Chitosan-supported cinchonine as an efficient organocatalyst for direct asymmetric aldol reaction in water

Chitosan-supported succinic anhydride-cinchonine (CTS-SA-CN) was synthesized via a two-step route with succinic anhydride as the linker. The catalyst was used to promote the direct asymmetric aldol reaction between cyclohexanone and a variety of aromatic aldehydes in aqueous medium. Aldol adducts were obtained in excellent yields (up to 99%) and good enantioselectivities (up to 96% ee). The CTS-SA-CN catalyst was successfully recycled simply by filtration after use, and was reused 5 times without any significant loss of activity.

Graphical AbstractChitosan-supported succinic anhydride-cinchonine was conveniently synthesized. The organocatalyst catalyzed the direct asymmetric aldol reaction with excellent yields and good enantioselectivity in aqueous medium.Figure optionsDownload full-size imageDownload as PowerPoint slide