A new, efficient synthesis of (+)-isodrimenin

Abstract

A new, efficient synthesis of natural (+)-isodrimenin (1a) from manool is reported. This synthesis consists of the following key steps. The cyclic peroxide (3), obtained from the diene (2) by photo-oxygenation in meso-tetraphenylporphine in carbon tetrachloride, was epoxidised to protect the Δ^8.9-double bond. The epoxy-peroxide (5) thus obtained smoothly underwent ferrous sulphate-catalysed rearrangement to the epoxy-lactol (6a), which on oxidation with Sarett reagent led to the epoxy-lactone (6b). Deoxygenation of (6b) with pentacarbonyliron in N,N-dimethylacetamide afforded the α,β-unsaturated lactone (1a).