Abstract
Total syntheses of (±)-lepadiformine B and C are presented. The key theme in our approach is the stereodivergent synthesis of both cis- and trans- N-acetyl-2-alkyl-8a-cyanodecahydroquinoline, which are effectively prepared through deprotection-initiated alkylative/reductive cyclization of sterically well-defined α-aminonitriles bearing a masked carbonyl group. After the Dieckmann-type condensation to a tricyclic lactam, lepadiformine B and its analogues can be achieved through the Ir-catalyzed reductive cyanation and subsequent hydrolysis, reduction, and Bruylants reactions.