IMPROVED METHOD OF PRODUCTION OF 9-CIS-RETINOIC ACID

摘要

Method of production of 9-(Z)-retinoic acid, in which: a) a .beta.-formyl-crotonic acid C1-C10 alkyl or phenyl ester is reacted with an isolated 9-(Z)-C15-triarylphosphonium salt by the Wittig reaction in the presence of a base to the corresponding 9-(Z)-retinoic acid ester, which b) is then saponified with a base to the corresponding 9-(Z)-retinoic acid carboxylate and then, following protonation with an acid, the desired 9-(Z)-retinoic acid is obtained, and method for the enrichment and isolation of the 9-(Z)-C15-triarylphosphonium salt, wherein the 9-(Z)-C15-triarylphosphonium salt is a compound of formula (I) (see formula I) in which aryl represents an optionally substituted C6-C10 aryl residue and X represents a halogen.