Direct Asymmetric Aldol Reactions of Glycine Schiff Base with Aldehydes Catalyzed by Chiral Quaternary Ammonium Salts

Abstract

A practical and environmentally benign chemical process for the synthesis of optically active β-hydroxy-α-amino acids involves the reaction of an aldehyde, glycine Schiff base 2, in the presence of catalytic N-spiro chiral quaternary ammonium bromide 1. The cross-aldol product 3 is obtained with excellent stereochemical control (see scheme; a) (R,R)-1 (2 mol %), toluene/aqueous NaOH (1 %), 0° C, 2 h; b) HCl (1 n)/THF). Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2002/z19746_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.