The present invention relates to certain novel monocyclic β-lactam compounds, processes for their preparation, intermediates useful in their preparation, pharmaceutical compositions containing them and their use in therapy, in particular in the treatment of atherosclerosis.

WO 95/00649 (SmithKline Beecham pic) describe the phospholipase A2 enzyme Lipoprotein Associated Phospholipase A2 (Lp-PLA2). the sequence, isolation and purification thereof, isolated nucleic acids encoding the enzyme, and recombinant host cells transformed with DNA encoding the enzyme. Suggested therapeutic uses for inhibitors of the enzyme included atherosclerosis, diabetes, rheumatoid arthritis, stroke, myocardial infarction, reperfusion injury and acute and chronic inflammation. A subsequent publication from the same group further describes this enzyme (Tew D et al, Arterioscler Thromb Vas Biol 1996:16;591- 9) wherein it is referred to as LDL-PLA2. A later patent application (WO 95/09921, Icos Coφoration) and a related publication in Nature (Tjoelker et al, vol 374, 6 April 1995, 549) describe the enzyme PAF- AH which has essentially the same sequence as Lp-PLA2 and suggest that it may have potential as a therapuetic protein for regulating pathological inflammatory events.

It has been shown that Lp-PLA2 is responsible for the conversion of phosphatidylcholine to lysophosphatidylcholine, during the conversion of low density lipoprotein (LDL) to its oxidised form. The enzyme is known to hydrolyse the sn-2 ester of the oxidised phosphatidylcholine to give lysophosphatidylcholine and an oxidatively modified fatty acid. Both products of Lp-PLA2 action are biologically active with lysophosphatidylcholine, a component of oxidised LDL, known to be a potent chemoattractant for circulating monocytes. As such, lysophosphatidylcholine is thought play a significant role in atherosclerosis by being responsible for the accumulation of cells loaded with cholesterol ester in the arteries. Inhibition of the Lp-PLA2 enzyme would therefore be expected to stop the build up of these macrophage enriched lesions (by inhibition of the formation of lysophosphatidylcholine and oxidised free fatty acids) and so be useful in the treatment of atherosclerosis.

The increased lysophosphatidylcholine content of oxidatively modified LDL is also thought to be responsible for the endothelial dysfunction observed in

patients with atherosclerosis. Inhibitors of Lp-PLA2 could therefore prove beneficial in the treatment of this phenomenon. An Lp-PLA2 inhibitor could also find utility in other disease states that exhibit endothelial dysfunction including diabetes, hypertension, angina pectoris and after ischaemia and reperfusion.

In addition, Lp-PLA2 inhibitors may also have a general application in any disorder that involves activated monocytes, macrophages or lymphocytes, as all of these cell types express Lp-PLA ₂ . Examples of such disorders include psoriasis.

Furthermore, Lp-PLA2 inhibitors may also have a general application in any disorder that involves lipid peroxidation in conjunction with Lp-PLA2 activity to produce the two injurious products, lysophosphatidylcholine and oxidatively modified fatty acids. Such conditions include the aforementioned conditions atherosclerosis, diabetes, rheumatoid arthritis, stroke, myocardial infarction, reperfusion injury and acute and chronic inflammation. Further such conditions include various neuropsychiatric disorders such as schizophrenia (see Psychopharmacology Bulletin, 31, 159-165, 1995).

An earlier patent application (WO 96/19451, SmithKline Beecham pic) discloses compounds of the formula (A):

(A) in which:

R.1 and R.2, which may be the same or different, is each selected from hydrogen, halogen or optionally substituted C(i_g ₎ alkyl;

R3 is aryl or arylC(i_4)alkyl which may be optionally substituted;

X is a linker group;

Y is an optionally substituted aryl group; and n is 0, 1 or 2.

Such compounds of formula (A) are inhibitors of Lp-PLA2 and as such are expected to be of use in treating atherosclerosis and the other disease conditions noted above.

WO 97/02242 (SmithKline Beecham pic) describes further compounds having a substiuent such a methyl on the carbon attached to N-1. In addtion,

PCT/EP96/05587 (SmithKline Beecham pic) discloses pro-drugs of compounds of formula (A) in which R^ is a 4-carboxybenzyl group.

Compounds of formula (A) exist in a number of stereoisomeric forms. The C-4 carbon of the β-lactam ring is a chiral centre which will give rise to the presence of stereoisomers. Furthermore, in compounds of formula (A) in which n is 1, that is sulphoxide compounds, the presence of the SO moiety will introduce an additional chiral centre into the molecule and therefore give rise to the existence of extra stereoisomers. Preferred compounds of formula (A) are said to be those in which the relative configurations at C-4 and the SO moiety are R,S (4R,SS) and SM (45.SR) with the most preferred compounds having the absolute configuration (4R.SS).

Accordingly, the present invention provides for a compound of the formula (I):

(I) in which:

Rl is hydrogen or a corresponding pharmaceutically acceptable ester or a pharmaceutically acceptable salt thereof;

R2 and R3 which may be the same or different is each selected from hydrogen or optionally substituted C(i_6)alkyl;

X is a group X ^, (CH ₂ ) _m in which X' is CO, CONR ⁴ , COO, CONR ⁴ CO, CONHO or CH2O in which R ⁴ is hydrogen or C(i_6 ₎ alkyl and m is 0 or an integer from 1 to 12, or a C(j.ι 2 ₎ alkylene chain optionally interupted by X'; and

Y is an optionally substituted aryl group; having the absolute configuration (4R,SS).

Representative examples of X include CO(CH2) _m , CONH(CH2) _m , COO(CH ₂ ) _m , CONHCO(CH ₂ ) _m , CONHO(CH ₂ )rn CH2θ(CH ₂ )m and C ₍ μ j2 ₎ alkylene. Preferably, X' is CO, CONR ² or CH2O, more preferably CONH. Preferably, m is 1, 2, 5, 6, 7 or 9, preferably 6. Suitably, X is CONH ⁽ CH ₂ )6 or CH ₂ O(CH ₂ )6. preferably CONH(CH ₂ )6.

Suitably, R ² and R^ is each hydrogen or R ² is hydrogen and R-* is methyl. Preferably, R ² and R^ is each hydrogen. It will be readily appreciated that when

R ² and R have different values, the carbon to which they are attached will be chiral. Preferably, the absolute configuration at this carbon is S. In such compounds of formula (I), the absolute configuration of the preferred enantiomer is (α-5, 4-R, S-S).

Suitably, Y is phenyl, optionally substituted by up to three further substituents. Suitable substituents include halo, hydroxy, C ₍ i_g ₎ alkyl and C(j_g)alkoxy. Preferably, Y is phenyl optionally substituted by halo, more preferably 4-chloro or 4-fluoro-phenyl, most preferably, 4-fIuoro-phenyl.

Suitably X-Y is CONH(CH ₂ )6Ph(4-F)/(4-CI).

Suitable pharmaceutically acceptable esters include C ₍ i_6 ₎ alkyl or C ₍ 2-6 ₎ alk ^en yl esters, as well as pharmaceutically acceptable in vivo hydrolysable esters. The skilled person will appreciate that simple C(i_6 ₎ alkyl or C(2-6 ₎ alke ⁿ y! benzoate esters show little if any tendency to break down in the human body, to leave the parent acid or its salt, even though they may be susceptible to in vivo hydrolysis in animals such as rabbits and dogs. The term "in vivo hydrolysable ester" is not therefore conventionally considered to include such esters.

Suitable C(i_6 ₎ alkyl or C(2-6 ₎ alkenyl esters include ethyl and allyl esters.

Suitable pharmaceutically acceptable in vivo hydrolysable ester groups for incorporation in R include those which break down readily in the human body to leave the parent acid or its salt.

Suitable values of R* for use in vivo hydrolysable esters include: -CH(R ^a )O.CO.R ^b ; -CH(R ^a )O.CO.OR ^c ; -CH(R ^a )CO.NReR ^f -R ^d NReRf; -CH ₂ ORg;

OH,

°Y o ° -CH(R ^a )O.CO.C ₆ H4Y ¹ COCH(R ⁱ )NH ₂ ; and

in which:

R ^a is hydrogen, (Cι-6)alkyl, in particular methyl, (Cβ-γteycloalkyl, or phenyl, each of which may be optionally substituted;

R ^b is (Cι-6)alkyl, (Cι-6)alkoxy(Cι-6)alkyl, phenyl, benzyl, (C3-7)cycloalkyl,

(Cι-6)alkyl(C3-7)cycloalkyl _t l-amino(Cι-6)alkyl, or l-(Cι-6alkyl)amino(Cι-6)aIkyl, each of which may be optionally substituted; or

R ^a and R ^D together form a 1,2-phenylene group optionally substituted by one or two methoxy groups;

R ^c is (Cι-6)alkyl, (Cβ^cycloalkyl, (C^alkyKC _β -γJcycloalkyl;

R ^d is (Cι-6)alkylene optionally substituted with a methyl or ethyl group;

R ^e and R ^f which may be the same or different is each (Cι-6)alkyl; or ary!(C 1 -4) alkyl, optionally substituted with e.g. hydroxy;

Rg is (Cι-6)alkyl;

R ⁿ is hydrogen, (Cι-6)alkyl or phenyl;

R* is hydrogen or phenyl optionally substituted by up to three groups selected from halogen, (Cι-6)-alkyI, or (Cj-6)alkoxy; and γl is oxygen or NH.

Suitable values of R* include:

(a) acyloxyalkyl groups such as acetoxymethyl, isobutyryloxymethyl, pivaloyloxymethyl, benzoyloxymethyl, α-acetoxyethyl, α-pivaloyloxyethyl, l-(cyclohexylcarbonyloxy)ethyl, (l-aminoethyl)carbonyloxymethyl, 2- methoxyprop-2-ylcarbonyloxymethyl, phenylcarbonyloxymethyl and 4- methoxyphenyl-carbonyloxymethyl;

(b) alkoxy/cycloalkoxycarbonyloxyalkyl groups, such as ethoxycarbonyloxymethyl, t-butyloxycarbonyloxymethyl, cyclohexyloxycarbonyloxymethyl, 1-methylcyclohexyloxycarbonyloxymethyl and α-ethoxycarbonyloxyethyl;

(c) dialkylaminoalkyl, especially di-loweralkylamino alkyl groups such as dimethylaminomethyl, dimethylaminoethyl, diethylaminomethyl or diethylaminoethyl;

(d) acetamido groups such as N,N-dimethylaminocarbonylmethyl, N,N-(2- hydroxyethyl)aminocarbonylmethyl ;

(e) lactone groups such as phthalidyl and dimethoxyphthalidyl;

(f) (5-methyl-2-oxo-l,3-dioxolen-4-yl)methyl; and

(g) (2-methoxycarbonyl-£-but-2-en-yl)methyl.

Representative examples of R ¹ include: (2-methoxycarbonyI-E-but-2-en-yl)methyl, isobutyryloxymethyl, 2- methoxyprop-2-ylcarbonyloxymethyl, phenylcarbonyloxymethyl, 4-methoxyphenyl-carbonyloxymethyl, t-butyloxycarbonyloxymethyl, cyclohexyloxy-carbonyloxymethyl, 1-methylcyclohexyloxycarbonyloxymethyl, N,N-dimethylaminocarbonylmethyl, N-N-di-(2- hydroxyethyl)aminocarbonylmethyloxy and (5-methyl-2-oxo- 1 ,3-dioxolen-4- yl)methyl.

Especially preferred compounds of Formula (I) include: (4R, S5)-N-[6-(4-Fluorophenyl)hex-l-yl]-4-(4-carboxybenzylsulphin yl)-2- oxoazetidin-l-yl)acetamide and pharmaceuticaly acceptable salts thereof, in particular the sodium salt.

Since the compounds of Formula (I) are intended for use in pharmaceutical compositions, it will be understood that they are each provided in substantially pure form, for example at least 50% pure, more suitably at least 75% pure and preferably at least 95% pure (% are on a wt/wt basis). Impure preparations of the compounds of Formula (I) may be used for preparing the more pure forms used in the pharmaceutical compositions. Although the purity of intermediate compounds of the present invention is less critical, it will be readily understood that the substantially pure form is preferred as for the compounds of Formula (I). Preferably, whenever possible, the compounds of the present invention are obtained in crystalline form.

When some of the compounds of this invention are allowed to crystallise or are recrystallised from organic solvents, solvent of crystallisation may be present in the crystalline product. This invention includes within its scope such solvates. Similarly, some of the compounds of this invention may be crystallised or recrystallised from solvents containing water. In such cases water of hydration may be formed. This invention includes within its scope stoichiometric hydrates as well as compounds containing variable amounts of water that may be produced by processes such as lyophilisation. In addition, different crystallisation

conditions may lead to the formation of different polymorphic forms of crystalline products. This invention includes within its scope all polymorphic forms of the compounds of Formula (I).

Compounds of the present invention are inhibitors of the enzyme lipoprotein associated phospholipase A2 (Lp-PLA2) and as such are expected to be of use in therapy, in particular in the treatment of atherosclerosis. In a further aspect therefore the present invention provides a compound of Formula (I) for use in therapy.

The compounds of Formula (I) are inhibitors of lysophosphatidylcholine production by Lp-PLA2 and may therefore also have a general application in any disorder that involves endothelial dysfunction, for example atherosclerosis, diabetes, hypertension, angina pectoris and after ischaemia and reperfusion. In addition, compounds of Formula (I) may have a general application in any disorder that involves lipid peroxidation in conjunction with enzyme activity, for example in addition to conditions such as atherosclerosis and diabetes, other conditions such as rheumatoid arthritis, stroke, inflammatory conditions of the brain such as Alzheimer's Disease, myocardial infarction, reperfusion injury, sepsis, and acute and chronic inflammation. Further such conditions include various neuropsychiatric disorders such as schizophrenia (see Psychopharmacology Bulletin, 31, 159-165, 1995).

Further applications include any disorder that involves activated monocytes, macrophages or lymphocytes, as all of these cell types express Lp- PLA2. Examples of such disorders include psoriasis.

Accordingly, in a further aspect, the present invention provides for a method of treating a disease state associated with activity of the enzyme Lp-PLA2 which method involves treating a patient in need thereof with a therapeutically effective amount of an inhibitor of the enzyme. The disease state may be associated with the increased involvement of monocytes, macrophages or lymphocytes; with the formation of lysophosphatidylcholine and oxidised free fatty acids; with lipid peroxidation in conjunction with Lp-PLA2 activity; or with endothelial dysfunction.

Compounds of the present invention may also be of use in treating the above mentioned disease states in combination with anti-hyperlipidaemic or anti- atherosclerotic or anti-diabetic or anti-anginal or anti-inflammatory or anti- hypertension agents. Examples of the above include cholesterol synthesis

inhibitors such as statins, anti-oxidants such as probucol, insulin sensitisers, calcium channel antagonists, and anti-inflammatory drugs such as NSAIDs.

In therapeutic use, the compounds of the present invention are usually administered in a standard pharmaceutical composition. The present invention therefore provides, in a further aspect, a pharmaceutical composition comprising a compound of Formula (I) and a pharmaceutically acceptable carrier.

Suitable pharmaceutical compositions include those which are adapted for oral or parenteral administration or as a suppository.

The compounds of Formula (I) which are active when given orally can be formulated as liquids, for example syrups, suspensions or emulsions, tablets, capsules and lozenges.

A liquid formulation will generally consist of a suspension or solution of the compound or pharmaceutically acceptable salt in a suitable liquid carrier(s) for example, ethanol, glycerine, non-aqueous solvent, for example polyethylene glycol, oils, or water with a suspending agent, preservative, flavouring or colouring agent.

A composition in the form of a tablet can be prepared using any suitable pharmaceutical carrier(s) routinely used for preparing solid formulations. Examples of such carriers include magnesium stearate, starch, lactose, sucrose and cellulose.

A composition in the form of a capsule can be prepared using routine encapsulation procedures. For example, pellets containing the active ingredient can be prepared using standard carriers and then filled into a hard gelaun capsule; alternatively, a dispersion or suspension can be prepared using any suitable pharmaceutical carrier(s), for example aqueous gums, celluloses, sihcates or oils and the dispersion or suspension then filled into a soft gelatin capsule.

Typical parenteral compositions consist of a solution or suspension of the compound of Formula (I) in a sterile aqueous carrier or parenterally acceptable oil, for example polyethylene glycol, polyvinyl pyrrolidone, lecithin, arachis oil or sesame oil. Alternatively, the solution can be lyophilised and then reconstituted with a suitable solvent just prior to administration.

A typical suppository formulation comprises a compound of Formula (I) which is active when administered in this way, with a binding and/or lubricating agent such as polymeric glycols, gelatins or cocoa butter or other low melting vegetable or synthetic waxes or fats.

Preferably the composition is in unit dose form such as a tablet or capsule.

Each dosage unit for oral administration contains preferably from 1 to 500 mg (and for parenteral administration contains preferably from 0.1 to 25 mg) of a compound of the Formula (I).

The daily dosage regimen for an adult patient may be, for example, an oral dose of between 1 rag and 1000 mg, preferably between 1 mg and 500 mg, or an intravenous, subcutaneous, or intramuscular dose of between 0.1 mg and 100 mg, preferably between 0.1 mg and 25 mg, of the compound of the Formula (I), the compound being administered 1 to 4 times per day. Suitably the compounds will be administered for a period of continuous therapy, for example for a week or more.

Compounds of formula (I) may be prepared from convenient starting materials by adapting synthetic procedures well known in the art, with reference to earlier applications WO 96/19451 and WO 97/02242 (SmithKline Beecham pic).

Preferred compounds of formula (I) in which X is an amide CONH may be prepared by a process which comprises treating a compound of formula (LI):

(II) in which R* is C(i.6)alkyl or C^-φ^eny ¹ ^d R^ ^and & ^e ∞ hereinbefore defined, and having the absolute configuration (4R,SS); with an amine of the formula (HI):

H ₂ N(CH ₂ ⁾ _n Y

(III) under suitable amide forming conditions, for instance in the presence of an activating agent such as N,N-dicyclohexylcarbodiimide and 1- hydroxybenzotriazole in a suitable solvent such as dry dimethylformamide; and thereafter, and if necessary,

(a) removing the ester group under suitable de-esterifying conditions to form the acid;

(b) converting the acid to a pharmaceutically acceptable salt; and/or

(c) converting the acid, a suitable salt, the ester or an activated derivative of the acid, to an in vivo hydrolysable ester by reaction with a compound of formula (IV):

RlR4

(IV) in which:

R ⁴ is a reactive esterifying leaving group; and Rl is as hereinbefore defined; under ester forming conditions.

In step (a) above, the free acid may be regenerated from a corresponding compound in which the carboxy group is protected as a C^.^alkyl or C(2-6) ^a U ^£en y ¹ ester; using methods well known in the art for the particular protecting group, for instance, when an allyl group, using palladium catalysed de- allylation (triphenylphosphine/ pyrrolidine/ tetrakis triphenyl- phosphinepalladium(O) in dichloromethane).

In step (b) above, salts by prepared by treating the corresponding acid with an appropriate base.

Suitable ester forming conditions for use in step (c) above are well known in the art and are described in, for instance, Comprehensive Organic Synthesis, Pergamon Press, 1991, 6, 323-380. Suitable ester forming conditions include:

(a) reacting a salt of the acid, for instance, a sodium or a tertiary amine salt such as triethylamine, with a compound of formula (IV), in a polar aprotic solvent such as dimethyl formamide, dimethyl sulphoxide or acetonitrile, at moderate temperature, for instance in the range 0 to 100°C;

(b) reacting the acid with a compound of formula (IV) in the presence of a base such as an alkali metal carbonate or a tertiary amine, in a polar aprotic solvent and temperature as for (a);

(c) reacting the acid with a compound of formula (IV) in which R ⁷ is a hydroxyl group, under dehydrating conditions, for instance the Mitsunobu reaction employing an azodicarboxylate and a trivalent phosphorus reagent (Mitsunobu, Synthesis, 1981, 1); or

(d) reacting an activated derivative of the acid, for instance a mixed anhydride, for instance an isø-butylcarbonic or a methane sulphonic anhydride or a carbodiimide (DCC) adduct, with a compound of formula (IV) in which R^ is a hydroxyl group, in the presence of a suitable base such as a tertiaryamine, for instance, triethylamine, in an aprotic solvent such as tetrahydrofuran, at a moderate temperature, preferably in the range -20 to +20°C, or alternatively, in the absence of a base but using a preformed salt of the alcohol, for instance the magnesium or lithium alkoxide.

Preferred conditions include the use of the sodium salt of the acid in combination with a halide or sulphonate derivative of the compound of formula (TV).

Compounds of formula (LI) are useful intermediates in the preparation of a compound of formula (I). Accordingly, in a further aspect, the present invention provides for a compound of formula (II) as hereinbefore defined.

Compounds of formula (LT) are sulfoxides and may be readily prepared by oxidising a corresponding thio compound of formula (V):

(V) in which R*, R ² and R^ are as hereinbefore defined, and having the absolute configuration (4R); with a conventional oxidising agent such as m-chloroperbenzoic acid (mcpba) or ozone and thereafter and, if necessary, isolating the required diastereoisomer having the desired absolute configuration (4R, SS), for instance by fractional crystallisation and/or chromatography.

Compounds of formula (V) are of use in preparing compounds of formula (I). Accordingly, in a further aspect, the present invention provides for compounds of formula (V) as hereinbefore defined.

Compounds of formula (I) may also be obtained by an alternative process in which the two steps hereinbefore described are reversed, that is a compound of formula (V) is first treated with a compound of formula (LTI), to form the amide

bond, and the resultant thio intermediate then oxidised to the corresponding sulfoxide of formula (II), preferably using a chiral oxidising system which yields the required isomer as the predominant product.

Compounds of formula (V) having the absolute configuration (4R) may be obtained from the corresponding racemic compound of formula (VI):

(VI) in which R* is a carboxy protecting group, for instance C(i_6)alkyl or C(2-6) ^alk enyl and R ² and R are as hereinbefore defined; via the formation of a diastereoisomeric salt with a chiral base such as (-)-cinchonidine; and thereafter:

(a) isolating the preferred diastereoisomeric salt may be obtained by fractional crystallisation; and then

(b) generating the enantiomeric free acid therefrom by acidification.

Diastereoisomeric salts formed from a compound of formula (VI) and a chiral base are of use in preparing compounds of formula (I). Therefore, in a further aspect, the present invention provides for such salts.

Compounds of formula (VI) may be obtained according to the procedures described in earlier applications WO 96/19451 and WO 97/02242 (SmithKline Beecham pic).

The process hereinbefore described for compounds of formula (I), as well as an alternative process for preparing compounds of formula (II), in which R ² and R-* is each hydrogen is summarised in the following scheme, in which R corresponds to CH2C6H4CO2R ¹ :

OAc / ^SR ttnmt —tl * ^s r< Ef »CO _j H ^~ sr* . Ef -CO,H

03

Compounds of formula (I) in which R ² is hydrogen and R^ is alkyl, for instance methyl, may be usefully prepared by a corresponding process in which the alkyl group is introduced at an early stage, by alkylating an azetidinone acetate of formula (VII):

(vπ) in which R** is C ₍ ].6)alkyl, for instance, methyl, and R* is as hereinbefore defined; with an alkylating agent under standard alkylating conditions; and thereafter, isolating the diastereoisomers thus obtained by fractional crystallisation and/or chromatography. Suitably, the compound of formula (VII) may be a single enantiomer, having the required absolute configuration (4R).

Suitable alkylating agents include an alkyl iodide, in the presence ofa suitable base such as sodium hydride or potassium hydroxide, optionally with a quaternary ammonium salt such tetrabutyl ammonium bromide, in a suitable alkylating solvent such as tetrahydrofuran (THF), and at a temperature in the range -10 to 0°C. Other suitable conditions include lithium bis(trimethylsilyl)amide in THF, optionally with l,3-dimethylimidazolidin-2-one, and at a temperature of about -70°C.

The newly formed propionate ester may then be converted to the corresponding acid, using basic conditions such as aqueous sodium hydroxide in THF, followed by amide bond formation and then oxidation of the thio group, as previously described. Enantiomers may be usefully isolated by chiral chromatography, for instance hplc using a chiral stationary phase, on compounds of formula (I), at the alkyl/alkenyl ester stage.

The sequences can be readily adapted for other values of X, by reference to earlier applications WO 96/19451 and WO 97/02242 (SmithKline Beecham plc).

For instance, compounds of formula (I) in which the linker group X contains an ether function may be prepared by a suitable ether coupling reaction, for instance, when X' is CH2O, treating a compound of formula (VUΪ):

(VUI) in which R*. R ² and R^ are as hereinbefore defined; with a compound of formula (DC):

L3(CH ₂ ) _m Y

(IX) in which one of L ² and L is a halogen or another suitable leaving group such as triflate or tosylate and the other is OH or a suitable salt therof and m and Y are as hereinbefore defined; under standard ether forming conditions. The thus formed ether compound may then be treated with an oxidising agent to convert the thio group into a sulphinyl group, to give a compound of formula (I).

If the compound of formula (VLLI) is a racemic compound, this will lead to a mixture of diastereoisomers. Oxidation of the thio group will create a further chiral centre and the resultant distereoisomers may be separated by fractional crystallisation and/or chromatography. Individual enatiomers may then be obtained by chiral chromatography.

Suitable compounds of formula (VLTI) may be prepared by analogy with the processes described in WO 97/02242.

Compounds of formula (I) which are in vivo hydrolysable pharmaceutically acceptable esters may be conveniently prepared from the corresponding parent acid by a process which compromises treating the corresponding parent acid or a salt, alkyl ester or activated derivative thereof;

The present invention will now be illustrated by the following examples. Chiral compounds are described as 4R or 4S, SR or SS where the 4 describes the centre at the C4 position in the azetidinone and the S describes the sulfoxide centre. Diastereoisomer 1 derived from a 4R sulfide has the configuration 4R, SR. The corresponding diastereoisomer 2 is 4R, SS. Such configurations are by extrapolation , based on their ^X H NMR spectra, from configurations obtained initially by x-ray analysis of a limited number of compounds. The absolute configuration at the chiral α-carbon, when one of R ² and R is hydrogen and the other is methyl, is described as α-R or oc-5.

W

Example 1 - (R)-N-[6-(4-FluorophenyI)hex-l-yl]-4-(4- alloxycarbonylbenzylthio)-2-oxoazetidin-l-yl)acetamide a. Allyl 4-(bromomethyl)benzoate

4-(Bromomethyl)benzoic acid (103 g, 0.48 moles)was suspended in thionyl chloride (200 ml) and dimethylformamide (1 ml) was added. The mixture was heated under reflux until clear, evaporated and azeotroped with toluene (2 x 150 ml). The resulting oil was dissolved in dichloromethane and added dropwise to a cooled solution of pyridine (42 ml) and allyl alcohol (40 ml) in dichloromethane. The mixture was stirred at room temperature for 1 hour, then washed with water, 2M hydrochloric acid, sodium hydrogen carbonate solution and brine. The organic solution was dried and evaporated to give allyl 4-(bromomethyl)benzoate as a clear oil (98g, 84% yield). Η NMR d (CDC1,) 4.61 (2H, s, CH ₂ ), 4.82 (2H, m, CH ₂ O), 5.34 (2H, m, CH.CH-), 6.05 (IH, m, CHCH.), 7.45 (2H, d, Ph-H), 8.03 (2H, d, Ph-H). b. Allyl 4-(acetylthiomethyl)benzoate

Allyl 4-(bromomethyl)benzoate (98 g, 0.4 moles) in dry dimethylformamide (100 ml) was added dropwise to a cooled suspension of potassium thioacetate (46 g, 0.4 moles) in dry dimethylformamide (200 ml). The cooling bath was removed and the mixture was stirred overnight. The rection mixture was poured into water and extracted with ethyl acetate (x3). The combined extracts were washed with water and brine. The mixture was dried and evaporated to give allyl 4- (acetylthiomethyl)benzoate as an orange oil (lOOg, 100% yield). 'H NMR d (CDC1,) 2.36 (3H, s, COCH ₃ ), 4.13 (2H, s, CH2), 4.82 (2H, m, CH ₂ O), 5.32 (2H, m, CH ₂ CH-), 6.05 (IH, m, CHCH ₂ ), 7.35 (2H, d, Ph-H), 7.98 (2H, d, Ph-H). c 4-(4-(AllyloxycarbonyI)benzyIthio)azetidin-2-one Allyl alcohol (27 ml) in dry tetrahydrofuran (50 ml) was added dropwise to a solution of potassium tørt-butoxide (4.93 g, 0.044 moles) in dry tetrahydrofuran (100 ml). After stirring for 5 minutes a solution of allyl 4- (acetylthiomethyl)benzoate (10.1 g, 0.04 moles) in dry tetrahydrofuran (100 ml) was added dropwise. After stirring for 15 minutes a solution of 4- acetoxyazetidin-2-one (5.16 g, 0.04 moles) was added dropwise. The mixture was stirred for 1 hour and evaporated. The residue was partitioned between ethyl acetate and water and the aqueouse was extracted with ethyl acetate. The combined extracts were washed with brine, dried and evaporated. Flash chromatography (silica gel, ethyl acetate-petrol) gave 4-(4- allyloxycarbonylbenzylthio)azetidin-2-one as an oil (9.1g, 82% yield). 'H NMR d (CDC1,) 2.84 (IH, dd, H3a), 4.31 (IH, dd, H3b), 3.88 (2H, s, S-CH2), 4.68 (IH, dd, H4), 4.78 (2H, m, CH ₂ O), 5.35 (2H, m, CH ₂ CH-), 6.05 (IH, m, CHCH ₂ ), 6.07 (IH, br. singlet, N-H), 7.40 (2H, d, Ph-H), 8.03 (2H, d, Ph-H). d. Methyl 4-(4-(AHyIoxycarbonyI)benzylthio)-2-oxoazetidin-l-ylacetate

To a stirring solution of 4-(4-(allyloxycarbonyl)benzylthio)azetidin-2-one (2.55 g, 9.2 mmol), tetrabutylammonium bromide (0.33 g, 1.02 mmol) and methyl bromoacetate (1.06 ml, 11.2 mmol) in dry tetrahydrofuran (40 ml) was added powdered potassium hydroxide (0.63 g, 11.2 mmol) keeping the reaction temperature below 30 by means of a cold water bath. After 2 h, the mixture was diluted with water and extracted three times with ethyl acetate. The combined extracts were dried (MgSO4) and evaporated and the residue chromatographed (fine silica, ethyl acetate-petrol) to give the title compound as a clear oil, yield 2.66 g (83%).

'H NMR δ (CDC1 ₃ ) 2.97 (IH, dd, H3a), 3.26, 4.07 (each IH, QfcCO, d), 3.42 (IH, dd, H3b), 3.70 (3H, s, CH3O), 3.81 (2H, s, SCH ₂ ).4.83 (2H, m, CifeO), 4.93 (IH, dd, H4), 5.35 (2H, m, CH.2CH), 6.03 (IH, m, CH.CH ₂ ), 7.39 (2H, d, Ph-H), 8.02 (2H, d, Ph-H) e. (+/-)-4-(4-(Allyloxycarbonyl)benzylthio)-2-oxoazetidin-l-yla cetic acid To a solution of methyl 4-(4-(aIlyIoxycarbonyl)benzylthio)-2-oxoazetidin-l- ylacetate (2.17 g, 6.21mmol) in tetrahydrofuran (20 ml) was added dropwise with cooling (ice bath) over 10 min a 1 molar aqueous solution of potassium hydroxide. After a further 30 min, the solution was diluted with water and extracted twice with ether. The aqueous layer was then acidified (dil. hydrochloric acid) with cooling and the oil which precipited was extracted into ether. The combined extracts were dried (MgSO4) and evaporated to a clear oil which eventually crystallised under petrol and was filtered, washed and dried to give the title compound as white crystals, 1.87 g, 90% yield

Η NMR δ (CDC1 ₃ ) 2.98 (IH, dd, H3a), 3.34, 4.06 (each IH, CføCO, d), 3.42 (IH, dd, H3b), 3.82 (2H, s, SCH2).4.82 (2H, m, CH. ₂ 0), 4.92 (IH, dd, H4), 5.34 (2H, m, CH2CH), 6.03 (IH, m, CH.CH ₂ ), 7.39 (2H, d, Ph-H), 8.02 (2H, d, Ph-H) f. (-MR)-4-(4-(Allyloxycarbonyl)benzylthio)-2-oxoazetidin- 1-ylacetic acid 4-(4-(Allyloxycarbonyl)benzylthio)-2-oxoazetidin-l-ylacetic acid ( 3.41 g, 10.2 mmol) and cinchonidine (2.99 g, 10.2 mmol) in ethanol (40 ml) were heated to boiling when a clear solution was obtained. On standing for 90 min, the crystalline salt which had precipitated was filtered off, and recrystallised from ethanol (20 ml). The solid obtained was stirred vigorously with ether and water whilst acidifying with dil. hydrochloric acid, and when complete solution was obtained the layers were separated and the aqueous layer further extracted with ether. The combined extracts were dried (MgSO4) and evaporated to an oil which crystallised on trituration with light petrol to give the title compound as white crystals, m.p. 74-6°C, 6.7 g, 50% yield a/ = -24.2 (c. 0.7 w/v CHC1 ₃ , 25°C)

'H NMR δ (CDC1 ₃ ) 2.97 (IH, dd, H3a), 3.26, 4.07 (each IH, CH2CO, d), 3.42

(IH, dd, H3b), 3.70 (3H, s, CH.3O), 3.81 (2H, s, SCH.2). 4.83 (2H, m, CH2O),

4.93 (IH, dd. H4), 5.35 (2H, m, CH2CH), 6.03 (IH, m, CHCH ₂ ), 7.39 (2H, d,

Ph-H), 8.02 (2H, d, Ph-H) g. (R)-N-[6-(4-FluorophenyI)hex-l-yI]-4-(4-alloxycarbonyIbenzyl thio)-2- oxoazetidin-l-yl)acetamide

To a cooled (ice bath) solution of (R)-4-(4-(allyloxycarbonyl)benzylthio)-2- oxoazetidin-1-ylacetic acid (12.51 g, 0.0373 mol), 1-hydroxybenzotriazole hydrate (5.04 g, 0.0373 mol) and 6-(4-fluorophenyl)hexylamine (0.0373 mol) in dry dimethylformamide (150 ml) was added with stirring dicyclohexylcarbodiimide (7.29 g, 0.0373 mol). After 20 min the cooling bath was removed, and after a further 16 h, the solvent was evaporated under reduced pressure and the residue treated with ethyl acetate and the insoluble precipitate filtered off and discarded. The filtrate was further diluted with ethyl acetate, washed with 0.2 M hydrochloric acid, then saturated sodium hydrogen carbonate, dried and evaporated under reduced pressure. The residue was triturated with ethyl acetate/light petrol to give the title compound as white crystals, m.p. 54- 7°C, 17 g, 89% yield Η NMR δ (CDC1 ₃ ) 1.30-1.60 (8H, m, 4xCH ₂ ), 2.55 (2H, t, J=7.6 Hz, CH ₂ Ph),

2.90, 2.97 (IH, dd, J=2.4, 15.4 Hz, H ₃ ), 3.23 (2H, m, NHCH ₂ ), 3.35, 3.41 (IH, dd, J=5.1, 15.4 Hz, H ₃ ), 3.53, 3.78 (each IH, d, J=16.6 Hz, NCH ₂ ), 3.86 (2H, s, SCH ₂ ), 4.83 (3H, m, CO ₂ CH ₂ , H _< ), 5.37 (2H, m, CH ₂ =CH). 6.0 (2H, m, NH, CH ₂ =CH), 6.94 (2H, m, 4-FPh-H), 7.10 (2H, m, 4-FPh-H), 7.39 (2H, d, J=8.3 Hz, 4-CO ₂ allylPh-H), 8.02 (2H, d. J=8.3 Hz. 4-CO ₂ allylPh-H)

Example 2 - (4R, SS)-N-[6-(4-FluorophenyI)hex-l-yI]-4-(4- alloxycarbonylbenzylsuIphinyI)-2-oxoazetidin-l-yl)acetamide

A solution of (R)-N-[6-(4-fluorophenyl)hex-l-yl]-4-(4- alloxycarbonylbenzylthio)-2-oxoazetidin-l-yl)acetamide (16.36 g, 0.0319 mol) in dichloromethane (150 ml) was cooled to -65 to -70 and a solution of m- chloroperbenzoic acid (6.61 g, 0.0383 mol) in dichloromethane (120 ml) added dropwise with stirring over 20 min. After 1 h, the mixture was washed with saturated sodium metabisulphite solution, then saturated sodium hydrogen carbonate, then dried (MgSO4) ^d evaporated to a solid which was recrystallised from ethyl acetate to give a mixture of diastereoisomers 2 and 1 in the ratio 3:2. Chromatographic separation (HPLC) gave diastereomer 2 (4R, SS) as a white crystalline solid, m.p. 133-5°C, 3.3 g, 20% yield a/* = +74.0 (c. 0.6% w/v CHC1,. 25°C) Η NMR δ (CDC1 ₃ ) 1.30-1.60 (8H, m, 4xCH ₂ ), 2.56 (2H. t, J=7.6 Hz, CH ₂ Ph),

2.91, 2.95 (IH, dd, J=2.4, 15.2 Hz, H ₃ ), 3.27 (3H, m, NHCH ₂ . H ₃ ). 3.94, 4.22 (each IH, d, J=17.2 Hz, NCH ₂ ), 4.04, 4.18 (each IH, d, J=12.8 Hz, SOCH ₂ ), 4.65 (IH, m, HJ, 4.84 (2H, m, CO ₂ CH ₂ ), 5.37 (2H, m, CH ₂ =CH), 6.0 (IH, m,

CH ₂ =CH), 6.95 (3H, m, 4-FPh-H, NH),). 7.10 (2H, m, 4-FPh-H), 7.36 (2H, m, 4-CO ₂ allylPh-H), 8.09 (2H, m, 4-CO ₂ allylPh-H).

Example 3 - (4/?, SR)-N-[6-(4-FluorophenyI)hex-l-yl]-4-(4- alloxycarbonyIbenzylsuIphinyl)-2-oxoazeudin- 1 -yl)acetamide

From the HPLC chromatography described in Example 2 above the other diastereoisomer (Dia 1: 4R, SR) was obtained as a white crystalline solid (1.8 g,

11% yield) m.p. 175-7°C

^ = -119.7 (c. 0.5% w/v CHCl,, 25°C)

'H NMR δ (CDC1,) 1.30-1.60 (8H, m, 4xCH ₂ ), 2.55 (2H, t, J=7.6 Hz, CH ₂ Ph),

2.95. 2.98 (IH, dd, J=4.8, 14.8 Hz, H3), 3.24 (2H, m, NHCH ₂ ), 3.42, 3.46 (IH, dd, J=2.4, 14.8 Hz, H3), 3.76, 4.09 (each IH, d, J=17.2 Hz, NCH ₂ ), 3.95, 4.01 (each IH, d, J=13.2 Hz, SOCH ₂ ), 4.59 (IH, m. H4), 4.84 (2H, m, CO ₂ CH ₂ ), 5.37 (2H, m, CH ₂ =CH), 6.0 (IH. m, CH ₂ =CH). 6.53 (IH, m, NH), 6.95 (2H, m, 4- FPh-H), 7.10 (2H, m, 4-FPh-H), 7.36 (2H, d, J=8 Hz, 4-CO ₂ allylPh-H), 8.09 (2H, d, J=8 Hz, 4-CO ₂ allylPh-H).

Example 4 - (4R, S5)-N-f6-(4-Fluorophenyl)hex-l-yI]-4-(4- carboxybenzylsuIphinyI)-2-oxoazetidin-l-yl)acetamide

A solution of (4R, SS)-N-[6-(4-Fluorophenyl)hex-l-ylj-4-(4- alloxycarbonylbenzylsuIphinyl)-2-oxoazetidin- l-yl)acetamide (Example 2) (0.185 g, 0.35 mmol), triphenylphosphine (0.092 g, 0.35 mmol), pyrrolidine (0.033 ml, 0.4 mmol) and tetrakis triphenylphosphinepalladium(O) (0.012 g, 0.01 mmol) in dichloromethane (10 ml) was stirred under nitrogen for 16 h. A further 0.012 g (0.01 mmol) of tetrakis triphenylphosphinepalladium(O) was added and after a further 4 h the reaction was complete. The solution was diluted with water, acidified (2N HCl), the layers separated and the aqueous layer further extracted with dichloromethane. The combined extracts were dried (MgSO4)and evaporated to a yellow oil, which was triturated with ether. A yellow solid was obtained which was filtered off and dissolved in sodium hydrogen carbonate solution. Shaking with ether gave an emulsion which was separated by treatment with ethyl acetate and centrifugation. The aqueous layer was then acidified (2N HCl) and extracted with dichloromethane, and the extracts dried (MgSO4)and evaporated. The residue was triturated with ether to give a white solid which was filtered, washed and dried to give the title compound as a white solid, m.p. 105- 7°C, 0.1 g, 58% yield a _t , ^25"0 = -31.7 (c. 0.5% w/v DMSO, 25°C) Η NMR δ (DMSO) 1.26 (4H, m, 2xCH ₂ ). 1-38 (2H, m, CH ₂ ), 1-50 (2H, m, CH,),

2.96. 2.99 (IH, dd, J=2, 15.2 Hz, HJ, 3.06 (2H, m, NHCH ₂ ), 3.84, 4.09 (each lH. d, J=17.2 Hz, NCH ₂ ), 4.13, 4.31 (each IH, d, J=12.8 Hz, SOCH ₂ ), 4.84

(IH, m, HJ, 7.05 (2H, m.4-FPh-H).7.19 (2H, m, 4-FPh-H).7.47 (2H. d. J=8 Hz, 4-CO ₂ allylPh-H), 7.93 (2H, d, J=8 Hz, 4-CO ₂ allylPh-H), 8.13 (IH, m, NH), 13 (IH, bs, CO _j H).

Example 5 - (-)-(4K, S5)-N-[6-(4-Fluorophenyl)hex-l-yI]-4-(4- carboxybenzylsuIphinyl)-2-oxoazetidin-l-yl)acetamide, sodium salt

A mixture of N-[6-(4~fluorophenyl)hex- l-yl]-4-(4-carboxybenzylsulphinyl)-2- oxoazetidin-l-yl)acetamide (0.51 g) and sodium bicarbonate (0.088 g) in water (15 ml) was sonicated for 5 min, methanol added (20 ml) and the mixture sonicated for a further 20 min. After filtration the solution was evapotated to a low volume, diluted with water and lyophilised to give the title compound as a white powder (0.52 g), m.p. 238-40°C. a,, = -31.7° (c 0.5, DMSO)

Example 6 - 4R, S5-N-(6-(4-Fluorophenyl)hexyl)-4-(4- ethoxycarbonylbenzylsulphinyl)-2-oxoazetidin-l-ylacetamide a. Ethyl 4-(bromomethyl)benzoate

4-(Bromomethyl)benzoic acid (25.75g, 0.1197moles) was suspended in thionyl chloride (50ml) and dimethylformamide (0.25ml) was added. The mixture was heated under reflux for 25 minutes until clear, evaporated and azeotroped with toluene (x2). The resulting oil was dissolved in dichloromethane (75ml) and added dropwise over 10 minutes to a solution of absolute alcohol (8.6ml, 0.1465moles), pyridine (10.5ml, 0.1298moles) in dry dichloromethane (50ml), cooled to 10°C. The ice bath was removed and the reaction was stirred for 45 minutes , then washed with water, 2NHC1, water, sodium hydrogen carbonate solution and brine. The organic solution was dried (MgSO4) and evaporated to give a mixture of 60:40 ethyl 4-(bromomethyl)benzoate: ethyl 4- (chloromethyl)benzoate as an oil (25.6g, 94%)

!H nmr δ (CDC1 ₃ ) 1.40 (3H, m, CH3), 4.40 (2H, m, CH2O), 4.50, 4.61 (2H, 2xs, CH2C1/Br), 7.45 (2H, m, Ar-H), 8.01 (2H, m, Ar-H) b. Ethyl 4-(acetylthiomethyI)benzoate

60:40 Ethyl 4-(bromomethyl)benzoate: ethyl 4-(chloromethyl)benzoate (25.0g, 0.111 moles) in dry dimethylformamide (150ml), cooled to 5°C, was treated with potassium thioacetate (13.3g, 0.117moles) and the temperature rose to 20°C. The reaction was stirred at room temperature for 2 hours, poured into water (250ml) and extracted with diethyl ether (3x100ml). The organic extracts were combined, washed with water, dried (MgSO4), charcoaled and evaporated to give ethyl 4- (acetylthiomethyl)benzoate as a brown soild (26.0g, 99%), m.p. 36-37°C. ^l H nmr δ (CDCI3) 1.38 (3H, t, J=7.1Hz, CH3). 2.36 (3H, s, COCH3). 4.14 (2H, s, CH2S), 4.36 (2H, q, CH2O). 7.35 (2H, d, J = 8.2Hz, Ar-H), 7.97 (2H, d, J= 8.2Hz, Ar-H)

c 4-(4-(Ethoxycaτbonyl)benzylthio)azetidin-2-one

A solution of sodium (1.87g, 0.0813moles) in absolute alcohol (300ml) was treated with a solution of ethyl 4=(acetylthiomethyl)benzoate (19.4g, 0.0814moles) in absolute alcohol (75ml) over 3 minutes. The reaction was stirred at room temperature for 30 minutes, cooled to -5°C and treated with a solution of 4-acetoxyazetidin-2-one (lO.Og, 0.07745moles) over 5 minutes. The cooling bath was removed and reaction was stirred for 2 hours, evaporated to dryness and treated with brine (200ml) and extracted with ethyl acetate (200ml, 100ml). The organic extracts were combined washed with brine, dried (MgSO4) and evaporated to a red oil. Purified by flash column chromatography on silica gel eluted with 3:1 to 1:2 petroleum ether 40-60°C:ethyl acetate to give 4-(4- (ethoxycarbonyl)benzylthio)azetidin-2-one as an orange oil (18.64g, 91%). lH nmr δ (CDC1 ₃ ) 1.38 (3H, t, J=7.1Hz, CH3), 2.82, 2.89 (IH, 2xm, H3), 3.29, 3.35 (IH, 2xm, H3), 3.88 (2H, s, CH2S), 4.37 (2H, q, CH2O), 4.70 (IH, m, H4), 5.70 (lH,bs, NH), 7.40 (2H, d, J = 8.3Hz, Ar-H), 8.00 (2H, m, Ar-H) d. Methyl (4-(4-ethoxycarbonyI)benzylthio)-2-oxoazetidin-l-ylacetate

A stirred solution of 4-(4-(ethoxycarbonyl)benzylthio)azetidin-2-one (217.3g, 0.819mol), methyl bromoacetate (128.5g,0.84mol) and tetrabutylammonium bromide (25.8g,0.08mol) in dry THF (900ml) was cooled in an ice bath to 20°C and finely ground potassium hydroxide (48.3g, 0.86mol) was added in one portion. The reaction exothermed to 45°C and was allowed to cool back to 30°C when the ice bath was removed and stirring continued for lhr. More potassium hydroxide (2.4g, 0.043mol) was added and stirred 30mins when this addition was repeated. After a further 30mins, the reaction mixture was filtered through hyflo, washing with more THF. The combined organics were evaporated to a red oil. Ether (11) was added an shaken well. The ether was decanted and the process repeated. The combined ether extracts were evaporated to give the title compound as a dark red oil (199.8g, 72% yield)

^! H NMR δ (CDC1 ₃ ), 1.40 (3H, t, J=7Hz, CH2CH3), 2.98 (IH, dd, J=2, 15 Hz, H ₃ ). 3.26, 4.03 (each IH, d, J=18 Hz, NCH ₂ ), 3,42 (IH, dd, J=5. 15 Hz, H ₃ )» 3.70 (3H, s, OCH ₃ ), 3.81, (2H, m, SCH2). ⁴ -38 (2H, q, J=7 Hz, OCH ₂ ), 4.93 (IH, m, HJ, 7.39 (2H, m, Ph-H ), 7.99 (2H, m, Ph-H )• e. (4-(4-Ethoxycarbonyl)benzylthio)-2-oxoazetidin-l-ylacetic acid Methyl (4-(4-ethoxycarbonyl)benzylthio)-2-oxoazetidin- 1 -ylacetate (169.8g,0.503mol) was disolved in THF (750ml), cooled to 0°C and a solution of potassium hydroxide (29.7g, 0.529mol) in water (500ml) was added over 15min at 0 - 5°C then the mixture was stirred at 0°C for 45mins. Ether (11) and water (21) were added, the layers separated and the aqueous washed with ether (11), then acidified with cone hydrochloric acid (55ml) and extracted with dichloromethane

(2 x 11). The combined extracts were washed with brine, dried (MgSO4) and evaporated to give the title compound as a green solid (128.4g, 79% yield). f. (-)-R-(4-(4-Ethoxycarbonyl)benzylthio)-2-oxoazetidin-l-ylace tic acid 4-(4-Ethoxycarbonyl)benzylthio)-2-oxoazeyidin- 1-ylacetic acid (46.0g, 0.1422moles) and (-)-cinchonidine (41.88g, 0.1423moles) were dissolved in abolute alcohol (450ml). The solution was cooled for 1.5 hours, filtered, and dried to give the salt as a cream solid (33.15g). This solid was recrystallised from absolute alcohol (300ml) to give 23.6g of salt which was mixed with water (500ml) and diethyl ether (500ml) and acidified with dilute HCl (50ml). When all the solid had dissolved the layers were separated and the aquous layer was extracted with ether (250ml). The organic extracts were combined, ethyl acetate (100ml) was added and washed with water, dried (MgSO4), filtered and evaporated to give R-(4-(4-ethoxycarbonyl)benzylthio)-2-oxoazetidin- 1-ylacetic acid as a colourless solid. (10.93g, 23.8%) m.p. 135-137°C. a _D = -23.5 (c = 0.46 w/v in chloroform at 25°C)

Η NMR δ (CDC1 ₃ ) 1.39 (3H, t, J=7.1Hz, CH3), 2.96, 3.02 (IH, dd, J =2.2, 15.3

Hz, H3), 3.33, 4.05 (each IH, d, J=18.4 Hz, NCH2CO2H), 3.40, 3.46 (IH, dd,

J= 5.1, 15.3 Hz, H3). 3.82 (2H, s, SCH2), 4.37 (2H, q, CO ₂ CH2), 4.68 (IH, b,

CO ₂

H), 4.92 (IH, m, H4), 7.38 (2H, d, J=8.2Hz, Ph-H), 7.99 (2H. d, J=8.2Hz. Ph-

H) g. 4R,SR-(4-(4-EthoxycarbonyI)benzylsulphinyl)-2-oxoazetidin-l- yIacetic acid (diastereoisomer 1) h. 4R,S5-(4-(4-Ethoxycarbonyl)benzylsulphinyI)-2-oxoazetidin-l- ylacetic acid (diastereoisomer 2)

A solution of (-)-R-(4-(4-ethoxycarbonyl)benzylthio)-2-oxoazetidin- 1-ylacetic acid (10.81g, 0.03343moles) in dry dichloromethane (400ml) at -70°C was treated with ozone until a blue colouration appeared. The reaction was allowed to warm to room temperature and dichloromethane (50ml) was added to aid stirring. The solution was evaporated to dryness and the resulting soild was mixed with chloroform (200ml). The colourless solid was collected by filtration to give 4R,SR-(4-(4-ethoxycarbonyl)benzylsulphinyl-2-oxoazetidin-l-y lacetic acid (4.1 lg, 36%) m.p.l62-164°C. (contains 15.8:1 dial:dia2)

'H NMR δ (DMSO) 1.33 (3H, t, J=7Hz, CH3), 2.97, 3.04 (IH, dd, J=4.8,14.8Hz, H3), 3.12, 3.16 (IH, dd, J= 1.6, 14.8Hz. H3), 3.83. 4.17 (each IH, d, J= 18Hz, NCH2CO2H), 4.92, 4.24 (IH, d, J = 12.8Hz, SOCH2), 4.32 (2H, q, CO ₂ CH2). 4.99 (IH, m, H4). 7.48 (2H, d. J=8.0Hz, Ph-H), 7.96 (2H, d, J=8.0Hz, Ph-H) The filtrate from the above was evaporated, mixed with diethyl ether and filtered to give 4R,S5-(4-(4-ethoxycarbonyl)benzylsulphinyl-2-oxoazetidin- 1 -ylacetic acid (6.42, 56%) m.p. 152-155°C. (contains 92:8 dia2:dial)

'H NMR δ (DMSO) 1.33 (3H, t, J=7 Hz, CH3). 2.97, 3.01 (IH, dd, J=2.0,15.5Hz, H3), 3.35 (IH, m, H3). 3.95, 4.17 (each IH, d, J= 18.2Hz, NCH2CO2H), 4.15 (IH, d, 1 of SOCH2).4.32 (3H, m, 1 of SOCH2- CO ₂ CH2>. 4.82 (IH, m, H4), 7.51 (2H, d, J=8.2Hz, Ph-H), 7.97 (2H, d, J=8.2Hz, Ph-H) i. (+)-4ff, SS-N-(6-(4-FluorophenyI)hexyI)-4-(4- ethoxycarbonyIbenzylsulphinyI)-2-oxoazeridin- 1 -ylacetamide 6-(4-Fluorophenyl)hexylamine (1.82g, 0.00932moles) in dry dimethylformamide (75ml) was added to a mixture of 4R,SS -(4-(4-ethoxycarbonyl)benzylsulphinyl- 2-oxoazetidin- 1-ylacetic acid (3.15g, 0.00928moles), N.N.- dicyclohexylcarbodiimide (1.92g, 0.00931moles) and 1-hydroxybenzotriazole (1.25g, 0.00925moles). The reaction was stirred at room temperature for 3.5 hours, diluted with ethyl acetate (100ml) and cooled. The mixture was filtered to remove urea and the filtrate was evaporated to dryness. The residue was dissolved in ethyl acetate (400ml), washed with sodium hydrogen carbonate solution, brine, dried and evaporated to a colourless solid (5.8g) which was recrystallised from ethyl acetate (125 ml) to give the product (3.0g). Purification by column chromatography gave 4R.SS -(4-(4- ethoxycarbonyl)benzylsulphinyl-2-oxoazetidin- 1-ylacetic acid as a colourless solid, 155-156°C. 1.8 g, 38% yield

Η NMR δ (CDC1 ₃ ) 1.3-1.6 (1 IH, m, 4xCH.2, CH3), 2.56 (2H, t, J = 7.6Hz, CH2Ph), 2.89, 2.96 (IH, dd, J=2.4,15.3Hz, H3). 3.25 (3H, m, NHCH2. H3), 3.94, 4.22 (each IH, d, J=17Hz, NCH2CO), 4.03, 4.18 (each IH, d, J=12Hz, SOCH2), 4.39 (2H, q, CO2CH2), 4.65 (IH, m, H4), 6.9-7.12 (5H, m, NH.p- ClPh-H), 7.35 (2H, d, J=8.3Hz, Ph-H), 8.07 (2H, d, J=8.3Hz, Ph-H) ^ = +85.2 (c = 0.5% w/v in chloroform at 25°C)

Found: C, 62.6; H, 6.3; N, 5.4%; C2 ₇ H33FN2O5S requires: C, 62.8; H, 6.4; N, 5.4%

Example 7 - (+)-4R, SS-N-(6-(4-ChIorophenyl)hexyl)-4-(4- ethoxycarbonyIbenzyIsulphinyl)-2-oxoazetidin-l -ylacetamide

Treatment of 4R,S5-(4-(4-ethoxycarbonyl)benzylsulphinyl-2-oxoazetidin- 1- ylacetic acid with 6-(4-chlorophenyl)hexylamine, N,N-dicyclohexylcarbodiimide, and 1-hydroxybenzotriazole in dry dimethylformamide as described for Example 6 above, followed by the same work-up procedure gave the title compound as a colourless solid, 159-161°C, 45% yield

Η NMR δ (CDC1 ₃ ) 1.3-1.6 (11H, m, 4xCH2, CH3), 2.56 (2H, t, J = 7.6Hz, OfePn), 2.89, 2.95 (IH, dd, J=2.4,15.3Hz, H3), 3.25 (3H, m, NHCH.2> H3), 3.94, 4.24 (each IH, d, J=17Hz, NCH2CO), 4.03, 4.18 (each IH, d, J=12Hz, SOCH2).4.36 (2H, q. CO2CH2), 4.65 (IH, m, H4), 7.04 (IH, m, NH), 7.06-7.26 (4H, m, p-ClPh-H), 7.35 (2H, d, J=8.3Hz, Ph-H), 8.07 (2H, d, J=8.3Hz. Ph-H)

a,, = +83.9 (c = 1.0% w/v in chloroform at 25°C)

Found: C, 60.9; H, 6.1; N, 5.2%; C27H33CIN2O5S requires: C, 60.8; H, 6.2; N,

5.3%

Example 8 - (+)-4R, S5-N-(6-(4-Fluorophenyl)hexyl)-4-(4- e thoxy carbonylbenzylsulphinyl)-2-oxoazetidin-l-ylacetaιnide a. p-Methoxybenzyl [(35, 4R)-4-acetylthio-3-bromo-2-oxoazetidin-l- yljacetate

Ozonised oxygen was bubbled through a solution of p-methoxybenzyl 2-[(35, 4R)-4-acetylthio-3-bromo-2-oxoazetidin- 1 -yl]-3-methylbut-2-enoate (Osborne N. F. et al., J. Chem. Soc., Perkin Trans. 1, 1994, 179) (20.16 g, 0.0456 mol) in ethyl acetate (400 ml) at -65 to -70°C until a permanent blue solution was obtained. Excess ozone was removed by the passage of oxygen, then trimethyl phosphite (53.8 ml, 0.456 mol) was added dropwise. After 15 min. the solution was allowed to warm to room temperature, then stood for 16 hr. The solvents were evaporated and the residue reevaporated twice from toluene.then dissolved in ethyl acetate (300 ml) and stirred vigorously for 1.5 hr. with a solution of p- toluenesulphonic acid (2 g) in water (100 ml). After dilution with water the organic layer was separated and the aqueous layer further extracted with ethyl acetate. The combined extracts were washed successively with saturated aq. sodium hydrogen carbonate and brine, then dried (MgSO ₄ ) and evaporated. Purification by flash chromatography (silica, ethyl acetate-pet. ether) gave the title compound as a light brown oil, yield 10.6 g (58%). b. Silver (35,4Λ)-3-bromo-l-(p-methoxybenzyloxycarbonylmethyI)-2- oxoazetidine-4-thiolate

A solution of p-methoxybenzyl [(35, 4R)-4-acetylthio-3-bromo-2-oxoazetidin-l- yl]acetate (4.13 g, 0.01 mol) in methanol (90 ml) was added with stirring in subdued light to a solution of silver nitrate (2.27 g, 0.0133 mol) in methanol (90 ml). Triethylamine (1.87 ml, 0.0133 mol) was then added with ice cooling, and stirring continued for 1 hr. at 5-10°C followed by 30 min. at room temperature. The mixture was re-cooled (ice bath) and the precipitated solid filtered and washed twice with ice cold methanol then hexane to give the title compound, yield 4.6 g (96%). c 4-Carbethoxybenzyl iodide

Treatment of 4-carboxybenzylbromide with thionyl chloride followed by ethanol in pyridine have a mixture of 4-carbethoxybenzyl chloride and bromide which was treated (14.6 g) with sodium iodide (39.8g) in acetone (150ml) at reflux temperature for 20hrs. The mixture was cooled, filtered and the solvent evaporated off. The residue was taken up in ether (150ml) and washed with

water, aqueous sodium thiosulphate, water, brine, dried and evaporated to give the title compound as a pale yellow solid, m.p. 61-3°C, 17.5 g (91% yield). Η NMR δ (CDC1 ₃ ) 1.39(3H, t, J=7.1 Hz, CH3), 3.37(2H, q, J=7.1 Hz, CH2CH3), 4.46(2H, s, CH2D, 7.43 (2H, m, 3,5-Ph-H), 7.96(2H, m, 2,6-Ph-H) d. p-Methoxybenzyl [(35, 4R)-4-(4-carbethoxy)benzylthio-3-bromo-2- oxoazetidin- l-yl]acetate

A solution of silver (35,4R)-3-bromo-l-(p-methoxybenzyloxycarbonylmethyl)-2- oxoazetidine-4-thiolate (2.34g, 0.005mol) in acetonitrile (20 ml) was treated with a solution of 4-carbethoxybenzyl iodide (1.74g, O.OOόmoI) in acetonitrile (10ml) and the mixture stirred in subdued light for 2.5hrs. The mixture was filtered through hyflo, the filtrate evaporated and the residue purified by flash chromatography (silica, ethyl acetate-pet. ether) to give the title compound as a white solid, m.p. 97-9°C, 1.60g (61% yield).

1H NMR δ (CDC1 ₃ ), 1.39(3H, t, J=7.1Hz, CH2CH3), 3.48, 4.07 (each IH, d, J=18 Hz, NCH2). 3.80 (5H, s, SCH2 + OCH ₃ ), ⁴ -37 (2H, q, J=7.1Hz, CH2CH3), 4.61, 4.91 (each IH, d, J=1.6 Hz, H ₃ +H ₄ ), 5.03, 5.12 (2H, 2xd, J=11.8Hz, OCH2), 6.89 (2H, m, 3,5-(4-CH ₃ OPh)-H), 7.26-7.41 (4H, m, 2,6-(4-CO ₂ Et)Ph-H + 2.6-(4-CH ₃ OPh)-H), 8.00 (2H, m, 3,5-(4-CO2Et)Ph-H ). e. /*-MethoxybenzyI [(35, 4R)-4-(4-carbethoxy)benzyIsulphinyl-3-bromo-2- oxoazetidin-l-yI]acetate Diast 2:l 75:25 p-Methoxybenzyl [(35, 4R)-4-(4-carbethoxy)benzylthio-3-bromo-2-oxoazetidin- l-yl]acetate (15.2g, 0.029mol) was dissolved in dichloromethane (400ml), cooled to -65°C and a solution of m-chloroperbenzoic acid (8.9g,0.029mol) in dichloromethane (450 ml) added dropwise with stirring over 20 min. The cooling bath was removed and the mixture stirred at RT for 2hrs. The solution was shaken with a mixture of saturated aqueous sodium sulphite and saturated sodium hydrogen carbonate and the organic layer separated, washed with water, dried (MgSOJ and evaporated to an oil.

Hot ethyl acetate (60ml) was added and after cooling in freezer overnight, p- methoxybenzyl [(35, 4R)-4-(4-carbethoxy)benzylsulphinyl-3-bromo-2- oxoazetidin-l-yl]acetate crystallised out as a white solid as a 75:25 mixture of diastereomers (2:1), 9.94g, (63% yield) ^l H NMR of major component: δ (CDC1 ₃ ), 1.39(3H, t, J=7.1Hz, CH2CH3). 3.80 (3H, OCH3), 4.0 - 4.2 (3H, m, SOCH2 + NCH ₂ ), 4.3 - 4.4 (3H, m, CH2CH3 + NCH2), 4.50, 4.81 (each IH, d, J=1.7 Hz, H ₃ +U ₄ ), 5.1 (2H, m, OCH ₂ ), 6.88 (2H, m. 3,5-(4-CH ₃ OPh)-H), 7.26 (2H, m. 2,6-(4-CH ₃ OPh)-H), 7.41 (2H, m, 2,6-(4-CO ₂ Et)Ph-H ), 8.00 (2H, m. 3,5-(4-CO ₂ Et)Ph-H )• f. [(4R)-4-(4-carbethoxy)benzylsulphinyl-2-oxoazetidin-l-yl]ace tic acid Diast 2

p-Methoxybenzyl [(35, 4R)-4-(4-carbethoxy)benzylsulphinyl-3-bromo-2- oxoazetidin-l-yl]acetate (8.75g, 16.25mmol) was dissolved by warming in ethanol (400ml) and a solution of sodium bicarbonate (4.0g, 48mmol) in water (40ml) was added. To the cloudy mixture was added 10% Pd on carbon (0.5g) and the warm mixture (initial temp 40°C) was hydrogenated at 50psi, room temp for 2 hrs. More catalyst (l.Og) was added, the mixture warmed to 35°C and hydrogenated as above for 2 hrs. The mixture was filtered through hyflo and evaporated to give a mixture of p-methoxybenzyl and ethyl esters of the des- brorao derivative as brown oil. This was dissolved in ethanol (50ml), cooled to 10°C and IN sodium hydroxide (17ml) was added dropwise over lOmin. The mixture was stirred at 10°C for 45mins then most of the ethanol was evaporated off and the residue dissolved in dichloromethane and water. The layers were separated and the aqueous washed with dichloromethane then acidified with cone hydrochloric acid (2ml) and extracted with dichloromethane. The extracts were dried (MgSO4) with the addition of charcoal, filtered through hyflo and evaporated to a black foam. This was dissolved in chloroform and refrigerated overnight. A small amount of solid was filtered off and the filtrate evaporated to a black oil which solidified under ether to give the title compound as an off-white solid, 3.77g, (68% yield) (ratio of dia 2:dia 1 94:6). The chromatographic and spectral characteristics of this material identified it as the same compound prepared in Example 6h.

Η NMR δ (DMSO) 1.32 (3H, t, J=7Hz, CH3), 2.99 (IH, m, H3), 3.33 (IH, m, H3), 3.95 (IH, d, J= 18.2Hz, NCH2), 4.15 (2H, m, NCH2 + SOCH2), 4.34 (3H, m, SOCH2 + CO2CH2). 4.82 (lH, m, H4), 7.51 (2H, d, J=8.3Hz, Ph-H), 7.97 (2H, d, J=8.3Hz, Ph-H) g. [(4R)-4-(4-carbethoxy)benzylsulphinyl-2-oxoazetidin-l-yl]ace tic acid Diast 2

[(4R, S5)-4-(4-carbethoxy)benzylsulphinyl-2-oxoazetidin-l-yl]aceti c acid (Diast 2) was also prepared by the following procedure: p-Methoxybenzyl [(35, 4R)-4- (4-carbethoxy)benzylsulphinyl-3-bromo-2-oxoazetidin-l-yl]ace tate (Diast 2: 1 75:25) (4.59g, 8.52mmol) was dissolved in dichloromethane (50ml), cooled in an ice bath and activated zinc powder (1.1 lg, 17.05mmol) was added followed by glacial acetic acid (8ml). After 1 hr, the mixture was diluted with dichloromethane-water, and the organic layer washed with saturated aq. NaHCO ₃ , brine, dried (MgSO ₄ ) and evaporated to an oil which was purified by flash chromatography (silica, ethyl acetate-pet. ether) to give the title compound as an oil which solidified on standing. h. (+)-4Λ, S5-N-(6-(4-Fluorophenyl)hexyI)-4-(4- e thoxy carbonyIbenzylsuIphinyl)-2-oxoazetidin-l-ylacetamide

Treatment of [(4R)-4-(4-carbethoxy)benzylsulphinyl-2-oxoazetidin- l-yl]acetic acid with 6-(p-fluoropheny)lhexylamine under the conditions described for Example 6i gave, after chromatography, the title compound with identical spectral and chromatographic characteristics to that prepared in Example 6i. a^ = +71.9 (c. 1.0% w/v CHCL _. , 25°C)

Example 9 - (4R, S5)-N-(6-[4-Fluorophenyl]heχ.l-yl)-4-(4- (cyclohexyloxycarbonyIoxymethyloxycarbonyl)benzylsulphinyI)- 2- oxoazetidin- 1 -yl)acetamide

A solution of (4R, S5)-N-(6-[4-fluorophenyl]hex-l-yl)-4-(4- carboxybenzylsulphinyl)-2-oxoazetidin-l-yl)acetamide (see above, 4 g, 0.00819 mol) and iodomethyl cyclohexyl carbonate (3.49 g. 0.0123 mol) in N- methylpyrrolidinone (40 ml, dried over 4A molecular sieves) was treated with anhydrous potassium carbonate (1.7 g, 0.0123 mol) and stirred for 16 h at ambient temperature. The mixture was diluted with water and extracted thoroughly with ethyl acetate, and the combined extracts washed with 5% aq. sodium thiosulphate, dried (MgSO4) and evaporated. The residue was purified by chromatography (fine silica, ethyl acetate) and the title compound obtained as white crystals m.p.l05-7°C after trituration with ether/light petrol, 4.16 g, 79% yield lH NMR δ (DMSO) 1.23-1.51 (14H, m), 1.64 (2H, m), 1.84 (2H, m), 2.51 (2H, m), 3.04 (3H, m). 3.35 (IH, m), 3.83 and 4.09 (each IH, d), 4.15 and 4.35 (each IH, d), 4.58 (IH, m), 4.85 (IH, m), 5.95 (2H, s), 7.05 (2H, m), 7.18 (2H, m), 7.53 (2H, d), 7.98 (2H, d), 8.11 (IH, bt).

Found: C, 61.6; H, 6.4; N,4.6%; C ₃₃ H ₄₁ FN ₂ O _g S requires: C, 61.5; H, 6.4; N, 4.3%

Example 10 - (4/f, S5)-N-(6-[4-FluorophenyI]hex-l-yl)-4-(4-(tert- butyloxycarbonyIoxymethyloxycarbonyl)benzyIsulphinyI)-2-oxoa zetidin-l- yl)acetamide

A solution of (4R, S5)-N-(6-[4-fluorophenyl]hex-l-yl)-4-(4- carboxybenzylsulphinyl)-2-oxoazetidin-l-yl)acetamide (0.2g, 0.00041 mol) and iodomethyl tert-butyl carbonate (0.49 g. 0.001 mol) in N-methylpyrrolidinone (2 ml, dried over 4A molecular sieves) was treated with anhydrous potassium carbonate (0.14 g, 0.001 mol) and stirred for 16 h at ambient temperature. The mixture was diluted with water and extracted thoroughly with ethyl acetate, and the combined extracts washed with aq. sodium sulphite, dried (MgSO4) and evaporated. The residue was crystallised by trituration with light petrol to give the title compound as white crystals m.p.l02-4°C, 0.23 g, 92%yield

Η NMR δ (DMSO) 1.25-1.52 (17H, m), 2.50 (2H, m), 3.06(3H, m), 3.35 (IH, m), 3.84 and 4.09 (each IH, d), 4.15 and 4.35 (each IH, d), 4.86 (IH, m), 5.90 (2H, s), 7.06 (2H, m), 7.18 (2H, m), 7.53 (2H, d), 7.97 (2H, d), 7.99 (IH, bt) Found: C, 60.1; H, 6.3; N, 4.7%; C ₃₁ H3 ₉ FN ₂ O _g S requires: C, 60.2; H, 6.4; N, 4.5%

Example 11 - (4Λ, S5)-N.(6.[4-πuorophenyl]hex-l-yl)-4-(4-(l- methylcyclohexyIoxycarbonyloxymethyloxycarbonyI)benzylsulphi nyl)-2- oxoazetidin- l-yl)acetamide

A solution of (4R, S5)-N-(6-[4-fiuorophenyl]hex-l-yl)-4-(4- carboxybenzylsulphinyl)-2-oxoazetidin-l-yl)acetamide (0.2g, 0.00041 mol) and chloromethyl 1-methylcyclohexyl carbonate (0.21 g. 0.001 mol) in N- methylpyrrolidinone (2 ml, dried over 4A molecular sieves) was treated with anhydrous potassium carbonate (0.14 g, 0.001 mol) and potassium iodide (0.166 g, 0.001 mol) and stirred for 16 h at ambient temperature. The mixture was diluted with water and extracted thoroughly with ethyl acetate, and the combined extracts washed with aq. sodium thiosulphate, dried (MgSO4) and evaporated. The residue was purified by flash chromatography (fine silica, ethyl acetate) and the material thus obtained crystallised by trituration with ether, to give the title compound as yield white crystals, m.p. 92-3°C, 0.11 g, 41% yield *H NMR δ (DMSO) 1.25- 1.48 (16H, m), 2.00 (2H, m), 2.5 (5H, m), 3.07 (3H, m), 3.36 (IH, m), 3.83 and 4.09 (each IH, d), 4.15 and 4.35 (each IH, d), 4.86 (IH, m), 5.91 (2H, s), 7.06 (2H, m), 7.18 (2H, m), 7.54 (2H, d), 7,98 (2H, d), 8.11 (lH, bt)

Example 12 - (4R, S5)-N-(6-[4-FIuorophenyl]hex-l-yl)-4-(4-

(phenylcarbonyloxymethyloxycarbony])benzylsulphinyI)-2-ox oazetidin-l- yl)acetamide

A solution of (4R, S5)-N-(6-[4-fluorophenyl]hex-l-yl)-4-(4- carboxybenzylsulphinyl)-2-oxoazetidin-l-yl)acetamide (5 g, 0.0102 mol) and benzoyloxychloromethane (2.62 g. 0.0154 mol) in N-methylpyrrolidinone (50 ml, dried over 4A molecular sieves) was treated with anhydrous potassium carbonate (2.12 g, 0.0154 mol) and potassium iodide (2.55 g, 0.0154 mol) and stirred for 16 h at ambient temperature. The mixture was diluted with water and extracted thoroughly with ethyl acetate, and the combined extracts washed with aq. sodium thiosulphate, dried (MgSO4) and evaporated. The residue was purified by flash chromatography (fine silica, ethyl acetate) and the material thus obtained crystallised by trituration with ether to give the title compound as white crystals, m.p.H7-9°C, 4 g, 52% yield

lH NMR δ (CDC1 ₃ ) 1.33 (4H, m), 1.5-1,62 (4H, m), 2.56 (2H, t), 2.95, (IH, dd),

3.22 (3 H, m), 3.94 and 4.20 (each IH, d), 4.04 and 4.16 (each IH, d). 4.65 (IH, m), 6.25 (2H, s), 6.94 (3H, m), 7.11 (2H, m), 7.37 (2H. d), 7.46 (2H, m), 7.59

(lH, m), 8.1 (4H, m)

Found: C, 63.7; H.5.5; N, 4.5%; C ₃₃ H ₃₅ FN ₂ O ₇ S requires:C, 63.7; H, 5.7; N,

4.5%

Example 13 - (42?, S5)-N-(6-[4-Fluorophenyl]hex-l-yl)-4-(4-(4- methoxyphenylcarbonyloxymethyloxycarbonyI)benzylsulphinyI)-2 - oxoazetidin- l-yl)acetamide

A solution of (4R, S5)-N-(6-[4-fluoroρhenyl]hex-l-yl)-4-(4- carboxybenzylsulphinyl)-2-oxoazetidin-l-yl)acetamide (2 g, 0.0041 mol) and 4- methoxybenzoyloxymethyl chloride (2 g. 0.01 mol) in N-methylpyrrolidinone (20 ml, dried over 4A molecular sieves) was treated with anhydrous potassium carbonate (1.38 g, 0.01 mol) and potassium iodide (1.66 g, 0.01 mol) and stirred for 16 h at ambient temperature. The mixture was diluted with water and extracted thoroughly with ethyl acetate, and the combined extracts washed with aq. sodium thiosulphate, dried (MgSO4) and evaporated. The residue was purified by flash chromatography (fine silica, ethyl acetate) and the material thus obtained crystallised by trituration with ether, then recrystallised from dichloromethane/light petrol, to give the title compound as white crystals, m.p. 115-8°C, 1.34 g, 50% yield ^l H NMR δ (DMSO) 1.23-1.6 (8H, m), 2.50 (2H, m), 3.02-3.1(3H, m), 3.34 ( IH, m ), 3.8 and 4.09 (each IH, d), 3.84 (3H, s), 4.14 and 4.33 (each IH, d), 4.85 (IH, m), 6.17 (2H, s), 7.05 (4H, m), 7.16 (2H, m), 7.52 (2H, d), 7.97 (4H, m), 8.1 (IH. bt)

Example 14 - (4Λ, S5)-N-(6-[4-FluorophenyI]hex-l-yl)-4-(4-

(isobutyryloxymethyloxycarbonyl)benzyIsulphinyI)-2-oxoaze tidin-l- yDacetamide

A solution of (4R, S5)-N-(6-[4-fluorophenyl]hex-l-yl)-4-(4- carboxybenzylsulphinyl)-2-oxoazetidin-l-yl)acetamide (0.2g, 0.00041 mol) and isobutyryloxymethyl iodide (0.23 g. 0.001 mol) in N-methylpyrrolidinone (2 ml, dried over 4A molecular sieves) was treated with anhydrous potassium carbonate (0.14 g, 0.001 mol) and stirred for 16 h at ambient temperature. The mixture was diluted with water and extracted thoroughly with ethyl acetate, and the combined extracts washed with aq. sodium thiosulphate, dried (MgSO4) and evaporated. The residue was purified by chromatography (fine silica, ethyl acetate) and the material thus obtained crystallised by trituration with ether, to give the title compound as white crystals, m.p. 104-6°C, 0.14 g, 58% yield

lH NMR δ (DMSO)1.09 (6H, d), 1.25-1.52 (8H, m), 2.50 (2H, m), 2.61 (IH, m), 2.97-3.06 (3H, m), 3.34 (IH, m), 3.83 and 4.09 (each IH. d).4.15 and 4.34 (each IH, d), 4.84 (IH, m), 5.95 (2H, s), 7.06 (2H, m), 7.16 (2H, m), 7.53 (2H, d), 7.97 (2H, d), 7.99 (IH, bt)

Example 15 - (4R, S5)-N.(6-[4-Fluorophenyl]hex-l-yI)-4-(4-(2-methoxyprop-

2-ylcarbonyloxymethyloxycarbonyI)benzylsulphinyI)-2-oxoaz etidin-l- yl)acetamide

A solution of (4R, S5)-N-(6-[4-Fluorophenyl]hex-l-yl)-4-(4- carboxybenzylsulphinyl)-2-oxoazetidin-l-yl)acetamide (3 g, 0.00614 mol) and 2- methoxyprop-2-ylcarbonyloxymethyl chloride (1.53 g. 0.00921 mol) in N- methylpyrrolidinone (30 ml, dried over 4A molecular sieves) was treated with anhydrous potassium carbonate 1.27 g, 0.00921 mol) and potassium iodide (1.53 g, 0.00921 mol) and stirred for 16 h at ambient temperature. The mixture was diluted with water and extracted thoroughly with ethyl acetate, and the combined extracts washed with aq. sodium thiosulphate, dried (MgSO4) and evaporated. The residue was purified by chromatography (fine silica, ethyl acetate) and the material thus obtained as a solution in ethyl acetate further washed with aq. sodium thiosulphate then stirrred for 10 min with MgSO4 and decolourising charcoal. The solids were filtered off and the filtrate evaporated, and the residue crystallised by trituration with ether/light petrol to give the title compound as white crystals m.p. 92-4°C, 2.6 g, 68% yield

*H NMR δ (CDC1 ₃ ) 1.34 (4H, m), 1.45 (6H, s), 1.58 (4H, m), 2.56 (2H, t), 2.95 (IH, dd), 3.17-3.37 (3H, m + 3H, s), 3.96 and 4.10 (each IH, d), 4.05 and 4.22 (each IH, d), 4.69 (IH, m), 6.06 (2H, s), 6.93 (3H, m), 7.09 (2H, m). 7.39 (2H, d), 8.09 (2H, d)

Example 16 - (4R, S5)-N-(6-[4-FluorophenyI]hex-l-yl)-4-(4-((5-methyl-2-oxo-

13-dioxolen-4-yl)methyloxycarbonyl)benzylsuIphinyl)-2-oxo azetidin-l- yl)acetamide

A solution of (4R, S5)-N-(6-[4-fluorophenyl]hex-l-yI)-4-(4- carboxybenzylsulphinyl)-2-oxoazetidin-l-yl)acetamide (5 g, 0.0102 mol) and 4- bromomethyl-5-methyl-l,3-dioxol-2-one (2.96 g. 0.0154 mol) in N- methylpyrrolidinone (50 ml, dried over 4A molecular sieves) was treated with anhydrous potassium carbonate (2.12 g, 0.0154 mol) and stirred for 16 h at ambient temperature. The mixture was diluted with water and extracted thoroughly with ethyl acetate, and the combined extracts washed with water, brine, dried (MgSO4) and evaporated. The residue was purified by chromatography (fine silica, ethyl acetate) and the material thus obtained

crystallised by trituration with ether/light petrol to give the title compound as white crystals, m.p. 84-7°C, 3.81 g, 62% yield.

Η NMR δ (CDC1 ₃ ) 1.24-1.54 (8H, m), 2.22 (3H, s), 2.5 (2H, m), 2.95 (IH, dd),

3.05 (2H, m), 3.33 (IH, m), 3.84 and 4.07 (each IH, d), 4.15 and 4.32 (each IH, d), 4.85 (IH, m), 5.22 (2H, s), 7.06 (2H, m), 7.18 (2H, m), 7.51 (2H, d), 7.98

(2H, d), 8.1 (lH, bt)

Found: C, 59.7; H, 5.5; N, 4.7%; C ₃₀ H33FN2θ ₈ S requires:C, 60.0; H, 5.5; N,

4.7%

Example 17 - (4R, S5)-N-(6-[4.FluorophenyI]heχ.l-yl)-4-(4-((2- methoxycarbonyl-£-but-2-en-yI)methyIoxycarbonyl)benzyIsulph inyl)-2- oxoazetidin-l-yl)acetamide

A solution of (4R, S5)-N-(6-[4-fluorophenyl]hex-l-yl)-4-(4- carboxybenzylsulphinyl)-2-oxoazetidin-l-yl)acetamide (0.195 g, 0.0004 mol) and methyl £-2-bromomethylbut-2-enoate (0.16 g. 0.0008 mol) in N- methylpyrrolidinone (2 ml, dried over 4A molecular sieves) was treated with anhydrous potassium carbonate (0.11 g, 0.0008 mol) and stirred for 16 h at ambient temperature. The mixture was diluted with water and extracted thoroughly with ethyl acetate, and the combined extracts dried (MgSO4) and evaporated. The residue was purified by chromatography (fine silica, ethyl acetate) and the material thus obtained crystallised by trituration with ether to give the title compound as white microprisms, 0.024 g, 10% yield *H NMR δ (CDC1 ₃ ) 1.25-1.63 (8H, m), 1.99(3H, d), 2.56 (2H, t), 2.93 (IH, dd), 3.17-3.36 (3H, m), 3.79 (3H, s), 3.93 and 4.17 (each IH, d), 3.43 and 4.23 (each IH, d), 4.64 (IH, m), 5.12 (2H, s), 6.91-7.26 (6H, m), 7.34 (2H, d), 8.04 (2H, d)

Example 18 - (4R, S5)-N-(6-[4-FIuorophenyl]hex-l-yl)-4-(4-( N-N- dimemylaminocarbonylmethyloxycarbonyI)benzylsulphinyl)-2-oxo azetidin-l- yl)acetamide

A solution of (4R, S5)-N-(6-[4-fluoroρhenyl]hex-l-yl)-4-(4- carboxybenzylsulphinyl)-2-oxoazetidin-l-yl)acetamide (0.2 g, 0.0004 mol) and α-chloro-N,N-dimethyl acetamide (0.17 g. 0.001 mol) in N-methylpyrrolidinone (2 ml, dried over 4A molecular sieves) was treated with anhydrous potassium carbonate (0.14 g, 0.001 mol) and stirred for 16 h at ambient temperature. The mixture was diluted with water and extracted thoroughly with ethyl acetate, and the combined extracts dried (MgSO4) and evaporated. The residue was crystallised by trituration with ether to give the title compound as white cryatals, m.p. 141-4°C, 0.01 g

lH NMR δ (CDC1 ₃ ) 1.25-1.75 (8H, m), 2.56 (2H, t), 2.93 (IH, dd), 2.99 (3H, s), 3.04 (3H, s), 3.17-3.36 (3H, m), 3.85-4.25 (4H, 4 x d), 4.65 (IH, m).4.97 (2H, s), 6.93 (2H, m), 7.10 (3H, m), 7.36 (2H, d), 8.13 (2H, d).

Example 19 - (4Λ, S5)-N-(6-[4-Fluorophenyl]hex-l-yI)-4-(4-( N-N-di-(2- hydroxyethyl)aminocarbonyImethyloxycarbonyl)benzylsulphinyl) -2- oxoazetidin- l-yl)acetamide

To a solution of N,N-(l,l-dihydroxyethyl)bromoacetamide (1.20g, 5.3mmol) in DMF (10ml) was added (4R, S5)-N-(6-[4-fluorophenyl]hex-l-yl)-4-(4- carboxybenzylsulphinyl)-2-oxoazetidin-l-yl)acetamide (l.OOg, 2.05mmol) followed by caesium carbonate (1.3g, 4.0mmol). The mixture was stirred for 18 hrs then separated between ethyl acetate and 2M hydrochloric acid. Separation of the organics followed by washing with brine, drying (MgSO ₄ ) and concentration provided the crude product as a white solid. The solids were washed with chloroform, filtered and dried to yield the product as a white solid (0.97g, 75%) mp l l9-121°C.

Η nmr δ (DMSO^) 1.28-1.55(m,8H), 2.5(t, J=12Hz, 2H), 2.8(br d, J=16Hz, IH), 3.1(q, J=10Hz, 2H), 3.3-3.7(m, 9H), 3.9(d, J=27Hz, IH), 4.1(d, J=27Hz, IH), 4.15(d, J=20Hz, IH), 4.35(d, J=20Hz, IH), 4.7(br, IH), 4.85(m, IH), 4.95(br, IH), 5.2(s, 2H), 7.0(apparent t, J=14Hz, 2H), 7.15(dd, J=14, 9Hz, 2H), 7.5(d, J=13Hz, 2H), 8.05(d, J=13Hz, 2H), 8.2(t, J=8Hz, IH)

Example 20 Enantiomers of (.R,5/S,-r?>l-(2-(6-FluorophenyI)hexyIoxy)ethyl- 4-(4-aIlyloxycarbonylbenzylsulphinyl)-2-oxoazetidine a. 6-(4-FluorophenyI)hexyIoxy ethanol

Ethylene glycol (41.26g) and 6-(4-fluorophenyl)hexyl bromide (17.22g) were added to a solution of sodium hydroxide (2.79g) in water (2.5ml) and the mixture was heated at 110°for 24 hours. The mixture was cooled and partitioned between water (150ml) and diethyl ether (150ml). The layers were separated and the organic layer was washed with water, brine, dried (MgSO4) and evaporated to an orange oil. Purification by column chromatography on silica gel eluted with [5:1] to [1:1] P.E 40-60°C:ethyl acetate gave the product as an orange oil (9.91g, 62%). b. 6-(4-Fluorophenyl)hexyloxy triflate

6-(4-Fluorophenyl)hexyloxy ethanol (4.0g), pyridine (1.43g) and DMAP (40mg) were dissolved in dry dichloromethane (30ml), cooled to -10°C and triflic anhydride (5.6g) in dry dichloromethane (10ml) was added over 5 minutes keeping temperature below 0°C. The mixture was stirred at -10°C to 0°C over 60 minutes and then washed with water (50ml), brine (50ml), dried (MgSO4) and evaporated to a brown oil (6.17g, 99%).

c. l-(2-(6-FluorophenyI)hexyloxy)ethyl-4-(4-aIIyloxycarbonyIben zylthio)-2- oxoazetidine

A solution of 6-(4-fluorophenyl)hexyloxy triflate (7.0g), 4-(4- allyloxycarbonylbenztlthio)azetidin-2-one (5.08g) and tetrabutylammonium bromide (0.59g) in dry THF (150ml) was cooled to 15°C under nitrogen and was treated with powdered potassium hydroxide (1.08g). The cooling bath was removed and the reaction was stirred for 30 minutes. Powdered KOH (50mg) was added and the reaction was stirred at room temperature for 30 minutes. The mixture was filtered through celite and washed through with ethyl acetate (100ml). The filtrate was evaporated to a dark oil and purification by flash column chromatography on silica gel eluted with [3:2] to [1:1] P.E. 40-60°C: ethyl acetate gave the product as an orange oil (4.65g, 51%). IH NMR δ (CDC1 ₃ ) 1.3-1.6 (8H, m, 4xCH2,)> ² - ⁵⁵ ( ^2H - 1. J = 7.6Hz, CH.2Ph). 2.85, 2.90 (IH, dd, H3), 3.05 (IH, m, IH), 3.26, 3.32(1H, dd, J=4.9, 15.1Hz, H3), 3.37-3.68 (5H, m, NCH2CH2. OCH2), 3-86 (2H, s, SCH2), 4.76 (IH, m, H4), 4.81 (2H, m CO ₂ CH2). 5.36 (2H, m, CH=CH2). 6.03 (IH, m, CH=CH ₂ ), 6.94 (2H, m p-FPh-H), 7.07 (2H,m, p-FPh-H), 7.39 (2H, d, J=8.3Hz, Ph-H), 8.01 (2H, d, J=8.3Hz, Ph-H) d. (R,S/S,R)- l-(2-(6-Fluorophenyl)hexyloxy)ethyI-4-(4- allyloxycarbonylbenzylsulphinyI)-2-oxoazetidine (diast 2) A solution of l-(2-(6-fluorophenyl)hexyloxy)ethyl-4-(4- allyloxycarbonylbenzylthio)-2-oxoazetidine (4.58g) in dichloromethane (100ml), cooled to -70°C, was treated with a solution of mcpba (2.0g) in CH2CI2 (125ml) dropwise over 1 hour maintaining the temperature at below -70°C. The cooling bath was removed and the reaction was stirred for 1.5 hours, washed with a solution of 10% aq.sodium hydrogen carbonate( 150ml) + 10% aq. sodium sulphite (150ml). The layers were separated and the organic layer was washed with brine, dried (MgSO4) and evaporated to an oil which solidified on standing. Repeat recyrstallisations from diethyl ether (3 times) gave diastereoisomer 2 as a colourless solid (0.7g,12.2%).m.p. 73-74°C

IH NMR δ (CDC1 ₃ ) 1.3-1.6 (8H, m, 4xCH2.). ² -56 (2H, t, J = 7.8Hz, OfePh), 2.66, 2.69 (IH, dd, J=2,14.8Hz, H3). 3.38-3.68 (7H, m, H3, NCH2CH2, OCH2). 4.07 (2H, s, SOCH2), 4.54 (IH, m, H4), 4.83 (2H, m CO ₂ CH2), 5.36 (2H, m, CH=CH2> 6.03 (IH, m, CH=CH ₂ ), 6.94 (2H, m, p-FPh-H), 7.10 (2H, m, p-FPh- H), 7.38 (2H. d, J=8.4Hz, Ph-H), 8.08 (2H, m, Ph-H) e. (Λ,Λ/5,5>(2-(6-πuorophenyI)hexyloxy)ethyl-4-(4- allyloxycarbonylbenzylsulphinyl)-2-oxoazetidine (diast 1)

A sample of diastereoisomer 1 (contains 21% dia2) was obtained as a colourless solid, m.p.46-50°C.

IH NMR δ (CDC1 ₃ ) 1.3-1.6 (8H, m, 4xCH2,). ² -55 (2H, t, J = 7.8Hz, CH2Ph). 2.66, 2.69 (IH, dd, J=4.8,14.8Hz, H3), 3.38-3.68 (7H, m, H3, NCH2CH2, OCH2), 3.94 (2H, m, SOCH2), 4.55 (IH, m, H4), 4.83 (2H, m CO ₂ CH2), 5.36 (2H, m, CH=CH2) 6.03 (IH, m, CH=CH ₂ ), 6.94 (2H, m, p-FPh-H), 7.10 (2H, m, p-FPh-H), 7.38 (2H, d, J=8.4Hz, Ph-H), 8.08 (2H, m, Ph-H)

Enantiomers of (R,5A,RH-(2-(6-fluorophenyl)hexyloxy)ethyl-4-(4- allyloxycarbonylbenzylsulphinyl)-2-oxoazetidine were separated by hplc on a Chiracel OD -20MM eluted with 60:40 ethanol hexane:

f. (+)-l-(2-(6-Fluorophenyl)hexyloxy)ethyl-4-(4- allyloxycarbonylbenzylsulphinyI)-2-oxoazetidine (diast 2)

164mg, colourless solid. M.p. 52-53°C

Enantiomerically pure

[α] _D = +57.5° (c=0.5%w/v in ethanol at 25°C)

IH NMR δ (CDCI3) 1.3-1.6 (8H, m, 4xCH2,), ² -56 (2H, t, J = 7.8Hz, CH2Ph),

2.66, 2.69 (IH, dd, J=2,14.8Hz, H3), 3.38-3.68 (7H, m, H3, NCH2CH2, OCH2),

4.07 (2H, s. SOCH2).4-54 (IH, m, H4), 4.83 (2H, m CO ₂ CH2), 5.36 (2H, m,

CH=CH2> 6.03 (IH, m, CH=CH ₂ ), 6.94 (2H, m, p-FPh-H). 7.10 (2H, m, p-FPh-

H). 7.38 (2H, d, J=8.4Hz, Ph-H), 8.08 (2H, m, Ph-H) g. (-) l-(2-(6-FluorophenyI)hexyloxy)ethyl-4-(4- allyloxycarbonyIbenzylsuiphinyI)-2-oxoazetidine (diast 2) 170mg, colourless solid M.p. 51-53°C

99.69% desired enantiomer with 0.31% of the other enantiomer present

[α] _D = -57.9°C (c=0.4%w/v in ethanol at 25°C)

IH NMR δ (CDC1 ₃ ) 1.3-1.6 (8H, m, 4xCH2>), ² -56 (2H. t, J = 7.8Hz, CføPh).

2.66, 2.69 (IH. dd, J=2,14.8Hz, H3), 3.38-3.68 (7H, m, H3, NCH2CH2, OCH2),

4.07 (2H, s, SOCH2), 4.54 (IH, m, H4), 4.83 (2H, m CO ₂ CH2)« 5.36 (2H, m,

CH=CH2) 6.03 (IH, m, CH=CH ₂ ), 6.94 (2H, m, p-FPh-H), 7.10 (2H, m, p-FPh-

H), 7.38 (2H, d, J=8.4Hz, Ph-H), 8.08 (2H, m, Ph-H)

Example 21 (R,S/S,R)-l-(2-(6-FIuorophenyl)hexyloxy)ethyl-4-(4- carboxybenzyIsulphinyI)-2-oxoazetidine (diast 2)

(R,S/S,R)-l-(2-(6-Fluorophenyl)hexyloxy)ethyl-4-(4- allyloxycarbonylbenzylsulphinyl)-2-oxoazetidine (220mg), triphenylphosphine (1 lmg), tetrakis(triphenylphosphine)palladium (0) (15mg) in dry CH2CI2 (5ml) under nitrogen was treated with pyrrolidine (37μl) and the mixture was stirred at room temperature for 19 hours.. Purification by flash column chromatography on silica gel eluted with a CH2θ2:acetone:acetic acid gradient elution gave the product as an oil. The oil was dissolved in CH2CI2 (4ml) and diluted with diethyl

ether (75ml), washed with water, brine, dried (MgSO4), filtered and evaporated to an oil which solidified on cooling. Trituration with diethyl ether gave the product as a cream solid (155mg, 78%) m.p.95-96°C

IH NMR δ (CDCI3) 1.25-1.6 (8H, m. 4xCH2.). ² -56 ( ² H, t, J=7.6Hz, CH2Ph), 2.69, 2.76,(1H, dd, J=2.1,15.1Hz,H3), 3.10, 3.17 (IH, dd, J=5.1, 15.1Hz), 3.37- 3.74 (6H,m, NCH2CH2, OCH2).4.11 (2H, s, SOCH2).4.64 (IH, m, H4), 6.94 (2H, m, p-FPh-H), 7.10 (2H, m, p-FPh-H), 7.41 (2H, d, J=8Hz, Ph-H), 8.07 (2H, d, J=8Hz, Ph-H)

Example 22 (-H-(2-(6-Fluoroρhenyl)hexyloxy)ethyI-4-(4- carboxybenzylsulphinyl)-2-oxoazetidine (diast 2)

(-)-l-(2-(6-Fluorophenyl)hexyloxy)ethyl-4-(4-allyloxycarb onylbenzylsulphinyl)- 2-oxoazetidine (145mg), triphenylphosphine (7.3mg), tetrakis(triphenylphosphine)palladium (0) (10.5mg) in dry CH2CI2 (4ml) under nitrogen was treated with pyrrolidine (23.5μl) and the mixture was stirred at room temperature for 6 hours. Pyrrolidine (5μl) was added and the reaction was stirred at room temperature for 19 hours. Purification by flash column chromatography on silica gel eluted with a CH2Cl2:acetone:acetic acid gradient elution gave the title compound as an oil. Trituration with diethyl ether gave the product as a cream solid (113mg, 85%) m.p.l23-124°C, [cc] _D = -53.5° ( c=0.5 %w/v in ethanol at 25°C)

IH NMR δ (DMSO) 1.25-1.6 (8H, m, 4xCH2.). ² -50 (2H. t, QfePh). 2.91, 2.95 (IH, dd, J=2,15.2Hz, H3).3.22-3.53 (7H,m, H3, NCH2CH2, OCH2), 4.16, 4.31 (each IH, 2xd, J=13Hz, SOCH2), 4.73 (IH, m, H4), 7.0 (2H, m, p-FPh-H), 7.19 (2H, m, p-FPh-H), 7.48 (2H, d, J=8Hz, Ph-H), 7.94 (2H, d, J=8Hz, Ph-H)

Example 23 (+)-l-(2-(6-FIuorophenyl)hexyloxy)ethyl-4-(4- carboxybenzylsuIphinyI)-2-oxoazetidine (diast 2)

(+)-l-(2-(6-Fluorophenyl)hexyloxy)ethyl-4-(4-allyloxycarb onylbenzylsulphinyl)- 2-oxoazetidine (140mg), triphenylphosphine (7mg), tetrakis(triphenylphosphine)palladium (0) (lOmg) in dry CH2CI2 (4ml) under nitrogen was treated with pyrrolidine (23.5μl) and the mixture was stirred at room temperature for 19 hours. 1.5mg more catalyst and pyrrolidine (5μl) were added and the reaction was stirred for 2 hours, diluted with water (25ml) and CH2CI2 (25ml) and acidified to pH 2 with HCl (2N). The layers were separated and the aquoues layer was washed with CH2CI2 (25ml) The organic extracts were combined, dried (MgSO4) and evaporated to a yellow oil. Purification by flash column chromatography on silica gel eluted with a CH2θ2:acetone:acetic acid gradient elution gave the product as an oil. Trituration with diethyl ether gave the

product as a colourless solid (109mg, 84%) m.p.118-120°C, [α] _D = +50.0° ( c=0.5%w/v in ethanol at 25°C)

IH NMR δ (DMSO) 1.25-1.6 (8H, m, 4xCH2.), ² -50 (2H, t, CH2Ph), ² -91, 2.95 (IH, dd, J=2,15.2Hz, H3). 3.22-3.53 (7H,m, H3. NCH2CH2, OCH2). 4.16, 4.31 (each IH, 2xd, J=13Hz, SOCH2). ⁴ -73 (IH, m, H4), 7.0 (2H, m, p-FPh-H), 7.19 (2H, m, p-FPh-H), 7.48 (2H, d, J=8Hz, Ph-H), 7.94 (2H, d, J=8Hz, Ph-H)

Example 24 Enantiomers of (Λ,S/5,/?)-l-(2-(6-Chlorophenyl)hexyIoxy)ethyI- 4-(4-allyloxycarbonyIbenzylsulphinyl>2-oxoazetidine a. 6-(4-Chlorophenyl)hexyloxy ethanol

Ethylene glycol (51.1g) and 6-(4-chlorophenyl)hexyl bromide (22.7g) were added to a solution of sodium hydroxide (3.46g) in water (3.1ml) and the mixture was heated at 110°for 24 hours. The mixture was cooled and partitioned between water (300ml) and diethyl ether (300ml). The layers were separated and the aqueous layer was washed with ether (150ml). The organic layers were combined and washed with water, brine, dried (MgSO4) and evaporated to yellow oil. Purification by column chromatography on silica gel eluted with [3:1] to [2:1] P.E 40-60°C:ethyl acetate gave the product as a yellow oil (14.13g, 67%). b. 6-(4-Chlorophenyl)hexyloxy triflate

6-(4-Chlorophenyl)hexyloxy ethanol (7.6g), pyridine (2.53g) and DMAP (79mg) were dissolved in dry dichloromethane (60ml), cooled to -10°C and triflic anhydride (lO.Og) in dry dichloromethane (20ml) was added over 7 minutes keeping T below 0°C. The mixture was stirred at 0°C for 45 minutes, washed with water (60ml), brine (60ml), dried (MgSO4) and evaporated to a dark oil (11.13g, 97%). c. (2-(6-Chlorophenyl)hexyloxy)ethyl-4-(4-aIlyIoxycarbonylbenzy lthio)>2- oxoazetidine

A solution of 6-(4-chlorophenyl)hexyloxy triflate (1 l.lg), 4-(4- allyloxycarbonylbenztlthio)azetidin-2-one (7.69g) and tetrabutylammonium bromide (0.89g) in dry THF (200ml) was cooled to 10°C under nitrogen and was treated with powdered potassium hydroxide (1.63g). The cooling bath was removed and the reaction was stirred for 40 minutes. Powdered KOH (163mg) was added and the reaction was stirred at room temperature for 1.5h, partitioned between brine (600ml) and ethyl acetate (400ml). The mixture was filtered through hy-flo and the layers were separated. The organic layer was dried (MgSθ4) and evaporated to a dark oil. Purification by flash column chromatography on silica gel eluted with [2:1] to [1:1] P.E. 40-60°C: ethyl acetate gave the product as an orange oil (7.28g, 51%). IH NMR δ (CDC1 ₃ ) 1.3-1.6 (8H, m, 4xCH2,). ² -55 (2H, t, J = 7.6Hz, CH2Ph), 2.85, 2.90 (IH, dd, H3), 3.05 (IH, m. IH), 3.26, 3.32(1H, dd, J=4.9, 15.1Hz,

H3). 3.37-3.68 (5H. m, NCH2CH2, OCH2). 3.86 (2H. s, SCH2). 4.76 (IH, m, H4), 4.81 (2H, m CO2CH2). 5.36 (2H, m, CH=CH.2) 6.03 (IH, m, CH=CH ₂ ) 7.07 (2H, d, J=8.4Hz, p-ClPh-H), 7.23 (2H,m, p-ClPh-H), 7.39 (2H, d, J=8.3Hz, Ph-H), 8.01 (2H, d, J=8.3Hz, Ph-H) d. (R,S/S,R)- l-(2-(6-Chlorophenyl)hexyloxy)ethyl-4-(4- allyloxy car bonyIbenzylsulphinyl)-2-oxoazeti dine

A solution of l-(2-(6-Chlorophenyl)hexyloxy)ethyl-4-(4- allyloxycarbonylbenzylthio)-2-oxoazetidine (7.2g) in dichloromethane (175ml), cooled to -70°C, was treated with a solution of mcpba (3.0g) in CH2CI2 (175ml) dropwise over 1 hour maintaining the temperature at below -70°C. The cooling bath was removed and the reaction was stirred for 1.5 hours, washed with a solution of 10% aq.sodium hydrogen carbonate(200ml) + 10% aq. sodium sulphite (200ml). The layers were separated and the organic layer was washed with brine, dried (MgSO4) and evaporated to an oil which solidified on standing. Repeat recyrstallisations from diethyl ether (4 times) gave diastereoisomer 2 as a colourless solid (0.9g,12.2%).

IH NMR δ (CDCI3) 1.3-1.6 (8H, m, 4xCH2,). ² -56 (2H, t, J = 7.8Hz, CH2Ph), 2.66, 2.69 (IH, dd, J=2.4,15.2Hz, H3), 3.07, 3.11 (IH, dd, J=4.8, 15.2Hz, H3), 3.37-3.68 (6H, m, NCH2CH2, OCH2).4.07 (2H, s, SOCH2), 4.54 (IH, m, H4), 4.83 (2H, ra CO ₂ CH2), 5.36 (2H, m, CH=CH2) 6-03 (IH, m, CH=CH ₂ ) 7.09 (2H, d, J=8.8Hz, p-ClPh-H), 7.23 (2H, d. J=8.8Hz, p-ClPh-H), 7.39 (2H, d, J=8.4Hz, Ph-H), 8.07 (2H, m, Ph-H)

The above racemic compound was separated by hplc on a Chiracel OD -20mm eluted with 80:20 ethanol:hexane to give the enantiomers:

e. (+H-(2-(6-ChlorophenyI)hexyIoxy)ethyl-4-(4- allyloxy car bonylbenzylsulphinyl)-2-oxoazeti dine

83mg, colourless solid. M.p. 57-59°C

99.95% desired enantiomer with 0.05% of the other enantiomer present

[α] _D = +52.2° (c=0.28%w/v in ethanol at 25°C)

IH NMR δ (CDC1 ₃ ) 1.3-1.6 (8H, m, 4xCH2,), ² -56 (2H, t, J = 7.8Hz, CH2Ph),

2.66, 2.69 (IH, dd, J=2.4,15.2Hz. H3), 3.07, 3.11 (IH, dd, J=4.8, 15.2Hz, H3),

3.37-3.68 (6H, m, NCH2CH2, OCH2), 4.07 (2H, s, SOCH2).4.54 (IH, m, H4),

4.83 (2H, m CO ₂ CH.2), 5.36 (2H, m, CH=CH2) 6.03 (IH, m, CH=CH ₂ ) 7.09

(2H, d, J=8.8Hz, p-ClPh-H), 7.23 (2H, d, J=8.8Hz, p-ClPh-H), 7.39 (2H, d,

J=8.4Hz, Ph-H), 8.07 (2H, m, Ph-H) f. («)-l-(2-(6-ChJorophenyI)hexyloxy)ethyI-4-(4- allyloxycarbonylbenzylsulphinyl)-2-oxoazetidine 103mg colourless solid M.p. 58-59°C

99.62% desired enantiomer with 0.38% of the other enantiomer present [α] _D = -61.9°C (c=0.06%w/v in ethanol at 25°C)

IH NMR δ (CDC1 ₃ ) 1.2-1.6 (8H _? m, 4xCH2-). ² -56 (2H, t, J = 7.8Hz, CH2Ph), 2.66, 2.69 (IH, dd, J=2.4,15.2Hz, H3), 3.07, 3.11 (IH, dd, J=4.8, 15.2Hz, H3), 3.37-3.68 (6H, m, NCH2CH2. OCH ₂ , 4.07 (2H, s, SOCH2). ⁴ -54 (IH, m, H4), 4.83 (2H, m CO2CH2). 5.36 (2H, m, CH=CH2> 6.03 (IH, m, CH=CH ₂ ) 7.09 (2H, d, J=8.8Hz, p-ClPh-H), 7.23 (2H, d, J=8.8Hz, p-ClPh-H). 7.39 (2H, d, J=8.4Hz, Ph-H), 8.07 (2H, m, Ph-H)

Example 25 (-)-l-(2-(6-ChIorophenyl)hexyloxy)ethyI-4-(4- carboxybenzylsulphinyI)-2-oxoazetidine (diast 2)

(-)-l-(2-(6-Chlorophenyl)hexyloxy)ethyI-4-(4-allyloxycarb onylbenzylsulphinyl)- 2-oxoazetidine (86.2mg), triphenylphosphine (4.2mg), tetrakis(triphenylphosphine)palladium (0) (6mg) in dry CH2CI2 (2ml) under nitrogen was treated with pyrrolidine (13.5μl) and the mixture was stirred at room temperature for 19 hours. Purification by flash column chromatography on silica gel eluted with a CH2Cl2'acetone:acetic acid gradient elution gave the product as an oil. Trituration with diethyl ether gave the title compound as a cream solid (59.8mg, 75%) m.p.l02-102°C, [α] _D = -37.32° ( c=0.209%w/v in ethanol at 25 °C)

IH NMR δ (CDC1 ₃ ) 1.25-1.6 (8H, m, 4xCH2-). ² -56 (2H, t, J = 7.6Hz, CφPh). 2.71, 2.74 (IH, dd, J=2,15Hz, H3), 3.12, 3.15 (IH, dd, J=5.2, 15Hz, H3), 3.38- 3.72 (6H, m, NCH2CH2, OCH2), 4.09 (2H, m, SOCH2), 4.60 (IH, m, H4), 7.09 (2H, d, J=8.8Hz, p-ClPh-H), 7.22 (2H, d, J=8.8Hz, p-ClPh-H), 7.40 (2H, d, J=8Hz, Ph-H), 8.08 (2H, d, J=8Hz, Ph-H)

Example 26 (+)-l-(2-(6-Chlorophenyl)hexyloxy)ethyl-4-(4- carboxybenzylsulphinyI)-2-oxoazetidine (diast 2)

(+)-l-(2-(6-Chlorophenyl)hexyloxy)ethyl-4-(4-alIyIoxycarb onylbenzylsulphinyl)- 2-oxoazetidine (65.6mg), triphenylphosphine (3.2mg), tetrakis(triphenylphosphine)palladium (O) (4.6mg) in dry CH2CI2 (2ml) under nitrogen was treated with pyrrolidine (10.3μl) and the mixture was stirred at room temperature for 19 hours. Purification by flash column chromatography on silica gel eluted with a CH2Cl2'acetone:acetic acid gradient elution gave the product as an oil. Azeotroping with water and acetone followed by trituration with diethyl ether gave the product as a cream solid (44.7mg, 73%) m.p.l04-105°C, [α] _D = +51.92° ( c=0.208%w/v in ethanol at 25°C)

IH NMR δ (CDC1 ₃ ) 1.25-1.6 (8H, m, 4xCH2,), ² -56 ( ² H, t, J = 7.6Hz, CH2Ph), 2.71, 2.74 (IH, dd, J=2,15Hz, H3), 3.12, 3.15 (IH, dd, J=5.2, 15Hz, H3), 3.38- 3.72 (6H, m, NCH2CH2. OCH2).4.09 (2H, m, SOCH2). 4.60 (IH, m, H4), 7.09

(2H, d, J=8.8Hz, p-ClPh-H). 7.22 (2H, d, J=8.8Hz, p-ClPh-H). 7.40 (2H, d. J=8Hz, Ph-H), 8.08 (2H, d, J=8Hz, Ph-H)

Example 27 (α-S, 4-R, 5-S)-N-[6-(4-fluorophenyI)hexyI]-2-[(4- allyloxycarbonyl)benzyIsulphinyl)]-2-oxoazetidin-l-ylpropion amide a. R-Methyl-4-[(4-allyloxycarbonyl)benzylthio]-2-oxoazetidin-l- ylacetate

A suspension of R-4-[(4-allyloxycarbonyI)benzylthio]-2-oxoazetidin- 1-ylacetic acid (from Example If, 21.55g) and anhydrous potassium carbonate (8.88g)in 1- methyl-2-pyrrolidinone (100ml) was treated with methyl iodide (10.94g) and the mixture was stirred for 2h. Methyl iodide (l.Og) was added and after 30 minutes the reaction was partitioned between brine (500ml) and diethyl ether (500ml). The layers were separated and the aqueous layer was washed with diethyl ether (500ml). The organic extracts were combined washed with water (x2), brine, dried (MgSO4) and evaporated to an orange oil. Purification by flash column chromatography on silica gel eluted with [1:1] P.E 40-60°C:ethyl acetate gave the title compound as a yellow oil (contains 2% dimethyl ester) (20.0g, 89%). IH NMR δ (CDCl ₃ ) 2.94, 3.01 (IH, dd,J= 2.1, 15.2Hz, H3), 3.25 (IH, d, J=18Hz, 1 of NCH2), 3.39, 3.45 (IH, dd, J=5.1, 15.2Hz, H3), ³ -70 (3H, s, CH3).3.81 (2H. s, SCH2). 4.04 (IH. d. J=18Hz. 1 of NCH2). 4.83 (2H. m, CO ₂ CH2), 4.93 (IH, m, 4H), 5.35 (2H, m, CH=CH2), 6.04 (IH, m, CH=CH ₂ ), 7.39 (2H, d, J=8Hz, Ph-H), 8.02 (2H, d, J=8Hz, Ph-H) b. α-R,4-R-MethyI 2-{4-[(4-aIlyloxycarbonyl)benzylthio]-2-oxoazetidin-l- yljpropionate and α-S,-/-R-Methyl 2-{4-[(4-aIIyloxycarbonyI)benzylthio]-2- oxoazetidin- l-yl}propionate

A solution of R-methyl-4-[(4-allyloxycarbonyl)benzylthio]-2-oxoazetidin-l- ylacetate (13.2g) in dry tetrahydrofuran (250ml) at -75°C under nitrogen was treated with a IM solution of lithium bis(trimethylsilyl)amide in THF (46.3ml) over 10 minutes keeping the temperature below -70°C. 1,3- Dimethylimidazolidin-2-one (30.5ml) was added keeping the temperature below - 70°C. The resulting suspension was stirred at -75°C for 30 minutes and then treated with methyl iodide (4.3ml) over 1 minute and the temperature rose to - 68°C. The reaction was stirred for 1.5 hours at -75°C and then allowed to warm to -20°C over 30 minutes. The reaction was cooled to -75°C and quenched with glacial acetic acid (3.5ml), partititioned between water (300ml) and diethyl ether (250ml). The layers were separated and the aqueous layer was washed with diethyl ether (250ml). The organic extracts were combined washed with brine (x3), dried (MgSO4), and evaporated to a coloured oil. Ratio of 50% R,R (diaA): 15% starting material :35% S,R (dia B). Repeat purification by flash column chromatography on silica gel eluted with P.E. 40-60°C:ethyl acetate gave the products as coloured oils.

R.R Diastereoisomer (A), 3.9 lg (29%) (contains 9% dia B)

IH NMR δ (CDC1 ₃ ) 2.9 (IH. dd, H3). 3.30 (IH. H3). 3.75 (3H, s, CH3),3.88

(2H, s, SCH2), 4.4 (IH, m, CH), 4.83 (2H, m, CO ₂ CH2). ⁴ -90 (IH. m, 4H), 5.35

(2H. m, CH=CH2), 6.04 (IH, m, CH=CH ₂ ), 7.39 (2H. d, J=8Hz, Ph-H), 8.02

(2H, d, J=8Hz, Ph-H)

S,R Diastereoisomer (B), 5.36g (39%) (contains some sm and 43% dia A)

IH NMR δ (CDC1 ₃ ) 2.86, 2.92 (IH, dd, J=2.4, 15.2Hz, H3), 3.28, 3.33 (lH,dd,

J=5.1, 15.2Hz, H3), 3.73 (3H, s, CH3),3.85 (2H, s, SCH2), 3.95 (IH, m, CH),

4.71 (IH, m, 4H), 4.83 (2H, m, CO ₂ CH2), 4.90 (IH, m, 4H), 5.35 (2H, m,

CH=CH2), 6.04 (IH, m, CH=CH ₂ ), 7.40 (2H, d, J=8Hz, Ph-H), 8.02 (2H, d,

J=8Hz, Ph-H) c α-S,4-R-2-4{4-[(4-AlIyloxycarbonyI)benzylthio]-2-oxoazetidi n-l- yl}propionic acid

A solution of methyl 2-{4-[(4-allyloxycarbonyl)benzylthio]-2-oxoazetidin-l- yljpropionate (2.65g) (mixture of 5% dia A (R.R): 27% dia B (S,R): 65 % desαMe) in THF (50ml) at 3°C was treated with a IN sodium hydroxide solution (7.5ml) over 60 minutes. The cooling bath was removed and the reaction was stirred for 30 minutes. IN NaOH (1.0ml) was added over 30 minutes and the reaction was then stirred for 30 minutes, diluted with brine (75ml) and extracted with diethyl ether (75ml). The aqueous layer was acidified with 1NHC1 and extracted with diethyl ether (2x75ml). The organic extracts were combined washed with brine, dried (MgSO4), and evaporated to give the title compound as an orange oil (2.5g, 98%).and as a mixture in 5%R,R : 27%R,S : 65% des ceMe. d. α-S,^-R-N-[6-(4-FluorophenyI)hexyI]-2-[(4-aIlyIoxycarbonyI) benzylthio]- 2-oxoaze tidi n-1 -ylpropionamide

6-(4-Fluorophenyl)hexylamine (1.55g) in dry DMF (50ml) was added to a mixture of 2-[(4-allyloxycarbonyl)benzylthio]-2-oxoazetidin-l-ylpropion ic acid (2.70g) (above), 1-hydroxybenzotriazole (0.95g), N.N'-dicyclohexylcarbodiimide (1.46g) and the mixture was stirred at room temperature for 4h. The suspension was diluted with diethyl ether (100ml) and filtered to remove urea. The filtrate was washed saturated aq.NaHCO3, brine, dried (MgSO4), and evaporated to an oil. Purification by flash column chromatography on silica gel eluted with [2:1] P.E.40-60°C:ethyl acetate gave the product α-S, 4-R diastereoisomer (B)(contains 10% dia A) as a yellow oil (0.497g,13.4%).

*H NMR δ (CDCI3) 1.25-1.7 (1 IH, m, 4xCH2- CH ₃ ),2.55 (2H, t, J=7.6Hz, CH2Ph), 2.83, 2.89 (IH, dd, H3), 3.25 (3H, m, NCH2- H3), 3.86 (2H, s. SCH2), 4.10 (IH, m, CH). 4.69 (IH, m, 4H), 4.83 (2H. m, CO2CH2). 5.4 (2H. m, CH=CH2). 6.04 (IH, m, CH=CH ₂ ), 6.45 (IH, m, NH), 6.94 (2H, m, p-FPh-H), 7.09 (2H, m, p-FPh-H), 7.39 (2H, d, J=8Hz, Ph-H), 8.028 (2H, m, Ph-H)

Diastereoisomer A was also isolated

IH NMR δ (CDC1 ₃ ) 1.25-1.7 (11H, m, 4xCH2, CH ₃ ),2.55 (2H, t, J=7.6Hz, CH2Ph), 2.78, 2.85 (IH, dd, J=2.3, 15.4Hz, H3), 3.25 (3H, m, NCH2- H3). 3.89 (2H,m, SCH2). 4 05 (IH, m, CH), 4.81 (3H, 4 _Λ CO ₂ CH2), 5.4 (2H, m, CH=CH2). 6.04 (IH, m, CH=CH ₂ ), 6.48 (IH, m. NH). 6.94 (2H, m, p-FPh-H), 7.09 (2H. m, p-FPh-H), 7.39 (2H, d, J=8Hz, Ph-H), 8.02 (2H, d, Ph-H) e. α-S,4-R,S-S-N-[6-(4-Fluorophenyl)hexyI]-2-[(4- allyloxycarbonyi)benzyIsulphinyI)]-2-oxoazetidin-l-ylpropion amide A solution of S,R-N-[6-(4-fluorophenyl)hexyl]-2-[(4- allyloxycarbonyl)benzylthio]-2-oxoazetidin-l-ylpropionamide (1.20g)(80:20 DiaB:A) in dichloromethane (25ml), cooled to -75°C, was treated with a solution of mcpba (0.71g) in CH2CI2 (25ml) over 1 hour keeping the temperature at - 75°C. The cooling bath was removed and the reaction was stirred for 2 hours, diluted with CH2CI2 (25ml), washed with 10%aq. sodium sulphite (50ml), sat.NaHCO3 (50ml),dried (MgSO4) and evaporated to a coloured oil. Purification by flash column chromatography on silica gel eluted with ethyl acetate gave the title compound as a 60:40 mixture of dia B2 (α-S, 4-R, 5-S):dia Bl(α-S,4-R,5-R)

Purification on Kromasil 5μm silica (250mmx4.6mm) eluted with 50% hexane: 40% ethanol: 10% CHCI3 gave the title compound Diastereoisomer B2 : (α-S, 4- R. 5-S)-N-[6-(4-fluorophenyl)hexyl]-2-[(4-allyloxycarbonyl)benz ylsulphinyl)]-2- oxoazetidin-1-ylpropionamide as a colourless oil.

IH NMR δ (CDC1 ₃ ) 1.25-1.7 (11H. m, 4xCH2, CH ₃ ),2.55 (2H, t, J=7.6Hz. CH2Ph), 2.83, 2.89 (IH, dd,J= 2, 15Hz, H3), 3.24 (3H. m, NCH2, H3), 4.02 (2H, m, SOCH2), ⁴ - 44 (IH, m, CH), 4.60 (IH, m, 4H), 4.83 (2H, m, CO ₂ CH2). 5.4 (2H, m, CH=CH2). ^{6 04} (IH, m, CH=CH ₂ ), 6.85 (IH, m, NH), 6.94 (2H, m, p- FPh-H), 7.09 (2H, m, p-FPh-H), 7.37 (2H, d, J=8Hz. Ph-H), 8.08 (2H. d, J=8Hz. Ph-H ⁾

Example 28 (α-S, 4-R, 5-S)-N-[6-(4-FluorophenyI)hexyl]-2-[(4- carboxybenzylsuIphinyl)-2-oxoazetidin-l-ylpropionamide

A solution of (α-S, 4-R, 5-S)-N-[6-(4-fluorophenyl)hexyl]-2-[(4- allyloxycarbonyl)benzylsulphinyl]-2-oxoazetidin- 1-ylpropionamide (dia B2) (240mg),triphenylphosphine (6mg), tetrakis(triphenylphosphine)palladium (O) (15mg) in dry CH2CI2 (5ml) under nitrogen was treated with pyrrolidine (39μl) and the mixture was stirred at room temperature for 19 hours. The mixture was diluted with CH2CI2 (50ml) and water (25ml) and acidified with 2NHC1. The layers were separated and the aqueous was washed with CH2CI2 (2x50ml). The organic extracts were combined, dried (MgSO4) ^d evaporated to a yellow gum. Purification by flash column chromatography on silica gel eluted with a

CH2Cl2:acetone:acetic acid gradient elution gave the product as an oil. The oil was dissolved in CH2CI2 (4ml) and diluted with diethyl ether (75ml), washed with water, brine, dried (MgSO4), filtered and evaporated to a brown foam

(123mg, 56%)

[α]= No significant optical rotation (c=l.l%w/v in CHCI3)

*H NMR δ (CDCI ₃ ) 1.32-1.6 (13H, m, CH3, 4xCH2>, ² -55 (2H, t, J=7.6Hz,

CH2Ph), 2.84, 2.88 (IH, dd. J=2.4. 15.2Hz, H3), 3.1-3.3 (3H. m, NHCH.2. H3),

4.04, 4.10 (2H, 2xd, J=13Hz, SOCH2), ⁴ -4 (IH, q, CHCH3), 4.68 (IH, m, H ₄ ),

6.94 (3H, m, NH, p-F-Ph-H), 7.10 (2H, m, p-F-Ph-H), 7.39 (2H, m, Ar-H). 8.06

(2H, m, Ar-H)

Example 29 (α-R, 4-R, S-R)- and (α-R, 4-R, 5-S)-N-[6-(4- Fluorophenyl)hexyl]-2-[(4-aIlyloxycarbonyI)benzylsulphinyl)] -2-oxoazetidin- 1 -ylpropionamide

A solution of (α-R, 4-R)-N-[6-(4-fluorophenyl)hexyI]-2-[(4- allyloxycarbonyI)benzylthio] -2-oxoazetidin- 1 -ylpropionamide (1.25g)(diastereoisomer A) in dichloromethane (25ml), cooled to -75°C, was treated with a solution of mcpba (0.75g) in CH2CI2 (25ml) over 1 hour keeping the temperature at -75°C. The cooling bath was removed and the reaction was stirred for 2 hours, diluted with CH2CI2 (50ml), washed with 10%aq. sodium sulphite (50ml), sat.NaHCO3 (50ml), water, dried (MgSO4) and evaporated to a coloured oil. The oil was dissolved in ethyl acetate (7.5ml) and cooled. The resulting solid was collected, washed with diethyl ether and dried to give (α-R, 4- R, 5-R)-N-[6-(4-fluorophenyl)hexyl]-2-[(4-allyloxycarbonyl)benz ylsulphinyl)]-2- oxoazetidin-1 -ylpropionamide (dia Al) as a colourless solid 0.125g,9.7%. The filtrate was purified by flash column chromatography on silica gel eluted with ethyl acetate: P.E. 40-60°C. Pure R,R,R fractions were combined and recrystallised from ethyl acetate/diethyl ether to give R,R,R-N-[6-(4- fluorophenyl)hexyl]-2-[(4-allyloxycarbonyl)benzylsulphinyl)] -2-oxoazetidin-l- ylpropionamide as a colourless solid (0.195g, 15%), m.p.l39-140°C: IH NMR δ (CDC1 ₃ ) 1.25-1.7 (11H. m, 4xCH2. CH ₃ ),2.56 (2H, t, J=7.6Hz, CH2Ph)« ² -79. 2.83 (IH, dd,J= 5, 15Hz, H3), 3.20 (2H, m, NCH2), 3.33, 3.39 (IH, ddj= 2, 15Hz, H3). 3.94 (2H, m, SOCH2), 4.16 (IH, m. CH), 4.77 (IH, m, 4H), 4.83 (2H, m, CO ₂ CH2), 5.4 (2H, m, CH=CH2). 6.04 (IH. m, CH=CH ₂ ), 6.72 (IH, m, NH), 6.94 (2H, m, p-FPh-H), 7.09 (2H, m, p-FPh-H), 7.37 (2H, d, J=8Hz, Ph-H), 8.08 (2H. d, J=8Hz, Ph-H)

Impure R.R.S fractions were combined and recrystallised from ethyl acetate/diethyl ether to give (α-R, 4-R, 5-S)-N-[6-(4-fluorophenyl)hexyl]-2-[(4-

allyloxycarbonyl)benzylsulphinyl)]-2-oxoazetidin- 1 -ylpropionamide as a colourless solid (0.204g,15.8%), m.p. 102°C:

IH NMR δ (CDCI ₃ ) 1.25-1.7 (1 IH, m, 4xCH2. CH ₃ ),2.56 (2H, t, J=7.6Hz, CH2Ph), 2.83 (IH, dd, H3), 3.20 (3H, m, NCH2. H3).4.10 (3H, m, SOCH2- CH), 4.65 (IH, m, 4H), 4.83 (2H, m, CO ₂ CH2>, 5.4 (2H, m, CH=CH2>. 6.04 (IH, m, CH=CH ₂ ), 6.94 (2H, m, p-FPh-H), 7.09 (2H, m, , NH, p-FPh-H), 7.37 (2H, d, J=8Hz, Ph-H), 8.08 (2H, d, J=8Hz, Ph-H)

In an analagous manner the following chloro compounds were prepared from racemic 4-[(4-allyloxycarbonyl)benzylthio]-2-oxoazetidin- 1-ylacetic acid.

Example 30 (-)-(α-S, 4-R, SS)- and (+)-(α-R, 4>S, 5-R)-N-[6-(4- Chlorophenyl)hexyl]-2-[(4-al]yIoxycarbonyI)benzylsulphinyI]- 2-oxoazetidin- 1 -ylpropionamide a. N-[6-(4-Chlorophenyl)hexyI]-2-[(4-allyIoxycarbonyI)benzyIthi o]-2- oxoazetidin- 1 -ylpropionamide

A mixture of methyl-2-{(4-allyloxycarbonyl)benzylthio]-2-oxoazetidin-l- yl}propionate(4.87g), hydroxybenzotriazole (1.88g), DCC (2.89g) in dry DMF (60ml) was treated with 6-(4-chlorophenyl)hexylamine and stirred at room temperature for 6 days. The orange suspension was diluted with diethyl ether (200ml) and filtered to remove precipitate. Filtrate was washed with dil NaHCO3 (200ml), brine, dried (MgSO4), and evaporated to an orange oil. Repeat flash column chromatography on silica gel using P.E 40-60°C:ethyl acetate gave : Diastereoisomer A (R.R/S.S) (0.81g,l l%)

IH NMR δ (CDC1 ₃ ) 1.25-1.7 (1 IH, m, 4xCH2, CH ₃ ),2.55 (2H, t, J=7.6Hz, OfePh), 2.85 (IH, dd. H3), 3.25 (3H. m. NCH2. H3). 3.89 (2H,m, SCH2), ⁴ -05 (IH. m. CH). 4.81 (3H, 4,CO ₂ CH2), 5.4 (2H, m, CH=CH2>, 6.04 (IH, m, CH=CH ₂ ), 6.48 (IH, m, NH), 7.07 (2H, d, J=8.4Hz, p-ClPh-H), 7.22 (2H, d, J=8.8Hz, p-ClPh-H), 7.39 (2H, d, J=8Hz, Ph-H), 8.08 (2H, d, Ph-H) Diasterόisomer B (R.S/S.R) (1.63g. 22%)

IH NMR δ (CDCI3) 1.25-1.7 (11H, m, 4xCH2 _> CH ₃ ),2.55 (2H. t, J=7.6Hz, CH2Ph), 2.83, 2.89 (IH, dd, J= 2.3, 15.3Hz, H3). 3.25 (3H, m, NCH2. H3), 3.86 (2H, s, SCH2), 4.10 (IH, m, CH), 4.69 (IH, m, 4H). 4.83 (2H, m, CO ₂ CH2), 5.4 (2H. m, CH=CH2>. 6-04 (IH, m, CH=CH ₂ ), 6.43 (IH. m. NH), 7.07 (2H, d, J=8.4Hz, p-ClPh-H), 7.22 (2H, d, J=8.8Hz, p-ClPh-H), 7.39 (2H, d, J=8Hz, Ph- H), 8.08 (2H, m, Ph-H) b. N-[6-(4-ChIorophenyl)hexyI]-2-[(4-allyloxycarbonyl)benzylsuI phinyI]-2- oxoazetidin-1-ylpropionamide

A solution of (R,S/S,R)-N-[6-(4-chlorophenyl)hexyl]-2-((4-allyloxycarbonyl )-4- benzylthio)-2-oxoazetidin-l -ylpropionamide (1.60g)(diastereoisomer B) in

dichloromethane (30ml), cooled to -75°C, was treated with a solution of mcpba (0.92g) in CH2CI2 (30ml) over 45 minutes keeping the temperature below -70°C. The cooling bath was removed and the reaction was stirred for 45 minutes, diluted with CH2CI2 (20ml), washed with 10%aq. sodium sulphite (50ml), sat.NaHCO3 (50ml), dried (MgSO4) and evaporated to give the title compound as a mixture of stereoisomers as a coloured oil.(1.6g, 100%). (65%:35% sulfoxide diastereoisomer B2:B1) This material was separated by hplc: Sulfoxide dia B2 was separated from dia BI using Beckman silica 15cm x 4.6mm eluted with 10:90 ethanoLhexane and subsequent enantiomer separation of diasteroisomer B2 used Chiracel OD-4.6mm eluted with 25:75 ethanolihexane. c. (-)-(α-S, 4-R, 5-S)-N-[6-(4-Chlorophenyl)hexyl]-2-[(4- alIyloxycarbonyl)benzylsulphiny]]-2-oxoazetidin-l-ylpropiona mide ((-)B2) Enantiomerically pure, colourless oil, 148mg, [α] _D = -4.2° (c=0.4%w/v in CHCI3) IH NMR δ (CDC1 ₃ ) 1.25-1.7 (1 IH, m, 4xCH2, CH ₃ ),2.55 (2H, t, J=7.6Hz, CH2Ph), 2.83, 2.89 (IH, dd,J= 2.4, 15.3Hz, H3), 3.24 (3H, m, NCH2. H3).4.08 (2H, m), 4.60 (IH, m, CH), 4.69 (IH, m, 4H), 4.83 (2H, m, CO2CH2). 5.4 (2H, m, CH=CH2), 6.04 (IH, m, CH=CH ₂ ), 6.95 (IH, m, NH), 7.08 (2H, d, J=8.4Hz, p-ClPh-H), 7.22 (2H, d, J=8.8Hz, p-ClPh-H). 7.39 (2H, d, J=8Hz, Ph-H), 8.08 (2H, d, J=8Hz, Ph-H) d. (+)-(α-R, 4-S, 5»R)--N-[6-(4-ChlorophenyI)hexyl]-2-[(4- allyloxycarbonyl)benzyIsulphinyl]-2-oxoazetidin-l-ylpropiona mide ((+)B2) Sample contains 0.83% of the other enantiomer, colourless oil,145mg, [α] _D = +4.3° (c=0.4%w/v in CHCI3)

IH NMR δ (CDCI ₃ ) 1.25-1.7 (1 IH, m, 4xCH2, CH ₃ ),2.55 (2H, t, J=7.6Hz, CH2Ph), ² -83, 2.89 (IH, dd,J= 2.4, 15.3Hz, H3), 3.24 (3H, m, NCH.2, H3), 4.08 (2H, m), 4.60 (IH, m, CH), 4.69 (IH, m, 4H), 4.83 (2H, m, CO ₂ CH ₂ ), 5.4 (2H, m, CH=CH2>. 6.04 (IH, m, CH=CH ₂ ), 6.95 (IH, m, NH), 7.08 (2H, d, J=8.4Hz, p-ClPh-H), 7.22 (2H, d, J=8.8Hz, p-ClPh-H), 7.39 (2H, d, J=8Hz, Ph-H), 8.08 (2H, d, J=8Hz, Ph-H)

Example 31 (-)-(α-S, 4-R, 5-S)-[6-(4-Chlorophenyl)hexyI]-2-(4- carboxybenzylsulphinyI)-2-oxoazetidin-l-ylpropionamide

A solution of (-)-(α-S, 4-R, 5-S)-N-[6-(4-chlorophenyl)hexyl]-2-[(4- allyIoxycarbonyl)benzylsulphinyI]-2-oxoazetidin-l-ylpropiona mide (125mg), triphenylphosphine (6mg), tetrakis(triphenylphosphine)palladium (0) (8mg) in dry CH2O2 (2ml) under nitrogen was treated with pyrrolidine (19.5μl) and the mixture was stirred at room temperature for 19 hours. Purification by flash column chromatography eluted with a CH2θ2:acetone:acetic acid gradient elution gave the product as an oil. The oil was dissolved in CH2CI2 (2ml) and diluted with diethyl ether (50ml), washed with, brine (x2), dried (MgSO4),

W

filtered and evaporated to givee the title compound as a yellow foam (104mg,

87%)

[α] _D = -3.7° (c=0.5%w/v in CHCI3)

IH NMR δ (CDC1 ₃ ) 1.25-1.6 (8H, m, 4xCH2,). *-62 (3H, d, J=7.2Hz, CH ₃ ),2.55

(2H, t J=7.6Hz, CH2Ph). ² -86, 2.89 (IH, dd, J=2.4, 15.2Hzϋ ₃ ), 3.20 (3H, m,

NCH2. H3), 4.06 (2H, m, SOCH2), ⁴ -45 (IH, m, CH), 4.66 (IH, m, 4H), 6.95

(IH, m, NH), 7.08 (2H, d, J=8.4Hz, p-CIPh-H), 7.22 (2H, d, J=8.8Hz, p-ClPh-H),

7.39 (2H, d, J=8Hz, Ph-H), 8.08 (2H, d, J=8Hz, Ph-H)

Example 32 (+)-(α-R, 4-S, 5-R)-N-[6-(4-ChlorophenyI)hexyl]-2-(4- carboxybenzylsulphinyl)-2-oxoazetidin-l-ylpropionamide

A solution of (+)-(α-R, 4-S, 5-R)-N-[6-(4-chloroρhenyl)hexyI]-2-[(4- allyloxycarbonyl)benzylsulphinyl]-2-oxoazetidin-l-ylpropiona mide (123mg), triphenylphosphine (6mg), tetrakis(triphenylphosphine)palladium (O) (8mg) in dry CH2CI2 (2ml) under nitrogen was treated with pyrrolidine (19.5μl) and the mixture was stirred at room temperature for 19 hours. Purification by flash column chromatography eluted with a CH2Cl2:acetone:acetic acid gradient elution gave the product as an oil. The oil was dissolved in CH2CI2 (2ml) and diluted with diethyl ether (50ml), washed with, brine (x2), dried (MgSO4), filtered and evaporated to a yellow foam (lOlmg, 89%) [α] _D = +3.3° (c=0.3%w/v in CHCI3)

IH NMR δ (CDCI ₃ ) 1.25-1.6 (8H. m, 4xCH2-). 1-62 (3H, d, J=7.2Hz, CH ₃ ),2.55 (2H, t, J=7.6Hz, CH2Ph), 2.88 (IH, dd, H3), 3.20 (3H, m, NCH2. H3). 4.06 (2H, m, SOCH2), 4-45 (IH, m, CH), 4.69 (IH, m, 4H), 6.95 (IH, m, NH), 7.08 (2H, d, J=8.4Hz, p-CIPh-H), 7.22 (2H, d, J=8.8Hz, p-CIPh-H), 7.39 (2H, d, J=8Hz, Ph- H), 8.08 (2H, d, J=8Hz, Ph-H)

The following racemic compounds were also prepared. These may then be separated into enantiomers by hplc, using a chiral stationary phase, in a similar manner to separations hereinbefore described.

Description 1 (R,5/5,R>-l-(2-(6-Chlorophenyl)hexyloxy)ethyl-4-(4- carboxybenzylsulphinyI)-2-oxoazetidine (diast 2)

(R _r 5/5,RH-(2-(6-Chlorophenyl ⁾ hexyloxy)ethyl-4-(4- allyloxycarbonyIbenzylsulphinyl)-2-oxoazetidine (220mg), triphenylphosphine (1 lmg), tetrakis(triphenylphosphine)palladium (0) (15mg) in dry CH2CI2 (5ml) under nitrogen was treated with pyrrolidine (37μl) and the mixture was stirred at room temperature for 19 hours. Purification by flash column chromatography on silica gel eluted with a CH2Cl2:acetone:acetic acid gradient elution gave the product as an oil. The oil was dissolved in CH2CI2 (4ml) and diluted with diethyl

ether (75ml), washed with water, brine, dried (MgSO4), Altered and evaporated to an oil which solidified on cooling. Trituration with diethyl ether gave the title compound as a cream solid (149mg, 75%) m.p.l07-108°C IH NMR δ (CDC1 ₃ ) 1.25-1.6 (8H, m, 4xCH2,)> ² -56 (2H, t, J = 7.8Hz, CtøPh). 2.71, 2.74 (IH, dd, J=2,15.2Hz, H3), 3.12, 3.15 (IH, dd, J=5.2, 15.2Hz, H3), 3.38-3.72 (6H, m, NCH2CH2, OCH2). 4.10 (2H, m, SOCH2). 4.63 (IH, ni, H4). 7.09 (2H, d, J=8.8Hz, p-CIPh-H), 7.22 (2H, d, J=8.8Hz, p-CIPh-H), 7.40 (2H, d, J=8Hz, Ph-H), 8.08 (2H, d, J=8Hz, Ph-H)

Description 2 (Λ,5/5,RH-(2-(6-Chlorophenyl)hexyloxy)ethyl-4-(4- ethoxycarbonyIbenzylsulphinyI)-2-oxoazetidine (diast 2) a. l-(2-(6-ChlorophenyI)hexyloxy)ethyI-4-(4-ethoxycarbonyIbenzy lthio)-2- oxoazetidine

A solution of 6-(4-chlorophenyl)hexyloxy triflate (3.62g), 4-(4- ethoxycarbonylbenztlthio)azetidin-2-one (2.47g) and tetrabutylammonium bromide (0.30g) in dry THF (70ml) was cooled to 10°C under nitrogen and was treated with powdered potassium hydroxide (0.62g). The cooling bath was removed and the reaction was stirred for 2 hours . The mixture was partitioned between brine (200ml) and ethyl acetate (200ml) and filtered through celite. The layers were separated and the aqueous was washed with ethyl acetate (100ml). The organic extracts were combined, dried (MgSO4) and evaporated to a dark oil. Purification by flash column chromatography on silica gel eluted with [2:1] to [1:1] P.E. 40-60°C: ethyl acetate gave the title compound as a yellow oil (2.41g, 51%).

IH NMR δ (CDC1 ₃ ) 1.25-1.6 (1 IH, m, CH3, 4xCH2 _> ), ² -55 (2H, t, J =7.6Hz, CH2Ph), 2.85 (IH, dd, H3), 3.05 (IH, m), 3.25, 3.30 (IH, dd, H3), 3.36-3.72 (5H, m. NCH2CH2. OCH2), 3.85 (2H. s, SCH2), 4.37 (2H, q, J=7.1Hz, CO2CH3) 4.76 (IH. m, H4), 7.07 (2H, d, J=8.4Hz, p-CIPh-H), 7.22 (2H, m, p- ClPh-H), 7.39 (2H, d, J=8Hz, Ph-H), 8.08 (2H, d, J=8Hz, Ph-H) b. (Λ,S/5,Λ)-l-(2-(6-Chlorophenyl)hexyloxy)ethyl-4-(4- ethoxycarbonyIbenzylsuIphinyl)-2-oxoazetidine (diast 2) A solution of l-(2-(6-chlorophenyl)hexyloxy)ethyl-4-(4- ethoxycarbonylbenzylthio)-2-oxoazetidine (2.37g) in dichloromethane (75ml), cooled to -70°C, was treated with a solution of mcpba (l.Og) in CH2CI2 (75ml) dropwise over 1 hour maintaining the temperature at below -70°C. The cooling bath was removed and the reaction was stirred for 2 hours, washed with a solution of 10% aq.sodium hydrogen carbonate(50ml) + 10% aq. sodium sulphite (50ml). The layers were separated and the organic layer was washed with brine, dried (MgSO4) and evaporated to an oil. Recrystallisation from diethyl ether (40ml) gave a colourless solid (0.91g). Purification by flash column chromatography

eluted on silica gel with [2:1] ethyl acetate :hexane and recystallisation of the less polar product from diethyl ether (15ml) gave diastereoisomer 2 as a colourless solid (0.40g,16%).m.p. 81-82°C

IH NMR δ (CDC1 ₃ ) 1.25-1.6 (1 IH, m, CH3, 4xCH2,). ² -55 (2H, t, J =7.8Hz, CH2Ph), 2.63, 2.69 (IH, dd, J=2.2, 15.1Hz, H3), 3.05, 3.11 (IH, dd, J=5.1, 15.1Hz, H3), 3.36-3.74 ⁽ 6H, m, NCH2CH2. OCH2). 3.75 (2H, s, SOCH2), 4.39 (2H, q, J=7.1Hz, CO2CH3) 4.54 (IH, m, H4), 7.09 (2H, d, J=8.4Hz, p-CIPh-H), 7.22 (2H, m, p-CIPh-H), 7.37 (2H, d, J=8.3Hz, Ph-H), 8.06 (2H, m, Ph-H)

Biological Data

1. Screen for Lp-PLA2 inhibition.

Enzyme activity was determined by measuring the rate of turnover of the artificial substrate (A) at 37 °C in 50mM HEPES (N-2-hydroxyethylρiρerazine- N'-2-ethanesulphonic acid) buffer containing 150mM NaCl, pH 7.4.

(A)

Assays were performed in 96 well titre plates.

Lp-PLA2 was partially purified by density gradient centrifugation of human plasma. Active fractions were pooled and used as the source of Lp-PLA2- The enzyme was pre-incubated at 37 °C with vehicle or test compound for 10 min in a total volume of 180 μl. The reaction was then initiated by the addition of 20 μl lOx substrate (A) to give a final substrate concentration of 20 μM. The reaction was followed at 405 nm for 20 minutes using a plate reader with automatic mixing. The rate of reaction was measured as the rate of change of absorbance.

Results:

The compounds of Examples 1 and 2, the corresponding carboxylic acid (+/-)-N- [6-(4-chlorophenyl)hex-l-yl]-4-(4-carboxybenzylsulphinyl)-2- oxoazetidin-l- yl)acetamide and the carboxylic acid (4R, S5)-N-[6-(4-fluorophenyl)hex-l-yI]-4- (4-carboxybenzylsulphinyI)-2-oxoazetidin-l-yl)acetamide had IC50 values in the range 4 to 20 nM. The compounds of Example 12,13 and 14 had IC50 values in the range 2 to 4 nM.

2. Evaluation of Bioavailability

The pro-drug esters were evaluated in dog and human liver microsomes according to standard procedures for their ability to be hydrolysed to the parent acid. The results are given in the table below.

Acid production - % conversion of test ester to parent acid by dog or liver microsomes after incubation of lμm test compound for 15 min, determined by measuring the concentration of parent acid produced by HPLC detection of acid (100% = lμM acid produced). Figures are rounded to nearest 5%.

3. Evaluation of stability

Stability was estimated by determining half Uves for decomposition test compound in pH 7.5 buffer (50 mM phosphate) and pH 1.2 buffer (USP simulated gastric fluid = NaCl/HCl pH 1.2 + pepsin). Initial concentration = 50 uM and compound monitored by HPLC. Figures rounded to nearest 0.5 h.

Preferred compounds are those exhibiting good conversion of ester to acid in biological systems, while showing good stability in buffers (e.g. examples 9, 11, 12, 15, 16).