Novel sponge-derived amino acids. 5. Structures, stereochemistry, and synthesis of several new heterocycles

This paper reports the complete amino acid chemistry of an undescribed Jaspidae sponge, collected annually in the Benga lagoon of the Fiji Islands during the period from 1984 to 1987. Five different amino acid types are represented among its constituents and they include the bengamides (six compounds), isobengamide E, bengazoles (A and B), a diketopiperazine cyclo(L-trans-(4-hydroxyprolinyl)-L-phenylalanine), and N-acetyl-L-phenylalanine methyl ester. The structures and stereochemical features of the bengamides were established by relying on analogies to bengamides A and B, along with insights gained by extensive spectroscopic and chemical degradation of isobengamide E and bengamide E.