Silica-Supported Pyrrolidine-Triazole, an Insoluble, Recyclable Organocatalyst for the Enantioselective Michael Addition of Ketones to Nitroalkenes.

A highly efficient, silica-supported organocatalyst for the Michael addition of ketones to nitroalkenes is successfully developed. A 1,2,3-triazole ring, constructed via a click 1,3-dipolar cycloaddition, plays a dual role of grafting the chiral pyrrolidine onto the silica surface and of providing a structural element complementary to the pyrrolidine. The supported catalyst demonstrated high activity and enantioselectivity; furthermore, it can be readily reused four times without significant loss of catalytic activity.