Studies of Australian soft corals. XXVIII. The structure determination of two new diterpenes from the genus Xenia (Alcyonacea)

Abstract

The isolation of '9-deacetoxyxenicin' [systematic name: (1R*,4aS*,7E,11aS*,1'R*,2'R*)-1-acetoxy-4-(1',2'-diacetoxy-4'-methylpent-3'-enyl)-7-methy1-11-methylene-1,4a,5,6,9,10,11,11a-octahydrocyclonona[c]pyran] (2) from Xenia crassa and a further cyclized diterpene (6) from Xenia viridis are described. The structure of (2) was derived from n.m.r. spectroscopic comparison with xenicin (1), whilst the structure of (6) was determined by a single-crystal X-ray analysis when spectroscopy failed to afford an unambiguous structure.