Studies of Australian Soft Corals. XLVIII. New Briaran Diterpenoids From the Gorgonian Coral Junceela gemmacea

Abstract

The structures of three new briaran based diterpenes are reported from the gorgonian coral Junceela gemmacea. Their structures were deduced on the basis of extensive one- and two-dimensional high-field n.m.r. experiments. The metabolites were (1R,2R,5Z,7R,8S,9R,10R,11R,14R,17S)-2,14-diacetoxy-8,17:11,20-bisepoxy-9-hydroxybriar-5-en-18-one (3), (1R,2R,5Z,7R,8S,9R,10R,11Z,14R,17S)-2,14-diacetoxy-8,17-epoxy-9-hydroxybriara-5,11-dien-18-one (4), and 1R,2R,5Z,7R,8S,9R,10R,12R,14R,17S)-2,14-diacetoxy-8,17-epoxy- 9,12-dihydroxybriara-5,11(20)-dien-18-one (5). The compounds are closely related to recently reported metabolites from Briareum species of soft corals.