7-THIAPROSTAGLANDIN E 1?'S AND PROCESS FOR THEIR PREPARATION

Abstract: 7-thiaprostaglandin E₁'s represented by formula (I): (wherein R¹ represents H, C₁ to C₁₀ alkyl, C₂ to C₂₀ alkenyl, substituted or unsubstituted phenyl, substituted or unsubsti­ tuted C₃ to C₁₀ cycloalkyl, substituted or unsubstituted phenyl (C₁ to C₂) alkyl, or mono-equivalent cation, R² and R³, which may be the same or different, each represents H, tri (C₁ to C₇)-hydrocarbylsilyl or a group forming an acetal bond with the oxygen atom of the hydroxy group, R⁴ represents H, methyl or vinyl, R⁵ represents straight or branched C₃ to C₈ alkyl, straight or branched C₃ to C₈ alkenyl, straight or branched C₃ to C₈ alkynyl, optionally substituted phenyl, optionally substituted phenoxy, optionally substituted C₃ to C₁₀ cycloalkyl, or straight or branched C₁ to C₅ alkyl substituted by C₁ to C₆ alkoxy, optionally substituted phenyl, optionally substituted phenoxy or optionally substituted C₃ to C₁₀ cycloakyl, X represents ethylene, vinylene or ethyny­ lene, n represents 0 or 1, represents ethylene or vinylene, provided that, when n represents 0 or X represents ethylene, R5 does not represent straight or branched C₃ to C₈ alkyl, nor optionally substituted C₃ to C₁₀ cycloalkyl), enantiomers thereof, and mixtures thereof in arbitrary ratios are useful for treating and/or preventing diseases or digestive organs such as duodenum or stomach.

Description: DESCRIPTION TITLE OF THE INVENTION 7-thiapro.taglandin. E1 and Process for Producing Same TECHNICAL FIELD The present invention relates to novel 7-thiaprostaglandins E1 and a process for producing the same. More specifically, the present invention relates to novel 7-thiaprostaglandians E1 useful as medicines and a process for producing said 7-thiaprostaglandins E1 which comprises reacting an organolithium compound with a copper compound, then reacting the resultant reaction product with 2-organothio-2-cyclopentenones, and optionally subjecting the resultant product to deprotection, hydrolysis, salt-formation and/or reduction reaction. BACKGROUND OF THE ART Natural prostaglandins are known as local hormones having a biologically and pharmacologically high activity and therefore a large number of studies on their derivatives have been made. Among natural prostaglandins, prostanglandin E1 has strong blood platelet aggregation inhibition effect and vasodilatation effect, etc. and begins to be used for clinical applications. The greatest defect of natural prostaglandins, especially prostaglandins E1 , is that they can not be orally administered because they are rapidly metabolized when orally administered and therefore they must be usually administered by an intravenous injection. Conventionally, synthetic prostaglandins prepared by replacing one or two carbon atoms forming the skeleton of natural prostaglandins with a sulfur atom have been variously studied. For example, there are known l-thiaprostaglandin E2 or F2a wherein the carbon atom at the l-position of natural prostaglandins is replaced with a sulfur atom (J. Org. Chem., 40, 521, (1975)), 3-thia-il-deoxy- prostaglandin E1 (Tetrahedron Letters, 1975, 765; and J. Med. Chem., 20, 1662 (1977)), 7-thiaprostaglandins Fla (J. Amer. Chem. Soc., 96, 6757 (1974)), 9S-prostaglandins E1 (Tetrahedron Letters, 1974, 4267 and 4459; Tetrahedron Letters, 1976, 4793; and Heterocycles, 6, 1097 (1977)), ll-thiaprostaglandins E1 or Fla (Tetrahedron Letters, 1975, 1165), 13-thiaprostaglandins E or F (U.S. Patent No. 4,080, 458 (1978)), and 15-thiaprostaglandins E2 (Tetrahedron Letters, 1977, 1629). Moreover, there are known ll-deoxy-7-thiaprostaglandins E1 (U.S. Patent No. 4,180,672), natural type 7-thiaprostaglandins E1 containing a hydroxyl group at the 15-position (U.S. Patent No. 4,466,980) or nonnatural type 15-deoxy-16-hydroxy-3-thiaprostaglandins E1 containing a hydroxyl group at the 16-position (Japanese Unexamined Patent Publication No. 54-22342). DISCLOSURE OF THE INVENTION An object of the present invention is to provide novel non-natural type 15-deoxy-16-hydroxy-7-thiaprostaglandins E1 containing a hydroxyl group at the 16-position. Another object of the present invention is to provide novel natural type 7-thiaprostaglandins E1 containing an unsaturated bond at the 4-position or a specific substituent such as an alkenyl group or an alkynyl group at the 15-position. A further object of the present invention is to provide novel 7-thiaprostaglandins E1 which are especially useful for the treatment or prevention of digestive organ diseases such as a duodenal ulcer and a gastric ulcer. A still another object of the present invention is to provide novel 7-thiaprostaglandins E1 which can be orally administered. A further object of the present invention is to provide a process for producing novel 7-thiaprostaglandins E1 which is excellent for industrial purposes. Other objects and advantacasg of the present invention will bo apparent from the following doscrlption. The above-mentioned objects and advantages of the present invention are attained by the following 7-thiaprostaglandins E1. That is, the present invention is 7-thiaprostaglandins E1 which are compounds represented by the following formula [I] or their enantiomers or mixtures thereof in any ratio: EMI3.1 wherein R1 represents a hydrogen atom, a C1-C10 alkyl group, a C2-C20 alkenyl group, a substituted or unsubstituted phenyl group, a substituted or unsubstituted C3-C10 cycloalkyl group, a substituted or unsubstituted phenyl (C-C2) alkyl group, or one equivalent cation; R and R3, which may be the same or different, represent a hydrogen atom, a tri (C1-C7) hydrocarbon silyl group, or a group forming an acetal linkage together with an oxygen atom of a hydroxyl group; 4 R represents a hydrogen atom, a methyl group, or a vinyl group; R5 represents a linear or branched C3-C8 alkyl group, a linear or branched C3-C8 alkenyl group, a linear or branched C3-C8 alkynyl group, a phenyl group which may be substituted, a phenoxy group which may be substituted, a C3 -C10 cycloalkyl group which may be substituted, or a linear or branched C1-C5 alkyl group which is substituted with a C1-C 6 alkoxy group, a phenyl group which may be substituted, a phenoxy group which may be substituted, or a C3-C10 cycloalkyl group which may be substituted; X represents an ethylene group, a vinylene group or an ethynylene group; n represents 0 or 1, the expression /' represents an ethylene group or a vinylene group; provided that when n is 0 and X is an ethylene group, R5 is not a linear or branched C3-C8 alkyl group or a C3-C10 cycloalkyl group which may be substituted. BEST MODE OF CARRYING OUT THE INVENTION In the formula [I], RÚ represents a hydrogen atom, a C1-C10 alkyl group, a C2-C20 alkenyl group, a substituted or unsubstituted phenyl group, a substituted or unsubstituted C3-C10 cycloalkyl group, a substituted or unsubstituted phenyl (C1-C2) alkyl group, or one equivalent cation. The C1-C10 alkyl groups may be linear on branched and may include, for example, methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl. The C2-C20 alkenyl groups may include, for example, allyl, isoprenyl, geranyl, citronellyl, and retinyl. The substituent of the substituted or unsubstituted phenyl is preferably, for example, a halogen atom, a hydroxy group, a C2-C7 acyloxy group, a C1-C4 alkyl group which may be substituted with a halogen atom, a C1-C4 alkoxy group which may be substituted with a halogen atom, a nitrile group, a carboxyl group or a (C1-C6) alkoxycarbonyl group. The halogen atom is, for example, fluorine, chlorine or bromine and particularly preferably fluorine or chlorine. The C2-C7 acyloxy group may include, for example, acetoxy, propionyloxy, n-butyryloxy, iso-butyryloxy, n-valeryloxy iso-valeryloxy, caproyloxy, enanthyloxy or benzoyloxy. The C1-C4 alkyl groups which may be substituted with a halogen atom may preferably include, for example, methyl, ethyl, n-propyl, iso-propyl, n-butyl, chloromethyl, dichloromethyl, and trifluoromethyl. The C1-C4 alkoxy groups which may be substituted with a halogen atom may preferably include, for example, methoxy, ethoxy, n-propoxy, iso-propoxy, n-butoxy, chloromethoxy, dichloromethoxy and trifluoromethoxy. The (C1-C) alkoxycarbonyl groups may include, for example, methoxycarbonyl, ethoxycarbonyl, butoxycarbonyl and hexyloxycarbonyl. The substituted phenyl group may have 1 to 3, preferably one, substituents as mentioned above. The substituted or unsubstituted C3-C10 cycloalkyl groups may be substituted with a similar substituent as mentioned above or may be an unsubstituted cycloalkyl group, such as cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, and cyclodecyl. The substituted or unsubstituted phenyl (C1-C2) alkyl groups may be substituted with a similar substituent as mentioned above or may include, for example, unsubstituted benzyl, a-phenethyl and ss-phenethyl. The equivalent cations may include, for example, ammonium cations such as tetramethylammonium, monomethylammonium, dimethylammonium, trimethylammonium, benzylammonium, phenethylammonium, morpholinium cation, monoethanolammonium and piperidinium cation; alkali metal cations such as Na and K and divalent or trivalent metal cations such as 1/2 Ca , 1/2 Mg 2+ 3+ 1/2 Zn and 1/3 Al R1 is preferably a hydrogen atom, a C1-C10 alkyl group, a C2-C20 alkenyl group or one equivalent cation. In the formula [I], Rê and R may be the same or different and represent a hydrogen atom, a tri(Cl-C7) hydrocarbon silyl group or a group forming an acetal linkage together with an oxygen atom of a hydroxyl group. The tri (C1-C7) hydrocarbon silyl group may preferably include, for example, a tri (C1-C4) alkylsilyl such as trimethylsilyl, triethylsilyl, and t-butyl dimethylsilyl; a diphenyl (C1-C4) alkylsilyl such as t-butyldiphenylsilyl or tribenzylsilyl. The group forming an acetal linkage together with an oxygen atom of a hydroxyl group may include, for example, methoxyethyl, l-ethoxyethyl, 2-methoxy-2-propyl, 2-ethoxy-2-propyl, (2-methoxyethoxy) methyl, benzyloxymethyl, 2-tetrahydropyranyl, 2-tetrahydrofuranyl or 6,6-dimethyl-3-oxa-2-oxobicyclo [3.1.0] hexa-4-yl. Of these, 2-tetrahydropyranyl, 2-tetrahydrofuranyl, l-ethoxyethyl, 2-methoxy-2-propyl, 2-ethoxy-2-propyl, (2-methoxyethoxy) methyl or 6,6-dimethyl-3-oxa-2oxobicyclo [3.1.0] hexa-4-yl is especially preferable. R2 or R3 As , on R3, among the above-mentioned groups, a hydrogen atom, a tri (C1-C4) alkylsilyl group, a diphenyl (C1-C4) alkylsilyl group, a 2-tetrahydropyranyl group, a 2-tetrahydrofuranyl group, an l-ethoxyethyl group, a 2-methoxy-2-propyl group, a 2-ethoxy-2-propyl group, a (2-methoxyethoxy) methyl group or a 6,6dimethyl-3-oxa-2-oxobicyclo [3.1.0] hexa-4-yl group is preferable. 4 In the formula [I], R represents a hydrogen atom, a methyl group or a vinyl group. In the formula [I], R5 represents a linear or branched C3-C8 alkyl group, a linear or branched C3-C8 alkenyl group, a linear or branched C3-C8 a lkynyl group, a phenyl group which may be substituted, a phenoxy group which may be substituted, a C3-C10 cycloalkyl group which may be substituted, or a linear or branched C1-C5 alkyl group which may be substituted with a C1-C6 alkoxy group, a phenyl group which may be substituted, a phenoxy group which may be substituted or a C3-C10 cycloalkyl group which may be substituted. The linear or branched C3-C8 alkyl groups may include, for example, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, l-methyl-l-butyl, 2-methylhexyl, 2-methyl-2-hexyl, 2-hexyl, l,l-dimethylpentyl, preferably butyl, pentyl, hexyl, (2R)- or (2S)-2-methylhexyl, 2-hexyl, l-methyl-l-butyl, 2-methyl-l-butyl, more preferably butyl. A hydrogen atom to be attached to such alkyl groups may be deuterium and tritium. The linear or branched C3-C8 alkenyl groups may include, for example, l-butenyl, 2-butenyl, l-pentenyl, and 2-methyl-4-hexenyl. A hydrogen atom to be attached to such alkenyl groups may be deuterium and tritium. The linear or branched C C8 alkynyl groups may include, for example, 1-butynyl, 2-butynyl, l-pentynyl, and 2-methyl-4-hexynyl. The substituent of a phenyl group which may be substituted and a phenoxy group which may be substituted may be a similar substituent as mentioned for the substituent of a substituted phenyl group of R the substituent of a C3-C7 cycloalkyl group may be a similar substituent as mentioned for the substituent of a substituted phenyl group of R1. The unsubstituted C3-C7 cycloalkyl group may include, for example, cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl and cyclodecyl. The C1-C6 alkoxy groups in the linear or branched C1-C5 alkyl group which may be substituted with a C1-C6 alkoxy group, a phenyl group which may be substituted, a phenoxy group which may be substituted or a C3-C10 cycloalkyl group which may be substituted may include, for example, methoxy, ethoxy, propoxy, isopropoxy, butoxy, t-butoxy, and hexyloxy. The phenyl group which may be substituted and the phenoxy group which may be substituted may preferably include those mentioned above. The C3-C10 cycloalkyl groups which may be substituted may preferably include those mentioned above. The linear or branched C1-C5 alkyl goups may, include, for example, methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, t-butyl and pentyl. The substituent may be attached to the alkyl group at any position. As R5, butyl, pentyl, l-methyl-l-butyl, 2-methyl-lbutyl, cyclopentyl, cyclohexyl and phenyl are preferable. In the formula [I], X represents an ethylene group, a vinylene group or an ethynylene group. The vinylene group may be a cis-vinylene group, a trans-vinylene group or mixtures thereof in any ratio. A hydrogen atom to be attached to such an ethylene group or a vinylene group may be deutrium and tritium. The expression // represents an ethylene group or a vinylene group. The vinylene group may be a cis-vinylene group, a trans-vinylene group or mixtures thereof in any ratio. In the formula [I], n represents 0 or 1. In the formula [I], when n is 0 and X represents an ethylene group, R5 is not a linear or branched C3-C8 alkyl group or a C3-C10 cycloalkyl group which may be substituted. The 7-thiaprostaglandins E1 of the present invention are classified into the following two classes on the basis of the above-mentioned definition of n, X and R5. (i) 7-thiaprostaglandins E1 in the case of n = 1 In the case of n=l, the 7-thiaprostaglandins E1 of the present invention are represented by the following formula [I-l] : EMI8.1 wherein R1, R2, R3, R41 5, X and the expression / are the same as defined above. In the case, the 7-thiaprostaglandins w1 are 15-deoxy16-hydroxy-7-thiaprostaglandins E1. (ii) 7-thiaprostaglandins E1 in the case of n P 0 In the case of n - 0, the 7-thiaprostaglandins E1 of the present invention are represented by the following formula [I-2]: EMI9.1 wherein R1 R2 R3 R4 R5, X and the expression // are the same as defined above, provided that when X is an ethylene group, R5 is not a linear or branched C3-C8 alkyl group or a C -C branched group which may a substituted. 3 10 cycloalkyl group which may be substituted. In this case, the 7-thiaprostaglandins E1 contain an unsaturated bond at the 4-position or a substituent such as an alkynyl group or an alkenyl group at the 15-position. In the compound of the formula [I], the configuration of a substituent attached on the-cyclopentanone ring is the same as has natural prostaglandin E1. Therefore, such a stereoisomer is especially useful. The present invention includes stereoisomers which are the enantiomer of the above-mentioned stereoisomer and have the following formula [I) ent, or mixtures thereof in any ratio EMI9.2 wherein R1, R2 R3, R4, R5, n, X and the expression / are the same as defined above. Since the carbon atom to which OR3, R4 and R5 are attached by substitution is an asymmetric carbon atom, two types of optical isomers exist. The present invention includes any of these optical isomers or mixtures thereof in any ratio. Preferable examples of the novel 7-thiaprostaglandins E1 of the formula [I] which are provided by the present invention may include the following compounds. (01) l5-deoxy-l6-hydroxy-7-thiaprostaglandin E (02) 15-deoxy-16-hydroxy-18-oxa-7-thiaprosta- glandin E1 (03) 18,19, 20-trinor-l5-deoxy-l6-hydroxy-l7- phenoxy-7-thiaprostaglandin E1 (04) 15-deoxy-16-hydroxy-20-methyl-7-thiaprosta glandin E1 (05) 15-deoxy-l6-hydroxy-l7, 20-dimethyl-7-thia- prostaglandin E1 (06) 17,18,19,20-tetranor-15-deoxy-16-hydroxy-16- cyclopentyl-7-thiaprostaglandin E1 (07) 17,18,19,20-tetranor-15-deoxy-16-hydroxy-16- cyclohexyl-7-thiaprostaglandin E1 (08) 15-deoxy-16-hydroxy-16-methyl-7-thiaprosta- glandin E1 (09) 15 -deoxy-16-hydroxy-l 6-methyl-18-oxa-7- thiaprostagiandin E1 (10) 18,19,20-trinor-15-deoxy-16-hydroxy-17- phenoxy-16-methyl-7-thiaprostaglandin E1 (11) l5-deoxy-16-hydroxy-l6, 20-dimethyl-7- thiaprostaglandin E1 (12) 15-deoxy-16-hydroxy-16,17,20-trimethyl-7- thiaprostaglandin E1 (13) 17,18,19,20-tetranor-15-deoxy-16-hydroxy-16- cyclopentyl-16-methyl-7-thiaprostaglandin E1 (14) 17,18,19,20-tetranor-15-deoxy-16-hydroxy-16- cyclohexyl-16-methyl-7-thiaprostaglandin E1 (15) 15-deoxy-16-hydroxy-16-vinyl-7-thiaprosta glandin E1 (16) 15-deoxy-16-hydroxy-16-vinyl-18-oxa-7 thiaprostaglandin E1 (17) 18,19,20-trinor-15-deoxy-16-hydroxy-17 phenoxy-16-vinyl-7-thiaprostaglandin E1 (18) 15-deoxy-16-hydroxy-20-methyl-16-vinyl-7 thiaprostaglandin E1 (19) 15-deoxy-16-hydroxy-17,20-dimethyl-16-vinyl 7-thiaprostaglandin E1 (20) 17,18,19,20-tetranor-15-deoxy-16-hydroxy-16- cyclopentyl-16-vinyl-7-thiaprostaglandin E1 (21) 17,18,19,20-tetranor-15-deoxy-16-hydroxy-16- cyclohexyl-16-vinyl-7-thiaprostaglandin E1 (22) 15-deoxy-2,3-dehydro-16-hydroxy-7-thia prostaglanding E1 (23) 15-deoxy-2,3-dehydro-16-hydroxy-16-methyl-7- -thiaprostaglandin E1 (24) 15-deoxy-2, 3-dehydro-16-hydroxy-16-vinyl-7- thiaprostaglandin E1 (25) 4,4,5,5-dehydro-7-thiaprostaglandin E1 (26) 4,4,5,5-dehydro-17-methyl-7-thiaprosta- glandin E1 (27) 4,4,5,5-dehydro-17,20-dimethyl-7-thia prostaglandin E1 (28) 4,4,5,5-dehydro-17(S),20-dimethyl-7- thiaprostaglandin E1 (29) 4,4,5,5-dehydro-17(R),20-dimethyl-7- thiaprostaglandin E1 (30) 4,4,5,5-dehydro-16,17,18,19,20-pentanor 15-cyclohexyl-7-thiaprostaglandin E1 (31) 4,4,5,5-dehydro-16,17,18,19,20-pentanor 15-cyclopentyl-7-thiaprostaglandin E (32) 4,4,5,5-dehydro-18-oxa-7-thiaprostaglandin E1 (33) 4,4,5,5-dehydro-17,18,19,20-tetranor-16 cyclohexyl-7-thiaprostaglandin E1 (34) (4E)-4,5-dehydro-7-thiaprostaglandin E1 (35) (4E)-4,5-dehyro-17(R) ,20-dimethyl-7- thiaprostaglandin E1 (36) (4Z)-4,5-dehydro-7-thiaprostaglandin E1 (37) (4Z)-4,5-dehydro-17(R),20-dimethyl-7 thiaprostaglandin E1 (38) 17,17,18,18-dehydro-7-thiaprostaglandin E1 (39) 17,17,18,18-dehydro-16-methyl-7-thia- prostaglandin E1 (40) 18,18,19,19-dehydro-17-methyl-7-thia- prostaglandin E1 (41) 18,18,19,19-dehydro-17,20-dimethyl-7- thiaprostaglandin E1 (42) 19,20-dehydro-17,20-dimethyl-7-thia prostaglandin E1 (43) 19,20-dehydro-7-thiaprostaglandin E (44) 17,18-dehydro-7-thiaprostaglandin E1 (45) The 17,18-deuterated derivative of the compound (38) (46) The 17,18-tritiated derivative of the compound (39) (47) The 18,19-tritiated derivative of the compound (41) (48) The methyl esters of the compounds (1) to (47) (49) The ethyl esters of the compounds (1) to (47) (50) The sodium salt of the compounds (1) to (47) The 7-prostaglandins E1 of the present invention which are compounds of the formula [I] or their enantiomers or mixtures thereof in any ratio are prepared by reacting an organolithium compound of the formula [II] EMI12.1 wherein R31 represents a tri(C1-C7) hydrocarbon silyl group or a group forming an acetal linkage together with an oxygen atom of a hydroxyl group, and R4, R5 and n are the same as defined above, with a copper compound of the formula [III]: : CuQ wherein Q represents a halogen atom, a cyano group, a phenylthio group or a l-pentyl group, by then reacting the resultant reaction product with 2-organothio-2-cyclopentenones of the following formula [IV] or their enantiomers or mixtures thereof in any ratio: EMI13.1 wherein R11 represents a C1-C10 alkyl group, a C2-C20 alkenyl group, a substituted or unsubstituted phenyl gruop, a substituted or unsubstituted C3-C10 cycloalkyl group, or a substituted or unsubstituted phenyl (C1-C2) alkyl group; R21 represents a tri(C1-C7) hydrocarbon silyl group or a group forming an acetal linkage together with an oxygen atom of a hydroxyl group; and X and the expression // are the same as defined above, and by optionally subjecting the resultant product to deprotection, hydrolysis, salt-formation and/or reduction reaction. R31 in the organolithium compound of the formula [II] is defined as R3 from which a hydrogen atom is removed. Such an organolithium compound can be prepared by a method known per se (J. Am. Chem. Soc., 94, 7210 (1972); U.S. Patent No. 4,180,672; U.S. Patent No. 4,466,930; and Japanese Unexamined Patent Publi No. 4,466,9307 and Japanese Unexamined Patent Publication (Kokai) No. 53-108929) O in the copper compound of the formula [ represents a halogen atom such as chlorine, fluorine, and bromine, a cyano group, a phenylthio group or a l-pentyl group. Such a copper compound is a known compound. R21 in the 2-organothio-2-cyclopentenones of the formula [TV] is defined R2 from which a hydrogen atom is removed. R11 is defined as R1 from which a hydrogen atom and one equivalent cation are removed. 2-organothio-2-cyclopentenones of the formula [IV] in which the expression /, is an ethylene group can be prepared by the following synthetic route: EMI14.1 With regard to these synthetic processes, reference will be made to U.S. Patent No. 4,180,672; U.S. Patent No. 4,466,980, etc. 2-Organothio-2-cyclopentenones of the formula [1V3 in which the expression / is a vinylene group can be prepared by the following synthetic route: EMI15.1 With regard to these synthetic processes, reference will be made to U.S. Patent No. 4,466,980. In the present invention, the organolithium compound of the formula [II] is first reacted with the copper compound of the formula [III]. The reaction is carried out in the presence of an organic medium. An inert non-protonic organic medium which is liquid under the reaction temperature and does not react with the reaction reagents is preferably used. Such inert non-protonic organic media may include, for example, saturated hydrocarbons such as pentane, hexane, heptane, and cyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene; ether solvents such as diethyl ether, tetrahydrofuran, dioxane, dimethoxyethane, and diethylene glycol dimethyl ether; and other non-protonic polar solvents such as hexamethylphosphorictriamide (HMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAA), dimethyl sulfoxide, sulforan, and N-methylpyrrolidone. These solvents may be used in the form of a mixture of two or more thereof. The copper compound of the formula [III] is usually used in an amount of 0.8 to 2.0 times by mole, preferably 1 to 1.2 times by mole, based on the organolithium compound of the formula [II]. The reaction temperature is in the range of from -1000C to OOC, more preferably from approximately 78 CC to -200C. The reaction time is variable depending on the reaction temperature. Usually, an about one hour reaction time at a temperature of -780C to -400C is sufficient. The reaction is preferably carried out in an atmosphere of nitrogen or argon gas. The thus-obtained reaction product is estimated to have the partial structure represented by the following formula: EMI16.1 (Tetrahedron Lett., 21, 1247 (1980)). Then, the above-mentioned reaction product is reacted with the 2-organothio-2-cyclopentenones of the formula [ IV] . This reaction is preferably carried out by adding the organothio-2-cyclopentenones to the same reaction system without isolating the reaction product after the reaction of the organolithium compound of the formula [II] and the copper compound of the formula [III]. The 2-organothio-2-cyclopentenones are usually used in an amount of 0.5 to 1.5 times by mole, preferably 0.7 to 1.2 times by mole, based on the organolithium compound of the formula [IT] The reaction temperature is in the range of from -1200C to OOC, preferably from -9O0C to -300C. Although the reaction time is variable depending upon the reaction temperature, it is usually 10 minutes to 2 hours. The reaction is carried out in an atmosphere of nitrogen or argon gas. In the practice of the reaction, when a trivalent phosphorus compound, e.g., trialkylphosphines (e.g., triethylphosphine, tributylphosphine), trialkyl phosphites (e.g., trimethyl phosphite, triethyl phosphite, triisopropyl phosphite, tri-n-butyl phosphite), hexamethylphosphorustriamide or triphenylphosphine is used, the reaction smoothly proceeds. Especially tributylphosphine and hexamethylphosphorustriamide are preferably used. Such trivalent organic phosphorus compounds may be added during the reaction of the organolithium compound of the formula [Il] and the copper compound of the formula [III] Thus, there are obtained compounds of the formula [I] in which the hydroxyl group is protected and the carboxylic acid at the l-position is in the form of an ester. Since the production process of the present invention uses a reaction which proceeds stereospecifically, from the starting material having the configuration represented by the formula [IV], a compound having the configuration represented by the formula [I], is obtained, and from the enantiomer of the formula [IV], an enantiomer of the formula [I] represented by the formula [I]ent is obtained. At the completion of the reaction, the resultant product is separated from the reaction mixture and purified in a conventional manner. For example, extraction, washing, chromatography or combinations thereof may be used. Moreover, the compounds as obtained herein wherein the hydroxyl group is protected and the carboxylic acid at the l-position is in the form of an ester is then optionally subjected to deprotection, hydrolysis or salt-formation reaction. Alternatively, the compounds may be subjected to a reduction reaction in which X in the formula [I] which is an ethynylene group or a vinylene group is reduced, or to a reduction reaction in which R5 in the formula [I] which is a linear or branched C3-C8 alkenyl group, or a linear or branched C3-C8 alkynyl group is reduced. The removal of the protective group (R21 and R31) of a hydroxyl group, when the protective group is a group forming an acetal linkage together with an oxygen atom of a hydroxyl group, is conveniently carried out in a reaction solvent such as water, tetrahydrofuran, ethyl ether, dioxane, acetone, and acetonitrile, in the presence of a catalyst such as acetic acid, the pyridinium p-toluensulfonate or a cation exchange resin. The reaction is usually carried out at a temprature ranging from -780C to +500C for approximately 10 minutes to 3 days. In the case where the protective group is a tri (C1-C7) hydrocarbon silyl group, the reaction is carried out in the above-mentioned reaction solvents in the presence of a catalyst such as acetic acid, tetrabutylammonium fluoride, cesium fluoride, hydrofluoric acid and hydrogen fluoride-pyridine at the same temperature for the same period. The removal of the protective group (R ) of a carboxy group, i.e., hydrolysis reaction, is carried out in water or a solvent containing water in the presence of an enzyme such as lipase and esterase at a temperature ranging from -100C to +600C for approximately 10 minutes to 24 hours. In accordance with the present invention, the compound containing a carboxyl group produced by the hydrolysis reaction is then optionally subjected to a salt-forming reaction to give the corresponding carboxylic acid salt. The salt-forming reaction is known per se, and is carried out by a neutralization reaction with an inorganic compound, such as potassium hydroxide, sodium hydroxide, and sodium carbonate, or an organic basic compound, such as ammonia, trimethylamine, monoethanolamine, and morpholine, in an amount substantially equal to that of the carboxylic acid according to a conventional method. In the case where an ethynylene group of X in the formula [I] is reduced to an ethylene group or a vinylene group or X is reduced to an ethylene group, and in the 5 case where a C3-C8 alkynyl group of R5 in the formula [I] is reduced to a C3-C8 alkyl group or a C3-C8 alkenyl S group of R is reduced to a C3-C8 alkyl group, it is preferable to adopt a catalytic reduction method using a hydrogenation catalyst such as a palladium type catalyst, a platinum catalyst, a rhodium catalyst and a ruthenium type catalyst. The palladium type catalysts include palladiumactivated carbon, palladium-calcium carbonate and palladium-barium sulfate. Of these, palladium-activated carbon is preferable. As the platinum catalyst, there may be used platinum oxides and platinum black. The rhodium catalyst include chlorotris (triphenylphosphine) rhodium (I). There is given one example of the reaction conditions hereunder. When palladium-activated carbon is used as a hydrogenation catalyst, ethyl acetate, ethanol or methanol is used as the reaction solvent. A several hours to several days reaction time is usually satisfactory at room temperature under atmospheric pressure. The present invention has the noticeable feature that when the catalytic reduction is effected in deuterium or tritium, the 7-thiaprostaglandins E1 of the formula [I] labelled with deuterium or tritium are obtained. Such deuterium- or tritium-labelled compounds are useful for the determination of the corresponding 7-thiaprostaglandins E1 useful as a medicine or for the study on the in vivo behaviour of these compounds. The process of the present invention is also useful from this point. In the case where an ethynylene group of X in the formula [I] is reduced to a vinylene group, or a C3-C8 alkyl group of X is reduced to a C3-C8 alkenyl group, a lindlar catalyst or a palladium-barium sulfate poisoned with quinoline is preferably used. In the novel 7-thiaprostaglandins E1 represented by the formula [I] which are prepared by the abovementioned process, the 7-thiaprostaglandins E1 which are compounds of the formula [I'] in which R2 and R3 are hydrogen atoms and their enantiomers or mixtures thereof in any ratio: EMI20.1 wherein R1, R4, R5, X, n and the expression / are the same as defined above, have interesting physiological activities and can be used for the prevention and/or treatment of various diseases such as digestive organ diseases, e.g., a duodenal ulcer and a gastric ulcer, liver diseases, e.g., hepatitis, toxipathic hepatitis, fatty liver, hepatic coma, hypertrophy of the liver, and hepatocirrhosis, pancreas, e.g., pancreatitis, arinary diseases, e.g., diabetes kidney diseases, acute kidney insufficiency, cystitis, and urethritis; respiratory diseases, e.g., pneumatic and bronchitis; incretion diseases; immunity diseases, toxicoses, e.g., alcohol poisoning and carbon tetrachloride poisoning and low blood pressure. The 7-thiaprostaglandins E1 of the present invention are especially useful for the treatment and prevention of digestive organ diseases such as a duodenal ulcer and a gastric ulcer. The present invention will be explained in more detail by the following examples which by no means limit the present invention. Example 1 Synthesis of (16RS)-15-deoxy-ll-t-butyldimethyl silyl-16-t-butyldimethylsilyloxy-7-thiaprosta- glandin E1 methyl ester dl- (E) -4-t-butyldimethylsilyloxy-l-iodo-l-octene (1.77 g, 4.8 mmol) was dissolved in ether (10 ml) and cooled to -780C. Thereafter, t-butyllithium (2.0 M, 4.8 ml, 9.6 mmol) was added to the solution and the mixture was stirred at a temperature of -78 c for 2 hours. Phenylthiocopper (I) (828 mg, 4.8 mmol) and a solution of dexamethylphosphortriamide (1.56 g, 9.6 mmol) in ether (4 ml) were added to the reaction mixture and the resultant mixture was stirred at a temperature of -780C for 1 hour. Then, a solution of (4R) -4-t-butyldimethylsilyloxy-2- (5-methoxycarbonyl- pentylthio)-2-cyclopentenone (1.49 g, 4.0 mmol) in tetrahydrofuran (70 ml) was added to the reaction mixture and the resultant mixture was stirred at a temperature of -78 C for 15 minutes and at a temperature of -400C for 45 minutes. An acetate buffer solution was added to the reaction mixture. The organic layer was extracted with hexane (150 ml x 3), and the separated organic layer was washed with an aqueous sodium chloride, dried over anhydrous magnesium sulfate, filtered and concentrated to obtain 2.44 g of a crude product. The crude product was subjected to silica gel column chromatography (hexane : ethyl acetate - 4 : 1) to obtain the desired (l6RS)-15-deoxy-ll-t-butyldimethylsilyl-16-t-butyl- dimethylsilyloxy-7-thiaprostaglandin E1 methyl ester (2.23 g, 3.63 mmol, 918). Nuclear Magnetic Resonance (CDC13 , 0.06 (12H, s), 0.87 (21H), 1.1 ¯ 1.9 (12H, m), 1.9 "'3.1 (1OH, m), 3.61 (3H, s), 3.27 ¯ 4.4 (2H, m), 5.1 N 5.7 (2H, m) Infrared Absorption Spectrum (liquid film, cm 1); 1740, 1195, 1165, 960, 830, 770 Mass Spectrometric Analysis (FD-MS); 614 (M+) Example 2 Synthesis of (16RS)-15-deoxy-7- thiaprostaglandin E1 methyl ester The (16RS)-15-deoxy-11-t-butyldimethylsilyl-16-t- butyldimethylsilyloxy-7-thiaprostaglandin E1 methyl ester (1;20.g, 1.95 mmol) was dissolved in acetonitrile (60 ml). The resultant solution was added with 47% hydrofluoric acid (1 ml) and stirred at room temperature for 1 hour. The reaction mixture was neutralized with an aqueous solution of sodium hydrogen carbonate, and extracted with ethyl acetate (200 ml x 3). The separated organic layer was washed with an aqueous sodium chloride solution, dried over anhydrous magnesium sulfate and concentrated to obtain 750 mg of a crude product. The crude product was subjected to silica gel column chromatography (hexane : ethyl acetate = 1 : 3) to obtain the desired (16RS)-15-deoxy-7-thiaprostaglandin E1 methyl ester (680 mg, 176 mmol, 90%). Nuclear Magnetic Resonance (CDC13 , 0.87 (3H, t), 1.1 N 1.7 (12H, m), 2.0 ¯ 3.1 (12H, m), 3.61 (3H, s), 3.2 X 4.5 (2H, m), 5.4 X 5.75 (2H, m) -l Infrared Absorption Spectrum (liquid film, cm 3400, 1740, 1260, 845, 730 Mass Spectrometric Analysis (FD-MS): 386 (M+) High Resolution Mass Spectrometric Analysis; Analytical value: 386, 2102 Calcined value: 386, 2124 (C20H3405S) Example 3 Synthesis of (16RS)-15-deoxy-11-t-butyl- dimethylsilyl-16-trimethylsilyloxy-16-methyl- 7-thiaprostaglandin E1 methyl ester Dry ether (5 ml) was cooled to -780C and was added with a t-butyllithium solution (1.9 M, 2.3 ml, 4.4 mmol). A solution of dl- (E) -4-trimethylsilyloxy-4-methyl-l- iodo-l-octene (749 mg, 2.2 mmol) in dry ether (5 ml), which had been cooled to -780C, was added to the aboveprepared solution while stirring at a temperature of -78 C and the resultant mixture was stirred at a temperature of -780C for 1.5 hours Hexamethylphosphortriamide (1.0 ml, 5.5 mmol) was added to phenylthiocopper (I) (380 mg, 2.2 mmol) and the mixture was stirred for 1 hour. Dry tetrahydrofuran (5 ml) was added to the mixture and the resultant mixture was cooled to -780C. This mixture was added the above-prepared reaction mixture. After the resultant mixture was stirred at a temperature of -780C for 15 minutes, a solution of (4R) -4-t-butyldimethylsilyloxy-2- (5-methoxycarbonyl- pentylthio)-2-cyclopentenone (745 mg, 2.0 mmol) in dry tetrahydrofuran (20 ml) was added thereto after cooling to -780C. The resultant mixture was stirred at a temperature of -780C for 30 minutes and at a temperature of -40 C for 1 hour. The reaction mixture was poured in an acetate buffer solution (70 ml) having a pH of 4, followed by stirring for 15 minutes. The resultant solution was added with hexane (50 ml) and filtered through Celite and the filtrate was separated. The aqueous layer was extracted two times with hexane and the extracted organic layers were combined with the organic layer. The mixture was washed once with an aqueous saturated ammonium chloride solution containing aqueous ammonia, twice with an aqueous saturated ammonium chloride solution and twice with an aqueous saturated sodium chloride solution. The washed mixture was dried over anhydrous magnesium sulfate, filtered, concentrated and subjected to silica gel column chromatography (cyclohexane : ethyl acetate = 20 : 1) to obtain (16RS)-15-deoxy-11-t-butyldimethylsilyl-16-trimethyl- silyloxy-16-methyl-7-thiaprostaglandin E1 methyl ester (904 mg, 1.54 mmol, 77%). Nuclear Magnetic Resonance (CDC13 , 0.0 N 0.2 (15H, m), 0.88 (9H, s), 0.7 ¯ 1.0 (3H, m), 1.18 (3H, s), 1.1 ¯ 2.0 (12H, m), 2.0 X 3.1 (1OH, m), 3.61 (3H, s), 3.8 X 4.2 (1H, m), 5.2 N 6.0 (2H, m) Infrared Absorption Spectrum (liquid film, cm 1); 1743, 1248, 835, 773 Mass Spectrometric Analysis (FD-MS); 586 (M+) Example 4 Synthesis or (16RS)-15-deoxy-16-hydroxy-16 methyl-7-thiaprostaglandin E1 methyl ester The (16RS)-15-deoxy-11-t-butyldimethylsilyl-16- trimethylsilyloxy-16-methyl-7-thiaprostaglandin E1 methyl ester (800 mg, 1.36 mmol) obtained in Example 3 was dissolved in acetonitrile (10 ml). To this solution, pyridine (1 ml) and hydrogen fluoride-pyridine (2 ml) were added, and the mixture was stirred at room temperature for 1.5 hours. The reaction mixture was poured on an aqueous saturated sodium hydrogen carbonate solution (70 ml) and the resultant mixture was extracted with ethyl acetate. The aqueous layer was extracted twice with ethyl acetate and the extracted organic layers were combined. The extracted layer was washed with 1N hydrochloric acid, an aqueous solution saturated with sodium hydrogen carbonate and an aqueous saturated sodium chloride solution in that order, and was dried with anhydrous sodium carbonate. After filtration and concentration, the resultant product was subjected to silica gel column chromatography (cyclohexane ethylacetate : methanol - 2 : 2 : 0.04) to obtain the desired (16RS)-15-deoxy-16-hydroxy-16-methyl-7-thia- prostaglandin E1 methyl ester (480 mg, 1.20 mmol, 88%). Nuclear Magnetic Resonance (CDC13 , 6(ppm)); 0.88 (3H, t), 1.14 (3H, s), 1.0 ¯ 1.9 (12H, m), 2.0 X 3.4 (llH, m), 3.61 (3H, s), 3.6 a 4.5 (2H, m), 5.2 N 6.0 (2H, m) Infrared Absorption Spectrum (liquid film, cm 1); 3420, 1738 Mass Spectrometric Analysis (FD-MS); 400 (M+) Example 5 Synthesis of (16RS)-15-deoxy-16-hydroxy 16-methyl-7-thiaprostanglandin E1 The (16RS)-15-deoxy-16-hydroxy-16-methyl-7-thia- prostaglandin E1 methyl ester (400 mg, 1.0 mmol) obtained in Example 4 was dissolved in acetone (4 ml). To this solution, a phosphoric acid buffer (40 ml) having a pH of 8 was added, followed by the addition of swine liver esterase (produced by Sigma Co., No. E-3128, pH 8, 0.4 ml). The resultant mixture was stirred at room temperature for 24 hours. After the completion of the reaction, the reaction mixture was acidified to a pH of 4 with 0.1 N hydrochloric acid and the aqueous layer was saturated with ammonium sulfate. Thereafter, the aqueous layer was extracted with ethyl acetate and the extract was washed with an aqueous sodium chloride solution. After the washed extract was dried over magnesium sulfate, it was concentrated in vacuo to obtain a crude product. The crude product was subjected to silica gel column chromatography (hexane : ethyl acetate = 1 : 4, 0.1% acetic acid) to purify it, thereby isolating (16RS)-15-deoxy-16-hydroxy-16-methyl-7-thia- prostaglandin E1 (340 mg, 0.88 mmol, 88%). Nuclear Magnetic Resonance (CDCl3 , 6(ppm)); 0.86 (3S, t), 1.13 (3H, s), 1.0 N 1.9 (12H, m), 2.0 N 3.4 (llH, m), 3.6 N 4.5 (2R, m), 5.2 ¯ 6.0 (2H, m), 6.23 (1H, bs) Infrared Absorption Spectrum (liquid film, cm 1); ; 3400, 1740, 1710 Example 6 Synthesis of (16RS)-15-deoxy-11-t-butyldimethyl- silyl-16-trimethylsilyloxy-16-vinyl-7- thiaprostaglandin E1 methyl ester d1-(E)-4-trimethylsilyloxy-4-vinyl-1-iodo-1-octene (1.79 g, 5.25 mmol), t-butyllithium (1.9 M, 5.5 ml, 10.5 mmol), phenylthiocopper (906 mg, 5.25 mmol), and (4R) -4-t-butyldimethylsilyloxy-2- (5-methoxycarbonyl- pentylthio)-2-cyclopentenone (1.86 g, 5.0 mmol) were reacted according to the same procedures as those described in Example 1 in the same manner as in Example 1. The same post-treatment and column separation as in Example were effected to obtain the desired (16RS)-15-deoxy-11-t-butyldimethylsilyl-16- trimethylsilyloxy-16-vinyl-7-thiaprostaglandin E1 methyl ester (2.72 g, 4.65 mmol, 93%). Nuclear Magnetic Resonance (CDC13 , 0.04 (6H, s), 0.09 (9H, s), 0.85 (12H), 1.1 N 1.9 (12H, m), 1.9 ¯ 3.1 (1or, m), 3.63 (3H, s), 3.8 ¯ 4.2 (1H, m), 4.8 N 5.6 (5H, m) Infrared Absorption Spectrum (liquid film, cm-1); 3080, 1740, 1250, 835, 775 Mass Spectrometric Analysis (FD-MS), 586 (M+) Example 7 Synthesis of (l6RS) -15-deoxy-l6-hydroxy- 16-vinyl-7-thiaprostaglandin E1 methyl ester The (16RS)-15-deoxyS t-butyldimethylsilyl-16- trimethylsilyloxy-16-vinyl-7-thiaprostaglandin E1 methyl ester (1.76 g, 3.0 mmol) obtained in Example 6 was reacted in the same manner as in Example 4. The same post-treatment and column separation as in Example 4 were effected to obtain (16RS)-15-deoxy-16-hydroxy-16- vinyl-7-thiaprostaglandin E1 methyl ester (1.04 g, 2.61 mmol, 87%). Nuclear Magnetic Resonance (CDCl3 , 6(ppm)); 0.87 (3H, t), 1.1 ¯ 1.7 (12E, m), 2.0 N 3.1 (12H, m), 3.60 (3H, s), 3.8 ¯ 4.4 (1H, m), 4.8 N 5.7 (5H, m) Infrared Absorption Spectrum (liquid film, cm 1); 3400, 3080, 1740, 1160, 1080, 970, 730 Mass Spectrometric Analysis (FD-MS); 400 (M+) Example 8 Synthesis of (16RS)-15-deoxy-2,3-dehydro-11-t- butyldimethylsilyl-16-t-butyldimethylsilyloxy-7 thiaprostaglandin E1 methyl ester dl-(E)-4-t-butyldimethylsilyloxy-1-iodo-1-octene (1.77 g, 4.8 mmol), t-butyllithium (2.0 M, 4.8 ml, 9.6 mmol), phenylthiocopper (828 mg, 4.8 mmol), and (4R) -4-t-butyldimethylsilyloxy-2- (5-methoxycarbonyl- 4(E)-pentenylthio)-2-cyclopentenone (1.48 g, 4.0 mmol) were reacted according to the same procedures as those described in Example 1 in the same manner as in Example 1. The same post-treatment and column separation as in Example 1 were effected to obtain the desired (16RS)-15-deoxy-2,3-dehydro-11-t-butyldimethyl- silyl-16-t-butyldimethylsilyloxy-7-thiaprostaglandin E1 methyl ester (2.18 g, 3.56 mmol, 89%). Nuclear Magnetic Resonance (CDC13 , (ppm)); 0.03 (12H, s), 0.85 (21H), 0.8 X 2.0 (8E, m), 2.0 N 3.1 (10H, m), 3.65 (3E, s), 3.3 N 4.4 (2H, m), 5.1 ¯ 5.7 (2H, m), 5.80 (1H, d, J = 16 Hz), 6.85 (1H, dt, J = 16 and 6 Hz). Infrared Absorption Spectrum (liquid film, cm ); 1730, 1660, 1260, 1110, 840, 780 Mass Spectrometric Analysis (FD-MS); 612 (M ) Example 9 Synthesis of (16RS)-15-deoxy-2,3-dehydro-16-hydroxy- 7-thiaprostagiandin E1 methyl ester The (16RS)-15-deoxy-2,3-dihydro-11-t-butyldimethyl- silyl-16-t-butyldimethylsilyloxy-7-thiaprostaglandin E1 methyl ester (1.84 g, 3.0 mmol) was reacted in the same manner as in Example 4. The same post-treatment and column separation as in Example 4 were effected to obtain (16RS)-15-deoxy-2,3-dehydro-16-hydroxy-7-thia- prostaglandin E1 methyl ester (956 mg, 2.49 mmol, 83%). Nuclear Magnetic Resonance (CDC13 , (ppm)); 0.87 (3H), 1.0 ¯ 2.8 (20H), 3.65 (3H, s), 3.3 ¯ 4.4 (2H, m), 5.1 ¯ 5.7 (2H, m), 5.82 (1H, d, J = 16 Hz), 6.87 (1H, dt, J = 16 and 6 Hz) -1 Infrared Absorption Spectrum (liquid film, cm ); 3420, 1740, 1720, 1660, 1270, 1080, 975, 730 Mass Spectrometric Analysis (FD-MS); 384 (M+) Example 10 Synthesis of (4Z)-(16RS)-ll-t-butyldimethylsilyl 4, 5-dehydro-15-deoxy-16-methyl-16-trimethylsilyloxy- 7-thiaprostaglandin E1 methyl ester In the same manner as in Example 1, from dl-(E)-4trimethylsilyloxy-l-iodo-l-octene, and (R)-4-t-butyldi methylsilyloxy-2- ( (Z) -5-methoxycarbonyl-2-pentenylthio) - 2-cyclopentenone, (4Z)-(16RS)-ll-t-butyldimethylsilyl4,5-dehydro-15-deoxy-16-methyl-16-triemthylsilyloxy-7thiaprostaglandin E1 methyl ester was obtained in a yield of 79%. Nuclear Magnetic Resonance (CDC13 , 0.0 ¯ 0.2 (15H, m), 0.87 (9H, s), 0.7 ¯ 1.0 (3H, m), 1.18 (3H, s), 1.1 ¯ 2.0 (6H, m), 2.0 N 3.1 (12H, m), 3.61 (3H, s), 1.1 ¯ 2.0 (6H, m), 2.0 ¯ 3.1 (12H, m), 3.61 (3H, s), 3.8 ¯ 4.2 (1H, m), 5.2 ¯ 6.0 (4H, m) Infrared Absorption Spectrum (liquid film, cm 3080, 1740, 1250, 835, 775 Mass Spectrometric Analysis (FD-MS); 584 (M Example 11 Synthesis of (4Z)-(l6RS)-4,5-dehydro- 15-deoxv-l6-hydroxy-16-methyl-7-thiaprc,sta- glandin E1 methyl ester The (4Z)-(16RS)-;l-t-butyldimethylsilyl-4,5-dehydro- l5-deoxy-l 6-methyl-l 6-trimethylsilyloxy-7-thiaprosta- glandin E1 methyl ester obtained in Example 10 was subjected to exactly the same deprotection, posttreatment and purification, so as to obtain (4Z)-(16RS)4,5-dehydro-15-deoxy-16- hydroxy-16-methyl-7-thiaprostaglandin E1 methyl ester in a yield of 83%. Nuclear Magnetic Resonance (CDC13 , 6 (ppm)); 0.88 (3H,t), 1.14 (3H,S), 1.1 ¯ 2.0 (6H, m), 2.0 6 3.4 (14H, m), 3.61 (3H, s), 3.6 ¯ 4.5 (2H,m), 5.2 ¯ 6.0 (4H, m) Infrared Absorption Spectrum (liquid film, cm 3420, 1740, 1260, 845, 730 Mass Spectrometric Analysis (FD-MS); ; 398 (M+) Example 12 Synthesis of (165) -15-deoxy-16-hydroxy-16-methyl- 7-thiaprostaglandin E1 methyl ester Exactly the same manner as in Example 3 was repeated except that (lE)-(4S)-4-trimethylsilyloxy-4-methyl-1- iodo-l-octene ([a] 24 + 1.6 (C = 0.62, CHCl3)) was used in place of the dl-(E)-4-trimethylsilyloxy-4-methyl-liodo-l-octene. Thus, (16S)-15-deoxy-ll-t-butyldimethyl- silyl-16-trimethylsilyloxy-16-methyl-7-thiaprostaglandin E1 methyl ester (82%) was obtained. The spectral data of this product agreed with those of the product of Example 3. Then, the above-mentioned product was subjected to exactly the same deprotection method as in Example 4 to obtain (16S)-15-deoxy-16-hydroxy-16-methyl-7-thiaprostaglandin E1 methyl ester (91%). The spectral data of this product agreed with those of the product of Example 4. Example 13 Synthesis of (16R)-15-deoxy-16-ydroxy-16-methyl-7- thiaprostaglandin E1 methyl estcr Exactly the same manner as in Example 3 was repeated except that (lE)-(4R)-4-trimethylsilyloxy-4-methyl-1- iodo-l-octene ([a] - 1.60 (C = 0.59, CHC13)) was used in place of the dl-(E)-4-trimethylsilyloxy-4-methyl-liodo-l-octene. Thus, (16R)-15-deoxy-ll-t-butyldimethylsilyl-16-trimethylsilyloxy-16-methyl-7-thiaprostaglandin E1 methyl ester (87%) was obtained. The spectral data of this product agreed with those of the product of Example 3. Then, the above-mentioned product was subjected to exactly the same deprotection method as in Example 4 to obtain (16R)-15-deoxy-16-hydroxy-16-methyl-7-thiaprostaglandin E1 methyl ester (86%). The spectral data of this product agreed with those of the product of Example 4. Example 14 Synthesis of 11,15-bis(t-butyldimethylsilyl3- 4,4,5,5-dehydro-7-thiaprostaglandin E1 methyl ester (E) - (3S) -t-butyldimethylsilyloxy-1-iodo-l-octene (4.39 g, 11.94 mmol) was dissolved in ether (20 ml) and cooled to -780C. Then, t-butyllithium (1.9 M, 12.9 ml, 23.9 mmol) was added to the solution and the resultant mixture was stirred at a temperature of -78 C for 2 hours. Phenylthiocopper (2.06 g, 11.94 mmol3 and a solution of hexamethylphosphorustriamide (5.84 g, 35.8 mmol) in ether (20 ml) were added to the reaction mixture, and the resultant mixture was stirred at a temperature of -780C for 1 hour. Then, a solution of (R) -4-t-butyldimethylsilyloxy-2- (5-methoxycarbonyl-2- pentynylthio)-2-cyclopentenone (3.95 g, 10.7 mmol) in tetrahydrofuran (50 ml) was added to the above mixture, and the resultant mixture was stirred at a temperature of -780C for 15 minutes and at a temperature of -40 C for 30 minutes. The reaction mixture was added with a 2M acetate buffer solution and was extracted with hexane (150 ml x 3). Each organic layer was washed with an aqueous sodium chloride solution, dried over anhydrous magnesium sulfate, filtered and concentrated so as to obtain 6.8 g of a crude product. The crude product was subjected to silica gel column chromatography (hexane:ethyl acetate = 4:1) to obtain the desired 11,15-b is (t-butyldimethylsilyl) -4,4,5, 5-dehydro-7-thia- prostaglandin E1 methyl ester (6.83 g, 11.2 mmol, 94%). Nuclear Magnetic Resonance (CDC13 , 6 (ppm)); 0.06 (12H, s, 0.87 (21H), 1.0 * 1.8 (8H, m), 2.3 "a 3.6 (lOH, m), 3.67 (3E, s) 3.80 N 4.40 (2H, m), 5.50 X 5.75 (2H, m) Infrared Absorption Spectrum (liquid film, cm 1745, 1250, 1165, 1110, 1075, 965, 885, 835, 805, 775 Mass Spectrometric Analysis (FD-MS); 610 (M+) Example 15 Synthesis of 4,4,5,5-dehydro-7-thiaprostaglandin E1 methyl ester The 11,15-bis(t-butyldimethylsilyl)-4,4,5,5-dehydro- 7-thiaprostaglandin E1 methyl ester (1.22 g, 2.0 mmol) obtained in Example 14 was dissolved in acetonitrile (50 ml). To this solution, pyridine (1.0 ml) and then hydrogen fluoride-pyridine (2.0 ml) were added, and the resultant mixture was stirred at room temperature for 3 hours. The reaction mixture was neutralized with an aqueous solution of sodium hydrogen carbonate, and extracted with ethyl acetate (150 ml x 3). Each of the separated organic layers was washed with an aqueous sodium chloride solution, dried over anhydrous magnesium sulfate and concentrated to obtain 780 mg of a crude product. The crude product was subjected to silica gel column chromatography (hexane:ethyl acetate = 1:3) to obtain the desired 4,4,5,5-dehydro-7-thf3prostaglanain E1 methyl ester (710 mg, 1.86 mmol, 93%j. Nuclear Magnetic Resonance (CDCl3 , # (ppm)); 0.7 N 1.0 (3H, m) , 1.0 X 1.8 (8H, m), 2.3 ¯ 3.5 (12H, m), 3.67 (3H, s) 3.8 ¯ 4.4 (2H, m), 5.6 X 5.8 (2H, m) Infrared Absorption Spectrum (liquid film, cm 3400, 1740, 1260, 845, 730 Mass Spectrometric Analysis (FD-MS); 382 (M+) Example 16 Synthesis of 11,15-bis(t-butyldimethylsilyl) 4,4,5,5-dehydro-17(R),20-dimethyl-7- thiaprostaglandin E1 methyl ester The same procedures as those described in Example 14 were repeated except that (E)-(3S, 5R)-3-t-butyldimethyl silyloxy-5-methyl-l-iodo-1-nonen was used in place of the (E) - (3S)-t-butyldimethylsilyloxy-1-iodo-1-octene, and l-pentynylcopper was used in place of the phenylthiocopper. Thus, 11,15-bis(t-butyldimethylsilyl) 4,4,5,5-dehydro-17(R),20-dimethyl-7-thiaprostaglandin E1 methyl ester was obtained in a yield of 89%. Nuclear Magnetic Resonance (CDC13 , 6 (ppm)); 0.06 (12H, s) 0.87 (24H), 1.0 ¯ 1.8 (9H, m), 2.3 ¯ 3.6 (10H, m), 3.67 (3H, s), 3.85 X 4.35 (2H, m), 5.50 X 5.75 (2H, m) -1 Infrared Absorption Spectrum (liquid film, cm ); 1745, 1250, 1165, 1110, 1075, 965, 885, 835, 805, 775 Mass Spectrometric Analysis (FD-MS); ; 638 (M ), 581 (M-57), 57 Example 17 Synthesis of 4,4,5,5-dehydro-17(R),20-dimethyl-7- thiaprostaglandin E1 methyl ester The 11,15-bis(t-butyldimethylsilyloxy)-4,4,5,5- dehydro-17(R), 20-dimethyl-7-thiaprostaglandin E1 methyl ester obtained in Example 16 was subjected to exactly the same deprotection reaction, post-treatment and purification as those described in Example 2, so as to obtain 4,4,5,5-dehydro-17(R),20-dimethyl-7-thia- prostaglandin E1 methyl ester in a yield of 79%. Nuclear Magnetic Resonance (CDC13 , 6 (ppm)); 0.7 N 1.0 (6H, m), 1.0 ¯ 1.9 (9H, m), 2.3 N 3.5 (12H, m), 3.67 (3H, s) 3.8 X 4.4 (2H, m), 5.6 ¯ 5.8 (2H, m) Infrared Absorption Spectrum (liquid film, cm 1); 3400, 1740, 1240, 1200, 1165, 1075, 1040, 965, 735 Mass Spectrometric Analysis (FD-MS); 410 (M+) Example 18 Synthesis of (4E)-11,15-bis(t-butyldimethylsilyl)- 4, 5-dehydro-16 ,17,18,19, 20-pentanor-15- cyclohexyl-7-thiaprostaglandin E1 methyl ester According to the same manner as in Example 14, from (E)-(3S)-t-butyldimethylsilyloxy-3-cyclohexyl-1- iodo-l- propene and (R) -4-t-butyldimethylsilyloxy-2- ((E) -5-methoxycarbonyl-2-pentenylthio) -2-cyclopentenone, (4E)-11,15-bis(t-butyldimethylsilyl)-4,5-dehydro- 16,17,18,19,20-pentanol-15-cyclohexyl-7-thiaprostaglandin E1 methyl ester was obtained in a yield of 87%. Nuclear Magnetic Resonance (CDC13 , 6 (ppm)); 0.06 (12H, s), 0.87 (18H, s), 0.8 Ç 1.9 (11H, m), 1.9 X 3.1 (10H, m), 3.7 N 4.3 (2H, m), 3.65 (3H, s), 5.2 X 5.8 (4H, m) Infrared Absorption Spectrum (liquid film, cm ) 3080, 1740, 1270, 1200, 1080, 975, 885, 835, 805, 775 Mass Spectrometric Analysis (FD-MS); 624 (M ) Example 19 Synthesis of (4E)-4,5-dehydro-16,17,18,19,20 pentanor-15-cyclohexyl-7-thiaprostaglandin E1 methyl ester The (4E)-11,15-bis(t-butyldimethylsilyl)-4,5- dehydro-16,17,18,19,20-pentanor-lS-cyc'ohexyl-7-thia- prostaglandin E1 methyl ester obtained in Example 18 was subjected to exactly the same deprotection, posttreatment and purification as those described in Example 15, so as to obtain (4E)-4,5-dehydro-16,17, 18,19, 20-pentanor-15-cyclohexyl-7-thiaprostaglandin E1 methyl ester in a yield of 86%. Nuclear Magnetic Resonance (CDC13 , 6 (ppm)); 0.8 X 1.9 (11H, m), 1.9 ¯ 3.2 (12H, m), 3.7 X 4.3 (2H, m), 3.63 (3H, s), 5.2 X 5.8 (4H, m) -l Infrared Absorption Spectrum (liquid film, cm 3420, 3080, 1740, 1270, 1200, 1080, 975, 910, 730 Mass Spectrometric Analysis (FD-MS); 396 (M 1) Example 20 Synthesis of (4Z) -11,15-bis (t-butyldimethylsilyl) - 4,5-dehydro-7-thiaprostaglandin E1 methyl ester The 11,15-bis(t-butyldimethylsilyl)-4,4,5,5-dehydro- 7-thiaprostaglandin E1 methyl ester (610 mg, 1.0 mmol) obtained in Example 14 was dissolved in ethyl acetate (10 ml). The solution was added with 50 mg of a lindlar catalyst and was stirred at room temperature for 24 hours. The catalyst was filtered off and the reaction mixture was washed with ethyl acetate and concentrated to obtain a crude product. The crude product was subjected to silica gel column chromatography (hexane:ethyl acetate = 4:1) so as to obtain the desired (4Z)-11,15-bis(t-butyl-dimethylsilyl)-4,5-dehydro-7-thia- prostaglandin E1 methyl ester (428 mg, 0.70 mmol, 70%). Nuclear Magnetic Resonance (CDC13 , 6 (ppm)); 0.06 (12H, s), 0.87 (3H, s), 1.0 X 1.8 (8H, m), 2.3 ¯ 3.6 (10H, m), 3.67 (3H, s), 3.8 ¯ 4.4 (2H, m), 5.2 N 5.8 (4H, m) Infrared Absorption Spectrum (liquid film, cm 1) 1745, 1250, 1165, 1110, 1075, 965, 885, 835, 805, 775 Mass Spectrometric Analysis (FD-MS); ; 612 (M Example 21 Synthesis of (4Z)-4,5-dehydro-7-thiaprostaglandin E methyl ester The (4Z)-11,15-bis(t-butyldimethylsilyl)-4,5 dehydro-7-thiaprostaglandin E1 methyl ester (306 mg, 0.5 mmol) obtained in Example 20 was subjected to exactly the same deprotection, post-treatment and purification as those described in Example 2, so as to obtain (4Z)-4,5-dehydro-7-thiaprostaglandin E1 methyl ester (177 mg, 0.46 mmol, 92%). Nuclear Magnetic Resonance (CDC13 , 6 (ppm)); 0.88 (3H, t), 1.0 ¯ 1.8 (8H, m), 2.2 N 3.6 (12H, m), 3.63 (3H, s), 3.8 ¯ 4.4 (2H, m), 5.2 N 5.8 (4H, m) Infrared Absorption Spectrum (liquid film, cm 1); 3400, 1740, 1260, 845, 730 Mass Spectrometric Analysis (FD-MS); 384 (M+) Example 22 Synthesis of 4,4,5,5-dehydro-7-thiaprostaglandin E1 The 4,4,5,5-dehydro-7-thiaprostaglandin E1 methyl ester (191 mg, 0.5 mmol) obtained in Example 15 was dissolved in acetone (2 ml). To this solution, a phosphoric acid buffer solution (20 ml) having a pH of 8 was added and then, swine liver esterase (produced by Sigma Co., No. E-3128, pH 8, 0.2 ml) was added. The resultant mixture was stirred at room temperature for 24 hours. After the completion of the rection, the reaction mixture was acidified to a pH of 4 with 0.1 N hydrochloric acid. After the aqueous layer was saturated with ammonium sulfate, it was extracted with ethyl acetate and the extract was washed with an aqueous sodium chloride solution. The organic layer was dried over magnesium sulfate and concentrated in vacuo to obtain a crude product. The crude product was subjected to silica gel column chromatography (hc.ane:ethyl acetate " 1:4, 0.1% acetic acid) to purify it, thereby obtaining 4,4,5,5-dehydro-7-thiaprostagandin E1 (162 mg, 0.44 mmol, 88%). Nuclear Magnetic Resonance (CDC13 , 6 (ppm)); 0.7 N 1.0 (3H, m), 1.0 ¯ 1.8 (8H, m), 2.3 ¯ 3.5 (10H, m), 3.8 "a 4.4 (2H, m), 5.6 N 5.8 (2H, m), 6.30 (3H, bs) Infrared Absorption Spectrum (liquid film, cm 1); 3400, 1740, 1710 Mass Spectrometric Spectrum (FD-MS); 368 (M+) Example 23 Synthesis of (4Z)-4,5-dehydro-7-thiaprostaglandin E1 The (4Z)-4,5-dehydro-7-thiaprostaglandin E1 methyl ester obtained in Example 21 was subjected to exactly the same hydrolysis method as in Example 22, so as to obtain the corresponding (4Z)-4,5-dehydro-7-thiaprostaglandin E1 in a yield of 87%. Nuclear Magnetic Resonance (CDC13 , 6 (ppm)); 0.88 (3H, t), 1.0 ¯ 1.8 (8H, m), 2.2 X 3.6 (10H, m), 3.8 ¯ 4.4 (2H, m), 5.2 ¯ 5.8 (4H, m), 6.50 (3H, bs) Infrared Absorption Spectrum (liquid film, cm-1); 3400, 1740, 1710 Mass Spectrometric Analysis (FD-MS); 370 (M+) Example 24 Synthesis of (17R),20-dimethyl-7-thiaprostaglandin El-4,4,5,5-d4 methyl ester 11,15-bis(t-butyldimethylsilyl)-4,4,5,5-dehydro- (17R),20-dimethyl-7-thiaprostaglandin E1 methyl ester, which was used as the starting material, was catalytically reduced with deuterium in the presence of a hydrogenation catalyst consisting of 10% palladiumactivated carbon. The resultant product was subjected to deprotection to obtain (17R),20-dimethyl-7-thiaprostaglandin E -4,4,5,5-d4 methyl ester. Example 25 Synthesis of (l7R) ,20-dimethyl-7-thiaprostaglandin El-4,4,5,5-t4 methyl ester 11, 15-bis (t-butyidimethylsilyl) -4,4,5 ,5-dehydro- (17R),20-dimethyl-7-thiaprostaglandin E1 methyl ester, which was used as the starting material, was catalytically reduced with tritium in the presence of a hydrogenation catalyst consisting of 10% palladium-activated carbon. Thus, (17R),20-dimethyl-7-thiaprostaglandin E1-4,4,5,5-t4 methyl ester was obtained. Example 26 Synthesis of 19,20-dehydro-17,20-dimethyl-11,15 bis (t-butyl-dimethylsilyl) -7-thiaprostaglandin E1 methyl ester (i) A solution of 2.2M t-butyllithium in pentane (1.6 ml, 3.48 mmol) was added to a solution of 686 mg of (1E, 3S, SR)-l-iodo-5-methyl-1,7-nonadiene-3-ol t-butyldimethylsilylether in ether (5 ml) at a temperature of -780C. The resultant solution was strred for 2 hours. Hexamethylphosphorustriamide (567 mg, 3.48 mmol) was added to a suspension of phenylthiocopper (I) (300 mg, 1.74 mmol) in ether (2 ml) and the mixture was stirred at room temperature until a uniform solution was obtained. Then, this uniform solution was added to the above-prepared solution, and the mixture was stirred at a temperature of -780C for 1 hour. To this solution, a solution of 4 (R) -t-butyldimethylsilylexy-2- (5-methoxy- carbonylpentylthio)-2-cyclopentenone (647 mg, 1.74 mmol) in tetrahydrofuran (20 ml) was added, and the mixture was reacted at a temperature of -780C for 15 mintues and at a temperature of -400C for 1 hour. After the completion of the reaction, an aqueous ammonium chloride solution containing ammonia was added to the reaction mixture. The aqueous layer was extracted with ether (100 ml x 3) and the extract was washer with an aqueous ammonium chloride solution, dried (MgS and concentrated to botain a crude product. The crude product was subjected to column chromatography to purify it. Thus, 990 mg (yield 89%) of (17R)-19,20-dehydro-17,20-dimethyl- 11,15-bis(t-butyldimethylsilyl)-7-thiaprostaglandin E1 methyl ester was obtained in the 5% ethyl acetate-nhexane eluate fraction. (The configuration of the A19-double bond of this product contained 80 to 90% of Z-form. Nuclear Magnetic Resonance (CDC13 , S(ppm)); 0.88 (21H, bs), 3.65 (3H,S), 3.8 X 4.4 (2H, m), 5.2 N 5.7 (4H, m) Infrared Absorption Spectrum (liquid film, cm ); 1740, 1252, 1110, 965, 882, 835, 775 Mass Spectrometric Analysis (EI, m/e), 583 (M-tBu), 441, 381, 347, (ii) Similarily, from (1E, 3S, 5R)-1iodo-5-methyl-1,7-nonadiene-3-ol-t-butyldimethyl ether, (17S)-19,20-dehydro-17,20-dimethyl-11,15-bis(t-butyldimethylsilyl)-7-thiaprostaglandin E1 methyl ester was obtained. Nuclear Magnetic Resonance (CDC13 , S(ppm)); 0.88 (21H, bs), 3.66 (3H, S), 3.8 s 4.4 (2H, m), 5.2 % 5.7 (4H, m) In Frared Absorption Spectrum (liquid film, cm ); 1740, 1252, 1110, 965, 882, 835, 775 Mass Spetrometric Analysis (EI, m/e); 583 (M-tBu), 441 Example 27 Synthesis of 19,20-dehydro-17,20-dimethyl-7 thiaprostaglandin E1 methyl ester (i) 640 mg of the (17R)-19,20-dehydro-17,20 dimethyl-11,15-bis (t-butyldimethylsilyl) -7-thiaprosta- gland in E1 methyl ester obtained in Example 26 was dissolved in acetonitrile (20 ml). To this solution, 0.9 ml of pyridine and then 17 ml of pyridinium poly(hydrogen fluoride) were added. The resultant mixture was stirred at room temperature for 2 hours. The reaction mixture was neutralized with an aqueous solution of sodium hydrogen carbonate and extracted with ethyl acetate. The organic layer was washed with a saturated KHSO4 solution, a NaHCO3 solution and then an aqueous sodium chloride solution. After drying with MgS04 , the solvent was distilled away and the resultant crude product was subjected to silica gel chromatography to purify it. Thus, 363 mg (yield 88%) of (17R)-19,20 dehydro-17, 20-dimethyl-7-thiaprostaglandin E1 methyl ester was obtained in the 70 to 80% ethyl acetate-nhexane eluate fraction. Muclear Magnetic Resonance (CDCL3 , a (ppm)); 0.90 (3H, d, J = 5Hz), 3.60 (3H, s), 3.5 X 4.4 (4H, br) , 5.2 X 5.8 (4H, m) Infrared Absorption Spectrum (liquid film, cm ); 3425, 1735, 1438, 1200, 1172, 1080, 965 Mass Spectrometric Analysis (EI, m/e); 394 (M-H2O) , 376 (M-2H20) (ii) Similarily, from the (17S)-19,20-dehydro17,20-dimethyl-11,15-bis(t-butyldimethylsilyl)-7-thiaprostaglandin E1 methyl ester obtained in Example 26, (17S)-19,20-dehydro-17,20-dimethyl-7-thiaprostaglandin E1 methyl ester was obtained. Nuclear Magnetic Resonance (CDC13 , 6(ppm)); 0.90 (3H, d, J = 5Hz), 33.62 (3H, s), 3.5 N 4.4 (4H, br), 5.2 N 5.2 (4H, m) Infrared Absorption Spectrum (liquid film, cm ); 3420, 1738, 1438, 1200, 1170, 1080, 965. Mass Spectrometric Analysis (EI, m/e); 394 (M-H2O) , 376 (M-2H20) Example 28 Synthesis of (16RS) -15-deoxy-16-hydroxy-16- methyl-7-thiaprostaglandin E1 geranyl ester 100 mg (0.25 mmol) of (16RS)-15-deoxy-16-hydroxy-16 methyl-7-thiaprostaglandin E1 was dissolved in dry methylene chloride (1.2 ml). To this solution, 124 p1 (0.72 mmol) of geraniol was added. To tlis mixture, 9 mg (0.072 mmol) of 4- dimethylainopyidine and then 74 mg (0.36 mmol) of dicyclohexylcarbodiFmide were added under ice cooling, and the mixture was stirred for 30 minutes and then at room temperature for 1 hour. Ethyl acetate (20 ml) was added to the mixture and the resultant mixture was Celite filtered. The filtrate was mixed with water and the mixture was shaken in a separating funnel. The aqueous layer was again extracted with ethyl acetate (20 ml), after which the combined organic layer was washed with an aqueous potassium hydrogen sulfate solution, an aqueous sodium hydrogen carbonate solution, and an aqueous solution saturated with sodium chloride, and then dried over magnesium sulfate, after which the solvent was distilled away. The resultant residue was subjected to silica gel chromatography to effect separation and purification. Thus, 70 mg (yield 52%) of (16RS)-15-deoxy-16-hydroxy16-methyl-7-thiaprostaglandin E1 geranyl ester was obtained in the hexane-ethyl acetate (1:1) eluate fraction. Nuclear Magnetic Resonance (CDC13 , b(ppm)); 0.88 (3H, t), 1.14 (3H, s), 1.57 (3H, s), 1.67 (6H, s), 3.9 ¯ 4.3 (lH, br), 4.52 (2H, d, J=7Hz), 4.8 N 5.4 (2H, br), 5.61 (2H, m) Infrared Absorption Spectrum (liquid film, cm ); 3400, 2960, 2940, 2860, 1740, 1450, 1160, 965 Example 29 (i) Determination of Antiulcerative Effect The inhibiting effect on ulcer formation induced by indomethacin was examined by using rats. Wister male rats (7 weeks old and body weight of 220 g) were abstained from food for 24 hours except giving water and then subjected to experiments. The sample compounds to be tested were dissolved in a phosphoric acid buffer (pH 7.4) containing 0.9% NaCl and the solution was orally administered to the rats. 30 minutes after the administration, indomethacin was orally administered to the rats at a dose of 20 mg/kg. S hours after the administration of the indomethacin, the rats were kileld and the ulcer formation in the stomach was examined by determining the length of the ulcer formation portion under a stereomicroscope. From this measurement, the Inhibition of ulcer formation by the sample compounds were calculated to determine the ED50 values. The results are shown in Table 1. (ii) In vitro Blood Platelet Aggregation Inhibition Effect The in vitro blood platelet aggregation inhibition effect of the sample compounds to be tested was examined by using rabbits. That is, blood was collected from the ear vein of native Japanese white male domestic rabbits weighing 2.5 to 3.5 kg. The collected blood was 9 parts by volume per 1 part by volume of a 3.8% sodium citrate solution. The blood was centrifuged at 1000 r.p.m. for 10 mintues. The upper layer portion was separated as PRP (rich in platelet blood plasma). The lower layer portion was further centrifuged at 2800 r.p.m. for 10 mintues to divide it into two layers. The upper layer portion was separated as PPP (poor in platelet blood plasma). The number of the platelet was diluted with PPP to 6 to 7 x 10 / l. After the adjustment, 25 p1 of the sample compound was added to 250 p1 of PRP, which was preincubated at a temperature of 37"C for 2 minutes. Thereafter, 10 pM of ADP (final) was added to the preincubated PRP to record the variation of the transmittance by means of aggregometer. The sampel compounds were dissolved in ethanol to provide 10 mg/ml. When the activity of the sample compounds was determined, the ethanol solution was diluted with a phosphoric acid buffer (PH 7.4). The ethanol solution diluted with the buffer was left to staid at a temperature of 0 C for 4 hours, after which the activity of the sample compounds was determined in the same manner. The platelet aggregation inhibition was calculated by the following formula: T Inhibition (%) = (1 - To) x 100 T : the transmittance of the system to which 0 the phosphoric acid buffer is added T: the transmittance of the system to which the sample compounds are added The lowest concentration of the sample compounds at which the inhibition is 50% was represented as an ICso value. The results are shown in Table 1. Table 1 EMI43.1 <tb> <SEP> Antiulcerative <SEP> effect <SEP> Anti-platelet <tb> <SEP> Cat <SEP> aggregation <SEP> effect <tb> 3ED50 <SEP> (g/kg)P.O <SEP> EDso <SEP> (iig/kg) <SEP> P-O <SEP> IC50 <SEP> (g/±) <tb> Coqxxmd <SEP> of <SEP> this <SEP> invention <tb> <SEP> 0 <tb> <SEP> 10 <SEP> ¯ > xH3 <SEP> 10 <SEP> 17 <tb> <SEP> OH <tb> Canparative <SEP> ccPpO <tb> <SEP> 0 <tb> <SEP> K/S <SEP> CXXX3H, <tb> <SEP> 3 <SEP> Hz <SEP> 300 <SEP> > 100 <tb> <SEP> f <tb> <SEP> OH <tb> <SEP> 0 <tb> <SEP> K <SEP> S <SEP> COOT3 <SEP> 35 <SEP> O. <SEP> 004 <tb> <SEP> HO <SEP> OH <tb> As is apparent from Table 1, the compounds of the present invention are those having especially strong antiulcerative effect. Example 30 Determination of Effect against Ethanol Ulcer SD type male rats (7 wees old and body weight of 220 g) were abstained from food for 24 hours except giving water and then subjected to experiments. The sample compound to be tested was dissolved in a phosphoric acid buffer (pH 7.4) containing 0.9% NaCl and the solution was orally administered to the rats. 30 minutes after the administration, 7 ethanol was orally administered to the rats at a dose of 1 ml/kg. One hour after the administration of the ethanol, the rats were killed and the ulcer formation in the stomach was examined by determining the length of the ulcer formation portion under a stereomicroscope. From this measurement, the inhibition of ulcer formation by the sample compound was calculated to determine the ED50 value. The result is shown in Table 2. Table 2 EMI44.1 <tb> <SEP> Carmd <SEP> mtiulcerative <SEP> effect <tb> <SEP> catund <SEP> ED50 <SEP> (pg/kg) <SEP> P.O <tb> ChExxnd <SEP> of <SEP> this <SEP> invention <tb> <SEP> 0 <tb> <SEP> S <SEP> oI <tb> <SEP> - <SEP> 18 <tb> HO <SEP> OH <tb> CAPABILITY OF EXPLOITATION IN INDUSTRY The 7-thiaprostaglandins E1 of the present invention have interesting physiological activities and can be used for the prevention and/or treatment of various diseases such as digestive organ diseases, e.g., a duodenal ulcer and a gastric ulcer; liver diseases, e.g., hepatitis, toxipathic hepatitis, hepatic coma, hepertrophy of the liver, and hepatocirrhosis; pancreas, e.g., pancreatitis; arinary diseases, e.g., diabetos kidney diseases, acute kidney insufficiency, cystitis, and urethritis; respiratory diseases, e.g., pneumonia and bronchitis; incretion diseases immunity diseases; toxicosis, e.g., alcohol poisoning and carbon tetrachloride poisoning and low blood pressure. The 7-thiaprostaglandins E1 of the present invention are especially useful for the treatment and prevention of digestive organ diseases such as a duodenal ulcer and a gastric ulcer.

Claims: CLAIMS 1. 7-thiaprostaglandins E1 which .re compounds represented by the following formula [I] or their enantiomers or mixtures thereof in any ratio: EMI46.1 wherein RÚ represents a hydrogen atom, a C1-C10 alkyl group, a C2-C20 alkenyl group, a substituted or unsubstituted phenyl group, a substituted or unsubstituted C3-C10 cycloalkyl group, a substituted or unsubstituted phenyl(C1-C2)alkyl 2 and 3 group, or one equivalent cation; R and R which may be the same or different, represent a hydrogen atom, a tri(Cl-C7)hydrocarbon silyl group, or a group forming an acetal linkage together with an oxygen atom of a hydroxyl 4 group; R represents a hydrogen atom, a methyl group or a vinyl group; R5 represents a linear or branched C3-C8 alkyl group, a linear or branched C3-C8 a lkenyl group, a linear or branched C3-C8 alkynyl group, a phenyl group which may be substituted, a phenoxy group which may be substituted, a C3-C10 cycloalkyl group which may be substituted, or a linear or branched C1-C5 alkyl group which may be substituted with a C1-C6 alkoxy group, a phenyl group which may be substituted, a phenoxy group which may be substituted, or a C3-C10 cycloalkyl group which may be substituted; X represents an ethylene group, a vinylene group or an ethynylene group; n represents 0 or 1; the expression /' represents an ethylene group or a vinylene group; provided that when n is 0 and X is an ethylene group, R5 is not a linear or branched C3-C8 alkyl group or a C3-C1O cycloalkyl group which may be substituted. 2. The 7-thiaprostaglandins E1 according to claim 1, wherein R1 is a hydrogen atom, a C1-C10 alkyl group, a C2-C20 alkenyl group or one equivalent cation. 3. The 7-thiaprostaglandins E1 according to claim 1, wherein R5 is a butyl group, a pentyl group, a l-methyl-l-butyl group, a 2-methyl-l-butyl group, a cyclopentyl group, a cyclohexyl group or a phenyl group. 4. The 7-thiaprostaglandins E1 according to claim 1, wherein R2 and R3 may be the same or different, and are hydrogen atom, a tri(C1-C4)alkylsilyl group, a diphenyl(C1-C4)alkylsilyl group, a 2-tetrahydropyranyl group, a 2-tetrahydrofuranyl group, a l-ethoxyethyl group, a 2-methoxy-2-propyl group, a 2-ethoxy-2-propyl group, a (2-methoxyethoxy) methyl group, or a 6,6 dimethyl-3-oxa-2-oxobicyclof3,1,0]hexa-4-yl group. 5. A process for producing 7-thiaprostaglandins E1 which are compounds of the following formula [I] or the enantiomers thereof or mixtures thereof in any ratio: EMI47.1 wherein R1, R2, R3 R4 R5, X, n and the expression /,' are the same as defined above, which process comprises reacting an organolithium compound of the formula [11]: EMI47.2 wherein R31 represents a tri(C1-C7) hydrocarbon silyl group or a group forming an acetal linkage together with an oxygen atom of a hydroxyl group; and R4, R5 and n are the flame as defiend above, with a copper compound of the formula [III]: CuQ where Q represents a halogen atom, a cyano group, a phenylthiogroup, or a l-pentyl group; then reacting the resultant product with 2-organithio-2cyclopentenones of the formula [IV]: EMI48.1 wherein R11 represents a C1-C10 alkyl group, a C2-C20 alkenyl group, a substituted or unsubstituted phenyl group, a substituted or unsubstituted C3-C10 cycloalkyl group, or a substituted or unsubstituted phenyl (C1-C2) alkyl group; R represents a tri(C1-C7) hydrocarbon silyl group or a group forming an acetal linkage together with an oxygen atom of a hydroxyl group; and X and the expression / are the same as defined above, or the enantiomers thereof or mixtures thereof in any ratio; and optionally subjecting the resultant product to deprotection, hydrolysis, salt-formation and/or reduction reaction. 6. The process according to claim 5, wherein the copper compound of the formula [III] is used in an amount of 0.8 to 1.5 times by mole based on the organolithium compound of the formula [II]. 7. The process according to claim 5, wherein the reaction between the copper compound of the formula fill] and the organolithium compound of the formula [II], and the reaction between the resultant reaction product and the 2-organothio-2-cyclopentenones of the formula [IV] are carried out in a non-protonic inert organic medium. 8. The process according to claim 5, wherein the reaction of the rection product between the organolithium compound of the formula [II] and the copper compound of the formula [III] with 2-organothio-2-cyclopentenones of the formula [IV] is carried out in the presence of a trivalent organophosphorus compound.

Inventors: BANNAI, KIYOSHI 18-4-224, TAMADAIRA 3-CHOME, HAZATO, ATSUO 11-16-102, TAMADAIRA 6-CHOME, KUROZUMI, SEIJI 2-28, HIGASHITOKURA 1-CHOME, TANAKA, TOSHIO 17-20, TAMADAIRA 6-CHOME
Applicants: TEIJIN LIMITED
Application year: 1985
Main classification: C07C177
IPC codes: C07C405