Studies of Australian Soft Corals. XLVII. New Halogenated Briaran Diterpenes From a Briareum Species (Octocorallia, Gorgonacea)

Abstract

Two new halogenated briaran diterpenes (3) and (4) are reported from a Briareumspecies of soft corals from waters off Darwin, N.T. Their structures were determined by high-field n.m.r. spectroscopy including 2-D 13C-¹ H-correlation experiments and COSY-45 experiments, and stereochemical features were delineated by n.0.e. difference spectroscopy. The new metabolites are (1R*,2S*,4S*,6S*,7R',8R*,9S*,10S*,11Z,14S*,17S*)-14-acetoxy-6-chloro-4,8-epoxy-9,17-dihydroxy-2-propiony10xybriar5(16,11-dien-18-one (3) and (1R*,2R*,3S*,6S*,7R*,8R*,9S*,10S*,11R*,13Z)-3,9-diacetoxy-6-chloro-8-hydroxy-2-propionyloxybriara-5(16),13-diene-12,18-dione (4). The isolation of briaran diterpenes from this specimen supports its inclusion in the genus Briareum.