Synthesis of olefins by base-induced fragmentation of 2-phenyl-1,3-oxathiolans

Abstract

Treatment of 2-phenyl-1,3-oxathiolans with a lithium dialkylamide in ether leads to fragmentation to olefin and lithium thiobenzoate. Under certain conditions further reaction to give a dialkylbenzamide occurs. The olefin is formed stereospecifically, and the reaction has been developed into a method for ‘olefin inversion,’ illustrated by the preparation of trans-cyclo-octene, cis,trans-cyclo-octa-1,5-diene, and cis-stilbene. The latter two examples represent structural types which could not be prepared by the dioxolan olefin synthesis.