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Two isomeric 7,8-epoxycembra-3,11,15-trien-16,2-olides have been isolated from different species of the soft coral genus Efflatounaria. The structure of each was deduced spectroscopically , and the relative stereochemistry of one was determined by X-ray crystallography. The absolute stereochemistry of each cembranolide was obtained by chemical correlation with known compounds.

5-Nonylpyrrole-2-carbaldehyde has been isolated from a soft coral-sponge association. The structure was determined spectroscopically and confirmed by synthesis.

The isolation of two new cembranoid diterpenes, (14S,1E,3E,7E)-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 (3S,4S,1lS,12S,1E,7E)-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(11S,12S,1 E,3E,7E)-11,12-epoxycembra-1,3,7-triene. Further examples of stereospecific epoxidationsare reported.

Three new diterpenes have been isolated from soft corals of the genus Efflatounaria (Coelenterata, Octocorallia, Alcyonacea, Xeniidae). The structure of the first compound (4) was elucidated on the basis of high-field 1H n.m.r. spectroscopy while that of the second metabolite (5) was determined by single-crystal X-ray analysis. The third diterpene (6) was structurally related to (5), and its structure was confirmed by chemical transformation. All three diterpenes can be derived from xenicin-type precursors, by cleavage and recyclization.

The soft coral Lemnalia cervicornis May 1898 has afforded 13 novel sesquiterpenoid metabolites. The majority were derivatives of calamenen-7-ol and the structures were deduced by 1H and 13C n.m.r . spectroscopy. Absolute stereochemistry of compounds (3)-(13) was determined by chemical correlation with 7-hydroxycalamenen-3-one (3) for which an X-ray structure determination of its 7-p-bromobenzoyl derivative is reported. Two minor metabolites (15) and (16) were not aromatic, but were structurally related to the algal metabolite zonarene (21) for which absolute stereochemistry was available.

A novel trisnorsesquiterpene (1,4-dimethyl-2,3,3a,4,5,6-hexahydroazulene) and an optical antipode of the known sesquiterpene cubebol have been isolated from the soft coral Cespitularia species. The pigment in a small blue Alcyonium species has been identified as guaiazulene.