Formal Syntheses of (−)-Lepadiformines A, C, and (−)-Fasicularin

Marine tricyclic alkaloids lepadiformine and fasicularin, with a unique perhydropyrrolo[2,1-j]quinoline or perhydropyrido[2,1-j]quinoline framework, were synthesized starting from the B ring of the tricyclic system. This approach includes a highly stereocontrolled di-allylation of a cyclic enaminoester and subsequent ring-closing metathesis to construct the A/B ring system, which was transformed into key lactams 32 and 33, and amino alcohol 37. Thus, we achieved formal syntheses of (-)-lepadiformines A, C, and (-)-fasicularin in a divergent manner.