Recent progress in the synthesis of butenolide carotenoids and retinoids

Abstract

Two kinds of method (the Wittig and sulphone methods) to prepare 4-alkylidenebutenolides are described. An empirical rule regarding the NMR chemical shifts of H-3 in 4-alkylidenebutenolides displaying an extended conjuga-ed system at the C-2 position is shown. Total synthesis of racemic peridinin and pyrrhoxanthin has been accomplished by means of the sulphone method and optically active peridinin has been synthesised. Recent work on the synthesis of butenolide retinoids is also described. © 1991 IUPAC