Conversion of a cyclic alpha,beta-unsaturated ketone into a tertiary dienyl hydroperoxide: Application to the first hemisynthesis of 15-hydroperoxyabietic acid

The first hemisynthesis of 15-hydroperoxyabietic acid, a major contact alle rgen among the oxidation products of colophony, is reported. The key step i ncludes a new approach to easily obtain a dienyl tertiary hydroperoxide fro m a cyclic alpha,beta -unsaturated ketone. The procedure is based on the fo rmation of a bromodiene using a Vilsmeier's reagent, followed by a halogen/ metal exchange and alkylation with acetone, to afford the dienyl alcohol pr ecursor of the hydroperoxide.