Azomethine ylide cycloaddition/reductive heterocyclization approach to oxindole alkaloids: asymmetric synthesis of (-)-horsfiline.
The intermolecular [3 + 2] annulation of azomethine ylides with 2(2-nitrophenyl)acrylate dienophiles followed by reductive heterocyclization affords the spiro(indole-pyrrolidine) ring system. Hence, this enable us to accomplish a concise and highly enantioselective synthesis of (-)-horsfiline 1, based on chiral auxiliary-directed pi-face discrimination in the 1,3-dipolar cycloaddition of (1S,2R)-2-phenyl-1-cyclohexyl ester 4f with N-methylazomethine ylide.
Cravotto
G
G
Dipartimento di Scienza e Tecnologia del Farmaco, Università di Torino, via Giuria 9, 0125 Torino, Italy.
Giovenzana
G B
GB
Pilati
T
T
Sisti
M
M
Palmisano
G
G
D000470:Alkaloids / Q000138:chemical synthesis*; D018360:Crystallography, X-Ray; D003500:Cyclization; D007202:Indicators and Reagents; D008968:Molecular Conformation; D010084:Oxidation-Reduction; D010946:Plants, Medicinal / Q000737:chemistry*; D013141:Spiro Compounds / Q000138:chemical synthesis*; D013237:Stereoisomerism
D000470:Alkaloids; D007202:Indicators and Reagents; D013141:Spiro Compounds; C443722:horsfiline