Chemistry of the Podocarpaceae. LIX. Dimerization of a Favorski-type rearrangement product

Abstract

Ozonolysis of podocarpic acid (1) followed by reduction of the resulting hydroperoxide (16) gives a moderate yield of the keto diacid (6). Treatment of the derived 7α-bromo keto acid (10) with potassium carbonate in acetone effects a Favorski-type rearrangement with decarboxylation to give the methylene ketone (15); the latter dimerizes in hot ethanol to give a quantitative yield of (29).