Total Syntheses and Biological Investigations of Tamandarins A and B and Tamandarin A Analogs

Tamandarins A (1) and B (2), two natural products similar in structure to didemnin B (3), were
recently isolated from a Brazilian marine ascidian of the family Didemnidae. The cytotoxicity of 1 was reported
to be somewhat more potent in vitro than that of 3 against various human cancer cell lines. The present account
describes the first total syntheses of 1 and 2, and the syntheses of tamandarin A side chain analogues. The
cytotoxicity data for these compounds show that the side chain modifications exhibit a parallel effect for both
didemnins and tamandarins. This observation supports tamandarins' role as didemnins' mimic.