WO1997041099A1

WO1997041099A1 - Azetidinone derivatives for the treatment of atherosclerosis

Info

Publication number: WO1997041099A1
Application number: PCT/EP1997/002286
Authority: WO
Inventors: Deirdre Mary Bernadette Hickey; Colin Andrew Leach; Robert John Ife; Dashyant Dhanak
Original assignee: Smithkline Beecham Plc
Priority date: 1996-04-26
Filing date: 1997-04-28
Publication date: 1997-11-06
Also published as: GB9608649D0; EP0900199A1; JP2000509063A

Abstract

Compounds of formula (I) in which inter alia X is a linker group A-B in which A is bond, CH2O, CO, CONR6, COO, CONR6CO, or CONR6O in which R6 is hydrogen or C¿(1-6)?alkyl and B is (CH2)pCO(CH2)q in which p is an integer from 1 to 8, preferably 3 to 5, and q is 0 or an integer from 1 to 8, preferably 0, 1 or 2, such that p + q = 1 to 12, preferably 5 to 8, more preferably 5; are inhibitors of the enzyme Lp PLA2 and therefore of use in therapy, in particular, treating atherosclerosis.

Description

AZETIDINONE DERIVATIVES FOR THE TREATMENT OF ATHEROSCLEROSIS .

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.

Lipoprotein Associated Phospholipase A2 (Lp-PLA2) - also previously known as Platelet Activating Factor Acetyl Hydrolase (PAF acetyl hydrolase) - 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 oxidised phosphatidylcholine to give lysophosphatidylcholine and an oxidatively modified fatty acid. Both products of Lp- PLA? 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 ofthe 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-PLA? could therefore prove beneficial in the treatment of this phenomenon. A 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.

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 atherosclerosis and diabetes along with other conditions such as rheumatoid arthritis, stroke, inflammatory conditions of the brain such as Alzheimer's Disease, myocardial infarction, reperfusion injury, restenosis. acute and chronic inflammation and sepsis.

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-PLA2- Examples of such disorders include psoriasis.

Patent applications WO 96/13484, WO96/19451 and WO 97/02242 (SmithKline Beecham pic) disclose inter alia various series of 4-thionyl/sulfιnyl/sulfonyl azetidinone compounds characterised by the general formula (A):

(A) in which:

R^a and R^D, which may be the same or different, is each selected from hydrogen, halogen or optionally substituted

R^c is Cπ _8)alkyl, C(3_g)cycloalkyl, C(3-8)cycloalkylCπ _6)alkyl, aryl, aryl(C i .4)alkyl. heteroaryl, or heteroaryl(C \ _4)alkyl each of which may be optionally substituted

R and R^e which may be the same or different is each selected from hydrogen,

C(i _6)alkyl. C(2-6)^alkenyl, aryl. aryl(C j.4)alkyl and heteroaryl(C \ _4)alkyl each of which may be optionally substituted or R^ and R^e may be linked together to form the remainder of a (C3_7)cycloalkyl πng;

X is a linker group, in partcular a group X'(CH2)_m ⁱⁿ which X' is CO, CONR², COO,

CONR²CO, or CONHO in which R² is hydrogen or Cn .g^alkyl and m is 0 or an integer from 1 to 12; or a C(j.i2)^a^ylene chain optionally interupted by X', oxygen or a carbon-carbon double or triple bond; 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. We have now identified a further series of compounds which have been found to act as inhibitors of Lp-PLA2-

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

in which:

Rl and R², which may be the same or different, is each selected from hydrogen, halogen or Cπ _g\alkyl;

R is C(i_8)alkyl. C(3_g)cycloalkyl or Cπ-8)cycloalkylCπ _6)alkyl. aryl, aryl(C _j _4)alkyl or heteroaryl(Cι_4)alkyl, each of which may be optionally substituted;

R⁴ and R5 which may be the same or different is each selected from hydrogen, C(j_ 6)alkyl. C(2-6)alkenyl, aryl, aryl(C j _4)alkyl and heteroaryl(C i _4)alkyl each of which may be optionally substituted, or R^ and R^ may be linked together to form the remainder of a (C3_7)cycloalkyl ring;

X is a linker group A-B in which A is a bond, CH2O, CO, CONR⁶, COO, CONR⁶CO, or CONR⁶O in which R⁶ is hydrogen or C(i_6)alkyl and B is (CH2)pCO(CH2)q in which p is an integer from 1 to 8, preferably 3 to 5, and q is 0 or an integer from 1 to 8, preferably 0, 1 or 2, such that p + q = 1 to 12, preferably 5 to 8. more preferably 5;

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

Compounds of formula (I) are inhibitors of Lp-PLA2 and as such are expected to be of use in treating atherosclerosis and the other disease conditions noted above. Representative examples of R^ and R² include hydrogen, bromo. methyl and ethyl. Suitably. R¹ and R² is each hydrogen or one of Rl and R² is hydrogen and the other of R^ and R² is methyl (to give a trans-methyl). Preferably, R and R² is each hydrogen. Representative values for R^ include arylCπ _3\alkyl. Within R^, representative examples ofthe aryl group include phenyl and naphthyl. Suitable examples of R^ include benzyl, 2-pheny lethy 1 and 3-phenylpropyl in each of which the phenyl ring may be optionally substituted by up to three substituents. Suitable substituents for a phenyi or naphthyl ring in R include halo, hydroxy, C(i_6)alkyl, C( 1 _6)alkoxy, C( 1 _6)alkoxycarbonyl, C(2-6)aikenyloxycarbonyl. carboxy and pharmaceutically acceptable salts and in vivo hydrolysable esters thereof.

Representative examples of the aryl group for when R^ is aryl include phenyl and naphthyl. Preferably, the aryl group is optionally substitued phenyl. Suitable substituents for a phenyl or naphthyl ring include halo, hydroxy, C(i_6)alkyl, Cr\. 6)alkoxy, C( \ ^alkoxycarbonyl, C(2-6)^alkenyloxycarbonyl, carboxy and pharmaceutically acceptable salts and in vivo hydrolysable esters thereof.

Representative examples for R^ when R^ is Cπ _g)alkyl. Cπ_g)cycloalkyl or C(3_g)cycloalkylC(]_6)alkyl include methyl, n-butyl, t-butyl and n-hexyl, cyclohexyl and cyclohexyi methyl, suitably n-butyl, t-butyl or n-hexyl. Suitable substituents for the alkyl or cycloalkyl group in R3 include halo, hydroxy, Cπ _g)alkoxycarbonyl,

C(2-6)^aikeny^loχy^carDθny^l> carboxy and pharmaceutically acceptable salts and in vivo hydrolysable esters thereof.

Further representative values for R³ include heteroarylCπ _3)alkyl, preferably heteroarylmethyl. Representative examples ofthe heteroarylaryl group for use in R^ include pyridyl, pyridyl N-oxide, furanyl, thienyl and thiazolyl. Suitable substituents for a heteroaryl ring in R^ include halo, hydroxy, Cπ _6)alkyl, C(i_

C(i_6)alkoxycarbonyl, C(2-6)alkenyloxycarbonyl, carboxy and pharmaceutically acceptable salts and in vivo hydrolysable esters thereof. It will be appreciated that within R^, an optional substituent may be located in the alkyl, cycloalkyl. aryl and/or heteroaryl portion.

Preferably, R^ is arylC(i_3)alkyl or heteroarylCπ _3)alkyl. more preferably ary'C(i_3)alkyl.

Preferably, n is 1 or 2, more preferably 1. Preferably, S(O)_nR^J is optionally substitued benzylsuiphinyl, more preferably

4-carboxybenzyisulphinyl, a C(' _6)alkyl or C(2-6)alkenyl ester, a pharmaceutically acceptable salts or an in vivo hydrolysable ester thereof.

Suitably, R⁴ is hydrogen and R^ is methyi or R^ and R^ is each hydrogen.

Suitably in X, A is CFbO or CONH. Suitable examples of X include CONH(CH₂)5CO and CH₂0(CH₂)5CO.

Suitably, Y is a benzene ring, optionally substituted by up to three further substituents. Suitable substituents include halo, hydroxy, Cπ

and

C(i_g)alkoxy. Preferably, Y is phenyl optionally substituted by halo.

It will be readily appreciated by the skilled person that C-4 of the β-lactam ring is a chiral centre which will give rise to the presence of stereoisomers. The present invention encompasses all such stereoisomers. An additional chiral centre will be introduced when R^ and R³ are not the same. This will give rise to the existence of extra stereoisomers. The present invention encompasses all such stereoisomers. It will be further readily appreciated by the skilled person that, m compounds of formula (I) 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. The present invention encompasses all such stereoisomers. In preferred compounds of formula (I), the absolute configurations at C-4 and the SO moiety are R and S respectively.

When used herein, the term 'alkyl' and similar terms such as 'alkoxy' includes all straight chain and branched isomers. Representative examples thereof include methyl, ethyl, «-propyl, /JO- propyl, /i-butyl, .yec-butyl, /yo-butyl, t-butyl. «-pentyl and Ai-hexyl.

Suitable substituents for an alkyl group include, for example, halogen, cyano, azido, nitro. carboxy, (Cι_6)alkoxycarbonyI, carbamoyl, mono- or di-(C i _6)alkylcarbamoyl, sulpho, sulphamoyl, mono- or di-(C \ _g)alkylsulphamoyl, amino, mono- or di-(C] .^alkylamino, acylamino, ureido. (Cι _6)alkoxycarbonylamino, 2,2,2-trichloroethoxycarbonylamino. aryl, heterocyclyl. hydroxy, (C i _g)alkoxy, acyloxy, oxo, acyl, 2-thienoyl, (Cι_6)alkylthio, (Cμ6)alkylsulphinyl, (C ι_6)alkylsulphonyl, hydroxyimino, (C \ _6)alkoxyimino, hydrazino, hydrazono, benzohydroximoyl, guanidino. amidino and iminoalkylamino. When used herein, the term 'aryl' includes, unless otherwise defined, phenyl or naphthyl optionally substituted with up to five, preferably up to three substituents.

Suitable substituents for an aryl group include, for example, halogen, cyano, (Cι-6)alkyl, (C3-7)cycloalkyl, (C j -6)alkoxy, halo(Cj-6)alkyl, hydroxy, amino, mono- or di-(Cι-6)alkylamino. acy lamino, nitro. carboxy, (Cj-6)alkoxycarbonyl, (C i -6)alkenyloxycarbonyl. (C \ -g)alkoxycarbonyl(C \ -g)alkyl,

(C j -^alkylcarbonyloxy, carboxy(C \ -6)alkyloxy. (C j -g)alkyIcarbonyloxy, (Ct -6)alkylthio, (C i -6)alkylsulphinyl, (Cι-g)alkylsulphonyl, suiphamoyl, mono- and di-(Cι-6)-alkylsulphamoyl, carbamoyl, mono- and di-(C ι-6)alkylcarbamoyl, and heterocyclyl. When used herein, the term 'heteroaryl' includes single and fused rings, each πng suitably comprising up to four, preferably 1 or 2, heteroatoms each selected from oxygen, nitrogen and sulphur. Each ring may have from 4 to 7, preferably 5 or 6, ring atoms. A fused heteroaryl ring may include carbocyclic rings and need include only one heteroaryl ring. Suitabie fused heteroaryl rings include bicyclic systems. When used herein, the term 'heterocyclyl' includes aromatic and non-aromatic single or fused rings comprising up to four hetero-atoms in the ring selected from oxygen, nitrogen and sulphur and optionally substituted with up to three substituents. Suitably the heterocyclic ring comprises from 4 to 7, preferably 5 to 6, ring atoms. A fused heterocyclic ring system may include carbocyclic rings and need only include one heterocyclic ring.

When substituted, a heteroaryl or a heterocyclyl group may have up to three substituents. Suitable such substituents include those previously mentioned for an aryl group as well as oxo.

When used herein, the terms 'halogen' and 'halo' include fluorine, chlorine, bromine and iodine and fluoro. chloro, bromo and iodo. respectively.

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

Suitable values of the ester forming radical for use in vivo hydrolysable esters include:

-CH(R^a)O.CO.Rb_;

-CH(R^a)O.CO.OR^c;

-CH(R^a)CO.NR^eRf

-R^dNR^eRf; -CH2ORS;

CH₂ h R

/

CD .0

COCH(Ri)NH9; and

in which:

R^a is hydrogen, (C ^alkyl, in particular methyl, (C3-7)cycloalkyI, or phenyl, each of which may be optionally substituted;

R^b is (C ι-6)alkyl, (C \ -g)alkoxy(C \ -6)alkyl, phenyl, benzyl, (C3-7)cycloalkyl,

(C ι -6)alkyl(C3-7)cycloalkyl. l-amino(Cι-6)alkyl. or 1 -(C halky l)amino(C ι-6)alkyl, each of which may be optionally substituted; or

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

R^c is (C ι-(5)alkyl, (C₃-7)cycloalkyl, (C^^lkyl^^cycloalkyl;

Rd is (Cj-6)alkylene optionally substituted with a methyl or ethyl group; R^e and Rf which may be the same or different is each (Cι-6)alkyl; or aryl(C 1-4) alkyl, optionally substituted with e.g. hydroxy;

Rg is (C< -6)alkyl;

Rⁿ is hydrogen, (Cι-β)alkyl or phenyl;

R¹ is hydrogen or phenyl optionally substituted by up to three groups selected from halogen, (C \ -6)-alkyl, or (C \ -6)alkoxy; and is oxygen or NH.

Suitable values of the ester forming radical include:

(a) acyloxyalkyl groups such as acetoxymethyl, isobutyryloxymethyl, pivaloyloxymethyl, benzoyloxymethyl, α-acetoxyethyl, α-pivaloyloxyethyl,

1 -(cyclohexylcarbonyloxy)ethyl, ( 1 -aminoethy l)carbony loxymethy I. 2-methoxyprop- 2-ylcarbonyloxymethyl. phenylcarbony loxymethy 1 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-dimethylaminocarbonylmethyI. 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-E-but-2-en-yl)methyl.

Since the compounds ofthe present invention, in particular 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 ofthe compounds of formula (I) may be used for preparing the more pure forms used in the pharmaceutical compositions. Although the purity of intermediate compounds ofthe 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 ofthe present invention are obtained in crystalline form.

When some ofthe 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 ofthe present invention are inhibitors ofthe 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 ofthe brain such as Alzheimer's

Disease, myocardial infarction. reperfusion injury, restenosis. acute and chronic inflammation and sepsis. Furthermore, 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-PLA2, for example psoriasis.

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 cf 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 ofthe 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 gelatin capsule; alternatively, a dispersion or suspension can be prepared using any suitable pharmaceutical carrier(s), for example aqueous gums, celluloses, silicates 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 mg 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, ofthe 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. A suitable process comprises treating an azetidone

(II) in which: n, R' , R- and R^ are as hereinbefore defined: with an alkylating agent ofthe formula (III):

ZCR⁴R⁵X*Y

(III) in which Z is a suitable leaving group such as halogen or triflate; one of R⁴ and R^ is hydrogen or both are alkyl or cycloalkyl; and

X* con-esponds to X as hereinbefore defined, except that the ketone group is present in a protected form, preferably as a ketal; and

Y is as hereinbefore defined; in the presence of a 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; followed, if appropriate, by the steps of:

(i) oxidising the sulfide group using a suitable oxidising agent: and (ii) removing the ketone protecting group.

The preceding alkylation reaction is conveniently effected on compounds of formula (II) in which n is 0.

Compounds of formula (I) in which one of R⁴ and R^ is alkyl may also be prepared from corresponding compounds of formula (I) where both R⁴ and R^ are hydrogen by treatment thereof with an alkylating agent under the conditions described above. Such compounds may be obtained by treating a compound of formula (II) with an alkylating agent of formula (III) in which both of R⁴ and R^ is hydrogen, under alkylating conditions as hereinbefore described.

A second alkyl group for R⁴/R⁵ may be introduced by treating a first obtained compound of formula (I) in which one of R⁴ and R^ is hydrogen, with an alkylating agent in the presence of a suitable base such as sodium hydride, potassium hydroxide or lithium hexamethyldisiiazide, in a suitable alkylating solvent such as tetrahydrofuran (THF), end at a temperature in the range -80 to 10°C.

Compounds of formula (I) in which n is 1 or 2 can be readily prepared from compounds of formula (I) in which n is 0 by treatment thereof with a suitable oxidising agent such as m-chloroperbenzoic acid. Use of chiral oxidising agents such as (+)- or (-)-l,l'-bi-2-naphthol / titanium /jopropoxide (N Komatsu et al, J Org Chem, 1993, 58, 7624-7626) can give diastereoisomeric selectivity, if not chirally pure compounds. Suitably, oxidation of sulfide is carried out as a final step, prior to deprotecting the ketone group. Compounds of formula (II) in which n is 0 may be obtained by treating 4- acetoxyazetidinone, 4-benzoyloxyazetidinone or 4-phenylsulfonylazetidinone with a thiol R-^SH in the presence of a base such as sodium ethoxide, in a suitable solvent such as ethanol at a temperature in the range 0 to 5°C. When this displacement is conducted in the presence of a chiral base, such as chinchonidine or cinchonine, enantiomerically enriched compounds (II) can be obtained (J Chem Soc, Chem Commun. 1982, 1324-5)

Compounds of formula (III) may be readily prepared by adapting known synthetic procedures, according to the specific value of X. Thus, for instance, when CR⁴R⁵X represents CH2CONH(CH₂)5COPh. a suitable compound of formula (III) may be prepared by treating an amine NH2(CH2)sC[O]Ph in which [O] indicates a protecting group, for instance ketal, with 2-bromoacetic acid, or a suitable activated derivative thereof, under standard amide forming conditions.

Compounds of formula (I) in which X denotes a group CONR^B or CONR⁶OB may also be conveniently prepared by treating an acid of the formula

(IV) in which: n, KK R², R^, R⁴ and R^ are as hereinbefore defined; with an amine ofthe formula (V):

NHR5BY

(V) or a hydroxylamine of the formula (VI):

NH->OBY

(VI) in which Y and B are as hereinbefore defined, in the presence of an activating agent such as ethyl chloro formate or dicyclohexylcarbodiimide (DCC), in a suitable solvent such as chloroform or dimethyl formamide, at a temperature in the range - 10 to 20°C.

An acid of formula (IV) in which one of R⁴ and R⁵ is hydrogen may be obtained by treating a compound of formula (II) with a corresponding 2 -bromo (C 1.7) alkanoate ester, under alkylating conditions as hereinbefore described; followed by the hydrolysis ofthe thus formed intermediate ester using standard conditions. A second alkyl group may be introduced by alkylating of the first formed monoalkyl ester.

Compounds of formula (I) in which X denotes a group COOB may also be conveniently prepared by a transesterification reaction from another ester, in particular the methyl ester of formula (VII):

(VII) in which: n, Rl>, R², R3, R⁴ and R^ are as hereinbefore defined; using conditions well known in the art for such reactions, for instance heating in toluene in the presence of a catalytic amount of sodium methoxide and an alcohol.

A compound of formula (VII) in which one of R⁴ and R^ is hydrogen may be obtained by treating a compound of formula (II) with a methyl 2-bromo(Cι_7) alkanoate, under alkylating conditions as hereinbefore described. Alternatively, a compound of formula (I) in which X denotes a group COOB may be prepared by treating a compound of formula (IV) with an alcohol YBOH or an activated derivative thereof, for instance a tosylate.

Compounds of formula (I) in which denotes a group CH2OB may be prepared by a suitable ether coupling reaction, for instance treating a compound of formula (VIII):

(VIII) in which Z 1 is a halogen or other suitable leaving group such as triflate or tosylate and Rl , R², R³. R⁴ and R⁵ are as hereinbefore defined: with a compound of formula (IX):

Z²(CH₂)pC[0](CH₂)qY

(IX) in which Z² is OH or a suitable salt therof, C[O] is a protected ketone and p and q are as hereinbefore defined.

Compounds of formula (I) in which x is 1 or 2 may be obtained from compounds of formula (I) in which x is 0 or 1 (for x=2) by conventional methods for oxidising sulphur to SO or SO2 or SO to SO2, as hereinbefore described for n=l or 2, for instance m-chloroperbenzoic acid in dichloromethane. In addition, compounds of formula (I) in which n is 0 may be prepared by a process which comprises treatin formula (X):

(X) in which Rl , R², R³, R⁴ and R^ are as hereinbefore defined; with an alkylating agent of the formula (XI):

R³Z

(XD in which R^J and Z are as hereinbefore defined; under suitable alkylating conditions, for instance, in a solvent such as acetonitrile, at a temperature in the region 25°C.

Compounds of formula (X) may be obtained from the corresponding 4- W

acetylthioazetidinone by treatment with silver nitrate and a base in a suitable solvent such as methanol.

Mixtures of diastereoisomeric compounds of formula (I) may be resolved, if so desired, according to procedures well known in the art. For instance sulphoxides (n=l) may be separated by chromatography and/or crystallisation. Chirally pure compounds may be prepared by chiral chromatography, from chirally pure intermediates or by chiral synthesis using chiral reagents or catalysis. Suitable chiral intermediates may be obtained by resolution or chiral induction or by using chiral reagents, in particular natural chiral molecules, according to methods well known to those skilled in the art

The present invention will now be illustrated by the following examples. All compounds are racemic unless otherwise stated. Sulfoxides can exist in two diastereoisomeric forms which can be distinguished on the basis of their ^H NMRs. The relative configurations of the diastereoisomers is believed to be R,R/S,S (diastereoisomer 1) and R.S/S.R (diastereoisomer 2) based on NMR shifts analogy with a compound where the assignment is made by an x-ray crystal structure. When quoted as "diastereoisomer 1 " or "2" the product is mainly that diastereoisomer. Otherwise ratios of diastereoisomers are given.

Preparation of intermediates

1. 4-(Benzylthio)azetidin-2-one

Sodium (8.1g, 0.35mol) was dissolved in ethanol (250ml) and benzyl mercaptan (45.2g, 0.37mol) added dropwise over 20 minutes keeping the temperature between 20°C - 25°C whilst bubbling nitrogen through the mixture. After 15 minutes, the reaction was cooled to 5°C and a solution of 4-acetoxyazetidin-2-one (45. Og, 0.35mol) in ethanol (50ml) was added dropwise over 15 minutes whilst maintaining the temperature at 5°C. The mixture was stirred at room temperature for 60 minutes and evaporated to dryness under reduced pressure. Water (400ml) was added, the mixture extracted with dichloromethane (2x300ml), the extracts dried (MgSθ4) and evaporated under reduced pressure to an oil. The oil was cooled to -20°C and titurated with ether (400ml) to give a white solid which was isolated by filtration (50.2g, 79%), mp 50-51.0°C.

2. Methyl-(4-benzylthio-2-oxoazetidin-l-yI) acetate To a solution of 4-(benzylthio)azetidin-2-one (5.0g, 25mmol), methyl bromoacetate (4.6g, 30mmol) and tetrabutylammonium bromide (0.9g, 0.28mmol ) in dry THF (150ml) was added powdered potassium hydroxide (1.7g, 30mmol). The resulting mixture was stirred for two hours at room temperature before water (50 ml) was added. The solution was extracted with ethyl acetate (3x150ml portions) and the combined extracts dried (MgSO4) and evaporated. The residue was purified by flash chromatography on silica gel eluted with petroleum ether 60°-80°:ethyl acetate 4: 1 to give methyl (4-benzylthio-2-oxoazetidin-l-yl)acetate as a yellow oil (5g, 70%). ¹H NMR δ (CDCl₃) 2.96(lH. dd, J=2.5, 16 Hz H_3a), 3.24.3.99 (each IH, d, J=18.00 Hz, NCH₂), 3.4 (IH, dd, J=5,12.5 Hz H_3b), ³-70 (3H, s, OCH₃), 3.77 (2H, s, SCH₂), 4.92 (lH, m, H₄), 7.28 (5H, m, Ph-H)

3. (4-Benzylthio-2-oxoazetidin-l-yI)acetic acid

To a solution of methyl (4-benzyIthio-2-oxo-azetidin-l-yl)acetate (2.5g, 9.4mmol) in methanol (80ml) was added, dropwise at 0°C, a solution of 1 N sodium hydroxide (9.9ml, 9.9mmol). The reaction was stirred for 1 hr and evaporated to dryness. Water (50 ml) was added and the solution acidified to pH 3 with dilute hydrochloric acid and extracted with ethyl acetate (3x100ml) . The combined extracts were dried (MgSO4), evaporated and the residue purified by recrystallisation (hexane/ether) to give (4- benzylthio-2-oxo-azetidin-l-yl)acetic acid as a white solid (1.3g, 55%), mp 1 10-1 1 1° C. ^lH NMR δ (CDC1₃) 2.99 (IH. dd, J=6.87,17.5 Hz, H_3a), ³-²?, ⁴-06 (each IH, d, J=18.40 Hz, NCH₂), 3.39 (IH, dd, J=5,15.4 Hz, H_3b), ³-?7 (2H, s, SCH₂), ⁴-91 (IH, m, H₄), 7.27 (5H, m. Ph-H).

4 (4-(4-ethoxycarbonyl)benzylthio)azetidin-2-one a. Ethyl 4-(bromomethyl)benzoate 4-(Bromomethyl)benzoic acid (25.75g, 0.1 197moles) 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 (CDC1₃) 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-(acerylthiomethyl)benzoate

60:40 Ethyl 4-(bromomethyl)benzoate: ethyl 4-(chloromethyl)benzoate (25. Og, 0.1 1 lmoles) 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 (MgSθ4), charcoaled and evaporated to give ethyl 4- (acetylthiomethyl)benzoate as a brown soild (26.0g, 99%), m.p. 36-37°C. iH 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-(Ethoxycarbonyl)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, 0.08 Mmoles) 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 ( 10.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%). ! H nmr δ (CDCI3) 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)

Examples

Example 1 N-(6-(4-Chlorophenyl)-6-oxoxhexyl)-4-(benzylthio-2-oxoazetidin-l- yl)acetamide a. 6-(4-Chlorophenyl)-6-oxohexyl bromide

SB # SS9 5116-137

Synthesis Friedel Crafts on chlorobenzene

6-Bromohexanoyl chloride (100.9g) was added to a suspension of aluminium chloride

(66.4g) in dichloromethane (600ml) over 10 minutes. The reaction was stirred for 30 minutes and was then treated with chlorobenzene (56.3g) dropwise over 10 minutes. The reaction was stirred at room temperature for 17 hours, poured into ice-

- 1S water (11) and diethyl ether (1.51). The layers were separated and the organic layer was washed with water, sat.NaHCO3, water , brine, dried (MgSθ4) and evaporated to a red oil. Purification by flash column chromatography on silica gel eluted with [20: 1] P.E.40-60°C gave 6-(4-chlorophenyl)-6-oxohexyl bromide as a yellow oil (15.8g, 12%). b. 6-(4-Chlorophenyl)-6-oxohexyl phthalimide

SB 248559

LNB SS95116-141

Synthesis Reaction of bromide with potassium phthalimide 6-(4-Chlorophenyl)-6-oxohexyl bromide (lO.Og) and potassium phthalimide (8.3 lg) were heated in dry DMF (100ml) at 100°C for 2 hours, cooled and evaporated to dryness. The residue was partitioned between water (100ml) and diethyl ether (100ml). Ethyl acetate (100ml) was added and the layers were separated. The aqueous was washed with CH2CI2 (2x75ml). The organic extracts were combined, washed with water, brine, dried (MgSU4) ^anc* evaporated to a pale yellow solid. Recrystallisation from diethyl ether (200ml) gave 6-(4-chlorophenyl)-6-oxohexyl phthalimide as a cream solid (5.06g, 41%), m.p. l22-126°C.

IH NMR δ (CDC1₃) 1.4-1.85 (6H. m, 3xCH2), ²-94 (2H, t, J=7.2Hz. CH2CO), 3.71 (2H, t, J=7.2Hz, CH2N), 7.4-7.9 (8H, m. Ar-H) c. 6-(4-Chlorophenyl)-6-oxohexyl phthalimide ethylene acetal SB 248768 LNB SS95116-153

Synthesis keto compound and ethylene glycol Ethylene glycol (0.95g), p-toluene sulphonic acid (30mg) and 6-(4-chlorophenyl)-6- oxohexyl phthalimide (4.82g) were refluxed in toluene (75ml) using a Dean and Stark to remove water. The reaction mixture was cooled and poured into 10% K2CO3 (100ml). The layers were separated and the aqueous was washed with toluene (2x50ml). The organic extracts were combined, dried (MgSO4), and evaporated to a pale yellow solid. Nmr indicates only 50% reaction. This was reacted as above with p-toluene sulphonic acid (lOOmg) and ethylene glycol (0.97g) and extracted as above to give 6-(4-chlorophenyl)-6-oxohexyl phthalimide ethylene acetal as a yellow oil (4.85g, 90%).

IH NMR δ (CDC1₃) 1.4-1.9 (8H, m. 4xCH₂), 3.65 (4H, m,CH2θ, CH2N). 3.99 (2H, m, CH2O). 7.05-7.37 (4H. m, Phth-H), 7.66-7.84 (4H, m. p-ClPh-H) d. 6-(4-Chlorophenyl)-6-oxohexylamine ethylene acetal SB 248895 LNB CW54595-121

Synthesis hydrazine hydrate on phthalimide 6-(4-Chlorophenyl)-6-oxohexyi phthalimide ethylene acetal (4.85g) in ethanol (50ml) was treated with hydrazine hydrate ( 1.2ml) and the mixture was stirred under reflux for 3 hours, cooled and evaporated to dryness. The residue was partitioned between IN NaOH (50ml) and diethyl ether ( 100ml). Water ( 100ml) was added to give a solution and the layers were separated. The aqueous layer was washed with ether (50ml) and the organic layers were combined, washed with water, dried (MgSO4) and evaporated to give a 6-(4- chlorophenyl)-6-oxohexylamine ethylene acetal as a light brown oil (3.18g, 97%) lH NMR δ (CDCt₃) 1.2-1.42 (6H, m. 3xCH2), 1.86 (2H, m, CH2), ²-64 (2H. t.

CH2NH2), 3.74 (2H, m, CH2O), 4.03 (2H, m, CH2O), 7.42 (4H. m, Ph-H) e. N-(6-(4-ChIorophenyl)-6-oxohexyl)-4-(benzy lthio-2-oxoazetidin- 1 - yl)acetamide ethyene acetal

SB 249236

LNB CW54595-124B1

Synthesis Coupling of acid + amine

6-(4-Chlorophenyl)-6-oxohexylamine ethylene acetal (2.15g),l-cyclohexyl-3-(2- morpholinoethyl)carbodiimide metho-p-toluenesulfonate (3.37g). 1- hydroxybenzotriazole ( 1.08g) and 4-benzylthio-2-oxoazetidin-l-yl acetic acid (2.15g) (ref. WO 96/19451) in dry dimethyl formamide (30ml) was stirred at room temperature for 19 hours. The resulting suspension was diluted with diethyl ether and washed with dilute NaHCO3 (50ml). The layers were separated and the aqueous was washed with diethyl ether . The organic extracts were combined, washed with brine (x3), dried (MgSO4) and evaporated to give N-(6-(4-chlorophenyl)-6-oxohexyl)-4- (benzylthio-2-oxoazetidin-l-yl)acetarnide ethylene acetal as an orange oil (3.74g, 94%). 1H NMR δ (CDCI3) 1.23-1.5 (6H. m. 3xCH2V -85 (2H, m, CH2), 2.91. 2.97 (IH. dd, J=2.4. 15.4Hz, H3), 3.20 (2H, m, NHCH2X ³-³⁴- ³-⁴⁰ (^{1 H}> m, J=5.1. 15.4Hz.

H3), 3.36. 3.42 (IH, dd, J=5.1. 15.4Hz, H3), ³-⁴5- ³-75 (4H, m, CH2O, NCH2), ³-80 (2H, s, SCH2), ⁴-02 (2H, m, CH2O), 4.80 (IH, m, 4H), 6.0 (IH, m, NH), 7.21-7.38 (9H, m. Ph-H, p-ClPh-H) f. N-(6-(4-Chlorophenyl)-6-oxoxhexyl)-4-(benzylthio-2-oxoazetidin-l- yDacetamide

SB-249237

LNB CW54595-133

Synthesis Hcl on acetal

A solution of N-(6-⁽4-chlorophenyl)-6-oxohexyl)-4-(benzylthio-2-oxoazetidin-l - yl)acetamide ethylene acetal (3.27g) in THF (200ml ) was treated with 10%aq.HCl (170ml) and the resulting solution was stirred at room temperature for 22h. diluted with water (100ml) and extracted with diethyl ether (2x200ml). The organic extracts were combined, washed with brine, dried (MgSO4) and evaporated to an orange oil. Purification by flash column chromatography on silica gel eluted with [2: 1] to [4:1 ] ethyl acetate:P.E. 40-60°C gave N-(6-(4-chlorophenyl)-6-oxoxhexyl)-4-(benzylthio-2- oxoazetidin-l-yl)acetamide as a colourless oil (2.9 lg, 98%). IH NMR δ (CDCI3) 1.23-1.8 (6H, m, 3xCH2), ²-96 (3H, m. CH2COPh, H3), 3.28 (2H, m, NHCH2), ³-56, 3.42 (IH, dd. J=5.1. 15.4Hz, H3), 3.56, 3.74 (2H. 2xd, J = 16.8Hz. NCH2). ³-82 (2H. s. SOCH2), ⁴-83 (IH, m, 4H), 6.15 (IH, m. NH), 7.30 (5H, m. Ph-H), 7.42 (2H. m, p-ClPh-H), 7.87 (2H, m, p-ClPh-H),

Example 2 N-(6-(4-Chlorophenyl)-6-oxoxhexyl)-4-(benzylsuIphinyI-2- oxoazetidin-1 -yl)acetamide SB 249532 LNB CW54595-138E1

Synthesis OXIDATION OF SULPIDE

A solution of N-(6-(4-chlorophenyl)-6-oxohexyl)-4-(benzylsulphinyl-2-oxoazetidin- 1 - yl)acetamide (3.06g) in dichloromethane (50ml) was cooled to -70°C and treated with a solution of mcpba (2.09g) in CH2CI2 (50ml) dropwise over 5 minutes. The cooling bath was removed and the reaction was stirred for 2 hours, washed with sat. NaHCθ3 (75ml) + 10%o aq. sodium sulphite (100ml). The organic layer was washed with water, dried (MgSU4) and evaporated to a colourless solid. Recrystallisation twice from ethyl acetate gave diastereoisomer 1 as a colourless solid (0.69g, 22%), m.p. 170-172°C.

IH NMR δ (DMSO) 1.28 ⁽2H, m, CH2), I -⁴³ (2H. m, CH₂), 1 -59 (2H.m, CH₂), 2.97- 3.17 (6H, m, CH2COPh. NHCH2, ²* H3X), 3.64. 4.02 (2H. 2xd. J = 17Hz. NCH2), 3.84. 4.13 (2H, 2xd, J = 12.8Hz, SOCH2), ⁴-90 (IH, m, 4H), 7.35 (5H, m, Ph-H),~7.58 (2H, m. p-ClPh-H), 7.95 (2H, m, p-ClPh-H), 8.01 (IH, m, NH) Purification of the filtrate by flash column chromatography on silica gel, followed by recrystallisation from ethyl acetate (35ml) gave dia 2 as a colourless solid (1.07g, 34%), m.p.l07°C.

I H NMR δ (DMSO) 1.31 (2H. m, CH2), 1 -44 (2H, m, CH₂), 1.59 (2H.m. CH₂), 2.95 (3H, m. CH2COPh, H3), 3.08 (2H, m, NHCH₂), 3.30 ( IH. m, Hj), 3.85. 4.10 (2H, 2xd, J = 17.21Hz, NCH2), ⁴-0⁴> ⁴-²l (²H, 2xd, J = 12.8Hz. SOCH2), ⁴-83 (IH. m. 4H), 7.35 (5H. m, ?h-R), 7.58 (2H. m, p-ClPh-H), 7.95 (3H. m, p-ClPh-H), 8.15 (IH, m, NH)

The following compounds may be prepared according to the procedures hereinbefore described:

N-(6-(4-fluorophenyl)-6-oxohexyl)-4-(benzylsulfinyl)-2-oxoazetidin-l-ylacetamide:

N-(6-(4-chlorophenyl)-6-oxohexyl)-4-(4-ethoxycarbonylbenzylsulfinyl)-2- oxoazetidin-1-ylacetamide;

N-(6-(4-chlorophenyl)-ό-oxohexyl)-4-(4-allyloxycarbonylbenzylsulfιnyl)-2- oxoazetidin- 1 -ylacetamide;

N-(6-(4-chlorophenyl)-6-oxohexyl)-4-(4-carboxybenzylsulfinyl)-2-oxoazetidin-l- ylacetamide; (the carboxy compound may be obtained from the corresponding allyl ester by treatment thereof with triphenylphosphine, tetrakis(triphenylphosphine)palladium (0) in dry CH2CI2, as described in WO 96/19451)

N-(6-(4-fluorophenyl)-6-oxohexyl)-4-(4-ethoxycarbonylbenzylsulfinyl)-2- oxoazetidin- 1 -ylacetamide;

N-(6-(4-fluorophenyl)-6-oxohexyl)-4-(4-allyloxycarbonylbenzylsuIfinyl)-2- oxoazetidin- 1 -ylacetamide;

N-(6-(4-fluorophenyl)-6-oxohexyl)-4-(4-carboxybenzylsulfinyl)-2-oxoazetidin-l- ylacetamide; (the carboxy compound may be obtained from the corresponding allyl ester by treatment thereof with triphenylphosphine. tetrakis(triphenylphosphine)palladium (0) in dry CH2CI2, ^as described in WO 96/19451)

N-(6-(4-chlorophenyl)-6-oxohexyl)-4-(benzylsulfinyl)-2-oxoazetidin-l- ylpropionamide;

N-(6-(4-fluorophenyl)-6-oxohexyl)-4-(benzylsulfinyl)-2-oxoazetidin-l- ylpropionamide;

N-(6-(4-chlorophenyl)-6-oxohexyl)-4-(4-ethoxycarbonylbenzylsulfinyI)-2- oxoazetidin- 1 -ylpropionamide; N-(6-(4-fluorophenyI)-6-oxohexyl)-4-(4-ethoxycarbonylbenzylsulfinyl)-2- oxoazetidin- 1 -ylpropionamide;

N-(6-(4-chlorophenyl)-6-oxohexyl)-4-(4-allyloxycarbonylbenzylsulfinyi)-2- oxoazetidin- 1 -ylpropionamide;

N-(6-(4-fluorophenyl)-6-oxohexyl)-4-(4-allyloxycarbonylbenzylsulfinyl)-2- oxoazetidin- 1 -ylpropionamide;

N-(6-(4-chlorophenyl)-6-oxohexyl)-4-(4-carboxybenzylsulfinyl)-2-oxoazetidin-l-yl-

2-propionamide;

N-(6-(4-fluoropheny l)-6-oxohexy l)-4-(4-carboxybenzy lsulfinyl)-2-oxoazetidin- 1 - ylpropionamide;

l-(6-(4-fluorophenyl)-6-oxohexyloxyethyl)-4-(4-allyloxycarbonylbenzylsulfinyl)- azetidin-2-one; l-(6-(4-chlorophenyl)-6-oxohexyloxyethyl)-4-(4-allyloxycarbonylbenzylsulfinyl)- azetidin-2-one; l-(6-(4-fluorophenyl)-6-oxohexyloxyethyl)-4-(4-ethoxycarbonylbenzylsulfinyl)- azetidin-2-one; l-(6-(4-chlorophenyl)-6-oxohexyloxyethyI)-4-(4-ethoxycarbonylbenzylsulfinyl)- azetidin-2-one; l-(6-(4-fluorophenyl)-6-oxohexyloxyethyl)-4-(4-carboxybenzylsulfinyl)-azetidin-2- one; l-(6-(4-chlorophenyl)-6-oxohexyloxyethyl)-4-(4-carboxybenzylsulfmyl)-azetidin-2- one; l-(6-(4-fluorophenyl)-6-oxohexyloxyethyl)-4-(4-benzylsulfinyl)-azetidin-2-one;

1 -(6-(4-chloropheny l)-6-oxohexyloxyprop-2-yl)-4-(4-benzylsulfiny l)-azetidin-2-one; l-(6-(4-fluorophenyl)-6-oxohexyloxyprop-2-yl)-4-(4-allyIoxycarbonylbenzylsulfinyl)- azetidin-2-one; l-(6-(4-chlorophenyl)-6-oxohexyloxyprop-2-yl)-4-(4- allyloxycarbonylbenzylsulfinyl)-azetidin-2-one; l-(6-(4-fluorophenyl)-6-oxohexyloxyprop-2-yl)-4-(4-ethoxycarbonylbenzylsulfinyI)- azetidin-2-one; l-(6-(4-chlorophenyl)-6-oxohexyloxyprop-2-yl)-4-(4-ethoxycarbonylbenzylsulfinyl)- azetidin-2-one; l-(6-(4-fluorophenyl)-6-oxohexyloxyprop-2-yl)-4-(4-carboxybenzylsulfιnyI)-azetidin- 2-one; l-(6-(4-chlorophenyl)-6-oxohexyloxyprop-2-yl)-4-(4-carboxybenzylsulfinyl)- azetidin-2-one; l-(6-(4-fluorophenyl)-6-oxohexyloxyprop-2-yl)-4-(4-benzylsulfιnyl)-azetidin-2-one; and l-(6-(4-chlorophenyl)-6-oxohexyloxyprop-2-yl)-4-(4-benzylsulfinyl)-azetidin-2-one.

-2α 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-hydroxyethylpiρerazine-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 according to the present invention are found to have IC50 values in the nM range.

Claims

1. A compound of formula (I):

in which:

Rl and R², which may be the same or different, is each selected from hydrogen, halogen or C(i_g)alkyl; R³ is C(i_8)alkyl, C(3_g)cycloaIkyl or C(3_g)cycloalkylC(i_6)alkyl, aryl, aryl(C i _4)alkyl or heteroaryl(C j _4)alkyl, each of which may be optionally substituted;

R⁴ and R^ which may be the same or different is each selected from hydrogen, C(i_

6)alkyl, C(2-6)^aIkenyl, aryl, aryl(Cι_4)alkyl and heteroaryl(C \ _4)alkyl each of which may be optionally substituted, or R⁴ and R^ may be linked together to form the remainder of a (C3_7)cycloalkyl ring;

X is a linker group A-B in which A is a bond, CH2O, CO, CONR⁶, COO,

CONR⁶CO, or CONR⁶O in which R⁶ is hydrogen or Cπ _6)alkyl and B is

(CH2)pCO(CH2)q in which p is an integer from 1 to 8, preferably 3 to 5, and q is 0 or an integer from 1 to 8, preferably 0, 1 or 2, such that p + q = 1 to 12. preferably 5 to 8. more preferably 5;

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

2. A compound of formula (I) as claimed in claim 1 in which Rl and R² is each hydrogen.

3. A compound of formula (I) as claimed in claim 1 or 2 in which R^J is , R³ is

or heteroarylC(i_3)alkyl.

4. A compound of formula (I) as claimed in claim 3 in which S(O)_nR^J is optionally substitued benzylsulphinyl

5. A compound of formaula (I) as claimed in claim 4 in which S(O)_nR³ is 4- carboxybenzylsulphinyl, a C( \ _g)alkyl or Cn-6)^alkenyl ester, a pharmaceutically acceptable salts or an in vivo hydrolysable ester thereof.

6. A compound of formula (I) as claimed in any one of claims 1 to 5 in which R⁴ is hydrogen and R^ is methyl or R⁴ and R^ is each hydrogen.

7. A compound of formula (I) as claimed in any one of claims 1 to 6 in which in X, A is CH₂0 or CONH.

8. A compound of formula (I) as claimed in any one of claims 1 to 6 in which X is CONH(CH₂)5CO and CH₂O(CH₂)5CO.

9. A compound of formula (I) as claimed in any one of claims 1 to 7 in which Y is phenyl optionally substituted by halo.

10. A compound of formula (I) in which n is 1 and having the absolute configuration (4R,SS).

1 1. A compound of formula (I) selected from:

N-(6-(4-chlorophenyl)-6-oxohexyI)-4-(benzylsulfinyl)-2-oxoazetidin-l-ylacetamide;

N-(6-(4-fluorophenyl)-6-oxohexyI)-4-(benzylsulfinyl)-2-oxoazetidin-l -ylacetamide;

N-(6-(4-chlorophenyl)-6-oxohexyl)-4-(4-ethoxycarbonylbenzylsulfinyl)-2- oxoazetidin- 1 -ylacetamide;

N-(6-(4-chlorophenyl)-6-oxohexyl)-4-(4-allyloxycarbonyIbenzylsulfinyl)-2- oxoazetidin- 1 -ylacetamide; N-(6-(4-chlorophenyl)-6-oxohexyl)-4-(4-carboxybenzylsulfinyl)-2-oxoazetidin- 1 - ylacetamide;

(the carboxy compound may be obtained from the corresponding allyl ester by treatment thereof with triphenylphosphine, tetrakis(triphenylphosphine)palladium (0) in dry CH2CI2, as described in WO 96/19451)

N-(6-(4-fluorophenyI)-6-oxohexyl)-4-(4-allyloxycarbonylbenzylsulfιnyl)-2- oxoazetidin- 1 -ylacetamide;

N-(6-(4-fluorophenyI)-6-oxohexyI)-4-(4-carboxybenzyisulfιnyI)-2-oxoazetidin-l- ylacetamide;

(the carboxy compound may be obtained from the corresponding allyl ester by treatment thereof with triphenylphosphine, tetrakis(triphenylphosphine)palladium (0) in dry CH2CI2. as described in WO 96/19451)

N-(6-(4-chlorophenyl)-6-oxohexyl)-4-(benzylsuIfinyl)-2-oxoazetidin-l- ylpropionamide;

-21 N-(6-(4-fluorophenyl)-6-oxohexyl)-4-(benzylsulfinyl)-2-oxoazetidin-l- ylpropionamide;

N-(6-(4-chlorophenyl)-6-oxohexyl)-4-(4-ethoxycarbonylbenzylsulfinyl)-2- oxoazetidin- 1 -ylpropionamide; N-(6-(4-fluorophenyl)-6-oxohexyl)-4-(4-ethoxycarbonylbenzylsulfmyl)-2- oxoazetidin- 1 -ylpropionamide;

N-(6-(4-chlorophenyl)-6-oxohexyl)-4-(4- allyloxycarbonylbenzylsulfinyl)-2- oxoazetidin- 1 -ylpropionamide;

N-(6-(4-fluorophenyl)-6-oxohexyl)-4-(4-allyloxycarbonylbenzylsulfinyl)-2- oxoazetidin-1 -ylpropionamide;

N-(6-(4-chlorophenyl)-6-oxohexyl)-4-(4-carboxybenzylsulfinyI)-2-oxoazetidin-l-yl-

2-propionamide;

N-(6-(4-fluorophenyl)-6-oxohexyl)-4-(4-carboxybenzylsulfmyl)-2-oxoazetidin-l- ylpropionamide;

l-(6-(4-fluorophenyl)-6-oxohexyloxyethyl)-4-(4-allyloxycarbonylbenzylsulfinyl)- azetidin-2-one; l-(6-(4-chlorophenyl)-6-oxohexyloxyethyl)-4-(4-allyloxycarbonylbenzylsulfinyl)- azetidin-2-one; l-(6-(4-fluorophenyl)-6-oxohexyloxyethyl)-4-(4-ethoxycarbonylbenzylsulfinyl)- azetidin-2-one; l-(6-(4-chlorophenyl)-6-oxohexyloxyethyl)-4-(4-ethoxycarbonylbenzylsulfinyl)- azetidin-2-one; l-(6-(4-fluorophenyl)-6-oxohexyloxyethyl)-4-(4-carboxybenzylsulfinyl)-azetidin-2- one; l-(6-(4-chlorophenyl)-6-oxohexyloxyethyl)-4-(4-carboxybenzylsulfinyl)-azetidin-2- one; l-(6-(4-fluorophenyl)-6-oxohexyloxyethyl)-4-(4-benzylsulfinyl)-azetidin-2-one;

l -(6-(4-chlorophenyl)-6-oxohexyloxyprop-2-yI)-4-(4-benzylsulfinyl)-azetidin-2-one; l-(6-(4-fluorophenyl)-6-oxohexyloxyprop-2-yl)-4-(4-allyloxycarbonylbenzylsulfinyl)- azetidin-2-one; l-(6-(4-chlorophenyl)-6-oxohexyloxyprop-2-yl)-4-(4- allyloxycarbonyibenzylsulfmyl)-azetidin-2-one; 1 -(6-(4-fluorophenyl)-6-oxohexy loxyprop-2-y l)-4-(4-ethoxycarbony Ibenzylsulfiny 1)- azetidin-2-one; l-(6-(4-chlorophenyl)-6-oxohexyloxyprop-2-yl)-4-(4-ethoxycarbonylbenzylsulfinyl)- azetidin-2-one; l-(6-(4-fluorophenyl)-6-oxohexyloxyprop-2-yl)-4-(4-carboxybenzyIsulfinyl)-azetidin- 2-one; l-(6-(4-chlorophenyl)-6-oxohexyloxyprop-2-yl)-4-(4-carboxybenzylsulfιnyl)- azetidin-2-one; l-(6-(4-fluorophenyl)-6-oxohexyloxyprop-2-yl)-4-(4-benzylsuIfinyl)-azetidin-2-one; and l-(6-(4-chlorophenyl)-6-oxohexyloxyprop-2-yl)-4-(4-benzylsulfinyl)-azetidin-2-one.

12. A pharmaceutical composition comprising a compound of formula (I) and a pharmaceutically acceptable carrier.

->

13. A compound of formula (I) for use in therapy.

14. The use of a compound of formula (I) as defined in claim 1 in the manufacture of a medicament for treating atheroscelrosis. 0

15. The use of a compound of formula (I) as defined in claim 1 in the manufacture of a medicament for treating diabetes, hypertension, angina pectoris, after ischaemia, reperfusion, rheumatoid arthritis, stroke, myocardial infarction, reperfusion injury, sepsis, and acute and chronic inflammation, inflammatory conditions of the brain such 5 as Alzheimer's Disease, neuropsychiatric disorders such as schizophrenia, and psoriasis.

16. A method of treating a disease state associated with activity of the enzyme Lp-PL A2 which method involves treating a patient in need thereof with a 0 therapeutically effective amount of an inhibitor of the enzyme.

17. A method as claimed in claim 16 in which the disease state is associated with the increased involvement of monocytes, macrophages or lymphocytes.

5 18. A method as claimed in claim 16 in which the disease state is associated with the formation of lysophosphatidylcholine and oxidised free fatty acids.

19. A method as claimed in claim 16 in which the disease state is associated with lipid peroxidation in conjunction with Lp PLA2 activity. 0

20. A method as claimed in claim 16 in which the disease state is associated with endothelial dysfunction.

21. A process for preparing a compound of formula (I) as defined in claim 1 which 5 process comprises treating an

(ID W

in which: n, Rl, R² and R³ are as hereinbefore defined; with an alkylating agent ofthe formula (III):

ZCR⁴R5χγ

(III) in which Z is a suitable leaving group such as halogen; one of R⁴ and R^ is hydrogen; and X and Y are as hereinbefore defined; in the presence of a suitable base such as sodium hydride or potassium hydroxide, in a suitable alkylating solvent such as tetrahydrofuran (THF), and at a temperature in the range -10 to 0°C.

22. A process for preparing a compound of formula (I) as defined in claim 1 which process comprises treating a

(VIII) in which RK R², R³, R⁴ and R^ are as hereinbefore defined; with an alkylating agent of the formula (IX):

R³Z

(IX) in which R^J and Z are as hereinbefore defined; under suitable alkylating conditions, for instance, in a solvent such as acetonitrile, at a temperature in the region 25°C.