Organocatalysis of asymmetric aldol reaction in water: comparison of catalytic properties of (S)-valine and (S)-proline amides

Abstract

(S)-Valine amides containing (S)- or (R)-α-phenylethyl substituents at N1 atom efficiently catalyze asymmetric aldol reactions between cyclic (heterocyclic) ketones and aromatic aldehydes in water, predominantly giving rise to the aldol anti-diastereomers in high yields (up to 98%) and enantiomeric excess (up to 94%).