Aspects of the chemistry of 6,6a-dehydrorotenol, rotenononic acid, and isoderrisic acid acetates

Abstract

Treatment of either of the 12a-epimeric 6,6a-dehydrorotenols with methanolic acid gives a transformation product having a 5/7-membered B/C system: rationalisation is proposed. In the case of rotenononic acid formation, the 3-aroylbenzofuran structure rather than the related 2-aryl structure is supported as a result of n.m.r. examination of the decarboxylation product. Some apparent anomalies concerning the acetates of the isoderrisic acid series are cleared up: enol acetate formation and rapid esterification by the solvent methanol may result in one of four acetates being formed.