New halogenated sesquiterpenes from South African specimens of the circumtropical sea hare Aplysia dactylomela

An examination of the digestive gland extracts from two color variants of t he circumtropical sea hare Aplysia dactylomela, collected off the Eastern C ape coast of South Africa, yielded four new halogenated sesquiterpenes: alg oane (1), 1-deacetoxyalgoane (2), 1-deacetoxy-8-deoxyalgoane (3), and ibhay inol (4). The known sesquiterpenes, nidificene (5) and prepacifenol epoxide (6), were also isolated from the A. dactylomela extracts. Standard spectro scopic techniques were used to determine the structures of compounds 1-6, w ith a single-crystal X-ray diffraction experiment establishing the structur e of 1 and providing the absolute stereochemistry of this compound.