Process for producing 1,3-substituted tetrahydro-1H-thieno-[3,4-d]-imidazol-2(3H)-on-4-ylidene pentanoic acid ester

Claim 1

Process for producing a 1,3-substituted tetrahydro-1H-thieno-[3,4-d]-imidazol-2(3H)-on-4-ylidene pentanoic acid ester of the formula: ##STR6## wherein R is a C 1 -C 6 alkyl group which is a straight-chain or branched, or a phenyl or benzyl group which is unsubstituted or substituted with at least one halogen atom or with a lower alkyl group and R 1 is an (R)- or (S)-1-phenyl lower alkyl group and R 2 is hydrogen, a lower alkanoyl group, a benzoyl group, a benzyl group which is unsubstituted or substituted with halogen or lower alkyl, a lower alkoxycarbonyl group, a lower alkoxyloweralkyl group, consisting essentially of reducing a 1,3-substituted tetrahydro-1H-thieno-[3,4-d]-imidazole-2,4-dione of the formula: ##STR7## wherein R 1 and R 2 have the above meanings, with a reducing agent selected from the group consisting of diisobutyl aluminum hydride, sodium borohydride, a borane complex or a complex aluminum hydride, to the corresponding hydroxy compound of the formula: ##STR8## reacting the corresponding hydroxy compound with a phosphonium salt of the formula: (R.sub.3).sub.3 PH.sup.⊕ X.sup.⊖ III wherein R 3 is an alkyl group with 1 to 20 C atoms, a phenyl group or benzyl group and X is a halogen atom, BF 4 - , ClO 4 - , I 3 - or PF 6 - , to provide a phosphonium compound of the formula: ##STR9## wherein R 1 , R 2 , R 3 and X have the above meanings, and converting the phosphonium compound of formula IV into the end product in the presence of a strong base with a 5-oxo-valeric acid ester of the formula: ##STR10## wherein R has the meaning above.