The present invention relates to compounds according to the general formula (1), with the definitions of the substituents A and Ar given below in the text, as well as their physiologically acceptable salts, methods for producing these compounds and their use as pharmaceuticals.

These compounds are kinase inhibitors, in particular inhibitors of the kinase CDK2 (cyclin-dependent kinase 2) It is known from literature that in the case of neoplastic diseases such as cancer, there is a connection between the therapy of said diseases and the inhibition of CDK2. There are many compounds available, which can be employed as inhibitors of CDK2 and/or other cyclin-dependent kinases such as CDK4 or CDK6 (M. H.

Lee et al., Cancer and Metastasis review 22 (2003), 435-449; A. Huwe et al., Angew. Chem. Int. Ed. 42 (2003), 2122-2138; WO 03/028721).

Pyridazinone derivatives are well known pharmaceutical, but it has not been reported so far that pyridazinone derivatives can be employed for the inhibition of CDK2. Pyridazinone derivatives described in literature differ from those of the present invention due to a different substitution pattern and (partially) different indications.

WO 03/059891 discloses pyridazinone derivatives that are useful for treating diseases and conditions caused or exacerbated by unregulated p38 MAP Kinase activity and/or TNF activity. The compounds described therein can be used, for example, for the treatment of inflammatory conditions, diabetes, Alzheimer's disease or cancer. They differ from the compounds of the present invention in the

substitution of the pyridazinone cycle, since the nitrogen at position 2 of the cycle is mostly substituted with alky, aryl or heteroaryl and at position 4 of the cycle there is no amido group defined as substituent (equals substituent A of the compounds of the present invention).

The documents EP-A 075 436, US 4,734, 415 and US 4,353, 905 describe pyridazinone derivatives as antihypertensive agents and as agents which increase cardiac contractibility. These pyridazinone derivatives have a phenyl residue at position 6 of the pyridazinone cycle, said phenyl residue is additionally substituted with a heterocycle containing at least one nitrogen atom. Whereas the pyridazinone derivatives described in the documents EP-A 075 436 and US 4,353, 905 do not have a substituent at position 4 of the pyridazinone cycle, those disclosed in US 4,734, 415 may have an amido group substituted with lower alkyl at this position. Compounds as such, explicitly disclosed by US 4,743, 415, are not a subject of the present invention.

Since neoplastic diseases such as cancer are a very serious risk for the health of humans and other mammals, there is a significant demand for new pharmaceuticals having a beneficial therapeutic profile for the treatment of such diseases. Thus, there exists a strong need for providing further compounds having an inhibitory effect for CDK2. The object of the present invention is to provide compounds showing this ability.

This object is attained by pyridazinone derivatives according to the below- mentioned formula (I) wherein A represents A1 or A2

R is unsubstituted or at least monosubstituted C1-C10-alkyl, aryl, aryl-(C1-C10- alkyl)-, heteroaryl, heteroaryl-(C1-C10-alkyl)-, heterocyclyl, heterocyclyl-(C1- C10-alkyl)-, C3-C10-cycloalkyl, polycycloalkyl, C2-C10-alkenyl or C2-C10- alkinyl, where the substituents are selected from halogen, -CN, C1-C10-alkyl, -NO2, - OR1, -C (O) OR1,-O-C (O) R1,-NR1 R2,-NHC (O) R1,-C (O) NR1 R2,-SR1,- S (O) R1,-S02R1,-NHS02R1,-S02NR1 R2,-C (S) NR1 R2,-NHC (S) R1, -O-SO2R1, -SO2-O-R1, oxo, -C (O) R1,-C (NH) NH2, heterocyclyl, C3-C10- cycloalkyl, aryl-(C1-C6-alkyl)-, aryl, heteroaryl, trifluoromethyl, trifluoromethylsulfanyl and trifluoromethoxy, and aryl, heterocyclyl and heteroaryl may in turn be at least monosubstituted with C,-C6-alkyl, C,-C6-alkoxy, halogen, trifluoromethyl, trifluoromethoxy or OH; Ar is unsubstituted or at least monosubstituted aryl or heteroaryl ; where the substituents are selected from halogen, -CN, NO2, C1-C10-alkyl, OR1, -C(O)OR1, -O-C(O)R1, -NR1R2, -NHC(O)R1, -C(O)NR1R2, -NHC (S) R1,-C (S) NR1 R2,-SR1,-S (O) R1,-S02R1,-NHS02R1, -SO2NR1R2, -O-SO2R1, -SO2-O-R1, aryl, heteroaryl, aryl-(C1-C6-alkyl)-, formyl, trifluoromethyl and trifluoromethoxy, and aryl and heteroaryl may in turn be at least monosubstituted with Ci-Ce- alkyl, C1-C6-alkoxy, halogen, trifluoromethyl, trifluoromethoxy or OH; R1 and R2 are independently from each other hydrogen; unsubstituted or at least monosubstituted C1-C10-alkyl, C3-C10-cycloalkyl, aryl, aryl-(C1-C10-alkyl)-, C2-C10-alkenyl, C2-C10-alkinyl, heterocyclyl,

heterocyclyl- (C1-C1o-alkyl)- or heteroaryl, where the substituents are selected from halogen, C1-C6-alkyl, C1-C6-alkoxy, CN, NO2, NH2, (Ci-C6- alkyl) amino-, di (Ci-C6-alkyl) amino-, OH, COOH,-COO-(C1-C6-alkyl), -CONH2, formyl, trifluoromethyl and trifluoromethoxy ; heteroaryl is a 5 to 10-membered, aromatic, mono-or bicyclic heterocycle containing one or more heteroatoms selected from N, O und S; aryl is phenyl, indanyl, indenyl or naphthyl ; heterocyclyl is a 5 to 10-membered, aliphatic, mono-or bicyclic heterocycle containing one or more heteroatoms selected from N, O and S; with the proviso that A is not-C (O) NH (Ci-C6-alkyl), in case Ar is phenyl which is at least monosubstituted with heterocyclyl or heteroaryl containing nitrogen.

If in the compounds of formula (I), groups, fragments, residues or substituents such as, for example, aryl, heteroaryl, alkyl etc. , may be present several times, they all independently from each other have the meanings indicated and may hence, in each individual case, be identical with or different from each other. The following comments apply to (for example) aryl as well as to any other residue independently from its classification as aryl group, -substituent, -fragment or- residue. One example is the di (Ci-Cio-alkyl) amino group in which the alkyl substitutents may be identical or different (for instance 2 x ethyl or 1 x propyl and 1 x heptyl).

If in the above-mentioned definitions of compounds according to formula (I) a substituent, for example aryl, may be unsubstituted or at least mono-substituted with a group of further substituents, for example, C1-C6-alkyl, C1-C6-alkoxy, halogen etc. , it applies in such cases, where there is a poly-substitution of aryl, that the selection from the group of further substituents is independently from each other. Thus, all combinations of further substituents are comprised in the case of, for example, a double-substitution of aryl. Therefore, aryl may be substituted twice with ethyl, aryl may be mono-substituted with methyl or ethoxy, respectively, aryl may be mono-substituted with ethyl or fluoro, respectively, aryl may be substituted twice with methoxy, etc..

Alkyl, alkenyl and alkynyl residues may be linear or branched. This also applies when they are part of other groups, for example in alkoxy groups (Ci-Cio-alkyl-O-), alkoxycarbonyl groups or amino groups, or when they are substituted.

Examples for alkyl groups are: methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl. This comprises both the n-isomers of these residues and isopropyl, isobutyl, isopentyl, sec-butyl, tert-butyl, neopentyl, 3, 3-dimethylbutyl etc.. Furthermore, unless stated otherwise, the term alkyl here also includes unsubstituted alkyl residues as well as alkyl residues which are substituted by one or more, for example one, two, three or four, identical or different residues, for example aryl, heteroaryl, alkoxy or halogen. The substituents may be present in any desired position of the alkyl group.

Examples for cycloalkyl residues are: cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl. All cycloalkyl groups may be unsubstituted or optionally substituted by one or more further residues, as exemplified above in the case of the alkyl groups.

Examples for alkenyl and alkynyl groups are the vinyl residue, the 1-propenyl residue, the 2-propenyl residue (allyl residue), the 2-butenyl residue, the 2-methyl- 2-propenyl residue, the 3-methyl-2-butenyl residue, the ethynyl residue, the 2- propynyl residue (propargyl residue), the 2-butynyl residue or the 3-butynyl residue. The term alkenyl here also expressly includes cycloalkenyl residues and cycloalkenyl-alkyl-residues (alkyl substituted by cycloalkenyl) containing at least three carbon atoms. Examples for cycloalkenyl residues are cyclopentenyl, cyclohexenyl, cycloheptenyl and cyclooctenyl.

The alkenyl residues may have 1 to 3 conjugated or unconjugated double bonds in a straight or branched chain; the same applies to alkynyl residues in respect of triple bonds. The alkenyl and alkinyl residues may be unsubstituted or optionally substituted by one or more further residues, as exemplified above in the case of the alkyl groups.

Examples for polycycloalkyl residues are: adamantyl, quinuclidinyl, bornanyl, norbornanyl, bornenyl and norbornenyl.

If not stated otherwise, the above-mentioned aryl, heteroaryl and heterocyclic residues may be unsubstituted or may carry one or more, for example one, two, three or four of the substituents indicated in the above definition, which substituents may be in any desired position. In monosubstituted phenyl residues, for example, the substituent may be in the 2-position, the 3-position or the 4- position, in disubstituted phenyl residues the substituents may be in 2,3-position, 2,4-position, 2,5-position, 2,6-position, 3,4-position or 3, 5-position. In trisubstituted phenyl residues the substituents may be in 2,3, 4-position, 2,3, 5-position, 2,3, 6- position, 2,4, 5-position, 2,4, 6-position or 3,4, 5-position. In fourfold substituted phenyl residues, the substituents may be in the 2,3, 4,5-position, the 2,3, 4,6- position, or the 2,3, 5,6-position.

The above definitions as well as the following definitions relating to monovalent residues equally apply to the divalent residues phenylen, naphthylene and heteroarylene. Those divalent residues (fragments) may be attached to the adjacent groups by any ring carbon atom. In the case of a phenylen residue, these may be in 1,2-position (ortho-phenylene), 1,3-position (meta-phenylene) or 1,4-position (para-phenylene). In the case of 5-membered ring aromatics containing one heteroatom such as, for example, thiophene or furan, the two free bonds may be in 2,3-position, 2,4-position, 2,5-position or 3,4-position. A divalent residue derived from pyridine may be a 2,3-, 2,4-, 2,5-, 2,6-, 3, 4- or 3, 5-pyridinediyl residue. In the case of unsymmetrical divalent residues the present invention includes all positional isomers, i. e. , in the case of a 2, 3-pyridinediyl residue, for example, it includes the compound in which the one adjacent group is present in the 2-position and the other adjacent group is present in the 3-position as well as the compound in which the one adjacent group is present in the 3-position and the other adjacent group is present in the 2-position.

Unless stated otherwise, heteroaryl residues, heteroarylene residues, heterocyclyl residues, heterocyclylen residues and rings which are formed by two groups bonded to a nitrogen are preferably derived from completely saturated, partially saturated or completely unsaturated heterocycles (i. e. heterocycloalkanes, heterocycloalkenes, heteroaromatics), which contain one, two, three or four heteroatoms, which may be identical or different; more preferably they are derived from heterocycles which contain one, two, or three, in particular one or two, heteroatoms, which may be identical or different. Unless stated otherwise, the heterocycles may be monocyclic or polycyclic, for example monocyclic, bicyclic or

tricyclic. Preferably they are monocyclic or bicyclic. The rings preferably are 5- membered rings, 6-membered rings or 7-membered rings. Examples of monocyclic and bicyclic heterocyclic systems from which residues occuring in the compounds of the formula (I) may be derived, are pyrrole, furan, thiophene, imidazole, pyrazol, 1,2, 3-triazole, 1,2, 4-triazole, 1, 3-dioxole, 1, 3-oxazol oxazol), 1, 2-oxazol (= isoxazole), 1, 3-thiazole (= thiazole), 1, 2-thiazole (= isothiazole), tetrazol, pyridine, pyridazine, pyrimidine, pyrazine, pyran, thiopyran, 1,4-dioxine, 1,2-oxazine, 1,3-oxazine, 1,4-oxazine, 1,2-thiazine, 1,3-thiazine, 1,4- thiazine, 1,2, 3-triazine, 1,2, 4-triazine, 1,3, 5-triazine, 1,2, 4,5-tetrazine, azepine, 1,2- diazepine, 1,3-diazepine, 1,4-diazepine, 1,3-oxazepine, 1,3-thiazepine, indole, benzothiophene, benzofuran, benzothiazole, benzimidazole, benzodioxol, quinoline, isoquinoline, quinazoline, quinoxaline, phthalazine, thienothiophenes, 1,8-naphthyridine and other naphthyridines, pteridin, or phenothiazine, each of them in saturated form (perhydro form) or in partially unsaturated form (for example in the dihydro form or the tetrahydro form) or in maximally unsaturated form, in case the respective forms are known and stable. The term"aryl"and the term"heteroaryl"as used herein comprise bicyclic residues in which both cycles are aromatic as well as bicyclic residues in which only one cycle is aromatic.

Suitable aliphatic heterocycles include, for example, the saturated heterocycles pyrrolidine, piperidine, piperazine, imidazolidine, pyrazolidine, isothiazolidine, thiazolidine, isoxazolidine, oxazolidine, tetrahydrofuran, dioxolane, 2-oxo-azepane, morpholine and thiomorpholine as well as the partially unsaturated heterocycles isochromamyl, chromamyl, 1,2, 3, 4-tetrahydroisochinolyl and 1,2, 3,4- tetrahydrochinolyl. The degree of saturation of heterocyclic groups is indicated in their individual definitions.

Substituents which may be derived from these heterocycles may be attached via any suitable carbon atom. Residues derived from nitrogen heterocycles may carry a hydrogen atom or a substituent on a ring nitrogen atom, and examples include pyrrole, imidazole, pyrrolidine, morpholine, piperazine residues, etc. Those nitrogen heterocyclic residues may also be attached via a ring nitrogen atom, in particular if the respective heterocyclic residue is bonded to a carbon atom. For example, a thienyl residue may be present as 2-thienyl or 3-thienyl, a piperidinyl residue as 1-piperidinyl (= piperidino), 2-piperidinyl, 3-piperidinyl or 4-piperidinyl.

Suitable nitrogen heterocycles may also be present as N-oxides or as quaternary salts containing a counterion which is derived from a physiologically acceptable acid. Pyridyl residues, for example, may be present as pyridine-N-oxides.

Arylalkyl means an alkyl residue, which in turn is substituted by an aryl residue.

Heteroarylalkyl means an alkyl residue, which in turn is substituted by a heteroaryl residue. Heterocyclylalkyl means an alkyl residue, which in turn is substituted by a heterocyclyl residue. For the definitions and possible substitutions of alkyl, heteroaryl, heterocyclyl and aryl it is referred to the above-mentioned definitions.

Halogen is fluorine, chlorine, bromine or iod, preferably fluorine, chlorine or bromine, most preferably fluorine or chlorine.

The present invention includes all stereoisomeric forms of the compounds of the formula (I). Centers of asymmetry that are present in the compounds of formula (I) all independently of one another have S configuration or R configuration. The invention includes all possible enantiomers and diastereomers and mixtures of two or more stereoisomers, for example mixtures of enantiomers and/or diastereomers, in all ratios. Thus, compounds according to the present invention which may exist as enantiomers may be present in enantiomerically pure form, both as levorotatory and as dextrorotatory antipodes, in the form of racemates and in the form of mixtures of the two enantiomers in all ratios. In the case of a cis/trans isomerism the invention includes both the cis form and the trans form as well as mixtures of these forms in all ratios. All these forms are an object of the present invention. The preparation of individual stereoisomers may be carried out, if desired, by separation of a mixture by customary methods, for example by chromatography or crystallization, by the use of stereochemically uniform starting materials for the synthesis or by stereoselective synthesis. Optionally, a derivatization may be carried out before a separation of stereoisomers. The separation of a mixture of stereoisomers may be carried out at the stage of the compounds of the formula (I) or at the stage of an intermediate during the synthesis. The present invention also includes all tautomeric forms of the compounds of formula (I), in particular keto-enol tautomerism, i. e. the respective compounds may be present either in their keto form or in their enol form or in mixtures thereof in all ratios.

In case the compounds according to formula (I) contain one or more acidic or basic groups, the invention also comprises their corresponding physiologically or toxicologically acceptable salts.

Physiologically acceptable salts are particularly suitable for medical applications, due to their greater solubility in water compared with the starting or base compounds. Said salts must have a physiologically acceptable anion or cation. Suitable physiologically acceptable acid addition salts of the compounds of the invention are salts of inorganic acids such as hydrochloric acid, hydrobromic acid, phosphoric acid, metaphosphoric acid, nitric acid, sulfonic acid and sulfuric acid and also of organic acids such as, for example, acetic acid, theophyllinacetic acid, methylene-bis-b-oxynaphthoic acid, benzenesulfonic acid, benzoic acid, citric acid, ethanesulfonic acid, salicylic acid, fumaric acid, gluconic acid, glycolic acid, isethionic acid, lactic acid, lactobionic acid, maleic acid, malic acid, methane- sulfonic acid, succinic acid, p-toluenesulfonic acid, tartaric acid and trifluoroacetic acid. Suitable pharmaceutically acceptable basic salts are ammonium salts, alkali metal salts (such as sodium salts and potassium salts) and alkaline earth metal salts (such as magnesium salts and calcium salts).

Salts having a pharmaceutical unacceptable anion are likewise included within the scope of the present invention as useful intermediates for preparing or purify- ing pharmaceutical acceptable salts and/or for use in nontherapeutic applica- tions, for example in-vitro applications.

If the compounds of the formula (I) simultaneously contain acidic and basic groups in the molecule, the invention also includes, in addition to the salt forms mentioned, inner salts or betaines (zwitterions).

The respective salts according to the formula (I) may be obtained by customary methods which are known to the person skilled in the art like, for example by contacting these with an organic or inorganic acid or base in a solvent or dispersant, or by anion exchange or cation exchange with other salts.

The present invention furthermore includes all solvates of compounds of the formula (I), for example hydrates or adducts with alcohols, active metabolites of the compounds of the formula (I), and also derivatives, which contain physiologically tolerable and cleavable groups, for example esters or amides.

The term"physiologically functional derivative"used herein relates to any physio- logically acceptable derivative of an inventive compound of the formula 1, for example an ester which on administration to a mammal, for example humans, is

capable of forming (directly or indirectly) a compound of the formula I or an active metabolite thereof.

The physiologically functional derivatives also include prodrugs of the compounds of the invention. Such prodrugs may be metabolized in vivo to a compound of the invention. These prodrugs may or may not be active themselves and are also object of the present invention.

The compounds of the invention may also be present in various polymorphous forms, for example as amorphous and crystalline polymorphous forms. All polymorphous forms of the compounds of the invention are included within the scope of the invention and are another aspect of the invention.

Compounds of formula (I) are preferred, wherein A is A1 ; R is unsubstituted or at least monosubstituted Cl-Clo-alkyl, aryl, aryl- (Cl-Clo- alkyl)-, heteroaryl, heteroaryl-(C1-C10-alkyl)-, heterocyclyl, heterocyclyl-(C1- C10-alkyl)-, C3-C10-cycloalkyl, polycycloalkyl, C2-C10-alkenyl or C2-Cio- alkinyl, where the substituents are selected from halogen,-CN, C1-C10-alkyl, -NO2, -OR1, -C(O)OR1, -O-C(O)R1, -NR1R2, -NHC(O)R1, -C(O)NR1R2, -SR1, - S (O) R1,-S02R1,-NHS02R1,-S02NR1 R2,-C (S) NR1R2, -NHC (S) R1, -O-SO2R1, -SO2-O-R1, oxo, -C (O) R1,-C (NH) NH2, heterocyclyl, C3-C10- cycloalkyl, aryl- (C,-C6-alkyl)-, aryl, heteroaryl, trifluoromethyl, trifluoromethylsulfanyl and trifluoromethoxy, and aryl, heterocyclyl and heteroaryl may in turn be at least monosubstituted with C1-C6-alkyl, Ci-C6-alkoxy, halogen, trifluoromethyl, trifluoromethoxy or OH; R1 and R2 independently from each other hydrogen;

unsubstituted or at least monosubstituted C1-C10-alkyl, C3-C10-cycloalkyl, aryl, aryl-(C1-C10-alkyl)-, C2-C10-alkenyl, C2-C10-alkinyl, heterocyclyl, heterocyclyl-(C1-C10-alkyl)- or heteroaryl, where the substituents are selected from halogen, C1-C6-alkyl, C1-C6-alkoxy, CN, N02, NH2, (Ci-Ce- alkyl) amino-, di (C,-C6-alkyl) amino-, OH, COOH, -COO-(C1-C6-alkyl), -CONH2, formyl, trifluoromethyl and trifluoromethoxy ; heteroaryl is a 5 to 10-membered, aromatic, mono-or bicyclic heterocycle containing one or more heteroatoms selected from N, O and S; aryl is phenyl, indanyl, indenyl or naphthyl ; heterocyclyl is a 5 to 10-membered, aliphatic, mono-oder bicyclic heterocycle containing one or more heteroatoms selected from N, O and S; In another embodiment, compounds of formula (I) are preferred, wherein R is unsubstituted or at least monosubstituted C1-C10-alkyl, aryl, aryl-(C1-C10- alkyl)-, heterocyclyl, heterocyclyl-(C1-C10-alkyl)-, C3-C10-cycloalkyl, heteroaryl or heteroaryl- (Ci-Cio-alkyl)-, where the substituents are selected from halogen,-CN, C1-C10-alkyl, -NO2, - OR1, -C (O) OR1,-O-C (O) R1,-NR1 R2, -NHC (O) R1,-C (O) NR1 R2,-SR1,- S (O) R1,-S02R1,-NHS02R1,-S02NR1R2,-C (S) NR1R2, -NHC (S) R1, -O-SO2R1, -SO2-O-R1, oxo, -C (O) R1,-C (NH) NH2, heterocyclyl, C3-C10- cycloalkyl, aryl-(C1-C6-alkyl)-, aryl, heteroaryl, trifluoromethyl, trifluoromethylsulfanyl and trifluoromethoxy, and aryl, heterocyclyl and heteroaryl may in turn be at least monosubstituted with Ci-C6-alkyl, Ci-C6-alkoxy, halogen, trifluoromethyl, trifluoroethoxy or OH; R1 and R2 are independently from each other hydrogen;

unsubstituted or at least monosubstituted C1-C10-alkyl, C3-C10-cycloalkyl, aryl, aryl-(C1-C10-alkyl)-, C2-C10-alkenyl, C2-C10-alkinyl, heterocyclyl, heterocyclyl-(C1-C10-alkyl)-or heteroaryl, where the substituents are selected from halogen, C1-C6-alkyl, C1-C6-alkoxy, CN, N02, NH2, (Ci-Ce- alkyl) ami no-, di (C1-C6-alkyl) amino-, OH, COOH,-COO- (C,-C6-alkyl), -CONH2, formyl, trifluoromethyl and trifluoromethoxy ; heteroaryl is a 5 to 10-membered, aromatic, mono-or bicyclic heterocycle containing one or more heteroatoms selected from N, O and S; aryl is phenyl, indanyl, indenyl or naphthyl ; heterocyclyl is a 5 to 10-membered, aliphatic, mono-oder bicyclic heterocycle, containing one or more heteroatoms selected from N, O and S; In another embodiment, compounds of formula (I) are preferred, wherein Ar is unsubstituted or at least monosubstituted phenyl, pyridinyl, pyrimidinyl, pyrazolyl, thiophenyl, isoxazolyl, benzo [b] thiophenyl, benzodioxolyl or thiazolo [3,2-b] [1,2, 4]-tiazolyl, where the substituents are selected from halogen, -CN, NO2, C1-C10-alkyl, -OR1, -C(O)OR1, -O-C(O)R1, -NR1R2, -NHC(O)R1, -C(O)NR1R2, -NHC (S) R1,-C (S) NR1 R2,-SR1,-S (O) R1,-S02R1,-NHS02R1, -SO2NR1R2, -O-SO2R1, -SO2-O-R1, aryl, heteroaryl, aryl-(C1-C6-alkyl)-, formyl, trifluoromethyl and trifluoromethoxy, and aryl and heteroaryl may in turn be at least monosubstituted with Ci-Ce- alkyl, d-Ce-aikoxy, halogen, trifluoromethyl, trifluoromethoxy or OH; R1 and R2 are independently from each other hydrogen; unsubstituted or at least monosubstituted Ci-Cio-alkyl, C3-C, o-cycloalkyl, aryl, aryl-(C1-C10-alkyl)-, C2-C10-alkenyl, C2-C10-alkinyl, heterocyclyl, heterocyclyl-(C1-C10-alkyl)- or heteroaryl, where the substituents are

selected from halogen, C,-C6-alkyl, C,-C6-alkoxy, CN, N02, NH2, (C1-C6- alkyl) amino-, di (C1-C6-alkyl) amino-, OH, COOH,-COO-(C1-C6-alkyl), -CONH2, formyl, trifluoromethyl and trifluoromethoxy ; heteroaryl is a 5 to 10-membered aromatic, mono-or bicyclic heterocycle, containing one or more heteroatoms selected from N, O and S; aryl is phenyl, indanyl, indenyl or naphthyl ; heterocyclyl is a 5 to 10-membered aliphatic, mono-oder bicyclic heterocycle, containing one or more heteroatoms selected from N, O and S; Compounds of formula (I) are more preferred, wherein A is A1 ; R is unsubstituted or at least monosubstituted C1-C10-alkyl, aryl, aryl-(C1-C10- alkyl)-, heterocyclyl, heterocyclyl-(C1-C10-alkyl)-, C3-C10-cycloalkyl, heteroaryl or heteroaryl-(C1-C10-alkyl)-, where the substituents are selected from halogen, C1-C10-alkyl, -OR1, - C (O) OR1,-NR1 R2,-C (O) NR1 R2,-SR1,-S02R1,-S02NR1 R2, oxo, -C(O)R1, -C (NH) NH2, heterocyclyl, C3-C10-cycloalkyl, aryl- (Ci-C6-alkyl)-, aryl, trifluoromethyl and trifluoromethoxy, and aryl, heterocyclyl and heteroaryl may in turn be at least monosubtituted with C1-C6-alkyl, C1-C6-alkoxy, halogen, trifluoromethyl, trifluoromethoxy or OH; Ar is unsubstituted or at least monosubstituted phenyl, pyridinyl, pyrimidinyl, pyrazolyl, thiophenyl, isoxaloyl, benzo [b] thiophenyl, benzodioxolyl or thiazolo [3,2-b] [1,2, 4]-tiazolyl, where the substituents are selected from halogen, C1-C10-alkyl, -OR1, -C (O) OR1,-NR1 R2,-C (O) NR1 R2, aryl, heteroaryl, aryl-(C1-C6-alkyl)-, trifluoromethyl and Trifluoromethoxy,

and aryl and heteroaryl may in turn be at least monosubsituted with Cl-C6- alkyl, C1-C6-alkoxy, halogen, trifluoromethyl or OH; R1 und R2 are independently from each other hydrogen; unsubstituted or at least monosubstituted C1-C10-alkyl, C3-C10-cycloalkyl, aryl, aryl-(C1-C10-alkyl)-, heterocyclyl, heterocyclyl-(C1-C10-alkyl)- or heteroaryl, where the substituents are selected from halogen, C1-C6-alkyl, C1-C6-alkoxy, NH2, (Ci-C6-alkyl) amino-, di (C1-C6-alkyl) amino-, OH, trifluoromethyl and trifluoromethoxy ; heteroaryl is a 5 to 10-membered, aromatic, mono-or bicyclic heterocycle containing one or more heteroatoms selected from N, O und S; heteroaryl is preferably imidazolyl, thiophenyl, furanyl, isoxazolyl, pyridinyl, pyrimidinyl, 1,2, 3,4- tetrahydrochinolinyl, benzoimidazolyl, indolyl or benzodioxolyl ; aryl is phenyl, indanyl, indenyl or naphthyl ; aryl is preferably phenyl or naphthyl. heterocyclyl is a 5 to 10-membered, aliphatic, mono-or bicyclic heterocycle containing one or more heteroatoms selected from N, O und S; heterocyclyl is preferably 2-oxo-azepanyl, tetrahydrofuranyl, 1, 3-dioxolanyl, morpholinyl, piperazinyl or piperidinyl ; Compounds of formula (I) are even more preferred, wherein A is A1 ; R is unsubstituted or at least monosubstituted C1-C10-alkyl, aryl, aryl-(C1-C10- alkyl)-, heterocyclyl, heterocyclyl-(C1-C10-alkyl)-, C3-C10-cycloalkyl, heteroaryl or heteroaryl-(C1-C10-alkyl)-, where the substituents are selected from halogen, Ci-Cio-alkyl,-OR1, - C (O) OR1,-NR1 R2,-C (O) NR1 R2,-SR1,-S02R1,-S02NR1 R2, oxo, -C(O)R1, -C (NH) NH2, heterocyclyl, C3-C1o-cycloalkyl, aryl-(C1-C6-alkyl)-, aryl, trifluoromethyl and trifluoromethoxy,

and aryl, heterocyclyl and heteroaryl may in turn be at least monosubsituted with C1-C6-alkyl, C1-C6-alkoxy, halogen, trifluoromethyl, trifluoromethoxy or OH; Ar is unsubstituted or at least monosubstituted phenyl, pyridinyl or pyrimidinyl, where the substituents are selected from halogen, C1-C10-alkyl, -OR1, - C (O) OR1,-NR1 R2,-C (O) NR1 R2, aryl, heteroaryl, aryl- (Ci-C6-alkyl)-, trifluoromethyl and trifluoromethoxy, and aryl and heteroaryl may in turn be at least monosubsituted with C1-C6- alkyl, C1-C6-alkoxy, halogen, trifluoromethyl or OH; R1 und R2 are independently from each other hydrogen; unsubstituted or at least monosubstituted C1-C10-alkyl, C3-C10-cycloalkyl, aryl, aryl-(C1-C10-alkyl)-, heterocyclyl, heterocyclyl-(C1-C10-alkyl)- or heteroaryl, where the substituents are selected from halogen, C1-C6-alkyl, C1-C6-alkoxy, NH2, (Ci-C6-alkyl) amino-, di (Ci-C6-alkyl) amino-, OH, trifluoromethyl and trifluoromethoxy ; heteroaryl is a 5 to 10-membered, aromatic, mono-or bicyclic heterocycle containing one or more heteroatoms selected from N, O und S; heteroaryl is preferably imidazolyl, thiophenyl, furanyl, isoxazolyl, pyridinyl, pyrimidinyl, 1,2, 3,4- tetrahydrochinolinyl, benzoimidazolyl, indolyl or benzodioxolyl ; aryl is phenyl, indanyl, indenyl or naphthyl ; aryl is preferably phenyl or naphthyl. heterocyclyl is a 5 to 10-membered, aliphatic, mono-or bicyclic heterocycle containing one or more heteroatoms selected from N, O und S; heterocyclyl is preferably 2-oxo-azepanyl, tetrahydrofuranyl, 1, 3-dioxolanyl, morpholinyl, piperazinyl or piperidinyl ; Compounds of formula (I) are even much more preferred, wherein

A is A1 ; R is unsubstituted or at least monosubstituted aryl- (Ci-C6-alkyl)-, heteroaryl- (Ci-C6-alkyl)-or heterocyclyl- (Ci-C6-alkyl)-, where the substituents are selected from halogen, C1-C6-alkyl, -OH, -O-aryl, C1-C6-alkoxy, -O-(C1-C6-alkylen)-N(C1-C6-alkyl) 2, -C (O) OH, -C (O) 0- (Ci-Ce- alkyl),-NH2,-N (C1-C6-alkyl) 2, -NH (C1-C6-alkyl), -NH(C1-C10-cycloalkyl), -C(O) NH2, -C (O) NH-heteroaryl, -C(O)NH-(C1-C6-alkyl), -SO2(C1-C6-alkyl), - S02NH2,-C (O)-heterocyclyl,-C (NH) NH2, heterocyclyl, aryl-(C1-C6-alkyl)-, aryl, trifluoromethyl, and trifluoromethoxy, and aryl, heterocyclyl and heteroaryl may in turn be at least monosubstituted with C1-C3-alkyl, C1-C3-alkoxy, fluorine, chlorine, bromine, trifluoromethyl, trifluoromethoxy or OH; heteroaryl is imidazolyl, thiophenyl, furanyl, isoxazolyl, pyridinyl, pyrimidinyl, benzoimidazolyl, indolyl or benzodioxolyl ; aryl is phenyl or naphthyl ; hetrocyclyl is morpholinyl, piperazinyl or piperidinyl ; In another embodiment, compounds of formula (I) are even much more preferred, wherein A is A1 ; Ar is unsubstituted or at least monosubstituted phenyl, pyridin-4-yl or pyrimidin-4-yl, where the substituents are selected from halogen, C1-C6-alkyl, -OH, C1-C6- alkoxy,-C (O) OH, -C (O) O- (C,-C6-alkyl),-NH2,-N (Ci-C6-alkyl) 2, -NH (Ci-Ce- alkyl), -NH(C1-C10-cycloalkyl), -NH(heterocyclyl-(C1-C6-alkyl-)), -NH(aryl- (C1-C6-alkyl-)),-C (O) NH2, -C (O) NH-(C1-C6-alkyl), aryl, and heteroaryl,

and aryl, heterocyclyl and heteroaryl may in turn be at least monosubstituted with C1-C3-alkyl, C1-C3-alkoxy, fluorine, chlorine, bromine, trifluoromethyl, trifluoromethoxy or OH; heteroaryl is pyridinyl or pyrimidinyl ; aryl is phenyl or naphthyl ; hetrocyclyl is morpholinyl, piperazinyl or piperidinyl ; Compounds of formula (I) are particularly preferred, wherein A is A1 ; R is unsubstituted or at least monosubstituted benzyl, phenylethyl-, phenylpropyl-, piperazinylpropyl, pyridinylmethyl-, pyridinylethyl-or pyridinylpropyl-, where the substituents are selected from chlorine, bromine, fluorine, methyl, ethyl, propyl, methoxycarbonyl and carboxy; Ar is unsubstituted or at least monosubstituted pyridin-4-yl, pyrimidin-4-yl or phenyl, where the substituents are selected from methylamino-, ethylamino-, propylamino-, butylamino-, hydroxy, methoxy, ethoxy, (phenylethyl) amino-, benzylamino-and (morpholinylethyl) amino- ; Compounds of formula (I) are exceptionally preferred, which are selected from the group consisting of: 6- (2-butylamino-pyrimidin-4-yl)-3-oxo-2, 3-dihydro-pyridazine-4-car- boxylic acid (3-pyridin-3-yl-propyl)-amide, 6- (4-hydroxy-3-methoxy-phenyl)-3-oxo-2, 3-dihydro-pyridazine-4- carboxylic acid (3-pyridin-3-yl-propyl)-amide, 6- (4-hydroxy-phenyl)-3-oxo-2, 3-dihydro-pyridazine-4-carboxylic acid (3- pyridin-3-yl-propyl)-amide, 6-(2-ethylamino-pyrimidin-4-yl)-3-oxo-2, 3-dihydro-pyridazine-4- carboxylic acid 4-chloro-benzylamide, <BR> <BR> <BR> <BR> <BR> 6- (3-chloro-4-hydroxy-phenyl)-3-oxo-2, 3-dihydro-pyridazine-4-carboxylic acid 4-chloro-benzylamide, 4- (f [6- (4-hydroxy-3-methoxy-phenyl)-3-oxo-2, 3-dihydro-pyridazine-4- carbonyl]-amino}-methyl)-benzoic acid, 6-(2-butylamino-pyrimidin-4-yl)-3-oxo-2, 3-dihydro-pyridazine-4- carboxylic acid (pyridin-3-ylmethyl)-amide, <BR> <BR> <BR> <BR> <BR> 6- (3-fluoro-4-hydroxy-phenyl)-3-oxo-2, 3-dihydro-pyridazine-4-carboxylic acid 4-chloro-benzylamide, 6- [2- (2-morpholin-4-yl-ethylamino)-pyrimidin-4-yl]-3-oxo-2, 3-dihydro- pyridazine-4-carboxylic acid 4-chloro-benzylamide, N- (3, 4-dichlorobenzyl)-3-oxo-6-pyridin-4-yl-2, 3-dihydropyridazin-4- carboxamide, 3-oxo-6-pyridin-4-yl-2,3-dihydro-pyridazine-4-carboxylic acid [2- (2- chloro-phenyl)-ethyl]-amide, <BR> <BR> <BR> <BR> <BR> 6- (2-methylamino-pyridin-4-yl)-3-oxo-2, 3-dihydro-pyridazine-4-carboxylic acid 4-chloro-benzyl amide, R-3-oxo-6-[2-(1-phenyl-ethylamino)-pyrimidin-4-yl]-2, 3-dihydro- pyridazine-4-carboxylic acid (3-pyridin-3-yl-propyl)-amide, 6- (2-butylamino-pyrimidin-4-yl)-3-oxo-2, 3-dihydro-pyridazine-4- carboxylic acid [3- (4- methyl-piperazin-1-yl)-propyl]-amide, 4-{[(3-oxo-6-pyridin-4-yl-2,3-dihydro-pyridazine-4-carbonyl) -amino]- methyl}-benzoic acid methyl ester,

6-(2-methylamino-pyrimidin-4-yl)-3-oxo-2, 3-dihydro-pyridazine-4- carboxylic acid (3-pyridin-3-yl-propyl)-amide, 6- (4-hydroxy-3-methoxy-phenyl)-3-oxo-2, 3-dihydro-pyridazine-4- carboxylic acid 4-chloro-benzylamide, 6-(2-methylamino-pyrimidin-4-yl)-3-oxo-2, 3-dihydro-pyridazine-4- carboxylic acid 4-chloro-benzylamide, 6- (4-hydroxy-phenyl)-3-oxo-2, 3-dihydro-pyridazine-4-carboxylic acid 4- chloro-benzylamide, 3-oxo-6-pyridin-4-yl-2,3-dihydro-pyridazine-4-carboxylic acid 4-bromo- benzylamide, N-(2,4-dichlorobenzyl)-3-oxo-6-pyridin-4-yl-2, 3-dihydropyridazine-4- carboxamide, 3-oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine-4-carboxylic acid 4-chloro-2- fluoro-benzylamide, and N- (4-chlorobenzyl)-3-oxo-6-pyridin-4-yl-2, 3-dihydropyridazine-4- carboxamide; It is explicitly indicated once more that also in case of the preferred, more preferred, even more preferred, even much more preferred, particularly preferred and exceptionally preferred compounds according to formula (I) the above- mentioned explanations also apply in respect of the salts, stereoisomers, prodrugs, N-oxides etc.; in particular, the respective physiologically acceptable salts are included.

The derivatives of formula (I) for which A = A1= CONHR may be obtained from compounds according to formula (II), where X is a functional group, preferably- OH, C1-C10-alkoxy, chloro or-O-C (O)-(C1-C10-alkyl). The convertion with the amine (III) may be carried out using an inert solvent at 0 to 150 °C.

In case X is OH, the compounds of formula (I) may be obtained by acylation of the amine derivatives, either using an acid chloride to be added beforehand or by reaction in the presence of an activating agent.

The reaction may be carried out by forming an acid chloride according to any methods known to persons skilled in the art or more precisely by the action of oxalyl chloride in toluene, dichloromethane (R. D. MILLER, J. Org. Chem, 56, (4) 1453, (1991) ) which, thus formed, will react with the amine (III) in the presence of a base such as pyridine, triethylamine, diisopropylethylamine ; the reaction can start at 0°C and when the addition of the acid chloride is complete, the medium is kept stirred at room temperature (G. DAIDONE, Heterocycles, 43, (11), 2385-96, (1996) ) or it is heated if necessary.

The reaction may also be carried out in the presence of an activating agent of the carbodiimide type alone (DCC, EDAC) (M. C. DESAI, Tetrahedron Lett., 34,7685, (1993) ) or in the presence of hydroxybenzotriazole and dimethylaminopyridine (J.

P. GAMET, Tetrahedron, 40,1995, (1984), K. BARLOS, J. Org. Chem. , 50,696, (1985) ) or according to well known methods of coupling in peptide chemistry (M.

BODANSZKY, Principles of Peptide Synthesis; Springer-Verlag, New York, NY, pages 9-58, (1984) ) or of forming the amide bond.

The derivatives of formula (II) are obtained by the method described in patent F. R 2481284 and by Y. Shojiro. Chem. Pharm. Bull ; 19 (11) p 2354. It is necessary to protect the reactive functional groups. The protecting groups are introduced according to any methods known to persons skilled in the art and in particular those described by T. W. GREENE, Protective groups in Organic Synthesis, J. Wiley-Interscience Publication (1991). For the phenols, there will be preferably chosen more particularly a benzyl group introduced in the presence of an inorganic base such as sodium carbonate at the reflux temperature of acetone and of acetonitrile (A. R Mac Kenzie, Tetrahedron, 42,3259, (1986) ), which may then

be removed by catalytic hydrogenation or more particularly using trifluoroacetic acid under reflux, described in patent W O 9727846.

The products of general formula (III) may be obtained commercially or by functionalization and protection of the reactive functional groups of commercially available products according to the methods described by Larock, Comprehensive Organic Transformations, VCH, New York, 1999. The nitrile functional groups are reduced with hydrogen in the presence of catalysts, BH3 or more precisely lithium aluminum hydride in solvents such as dioxane or THF (T. M. Koening, Tetrahedron Letters, 35,1339, (1994) ). The phenol functional groups are protected with trimethylsilylethoxymethyl by reacting the starting compound with trimethylsilylethoxymethyl chloride in the presence of sodium hydride in a solvent such as dimethylformamide at room temperature (J. P. WHITTEN, J. Org. Chem., 51,1891, (1986); M. P. EDWARDS, Tetrahedron, 42,3723, (1986) ). The deprotection is carried out according to methods known to persons skilled in the art and described by T. W. GREENE, Protective groups in Organic Synthesis, J.

Wiley-Interscience Publication (1991).

The derivatives of formula (I) for which the protecting group is trimethylsilylethoxymethyl can be deprotected by reaction with tetrabutylammonium fluoride under reflux in solvents such as tetrahydrofuran, dioxane. (J. P. WHITTEN, J. Org. Chem. , 51,1891, (1986); B. H. LIPSHUTZ, Tetrahedron Lett., 4095, (1986)).

The derivatives of formula (I) for which the protecting group is an ester can be saponified according to any methods known to persons skilled in the art and in particular by the action of sodium hydroxide on the reflux (L. Anzalone, J. Org.

Chem. , 50,2128, (1985).

For the derivatives in formula (I) for which A = A2 = NHCOR, it is necessary to subject the derivatives of formula (II) to a rearrangement according to the methods described by Larock, Comprehensive Organic Transformations, VCH, New York, 1999 or more particularly by B. Singh, HETEROCYCLES, 31, (12), 2163, (1990).

The derivatives of formula (I) may be obtained according to route a) by acylating the derivatives of formula (IV) either using an acid chloride, or according to the route b) by acylating the derivatives of formula (IV) or using an anhydride, or according to the route c) by the reaction of an acid in the presence of an activating agent. 0 0 H, N NH2 a) R-C02H HN NC b) (R-C0) 20 NXJ Ar (IV) c) coupling agent Ar (I) Ar Ar (1) By the route (a) the reaction is carried out in the presence of a base such as pyridine, triethylamine, diisopropylethylamine ; the reaction may start at 0°C, and when the addition of the acid chloride is complete, the medium is kept stirred at room temperature (G. DAIDONE, Heterocycles, 43, (11), 2385-96, (1996) or it is heated if necessary.

By the route (b) the reaction is carried out at the reflux temperature of an inert solvent such as xylene or tetrahydrofuran (F. ALBERICIO, Synth. Commun. , 31, (2), 225-32, (2001) ) or dichloromethane, (G. PROCTER, Tetrahedron, 51, (47), 12837-842, (1995) ) or in the anhydride itself.

By the route (c) the reaction is carried out in the presence of an activating agent of the carbodiimide type alone (DCC, EDAC) (M. C. DESAI, Tetrahedron Lett., 34, 7685, (1993) ) or in the presence of hydroxybenzotriazole and dimethylaminopyridine (J. P. GAMET, Tetrahedron, 40,1995, (1984), K. BARLOS, J. Org. Chem. , 50,696, (1985) ) or according to well known methods of coupling in peptide chemistry (M. BODANSZKY, Principles of Peptide Synthesis; Springer- Verlag, New York, NY, pages 9-58, (1984) ) or of forming the amide bond.

Furthermore, compounds according to general formula (I) can be prepared by palladium catalyzed coupling according to a reaction of Suzuki (I. Parrot et al., Synthesis; 7; 1999; 1163-1168). A compound of formula (IV), where Y1 is halogen, B (OH) 2 or Sn (C1-C10-alkyl) and Y2 is H or a protecting group, is hereby converted with a compound of formula (V).

Z may be, for example, B (OH) 2, B (C1-Cio-alkyl) 2, Sn (Ci-C1o-alkyl) 3, Zn (C1-C1o- alkyl) or halogen. In case Y2 is a protecting group, said group is removed after the reaction of (IV) and (V) using methods known by a person skilled in the art. All protecting groups known by a person skilled in the art can be used as protecting groups, preferably trimethylsilylethoxymethyl-. For performing the palladium catalyzed coupling all palladium complexes known by a person skilled in the art can be employed, preferably Pd (triphenylphosphin) 4 (Pd-tetrakis-catalyst) is employed, which is preferably obtained in situ from palladium acetate.

The compounds of formula (I) are isolated and may be purified by known methods, for example by crystallization, chromatography or extraction.

Subject of the present invention is also the use of compounds according to the general formula (I) as pharmaceutical or medicaments, respectively. With respect to the definition of the substituents A and Ar (as well as all further substituents defined by the before-mentioned substituents) the same explanations as laid out above in the context with the compounds as such apply.

The use of compounds according to the general formula (I) as pharmaceutical, where the compounds have the above-mentioned preferred, more preferred, even more preferred, even much more preferred, in particular preferred or exceptionally preferred meaning, are also subject of the present invention.

The compounds of general formula (I) are kinase inhibitors and can therefore be employed for the treatment of diseases, which may result from an abnormal activity of kinases. As abnormal kinase activity, there may be mentioned, for example, that of CDK2 and the like.

In particular, compounds according to the present invention can be used for the inhibition of the kinase CDK2. Since CDK2 is usually part of a complex, such as CDK2/cyclin A or CDK2/cyclin E complexes, the compounds of the present invention can also used as inhibitors of CDK2/cyclin A or CDK2/cyclin E. This effect is particularly relevant for the treatment of neoplastic diseases such cancer.

Examples of diseases, which can be treated with the compounds according to the present invention, include: neoplastic diseases, preferably cancer, in particular a solid tumor.

In the above-mentioned explanation the item treatment also includes prophylaxis, therapy or curing of the above-mentioned diseases.

All references to"compound (s) according to formula (I)"refer hereinbelow to a compound/compounds of the formula (I) as described above and also to their salts, solvates and physiologically functional derivatives as described herein.

The compounds of the formula (I) can be administered to animals, preferably to mammals, and in particular to humans. The compounds of the formula (1) can be administered as pharmaceutical by themselves, in mixtures with one another or in mixtures with other pharmaceuticals or in the form of pharmaceutical preparations.

Further subjects of the present invention therefore also are the use of the compounds of the formula (I) for preparing one or more medicaments for prophylaxis and/or treatment of the before-mentioned diseases, pharmaceutical preparations (or pharmaceutical compositions) comprising an effective dose of at least one compound of the formula (I) as well as pharmaceutical preparations comprising an effective dose of at least one compound of the formula (I) for prophylaxis and/or treatment of the before-mentioned diseases The amount of a compound according to formula (I) which is required in order to attain the desired biological effect depends on a number of factors, for example the specific compound selected, the intended use, the type of administration and

the clinical state of the patient. In general, the daily dose is in the range from 0.3 mg to 100 mg (typically from 3 mg to 50 mg) per day per kilogram of body weight, for example 3-10 mg/kg/day. An intravenous dose can be, for example, in the range from 0.3 mg to 1.0 mg/kg and can be administered in a suitable manner as an infusion of 10 ng to 100 ng per kilogram per minute. Suitable infusion solutions for these purposes may contain, for example, from 0.1 ng to 10 mg, typically from 1 ng to 10 mg per milliliter. Individual doses may contain, for example, from 1 mg to 10 g of the active compound. Thus, ampoules for injections can contain, for example, from 1 mg to 100 mg, and orally administerable individual dose formulations such as, for example, tablets or capsules can contain, for example, from 1.0 to 1000 mg, typically from 10 to 600 mg. In the case of pharmaceutical acceptable salts, the abovementioned masses relate to the mass of the free compound on which the salt is based. The compound used for the prophylaxis or therapy of the abovementioned conditions may be the compounds according to formula (I) themselves, but they are preferably present in the form of a pharmaceutical composition together with an acceptable carrier. The carrier must be naturally acceptable, in the sense that it is compatible with the other ingredients of said composition and is not harmful to the patient's health. The carrier may be a solid or a liquid or both and is preferably formulated with the compound as an individual dose, for example as a tablet which may contain from 0.05% to 95% by weight of the active compound. Further pharmaceutical active substances may also be present, including further compounds according to formula (I). The pharmaceutical compositions of the invention may be prepared according to any of the known pharmaceutical methods which essentially comprise mixing the ingredients with pharmacologically acceptable carriers and/or excipients.

Besides at least one compound according to formula (I) as well as one or more carriers, the pharmaceutical preparations can also contain additives. As additives can be employed, for example : fillers, binders, lubricants, wetting agents, stabilizers, emulsifiers, dispersants, preservatives, sweeteners, colorants, flavorings, aromatizers, thickeners, diluents, buffer substances, solvents, solubilizers, agents for achieving a depot effect, salts for altering the osmotic pressure, coating agents or antioxidants.

The pharmaceutical compositions of the invention may be in form of a pill, tablet, lozenge, coated tablet, granule, capsule, hard or soft gelatin capsule, aqueous

solution, alcoholic solution, oily solution, syrup, emulsion suspension pastille suppository, solution for injection or infusion, ointment, tincture, cream, lotion, powder, spray, transdermal therapeutic systems, nasal spray, aerosol mixture, microcapsule, implant, rod or plaster.

Pharmaceutical compositions of the invention are those which are suitable for oral, rectal, topical, peroral (e. g. sublingual) and parenteral (e. g. subcutaneous, intramuscular, intradermal or intravenous) administration, although the most suitable manner of administration depends in each individual case on the nature and severity of the condition to be treated and on the nature of the compound according to formula (I) used in each case. Sugar-coated formulations and sugar- coated delayed-release formulations, too, are included within the scope of the invention. Preference is given to acid-resistant and enteric formulations. Suitable enteric coatings include cellulose acetate phthalate, polyvinyl acetate phthalate, hydroxypropyl-methylcellulose phthalate and anionic polymers of methacrylic acid and methyl methacrylate.

Suitable pharmaceutical compounds for oral administration may be present in separate units as, for example, capsules, cachets, lozenges or tablets, which in each case contain a particular amount of the compound according to formula (I) ; as powders (gelatin capsules or cachets) or granules; as solution or suspension in an aqueous or nonaqueous liquid; or as an oil-in-water or water-in-oil emulsion. As already mentioned, said compositions can be prepared according to any suitable pharmaceutical method which includes a step in which the active compound and the carrier (which may comprise one or more additional components) are contacted. In general, the compositions are prepared by uniform and homogeneous mixing of the active compound with a liquid and/or finely dispersed solid carrier, after which the product is shaped, if necessary. Thus a tablet, for example, may be prepared by pressing or shaping a powder or granules of the compound, where appropriate with one or more additional components. Pressed tablets can be prepared by tableting the compound in free-flowing form, for example a powder or granules, mixed, where appropriate, with a binder, lubricant, inert diluent and/or one or more surface active/dispersing agents in a suitable machine. Shaped tablets can be prepared by shaping the pulverulent compound, moistened with an inert liquid diluent, in a suitable machine. As diluents can be used, for example, starch, cellulose, saccharose, lactose or silica. The pharmaceutical compositions of the invention may also comprise substances other

than diluents, for example one or more lubricants such as magnesium stearate or talc, a coloring, a coating (sugar-coated tablets) or a varnish.

Pharmaceutical compositions which are suitable for peroral (sublingual) administration include lozenges which contain a compound according to formula (I) with a flavoring, usually sucrose and gum arabic or tragacanth, and pastilles which comprise the compound in an inert base such as gelatin and glycerol or sucrose and gum arabic.

Suitable pharmaceutical compositions for parenteral administration preferably comprise sterile aqueous preparations of a compound according to formula (I) which are preferably isotonic with the blood of the intended recipient. These preparations are preferably administered intravenously, although they may also be administered subcutaneously, intramuscularly or intradermally as an injection. Said preparations may preferably be prepared by mixing the compound with water and rendering the obtained solution sterile and isotonic with the blood. Injectable compositions of the invention generally contain from 0.1 to 5% by weight of the active compound.

These sterile compositions for parenteral administration may be preferably solutions which are aqueous or non aqueous, suspensions or emulsions. As solvent or vehicle, there may be used water, propylene glycol, polyethylene glycol, vegetable oils, in particular olive oil, organic esters for injection, for example ethyl oleate or other suitable organic solvents. These compositions may also contain adjuvants, in particular wetting, isotonizing, emulsifying, dispersing and stabilizing mediums. The sterilization may be carried out in several ways, for example by an aseptic filtration, by incorporating sterilizing agents into the composition, by irradiation or by heating. They may also be prepared in the form of sterile solid compositions which may be dissolved at the time of use in sterile water or in any other sterile medium for injection.

Suitable pharmaceutical compositions for rectal administration are preferably present as individual dose suppositories. These may be prepared by mixing a compound according to formula (I) with one or more conventional solid carriers, for example cocoa butter, and shaping the resulting mixture.

Suitable pharmaceutical compositions for topical application to the skin are preferably present as ointment, cream, lotion, paste, spray, aerosol or oil. Carriers which may be used are petroleum jelly, lanolin, polyethylene glycols, alcohols and combinations of two or more of these substances. In general, the active compound is present at a concentration of from 0.1 to 15%, for example from 0.5 to 2%, by weight of the composition.

Transdermal administration is also possible. Suitable pharmaceutical compositions for transdermal administration may be present as individual patches which are suitable for long-term close contact with the epidermis of the patient. Such patches suitably contain the active compound in an optionally buffered aqueous solution, dissolved and/or dispersed in an adhesive or dispersed in a polymer. A suitable active compound concentration is from approx. 1 % to 35%, preferably approx. 3% to 15%. A particular possibility is the release of the active compound by electro- transport or iontophoresis, as described, for example, in Pharmaceutical Research, 2 (6): 318 (1986).

The following examples illustrate compositions according to the invention: EXAMPLE A Gelatin capsules containing a dose of 50 mg of active product and having the following composition are prepared according to the usual technique: - Compound of formula 50 mg - 18 mg - 55 mg - Colloidal silica 1 mg - Sodium 10 mg - Talc 10 mg -Magnesium stearate 1 mg EXAMPLE B Tablets containing a dose of 50 mg of active product and having the following composition are prepared according to the usual technique:

- Compound of formula 50 mg - 104 mg - 40 mg - 10 mg - Sodium 22 mg - 10 mg -Magnesium stearate 2 mg -Colloidal silica 2 mg - Mixture of hydroxymethylcellulose, glycerin, titanium oxide (72-3. 5-24. 5) qs 1 finished film-coated tablet of 245 mg EXAMPLE C A solution for injection containing 10 mg of active product and having the following composition is prepared: - Compound of formula 10 mg -Benzoic acid 80 mg - Benzyl 0. 06 ml - Sodium benzoate 80 mg 0 - Ethanol at 95 % 0. 4 ml - Sodium hydroxide 24 mg -Propylene glycol 1. 6 ml - qs 4 ml Another subject of the present invention is the combination of compounds of the formula (I) with other pharmaceutical active substances not covered by formula (1).

The compounds of the present invention may be administered alone or mixed with other anticancer agents. Among the possible combinations, there may be mentioned: - alkylating agents and in particular cyclophosphamide, melphalan, ifosfamide, chlorambucil, busulfan, thiotepa, prednimustine, carmustine, lomustine, semustine, streptozotocin, decarbazine, temozolomide, procarbazine and hexamethylmelamine ;

- platinum derivatives such as in particular cisplatin, carboplatin or oxaliplatin ; - antibiotic agents such as in particular bleomycin, mitomycin or dactinomycin; - antimicrotubule agents such as in particular vinblastine, vincristine, vindesine, vinorelbine or taxoids (paclitaxel and docetaxel) ; - anthracyclines such as in particular doxorubicin, daunorubicin, idarubicin, epirubicin, mitoxantrone or losoxantrone ; - group) and)) topoisomerases such as etoposide, teniposide, amsacrine, irinotecan, topotecan or tomudex; - fluoropyrimidines such as 5-fluorouracil, UFT or floxuridine ; - cytidine analogues such as 5-azacytidine, cytarabine, gemcitabine, 6- mercaptomurine or 6-thioguanine; - adenosine analogues such as pentostatin, cytarabine or fludarabine phosphate; - methotrexate and folinic acid; - various enzymes and compounds such as L-asparaginase, hydroxyurea, trans- retinoic acid, suramine, dexrazoxane, amifostine, herceptin as well as oestrogenic and androgenic hormones.

It is also possible to combine a radiation treatment with the compounds of the present invention. This treatment may be administered simultaneously, separately or sequentially. The treatment will be adapted to the patient to be treated by the practitioner.

The following examples illustrate the invention without limitation.

Example 1 <BR> <BR> <BR> N-(2, 4-dichlorobenzyl)-3-oxo-6-phenyl-4-yl-2, 3-dihydropyridazine-4- carboxamide

0.14 g of 1-hydroxybenzotriazole, 0. 14 cm3 of 2, 4-dichlorobenzylamine and 0.14 cm3 of triethylamine are added to 0. 2 g of 3-oxo-6-phenyl-2, 3-dihydro- pyridazine-4-carboxylic acid prepared as described by Y. Shojiro et al., Chem.

Pharm. Bull ; 19, (11), p. 2354, in 10 cm3 of dichloromethane. 0.2 g of 1- (3- dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride is then added. The mixture is stirred for 48 hours at 19°C. 10 cm3 of distilled water are added. The organic phase is washed again with 3 times 10cm3 of aqueous normal hydrochloric acid solution and then with 10cm3 of saturated aqueous sodium chloride solution. The organic phase is then dried over magnesium sulfate. The mixture is filtered through a sinter funnel and then evaporated under reduced pressure (2 kPa; 45°C). The residue is taken up with 10 cm3 of diisopropyl ether.

The insoluble material is filtered off through a sinter funnel and then rinsed again with 10cm3 of diisopropyl ether. After drying (10kPa ; 20°C), 28 mg of N- (2, 4- dichlorobenzyl)-3-oxo-6-phenyl-4-yl-2, 3-dihydropyridazine-4-carboxamide are ob- tained in the form of a cream-colored solid melting at about 258°C.

'H NMR spectrum (300 MHz, (CD3) 2SO d6, 8 in ppm): 4.64 (d, J = 6 Hz: 2H); from 7.40 to 7.60 (mt: 5H); 7.66 (broad s: 1 H) ; 7.92 (mt: 2H); 8.55 (s: 1 H) ; 10.04 (broad t, J = 6 Hz: 1 H) ; from 13.80 to 14.15 (broad unresolved peak: 1 H).

[M+1] -peak: 374 Example 2 <BR> <BR> N-(2, 4-dichlorobenzyl)-3-oxo-6-pyridin-4-yl-2, 3-dihydropyridazine-4- carboxamide

0.02 cm3 of dimethylformamide and then 0.12 cm3 of oxalyl chloride are added to 0.3 g of 3-oxo-6- (pyridin-4-yl)-2, 3-dihydropyridazine-4-carboxylic acid prepared as described in patent FR 2 481 284, dissolved in 10cm3 of dichloromethane. The reaction medium is stirred for 3 hours at 19°C. A further 0.12 cm3 of oxalyl chloride is then added and the mixture is stirred for a further one hour at 19°C. The reaction mixture is then poured onto a solution of 10cm3 of dichloromethane containing 0.19 cm3 of triethylamine and 0.21 cm3 of 2, 4-dichlorobenzylamine. The reaction medium is stirred for 12 hours at 19°C and then filtered through a sinter funnel, rinsed with 10 cm3 of dichloromethane, 10 cm3 of distilled water and with 10 cm3 of aqueous normal hydrochloric acid solution. After drying (10 kPa; 20°C), 0.25 g of N-(2, 4-dichlorobenzyl)-3-oxo-6-pyridin-4-yl-2, 3-dihydropyridazine-4- carboxamide is obtained in the form of a white solid melting at 233°C. oh NMR spectrum (300 MHz, (CD3) 2SO d6, 8 in ppm): 4.64 (d, J = 6 Hz: 2H); 7.45 (mt: 2H); 7.66 (broad s: 1 H) ; 7.91 (broad d, J = 5 Hz: 2H); 8.62 (s: 1 H) ; 8.73 (broad d, J = 5 Hz: 2H); 9.95 (broad t, J = 6 Hz: 1 H); 14.25 (unresolved peak: 1 H).

[M+1]-peak : 375,03 Example 3 N-benzyl-3-oxo-6-pyridin-4-yl-2, 3-dihydropyridazine-4-carboxamide

Working as in example 2 for the preparation of N- (2, 4-dichlorobenzyl)-3-oxo-6- pyridin-4-yl-2, 3-dihydropyridazine-4-carboxamide, but starting with 0.3 g of 3-oxo- 6-pyridin-4-yl-2, 3-dihydropyridazine-4-carboxylic acid, 10 cm3 of dichloromethane, 0.02 cm3 of dimethylformamide, 0. 12 cm3 of oxalyl chloride, 0.17 cm3 of benzylamine and 0.19 cm3 of triethylamine, 0. 22 g of N-benzyl-3-oxo-6-pyridin-4- yl-2, 3-dihydropyridazine-4-carboxamide is obtained in the form of a cream-colored solid melting at 258°C.

'H NMR spectrum (300 MHz, (CD3) 2SO d6, 8 in ppm): 4.61 (d, J = 6 Hz: 2H); from 7.25 to 7.45 (mt: 5H); 7.92 (broad d, J = 6 Hz: 2H); 8.64 (s: 1 H) ; 8.73 (broad d, J = 6 Hz: 2H); 9.93 (broad t, J = 6 Hz: 1 H).

[M+1] -peak: 307 Example 4 <BR> <BR> <BR> N- (4-chlorobenzyl)-3-oxo-6-pyridin-4-yl-2, 3-dihydropyridazine-4-carboxamide Working as in example 2 for the preparation of N- (2, 4-dichlorobenzyl)-3-oxo-6-

pyridin-4-yl-2, 3-dihydropyridazine-4-carboxamide, but starting with 0.3 g of 3-oxo- 6-pyridin-4-yl-2, 3-dihydropyridazine-4-carboxylic acid, 10 cm3 of dichloromethane, 0.02 cm3 of dimethylformamide, 0.12 cm3 of oxalyl chloride, 0.19 cm3 of 4- chlorobenzylamine and 0. 19 cm3 of triethylamine, 0. 2 g of N- (4-chlorobenzyl)-3- oxo-6-pyridin-4-yl-2, 3-dihydropyridazine-4-carboxamide is obtained in the form of a cream-colored solid melting at 250°C.

'H NMR spectrum (300 MHz, (CD3) 2SO d6, 8 in ppm): 4.60 (d, J = 6 Hz: 2H); 7.41 (mt: 4H); 7.92 (broad d, J = 6 Hz: 2H); 8.64 (s: 1H) ; 8.73 (broad d, J = 6 Hz: 2H); 9.91 (broad t, J = 6 Hz : 1 H).

[M+1] -peak: 341 Example 5 <BR> <BR> N- (2-chlorobenzyl)-3-oxo-6-pyridin-4-yl-2, 3-dihydropyridazine-4-carboxamide Working as in example 2 for the preparation of N- (2, 4-dichlorobenzyl)-3-oxo-6- pyridin-4-yl-2, 3-dihydropyridazine-4-carboxamide, but starting with 0.3 g of 3-oxo- 6-pyridin-4-yl-2, 3-dihydropyridazine-4-carboxylic acid, 10 cm3 of dichloromethane, 0.02 cm3 of dimethylformamide, 0. 12 cm3 of oxalyl chloride, 0.19 cm3 of 2- chlorobenzylamine and 0.19 cm3 of triethylamine, 0.25 g of N- (2-chlorobenzyl)-3- oxo-6-pyridin-4-yl-2, 3-dihydropyridazine-4-carboxamide is obtained in the form of a white solid melting above 260°C. oh NMR spectrum (300 MHz, (CD3) 2SO d6, 8 in ppm): 4.67 (d, J = 6 Hz: 2H); 7.35 (mt: 2H); from 7.40 to 7.55 (mt: 2H); 7.92 (broad d, J = 6 Hz: 2H); 8.63 (s: 1H) ; 8.72 (broad d, J = 6 Hz: 2H); 9.95 (broad t, J = 6 Hz: 1 H) ; 14.25 (s: 1 H).

[M+1]-peak : 341 Example 6 <BR> <BR> N- [2- (2, 4-dichlorophenyl) ethyl]-3-oxo-6-pyridin-4-yl-2, 3-dihydropyridazine-4- carboxamide

Working as in example 2 for the preparation of N- (2, 4-dichlorobenzyl)-3-oxo-6- pyridin-4-yl-2, 3-dihydropyridazine-4-carboxamide, but starting with 0.3 g of 3-oxo- 6-pyridin-4-yl-2, 3-dihydropyridazine-4-carboxylic acid, 10 cm3 of dichloromethane, 0.02 cm3 of dimethylformamide, 0.12 cm3 of oxalyl chloride, 0.23 cm3 of 2,4- dichlorophenylethylamine and 0. 19 cm3 of triethylamine, 0.23 g of N- [2- (2, 4- dichlorophenyl) ethyl]-3-oxo-6-pyridin-4-yl-2, 3-dihydropyridazine-4-carboxamide is obtained in the form of a cream-colored solid melting at 202°C.

'H NMR spectrum (300 MHz, (CD3)2SO d6, 8 in ppm): 3.00 (t, J = 7 Hz: 2H); 3.63 (q, J = 7 Hz: 2H); 7.38 (dd, J = 8. 5 and 2 Hz: 1H) ; 7.44 (d, J = 8 Hz: 1H) ; 7.60 (d, J = 2 Hz: 1H) ; 7.90 (d mt, J = 6 Hz: 2H); 8.49 (s: 1H) ; 8.68 (d mt, J = 6 Hz: 2H); 9.96 (unresolved peak: 1H) ; from 13.50 to 14.50 (very broad unresolved peak: 1H).

[M+1] -peak: 389 Example 7 N-(2, 4-dichlorophenyl)-3-oxo-6-pyridin-4-yl-2, 3-dihydropyridazine-4- carboxamide

Working as in example 2 for the preparation of N- (2, 4-dichlorobenzyl)-3-oxo-6- pyridin-4-yl-2, 3-dihydropyridazine-4-carboxamide, but starting with 0.3 g of 3-oxo- 6-pyridin-4-yl-2, 3-dihydropyridazine-4-carboxylic acid, 10 cm3 of dichloromethane, 0.02 cm3 of dimethylformamide, 0. 12 cm3 of oxalyl chloride, 0. 036 g of 2,4- dichloroaniline and 0. 19 cm3 of triethylamine, 0. 16 g of N- (2, 4-dichlorophenyl)-3- oxo-6-pyridin-4-yl-2, 3-dihydropyridazine-4-carboxamide is obtained in the form of a cream-colored solid melting above 260°C.

'H NMR spectrum (400 MHz, (CD3) 2SO d6 with addition of a few drops of CD3COOD d4, 8 in ppm): 7.52 (dd, J = 8.5 and 2.5 Hz: 1H) ; 7.75 (d, J = 2.5 Hz: 1 H) ; 7.96 (d mt, J = 6 Hz: 2H); 8.60 (d, J = 8.5 Hz: 1 H) ; 8.75 (broad d, J = 6 Hz: 2H); 8.77 (s: 1H).

[M+1] -peak: 361 Example 8 3-oxo-6-pyridin-4-yl-N- (pyridin-4-ylmethyl)-2, 3-dihydropyridazine-4- carboxamide Working as in example 2 for the preparation of N- (2, 4-dichlorobenzyl)-3-oxo-6- pyridin-4-yl-2, 3-dihydropyridazine-4-carboxamide, but starting with 0.3 g of 3-oxo- 6-pyridin-4-yl-2, 3-dihydropyridazine-4-carboxylic acid, 10 cm3 of dichloromethane, 0.02 cm3 of dimethylformamide, 0. 12 cm3 of oxalyl chloride, 0.15 cm3 of 4- (aminomethyl) pyridine and 0.19 cm3 of triethylamine, 0. 14 g of 3-oxo-6-pyridin-4-

yl-N- (pyridin-4-ylmethyl)-2, 3-dihydropyridazine-4-carboxamide is obtained in the form of a cream-colored solid melting at 254°C. oh NMR spectrum (300 MHz, (CD3) 2SO d6, 8 in ppm): 4.63 (d, J = 6 Hz: 2H); 7.35 (broad d, J = 6 Hz: 2H); 7.92 (d mt, J = 6 Hz: 2H); 8.53 (broad d, J = 6 Hz: 2H); 8.62 (s: 1 H); 8.72 (broad d, J = 6 Hz: 2H); 9.99 (t, J = 6 Hz: 1 H); 14.26 (unresolved peak: 1 H).

[M+1] -peak: 308 Example 9 3-oxo-6-pyridin-4-yl-N- [3- (trifluoromethyl) benzyl]-2, 3-dihydropyridazine-4- carboxamide Working as in example 2 for the preparation of N- (2, 4-dichlorobenzyl)-3-oxo-6- pyridin-4-yl-2, 3-dihydropyridazine-4-carboxamide, but starting with 0.3 g of 3-oxo- 6-pyridin-4-yl-2, 3-dihydropyridazine-4-carboxylic acid, 10 cm3 of dichloromethane, 0. 02cm3 of dimethylformamide, 0. 12cm3 of oxalyl chloride, 0.21 cm3 of 3- (trifluoromethyl) benzylamine and 0.19 cm3 of triethylamine, 0. 22 g of 3-oxo-6- pyridin-4-yl-N- [3- (trifluoromethyl) benzyl]-2, 3-dihydropyridazine-4-carboxamide is obtained in the form of a cream-colored solid melting at 224°C.

'H NMR spectrum (300 MHz, (CD3) 2SO d6, 8 in ppm): 4.68 (d, J = 6 Hz: 2H); from 7.55 to 7.75 (mt: 3H); 7.74 (broad s: 1 H) ; 7.91 (d mt, J = 6 Hz: 2H); 8.63 (s: 1 H) ; 8.72 (d mt, J = 6 Hz: 2H); 9.96 (broad t, J = 6 Hz: 1H) ; 14.21 (unresolved peak: 1H).

[M+1] -peak: 375 Example 10 <BR> <BR> 3-oxo-6-pyridin-4-yl-N- [4- (trifluoromethyl) benzyl]-2, 3-dihydropyridazine-4- carboxamide

Working as in example 2 for the preparation of N- (2, 4-dichlorobenzyl)-3-oxo-6- pyridin-4-yl-2, 3-dihydropyridazine-4-carboxamide, but starting with 0.3 g of 3-oxo- 6-pyridin-4-yl-2, 3-dihydropyridazine-4-carboxylic acid, 10 cm3 of dichloromethane, 0.02 cm3 of dimethylformamide, 0. 12cm3 of oxalyl chloride, 0.21 cm3 of 4- (trifluoromethyl) benzylamine and 0.19 cm3 of triethylamine, 0. 22 g of 3-oxo-6- pyridin-4-yl-N- [4- (trifluoromethyl) benzyl]-2, 3-dihydropyridazine-4-carboxamide is obtained in the form of a cream-colored solid melting at 227°C.

'H NMR spectrum (300 MHz, (CD3) 2SO d6, 8 in ppm): 4.69 (d, J = 6 Hz: 2H); 7.59 (broad d, J = 8 Hz: 2H); 7.73 (broad d, J = 8 Hz: 2H); 7.91 (d mt, J = 6 Hz: 2H); 8.62 (s: 1H) ; 8.72 (d mt, J = 6 Hz: 2H); 10.04 (very broad t, J = 6 Hz: 1H) ; 14.24 (unresolved peak: 1 H).

[M+1] -peak: 375 Example 11 N- (3, 5-dichlorobenzyl)-3-oxo-6-pyridin-4-yl-2, 3-dihydropyridazine-4- carboxamide

Working as in example 2 for the preparation of N- (2, 4-dichlorobenzyl)-3-oxo-6- pyridin-4-yl-2, 3-dihydropyridazine-4-carboxamide, but starting with 0.3 g of 3-oxo- 6-pyridin-4-yl-2, 3-dihydropyridazine-4-carboxylic acid, 10 cm3 of dichloromethane, 0.02 cm3 of dimethylformamide, 0.12 cm3 of oxalyl chloride, 0. 19 cm3 of 3,5- dichlorobenzylamine and 0. 19 cm3 of triethylamine, 0. 025 g of N- (3, 5- dichlorobenzyl)-3-oxo-6-pyridin-4-yl-2, 3-dihydropyridazine-4-carboxamide is obtained in the form of a white solid melting above 260°C.

'H NMR spectrum (300 MHz, (CD3) 2SO d6, # in ppm): 4.59 (d, J = 6 Hz: 2H); 7.43 (mt: 2H); 7.51 (mt: 1H) ; 7.91 (d mt, J = 6 Hz: 2H); 8.57 (s: 1H) ; 8.70 (d mt, J = 6 Hz: 2H); 10.14 (unresolved peak: 1H) ; 14.18 (broad unresolved peak: 1H).

[M+1] -peak: 375 Example 12 3-oxo-6-pyridin-4-yl-N- (n-butyl)-2, 3-dihydropyridazine-4-carboxamide Working as in example 2 for the preparation of N- (2, 4-dichlorobenzyl)-3-oxo-6- pyridin-4-yl-2, 3-dihydropyridazine-4-carboxamide, but starting with 0.3 g of 3-oxo- 6-pyridin-4-yl-2, 3-dihydropyridazine-4-carboxylic acid, 10 cm3 of dichloromethane, 0.02 cm3 of dimethylformamide, 0.12 cm3 of oxalyl chloride, 0.15 cm3 of n- butylamine and 0.19 cm3 of triethylamine, and after purification by chromatography on silica gel (particle size 40-63 pm, under an argon pressure of 150 kPa), eluting with a mixture of dichloromethane and methanol (97.5/2. 5 by volume), 0.23 g of 3- oxo-6-pyridin-4-yl-N- (n-butyl)-2, 3-dihydropyridazine-4-carboxamide is obtained in the form of a white solid melting at 209°C.

'H NMR spectrum (300 MHz, (CD3) 2SO d6, 8 in ppm): 0.93 (t, J = 7 Hz: 3H); 1.38 (mt: 2H); 1.55 (mt: 2H); 3.37 (mt: 2H); 7.90 (d mt, J = 6 Hz: 2H); 8.60 (s: 1 H) ; 8.72 (broad d, J = 6 Hz: 2H); 9.50 (t, J = 6 Hz: 1 H); 14.20 (unresolved peak: 1 H).

[M+1] -peak: 273 Example 13 Ethyl 3-[(3-oxo-6-pyridin-4-yl-2, 3-dihydropyridazine-4-carbonyl) amino] propionate 0.733 g of 1-hydroxybenzotriazole, 0.833 g of 0-alanine ethyl ester hydrochloride, 0.96 cm3 of N, N-diisopropylethylamine and 2.06 g of 0- (7-azabenzotriazol-1-yl)- N, N, N', N'-tetramethyluronium hexafluorophosphate are successively added to 0.94 g of 3-oxo-6-pyridin-4-yl-2, 3-dihydropyridazine-4-carboxylic acid dissolved in 100 cm3 of N, N-dimethylformamide. The reaction medium is stirred for 12 hours at 19°C. The solvent is evaporated off under reduced pressure (2 kPa; 55°C). The solid residue is triturated in 20 cm3 of dichloromethane, suction-filtered and oven- dried under reduced pressure (10 kPa; 20°C). After purification by chromatography on silica gel (particle size 40-63, um, under an argon pressure of 150 kPa) eluting with dichloromethane, 0. 45 g of ethyl 3- [ (3-oxo-6-pyridin-4-yl-2, 3- dihydropyridazine-4-carbonyl) amino] propionate is obtained in the form of a white solid melting at 180°C.

1 H NMR spectrum (300 MHz, (CD3) 2SO d6, 8 in ppm): 1.22 (t, J = 7 Hz: 3H); 2.63 (broad t, J = 6.5 Hz: 2H); 3.62 (q, J = 6.5 Hz: 2H); 4.12 (q, J = 7 Hz: 2H); 7. 92 (broad d, J = 6 Hz: 2H); 8.61 (s: 1 H) ; 8.73 (broad d, J = 6 Hz: 2H); 9.69 (broad t, J = 6. 5 Hz: 1 H).

[M+1] -peak: 317 Example 14 3-oxo-6-pyridin-4-yl-N- (pyridin-3-ylmethyl)-2, 3-dihydropyridazine-4-carboxamide

Working as in example 13 for the preparation of ethyl 3- [ (3-oxo-6-pyridin-4-yl-2, 3- dihydropyridazine-4-carbonyl) amino] propionate, but starting with 0.3 g of 3-oxo-6- pyridin-4-yl-2, 3-dihydropyridazine-4-carboxylic acid, 30 cm3 of N, N- dimethylformamide, 0. 233 g of 1-hydroxybenzotriazole, 0. 18 cm3 of 3- (aminomethyl) pyridine, 0.31 cm3 of N, N-diisopropylethylamine and 0.65 g of 0- (7- azabenzotriazol-1-yl)-N, N, N', N'-tetramethyluronium hexafluorophosphate, 0. 046 g of 3-oxo-6-pyridin-4-yl-N- (pyridin-3-ylmethyl)-2, 3-dihydropyridazine-4-carboxamide is obtained in the form of a yellow solid melting at 262°C.

'H NMR spectrum (300 MHz, (CD3) 2SO d6, 8 in ppm): 4.62 (d, J = 6 Hz: 2H); 7.38 (broad dd, J = 8 and 5 Hz: 1 H); 7.79 (very broad d, J = 8 Hz: 1 H); 7.91 (broad d, J = 6 Hz: 2H); 8.48 (broad d, J = 5 Hz: 1 H) ; 8.60 (broad s: 1 H) ; 8.62 (s: 1 H) ; 8.72 (broad d, J = 6 Hz: 2H); 9.94 (broad t, J = 6 Hz: 1 H); 14.15 (unresolved peak: 1 H).

[M+1] -peak: 308 Example 15 3-oxo-6-pyridin-4-yl-N- (pyridin-2-ylmethyl)-2, 3-dihydropyridazine-4- carboxamide Working as in example 13 for the preparation of ethyl 3- [ (3-oxo-6-pyridin-4-yl-2, 3- dihydropyridazine-4-carbonyl) amino] propionate, but starting with 0.3 g of 3-oxo-6- pyridin-4-yl-2, 3-dihydropyridazine-4-carboxylic acid, 30 cm3 of N, N-

dimethylformamide, 0. 233 g of 1-hydroxybenzotriazole, 0.18 cm3 of 2- (aminomethyl) pyridine, 0.31 cm3 of N, N-diisopropylethylamine and 0.65 g of 0- (7- azabenzotriazol-1-yl)-N, N, N', N'-tetramethyluronium hexafluorophosphate, 0. 125 g of 3-oxo-6-pyridin-4-yl-N- (pyridin-2-ylmethyl)-2, 3-dihydropyridazine-4-carboxamide is obtained in the form of a white solid melting at 242°C.

'H NMR spectrum (300 MHz, (CD3) 2SO d6, 8 in ppm): 4.71 (d, J = 6 Hz: 2H); 7.33 (broad dd, J = 8 and 5.5 Hz: 1 H); 7.42 (broad d, J = 8 Hz: 1 H); 7.81 (resolved t, J = 8 and 2 Hz: 1 H); 7.93 (broad d, J = 6 Hz: 2H); 8.57 (broad d, J = 5.5 Hz: 1 H); 8.63 (s: 1 H) ; 8.73 (broad d, J = 6 Hz: 2H); 10.24 (broad t, J = 6 Hz: 1 H) ; from 14.00 to 14.50 (very broad unresolved peak: 1 H).

[M+1] -peak: 308 Example 16 N- (3, 4-dichlorobenzyl)-3-oxo-6-pyridin-4-yl-2, 3-dihydropyridazine-4- carboxamide Working as in example 13 for the preparation of ethyl 3- [ (3-oxo-6-pyridin-4-yl-2, 3- dihydropyridazine-4-carbonyl) amino] propionate, but starting with 0.3 g of 3-oxo-6- pyridin-4-yl-2, 3-dihydropyridazine-4-carboxylic acid, 30 cm3 of N, N- dimethylformamide, 0.233 g of 1-hydroxybenzotriazole, 0. 19 cm3 of 3,4- dichlorobenzylamine, 0.31 cm3 of N, N-diisopropylethylamine and 0.65 g of 0- (7- azabenzotriazol-1-yl)-N, N, N', N'-tetramethyluronium hexafluorophosphate, 0. 28 g of N- (3, 4-dichlorobenzyl)-3-oxo-6-pyridin-4-yl-2, 3-dihydropyridazine-4- carboxamide is obtained in the form of a cream-colored solid melting at 265°C.

'H NMR spectrum (300 MHz, (CD3) 2SO d6, 5 in ppm): 4.58 (d, J = 6 Hz: 2H); 7.37 (dd, J = 8 and 1.5 Hz: 1 H); 7.62 (d, J = 8 Hz: 1 H); 7.64 (mt: 1 H); 7.91 (broad d, J = 6 Hz: 2H); 8.62 (s: 1 H); 8.72 (broad d, J = 6 Hz: 2H); 9.92 (broad t, J = 6 Hz: 1 H); from 14.00 to 14.40 (very broad unresolved peak: 1 H).

[M+1] -peak: 375 Example 17 <BR> <BR> N- (4-morpholin-4-ylbenzyl)-3-oxo-6-pyridin-4-yl-2, 3-dihydropyridazine-4- carboxamide

Working as in example 13 for the preparation of ethyl 3- [ (3-oxo-6-pyridin-4-yl-2, 3- dihydropyridazine-4-carbonyl) amino] propionate, but starting with 0.3 g of 3-oxo-6- pyridin-4-yl-2, 3-dihydropyridazine-4-carboxylic acid, 30 cm3 of N, N- dimethylformamide, 0.233 g of 1-hydroxybenzotriazole, 0.265 g of 4-morpholino- benzylamine, 0.31 cm3 of N, N-diisopropylethylamine and 0. 65g of 0- (7- azabenzotriazol-1-yl)-N, N, N', N'-tetramethyluronium hexafluorophosphate, and after purification by chromatography on silica gel (particle size 40-63 pm, under an argon pressure of 150 kPa), eluting with dichloromethane, 0. 13 g of N- (4- morpholin-4-ylbenzyl)-3-oxo-6-pyridin-4-yl-2, 3-dihydropyridazine-4-carboxamide is obtained in the form of a yellow solid melting at 252°C.

'H NMR spectrum (300 MHz, (CD3) 2SO d6, 8 in ppm): 3.09 (t, J = 5 Hz: 4H); 3.74 (t, J = 5 Hz: 4H); 4.48 (d, J = 6 Hz: 2H); 6.93 (d, J = 8 Hz: 2H); 7.24 (d, J = 8 Hz: 2H); 7.91 (broad d, J = 6 Hz: 2H); 8.62 (s: 1 H) ; 8.72 (broad d, J = 6 Hz: 2H); 9.85 (very broad t, J = 6 Hz: 1 H); 14.22 (unresolved peak: 1 H).

[M+1] -peak: 392,16 Example 18 (Trimethylsilyl)-2-ethoxymethoxy-4-benzonitrile 0.085 9 of 4-dimethylaminopyridine and 4. 9cm3 of chloromethylethoxy (trimethylsilyl) are added successively to 3 g of 4- hydroxybenzonitrile dissolved in 60 cm3 of dichloromethane, followed by addition

of 5.62 cm3 of triethylamine. The reaction medium is stirred for 12 hours at 19°C and then washed with three times 10 cm3 of aqueous normal hydrochloric acid solution, then with 10 cm3 of water, then with 10 cm3 of normal sodium hydroxide and finally with 10 cm3 of saturated sodium chloride solution. The organic phase is dried over magnesium sulfate, filtered through a sinter funnel and then evaporated under reduced pressure (2 kPa; 45°C). After purification by chromatography on silica gel (particle size 40-63 um, under an argon pressure of 150 kPa), eluting with dichloromethane, 3.5 g of (trimethylsilyl)-2-ethoxymethoxy-4-benzonitrile are obtained in the form of a colorless oil.

Mass spectrum: El, m/z = 206 (M-SiCH3) +, m/z = 191 (M-Si (CH3) 2) +, m/z = 176 (M-Si (CH3) 3) + base peak, m/z = 103 (PhCN) +, m/z = 73 (Si (CH3) 3) + 'H NMR spectrum (300 MHz, (CD3) 2SO d6, 5 in ppm):-0. 03 (s: 9H); 0.89 (t, J = 8 Hz: 2H); 3.72 (t, J = 8 Hz: 2H); 5.35 (s: 2H); 7.18 (d, J = 9 Hz: 2H); 7.79 (d, J = 9 Hz: 2H).

(Trimethylsilyl)-2-ethoxymethoxy-4-benzylamine 15.5 cm3 of molar lithium aluminum hydride solution are added, at a temperature in the region of 19°C, to 3. 5 g of (trimethylsilyl)-2-ethoxymethoxy-4-benzonitrile dissolved in 70 cm3 of tetrahydrofuran. The reaction medium is heated and maintained at the reflux point of the tetrahydrofuran for 4 hours. After cooling to a temperature in the region of 19°C, 0. 6cm3 of water is added to the reaction medium, followed by 0.6 cm3 of aqueous 0.5 N sodium hydroxide solution and 1.8 cm3 of water. The suspension obtained is filtered through a sinter funnel and the residue is washed with 5 times 1.8 cm3 of tetrahydrofuran. The organic phase is dried over magnesium sulfate, filtered through a sinter funnel and then evaporated under reduced pressure (2 kPa; 45°C). 3.3 g of (trimethylsilyl)-2- ethoxymethoxy-4-benzylamine are obtained in the form of a yellow oil.

Mass spectrum: El, m/z = 253 M+, m/z = 194 (M-CH3CH20CH2) + base peak, m/z = 180 (M-Si (CH3) 3+, m/z = 73 (Si (CH3) 3) +

'H NMR spectrum (400 MHz, (CD3) 2SO d6, 8 in ppm): 0.00 (s: 9H); 0.90 (t, J = 8 Hz: 2H); 3.66 (s: 2H); 3.71 (t, J = 8 Hz: 2H); 5.20 (s: 2H); 6.95 (broad d, J = 8.5 Hz: 2H); 7.24 (broad d, J = 8.5 Hz: 2H).

N- (4-hydroxybenzyl)-3-oxo-6-pyridin-4-yl-2, 3-dihydropyridazine-4- carboxamide Working as in example 13 for the preparation of ethyl 3- [ (3-oxo-6-pyridin-4-yl-2, 3- dihydropyridazine-4-carbonyl) amino] propionate, but starting with 0.6 g of 3-oxo-6- pyridin-4-yl-2, 3-dihydropyridazine-4-carboxylic acid, 60 cm3 of N, N- dimethylformamide, 0.466 g of 1-hydroxybenzotriazole, 0.91 g of (trimethylsilyl)-2- ethoxymethoxy-4-benzylamine, 0.6 cm3 of N, N-diisopropylethylamine and 1.31 g of 0- (7-azabenzotriazol-1-yl)-N, N, N', N'-tetramethyluronium hexafluorophosphate, and after purification by high performance liquid chromatography on a 100 x 30 mm HyPURITYs 5pm column, eluting with a mixture increasing from 25% to 95% of acetonitrile/water (containing 0.05% trifluoroacetic acid), 0. 16g of N- (4- hydroxybenzyl)-3-oxo-6-pyridin-4-yl-2, 3-dihydropyridazine-4-carboxamide is obtained in the form of a cream-colored solid melting at a temperature above 260°C. oh NMR spectrum (300 MHz, (CD3) 2SO d6, # in ppm): 4.48 (d, J = 6 Hz: 2H); 6.75 (d, J = 8 Hz: 2H); 7.19 (d, J = 8 Hz: 2H); 8.05 (broad d, J = 6 Hz: 2H); 8.69 (s: 1H) ; 8.79 (broad d, J = 6 Hz: 2H); from 9.00 to 9.60 (broad unresolved peak: 1 H) ; 9.74 (t, J = 6 Hz: 1 H); 14.28 (broad s: 1 H).

[M+1] -peak: 323.11 Example 19 4-benzyloxyacetophenone

14.5 cm3 of benzyl bromide and 16.75 g of potassium carbonate are added, at a temperature in the region of 19°C, to 15 g of 4-hydroxyacetophenone dissolved in 180 cm3 of acetone. The reaction medium is heated and maintained at the reflux temperature of the acetone for 4 hours. After cooling to a temperature in the region of 19°C, the reaction medium is suction-filtered through a sinter funnel and the insoluble material is rinsed again with 10 cm3 of acetone. The organic phase is evaporated under reduced pressure (2 kPa ; 45°C) and the solid obtained is dissolved in 300 cm3 of ethyl acetate. The organic solution is washed with twice 100 cm3 of water and then with 100 cm3 of saturated sodium chloride solution. The organic phase is dried over magnesium sulfate, filtered through a sinter funnel and then evaporated under reduced pressure (2 kPa; 45°C). The solid residue is triturated in 20 cm3 of pentane, suction-filtered through a sinter funnel and oven- dried under reduced pressure (10 kPa; 20°C). 23.1 g of 4-benzyloxyacetophenone are obtained in the form of a white solid melting at 99°C.

'H NMR spectrum (300 MHz, (CD3) 2SO d6, 5 in ppm): 2.52 (s: 3H); 5.21 (s: 2H); 7.13 (d, J = 9 Hz: 2H); from 7.30 to 7.55 (mt: 5H); 7.95 (d, J = 9 Hz: 2H).

Diethyl hydroxy [2- (4-benzyloxyphenyl)-2-oxoethyl] malonate

19 cm3 of ethyl ketomalonate and 2.5 cm3 of pyridine are added to 23.1 g of 4- benzyloxyacetophenone. The reaction medium is heated and maintained at reflux for 12 hours. After cooling, the reaction medium is purified by chromatography on silica gel (particle size 40-63pu, under an argon pressure of 150 kPa), eluting with a mixture of dichloromethane and methanol (99/1 by volume). The fractions containing the product are combined and then concentrated under reduced pressure (45°C ; 5 kPa). The product obtained is triturated in 150 cm3 of ethanol, filtered through a sinter funnel, washed with twice 50 cm3 of ethanol and 50 cm3 of isopropyl ether to give, after drying under reduced pressure (2 kPa; 55°C), 5.6 g of diethyl hydroxy [2- (4-benzyloxyphenyl)-2-oxoethyl] malonate melting at 80°C. oh NMR spectrum (300 MHz, (CD3) 2SO d6, 8 in ppm): 1.21 (t, J = 7 Hz: 6H); 3.65 (s: 2H); 4.18 (q, J = 7 Hz: 4H); 5.22 (s: 2H); 6.25 (s: 1H) ; 7.14 (d, J = 9 Hz: 2H); from 7.30 to 7.55 (mt: 5H); 7.94 (d, J = 9 Hz: 2H).

Ethyl 6- [4- (benzyloxy) phenyl]-3-oxo-2, 3-dihydropyridazine-4-carboxylate 1.69 g of hydrazine dihydrochloride are added, at a temperature in the region of 19°C, to 5.6 g of diethyl hydroxy [2- (4-benzyloxyphenyl)-2-oxoethyl] malonate dissolved in 180 cm3 of ethanol. The reaction medium is heated and maintained at reflux for 12 hours. After cooling, the solvent is removed under reduced pressure (2 kPa; 55°C). The solid residue is triturated in 20 cm3 of ethanol, suction-filtered through a sinter funnel and oven-dried under reduced pressure (10 kPa ; 50°C).

3.85 g of ethyl 6- [4- (benzyloxy) phenyl]-3-oxo-2, 3-dihydropyridazine-4-carboxylate are obtained in the form of a green solid melting at 239°C.

'H NMR spectrum (300 MHz, (CD3) 2SO d6, 5 in ppm): 1.32 (t, J = 7 Hz: 3H); 4.32 (q, J = 7 Hz: 2H); 5.19 (s: 2H); 7.14 (d, J = 9 Hz: 2H); from 7.30 to 7.55 (mt: 5H); 7.84 (d, J = 9 Hz: 2H); 8.30 (s: 1H) ; 13.51 (broad s: 1H).

6- [4- (benzyloxy) phenyl]-3-oxo-2, 3,4, 5-tetrahydropyridazine-4-carboxylic acid 33 cm3 of one molar sodium hydroxide solution are added to 3.85 g of ethyl 6- [4- (benzyloxy) phenyl]-3-oxo-2, 3-dihydropyridazine-4-carboxylate. The reaction medium is heated and maintained at reflux for 30 minutes. After cooling, 33 cm3 of one molar hydrochloric acid solution are added.

The suspension obtained is filtered through a sinter funnel and the residue is washed with twice 25 cm3 of water and oven-dried under reduced pressure (10 kPa ; 50°C). 3. 05 g of 6- [4- (benzyloxy) phenyl]-3-oxo-2, 3,4, 5-tetrahydro- pyridazine-4-carboxylic acid are obtained in the form of a yellow solid melting above 260°C.

'H NMR spectrum (300 MHz, (CD3) 2SO d6, 8 in ppm): 5.20 (s: 2H); 7.15 (d, J = 9 Hz: 2H); from 7.30 to 7.55 (mt: 5H); 7.92 (d, J = 9 Hz: 2H); 8.42 (s: 1 H). <BR> <BR> <BR> <BR> <BR> <BR> <P>N- (2, 4-dichlorobenzyl)-3-oxo-6- [4- (benzyloxy) phenyl]-2, 3-dihydropyridazine- 4-carboxamide Working as in example 13 for the preparation of ethyl 3- [ (3-oxo-6-pyridin-4-yl-2, 3- dihydropyridazine-4-carbonyl) amino] propionate, but starting with 1 g of 6- [4- (benzyloxy) phenyl]-3-oxo-2, 3,4, 5-tetrahydropyridazine-4-carboxylic acid, 100 cm3 of N, N-dimethylformamide, 0. 523 g of 1-hydroxybenzotriazole, 0. 56cm3 of 2,4- dichlorobenzylamine, 1.1 cm3 of N, N-diisopropylethylamine and 1. 47 g of 0- (7- azabenzotriazol-1-yl)-N, N, N', N'-tetramethyluronium hexafluorophosphate, 1.02 g of N- (2, 4-dichlorobenzyl)-3-oxo-6- [4- (benzyloxy) phenyl]-2, 3-dihydropyridazine-4- carboxamide are obtained in the form of a yellow solid melting at 225°C.

'H NMR spectrum (300 MHz, (CD3) 2SO d6, 8 in ppm): 4.53 (d, J = 6 Hz: 2H); 5.19 (s: 2H); 7.15 (d, J = 9 Hz: 2H); from 7.30 to 7.55 (mt: 7H); 7.66 (broad s: 1 H) ; 7.86 (d, J = 9 Hz: 2H); 8.47 (s: 1H) ; 10.24 (unresolved peak: 1H) ; from 13.75 to 13.95 (broad unresolved peak: 1 H).

N-benzyl-3-oxo-6- [4- (hydroxy) phenyl]-2, 3-dihydropyridazine-4-carboxamide

0.525 g of ammonium formate and 0.022 g of palladium hydroxide are added to 0.4 g of N- (2, 4-dichlorobenzyl)-3-oxo-6- [4- (benzyloxy) phenyl]-2, 3-dihydropyrida- zine-4-carboxamide dissolved in 10cm3 of methanol. The reaction medium is heated and maintained at reflux for 2 hours. After cooling, the reaction medium is suction-filtered through a sinter funnel and the insoluble material is rinsed again with three times 10 cm3 of hot methanol. The organic phase is evaporated under reduced pressure (2 kPa; 45°C). The residue is recrystallized from methanol. After filtration through a sinter funnel, washing with twice 10 cm3 of methanol and oven- drying under reduced pressure (10kPa ; 50°C), 0. 022 g of N-benzyl-3-oxo-6- [4- (hydroxy) phenyl]-2, 3-dihydropyridazine-4-carboxamide is obtained in the form of a yellow solid melting at a temperature above 260°C. oh NMR spectrum (300 MHz, (CD3) 2SO d6, 8 in ppm): 4.53 (d, J = 6 Hz: 2H); 6.89 (broad d, J = 9 Hz: 2H); from 7.20 to 7.45 (mt: 5H); 7.75 (broad d, J = 9 Hz: 2H); 8.50 (s: 1 H) ; 10.02 (t, J = 6 Hz : 1 H).

[M+1] -peak: 322 <BR> <BR> <BR> <BR> <BR> <BR> N- (2, 4-dichlorobenzyl)-3-oxo-6- [4- (hydroxy) phenyl]-2, 3-dihydropyridazine-4-<BR> <BR> <BR> <BR> carboxamide and N- (2, 4-dichlorobenzyl)-3-oxo-6- [3-benzyl-4-hydroxyphenyl]- 2,3-dihydropyridazine-4-carboxamide 5 cm3 of trifluoroacetic acid are added to 0.4 g of N- (2, 4-dichlorobenzyl)-3-oxo-6- [4- (benzyloxy) phenyl]-2, 3-dihydropyridazine-4-carboxamide. The reaction medium is heated and maintained at reflux for 2 hours. After cooling, the solvent is

removed under reduced pressure (2 kPa; 55°C). The residue is purified by high performance liquid chromatography on a 100 x 30 mm HyPURITY 5 um column, eluting with a mixture increasing from 5% to 95% of acetonitrile/water (containing 0.05% trifluoroacetic acid).

0. 021 g of N- (2, 4-dichlorobenzyl)-3-oxo-6- [4- (hydroxy) phenyl]-2, 3-dihydropyri- dazine-4-carboxamide is obtained in the form of a yellow solid melting at a temperature above 260°C. oh NMR spectrum (300 MHz, (CD3) 2SO d6, 8 in ppm): 4.63 (d, J = 6 Hz: 2H); 6.88 (d, J = 8 Hz: 2H); 7.45 (s: 2H); 7.65 (s: 1H) ; 7.75 (d, J = 8 Hz: 2H); 8.47 (s: 1H) ; 9.90 (unresolved peak: 1H) ; 10.11 (broad t, J = 6 Hz : 1H) ; 13.78 (broad unresolved peak: 1 H).

0.040 g of N- (2, 4-dichlorobenzyl)-3-oxo-6- [3-benzyl-4-hydroxyphenyl]-2, 3-dihydro- pyridazine-4-carboxamide is also obtained, in the form of a yellow solid melting at a temperature in the region of 270°C.

'H NMR spectrum (300 MHz, (CD3) 2SO d6, 6 in ppm): 3.95 (s: 2H); 4.62 (d, J = 6 Hz: 2H); 6.94 (d, J = 8.5 Hz: 1H) ; from 7.10 to 7.35 (mt: 5H); 7.44 (mt: 2H); 7.60 (dd, J = 8.5 and 2 Hz: 1H) ; 7.65 (mt: 2H); 8.45 (s: 1H) ; 9.95 (broad s: 1H) ; 10.07 (broad t, J = 6 Hz: 1 H); 13.81 (unresolved peak: 1 H).

Example 20 Diethyl hydroxy (pyridin-2-oxoethyl) malonate Working as in example 19 for the preparation of diethyl hydroxy [2- (4- benzyloxyphenyl)-2-oxoethyl] malonate, but starting with 13 cm3 of 2- acetylpyridine, 21 cm3 of ethyl ketomalonate and 2.5 cm3 of pyridine, and after

purification by chromatography on silica gel (particle size 40-63 µm, under an argon pressure of 150 kPa), eluting with dichloromethane, 31. 1 g of diethyl hydroxy (pyridin-2-oxoethyl) malonate are obtained in the form of a brown oil.

'H NMR spectrum (300 MHz, (CD3) 2SO d6, 8 in ppm): 1.20 (t, J = 7 Hz: 6H); 3.90 (s: 2H); 4.19 (q, J = 7 Hz: 4H); 6.38 (s: 1 H) ; 7.71 (ddd, J = 7.5-5 and 1.5 Hz: 1 H) ; 7.97 (broad d, J = 7.5 Hz: 1H) ; 8.04 (resolved t, J = 7.5 and 1.5 Hz: 1H) ; 8.76 (broad d, J = 5 Hz : 1 H).

Ethyl 6-pyridin-2-yl-3-oxo-2, 3-dihydropyridazine-4-carboxylate Working as in example 19 for the preparation of ethyl 6- [4- (benzyloxy) phenyl]-3- oxo-2, 3-dihydropyridazine-4-carboxylate, but starting with 31. 1 g of diethyl hydroxy (pyridin-2-oxoethyl) malonate, 11. 55 g of hydrazine dihydrochloride and 700 cm3 of ethanol, and after purification by chromatography on silica gel (particle size 40-63 um, under an argon pressure of 150 kPa), eluting with dichloromethane, followed by recrystallization from ethanol, 6.9 g of ethyl 6- pyridin-2-yl-3-oxo-2, 3-dihydropyridazine-4-carboxylate are obtained in the form of a yellow solid melting at 182°C.

'H NMR spectrum (300 MHz, (CD3) 2SO d6, 8 in ppm): 1.33 (t, J = 7 Hz: 3H); 4.33 (q, J = 7 Hz: 2H); 7.50 (ddd, J = 8-5 and 1.5 Hz: 1 H); 7.97 (resolved t, J = 8 and 2 Hz: 1 H); 8.08 (broad d, J = 8 Hz: 1 H); 8.67 (s: 1 H); 8.70 (ddd, J = 5-2 and 1.5 Hz: 1 H) ; 13.72 (broad s : 1 H).

6-pyridin-2-yl-3-oxo-2, 3,4, 5-tetrahydropyridazine-4-carboxylic acid

Working as in example 19 for the preparation of 6- [4- (benzyloxy) phenyl]-3-oxo- 2,3, 4, 5-tetrahydropyridazine-4-carboxylic acid, but starting with 4 g of ethyl 6- pyridin-2-yl-3-oxo-2, 3-dihydropyridazine-4-carboxylate, 49 cm3 of one molar sodium hydroxide solution and 50 cm3 of one molar hydrochloric acid solution, 3. 44 g of 6-pyridin-2-yl-3-oxo-2, 3,4, 5-tetrahydropyridazine-4-carboxylic acid are obtained in the form of a beige-colored solid melting at a temperature above 260°C.

'H NMR spectrum (300 MHz, (CD3) 2SO d6, 8 in ppm): 7.53 (broad dd, J = 7.5 and 5 Hz: 1 H); 7.99 (resolved t, J = 7.5 and 1.5 Hz: 1 H); 8.13 (broad d, J = 7. 5 Hz: 1 H); 8.72 (broad d, J = 5 Hz: 1H) ; 8.83 (s: 1H) ; from 13.55 to 14.30 (unresolved peak: 2H).

N-(2, 4-dichlorobenzyl)-3-oxo-6-pyridin-2-yl-2, 3-dihydropyridazine-4- carboxamide Working as in example 2 for the preparation of N- (2, 4-dichlorobenzyl)-3-oxo-6- pyridin-4-yl-2, 3-dihydropyridazine-4-carboxamide, but starting with 0.3 g of 3-oxo- 6-pyridin-2-yl-2, 3-dihydropyridazine-4-carboxylic acid, 10 cm3 of dichloromethane, 1 cm3 of dimethylformamide, 0. 12 cm3 of oxalyl chloride, 0. 21 cm3 of 2,4- dichlorobenzylamine and 0.22 cm3 of triethylamine, 0.22 g of N- (2, 4- dichlorobenzyl)-3-oxo-6-pyridin-2-yl-2, 3-dihydropyridazine-4-carboxamide is

obtained in the form of a cream-colored solid melting at a temperature above 260°C. oh NMR spectrum (300 MHz, (CD3) 2SO d6, 8 in ppm): 4.65 (d, J = 6 Hz: 2H); 7.46 (s: 2H); 7.55 (broad dd, J = 8 and 5 Hz: 1H) ; 7.67 (broad s: 1H) ; 8.31 (ddd, J = 8- 2.5 and 2 Hz: 1H) ; 8.59 (s: 1H) ; 8.68 (dd, J = 5 and 2 Hz: 1H) ; 9.10 (broad d, J = 2.5 Hz: 1 H); 10.09 (t, J = 6 Hz: 1 H).

[M+1] -peak: 375 Example 21 Diethyl hydroxy (pyridin-3-oxoethyl) malonate Working as in example 19 for the preparation of diethyl hydroxy [2- (4- benzyloxyphenyl)-2-oxoethyl] malonate, but starting with 8 cm3 of 3-acetylpyridine, 14 cm3 of ethyl ketomalonate and 2cm3 of pyridine, and after purification by chromatography on silica gel (particle size 40-63 µm, under an argon pressure of 150 kPa), eluting with dichloromethane, 8. 85 g of diethyl hydroxy (pyridin-3- oxoethyl) malonate are obtained in the form of a brown oil.

'H NMR spectrum (300 MHz, (CD3) 2SO d6, # in ppm): 1.21 (t, J = 7 Hz: 6H); 3.76 (s: 2H); 4.20 (q, J = 7 Hz: 4H); 6.44 (s: 1H) ; 7.59 (broad dd, J = 8 and 5 Hz: 1H) ; 8.31 (ddd, J = 8-2.5 and 2 Hz: 1 H) ; 8.83 (dd, J = 5 and 2 Hz: 1 H) ; 9.12 (broad d, J = 2. 5 Hz : 1 H).

Ethyl 6-pyridin-3-yl-3-oxo-2, 3-dihydropyridazine-4-carboxylate

Working as in example 19 for the preparation of ethyl 6- [4- (benzyloxy) phenyl]-3- oxo-2, 3-dihydropyridazine-4-carboxylate, but starting with 8. 85 g of diethyl hydroxy (pyridin-3-oxoethyl) malonate, 3.67 g of hydrazine dihydrochloride and 250 cm3 of ethanol, and after recrystallization from ethanol, 3.6 g of ethyl 6-pyridin- 3-yl-3-oxo-2, 3-dihydropyridazine-4-carboxylate are obtained in the form of a green solid melting at a temperature in the region of 150°C. oh NMR spectrum (300 MHz, (CD3) 2SO d6, 8 in ppm): 1.33 (t, J = 7 Hz: 3H); 4.34 (q, J = 7 Hz: 2H); 7.54 (broad dd, J = 8 and 5 Hz: 1 H); 8.28 (ddd, J = 8-2.5 and 2 Hz: 1H) ; 8.41 (s: 1H) ; 8.67 (dd, J = 5 and 2 Hz: 1H) ; 9.09 (broad d, J = 2.5 Hz: 1 H) ; 13.75 (unresolved peak: 1 H).

6-pyridin-3-yl-3-oxo-2, 3,4, 5-tetrahydropyridazine-4-carboxylic acid Working as in example 19 for the preparation of 6- [4- (benzyloxy) phenyl]-3-oxo- 2,3, 4, 5-tetrahydropyridazine-4-carboxylic acid, but starting with 2 g of ethyl 6- pyridin-3-yl-3-oxo-2, 3-dihydropyridazine-4-carboxylate, 24.5 cm3 of one molar sodium hydroxide solution and 25 cm3 of one molar hydrochloric acid solution, 1. 65 g of 6-pyridin-3-yl-3-oxo-2, 3,4, 5-tetrahydropyridazine-4-carboxylic acid are obtained in the form of a cream-colored solid melting at a temperature above 260°C.

'H NMR spectrum (300 MHz, (CD3) 2SO d6, 8 in ppm): 7.55 (broad dd, J = 8 and 5 Hz: 1H) ; 8.33 (ddd, J = 8-2.5 and 2 Hz: 1H) ; 8.56 (s: 1H) ; 8.68 (dd, J = 5 and 2 Hz: 1H) ; 9.12 (broad d, J = 2.5 Hz: 1H) ; from 13.50 to 14.80 (very broad unresolved peak: 2H).

N-(2, 4-dichlorobenzyl)-3-oxo-6-pyridin-3-yl-2, 3-dihydropyridazine-4- carboxamide Working as in example 2 for the preparation of N- (2, 4-dichlorobenzyl)-3-oxo-6- pyridin-4-yl-2, 3-dihydropyridazine-4-carboxamide, but starting with 0.3 g of 3-oxo- 6-pyridin-3-yl-2, 3-dihydropyridazine-4-carboxylic acid, 10 cm3 of dichloromethane, 1 cm3 of dimethylformamide, 0. 12cm3 of oxalyl chloride, 0.21 cm3 of 2,4- dichlorobenzylamine and 0.22 cm3 of triethylamine, and after purification by chromatography on silica gel (particle size 40-63 um, under an argon pressure of 150 kPa), eluting with a mixture of dichloromethane and methanol (90/10 by volume), 0.204 g of N-(2, 4-dichlorobenzyl)-3-oxo-6-pyridin-3-yl-2, 3-dihydro- pyridazine-4-carboxamide is obtained in the form of a cream-colored solid melting at a temperature in the region of 260°C.

'H NMR spectrum (300 MHz, (CD3) 2SO d6, 8 in ppm): 4.65 (d, J = 6 Hz: 2H); 7.46 (s: 2H); 7.55 (broad dd, J = 8 and 5 Hz: 1 H) ; 7.67 (broad s: 1 H) ; 8.31 (ddd, J = 8- 2.5 and 2 Hz: 1H) ; 8.59 (s: 1H) ; 8.68 (dd, J = 5 and 2 Hz: 1H) ; 9.10 (broad d, J = 2.5 Hz: 1H) ; 10.09 (t, J = 6 Hz: 1H).

[M+1] -peak: 375 If not stated otherwise, the examples listed in the following table are synthesized according to the above-mentioned methods. Example structural formula name M+1 peak synthesis according to example 22 coo N- (2, 4-Dichtorbenzy))-3-oxo-6- [4- 390 13 (hydroxy) phenyl]-2, 3-dihydropyridazine-4- 'N carboxylic acid QH 23 BL o R-3-Oxo-6-pyridin-4-yl-2, 3-dihydro-355, 09 13 IN4NH pyridazine-4-carboxylic acid [1- (4-chloro- N phenyl)-ethyl]-amide t ua 24 ° ° 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 388, 13 13 4-carboxylic acid (5-methyl-3-phenyl- Nf t-NO isoxazol-4-ylmethyl)-amide v i 25 S-3-Oxo-6-pyridin-4-yl-2, 3-dihydro-355, 09 13 IN4NH pyridazine-4-carboxylic acid [1- (4-chloro- phenyl)-ethyl]-amide t a 26 o o 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 389, 05 13 4-carboxylic acid [1- (2, 4-dichloro-phenyl)- N I ethyl]-amide ° Example structural formula name M+1 peak synthesis according to example 27"3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 390, 19 13 , N 4-carboxylic acid (1-benzyl-piperidin-4-yl)- i amide zon 28 OH 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine-315, 14 13 4-carboxylic acid (4-hydroxy-cyclohexyl)- "amide if 29 0 0 6- (4-Methoxy-phenyi)-3-oxo-2, 3-dihydro- 365, 15 13 pyridazine-4-carboxylic acid (3-pyridin-3-yl- propyl)-amide Cl-I 30 0 0 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 344, 2 13 4-carboxylic acid (2-diisopropylamino-ethyl)- N amide ' 31 0 0 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 289, 12 13 Ni 4-carboxylic acid (4-hydroxy-butyl)-amide t% H Oi Example structural formula name M+1 peak synthesis according to example 32 4- (f [6- (4-Hydroxy-3, 5-dimethyl-phenyl)-3- 394, 13 13 oxo-2, 3-dihydro-pyridazine-4-carbonyl]- amino}-methyl)-benzoic acid O HH 1C0 A CH 33 O O 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine-433, 19 13 4-carboxylic acid 4- (4-methyl-piperazine-1- N carbonyl)-benzylamide ; compound with trifluoro-acetic acid 34 O 6-(2-Methylamino-pyrimidin-4-yl)-3-oxo-2, 3-371, 1 13 dihydro-pyridazine-4-carboxylic acid 4- / 0 chloro-benzylamide / Example structural formula name M+1 peak synthesis according to example 35 0 0 4- [ (3-Oxo-6-pyridin-4-yi-2, 3-dihydro- 400, 19 13 NH pyridazine-4-carbonyl)-amino]-piperidine-1- carboxylic acid ter-butyl ester (ii" S 36 0 0 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 299, 14 13 t 4-carboxylic acid cyclohexylamide iSi 6 S, S-3-Oxo-6-pyridin-4-yl-2, 3-dihydro- 405, 19 13 pyridazine-4-carboxylic acid (2-benzyloxy- cyclohexyl)-amide C 38 R, R-3-Oxo-6-pyridin-4-yl-2, 3-d ihydro-405, 19 13 pyridazine-4-carboxylic acid (2-benzyloxy- cyclohexyl)-amide y 39 0 0 3-Oxo-6- (1 H-pyrazol-4-yl)-2, 3-dihydro- 330, 07 41 pyridazine-4-carboxylic acid 4-chloro- Nf WC benzylamide N H-N Example structural formula name M+1 peak synthesis according to example 40 0 0 6- (4-Hydroxy-phenyl)-3-oxo-2, 3-dihydro- 356, 07 41 4 pyridazine-4-carboxylic acid 4-chloro- N benzylamide 41 0 0 6- (4-Hydroxy-3-methoxy-phenyl)-3-oxo-2, 3- 386, 08 description of dihydro-pyridazine-4-carboxylic acid 4-synthesis at the end N chloro-benzylamide of this table I 42 0 0 6- (3-Chloro-pyridin-4-yl)-3-oxo-2, 3-dihydro- 375, 03 41 pyridazine-4-carboxylic acid 4-chloro- 0 benzylamide 43 _ 6-Chloro-3-oxo-2, 3-dihydro-pyridazine-4-298, 01 13 Hl carboxylic acid 4-chloro-benzylamide Nez I\ l OH Example structural formula name M+1 peak synthesis according to example 44 O O 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 273, 13 13 4-carboxylic acid tert-butylamide O 45 O O 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine-314, 15 13 4-carboxylic acid (1-methyl-piperidin-4-yl)- N amide N 46 OK 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine-328, 13 13 ICNH o 4-carboxylic acid (2-oxo-azepan-3-yl)-amide i b fl" 4 ° ° 4- [ (3-Oxo-6-pyridin-4-yl-2, 3-dihydro- 372, 16 13 pyridazine-4-carbonyl)-amino]-piperidine-1- carboxylic acid ethyl ester AO J 48 O O 6-(4-Hydroxy-3, 5-dimethyl-phenyl)-3-oxo-379, 17 13 2, 3-dihydro-pyridazine-4-carboxylic acid (3- pyridin-3-yl-propyl)-amide CH Example structural formula name M+1 peak synthesis according to example 49 O O 6-(4-Hydroxy-3-methoxy-phenyl)-3-oxo-2, 3-381, 15 13 @< dihydro-pyridazine-4-carboxylic acid (3- pyridin-3-yl-propyl)-amide OH 50 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 429, 05 13 1 0 4-carboxylic acid [2- (3-bromo-4-methoxy- phenyl)-ethyl]-amide ; compound with trifluoro-acetic acid 51 0 0 6- (4-METHOXY-PHENYL)-3-OXO-2, 3- 370, 09 41 DIHYDRO-PYRIDAZINE-4-CARBOXYLIC N a ACID 4-CHLORO-BENZYLAMIDE 52 0 0 6- (4-Hydroxy-3, 5-dimethyl-phenyl)-3-oxo- 384, 1 41 2, 3-dihydro-pyridazine-4-carboxylic acid 4- chloro-benzylamide ci 53 0 0 6- (3-Hydroxy-phenyl)-3-oxo-2, 3-dihydro- 356, 07 41 pyridazine-4-carboxylic acid 4-chloro- benzylamide Example structural formula name M+1 peak synthesis according to example 54 H o 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine-259, 11 13 4-carboxylic acid propylamide ; compound with trifluoro-acetic acid WN K 55 H o 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine-322, 12 13 4-carboxylic acid (2-pyridin-3-yl-ethyl)- amide ; compound with trifluoro-acetic acid N 56 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 322, 12 13 1N 0 4-carboxylic acid (2-pyridin-2-yl-ethyl)- amide ; compound with trifluoro-acetic acid N 57 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine-289, 12 13 4-carboxylic acid (2-ethoxy-ethyl)-amide ; compound with trifluoro-acetic acid 0 N 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 275, 11 13 4-carboxylic acid (2-methoxy-ethyl)-amide ; 0 ; compound with trifluoro-acetic acid Ht+ çN Example structural formula name M+1 peak synthesis according to example 59 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 323, 12 13 4-carboxylic acid (5-methyl-pyrazin-2- 0 ylmethyl)-amide ; compound with trifluor- acetic acid \ IN 60 H 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 271, 11 13 °lX 4-carboxylic acid cyclopropylmethyl-amide ; compound with trifluoro-acetic acid tN 61 3 301, 12 13 0 4-carboxylic acid [(R)-1-(tetrahydro-furan-2- yl) methyl]-amide ; compound with trifluor- acetic acid bv 62 H o 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine-257, 1 13 4-carboxylic acid cyclopropylamide ; compound with trifluoro-acetic acid < 63 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 271, 11 13 4-carboxylic acid cyclobutylamide ; O compound with trifluoro-acetic acid IN N Example structural formula name M+1 peak synthesis according to example 64 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 347, 12 13 4-carboxylic acid (1 H-benzoimidazol-2- N ylmethyl)-amide ; compound with trifluor- O I \N acetic acid N d , \N 65 H 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 287, 14 13 4-carboxylic acid (3-methyl-butyl)-amide ; compound with trifluoro-acetic acid t 66 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 335, 14 13 4-carboxylic acid (3-phenyl-propyl)-amide ; °< ? compound with trifluoro-acetic acid N 67 CH-AL 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 399, 04 13 H S 4-carboxylic acid [(R)-1-(4-bromo-phenyl)- ethyl]-amide ; compound with trifluoro-acetic Hk N » 9 acid FN, 68 H 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 335, 14 13 4-carboxylic acid (2-o-tolyl-ethyl)-amide ; compound with trifluoro-acetic acid M' N Example structural formula name M+1 peak synthesis according to example 69 3-0xo-6-pyridin-4-yi-2, 3-dihydro-pyridazine- 351, 14 13 h 4-carboxylic acid [2- (2-methoxy-phenyl)- ethyl]-amide ; compound with trifluoro-acetic fun, acid 70 H 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 351, 14 13 4-carboxylic acid [2- (3-methoxy-phenyl)- HK ethyl]-amide ; compound with trifluoro-acetic acid 71 H 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine-337, 12 13 4-carboxylic acid [2- (3-hydroxy-phenyl)- ethyl]-amide ; compound with trifluoro-acetic IN acid 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 4-carboxylic acid [2- (4-bromo-phenyl)-ethyl]- amide ; compound with trifluoro-acetic acid ÇN 73 H O 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine-351, 14 13 4-carboxylic acid [2- (4-methoxy-phenyl)- ethyl]-amide ; compound with trifluoro-acetic acid Example structural formula name M+1 peak synthesis according to example 74 H 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine-337, 12 13 4-carboxylic acid [2- (4-hydroxy-phenyl)- ethyl]-amide ; compound with trifluoro-acetic avid \ N acid 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 385, 02 13 4-carboxylic acid 4-bromo-benzylamide ; compound with trifluoro-acetic acid FK, 76 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 337, 12 13 0 4-carboxylic acid (2-phenoxy-ethyl)-amide ; compound with trifluoro-acetic acid \ N WN 77 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 335, 14 13 " 4-carboxylic acid 2, 4-dimethyl-benzylamide ; °t% compound with trifluoro-acetic acid N N Example structural formula name M+1 peak synthesis according to exam le 78 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine-321, 13 13 4-carboxylic acid 2-methyl-benzylamide ; compound with trifluoro-acetic acid 0 Im, 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 337, 12 13 4-carboxylic acid 2-methoxy-benzylamide ; compound with trifluoro-acetic acid t0 m. o 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 335, 14 13 4-carboxylic acid 3, 4-dimethyl-benzylamide ; compound with trifluoro-acetic acid H H 0 Example structural formula name M+1 peak synthesis according to example 81 3-Oxo-6-pyridin-4-yi-2, 3-dihydro-pyridazine- 335, 14 13 4-carboxylic acid 3, 5-dimethyl-benzylamide ; compound with trifluoro-acetic acid 0 W. 0 A 82 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 321, 13 13 4-carboxylic acid 4-methyl-benzylamide ; compound with trifluoro-acetic acid 0 W t E 83 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 337, 12 13 4-carboxylic acid 4-methoxy-benzylamide ; compound with trifluoro-acetic acid N, o 'i 84 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 351, 1 13 4-carboxylic acid (benzo [1, 3] dioxol-5- ylmethyl)-amide ; compound with trifluor- acetic acid u Example structural formula name M+1 peak synthesis according to example 85 H 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 311, 11 13 0 4-carboxylic acid (5-methyl-furan-2- °t'% ylmethyl)-amide ; compound with trifluoro- FN, acetic acid n 86 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine-297, 09 13 H ° 4-carboxylic acid (furan-2-ylmethyl)-amide ; XN compound with trifluoro-acetic acid zu 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 313, 16 13 4-carboxylic acid cyclohexylmethyl-amide ; compound with trifluoro-acetic acid Oqr NH HS O 6 88 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 333, 13 13 4-carboxylic acid ( (1 S, 2R)-2-phenyl- cyclopropyl)-amide ; compound with trifluor- y. N acetic acid NHo N r, N 0 H Example structural formula name M+1 peak synthesis according to example 89 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 313, 16 13 4-carboxylic acid (4-methyl-cyclohexyl)- amide ; compound with trifluoro-acetic acid 0 lw 0 90 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 285, 13 13 4-carboxylic acid cyclopentylamide ; OX compound with trifluoro-acetic acid HNste T 91 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 333, 13 13 4-carboxylic acid indan-2-ylamide ; compound with trifluoro-acetic acid 0 lw cY"'0 92 H 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine-374, 15 13 4-carboxylic acid [2- (5-methyl-1 H-indol-3-yl)- ethyl]-amide ; compound with trifluoro-acetic acid Example structural formula name M+1 peak synthesis according to example 93 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 403, 01 13 4-carboxylic acid 3-bromo-4-fluoro- N benzylamide ; compound with trifluoro-acetic acid F F O+, NH a c i d HS O 94 H (T t t M > 3 89, 05 13 4-carboxylic acid [2- (3, 4-dichloro-phenyl)- ethyl]-amide ; compound with trifluoro-acetic IN acid \ IN acid 95 H o 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine-361, 13 13 "Wi 0 4-carboxylic acid [2- (1 H-benzoimidazol-2- < ide N 96 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 390, 15 13 4-carboxylic acid [2- (6-methoxy-1 H-indol-3- olzq yl)-ethyl]-amide ; compound with trifluor- acetic acid \ N 97 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 360, 14 13 4-carboxylic acid [2- (1 H-indol-3-yl)-ethyl]- amide ; compound with trifluor v i I zain Example structural formula name M+1 peak synthesis according to Example 98 3-Oxo-6-pyridin-4-yi-2, 3-dihydro- 385, 09 13 pyridazine-4-carboxylic acid 4- methanesulfonyl-benzylamide ; compound with trifluoro-acetic acid Ni 0 0=9 : =o 99 5 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-291, 08 pyridazine-4-carboxylic acid (2- ° methylsulfanyl-ethyl)-amide ; compound with trifluoro-acetic acid 100 3-Oxo-6-pyridin-4-yl-2, 3-dihydro- 327, 08 13 pyridazine-4-carboxylic acid (2-thiophen-2- yl-ethyl)-amide ; compound with trifluor- acetic acid °A 101 H o 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-389, 05 13 0 pyridazine-4-carboxylic acid [2- (2, 4- dichloro-phenyl)-ethyl]-amide ; compound with trifluoro-acetic acid Example structural formula name M+1 peak synthesis according to Example 102 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-375, 03 13 pyridazine-4-carboxylic acid 2, 3-dichloro- AN benzylamide ; compound with trifluor- acetic acid ß Y3 0 103 a H 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-355, 09 13 0 pyridazine-4-carboxylic acid [2- (2-chloro- wv ov phenyl)-ethyl]-amide ; compound with trifluoro-acetic acid 104 3-Oxo-6-pyridin-4-yl-2, 3-dihydro- 355, 09 13 pyridazine-4-carboxylic acid 4-chloro-2- methyl-benzylamide ; compound with trifluoro-acetic acid NH O Q 105 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-355, 09 13 pyridazine-4-carboxylic acid 5-chloro-2- methyl-benzylamide ; compound with N trifluoro-acetic acid ' \ N Example structural formula name M+1 peak synthesis according to Example 106 3-Oxo-6-pyridin-4-yl-2, 3-dihydro- 355, 09 13 pyridazine-4-carboxylic acid [1- (4-chloro- NC O > phenyl)-ethyl]-amide ; compound with trifluoro-acetic acid 107 H o 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-369, 1 13 <4 pyridazine-4-carboxylic acid [2- (4-chloro- phenyl)-1-methyl-ethyl]-amide ; compound with trifluoro-acetic acid 108 H 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-355, 09 13 <4 pyridazine-4-carboxylic acid [2- (4-chloro- HNs phenyl)-ethyl]-amide ; compound with N trifluoro-acetic acid 109"° 3-Oxo-6-pyridin-4-yl-2, 3-dihydro- 394, 1 13 pyridazine-4-carboxylic acid [2- (5-chloro- 1 H-indol-3-yl)-ethyl]-amide ; compound with O N trifluoro-acetic acid 110 F F"3-Oxo-6-pyridin-4-yl-2, 3-dihydro- 389, 12 13 ° pyridazine-4-carboxylic acid [2- (3- wo trifluoromethyl-phenyl)-ethyl]-amide ; compound with trifluoro-acetic acid N t Example structural formula name M+1 peak synthesis according to Example 3-Oxo-6-pyridin-4-yl-2, 3-dihydro- 375, 1 13 pyridazine-4-carboxylic acid 3- N trifluoromethyl-benzylamide ; compound with trifluoro-acetic acid 0 'i F 112 3-Oxo-6-pyridin-4-yl-2, 3-dihydro- 375, 1 13 pyridazine-4-carboxylic acid 4- trifluoromethyl-benzylamide ; compound with trifluoro-acetic acid KNH O ___ F F F 113 2 H 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-391, 09 13 pyridazine-4-carboxylic acid 2- trifluoromethoxy-benzylamide ; compound F H9sX with trifluoro-acetic acid N 114 3-Oxo-6-pyridin-4-yl-2, 3-dihydro- 391, 09 13 pyridazine-4-carboxylic acid 3- trifluoromethoxy-benzylamide ; compound F with trifluoro-acetic acid \ N Example structural formula name M+1 peak synthesis according to Example 115 3-Oxo-6-pyridin-4-yl-2, 3-dihydro- 343, 09 13 pyridazine-4-carboxylic acid 3, 4-difluoro- N benzylamide ; compound with trifluor- acetic acid 0 F 116 a 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-359, 06 13 , HN o pyridazine-4-carboxylic acid 4-chloro-2- F 0 fluoro-benzylamide ; compound with trifluoro-acetic acid \ ion 117 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-343, 09 13 pyridazine-4-carboxylic acid 2, 4-difluoro- N benzylamide ; compound with trifluor- acetic acid 1- 0 F F 1 H 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-339, 12 13 pyridazine-4-carboxylic acid [2- (2-fluoro- phenyl)-ethyl]-am ide ; compound with trifluoro-acetic acid Example structural formula name M+1 peak synthesis according to Example 119 3-Oxo-6-pyridin-4-yl-2, 3-dihydro- 359, 06 13 pyridazine-4-carboxylic acid 2-chloro-4- N fluoro-benzylamide ; compound with trifluoro-acetic acid ni ° °' i F 120 F 3-Oxo-6-pyridin-4-yl-2, 3-dihydro- 343, 09 13 pyridazine-4-carboxylic acid 3, 5-difluoro- benzylamide ; compound with trifluor- 0 acetic acid N \ N 121 H 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-339, 12 13 ° pyridazine-4-carboxylic acid [2- (3-fluoro- phenyl)-ethyl]-amide ; compound with ON trifluoro-acetic acid 122 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-325, 1 13 pyridazine-4-carboxylic acid 3-fluor- N benzylamide ; compound with trifluor- acetic acid Zozo zu Example structural formula name M+1 peak synthesis according to Example 123 3-Oxo-6-pyrid in-4-yl-2, 3-dihydro-339, 12 13 pyridazine-4-carboxylic acid [1- (4-fluoro- HSo4O phenyl)-ethyl]-amide ; compound with trifluoro-acetic acid \ N 124 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-339, 12 13 ° pyridazine-4-carboxylic acid [2- (4-fluoro- D phenyl)-ethyl]-amide ; compound with nN trifluoro-acetic acid 125 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-325, 1 13 pyridazine-4-carboxylic acid 4-fluor- N benzylamide ; compound with trifluor- acetic acid ni O F 126 HO 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-289, 12 13 -4-carboxylic acid (2-hydroxy- 1, 1-dimethyl-ethyl)-amide ; compound with trifluoro-acetic acid "Tit '" Example structural formula name M+1 peak synthesis according to Example 127 3-Oxo-6-pyridin-4-yl-2, 3-dihydro- 429, 05 13 H 0 pyridazine-4-carboxylic acid [2- (5-bromo-2- 9 qA methoxy-phenyl)-ethyl]-amide ; compound with trifluoro-acetic acid ka 128 s 3-Oxo-6-pyridin-4-yl-2, 3-d ihydro-335, 14 13 pyridazine-4-carboxylic acid ((R)-1-phenyl- Y propyl)-amide ; compound with trifluor- acetic acid 129 3-Oxo-6-pyridin-4-yl-2, 3-dihyd ro-289, 12 13 pyridazine-4-carboxylic acid ( (S)-2- ° \ methoxy-1-methyl-ethyl)-amide ; compound with trifluoro-acetic acid \ N 130 s 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-351, 14 13 pyridazine-4-carboxylic acid [ (R)-1- (3- o methoxy-phenyl)-ethyl]-amide ; compound with trifluoro-acetic acid HNs \ N 131 ov 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-335, 14 13 NH O pyridazine-4-carboxylic acid ((R)-1-p-tolyl- ethyl)-amide ; compound with trifluor- ° acetic acid Example structural formula name M+1 peak synthesis according to Example 132 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-263, 09 13 pyridazine-4-carboxylic acid (2-fluor- ho ethyl)-amide ; compound with trifluor- acetic acid HNFtBN '1333-0xo-6-pyridin-4-y !-2, 3-dihydro-321, 1313 pyridazine-4-carboxylic acid ((R)-1-phenyl- 0 ethyl)-amide ; compound with trifluor- acetic acid \ N 134 oK 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-371, 14 13 i pyridazine-4-carboxylic acid ((R)-1- f naphthalen-2-yl-ethyl)-amide ; compound with trifluoro-acetic acid 'I \ N i 135 3-Oxo-6-pyridin-4-yl-2, 3-dihydro- 299, 14 13 pyridazine-4-carboxylic acid N cyclohexylamide ; compound with trifluor- acetic acid 1, 40 Example structural formula name M+1 peak synthesis according to Example 136 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-337, 12 13 two pyridazine-4-carboxylic acid ( (S)-2- I-ly hydroxy-1-phenyl-ethyl)-amide ; compound with trifluoro-acetic acid M'i çN 137 3-Oxo-6-pyridin-4-yl-2, 3-dihydro- 373, 1 13 pyridazine-4-carboxylic acid [2- (3, 4- difluoro-phenoxy)-ethyl]-amide ; compound with trifluoro-acetic acid "'in 0 S { 138 3-Oxo-6-pyridin-4-yi-2, 3-dihydro- 379, 17 13 pyridazine-4-carboxylic acid 4-butoxy- N benzylamide ; compound with trifluor- acetic acid zozo Example structural formula name M+1 peak synthesis according to Example 139 3-Oxo-6-pyridin-4-yl-2, 3-dihydro- 327, 08 13 pyridazine-4-carboxylic acid (5-methyl- thiophen-2-ylmethyl)-amide ; compound -acetic acid H9 \ N 140 s 3-Oxo-6-pyridin-4-yl-2, 3-dihydro- 327, 08 13 pyridazine-4-carboxylic acid (1-thiophen-2- yl-ethyl)-amide ; compound with trifluor- acetic acid 141 3-Oxo-6-pyridin-4-yl-2, 3-dihydro- 327, 08 13 pyridazine-4-carboxylic acid (3-methyl- ° thiophen-2-ylmethyl)-amide ; compound XN with trifluoro-acetic acid FK, 142 a 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-347X03 13 pyridazine-4-carboxylic acid (5-chloro- 1 thiophen-2-ylmethyl)-amide ; compound with trifluoro-acetic acid Example structural formula name M+1 peak synthesis according to Example 143 3-Oxo-6-pyridin-4-yl-2, 3-dihydro- 341, 1 13 pyridazine-4-carboxylic acid (5-ethyl- o thiophen-2-ylmethyl)-amide ; compound -acetic acid HNs tN 144 1- [ (3-Oxo-6-pyridin-4-yl-2, 3-dihydro- 433, 18 13 pyridazine-4-carbonyl)-amino]-indan-5- N carboxylic acid butyl ester ; compound with trifluoro-acetic acid ni o 0 145 3-Oxo-6-pyridin-4-yl-2, 3-d ihydro-399, 04 13 pyridazine-4-carboxylic acid [2- (3-bromo- 4 phenyl)-ethyl]-amide ; compound with trifluoro-acetic acid 146 H 3-Oxo-6-pyridin-4-yl-2, 3-dihyd ro-348, 14 13 pyridazine-4-carboxylic acid (1, 2, 3, 4- 0 O tetrahydro-quinolin-4-yl)-amide ; compound with trifluoro-acetic acid IN Example structural formula name M+1 peak synthesis according to Example 147 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-407, 2 13 0 pyridazine-4-carboxylic acid [2-ethyl-2- (3- ; methoxy-phenyl)-butyl]-amide ; compound with trifluoro-acetic acid tN 148 H 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-358, 18 13 pyridazine-4-carboxylic acid (3-morpholin- 4-yl-butyl)-amide ; compound with trifluor- acetic acid 149 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-388, 17 13 H pyridazine-4-carboxylic acid [2- (1 H-indol-3- yl)-1, 1-dimethyl-ethyl]-amide ; compound °t » with trifluoro-acetic acid N 150 3-Oxo-6-pyridin-4-yl-2, 3-dihydro- 390, 15 13 H pyridazine-4-carboxylic acid [2- (5-methoxy- ° 1 H-indol-3-yl)-ethyl]-amide ; compound with H trifilioro-acetic acid \ N Example structural formula name M+1 peak synthesis according to Example 151 3-Oxo-6-pyridin-4-yl-2, 3-dihydro- 359, 06 13 pyridazine-4-carboxylic acid 3-chloro-4- N fluoro-benzylamide ; compound with trifluoro-acetic acid 0 F 152 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-351, 14 13 pyridazine-4-carboxylic acid [ (R)-1- (4- methoxy-phenyl)-ethyl]-amide ; compound 0 with trifluoro-acetic acid HNsts \ N 153 Nn 3-Oxo-6-pyridin-4-yl-2, 3-dihyd ro-379, 17 13 pyridazine-4-carboxylic acid [2- (3- isopropyl-phenoxy)-ethyl]-amide ; compound with trifluoro-acetic acid FIIIO tL 0 0 Example structural formula name M+1 peak synthesis according to Example 154 3-Oxo-6-pyridin-4-yl-2, 3-dihydro- 393, 19 13 -4-carboxylic acid [2- (2-tert- butyl-phenoxy)-ethyl]-amide ; compound with trifluoro-acetic acid KNH O 0 155 O O 6-(4-Hydroxy-3-methyl-phenyl)-3-oxo-2, 3-370, 09 41 " . dihydro-pyridazine-4-carboxylic acid 4- chloro-benzylamide OH OH 156 O O 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-427, 14 13 pyridazine-4-carboxylic acid 4- (pyridin-4- yfcarbamoyl)-benzylamide ; compound with trifluoro-acetic acid y 157 O O 3-Oxo-6-th iophen-3-yl-2, 3-dihydro-346, 03 41 pyridazine-4-carboxylic acid 4-chloro- benzylamide O Example structural formula name M+1 peak synthesis according to Example 158 O O 6-(3, 5-Dimethyl-isoxazol-4-yl)-3-oxo-2, 3-359, 08 41 dihydro-pyridazine-4-carboxylic acid 4- chloro-benzylamide O-N O-N 159 O O 6-1, 3-Benzodioxol-5-yl-3-oxo-2, 3-dihydro-384, 07 41 pyridazine-4-carboxylic acid 4-chloro- N benzylamide 0 160 0 0 6- (3, 4-Difluoro-phenyl)-3-oxo-2, 3-dihydro- 376, 06 41 pyridazine-4-carboxylic acid 4-chloro- benzylamide r F 161 0 0 6- (4-Amino-phenyl)-3-oxo-2, 3-dihydro- 355, 09 13 pyridazine-4-carboxylic acid 4-chloro- benzylamide 162 0 0 3-Oxo-6-pyrimidin-5-yl-2, 3-dihydro- 342, 07 13 pHm pyridazine-4-carboxylic acid 4-chloro- N benzylamide N<o N Example structural formula name M+1 peak synthesis according to Example 163 3-Oxo-6-pyridin-4-yl-2, 3-dihydro- 375, 1 13 pyridazine-4-carboxylic acid 2- N trifluoromethyl-benzylamide ; compound with trifluoro-acetic acid F ? 95 fi'6 164 0 0 6- (4-Hydroxy-phenyl)-3-oxo-2, 3-dihydro- 351, 14 13 pyridazine-4-carboxylic acid (3-pyridin-3-yl- NW propyl)-amide OH Example structural formula name M+1 peak synthesis according to example 165 oo 6- (2-Methyl-pyrimidin-4-yl)-3-oxo-2, 3- 356, 08 13 dihydro-pyridazine-4-carboxylic acid 4- chloro-benzylamide a 1NH 166 O O 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine-317, 12 13 4-carboxylic acid (2- [1, 3] dioxolan-2-yl- ethyl)-amide ° y 167 avL R-3-Oxo-6-[2-(1-phenyl-ethylamino)-456, 21 13 -4NH pyrimidin-4-yl]-2, 3-dihyd ro-pyridazine-4- 'jj carboxylic acid (3-pyridin-3-yl-propyl)-amide y 168 0 6- (6-Methyl-thiazolo [3, 2-b] [1, 2, 4] triazol-5-yl)-401, 05 13 N, 4SO 3-oxo-2, 3-dihydro-pyridazine-4- carboxylic acid 4-chloro-benzylamide N, r v N O Example structural formula name M+1 peak synthesis according to example 169 0 0 6- (2-Methyl-pyrimidin-4-yl)-3-oxo-2, 3- 354, 13 13 dihydro-pyridazine-4-carboxylic acid [2- (4- fluoro-phenyl)-ethyl]-amide F 170 0 0 6- (2-Methyl-pyrimidin-4-yl)-3-oxo-2, 3- 348, 14 13 DJ9NH dihydro-pyridazine-4-carboxylic acid indan- 2-ylamide NA/=\ JXNJ 171 0 0 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 391, 09 13 4-carboxylic acid 4-trifluoromethoxy- f benzylamide t SF _ _ 172 0 0 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 342, 07 13 4-carboxylic acid (2-amino-4-chloro-phenyl)- amide _ a Example structural formula name M+1 peak synthesis according to example 173 O O 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine-400, 1 13 If 4-carboxylic acid [2- (4-sulfamoyl-phenyl)- ethyl]-amide 0=- 0 174 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine-370, 06 13 11 u'H 4-carboxylic acid (2-carbamoyl-4-chloro- "phenyl)-amide _t. _ i 175 O O 6-[2-(2-Morpholin-4-yl-ethylamino)-470, 16 13 +< pyrimidin-4-yl]-3-oxo-2, 3-dihydro-pyridazine- N 1 4-carboxylic acid 4-chloro-benzylamide ; eN compound with trifluoro-acetic acid knlH Y A N O 176 O O 6-Benzo [b] thiophen-3-yl-3-oxo-2, 3-dihydro- 396, 05 41 eHm pyridazine-4-carboxylic acid 4-chloro- benzylamide YS s Example structural formula name M+1 peak synthesis according to example 177 0 0 6- (3-Fluoro-pyridin-4-yl)-3-oxo-2, 3-dihydro- 359, 06 41 pyridazine-4-carboxylic acid 4-chloro- Nf u a benzylamide I I 178 0 0 4- [5- (4-Chloro-benzylcarbamoyl)-6-oxo-1, 6- 384, 07 41 dihydro-pyridazin-3-yl]-benzoic acid N \ o 179 0 0 3- [5- (4-Chloro-benzylcarbamoyl)-6-oxo-1, 6- 384, 07 41 dihydro-pyridazin-3-yl]-benzoic acid N\ I H \ I O OH 180 0 0 6- (3-Chloro-4-hydroxy-phenyl)-3-oxo-2, 3- 390, 03 41 dihydro-pyridazine-4-carboxylic acid 4- chloro-benzylamide OH Example structural formula name M+1 peak synthesis according to example 181 0 0 6- (2-Chloro-4-hydroxy-phenyl)-3-oxo-2, 3- 390, 03 41 dihydro-pyridazine-4-carboxylic acid 4- chloro-benzylamide en 182 0 0 6- (3, 5-Difluoro-4-hydroxy-phenyl)-3-oxo-2, 3- 392, 05 41 dihydro-pyridazine-4-carboxylic acid 4- N chloro-benzylamide CH F Oi 183 0 0 6- (3-Fluoro-4-hydroxy-phenyl)-3-oxo-2, 3- 374, 06 41 dihydro-pyridazine-4-carboxylic acid 4- N chloro-benzylamide CH 9 F OFi 184 0 0 6- (2-Butylamino-pyrimidin-4-yl)-3-oxo-2, 3- 429, 27 13 H<NH dihydro-pyridazine-4-carboxylic acid [3- (4- methyl-piperazin-1-yl)-propyl]-amide N1 t Ns _ H Example structural formula name M+1 peak synthesis according to example 185 0 0 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 342, 19 13 I 4-carboxylic acid (2-cyclohexylamino-ethyl)- N amide 'WJ 186 0 6- (3-Methyl-pyridin-4-yl)-3-oxo-2, 3-dihydro- 355, 09 13 a pyridazine-4-carboxylic acid 4-chloro- N benzylamide ; compound with trifluoro-acetic acid 187 0 0 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 309, 1 13 4-carboxylic acid (4-amino-pyridin-3-yl)- amide t Nv 188 o 0 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 322, 12 13 4-carboxylic acid 2-amino-benzylamide C N\ I/ Example structural formula name M+1 peak synthesis according to example 189 O O 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 314, 15 13 4-carboxylic acid (2-amino-cyclohexyl)- amide O 190 O O 6-(2-Ethylamino-pyrimidin-4-yl)-3-oxo-2, 3-385, 1 1 13 dihydro-pyridazine-4-carboxylic acid 4- chloro-benzylamide y ° L H 191 0 0 5- [5- (4-Chloro-benzylcarbamoyl)-6-oxo-1, 6- 390, 02 41 dihydro-pyridazin-3-yl]-thiophene-2- N carboxylic acid w HO ro 192 ° ° 4- [5- (4-Chloro-benzylcarbamoyl)-6-oxo-1, 6- 390, 02 41 dihydro-pyridazin-3-yl]-thiophene-2- N carboxylic acid O ° Example structural formula name M+1 peak synthesis according to example 193 0 0 6- (4-Methyl-2-pyridin-3-yf-thiazol-5-yl)-3- 438, 07 13 oxo-2, 3-dihydro-pyridazine-4-carboxylic acid 4-chloro-berfzylamide i " -N 194 0 0 6- [2- (4-Chloro-phenyl)-pyrimidin-4-yl]-3-oxo- 452, 06 13 IvNH 2, 3-dihydro-pyridazine-4-carboxylic acid 4- chloro-benzylamide INr a _ __ 195 0 0 6- (2, 6-Dimethyl-pyrimidin-4-yl)-3-oxo-2, 3- 370, 1 13 +<a dihydro-pyridazine-4-carboxylic acid 4- chloro-benzylamide-hydrochloride 196 0 0 5- [5- (4-Chloro-benzylcarbamoyl)-6-oxo-1, 6- 428, 06 13 dihydro-pyridazin-3-yi]-isophthalic acid N\ I H \ I O O I/p1 CFi 0 Example structural formula name M+1 peak synthesis according to example 197 0 0 4- [5- (4-Chloro-benzylcarbamoyl)-6-oxo-1, 6- 420, 03 41 dihydro-pyridazin-3-yl]-3-methoxy- "Ja thiophene-2-carboxy) ic acid s CH 198 o o 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 325, 13 13 4-carboxylic acid (3-imidazol-1-yl-propyl)- amide NH 4/ 199 o o 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 357, 2 13 4-carboxylic acid [3- (4-methyl-piperazin-1- " yl)-propyl]-amide I k NS t s 200 0 0 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 418, 22 13 4-carboxylic acid [2- (1-benzyl-piperidin-4- S yl)-ethyl]-amide { y Example structural formula name M+1 peak synthesis according to example 201 O O 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine- 394, 18 13 4-carboxylic acid 4- (2-dimethylamino- ethoxy)-benzylamide NJ H 202 O O 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine-356, 18 13 If 4-carboxylic acid (1-carbamimidoyl- < + piperidin-4-ylmethyl)-amide r4 Ns * NH t NS NHz 203 O O 3-Oxo-6-pyridin-4-yl-2, 3-dihydro-pyridazine-356, 2 13 4-carboxylic acid (3-cyclohexylamino- propyl)-amide Ns b 6 204 0 0 4-f [ (3-Oxo-6-pyridin-4-yl-2, 3-dihydro- 351, 1 13 pyridazine-4-carbonyl)-amino]-methyl}- N-benzoic acid CL I Example structural formula name M+1 peak synthesis according to example 205 0 0 6- (2-Benzylamino-pyridin-4-yi)-3-oxo-2, 3- 446, 13 41 dihydro-pyridazine-4-carboxylic acid 4- ; N t a chloro-benzylamide Y if H 206 O O 6-(2-Methylamino-pyridin-4-yl)-3-oxo-2, 3-370, 1 41 dihydro-pyridazine-4-carboxylic acid 4- chloro-benzylamide H H 207 O O 6-(5-Carbamoyl-4-methoxy-thiophen-3-yl)-3-419, 05 41 oxo-2, 3-dihydro-pyridazine-4-carboxylic acid a 4-chloro-benzylamide -ITS' s 208 0 0 6- (2-Methyl-pyridin-4-yl)-3-oxo-2, 3-dihydro- 355, 09 41 pyridazine-4-carboxylic acid 4-chloro- benzylamide ; compound with trifluoro-acetic acid Example structural formula name M+1 peak synthesis according to example 209 0 0 6- (4-Methylcarbamoyl-phenyl)-3-oxo-2, 3- 397, 1 41 dihydro-pyridazine-4-carboxylic acid 4- NX > a chloro-benzylamide W H 210 0 0 6- (3-Methylcarbamoyl-phenyl)-3-oxo-2, 3- 397, 1 41 dihydro-pyridazine-4-carboxylic acid 4- NY a chloro-benzylamide 0 211 O O 6-(4-Carbamoyl-phenyl)-3-oxo-2, 3-dihydro-383, 08 41 pyridazine-4-carboxylic acid 4-chloro- a N benzylamide Y _ OANH2 Example structural formula name M+1 peak synthesis according to example 212 O O 6-(3-Carbamoyl-phenyl)-3-oxo-2, 3-dihydro-383, 08 41 pyridazine-4-carboxylic acid 4-chloro- benzylamide _ _. 0 213 R-3-Oxo-6- [2- (1-phenyl-ethylamino)- 461, 14 13 I » NH pyrimidin-4-yl]-2, 3-dihydro-pyridazine-4- N carboxylic acid 4-chloro-benzylamide , ° 1-k 214 CHFAL R-3-Oxo-6- [2- (1-phenyl-ethylamino)- 461, 14 13 0 0 pyrimidin-4-yl]-2, 3-dihydro-pyridazine-4- carboxylic acid butylamide ¢IlN) 4NS Example structural formula name M+1 peak synthesis according to example 215 CHPAL R-3-Oxo-6- [2- (l-phenyi-ethylamino)-455, 21 13 ° ° pyrimidin-4-yl]-2, 3-dihydro-pyridazine-4- N carboxylic acid (3-phenyl-propyl)-amide eD X H 216 ° ° 6- (2-Butylamino-pyrimidin-4-yl)-3-oxo-2, 3- 413, 14 13 If dihydro-pyridazine-4-carboxylic acid 4- N chloro-benzylamide i ° L H 217 O O 4-{[(3-Oxo-6-pyridin-4-yl-2, 3-dihydro-365, 12 13 pyridazine-4-carbonyl)-amino]-methyl}- N benzoic acid methyl ester ; compound with ¢) trifluoro-acetic acid 218 0 0 6- (2-Butylamino-pyrimidin-4-yl)-3-oxo-2, 3- 429, 27 13 dihydro-pyridazine-4-carboxylic acid [3- (4- methyl-piperazin-1-yl)-propyl]-amide ; compound with trifluoro-acetic acid H H Example structural formula name M+1 peak synthesis according to example 219 0 0 6- (2-Butylamino-pyrimidin-4-yl)-3-oxo-2, 3- 380, 18 13 dihydro-pyridazine-4-carboxylic acid (pyridin-3-ylmethyl)-amide > > Nv H H 220 0 0 6- (2-Butylamino-pyrimidin-4-yl)-3-oxo-2, 3- 408, 21 13 dihydro-pyridazine-4-carboxylic acid (3- < % pyridin-3-yl-propyl)-amide H L) U H 221 O O 6-(2-Ethylamino-pyrimid in-4-yl)-3-oxo-2, 3-400, 24 13 dihydro-pyridazine-4-carboxylic acid (3- cyclohexylamino-propyl)-amide N1 X 6 222 o 0 3-Oxo-6- (2-phenethylamino-pyridin-4-yl)- 460, 15 41 2, 3-dihydro-pyridazine-4-carboxylic acid 4- chloro-benzylamide av3 H Example structural formula name M+1 peak synthesis according to example 223 0 0 6- [2- (2-Morpholin-4-yl-ethylamino)-pyridin-4- 469, 17 41 , i"i \ yl]-3-oxo-2, 3-dihydro-pyridazine-4-carboxylic acid 4-chloro-benzylamide '° ^lJ 224 O O 6-(2-Ethylamino-pyridin-4-yl)-3-oxo-2, 3-384, 12 41 dihydro-pyridazine-4-carboxylic acid 4- N chloro-benzylamide H H 225 4- (f [6- (4-Hydroxy-3-methoxy-phenyl)-3-oxo- 396, 11 41 2, 3-dihydro-pyridazine-4-carbonyl]-amino}- methyl)-benzoic acid 0 hp 226 6- (2-Methylamino-pyrimidin-4-yl)-3-oxo-2, 3- H dihydro-pyridazine-4-carboxylic acid (3- pyridin-3-yl-propyl-) amide . NH-N I i

Example 41<BR> 6-(4-Hydroxy-3-methoxy-phenyl)-3-oxo-2,3-dihydro-pyridazine- 4-<BR> carboxylic acid 4-chloro-benzyl amide<BR> a) 3,6-Dichloro-pyridazine-4-carboxylic acid<BR> A solution of 24.9 g 3,6-dichloro-4-methylpyridazine and 56,7 g potassium<BR> dichromate in 250 ml of concentrated sulphuric acid are stirred at 40°C for<BR> 2 h, the reaction mixture is poured onto 1.5 I ice-water and extracted with<BR> ethyl acetate. The organic layer is extracted with water and a saturated<BR> solution of NaCl, dried over MgSO4 and evaporated. The raw product is<BR> used without any further purification.<BR> <P>Yield: 27.1 g<BR> MS:M+1=193.1<BR> b) 6-Chloro-3-oxo-2,3-dihydro-pyridazine-4-carboxylic acid<BR> 27 g of 3,6-dichloro-pyridazine-4-carboxylic acid are stirred at 50°C for 6 h<BR> in a 1:1 mixture of concentrated sulphuric acid and water. The pure product<BR> crystallizes after cooling off the reaction mixture and is filtered.<BR> <P>Yield: 12.48 g<BR> MS:M+1=175.1<BR> c) 6-Chloro-3-oxo-2,3-dihydro-pyridazine-4-carboxylic acid 4-<BR> chloro-benzyl amide<BR> Oxalyl chloride is added to a solution a 8.73 g of 6-chloro-3-oxo-2,3-<BR> dihydro-pyridazine-4-carboxylic acid and 1 ml DMF in 250 ml THF at 5-<BR> 10°C and the mixture is stirred at room temperature for 2 h. Afterwards, it is<BR> evaporated to dryness, the residue dissolved in 450 ml THF and 13.8 g<BR> potassium carbonate and a solution of 7.2 g 4-chloro-benzyl amide in THF<BR> are added. The solvent is distilled off after 2 h of stirring at room<BR> temperature, the residue suspended in 100 ml water and a pH of 6.4 is<BR> adjusted. The obtained precipitate is sucked off, suspended again in 50 ml

water and the pH is adjusted to 3. Afterwards, the precipitate is sucked off and dried over phosphorous pentoxide in an exciccator.

Yield : 9.3 g MS: M+1=298. d) 6-Chloro-3-oxo-2- (2-trimethylsilyl-ethoxymethyl)-2, 3-dihydro- pyradizine-4-carboxylic acid 4-chloro-benzyl amide 8.6 g of 6-chloro-3-oxo-2, 3-dihydro-pyridazine-4-carboxylic acid 4 chloro- benzyl amide are dissolved in 100 ml of absolute DMF and 4.8 g N, N- diisopropylethyl amine are added, then it is stirred at room temperature for 30 min. Afterwards, 5.9 g of trimethylsilylethoxymethyl chloride is added dropwise and it is stirred at room temperature for 5 h. The mixture is added to 1000 ml water for working up, extracted with ethyl acetate, the organic layer is washed with a saturated solution of NaCI and dried over MgS04.

After distilling off the solvent the residue is chromatographically purified (silica gel, n-heptane/ethylacetate).

Yield : 7.6 g MS : M+1=428. 18. e) 6- (4-Hydroxy-3-methoxy-phenyl)-3-oxo-2- (2-trimethylsilanyl- ethoxymethyl)-2, 3-dihydro-pyradizine-4-carboxylic acid 4- chloro-benzyl amide A solution of 128.5 mg 6-chloro-3-oxo-2-(2-trimethylsilyl-ethoxymethyl)-2, 3- dihydropyridazine-4-carboxylic acid 4-chloro-benzyl amide, 91.8 mg 2- methoxy-4- (4, 4,5, 5-tetramethyl-1, 3, 2-dioxaborolan-2-yl)-phenol, 82.9 mg K2C03 and 32.1 mg triphenylphosphine in 3.2 ml DME/H20 (2/1) are degassed by conducting of argon. Afterwards, the mixture is diluted with ethyl acetate and washed with 0.5 N of HCI. After drying over MgS04 the solvent is distilled off and the raw product is purified by HPLC (column 125x25, PurospherStar RP18 endcapped, 5 pm ; solvent : A: water (0.05 % HCOOH), B: acetonitrile (0.05 % HCOOH)).

Yield : 70.7 mg

MS: M+1=516.31 f) 6- (4-Hydroxy-3-methoxy-phenyl)-3-oxo-2, 3-dihydro-pyridazine- 4-carboxylic acid 4-chloro-benzyl amide 70.7 mg of 6- (4-hydroxy-3-methoxy-phenyl)-3-oxo-2- (2-trimethylsilanyl- ethoxymethyl)-2, 3-dihydro-pyridazine-4-carboxylic acid 4-chloro-benzyl amide and 60 pi ethandithiol and 60 pi Water are dissolved in 750 pI TFA and stirred at room temperature for 3 h. Afterwards, the solvent is distilled off and the raw product purified by HPLC (column 125x25, PurospherStar RP18 endcapped, 5 um ; solvent: A: water (0.05 % HCOOH), B: acetonitrile (0.05 % HCOOH)).

Yield : 19. 7 mg MS: M+1=386. 14 Functional measurements for determination of IC50-values CDK2/Cyclin E Flashplate Assay : 96-well format A 96-well streptavidin-coated flashplate is used to assay potency of compounds according formula (I) against CDK2/Cyclin E kinase. To carry out the assay, biotinylated-Rb peptide substrate (Biotin- SACPLNLPLQNNHTAADMYLSPVRSPKKKGSTTR-OH) is solubilized at 1 mM in kinase buffer (Hepes 50 mM, NaCl 1 mM, MgCl2 5mM pH 7.5) as a stock solution conserved at-20°C in aliquots of 110 µl. The day of the experiment, an aliquot of this solution is thawn and diluted to 14. 3 uM in kinase buffer, containing 1 mM dithithreitol (DTT) added in the buffer extemporarily.

70 NI of this solution is added in each well of the flashplate in order to achieve a final concentration of 10 µM (100 µl reactionnal volume). Serial dilutions of inhibitors are prepared in DMSO from 10 mM stock solutions in order to achieve 1000 uM, 333. 3 µM, 111. 1 uM, 37. 03 µM, 12. 35 uM, 4.11 uM and 1. 37 uM and all rediluted in kinase buffer + DTT in order to achieve 100 jiM, 33.3 NM, 11.1 NM, 3.7 NM, 1. 24 µM, 0.41 pM and 0. 14 MM in DMSO 10 % buffer (vol/vol). 10 NI of each of these solutions (or 10 MI of buffer + DTT for controls) are transferred to the testplate wells in order to achieve 10 NM, 3. 33 uM, 1. 11 µM, 0. 37 uM, 0. 12 µM, 0. 04 jiM and 0.01 NM

as final concentrations, 1 % DMSO (vol/vol). In each well, 10 µl of a solution of a mix of 33PyATP/ATP are added in order to achieve 1 NM final concentration and a total of 1 µCi. The kinase reaction is initiated by addition of 10 pi of a solution at 200 nM of CDK2/Cyclin E in kinase buffer + DTT (or buffer + DTT for blanks) in order to achieve 20 nM final concentration. After addition of each reagent, the test-plate is shaked. The plates are incubated 30 minute at 30°C with a shaking at 650 rpm. At the end of the incubation, the plates are washed 3 times with 300 NI of PBS (without calcium and magnesium) per well. The incorporation of 33P to the peptide is measured by scintillation counting. Exam le ICSO M 2 0, 905 4 0, 577 13 0, 764 16 0, 174 18 0, 536 31 0, 581 34 0, 03 39 0, 344 40 0, 119 41 0, 147 49 0, 175 66 0, 521 75 0, 802 83 0, 552 84 0, 219 93 0, 349 98 0, 664 103 0, 164 112 0, 36 116 0, 787 125 0, 519 139 0, 353 142 0, 356 164 0, 133 167 0, 125 175 0, 027 180 0, 173 182 0, 464 183 0, 102 190 0, 018 206 0, 157 217 0, 024 218 0, 107 219 0, 015 220 0, 012 225 0, 149 226 0, 055