Studies of Australian Soft Corals .XXXVI. The Isolation and Structure Determination of 11 Calamenene-Based Sesquiterpenes From Lemnalia-Cervicornis (Coelenterata, Octocorallia, Alcyonacea)

Abstract

The soft coral Lemnalia cervicornis May 1898 has afforded 13 novel sesquiterpenoid metabolites. The majority were derivatives of calamenen-7-ol and the structures were deduced by ¹H and ¹³C n.m.r . spectroscopy. Absolute stereochemistry of compounds (3)-(13) was determined by chemical correlation with 7-hydroxycalamenen-3-one (3) for which an X-ray structure determination of its 7-p-bromobenzoyl derivative is reported. Two minor metabolites (15) and (16) were not aromatic, but were structurally related to the algal metabolite zonarene (21) for which absolute stereochemistry was available.