PROCEDURES FOR OBTAINING NORAMBREINOLIDE ENANTIOMERICALLY PURE AND RACEMIC.

摘要

Procedures for obtaining enantiomerically pure and racemic norambreinolide. The present invention consists of (a) a method of synthesizing (+) - norambreinolide (1), known tobacco flavoring, food additive and synthetic precursor of the perfume fixative (-) - Ambrox, from endareol oxide (2) ), and (b) in a synthesis procedure of (+ -) - norambreinolide (1) from farnesyl ketone (3). Both procedures are based on the direct conversion of a cyclic ether enol into a {ga} -lactonic ring by reaction with molecular oxygen, an oxygen acceptor and in the presence or absence of catalyst. Obtaining (+) - 1 from 2 is carried out in a single stage (85%), and (+ -) - 1 from 3 in two, consisting of stereospecific cyclization of 3 with acid chlorosulfonic acid and conversion of (+ -) - 2 (together with its epimer in C-9; 1.8: 1) by reaction with oxygen in (+ -) - 1 (together with its epimer in C-9; 1.8 : 1), with an overall yield of 70%.