Direct Organocatalytic Asymmetric Aldol leactions of a-Amino Aldehydes:Expedient Syntheses of Highly Enantiomerically Enriched anti-beta-Hydroxy-alpha-amino Acids

摘要

A simple and efficient method for the synthesis of highly enantiomerically enriched beta-hydroxy-alpha-amino acid derivatives has been developed.Direct asymmetric aldol reactions of a glycine aldehyde(aminoacetaldehyde)derivative have been performed under organocatalysis using L-proline or(S)-5-pyrrolidine-2-yl-1H-tetrazole.The reactions afforded anti-beta-hydroxy-a-amino aldehydes in good yield with high diastereoselectivity(dr up to >100:1)and high enantioselectivity(up to >99.5% ee),which were easily transformed into beta-hydroxy-alpha-amino acid derivatives.