Total synthesis of (+)-nankakurines A and B and (±)-5-epi-nankakurine A.
J Org Chem
; 75(22): 7519-34, 2010 Nov 19.
Article
en En
| MEDLINE
| ID: mdl-20958075
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 cyclization cascade. The enantioselective total syntheses of (+)-nankakurine A (2) and (+)-nankakurine B (3) establish the relative and absolute configuration of these alkaloids and are sufficiently concise that substantial quantities of 2 and 3 were prepared for biological studies. (+)-Nankakurine A and (+)-nankakurine B showed no effect on neurite outgrowth in rat hippocampal H-19 cells over a concentration range of 0.3-10 µM.
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Compuestos Heterocíclicos de Anillo en Puente
/
Lycopodium
/
Alcaloides
Límite:
Animals
Idioma:
En
Revista:
J Org Chem
Año:
2010
Tipo del documento:
Article
País de afiliación:
Estados Unidos