Novel enantiocontrol system with aminoacyl derivatives of glucoside as enamine-based organocatalysts for aldol reaction in aqueous media

Introduction of carbohydrate auxiliary into enanine-based catalyst provided a novel enantiocontrol for aqueous aldol reaction. Methyl 2-(L-prolyl)amido-2-deoxy-alpha-D-glucopyranosides led to the enantiocontrol as parent amino acids did in the reaction of acetone with 4-nitrobenzaldehyde, and provided R-aldol in an improved efficiency compared with that of L-proline in aqueous media. The enantioreversal control of that with parent amino acid was observed in the reaction with methyl 2-(L-tert-leucyloxy)-alpha-D-glucopyranoside, which provided S-aldol predominantly in moderate efficiency. The novel enantiocontrol system was proposed to occur as a result of the generation of the transition state through the reaction of enamine with hydroxyl group on glucoside auxiliary. (c) 2007 Elsevier Ltd. All rights reserved.