur and Rw is RG or CN; r6 is C1-6alkyl, C2-6alkenyl, C206alkynyl, C3-6cycloalkyl, hydroxyC1-6alkyl, C1-6alkoxy, C2-6alkenyloxy, C2-6alkynyloxy, C1-6alkoxyC1-6alkyl, CH2F or CF3; and R7 and R8 are each independently hydrogen, C1-6alkyl, C2-6alkenyl, C2 6alkynyl, C3-6cycloalkyl or CF3 or R7 and R8, together with the nitrogen atom to which they are attached, form a 4-7 membered heteroaliphatic ring containing the nitrogen atom as the sole heteroatom; or a pharmaceutically acceptable salt thereof.

As used herein, the expression "C1-6alkyl" includes methyl and ethyl groups, and straight-chained and branched propyl, butyl, pentyl and hexvl groups. Particular alkyl groups are methyl, ethyl, n-propyl, isopropyl and t-butyl. Derived expressions such as "C1-4alkyl", "C2-4alkenyl",

"C2-6alkenyl", "hydroxyC1-6alkyl", "C2-4alkyl" and "C2-6alkynyl" are to be construed in an analogous manner.

The expression "C3-6cycloalkyl" as used herein includes cyclic propyl, butyl, pentyl and hexyl goups such as cyclopropyl and cyclohexyl.

Suitable 5- and 6-membered heteroaromatic rings include pyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, pyrrolyl, pyrazolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, imidazolyl, oxadiazolyl and thiadiazolyl groups. A suitable 5-membered heteroaromatic ring containing four nitrogen atoms is tetrazolyl. Suitable 6-membered heteroaromatic rings containing three nitrogen atoms include 1,2,4-triazine and 1,3,5-triazine.

The term "halogen" as used herein includes fluorine, chlorine, bromine and iodine, of which fluorine and chlorine are preferred.

As used herein the term "Ci.alkoxy" includes methoxy and ethoxy groups, and straight-chained, branched and cyclic propoxy, butoxy, pentoxy and hexoxy groups, including cyclopropylmethoxy. Derived expressions such as "C2-6alkenyloxy", "C2-6alkynyloxy", "C1-4alkoxy", "C2-4alkenyloxy" and "C.alkyloxy" should be construed in an analogous manner.

R1 may be hydrogen, halogen or CN or a group C1.4alkyl, C2-4alkenyl, C2-4alkynyl, C1-4aoxy, C2-4alkenyloxy or C2-4alkynyloxy, each of which groups is unsubstituted or substituted with one or two halogen atoms or with a pyridyl or phenyl ring each of which rings may be unsubstituted or independently substituted by one or two halogen atoms or nitro, cyano, amino, methyl or CF3 groups. R1 is typically hydrogen, fluorine, chlorine, bromine or a group Cl 4alkyl, C2 4alkenyl, C2 4alkynyl, C1-4alkoxy, C2 4alkenyloxy or C2 4alkynyloxy, each of which groups is unsubstituted or substituted with one or two halogen atoms or by a pyridyl or phenyl ring each of which rings may be unsubstituted or substituted by one or two halogen atoms or nitro, cyano, amino, methyl or CF3 groups and is generally hydrogen, fluorine or pyridylmethoxy, typically hydrogen.

R2 may be hydrogen, halogen or CN or a group C1-4alkyl, C2-4alkenyl, C2-4alkynyl, C1-4alkoxy, C2-4alkenyloxy of C2-4alkynyloxy each of which groups is unsubstituted or substituted with one or two halogen atoms. R2 is typically hydrogen, fluorine, chlorine or bromine, and is generally hydrogen or fluorine, typically hydrogen.

Preferably L is an oxygen atom. L may also be NR" in which Rn is preferably hydrogen or methyl. Rn may be hydrogen.

X is generally: pyridyl, pyrazinyl, pyridazinyl or pyrimidinyl optionally substituted by a halogen atom or a group R3, OR3, NR4R5 or a five membered heteroaromatic ring containing 1, 2 or 3 nitrogen atoms, and X is optionally fused to a benzene ring; a 5-membered heteroaromatic ring containing 2 or 3 heteroatoms chosen from oxygen, sulphur and nitrogen, at most one of the heteroatoms being oxygen or sulphur, which is unsubstituted or substituted by one, two or three groups independently chosen from halogen and R3, or which is substituted by a pyridyl, phenyl or benzyl ring which ring is optionally independently substituted by one, two or three halogen atoms or Cl 6alkyl or CF3 groups; or phenyl optionally substituted by one, two or three independently chosen halogen atoms. In particular X is pyridyl, pyrazinyl, pyridazinyl or pyrimidinyl which is unsubstituted or substituted by methyl, CF3, methoxy, bromine, chlorine, isopropoxy, dimethylamino or a 5-membered heterocyclic ring containing 1, 2 or 3 nitrogen atoms, and X is optionally fused to a benzene ring, or X is pyrazolyl, isothiazolyl, isoxazolyl, 1,2, 4-triazolyl, thiazolyl, 1,2,3- triazolyl or imidazolyl which is unsubstituted or substituted by one, two or three groups independently chosen from methyl, CF3 and chlorine or is substituted by a phenyl, benzyl or pyridyl ring which ring is unsubstituted or substituted by chlorine or CF3, or X is phenyl which is unsubstituted or substituted by chlorine. X may be monosubstituted by tri(C 6alkyl) silylCl 6alkoxyCl 4alkyl such as trimethylsilylethoxymethyl.

A favoured value of X is pyridazine. Specific values of X are 2-pyridyl, 6- methylpyridin-2-yl, 3-pyridyl, 4-pyridyl, 3, 5-dimethylpyrazol- 1 -yl, 3-

methoxypyridin-2-yl, 3-methylisoxazol-5-yl, pyrazol-1-yl, 6-chloropyridin- 2-yl, 6-bromopyridin-2-yl, 6-methoxypyridin-2-yl, 6-isopropoxypyridin-2-yl, 6-N,N-dimethylpyridin-2-yl, 6-(imidazol-1-yl)pyridin-2-yl, 3-pyridazino, 4- pyrimidinyl, pyrazin-2-yl, 2-quinolinyl, 2-quinoxalyl, 2-(4- trifluoromethyl)pyridyloxy, 4-methylisothiazolyl, 2, 6-dichlorophenyl, 4- methylthiazol-S-yl, 2-methylthiazol-4-yl, 2-C1-(3-trifluoromethyl)pyrid-6- yl]imidazolyl, 1-benzylimidazol-2-yl, 1-(4-chlorophenyl)-1,2,3-triazol-4-yl, 3-chloro-2-methyl-5-trifluoromethylpyrazol-4-yl and 1-methyl- 1,2, 4-triazol- 3-yl. Further specific values of X are (5-trifluoromethyl)pyridyl-2-yl, (3- trifluoromethyl)pyrid-2-yl, (4-trifluoromethyl)pyrid-2-yl, 1-methylimidazol- 2-yl, 2-{[2-(trimethylsilyl)ethoxy]methyl}-1,2,4-triazol-3-yl, 3- methylimidazol-4-yl, 1,2, 4-triazol-3-yl, 1-isopropyl- 1,2, 4-triazol-3-yl, 4- methyl- 1,2, 4-triazol-3-yl, 1,2, 3-triazol-4-yl, isothiazol-3-yl, 1-ethyl-1,2,4- triazol-3-yl, 2-methyl- 1,2, 3-triazol-4-yl, 1-methyl- 1,2, 3-triazol-4-yl, 2- methyl-1, 2, 4-triazol-3-yl, 1-methylimidazol-4-yl, 5-tert-butylpyridazin-3-yl and 1-methyl-1,2,3-triazol-5-yl. Still further particular values of X are 2- benzyl- 1,2, 4-triazol-3-yl, 1-benzyl- 1,2, 4-triazol- 3-yl, 1-nbutyl-1, 1,2, 4-triazol- 3-yl, 2-ethyl-1, 2, 4-triazol-3-yl, 2-methylpyrazol-3-yl, 1-methylpyrazol-3-yl, 1-npropyl-1, 1,2, 4-triazol-3-yl, 1-(2,2,2-trifluorethyl)- 1,2, 4-triazol-3-yl, 1- ethyl-1,2, 3-triazol-5-yl, 1-methyltetrazol-2-yl, imidazol-2-yl, 2-npropyl- 1,2,4-triazol-3-yl, 1-ethyl-1,2,3-triazol-4-yl, 2-ethyl-1,2,3-triazol-4-yl, 1- ethylimidazol-5-yl, 1-ethylimidazol-4-yl, 1-npropyl-1, 1,2, 4-triazol- 3-yl and 1- ethyl-1, 2, 3-triazol-5-yl.

When X is a substituted 6-membered heteroaromatic ring: Rx is preferably halogen, R3, OR3, NR4R5 or a five-membered heteroaromatic ring containing 1, 2 or 3 nitrogen atoms and more preferably methyl, CF3, methoxy, bromine, chlorine, isopropoxy, dimethylamino or a five-membered heterocyclic ring containing 1, 2 or 3 nitrogen atoms; and RY and Rz are preferably absent.

When X is a substituted 5-membered heteroaromatic ring:

Rx is preferably halogen, R3 or a pyridyl, phenyl or benzyl ring which ring is optionally independently substituted by one, two or three halogen atoms or C1-6alkyl or CF3 groups and more preferably Rx is methyl, CF3, chlorine or a phenyl, pyridyl or benzyl ring which ring is unsubstituted or substituted by chlorine or CF3; and Rr and Rz are preferably halogen or R3, and more preferably methyl, CF3 or chlorine.

Particularly aptly X is an unsubstituted six-membered heteroaromatic group containing one or two nitrogen atoms.

Apt values for Y include CH2, CH(CH3), CH2CH2 and CH2CH2CH2 optionally substituted by an oxo group, and CH2CH2O and CH2CH2CH20.

For example, Y can be CH2, CH2CH2, CH2CH2CH2, CH2CH20 or CH2CH2CH20. Preferably Y is CH2 or CH2CH2 and most preferably CH2.

From the foregoing it will be understood that particularly suitable groups L-Y-X are OCH2X groups where X is pyridyl or pyridazinyl, particularly 2-pyridyl.

Rv is suitably chlorine, R6, thienyl, furyl, pyridyl or NR7R8, more particularly R6, thienyl, furyl, pyridyl or NR7R8, for example Cl 6alkyl, C3 6cycloalkyl, hydroxyCl 6alkyl, pyridyl, thienyl or amino and more particularly methyl, ethyl, ethoxy, isopropyl, cyclopropyl, thienyl or pyridyl, and even more particularly methyl, ethyl, isopropyl, cyclopropyl, thienyl or pyridyl. A further example of RY is chlorine.

Rw is suitably R6, for example Cl.calkyl, CH2F or hydroxyCl 6alkyl, more particularly methyl, CH2F or hydroxymethyl. Generally Rw is absent.

Rx may be halogen, R3, OR3, OCOR3, NRYR5, NR4COR5, CN or R9.

Z is preferably a 5-membered heteroaromatic ring containing 1, 2 or 3 heteroatoms independently selected from oxygen, nitrogen and sulphur, at most one of the heteroatoms being oxygen or sulphur and providing that when two of the heteroatoms are nitrogen an oxygen or sulphur atom is also present and that when one of the atoms is oxygen or sulphur then at least one nitrogen atom is present, or a 6-membered heteroaromatic ring

containing 2 or 3 nitrogen atoms, Z being optionally substituted by Rv and/or Rw, where Rv is halogen, R6, NR7R8, NR7COR8, C, furyl, thienyl, phenyl, benzyl, pyridyl or a 5-membered heteroaromatic ring containing at least one nitrogen atom and optionally 1, 2 or 3 other heteroatoms independently selected from oxygen, nitrogen and sulphur, at most one of the other heteroatoms being oxygen or sulphur and Rw is R6 or CN.

Suitable values for Z include pyrimidinyl, pyrazinyl, pyrrolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, oxadiazolyl and thiadiazolyl groups which groups are optionally substituted by R6, thienyl, furyl, pyridyl or NR7R8 groups.

Z is very aptly a 5-membered heteroaromatic ring containing one oxygen and one or two nitrogen ring atoms and is optionally substituted by a group R6. In such compounds R6 is favourably a methyl group.

Favoured values for Z include optionally substituted isoxazoles and oxadiazole s.

Z may be unsubstituted.

Z may very aptly be substituted by methyl.

Particular values of Z are 3-methyloxadiazol-5-yl, 3- cyclopropyloxadiazol-5-yl, 5-methylisoaol-3-yl, 5-(3-pyridyl)-isoxazol-3- yl, 5-hydroxymethylisoxazol-3-yl, 4, 5-dimethylisoxazol- 3-yl, 5- ethylisoxazol-3-yl, 5-cyclopropylisoxazol- 3-yl, 5 -isopropylisoxazol- 3-yl, isoxazol-3-yl and S-thienylisoxazol-3-yl. Further particular values for Z include 5-fluoromethylisoxazol- 3-yl, 4-methylisoxazol- 3 -yl, 5- ethoxyisoxazol-3-yl, 4-methyl-5-chloroisoxazol-3-yl, 5- trifluoromethylisoxazol-3-yl, 5-(pyrid-2-yl)isoxazol-3-yl, 5-benzylisoxazol-3- yl, 5-chloroisoxazol-3-yl and 3-cyclopropyloxadiazol-5-yl. Still further particular values for Z include S-methoxyisoxazol-3-yl, 5- methoxymethylisoxazol- 3-yl, 5-methyloxadiazol-3-yl, pyrazin-2-yl and 3- methylisoxazol-5-yl.

R3 may be Cl 6alkyl, Cz.calkenyl, C2 6alkynyl, C3-6cycloalkyl, hydroxyCl 6alkyl or CF3.

Generally R3 is C1-6alkyl, C1-6alkoxy or CF3. In particular R3 is methyl, methoxy, ispropoxy or trifluoromethyl.

Generally R4 and R5 are independently hydrogen or C1-6alkyl, in particular hydrogen or methyl, for example both can be methyl.

R6 may be C1-6alkyl, C2 6alkenyl, C2 6alkynyl, C3 6cycloalkyl, hydroxyC1-6alkyl, C1-6alkoxy, C2-6alkenyloxy, C2-6alkynyloxy, CH2F or CF3.

Generally R6 is CH2F, CF3, C1-6alkoxy, C3-6cycloalkoxy, C1-6alkyl or hydroxyC1-6alkyl, for example, CH2F, CF3, methyl, ethyl, iospropyl, cyclopropyl or hydroxymethyl, particularly methyl or cyclopropyl.

Alternatively R6 is C1-6alkyl or hydroxyCl 6alkyl, for example, methyl, ethyl, isipropyl, cyclopropyl or hydroxymethyl.

Generally R7 and R8 are independently hydrogen or Cl 6alkyl, particularly hydrogen or methyl.

Generally R9 is pyrazolyl, imidazolyl, phenyl, benzyl or pyridyl optionally substituted by halogen, preferably chlorine, or CF3. In particular R9 can be imidazol-1-yl, 3-trifluoromethylpyrid-5-yl, benzyl and 4-chlorophenyl.

Generally R10 is C1-6alkyl or CF3, in particular methyl or CF3, for example CF3.

A preferred subclass of compounds is that represented by formula I': wherein: R1' is hydrogen or fluorine; X' is pyridyl, pyrazinyl, pyridazinyl or pyrimidinyl which is unsubstituted or substituted by methyl, CF3, methoxy, bromine, chlorine, isopropoxy, dimethylamino or a 5-membered heterocyclic ring containing 1, 2 or 3 nitrogen atoms, and X' is optionally fused to a benzene ring, or X'

is pyrazolyl, isothiazolyl, isoxazolyl, 1,2,4-triazolyl, thiazolyl, 1,2,3- triazolyl or imidazolyl any of which is unsubstituted or substituted by one, two or three groups independently chosen from methyl, CF3 and chlorine or is substituted by a phenyl, benzyl or pyridyl ring which ring is unsubstituted or substituted by chlorine or CF3, or Xis phenyl which is unsubstituted or substituted by chlorine; Y' is CH2 or CH2CH2; and Z' is an isoxazole or oxadiazole optionally substituted by CH2F, C1-6alkyl, C3-6cycloalkyl, hydroxyC1-6alkyl, pyridyl, thienyl or amino; or a pharmaceutically acceptable salt thereof.

R1' is preferably hydrogen.

X' is preferably pyridazyl or pyridyl optionally substituted by methyl, and especially 2-pyridyl.

Y' is preferably CH2.

Z' is preferably unsubstituted or substituted by methyl, CH2OH or CH2F, in particular by methyl. Z is particularly S-methylisoxazol-3-yl.

In a further preferred subclass of compounds of formula I or I', X or as as the case may be is 1,2,4-triazolyl which is unsubstituted or substituted by one, two or three groups independently chosen from methyl, CF3 and chlorine. Preferably L or L' as the case may be is 0. Preferably Y or Y' as the case may be is CH2. Preferably R1 and R2 or Rl'and R2, as the case may be are both hydrogen. Preferably Z or Z' as the case may be is 5- methylisoxazol-3-yl or 3-methylisoxazol-5-yl, and particularly 5- methylisoxazol-3-yl. More particularly the 1,2,4-triazolyl is an unsubstituted or substituted 1,2,4-triazol-3-yl. Preferably the 1,2,4- triazolyl is substituted by methyl. A particularly favoured value of X or is 1-methyl-1,2,4-triazol-3-yl.

In another preferred subclass of compounds of formula I or I', X or as as the case may be is imidazolyl which is unsubstituted or substituted by one, two or three groups independently chosen from methyl, CF3 and chlorine. Preferably L or L' as the case may be is 0. Preferably Y or Y' as

the case may be is CH2. Preferably R1 and R2 or R1' and R2' as the case may be are both hydrogen. Preferably Z or Z' as the case may be is 5- methylisoxazol-3-yl. More particularly the imidazolyl is an unsubstituted or substitutd imidazolyl-4-yl. Preferably the imidazolyl is substituted by methyl, for example it is 1-methylimidazol-4-yl.

In a further preferred subclass of compounds of formula I or I', X or as as the case may be is 1,2,3-triazolyl which is unsubstituted or substituted by one, two or three groups independently chosen from methyl, CF3 and chlorine. Preferably L or L' as the case may be is 0. Preferably Y or Y' as the case may be is CH2. Preferably R1 and R2 or R" and R2, as the case may be are both hydrogen. Preferably Z or Z' as the case may be is 5- methylisoxazol-3-yl. More particularly the 1,2,3-triazolyl is an unsubstituted or substituted 1,2,3 -triaz6l-4-yl. Preferably the 1,2,3- triazolyl is substituted by methyl. A particularly favoured value of X or is 1-methyl-1, 2, 3-triazol-4-yl.

For use in medicine, the salts of the compounds of formula I will be pharmaceutically acceptable salts. Hence in a favoured aspect this invention provides the compounds of the formula I and pharmaceutically acceptable salts thereof. Other salts may, however, be useful in the preparation of the compounds according to the invention or of their pharmaceutically acceptable salts. Suitable pharmaceutically acceptable salts of the compounds of this invention include acid addition salts which may, for example, be formed by mixing a solution of the compound according to the invention with a solution of a pharmaceutically acceptable acid such as hydrochloric acid, sulphuric acid, methanesulphonic acid, fumaric acid, maleic acid, succinic acid, acetic acid, benzoic acid, oxalic acid, citric acid, tartaric acid or phosphoric acid. Furthermore, where the compounds of the invention carry an acidic moiety, suitable pharmaceutically acceptable salts thereof may include alkali metal salts, e.g. sodium or potassium salts; alkaline earth metal salts, e.g. calcium or

magnesium salts; and salts formed with suitable organic ligands, e.g. quaternary ammonium salts.

Where the compounds according to the invention have at least one asymmetric centre, they may accordingly exist as enantiomers. Where the compounds according to the invention possess two or more asymmetric centres, they may additionally exist as diastereoisomers. It is to be understood that all such isomers and mixtures thereof in any proportion are encompassed within the present invention.

It will be understood by the skilled person that when a five- membered heterocyclic ring is referred to in the foregoing having four heteroatoms in the ring, then all these heteroatoms are nitrogen. It will further be understood that when a substituted five-membered heterocyclic ring is referred to having two nitrogen atoms and an oxygen or sulphur atom in the ring, then only one substituent may be present so that aromaticity is maintained. Thus, for example, in such a case X may only be substituted by Rx and Z may only be substituted by RY.

Specific compounds within the scope of the present invention include: 3-(5-Methylisoxazol-3-yl)-6-(2-pyridyl)methyloxy-1,2,4-triaz olo[3,4- <BR> <BR> <BR> a]phthalazine, <BR> <BR> <BR> 3-(S-Methylisoxazol-3-yl)-6-(6-methylpyridin-2-yl)methyloxy- 1,2,4- triazolo[3,4-a]phthalazine, 3-(5-Methylisoxazlo-3-yl)-6-(3-pyridyl)methyloxy-1,2,4-triaz olo[3,4- <BR> <BR> <BR> a]phthalazine, <BR> <BR> <BR> 3-(5-Methylisoxazol-3-yl)-6-(4-pyridyl)m 1,2, 4-triazolo [3,4- a]phthalazine, 6-(3, 5-Dimethylpyrazol- 1 -yl)methyloxy-3-(S-methylisoxazol-3-yl)- 1,2,4- triazolo[3,4-a]phthalazine, 6(3-Methoxypyridin-2-yl)methyloxy-3-(5-methylisoxazol-3-yl)- 1,2,4- triazolo [3,4-a]phthalazine,

6-(5-Methylisoxazol-3-yl)methyloxy-3-(5-methylisoxazol-3-yl) -1,2,4- triazolo[3,4-a]phthalazine, 3-(5-Methylisoxazol-3-yl)-6-(pyrazol-1-yl)methyloxy-1,2,4- trizaolo[3,4-a]phthalazine, 6-(6-Chloropyridin-2-yl)methyloxy-3-(5-methylisoxazol-3-yl)- 1,2,4- trizaolo[3,4-a]phthalazine, 6-(6-Brompyridin-2-yl)methyloxy-3-(5-methylisoxazol-3-yl)-1, 2,4- triazolo [3, 4-a]phthalazine, 6-(6-Methoxypyridin-2-yl)methyloxy-3-(5-methylisoxazol-3-yl) -1,2,4- trizaolo[3,4-a]phthalazine, 6-(6-Isopropoxypyridin-2-yl)methyloxy-3-(5-methylisoxazol-3- yl)-1,2,4- triazolo [3, 4-a]phthalazine, 6-(6-N,N-Dimethylpyridin-2-yl)methyloxy-3-(5-methylisoxazol- 3-yl)-1,2,4- triazolo [3, 4-a]phthalazine, 6-[6-(Imidazol-1-yl)pyridin-2-yl]methyloxy-3-(5-methylisoxaz ol-3-yl)-1,2,4- trizaolo[3,4-a]phthalazine, 3- (5-Methylisoxazol- 3 -yl)-6- (3-pyridazino)methyloxy- 1,2,4- triazolo [3, 4-a]phthalazine, 3-(5-Methylisoxazol-3-yl)-6-(4-pyrimidinyl) 1,2,4- triazolo [3,4-a]phthalazine, 3-(5-Methylisoxazol-3-yl)-6-(pyrazin-2-yl) methyloxy-1, 1,2,4- triazolo [3, 4-a]phthalazine, 3- (5-Methylisoxazol-3-yl)-6-(2-quinolinyl) 1,2,4- trizaolo[3,4-a]phthalazine, 3-(5-Methylisoxazol-3-yl)-6-(2-quinoxalyl)methyloxy-1,2,4- triazolo [3,4-a]phthalazine, 3-(5-Methylisoazol-3-yl)-6-(2-(4-trifluoromethyl)pyridyloxy) ethyloxy-1,2,4 trizaolo[3,4-a]phthalazine, 3-(S-Methylisoxazol-3-yl)-6- (6-methylpyrid-2-yl)propyloxy- 1,2,4- triazolo [3,4-a]phthalazine,

3-(5-Methylisoxazol-3-yl)-6-(5-(4-methylisothiazolyl)ethylox y-1,2,4- trizaolo[3,4-a]phthalazine, <BR> <BR> <BR> <BR> <BR> <BR> 3-(5-Methylisoxazol-3-yl)-6-(2,6-dichlorophenyl)methyloxy-1, 2,4-triazolo-<BR> phthalazine, 3-(5-Methylisoxazol-3-yl)-6-(4-methylthiazol-5-yl)ethyloxy-1 ,2,4- triazolo- [3,4-a]phthalazine, 3-(5-Methylisoxazol-3-yl)-6-(2-methylthiazol-4-yl) 1,2,4- triazolo- [3,4-a]phthalazine, 3-(5-Methylisoxazol-3-yl)-6-(4-methylthiazol-5-yl)ethyloxy-1 ,2,4- yl]imidazolyl)methyloxy-1,2,4-triazolo[3,4-a]phthalazine 3-(5-Methylisoxazol-3-yl)-6-[(1-benzyl)imidazol-2-yl]methylo xy-1,2,4- triazolo [3, 4-a]phthalazine, 3-(5-Methylisoxazol-3-yl)-6- [1 -(4-chlorophenyl)- 1,2, 3-triazol-4- yl] methyloxy- 1,2, 4-triazolo [3,4- a]phthalazine, 3-(5-methylisoxazol-3-yl)-6-(3-chloro-2-methyl-5-trifluorome thylpyrazol-4- yl)methyloxy- 1,2, 4-triazolo [3,4- a]phthalazine, 3-(5-Isopropylisoxazol-3-yl)-6-(2-pyridyl)methyloxy-1,2,4-tr iazolo[3,4- a]phthalazine, 3-(5-Cyclopropylisoxazol-3-yl)-6-(2-pyridyl)methyloxy-1,2,4- triazolo[3,4- a]phthalazine, 3-(5-Ethylisoxazol-3-yl)-6-(2-pyridyl)methyloxy-1,2,4-triazo lo[3,4- a]phthalazine, 3-(4,5-Dimethylisoxazol-3-yl)-6-(2-pyridyl)methyloxy-1,2,4-t riazolo[3,4- a]phthalazine, 3-(3-Isoxazolyl)-6-(2-pyridyl)methyloxy-1,2,4-triazolo[3,4-a ]phthalazine,.

3-[5-(Pyridin-3-yl)isoxazol-3-yl]-6-(2-pyridinyl)methyloxy-1 ,2,4- triazolo [3, 4-a]phthalazine, 6- (2-Pyridyl)methyloxy-3- [5- (2-thienyl)isoxazol-3-yl] -1,2,4-triazolo [3,4- a]phthalazine, 3-(5-Methylisoxazol-3-yl)-6-(l-methyl- 2, 4-triazol-3-yl) methyloxy- 1,2,4-triazol[3,4-a]phthalazine,

7,10-Difluoro-3-(5-methylisoxzaol-3-yl)-6-(2-pyridyl)methyly oxy- 1,2,4-triazolo[3,4-a]phthalazine, 6,10-Bis[(2-pyridyl)methyloxy]-3-(5-methylisoxazol-3-yl)- 1,2,4-triazolo[3,4-a]phthalazine, 7-Fluoro-3-(5-methylisoxazol-3-yl)-6-(2-pyridyl)methlyoxy- 1,2,4-triazolo[3,4-a]phthalazine, 10-Fluoro-3-(5-methylisoxazol-3-yl)-6-(2-pyridyl)methyloxy- 1,2,4-triazolo[3,4-a]phthalazine; and the pharmaceutically acceptable salts thereof.

Further specific compounds within the scope of the present invention include: 6-(1-methylimidazol-4-yl)nmethyloxy-3-(5-methylisoxazol-3-yl )-1,2,4- triazolo[3, 4-a]phthalazine; 6-(1-methylimidazol-5-yl)methyloxy-3-(5-methylisoxazol-3-yl) - 1,2,4-triazolo[3,4-a]phthalazine; 3-(5-methylisoxazol-3-yl)-6-(2-methyl-1,2,4-triazol-3-yl)met hyloxy-1,2,4- triazolo[3,4-a]phthalazine; 3-(5-methylisoxazol-3-yl)-6-(4-methyl-1,2,4-triazol-3-yl)met hyloxy-1,2,4- triazolo [3, 4-a]phthalazine; 3-(5-methylisoxazol-3-yl)-6-[2-{[2-(trimethylisilyl)ethoxy]m ethyl}-1,2,4- triazolyl]emthyloxy-1,2,4-triazolo[3,4-a]phthalazine; 3-(5-methylisoxazol-3-yl)-6-(1 2, 4-triazol-3-yl)methyloxy- 1,2,4- triazolo [3, 4-a]phthalazine; 3-(5-methylisoxazol-3-yl)-6-(1-isopropyl-1,2,4-triazol-3-yl) methyloxy-1,2,4- triazolo[3,4-a]phthalazine; 3-(5-methylisoxazol-3-yl)-6-(-1-ethyl-1,2,4-triazol-3-yl)met hyloxy-1,2,4- triazolo[3,4-a]phthalazine; 3-(5-methylisoxazol-3-yl)-6-(1H- 1,2,3-triazol-5-yl)methyloxy- 1,2,4- -triazolo[3,4-a]phthalazine; <BR> <BR> <BR> 3-(5-methylisoxazol-3-yl)-6-(l-methyl- 1,2,3-triazol-5-yl)methyloxy- 1,2,4- triazolo[3,4-a]phthalazine;

3-(5-methylisoxazol-3-yl)-6-(2-methyl- 1,2, 3-triazol-4-yl)methyloxy- 1,2,4- triazolo[3,4-a]phthalazine; 3-(5-methylisoxazol-3-yl)-6-(1methyl-1,2,3-triazol-4-yl)meth yloxy-1,2,4- triazolo[3,4-a]phthalazine; 3-(5-methylisoxazol-3-yl)-6-[(5-terifluoromethyl)pyridin-2-y l]methyloxy- 1,2,4-triazolo[3,4-a]phthalazine; 3-(5-methylisoxazol-3-yl)-6-[(3-trifluoromethyl)pyridin-2-yl ]methyloxy- 1,2,4-triazolo[3,4-a]phthalazine; 3-(5-methylisoxazol-3-yl)-6-[(4-trifluoromethyl)pyridin-2-yl ]methyloxy- 1,2,4-triazolo[3,4-a]phthalazine; 3-(5-methylisoxazol-3-yl)-6-(thiazol-4-yl)-1,2,4-triazolo[3, 4-a]phthalazine; 3-(isothiazol-3-yl)methyloxy-3-(5-methylisoxazol-3-yl)-1,2,4 - triazolo[3,4-a]phthalazine; 3-(4-methylisoxazol-3-yl)-6-[(4-tert-butyl)pyridazin-3-yl]me thyloxy-1,2,4- triazolo[3, 4-a]phthalazine; 3-(5-methylisoxazol-3-yl)-6- [(5-tert-butyl)pyridazin-3-yl]methyloxy- 1,2,4- triazolo [3,4-a]phthalazine; 6-(imidazol-4-yl) methyloxy-3- (5-methylisoxazol-3-yl)-1, 1,2,4- triazolo[3,4-a]phthalazine; 3-[(5-methylisoxazol-3-yl)-6-(1-methyl-1,2,4-triazol-3-yl)me thylamino- 1,2,4-triazolo[3,4-a]phthalazine; 3-(5-methylisoxazol-3-yl)-6-{(N-methyl), N- [(1-methyl- 1,2,4-triazol-3- yl)methyl]amino}-1,2,4-triazolo[3,4-a]phthalazine; 3-(5-isoxazol-3-yl)-6-(1-methyl-1,2,4-triazol-3-yl)methyloxy -1,2,4- triazolo[3,4-a]phthalazine; <BR> <BR> <BR> <BR> 3- (3-isoxazolyl)-6- (2-methyl-1, 2, 2,4-triazol-3-yl)methyloxy- 1,2,4- <BR> <BR> <BR> <BR> <BR> triazolo [3 4-a]phthalazine; 3-(3-isoxazolyl)-6-(1-methylimidazol-4-yl)methyloxy-1,2,4- triazolo [3. 4-a]phthalazine; 3-(5-methylisoxazol-3-yl)-6-(2-pyridyl)methyloxy-1,2,4-traiz olo- [3,4-a]phthalazine;

3-(5-hydroxymethylisoxazol-3-yl)-6-(1-methyl-1,2,4-triazol-3 -yl)methyloxy- 1,2,4-triazolo[3,4-a]phthalazine; 3-(5-fluoromethylisoxzaol-3-yl)-6-(2-pyridyl)methyloxy-1,2,4 - triazolo[3,4-a]phthalazine; 3-(5-fluoromethylisoxazol-3-yl)-6-(1-methyl-1,2,4-triazol-3- yl)methyloxy- 1,2,4-triazolo[3,4-a]phthalazine; 3-(5-fluoromethylisoxazol-3-yl)-6-(1-methyl-1,2,4-triazol-5- yl)methyloxy- 1,2,4-triazolo[3,4-a]phthalazine; 3-(5-fluoromethylisoxazol-3-yl)-6-(1,2,4-triazol-3-yl)methyl oxy-1,2,4- triazolo [3, 4-a]phthalazine; 3- (5-ethoxyisoxazol-3-yl)-6- (2-pyridyl) methyloxy-1, 1,2,4- triazolo [3, 4-ajphthalazine; 3-(5-ethoxyisoxazol-3-yl)-6-(1-methyl-1,2,4-triazol-3-yl)met hyloxy-1,2,4- triazolo[3,4-a]phthalazine; 3-(5-ethoxyisoxazol-3-yl)-6-(2-methyl-1,2,4-triazol-3-yl)met hyloxy-1,2,4- triazolo[3,4-a]phthalazine; 3-(5-ethoxyisoxazol-3-yl)-6-(1,2,4-triazol-3-yl)methyloxy-1, 2,4- triazolo [3,4-a]phthalazine; 3-(5-ethoxyisoxazol-3-yl)-6-(1-methylimidazol-4-yl) methyloxy- 1,2,4- triazolo[3,4-a]phthalazine; 3-(5-chloroisoxazol-3-yl)-6- (2-pyridyl) methyloxy-1, 1,2,4- triazolo [3, 4-a]phthalazine; 3-(5-chloroisoxazol-3-yl)-6-(1-methyl-1,2,4-triazol-3-yl)met hyloxy-1,2,4- triazolo[4, 3-a]phthalazine; 3-(5-chloroisoxazol-3-yl)-6-(2-methyl-1,2,4-triazol-3-yl)met hyloxy-1,2,4- triazolo[4, 3-a]phthalazine; 3-(5-chloroisoxazol-3-yl)-6-(1-methylimidazol-4-yl)methyloxy -1,2,4- triazolo[3,4-a]phthalazine;<BR> <BR> <BR> <BR> <BR> <BR> <BR> 3-(5-methylisoxazol-3-yl)-6-(1,2,4-triazol-3-yl)methyloxy-1, 2,4-triazolo[3,4-<BR> <BR> <BR> <BR> <BR> <BR> <BR> a]phthalazine;

3-(5-chloroisoxazol-3-yl)-6-(1-methylimidazol-5-yl)methyloxy -1,2,4- triazolo[3,4-a]phthalazine; <BR> <BR> <BR> <BR> <BR> <BR> <BR> 3-(5-chloroisoxazol-3-yl)-6-(4-methyl-1,2,4-triazol-3-yl)met hyloxy-1,2,4-<BR> triazolo[3,4-a]phthalazine; 6-(2-pyridylmethyloxy)-3-(5-trifluoromethylisoxazol-3-yl)-1, 2,4-triazolo[3,4- a]phthalazine; 3-(5-phenylmethylisoxazol-3-yl)-6-[(2-pyridyl)methyloxy]-1,2 ,4-triazolo[3,4- a]phthalazine; 3- [5-(2-pyridyl)isoxazol-3-yl] -6-(2-pyridyl)methyloxy- 1,2, 4-triazolo [3,4- <BR> <BR> <BR> <BR> a]phthalazine; <BR> <BR> <BR> <BR> <BR> <BR> <BR> 3-(4-methylisoxazol-3-yl)-6-(2-pyridyl)m 1,2, 4-triazolo [3,4- -a]phthalazine; 3-(5-chloro-4-methylisoxazol-3-yl)-6-(2-pyridyl) methyloxy-1, 1,2,4- triazolo [3, 4-a]phthalazine; 3-(3-methyloxadiazol-5-yl)-6-(2-pyridyl)methyloxy-1,2,4-tria zolo[3,4- a]phthalazine; 3-(3-cyclopropyloxadiazol-5-yl)-6-(2-pyridyl) 1,2, 4-triazolo [3,4- -a]phthalazine; and the pharmaceutically acceptable salts thereof.

Still further specific compounds within the scope of the present invention are: 3-(3-Methyl- 1,2,4-oxadiazol-5-yl)-6-(l-methyl- 1,2, 4-triazol-3-yl)methyloxy- 1,2,4-triazolo[3,4-a]phthalazine; 6-(1-Benzyl-1,2,4-triazol-3-yl)-3-(5-methylisoxazol-3-yl)mth yloxy-1,2,4- triazolo[3,4-a]phthalazine and 6-(2-Benzyl-1,2,4-triazol-3-yl)-3-(5- methylisoxazol-3-yl)methyloxy-1,2,4-triazolo[3,4-a]phthalazi ne; 6-(1-Butyl-1,2,4-triazol-3-yl)-3-(5-methylisoxazol-3-yl)meth yloxy-1,2,4- triazolo[3,4-a]phthalazine; 6-(2-Ethyl-1,2,4-triazol-3-yl)-3-(5-methylisoxazol-3-yl)meth yloxy-1,2,4- triazolo [3,4-a]phthalazine;

3-(5-Methylisoxazol-3-yl)-6-(1-propyl-1,2,4-triazol-3-yl)met hyloxy-1,2,4- triazolo[3,4-a]phthalazine; 3-(5-Methylisoxazol-3-yl)-6- [1-(2,2, 2-trifluoroethyl)- 1,2,4-triazol-3- yl]methyloxy-1,2,4-triazolo[3,4-a]phthalazine; 6-(1-Ethylimidazol-5-yl)methyloxy-3-(5-methylisoxazol-3-yl)- 1,2,4- triazolo[3,4-a]phthalazine; 6-(1-Ethylimidazol-4-yl)methyloxy-3-(5-methylisoxazol-3-yl)- 1,2,4- triazolo[3, 4-a]phthalazine; <BR> <BR> <BR> <BR> 6-(1-Ethyl- 1,2, 3-triazol-5-yl) methyloxy-3-(5-methylisoxazol-3-yl)-1, 1,2,4- triazolo[3, 4-a]phthalazine; 6-(1-Ethyl-1,2,3-triazol-4-yl)methyloxy-3-(5-methylisoxazol- 3-yl)-1,2,4- triazolo[3,4-a]phthalazine; <BR> <BR> <BR> <BR> 6- (2-Ethyl- 1,2, 3-triazol-4-yl) methyloxy-3-(5-methylisoxazol-3-yl)-1, 1,2,4- triazolo [3, 4-a]phthalazine; 3-(5-Methylisoxazol-3-yl)-6-(1-methylisoxazol-5-yl)methyloxy -1,2,4- <BR> <BR> <BR> <BR> triazolo [3,4-a] phthalazine; <BR> <BR> <BR> <BR> <BR> <BR> 6-(Imidazol-2-yl) methyloxy-3-(5-methylisoxazol-3-yl)-1, 1 ,2,4-triazolo [3,4- <BR> <BR> <BR> <BR> <BR> <BR> a]phthalazine; 3-(5-Methylisoxazol-3-yl)-6-(2-methylpyrazol-3-yl)methyloxy- 1,2,4- triazolo[3,4-a]phthalazine; 3- (5-Methylisoxazol-3-yl)-6-(1-methylpyrazol-3-yl) 1,2,4- triazolo [3,4-a]phthalazine; 3-(S-Methylisoxazol-3-yl)-6- (1-methylpyrazol-4-yl)methyloxy- 1,2,4- triazolo[3,4-a]phthalazine; 3-(5-Ethylisoxazol-3-yl)-6-(20methyl-1,2,4-triazol-3-yl)meth yloxy-1,2,4- triazolo[3,4-a]phthalazine; 3-(5-Ethylisoxazol-3-yl)-6-(1-methyl-1,2,4-triazol-3-yl)meth yloxy-1,2,4- triazolo[3,4-a]phthalazine; 3-(5-Ethylisoxazol-3-yl)-6-(pyrazin-2-yl)methyloxy-1,2,4-tri azolo[3,4- a]phthalazine;

6-(1-Ethyl-1,2,3-triazol-4-yl)methyloxy-3-(3-isoxazolyl)-1,2 ,4-triazolo[3,4- a]phthalazine; <BR> <BR> <BR> <BR> <BR> <BR> <BR> 6-(1-Ethyl-1,2,4-traizol-3-yl)methyloxy-3-(3-isoxazolyl)-1,2 ,4-triazolo[3,4-<BR> a]phthalazine; 6-(1-Ethyl-1,2,3-triazol-5-yl)methyloxy-3-(3-isoxazolyl)-1,2 ,4-triazolo[3,4- a]phthalazine; 6-(1-Ethylimidazol-4-yl)-4-(3-isoxazoly)methyloxy-1,2,4-tria zolo[3,4- a]phthalazine; 6-(2-Ethyl-1,2,4-triazol-3-yl)-3-(3-isoxazolyl)methyloxy-1,2 ,4-triazolo[3,4- a]phthalazine; 3-(3-Isoxazolyl)-6-(2-propyl-1,2,4-triazol-3-yl)methyloxy-1, 2,4-triazolo[3,4- <BR> <BR> <BR> <BR> a]phthalazine; <BR> <BR> <BR> <BR> <BR> <BR> <BR> 3-(3-Isoxazolyl)-6-(1-propyl-1, 1,2,4-triazol-3-yl)methyloxy- 1,2, 4-triazolo [3,4- <BR> <BR> <BR> <BR> <BR> <BR> a]phthalazine; <BR> <BR> <BR> <BR> <BR> <BR> <BR> 6-(1-Benzylimidazol-2-yl) methyloxy-3-(3-isoxazolyl)-1, 1,2,4-triazolo[3 '4- a]phthalazine; 3-(5-Methylisoxazol-3-yl)-6-(1-methyl-1,2,4-triazol-3-yl)met hyloxy- 1,2,4-triazolo[3,4-a]phthalazine; 3-(5-Methylisoxazol-3-yl)-6-(2-methyl-1,2,4-triazol-3-yl)met hyloxy- 1,2,4-triazolo[3,4-a]phthalazine; 3-(5-Methylisoxazol-3-yl)-6-(1-methylimidazol-4-yl)methyloxy -1,2,4- triazolo [3,4-a]phthalazine; 3-(5-methylisoxazol-3-yl)-6-(1-methyl-1,2,4-triazol-3-yl)met hyloxy-1,2,4- triazolo[3,4-a]phthalazine; 3-(3-Methylisoxazol-5-yl)-6-(2-pyridyl)methyloxy-1,2,4-triaz olo[3,4- a]phthalazine; 3-(3-Methylisoxazol-5-yl)-6-(6-methylpyridin-2-yl)methyloxy- 1,2,4- triazolo[3,4-a]phthalazine; 3- (3-Methylisoxazol- 5-yl)-6- (pyrazin-2-yl)methyloxy- 1,2,4-triazolo [3,4- a]phthalazine;

3-(3-Methylisoxazol-5-yl)-6-(2-methyl-1,2,4-triazol-3-yl)met hyloxy-1,2,4- triazolo[3,4-a]phthalazine; <BR> <BR> <BR> <BR> <BR> <BR> <BR> 3-(3-methylisoxazol-5-yl)-6-(1-methyl-1,2,4-triazol-3-yl)met hyloxy-1,2,4-<BR> triazolo[3,4-a]phthalazine; 3-(3-Ethoxyisoxazol-5-yl)-6-(1-methyl-1,2,4-triazol-3-yl)met hyloxy-1,2,4- triazolo [3,4-a]phthalazine; 6-(2-Methyl-1,2,4-triazol-3-yl)methyloxy-3-(pyrazin-2-yl)-1, 2,4-triazolo[3,4- a]phthalazine; 3-(Pyrazin-2-yl)-6-(pyrid-2-yl)methyloxy-1,2,4-triazolo[3,4- a]phtahalazine; 3-(S-Methyl- 1,2,4-oxadiazol-3-yl)-6-(l-methyl- 1,2,4-triazol-3-yl)methyloxy- 1 ,2,4-triazolo [3, 4-a]phthalazine; and the pharmaceutically acceptable salts thereof.

Particularly favoured compounds are: 3-(5-methylisoxazol-3-yl)-6-(2-pyridyl) methyloxy-1, 1,2, 4-triazolo [3,4- a]phthalazine and <BR> <BR> <BR> <BR> 3-(5-methylisoxazol-3-yl)-6-(3-pyridazinyl) methylOxy-1, 1,2, 4-triazolol[3, 4- <BR> <BR> <BR> <BR> <BR> <BR> <BR> a]phthalazine or pharmaceutically acceptable salts thereof.

An especially favoured compound is 3-(5-methylisoxazol-3-yl)-6-(2- pyridyl)methyloxy-1,2,4-traiazololo[3,4-a]phthalazine or a pharamaceutically acceptable salt thereof.

Another especially favoured compound is 3- (5-methylisoxazol- 3-yl)- 6-(1-methyl- 1,2,4-triazol-3-yl)methyloxy- 1,2,4-triazolo[3,4-a[phthalazine or a pharmaceutically acceptable salt thereof.

Another especially favoured compound is 3- (5 -methylisoxazol- 3-yl) - 6-(1-methylinidazol-4-yl)methyloxy-1,2,4-triazolo[3,4-a]phth alazine or a pharmaceutically acceptable salt thereof.

Another especially favoured compound is 3-(5-methylisoxazol-3-yl)- 6-(1 -methyl- 1,2, 3-triazol-4-yl)methyloxy- 1,2,4-triazolo [3,4-a]phthalazine or a pharmaceutically acceptable salt thereof.

Another especially favoured compound is 3-(3-methylisoxazol-5-yl)- 6-(1-methyl-1,2,4-triazol-3-yl)methyloxy-1,2,4-triazolo[3,4- a]phthalazine or a pharmaceutically acceptable salt thereof.

Examples of pharmaceutically acceptable salts are hydrochlorides, sulfates, citrates, tartrates, acetates, methanesulfonates, phosphates, oxalates and benzoates.

The compounds of the present invention have a good binding affinity (Ki) for the a5 subunit. In a preferred embodiment the compounds of the invention are binding selective for the a5 subunit relative to the al, a2 and a3 subunits. In another preferred embodiment the compounds are functionally selective for the a5 subunit as partial or full inverse agonists whilst substantially being antagonists at the al, a2 and a3 subunits.

Cognition enhancement can be shown by testing the compounds in the Morris watermaze as reported by McNamara and Skelton, Psychobiology, 21:101-108. The functional efficacy at the various receptor subtypes can be calculated using the method disclosed in WO-A-9625948.

The invention also provides pharmaceutical compositions comprising one or more compounds of this invention and a pharmaceutically acceptable carrier. Preferably these compositions are in unit dosage forms such as tablets, pills, capsules, powders, granules, sterile parenteral solutions or suspensions, metered aerosol or liquid sprays, drops, ampoules, transdermal patches, auto-injector devices or suppositories; for oral, parenteral, intranasal, sublingual or rectal administration, or for administration by inhalation or insufflation. For preparing solid compositions such as tablets, the principal active ingredient is mixed with a pharmaceutical carrier, e.g. conventional tableting ingredients such as corn starch, lactose, sucrose, sorbitol, talc, stearic acid, magnesium stearate, dicalcium phosphate or gums or surfactants such as sorbitan monooleate, polyethylene glycel, and other pharmaceutical diluents, e.g. water, to form a solid preformulation composition containing a homogeneous mixture of a compound of the

presen invention, or a pharmaceutically acceptable salt thereof. When referring to these preformulation compositions as homogeneous, it is meant that the active ingredient is dispersed evenly throughout the composition so that the composition may be readily subdivided into equally effective unit dosage forms such as tablets, pills and capsules.

This solid preformulation composition is then subdivided into unit dosage forms of the type described above containing from 0.1 to about 500 mg of the active ingredient of the present invention. Typical unit dosage forms contain from 1 to 100 mg, for example 1, 2, 5, 10, 25, 50 or 100 mg, of the active ingredient. The tablets or pills of the novel composition can be coated or otherwise compounded to provide a dosage form affording the advantage of prolonged action. For example, the tablet or pill can comprise an inner dosage and an outer dosage component, the latter being in the form of an envelope over the former. The two components can be separated by an enteric layer which serves to resist disintegration in the stomach and permits the inner component to pass intact into the duodenum or to be delayed in release. A variety of materials can be used for such enteric layers or coatings, such materials including a number of polymeric acids and mixtures of polymeric acids with such materials as shellac, cetyl alcohol and cellulose acetate.

The present invention also provides a compound of the invention for use in a method of treatment of the human body. Preferably the treatment is for a condition associated with GABAA receptors comprising the a5 subunit and/or for the enhancement of cognition. Preferably the condition is a neurological deficit with an associated cognitive disorder such as a dementing illness such as Alzheimer's disease. Other conditions to be treated include cognition deficits due to traumatic injury, stroke, Parkinson's disease, Downs syndrome, age related memory deficits, attention deficit disorder and the like.

Thus, for example, the compounds of the present invention can be used in a variety of disorders of the central nervous system. Such

disorders include delirium, ementia and amnestic and other cognitive disorders. Examples of delirium are delirium due to substance intoxication or substance withdrawal, delirium du to multiple etiologies and delirium NOS (not otherwise specified). Exam,ples of dementia are: dementia of the Alzheimer's type with early onset which can be uncomplicated or with delirium, delusions or depressed mood; dementia of the Alzheimer's type, with late onset, which can be uncomplicated or with delirium, delusions or depressed mood; vascular dementia which can be uncomplicated or with delirium, delusions or depressed mood; dementia due to HIV disease; dementia due to head trauma; dementia due to Parkinson's disease; dementia due to Huntington's disease; dementia due to Pick's disease; dementia due to Creutzfeld-Jakob disease; dementia which is substance-induced persisting or due to multiple etiologies; and dementia NOS. Examples of amnestic disorders are amnestic disorder due to a particular medical condition or which is substance-induced persisting or which is amnestic disorder NOS.

Those compounds which are not inverse agonists at the a5 subtype may be used as alcohol antagonists or to treat obesity.

The present invention further provides the use of a compound of the present invention in the manufacture of a medicament for the enhancement of cognition, preferably in a human suffering from a dementing illness such as Alzheimer's disease.

Also disclosed is a method of treatment of a subject suffering from a cognition deficit, such as that resulting from a dementing illness such as Alzheimer's disease, which comprises administering to that subject an effective amount of a compound according to the present invention.

The liquid forms in which the novel compositions of the present invention may be incorporated for administration orally or by injection include aqueous solutions, suitably flavoured syrups, aqueous or oil suspensions, and flavoured emulsions with edible oils such as cottonseed oil, sesame oil, coconut oil or peanut oil, as well as elixirs and similar

pharmaceutical vehicles. Suitable dispersing or suspending agents for aqueous suspensions include synthetic and natural gums such as tragacanth, acacia, alginate, dextran, sodium carboxymethylcellulose, methylcellulose, polyvinyl-pyrrolidone or gelatin.

For the enhancement of cognition, a suitable dosage level is about 0.01 to 250 mg/kg per day, preferably about 0.01 to 100 mg/kg per day, and especially about 0.01 to 5 mg/kg of body weight per day. The compounds may be administered on a regimen of 1 to 4 times per day. In some cases, however, dosage outside these limits may be used.

It is preferred that the compounds of the present invention are ground, for example using a pestle and mortar or industrial equivalent thereto, to a particle size of between 1 and 10 uM, and preferably less than 5 pM, before formulation. The compounds may be micronised or sonicised by methods known in the art or nanonised, for example by methods disclosed in US-A-5145684.

The compounds in accordance with the present invention may be prepared by a process which comprises reacting a compound of formula III with a compound of formula IV: wherein R1, R2, X and Y are as defined above, G is a leaving group such as chlorine, OCH2CF3 or para-sulphonyltoluene, B is LH where L is as defined above and Z1 is a group Z as defined above or is a moiety which can be converted into a group Z by further reaction.

Compounds of formula III represent a further feature of the present invention. The groups Z which are preferred for compounds of formula I are preferred for these compounds likewise.

The reaction between compounds III and IV when L is O is conveniently effected by stirring the reactants in a suitable sovent, typically N,N-dimethylformamide, in the presence of a strong base such as sodium hydride or lithium bis(trimethylsilyl)amide, typically without heating and under an inert atmosphere such as nitrogen. When L is NRn the reaction is conveniently effected in the presence of a strong base such as Et3N or NaH and a solvent such as DMF or DMSO generally for 15 to 60 hours with heating to 50-120°C.

The intermediates of formula III above may be prepared by reacting a compound of formula V, which constitutes a further feature of the present invention, with a compound of formula VI: wherein R1, R2, G and Z1 are defined above, and W represents a suitable leaving group such as C1-6alkoxy, chlorine or hydroxy.

The reaction is advantageously conducted in an inert organic solvent, generally in the presence of an organic nitrogen base and preferably under an inert atmosphere such as nitrogen. Suitable solvents include xylene, dioxane, tetrahydrofuran and lower aliphatic halogenated and aromatic hydrocarbons. Suitable organic nitrogen bases that may be employed include trialkylamines and pyridine. The reaction is generally conducted at a temperature range of from -20°C to the reflux temperature of the reaction mixture, for a period of time that depends on the reactants employed and the temperature at which the reaction is carried out. The compound of formula VI may be activated by reacting with a compound such as bis (2-oxo-3-oxazolidinyl)phosphinic chloride or 1,1'-dicarbnyldiimidzole before reaction with the hydrazine.

When Z1 is not a group Z, it is, for example, an allylformyloxime group which can be converted to a carboxaldehydeoxime using tetrakis(triphenylphosphine)palladium(0) generally under an inert atmosphere such as nitrogen in the presence of triethylammonium formate, in a solvent such as ethanol for about 18 hours. The carboxaldehydeoxime can be converted to a carboxaldehydechloroxime by reacting with a chlorinating agent such as N-chlorosuccinimide in a solvent such as DMF. The carboxaldehydechloroxime can be converted to the desired group Z by reacting with an unsaturated compound such a vinylidene chloride, methyl propargyl ether, 3-phenyl- 1-propyne, 2- pyridylacetylene, trifluoromethylacetylene or ethoxyacetylene generally in the presence of a base such a triethylamine, and a solvent such as dichloromethane. Alternatively, the carboxaldehydechloroxime can be converted to a group Z by reacting with ammonium hydroxide generally in a solvent such as ethanol for about 30 minutes and then acetic anhydride generally with heating to reflux for about 16 hours.

The reaction is advantageously conducted in an inert organic solvent, generally in the presence of an organic nitrogen base and preferably under an inert atmosphere such as nitrogen. Suitable solvents include xylene, dioxane, tetrahydrofuran and lower aliphatic halogenated and aromatic hydrocarbons. Suitable organic nitrogen bases that may be employed include trialkylamines and pyridine. The reaction is generally conducted at a temperature range of from -20"C to the reflux temperature of the reaction mixture, for a period of time that depends on the reactants employed and the temperature at which the reaction is carried out. The compound of formula VI may be activated by reacting with a compound such as bis (2-oxo-3-oxazolidinyl)phosphinic chloride or 1,1 '-dicarbonyldiimidazole before reaction with the hydrazine.

Compounds of formula III in which G is OCH2CF3 can be prepared by reacting a compound of formula III in which G is chlorine with 2,2,2- trifluoroethanol in the presence of a base such as lithium

bis(trimethylsilyl)amide generally in a solvent such as DMF, preferably with cooling to about -20°C-0°C for a period of about 30 minutes.

The compound of formula V is prepared by reaction of a compound of formula VII: where R1, R2 and G are as defined above, and G' is another suitable leaving group whicuh may be the same as or different to G, with hydrazine, usually in the form of its monohydrate, generally in a solvent such as ethanol and gnerally by refluxing for a suitable period such as 15 minutes to 2 hours.

When the compound of formula VII is asymmetrical, that is R1 and R2 are different or if they are the same, the substitution pattern about the fused benzene ring is not symmetrical, the reaction between this compound and hydrazine will usually give rise to a mixture of isomeric products depending on whether group G or G' is displaced first. Thus in addition to the required product of formula V, the isomeric compound wherein the R1 and R2 moieties are reversed will usually be obtained to some extent. For this reason it will generally be necessary to separate the resulting mixture of isomers by conventional methods such as chromatography.

The compound of formula VII can be used to prepare a compound of formula III in a single step by reacting with the appropriate hydrazoic acid. This is generally carried out in the presence of a base, such as triethylamine, in a solvent such as xylene, at reflux under an inert atmosphere such as nitrogen.

The compound of formula VII can be prepared by reacting a compound of formula X:

where R1 and R2 are as defined above, with a suitable reagent for introducing leaving groups G and G1, for example where G and G1 are both chlorine POCl3 can be used generally with heating to reflux for about 16 hours.

The compound of formula X can be prepared by reacting a compound of formula XI with hydrazine hydrate (H2NNH2.H2O): where R1 and R2 are as defined above. The reaction is generally carried out in a protic solvent, such as 40% aqueous acetic acid, and in the presence of a buffering agent such as sodium acetate, generally with heating to reflux for about 16 hous.

The compound of formula XI can be prepared by reaction of a compound of formula XII: with suitable reagents to introduce the substitutents R1 and R2 where necessary. For example, when R1 is phenyloxy or pyridyloxy or a derivative thereof, the corresponding hydroxy compound can be used as a reagent. the compound of formula XII is commercially available.

alternatively, when R1 is the same as L-Y-X in the compound of formula I, it can be introduced by displacing another group R1 which can act as a leaving group, such as fluorine, in the reaction between the compounds of formulae III and IV.

In another procedure, the compounds according to the invention wherein L is O may be prepared by a process which comprises reacting a compound of formula VIII with a compound of formula IX: J-YX (IX) wherein R1, R2, X, Y and Z are as defined above and J represents a sutiable leaving group such as a halogen atom, typically achlorine. The reaction between compounds VIII and IX is conveniently effected by stirring the reactants in a suitable solvent, typically N, N-dimethylformamide, in the presence of a strong base such as sodium hydride.

The intermediates of formula VIII above may be conveniently prepared by reacting a compound of formula III as defined above with an alkaline hydroxide, e.g. sodium hydroxide. The reaction is conveniently effected in an inert solvent such as 1,4-dioxane, ideally at the reflux temperature of the solvent. A compound of formula III in which G is para- sulphonyltoluene can be made by reacting a compound of formula VIII with 4-toluenesulphonylchloride.

Where they are not commercially available, the starting materials of formula IV, VI, VIII and IX may be prepared by methods analogous to those described in the accompanying Examples, or by standard methods known from the art.

It will be understood that any compound of formula I initially obtained from the above process may, where appropriate, subsequently be

elaborated into a further compound of formula I by techniques known from the art.

It will also be appreciated that where more than one isomer can be obtained from a reaction then the resulting mixture of isomers can be separated by conventional means.

Where the above-described process for the preparation of the compounds according to the invention gives rise to mixtures of stereoisomers, these isomers may be separated by conventional techniques such as preparative chromatography. The novel compounds may be prepared in racemic form, or individual enantiomers may be prepared either by enantiospecific synthesis or by resolution. The novel compounds may, for example, be resolved into their component enantiomers by standard techniques such as preparative HPLC, or the formation of diastereomeric pairs by salt formation with an optically active acid, such as (-)-di-p-toluoyl-d-tartaric acid and/or (+)-di-p-toluoyl-l-tartaric acid, followed by fractional crystallization and regeneration of the free base.

The novel compounds may also be resolved by formation of diastereomeric esters or amides, followed by chromatographic separation and removal of the chiral auxiliary.

During any of the above synthetic sequences it may be necessary and/or desirable to protect sensitive or reactive groups on any of the molecules concerned. This may be achieved by means of conventional protecting groups, such as those described in Protective Groups in Organic Chemistry, ed. J.F.W. McOmie, Plenum Press, 1973; and T.W. Greene & P.G.M. Wuts, Protective Groups in Organic Synthesis, John Wiley & Sons, 1991. The protecting groups may be removed at a convenient subsequent stage using methods known from the art.

The compounds in accordance with this invention potently inhibit the binding of [3H]-flumazenil to the benzodiazepine binding site of human GABAA receptors containing the a5 subunit stably expressed in Ltk- cells.

Reagents

# Phosphate buffered saline (PBS).

# Assay buffer: 10 mM KH2PO4, 100 mM KCl, pH 7.4 at room temperature.

# [3H]-Flumazenil (18 nM for α1 3γ2 cells; 18 nM for α2 3γ2 cells; 10 nM for α3 3γ2 cells; 10 nM for α5 3γ2 cells) in assay buffer.

# Flunitrazepam 100 µM in assay buffer.

# Cells resuspended in assay buffer (1 tray to 10 ml).

Harvesting Cells Supernatant is removed from cells. PBS (approximately 20 ml) is added. The cells are scraped and placed in a 50 ml centrifuge tube. The procedure is repeated with a further 10 ml of PBS to ensure that most of the cells are removed. The cells are pelleted by centrifuging for 20 min at 3000 rpm in a benchtop centrifuge, and then frozen if desired. The pellets are resuspended in 10 ml of buffer per tray (25 cm x 25 cm) of cells.

Assay Can be carried out in deep 96-well plates or in tubes. Each tube contains: .300 sul of assay buffer.

.50 µl of [3H]-flumazenil (final concentration for α1 3γ2: 1.8 nM; for a2P3y2: 1.8 nM; for a3P3y2: 1.0 nM; for aSp3y2: 1.0 nM).

50 pl of buffer or solvent carrier (e.g. 10% DMSO) if compounds are dissolved in 10% DMSO (total); test compound or flunitrazepam (to determine non-specific binding), 10 pM final concentration.

# 100 µl of cells.

Assays are incubated for 1 hour at 40°C, then filtered using either a Tomtec or Brandel cell harvester onto GF/B filters followed by 3 x 3 ml washes with ice cold assay buffer. Filters are dried and counted by liquid scintillation counting. Expected values for total binding are 3000-4000 dpm for total counts and less than 200 dpm for non-specific binding if using liquid scintillation counting, or 1500-2000 dpm for total counts and less than 200 dpm for non-specific binding if counting with meltilex solid

scintillant. Binding parameters are determined by non-linear least squares regression analysis, from which the inhibition constant Ki can be calculated for each test compound.

The compounds of the accompanying Examples were tested in the above assay, and all were found to possess a Ki value for displacement of [3H]Ro 15-1788 from the a5 subunit of the human GABAA receptor of 100 nM or less, most were at 50 nM or less, many were at 10 nM or less and some were at 1 nM or less.

The compounds of the present invention have been shown to enhance cognition in the rat water maze test (Morris, Learning and Motivation, 1981, 12, 239ff). Further details of methodology for demonstrating that the present compounds enhance cognition can be found in WO-A-9625948.

The following Examples illustrate the present invention: INTERMEDIATE 1 6-Chloro-3-(5-Methylisoxazol-3-yl)-1, 1,2, 4-triazolo [3, 4-aiphthalazine a) 1-Chloro-4-hydrazinophthalazine 1,4-Dichlorophthalazine (20.0g, 0.100 mol) was added to a boiling solution of hydrazine monohydrate (37.3 ml, 0.765 mol) in ethanol (500 ml) and the mixture heated at reflux for 0.5 h. The mixture was cooled to room temperature and the solid collected by filtration and washed with ether. The material was taken with n-butanol and ammonia solution (sp. gr. 0.91) and heated until the solid dissolved. The organic layer was separated, evaporated in vacuo and the residue azeotroped with xylene (x2) and dried in vacuo to give the title-hydrazine (11.5 g, 59%), lH NMR (250 MHz, d6DMSO) 6 7.84 - 8.04 (3H, m, Ar-H), 8.20 (1H, m, Ar-H); MS (ES+) m/e 194 [MH]+. b) 5-Methylisoxazole - 3-carboxylic acid A mixture of acetonylacetone (lOg, 88 mmol) and nitric acid (sp. gr.

1.42) / water (2:3) (50 ml) was cautiously brought to reflux under a stream

of nitrogen and boiled for 1h. The solution was cooled to room temperature and aged overnight. The resultant solid was collected by filtration, washed with chilled water (2 x 7 ml) and hexane, and dried in vacuo to give the title-acid (4.4g, 40%), 1H NMR (CDCl3) # 2.50 (3H, d, J=0.8Hz, Me), 6.41 (1H, d, J=0.8Hz, Ar-H). c) 6-chloro-3-(5-Methylisoxazol-3-yl)- 1,2, 4-triazolo [3,4-al ohthalazine 5-methylisoxazole-3-carboxylic acid (5.24 g, 41.3 mmol), bis(2-oxo-3- oxazolidinyl)phosphinic chloride (10.5 g, 41.2 mmol) and triethylamine (11.5 ml, 82.5 mmol) were added successively to a stirred suspension of 1-chloro-4-hydrazinophthalazine (8.00 g, 41.2 mmol) in dichloromethane (1 1) at 0 °C under nitrogen. The mixture was stirred at 0 °C for 2h and at room temperature overnight. The solvent was evaporated in vacuo, the residue triturated with water and the solid filtered off, washed with hexane and dried in vacuo to give the ketohydrazine (11 g), MS (ES+) m/e 304 [MH]+. A solution of the ketohydrazine (11 g) and triethylamine hydrochloride (2.2 g, 20% w/w) in xylene (500 ml) was heated at reflux for 3 h. The mixture was cooled to room temperature and the solvent evaporated in vacuo. The residue was dissolved in dichloromethane, washed with water (x 2), dried (MgSO4) and evaporated in vacuo, and the solid recrystallised (dichloromethane/hexane) to give the title-compound (6.8 g, 58%), lH NMR (360MHz, CDCl3) 6 2.59 (3H, s, Me), 6.90 (1H, s, Ar-H), 7.95 (1H, m, Ar-H), 8.07 (1H, m, Ar-H), 8.34 (1H, m, Ar-H), 8.78 (1H, s, Ar-H); MS (ES+) m/e 286 [MH]+.

EXAMPLE 1 3-(5-Methylisoxazol-3-yl)-6-(2-pyridyl)methyloxy-1,2,4-triaz olo[3m4- al phthalazine Sodium hydride (244 mg of a 60% dispersion in oil, 6.10 mmol) was added to a stirred solution of 2-pyridylcarbinol (470 mg, 4.27 mmol) in DMF (60 ml) at room temperature under nitrogen and the mixture stirred for 0.25 h. After this time, Intermediate 1 (1160 mg, 4.07 mmol) was

added andthe mixture stirred for 2h. The solvent was removed in vacuo and the residue dissolved in dichlormethane, washed with water (x2), dried (MgSO4) and evaporated in vacuo. Flash chromatography on silica gel eluting with 3% methanol/dichloromethane followed by recrystallisation (dichloromethane/hexane) gave the title-product (640 mg, 44%), mp 234 - 236 °C; 1H NMR (360MHz, CDCl3) 6 2.59 (3H, d, J =0.8Hz, Me), 5.77 (2H, s, CH2), 6.82 (1H, d, J=0.8Hz, Ar-H), 7.30 (1H, m, Ar-H), 7.74 - 7.85 (311, m, Ar-H), 7.95 (1H, m, Ar-H), 8.33 (1H, d, J=7.8Hz, Ar-H), 8.64 - 8.72 (2H, m, Ar-H); MS (ES+) m/e 359 [MH]+; Anal. Found. C, 62.93; H, 3.56; N, 22.94. C19H14N6O2 0.05 (CH2Cl2) requires C, 63.10; H, 3.92; N, 23.17%.

EXAMPLE 2 3-(5-Methylisoxazol-3-yl)-6-(6-methylopyridin-2-yl)methyloxy -1,2,4- triazolo[3,4-a]phathalazine The title-compound was prepared from Intermediate 1 and 6- methyl-2-pyridylcarbinol using the procedure given for Example 1, lH NMR (360 MHz, CDC13) 6 2.59 (3H, d, J = 0.8 Hz, Me), 2.61 (3H, s, Me), 5.73 (2H, s, CH2), 6.86 (1H, d, J = 0.8 Hz, Ar-H), 7.16 (1H, d, J = 7.6 Hz, Ar-H), 7.53 (1H, d, J = 7.5 Hz, Ar-H), 7.66 (1H, t, J = 7.7 Hz, Ar-H), 7.83 (111, m, Ar-H), 7.97 (1H, t, J = 8.2 Hz, Ar-H), 8.33 (1H, d, J = 7.7 Hz, Ar-H), 8.70 (1H, d, J = 7.7 Hz, Ar-H); MS (ES+) m/e 373 [MH]+; Anal.

Found. C, 60.72; H, 4.15; N, 21.20. C20H16N6O2. 1.15 (H20) requires C, 61.11; H, 4.69; N, 21.38%.

EXAMPLE 3 3-(5-Methylisoxazol-3-yl)-6-(3-pyridyl)methyloxy-1,2,4-triaz olo[3,4- a]phthalazine The title-compound was prepared from Intermediate 1 and pyridine- 3-methanol using the procedure given for Example 1, mp 226 - 228 °C; lH NMR (360 MHz, CDCl3) 6 2.59 (3H, d, J = 0.6 Hz, Me), 5.69 (2H, s, CH2),

6.83 (1H, d, J = 0.8 Hz, Ar-H), 7.37 (1H, m, Ar-H), 7.79 (1H, t, J = 8.4 Hz, Ar-H), 7.95 (1H, t, J = 8.6 Hz, Ar-H), 8.08 (1H, d, J = 7.8 Hz, Ar-H), 8.22 (1H, d, J = 8.5 Hz, Ar-H), 8.65 (1H, d, Ar-H), 8.70 (1H, d, Ar-H), 8.93 (1H, br s, Ar-H); MS (ES+) m/e 359 [MH+; Anal, Found. C, 63.54; H, 3.70; N, 23.10. C19H14N602 requires C, 63.68; H, 3.94, N 23.45%.

EXAMPLE 4 3-(5-Methylisoxazol-3-yl)-6-(4-pyridyl)methyloxy-1,2,4-triaz olo[3,4- alphthalazine The title-compound was prepared from Intermediate 1 and pyridine- 4-methanol using the procedure given for Example 1, mp 244 - 246 °C; lH NMR (360 MHz, CD Cl3) 6 2.58 (3H, s, Me), 5.68 (2H, s, CH2), 6.79 (1H, s, Ar-H), 7.57 (2H, br s, Ar-H), 7.85 (1H, t, J = 7.3 Hz, Ar-H), 7.98 (1H, t, J = 7.9 Hz, Ar-H), 8.29 (1H, d, 8.0 Hz, Ar-H), 8.70 (2H, d, Ar-H); MS (ES+) m/e 359 [MH]+; Anal. Found. C, 62.81; H, 3.93; N, 22.78. C19H14N6O2.

0.3 (H20) requires C, 62.74; H, 4.04; N, 23.10% EXAMPLE 5 6-(3,5-dimethylpyrazol-1-yl)methyloxy-3-(5-methylisoxazol-3- yl)-1,2,4- triazolo[3,4-a]phthalazine The title-compound was prepared from Intermediate 1 and 3,5- dimethylpyrazole-1-methanol using the procedure given in Example 1 mp 229 - 231 °C; lH NMR (360 MHz, CD Cl3) 6 2.27 (3H, s, Me), 2.41 (3H, s, Me), 2.61 (3H, s, Me), 5.98 (1H, s, Ar-H), 6.49 (2H, s, CH2), 6.96 (1H, d, J = 0.8 Hz, Ar-H), 7.83 (1H, t, J = 8.4 Hz, Ar-H), 8.02 (1H, t, J = 8.3 Hz, Ar-H), 8.20 (1H, d, J = 7.8 Hz, Ar-H), 8.70 (1H, d, Ar-H); MS (ES+) m/e 376 [MH]+, Anal. Found. C, 59.65; H, 4.13; N, 25.26. C19H17N7O2.0.1 (CH2CL2) requires C, 59.76; H, 4.51, N, 25.54%.

6-(3-Methoxypyridin-2-yl)methyloxy-3-(5-methylisoxazol-3- yl)-1.2.4- triazolo[3,4-a]phthalazine a) 3-Methoxy(2-hydroxymethyl)phyridine To a mixture of ground potassium hydroxide (10.2 g, 0.186 mol) in dimethylsulphoxide (15 ml) under nitrogen was added 3-hydroxy(2- hydroxymethyl)pyridine hydrochloride (5.0 g, 0.031 mol) in dimethylsulphoxide (15 ml) over 0.25 h. The reaction was stirred at room temperature for 1 h before the addition of methyl iodide (1.92 ml, 0.0309 mol) and then stirred at room temperature overnight. Water (100 ml) was added and the solution acidified to pH 1 with 2N hydrochloric acid, washed with dichloromethane (x 3) and then basified with solid potassium carbonate until pH 12 was attained. The aqueous was extracted with dichloromethane (x 3), dried (MgSO4), evaporated in vacuo and the residue purified by chromatography on silica gel, eluting with dichloromethane/methanol/ammonia (90:5:0.5), to give the title-compound (300 mg, 7%). 1H NMR (360 MHz, CD Cl3) 6 3.85 (3H, s, CH3), 4.74 (2H, s, CH2), 7.12 (1H, d, J = 8.3Hz, Ar-H), 7. 21 (1H, m, Ar-H), 8.15 (1H, d, J = 4.8Hz, Ar-H). b) 3-(5-Methylisoxazol-3-yl)-6-(3-methoxypyridin-2-yl)methyloxy -1,2,4- triazolo[3,4-a]phthalazine The title-compound was prepared from Intermediate 1 and the preceding alcohol using the procedure given for Example 1, mp 243 - 245 °C; 1H NMR 6 (360 MHz, CDCl3) 5 2.59 (3H, d, J = 0.5 Hz, Me), 3.90 (3H, s, OMe), 5.79 (2H, s, CH2), 6.87 (1H, d, J = 0.8 Hz, Ar-H), 7.34 (2H, m, Ar-H), 7.76 (1H, t, J = 8.2, Ar-H), 7.93 (1H, t, J = 8.1 Hz, Ar-H), 8.25 (1H, m, Ar-H), 8.70 (1H, d, Ar-H); MS (ES+) m/e 389 [MH]+; Anal. Found. C, 62.03; H, 3.68; N, 21.52. C20Hl6NsO3 requires C, 61.85; H, 4.15; N, 21.18%.

EXAMPLE 7 6-(6-Methylisoxazol-3-yl)methyloxy-3-(5-methylisoxazol-3-yl) -1,2l4- triazolo[3,4-a]phthalazine The title-compound was prepared from Intermediate 1 and 5- methylisoxazole-3-methanol using the procedure given for Example 1, mp 243 - 245 °C; lH NMR (360 MHz, CD Cl3) 5 2.45 (3H, s, Me), 2.60 (3H, s, Me), 5.70 (2H, s, CH2), 6.43 (1H, s, Ar-H), 6.88 (1H, d, J = 0.7 Hz, Ar-H), 7.81 (1H, t, J = 8.2 Hz, Ar-H), 7.98 (1H, t, J = 8.1 Hz, Ar-H), 8.24 (1H, d, J = 7.9 Hz, Ar-H), 8.70 (1H, d, Ar-H); MS (ES+) m/e 347 [MH]+; Anal.

Found. C, 59.45; H, 3.62; N, 22.80. C181114N6O2 requires C, 59.67; H 3.89; N, 23.19%.

EXAMPLE 8 3-(5-Methylisoxazol-3-yl)-6-(pyrazol-1-yl)methyloxy-1,2,4-tr iazolo [3,4-a]phthalazine a) Pyrazole-1-methanol To a solution of pyrazole (1.0 g, 0.015 mol) in tetrahydrofuran (40 ml) at room temperature was added formaldehyde (37% aq) (1.19 g, 0.0147 mol) and the mixture stirred for 16 h. The solvent was removed in vacuo to give the title-alcohol (1.36 g, 94%). lH NMR (250 MHz, CD Cl3) 5 5.53 (2H, s, CH2), 6.30 (1H, t, J = 3.1 Hz, Ar-H), 7.58 - 7.60 (2H, m, Ar-H). b) 3-(5-Methylisoxazol-3-yl)-6-(pyrazol-1-yl)methyloxy-1-2-4- triazolo[3,4-A]PHTHALAZINE The title-compound was prepared from Intermediate 1 and pyrazole- 1-methanol using the procedure given for Example 1, mp 235 - 237 °C; lH NMR (360 MHz, CDCl3 # 2.60 (3H, d, J = 0.7 Hz, Me), 6.29 (1H, t, J = 2.5 Hz, Ar-H), 6.61 (2H, s, CH2), 6.91 (1H, d, J = 0.8 Hz, Ar-H), 7.61 (1H, s, Ar-H), 7.81 (1H, t, J = 10.4 Hz, Ar-H), 7.95 (1H, t, J = 7.5 Hz, Ar-H), 8.25 (1H, d, J = 7.8 Hz, Ar-H), 7.70 (2H, m, Ar-H); MS (ES+) m/e 348 [MH]+.

EXAMPLE 9 6-(6-Chloropyridin-2-yl)methyloxy-3-(5-methylisoxazol-3-yl)- 1,2,4- triazolo[3,4-a]phthalazine a) 2-Chloropyridine-6-methanol m-Chloroperbenzoic acid (50%) (16.2 g, 94 mmol) was added over 0.75 h to a solution of 2-chloro-6-methylpyridine (5 g, 39 mmol) in dichloromethane (100 ml) at OOC, and the mixture stirred at room temperature overnight. Further mCPBA (2.7 g, 15 mmol) in dichloromethane (20 ml) was added and stirred for 2 h.

Sodium hydroxide solution (4M, 15 ml) was added and the organic layer separated, dried (MgSO4) and evaporated in vacuo to give the N- oxide (5.13 g). The N-oxide (7.74 g,) was added slowly to acetic anhydride (15 ml) at 110 °C with stirring. The mixture was heated at 110 °C for 2 h, cooled to room temperature and distilled in vacuo to give the acetate (4.8 g), bp 98 - 104 °C at 1.8 mbar. A solution of the acetate (4.8 g) in methanol / HCl solution (1:1) was stirred for 5 h at room temperature.

The mixture was basified by addition of sodium hydroxide solution (1 M), and extracted into dichloromethane. The organic extracts were washed with brine (x 1), dried (MgSO4) and evaporated in vacuo and the residue flash chromatographed on silica gel, eluting with 2% methanol / dichloromethane to give the title-alcohol (2.02 g), lH NMR (250 MHz, CDCl3), 6 4.75 (2H, s, CH2), 7.24 (2H, m, 2 of Ar-H) 7.66 (1H, t, J = 7.7 Hz, Ar-H); MS (ES+) m/e 144 [MH]+. b) 6-(6-Chloropyridin-2-yl)methyloxy-3-(5-methylisoxazol-3-yl)- 1,2,4- triazolo[3,4-a]phthalazine The title-compound was prepared from the preceding alcohol and Intermediate 1 following the procedure given for Example 1, mp 240 - 242 °C 1H NMR (360 MHz, CD Cl3) 5 2.60 (3H, d, J = 0.6 Hz, Me), 5.73 (2H, s, CH2), 6.82 (1H, d, J = 0.7Hz, Ar-H), 7.33 (1H, m, Ar-H), 7.72 - 7.74 (211, m, Ar-H), 7.84 ((1H, t, J = 8.3 Hz, Ar-H), 7.99 (1H, t, J = 8.2 Hz, Ar-H), 8.31 (1H, d, J = 7.8 Hz, Ar-H), 8.70 (1H, d, Ar-H); MS (ES+) m/e 393 [MH]+;

anal. Found. c, 58.58; H, 3.11; N, 21.32. C19H13N6O2Cl requires C, 58.10; H, 3.34; N, 21.39%.

EXAMPLE 10 6-(6-Chloropyridin-2-yl)methyloxy-3-(5-methylisoxazol-3-yl)- 1,2,4- triazolo [3, 4-alphthalazine The title-compound was prepared from Intermediate 1 and 2- bromopyridine-6-methanol (Tetrahedron Lett., 1996, 50, 2537) following the procedure given for Example 1. The product was isolated by addition of water to the reaction mixture and the resulting precipitate was filtered off. Flash chromatography on silica gel, eluting with ethyl acetate, and recrystallisation (ethyl acetate-methanol) gave the title-phthalazine, mp 247.5 - 249 °C; lH NMR (360 MHz, CDCl3) 5 2.61 (3H, d, J = 0.7 Hz, Me), 5.73 (2H, s, CH2), 6.82 (1H, d, J = 0.7 Hz, Ar-H), 7.48 (1H, d, J = 7.8 Hz, Ar-H), 7.63 (1H, t, J = 7.7 Hz, Ar-H), 7.76 (1H, d, J = 7.4 Hz, Ar-H), 7.84 (1H, t, J = 8.4 Hz, Ar-H), 7.98 (1H, t, J = 8.4 Hz, Ar-H), 8.31 (1H, d, J = 8.5 Hz, Ar-H), 8.70 (1H, d, Ar-H); MS (ES+) m/e 437 [MH]+; Anal. Found C, 52.27; H, 2.85; N, 19.14. C19H13N6O2 Br. 0.1 (H20) requires C, 51.98; H, 3.03; N, 18.60%.

EXAMPLE 11 6-(6-Chloropyridin-2-yl)methyloxy-3-(5-methylisoxazol-3-yl)- 1,2,4- triazolor3,4-alphthalazine a) 6-Bromo-2-[(tetrahydropyran-2-yl)oxymethyl]pyridine 2-Bromopyridine-6-methanol (prepared as described in Tetrahedron Lett., 1996, 50, 2537) (5 g, 26.5 mmol) was added to a solution of dihydropyran (2.65 ml, 29.2 mmol), and p-toluenesulfonic acid (506 mg, 2.7 mmol) in dichloromethane (150 ml) at room temperature under nitrogen. After 24 h, the mixture was washed with sodium carbonate solution (x 1) and water (x 1), dried (MgSO4), evaporated in vacuo and the residue flash chromatographed on silica gel, eluting with 10% ethyl

acetate / hexane to give the title-compound (6.04 g, 84%), 1H NMR (250 MHz, CDCl3) # 1.5 - 1.9 (6H, m, 3 of CH2), 3.56 (1H, m, CH2O), 3.88 (1H, m, CH2O), 4.62 (1H, d, J = 14.2 Hz, CH2O), 4.76 (1H, t, J = 3.4 Hz, CHO), 4.93 (1H, d, J = 14.6 Hz, CH2O), 7.37 (1H, d, J = 7.6 Hz, Ar-H), 7.46 (1H, d, J = 6.6 Hz, Ar-H), 7.56 (1H, t, J = 7.6 Hz, Ar-H); MS (ES+) m/e 272 [MH]+. b) 6-Methoxy-2-[(tetrahydropyran-2-yl)oxymethyl]pyridine Methanol (467 mg, 14.5 mmol) was added to a stirred mixture of sodium hydride (595 mg of a 60% dispersion in oil, 14.9 mmol) in N,N-dimethylformamide (20 ml) at room temperature under nitrogen, and the mixture stirred for 0.75 h. The preceding bromide was added in N,N-dimethylformamide (5ml) and the reaction mixture stirred for 24 h.

The solvent was removed in vacuo and the residue partitioned between water and ethyl acetate. The aqueous phase was extracted with ethyl acetate (x 3) and the combined extracts dried (MgSO4) and evaporated in vacuo to give the title-compound (666 mg). 1H NMR (250 MHz, CD Cl3), 5 1.5 - 1.9 (6H, m, 3 of CH2), 3.57 (1H, m, CH20), 3.95 (4H, m, CH20 and <BR> <BR> <BR> <BR> <BR> OMe), 4.55 (1H, d, J = 13.7 Hz, CH20), 4.78 (2H, m CH CH2O), 6.61 (1H, d, J = 8.2 Hz, Ar-H), 7.02 (1H, d, J = 7.3 Hz, Ar-H), 7.56 (1H, m, Ar-H); MS (ES+) m/e 224 [MH]+. c) 2-Methyloxypyridine-6-methanol Pyridinium p-toluenesulphonate (75 mg, 0.3 mmol) was added to a solution of the preceding product (666 mg, 3.0 mmol) in ethanol (2 ml) at room temperature under nitrogen. The mixture was heated at 55 °C for 3 h then cooled and the solvent removed in vacuo. Flash chromatography of the residue on silica gel, eluting with 30% ethyl acetate / hexane, gave the title-compound (204 mg, 50%) lH NMR (250 MHz, CD Cl3) 5 3.52 (1H, br s, OH), 5 3.96 (3H, s, Me), 4.68 (2H, s, CH2), 6.64 (1H, d, J = 8.2 Hz, Ar-H), 6.80 (1H, d, J = 7.2 Hz, Ar-H), 7.56 (1H, dd, J = 8.2 and 7.3 Hz, Ar-H); MS (ES+) m/e 140 [MH]+.

d) 6-(6-Chloropyridin-2-yl)methyloxy-3-(5-methylisoxazol-3-yl)- 1,2,4- triazoo[3,4-a]phthalazine The title-compound was prepared from Intermediate 1 and the preceding alcohol using the procedure described for Example 10, mp 211 - 213 °C; lH NMR (360 MHz, CDCl3), 5 2.57 (3H, d, J = 0.7Hz, Me), 3.95 (3H, s, OMe), 5.65 (2H, s, CH2), 6.72 (1H, d, J = 8.4 Hz, Ar-H), 6.78 (1H, d, J = 0.8 Hz, Ar-H), 7.20 (1H, m, Ar-H), 7.62 (1H, m, Ar-H), 7.83 (1H, m, Ar-H), 7.97 (1H, m, Ar-H), 8.32 (1H, d, J = 8.6 Hz, Ar-H), 8.70 (1H, d, Ar-H); MS (ES+) m/e 389 [MH]+; Anal. Found. C, 62.13; H, 3.88; N, 21.83.

C20H16N6O3 requires C, 61.85; H, 4.15; N, 21.64%.

EXAMPLE 12 6-(6-Isopropoxypyridin-2-yl)methyloxy-3-(5-methylisoxazol-3- yl)-1,2,4- triazolop[3,4-a]phthalazine a) 6-Isopropoxy-2-[(tetrahydropyran-2-yl)oxymethyl]pyridine The title-compound was prepared from 6-bromo-2- [(tetrahydropyran-2-yl)oxymethyl]pyridine prepared following the procedure given for Example 11 part a and isopropyl alcohol following the procedure given for Example 11 part b, lH NMR (250 MHz, CDCl3), 5 1.32 (6H, d, J = 6. 2 Hz, 2 of CH3), 1.6 - 1.9 (6H, Me, 3 of CH2), 3.56 (1H, m, CH2O), 3.91 (1H, m, CH2O), 4.53 (1H, d, J = 13.7 Hz, CH20), 4.76 (1H, d, J = 13.6 Hz, CH2O), 4.79 (1H, m, CHO), 5.29 (1H, septet, J = 6.2 Hz, CH), 6.55 (1H, d, J = 8.2 Hz, Ar-H), 6.96 (1H, d, J = 7.3 Hz, Ar-H), 7.53 (1H, dd, J = 8.2 and 7.3 Hz, Ar-H); MS (ES+) m/e 252 [MH]+. b) 2-Isopropoxypyridine-6-methandol The title-compound was prepared from the preceding isopropoxypyridine using the procedure given for Example 11 part c, lH NMR (250 MHz, CDCl3), 5 1.36 (6H, d, J = 6.2 Hz, 2 of CH3), 3.51 (1H, br t, OH), 4.65 (2H, d, J = 3.5 Hz, CH2), 5.31 (1H, septet, J = 6.2 Hz, CH), 6.58 (1H, dd, J = 8.2 and 0.6 Hz, Ar-H), 6.74 (1H, dd, J = 7.3 and 0.8 Hz, Ar-H), 7.54 (1H, dd, J = 8.2 and 7.3 Hz, Ar-H); MS (ES+) m/e 168 [MH]+.

c) 6-(6-Isopropoxypyridin-2-yl)methyloxy-3-(5-methylisoxazol-3- yl)- 1,2,4-triazolo[3,4-a]phthalazine The title-compound was prepared from Intermediate 1 and the preceding alcohol using the procedure described for Example 10, mp 188 - 190 °C: lH NMR (360 MHz. CDCl3) 5 1.32 (6H, d, J = 6.2 Hz, 2 of CH3), 2.57 (3H, d, J = 0.7 Hz, Me), 5.30 (1H, septet, J = 6.5 Hz, CH), 5.63 (2H, s, CH2), 6.66 (1H, d, J = 8.3 Hz, Ar-H), 6.80 (1H, s, Ar-H), 7.15 (1H, d, J = 7.5 Hz, Ar-H), 7.60 (1H, t, J = 8.3 Hz, Ar-H), 7.83 (1H, t, J = 8.4 Hz, Ar-H), 7.97 (1H, t, J = 8.6 Hz, Ar-H), 8.31 (1H, d, J = 7.8 Hz, Ar-H), 8.70 (1H, d, Ar-H); MS (ES+) m/e 417 [MH]+; Anal. Found. C, 63.84; H, 4.57; N, 19.96%; C22H20N6O2 requires C, 63.45; H, 4.84; N, 20.18%.

EXAMPLE 13 6-(6-N,N-Dimethylpyridin-2-yl)methyloxy-3-(5-methylisoxazol- 3-yl)-1,2,4- triaozl[3,4-a]phthalazine a) (6-N,N-Dimethyl-2-[-(tetrahydropyran-2-yl)oxymethyl]pyridine A mixture of 6-bromo-2- [(tetrahydropyran-2-yl)oxymethyl]pyridine (400 mg, 15 mmol) prepared following the procedure given for Example 11 part a and dimethylamine (10 ml of a 33% solution in ethanol) was heated at reflux for 48 h and then heated in a sealed tube at 120 °C for 18 h. The solvent was removed in vacuo and the residue taken up in ethyl acetate, washed with sodium carbonate solution (x 1), dried (MgSO4) and evaporated in vacuo. Flash chromatography of the residue on silica gel, eluting with 15% diethyl ether / hexane, gave the title-compound (298 mg, 86%), lH NMR (250 MHz, CDCl3), 6 1.5 - 1.8 (6H, m, 3 of CH2) 3.07 (6H, s, 2 of CH3), 3.55 (1H, m, CH20), 3.95 (1H, m, CH2O), 4.51 (1H, d, J = 13.5 Hz, CH2O), 4.74 (1H, d, J = 13. 5 Hz, CH2O), 4.80 (1H, m, CH), 6.40 (1H, d, J = 8.5 Hz, Ar-H), 6.69 (1H, d, J = 7.2 Hz, Ar-H), 7.44 (1H, dd J = 8.3 and 7.4 Hz, Ar-H); MS (ES+) m/e 237 [MH]+.

b) 6-N,N-dimethylpyridine-2-methanol The title-compound was prepared from the preceding pyridine using the procedure given for Example 11 part c, 1H NMR (250 MHz, CDCl3), # 3.91 (6H, s, 2 of CH3), 4.21 (1H, br s, OH), 4.61 (2H, s, CH2), 6.40 (2H, t, J = 7.9 Hz, Ar-H), 7.43 (1H, t, J = 7.8 Hz, Ar-H); MS (ES+) m/e 153 [MH]+. c) 6-N,N-Dimethylpyridin-2-yl)methyloxy-3-(5-methylisoxazol-3-y l)- 1,2,4-triazolo[3,4-a]phthalazine The title-compound was prepared from Intermediate 1 and the preceding alcohol following the procedure described for Example 10, mp 188 - 190 °C; lH NMR (360 MHz, CD Cl3), 6 2.56 (3H, d, J = 0.6 Hz, CH3), 3.09 (6H, s, 2 of CH3), 5.59 (2H, S, CH2), 6.48 (1H, d, J = 8.5 Hz, Ar-H), 6.79 (1H, s, Ar-H), 6.81 (1H, d, J = 7.3 Hz, Ar-H), 7.49 (1H, t, J = 7.8 Hz, Ar-H), 7.82 (1H, m, Ar-H), 7.95 (1H, m, Ar-H), 8.33 (1H, d, J = 7.8 Hz, Ar-H), 8.70 (1H, d, Ar-H); MS (ES+) m/e 402 [MH]+; Anal. Found. C, 63.09; H, 4.49; N, 24.18%; C21H19N7O2 requires C, 62.83; H, 4.77; N, 24.42%.

EXAMPLE 14 6-[6-(Imidazol-1-yl)pyridin-2-yl]methyloxy-3-(5-methylisoxaz ol-3-yl)-1,2,4- triazolo [3,4-alphthalazine a) 6-(Imidazol-1-yl)-2-[(tetrahydropyran-2-yl)oxymethyl]pyridin e Imidazole (500 mg, 74 mmol) was added to a stirred mixture of sodium hydride (300 mg of a 60% dispersion in oil, 75 mmol) and dimethylformamide (20 ml), at room temperature under nitrogen. After 0.75 h, 6-bromo-2-[(tetrahydropyran-2-yl)oxymethyl]pyridine (400 mg 14.6 mmol) prepared following the procedure given for Example 11 part a in dimethylformamide (5 ml) was added. The mixture was heated at 80 °C for 24 h then in a sealed tube at 120 °C for 4 h. The solvent was evaporated in vacuo and the residue partitioned between water and ethyl acetate. The aqueous phase was separated and extracted with ethyl acetate (x 3). The combined extracts were dried (MgSO4), and evaporated in vacuo and the residue flash chromatographed on silica gel, eluting with

5% methanol / dichloromethane to give the title-compound (280 mg, 73%), 1h NMR (250 MHz, CDCl3), # 1.5 - 1.8 (6H, m, 3 of CH2), 3.58 (1H, m, CH2O), 3.93 (1H, m, CH2O), 4.66 (1H, d, J = 14.1 Hz, CH2O0, 4.82 (1H, m, CH0, 4.90 (1H, d, J = 14.1 Hz, CH2O), 7.19 (1H, br s, Ar-H), 7.24 (1H, d, J = 8.2 Hz, Ar-H), 7.43 (1H, dd, J = 7.6 Hz and 7.1 Hz, Ar-H), 7.64 (1H, t, J = 1.2 Hz, Ar-H), 7.83 (1H, t, J = 7.9 Hz, Ar-H), 8.35 (1H, s, Ar-H); MS (ES+) m/e 260 [MH]+. b) 2-(Imidazol- l-vl)pvridine-6-methanol The title-compound was prepared from the preceding pyridine following the procedure given for Example 11 part c. 'H NMR (250 MHz, CDCl3), 5 4.81 (2H, s, CH2), 7.20 (1H, s, Ar-H), 7.24 - 7.29 (211, m, 2 of Ar-H), 7.64 (1H, t, J = 1.3 Hz, Ar-H), 7.84 (1H, t, J = 7.9 Hz, Ar-H), 8.35 (1H, s, Ar-H); MS (ES+) m/e 176 [MH]+. c) 6-[6-(Imidazol-1-yl)pyridin-2-yl]methyloxy-3-(5-methylisoxaz ol-3-yl)- 1,2,4-triazolo[3,4-a]phthalazine The title-compound was prepared from Intermediate 1 and the preceding alcohol using the procedure described for Example 10, mp 126 - 127 °C; lH NMR (360 MHz, CD Cl3), 6 2.53 (3H, d, J = 0.7 Hz, Me), 5.78 (2H, s, CH2), 6.78 (1H, d, J = 0.8 Hz, Ar-H), 7.22 (1H, s, Ar-H), 7.34 (1H, d, J = 8.1 Hz, Ar-H), 7.66 (2H, s, 2 of Ar-H), 7.80 - 7.90 (2H, m, 2 of Ar-H), 7.98 (1H, t, J = 7.5 Hz, Ar-H), 8.33 (1H, d, J = 8.4 Hz, Ar-H), 8.40 (1H, s, Ar-H), 8.70 (1H, d, Ar-H); MS (ES+) m/e 425 [MH]+; Anal. Found. C, 62.48; H, 3.49; N, 25.97. C22H16N8O2.0.05 H20 requires C, 62.13; H, 3.82; N, 26.35%.

INTERMEDIATE 2 6-Hydroxy-3-(5-Methylisoxazol-3-yl)-1,2,4-triazolo[3,4-a]pht halazine A solution of sodium hydroxide (0.67 g, 17 mmol) in water (7.5 ml) was added to a stirred solution of Intermediate 1 (1.0 g, 3.5 mmol) in dioxane (37.5 ml) and the mixture heated at reflux for 4 h. The solvent was evaporated in vacuo and the residue partitioned between water and

diethyl ether. The aqueous layer was separated, washed with ehter (x 1) and then acidified with 2N hydrochloric acid unitl pH2 was attained. The solid which precipitated out of solution was filtered off and the aqueous filtrate extracted with dichloromethane (x 3). The combined extracts were dried (MgS04) and evaporated in vacuo and combined with the precipitate to give the title-product (0.45 g, 48%), 1H NMR (250 MHz, d6-DMS0) 6 2.58 (3H, d, J = 0.7 Hz, Me), 7.07 (1H, d, J = 0.9 Hz, Ar-H), 7.94 (1H, m, Ar-H), 8.08 (1H, m, Ar-H), 8.24 (1H, d, J = 7.4 Hz, Ar-H), 8.54 (1H, d, J = 7.4 Hz, Ar-H), 13.32 (1H, br s, NH); MS (ES+) m/e 268 [MH] + EXAMPLE 15 3-(5-Methylisoxazol-3-yl)-6-(3-pyridazino)methyloxy-1,2,4- triazolo[3,4-a]phthalazine a) 3-Chloromethlpvridazine Trichloroisocyanuric acid (1.04 g, 4.46 mmol) was added to a boiling solution of 3-methylpyridazine (1.00 g, 10.6 mmol) in chloroform (30 ml) under nitrogen and the mixture heated at reflux overnight. The mixture was cooled to room temperature, diluted with dichloromethane and filtered through a pad of celite. The filtrate was washed with 1N sodium hydroxide solution (2 x 100 ml) and brine (x 2), dried (MgSO4) and evaporated in vacuo to give 3-chloromethylpyridazine. b) 3-(5-Methylisoxazol-3-vl)-6-(pyridazino) methylOxY-1, 1,2,4- triazolo [3. 4-alththalazine Sodium hydride (27 mg, 0.67 mmol) was added to a stirred solution of Intermediate 2 (150 mg, 0.561 mmol) in DMF (20 ml) at room temperature under nitrogen. The mixture was heated at 80°C for 0.3 h, cooled to room temperature and a solution of 3-chloromethylpyridazine (143 mg, 1.12 mmol) in DMF (2 ml) added. The reaction mixture was stirred at room temperature for 0.5 h and at 80 °C for 4 h. After cooling to room temperature, water (100 ml) was added and the resulting precipitate filtered off, dissolved in dichloromethane, washed with water (x 3), dried

(MgSO4) and evaporated in vacuo. Flash chromatography fo the residue on silica gel, eluting with 3% methanol/dichloromethane, followed by recrystallisation (dichloromethane/ethyl acetate) gave the title-product (78 mg, 41%) mp 222-224°C; 1H NMR (360 MHz, CDCl3) # 2.60 (3H, d, J = 0.7 Hz, Me), 6.00 (2H, s, CH2), 6.83 (1H, s, Ar-H), 7.57 (1H, dd, J = 8.4 and 5.0 Hz, Ar-H), 7.83 (1H, m, Ar-H), 7.97 (1H, m, Ar-H), 8.18 (1H, dd, J = 8.4 and 1.6 Hz, Ar-H), 8.30 (1H, d, J = 7.8 Hz, Ar-H), 8.68 (1H, d, J = 7.8 Hz, Ar-H), 9.20 (1H, m, Ar-H); MS (ES+) m/e 360 [MH]+; Anal.

Found. C, 60.31; H, 3.27; N, 27.15. C18H13N7O2 requires C, 60.16; H, 3.64; N, 27.28%.

EXAMPLE 16 3-(5-Methylisoxazol-3-yl)-6(4-pyrimidinyl)methyloxy-1,2,4- triazolo r3,4-alphthalazine The title-compound was prepared from Intermediate 2 and 4- chloromethylpyrimidine, prepared following the procedure given for Example 15 part a, using the procedure given for Example 15 part b, mp 222 - 224 °C. 1H NMR (360 MHz, CDCl3) # 2.58 (3H, d, J = 0.6 Hz, Me), 5.75 (2H, s, CH2), 6.77 (1H, s, Ar-H), 7.77 (1H, d, J = 4.5 Hz, Ar-H), 7.88 (1H, t, J = 7.7 Hz, Ar-H), 7.99 (1H, t, J = 7.4 Hz, Ar-H), 8.33 (1H, d, J = 7.9 Hz, Ar-H), 8.70 (1H, d, J = 7.7 Hz, Ar-H), 8.82 (1H, d, J = 5.1 Hz, Ar-H), 9.26 (1H, s, Ar-H); MS (ES+) m/e 360 [MH]+; Anal. Found. C, 60.41; H, 3.41; N, 27.05. C18H13N7O2 requires C,60.16; H, 2.64; N, 27.28%.

EXAMPLE 17 3-(5-Methylisoxazol-3-yl)-6-(pyrazin-2-yl)methyloxy-1.2,4- triazolo[3,4-a]phthalazine The title-compound was prepared from Intermediate 2 and 2- chloromethylpyrazine, prepared following the procedure of Example 15 part a, using the procedure given for Example 15 part b, lH NMR (360 MHz, CDCl3) # 2.59 (3H, d, J = 0.7 Hz, CH3), 5.82 (2H, s, CH2), 6.83 (1H, d,

J = 0.8 Hz, Ar-H), 7.83 (1H, t, J = 8.1 Hz, Ar-H), 7.97 (1H, t, J = 8.3 Hz, Ar-H), 8.30 (1H, d, J = 7.8 Hz, Ar-H), 8.60 (2H, d, Ar-H), 8.70 (1H, d, Ar-H), 9.15 (1H, s, Ar-H); MS (ES+) m/e 360 [MH+]; Anal. Found. c, 60.29; H, 3.31; N, 27.09. C18H13N7O2 requires C, 60.16; H, 3.64; N, 27.28%.

EXAMPLE 18 3-(5-Methylisoxazol-3-yl)-6-(2-quinolinyl)methyloxy-1,2,4- triazolo[3,4-a]phthalazine The title-compound was prepared from Intermediate 2 and 2- chloromethylquinoline, prepared following the procedure of Example 15 part a, using the procedure given for Example 15 part b, mp 223 - 225 °C; lH NMR (360 MHz, CD Cl3) 6 2.53 (3H, d, J = 0.6 Hz, Me), 5.94 (2H, s, CH2), 6.76 (1H, d, J = 0.7 Hz, Ar-H), 7.58 (1H, t, J = 7.1 Hz, Ar-H), 7.80 - 7.86 (4H, m, Ar-H), 7.87 (1H, m, Ar-H), 8.15 (1H, d, Ar-H), 8.25 (1H, d, J = 8.5 Hz, Ar-H), 8.35 (1H, d, J = 7.8 Hz, Ar-H), 8.70 (1H, d, Ar-H); MS (ES+) m/e 409 [MH+]; Anal. Found. C, 67.70; H, 3.54; N, 20.35. C23H16N6O2 requires C, 67.64; H, 3.94; N, 20.57%.

EXAMPLE 19 3-(5-Methlisoxazol-3-yl)-6-(2-quinoxalyl)methyloxy-1,2,4- triazolo [3,4-aluhthalazine The title-compound was prepared from Intermediate 2 and 2- chloromethylquinoxaline, prepared following the procedure of Example 15 part a, using the procedure given for Example 15 part b, mp 243 - 245 °C; lH NMR (360 MHz, CDCl3) # 2.58 (3H, s, Me), 6.00 (2H, s, CH2), 6.82 (1H, s, Ar-H), 7.80 - 7.85 (311, m, Ar-H), 7.97 (1H, t, Ar-H), 8.11 - 8.14 (2H, m, 2 of Ar-H), 8.32 (1H, d, J = 7.8 Hz, Ar-H), 8.70 (1H, d, Ar-H), 9.39 (1H, s, Ar-H); MS (ES+) m/e 410 [MH+]; Anal. Found. C, 63.75; H, 3.31; N, 23.32.

C22H15N7O2.0.1 (CH2Cl2) requires C, 63.52; H, 3.66; N, 23.46%.

DESCRIPTION 1 Rapid analogue synthesis of 6-(aryl)alkyloxy-3-(5-methylisoxazol-3-yl)- 1,2,4-triazolo[3,4-a]phthalazine To 0.1 g of appropriate alcohol in each tube with a stirrer under dry nitrogen was added a solution of Intermediate 1 in dimethylformamide (1.5 ml, 33 mg/ml) followed by 0.35 ml of a 1 M solution of lithium bis(trimethylsilyl) amide in tetrahydrofuran. The reactions were stirred for 16 h, diluted with methanol/water (1:4) (15 ml) and poured onto separate C18 Mega Bond Elut# cartridges (20 ml, 5 g). The cartridges were eluted with a gradient of 50 to 100% methanol / water and the fractions containing product were evaporated to yield the title-compounds.

The following examples were prepared by the method of Description 1.

EXAMPLE 20 3-(5-Methylisoxazol-3-yl)-6-(2-(4-trifluroomethyl)pyridyloxy )ethyloxy-1,2,4- triazolor3,4-alDhthalazine 1H NMR (250 MHz, CDCl3) # 2.59 (3H, s), 4.88 - 5.03 (4H, m), 6.86 (1H, s), 7.04 (1H, s), 7.13 (1H, d, J = 5Hz), 7.84 (1H, t, J = 8Hz), 7.98 (1H, t, J = 8 Hz), 8.23 (1H, d, J = 8 Hz), 8.32 (1H, d, J = 5 Hz), 8.70 (1H, d, J = 8 Hz); MS (ES+) m/e 457 [MH]+.

EXAMPLE 21 3-(5-Methylisoxazol-3-yl)-6-(6-methylpyrid-2-yl)pyridyloxy)e thyloxy-1,2,4- triazolo[3,4-a]phthalazine 1H NMR (250 MHz, CD Cl3) 6 2.37-2.47 (2H, m), 2.54 (3H, s), 2.58 (3H, s), 3.07 (2H, t, J = 8 Hz), 4.69 (2H, t, J = 6 Hz), 6.85 (1H, s), 7.01 (2H, t, J = 8 Hz), 7.50 (1H, t, J = 7.5 Hz), 7.80 (1H, t, J = 7 Hz), 7.96 (1H, t, J = 8 Hz), 8.17 (1H, d, J = 7.5 Hz), 8.68 (1H, d, J = 7.5 Hz); MS (ES+) m/e 401 [MH]+.

EXAMPLE 22 3-(5-Methylisoxazol-3-yl)-6-(5-(4-methylisothiazoly)ethyloxy -1,2,4- triazolo[3,4-a]phthalazine 1H NMR (360 MHz, CDCl3) # 2.51 (3H, s), 2.58 (3H, s), 3.46 (2H, t, J = 6 HZ), 4.81 (2H, t, J = 6 Hz), 6.83 (1H, s), 7.83 (1H, t, J = 8 Hz), 7.96 (1H, t, J = 7 Hz), 8.21 (1H, d, J = 8 Hz), 8.62 (1H, s), 8.69 (1H, d, J = 8Hz); MS (ES+) m/e 393 [MH]+.

EXAMPLE 23 3-(5-Methylisoxazol-3-yl)-6-(2,6-dichlorophenyl)methyloxy-1, 2,4-triazolo- phthalazine lH NMR (250 MHz, CDCl3), 6 2.60 (3H, s), 5.91 (2H, s), 6.91 (1H, s), 7.26 - 7.46 (3H, m), 7.77 (1H, t, J = 7 Hz), 7.95 (1H, t, J = 8 Hz), 8.15 (1H, d, J = 8 Hz), 8.70 (1H, d, J = 8 Hz). MS (ES+) m/e 426 [MH]+.

EXAMPLE 24 3-(5-Methylisoxazol-3-yl)-6-(4-methylthiazol-5-yl)ethyloxy-1 ,2,4- triazolo[3,4-a]phthalazine lH NMR (250 MHz, CDCl3), 6 2.51 (3H, s), 2.58 (3H, s), 3.47 (2H, t, J = 6 Hz), 4.81 (2H, t, J = 6 Hz), 6.84 (1H, s), 7.84 (1H, t, J = 7 Hz), 7.97 (1H, t, J = 7 Hz), 8.21 (1H, d J = 8 Hz), 8.64 (1H, s), 8.70 (1H, d, J = 8 Hz); MS (ES+) m/e 393 [MH]+.

EXAMPLE 25 3-(5-Methylisoxazol-3-yl)-6-(2-methylthiazol-4-yl)ethyloxy-1 ,2,4- triazolo-r3,4-alphthalazine 1H NMR (250 MHz, CDCl3) # 2.59 (3H, s), 2.71 (3H, s), 3.42 (2H, t, J = 6 Hz), 4.93 (2H, t, J = 6 Hz), 6.88 (1H, s), 7.00 (1H, s), 7.79 (1H, t, J = 7 Hz), 7.94 (1H, t, J = 7 Hz), 8.16 (1H, d, J = 7 Hz), 8.67 (1H, d, J = 7 Hz); MS (ES+) m/e 393 [MH]+.

EXAMPLE 26 3-(5-Methylisoxazol-3-yl)-6-(2-[1-(3-trifluroomethyl)pyrid-6 -yl]imidazoly) methyloxy-1,2,4-triazolo[3,4-a]phthalazine MS (ES+) m/e 493 [MH]+.

EXAMPLE 27 3-(5-Methylisoxazol-3-yl)-6-[(1-benzyl)imidazol-2-yl]methylo xy-1,2,4- triazolo [3, 4-alnhthalazine 'H NMR (250 MHz), CDCl3) # 2.57 (3H, s), 5.39 (2H, s), 5.76 (2H, s), 6.87 - 7.19 (8H, m), 7.64 (1H, t, J = 8 Hz), 7.78 (1H, d, J = 8 Hz), 7.89 (1H, t, J = 7 Hz), 8.62 (1H, d, J = 7 Hz); MS (ES+) m/e 438 [MH]+.

EXAMPLE 28 3-(5-Methylisoxazol-3-yl)-6-[1-(4-chlorophenyl)-1,2,3-triazo l-4- yl]methyloxy-1,2,4-triazolo[3,4-a]phthalazine lH NMR (250 MHz, CDCl3) # 2.64 (3H, s), 5.83 (2H, s), 6.92 (1H, s), 7.46 (2H, d, J = 9 Hz), 7.79 - 7.85 (3H, m), 7.96 (1H, t, J = 8 Hz), 8.29 (1H, d, 7 Hz), 8.66 (1H, d, J = 7 Hz), 9.72 (1H, s); MS (ES+) m/e 459 [MH]+.

EXAMPLE 29 3-(5-Methylisoxazol-3-yl)-6-(3-chloro-2-methyl-5-trifluorome thylpyrazol-4- yl)methyloxy-1,2,4-triazolo[3,4-a]phthalazine 1H NMR (250 MHz, CDCl3) 6 2.59 (3H, s), 3.97 (3H, s), 5.58 (2H, s), 6.86 (1H, s), 7.79 (1H, t, J = 8 Hz), 7.96 (1H, t, J = 7 Hz), 8.14 (1H, d, J = 8 Hz), 8.70 (1H, d, J = 7 Hz); MS (ES+) m/e 464 [MH]+.

EXAMPLE 30 3-(5-Isporpylisoxazol-3-yl)-6-(2-pyridyl)methyloxy-1,2,4-tri azolo[3,4- a]phthalazine a) Ethyl 2,4-dioxo-5-methylhexanoate Sodium (2.63 g, 0.116 mol) was added in small portions to ethanol (65 ml) under nitrogen and the mixture heated until at reflux to aid dissolution. The solution was cooled to 0 "C and diethyl oxalate (16.98 g, 0.116 mol) and 3-methyl-2-butanone (10.0 g, 0.116 mol) added. The resulting solid was allowed to stand at room temperature for 1 h and then heated at 80 "C for 0.75 h. The solid mass was cooled to room temperature, acidified to pH 2 using dilute sulphuric acid, and water added. The mixture was extracted with ether (x 2) and the combined ethereal extracts dried (MgSO4), evaporated in vacuo and the residue distilled under reduced pressure to give the title-ester (14.4 g, 67%); lH NMR (360 MHz, CDCl3) 5 1.19 (6H, d, J = 6.8 Hz, 2 of Me), 1.38 (3H, t, J = 7.1 Hz, Me), 2.67 (1H, septet, J = 7.0 Hz, CHMe2), 4.36 (2H, q, J = 7.1 Hz, CH2), 6.41 (1H, s, CH), 14.53 (1H, br s, OH) (enol form). b) Ethyl 5-isopropylisoxazole-3-carboxylate A mixture of the preceding ester (5.0 g, 27 mmol) and hydroxylamine hydrochloride (5.6 g, 81 mmol) in ethanol (100 ml) was heated at reflux under nitrogen for 1 h. The mixture was cooled to room temperature, the solvent evaporated in vacuo and the residue partitioned between ethyl acetate and water. The aqueous layer was separated and extracted further with ethyl acetate (x 1). The combined extracts were dried (MgSO4), evaporated in vacuo and the residue chromatographed on silica gel, eluting with 40% ethyl acetate / hexane, to give the title-product (3.60 g, 73%); lH NMR (360 MHz, CDCl3) 1.34 (6H, d, J = 6.9 Hz, 2 of Me), 1. 41 (3H, t, J = 7.1 Hz, Me), 3.13 (1H, septet, J = 7.1 Hz, CHMe2), 4.43 (2H, q, J = 7.1 Hz, CH2), 6.39 (1H, d, J = 0.8 Hz, Ar-H).

c) 5-Isopropylisoxazole-3-carboxylic acid A solution of sodium hydroxide (1.76 g, 44.0 mmol) in water 95ml) was added to a stirred solution of the preceding product (2.00 g, 10.9 mmol) in methanol (10ml). After 3 h at room temperature, the methanol was evaporated in vacuo and the aqueous solution cooled and acidified to pH 2 with 2N hydrochloric acid. The solution was extracted with dichloromethane (x 2) and the combined extracts dried (MgS04) and evaporated in vacuo to give the title-acid (1.39 g, 82%), lH NMR (250 MHz, CDCl3) 5 1.36 (6H, d, J = 6.9 Hz, 2 of Me), 3.16 (1H, septet, J = 7.0 Hz, CHMe2), 6.47 (1H, d, J = 0.5 Hz, Ar-H). d) 3-(5-Isopropylosoxazol-3-yl)-6-(2-pyridyl)methyloxy-1,2,4- triazolor3.4-alphthalazine The title-compound was prepared from the preceding acid, 1-chloro- 4-hydrazinophthalazine and 2-pyridylcarbinol, using the procedures given for Intermediate 1 part c and Example 1, lH NMR (360 MHz, CD Cl3) 5 1.42 (6H, d, J = 7.0 Hz, 2 of Me), 3.23 (1H, septet, J = 7.0 Hz, CHMe2), 5.78 (2H, s, CH2O), 6.82 (1H, d, J = 0.7 Hz, Ar-H), 7.29 (1H, m, Ar-H), 7.74 - 7.85 (3H, m, 3 of Ar-H), 7.96 (1H, m, Ar-H), 8.32 (1H, d, J = 7.8 Hz, Ar-H) 8.65 - 8.74 (211, m, Ar-H); MS (ES+) m/e 387 [MH]+; Anal. Found. C, 65.08: H, 4.46; N, 21.91. C21H18N6O2 requires C, 65.27; H, 4.69; N, 21.75%.

EXAMPLE 31 3-(5-Cyclopropylisoxazol-3-yl)-6-(2-pyridyl)methyloxy-1,2,4- triazolo[3,4- alphthalazine The title-compound was prepared as described in Example 30 with cyclopropylmethyl ketone being used instead of 3-methyl-2-butanone in step a), lH NMR (360 MHz, CDCl3) 6 1.09 - 1.20 (4H, m, 2 of CH2), 2.19 (1H, m, CH), 5.77 (2H, s, CH20), 6.75 (1H, s, Ar-H), 7.29 (1H, m, Ar-H), 7.74 - 7.84 (3H, m, 3 of Ar-H), 7.96 (1H, m, Ar-H), 8.32 (1H, d, J = 8.5 Hz.

Ar-H), 8.68 - 8.72 (2H, m, Ar-H); MS (ES+) m/e 385 [MH]+; Anal. Found

C, 65.43; H, 3.89; N, 21.75. C21H16N6O2 requires C, 65.62; H, 4.16; N, 21.86%.

EXAMPLE 32 3-(5-Ethylisoxazol-3-yl)-6-(2-pyridyl)methyloxy-1,2,4-triazo lo[3,4- alphthalazine a) 6-chloro-3-(5-ethylisoxazol-3-yl)-1,2,4-triazolo[3,4-a]phtha lazine and 6-chloro-3-(4,5-dimethylisozazol-3-yl)-1,2,4-triazolo[3,4-a] phthalazine The title compounds were prepared as described in Example 30 with 2-butanone being used instead of 3-methyl-2-butanone in step a).

Separation of the title compounds was achieved by chromatography on alumina eluting with dichloromethane / hexane (9:1).

6-chloro-3-(5-ethylisoxazol-3-yl)-1,2,4-triazolo[3,4-a]phtha lazine : 1H NMR (250 MHz, CDCl3) 6 1.42 (3H, t, J = 7.6 Hz, Me), 2.98 (2H, q. J = 7.6 Hz, CH2), 6.89 (1H, s, Ar-H), 7.95 (1H, m, Ar-H), 8.07 (1H, m, Ar-H), 8.34 (1H, dd, J = 8.2 and 0.6 Hz, Ar-H), 8.78 (1H, m, Ar-H); MS (ES+) m/e 300 [MH]+.

6-chloro-3-(4, 5-dimethylisoxazol-3-yl)-1, 2, 4- triazolo[3,4-a]phthalazine : 1H NMR (250 MHz, CDCl3) # 2.33 (3H, d, J = 0.5 Hz, Me), 2.49 (3H, d, J = 0.4 Hz, Me), 7.95 (1H, m, Ar-H), 8.07 (1H, m, Ar-H), 8.34 (1H, d, J = 7.6 Hz, Ar-H), 8.78 (1H, m, Ar-H); MS (ES+) m/e 300 [MH]+. b) 3-(5-Ethylisoxazol-3-yl)-6-(2-pyridyl)methyloxy-1,2,4-triazo lo[3,4- alphthalazine The title-compound was prepared from 6-chloro-3-(5-ethylisoxazol-3- yl)-1,2,4-triazolo [3,4- a]phthalazine and 2-pyridylcarbinol using the procedure given for Example 1, lH NMR (360 MHz, CD Cl3) 6 1.42 (3H, t, J = 7.6 Hz, Me), 2.93 (2H, q, J = 7.5 Hz, CH2), 5.78 (2H, s, CH20), 6.83 (1H, s, Ar-H), 7.29 (1H, m, Ar-H), 7.75 - 7.85 (3H, m, 3 of Ar-H), 7.99 (1H, m, Ar-H), 8.33 (1H, d, J = 7.8 Hz, Ar-H), 8.64 - 8.72 (2H, m, Ar-H); MS (ES+) m/e 373 [MH]+.

EXAMPLE 33 3-(4,5-Dimethylisoxazol-3-yl)-6-(2-pyridyl)methyloxy-1,2,4-t riazolo[3,4- a]phthalazine The title-compound was prepared from 6-chloro-3-(4,5- dimethylisoxazol-3-yl)-1,2,4-triazolo[3,4-a]phthalazine prepared in Example 32 part a and 2-pyridylcarbinol using the procedure given for Example 1, lH NMR (360 MHz, CDCl3) # 2.30 (3H, s, Me), 2.49 (3H, s, Me), 5.73 (2H, s, CH20), 7.29 (1H, m, Ar-H), 7.70 - 7.83 (311, m, 3 of Ar-H), 7.96 (1H, m, Ar-H), 8.31 (1H, d, J = 8.3 Hz, Ar-H), 8.64 - 8.70 (211, m, 2 of Ar-H); MS (ES+) m/e 373 [MH]+; Anal. Found C, 64.38; H, 4.05; N,22.60.

C20H,6N6O2 requires C, 64.50; H, 4.33; N, 22.57%.

EXAMPLE 34 3-(3-Isoxazolyl)-6-(2-pyridyl)methyloxyl-1,2,4-triazolo[3,4- a]phthalazine a) Ethvl isoxazole-3-carboxvlate A solution of triethylamine (5.5 ml, 40 mmol) in diethyl ether (35 ml) was added over 0.3 h to a vigorously stirred solution of carbethoxychloraldoxime (5.00 g, 33.0 mmol) (prepared as described in J. Org. Chem., 1983, 48, 366) and vinyl acetate (30.5 ml, 33.1 mmol) in ether (65 ml) at reflux under nitrogen. The mixture was heated at reflux for a further 1 h and then allowed to cool to room temperature. Water (50 ml) was added and the ethereal layer separated, dried (MgS04) and evaporated in vacuo to give ethyl (5-acetoxy-#2-isoxazlin-3-yl)carboxylate (6.28 g, 95%). This material was heated at 180 °C under nitrogen for 1 h and then distilled under reduced pressure to give the title-ester (3.23g, 73%) bp 62 °C / 1 mm Hg; 1H NMR (250 MHz, CDCl3) 6 1.43 (3H, t, J = 7.2 Hz, CH3), 4.47 (2H, q, J = 7.1 Hz, CH2), 6.80 (1H, d, J = 1.7 Hz, Ar-H), 8.62 (1H, d, J = 1.7 Hz, Ar-H).

b) 6-Chloro-3-*3-isoxazolyl)-1,2,4-triazolo[3,4-a]phthalazine Lithium hydroxide monohydrate (0.327 g, 7.79 mmol) was added to a stirred solution of the preceding ester 1.00 g, 7.90 mmol) in THF / H2O (1:1) (6 ml) at 0°C. After 2 h at 0°C, the solvent was evaporated in vacuo and the residue dissolved in water and acidified to pH 1 with 2N hydrochloric acid. Ethanol was added, the solvents evaporated in vacuo and the residue azeotroped with ethanol and dried in vacuo to give isoxazole-3-carboxylic acid contaminated with lithium chloride.

The title-compound was prepared from this material reacting with 1-chloro-4-hydrazinophthalazine using the procedure described for Intermediate 1, step c, 'H NMR (250 MHz, CDCl3) # 7.30 (1H, d, J = 1.1 Hz, Ar-H), 7.96 (1H, m, Ar-H), 8.09 (1H, m, Ar-H), 8.36 (1H, d, Ar-H), 8.68 (1H, s, Ar-H), 8.80 (1H, d, Ar-H); MS (ES+) m/e 272 [MH]+. c) 3-(3-Isoxazolyl)-6-(2-pyridyl)methyloxy-1,2,4-triazolo[3,4- alphthalazine The title-compound was prepared from the preceding product and 2- pyridylcarbinol using the procedure given for Example 1, lH NMR (360 MHz, CD Cl3) 5 5.78 (2H, s, CH2), 7.24 (1H, d, J = 1.6 Hz, Ar-H), 7.30 (1H, m, Ar-H), 7.72 - 7.88 (311, m, 3 of Ar-H), 7.97 (1H, m, Ar-H), 8.33 (1H, d, J = 7.9 Hz, Ar-H), 8.60 - 8.72 (311, m, 3 of Ar-H); MS (ES+) m/e 345 [MH] + EXAMPLE 35 3-(5-(Pyridin-3-yl)isoxazol-3-yl]-6-(2-pyridyl)methyloxy-1,2 ,4- triazolo[3,4-a]phthalazine a) Ethyl 5-(tri-n-butylstannyl)isoxazole-3-carboxylate A solution of triethylamine (2.68 g, 26.5 mmol) in diethyl ether (40 ml) was added over 5 h to a vigorous stirred solution of carbethoxychloraldoxime (4.01 g, 26.5 mmol) and tri-n-butylethynyltin (10.0 g, 31.7 mmol) in diethyl ether (64 ml) at room temperature under nitrogen. The mixture was stirred overnight at room temperature, then diluted with ether, washed with water (x 2), dried (MgS04) and evaporated

in vacuo. Flash chromatography of the residue on silica gel, eluting with 8% methanol / dichloromethane, gave the title-ester (6.75 g, 59%), 1H NMR (250 MHz, CDCl3) # 0.89 (9H, t, J = 7.0 Hz, 3 of CH3), 1.06 - 1.72 (21H, m, CH3 and 9 of CH2), 4.45 (2H, q, J = 7.1 Hz, CH2O), 6.80 (1H, t, J = 1.4 Hz, Ar-H); MS (ES+) m/e 428 [MH]+. b) Ethyl 5-(pyridin-3-yl)isoxazole-3-carboxylate A mixture of the preceding ester (3.50 g, 8. 14 mmol), 3- bromopyridine (0.53 ml, 5.5 mmol) and Pd (PPh3)2Cl2 (0.105 g) in dioxane (40 ml) was heated at reflux under nitrogen for 4 h. The solvent was evaporated in vacuo and the residue partitioned between dichloromethane and water. The aqueous layer was separated and extracted further with dichloromethane (x 2). The combined extracts were dried (MgSO4) and evaporated in vacuo, and the residue chromatographed on silica gel, eluting with 50% ethyl acetate / hexane, to give the required product (1.07 g, 60%), lH NMR (250 MHz, CD Cl3) 1.46 (3H, t, J = 7.2 Hz, CH3), 4.49 (2H, q, J = 7.2 Hz, CH2), 7.05 (1H, s, Ar-H), 7.48 (1H, m, Ar-H), 8.14 (1H, m, Ar-H), 8.72 (1H, m, Ar-H), 9.07 (1H, d, J = 1.6Hz, Ar-H); MS (ES+) m/e 219 [MH]+. c) 5-(Pryidin-3-yl)isoxazole-3-hydrazoic acid Hydrazine monohydrate (0.56 ml, 11.5 mmol) was added to a stirred solution of the preceding ester (0.852 g, 3.90 mmol) in methanol (9 ml) at room temperature. After 2 h, the solvent was evaporated ill vacuo and the residue azeotroped with ethanol to give the title-hydrazoic acid (0.804 g, 100%), lH NMR (250 MHz, d6-DMSO) 4.66 (2H, br s, NH2), 7.51 (1H, s, Ar-H), 7.60 (1H, m, Ar-H), 8.32 (1H, m, Ar-H), 8.72 (1H, m, Ar-H), 9.15 (1H, m, Ar-H), 10.10 (1H, br s, NH); MS (ES+) m/e 205 [MH]+. d) 6-Chloro-3- r5-(pvridin-3-irl)isoxazol-3-vll - 1,2. 4-triazolo [3,4- alphthalazine A mixture of the preceding hydrazoic acid (798 mg, 3.91 mmol), 1,4- dichlorophthalazine (778 mg, 3.91 mmol) and triethylamine (0.54 ml, 3.9 mmol) in xylene (28 ml) was heated at reflux under nitrogen for 20.5 h.

The mixture was colled to room temperature, the solvent evaporated in vacuo and the residue partitioned between dichloromethane and water.

The aqueous was separated and re-extracted with dichloromethane (x 2).

The combined extracts were dried (MgSO4), evaporated in vacuo and the residue chromatographed on silica gel eluting with ethyl acetate, then 5% methanol / dichloromethane to afford the title-phthalazine (77 mg, 6%), lH NMR (360 MHz, CDCl3 / d6-DMSO) 5 7.51 (1H, m, Ar-H), 7.55 (1H, s, Ar-H), 7.99 (1H, m, Ar-H), 8.11 (1H, m, Ar-H), 8.24 (1H, m, Ar-H), 8.38 (1H, d, J = 7.8 Hz, Ar-H), 8.78 (1H, m, Ar-H), 8.83 (1H, m, Ar-H), 9.18 (1H, br s, Ar-H); MS (ES+) m/e 349 [MH]+.

4) 3-[5-(Pyridin-3-yl)isoxazol-3-yl]-6-(2-pyridyl)methyloxy-1,2 ,4- triazolo[3,4-a]phthalazine The title-compound was prepared from the preceding product and 2- pyridylcarbinol using the procedure given for Example 1, lH NMR (360 <BR> <BR> <BR> <BR> MHz, CDCl3) # 5.83 (2H, s, CH2), 7.29 (1H, m, Ar-H), 7.50 (1H, d, J = 8.0 and 4.8 Hz, Ar-H), 7.57 (1H, s, Ar-H), 7.74 - 7.77 (2H, m, 2 of Ar-H), 7.87 (1H, m, Ar-H), 7.97 (1H, m, Ar-H), 8.26 (1H, m, Ar-H), 8.36 (1H, d, J = 7.8 Hz, Ar-H), 8.62 - 8.76 (3H, m, 3 of Ar-H), 9.22 (1H, d, J = 1.7 Hz, Ar-H); MS (ES+) m/e 422 [MH]+.

EXAMPLE 36 6-(2-Pyridyl)methyloxy-3-[5-(2-thienyl)isoxazol-3-yl]-1,2,4- triazolo[3,4- alphthalazine The title-compound was prepared from ethyl 5- (2-thienyl)isoxazole - 3-carboxylate (J. Org. Chem., 1961, 26, 1514) using the procedure given for Example 1, mp 213-215 °C; 1H NMR (360 MHz, CDCl3), 5 5.81 (2H, s, CH20), 7.20 (1H, m, Ar-H), 7.28 - 7.29 (2H, m, 2 of Ar-H), 7.52 (1H, m, Ar-H), 7.68 (1H, m, Ar-H), 7.75 - 7.77 (2H, m, 2 of Ar-H), 7.84 (1H, m, Ar-H), 7.95 (1H, m, Ar-H), 8.34 (1H, d, J = 7.9 Hz, Ar-H), 8.65 - 8.72 (2H, m, 2 of Ar-H); MS (ES+) m/e 427 [MH]+. Anal. Found. C, 62.30; H, 3.07; N.

19.34. C22h14N6O2S requires C, 61.96; H, 3.31; N, 19.71%.

EXAMPLE 37 3-(5-Methylisoxazol-3-yl)-6-(1-methyl-1,2,4-triazol-3-yl)met hyloxy- 1,2,4-triazolo[3,4-a]phthalazine The title compound was prepared from Intermediate 1 and 1-methyl 1,2,4-triazole-3-methanol (prepared using the conditions of Itoh and Okongi, EP-A-421210) following the procedure given in Example 1, mp 249 - 251 °C; lH NMR (360 MHz, CDCl3), 5 2.59 (3H, d, J = 0.7 Hz, Me), 3.97 (3H, s, Me), 5.71 (2H, s, CH2), 6.98 (1H, d, J = 0.7 Hz, Ar-H), 7.80 (1H, t, J = 7.2 Hz, Ar-H), 7.94 (1H, t, J = 8.2 Hz, Ar-H), 8.09 (1H, s, Ar-H), 8.26 (1H, d, J = 7.7 Hz, Ar-H); 8.70 (1H, d, J = 7.0 Hz, Ar-H); MS (ES+) m/e 363 [MH]+.

EXAMPLE 38 7, 10-Difluoro-3-(S-methylisoxazol-3-yfl-6-(2-ovndyl)methlyoxy- 1,2,4-triazolo[3,4-a]phthalazine a) 5,8-Difluorophthalazine-1,4-dione 3,6-Difluorophthalic anhydride (10 g, 54 mmol) was added to a mixture of sodium acetate trihydrate (10 g, 73 mmol) and hydrazine hydrate (5 ml, 156 mmol) in 40% aqueous acetic acid. The reaction was heated under reflux conditions for 16 h and the reaction was filtered to give the title-compound as a white solid (10.5 g, 98%), lH NMR (250 MHz, d6-DMSO) 5 8.01 (2H, t, J = 9Hz), 11.50 - 11.80 (2H, br s). b) 1,4-Dichloro-5-8-difluroophthalazine The preceding dione (10.5 g, 18.9 mmol) was suspended in phosphorous oxychloride (200 ml) and then heated to reflux for 16 h. The solvent was removed by evaporation and the residue was treated with ice and basified with solid sodium hydrogen carbonate. The reaction was extracted with dichloromethane (3 x 100 ml), dried (MgSO4), filtered and evaporated to yield the title-compound as a yellow solid (10.1 g) used without further purification in the next step.

c) 6-Chloro-7,10-difluoro-3-(5-methylisoxazol-3-yl)-1,2,4-triaz olo[3,4-a]- phthalazine The title compound was prepared from the preceding dichlorophthalazine according to the procedure given for Intermediate 1, 1H NMR (250 MHz, d6-DMSO) # 2.59 (3H, d, J = 1Hz), 7.00 (1H, d, J = 1Hz), 7.95 (1H, dt, J = 9 and 4Hz); MS (ES+) m/e 322 [MH]+. d) 7,10-Difluoro-3-(5-methylisoxazol-3-yl)-6-(2-pyridyl)methyly oxy- 1,2,4-triazolo[3,4-a]phthalazine The title compound was prepared from the preceding chlorophthalazine and 2-pyridyl carbinol according to the procedure given for Example 1. lH NMR (250 MHz, CDCl3/CD30D 1:1) 5 2.63 (3H, d, J = lHz), 5.78 (2H, s), 6.92 (1H, d, J = lHz), 7.40 - 7.45 (1H, m), 7.70 (1H, dt, J = 9 and 4Hz), 7.84 - 7.92 (3H, m) 8.94 (1H, d, J = 5Hz); MS (ES+) m/e 395 [MH]+.

INTERMEDIATE 3 6-Chloro-7-fluoro-3-(5-methylisoxazol-3-yl)-1,2,4-triazolo[3 ,4-a]phthalazine and 6-chloro-10-fluoro-3-(5-methylisoxazol-3-yl)-1,2,4- triazolo[3,4-a]phthalazine The title compounds were prepared from 3-fluorophthalic anhydride according to the procedure given for Example 38 part c. Intermediate 3 was separated into its constituent isomers by column chromatography on silica gel using dichloromethane/toluene/ethyl acetate (2:2:1) to yield Intermediate 3(a) (less polar isomer): 6-chloro-7-fluoro-3-(5- methylisoxazol-3-yl)-1,2,4-triazolo[3,4-a]phthalazine; 1H NMR (250 MHz, <BR> <BR> <BR> CDCl3) # 2.59 (3H, d, J = lHz), 6.90 (1H, d, J = lHz), 7.26 (1H, s), 7.80 (1H, t, J = 9 Hz), 7.89 - 7.98 (1H, m), 8.19 (1H, d, J = 9Hz); MS (ES+) m/e 304 [MH] + and Intermediate 3(b) (more polar isomer): 6-chloro-10-fluoro-3-(5- methylisoxazol-3-yl)-1,2,4-triazolo[3,4]phthalazine; lH NMR (250 MHz, <BR> <BR> <BR> CDCl3) # 2.59 (3H, d, J = 1Hz), 6.89 (1H, d, J = 1Hz), 7.61 (1H, ddd, J = 13, 8 and 1Hz), 8.03 (1H, dt, J = 8 and 5 Hz), 8.67 (1H, d, J = 13Hz).

EXAMPLE 39 6,10-Bis[(2-pyridyl)methyloxy]-3-(5-methylisoxazol-3-yl)- 1,2,4-triazolo[3,4-a]phthalazine Intermediate 3(b) (0.1 g, 0.33 mmol) was added to a mixture of 2-pyridylmethanol (0.1 g, 0.9 mmol) and lithium hexamethydisilazane (1M in THF, 1 ml, 1 mmol) in DMF (5 ml) and stirred for 16 h. The reaction mixture was poured into water, extracted with dichloromethane, dried (MgSO4), filtered and evaporated to yield an oil which was purified by chromatography on silica using 3% methanol/dichloromethane to yield the title-product as a pale yellow powder (47 mg, 30%); 1H NMR (250 MHz, CDCl3) 5 2.59 (3H, s), 5.41 (2H, s), 5.78 (2H, s), 6.83 (1H, d, J = 1Hz), 7.18 - 7.38 (2H, m), 7.36 (1H, d, J = 8Hz), 7.49 - 7.68 (4H, m), 7.87 (1H, t, J = 8Hz), 8.36 (1H, d, J = 8Hz), 8.58 - 8.64 (2H, m); MS (ES+) m/e 466 [MH]+.

EXAMPLE 40 7-fluoro-3-(5-methylisoxazol-3-yl)-6-(2-pyridyl)methlyoxy- 1,2,4-triazolo[3,4-a]phthalazine and 10-fluoro-3-(5-methylisoxazol-3-yl)- 6-(2-pyridyl)methyloxy-1,2,4-triazolo[3,4-a]phthalazine The title compounds were prepared from Intermediate 3 and 2-pyridyl carbinol according to the procedure given for Example 1. The mixture was separated into its component isomers by column chromatography on silica to yield less polar isomer: 7-fluoro-3-(5- methylisoxazol-3-yl)-6-(2-pyridyl)methyloxy-1,2,4-triazolo ,4-alphthalazine; 1H NMR (250 MHz, CD Cl3) 5 2.61 (3H, s), 5.78 (2H, s), 6.84 (1H, s), 7.26 - 7.31 (1H, m), 7.49 - 7.56 (1H, m), 7.79 -7.81 (2H, m), 7.91 - 7.99 (1H, m), 8.54 (1H, d, J = 8Hz), 7.86 - 7.88 (1H, m); MS (ES+) 377 (MH)+ and the more polar isomer: 10-fluoro-3-(5-methylisoxazol-3-yl)- 6-(2-pvridvl)methlvoxv- 1,2,4-triazolo[3,4-a]phthalazine; 'H NMR (250 MHz, CDCl3) 5 2.59 (3H, s), 5.77 (2H, s), 6.83 (1H, s), 7.24 -7.32 (1H, s),

7.63 - 7.84 (4H, m), 8.15 (1H, d, J = 8Hz), 8.64 - 8.66 (1H, m); MS (ES+) 377 [MH]+.

EXAMPLE 41 6-(1-Mehylimidazol-4-yl)methyloxy-3-(5-methylisoxazol-3-yl)- 1,2,4- triazolo r3, 4-alphthalazine The title-compound was prepared from Intermediate 1 and 1- methyl-4-hydroxymethylimidazole (J. Org. Chem., 1968, 33, 3758) using the procedure given for Example 1, mp 207.5-209°C; lH NMR (360MHz, CDCl3) # 2.59 (3H, s, Me), 3.69 (3H, s, Me), 5.60 (2H, s, CH2), 6. 91 (1H, d, J = 0.8Hz, Ar-H), 7.43 (1H, s, Ar-H), 7.58 (1H, s, Ar-H), 7.76 (1H, td, J = 7.7 and 1.1Hz, Ar-H), 7. 91 (1H, td, J = 7.5 and 1.1Hz, Ar-H), 8.26 (1H, d, J = 8.0Hz, Ar-H), 8.65 (1H, d, J = 8.0Hz, Ar-H); MS(ES+) m/e 362 [MH]+; Anal. Found. C, 59.73; H, 3.85; N, 27.48. C18H15N7O2 requires C, 59.83; H, 4.18; N, 27.13%.

EXAMPLE 42 6-(1-methylimidazol-5-yl)methyloxy-3-(5-methylisoxazol-3-yl) - 1,2,4-triazolo[3,4-a]phthalazine a) 5- (tert-Butyldimethylsilyloxymethyl) - 1 -methylimidazole To a solution of 4-(tert-butyldimethylsilyloxymethyl)imidazole (Amino, Y.; Eto, H; Eguchi, C. Chem. Pharm. Bull. 1989, 37, 1481-1487) (3.158g, 14.9mmol) in anhydrous THF (25ml), cooled to-78°C under nitrogen, was added a 1.6M solution of butyl-lithium in hexanes (10.2ml, 16.4mmol). The mixture was stirred under nitrogen at - 78°C for 30 min, then iodomethane (0.97ml, 15.6mmol) was added. The mixture was allowed to warm to room temperature and stirred for 5h. Water (150ml) was added and the mixture extracted with diethyl ether (150ml). The organic extract was washed with brine, dried (MgSO4) and evaporated in vacuo. The product isomers were separated by flash chromatography on alumina, eluting with 40% ethyl acetate/hexane to yield the title-imidazole

(1.463g, 43%), 1H NMR (250 MHz, CDCl3), # 0.05 (6H, s), 0.88 (9H, s), 3.67 (3H, m), 4.65 (2H, s), 6.90 (1H, s), 7.41 (1H, s). b) 5-Hydroxymethyl-1-methylimidazole To a solution of 5-tert-butyldimethylsilyloxymethyl-1-methyl imidazole (from step a) (0.100g, 0.442mmol) in ethanol (0.5ml) and methanol (lml) was added 4M aqueous NaOH (0.165ml, 0.66mmol) and the mixture heated at 50°C for 16hrs. The mixture was evaporated in vacuo and the residue was purified by flash chromatography on silica gel, eluting with dichloromethane/methanol/ammonia (aq), (80:20:2) to give (31.3mg, 63%) of the title-alcohol, lH NMR (250 MHz, CDCl3) 6 3.71 (3H, s), 4.62 (2H, s), 6.87 (1H, s), 7.38 (1H, s). c) 6-(1-methylimidazol-5-yl)methyloxy-3-(5-methylisoxazol-3-yl) - 1,2,4-triazolo[3,4-a]phthalazine The title compound was prepared from the preceding alcohol and Intermediate 1 using the procedure given for Example 1, mp 236.5 - 237.5°C; lH NMR (360 MHz, CDCl3) 6 2.59 (3H, d, J = 0.7 Hz; CH3), 3.77 (3H, s, CH3), 5.69 (2H, s, CH2), 6.86 (1H, d, J = 0.8 Hz, Ar-H), 7.38 (1H, s, Ar-H), 7.55 (1H, s, Ar-H), 7.80 (1H, m, Ar-H), 7.96 (1H, m, Ar-H), 8.15 (1H, d, J = 7.8 Hz; Ar-H), 8.80 (1H, d, Ar-H); MS (ES+) m/e 362 [MH]+; Anal.

Found. C, 59.67; H, 3.84; N, 26.97. C18H15N7O2 required C, 59.83; H, 4.18; N, 27.13%.

EXAMPLE 43 3-(5-Methylisoxazol-3-yl)-6-(2-methyl-1,2,4-triazol-3-yl)met hyloxy-1,2,4- triazolo[3,4-a]phthalazine The title-compound was prepared from Intermediate 1 and 1-methyl-1,2,4-triazole-5-methanol (prepared using the conditions of Itoh and Okongi, EP-A-421210) following the procedure given in Example 10, mp 256-258°C; lH NMR (360 MHz, CDCl3) 6 2.57 (3H, s, CH3), 4.11 (3H, s, CH3), 5.83 (2H, s, CH2), 6.85 (1H, s, Ar-H), 7.84 (1H, t, J = 7.3 Hz, Ar-H), 7.92 (1H, s, Ar-H), 7.97 (1H, t, J = 7.1 Hz, Ar-H), 8.24 (1H, d, J = 8.1 Hz,

Ar-H), 8.70 (1H, d, J = 7.3 Hz, Ar-H). MS (ES+) m/e 363 [MH]+; Anal.

Found. C, 56.30; H, 3.49; N, 30.53. C17H14N8O2 C, 56.35; H, 3.89; N, 30.92%.

EXAMPLE 44 3-(5-Methylisoxazol-3-yl)-6-(4-methyl-1,2,4-triazol-3-yl)met hyloxy-1,2,4- triazolo[3,4-a]phthalazine The title-compound was prepared from Intermediate 1 and 4-methyl-1,2,4-triazole-3-methanol (prepared using the conditions of Itoh and Okongi, EP-A-421210) following the procedure given in Example 10, mp 261-263°C; 1H NMR (360 MH2, CDCl3) 6 2.58 (3H, s, Me), 3.90 (3H, s, Me), 5.90 (2H, s, CH2), 6.90 (1H, s, Ar-H), 7.82 (1H, m, Ar-H), 7.98 (1H, m, Ar-H), 8.14 (1H, s Ar-H), 8.20 (1H, s, Ar-H), 8.70 (1H, d, J = 7.4 Hz, Ar-H); MS (ES+) m/e 363 [MH]+; Anal. Found. C, 50.22; H, 4.23; N, 27.45. C17H14N8O2 requires 50.68; H, 4.62; N, 27.81%.

EXAMPLE 45 3-(5-Methylisoxazol-3-yl)-6-[2-{[2-(trimethylsilyl)ethoxy]me thyl}-1,2,4- triazolyll methyloxy- 1.2, 4-triazolo [3,4-a]phthalazine a) 1-[2-(trimethylsilyl)ethoxy]methyl-1,2,4-triazole To a suspension of sodium hydride (4.63g, 0.12mol) in tetrahydrofuran (150ml) was added 1,2,4-triazole (8.0g, 0.12mol) at room temperature under nitrogen. The mixture was cooled to 0°C and 2-(trimethylsilyl)ethoxymethylchloride (20.5ml, 0.12mol) added dropwise.

The mixture was stirred at room temperature overnight, water (100ml) was added and the mixture diluted with ethyl acetate. The organic layer was dried ((MgSO4) and evaporated in vacuo and the residue distilled to give the title-compound (14.6g, 63%), bp 110°C at 5mm Hg; lH NMR (250 MHz, CD Cl3) 6 0.01-0.03 (9H, s, 3 of CH3), 0.93 (2H, m, CH2), 3.63 (2H, m, CH2), 5.52 (2H, s, CH2), 7.99 (1H, s, Ar-H), 8.26 (1H, s Ar-H).

b) 2-[2-(Trimethylsilyl)ethoxymethyl]-1,2,4-triazole-3-carboxal dehyde To a solution of the preceding triazole (10.0g, 0.05mol) in tetrahydrofuran (160ml) was added n-butyl lithium (36.1ml, 0.06mol of a 1.6M solution in hexane) at - 78°C under nitrogen. The mixture was stirred for 0.25h and N,N-dimethylformamide (3.88ml, 0.05mol) added.

The mixture was left to warm to 0°C over 2h. Saturated ammonium chloride solution was added (25ml) and the mixture extracted with ethyl acetate (3 x 100ml), dried (Na2SO4) and evaporated in vacuo. The residue was flash chromatographed on silica gel, eluting with 35% ethyl acetate/hexane, to give the title-product (7.70g, 68%), lH NMR (250 MHz, CD Cl3) 5 0.02-0.03 (9H, s, 3 of CH3), 0.95 (2H, m, CH2), 3.68 (2H, m CH2), 5.89 (2H, s, CH2), 8.12 (1H, s, Ar-H), 10.07 (1H, s, CHO). c) 3-(Hydroxymethyl)-2-{[2-(trimethylsilyl)ethoxy]methyl}- 1,2,4-triazole To a solution of the preceding aldehyde (7.70g, 0.034mol) in methanol (120ml) at room temperature under nitrogen was added sodium borohydride (1.2g, 0.034mol) portionwise. After 1h, the mixture was diluted with dichloromethane (150ml) and washed with water (3x), dried (MgSO4) and evaporated in vacuo. The residue was flash chromatographed on silica gel, eluting with 70% ethyl acetate/hexane, to give the title-product (4.0g, 52%), 1H NMR (360 MHz. CDCl3) 5 0.06-0.10 (9H, s, 3 of CH3), 0.93 (2H, m, CH2), 3.63 (2H, m, CH2), 4.16 (1H, br s, OH), 4.87 (2H, br s, CH2), 5.58 (2H, s, CH2), 7.85 (1H, s, Ar-H). d) 3-(5-Methylisoxazol-3-yl)-6-[2-{[2-(trimethylsilyl)ethoxy]me thyl}- 1,2,4-triazolyl]methyloxy - 1,2,4-triazolo[3,4-a]phthalazine The title-compound was prepared from Intermediate 1 and the preceding alcohol, using the procedure given for Example 1, mp 153-155°C; 1H NMR (360MHz, CD Cl3) 6 0.04 (9H, s, 3 of CH3), 0.89 (2H, t, J = 8.2 Hz, CH2), 2.61 (3H, s, me), 3.67 (2H, t, J = 8.0 Hz, CH2), 5.83 (2H, s, CH2), 5.90 (2H, s, CH2), 6.89 (1H, d, J = 0.7 Hz, Ar-H), 7.85 (1H, t, J = 7.2 Hz, Ar-H).

7.98 (1H, s, Ar-H), 8.01 (1H, t, J = 7.3 Hz, Ar-H), 8.33 (1H, d, J = 8.0 Hz,

Ar-H), 8.78 (1H, d, J = 7.4 Hz, Ar-H); MS (ES+) m/e 479 [MH]+; Anal.

Found. C, 55.38; H, 5.16; N, 23.26; C22H26N8O3Si requires C, 55.21; H, 5.48; N, 23.41%.

EXAMPLE 46 3-(5-Methylisoxazol-3-yl)-6-(1,2,4-triazol-3-yl)methyloxy-1, 2,4- triazolo[3,4-a]phthalazine To a solution of 3-(5-methylisoxazol-3-y1)-6-[2-([2- (trimethylsilyl)ethoxy] methyl)- 1,2, 4-triazolyl] methyloxy- 1,2, 4-triazolo- [3,4-a]phthalazine (1.20g, 2.5mmol) in ethanol (20ml) was added 2N hydrochloric acid (40ml) at room temperature. The mixture was heated at 60°C for 5h, saturated potassium carbonate solution was added and the solvent evaporated in vacuo. The solid was triturated with ethanol, filtered and the filtrate evaporated in vacuo. The residue was flash chromatographed on silica gel, eluting with 4% methanol/dichloromethane, to give the title-product (140mg, 16%), mp 260-262°C; 1H NMR (360 MHz, d6-DMSO) 6 2.56 (3H, s, me), 5.75 (2H, s, CH2), 7.24 (1H, s, Ar-H), 8.00 (1H, t, J = 8.1 Hz, Ar-H), 8.14 (1H, t, J = 7.7 Hz, Ar-H), 8.26 (1H, d, J = 8.0 Hz, Ar-H), 8.60 (1H, br s, NH), 8.65 (1H, d, J = 7.4 Hz, Ar-H); MS (ES+) m/e 349 [MH]+.

EXAMPLE 47 3-(5-Methylisoxazol-3-yl)-6-(1-isopropyl-1,2,4-triazol-3-yl) methyloxy-1,2,4- triazolo r3,4-alphthalazine To a stirred solution of 3-(5-methylisoxazol-3-yl)-6-(1, 2, 4-triazol- 3-yl)methyloxy- 1,2,4-triazolo [3, 4-a]phthalazine (100mg, 0.29mmol) in NN-dimethylformamide (6ml) at room temperature under nitrogen was added sodium hydride (17mg, 0.4lmmol). The mixture was cooled to 0°C and 2-iodopropane (0.04ml, 0.36mmol) added after 0.25h. The mixture was left to stir at room temperature overnight, water was added and the precipitate filtered off. The crude product was flash chromatographed on

silica gel, eluting with ethyl acetate # 4% methanol/ethyl acetate, to give the title-product (25mg, 22%), mp 179-181°C; lH NMR (360 MHz, CD Cl3) 6 1.58 (6H, d, J = 6.7 Hz, 2 of CH3), 2.59 (3H, s, CH3), 4.58 (1H, septet, J = 6.7 Hz, CH), 5.72 (2H, s, CH2), 7.01 (1H, s, Ar-H), 7.78 (1H, t, J = 7.2 Hz, Ar-H), 7.94 (1H, t, J = 7.6 Hz, Ar-H), 8.13 (1H, s, Ar-H), 8.28 (1H, d, J = 7.9 Hz, Ar-H), 8.80 (1H, d, J = 7.4 Hz, Ar-H); MS (ES+) m/e 391 [MH]+; Anal. Found. C, 56.81; H, 4.68; N, 27.89; C19H18N8O2#0.7H2O requires C, 56.62; H, 4.85; N, 27.80%.

EXAMPLE 48 3-(5-Methylisoxazol-3-yl)-6-(-1-ethyl-1,2,4-triazol-3-yl)met hyloxy-1,2,4- triazolo[3,4-alphthalazine The title-compound was prepared from 3-(5-methylisoxazol-3-yl)-6- (1,2,4-triazol-3-yl)methyloxy-1,2,4-triazolo[3,4-a]phthalazi ne and iodoethane following the procedure given for Example 47, lH NMR (360 MHz, CD Cl3) 5 1.56 (3H, t, J = 7.3 Hz, Me), 2.59 (3H, s, Me), 4.26 (2H, q, J = 7.3 Hz, CH2), 5.72 (2H, s, CH2), 7.00 (1H, s, Ar-H), 7.78 (1H, t, J = 7.3 Hz, Ar-H), 7.94 (1H, t, J = 7.7 Hz, Ar-H), 8.11 (1H, s, Ar-H), 8.29 (1H, d, J = 8.1 Hz, Ar-H), 8.70 (1H, d, J = 7.4 Hz, Ar-H); MS (ES+) m/e 377 [MH]+.

EXAMPLE 49 3-(5-methylisoxazol-3-yl)-6-(1H-1,2,3-triazol-5-yl)-methylox y-1,2,4- triazolo[3,4-a]phthalazine a) 5-Formyl-1-[2-(trimethylsilyl)ethoxy]methyl-1,2,3-triazole n-Butyl lithium (6.8ml of a 1.6M solution in hexanes, 10.9mmol) was added dropwise over 0.08h to a stirred solution of 1-[2-(trimethyl- silyl)ethoxy]methyl-1,2,3-triazole (J. Heterocycl. Chem., 1992, 29, 1203) (2.077g, 10.42mmol) in THF (30ml) at-78°C under nitrogen. The solution was allowed to warm to -60°C over 0.67h, then recooled to -78°C and DMF (0.9ml, 11.6mmol) added. The mixture was allowed to warm to room temperature and stirred for 16.5h. Saturated ammonium chloride solution

(50ml) was added and the reaction mixture extracted with diethyl ether (3 x 80ml). The combined ethereal ex trants were dried (MgSO4), evaporated in vacuo, and the residue chromatographed on silica gel, eluting with 30% ethyl acetate/hexane, to give the title-triazole (1.713g, 72%), lH NMR (360 MH2, CD Cl3) 6 0.01 (9H, s, Me3Si), 0.92-0.99 (2H, m, CH2), 3.64-3.69 (2H, m, CH2), 6.05 (2H, s, CH2), 8.31 (1H, s, Ar-H), 10.12 (1H, s, CHO). b) 5-Hydroxymethyl-1-[2-(trimethylsilyl)ethoxy]methyl-1,2,3-tri azole Sodium borohydride (0.284g, 7.51mmol) was added to a stirred solution of the preceding triazole (1.704g, 7.495mmol) in methanol (8ml) at 0°C under nitrogen. The mixture was stirred at 0°C for 0.5h and at room temperature for 0.5h. Water was added and the mixture partitioned between dichloromethane and saturated brine. The aqueous layer was separated and further extracted with dichloromethane (x2). The combined organic layers were dried ((MgSO4) and evaporated in vacuo and the residue chromatographed on silica gel, eluting with 70% ethyl acetate/hexane, to give the title-product (1.34g, 78%), 1H NMR (360 MHz, CDCl3) 6 0.00 (9H, s, Me3Si), 0.90-0.95 (2H, m, CH2), 3.58-3.63 (2H, m, CH2), 4.84 (2H, s, CH2), 5.80 (2H, s, CH2), 7.68 (1H, s, Ar-H). c) 3-(5-Methvlisoxazol-3-vl)-6-f 1- [2-(trimethylsilyl)ethoxy] methyl- 1,2,3-triazol-5-yl}methyloxy-1,2,4-triazolo[3,4-a]phthalazin e The title-compound was prepared from Intermediate 1 and the preceding alcohol following the procedure described for Example 10, 360 MHz (360 MHz, CD Cl3) 6 0.00 (9H, s, Me3Si), 0.88-0.93 (2H, m, CH2), 2.63 (3H, s, Me), 3.61-3.66 (2H, m, CH2), 5.92 (2H, s, CH2), 5.97 (2H, s, CH2), 6.89 (1H, s, Ar-H), 7.86 (1H, m, Ar-H), 8.02 (1H, t, J = 7.7 Hz, Ar-H), 8.18 (1H, s, Ar-H), 8.23 (1H, d, J = 8.0 Hz, Ar-H), 8.76 (1H, d, J = 8.0 Hz, Ar-H); MS (ES+) m/e 479 [MH]+.

d) 3-(5-Methylisoxazol-3-yl)-6-(1H-1,2,3-triazol-5-yl)methyloxy -1,2,4- triazolo[3,4-a]phthalazine A mixture of the preceding product, ethanol (10ml) and 2N HCl (20ml) was heated at 50°C for 15.25h. The solution was basified to pH 12 with saturated sodium carbonate solution and the solvents evaporated in vacuo. The residue was azeotroped with ethanol (x2) and chromatographed on silica gel, eluting with 0-4% methanol/dichloromethane (gradient elution), to give the title-product, lH NMR (400 MHz, CDCl3)# 2.65 (3H, s, Me), 5.73 (2H, s, CH2), 7.02 (1H, s, Ar-H), 7.87 (1H, t, J = 7.8 Hz, Ar-H), 7.99-8.03 (2H, m, 2 of Ar-H), 8.24 (1H, d, J = 8.2 Hz, Ar-H) 8.72 (1H, d, J = 7.9 Hz, Ar-H); MS (ES+) m/e 349 [MH]+.

EXAMPLE 50 3-(5-Methylisoxazol-3-yl)-6-(1-methyl- 1,2, 3-triazol-5-vl)methvloxv- 1,2,4- triazolo[3,4-a]phthalazine, 3-(5-methylisoxazol-3-yl)-6-(2-methyl-1,2,3- triazol-4-yl)methyloxy- 1,2, 4-triazolo [3, 4-alohthalazine and 3 - (5-methvlisoxazol-3-vl)-6-(l-methvl- 1,2, 3-triazol-4-yl)methyloxy- 1,2,4- triazolo[3,4-a]phthalazine Lithium hexamethyldisilazide (1.63ml of a 1M solution in THF, 1.63mmol) was added dropwise to a stirred solution of 3-(5-methylisoxazol- 3-yl)-6-(1H- 1,2, 3-trazol-5-yl)methyloxy- 1,2, 4-triazolo [3,4-a]phthalazine (241mg, 0.626mmol) in DMF (50ml) at-31°C under nitrogen. The mixture was warmed to -23°C over 1.5h, methyl iodide (0.10ml, 1.6mmol) added dropwise and the reaction mixture allowed to warm to room temperature overnight. Water was added and the solvent evaporated in vacuo. The residue was partitioned between dichloromethane and water and the aqueous phase separated and re-extracted with dichloromethane (x1). The combined organic extrants were washed with brine (x1), dried (MgSO4) and evaporated in vacuo. Chromatography of the residue on silica gel, eluting with 0-5% methanol/dichloromethane (gradient elution), followed

bypreparative HPLC (YMC Sil column, 250 x 20mm) eluting with 5% methanol/1-chlorobutane, separated the triazole isomers: Least polar isomer (HPLC solvent system): 3-(5-methylisoxazol-3-yl)-6-(2- methyl-1,2,3-triazol-4-yl)methyloxy-1,2,4-triazolo[3,4-a]pht halazine lH NMR (400 MHz, CDCl3) # 2.59 (3H, s, Me), 4.21 (3H, s, Me), 5.73 (2H, s, CH2), 6.89 (1H, s, Ar-H), 7.79 (1H, m, Ar-H), 7.94 (1H, m, Ar-H), 8.10 (1H, s, Ar-H), 8.22 (1H, d, J = 8.0 Hz, Ar-H), 8.67 (1H, d, J = 8.0 Hz, Ar-H); MS (ES+) m/e 363 [MH]+.

Intermediate polarity isomer: 3-(5-methylisoxazol-3-vl)-6-(l-methvl- 1,2,3- triazol-4-yl)methyloxy-1,2,4-triazolo[3,4-a]phthalazine 1H NMR (400MHz, CDCl3) # 2.60 (3H, s, Me), 4.09 (3H, s, Me), 5.78 (2H, s, CH2), 6.90 (1H, d, J = 0.8 Hz, Ar-H), 7.80 (1H, m, Ar-H), 7.94 (1H, m, Ar-H), 8.25 (1H, d, J = 8.0 Hz, Ar-H), 8.65 (1H, d, J = 8.0 Hz, Ar-H), 8.73 (1H, s, Ar-H); MS (ES+) m/e 363 [MH]|.

Most polar isomer (HPLC solvent system): 3-(5-methylisoxazol-3-vl)-6-(1- methyl- 1,2,3-triazol-5-yl)methyloxy- 1,2, 4-triazolo [3,4-al phthalazine lH NMR (400 MHz, (CDCl3) # 2.56 (3H, s, Me), 4.19 (3H, s, Me), 5.76 (2H, s, CH2), 6.82 (1H, s, Ar-H), 7.80 (1H, m, Ar-H), 7.96 (1H, m, Ar-H), 8.04 (1H, s, Ar-H), 8.12 (1H, d, J = 8.8 Hz, Ar-H), 8.67 (1H, d, J = 8.0 Hz, Ar-H); MS (ES+) m/e 363 [MH]+.

EXAMPLE 51 3-(5-Methylisoxazol-3-yl)-6-[(5-trifluoromethyl)pyridin-2-yl ]methyloxy- 1,2,4-triazolo[3,4-a]phthalazine The title-compound was prepared from Intermediate 2 and 2-chloromethyl- 5-trifluoromethylpyridine (prepared from 2-methyl-5- trifluoromethylpyridine (Chem. Pharm. Bull. 1990, 38(9) 2446-58) following the procedure given for Example 15 part a) using the procedure given for Example 15 part b, mp 236-238 C; 1H NMR (360 MHz, CDCl3) 5 2.58 (3H, d, J = 0.6 Hz, Me), 5.83 (2H, s, CH2), 6.80 (1h, d, J = 0.7 Hz,

Ar-H), 7.84 (1H, t, J = 7.3Hz, Ar-H), 8.00-8.03 (4H, m, Ar-H), 8.31 (1H, d, J = 8.4 Hz, Ar-H), 8.70 (1H, d, J = 8.0 Hz, Ar-H). MS (ES+) m/e 427 [MH]+.

EXAMPLE 52 3-(5-Methylisoxazol-3-yl)-6-[(3-trifluoromethyl)pyridin-2-yl ]methyloxy- 1,2,4-triazolo[3,4-a]phthalazine The title-compound was prepared from Intermediate 2 and 2-chloromethyl-3-trifluoromethylpyridine (prepared from 2-methyl-3- trifluoromethylpyridine (Chem. Pharm. Bull. 1990, 38(9) 2446-58) following the procedure given for Example 15 part a) using the procedure given for Example 15 part b, mp 244-246°C; lH NMR (360 MHz, CD Cl3) 6 2.56 (3H, d, J = 1.1 Hz, Me), 5.94 (2H, s, CH2), 6.79 (1H, d, J = 1.2 Hz, Ar-H), 7.50 (1H, dd, J = 11.3 Hz and 11.0 Hz, Ar-H), 7.80 (1H, t, J = 10.4 Hz, Ar-H), 7.96 (1H, t, J = 9.8 Hz, Ar-H), 8.01 (1H, d, J = 11.4 Hz, Ar-H), 8.27 (1H, d, J = 11.1 Hz, Ar-H), 8.75 (1H, d, J = 9.4 Hz, Ar-H), 8.81 (1H, s, Ar-H); MS (ES+) m/e 427 [MH]+; Anal. Found. C, 56.06; H, 2.80; N, 19.53.

C20H13N6O2F3 requires C, 56.34; H, 3.07; N, 19.71%.

EXAMPLE 53 3-(5-Methylisoxazol-3-yl)-6-[(4-trifluoromethyl)pyridin-2-yl ]methyloxy- 1,2,4-triazolo[3,4-a]phthalazine The title-compound was prepared from Intermediate 2 and 2-chloromethyl-4-trifluoromethylpyridine (prepared from 2-methyl-4- trifluoromethylpyridine (Chem. Pharm. Bull. 1990, 38(9) 2446-58) following the procedure given for Example 15 part a) using the procedure given for Example 15 part b, mp 224-226°C; 'H NMR (360 MHz, CDCl3) 6 2.59 (3H, d, J = 0.8 Hz, CH3), 5.84 (2H, s, CH2), 6.82 (1H, d, J = 0.8 Hz, Ar-H), 7.51 (1H, d, J = 4.3 Hz, Ar-H), 7.83 (1H, t, J = 8.3 Hz, Ar-H), 8.00 (1H, t, J = 8.3 Hz, Ar-H), 8.12 (1H, s, Ar-H), 8.33 (1H, d, J = 7.7 Hz, Ar-H), 8.70 (1H, d, J = 8.0 Hz, Ar-H), 8.80 (1H, d, J = 8.0 Hz, Ar-H). MS (ES+)

m/e 427 [MH]+; Anal. Found, C, 56.42; H, 2.86; N, 19.47. C20H13N6O2F3 requires C, 56.34; H, 3.07; N, 19.71%.

EXAMPLE 54 3-(5-Mehylisoxazol-3-yl)-6-(thiazol-4-yl)-1,2,4-triazolo[3,4 -a]phthalazine a) 4-Hvdroxymethylthiazole A solution of m-chloroperbenzoic acid (57-58%, 61.1g, 0.2mol) in dichloromethane (500ml) was added dropwise to a stirred solution of 4-methylthiazole (20g, 0.2mol) in dichloromethane (200ml) at 0°C. When addition was complete the mixture was allowed to warm to room temperature and stirred for 18h. The solvent was evaporated in vacuo to half its volume and the m-chlorobenzoic acid filtered off. This was repeated five times to give the crude N-oxide (31g). The N-oxide (33g) was added slowly to acetic anhydride (60ml) at 110°C with stirring. The mixture was heated at this temperature for 18h, then cooled to room temperature and concentrated in vacuo. The residue was distilled in vacuo to give the crude acetate (9.58g), bp 106-110°C at 4 Torr. A solution of the acetate (9.58g) in methanol/HCl solution (1:1) was stirred at room temperature for 4h. The solvent was evaporated in vacuo and the residue partitioned between sodium hydroxide solution (4M) and dichloromethane. The aqueous phase was extracted into dichloromethane (6x) and the combined extracts were dried (MgSO4) and evaporated in vacuo. Flash chromatography on silica gel, eluting with 3% methanol/dichloromethane, gave the title-alcohol (1.22g, 23°), 1H NMR (250 MHz, CDCl3) 6 4.85 (2H, s, CH2), 7.27 (1H, m, Ar-H), 8.81 (1H, m, Ar-H); MS (ES+) m/e 115 [MH]+. b) 3-(5-methylisoxazol-3-yl)-6-(thiazol-4-yl)methyloxy-1,2,4- triazolo [3. 4-alohthalazine The title-compound was prepared from the preceding alcohol and Intermediate 1 using the procedure given for Example 10, mp 227-229°C; 1H NMR (360 MHz, CDCl3) 6 2.60 (3H, s, CH3), 5.85 (2H, s, CH2), 6.89 (1H,

s, Ar-H), 7.80 (1H, m, Ar-H), 7.94 (1H, m, Ar-H), 8.13 (1H, d, J = 2.0 Hz, Ar-H), 8.28 (1H, d, J = 8.4 Hz, Ar-H), 8.60 (1H, d, J = 2 Hz, Ar-H), 8.83 (1H, d, J = 2.0 Hz, Ar-H); MS (ES+) m/e 365 [MH]+; Anal. Found. C, 55.67; H, 3.08; N, 22.47; C17H12N6O2S0.25 H2O requires C, 55.35; H, 3.42; N, 22.78%.

EXAMPLE 55 3-(Isothiazol-3-yl)methyloxy-3-(5-methylisoxazol-3-yl)-1,2,4 - triazolo [3, 4-alphthalazine a) 3-Hydroxymethylisothiazole Lithium aluminium hydride (1M solution in tetrahydrofuran), (0.93ml, 0.9mmol) was added dropwise to a solution of ethyl isothiazole-3- carboxylate (J. Org. Chem., 1975, 40, 3381) (195mg, 0. 1mmol) in tetrahydrofuran at-40°C under N2. The mixture was stirred at-40°C for 45 min. Saturated sodium sulfate solution (lml) was added keeping the temperature below -300C. The mixture was allowed to warm to room temperature, stirred for 1h, then filtered and the filtrate evaporated in vacuo. The residue was purified by flash chromatographed on silica gel, using 30% ethyl acetate/hexane as eluant, to give the title-alcohol (47mg, 33%); lH NMR (250 MHz, CD Cl3) 6 4.86 (2H, s, CH2), 7.22 (1H, d, J = 4.7 Hz, Ar-H), 8.67 (1H, d, J = 5 Hz, Ar-H); MS (ES+) m/e 115 [MH]+. b) 6-(Isothiazol-3-yl)methyloxy-3-(5-methylisoxazol-3-yl)-1,2,4 - triazolo [3, phthalazine The title-compound was prepared from the preceding alcohol and Intermediate 1 using the procedure given for Example 1, mp 230-231°C; lH NMR (360 MHz, CDCl3) # 2.60 (3H, s, CH3), 5.84 (2H, s, CH2), 6.85 (1H, d, J = 0.7 Hz, Ar-H), 7.68 (1H, d, J = 4.6 Hz, Ar-H), 7.82 (1H, m, Ar-H), 7.96 (1H, m, Ar-H), 8.28 (1H, d, J = 7.8 Hz, Ar-H), 8.70 (1H, d, J = 8 Hz, Ar-H), 8.80 (1H, d, J = 4Hz, Ar-H); MS (ES+) m/e 365 [MH]+; Anal. Found.

C, 56.11; H, 3.20; N, 22.59. C17H12N6O2S0.1H2O requires C, 55.76; H, 3.36; N, 22.95%.

EXAMPLE 56 3-(5-Methylisoxazol-3-yl)-6-[(4-tert-butyl)pyridazin-3-yl]me thyloxy-1,2,4- triazolo[3,4-a]phthalazine The title-compound was preparaed from Intermediate 2 and 3- chloromethyl-4-tert-butylpyridazine (prepared from 3-methyl-4- tert-butyl pyridazine (Acta Chemica, 1967, 21, 2104-2210) following the procedure given for Example 15 part a) using the procedure given for Example 15 part b, mp 230-232°C; 1H NMR (360 MHz, CDCl3) 6 1.51 (9H, s, 3 of CH3), 2.57 (3H, s, CH3), 6.18 (2H, s, CH2), 6.87 (1H, d, J = 0.7 Hz, Ar-H), 7.55 (1H, d, J = 5.6 Hz, Ar-H), 7.74 (1H, t, J = 1 Hz, Ar-H), 7.93 (1H, t, J = 8.2 Hz, Ar-H), 8.18 (1H, d, J = 7.6 Hz, Ar-H), 8.90 (1H, d, J = 7.4 Hz, Ar-H), 9.11 (1H, d, J = 5.7 Hz, Ar-H); MS (ES+) m/e 416 [MH]+; Anal. Found. C, 60.75; H, 4.91; N, 22.19; C22H21N7O20.4H2O#0.2CH2Cl2 requires C, 60.65; H, 5.09; N, 22.30%.

EXAMPLE 57 3-(5-methylisoxazol-3-yl)-6-[(5-tert-butyl)pyridazin-3-yl]me thyloxy-1,2,4- triazolo[3,4-a]phthalazine The title-compound was prepared from Intermediate 2 and 3- chloromethyl-5-tert-butylpyridine (prepared from 3-methyl-4-tert-butyl pyridazine (Acta Chemica, 1967, 21, 2104-2210) following the procedure given for Example 15 part a) using the procedure given for Example 15 part b, mp 219-221°C; lH NMR (360 MHz, CDCl3) 6 1.33 (9H, s, 3 of CH3), 2.59 (3H, s, CH3), 5.97 (2H, s, CH2), 6.87 (1H, d, J = 0.8 Hz, Ar-H), 7.83 (1H, t, J = 8.2 Hz, Ar-H), 7.94 (1H, t, J = 8.8 Hz, Ar-H), 8.06 (1H, d, J = 2.3 Hz, Ar-H), 8.31 (1H, d, J = 7.7 Hz, Ar-H), 8.70 (1H, d, J = 7.4 Hz, Ar-H), 9.23 (1H, d, J = 2.5 Hz, Ar-H); MS (ES+) m/e 416 [MH]+; Anal. Found. C, 63,75; H, 5.04; N, 23.53; C22H21N702 requires C, 63.60; H, 5.10; N, 23.60%.

EXAMPLE 58 6-(Imidazol-4-yl)methyloxy-3-(5-methylisoxazol-3-yl)-1,2,4- triazolo[3,4-a]phthalazine a) 4-and 5-Hydroxymethyl-1-{[2-(trimethylsilyl)ethoxy]methyl} imidazole 4-Hydroxymethylimidazole (formed from the commercially available hydrochloride salt by treatment with saturated potassium carbonate solution and extraction into butanol) (1.08g, llmmol) was added to a stirred suspension of sodium hydride (60% dispersion in oil) (441mg, 1 lmmol) in N,N-dimethylformamide at 0°C under nitrogen. The mixture was stirred at 0°C for 1h then 2-(trimethylsilyl)ethoxymethyl chloride (1.95ml, llmmol) was added dropwise. The mixture was stirred for 15 min then warmed to room temperature and stirred for 2h. The solvent was evaporated in vacuo and the residue taken up in water and extracted into ethyl acetate (3x). The combined extracts were dried (MgSO4) and evaporated in vacuo.

Purification of the residue by flash chromatography on silica gel, eluting with 8% methanol/dichloromethane, gave a 1:1 mixture of the title-alcohols 1.5g, 60%), lH NMR (250 MHz, d6-DMSO 6 0.00 (9H, s), 0.88 (2H, m), 3.49 (2H, m), 4.37 and 4.51 (2H, d, J = 5.5 and 5.3 Hz,), 4.92 and 5.15 (1H, t, J = 5.5 and 5.3 Hz), 5.32 and 5.40 (2H, s), 6.87 and 7.12 (1H, s), 7.73 and 7.77 (1H, s); MS (ES+) m/e 229 [MH]+. b) 3-[(5-Methylisoxazol-3-yl)-6-[2-(trimethylsilyl)ethyloxy]met hyl imidazol-4-yl]methyloxy-1,2, 4-triazolo [3, 4-aluhthalazine and 3 - [(5- methylisoxazol-3-yl)-6-[2-(trimethylsilyl)ethyloxy]methylimi dazol-5- vl]methyloxy-1,2,4-triazolo[3,4-a]phthalazine The title-compounds were prepared from the preceding mixture of alcohols and Intermediate 1 using the procedure given in Example 1 and using lithium bis (trimethylsilyl) amide (1.OM solution in tetrahydrofuran) as base, 1H NMR (250 MHz, CD Cl3) 6 0.00 (9H, s), (0.91 (2H, m), 2.65 (3H, d, J = 0.6 Hz), 3.55 (2H, m), 5.32 and 5.51 (2H, s), 5.69 and 5.81 (2H, s), 6.93 and 6.96 (1H, s), 7.50 and 7.87 (1H, s), 7.71 and 7.66 (1H, s), 7.84 (1H,

m), 7.99 (1H, m), 8.22 and 8.33 (1H, d, J = 8.0 and 7.4 Hz), 8.74 (1H, m); MS (ES+) m/e 478 [MH]+. c) 6-(imidazol-4-yl)methyloxy-3-[(5-methylisoxazol-3-yl)-1,2,4- triazolo[3,4-a]phthalazine The preceding mixture of compounds (180mg, 0.4mmol) was treated with 2M HCl solution (20ml) and ethanol (10ml) and the mixture heated under reflux for 5h. After cooling to room temperature, the mixture was basified to pH 9 using saturated potassium carbonate solution and evaporated in vacuo. Purification of the residue by flash chromatography on silica gel using 4% methanol/dichloromethane as eluant, followed by recrystallisation from dichloromethane gave the title-compound (69mg, 53%); mp 179-181°C; 1H NMR (360 MHz, d6-DMSO), 6 2.60 (3H, s, CH3), 5.54 (2H, s, CH2), 7.18 (1H, s, Ar-H), 7.44 (1H, br s, Ar-H), 7.72 (1H, s, Ar-H), 7.93 (1H, m, Ar-H), 8.08 (1H, m, Ar-H), 8.16 (1H, d, J = 7.9Hz, Ar-H), 8.56 (1H, d, J = 8.0 Hz, Ar-H); MS (ES+) m/e 348 [MH]+; Anal.

Found. C, 55.10; H, 3.90; N, 26.23. C17H13N7O2#0.35 CH2Cl2 requires C, 55.27; H, 3.66; N, 26.00%.

EXAMPLE 59 3-[(5--Methylisoxazol-3-yl)-6-(1-methyl-1,2,4-triazol-3-yl)m ethylamino- 1,2,4-triazolo[3,4-a][phthalazine a) 1-Methyl-1,2,4-triazole-3-methylamine hydrochloride 1-Methyl- 1,2, 4-triazole-3-methanol (500mg, 4.4mmol) was added to ice-cold thionyl chloride (5ml, 69mmol). The mixture was heated at reflux for 0.75h, then cooled to room temperature and evaporated in vacuo. The residue was partitioned between dichloromethane and aqueous sodium bicarbonate solution and the aqueous layer separated and further extracted with dichloromethane (x2). The combined organic extracts were dried (MgSO4) and evaporated in vacuo. The residue was treated with 33% w/w aqueous ammonia (5ml) and the mixture heated in a sealed tube at 80°C for 16h. After cooling to room temperature, the reaction mixture

was evaporated in vacuo and azeotroped with ethanol to give the title-amine (600 mg, 92%), 1H NMR (250 MHz, d6-DMSO) # 3.88 (3H, s, Me), 4.04 (2H, s, CH2), 8.36 (2H, br s, NH2), 8.58 (1H, s, Ar-H). b) 3-(5-Methylisoxazol-3-yl)-6-(1-methyl-1,2,4-triazol-3- yl)methylamino- 2 4-triazolo [3, 4-alphthalazine A mixture of Intermediate 1 (200mg, 0.700mmol), the preceding amine hydrochloride (125mg, 0.841mmol) and triethylamine (0.7ml, 5.0mmol) in DMSO (11ml) was heated at 100°C under nitrogen for 48h.

The mixture was cooled to room temperature, water added and the solvents evaporated in vacuo. The residue was partitioned between dichloromethane and water and the organic layer separated, washed with water (x2), dried (MgSO4) and evaporated in vacuo. Flash chromatography of the residue on silica gel, eluting with 1-10% methanol/dichloromethane (gradient elution) followed by recrystallisation (ethyl acetate) gave the title-product (5mg, 2%), lH NMR (360MHz, CDCl3/d6-DMSO) # 2.60 (3H, s, Me), 3.93 (3H, s, Me), 4.85 (2H, d, J = 4.8 Hz, CH2), 6.93 (1H, m, NH), 7.10 (1H, s, Ar-H), 7.78 (1H, m, Ar-H), 7.89 (1H, m, Ar-H), 8.07-8.10 (2H, m, 2 of Ar-H), 8.70 (1H, d, J = 8 Hz, Ar-H); MS (ES+) m/e 362 [MH]+.

EXAMPLE 60 3-(5-Methylisoxazol-3-yl)-6-{(N-methyl), N-[(1-emthyl-1,2,4-triazol-3- yl)methyl]amino}-1,2,4-triazolo[3,4-a]phthalazine a) (N-Methyl), [N-(1-methyl-1,2,4-triazol-3-yl)methyl]amine 1-Methyl- 1,2, 4-triazole-3-methanol (500mg, 4.4mmol) was added to ice-cooled thionyl chloride (5ml, 69mmol) and the mixture warmed to room temperature before being heated at reflux for 0.75h. After cooling to room temperature, the mixture was evaporated in vacuo and the residue taken up in 40 w/w aqueous methylamine (5ml, 58mmol) and dioxan (5ml) and heated in a sealed tube at 80°C overnight. After cooling to room temperature, the mixture was evaporated in vacuo and azeotroped with

ethanol, and the residue purified by chromatography on silica gel, eluting with dichloromethane/methanol/ammonia (60:80:1 to 40:8:1, gradient elution), to gibve the title-amine (440mg, 80%), 1H NMR (250 MHz, d6-DMSO) # 2.28 (3H, s, Me), 3.62 (2H, s, CH2), 3.81 (3H, s, Me), 8.35 (1H, s, Ar-H). b) 3-(5-methylisoxazol-3-yl)-6-[(N-methyl),[N-(1-methyl-1,2,4-t riazol-3- yl)methyl]amino-1,2,4-triazolo[3,4-a]phthalazine Sodium hydride (57mg of a 60% dispersion in oil, 1.4mmol) was added to a stirred solution of the preceding amine (117mg, 0.927mmol) in DMF (8ml) at room temperature under nitrogen and the mixture stirred for 1h. After this time, Intermediate 1 (204mg, 0.714mmol) was added and the mixture heated at 600C for 22h. The mixture was cooled to room temperature, water was added and the solvent was evaporated in vacuo.

The residue was partitioned between dichloromethane and water, and the aqueous phase separated and re-extracted with dichloromethane (x1). The combined organic extracts were washed with brine (x1), dried (MgSO4) and evaporated in vacuo. Chromatography of the residue on silica gel, eluting with methanol/dichloromethane (1% to 10%, gradient elution), followed by recrystallisation (ethyl acetate) gave the title-product (20mg, 7.1) 'H NMR (360 MHz, CDCl3/d6-DMSO) 6 2.58 (3H, s, Me), 3.16 (3H, s, Me), 3.97 (3H, s, Me), 4.63 (2H, s, CH2), 6.92 (1H, s, Ar-H), 7.82 (1H, dd, J = 8.4 and 7.1 Hz, Ar-H), 7.91 (1H, dd, J = 8.2 and 7.0 Hz, Ar-H), 8.10 (1H, s, Ar-H), 8.60 (1H, d, J = 7.1 Hz, Ar-H), 8.74 (1H, d, J = 7.1 Hz, Ar-H); MS (ES+) m/e 376 [MH]+.

EXAMPLE 61 3-(5-Isoxazol-3-yl)-6-(1-methyl-1,2,4-triazol-3-yl)methyloxy -1,2,4- triazol[3,4-a]phthalazine Prepared from the product of Example 34 part c (150mg, 0.55mmol) and 3-hydroxymethyl-1-methyl-1, 1,2, 4-triazole using the method of Example 1 to yield a pale yellow solid (73mg, 38%), lH NMR (360 MHz, CD Cl3) 6

3.97 (3H, s), 5.73 (2H, s), 7.40 (1H, d, J = 2Hz), 7.82 (1H, t, J = 7 Hz), 7.96 (1H, t, J = 7 Hz), 8.08 (1H, s), 8.29 (1H, d, J = 7 Hz), 8.64 (1H, d, J = 2 Hz), 8.72 (1H, d, J = 7 Hz); MS (ES+) m/e 349 [MH]+.

INTERMEDIATE 4 3-(Carboxaldehydechloroxime)-6-(2,2,2-trifluoroethyloxy)-1,2 ,4-triazolo- [3,4-a]phthalazine a) 3-Allyloxyformyloxime-6-(2,2,2-trifluoroethyloxy)-1,2,4-tria zolo- [3,4-a]phthalazine The product of Example 70 part a (20g, 70mmol) was dissolved in dry DMF (350ml) and cooled to -200C. 2,2,2-Trifluoroethanol in dry DMF was cooled to 0°C and lithium bis(trimethylsilyl)amide was added dropwise. The anion thus produced was added to the preceding solution maintaining the internal temperature below -200C. The reaction was warmed to 0°C. After 0.5h, the reaction was poured into saturated ammonium chloride solution, filtered, washed with water and dried to yield a pale green solid (22g, 89%), lH NMR (250 MHz, CD Cl3) 6 4.82-4.86 (2H, m), 4.93 (2H, q, J = 8 Hz), 5.28-5.45 (2H, m), 6.03-6.19 (1H, m), 7.89 (1H, dt, J = 1 and 8 Hz), 8.22 (1H, dt, J = 1 and 8 Hz), 8.24 (1H, dd, J = 1 and 8 Hz), 8.58 (1H, s), 8.73 (1H, dd, J = 1 and 8 Hz); MS (ES+) m/e 352 [MH]+. b) 3-Carboxaldehvdeoxime-6-(2, 2 2-trifluoroethvloxv)-1. 1,2,4- [3,4-a]phthalazine The preceding allyl ether was suspended in a solution of triethylammonium formate in ethanol (1M), the suspension was purged with nitrogen, tetrakis (triphenylphosphine) palladium (0) (0.5g) was added and the reaction was heated to reflux for 16h. Most of the solvent was removed by evaporation and the residue was poured into water. The precipitate was filtered off, washed with water and then boiled in ethanol and allowed to cool and age 16h before filtering and drying to yield a brown solid (18g, 83%) lH NMR (250 MHz, d6-DMSO) # 5.30 (2H, q, J = 9

Hz), 7.95-8.20 (3H, m), 8.52-8.58 (2H, m), 12.25 (1H, s); MS (ES+) m/e 312 [MH]+. c) 3-Carboxaldehydechloroxime-6-(2,2,2-triflouroethyloxy)-1,2,4 - [3,4-a]phthalazine The preceding oxime (18g, 60mmol) was dissolved in DMF (500ml) and N-chlorosuccinimide (8.01g, 60mmol) was added. The reaction mixture was heated to 500C and wet hydrogen chloride was bubbled through the mixture. The reaction was allowed to cool and poured into cold, saturated brine. The product was filtered, washed with water and dried to yield a pale yellow solid (18g, 87%) lH NMR (250 MHz, CD Cl3) 6 5.20 (2H, q, J = 8 Hz), 8.01-8.21 (3H, m), 8.58-8.61 (1H, m), 13.27 (1H, s); MS (ES+) m/e 346 [MH]+.

INTERMEDIATE 5 3-(Isoxazol-3-yl)-6-(2,2,2-trifluoroethyloxy)-1,2,4-triazolo - [3,4-a]phthalazine Intermediate 4 (1.73g, 5.0lmmol) was suspended in a stirred solution of vinyl acetate (2.0ml) in dichloromethane (250ml). A solution of triethylamine was added dropwise to the reaction mixture over a period of 0.5h. The mixture was stirred for 1h then the solvent was removed by evaporation and replaced with xylene (200ml) and heated at its reflux for 16h. The solvent was removed and the residue was purified by column chromatographed on silica gel using ethyl acetate/dichloromethane (1:4) as eluent, to yield the title-product (1.01g, 60%); lH NMR (250 MHz, d6-DMSO) 6 5.31 (2H, q, J = 9 Hz), 7.53 (1H, d, J = 2Hz), 8.02-8.23 (3H, m), 8.62 (1H, m), 9.30 (1H, d, J = 2 Hz); MS (ES+) m/e 336 [MH]+.

EXAMPLE 62 3-93-Isoxazolyl)-6-(2-methyl-1,2,4-triazol-3-yl)methyloxy-1, 2,4- triazolo[3,4-a]phthalazine The title-compound was prepared from Intermediate 5 and 2- methyl-1,2,4-triazole-3-methanol (prepared using the conditions of Itoh and Okongi, EP-A-421210) following the procedure given in Example 1, 1H NMR (360 MHz, d6-DMSO) 6 4.01 (3H, s, Me), 5.83 (2H, s, CH2), 7.57 (1H, d, J = 1.7 Hz, Ar-H), 7.96 (1H, m, Ar-H), 8.00 (1H, s, Ar-H), 8.12 (1H, t, J = 7.3 Hz, Ar-H), 8.25 (1H, d, J = 8.2 Hz, Ar-H), 8.58 (1H, d, J = 7 Hz, Ar-H); MS (ES+) m/e 349 [MH]+.

EXAMPLE 63 3-(3-Isoxazolyl)-6-(1-methylimidazl-4-yl)methyloxy-1,2,4- triazolo [3,4-alnhthalazine The title-compound was prepared from Intermediate 5 (150mg, 0.45mmol) and 4-hydroxymethyl-1-methylimidazole (55mg, 5.0mmol) using the procedure described in Example 1 (18mg, 12%), mp 191-192°C; 'H NMR (360 MHz, CD Cl3) 6 3.68 (3H, s, CH3), 5.62 (2H, s, CH2), 7.32 (1H, d, J = 1.6 Hz, Ar-H), 7.43 (1H, s, Ar-H), 7.55 (1H, s, Ar-H), 7.78 (1H, t, J = 8.2 Hz, Ar-H), 7.93 (1H, t, J = 8.2 Hz, Ar-H), 8.27 (1H, d, J = 7.9 Hz, Ar-H), 8.64 (1H, d, J = 1.6 Hz, Ar-H), 8.68 (1H, d, J = 7.9 Hz, Ar-H); MS (ES+) m/e 348 [MH]+.

EXAMPLE 64 3-(5-Hydroxymethylisoxazol-3-yl)-6-(2-pyridyl)mthyloxy-1,2,4 -triazolo- [3,4-a]phthalazine a) 5-Hydroxymethylisoxazole-3-carboxylic acid ethyl ester A solution of triethylamine (7.36ml, 53mmol) in diethyl ether (40ml) was added dropwise over 4h (syringe pump; 10ml/hr) to a vigorously stirred solution of carbethoxychloraldoxime (8g, 53mmol) (prepared as described in J. Org. Chem., 1983, 48, 366) and propargyl alcohol (3.69ml,

63mmol) in diethyl ether (120ml) at room temperature under nitrogen.

The mixture was stirred for 48jh then diluted with diethyl ether (100ml) and poured into water (100ml). the organics were separated, washed with water (x1) then dried (MgSO4) and the solvent evaporated in vacuo. Flash chromatography of the residue on silica gel, eluting with 1:1 ethyl acetate/hexane, gave the title-compound (6.9g, 74%), lH NMR (250 MHz, <BR> <BR> <BR> <BR> CDCl3) # 1.42 (3H, t, J = 7.1 Hz, CH3), 6 2.34 (1H, br s, OH) # 4.45 (2H, q,<BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> J = 7.1 Hz, CH2) # 4.84 (2H, s, CH2) # # 6.69 (1H, s, Ar-H); MS (ES+) m/e 172 [MH]+. b) 5-(TetrahYdrosvran-2-sloxvmethYl)-isoxazol-3-carboxylic acid ethvl ester 2,4-dihydro-2H-pyran (2.07ml, 23mmol) and p-toluene sulfonic acid monohydrate (333mg, 1.7mmol) were added to a solution of the preceding ester (3g, 17mmol) in dichloromethane (60ml), and the mixture stirred at room temperature under nitrogen for 18h. The mixture was diluted with dichloromethane (50ml), then washed with aqueous sodium carbonate solution (x1) and with water (x1). The organic phase was dried (MgSO4) and the solvent evaporated in vacuo. Flash chromatography of the residue on silica gel, eluting with 25% ethyl acetate/hexane, gave the title-compound (3.24g, 72%), 1H NMR (250 MHz, CD Cl3) 6 1.42 (3H, t, J = 7.1 Hz, CH3), 1.60-1.70 (6H, m, 3 of CH2), 3.58 (1H, m, CH of CH2), 3.84 (1H, m, CH of CH2), 4.45 (2H, q, J = 7.1 Hz, CH2), 4.69 (1H, d, J = 13.9 Hz, CH2), 4.75 (1H, t, J = 3.3 Hz, CH), 4.84 (1H, d, J = 14.0 Hz, CH2), 6.69 (1H, s, Ar-H); MS (ES+) m/e 256 [MH]+. c) 5-(Tetrahydropyran-2-yloxymethyl)-isoxazol-3-carboxylic acid Sodium hydroxide (2.01g, 50mmol) in water (20ml) was added to a solution of the preceding ester (3.24g, 13mmol) in methanol (12ml). The mixture was stirred at room temperature for 0.67h then the methanol evaporated in vacuo and the aqueous residue cooled using an ice/water bath. 2M Hydrochloric acid (19ml, 38mmol) was added slowly, keeping the temperature below 5°C. Ethanol (20ml) was added and the mixture

evaporated in vacuo. The solid formed was dissolved in water and acetic acid added (lml). The mixture was extracted into ethyl acetate (6x) and the combined extracts were dried (MgSO4) and evaporated to give the title-compound (1.93g, 67%); 1H NMR (360 MHz, d6-DMSO) # 1.40-1.60 (6H, m, 3 of CH2), 3.49 (1H, m, CH of CH2), 3.75 (1H, m, CH of CH2), 4.68 (1H, d, J = 13.7 Hz, CH2), 4.73 (1H, m, CH), 4.78 (1H, d, J = 13.8 Hz, CH2), 6.82 (1H, s, Ar-H). d) 6-chloro-3-{[5-(6etrahydropyran-2-yloxy)methyl]-isoxazol-3-y l}-1,2,4- triazolo[3,4-a]phthalazine The title-compound was prepared from the preceding acid using the procedure described in Example 1 part c; 1H NMR (250 MHz, CDCl3) 6 1.60-1.80 (6H, m, 3 of CH2), 3.61 (1H, m, CH of CH2), 3.92 (1H, m, CH of CH2), 4.75 (2H, m, CH and CH of CH2), 4.95 (1H, d, J = 13.9 Hz, CH2), 7.18 (1H, s, Ar-H), 7.99 (1H, m, Ar-H), 8.05 (1H, m, Ar-H), 8.33 (1H, m, Ar-H), 8.82 (1H, m, Ar-H); MS (ES+) m/e 386 [MH]+. e) 3-{[5-(Tetrahydropyran-2-yloxy)methyl]-isoxazol-3-yl}-6-(2- pyridylmethyloxy-1,2,4-triazolo[3,4-a]phthalazine The title-compound was prepared from 6-hydroxy-3-{[5-(tetrahydro- pyran-2-yloxy)methyl]isoxazol-3-yl}-1,2,4-triazolo[3,4-a]pht halazine and picolyl chloride following the procedure given for Example 15, lH NMR (250 MHz, CDCl3) 6 1.60-1.80 (6H, m, 3 of CH2), 3.60 (1H, m, CH of CH2), 3.91 (1H, m, CH of CH2), 4.80 (1H, d, J = 13.8 Hz, CH of CH2), 4.84 (1H, m, CH), 4.95 (1H, d, J = 13. 7 Hz, CH of CH2), 5.77 (2H, s, CH2), 7.13 (1H, s, Ar-H), 7.29 (1H, m, Ar-H), 7.83 (2H, m, 2 of Ar-H), 7.86 (1H, m, Ar-H), 7.98 (1H, m, Ar-H), 8.33 (1H, m, Ar-H), 8.70 (2H, m, 2 of Ar-H); MS (ES+) m/e 459 [MH]+. f) 3-(5-Hydroxymethylisoxazol-3-yl)-6-(2-pyridyl)methyloxy-1,2, 4- triazolo[3,4-a]phthalazine Pyridinium-p-toluenesulfonate (16mg, 0.6mmol) was added to the preceding phthalazine (295mg, 6mmol) in ethanol (10ml) and the mixture heated at 55°C under nitrogen for 24h. A further portion of pyridinium-

p-toluenesulfonate (16mg, 0.6mmol) was added during this time. The Inixture was evaporated in vacuo and water added. The solid formed was filtered off and washed successively with water and hexane. Flash chromatography of the residue on silica gel, eluting with 5% methanol/dichloromethane, followed by recrystallisation from ethyl acetate/dichloromethane gave the title-compound as a cream solid (89mg, 30%), mp 129-131°C; 1H NMR (360 MHz, d6-DMSO) # 4.74 (2H, d, J = 5.9 Hz, CH2), 5.92 (2H, s, CH2), 5.84 (1H, t, J = 6.0 Hz, OH), 7.14 (1H, s, Ar-H), 7.41 (1H, t, J = 5.0 Hz, Ar-H), 7.76 (1H, d, J = 7.8 Hz, Ar-H), 7.89 (1H, m, Ar-H), 7.99 (1H, t, J = 7.7 Hz, Ar-H), 8.12 (1H, t, J = 7.7 Hz, Ar-H), 8.34 (1H, d, J = 8.1 Hz, Ar-H), 8.58 (1H, d, Ar-H), 8.62 (1H, d, Ar-H); MS (ES+) m/e 375 [MH]+; Anal. Found. C, 59.87; H, 3.72; N, 21.92.

C19H14N5O3#0.1 CH2Cl2 requires C, 59.92; H, 3.74; N, 21.95%.

EXAMPLE 65 3-(5-Hydroxymethylisoxazol-3-yl)-6-(1-methyl-1,2,4-triazol-3 -yl)methyloxy- 1,2,4-triazolo[3,4-a]phthalazine a) 6-(1-Methyl-1,2,4-triazol-3-yl)methyloxy-3-{5-[(6etrahydroxp yran-2- yloxy)methyl]isoxazol-3-yl}-1,2,4-triazolo[3,4-a]phthalazine The title-compound was prepared using 6-chloro-3-[(5- tetrahydroxpyran-2-yloxymethyl-isoxazol-3-yl]-1,2,4-triazolo [3,4- a]phthalazine (290mg, 0.7mmol) (prepared as described in Example 64 part d) and 1-methyl-1,2,4-triazoloe-3-methanol (94mg, 0.8mmol) (prepared using the conditions of Itoh and Okongi, EP-A-421210) using the procedure given for Example 1, lH NMR (360MHz, CD Cl3) 6 1.60-1.80 (6H, m, 3 of CH2), 3.59 (1H, m, CH of CH2), 3.92 (1H, m, CH of CH2), 3.97 (3H, s, CH3), 4.81 (1H, d, J = 13.9 Hz, CH2), 4.84 (1H, m, CH), 4.94 (1H, d, J = 13.8 Hz, CH2), 5.72 (2H, s, CH2), 7.28 (1H, s, Ar-H), 7.79 (1H, m, Ar-H), 7.95 (1H, m, Ar-H), 8.09 (1H, s, Ar-H), 8.27 (1H, d, J = 8.0 Hz, Ar-H), 8.70 (1H, d, Ar-H); MS (ES+) m/e 463 [MH]+.

b) 3-(5-Hydroxymethylisoxazol-3-yl)-6-(1-methyl-1,2,4-triazol-3 - yl)methyloxy-1,2,4-triazolo[3,4-a]phthalazine The title-compound was prepared from the preceding phthalazine using the procedure given in Example 64 part f, mp 275-276°C; 1H NMR (360 MHz, d6-DMSO) 5 3.91 (3H, s, CH3), 4.74 (2H, d, J = 6.0 Hz, CH2), 5.62 (2H, s, CH2), 5.82 (1H, t, J = 6.0 Hz, OH), 7.39 (1H, s, Ar-H), 7.95 (1H, t, J = 8.1 Hz, Ar-H), 8.11 (1H, t, J = 7.6 Hz, Ar-H), 8.17 (1H, d, J = 8.0 Hz, Ar-H), 8.56 (1H, s, Ar-H), 8.60 (1H, d, Ar-H); MS (ES+) m/e 379 [MH]+.

Anal. Found. C, 53.72; H, 3.74; N, 28.57. C17H14N8O3#0.3CH3OH requires C, 53.56; H, 3.95; N, 28.88%.

EXAMPLE 66 3-(5-Fluoromethylisoxazol-3-yl)-6-(2-pyridyl)methyloxy-1,2,4 - triazolo[3,4-a]phthalazine a) Ethyl 5-fluoromethylisoxazole-3-carboxylate A solution of DAST (2.260g, 14.02mmol) in dichloromethane (15ml) was added dropwise to a stirred solution of ethyl 5-hydroxymethylisoxazole- 3-carboxylate (2.000g, 11.69mmol) in dichloromethane (20ml) at-78°C under nitrogen. The mixture was stirred at-78°C for 0.83h and then at room temperature for 2.5h. Water (6ml) and 2.5% aqueous sodium bicarbonate solution (25ml) were added succesively and the organic layer separated, dried (MgSO4) and evaporated in vacuo. Chromatography of the residue on silica gel, eluting with 9:1 dichloromethane/hexane, gave the title-ester (1.397g, 69%), lH NMR (250MHz, CDCl3) 6 1.43 (3H, t, J = 7.2 Hz, Me), 4.47 (2H, q, J = 7.1 Hz, CH2), 5.48 (2H, d, J = 47 Hz, CH2F), 6.83 (1H, d, J = 2.7 Hz, Ar-H). b) 5-Fluoromethvlisoxazole-3-carboxylic acid 10% Aqueous sodium hydroxide solution (5ml) was added to a stirred solution of the preceding ester (1.884g, 10.88mmol) in ethanol (5ml) at room temperature. After stirring overnight, the solvents were evaporated in uacuo and the residue dissolved in water and acidified to pH 1 with 35%

hydrochloric acid. Ethanol was added, the solvents evaporated in vacuo and the residue azeotroped with ethanol. Ethanol was added and the mixture filtered to remove inorganic solids, Evaporation in vacuo of the filtrate gave the title-acid (0.921g, 58%), 1H NMR (250 MHz, d6-DMSO), 5.55 (2H, d, J = 47 Hz, CH2F), 6.77 (1H, br s, Ar-H). c) 6-Chloro-3-(5-fluoromethylisoxazol-3-yl)-1,2,4- triazolo[3,4-a]phthalazine The title-compound was prepared from the preceding acid using the procedure given for Intermediate 1 part c, 1H NMR (360 MHz, CDCl3/d6-DMSO) # 5.60 (2H, d, J = 47 Hz, CH2F), 7.34 (1H, d, J = 2.8 Hz, Ar-H), 7.98 (1H, m, Ar-H), 8.11 (1H, m, Ar-H), 8.36 (1H, d, J = 8.0 Hz, Ar-H), 8.82 (1H, d, J = 8.0 Hz, Ar-H); MS (ES+) m/e 304 [MH]+. d) 3-(5-Fluoromethylisoxazol-3-yl)-6-(2-pyridyl)methyloxy-1,2,4 - triazolo[3,4-a]phthalazine The title-compound was prepared from the preceding product and 2-pyridylcarbinol using the precedure given for Example 1, 'H NMR (360 MHz, CDCl3 # 5.59 (2H, d, J = 47 Hz, CH2F), 5.78 (2H, s, CH2O), 7.25-7.32 (2H, m, 2 of Ar-H), 7.74-7.87 (3H, m, 3 of Ar-H), 7.98 (1H, m, Ar-H), 8.34 (1H, d, J = 7.8 Hz, Ar-H), 8.66-8.72 (2H, m, 2 of Ar-H); MS (ES+) m/e 377 [MH]+.

EXAMPLE 67 3-(5-Fluoromethylisoxazol-3-yl)-6-(1-methyl-1,2,4-triazol-3- yl)methyloxy- 1,2,4-triazolo[3,4-a]phthalazine Prepared from the product of Example 66 part c (85mg, 0.28mmol) and 3 -hydroxymethyl- 1-methyl- 1,2, 4-triazole using the method of Example 1 to yield a pale yellow solid (56mg, 52%), lH NMR (360 MHz, CD Cl3) 6 3.96 (3H, s), 5.58 (2H, d, J = 44 Hz), 5.73 (2H, s), 7.51 (1H, s), 7.81 (1H, t, J = 7 Hz), 7.96 (1H, t, J = 7 Hz), 8.08 (1H, s), 8.30 (1H, d, J = 7 Hz), 8.72 (1H, d, J = 7 Hz); MS (ES+) m/e 381 [MH]+.

EXAMPLE 68 3-(5-fluoromethylisoxazol-3-yl)-6-(1-methyl-1,2,4-triazol-5- yl)methyloxy- 1,2,4-triazolo[3,4-a]phthalazine The title-compound was prepared from the product of Example 66 part c (150mg, 0. 5mmol) and 2-methyl- 1,2,4-triazole-3-methanol (61mg, 0.53mmol) (prepared using the conditions of Itoh and Okongi, EP-A-421210) using the procedure given in Example 1 using lithium bis (trimethylsilyl) amide (0.59ml, 1. 0M in tetrahydrofuran) as the base (80mg, 43%), mp 250-252°C; 1H NMR (360 MHz, d6-DMSO) # 4.01 (3H, s, CH3), 5.76 (2H, d, J = 47 Hz, CH2), 5.83 (2H, s, CH2), 7.70 (1H, d, J = 3.5 Hz, Ar-H), 7.96 (1H, m, Ar-H), 8.02 (1H, s, Ar-H), 8.13 (1H, m, Ar-H), 8.25 (1H, d, J = 7.8 Hz, Ar-H), 8.59 (1H, d, J = 7.9 Hz, Ar-H); MS (ES+) m/e 381 [MH]+; Anal. Found. C, 52.31; H, 3.36; N, 28.64. C17H13N8O2F#0.15CH2Cl2 requires C, 52.40; H, 3.41; N, 28.51%.

EXAMPLE 69 3-(5-Fluoromethylisoxazol-3-yl)-6-(1,2,4-triazol-3-yl)methyl oxy-1,2,4- triazolo[3,4-a]phthalazine a) 3-(5-Fluoromethylisoxazol-3-yl)-6-[2-{[2- (trimethylsilyl)ethoxy]methyl}-1,2,4-triazol-3-yl)methyloxy- 1,2,4- triazolo[3,4-a]phthalazine The title-compound was prepared from 6-chloro-3-(5- fluoromethylisoxazol-3-yl)-1,2,4-triazolophthalazine (160mg, 0.53mmol) and 3-hydroxymethyl-2-{[(2-trimethylsilyl)ethoxy]methyl}-1,2,4- triazole (133mg, 5.8mmol) using the procedure given for Example 10, using lithium bis(trimethylsilyl)amide (0.63ml, 1. 0M in tetrahydrofuran) as base, (101mg, 41%), lH NMR (250 MHz, CDCl3) # 0.00 (9H, s, SiMe3); 0.89 (2H, m, CH2), 3.67 (2H, m, CH2), 5.62 (2H, d, J = 47 Hz, CH2), 5.84 (2H, s, CH2), 5.92 (2H, s, CH2), 7.36 (1H, d, J = 2.8 Hz, Ar-H), 7.88 (1H, m, Ar-H), 7.97 (1H, s, Ar-H), 8.04 (1H, m, Ar-H), 8.34 (1H, d, J = 7.7 Hz, Ar-H), 8.74 (1H, d, Ar-H); MS (ES+) m/e 497 [MH]+.

b) 3-(5-Flouoromethylisoxazol-3-yl)-6-(1,2,4-triazol-3-yl)methy loxy- 1,2,4-triazolo[3,4-a]phthalazine The title-compound was prepared from the preceding phtahalazine (101mg, 0.2mmol) using the procedure given in Example 58 part c (60mg, 80%), mp 266-268°C; lH NMR (360 MHz, d6-DMSO) 5 5.70 (2H, s, CH2), 5.76 (2H, d, J = 47 Hz, Ar-H), 7.72 (1H, d, J = 3.5 Hz, Ar-H), 7.97 (1H, m, Ar-H), 8.12 (1H, m, Ar-H), 8.23 (1H, d, J = 7.8 Hz, Ar-H), 8.44 (1H, br s, Ar-H), 8.60 (1H, d, J = 7.2 Hz, Ar-H); MS (ES+) m/e 367 [MH]+; Anal.

Found. C, 51.90; H, 3.06; N, 30.09. C16H11N8O2F#0.1H2O requires C, 52.21; H, 3.07; N, 30.44.

EXAMPLE 70 3-(5-Ethoxyisoxazol-3-yl)-6-(2-pyridyl)methyloxy-1,2,4- triazolo [3, 4-alphthalazine a) 3-(O-allyloxyformayloxime)-6-chloro-1,2,4-triazolo[3,4-a]pht halazine 1- Chloro-4-hydrazinophthalazine (5. Og, 25. 7mmol) and 0 - alkylglyoxal oxime (JP-A-6312673) (3.87g, 30mmol) in dichloromethane (200ml) with triethylamine (7.7g, 60mmol) was cooled to 0°C and bis(2-oxo- 3-oxazolidinyl)-phosphinic chloride (7.6g, 60mmol) was added. The reaction mixture was allowed to warm to room temperature and was stirred for 16h.

The solvent was removed by evaporation and the residue was triturated with water, xylene (200ml) and triethylamine hydrochloride (0.5g) were added and the reaction was heated to 150°C for 2h. The xylene solution was washed with water and evaporated to give a yellow solid which was purified by column chromatography on silica gel, eluting with ethyl acetate/hexane (1:4) followed by recrystallisation from dichloromethane/hexane to yield a pale yellow solid (2.3g, 31%), lH NMR (250 MHz, CDCl3) # 4.87-4.90 (2H, m), 5.30-5.47 (2H, m), 6.03-6.18 (1H, m), 7.90-7.96 (1H, m), 8.03-8.06 (1H, m), 8.29-8.32 (1H, m), 8.64 (1H, s), 8.76- 8.85 (1H, m); MS (ES+) m/e 288 [MH]+.

b) 3-(O-Allyloxyformyloxime)-6-(2-pyridyl)methyloxy-1,2,4- triazolo[3,4-a]phthalazine 2-Pyridine methanol (0.824g, 7.56mmol) and the preceding phthalazine (2.17g, 7.56mmol) were dissolved in dry DMF (25ml) and cooled to -200C before adding lithium bis(trimethylsilyl)amide (1M in THF, 7.6ml) dropwise, maintaining the temperature of the reaction below -100C.

After 0.5h, the reaction mixture was poured into water and extracted with dichloromethane. The organic layer was dried (MgSO4), filtered and evaporated to yield an oil, which was purified by chromatography on silica gel, eluting with methanol/dichloromethane (1:99), to give a white solid (1.3g, 48%), lH NMR (250 MHz, CD Cl3) 5 4.84-4.86 (2H, m), 5.28-5.45 (2H, m), 5.71 (1H, s), 6.11 (1H, m), 7.30 (1H, m), 7.62 (1H, m); 7.48-7.81 (2H, m); 7.91 (1H, m), 8.29 (1H, m), 8.57 (1H, s), 8.66 (1H, m); MS (ES+) m/e 361 [MH]+. c) 3-(Carboxaldehvdeoxime)-6-(2-pvridyl)met 1,2,4- triazolo[3,4-a]phthalazine The preceding allyl ether (1.1g, 3.06mmol) was suspended in a 1M solution of triethylammonium formate in ethanol. 2ml of water were added and then the suspension was purged with nitrogen. Tetrakis (triphenylphosphine) palladium (0) (30mg) was added and the reaction was heated to reflux for four hours. The reaction was cooled to 4°C and aged for 16h. The product was filtered off and dried to yield 0.86g of the product as a white solid (88%), lH NMR (250 MHz, d6-DMSO) 5 5.73 (2H, s), 7.45 (1H, m), 7.81 (1H, m), 7.92-8.03 (2H, m), 8.14 (1H, m), 8.36 (1H, m), 8.51 (1H, s), 8.58 (1H, m), 8.68 (1H, m), 12.29 (1H, s); MS (ES+) m/e 321 [MH]+. d) 3-(Carboxaldehydechloroxime)-6-(2-pyridyl)methyloxyl-1,2,4- triazolo[3,4-a]phthalazine The preceding oxime (2.53g, 7.9mmol) and N-chlorosuccinimide (1.12g, 7.9mmol) were suspended in dry DMF and heated until the reactants had dissolved. The reaction was stirred for 16h, filtered and the white product obtained was washed with water, methanol and ether and

dried to yield 5.8g (74%) of a white solid, lH NMR (250 MHz, d6-DMSO) 5 5.69 (1H, s), 7.47 (1H, m), 7.82 (1H, m), 7.94-8.05 (2H, m), 8.16-8.22 (1H, m), 8.63 (1H, m), 13.38 (1H, s); MS (ES+) m/e 355 [MH]+. e) 3-(5-Ethoxyisoxazol-3-yl)-6-(2-pyridyl)methyloxy-1,2,4- triazolo[3,4-a]phthalazine The preceding chloroxime (50mg) was suspended in a solution of ethoxyacetylene in dichloromethane (20%, 20ml) and triethylamine (43mg) was added. The reaction was stirred for 16h and then washed with dilute ammonium hydroxide, dried (MgSO4), filtered and evaporated. The residue was purified by silica chromatography to yield a pale yellow powder (40.5mg, 74%), lH NMR (250 MHz, CDCl3) # 1.85 (3H, t, J = 7 Hz), 4.70 (2H, q, J = 7 Hz), 6.07 (2H, s), 6.39 (1H, s), 7.59 (1H, m), 8.06-8.27 (4H, m), 8.66 (1H, m), 8.93-9.02 (2H, m); MS (ES+) m/e 389 [MH]+.

INTERMEDIATE 6 3-(5-Ethoxyisoxazol-3-yl)-6-(2,2,2-trifluoroethyloxy)-1,2,4- triazolo[3,4-a]phthalazine Intermediate 4 (1.5g, 4.34mmol) and ethoxyacetylene (5ml of a 40% w/w solution in hexane) were suspended in dichloromethane and triethylamine (1.5g, 14.8mmol) in 100ml dichloromethane was added dropwise to the mixture over 1h. The reaction was washed with water and the organic layer was dried (MgSO4), filtered and evaporated. The residue was purified by column chromatography on silica, eluting with ethyl acetate/dichloromethane (1:4), to yield a white solid (0.85g, 51%), lH NMR (250 MHz, CDCl3) # 1.50 (3H, t, J = 7 Hz), 4.40 (2H, d, J = 7 Hz), 5.00 (2H, d, J = 9 Hz), 6.06 (1H, s), 7.88 (1H, dt, J = 1 and 7 Hz), 8.03 (1H, dt, J = 1 and 7 Hz), 8.28 (1H, dd, J = 1 and 7 Hz), 8.73 (1H, dd, J = 1 and 7 Hz); MS (ES+) m/e 380 [MH]+.

EXAMPLE 71 3-(5-Ethoxyisoxazol-3-yl)-6-(1-methyl-1,2,4-triazol-3-yl)met hyloxy-1,2,4- triazolo[3,4-a]phthalazine Lithium hexamethyldisilazide (1.0M solution in hexane) (0.22ml, 1.10mmol) was added to stirred solution of 3-hydroxymethyl-1-methyl- 1,2,4-triazole (90mg, 0.79mmol) (prepared using the conditions of Itoh and Okongi, EP-A-421210) in N,N-dimethylformamide (10ml) at -100C under nitrogen, and the mixture stirred for 0.25h. After this time, Intermediate 6 (100mg, 0.53mmol) was added and the mixture stirred at -100C for 0.5h and then room temperature overnight. Water was added to the reaction mixture and the resulting precipitate filtered off and recrystallised from dichloromethane/ethyl acetate to give the title-phthalazine (55mg, 27%), mp 221-223°C; lH NMR (360 MHz, CDCl3) 6 1.54 (3H, t, J = 10.2 Hz, CH3), 3.96 (3H, s, CH3), 4.47 (2H, q, J = 10.2 Hz, CH2), 5.71 (2H, s, CH2), 6.26 (1H, s, Ar-H), 7.79 (1H, m, Ar-H), 7.94 (1H, m, Ar-H), 8.08 (1H, s, Ar-H), 8.25 (1H, d, J = 11.0 Hz, Ar-H), 8.70 (1H, d, J = 8.1 Hz, Ar-H); MS (ES+) m/e 393 [MH]+; Anal. Found. C, 54.87; H, 3.91; N, 28.27; C18H16N8O3 requires C, 55.09; H, 4.11; N, 28.55%.

EXAMPLE 72 3-(5-Ethoxyisoxazol-3-yl)-6-(2-methyl-1,2,4-triazol-3-yl)met hyloxy-1,2,4- triazolo[3,4-a]phthalazine The title compound was prepared from Intermediate 6 and 2-methyl 1,2,4-triazole-3-methanol (prepared using the conditions of Itoh and Okongi, EP-A-421210) following the procedure given in Example 71, mp 223-225°C; lH NMR (360MHz, CDCl3) # 1.54 (3H, t, J = 7.1Hz, CH3), 4.11 (3H, s, CH3), 4.39 (2H,q, J = 7.1Hz, CH2), 5.83 (2H,s, CH2), 6.12 (1H, s, Ar-H), 7.80 (1H, m, Ar-H), 7.91 (1H, s, Ar-H), 7.95 (1H, m, Ar-H), 8.24 (1H, d, J=8.0Hz, Ar-H), 8.70 (1H, d, J = 7.9Hz, Ar-H); MS (ES+) m/e 393 [MH]-: Anal. Found. C, 54.30; H, 3.67; N, 27.80; C18H,6N8O3 requires C, 54.22; H.

4.07; N, 27.95%.

EXAMPLE 73 3-(5-Ethoxyisoxazol-3-yl)-6-(1,2,4-triazol-3-yl)methyloxy-1, 2,4- triazolo[3,4-a]phthalazine a) 3-(5-Ethoxyisoxazol-3-yl)-6-{[1-(trimethylsilyl)ethoxy]methy l-1,2,4- triazol-5-yl}methyloxy-1,2,4-triazolo[3,4-a]phthalazine The title compound was prepared from Intermediate 6 (300mg, 0. 8mmol) and 3-hydroxymethyl-2-([2-(trimethylsilyl)et 1,2,4- triazole (199mg, 0.9mmol) following the procedure given in Example 71 (250mg, 62%), lH NMR (250MHz, CDCl3) 6 0.12 (9H, s, 3 of CH3), 0.85-0.91 (2H, m, CH2), 1.58 (3H, t, J = 7.0Hz, CH3), 3.63-3.69 (2H, m, CH2), 4.44 (2H, q, J = 7.1Hz, CH2), 5.85 (2H, s, CH2), 5.91 (2H, s, CH2), 6.16 (1H, s, Ar- H), 7.87 (1H, m, Ar-H), 7.95 (1H, s, Ar-H), 8.02 (1H, m, Ar-H), 8.33 (1H, d, Ar-H), 8.72 (1H, d, Ar-H); MS (ES+) m/e 509 [MH]+. b) 3-(5-Ethoxyisoxazol-3-yl)-6-(1,2,4-triazol-3-yl)methyloxy-1, 2,4- triazolo[3,4-a]phthalazine The title compound was prepared from the preceding phthalazine (250mg, 0.5mmol) using the procedure described in Example 58 part c, (66mg, 35%), mp 240-243°C; 1H NMR (360MHz, d6-DMSO) # 1.46 (3H, t, J = 7.0Hz, CH3), 4.51 (2H, q, J = 7.0Hz, CH2), 5.72 (2H, s, CH2), 6.61 (1H, s, Ar-H), 7.96 (1H, m, Ar-H), 8.11 (1H, m, Ar-H), 8.24 (1H, d, J = 8.1Hz, Ar-H), 8.51 (1H, br s, Ar-H), 8.56 (1H, d, Ar-H); MS (ES+) m/e 379 [MH]+; Anal. Found. C, 53.67; H, 3.33; N, 29.52; C17H14N8O3 requires C, 53.97; H, 3.73; N, 29.62%.

EXAMPLE 74 3-(5-Ethoxyisoxazol-3-yl)-6-(1-methylimidazol-4-7l)methyloxy -1,2,4- triazolor3,4-alphthalazine The title compound was prepared from Intermediate 6 (150mg, 0. 4mmol) and 4-hydroxymethyl-1-methylimidazole (49mg, 0. 4mmol) following the procedure given in Example 71 (45mg, 18%), mp 189-190°C

1H NMR (360MHz, CDCl3) # 1.55 (3H, t, J = 7.1Hz, CH3), 3.68 (3H, s, CH3), 4.40 (2H, q, J = 7.0Hz, CH2), 5.60 92H, s, CH2), 6.15 (1H, s, Ar-H), 7.41 (1H, s, Ar-H), 7.61 (1H, s, Ar-H), 7.77 (1H, m, Ar-H), 7.91 (1H, m, Ar-H), 8.26 (1H, d, J = 7.8Hz, Ar-H), 8.64 (1H, d, Ar-H); MS (ES+) m/e 392 [MH]+; Anal.

Found. C, 57.85; H, 4.07; N, 24.48; C19H17N7O3 0.15H2O requires C, 57.91; H, 4.42; N, 24.88%.

EXAMPLE 75 3-(5-Chloroisoxazol-3-yl)-6-(2-pyridyl)methyloxy-1,2,4- triazolo[3,4-a]phthalazine The product from Example 70, part d) (50mg, 0.14mmol) was suspended in vinylidine chloride (5ml) with triethylamine (43mg, 0.42mmol). The reaction was stirred for 16 hours, diluted with dichloromethane and washed with 5% ammonia solution and then dried (MgSO4), filtered and evaporated to yield a solid which was purified by preparative thin layer chromatography using methanol/dichloromethane (3:97) as elutant to yield 12.5mg of pure product, lH NMR (360MHz, CD Cl3) 8.66-8.72 (2H, m), 8.35 (1H, d, J = 7Hz), 7.98 (1H, t, J = 7Hz), 7.85 (1H, t, J = 7Hz), 7.80-7.70 (2H, m), 7.28 (1H, m), 7.03 (1H, s), 5.76 (2H, s); MS (ES+) 379 [MH]+.

INTERMEDIATE 7 3-(5-Chloroisoxazol-3-vl)-6-(2. 2. 2-trifluoroethvloxY)-1 2, 4-triazolo [3,4- al phthalazine.

Intermediate 4 (3.5g, 10mmol) was dissolved in THF (350ml) and added dropwise to a stirred solution of triethylamine (2.02g, 20mmol) in vinylidine chloride (200 ml) over a period of two hours. The solvent was removed and the residue was purified by column chromatography on silica gel, eluting with ethyl acetate/dichloromethane (1:10), to yield the product as a white solid (1.9g, 50%), 1H NMR (250MHz, d6-DMSO) 6 5.33 (2H, q, J = 9Hz), 7.66 (1H, s), 8.02-8.20 (3H, m), 8.59 (1H, m); MS (ES+) 379 [MH]+.

EXAMPLE 76 3-(5-Chloroisoxazol-3-yl)-6-(1-methyl-1,2,4-triazol-3-yl)met hyloxy-1,2,4- triazol[4,3-a]phthalazine Prepared in a similar manner to Example 71 using intermediate 7 (200mg, 0.54 mmol) and 3-hydroxymethyl-1-methyl-1,2,4-triazole (73mg) to yield a white solid (110mg, 53%). lH NMR (250MHz, CDCl3) 6 3.98 (3H, s), 5.72 (2H, s), 7.33 (1H, s), 7.82 (1H, t, J = 7Hz), 7.98 (1H, t, J = 7Hz), 8.10 (1H, s), 8.30 (1H, d, J = 7Hz), 8.62 (1H, d, J = 7Hz); MS (ES+) 383 [MH]+.

EXAMPLE 77 3-(5-Chloroisoxazol-3-yl)-6-(2-methyl-1,2,4-triazol-3-yl)met hyloxy-1,2,4- triazolo r4,3-alphthalazine Prepared in a similar manner to Example 71 using intermediate 7 (200mg, 0.54 mmol) and 3-hydroxymethyl-2-methyl-1,2,4-triazole (73mg) to yield a white solid (125mg, 61%), lH NMR (360MHz, CDCl3) 6 4.11 (3H, s), 5.83 (2H, s), 7.11 (1H, s), 7.86 (1H, t, J = 7Hz), 7.93 (1H, s), 8.00 (1H, t, J = 7Hz), 8.25 (1H, d, J = 7Hz), 8.73 (1H, d, J = 7Hz); MS (ES+) 383 [MH]+.

EXAMPLE 78 3-(5-Chloroisoxazol-3-yl)-6-(1-methylimidazol-4-yl)methyloxy -1,2,4- triazol[4,3-a]phthalazine The title compound was prepared from Intermediate 7 and 1-methyl- 4-hydroxymethylimidazole (J. Org. Chem. 1968, 33, 3758) using the procedure given for Example 71, lH NMR (360MHz, CDCl3) 6 3.69 (3H, s, Me), 5.61 (2H, s, CH2), 7.13 (1H, s, Ar-H), 7.43 (1H, s, Ar-H), 7.50 (1H, s, Ar-H), 7.79 (1H, m, Ar-H), 7.93 (1H, m, Ar-H), 8.28 (1H, d, J = 8.0Hz, Ar- H), 8.66 (1H, d, J = 8.0Hz, Ar-H); MS (ES+) m/e 382 [MH]+.

EXAMPLE 79 3-(5-Chloroisoxazol-3-yl)-6-(1,2,4-triazol-3-yl)methyloxy-1, 2,4-triazolo[3,4- a]phthalazine a) 3-(5-Chloroisoxazol-3-yl)-6-[2-{[2-(trimethylsilyl)ethoxy]me thyl}-1,2,4- triazol-3-yl)methyloxy-1,2,4-triazolo[4,3-a]phthalazine The title compound was prepared from Intermediate 7 (200mg, 0.5mmol) and 3-(hydroxymethyl)-2-{[2-(trimethylsilyl)ethoxy]methyl}-1,2,4 - triazole (136mg, 0.6mmol) following the procedure given in Example 71 (105mg, 39%), 1H NMR (250MHz, CDCl3) 6 0.13 (9H, s, 3 of CH3), 0.89 (2H, m, CH2), 3.67 (2H, m, CH2), 5.83 (2H, s, CH2), 5.90 (2H, s, CH2), 7.14 (1H, s, Ar-H), 7.88 (1H, m, Ar-H), 7.92 (1H, s, Ar-H), 8.01 (1H, m, Ar-H), 8.36 (1H, d, Ar-H), 8.72 (1H, d, Ar-H); MS (ES+) m/e 499 [MH]+. b) 3-(5-Chloroisoxazol-3-yl)-6-(1,2,4-triazol-3-yl)methyloxy-1, 2,4- triazolo [4, 3-alphthalazine The title compound was prepared from the preceding phthalazine (105mg, 0.2mmol) using the procedure described in Example 58 part c, (29mg, 37%), mp 235-236°C; 1H NMR (500MHz, d6-DMSO) 6 5.72 (2H, s, CH2), 7.72 (1H, s, Ar-H), 7.98 (1H, m, Ar-H), 8.19 (1H, m, Ar-H), 8.25 (1H, d, Ar-H), 8.52 (1H, br s, Ar-H), 8.59 (1H, d, Ar-H); MS (ES+), m/e 369 [MH]+; Anal. Found. C, 47.93; H, 2.34; N, 29.14. C15H9N8O2cl. 0.15CH2Cl2 requires C, 47.70; H, 2.46; N, 29.37%.

EXAMPLE 80 3-(5-Chloroisoxazol-3-yl)-6-(1-methylimidazol-5-yl)methyloxy -1,2,4- triazol[4,3-a]phthalazine The title compound was prepared from Intermediate 7 and 5-hydroxymethyl-1-methylimidazole using the procedure given for Example 71, 1H NMR (360MHz, CDCl3) # 3.79 (3H, s, Me), 5.68 (2H, s, CH2), 7.05 (1H, s, Ar-H), 7.38 (1H, s, Ar-H), 7.55 (1H, s, Ar-H), 7.82 (1H, t, J = 7.2Hz, Ar-H), 8.00 (1H, m, Ar-H), 8.17 (1H, d, J = 8.0Hz, Ar-H), 8.68 (1H, d, J = 8.0Hz, Ar-H); MS (ES+) m/e 382 [MH]+.

EXAMPLE 81 3-(5-Chloroisoxazol-3-yl)-6-(4-methyl-1,2,4-triazol-3-yl)met hyloxy-1,2,4- triazol[4,3-a]phthalazine The title compound was prepared from Intermediate 7 (150mg, 0. 5mmol) and 4-methyl- 1,2, 4-triazole-5-methanol (prepared using the conditions of Itoh and Okongi, EP-A-421210) following the procedure given for Example 71 (41mg, 21%) mp 239-241°C; 1H NMR (360MHz, d6-DMSO) 6 3.80 (3H, s, CH3), 5.86 (2H, s, CH2), 7.80 (1H, s, Ar-H), 7.96 91H, m, Ar- H), 8.14 (1H, m, Ar-H), 8.62 (1H, s, Ar-H); MS (ES+) m/e 383 [MH]+; Anal.

Found. C, 48.95; H, 2.98; N, 27.61. C16H11N8O2Cl. 0.21CH2Cl2 requires C, 48.60; H, 2.87; N, 27.97%.

EXAMPLE 82 6-(2-Pyridylmethyloxy)-3-(5-trifluoromethylisoxazol-3-yl)-1, 2,4- triazolo[3,4-a]phthalazine Prepared in a similar manner to Example 70 step e using a solution of trifluoromethylacetylene in dichloromethane to yield a pale yellow solid (28mg, 48%), 1H NMR (250MHz, CDCl3) 6 5.77 (2H, m), 7.30 (1H, m), 7.67 (1H, s), 7.68-8.00 (4H, m), 8.37 (1H, m), 8.64-8.75 (2H, m); MS (ES)+ 413 [MH]+.

EXAMPLE 83 3-(5-Phenylmethylisoxazol-3-yl)-6-[(2-pyridyl)methyloxy]-1,2 ,4- triazolo[3,4-a]phthalazine Prepared in a similar manner to Example 70 step e using 3-phenyl- 1-propyne to yield a solid (35mg, 57%), lH NMR (250MHz, CDCl3) # 4.23 (2H, s), 5.73 (2H, s), 6.80 (1H, s), 7.26-7.37 (6H, m), 7.72-7.97 (4H, m), 8.31 (1H, m), 8.64 (2H, m); MS (ES)+ 435 [MH]+.

EXAMPLE 84 3-[5-(2-Pyridyl)isoxazol-3-yl]-6-(2-pyridyl)methyloxy-1,2,4- triazolo[3,4- a]phthalazine Prepared in a similar manner to Example 70 step e using 2-pyridyl acetylene. lH NMR (250MHz, CDC13) 6 5.82 (2H, s), 7.28 (1H, m), 7.41 (1H, m), 7.75-8.20 (8H, m), 8.35 (1H, m), 8.68-8.70 (2H, m); MS (ES)+ 422 [MH]+.

EXAMPLE 85 3-(4-Methylisoxazol-3-yl)-6-(2-pyridyl)methyloxy-1,2,4-triaz olo[3,4- alphthalazine a) 1-Propenylacetate Dimethylaminopyridine (6.31g, 52mmol) was added to a stirred mixture of propionaldehyde (30g, 0.52mol) acetic anhydride (263.6g, 2.58mol) and and triethylamine (104.5g, 1.03mol) at room temperature under nitrogen. The mixture was stirred for 36h, poured onto ice and stirred at -200C for 0.5h, then allowed to warm to room temperature and the aqueous phase separated. This was extracted with diethyl ether (3x) and the combined organic extracts washed with saturated sodium hydrogen carbonate solution until neutralised, then washed with water (xl) and brine (x1), dried (MgSO4) and the solvent evaporated in vacuo.

Distillation at atmospheric pressure gave the title-compound (30g, 58%), bp 108-118°C; 1H NMR (250MHz, CDCl3) 6 1.65 (6H, m, CH3 E/Z), 2.16 (3H, s, OCH3 E), 2.18 (3H, s, OCH3 Z), 4.93 (1H, quintet, J = 6.8Hz, CH z), 5.43 (1H, m, CH E), 7.02 (2H, m, CH E/Z). b) 4-Methvlisoxazole-3-carboxvlic acid ethyl ester Carbethoxychloraldoxime (4. 68g, 3 lmmol) (prepared as described in J. Org. Chem. 1983, 48, 366) in diethyl ether (20ml) was added dropwise over 20min to a refluxing mixture of 1-propenyl acetate (29.98g, 0.29mol) and triethylamine (3.12g, 0.29mol) in diethyl ether (45ml). The mixture was heated under reflux for 4.5h then allowed to cool to room temperature

and poured into water (100m). The ether layer was separated, dried (MgSO4) and evaporated in vacuo. The residue was heated at 180°C for 5h then allowed to cool and the acetic acid formed distilled off (110-115°C).

The residue was purified by flash chromatography on silica gel, eluting with 10% ethyl acetate/hexane, to give the title compound (650mg, 2%), 1H NMR (250MHz, CDCl3) # 1.41 (3H, t, J=7.1Hz, CH3), 2.24 (3H, d, J = 1.1Hz, CH3), 4.44 (2H, m, CH2), 8.30 (1H, d, J = 1.1Hz, CH). c) 4-Methylisoxazole-3-carboxylic acid The title compound was prepared from the above ester using the procedure described in Example 30 part c. lH NMR (250MHz, CD Cl3) 6 2.25 (3H, d, J = 1.0Hz, CH3), 6.85 (1H, br s, OH), 8.34 (1H, q, J = 1.0Hz, Ar-H). d) 6-Chloro-3-(4-methylisoxazol-3-yl)-1,2,4-triazolo[3,4-a]phth alazine The title compound was prepared as described in Example 1 part c using the preceding acid. lH NMR (250MHz, CD Cl3) 6 2.45 (3H, d, J = 1.1Hz. CH3), 7.96 (1H, m, Ar-H), 8.09 (1H, m, Ar-H), 8.35 (1H, m, Ar-H), 8.44 (1H, d, J = 1.0Hz, CH), 8.82 (1H, m, Ar-H). e) 3-(4-Methylisoxazol-3-yl)-6-(2-pyridiyl)methyloxy-1,2,4-tria zolo[3,4- alphthalazine The title compound was prepared from the above chloride using the procedure described in Example 1 part d, mp 163.5-164.5°C; lH NMR (360MHz, CDCl3) # 2.41 (3H, d, J = 0.8Hz, CH3), 5.74 (2H, s, CH2), 7.29 (1H, m, Ar-H), 7.75-7.77 (2H, m, 2 of Ar-H), 7.84 (1H, m, ar-H), 7.95 (1H, m, Ar-H), 8.32 (1H, m, Ar-H), 8.41 (1H, d, J = 1.1Hz, Ar-H), 8.66-8.70 (2H, m, 2 of Ar-H); MS (ES)+ m/e 359 [MH]+; Anal. Found. C, 63.46; H, 3.60; N, 22.74. C19H14N6O2 requires C, 63.68; H, 3.94; N, 23.45%.

EXAMPLE 86 3-(5-Chloro-4-methylisoxazol-3-yl)-6-(2-pyridyl)methyloxy-1, 2,4- triazolo[3,4-a]phthalazine The title-compound was preparaed from ethyl 5-chloro-4- methylisoxazole-3-carboxylate (Chem. Abs. 1965, 63, 13234h) using the procedure given for Example 34, lH NMR (360MHz, CD Cl3) 6 2.37 (3H, s, Me), 5.73 (2H, s, CH2), 7.29 (1H, t, J = 4.5Hz, Ar-H), 7.75-7.86 (3H, m, 3 of Ar-H), 7.97 (1H, m, Ar-H), 8.33 (1H, d, J = 8.0Hz, Ar-H), 8.66-8.70 (2H, m, 2 of Ar-H); MS (ES)+ m/e 393 [MH]+.

EXAMPLE 87 3-(3-Methyl-1,2,4-oxadiaozol-5-yl)-6-(2-pyridyl)methyloxy-1, 2,4-triazolo[3,4- alphthalazine The title-compound was prepared in a similar manner to Example 35 part d using 3-methyl- 1,2,4-oxadiazole-5-hydrazoic acid, mp. 201-203°C; 1H NMR (360MHz, d6-DMSO) # 2.56 (3H, s), 5.65 (2H, s), 7.42 (1H, m), 7.85 (2H, m), 8.05 (1H, t, J = 7.6Hz), 8.16 (1H, t, J = 7.7Hz), 8.37 (1H, d, J = 8.2Hz), 8.60 (2H, m); MS (ES)+ m/e 360 [MH]+; Anal. Found. C, 60.32; H, 3.39; N, 26.55. C18H13N7O2. 0.1EtOAc requires C, 60.03; H, 3.78; N, 26.63%.

EXAMPLE 88 3-(3-Cyclopropyl-1,2,4-oxadiazol-5-yl)-6-(2-pyridyl)methylox y-1,2,4- triazolor3,4-alphthalazine The title-compound was prepared in a similar manner to Example 35 part d using 3-cylopropyl-1,2,4-oxadiazole-5-hydrazoic acid, mp. 229- 231°C; 1K NMR (360MHz, d6-DMSO) # 1.11 (4H, m), 2.35 (1H, m), 5.73 (2H, s), 7.42 (1H, m), 7.35 (2H, m), 8.11 (2H, m), 8.39 (1H, d, J = 8.0Hz), 8.62 (2H, m); MS (ES)+ m/e 386 [MH]+; Anal. Found. C, 62.81; H. 3.71; N, 25.35. C20H15N7O2. 0.05C6H14 requires C, 62.57; H, 4.06; N, 25.16%.

EXAMPLE 89 <BR> <BR> <BR> <BR> <BR> <BR> 3-(3-Methyl-1,2,4-oxadiazol-5-yl)-6-(1-methyl-1,2,4-triazol- 3-yl)methyloxy- 1,2,4-triazolo[3,4-a]phthalazine a) 6-Chloro-3-(3-methyl-1,2,4-oxadiazol-5-yl)-1,2,4-triazolo[3, 4- al phthalazine The title compound was prepared from 1,4-dichlorophthalazine and 3-methyl- (1,2, 2,4-oxadiazol-5-yl)hydrazoic acid (prepared using the conditions of Gregory, Warburton and Seark, CAN 78:72156) in a similar manner to Example 35 part d, lH NMR (250MHz, CDCl3) # 2.64 (3H, s, CH3), 8.03 (1H, m, ArH), 8.15 (1H, m, ArH), 8.41 (1H, d, J = 7.9Hz, ArH), 8.87 (1H, d, J = 8.5Hz, ArH); MS (ES+) m/e 287 [MH]+. b) 3-(3-Methyl-1,2,4-oxadiazol-5-yl)-6-(1-methyl-1,2,4-triazol- 3- yl)methyloxy-1,2,4-triazolo[3,4-a]phthalazine The title-compound was made from the preceding phthalazine and 1-methyl-1,2,4-triazole-3-methanol (prepared using the conditions of Itoh and Okongi, EP-A-421210) in a similar manner to Example 98, mp 283- 285°C, lH NMR (360MHz, CDC13) 6 2.60 (3H, s, CH3), 3.99 (3H, s, CH3), 5.76 (2H, s, CH2), 7.86 (1H, m, ArH), 7.99 (1H, m, ArH), 8.10 (1H, s, ArH), 8.31 (1H, d, J=8.0Hz, ArH), 8.73 (1H, d, J = 7.2Hz, ArH); MS (ES+) m/e 364 [MH]+.

EXAMPLE 90 6-(1-Benzyl-1,2,4-triazol-3-yl)-3-(5-methylisoxazol-3-yl)met hyloxy-1,2,4- triazlo[3,4-a]phthalazine and 6-(2-Benzyl-1,2,4-triazol-3-yl)-3-(5- methvlisoxazol-3-vl)methvloxv- 1,2, 4-triazolo [3,4-al phthalazine The title-compounds were prepared from 3-(5-methylisoxazol-3-yl)- 6-(1, 2, 4-triazol-3-yl)methyloxy- 1,2,4-triazolo[3,4-a]phthalazine and benzylbromide following the procedure given for Example 47. The two regioisomers were separated by M.P.L.C. [Lobar Lichroprep Si60 (40-

63µm) (Art. 10402)], eluting with 2% methanol/dichloromethane, to give the title-products (51mg, 21%); 6-(2-Benzyl-1,2,4-triazol-3-yl)-3-(5-methylisoxazol-3-yl)met hyloxy-1,2,4- triazolo[3,4-a]phthalazine (less polar isomer) 1H NMR (360MHz, CDCl3) # 2.55 (3H, s, CH3), 5.67 (2H, s, CH2), 5.79 (2H, s, CH2), 6.79 (1H, s, Ar-H), 7.07-7.09 (2H, m, 2 of Ar-H), 7.15-7.17 (3H, m, 3 of Ar-H), 7.71 (1H, t, J=8.4Hz), 7.91-7.93 (2H, m, 2 of Ar-H), 8.01 (1H, s, Ar-H), 8.64 (1H, d, J=7.8Hz, Ar-H); MS (ES+) m/e 439 [MH]+.

6-(1-Benzyl-1,2,4-triazol-3-yl)-3-(5-methylisoxazol-3-yl)met hyloxy-1,2,4- triazolo[3,4-a]phthalazine (more polar isomer) 'H NMR (360MHz, CDCl3) 6 2.56 (3H, s, CH3), 5.30 (2H, s, CH2), 5.73 (2H, s, CH2), 6.74 (1H, s, Ar-H), 6.95-6.98 (2H, m, 2 of Ar-H), 7.26-7.30 (3H, m, 3 of Ar-H), 7.79 (1H, t, J=6.3hz, Ar-H), 7.95 (1H, t, J=8.1Hz, Ar-H), 8.09 (1H, s, Ar-H), 8.29 (1H, d, J=8.1Hz, Ar-H), 8.71 (1H, d, J=7.3Hz, Ar-H); MS (ES+) m/e 439 [MH]+; Anal. Found. C, 62.91; H, 4.20; N, 23.97. C23H18N8O2, 0.25(CH3CO2C2H5) requires C, 62.53; H, 4.48; N, 24.31%.

EXAMPLE 91 6-(1-Butyl-1,2,4-triazol-3-yl)-3-(5-methylisoxazol-3-yl)meth yloxy-1,2,4- triazol[3,4-a]phthalazine The title-compound was prepared from 3-(5-methylisoxazol-3-yl)-6- (1,2, 4-triazol-3-yl)methyloxy- 1,2,4-triazolo[3,4-a]phthalazine and 1- iodobutane following the procedure given for Example 47. The two regioisomers were separated by M.P.L.C. [Lobar Lichroprep Si60 (40- 63m) (Art. 10402)], eluting with 2.5% methanol/dichloromethane, to give the title-product as the more polar isomer, lH NMR (360MHz, CDC13) 6 0.97 (3H, t, J=7.4Hz, CH3), 1.41 (2H, m, CH2), 1.23-1.41 (2H, m, CH2), 2.57 (3H, s, CH3), 4.19 (211, t, J=7.2Hz, CH2), 5.72 (2H, s, CH2), 6.98 (1H, s, Ar- H), 7.77 (1H, t, J=7.4Hz, Ar-H), 7.95 (1H, t, J=8.1Hz, Ar-H), 8.09 (1H, s, Ar-H), 8.29 (1H, d, J=8.0Hz, Ar-H), 8.68 (1H, d, J=7.9Hz); MS (ES+) m/e 405 [MH]+.

EXAMPLE 92 6-(2-Ethyl-1,2,4-triazol-3-yl)-3-(5-methylisoxazol-3-yl)meth yloxy-1,2,4- triazolo[3,4-a]phthalazine The title-compound was prepared from 3-(5-methylisoxazol-3-yl)-6- (1,2,4-triazol-3-yl)methyloxy-1,2,4-triazolo[3,4-a]phthalazi ne and iodoethane following the procedure given for Example 47. The two regioisomers were separated by M.P.L.C. [Lobar Lichroprep Si60 (40- 63µm) (Art. 10402)], eluting with 2.5% methanol/dichloromethane, to give the title-product as the less polar isomer, lH NMR (360MHz, CDC13) 6 1.52 (3H, t, J=7.2Hz, CH3), 2.58 (3H, s, CH3), 4.43 (2H, q, J=7.2Hz, CH2), 5.84 (2H, s, CH2), 6.87 (1H, d, J=0.7Hz, Ar-H), 7.82 (1H, t, J=8.3Hz, Ar-H), 7.79-7.84 (2H, m, 2 of Ar-H), 8.20 (1H, d, J=8.0Hz, Ar-H), 8.70 (1H, d, J=7.8Hz, Ar-H); MS (ES+) m/e 377 [MH]+.

EXAMPLE 93 3-(5-Methylisoxazol-3-yl)-6-(1-propyl-1,2,4-triazol-3-yl)met hyloxy-1,2,4- triazolo[3,4-a]phthalazine The title-compound was prepared from 3-(5-methylisoxazol-3-yl)-6- (1,2,4-triazol- 3-yl)methyloxy- 1,2, 4-triazolo [3,4-a]phthalazine and 1-iodopropane following the procedure given for Example 47. The two regioisomers were separated by M.P.L.C. [Lobar Lichroprep Si60 (40- 63µm) (Art. 10402)], eluting with 2.5% methanol/dichloromethane, to give the title-product as the more polar isomer, lH NMR (360MHz, CDCl3) 6 0.96 (3H, t, J=7.4hz, CH3), 1.88-1.99 (2H, m, CH2), 2.59 (3H, s, CH3), 4.16 (2H, t, J=7.1Hz, CH2), 5.72 (2H, s, CH2), 7.00 (1H, s, Ar-H), 7.81 (1H, t, J=7.3Hz, Ar-H), 7.92 (1H, t, J=7.8Hz, Ar-H), 8.10 (1H, s, Ar-H), 8.26 (1H, d, J=8.2hz, Ar-H), 8.74 (1H, d, J=8.1Hz, Ar-H); MS (ES+) m/e 391 [MH]+; Anal. Found. C, 57.72; H, 4.52; N, 27.11. C19H18N8O2. 0.8 (CH3CO2C2Hs).

0.05 CH2C12 requires C, 57.77; H, 4.90; N, 27.15%.

EXAMPLE 94 3-(5-Methylisoxazol-3-yl)-6-[1-2,2,2-trifluoroethyl)-1,2,4-t riazol-3- yl]methyloxy-1,2,4-triazolo[3,4-a]phthalazine The title-compound was prepared from 3-(5-methylisoxazol-3-yl)-6- (1,2, 4-triazol-3-yl)methyloxy- 1,2,4-triazolo[3,4-a]phthalazine and 2,2,2- trifluoroethylsulphonate following the procedure given for Example 47.

The two regioisomers were separated by M.P.L.C. [Lobar Lichroprep Si60 (40-63pm) (Art. 10402)], eluting with 2.5% methanol/dichloromethane, to give the title-product as the more polar isomer, 1H NMR (360MHz, CD Cl3) # 2.58 93H, s, CH3), 4.81 (2H, q, J=8.1Hz, CH2), 5.75 (2H, s, CH2), 6.94 (1H, d, J=0.7Hz, Ar-H), 7.80 (1H, t, J=7.2Hz, Ar-H), 7.98 (1H, t, J=8.0Hz, Ar- H), 8.26-8.28 (2H, m, Ar-H), 8.70 (1H, d, J=7.7Hz, Ar-H); MS (ES+) m/e 431 [MH] +.

EXAMPLE 95 6-(1-Ethylimidazol-5-yl)methyloxy-3-(5-methylisoxazol-3-yl)- 1,2,4- triazolo[3,4-a]phthalazine a) Methvl 1-ethylimidazoloe-5-carboxylate and methvl 1-ethvlimidazole-4- carboxvlate Potassium carbonate (0.66g, 4.8mmol) and ethyl iodide (0.67ml, 8.4mmol) were added successively to a stirred suspension of methyl 4- imidazolecarboxylate (1.00g, 7.93mmol) in DMF (12ml) at 0°C under nitrogen. The mixture was stirred at 0°C for 1h and then at room temperature overnight. The solvent was evaporated in vacuo and the residue partitioned between dichloromethane and water. The aqueous layer was separated and re-extracted with dichloromethane (xl) and the combined organic extracts were dried (MgSO4) and evaporated in vacuo.

Flash chromatography of the residue on alumina, eluting with 50-100% ethyl acetate/hexane (gradient elution), gave the title-esters: methyl 1-ethylimidazole-5-carboxylate (less polar isomer) (0.235g, 19%), 1H NMR (360MHz, CD Cl3) 5 1.44 (3H, t, J=7.2Hz, CH3), 3.86 (3H, s, Me),

4.35 (2H, q, J=7.2hz, CH2), 7.60 (1H, s, Ar-H), 7.73 (1H, s, Ar-H); MS (ES+) m/e 155 [MH]+ methyl 1-ethylimidazole-4-carboxylate (more polar isomer) (0.358g, 29%), 1H NMR (360NHz, CDCl3) # 1.47 (3H, t J=7.4Hz, CH3), 3.89 (3H, s, CH3), 4.03 (2H, q, J=7.4Hz, CH2), 7.50 (1H,m s, Ar-H), 7.64 (1H, s, Ar-H); MS (ES+) 155 [MH]+. b) 5-Hydroxymethyl-1-ethylimidazole Lithium aluminium hydride 1.49ml of a 1.0M solution in THF, 1.49mmol) was added dropwise to a stirred solution of methyl 1- ethylimidazole-5-carboxylate (230mg, 1.49mmol) in THF (10ml) at 0°C under nitrogen. The mixture was stirred at 0°C for 0.5h and at room temperature for 1.8h, then recooled to 0°C and saturated aqueous sodium sulphate solution (1.5ml) added dropwise. The mixture was stirred at room temperature, filtered through a pad of Hyflo and evaporated in vacuo. The residue was azeotroped with ethanol (xl) and then flash chromatographed on silica gel, eluting with 10% methanol/dichloromethane, to give the title-alcohol (175mg, 93%), 'H NMR (360MHz, CD Cl3) 5 1.47 (3H, t, J=7.4Hz, CH3), 4.07 (2H, q, J=7.3Hz, CH2), 4.63 (2H, s, CH20), 6.90 (1H,s , Ar-H), 7.47 (1H, s, Ar-H); MS (ES+) 127 [MH]+. c) 6-(1-Ethylimidazol-5-yl)-methyloxy-3-(5-methylisoxazol-3-yl) -1,3,4- triazolo 4-alphthalazine The title-compound was prepared from the preceding alcohol and Intermediate 1 following the procedure given for Example 71, lH NMR <BR> <BR> <BR> <BR> (360MHz, CDCl3) # 1.52 (3H, t, J=7.4Hz, CH3), 2.59 (3H, s, CH3), 4.14 (2H, q, J=7.3Hz, CH2), 5.68 (2H, s, CH2O), 6.86 (1H, d, J=0.7Hz, Ar-H), 7.38 (1H, s, Ar-H), 7.61 (1H, s, Ar-H), 7.79 (1H, dd, J=7.2 and 8.4Hz, Ar-H), 7.95 (1H, dd, J=7.1 and 8.3Hz, Ar-H), 8.14 (1H, d, J=7.8Hz, Ar-H), 8.70 (1H, d, J=8.3Hz, Ar-H); MS (ES+) m/e 376 [MH]+; Anal. Found. C, 60.51; H, 4.39; N, 25.88. C19H17N7O2 requires C, 60.79; H, 4.56; N, 26.12%.

EXAMPLE 96 6-(1-Ethylimidazol-4-yl)methyloxy-3-(5-methylisoxazol-3-yl)- 1,2,4- triazolor3,4-alphthalazine The title-compound was prepared from methyl 1-ethylimidazole-4- carboxylate using the procedure given for Example 95 parts b and c, 'H NMR (360MHz, CDCl3) # 1.46 (3H, t, J=7.4Hz, CH3), 2.59 (3H, s, CH3), 3.98 (2H, q, J=7.3Hz, CH2), 5.61 (2H, s, CH20), 6.90 (1H, s, Ar-H), 7.48 (1H, d, J=1.1Hz, Ar-H), 7.69 (1H, d, J=1.lHz, Ar-H), 7.77 (1H, m, Ar-H), 7.91 (1H, m, Ar-H), 8.27 (1H, d, J=8.2Hz, Ar-H), 8.66 (1H, d, J=7.111z, Ar- H); MS (ES+) m/e 376 [MH]+; Anal. Found. C, 60.67; H, 4.40; N, 25.6 5.

C19H17N7O2. 0.05C4H8O2 requires C, 60.72; H, 4.62; N, 25.82%.

EXAMPLE 97 6-(1-Ethyl-1,2,3-triazol-5-yl)methyloxy-3-(5-methylisoxazol- 3-yl)-1,2,4- triazolo[3,4-a]phthalazine a) Methyl 1-ethyl-1,2,3-triazole-4-carboxylate, methyl 2-ethyl-1,2,3- triazole-4-carboxylate and methyl 1-ethyl-1,2,3-triazole-5-carboxylate Potassium carbonate (3.3g, 24mmol) and ethyl iodide (6.4g, 4lmmol) were added successively to a stirred solution of methyl 1,2,3- triazole-4-carboxylate (J. Het. Chem. 1976, 13, 589) (5.0g, 39mmol) in DMF (60ml) at 0°C under nitrogen. The mixture was stirred at 0°C for 1h and then at room temperature overnight. The solvent was evaporated in vacuo and the residue partitioned between dichloromethane and water.

The aqueous layer was separated and extracted with dichloromethane (xl) and the combined organic extracts were dried (MgSO4) and evaporated in vacuo. Flash chromatography of the residue on silica, eluting with 30- 60% ethyl acetate/hexane (gradient elution) gave the title-esters: methyl 1-ethyl-1, 2 3-triazole-4-carboxvlate (most polar isomer) (1. 22g, <BR> <BR> 20%), 1H NMR (250MHz, CDCl3) 5 1.60 (3H, t, J=7.3Hz, CH2), 3.96 (3H, s,

CH3), 4.55 (2H, q, J=7.4Hz, CH3), 8.05 (1H, s, Ar-H); MS (ES+) m/e 156 @[MH]+. methyl 2-ethyl-1,2,3-triazole-4-carboxylate (least polar isomer) (2.59g, 42%), 1H NMR (250MHz, CDCl3) # 1.60 (3H, t, J=7.4Hz, CH3), 3.96 (3H, s, CH3), 4.49 (2H, q, J=7.4Hz, CH2), 8.11 (1H, s, Ar-H); MS (ES+) m/e 156 [MH]+. methyl 1-ethyl-1,2,3-triazole-5-carboxylate (880g, 14%), 1H NMR <BR> <BR> <BR> (250MHz, CDCl3) # # 1.54 (3H, t, J=7.3Hz, CH3), 3.94 (3H, s, CH3), 4.78 (2H, q, J=7.2Hz, CH2), 8.13 (1H, s, Ar-H); MS (ES+) m/e 156 [MH]+. b) 5-Hydroxymethyl-1-ethyl-1,2,3-triazole The title-compound was prepared from methyl 1-ethyl-1,2,3- triazole-5-carboxylate using the procedure given for Example 95 part b, 1H NMR (250MHz, CDCl3) # 1.88 (3H, t, J=7.3Hz, CH3), 2.74 (1H, br s, OH), 4.76 (2H, q, J=7.3Hz, CH2), 5.09 (2H, s, CH2), 7.87 (1H, s, Ar-H); MS (ES+) m/e 128 [MH]+. c) 6-(1-Ethylimidazol-1,2,3-triazol-5-yl)methyloxy-3-(5-methyli soxazol-3- yl)-1,2,4-triazolo[3,4-a]phthalazine The title-compound was prepared from the preceding alcohol and Intermediate 1 following the procedure given for Example 71, 1H NMR <BR> <BR> <BR> (360MHz, CDCl3) # 1.62 (3H, t, J=7.3Hz, CH3), 2.59 (3H, d, J=0.7Hz, CH3), 4.57 (2H, q, J=7.3Hz, CH2), 5.80 (2H, s, CH2), 6.85 (1H, d, J=0.8Hz, Ar-H), 7.83 (1H, m, Ar-H), 7.99 (1H, m, Ar-H), 8.08 (1H, s, Ar-H), 8.13 (1H, d, J=8.0Hz, Ar-H), 8.70 (1H, d, J=8.0Hz, Ar-H); MS (ES+) m/e 377 [MH]+; Anal. Found. C, 57.37; H, 4.11; N, 29.73. C18H16N8O2 requires C, 57.44; H, 4.28; N, 29.77%.

EXAMPLE 98 6-(1-Ethyl-1,2,3-triazol-4-yl)methyloxy-3-(5-methylisoxazol- 3-yl)-1,2,4- triazolo[3,4-a]phthalazine a) 4-Hydroxymethyl-1-ethyl-1,2,3-triazole The title-compound was prepared from methyl 1-ethyl-1,2,3- triazole-4-carboxylate (Example 97 part a) using the procedure given for Example 95 part b, lH NMR (360MHz, CD Cl3) 6 1.56 (3H, t, J=7.3Hz, CH3), 2.81 (1H, t, J=6.0Hz, OH), 4.41 (2H, Q, J=7.3Hz, CH2), 4.79 (2H, d, J=5.9Hz, CH2), 7.55 (1H, s, Ar-H); MS (ES+) m/e 128 [MH]+. b) 6-(1-Ethyl-1,2,3-triazol-4-yl)methyloxy-3-(5-methylisoxazol- 3-yl)-1,2,4- triazolo[3,4-a]phthalazine Lithium hexamethyldisilazide (0.84ml of a 1.0M solution in tetrahydrofuran, 0.8mmol) was added dropwise to a stirred solution of the preceding alcohol (98mg, 0.7mmol) in dry N,N-dimethylformamide (20ml) at -100C under nitrogen. The mixture was stirred at -100C for 0.5h then Intermediate 1 (200mg, 0.7mmol) added in one portion and stirred at - 10°C for 2h and then at room temperature overnight. The solvent was evaporated in vacuo and the residue taken up in water and extracted into dichloromethane (x3). The combined extracts were dried (MgSO4) and evaporated in vacuo. Flash chromatography of the residue on silica gel, eluting with 2% methanol/dichloromethane, followed by recrystallisation from ethyl acetate gave the title-compound as a white solid (lllmg, 42%), 'H NMR (360MHz, CDCl3) 5 1.56 (3H, t, J=7.4Hz, CH3), 2.61 (3H, s, CH3), 4.41 (2H, q, J=7.4Hz, CH2), 5.77 (2H, s, CH2), 6.90 (1H, d, J=0.8Hz, Ar-H), 7.80 (1H, m, Ar-H), 7.94 (1H, m, Ar-H), 8.25 (1H, d, J=8.1Hz, Ar-H), 8.66 (1H, d, J=8.0Hz, Ar-H), 8.84 (1H, s, Ar-H); MS (ES+) m/e 377 [MH]+; Anal.

Found. C, 57.02; H, 4.11; N, 29.61. C18H18N8O2 requires C, 57.44; H, 4.28: N, 29.77%.

EXAMPLE 99 6-(2-Ethyl-1,2,3-triazol-4-yl)methyloxy-3-(5-methylisoxazol- 3-yl)-1,2,4- triazolo[3,4-a]phthalazine a) 2-Ethyl-4-hydroxymethyl-1,2,3-triazole The title-compound was prepared from methyl 2-ethyl-1,2,3- triazole-4-carboxylate (prepared as described in Example 97 part a) using the procedure given for Example 95 part b, 1H NMR (250MHz, CDCl3) 6 1.56 (3H, t, J=7.3Hz, CH3), 2.08 (1H, t, J=5.9Hz, OH), 4.45 (2H, q, J=7.3Hz, CH2), 4.77 (2H, d, J=5.8Hz, CH2), 7.56 (1H, s, Ar-H); MS (ES+) m/e 127 [MH]+. b) 6-(2-Ethyl-1,2,3-triazol-4-yl)methyloxy-3-(5-methylisoxazol- 3-yl)-1,2,4- triazolo[3,4-a]phthalazine The title-compound was prepared from the preceding alcohol and Intermediate 1 following the procedure given in Example 98, lH NMR (360MHz, CDCl3) # 1.58 (3H, t, J=7.4Hz, CH3), 2.59 (3H, s, CH3), 4.48 (2H, q, 7.3Hz, CH2), 5.74 (2H, s, CH2), 6.90 (1H, s, Ar-H), 7.80 (1H, m, Ar-H), 7.94 (1H, m, Ar-H), 8.11 (1H, s, Ar-H), 8.22 (1H, d, J=8.0Hz, Ar-H), 8.66 (1H, d, J=8.0Hz, Ar-H); MS (ES+) m/e 377 [MH]+; Anal. Found. C, 57.77; H, 4.15; N, 29.63. C18H16N8O2 requires C, 57.44; H, 4.28; N, 29.77%.

EXAMPLE 100 3-(5-Methylisoxazol-3-yl)-6-(1-methyltetrazol-5-yl)methyloxy -1,2,4- triazolo[3,4-a]phthalazine The title-compound was prepared from Intermediate 2 and 5-chloromethyl-1-methyltetrazole (Chem. Pharm. Bull., 1989, 37, 322) following the procedure given for Example 15 part b, lH NMR (360MHz, CDCl3) # 2.60 (3H, s, CH3), 4.33 (3H, s, CH3), 6.03 (2H, s, CH2), 6.89 (1H, s, Ar-H), 7.91 (1H, t, J=7.4Hz, Ar-H), 8.04 (1H, t, J=8.3Hz, Ar-H), 8.25 (1H, d, J=7.9Hz, Ar-H), 8.70 (1H, d, J=7.7Hz, Ar-H); MS (ES+) m/e 364 [MH]+.

EXAMPLE 101 6-(Imidazol-2-yl)methyloxy-3-(5-methylisoxazol-3-yl)-1,2,4-t riazolo[3,4- a]phthalazine a) 3-(5-Methylisoxazol-3-yl)-6-{[1-(2- trimethylsilyl)ethyloxymethyl]imidazol-2-yl}methyloxy-1,2,4- triazolo[3,4- al phthalazine Prepared from Intermediate 1 and 1-[(2- trimethylsilyl)ethyloxymethyl] imidazole-2-methanol (CAN 121:82872) following the procedure of Example 98, lH NMR (250MHz, CDCl3) 6 0.01 (9H, s, Si(C113)3), 0.89 (2H, t, J=8.2Hz SiCH2), 2.65 (3H, s, CH3), 3.58 (2H, t, J=8.2Hz, CH2O), 5.57 (2H, s, CH2O), 5.86 (2H, s, CH2O), 6.98 (1H, d, J=0.7Hz, Ar-H), 7.17 (1H, d, J=0.7Hz, ArH), 7.18 (1H, s, ArH), 7.81 (1H, t, J=7.7Hz, Ar-H), 7.87 (1H, t, J=7.7Hz, Ar-H), 8.27 (1H, d, J=7.7Hz, Ar-H), 8.74 (1H, d, J=7.7Hz, Ar-H); MS (ES+) 478 (MH)+. b) 6-(Imidazol-2-yl)methyloxyx-3-(5-methylisoxazol-3-yl)-1,2,4- triazolo[3,4- a]phthalazine The preceding protected imidazole (0.4g, 0.84mmol) was suspended in trifluoroacetic acid (5ml) and dichloromethane (5ml) and stirred for 16h.

The solvent was removed and the residue was purified by column chromatography on silica gel, eluting with 5% methanol/dichloromethane, to yield the product (0.08g, 27%), mp 188-189°C, 1H NMR (250MHz, d6- DMSO) 6 2.60 (3H, s, Me), 5.62 (2H, s, CH2O), 7.13 (1H, br s, ArH), 7.19 (1H, s, ArH), 7.94 (1H, t, J=7.7Hz, ArH), 8.10 (1H, t, J=7.7Hz, ArH), 8.22 (1H, d, J=7.7Hz, Ar-H), 8.60 (1H, d, J=7.7Hz, Ar-H), 12.46 (1H, br s, NH); MS (ES+) 348 (MH)+; Anal. Found. C, 58.13; H, 3.58; N, 27.42. C17H13N7O2.

0.25(H2O) requires C, 58.03; H, 3.87; N, 27.87%.

example 102 3-(5-Methylisoxazol-3-yl)-6-(2-methylpyrazol-3-yl)methyloxy- 1,2,4- triazolo[3,4-a]phthalazine The title-compound was prepared from Intermediate 1 and 1- methyl-5-hydroxymethylpyrazole (Bioorg. Med. Chem. Lett. 1997, 7, 1409) following the procedure given in Example 71, mp 270-270.5°C; lH NMR (250MHz, CDCl3) # 2.60 (3H, s, CH3), 4.03 (3H, s, CH3), 5.71 (2H, s, CH2), 6.60 (1H, d, J=1.911z, ArH), 6.86 (1H, s, ArH), 7.26 (1H, d, J=1.8Hz, ArH), 7.82 (1H, m, ArH), 7.98 (1H, m, ArH), 8.18 (1H, d, J=7.9Hz, ArH), 8.70 (1H, d, J=7.9Hz, ArH); MS (ES+) m/e 362 [MH]+.

EXAMPLE 103 3-(5-Methylisoxazol-3-yl)-6-(1-methylpyrazol-3-yl)methyloxy- 1,2,4- triazolo[3,4-a]phthalazine a) 3-(5-Methylisoxazol-3-yl)-6-(4-toluenesulphonyloxy)-1,2,4-tr iazolo[3,4- al phthalazine 4-Toluenesulphonyl chloride (382mg, 2mmol) was added to a solution of Intermediate 2 (267mg, lmmol) and triethylamine (202mg, 2mmol) in dichloromethane (7ml) at 0°C and stirred for 2h. The solvent was removed and the residue was purified by column chromatography on silica gel, eluting with ethyl acetate/dichloromethane (1:1), to yield the product as a white solid (380mg, 90%), 1H NMR (250MHz, CD Cl3) 6 2.50 (3H, s, CH3), 2.62 (3H, s, CH3), 6.81 (1H, s, ArH), 7.45 (2H, d, J=8.2Hz, 2 of ArH), 7.93 (1H, m, ArH), 8.05 (1H, m, ArH), 8.26-8.32 (3H, m, 3 of ArH), 8.74 (1H, d, J=7.5Hz, ArH); MS (ES+) m/e 422 [MH]+. b) 3-(5-Methylisoxazol-3-yl)-6-(1-methylpyrazol-3-yl)methyloxyx 1,2,4- triazolo « 4-alphthalazine The title-compound was prepared from the preceding phthalazine and 1-methyl-3-hydroxymethylpyrazole (Zh. Obshch. Khim. 1982, 52, 2598) in a similar manner to Example 98, mp 243-244.5°C, lH NMR <BR> <BR> (250MHz, CDCl3) # 2.60 (3H, s, CH3), 3.94 (3H, s, CH3), 5.66 (2H, s, CH2),

6.64 (1H, d, J=2.2Hz, ArH), 6.95 (1H, s, ArH), 7.38 (1H, d, J=2.2Hz, ArH), 7.81 (1H, m, ArH), 7.97 (1H, m, ArH), 8.25 (1H, d, J=8.1z, ArH), 8.70 (1H, d, J=7.5Hz, ArH); MS (ES+) m/e 362 [MH]+; Anal. Found. C, 56.33; H, 4.56; N, 25.36, C18H15N7O2 requires C, 56.32; H, 4.59; N, 25.54%.

EXAMPLE 104 3-(5-Methylisoxazol-3-yl)-6-(1-methylpyrazol-4-yl)methyloxy- 1,2,4- triazolo[3,4-a]phthalazine The title-compound was prepared from Intermediate 1 and 1-methyl-4-hydroxymethylpyrazole following the procedure given for Example 71, mp 212-213°C; 1H NMR (250MHz, CDCl3) 6 2.60 (3H, s, CH3), 3.89 (3H, s, NCH3), 5.56 (2H, s, CH20), 6.88 (1H, s, ArH), 7.74 (1H, s, ArH), 7.82 (1H, t, J=7.7Hz, ArH), 7.96 (1H, t, J=7.7Hz, ArH), 8.04 (1H, s, ArH), 8.18 (1H, d, J=7.7Hz, ArH), 8.68 (1H, d, J=7.7Hz, ArH); MS (ES+) 362 (MH)+.

EXAMPLE 105 3-(5-Ethylisoxazol-3-yl)-6-(2xmethyl-1,2,4-triazol-3-yl)meth yloxy-1,2,4- triazolo[3,4-a]phthalazine a) 5- [2-(Phenoxythiocarbonyloxy)ethyl] isoxazole - 3-carboxylic acid ethyl ester Pyridine (2.4g, 3lmmol) was added to a stirred solution of 5-hydroxyethylisoxazole-3-carboxylic acid ethyl ester (4.75 g, 26mmol) (prepared analogously to Example 64 part a) in dichloromethane (150ml) under nitrogen at room temperature. The mixture was cooled to 0°C and phenyl chlorothionoformate (5.3g, 3lmmol) was added dropwise. The mixture was stirred at 0°C for 1h and at room temperature for 2h, then diluted with dichloromethane (200ml) and washed with water (x2). The organic layer was dried (MgS04) and evaporated in vacuo. Flash chromatography of the residue on silica gel, eluting with 20% ethyl acetate/hexane, gave the title-compound (6.7g, 81%), lH NMR (250MHz,

CDCl3) # 1.43 (3H, t, J=7.1Hz, CH3), 3.37 (2H, t,J=6.3Hz, CH2), 4.46 (2H, q, J=7.1Hz, CH2), 4.83 (2H, t, J=6.3Hz, CH2), 6.60 (1H, s, Ar-H), 7.08-7.11 (2H, m, 2 of Ar-H), 7.29 (1H, m, Ar-H), 7.38-7.46 (2H, m, 2 of Ar-H); MS (ES+) m/e 322 [mh]+, m/e 168 [MH - 154]+. b) 5-Ethvlisoxazole-3-carboxylic acid Tris(trimethylsilyl) silane (8. 9g, 36mmol) and azobisisobutyronitrile (153mg, 2%w/w) were added successively to a stirred solution of the preceding ester (7.66g, 24mmol) in toluene (180ml) at room temperature.

The mixture was heated at 80°C for 3h then cooled to room temperature and the solvent evaporated in vacuo. Flash chromatography of the residue on silica gel, eluting with 0%-10% ethyl acetate/hexane (gradient elution), yielded crude 5-ethylisoxazole-3-carboxylic acid ethyl ester. The crude material was taken up in methanol (30ml) and aqueous sodium hydroxide solution (60ml, approx. 1.2M) added dropwise with stirring. The mixture was stirred at room temperature for 1h then the solvents evaporated in vacuo and the residue taken up in water and washed with dichloromethane (x3). The aqueous phase was acidified using 2M hydrochloric acid and extracted into dichloromethane (x4). The combined extracts were dried (MgSO4) and evaporated in vacuo to yield the title- compound as a white solid (1.15g, 34%); 1H NMR (250MHz, CDCl3) 6 1.35 (3H, t, J=7.6Hz, CH3), 2.86 (2H, q, J=7.6Hz, CH2), 5.55 (1H, br s, OH), 6.48 (1H, s, Ar-H). c) 6-Chloro-3-(5-ethylisoxazol-3-yl)-1,2,4-triazolo[3,4-a]phtha lazine The title-compound was prepared from the preceding acid following the procedure given for Example 1 part c, 1H NMR (250MHz, CD Cl3) 6 1.42 (3H, t, J=7.6Hz, CH3), 2.94 (2H, q, J=7.6Hz, CH2), 6.89 (1H, s, Ar-H), 7.96 (1H, m, Ar-H), 8.08 (1H, m, Ar-H), 8.35 (1H, m, Ar-H), 8.81 (1H, m, Ar-H); MS (ES+) m/e 302 FIH]+.

d) 3-(5-Ethylisoxazol-3-yl)-6-(2-methyl-1,2,4-triazol-3-yl)meth yloxy-1,2,4- triazolo[3,4-a]phthalazine The title-compound was prepared from the preceding chloride and 2-methyl-1,2,4-triazole-3-methanol (prepared using the conditions of Itoh and Okongi, EP-A-421210), following the procedure given in Example 98, mp 240-242°C; 1H NMR (360MHz, CDCl3) # 1.42 (3H, t, J=7.6Hz, CH3), 2.92 (2H, q, J=7.5Hz, CH2), 4.11 (3H, s, CH3), 5.85 (2H, s, CH2), 6.88 (1H, s, Ar-H), 7.83 (1H, m, Ar-H), 7.93 (1H, s, Ar-H), 7.99 (1H, m, Ar-H), 8.23 (1H, d, J=7.9Hz, Ar-H), 8.70 (1H, d, J=8.0Hz, Ar-H); MS (ES+) m/e 377 [MH]+; Anal. Found. C, 56.67; H, 4.15; N, 28.89. C18H16N8O2, 0.1CH2Cl2 requires C, 56.49; H, 4.24; N, 29.11%.

EXAMPLE 106 3-(5-Ethylisoxazol-3-yl)-6-(1-methyl-1,2,4-triazol-3-yl)meth yloxy-1,2,4- triazolo[3,4-a]phthalazine The title-compound was prepared from 6-chloro-3-(5-ethylisoxazol-3- yl)- 1,2, 4-triazolo [4, 3-a]phthalazine (prepared as described in Example 105 part c) and 3-hydroxymethyl-1-methyl- 1,2, 4-triazole (prepared using the conditions of Itoh and Okongi, EP-A-421210), following the conditions described in Example 98, mp 236-238°C; lH NMR (360MHz, CD Cl3) 6 1.42 (3H, t, J=7.5Hz, CH3), 2.94 (2H, q, J=7.4Hz, CH2), 3.97 (3H, s, CH3), 5.73 (2H, s, CH2), 6.99 (1H, s, Ar-H), 7.79 (1H, m, Ar-H), 7.95 (1H, m, Ar-H), 8.08 (1H, s, Ar-H), 8.27 (1H, d, J=7.8Hz, Ar-H), 8.70 (1H, d, J=7.8Hz, Ar- H); MS (ES+) m/e 377 [MH]+; Anal. Found. C, 55.55; H, 4.16; N, 28.38.

C18H16N8O2. 0.2CH2Cl2 requires C, 55.57; H, 4.20; N, 28.49%.

EXAMPLE 107 3-(5-Ethylisoxazol-3-yl)-6-(pyrazin-2-yl)methyloxy-1,2,4-tri azolo[3,4- alphthalazine The title-compound was prepared from 6-hydroxy-3-(5-ethylisoxazol- 3-yl)-1,2,4-triazolo[3,4-a]phthalazine (prepared from 6-chloro-3-(5-

ethylisoxazol-3-yl)-1,2,4-triazolo[3,4-a]phthalazine, Example 105 part c, using conditions described for the preparation of intermediate 2) and 2-chloromethylpyrazine (prepared as described in Example 15 part a) using the procedure described in Example 15 part b, 1H NMR (360MHz, CDCl3) # 1.42 (3H, t, J=7.6Hz, CH3), 2.94 (2H, q, J=7.6Hz, CH2), 5.83 (2H, s, CH2), 6.84 (1H, s, Ar-H), 7.84 (1H, m, Ar-H), 7.98 (1H, m, Ar-H), 8.30 (1H, d, J=7.9Hz, Ar-H), 8.60-8.64 (2H, m, 2 of Ar-H), 8.70 (1H, m, Ar-H), 9.15 (1H, d, J=1.3Hz, Ar-H); MS (ES+) m/e 374 [MH]+; Anal. Found. C, 61.16; H, 3.79; N, 26.19. C19H15N7O2 requires C, 61.12; H, 4.05; N, 26.26%.

EXAMPLE 108 6-(1-Ethyl-1,2,3-triazol-4-yl)methyloxy-3-(3-isoxazolyl)-1,2 ,4-triazolo[3,4- alphthalazine The title-compound was prepared from 6-chloro-3-(3-isoxazolyl)- 1,2,4-triazolo[3,4-a]phthalazine (prepared as described in Example 34, step b) and 4-hydroxymethyl-1-ethyl-1,2,3-triazole (prepared as described in Example 98 part a), following the procedure described in Example 98, but performing the reaction at-45°C. 1H NMR (360MHz, CDCl3) 6 1.55 (3H, t, J=7.5Hz, CH3), 4.40 (2H, q, J=7.4Hz, CH2), 5.78 (2H, s, CH2), 7.31 (1H, d, J=1.7Hz, Ar-H), 7.82 (1H, m, Ar-H), 7.95 (1H, m, Ar-H), 8.27 (1H, d, J-7.8Hz, Ar-H), 8.64-8.66 (2H, m, 2 of Ar-H), 8.69 (1H, s, Ar-H); MS (ES+) m/e 363 [MH]+; Anal. Found. C, 56.24; H, 3.70; N, 30.65. C17H14N8O2 requires C, 56.35; H, 3.89; N, 30.92%.

EXAMPLE 109 6-(1-Ethyl-1,2,4-triazol-3-yl)methyloxy-3-(3-isoxazolyl)-1,2 ,4-triazolo[3,4- a]phthalazine a) 3-(3-lsoxazolyl)-6-[2-{[2-(trimethylsilyl)ethoxy]methyl}-1,2 ,4-triazol-3- yl]methyloxy-1,2,4-triazolo[3,4-a]phthalazine The title-compound was prepared from 6-chloro-3-(3-isoxazolyl)- 1,2,4-triazolo[3,4-a]phthalazine (described in Example 34, part b) and 3- (hydroxymethyl)-2-{[2-(trimethylsilyl)ethoxy]methyl}-1,2,4-t riazole (described in Example 45, part c) following the procedure described in Example 45, part d, 1H NMR (360MHz, CDC13) 6 0.00 (9H, s, 3 of CH3), 0.88 (2H, q, J=8.4Hz, CH2), 3.67 (2H, t, J=8.3HZ, CH2), 5.84 (2H, s, CH2), 5.92 (2H, s, CH2), 7.30 (1H, d, J=1.7Hz, Ar-H), 7.89 (1H, t, J=7.1Hz, Ar-H), 7.96 (1H, s, Ar-H), 8.02 (1H, t, J=7.6Hz, Ar-H), 8.32 (1H, d, J=8.2Hz, Ar- H), 8.70 (1H, s, Ar-H), 8.75 (1H, d, J=8.2Hz, Ar-H). b) 3-(3-Isoxazolyl)-6-(1,2,4-triazol-3-yl)methyloxy-1,2,4-triaz olo[3,4- alphthalazine The title-compound was prepared from the preceding phthalazine using the procedure in Example 46, 1H NMR (250MHz, d4-MeOH) 6 5.73 (2H, s, CH2), 7.48 (1H, s, Ar-H), 7.95 (1H, m, Ar-H), 8.05-8.07 (2H, m, 2 of Ar-H), 8.38 (1H, m, Ar-H), 8.60 (1H, m, Ar-H), 8.99 (1H, s, Ar-H). c) 6-(1-Ethyl-1,2,4-triazol-3-yl)methyloxy-3-(3-isoxazolyl)-1,2 ,4-triazolo[3,4- a]phthalazine The title compound was prepared from the preceding phthalazine and iodoethane using the procedure described in Example 47 at -40°C, 1H NMR (360MHz, CDCl3) 6 1.56 (3H, t, J=7.4Hz, CH3), 4.24 (2H, q, J=7.4Hz, CH2), 5.73 (2H, s, CH2), 7.41 (1H, d, J=1.7Hz, Ar-H), 7.79 (1H, t.

J=7.6Hz, Ar-H), 7.96 (1H, t, J=8.3Hz, Ar-H), 8.11 (1H, s, Ar-H), 8.28 (1H. d, J=8.2Hz, Ar-H), 8.73 (1H, d, J=1.7Hz, Ar-H), 8.76 (1H, d, J=8.2Hz, Ar- H); MS (ES+) m/e 363 [MH]+.

EXAMPLE 110 6-(1-Ethyl-1,2,3-triazol-5-yl)methyloxy-3-(3-isoxazolyl)-1,2 ,4-triazolo[3,4- a]phthalazine The title-compound was prepared from 6-chloro-3-(3-isoxazolyl)- 1,2,4-triazolo[3,4-a]phthalazine (prepared as described in Example 34 step b) and 5-hydroxymethyl-1-ethyl-1,2, 3-triazole (prepared as described in Example 97 part b), following the procedure given for Example 71 but performing the reaction at -45°C; 1H NMR (360MHz, CD Cl3) 6 1.62 (3H, t, J=7.2Hz, CH3), 4.58 (2H, q, J=7.3Hz, CH2), 5.81 (2H, s, CH2), 7.25 (1H, d, J=1.8Hz, Ar-H), 7.84 (1H, m, Ar-H), 7.99 (1H, m, Ar-H), 8.08 (1H, s, Ar-H), 8.14 (1H, d, J=7.Hz, Ar-H), 8.66 (1H, d, J=1.8Hz, Ar-H), 8.72 (1H, d, J=7.8Hz, Ar-H); MS (ES+) m/e 363 [MH]+; Anal. Found. C, 56.47; H, 3.68; N, 30.82. C17H14N8O2 requires C, 56.35; H, 3.89; N, 30.92%.

EXAMPLE 111 6-(1-Ethylimidazol-4-vl)-4-(3-isoxazolyl) methvlOxy-1 2, 4-triazolo [3,4- alphthalazine The title-compound was prepared from 6-chloro-3-(3-isoxazolyl)- 1,2,4-triazolo[3,4-a]phthalazine (described in Example 34, part c) and 1-ethylimidazole-4-methanol using the conditions described in Example 98, 1H NMR (360MHz, CDCl3) # 1.45 (3H, t, J=7.3Hz, CH3), 3.96 (2H, q, J=7.3Hz, CH2), 5.62 (2H, s, CH2), 7.31 (1H, d, J=1.7Hz, Ar-H), 7.47 (1H, d, J=1.1Hz, Ar-H), 7.67 (1H, d, J=1.1Hz, Ar-H), 7.78 (1H, t, J=8.6Hz, Ar-H), 7.92 (1H, t, J=6.4Hz, Ar-H), 8.28 (1H, d, J=8.1Hz, Ar-H), 8.70-8.73 (2H, m, 2 of Ar-H); MS (ES+) m/e 362 [MH]+.

EXAMPLE 112 6-(2-Ethyl-1,2,4-triazol-3-yl)-3-(3-isoxazolyl)methyloxy-1,2 ,4-triazolo[3,4- a]phthalazine a) 2-Ethyl-1,2,4-triazole-3-methanol To a solution of 1,2,4-triazole (lOg, 0.145mol) in N,N- dimethylformamide (150ml) under nitrogen at room temperature was added sodium hydride (6.4g of a 60% dispension in oil, 0.16mol). The mixture was stirred for 0.5h and cooled to 0°C. Iodoethane (14ml, 0.174mol) was added and stirred for 1h at room temperature. The solvent was removed in vacuo and the residue dissolved in ethyl acetate (300ml) and washed with water (3x150ml). The organic layer was dried (MgSO4) and evaporated in vacuo, and the crude product purified by vacuum distillation (bp 1200C at 20mmHg) to give the ethylated triazole (7.49g, 41%). A solution of this material (2.4g, 0.025mol) in tetrahydrofuran (35ml) at -40°C under nitrogen was treated with n-butylithium (16.24ml of a 1.6M solution in hexane, 0.026mol) over 0.25h. After 0.25h, N,N- dimethylformamide (2.03ml, 0.026mol) was added and the mixture allowed to warm to room temperature over 2h. Sodium borohydride (1.0g, 0.03mol) and methanol (20ml) were added and the reaction mixture stirred for 12h. The solvent was evaporated in vacuo and the crude material mixed with water (50ml) and extracted into dichloromethane (6x50ml). The combined organic extracts were dried (MgSO4) evaporated in vacuo and the residue purified by chromatography on silica gel, eluting with 0-5% methanol/dichloromethane (gradient elution), to give the title- compound (0.5g, 16%), lH NMR (360MHz, CDCl3) 6 1.47 (3H, t, J=7.3Hz, CH3), 4.24 (2H, q, J=7.3Hz, CH2), 4.75 (2H, s, CH2), 5.14 (1H, br s, OH), 7.26 (1H, s, Ar-H). b) 6-(2-Ethyl-1,2,4-triazol-3-yl)-3-(3-isoxazolyl)methyloxy-1,2 ,4- triazolo [3.4-al phthalazine The title-compound was prepared from 6-chloro-3-(3-isoxazolyl)- 1,2,4-triazolo[3,4-a]phthalazine (described in Example 34, part c) and 2-

ethyl-1,2,4-triazole-3-methanol using the conditions described in Example 71 at -40°C, 1H NMR (360MHz, CDCl3) # 1.52 (3H, t, J=7.2Hz, CH3), 4.43 (2H, q, J=7.3Hz, CH2), 5.85 (2H, s, CH2), 7.29 (1H, d, J=1.7Hz, Ar-H), 7.83 (1H, t, J=7.3Hz, Ar-H), 7.95-8.01 (2H, M, 2 of Ar-H), 8.21 (1H, d, J=8.1Hz, Ar-H), 8.70 (1H, d, J=1.7Hz, Ar-H), 8.76 (1H, d, J=8.1Hz, Ar-H); MS (ES+) m/e 363 [MH]+.

EXAMPLE 113 3-(3-Isoxazolyl)-6-(2-propyl-1,2,4-triazol-3-yl)methyloxy-1, 2,4-triazolo[3,4- alphthalazine The title-compound was prepared from 6-chloro- 3 - (isoxazol- 3-yl)- 1,2,4-triazolo[3,4-a]phthalazine (described in Example 34 part b) and 2-propyl-3-hydroxymethyl- 1,2, 4-triazole prepared as described in WO-A- 9804559 using the procedure given for Example 71, lH NMR (360MHz, CDCl3) # 0.95 (3H, t, J=7.4Hz, Ar-H), 1.91-2.01 (2H, m, CH2), 4.34 (2H, t, J=7.0Hz, CH2), 5.85 (2H, s, CH2), 7.28 (1H, d, J=1.7Hz, Ar-H), 7.83 (1H, t, J=8.3Hz, Ar-H), 7.96-8.01 (2H, m, 2 of Ar-H), 8.21 (1H, d, J=7.9Hz, Ar-H), 8.62 (1H, s, Ar-H), 8.70 (1H, d, J=7.1Hz, Ar-H); MS (ES+) m/e 377 [MH]+; Anal. Found. C, 57.12; H, 3.87; N, 29.49. C18H16N8O2, 0.05CH2Cl2 requires C, 56.96; H, 4.26; N, 29.44%.

EXAMPLE 114 3-(3-Isoxazolyl)-6-(1-propyl-1,2,4-triazol-3-yl)methyloxy-1, 2,4-triazolo[3,4- alphthalazine The title-compound was prepared from 6-chloro- 3-(isoxazol- 3 -yl)- 1,2,4-triazolo[3,4-a]phthalazine (described in Example 34 part b) and 1-propyl-3-hydroxymethyl- 1,2, 4-triazole prepared as described in WO-A- 9804559 using the procedure given for Example 71, lH NMR (360MHz, CDCl3) # 0.95 (3H, t, J=7.4Hz, CH3), 1.89-1.99 (2H, m, CH2), 4.15 (2H, t, J=7.0Hz, CH2), 5.73 (2H, s, CH2), 7.40 (1H, d, J=1.7Hz, Ar-H), 7.80 (1H, t, J=7.2Hz, Ar-H), 7.96 (1H, t, J=6.9Hz, Ar-H), 8.09 (1H, s, Ar-H), 8.28 (1H,

d, J=7.9Hz, Ar-H), 8.70 (1H, s, Ar-H), 8.74 (1H, d, J=7.7Hz, Ar-H); MS (ES+) m/e 377 [MH]+.

EXAMPLE 115 6-(1-Benzylimidazol-2-yl)methyloxy-3-(3-isoxazolyl)-1,2,4-tr iazolo[3,4- a]phthalazine The title-compound was prepared from Intermediate 5 and 1-benzyl- 2-(hydroxymethyl)imidazole in a similar manner to Example 98, mp 197.5- 198.5°C; 'H NMR (250MHz, CDC13) 6 5.39 (2H, s, CH2), 5.78 (2H, s, CH2), 6.92-7.19 (7H, m, 7 ofArH), 7.31 (1H, d, J=1.7Hz, ArH), 7.67 (1H, m, ArH), 7.84 (1H, d, J=7.9Hz, ArH), 7.91 (1H, m, ArH), 8.63 (1H, d, J=10.0Hz, ArH), 8.65 (1H, d, J=1.7Hz, ArH); MS (ES+) m/e 424 [MH]+.

EXAMPLE 116 3-(5-Methoxymethylisoxazol-3-yl)-6-(1-methyl-1,2,4-triazol-3 -yl)methyloxy- 1,2,4-triazolo[3,4-a]phthalazine a) 3-(5-Methoxymethylisoxazol-3-yl)-6-(2,2,2-trifluoroethyloxy) -1,2,4- triazolor3,4-alphthalazine A solution of triethylamine (1.0g, 10.2mmol) in dichloromethane (50ml) was added dropwise to a suspension of Intermediate 4 (1g, 2.9mmol) and methyl propargyl ether (0.812g, 11.6mmol) in dichloromethane (50ml). After lh, the solvent was evaporated in vacuo and the residue dissolved in ethyl acetate, washed with water, dried (MgSO4) and evaporated in vacuo. The crude product was purified by chromatography on silica gel, eluting with 10-40% ethyl acetate/dichloromethane (gradient elution) followed by recrystallisation from ethyl acetate to give the title-compound (230mg, 21%), lH NMR (250MHz, CDCl3) # 3.52 (3H, s, CH3), 4.70 (2H, s, CH20), 5.03 (2H, q, J=8.1Hz, CH2CF3), 7.11 (1H, s, Ar-H), 7.90 (1H, m, ArH), 8.04 (1H, m, ArH), 8.28 (1H, d, J=7.9Hz, ArH), 8.74 (1H, d, J=7.5Hz, ArH); MS (ES+) m/e 380 [MH]+.

b) 3-(5-Methoxymethylisoxazol-3-yl)-6-(1-methyl-1,2,4-triazol-3 - yl)methyloxy-1,2,4-triazolo[3,4-a]phthalazine The title-compound was prepared from the preceding phthalazine and 1-methyl-1,2,4-triazole-3-methanol (prepared using the conditions of Itoh and Okongi, EP-A-421210) in a similar manner to Example 98, mp <BR> <BR> <BR> <BR> 235.5-236.5°C; ;'H NMR (360MHz, CDCl3) # 3.51 (3H, s, CH3), 3.97 (3H, s, CH3), 4.71 (2H, s, CH2), 5.72 (2H, s, CH2), 7.29 (1H, s, ArH), 7.80 (1H, m, ArH), 7.96 (1H, m, ArH), 8.08 (1H, s, ArH), 8.29 (1H, d, J=7.7Hz, ArH), 8.71 (1H, d, J=7.2Hz, ArH); MS (ES+) m/e 393 [MH]+; Anal. Found. C, 55.47; H, 4.01; N, 28.30. C18H16N8O3 requires C, 55.10; H, 4.11; N, 28.56%.

EXAMPLE 117 3-(5-Methoxymethylisoxazol-3-yl)-6-(2-methyl-1,2,4-triazol-3 -yl)methyloxy- 1,2,4-triazolo[3,4-a]phthalazine The title-compound was prepared from the product of Example 116 part a and 1-methyl-1,2,4-triazole-5-methanol (prepared using the conditions of Itoh and Okongi, EP-A-421210) in a similar manner to Example 98, mp 206-207.5°C; 1H NMR (360MHz, CDCl3) 6 3.53 (3H, s, CH3), 4.12 (3H, s, CH3), 4.73 (2H, s, CH2), 5.87 (2H, s, CH2), 7.20 (1H, s, ArH), 7.42 (1H, s, ArH), 7.93 (1H, m, ArH), 8.06 (1H, m, ArH), 8.30 (1H, d, J=7.7Hz, ArH), 8.70 (1H, d, J=7.2Hz, ArH); MS (ES+) m/e 393 [MH]+.

EXAMPLE 118 3-(5-Methoxyisoxazol-3-yl)-6-(1-methylimidazol-4-yl)methylox y-1,2,4- triazolo[3,4-a]phthalazine <BR> <BR> <BR> <BR> a) 3-(5-Methoxvisoxazol-3-vl)-6-(4-toluenesulphonYlOxY)-1, 2, 4-triazolo [3,4- alphthalazine Sodium methoxide (165mg, 0.3mmol) was added to a stirred suspension of 3-(5-chloroisoxazol-3-yl)-6-hydroxy- 1,2,4-triazolo[3,4- a]phthalazine (400mg, 0.14mmol) (prepared from Intermediate 7 using the procedure described in Example 15 part b) in N,N-dimethylformamide

(20ml) at 0°C under nitrogen. The mixture was stirred at 0°C for 3h then water was added (5ml) and the solvents evaporated in vacuo. The residue was taken up in water and acidified to pH 2 using 2M hydrochloric acid.

The resulting precipitate was filtered off, washed with hexane and azeotroped with ethanol to give crude 6-hydroxy-3(5-methoxyisoxazol-3- yl)-1,2,4-triazolo [3,4-a]phthalazine, MS (ES+) 284 [MH] +. The title- compound was prepared from this material using the procedure described in Example 103 part a, lH NMR (250MHz, CDCl3) 6 2.49 (3H, s, CH3), 4.15 (3H, s, CH3), 6.10 (1H, s, Ar-H), 7.45 (2H, d, J=8.5Hz, Ar-H), 7.92 (1H, m, Ar-H), 8.06 (1H, m, Ar-H), 8.26-8.32 (3H, m, 3 of Ar-H), 8.64 (1H, d, Ar-H); MS (ES+) 438 [MH]+. b) 3-(5-Methoxyisoxazol-3-yl)-6-(1-methylimidazol-4-yl)methylox y-1,2,4- triazolo[3,4-a]phthalazine The title-compound was prepared from the preceding compound and 4-hydroxymethyl-1-methylimidazole using the conditions described for Example 98, lH NMR (360MHz, CDCl3) # 3.68 (3H, s, CH3), 4.14 (3H, s, CH3), 5.61 (2H, s, CH2), 6.18 (1H, s, Ar-H), 7.41 (1H, s, Ar-H), 7.60 (1H, s, Ar-H), 7.77 (1H, m, Ar-H), 7.91 (1H, m, Ar-H), 8.26 (1H, d, J=8.5Hz, Ar-H), 8.64 (1H, d, J=8.5Hz, Ar-H); MS (ES+) 378 [MH]+; Anal. Found. C, 55.86; H, 3.81; N, 24.93. C18H15N7O3. 0.15 CH2Cl2 requires C, 55.88; H, 3.95; N, 25.13%.

EXAMPLE 119 3-(5-Methoxyisoxazol-3-yl)-6-(1-methyl-1,2,4-triazol-3-yl)me thyloxy-1,2,4- triazolo[3,4-a]phthalazine The title-compound was prepared from 3-(5 -methoxyisoxazol- 3-yl)-6- (4-toluene sulphonyloxy)- 1,2, 4-triazolo [3,4-a]phthalazine (prepared as described in Example 118 part a) and 3-hydroxymethyl-1-methyl-1,2,4- triazole (prepared using the conditions of Itoh and Okongi, EP-A-421210) using the conditions given for in Example 98, lH NMR (360MHz, CD Cl3) 6 3.96 (3H, s, CH3), 4.15 (3H, s, CH3), 5.72 (2H, s, CH2), 6.30 (1H, s, Ar-H),

7.79 (1H, m, Ar-H), 7.95 (1H, m, Ar-H), 8.07 (1H, s, Ar-H), 8.28 (1H, d, J=8.4Hz, Ar-H), 8.68 (1H, d, J=8.4Hz, Ar-H); MS (ES+) m/e 379 [MH]+; <BR> <BR> <BR> <BR> <BR> <BR> Anal. Found, C, 53.97; H, 3.73; N, 29.62. C17H14N8O3 requires C, 54.04; H,<BR> 3.48; N, 29.32%.

EXAMPLE 120 3-(3-Methylisoxazol-5-yl)-6-(2-pyridyl)methyloxy-1,2,4-triaz olo[3,4- alphthalazine a) 6-Chloro-3-(3-(3-methylisoxazol-5-yl)-1,2,4-triazolo[3,4-a]p hthalazine The title-compound was prepared from 3-methyl-5-isoxazole carboxylic acid (Eur. J. Med. Chem., 1992, 27, 581) using the procedure described for Intermediate 1, step c, 1H NMR (250MHz, CD Cl3) 6 2.50 (3H, s, CH3), 7.22 (1H, s, Ar-H), 8.00 (1H, m, Ar-H). 8.10 (1H, m, Ar-H), 8.36 (1H, d, J=8.2Hz, Ar-H), 8.84 (1H, m, Ar-H); MS (ES+) m/e 286 [MH]+. b) 3-(3-Methylisoxazol-5-yl)-6-(2-pyridyl)methyloxy-1,2,4-triaz olo[3,4- alphthalazine The title-compound was prepared from the preceding product and 2- pyridylcarbinol using the procedure given for Example 1, lH NMR (360MHz, CDCl3/d6-DMSO) 6 2.48 (3H, s, CH3), 5.78 (2H, s, CH2), 7.05 (1H, s, Ar-H), 7.34 (1H, m, Ar-H), 7.65 (1H, d, J=7.8Hz, Ar-H), 7.79-7.90 (2H, m, 2 of Ar-H), 8.01 (1H, m, Ar-H), 8.36 (1H, d, J=7.9Hz, Ar-H), 8.68- 8.72 (2H, m, 2 of Ar-H); MS (ES+) m/e 359 [MH]+; Anal. Found. C, 63.04; H, 3.63; N, 22.89. C19H14N6O2. 0.25H2O requires C, 62.89; H, 4.03; N, 23.16%.

EXAMPLE 121 3-(3-Methylisoxazol-5-yl)-6-(6-methylpyridin-2-yl)methyloxy- 1,2,4- triazolo [3, 4-alphthalazine The title-compound was prepared from the product of Example 120, step a, and 6-methyl-2-pyridylcarbinol using the procedure given for Example 1, lH NMR (360MHz, CDCl3) 6 2.48 (3H, s, CH3), 2.64 (3H, s,

CH3), 5.74 (2H, s, CH2), 7.07 (1H, s, Ar-H), 7.18 (1H, d, J=7.7Hz, Ar-H), 7.44 (1H, d, J=7.6Hz, Ar-H), 7.69 (1H, t, J=7.7Hz, Ar-H), 7.85 (1H, m, Ar- <BR> <BR> <BR> H), 7.99 (1H, m, Ar-H), 8.35 (1H, d, J=8.6Hz, Ar-H), 8.71 (1H, d, Ar-H); MS (ES+) m/e 373 [MH]+.

EXAMPLE 122 3-(3-Methylisoxazol-5-yl)-6-(pyrazin-2-yl)methyloxy-1,2,4-tr iazolo[3,4- al phthalazine The title-compound was prepared from 6-hydroxy-3-(3- methylisoxazol-5-yl)-1,2,4-triazolo[3,4-a]phthalazine (generated from the product of Example 120 part a using the conditions described for the preparation of Intermediate 2) and 2-chloromethylpyrazine (prepared as described in Example 15 part a) using the procedure described in Example 15 part b. lH NMR (360MHz, CD Cl3) 6 2.48 (3H, s, CH3), 5.83 (2H, s, CH2), 7.03 (1H, s, Ar-H), 7.87 (1H, m, Ar-H), 8.01 (1H, m, Ar-H), 8.32 (1H, d, J=7.8Hz, Ar-H), 8.62-8.68 (2H, m, 2 of Ar-H), 8.72 (1H, d, J=7.8Hz, Ar-H), 8.99 (1H, s, Ar-H); MS (ES+) m/e 360 [MH]+; Anal. Found C, 60.24; H, 3.44; N, 27.03. C18H13N7O2 requires C, 60.16; H, 3.63; N, 27.28%.

EXAMPLE 123 3-(3-Methylisoxazol-5-yl)-6-(2-methyl-1,2,4-triazol-3-yl)met hyloxy-1,2,4- triazolo [3,4- phthalazine The title-compound was prepared from the product of Example 120 part a and 2-methyl-1,2,4-triazole-3-methanol (prepared using the conditions of Itoh and Okongi, EP-A-42120) following the procedure given for Example 98, 1H NMR (400MHz, CDCl3) 6 2.43 (3H, s, CH3), 4.16 (3H, s, CH3), 5.82 (2H, s, CH2), 7.07 (1H, s, Ar-H), 7.84 (1H, m, Ar-H), 7.95-8.04 (2H, m, 2 of Ar-H), 8.21 (1H, d, J=8.0Hz, Ar-H), 8.62 (1H, d, J=8.0Hz, Ar- H); MS(ES+) m/e 363 [MH]+; Anal. Found. C, 56.12; H, 3.90; N, 30.74.

C17H14N8O2 requires C, 56.35; H, 3.89; N, 30.92%.

EXAMPLE 124 3-(3-Methylisoxazol-5-yl)-6-(1-methyl-1,2,4-triazol-3-yl)met hyloxy-1,2,4- triazolo[3,4-a]phthalazine The title-compound was prepared from the product of Example 120 part a and 3-hydroxymethyl-1-methyl-1, 1,2, 4-triazole (prepared using the conditions of Itoh and Okongi, EP-A-421210) following the conditions described for Example 71, mp 270-271.5°C; lH NMR (360MHz, CDCl3) 6 2.50 (3H, s, CH3), 3.97 (3H, s, CH3), 5.73 (2H, s, CH2), 7.31 (1H, s, Ar-H), 7.82 (1H, m, Ar-H), 7.97 (1H, m, Ar-H), 8.09 (1H, s, Ar-H), 8.31 (1H, d, J=8.6Hz, Ar-H), 8.70 (1H, d, J=8.6Hz, Ar-H); MS (ES+) m/e 363 [MH]+; Anal. Found. C, 55.92; H, 3.63; N, 30.16. C17H14N8O2, 0.06CH2Cl2 requires C, 55.77; H, 3.87, N, 30.49%.

EXAMPLE 125 3-(3-Ethoxyisoxazol-5-yl)-6-(1-methyl-1,2,4-triazol-3-yl)met hyloxy-1,2,4- triazolo [3,4-alththalazine a) Methvl (3 -hydroxy)isoxazole-5-carboxylate To a solution of N-hydroxyurea (3.80g, 0.05mol) and diazabicyclo[5.4.0]undec-7-ene (8.37g, 0.055mol) in methanol (50ml) at 0°C under nitrogen was added dimethylacetylene dicarboxylate (7. lOg, 0.05mol). The reaction was stirred at 0°C for 1h then at room temperature for 12h. The solvent was evaporated in vacuo and the residue taken up into water (20ml) and acidified to pH 1 with concentrated hydrochloric acid. The mixture was extracted with diethyl ether (3x25ml), dried (Na2SO4) and evaporated in vacuo. The resulting solid was recrystallised from chloroform to give the title-ester (2.20g, 31%), 1H NMR (250MHz, CDCl3) # 3.97 (3H, s, CH3), 6.61 (1H, s, Ar-H). b) Methyl (3-ethoxv)isoxazole-5-carboxvlate To a stirred solution of the preceding ester (2.20g, 0.015mol) in N,N- dimethylformamide (50ml) at 0°C under nitrogen was added sodium hydride (0.74g of a 60% dispersion in oil, 0.018mol). After 0.5h,

iodoethane (2.4ml, 0.03mol) was added dropwise and the reaction mixture allowed to warm to room temperature and stirred for 24h. The solvent was evaporated in vacuo and the residue dissolved in ethyl acetate (100ml) and washed with water (3x75ml). The organic layer was dried (MgSO4) evaporated in vacuo and the crude product purified by chromatography on silica gel, eluting with ethyl acetate/hexane (2:3), to give the title- compound (2.20g, 84%), lH NMR (250MHz, CDCl3) # 1.43 (3H, t, J=7.0Hz, CH3), 3.94 (3H, s, CH3), 4.33 (2H, q, J=7.1Hz, CH2), 6.52 (1H, d, J=2.3Hz, Ar-H). c) 3-Ethoxyisoxazole-5-carboxylic acid To a solution of the preceding ester (2.20g, 0.013mol) in methanol (10ml) at room temperature was added a solution of sodium hydroxide (2.06g, 0.051mol) in water (15ml), The mixture was stirred for lh then cooled to 0°C and acidified to pH1 with concentrated hydrochloric acid.

The resulting white solid was filtered off to give the title-acid (1.5g, 75%), 1H NMR (250MHz, CDCl3) 6 1.44 (3H, t, J=4.9Hz, CH3), 4.38 (2H, q, J=4.9Hz, CH2), 6.63 (1H, s, Ar-H), 6.74 (1H, br s, OH). d) 6-Chloro-3-(3-ethoxyisoxazol-5-yl)-1,2,4-triazolo[3,4-a]phth alazine The title-compound was prepared from 1-chloro-4- hydrazinophthalazine and the preceding acid in a similar manner to that described for Intermediate 1 part c, 1H NMR (360MHz, CD Cl3) 6 1.50 (3H, t, J=7.1Hz, CH3), 4.43 (2H, q, J=7.1Hz, CH2), 6.97 (1H, s, Ar-H), 7.96 (1H, t, J=8.3Hz, Ar-H), 8.09 (1H, t, J=8.3Hz, Ar-H), 8.34 (1H, d, J=7.6Hz, Ar- H), 8.81 (1H, d, J=7.6Hz, Ar-H). e) 3-(3-Ethoxyisoxazol-5-yl)-6-(1-methyl-1,2,4-triazol-3-yl)met hyloxy-1,2,4- triazolo[3,4-a]phthalazine The title-compound was prepared from the preceding phthalazine and 1-methyl-1,2,4-triazole-3-methanol (prepared using the conditions of Itoh and Okongi, EP-A-421210) following the procedure given in Example 71, 1H NMR (360MHz, CDCl3) 5 1.49 (3H, t, J=7.1Hz, CH3), 3.97 (3H, s, CH3), 4.46 (2H, q, J=7.1Hz, CH2), 5.70 (2H, s, CH2), 7.10 (1H, s, Ar-H),

7.81 (1H, t, J=8.4Hz, Ar-H), 7.96 (1H, t, J=8.3Hz; Ar-H), 8.08 (1H, s, Ar- H), 8.30 (1H, d, J=8.1Hz, Ar-H), 8.70 (1H, d, J=8.1Hz, Ar-H); MS (ES+) m/e 393 [MH]+.

EXAMPLE 126 6-(2-Methyl-1,2,4-triazol-3-yl)methyloxy-3-(pyrazin-2-yl)-1, 2,4-triazolo[3,4- alphthalazine a) 6-Chloro-3-(pyrazin-2-yl)-1,2,4-triazolo[3,4-a]phthalazine The title-compound was prepared from 1-chloro-4- hydrazinophthalazine and pyrazine-2-carboxylic acid as described for Intermediate 1 part c, lH NMR (250MHz, CDCl3) 6 7.99 (1H, t, J=7.2Hz, Ar-H), 8.09 (1H, t, J=8.2Hz, Ar-H), 8.33 (1H, d, J=6.8Hz, Ar-H), 8.80 (1H, m, Ar-H), 8.82-8.88 (2H, m, 2 of Ar-H), 9.67 (1H, d, J=1.SHz, Ar-H). b) 6-(2-Methyl-1,2,4-triazol-3-yl)methyloxy-3-(pyrazin-2-yl)-1, 2,4- triazolo[3,4-a]phthalazine The title-compound was prepared from the preceding phthalazine and 2-methyl- 1,2,4-triazole-3-methanol (prepared using the conditions of Itoh and Okongi, EP-A-421210) following the procedure given for Example 98, 1H NMR (360MHz, CDC13) 6 4.06 (3H, s, CH3), 5.97 (2H, s, CH2), 7.83 (1H, t, J=7.5Hz, Ar-H), 8.00-8.02 (2H, m, 2 of Ar-H), 8.19 (1H, d, J=8.5Hz, Ar-H), 8.77-8.81 (2H, m, 2 of Ar-H), 8.82 (1H, s, Ar-H), 9.65 (1H, s, Ar-H); MS (ES+) m/e 360[MH]+.

EXAMPLE 127 3-(Pyrazin-2-yl)-6-(pyrid-2-yl)methyloxy-1,2,4-triazolo[3,4- a]phthalazine The title-compound was prepared from 6-chloro-3-(pyrazin-2-yl)- 1,2, 4-triazolo [3,4- a]phthalazine and 2-pyridylcarbinol using the procedure given for Example 98, 1H NMR (360MHz, CD Cl3) 6 5.77 (2H, s, CH2), 7.40 (1H, t, J=6.6Hz, Ar-H), 7.71 (1H, d, J=7.8Hz, Ar-H), 7.95-8.00 (2H, m, 2 of Ar-H), 8.08 (1H, t, J=7.6Hz, Ar-H), 8.40 (1H, d, J=8.0Hz, Ar-H), 8.70 (2H,

m, 2 of Ar-H), 8.78 (1H, m, Ar-H), 8.88 (1H, s, Ar-H), 9.58 (1H, s, Ar-1H); MS (ES+) m/e 356 [MH]+.

EXAMPLE 128 3-(5-Methyl-1,2,4-oxadiazol-3-yl)-6-(1-methyl-1,2,4-triazol- 3-yl)methyloxy- 1,2,4-triazolo[3,4-a]phthalazine a) 3-Carboxamidoxime-6-(2,2,24-trifluoroethyloxy)- 1,2,4-triazolo F3,4- alphthalazine Intermediate 4 (690mg, 2 mmol) was suspended in ethanol (10ml) and concentrated ammonium hydroxide (10ml) was added. The reaction was stirred for 0.5h and then diluted with ethanol and evaporated. The product was washed successively with water, ethanol and ether and dried to yield the title-product (0.6g, 92%); lH NMR (250MHz, d6-DMSO) 6 5.23 (2H, q, J=8.7Hz), 6.10 (2H, br s), 7.98 (1H, t, J=7.7Hz), 8.12 (1H, t, J=7.7Hz), 8.18 (1H, d, J=7.7Hz), 8.56 (1H, d, J=7.7Hz), 10.25 (1H, s); MS (ES+) m/e 327 [MH]+. b)3-(5-Methyl-1,2,4-oxadiazol-3-yl)-6-(2,2,2-trifluoroethylo xy)-1,2,4- triazolo[3,4-a]phthalazine The preceding amide oxime (0.6g, 1.8mmol) in acetic anhydride (10ml) was heated at reflux for 16h. The solvent was removed and the residue was azeotroped with xylene. The residue was taken up in dichloromethane, washed with water, dried (MgSO4) and evaporated. The residue was purified by column chromatography on silica gel, eluting with ethyl acetate/dichloromethane, to yield the title-product (0.31g, 49%), lH NMR (250MHz, CDCl3)# 2.79 (3H, s), 5.00 (2H, q, J=8.7Hz), 7;91 (1H, t, J=7.7Hz), 8.08 (1H, t, J=7.7Hz), 8.29 (1H, d, J=7.7Hz), 8.78 (1H, d, J=7.7Hz); MS (ES+) 351 [MH]+. c) c-(5-Methyl-12,4-oxadiazol-3-yl)-6-(1-methyl-1,2,4-triazol-3 - yl)methyloxy-1,2,4-triazolo[3,4]a]phthalazine The title-compound was prepared from the preceding phthalazine and 1-methyl-1,2,4-triazole-3-methanol (prepared using the conditions of Itoh and Okongi, EP-A-421210) ij a similar manner to Example 98, 1H<BR> <BR> <BR> NMR (250MHz, CDCl3) # 2.78 (3H, s, CH3) 3.99 (3H, s, CH3), 5.74 (2H, s,<BR> <BR> <BR> CH2), 7.81 (1H, m, Ar-H), 7.97 (1H, m, Ar-H), 8.10 (1H, s, Ar-H), 8.28 (1H, d, J=7.7Hz, Ar-H), 8.74 (1H, d, J=7.5Hz, Ar-H); MS (ES+) m/e 364 [MH]+.