Oxy effects on the platinum-catalyzed carbo- and oxacyclizations of 2-oxiranyl-1-(1-oxyalk-2-ynyl)benzenes

Abstract

We report new platinum-catalyzed protocols for the synthesis of carbocycles and oxacycles from 2-oxiranyl-1-(1-oxyalk-2-ynyl)benzenes. For 1,2,2-trisubstituted epoxides bearing an acyloxy group, their platinum-catalyzed cyclizations proceed through an initial 1,3-acyloxy shift, followed by an intramolecular attack of an allenyl acetate at the carbonyl group, ultimately giving 2-naphthyl ketones through a selective 1,2-alkyl shift. 1,1-Disubstituted epoxides bearing a siloxy group undergo an oxacyclization to give bicyclic ketals with high diastereoselectivity. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.