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Phase-Transfer Catalytic One-Pot Approach to Alkaloid Core Structures
Y.-G. Wang, T. Kumano, T. Kano, K. Maruoka*
Kyoto University, Japan
25 May 2009 (online)
The authors present an elegant and highly enantioselective synthesis of pyrrolidine, hexahydropyrrolizine, and octahydroindolizine core structures. Key step is the asymmetric conjugate addition of N-(diphenylmethylene)-glycine ester to α,β-enones catalyzed by chiral phase-transfer catalyst 1. Intramolecular reduc-tive amination and subsequent in situ acetal hydrolysis-reductive amination using Hantzsch ester 2 and trifluoroacetic acid gives access to alkaloid core structures in a simple one-pot procedure.