l-Proline amide-catalyzed direct asymmetric aldol reaction of aldehydes with chloroacetone

l-Proline amides were evaluated for catalyzing the direct aldol reaction of 4-nitrobenzaldehyde with chloroacetone. The presence of 30 mol% (S)-pyrrolidine-2-carboxylic acid (2,4,6-trimethyl-phenyl)-amide catalyzed the direct aldol reactions of a range of aldehydes with chloroacetone to give anti-α-chloro-β-hydroxyketones with high regio-, diastereo- and enantioselectivity.