Total Synthesis of Incarnatapeptins A and B

Abstract The first total synthesis of incarnatapeptins A and B, two novel marine natural products, was accomplished from readily available ( S )‐1‐benzyloxycarbonylhexahydropyridazine‐3‐carboxylic acid. This route, whose longest linear sequence was 12 steps, provided the incarnatapeptins A and B in yields of 26.5 % and 19.7 %, respectively, and enabled the structure and stereochemistry of both natural products to be unambiguously confirmed. Highlights of our synthesis include the photoredox‐mediated decarboxylative 1,4‐addition reaction and a novel and practical N ‐acylation paradigm promoted by silver carbonate. The unusual facile atropisomerism of some linear peptidic intermediates was also observed by TLC analysis in the course of this work.