(2S,5S)-Pyrrolidine-2,5-dicarboxylic acid, an efficient chiral organocatalyst for direct aldol reactions

Enantioselective aldol reaction of ketones with aldehydes catalyzed by (2S,5S)-pyrrolidine-2,5-dicarboxylic acid in the presence of an equal molar amount of Et3N was described. By using the new chiral organocatalyst, the direct aldol condensation products were obtained in reasonable yields and up to 90% ee.

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(4R)-4-Hydroxy-4-(4-nitrophenyl)-2-butoneC10H11NO4Ee = 65%[α]D20=+35.0 (c 0.2, CHCl3)Source of chirality: asymmetric aldol reactionAbsolute configuration: 4R