Studies of Australian Soft Corals. XII. Further Cembranolide Diterpenes from Lobophytum crassospiculatum and a Correction of a Previous Stereochemical Assignment

Abstract

Three new cembranolide diterpenes from Lobophytum crassospiculatum are reported. The structure of one of these was deduced from spectroscopic data and chemical degradation, then confirmed as (E,E,E)-6,10,14-trimethyl-3-methylene-trans-3a,4,7,8,11,12,15,15a- octahydrocyclotetradeca[b]furan-2(3H)-one (3), by synthesis from the previously reported (2). The other two diterpenes,(4) and (5), are shown to be the epimeric 15-acetoxyl derivatives of (2).