Organic letters

Catalytic asymmetric protonation of lithium enolates using amino acid derivatives as chiral proton sources

K Mitsuhashi, R Ito, T Arai, A Yanagisawa

Index: Mitsuhashi, Kaori; Ito, Rie; Arai, Takayoshi; Yanagisawa, Akira Organic Letters, 2006 , vol. 8, # 8 p. 1721 - 1724

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Citation Number: 35

Abstract

Asymmetric protonation of lithium enolates was examined using commercially available amino acid derivatives as chiral proton sources. Among the amino acid derivatives tested, N β-l-aspartyl-l-phenylalanine methyl ester was found to cause significant asymmetric induction in the protonation of lithium enolates. The enantiomeric excess (up to 88% ee) of the products obtained in the presence of a catalytic amount of the chiral proton source was ...