Three new diterpenes from a soft coral Nephthea species

Abstract

Two new cembranoid diterpenes and a non-cembranoid diterpene have been isolated from a soft coral Nephthea species along with two previously reported diterpenes (1) and (9). The structures were determined from spectral data and chemical degradation sequences. The compounds were identified as (1E,3E,7E,11E,13S)-cembra-1,3,7,1l-tetraen-13-ol (6), (lE,3E,7E,llE,13S)-cembra- 1,3,7,11-tetraen-13-yl acetate (7) and 2-[(2'R*,4a'S*,8a'R*)-4a',8'-dimethyl-l',2',3',4,4a',5',6',8a'- octahydronaphthalen-2'-yl]-5,6-epoxy-6-methyhept-1-ene(8).