Direct asymmetric aldol reactions in aqueous media catalyzed by a β-cyclodextrin–proline conjugate with a urea linker

[Display omitted] Covalently attaching proline to β-CD through a urea linkage resulted in the synthesis of a water-soluble chiral organocatalyst 1 in high yield. Catalytic asymmetric aldol condensations between aldehydes and acetone were carried out under water-containing conditions by using 5mol% of 1 as catalyst, and moderate to high yields and enantioselectivities (up to 99% ee) were achieved for a broad range of aldehydes. Substrate selectivity was also tested. Recycling experiments were performed to confirm good recyclability and reusability of the catalyst.