Total synthesis of the marine sponge pigment fascaplysin

Abstract

Fascaplysin ( 1), an antimicrobial and cytotoxic red pigment from the marine sponge Fascaplysinopsis sp., has been synthesized in seven steps from indole (65% yield). The pivotal intermediate in the synthesis is diindole 3 which is induced to undergo acid-catalyzed cyclization and dehydrogenation to afford the desired pentacycle 2 in > 90% yield. Peracid oxidation of 2 yields fascaplysin.