▎ 摘　　要

Pristine L-proline was non-covalently loaded on the graphene oxide (GO) sheet in a simple route by mixing them in aqueous solution. Technologies of characterization well suggested that L-proline was efficiently loaded on the two sides and edge of the GO sheet through hydrogen-bonding or/and ionic interaction, giving the excellent L-proline/GO hybrid catalyst for the direct asymmetric aldol reaction. The unique multilayered structure of the GO carrier with sufficient interlayer space favored reagents' diffusion toward L-proline chiral moiety and therefore resulted in the high catalytic efficiency of the heterogeneous L-proline. Excellent yield (96%) with high enantiomeric excess (79% ee) was obtained in the direct aldol reaction of 2-nitrobenzaldehyde with acetone catalyzed by L-proline/GO hybrid, which was comparable to that observed in the reactions promoted by L-proline itself. Furthermore, the L-proline/GO hybrid used as a heterogeneous catalyst could be easily recovered and recycled for seven times without significant loss of the reactivity. (C) 2012 Elsevier Inc. All rights reserved.