Total synthesis of (+)-nankakurines A and B and (±)-5-epi-nankakurine A.

ABSTRACT: The first total syntheses of the Lycopodium alkaloids (+)-nankakurine A (2), (+)-nankakurine B (3), and the originally purported structure 1 of nankakurine A were accomplished. The syntheses of 2 and 3 feature a demanding intramolecular azomethine imine cycloaddition as the key step for generating the octahydro-3,5-ethanoquinoline moiety and installing the correct relative configuration at the spiropiperidine ring juncture. The cyclization precursor was prepared from octahydronaphthalene ketone 50, which was assembled from enone (+)-9 and diene 48 by a cationic Diels-Alder reaction. The Diels-Alder reactants were synthesized from 5-hexyn-1-ol (16) and (+)-pulegone (49), respectively. The tetracyclic ring system of 1 was generated using an unprecedented nitrogen-terminated aza-Prins cycliza

SUBMITTER: Altman RA 

PROVIDER: S-EPMC3038189 | biostudies-literature | 2010 Nov

REPOSITORIES: biostudies-literature