Studies of Australian soft corals. XXXIII. New cembranoid diterpenes from a Lobophytum species

The isolation of two new cembranoid diterpenes, (14 S ,1 E ,3 E ,7 E )-14-acetoxy-11,12-epoxycembra-1,3,7-triene and the corresponding 14-alcohol, is reported from the soft coral Lobophytum sp. A minor component in the extract (3 S ,4 S ,1l S ,12 S ,1 E ,7 E )-3,4:11,12-bisepoxycembra-1,7-diene was identified but may be artefactual as it is the sole product of the aerial oxidation of the major metabolite(11 S ,12 S ,1 E ,3 E ,7 E )-11,12-epoxycembra-1,3,7-triene. Further examples of stereospecific epoxidationsare reported.