Enantioselective total syntheses of nankakurines A and B: confirmation of structure and establishment of absolute configuration.
Total syntheses of (+)-nankakurine A (2) and (+)-nankakurine B (3) were accomplished by a sequence that employs an intramolecular dipolar cycloaddition of an azomethine imine intermediate to form the azatricyclic moiety and establish the relative configuration of the spiropiperidine ring. These syntheses, together with the synthesis of the originally purported structure 1 of nankakurine A, rigorously establish the relative and absolute configuration of these structurally unusual Lycopodium alkaloids. The syntheses are sufficiently concise that gram quantities of (+)-nankakurine A (2) and (+)-nankakurine B (3) will be available for further biological studies.
Nilsson
Bradley L
BL
Department of Chemistry, University of California, Irvine, 1102 Natural Sciences II, Irvine, California 92697-2025, USA.
Overman
Larry E
LE
Read de Alaniz
Javier
J
Rohde
Jason M
JM
D000470:Alkaloids / Q000138:chemical synthesis*; D001372:Aza Compounds / Q000737:chemistry; D001391:Azo Compounds / Q000737:chemistry; D006572:Heterocyclic Compounds, Bridged-Ring / Q000138:chemical synthesis*; D007097:Imines / Q000737:chemistry; D032502:Lycopodium / Q000737:chemistry*; D008956:Models, Chemical; D010880:Piperidines / Q000737:chemistry; D013237:Stereoisomerism; D013882:Thiosemicarbazones / Q000737:chemistry
D000470:Alkaloids; D001372:Aza Compounds; D001391:Azo Compounds; D006572:Heterocyclic Compounds, Bridged-Ring; D007097:Imines; D010880:Piperidines; D013882:Thiosemicarbazones; C512188:azomethine; C504053:nankakurine A; C032727:piperidine