Stereochemical Control in Intramolecular Ene Reactions of Crotyl Propargyl Ether Systems

Abstract
Stereochemical features are described of the title reactions leading to the γ-alkylidene-β-vinyloxolanes. Of particular interest is the high 1,2-trans diastereoselectivity observed for the (α-alkyl)crotyl and (α,β-dialkyl)crotyl ether systems with methoxycarbonyl group at the acetylenic terminus which remarkably facilitates the ene cyclization.