The hydrogenation of ethyl 3-(2-furyl)acrylate (I) with H2 over Raney-Ni in ethanol gives ethyl 3-(2-furyl)propionate (II), which oxidative methoxylation with Br2 in methanol affords ethyl 3-(2,5-dimethoxy-2,5-dihydro-2-furyl)propionate (III). The partial reduction of (III) with diisobutylaluminum hydride in toluene yields the substituted propionaldehyde (IV), which by a Wittig condensation with 4-carboxybutyl triphenylphosphonium bromide by means of NaH in DMSO gives 8-(2,5-dimethoxy-2,5-dihydro-2-furyl)-5-octenoic acid (VI). The hydrolytic ring opening of (VI), followed by an aldol cyclization in refluxing dioxane - water by means of sodium acetate - NaH2PO4 - hydroquinone affords 7-(2-oxo-5-hydroxycyclopent-3-en-1-yl)-5-heptenoic acid (VII), which is isomerized by treatment with H2SO4 yielding 7-(5-oxo-3-hydroxycyclopenten-1-yl)-5-heptenoic acid (VIII). Methylation and esterification of (VIII) with H2SO4/refluxing methanol gives the methoxy methyl ester (IX), which by reaction with 2-mercaptoethanol (A) and sodium methoxide in methanol is converted into methyl 7-[5-oxo-3-(2-hydroxyethylthio)cyclopenten-1-yl]-5-heptenoate (X). The methylation of acid (VI) with NaH and methyl iodide gives the corresponding methyl ester (XIV), which is submitted to a hydrolytic ring opening and aldol cyclization as before to afford methyl 7-(2-oxo-5-hydroxycyclopent-3-en-1-yl)-5-heptenoate (XV). The silylation of (XV) with trimethylchlorosilane and hexamethyldisilazane as usual yields the corresponding trimethylsilyloxy derivative (XVI), which is treated with 2-mercaptoethanol (A) and sodium methoxide to give the isomerized compound (X).

The protection of the free hydroxy group of (X) with trimethylchlorosilane and hexamethyldisilazane in pyridine gives the trimethylsilyl derivative (XI), which is condensed with [3-(triphenylmethoxy)-1-octenyl](pentenyl)lithiocuprate (XII) in HMPT-ether to afford 11-deoxy-11alpha-(2-trimethyl-silyloxyethylthio)-15-triphenylmethoxy-PGE2 methyl ester (XIII). Finally, this compound is deprotected by treatment with acetic acid in THF. The lithium cuprate (XII) is prepared as follows: Hydrogen iodide addition to 3-triphenylmethoxy-1-octyne (XVII) gives 1-iodo-3-triphenylmethoxy-1-octene (XVIII), which is condensed with copper 1-pentyne (B) and butyllithium in ether.

The hydrogenation of ethyl 3-(2-furyl)acrylate (I) with H2 over Raney-Ni in ethanol gives ethyl 3-(2-furyl)propionate (II), which oxidative methoxylation with Br2 in methanol affords ethyl 3-(2,5-dimethoxy-2,5-dihydro-2-furyl)propionate (III). The partial reduction of (III) with diisobutylaluminum hydride in toluene yields the substituted propionaldehyde (IV), which by a Wittig condensation with 4-carboxybutyl triphenylphosphonium bromide by means of NaH in DMSO gives 8-(2,5-dimethoxy-2,5-dihydro-2-furyl)-5-octenoic acid (VI). The hydrolytic ring opening of (VI), followed by an aldol cyclization in refluxing dioxane - water by means of sodium acetate - NaH2PO4 - hydroquinone affords 7-(2-oxo-5-hydroxycyclopent-3-en-1-yl)-5-heptenoic acid (VII), which is isomerized by treatment with H2SO4 yielding 7-(5-oxo-3-hydroxycyclopenten-1-yl)-5-heptenoic acid (VIII). Methylation and esterification of (VIII) with H2SO4/refluxing methanol gives the methoxy methyl ester (IX), which by reaction with 2-mercaptoethanol (A) and sodium methoxide in methanol is converted into methyl 7-[5-oxo-3-(2-hydroxyethylthio)cyclopenten-1-yl]-5-heptenoate (X). The methylation of acid (VI) with NaH and methyl iodide gives the corresponding methyl ester (XIV), which is submitted to a hydrolytic ring opening and aldol cyclization as before to afford methyl 7-(2-oxo-5-hydroxycyclopent-3-en-1-yl)-5-heptenoate (XV). The silylation of (XV) with trimethylchlorosilane and hexamethyldisilazane as usual yields the corresponding trimethylsilyloxy derivative (XVI), which is treated with 2-mercaptoethanol (A) and sodium methoxide to give the isomerized compound (X).

The protection of the free hydroxy group of (X) with trimethylchlorosilane and hexamethyldisilazane in pyridine gives the trimethylsilyl derivative (XI), which is condensed with [3-(triphenylmethoxy)-1-octenyl](pentenyl)lithiocuprate (XII) in HMPT-ether to afford 11-deoxy-11alpha-(2-trimethyl-silyloxyethylthio)-15-triphenylmethoxy-PGE2 methyl ester (XIII). Finally, this compound is deprotected by treatment with acetic acid in THF. The lithium cuprate (XII) is prepared as follows: Hydrogen iodide addition to 3-triphenylmethoxy-1-octyne (XVII) gives 1-iodo-3-triphenylmethoxy-1-octene (XVIII), which is condensed with copper 1-pentyne (B) and butyllithium in ether.

The hydrogenation of ethyl 3-(2-furyl)acrylate (I) with H2 over Raney-Ni in ethanol gives ethyl 3-(2-furyl)propionate (II), which oxidative methoxylation with Br2 in methanol affords ethyl 3-(2,5-dimethoxy-2,5-dihydro-2-furyl)propionate (III). The partial reduction of (III) with diisobutylaluminum hydride in toluene yields the substituted propionaldehyde (IV), which by a Wittig condensation with 4-carboxybutyl triphenylphosphonium bromide by means of NaH in DMSO gives 8-(2,5-dimethoxy-2,5-dihydro-2-furyl)-5-octenoic acid (VI). The hydrolytic ring opening of (VI), followed by an aldol cyclization in refluxing dioxane - water by means of sodium acetate - NaH2PO4 - hydroquinone affords 7-(2-oxo-5-hydroxycyclopent-3-en-1-yl)-5-heptenoic acid (VII), which is isomerized by treatment with H2SO4 yielding 7-(5-oxo-3-hydroxycyclopenten-1-yl)-5-heptenoic acid (VIII). Methylation and esterification of (VIII) with H2SO4/refluxing methanol gives the methoxy methyl ester (IX), which by reaction with 2-mercaptoethanol (A) and sodium methoxide in methanol is converted into methyl 7-[5-oxo-3-(2-hydroxyethylthio)cyclopenten-1-yl]-5-heptenoate (X). The methylation of acid (VI) with NaH and methyl iodide gives the corresponding methyl ester (XIV), which is submitted to a hydrolytic ring opening and aldol cyclization as before to afford methyl 7-(2-oxo-5-hydroxycyclopent-3-en-1-yl)-5-heptenoate (XV). The silylation of (XV) with trimethylchlorosilane and hexamethyldisilazane as usual yields the corresponding trimethylsilyloxy derivative (XVI), which is treated with 2-mercaptoethanol (A) and sodium methoxide to give the isomerized compound (X).

The protection of the free hydroxy group of (X) with trimethylchlorosilane and hexamethyldisilazane in pyridine gives the trimethylsilyl derivative (XI), which is condensed with [3-(triphenylmethoxy)-1-octenyl](pentenyl)lithiocuprate (XII) in HMPT-ether to afford 11-deoxy-11alpha-(2-trimethyl-silyloxyethylthio)-15-triphenylmethoxy-PGE2 methyl ester (XIII). Finally, this compound is deprotected by treatment with acetic acid in THF. The lithium cuprate (XII) is prepared as follows: Hydrogen iodide addition to 3-triphenylmethoxy-1-octyne (XVII) gives 1-iodo-3-triphenylmethoxy-1-octene (XVIII), which is condensed with copper 1-pentyne (B) and butyllithium in ether.

The hydrogenation of ethyl 3-(2-furyl)acrylate (I) with H2 over Raney-Ni in ethanol gives ethyl 3-(2-furyl)propionate (II), which oxidative methoxylation with Br2 in methanol affords ethyl 3-(2,5-dimethoxy-2,5-dihydro-2-furyl)propionate (III). The partial reduction of (III) with diisobutylaluminum hydride in toluene yields the substituted propionaldehyde (IV), which by a Wittig condensation with 4-carboxybutyl triphenylphosphonium bromide by means of NaH in DMSO gives 8-(2,5-dimethoxy-2,5-dihydro-2-furyl)-5-octenoic acid (VI). The hydrolytic ring opening of (VI), followed by an aldol cyclization in refluxing dioxane - water by means of sodium acetate - NaH2PO4 - hydroquinone affords 7-(2-oxo-5-hydroxycyclopent-3-en-1-yl)-5-heptenoic acid (VII), which is isomerized by treatment with H2SO4 yielding 7-(5-oxo-3-hydroxycyclopenten-1-yl)-5-heptenoic acid (VIII). Methylation and esterification of (VIII) with H2SO4/refluxing methanol gives the methoxy methyl ester (IX), which by reaction with 2-mercaptoethanol (A) and sodium methoxide in methanol is converted into methyl 7-[5-oxo-3-(2-hydroxyethylthio)cyclopenten-1-yl]-5-heptenoate (X). The methylation of acid (VI) with NaH and methyl iodide gives the corresponding methyl ester (XIV), which is submitted to a hydrolytic ring opening and aldol cyclization as before to afford methyl 7-(2-oxo-5-hydroxycyclopent-3-en-1-yl)-5-heptenoate (XV). The silylation of (XV) with trimethylchlorosilane and hexamethyldisilazane as usual yields the corresponding trimethylsilyloxy derivative (XVI), which is treated with 2-mercaptoethanol (A) and sodium methoxide to give the isomerized compound (X).