Total synthesis of the marine sponge pigment fascaplysin

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.