Synthesis of Sabina δ-Lactones and Sabina δ-Lactams from (+)-Sabinene

Abstract

Two sabina δ-lactones (3 and 4) were obtained in a two-step synthesis from (+)-sabinene (1). The oxidation of (+)-sabinene (1) with potassium permanganate and sodium periodate to (–)-sabina ketone (2) was the first step. In the second step, the ketone obtained was subjected to chemical and microbial Baeyer–Villiger oxidation. Chemical Baeyer–Villiger oxidation of this ketone afforded two δ-lactones 3 and 4 whereas microbial Baeyer–Villiger oxidation afforded only ‘abnormal’ δ-lactone 4. (–)-Sabina ketone was also the starting material for the synthesis of new δ-lactams (7 and 8). They were obtained by Beckmann rearrangement of sabina ketone oximes 5a and 5b. An attempt to separate (–)-sabina ketone oximes 5a and 5b is also presented.