IE45491B1

IE45491B1 - Prostagladin analogues

Info

Publication number: IE45491B1
Application number: IE11/77A
Authority: IE
Original assignee: Ono Pharmaceutical Co
Priority date: 1976-01-05
Filing date: 1977-01-04
Publication date: 1982-09-08
Also published as: DK2577A; AU2104477A; NZ182968A; JPS5285151A; JPS5761276B2; AU512644B2; DK146025C; DK146025B; LU76513A1; IE45491L

Abstract

PURPOSE:Prostaglandin-like compounds of formula I (R is H, 1-4C alkyl; dotted lines represent bonding of OH group in alpha-or beta-configuration; the double bonds at C2-C3 and C14-C14 are trans-configuration), or clathrate compounds thereof in cyclodextrin, or non-toxic salts thereof when R is H; for example, 9-oxo-11alpha, 15alpha-dihydroxy-16, 16-dimethylprosta-trans-2,trans-13dienoic acid.

Description

we have described and claimed inter alia trans-/\ 5 prostaglandin analogues of the general formula:- OH (wherein Ά represents a grouping of the formula: II III IV X represents ethylene (i.e. -CH2CH2-) or trans-vinylene (i.e. -CH=CH-)j R^ represents a straight- or branchedchain alkyl radical containing from 1 to 10 carbon atoms ( or a straight- or branched-chain alkyl radical containing from 1 to 6 carbon atoms carrying a phenyl substituent or a cycloalkyl substituent of 5 to 7 carbon atoms, R2 represents a hydrogen atom or a straight- or branched- 2 chain alkyl'radical containing from 1 to 4 carbon atoms» the wavy line indicates attachment of the hydroxy radical to the carbon atom in alpha or beta configuration and the C2~C3 double bond is trans) and alkyl esters thereof having 1 to 10 carbon atoms in a straightor branched-chain, and cyclodextrin clathrates of such acids or esters» and non-toxic salts of such acids, with the exclusion of trans-2,3-didehydro-PGE^. In the aforesaid Specification it is disclosed that the compounds possess the known valuable pharmacological properties typical of prostaglandins in a selective fashion including, in particular* hypotensive activity, inhibitory activity on blood platelet aggregation, inhibitory activity on gastric acid secretion* and gastric ulceration* and bronchodilator activity and are useful in the treatment of hypertension* in the treatment of disorders of the peripheral circulation, in the prevention and treatment of cerebral thrombosis and myocardial infarction* in the treatment of gastric ulceration and in the treatment of asthma.

It has now been found after further research and experimentation that trans-Δ -prostaglandin analogues of general formula I wherein A represents the grouping of the formula: Ο ι ι ΟΗ X represents trans-vinylene, R^ represents the 1,1-dimethylpantyl group [i.e.

CH.. i 3 -C-iCHPj-CHgJ and R2 represents a hydrogen atom ch3 [viz. 16,16-dimethyl-trans-2,3-didehydro-PGB^], and the methyl ester thereof, the cyclodextrin clathrates of such an acid or ester, and non-toxic salts of such an acid, possess unexpectedly outstanding pharmacological properties.

The present invention is thus concerned with the hitherto unknown prostaglandin analogues of the general formula: IS COOH VI - 4 (wherein R3 represents the 1,1-dimethylpentyl group, the wavy line aaa. indicates attachment of the hydroxy group in beta or, preferably alpha configuration and the C2-C3 and cj3_cj4 double bonds are trans) and the methyl ester thereof, the cyclodextrin clathrates of such an acid or ester, and non-toxic (e.g. sodium) salts of such an acid.

The present invention is concerned with all such compounds in the •natural* form as depicted.

As will be apparent to those skilled in the art, the compounds depicted in general formula VI have four centres of chirality, these four centres of chirality being at the alicyclic ring carbon atoms identified as 8, 11 and 12 and at the C-15 carbon atom which has attached to it a hydroxy group. The presence of chirality leads, as is well known, to the existence of isomerism. All isomers of general formula VI and mixtures thereof are to be considered within the scope of general formula VI.

The prostaglandin analogue of formula VI wherein R3 represents the 1,1-dimethylpentyl group, and the methyl ester, and non-toxic salts thereof, have been found to possess exceptionally marked abortifacient activity and stimulatory activity on uterine contraction, activities not mentioned in the Specification of Irish Patent - 5 ssiai No. 38677 in respect of any specific compound conforming to general formula I disclosed therein» and are accordingly useful for the induction of labour in pregnant human females and» in non-human female mammals» for the termination of pregnancyi the induction of labour» the control of oestrus, contraception and menstrual regulation. Such compounds also have hypotensive activity.

The prostaglandin compounds of the present invention have relatively low potencies in inducing diarrhoea in comparison with their potencies in respect of the valuable pharmacological properties hereinbefore mentioned» and may accordingly be used for the stated purposes at appropriate rates of administration which do not induce diarrhoea as an undesired side effect.

The preferred compound of the invention in respect of its abortifacient activity and stimulatory activity on uterine contraction is 16,16-dimethyl-trans2,3-didehydro-PGE^ methyl ester. 16ι16-Dlmethvl-trans-2»3-didehydro-PGE^ methyl ester (i) stimulates uterine contraction when administered intravenously to the pregnant rat on the 20th day of gestation at a dose of 0.5 (Xg./kg. animal body weight» (ii) produces a fall of the blood pressure when administered intravenously to the allobarbital25 anaesthetised dog at a dose of 1 μg./kg. animal body weight» and (iii) produces diarrhoea at a dose of 1,200 - 6 ^3491 Eg./kg. animal body weight by oral administration in 50% of mice so treated.

Of the pharmacological activities of 16,16> I dimethyl-trans-2 < 3-didehydro-PGEj. methyl ester, (i) uterine contractile activity is the useful effect and (ii) hypotensive and (iii) diarrhoea-producing activities are considered to be undesired effects.

The pharmacological activities on rats of 16,16-dimethyltrans-2,3-didehydro-PGE^ methyl ester and of prostaglandin analogues already disclosed in the Specification of our Irish Patent No. 38677, e.g. 16(R)-methyl-trans-2>3-didehydro-PGE^, 16(ζ)-phenyl18,19, 20-trinor-trans-2,3-didehydro-PGE^ and (6)-methyl-trans-2,3-didehvdro-PGE^, are compared in the following Table. •rl in r*· O » Cl \ rH Cl o O • li X II X o o in •H in o r- in o *3* X c~ •H X σ> X o Cl in r- •H in Ch o Cl in CO «Η II CJ H 11 rH II o H CJ CJ in •H in i—| C] O Ii II X o X O O in ci X in Cl II • • o o o O in o o •rf X X X •H o II o ft H rH H TABLE •rl fi •ri 0 •Η -r| OJ φ >, . o +> · Orfi-rl Ol s k > P H-riX. 0 ni +> · k-HOOi ft P (fl 3. in co O o o in Cl o in σι Cl rH H rH OJ > ri r- 0} >, •ri C +> · -ri φ-ri 0> 01 Ή +1 >1 · 4? 0 0 01 Ο D Iii in © CM o o I CM Π I i +) co 0 o * k E CM Ό Λ m: ft fi ·*-* fO to P r-i μ I ____ ,3 Ο «Ρ ft™ I I H h H H H 0 ω >1 W tt ΰ) μ rH S £ O P £ 5 C >1 CM •P CM 0 -P CM rt >< £ 1 1 0 1 1 «Ρ 0 1 | P Λ •P co 0 g co ο ω g 0 * P g CM Ό Mil) Ό cl Π3 P TJ cl tJ $ T3 I 'Ό •H d ^•01 0 TJ r- tn rfi ID 10 Λ > 10 10 0 1-i fi I H u fi 0 H fi 0,fl H fi p a * ·<Η CO tt -r ,8 TJ - nJ P -P * 0 •ri 6 10 CO P - Θ in k •H if k •ri 0 IO p P ft Η H -P CJ dj Η -Ρ TJ H +> P 6 rH P included for purposes of clarification only). £ +> Ή •P (0 rH - 8 •iSJSl As is to be noted from the Table, 16,16-dimethyltrans-2,3-didehvdro-PGE^ methyl ester produces a strong desired effect (uterine contraction) which ia at least 10 time· mors potent than the other compounds. Moreover, the selectivity index (separation of desired activity from aide-effects, i.e. the (ii)/(i) or (iii)/(i) ratio) of 16,16-dimethvl-trana-2,3-didehvdro-PGSj methyl ester is very much higher than those of the known compounds. These data indicate that 16,16-dimethvl-trang-2,310 didehydro-PGB^ methyl ester has a strong uterine contraction activity far superior to the other compounds tested and is better and safer for the induction of labour in pregnant human females and, in non-human females, for the termination of pregnancy, the induction of labour, the control of oestrus, contraception and menstrual regulation, than the other compounds tested.

According to a feature of the present invention, the trans-A -prostaglandins of general formula VI and the methyl ester thereof are prepared by the process which comprises reacting a cyclopentane derivative of the general formula: (wherein represents a 2-tetrahydropyranyl group A 3.i'J 5 unsubstituted or substituted by at least one alkyl radical or a 1-ethoxyethyl group, preferably being the 2-tetrahydropyranyl group, R^ is as hereinbefore defined and the wavy line -w·. indicates attachment of the OR^ group to the carbon atom in alpha or beta configuration) with a dialkyl phosphonate of the general formula: (r5o)2pck2coor VIII (wherein Rg represents a methyl or ethyl radical, and Rg represents the methyl radical or a straight- or branched10 chain alkyl radical containing from 2 to 12 carbon atoms), optionally hydrolysing when Rg is the methyl radical, or hydrolysing when Rg is an alkyl radical containing from . 2 to 12 carbon atoms, the resulting trans-A -prostaglandin ester of the general formula: OH (xvherein R^, R^, Rg and ζλΖ have the meanings hereinbefore specified) to the corresponding acid of the general formula - 10 4 2 4 9 2.

OH ι (wherein Rj, R^ and /saa/ have the meanings hereinbefore specified), converting by methods known per se the 9a-hydroxy group in the compound of general formula IX (wherein Rg represents the methyl radical) or formula X to an oxo group, and hydrolysing the OR^ groups in the resulting trans-Δ -prostaglandin compound of the general formula: (wherein R represents a hydrogen atom or the methyl radical, and Rj, R^ and/W have the meanings hereinbefore specified) to hydroxy groups to obtain a PGE compound of general formula VI or a methyl ester thereof. In general formulae VII, IX, X and XI the double bonds depicted are trans as are all other double bonds depicted or in following formulae; cis double bonds in following formulae are depicted \=/ · - 11 £ S 4 9 i . By the term methods known per se as used in this Specification is meant methods heretofore used or described in the chemical literature.

The reaction between the cyclopentane derivatives of general formula VII and the dialkyl phosphonates of general formula VIII (in the form of a sodio derivative formed, for example, by reaction of sodium hydride with the dialkyl phosphonate in an inert organic medium) is carried out under the normal conditions utilised for effecting a Wittig reaction, e.g. in an inert organic solvent at a temperature not exceeding 30°C. The reaction is preferably carried out by suspending a strong base, such as sodium hydride, in an inert organic medium (e.g. tetrahydrofuran or 1,2-dimethoxyethane), adding the dialkyl phosphonate thereby to form its sodio derivative with evolution of hydrogen, and adding to the resulting solution of the sodium dialkyl phosphonate the cyclopentane derivative of general formula VII. By the Wittig reaction a trans-Δ double bond is formed stereospecifically and a compound of general formula IX is obtained.

The hydrolysis of the alkyl esters of general formula IX to the corresponding acids of general formula X may be carried out according to methods known per se, for example by treatment of the ester with an aqueous solution of an alkali metal, e.g. sodium or potassium, hydroxide or carbonate in the presence of a water-miscible organic solvent, e.g. tetrahydrofuran or an alkanol containing from 1 to 4 carbon atoms, e.g. methanol.

The PGF alicyclic ring in the compounds of general formulae IX (wherein Rg represents the methyl radical) and X can be converted into a PGE ring by methods known per se for the conversion of a hydroxy group in the 9-position of a prostaglandin to an oxo group, for example by means of a chromic acid solution (e.g. obtained from chromium trioxide, manganese sulphate and sulphuric acid in water) or Jones' reagent.

The OR^ groups of the compounds of general formula XI may be converted to hydroxy groups by mild hydrolysis with an aqueous solution of an organic acid, e.g. acetic acid, or with a dilute aqueous inorganic acid, e.g. hydrochloric aedd, advantageously in the presence of an organic solvent miscible with water, e.g. tetrahydrofuran or an alkanol containing from 1 to 4 carbon atoms, e.g. methanol. The mild hydrolysis may be carried out at a temperature ranging from ambient to 60°C. (preferably at a temperature below 45°C.) with an acid mixture, e.g. a mixture of hydrochloric acid with tetrahydrofuran or methanol, or a mixture of acetic acid, water and tetrahydrofuran.

The products of general formula VI or the methyl •i 3 4 9 i esters thereof may be purified by column chromatography on silica gel, which procedure may, when the intermediate compound of general formula XI is a mixture of compounds with the OR4 group in the 15-position in a- or β5 configurations, lead to a separation of the resulting 15a-hydroxy and 15p-hydroxy isomers of general formula VI or ester thereof.

The cyclopentane derivatives of general formula VII employed as starting materials in the aforedescribed process can be prepared from bicyclo-octane derivatives of the general formula: (wherein R^, R^ and λλλ. have the meanings hereinbefore specified and the depicted double bond is trans) by application of procedures described in the Specification of Irish Patent No. 38677 for the preparation of analogous cyclopentane derivatives.

The dialkyl phosphonate starting materials of general formula VIII can be synthesised by the procedure described by G.M. Kosolapoff, J. Amer. Chem. Soc. 68, 1103 4549i (1946), according to the reaction sequence:0 0 0 || ' NaOC-H- || C1CH-COOR- || (R50)2PH-(R5O)2PNa ---=-» (R50)2PCH2COORg wherein R_ and R, are as hereinbefore defined. o The compounds of general formula XII can he 5 prepared using initially 2-oxa-6-syn-£ormyl-7-antiacetoxy-cis-bicyclo[3.3.0]octan-3-one [E.J. Corey et al, J. Amer. Chem. Soc., 91, 5675 (1969)] and the sodio derivative of a dialkyl phosphonate of the general formula: (R70)_PCH.CR, XIII 2,, 2,, 3 0 (wherein Ry represents an alkyl group containing from 1 to 4 carbon atoms and R^ is as hereinbefore defined) and applying thereto known procedures [see, for example, J. Amer. Chem. Soc., 92, 397 (1970) and French Patent No. 7215314 (publication No. 2134673)].

The dialkyl phosphonates of general formula XIII can be prepared by reacting a solution of n-butyllithium in diethyl ether with a solution of a dialkyl methylphosphonate of the general formula: (R70)_PCH, XIV 7 2|l 3 (wherein Ry is as hereinbefore defined), e.g. dimethyl methylphosphonate or diethyl methylphosphonate, in tetrahydrofuran at a temperature below - 50°C., and then adding - 15 -•1 tA ii yi dropwise to the reaction mixture a solution of a compound of the general formula: RqOOCRj XV (wherein Rg represents an alkyl group containing from 1 to 4 carbon atoms and Rj is as hereinbefore defined) in tetrahydrofuran at a temperature below -50°C., for 2 to 4 hours, and then stirring for 2 to 18 hours at a temperature ranging from ambient to 0°C., to give the desired dialkyl phosphonate of general formula XH, - 16 According to a further feature of the present . ? invention, the trans-A '-prostaglandin analogues of general formula VI and their methyl esters are prepared by the process which comprises reacting a compound of the general formula:- (wherein the various symbols and ΖΛΖ have the meanings hereinbefore specified, R^ preferably being the 2-tetrahydropyranyl group) with a compound of the general formula:- (wherein Rg and R1(J, which may be the came or different, each represents a straight- or branched-chain alkyl group containing from 1 to 6 carbon atoms or a cycloalkyl group containing from 3 to 6 carbon atoms), e.g. lithium diisopropylamide,to obtain a lithium esterenolate of the general formula:15 ft £5 *4 9 A OLi ι (wherein the various symbols and -w/ have the meanings hereinbefore specified), reacting the lithium esterenolate with benzeneselenenyl bromide (i.e. 0SeBr in which 0 represents the phenyl radical) or diphenyl diselenide or a dialkyl or diphenyl disulphide of the formula wherein the symbols R·^ both represent alkyl groups containing from 1 to 4 carbon atoms or phenyl radicals, hydrolysing the resulting intermediate to convert the —OLi group attached to the cyclopentane ring to an a-hydroxy group and to obtain a compound of the general formula :OH (wherein the various symbols and zwx have the meanings hereinbefore specified, and Q represents -Se0, in which 0 is as hereinbefore defined, or a group -SR·^, in which R-q is as hereinbefore defined), treating the resulting compound with hydrogen peroxide or sodium periodate, and *019 ’ decomposing the resulting compound of the general formula:OH (wherein the various symbols and ~w have the meanings hereinbefore specified) to convert the grouping COOR, '6 attached to the 8-position of the 0=0 z\. zN COORg cyclopentane ring to a trans-A -grouping £ , wherein Rg is as hereinbefore defined, i.e. to obtain a compound of general formula IX, wherein the various symbols and aazs are as hereinbefore defined, and treating the compound of formula IX as hereinbefore described to obtain a prostaglandin analogue of general formula VI or methyl ester thereof.

The reaction between the prostaglandin compound of general formula XVI and the lithiated amine of general formula XVII is carried out in an organic solvent, for example by adding dropwise a solution of a prostaglandin compound of formula XVI in tetrahydrofuran to a solution of an amine of formula XVII in tetrahydrofuran at a low temperature, e.g. -70°C., the ratio of the molecular ΰ ·4 3 A equivalents of the compounds of formula XVI to XVII in \ the reaction mixture being 1:2 to 3. After completion of the addition of the prostaglandin solution, the reaction mixture is stirred at the same temperature for about 30 minutes to obtain a solution of the lithium esterenolate of formula XVIII.

The reaction between the lithium esterenolate of formula XVIII and benzeneselenenyl bromide, diphenyl diselenide or dialkyl or diphenyl disulphide is preferably carried out in tetrahydrofuran, diethyl ether, hexane or pentane or a mixture of two or more of them, tetrahydrofuran being the preferred solvent, at a low temperature, e.g. -70°C. Thus, to the lithium esterenolate solution obtained as described above there is added a solution in tetrahydrofuran of 3 or 4 molecular equivalents of benzeneselenenyl bromide or diphenyl diselenide, or 2 to 3 molecular equivalents of dialkyl or diphenyl disulphide, for each molecular equivalent of lithium esterenolate present, the temperature of the two solutions being -70°C. The reaction mixture is stirred at -70°C. (a) for one hour when a selenium compound is the reactant or (b) for 30 minutes when a disulphide is the reactant, and subsequently at ambient temperature, e.g. 15°C. for 30 minutes. After addition of, for example, a small amount of a saturated aqueous ammonium chloride solution to the solution of the resulting prostaglandin - 20 4 5 4 91 intermediate to hydrolyze the —OLi group attached to the cyclopentane ring to an α-hydroxy group» the product of formula XIX is extracted with ethyl acetate.

When the product of formula XIX is a compound wherein Q is benzeneselenenyl, i.e. -Se0, the ethyl acetate solution of the product is then treated with 5 to 7 molecular equivalents of hydrogen peroxide at a temperature below 30°C. or with 5 molecular equivalents of sodium periodate in the presence of a lower alkanol, preferably methanol and water, at a temperature below 20°C., preferably for about 24 hours, to form a compound of formula XX wherein 0=Q- is benzeneseleninyl, i.e. -Se(O)0, and stirring of the reaction mixture at a temperature of 25° to 30°C. for one hour results in decomposition of the compound to a compound of general formula IX, which can be separated from the reaction medium by methods known per se and purified by column chromatography on silica gel.

When the product of formula XIX is a compound wherein Q is a group -SR^i R^ being as hereinbefore defined, the product is separated from the ethyl acetate solution by methods known per se and treated with hydrogen peroxide or sodium periodate in the same way as hereinbefore described for a product of formula XXX wherein Q is benzeneselenenyl to obtain a compound of general formula XX wherein Q is a group -SR^·^, R-q being as hereinbefore defined, which •i a 4 3 1 can be separated from the reaction medium by methods known per se.

When the compound of formula XX is one wherein Q represents an alky lthio group —SRn' wherein R·^ represents an alkyl group containing from 1 to ή carbon atoms, the compound is dissolved in toluene and the solution stirred, •preferably in the presence of a small amount of calcium carbonate, at a temperature of 100° to 120°C. for a period ranging from 5 to 2Zj hours to decompose the compound to a compound of general formula IX. When the compound of general formula XX is one wherein Q represents the phenylthio group, the compound is‘dissolved in carbon tetrachloride and the solution stirred, preferably in the presence of a small amount of calcium carbonate, at a temperature of about 50°C. for a period ranging from 5 to 2Z| hours to decompose the compound to a compound of general formula IX. The compounds of general formula IX can be separated from the reaction medium by methods known per se and purified by column chromatography on silica gel.

The starting materials of general formula XVI employed in this feature of the present invention can be prepared from the corresponding acids of the general formula (wherein R^, and have the meanings hereinbefore specified) by reaction with (i) diazoalkane compounds, e.g. diazomethane, (ii) alcohols in the presence of dicyclohexylcarbodiimide as condensing agent, (iii) alcohols following the formation of a mixed acid anhydride by adding a tertiary amine and then a pivaloyl halide or an arylsulphonyl or alkylsulphonyl halide (cf. our British Patents Nos. 1362956 and 1364125), (iv) alkyl halides, e.g. methyl iodide, and (a) potassium carbonate in acetone [cf. J. Org. chem. 34, 3717 (1969)], (b) sodium bicarbonate in Ν,Ν-dimethylacetamide or N,N-dimethylformamide [cf. Advan. Org. Chem. 5, 37 (1965)], (c) calcium oxide in dimethyl sulphoxide [cf. Synthesis, 262 (1972), or (v) N,N-dimethylformamide - dialkylacetals, e.g.

N,N-dimethylformamide - dimethylacetal, in dry benzene [cf. Helv. Chim. Acta, 48, 1746 (1965)].

Compounds of general formula XXI may be prepared by reacting a bicyclo-octane derivative of general formula XII, wherein Rg, Rj and have the meanings hereinbefore specified, with (4-carboxybutylidene)triphenyIphosphorane of the formula 0gP=CH-(CH2)g-COOH (herein fS is as hereinbefore defined) to obtain a cyclopentane derivative £5 49 i of the general formula:OH COOH XXII (wherein Rj, R^ and have the meanings hereinbefore specified) and hydrogenating by methods known per se the cis-double bond in the Cg-Cg position to obtain an acid of general formula XXI. Mild reducing conditions should be used for the said reduction step in order to reduce only the C^-Cg double bond and not to affect the C^g-C·^ double bond. Suitably the reduction may be effected by hydrogenation in the presence of a hydrogenation catalyst, for example palladium on charcoal, in the presence of an inert organic solvent, for example a lower alkanol, e.g. methanol or ethanol, at laboratory temperature at normal or elevated pressure, e.g. at a hydrogen pressure from atmospheric to 15 kilograms per square centimetre. Advantageously the quantity of hydrogen which reacts is observed during the course of the reaction so that the reaction may be terminated before any reduction of the ^3-^14 double bond to ethylene occurs.

The reaction between the bicyclo-octane of general formula XII and (4-carboxybutylidene)triphenylphosphorane [obtained by the reaction of sodium methyl- 24 sulphinylmethylide with (4-carboxybutyl)triphenylphosphonium bromide] is carried out under the normal conditions utilized for effecting the Wittig reaction, e.g. in an inert solvent at ambient temperature. The reaction is preferably carried out in dimethyl sulphoxide because the phosphorane compound is practically insoluble in other solvents, e.g. tetrahydrofuran, and because a cis-double bond must be formed stereospecifically in the Wittig reaction. For the better performance of the Wittig reaction more than two molecular equivalents of the phosphorane compound are required for each mole of the bicyclo-octane reactant. The reaction is generally effected at a temperature of 10-40°C, preferably at 20-30°C., and is usually complete after about 30 minutes to four hours at laboratory temperature. The acid product of formula XXII may be extracted from the reaction mixture by conventional procedures and further purified by column chromatography on silica gel.

The lithiated amines of general formula XVII employed in the aforementioned process of the invention, for example lithium diisopropylamide, and benzeneselenenyl bromide and diphenyl diselenide can be prepared by known methods, for example as described in J. Amer. Chem. Soc., 95, 6139 (1973).

According to a further feature of the present •iS ISA invention, the '2,3rdidehydro-prostaglandin analogues of general formula VI and their methyl esters are prepared by the process which comprises reacting a compound of the general formula:- 0R4 XXIII (wherein represents a straight- or branched-chain alkyl group containing from 1 to 4 carbon atoms, R13 represents an alkanoyl group containing from 2 to 5 carbon atoms, and is as hereinbefore defined, preferably the 2-tetrahydropyranyl group) with the sodio derivative of a dialkyl phosphonate of general formula XIII (wherein R^ and Ry are as hereinbefore defined) to obtain a compound of the general formula:- XXIV (wherein the various symbols are as hereinbefore defined), reducing the 15-oxo group in the compound of general formula XXIV to a hydroxy group by methods known per se to obtain a compound of the general formula: 13 OR.

XXV (wherein the various symbols and αλλ are as hereinbefore specified), reacting the obtained compound with dihydropyran unsubstituted or substituted with at least one alkyl radical, or ethyl vinyl ethyl, to obtain a compound of the general formula:- XXVI (wherein the various symbols and/vware as hereinbefore specified), hydrolysing under alkaline conditions the resulting compound to obtain a compound of the general formula:- (wherein R represents a hydrogen atom or a methyl group and R^, R^ and have the meanings hereinbefore specified), «S491 converting by methods known per se the Sa-hydroxy group in the compound of general formula XXVII to an oxo group, and hydrolysing the OR^ groups in the resulting compound of the general formula:- (wherein R, Rg, R^ and v.' have the meanings hereinbefore specified) to hydroxy groups to obtain a PGE compound, of general formula VI or a methyl ester thereof.

The reaction between an aldehyde of general formula XXIII and the sodio derivative of a dialkyl phosphonate of general formula XIII is carried out under the normal conditions utilized for effecting the Wittig reaction. Preferably the reaction is effected by suspending sodium hydride in an inert organic solvent, e.g. tetra15 hydrofuran or 1,2-dimethoxyethane, and adding the dialkyl phosphonate of general formula XIII. The resulting sodio derivative of the dialkyl phosphonate may then be reacted with the compound of general formula XXIII at a temperature of 20°C. to 45°C. to form the trans-enone compound of general formula XXIV stereoselectively.

The reduction of the 15-oxo group of a compound 4S19i of general formula XXIV to a hydroxy group is suitably effected (1) with excess sodium borohydride in an alkanol containing from 1 to 4 carbon atoms, e.g. methanol, at a low temperature, preferably at -30°C. to -60°C., or (2) with zinc borohydride in a suitable inert organic solvent, e.g. 1,2-dimethoxyethane, at a temperature of -10°c. to 10°c.

The product thus obtained is a mixture of isomers of general formula XXV in Which the 15-hydroxy group is in aor β-configuration. If desired, the isomer having the hydroxy group in α-configuration may he separated from the isomor having the hydroxy group in β-configuration by column chromatography on silica gel. The separated isomers may be utilized in the procedures herein described to give prostaglandin analogues of general formula VI or methyl esters thereof in which the hydroxy group in position 15 is in a- or β-configuration.

The reaction of a compound of general formula XXV with a dihydropyran or ethyl vinyl ether is carried out in an inert organic solvent, e.g. methylene chloride, in the presence of a condensing agent, e.g. p-toluenesulphonic acid.

The hydrolysis of compounds of general formula XXVI under alkaline conditions may be effected (1) with an aqueous solution of an alkali metal, e.g. sodium or potassium, hydroxide or carbonate in the presence of a water miscible solvent, e>g. tetrahydrofuran or an alkanol containing from 1 to 4 carbon atoms, to give compounds of general formula XXVII wherein R represents a hydrogen atom, or (2) with anhydrous potassium carbonate in anhydrous methanol to give compounds of general formula XXVII wherein R represents the methyl radical, Conversion of the hydroxy group in the 9-position of the PGF compounds of general formula XXVII to an oxo group may be effected by methods known per se for the conversion of a PGP alicyclic ring into a PGE ring, for example by means of a chromic acid solution (e.g. obtained from chromium trioxide, manganese sulphate and sulphuric acid in water) or Jones’ reagent.

( Hydrolysis of the OR^ groups of the compounds of general formula XI to hydroxy groups may be effected by means heretofore described for effecting such a conversion.

Compounds of general formula XXIII (wherein the various symbols are as hereinbefore defined) are new compounds. They may be prepared by a new synthetic route from known compounds of formula XXVIII, depicted hereafter, by the series of reactions depicted schematically below in Scheme A, wherein the various symbols are as hereinbefore defined. - 30 SCHEME A OH OH XXXV XXIII ok4 or4 - 31 10 Compounds of general formula XXVIII may be reduced to give compounds of general formula XXIX. Suitably the reduction may be effected by hydrogenation in the presence of a hydrogenation catalyst, e.g. palladium on charcoal, palladium black or platinum dioxide, in an inert organic solvent, for example a lower alkanol, e.g. methanol or ethanol, at laboratory temperature at normal or elevated pressure, e.g. at a hydrogen pressure from atmospheric to 15 kg./cm2.

Compounds of general formula XXXI may be prepared by the process which comprises reacting a compound of general formula XXIX with a compound of general formula XVII, wherein Rg and are as hereinbefore defined, to obtain a lithium compound of the general formula: OLi t I z'X/XZ OLi COOR Li XXXVL OR/, (wherein and R^^ are as hereinbefore defined), reacting tho lithium compound with benzeneselenenyl bromide (i.e. CgHgSeBr), or diphenyl diselenide or a dialkyl disulphide of diphenyl disulphide of general formula R^^SSR^^, in which it is as hereinbefore defined, hydrolysing the resulting intermediate to obtain a compound of general formula XXX, 'll - 32 aSiUl treating the resulting coinpound with hydrogen peroxide or sodium periodate, and decomposing the resulting compound of the general formula: %/X/\ /coor12 0=o XXXVII (wherein the various symbols are as hereinbefore defined) y\ χοοοκ. to convert the grouping z \S \X γ tz attacned to 0=0 the 8-position of the cyclopentane ring to a trans-Δ' grouping / Χ/Χ/Χ/^θθΧζ , wherein Rl2 is as hereinbeforedefined.

The reaction between a compound of general formula XXIX and a Iithiated amine of general formula XVII is carried out in an inert organic solvent, e.g. totrahydrofuran, at a low temperature, e.g. at -78°C., the ratio of the molecular equivalents of a compound of general formula XXIX to XVII in the reaction mixture being suitably adjusted to obtain a lithium compound of general formula xxxvl.

The reaction between the lithium compound of general formula XXXVTand benzeneselenenyl bromide, diphenyl diselenide or a dialkyl disulphide or diphenyl disulphide is preferably carried out in an inert organic solvent, e.g. tetrahydrofuran. .>5 49 i hexamethylphosphotriamide, diethyl ether, n-hexane or n-pentane or a mixture of two or more of them, at a low temperature, e.g. at -78°C.

The product of general formula XXX is 5 converted to a compound of general formula XXXI by the procedure already described for the conversion of a compound of general formula XIX to a compound of general formula IX.

Compounds of general formula XXXII may be prepared by reacting compounds of general formula XXXI with trimethylchlorosilane in an inert organic solvent, e.g. methylene chloride, in the presence of a base, e.g. pyridine or a tertiary amine, at a low temperature, e.g. at -30°C to 0°C.

Compounds of general formula XXXIII may be prepared by reacting a trimethylsilyl ether of general formula XXXII with an appropriate acyl chloride or acid anhydride in an inert organic solvent, e.g. methylene chloride, in the presence of a base, e.g. pyridine or a tertiary amine, at a low temperature, e.g. at 0° to 30°C. - 34 ..,3 4 9 ί> Ί Compounds of general formula XXXV may be prepared by treating compounds of general formula XXXIII by methods known per se for the removal of the trimethylsilyl group, for example by treatment with an acid: it is preferable not to use a strong acid in order to avoid the risk of the removal of the group R^.

Compounds of general formula XXXV may also be prepared by acylation of compounds of general formula XXXI (by means heretofore mentioned for the conversion of compounds of general(formula XXXII into those of general formula xxxill) to compounds of general formula XXXIV, and hydrolysing those compounds with an alkali metal, e.g. potassium or sodium, carbonate in an alkanol containing from 1 to 4 carbon atoms, e.g. methanol, at a moderately low temperature, e.g. at 0°-5°C.

Compounds of general formula XXXV may be converted to compounds of general formula XXIII under mild and neutral conditions, for example with chromium trioxide-pyridine complex or Jones' reagent, or dimethyl or methylphenyl sulphide-N-chlorosuccinimide complex or dimethyl or methylphenyl sulphide-chlorine complex [ef. J. Amer. Chem. Soc., 9A, 7586, (1972)], or dicyclohexylearbodiimide-dimethyl sulphoxide complex [cf. J. Amer. Chem. Soc., 87, 5661 (1965)], at a moderately low temperature.

Compounds of general formula XXVIII used as starting .,5 491 material in the series of reactions depicted in Scheme A may be prepared by the methods described in Belgian Patent Specification Ko. 838582 from the Itnown compound of formula XXXVIII [prepared as described in J. Amer. Chem. Soc., Si, 5675 (1969) and ibid, 92 397 (1970)] by the series of reactions depicted schematically below in Scheme B, wherein Ac represents the acetyl group and the other symbols are as hereinbefore defined. - 36 .-iS lOA SCHEME B or4 XXVIII ..

Compounds of formula XXXIX may be prepared by hydrolysis under alkaline conditions of compounds of formula XXXVIII, for example using potassium carbonate in methanol. Compounds of formula XL may be obtained by the acetylation of compounds of formula XXXIX under mild conditions and may be converted to compounds of general formula XLI by reaction with a dihydropyran or ethyl vinyl ether in an inert organic solvent, e.g. methylene chloride, in the presence of a condensing agent, e.g. p-toluenesulphonic acid. Compounds of general formula XLII may be prepared by reducing compounds of general formula XLI with diisobutylaluminium hydride in toluene at a temperature below -60°C. Dimsyl anion, previously prepared from sodium hydride and dimethyl sulphoxide, is reacted with (4-carboxybutyl)triphenylphosphonium bromide to form (4-carboxybutylidene)triphenylphosphorane.

To that compound is added a compound of general formula XLII and the mixture in dimethyl sulphoxide is made to react at room temperature to yield compounds of general formula XLIII. The acids of general formula XLIII are then esterified io give compounds of general formula XXVIII by means heretofore mentioned for the conversion of compounds of general formula XXI to those of general formula XVI.

The. methyl ester of the trans- /\2-prostaqlandin of general formula VI can be obtained by reaction of the acid with (i) diazomethane, (ii) methanol in the presence of /5491 Patents Nos. 1,362,956 and 1,364,125).

An acid of general formula VI may, if desired, be converted by methods known per se into non-toxic salts. By the term non-toxic salts, as used in this Specification, is meant salts the cations of which are relatively innocuous to the animal organism when used in therapeutic doses so that the beneficial pharmacological properties of the compounds of general formula VI are not vitiated by side-effects ascribable to those cations. Preferably, the salts are water-soluble. Suitable salts include the alkali metal, e.g. sodium and potassium, and ammonium salts and pharmaceutically-acceptable (i.e. nontoxic) amine salt. Amines suitable for forming such salts with carboxylic acids are well known and include, for example, amines derived in theory by the replacement of one or more of the hydrogen atoms of ammonia by groups, which may be the same or different when more than one hydrogen atom is replaced, selected from, for example, alkyl groups containing from 1 to 6 carbon atoms and hydroxyalkyl groups containing from 1 to 3 carbon atoms.

The non-toxic salts may be prepared from the acid of general formula VI by, for example, reaction ^45-lSi of stoichiometric quantities of the acid of general formula VI and the appropriate base, e.g. an alkali metal hydroxide or carbonate, ammonium hydroxide, ammonia or an amine, in a suitable solvent. The salts may be isolated by lyophilisation of the solution, or, if sufficiently insoluble in the reaction medium, by filtration, if necessary after removal of part of the solvent.

The trans-Δ -prostaglandin analogue of general 10 formula VI and the methyl ester thereof may, if desired, be converted into cyclodextrin clathrates. The clathrates may be prepared by dissolving the cyclodextrin in water and/or an organic solvent which is miscible with water and adding to the solution the prostaglandin compound in a water-miscible organic solvent. The mixture is then heated and the desired cyclo'dextrin clathrate product isolated by concentrating the mixture under reduced pressure or by cooling and separating the product by filtration or decanting. The ratio of organic solvent to water may be varied according to the solubilities of the starting materials and products. Preferably the temperature is not allowed to exceed 70°C., during the preparation of the cyclodextrin clathrates. α, β or γ-Cyclodextrins or mixtures thereof may be used in the preparation of the cyclodextrin clathrates.

Conversion into their cyclodextrin clathrates serves to increase the stability of the prostaglandin compounds. - 40 45491 The following Reference Examples and Examples illustrate the preparation of new prostaglandin analogues of the present invention. In them ’IR*, ’NMR· and ’TLC’ represent ’Infrared absorption spectrum*; ’Nuclear magnetic resonance spectrum’ and ’Thin layer chromatography* I respectively. Where solvent ratios are specified in chromatographic separations, the ratios are by volume.

REFERENCE EXAMPLE 1 Synthesis of (2-oarboxyethyl)triphenylphosphonium bromide A solution of 90 g of triphenylphosphine and 50 g of 3-bromopropionic acid in 550 ml of acetonitrile was refluxed for two days. The reaction mixture was then distilled under reduced pressure to remove acetonitrile, and the residue was stirred well together with diethyl ether, and then the upper ethereal layer removed by decantation.

The operation was repeated twice to form the crystalline product, which was recrystallised from acetonitrile; yield of the title compound; 115 g, m.p. 195 - 198°C.

IR (potassium bromide tablet); 2880, 1740, 1434, 1382, 1322, 1230, 1105, 745, 690, 520 and 505 cm1.

REFERENCE EXAMPLE 2 Synthesis of 9a-hydroxy~ll«,15g-bis-(2-tetrahydropyranyloxy)-16,16-dimethyl-2,3-dinorprost-trans-13-enoic acid A solution of 92 g of (2-carboxyethyl)triphenylphosphonium bromide (prepared as described in - 41 « S 4 S ί Reference Example 1) in 200 ml of dimethyl sulphoxide was mixed with 200 ml of a 2.1M solution of sodium mathylsulphinylmethylide in dimethyl sulphoxide whilst maintaining the temperature at 25°C. To the resulting red mixture was added 150 'ml of a solution containing 34 g of 2-oxa-syn-(3a-2B-tetrahydropyranyloxy-4,4-dimethyl-octtrans-l-enyl)-7-anti-(2-tetrahydropyranyloxy)-cis-bicyclo [3,3,0]octan-3-ol [prepared as described in British Patent Specification No 1 398 291, Preparation 6] in dimethyl sulphoxide. The resulting mixture was stirred for 2 hours at 25°C and 1 hour at 4o°C and then poured into a mixture of 3.5 litres of ice-water, 500 ml of diethyl ether and 6 g of potassium carbonate, and extracted with ethyl acetate. The aqueous layer was extracted three times with a mixture of diethyl ether and ethyl acetate (1:1) to remove the neutral substances. The aqueous layer was adjusted to pH 2 with oxalic acid and extracted 4 times with a diethyl ether-pentane mixture (1:1), and the extract was washed with water, dried and concentrated under reduced pressure. The residue was purified by silica gel column chromatography using an ethanol-benzene mixture (1:20) as eluent to give 9a-hydroxy-lla,15a-bis(2-tetrahydropyranyloxy)-16,16-dimethyl-2,3-dinorprostacis-(and trans)-5,trans-13-dienoic acids as a colourless oil in a yield of 12 g.

TLC (developing solvent, methylene chloride:methanol = 19:1): Rf = 0.21. Λΰ·ΐ3ί The product was dissolved in 300 ml of methanol, mixed with 4 g of 5% palladium on carbon and treated with an equimolar amount of hydrogen at room temperature. The reaction mixture was filtered with a glass filter to remove the catalyst and the filtrate concentrated under reduced pressure to yield the title compound (12 g).

TLC (developing solvent, methylene chloride:methanol = 19.1): Rf = 0.21.

REFERENCE EXAMPLE 3 Synthesis of methyl 9g-hydroxy-ll«.15g-bis-(2-tetrahydropyranyloxy)-16,16-dimethyl-2,3-dinorpro3t-trans-13enoate To a solution of 6 g of 9a-hydroxy-lla,15abis-(2-tetrahydropyranyloxy)-16,16-dimethyl-2,3-dinorprost15 trans-13-enoic acid (prepared as described in Reference Example 2) in 100 ml of diethyl ether was added a freshly prepared solution of diazomethane in diethyl ether until the reaction mixture became yellow. The reaction mixture was then concentrated under reduced pressure at a lew temperature, and the residue purified by means of silica gel column chromatography using an ethyl acetatecyclohexane mixture (1:1) as eluent to yield 4.92 g of the title compound as a colourless oil.

TLC (developing solvent, ethyl acetate:cyclohexane = 1:1): Rf = 0.59. _Λΰ 49 i REFERENCE EXAMPLE 4 Synthesis of 9K-hydroxy-llg,15a-bis-(2-tetrahydropyranyloxy)-16,16-dimethyl-2,3-dinorprost-trans-13-enaldehvde A solution of 8 g of the product of Reference Example 3 in 230 ml of toluene was cooled to -65°C, mixed with 34 ml of toluene solution containing diisobutylaluminium hydride (25% w/v)e and the reaction mixture stirred for 30 minutes at the same temperature. Methanol was gradually added dropwise and, after the bubbling stopped, the resulting mixture was raised to 0°C, then stirred with 50 ml of water for 30 minutes. The aluminium hydroxide which formed was filtered off, and the filtrate was washed with an aqueous sodium chloride solution, dried over magnesium sulphate and concentrated under reduced pressure to obtain the title compound as a colourless oil: yield 8 g.

TLC (developing solvent, ethyl acetate:cyclohexane = 1:1): Rf = 0.44.

REFERENCE EXAMPLE 5 Synthesis of ethyl 9ft-hydroxy-llg,15o:-bis-(2-tetrahydropyranyloxy)-16,16-dimethylprosta-trans-2.trans13-dienoate To a mixture of 1.02 g of sodium hydride (purity 65%) and 110 ml of tetrahydrofuran was added dropwise, with stirring, 6.2 g of triethylphosphonoacetate, the reaction mixture being maintained at a _ 44 _ u519i temperature less than 30°C. Stirring was continued at 25 ®C for 30 minutes until the evolution of hydrogen stopped. 4 g of the product of Reference Example 4 in 135 ml of tetrahydrofuran were added thereto, and the resulting mixture was stirred for 50 minutes at 25°C, adjusted to pH 7 with acetic acid, diluted with water, extracted with diethyl ether and the ethereal extract washed with water, dried and concentrated. The residue was purified by silica gel column chromato10 graphy using an ethyl acetate-cyclohexane mixture (1:3) as eluent to obtain 4 g of the title compound as a colourless oil.

TLC (developing solvent, ethyl acetate:cyclohexane = 1:1): Rf = 0.55.

REFERENCE EXAMPLE 6 Synthesis of 9-oxo-lla,15a-bis-(2-tetrahydrppyranvioxv)16.16-dimethylpro3ta-trans-2,trans-13-dienoic acid g of ethyl 9a-hydroxy-lla,15a-bis-(2-tetrahydropyranyloxy)-16,16-dimethylprosta-trans-2,trans-13 dienoate (prepared as described in Reference Example 5) were dissolved in 130 ml of a mixture of ethanol and water (3:1), mixed with 3.9 g of potassium hydroxide and stirred at 25°C for 2 hours. The reaction mixture was then acidified with an aqueous solution of oxalic acid to pH 5, diluted with 100 ml of water and extracted with ethyl acetate. These extracts were washed with water, dried over sodium sulphate and concentrated under reduced _ 45 u 1 pressure to obtain 3.88 g of 9a-hydroxy-lloc,15acbi s-(2-tetrahydropyranyloxy)-16.16-dimethvlprosta-tran s2,trans-13-dienoic acid.

TLC (developing solvent, ethyl acetate:cyclohexane = 1:1): Rf = 0.18. 2.46 g of the obtained compound were dissolved in 72 ml of diethyl ether and the solution stirred at 3°C. A solution of 15 g of manganese sulphate, 3.1 g of chromium trioxide, 72 ml of v/ater and 3.5 ml of sulphuric acid was added. After stirring for 3.5 hours at 3°C, the reaction mixture was extracted with diethyl ether. The organic layer was washed with water, dried over sodium sulphate and concentrated under reduced pressure. The residue was purified by column chromatography on silica gel using ethyl acetatebenzene (1:1) as eluent to give 2.35 g of the title compound having the following physical characteristics. TLC (developing solvent, methylene chloride:nethanol = 20:1): Rf = 0.24; IR (liquid film); 2925, 2850, 1740, 1690, 1645, 1445, 1375, 1350, 1240, 1140, 1090, 1045 and 980 cm-1. •λ β ·1 3 1 EXAMPLE 1 Synthesis of 16,16-dimethyl-trans-2.3-didehydro-PGE·^ [9-oxo-lla,15a-dihydroxy-16,16-dimethvlprosta-trans2,trans-13-dienoic acid] 2.35 g of 9-oxo-lla,15a-bis-(2-tetrahydropyranyloxy )-16,16-dimethvlprosta-trans-2,trans-13-dienoic acid (prepared as described in Reference Example 6) were dissolved in 6 ml of tetrahydrofuran and 60 ml of a 65% (v/v) aqueous acetic acid solution and the solution stirred at 60° to 70°C for 20 minutes. The reaction mixture was then extracted with ethyl acetate, and the organic layer was washed with water, dried and concentrated under reduced pressure. The residue was purified by column chromatography on silica gel using ethyl acetate-cyclohexane (2:3) as eluent to yield 270 mg of the title compound.

TLC (developing solvent, tetrahydrofuran:chloroform:acetic acid = 2:10:1): Rf = 0.30.

IR (liquid film): 3400, 2930, 1740, 1695, 1650, 980, 870 and 850 cm-1.

NMR (CDC13 solution): 7.2 - 6.8 (1H, m), 6.6 - 5.37 (6H, m), 5.03 - 4.7 (1H, m).

EXAMPLE 2 Synthesis of 16,16-dimethyl-trans-2,3-didehydro-PGE^ methyl ester 50.8 g of 16,16-dimethyl-trans-2,3-didehydroPGE^ (prepared as described in Example 1) were dissolved in 3 ml of diethyl ether, and to the solution a freshly 49 i prepared ethereal solution of diazomethane was added so that the reaction mixture turned yellow. The reaction mixture was concentrated under reduced pressure at a low temperature, and the residue purified by column chromatography on silica gel using ethyl acetate-cyclohexane (1:3) as eluent to give 40 mg of the title compound. TLC (developing solvent, chloroform:tetrahydrofuran:acetic acid = 10:2:1): Rf 0.51; IR (liquid film): 3400, 2940, 2850, 1750, 1730, 1660, 1440, 1280 cm-1.

NMR (CDClg solution): 7.10 - 6.75 (IH, m), 5.95 - 5.40 (3H, m), 3.71 (3H, s), 4.20 - 3.60 (2H, m), 2.75 (IH, dd), I. 00 - 0.75 (9H, m).

REFERENCE EXAMPLE 7 Methyl 9g-hydroxy-lla,15a-bis-(2-tetrahydropyranyloxy)16.16- dimethylprosta-trans-2,trans-13-dienoate A solution of 1545 mg of diisopropylamine in 33 ml of tetrahydrofuran was cooled to -70°C, and to it II. 9 ml of a solution Of n-butyllithium in hexane (1.3 molar concentration) were added dropwise and stirred for 15 minutes at -70°C to give lithium diisopropylamide.

To the lithium diisopropylamide solution 3.42 g of methyl 9a-hydroxy-llo:,15a-bis-(2-tetrahydropyranyloxy)16.16- dimethylprost-trans-13-enoate in 17 ml of tetrahydrofuran were added dropwise at -70°C and the reaction mixture stirred for 30 minutes at the same temperature. A solution of 2.75 g of diphenyl diselenide in 17 ml of tetrahydrofuran was added dropwise to the reaction mixture at -70°C and stirring was continued for 1 hour at the same temperature and then for 30 minutes at room tenperature. The reaction mixture was poured into a small amount of a saturated aqueous solution of ammonium chloride, and extracted with 263 ml of ethyl acetate.

The organic layer was washed with a small amount of IN hydrochloric acid and a saturated aqueous solution of sodium bicarbonate. Maintaining the temperature below 30°C, 4.7 ml of 30% hydrogen peroxide were added dropwise and the reaction mixture stirred for 1 hour at 23 °C. The reaction mixture was then washed successively with water, a saturated aqueous solution of sodium carbonate and a saturated aqueous splution of sodium chloride, dried over anhydrous magnesium sulphate and concentrated under reduced pressure. The residue was purified by column chromatography on silica gel using cyclohexaneethyl acetate (3:1) as eluent to give 2.33 g (68%) of the title compound having the following physical characteristics:IR (liquid film): 3450, 2930, 2850, 1725, 1660, l440, 1140, 1080, and 980 cm-1; TLC (developing solvent, benzene:cyclohexane = 1:1): Rf = 0.55.

The methyl 9a-hydroxy-lla,15a-bis-(2-tetrahydropyranyloxy )-16,16-dimethvlprost-trans-13-enoate - 49 4 & 1 used as starting material in the procedure described above-was prepared by esterification of the corresponding acid, 9ix-hydroxy-lla,15a-bis-(2-tetrahydropyranyloxy)-16, 16-dimethvlprost-trans-13-enoic acid using an ethereal solution of diazomethane. The said acid was prepared by a procedure similar to that described in J. Amer. Chem,Soc. 92, 2586 (1970) for the preparation of 9a-hydroxyllg,15g-bis-(2-tetrahydropyranyloxy)-prost-trans-13enoic acid.

REFERENCE EXAMPLE 8 9-Oxo-lla,15g-bis-(2-tetrahydropyranyloxy)-16,16-dime thylprosta-trans-2,trans-13-dienoic acid '3.95 g of methyl 9g-hydroxy-lla,15a-bis-(2tetrahydropyranyloxy)-16,16-dimethylprosta-trans2,trans-13-dienoate (prepared as described in Reference Example 7) were dissolved in a mixture of 32 ml of ethanol, 6ml of water and 1270 mg of potassium hydroxide and the solution was stirred at below 50°C for 2 hours.

The reaction mixture was acidified with aqueous sulphuric acid and diluted with ethyl acetate. The organic layer was washed with water, dried over sodium sulphate and concentrated under reduced pressure to obtain 3.66 g of 9g-hydroxy-lla,15g-bis-(2-tetrahydropyranyloxy)-16,16dimethylprosta-trans-2,trans-13-dienoic acid. 2.82 g of the 9g-hydroxy-llg,15g-bis-(2tetrahydropyranyloxy-16,16-dimethylprosta-trans-2.trans13-dienoic acid obtained were dissolved in 138 ml - 50 4S4Si of diethyl ether and the solution stirred at 0°C.

A solution of manganese sulphate (24.8 g), 5.5 g of chromium trioxide, 124 ml of water and 5.8 ml of sulphuric acid was. added. After stirring for 1.5 hours at 0 to 5°C, the reaction mixture was extracted with ethyl acetate. The organic extract was washed with water, dried over sodium sulphate and concentrated under reduced pressure. The residue was purified by column chromatography on silica gel using ethyl acetate-benzene (1:1) as eluent to give 2.35 g of the title compound having the same physical characteristics as the product of Reference Example 6.

EXAMPLE 3 16,16-Dimethvl-trans-2,3-didehydro-PGE 2.35 g of the bis-tetrahydropyranyl ether prepared as described in Reference Example 8 were dissolved in a mixture of 1.8 ml of tetrahydrofuran and 18 ml of 65% (v/v) aqueous acetic acid and the solution stirred at 60 to 70°C for 20 minutes. The reaction mixture was extracted with ethyl acetate, and the organic layer was washed with water, dried and concentrated under reduced pressure. The residue was purified by column chromatography on silica gel using ethyl acetatecyclohexane (2:3) as eluent to yield 270 mg of the title compound having the same physical characteristics as the product of Example 1. - 51 ^349 A ' EXAMPLE 4 16.16-dimethyl-trans-2,3-didehv6ro-PGE^ methyl ester 50.8 mg of 16,16-dimethyl-trans-2,3-didehydroPGE1 (prepared as described in Example 3) were dissolved in 3 ml of diethyl ether, and to the solution a freshly prepared ethereal solution of diazomethane was added so that the reaction mixture turned yellow. The reaction mixture was concentrated under reduced pressure at low temperature, and the residue purified by column chromatography on silica gel using ethyl acetate-cyclohexane (Is3) as eluent to give 40 mg of the title compound having the same physical characteristics as the product of Example 2.

REFERENCE EXAMPLE 9 2a-(6-Methoxvcarbonylhexvl)-38-hydroxvmethvl-4a:-(2te trahydropyranyloxy)cyclopen tan-lff-ol 14.2 g of 2a-(6-methoxycarbonylhex-cis-2-envl)3p-hydroxymethyl-4a-(2-tetrahydropyranyloxy)cyclopentanla-ol was hydrogenated at a pressure of one atmosphere in 300 ml of methanol containing 3 g of 5% (w/w) palladium on charcoal. The reduction was stopped after the absorption of one equivalent of hydrogen. The catalyst was removed by filtration and the filtrate was concentrated under reduced pressure to give 13.8 g of the title compound having the following physical characteristics:- 52 TLC (developing solvent, benzene:ethyl acetate = 1:1): Rf = 0.28; IR (liquid film): 3450, 1740, l440. 1030 cm1; NMR (CDClg solution): 5.00-4.55 (IH, m), 3.70 (3H, s). 2a-(6-Methoxycarbonvlhex-cis-2-envl)-3βhydroxymethyl-4a-(2-tetrahydropyranyloxy)cyclopentan-la-ol, used as a starting material in the above procedure, was prepared from 2-oxa-3-oxo-6-syn-hydroxvmethvl-7-antiacetoxy-cis-bicyclo[3,3,0loctane, [prepared as described by E. J. Corey et al, J. Amer. Chem. Soc. 92, 397 (1970)] as follows:190 g of 2-oxa-6-svn-hydroxvmethvl-7-anti-acetoxvcis-bicyclo-[3,3,0]octan-3-one in 1.5 litres of absolute methanol and 130 g of potassium hydroxide were stirred at room temperature for one hour, and then successively cooled in an ice-bath, and neutralized with hydrochloric acid. The precipitate was filtered off and the filtrate was concentrated under reduced pressure. The residue was washed with ethanol, and then with ethyl acetate, and dried to give 124 g of 2-oxa-6-avn-hvdroxvmethvl-7-anti-hvdroxycis-bicyclor 3.3.01octan-3-one as white crystallites having the following physical characteristics:mp 119°C; IR (KBr tablet): 3350,2970 - 2880, 1740, 1480, 1440, 1410, 1380, 1335, 1305, 1270, 1205, 1100, 1080, 1060, 1040, 1020, 1000 and 975 cm-1; /5491 t NMR (CDClj + deutero dimethyl sulphoxide solution): ,10 - 4.60 (IH, m), 4.29 (2H, s). 4.13 - 3.77 (IH, m) and 3,.38 (2H. d); TLC (developing solvent, methylene chloride:methanol = :1): Rf = 0.27. 124 g of 2-oxa-6-syn-hvdrQxymethyl-7-anti-hvdroxycis-bicyclo-[3,3,0]octan-3~one (obtained as described above) were dissolved in absolute pyridine (1.4 litres) and cooled to -40°C. 74 g of acetic anhydride were added dropwise and the mixture stirred for 5 hours at -40° to -20°C and then for 16 hours at 0°C. The pyridine was evaporated off under reduced pressure and the residue was dissolved in 1 litre of ethyl acetate. 200 g of sodium bisulphate were added, and the mixture stirred vigorously and filtered* The filtrate was concentrated under reduced pressure and the residue was purified by column chromatography on silica gel using a benzene-ethyl acetate mixture (1:3) as eluent to give 112 g of 2-oxa-6-syn-acetoxy-methyl-7-anti-hydroxy-cisbicyclo[3,3,0]octan-3-one as colourless needles having the following physical characteristics:mp: 36° to 37°C; IR (KBr tablet): 3450, 2960, 2850, 1775, 1740, 1420, 1370, 1250, 1190, 1120, 1090, 1040 and 980 cm-1; NMR (CDClg solution): 5.15 - 4.60 (IH, m), 4.3 - 3.75 (3H„ m), 3.50 (IH, s) and 2.02 (3H, s)} TLC (developing solvent methylene chloride:methanol = :1): Rf = 0.74. - 54 <*S4.3 g of- 2-oxa-6-syn-acetoxyniethyl-7-anti-hydroxyci3-bicyclo-F3,3,0]octan-3-one (obtained as described above) were dissolved in 520 ml of methylene chloride, g of dihydropyran and 0.52 g of p-toluenesulphonic acid were added and the mixture stirred for 20 minutes at room temperature. The reaction mixture was neutralized with an aqueous solution of sodium bicarbonate, diluted with ethyl acetate, washed with water, dried and concentrated under reduced pressure to give 56 g of 2-oxa-6-svnacetoxvmethvl-7-anti-(2-tetrahydropyranyloxy)-cis-bicvclo [3,3,0]octan-3-one' as a colourless oil having the following physical characteristics:XR (liquid film): 2950 - 2840, 1775, 1740, 1465, 1440, 1390 - 1340, 1240, 1180, 1140 - 1120, 1080, 1040 and 980 cm' NMR (CDClg solution): 5.2 - 4.72 (IH, m), 4.72 - 4.30 (IH, m), 4.2 - 3.2 (5H, ro) and 2.01 (3H, s)j TLC (developing solvent, methylene chloride:roethanol = 20:1): Rf = 0.74. g of the acetyl ether (prepared as described above) were dissolved in 900 ml of toluene and cooled to -60°C.456 ml of a 25 (w/v,% toluene solution of diisobutylaluminium hydride were added and the mixture stirred for 20 minutes at the same temperature; methanol was added in order to decompose the excess of diisobutylaluminium hydride and water was added. The resulting precipitate was filtered off and the filtrate was dried and concentrated under reduced pressure to give 35.2 g of 2-Oxa-6-syn-hvdroxvmethvl-7-anti-(2-tetrahydropyranyloxy)55 4-S191 cis-bicyclor3.3.0loctan-3-ol as a colourless oil-having the following physical characteristics:IR (liquid film): 3400, 2940 - 2860, 1465 - 1440, 1380, 1355, 1325, 1260, 1200, 1140, 1120, 1075, and 1020 cm-1: TLC (developing solvent, ethyl acetate): Rf = 0.25. 37.6 g of sodium hydride (content 63.5%) were suspended in 4θθ ml of dimethyl sulphoxide and stirred at 70°C for 1.5 hours to obtain sodium methylsulphinylmethylide. The reaction mixture was allowed to cool to room temperature and then added dropwise to a solution of 226 g of (4-carboxybutyl)triphenylphosphonium bromide in 460 ml of dimethyl sulphoxide, the reaction temperature being kept within the range of 20° to 25°C.

A solution of 35.2 g of 2-oxa-6-svn-hvdroxvmethvl-715 anti-(2-tetrahydropyranyloxy)-cis-bicvclof3,3,0]octan-3-ol (prepared as described above) in 90 ml of dimethyl sulphoxide was added to the above reaction mixture and stirred at 35° to 4o°C for 1.5 hours. The reaction mixture was then poured into 6 litres of ice-water and the neutral substances were removed by extraction with an ethyl acetate-diethyl ether mixture (1:1). The aqueous layer was acidified to pH 2 with saturated aqueous oxalic acid solution and extracted with a diethyl ether-n-pentane mixture (1:1). The organic layer was washed with water, dried over sodium sulphate and concentrated under reduced pressure. Ths residue was subjected to column chromatography on silica gel using a benzene-methanol mixture (10:1) as - 56 -45191 eluent to give 35 g of 2a-(6-carboxvhex-cis-2-envl)-36-hvdroxvmethyl-4a-{2-tetrahydropyranyloxy)-cyclopentan-la-ol as a colourless oil having the following physical characteristics:IR (liquid film): 3400, 2940 - 2860, - 2300, 1710, 1450, 1435, 1400, 1355, 1245, 1200, 1140, 1120, 1075, and 1025 cm-1; NMR (CDClg solution): 6.20 (3H, s), 5.50 - 5.10 (2H, m), 4.75 - 4.36 (1H, m), 4.24 - 3.85 (2H, m), and 3.85 3.0 (4H, m): TLC (developing solvent, chloroform:tetrahydrofur an:acetic acid = 10:2:1): Rf = 0.53.

To a solution of 18.8 g of 2a-(6-carboxvhex-cis2-enyl)-3p-hydroxymethyl-4a-(2-tetrahydropyranyloxy)cyclopentan-la-ol (obtained as described above) in 130 ml of diethyl ether, a freshly prepared ethereal solution of diazomethane was added with cooling in an ice-bath until the reaction mixture showed a pale yellow colour. The reaction mixture was concentrated in vacuo, and the residue was subjected to column chromatography on silica gel using a cyclohexane-ethyl acetate mixture (2:1) as eluent to give .4 g of 2a-(6-methoxycarbonvlhex-cis-2-envl)-36-hvdroxvmethyl-4a~(2-tetrahydropyranyloxy)-cyclopentan-la-ol as a colourless oil having the following physical characteristics:IR (liquid film): 3450, 2950 - 2870, 1740, 1440, 1360, 1325, 1250, 1200, 1140, 1120, 1080, and 1025 cm1; NMR (CDClg solution): 5.55 - 5.00 (2H, m), 4.78 - 4.30 (III, m), 4.20 - 3.06 (6H, m), 3.55 (3H, s) and 2.97 (2H, s); TLC (developing solvent, methylene chloride:methanol = 19:1) Rf = 0.43. - 57 4 91 ' ' REFERENCE EXAMPLE 10 2α-(6-Phenylseleno-6-msthoxvcarbonylhexyl)-36hvdroxymethyl-4a- (2-tetrahydropyranyloxy) cyclopentanla-ol Under an atmosphere of nitrogen, a solution of 19.4 ml of diisopropylamine in 350 ml of tetrahydrofuran was cooled to -78°C, and to it was added dropwise 114 ml of a 1.2M solution of n-butyllithium in n-hexane. The mixture was stirred at -78°C for 20 minutes to give lithium diisopropylamide. To the lithium diisopropylamide solution was added dropwise a solution of 13.8 g of 2a-(6-methoxy carbonylhexyl)-36-hydroxymethyl-4a-(2-tetrahydropyranyloxy) cyclopentan-la-ol (prepared as described in Reference Example 9) in 100 ml of tetrahydrofuran at -78°C and the mixture was stirred at the same temperature for 30 minutes. A solution of 18.2 g of diphenyl diselenide in 50 ml of tetrahydrofuran was added dropwise to the reaction mixture at -78°C and the solution was stirred at the sane temperature for one hour and then at 0°C for 20 minutes. The reaction mixture was poured into an aqueous solution of ammonium chloride and extracted with ethyl acetate. The extract was washed vath water and an aqueous solution of sodium chloride, dried over magnesium sulphate and concentrated under reduced pressure. The residue was purified by column chromatography on silica gel using a mixture of benzene and ethyl acetate (3:2) as eluent to give αδ.191 .8 g of the title compound having the following physical char acteristics: TLC (developing solvent, benzene:ethyl acetate = 1:1): Rf = 0.37; IR (liquid film): 3450, 1740, 1580, Ι44θ, 1030 cm-1; NMR (CDC13 solution): 7.75-7.10 (5H, m), 5.00-4.55 (IH, m), 3.70 (3H. s).

REFERENCE EXAMPLE 11 2a-(6-Methoxycarbonylhex-trans-5-enyl)-3P~hydroxymethyl4a-(2-tetrahydropyranyloxy)cyclopentan-la-ol To a solution of 15.8 g of 2a-(6-phenylseleno-6methoxycarbonylhexyl)-3p~hydroxymethyl-4a-(2-tetrahydropyranyloxy) cyclopentan-la-ol (prepared as described in Reference Example 10) in a mixture of 200 ml.of ethyl acetate and 100 ml of tetrahydrofuran were added 4.5 g of sodium carbonate and 6.2 ml of 30% hydrogen peroxide and the mixture'was stirred at 30°C for 30 minutes.

The reaction mixture was then poured into water, washed with an aqueous solution of sodium carbonate, water and an aqueous solution of sodium chloride, dried over magnesium sulphate and concentrated under reduced pressure to give .4 g of the title compound having the following physical char acteristics: TLC (developing solvent, benzene:ethyl acetate = 1:1): Rf = 0.28; IR (liquid film): 3450, 1735, 1660, 1440, 1030 cm-1; - 59 ft 5 491 NMR (CDClg solution): 6.90 (IH, dt), 5.82 (IH, d), .00 - 4.55 (IH, m), 3.70 (3E, s).

REFERENCE EXAMPLE 12 la-Acetoxy-2a-(6-methoxvcarbonvlhex-trans-5-envl) -3βhydroxymethyl-4a- (2-tetr ahydropyranyloxy) cyclopentane Under an atmosphere of nitrogen, a solution of 4.3 ml of trimethylchlorosilane in 20 ml of methylene chloride v/as added dropwise to a solution of 10.4 g of 2a- (6-methoxycarbonylhex-tran s-5-enyl) -3p-hydroxyirtethyl4a-(2-tetrahydropyranyloxy)cyclopentan-la-ol (prepared as described in Reference Example 11) in a mixture of 150 ml of methylene chloride and 18.8 ml of pyridine at -20°C and the mixture was stirred at the same temperature for 20 minutes. To the solution thus obtained was added dropwise a solution of 2.45 ml of acetyl chloride in 50 ml of methylene chloride at -20°C. and the mixture was stirred at room temperature for 30 minutes. Then 3 ml of ethanol was added to the reaction mixture in order to decompose the excess of acetyl chloride. Pyridine in the solution was quenched with 80 g of sodium bisulphate, and the resulting precipitate was filtered off. The filtrate was concentrated under reduced pressure. The residue was dissolved in 300 ml of ethyl acetate, 100 ml of a saturated aqueous solution of oxalic acid was added and the mixture was stirred vigorously at room temperature for 30 minutes. The reaction mixture was extracted with ethyl acetate, the extract was washed with water, an aqueous - 60 4C191 solution of sodium hisulphate, water and an aqueous solution of sodium chloride, dried over magnesium sulphate and concentrated under reduced pressure. The residue was purified by column chromatography on silica gel using a mixture of benzene and ethyl acetate (3:1) as eluent to give 7.2 of the title compound having the following physical characteristics: TLC (developing solvent, benzene:ethyl acetate = 1:1): Rf = 0.51; IR (liquid film): 3450, 1735, 1660, 1440, 1030 cm-1; NMR (CDClg solution): 6.90 (lH, dt), 5.82 (IH, d), .25-4.90 (IH, m), 4,85-4.45 (IH, m), 3.71 (3H, s), 2.05 (3H, s).

REFERENCE EXAMPLE 13 la-Acetoxy-2a-(6-methoxvcarbonvlhex-trans-5-envl)-3βformyl-4a-(2-tetrahydropyranyloxy)cyclopentane Under an atmosphere of nitrogen, 34 ml of pyridine were dissolved in 440 ml of methylene chloride, .2 g of chromium trioxide were added with stirring and the mixture was stirred at room temperature for 15 minutes. 88 g of infusorial earth were added to the reaction mixture which was then cooled to 0°C. A solution of 7.2 g of lg-acetoxy-2g-(6-methoxy-carbonvlhex-trans-5enyl)-3p-hydroxymethyl-4a-{2-tetrahydropyranyloxy) cyclopentane (prepared as described in Reference Example 12) in 100 ml of methyl chloride at 0°C was added. After 10 minutes stirring at Q°C, 155 g of sodium bisulphate were added to the reaction mixture and stirring was continued for a further 10 minutes. The resulting precipitate was filtered through a pad of magnesium sulphate and the filtrate was concentrated under reduced pressure. The residue was purified by column chromatography on silica gel using a mixture of benzene and ethyl acetate (5:1) as eluent to give 5.85 g of the title compound having the following physical characteristics: TLC (developing solvent, benzene: ethyl acetate = 2:1): Rf 0.67: IR (liquid film): 1735, 1660, ΐ44θ» 1250, 1030 cm-1; NMR (CDCl3 solution): 10.00-9.70 (1H, m), 6.90 (1H, dt), .82 (IH, d), 5.30-4.96 (1H, m), 4.75-4.10 (2H, m), 3.72 (3H, s), 2.06 (3H, s).

REFERENCE EXAMPLE 14 Methyl 9 Under an atmosphere of nitrogen, a solution of 1.62 g of dimethyl 2-oxo-3,3-dimethylheptylphosphonate (pjq?ared as described in British Patent Specification No 1 398 291) in 6 ml of tetrahydrofuran was added to a suspension of 230 mg of sodium hydride (63^ content) in 50 ml of tetrahydrofuran and. the mixture was stirred at room temperature for 30 minutes. To the solution thus obtained was added a solution of 1.98 g of la-acetoxy-2a(6-methoxvcarbonylhex-trans-5-envl)-3p-formyl-4a-(2tetrahydropyranyloxy)cyelopentane (prepared as described in «5391 Reference Example 13) in 10 ml of tetrahydrofuran at room temperature and the solution was stirred at the same temperature for one hour. The reaction mixture was quenched with acetic acid, filtered through a pad of silica gel and the filtrate was concentrated under reduced pressure. The residue was purified by column chromatography on silica gel using a mixture of benzene and ethyl acetate (8:1) as eluent to give 2.36 g of the title oompound having the following physical characteristics: TLC (developing solvent, benzene:ethyl aeetate = 2: 1): Rf = 0.71; IR (liquid film): 1730, 1660, 1630, 1440, 1030 cm-1; NMR (CDClg solution): 7.20-6.50 (2H, m), 6.16 (IH, d), .80 (IH, d), 5.30-4.90 (IH, m), 4.80-4.50 (IH, m), 3.72 (3H, s), 2.06 (3H, s), 1.10-0.70 (9H, m).

REFERENCE EXAMPLE 15 Methyl 9g-acetoxy-llg-(2-tetrahydropyranyloxy)-15αhydroxy-16,16-dimethvlprosta-tran s-2,trans-13-dienoate To a solution of 2.36 g of methyl 9a-acetoxy20 lla-(2-tetrahydropyranyloxy)-15-0X0-16,16-dimethylprostatrans-2.trans-13-dienoate (prepared as described in Reference Example 14) in 40 ml of methanol was added 700 mg of sodium borohydride at -40°C and the solution was stirred at that temperature for 20 minutes. The reaction mixture was quenched with acetic acid and concentrated under reduced pressure.

The residue was dissolved in ethyl acetate and the solution - 63 was washed with an aqueous solution of sodium bicarbonate and an aqueous solution of sodium chloride, dried over magnesium sulphate and concentrated under reduced pressure. The residue was purified by column chromatography on silica gel using a mixture of benzene and ethyl acetate (4:1) as eluent to give 790 mg' of the title compound, 810 mg of its 156-hydroxy isomer and 480 mg of a mixture of the isomers. The title compound showed the following physical characteristics: TLC (developing solvent, benzene:ethyl acetate = 2:1): Rf 0.38s (156-hydroxy isomar, Rf = 0.47); IR (liquid film): 3450, 1730, 1660, 1440, 1030, 980 cm-1; NMR (CDC13 solution): 7.20-6.70 (IH, m), 6.10-4.90 (4H, m), 4.80-4.50 (IH, m), 3.72 (3H, s), 2.06 (3H, s), 1.10-0.70 (9H,m).

REFERENCE EXAMPLE 16 Methyl 9a-acetoxy-llK,15cc-bis-(2-tetrahydropyranyloxy)16,16-dimethvlprosta-trans-2,trans-13-dienoate To a solution of 790 mg of methyl 9a-acetoxy20 lla-(2-tetrahydropyranyloxy)-15a-hydroxy-16,16-dimethylprostatrans-2,trans-13-dienoate (prepared as described in Reference Example 15) in 15 ml of methylene chloride were added 5 mg of p-toluenesulphonic acid and 0.3 ml of 2,3-dihydropyran and the mixture was stirred at room temperature for 20 minutes.

The reaction mixture was diluted with 50 ml of ethyl acetate, washed with an aqueous solution of sodium chloride, dried over - 64 4 519 2 magnesium sulphate and concentrated under reduced pressure to give 930 mg of the crude title compound having the following physical characteristics: TLC (developing solvent, benzene:ethyl acetate = 2:1): Rf = 0.67; IR (liquid film): 1730, 1660, 1440, 1030, 980 cm-1; NMR (CDClg solution): 7.20-6.70 (1H, m), 6.10-4.90 (4H, m), 4.80-4.50 (2H, m), 3.72 (3H, s), 2.06 (3H, s), 1.10-0.70 (9H, m).

REFERENCE EXAMPLE 17 Methyl 9a-hydroxy-lla,15a-bis-(2-tetrahydropyranyloxy)16,16-dimethvlprosta-trans-2,tran s-13-dienoate To a solution of 930 mg of methyl 9a-acetoxy11a,15a-bis-(2-tetrahydropyranyloxy)-16,16-dimethylprostatrans-2.trans-13-dienoate (prepared as described in Reference Example 16) in 12 ml of methanol was added 400 mg of potassium carbonate and the mixture was stirred at 40°C for 1.5 hours. The reaction mixture was quenched with acetic acid and extracted with ethyl acetate. The extract was washed with an aqueous solution of sodium bicarbonate, water and an aqueous solution of sodium chloride, dried over magnesium sulphate and concentrated under reduced pressure. The residue was purified by column chromatography on silica gel using a mixture of benzene and ethyl acetate (6:1) as eluent to give 745 mg of the title compound having the following physical characteristics: - 65 , TLC (developing solvent, benzene:ethyl acetate = 2:1): Rf = 0.47; IR (liquid film): 3450, 1730, 1660, l440, 1030, 980 cm-1; NMR (CDClg solution): 7.20-6.70 (IH, m), 6.10-5.30 (3H, m), 4.80-4.50 (2H, m), 3,72 (3H, s), 1.10-0.70 (9H, m).

EXAMPLE 5 Methyl 9-oxo-lla,15a-dihydroxy-l6,16-dimethylprostatrans-2.trans-13-dienoate [or 16.16-dimethyl-trans-2,310 didehydro-PGE^ methyl ester] To a solution of 745 mg of methyl 9a-hydroxy11a,15a-bis-(2-tetrahydropyranyloxy)-16,16-dimethylprostatrans-2.trans-13-dienoate (prepared as described in Reference Example 17) in 22 ml of diethyl ether was added a chromic acid solution (obtained from 0.94 g of chromium trioxide, 4.55 g of manganese sulphate and 1.06 ml of sulphuric acid in 22 ml of water), and the mixture was stirred at 0°C for one hour. The reaction mixture was then extracted with diethyl ether and the extract was washed with an aqueous solution of sodium chloride, dried over magnesium sulphate and concentrated under reduced pressure to give 732 mg of methyl 9-oxo-lla,15a-bis-(2-tetrahydropyranvloxy)-16,16dimethyIprosta-tran s-2,trans-13-dienoate having the following physical characteristic: TLC (developing solvent, benzene:ethyl acetate = 2:1): Rf = 0.74. 45-3 9 1 To a solution of 73έ mg of the 9-oxo-compound (prepared as described above) in 1.9 ml of tetrahydrofuran was added 19 ml of a 65% (v/v) aqueous solution of acetic acid and the mixture was stirred at 55°C to 60°C for one hour. The reaction mixture was then extracted with ethyl acetate and the extract was washed with water and an aqueous solution of sodium chloride, dried over magnesium sulphate and concentrated under reduced pressure to give 119 mg of the title compound having the same physical characteristics as the product of Examples 2 and 4.

The present invention includes within its scope pharmaceutical compositions which comprise, as active ingredient, at least one prostaglandin analogue of general formula VI or the methyl ester thereof, or a cyclodextrin clathrate of such a prostaglandin analogue or methyl ester thereof, or a non-toxic salt of such a prostaglandin analogue, together with a pharmaceutical carrier or coating. In clinical practice the new compounds of the present -,,3 431 invention will normally be administered orally, vaginally, rectally or parenterally.

Solid compositions for oral administration include compressed tablets, pills, dispersible powders, and granules. In such solid compositions one or more of the active compounds is, or are, admixed with at least one inert diluent such as calcium carbonate, potato starch,alginic acid,mannitol,or lactose. The compositions may also comprise, as is normal practice, additional substances other than inert diluents, e.g. lubricating agents, such as magnesium stearate. Liquid compositions for oral administration include pharmaceuticallyacceptable emulsions, solutions, suspensions, syrups and elixirs containing inert diluents commonly used in the art, such as water and liquid paraffin. Besides inert diluents such compositions may also comprise adjuvants, such as wetting and suspending agents, and sweetening, flavouring, perfuming and preserving agents. The compositions according to the invention, for oral administration, also include capsules or absorbable material such as gelatin containing one or more of tile active substances with or without the addition of diluents of excipients.

- Solid compositions for vaginal administration include pessaries formulated .in manner known per se and containing one or more of the active compounds.

Solid compositions for rectal administration include suppositories formulated in manner known per se and containing one or more of the active compounds.

Preparations according to the invention for parenteral administration include sterile aqueous or non-aqueous solutions, suspensions, or emulsions.

Examples of non-aqueous solvents or suspending media are propylene glycol, polyethylene glycol, vegetable oils such as olivq oil, and injectable organic esters such as ethyl oleate. The compositions may also include adjuvants such as preserving, wetting, emulsifying and dispersing agents. They may be sterilised, for example, by filtration through a bacteria-retajriing filter, by incorporation of sterilising agents in the compositions or by irradiation, They may also be manufactured in the form of sterile solid compositions, which can be dissolved in sterile water or some other sterile injectable medium immediately before use.

The percentage of active ingredient in the compositions of the invention may be varied, it being necessary that it should constitute a proportion such that ii suitable dosage for the therapeutic effect desired shall be obtained. Obviously several unit dosage forms may bo administered at about the same time. In general, the preparations should normally contain at .least 0.025% 191 by weight of active substance when required for administration by injection; for oral administration the preparations will normally contain at least 0.1% by weight of active substance. The dose employed depends upon the desired therapeutic effect, the route of administration and the duration of the treatment.

In the human adult, the doses per person are generally between 1 - 1000yug by oral, intravaginal, intravenous or extra-amniotic administration for the induction of labour in pregnant females.

In domestic female mammals such as cows, mares, sows, ewes and bitches, the doses are generally between 0.001 and 50 mg/animal by intramuscular, subcutaneous, intrauterine, intravaginal and intravenous administration for the synchronisation of oestrus, treatment of impaired fertility and the induction of abortion and of labour.

The following Example illustrates pharmaceutical compositions according to the invention.

EXAMPLE 6 16,16-Dimethvl-trans-2.3-didehvdro-PGE^ methyl ester (2 mg) was dissolved in ethanol (10 ml), mixed with mannitol (18.5 g), sieved through a 30-mesh sieve, dried at 30°C for 90 minutes and again sieved through a 30-mesh sieve. Aerosil (microfine silica; 200 mg) was added and the powder obtained was machine-filled into one hundred No 2 hard gelatin capsules to give capsules each containing 20 pg of 16,16-dimethyl-trans-2.3didehydro-PGEj_ methyl ester which after swallowing of the capsule is released into the stomach. “Aerosil is a registered Trade Mark.

Claims

1. Prostaglandin analogues of the general formula; 5 (wherein Rg. represents the 1,1-dimethylpentyl group, the wavy line indicates attachment of the hydroxy group in beta or alpha configuration and the Cg-Cg and double bonds are trans) and the methyl ester thereof, and cyclodextrin clathrates of such an 10 acid or ester, and non-toxic salts of such an acid.

2. Prostaglandin compounds according to claim 1 in which the hydroxy group attached to the 15-position carbon atom is in alpha configuration.

3. 16,16-Dimethyl-trans-2,3-didehvdro-PGE^ 15 and non-toxic salts thereof.

4. 16,16-Dimethyl-trans-2,3-didehvdro-PGE methyl ester.

5. Cyclodextrin clathrates of a prostaglandin analogue or methyl ester thereof claimed in claim 3 or 4. - 72 Αΰ-191

6. Process for the preparation of a prostaglandin analogue of the general formula depicted in claim 1 or methyl ester thereof, which comprises reacting a cyclopentane derivative of the general formula:- (wherein R^ represents a 2-tetrahydropyranyl group unsubstituted or substituted by at least one alkyl radical, or a 1-ethoxyethyl group, is as defined in claim 1, the wavy line zvsa. indicates attachment of the io or 4 group to the carbon atom in alpha or beta configuration, and the depicted double bond is trans) with a dialkyl phosphonate of the general formula:(R c O),PCH,COOR, VIII 5 2|| 2 6 (wherein Rg represents a methyl or ethyl radical, and Rg 15 represents the methyl radical or a straight- or branchedchain alkyl radical containing from 2 to 12 carbon atoms), optionally hydrolysing when Rg is the methyl radical, or hydrolysing when Rg is an alkyl radical containing from 2 to 12 carbon atoms, the resulting prostaglandin ester 20 of the general formula :- 73 z s 3 13 I OH (wherein Rg, R A , Rg and/o^/s have the meanings hereinbefore specified and the depicted double bonds are trans) to the corresponding acid of the general formula:OH (wherein Rg, andhave the meanings hereinbefore specified, and the depicted double bonds are trans), converting by methods known per se, the 9a-hydroxy group in the compound of general formula IX (wherein Rg represents the methyl radical) or X to an oxo group, and hydrolyzing .the OR^ groups in the resulting prostaglandin compound of the general formula:- >43192 (wherein R represents a hydrogen atom or the methyl radical» and Rg, R^ and have the meanings hereinbefore specified, and the depicted double bonds are trans) to hydroxy groups to obtain a PGE compound of the 5 general formula depicted in claim i or methyl ester thereof.

7. Process for the preparation of a prostaglandin analogue of the general formula depicted in claim 1 or methyl ester thereof, which comprises 10 reacting a compound of the general formula :OH ι (wherein the various symbols and/W\are as defined in claim 6 and the depicted double bond is trans) with a compound of the general formula:- 75 /S49i ,/ *10 NLi XVII (wherein Rg and R^O' which may be the same or different, each represents a straight- or branched-chain alkyl group containing from 1 to 6 carbon atoms or a cycloalkyl group containing from 3 to 6 carbon atoms) to obtain a lithium esterenolate of the general formula:OLi I t (wherein the various symbols and /M44 are as defined in claim 6 and the depicted double bond is trans), reacting 10 the lithium esterenolate with benzeneselenenyl bromide or diphenyl diselenide or a dialkyl or diphenyl disulphide of the formula Rp2 SSR ll' wherein the symbols R 11 both represent alkyl groups containing from 1 to 4 carbon atoms or phenyl radicals, hydrolysing the resulting intermediate to convert 15 the —OLi group attached to the cyclopentane ring to an α-hydroxy group and to obtain a compound of the general formula:- 76 Xr · OH (wherein R 3 , R^, R g and are as defined in claim 6, Q represents -Se0, in which 0 represents the phenyl radical, or a group -SR·^, in vSiich R·^ is as hereinbefore defined, and the depicted double bond is trans), treating the resulting compound with hydrogen peroxide or sodium periodate, and decomposing the resulting compound of the general formula:OH (wherein the various symbols and A'i'm are as defined in claim 6, and the depicted double bond is trans) to convert COOR the grouping ,'\/\/\/ 6 attached to the 8-position Q=O of the cyclopentane ring to a trans- Δ - grouping xCOORg \/ (wherein R g is as defined in claim 6 ,5491 and the depicted double bond is trans) to obtain a compound of general formula IX specified in claim 6, and treating the compound of formula IX as specified in claim 6 to obtain a PGE compound of the general formula depicted in claim 1 or 5 methyl ester thereof.

8. Process for the preparation of a prostaglandin analogue of the general formula depicted in claim 1 or methyl ester thereof, which comprises reacting a compound of the general formula:- (wherein represents a straight- or branched-chain alkyl group containing from 1 to 4 carbon atoms, R·^ represents an alkanoyl group containing from 2 to 5 carbon atoms, is as defined in claim 6, and the 15 depicted double bond is trans) with the sodio derivative of a dialkyl phosphonate of the general formula:(R 7 0) o PCH„CR, XIII ' 2 li 2 II 3 0 0 (wherein R? represents an alkyl group containing from 1 to 4 carbon atoms, and R^ is as defined in claim 1) 20 to obtain a compound of the general formula:78 «5191 (wherein Rg, R^, R 12 and R l3 have the meanings hereinbefore specified, and the depicted carbon-carbon double bonds are trans), reducing the 15-oxo group in the resulting conipound 5 to a hydroxy group by methods known per se to obtain a compound of the general formula:- (wherein the various symbols are as hereinbefore specified, the wavy line Mt indicates attachment of the hydroxy group 10 to the carbon atom in alpha or beta configuration, and the depicted double bonds are trans), reacting the obtained compound with dihydropyran, unsubstituted or substituted with at least one alkyl radical, or ethyl vinyl ether, to obtain a compound of the general formula:79 4S-391 (wherein the various symbols and A/W\ are as hereinbefore specified, and the depicted double bonds are trans), hydrolysing under alkaline conditions the resulting compound to obtain a compound of the general formula:- (wherein R represents a hydrogen atom or the methyl radical, the other symbols and avi’' have the meanings hereinbefore specified, and the depicted double bonds are trans), converting by methods known per se the 9a-hydroxy group in the compound of general formula XXVII to an oxo .group, and hydrolysing the groups in the resulting coinpound of the general formula:80 10 (wherein R, Rg, R^ and 4Λ0 have the meanings hereinbefore specified, and the depicted double bonds are trans) to hydroxy groups to obtain a PGE compound of the general formula depicted in claim 1 or methyl ester thereof.

9. Process according to claim 8 in which the hydrolysis of a compound of general formula XXVI under alkaline conditions is effected with an aqueous solution of an alkali metal hydroxide or carbonate in the presence of a water miscible organic solvent or with anhydrous potassium carbonate in anhydrous methanol.

10. Process according to claim 9 in which the alkali metal hydroxide or carbonate is sodium or potassium hydroxide or carbonate.

11. Process according to claim 9 or 10 in which the water miscible organic solvent is tetrahydrofuran or an alkanol containing from 1 to 4 carbon atoms.

12. Process according to claim 8 in which the alkaline hydrolysis of a compound of general formula XXVI is effected with potassium carbonate in absolute methanol. 81 i ' t

13. Process according to any one of claims 6 to 12 followed by the step of converting by methods known per se a prostaglandin analogue of the general formula depicted in claim 1 into the methyl ester or into a non-toxic salt.

14. Process according to any one of claims 6 to 13 followed by the step of converting by methods known per se a prostaglandin analogue of the general formula depicted in claim 1, or methyl ester thereof, into a cyclodextrin clathrate.

15. Process for the preparation of prostaglandin analogues of the general formula depicted in claim 1 or methyl ester or non-toxic salts thereof substantially as hereinbefore described with especial reference to Example 1 or 2.

16. Process for the preparation of prostaglandin analogues of the general formula depicted in claim 1 or methyl ester or non-toxic salts thereof substantially as hereinbefore described with especial reference to Example 3 or 4.

17. Process for the preparation of prostaglandin analogues of the general formula depicted in claim 1 or methyl ester or non-toxic salts thereof substantially as hereinbefore described with especial reference to Example 5. - 82 43 491

18. Prostaglandin analogues of; the general formula depicted in claim 1 and the methyl ester and non-toxic salts thereof, and cyelodextrin clathrates of said prostaglandin analogues and ester thereof, when 5 prepared by the process claimed in any one of claims 6 to 17.

19. Pharmaceutical compositions which comprise, as active ingredient, at least one prostaglandin analogue as claimed in any one of claims 1 to 4 or methyl ester 1θ thereof, or a cyelodextrin clathrate of such a prostaglandin analogue or methyl ester thereof, or a non-toxic salt of such a prostaglandin analogue, in association with a pharmaceutical carrier.

20. Pharmaceutical compositions according to 15 claim 19 in which the active ingredient is 16,16-dimethyltrans-2,3-didehvdro-PGEmethyl ester.

21. Pharmaceutical compositions according to claim 19 substantially as hereinbefore described.

22. Pharmaceutical compositions according to 20 claim 19 substantially as hereinbefore described in Example 6.