Synthesis of <i>d</i>,<i>l</i>-Norlabdane Oxide and Related Odorants: An Intramolecular Radical Approach

Abstract

A cascade radical approach to d,l-norlabdane oxide and related odorants is reported. Oxidative radical cyclization of polyene 4 with Mn(III) and Cu(II) afforded exclusively bicycle 3, which upon acid treatment gave tricycle 2 possessing the norlabdane oxide skeleton with a modified A-ring system. Tricycle 2 was ultimately converted to d,l-norlabdane oxide 1 and to several new A-ring labdane oxides as potential odorants.