A free radical method for attaching an oxygen-containing ring to either face of a bicyclic structure

Abstract

A method is described for attaching an oxygen-containing ring to either face of a cyclic ketone. The procedure involves selenenylation via the enolate followed by diisobutylaluminium hydride reduction to afford a cisα-(phenylseleno) alcohol. A prop-2-ynyl chain is then attached to the hydroxy group, and radical cyclization generates a new ring. If the original α-(phenylseleno) ketone is deprotonated and reprotonated, the same sequence of reduction, O-alkylation, and radical closure then serves to generate a new ring on the other face of the starting ketone.