Resin-immobilized pyrrolidine-based chiral organocatalysts for asymmetric Michael additions of ketones and aldehydes to nitroolefins

Abstract

Based on the electrostatic adsorption between acidic resins and organocatalysts, a series of resin-supported chiral organocatalysts were designed and synthesized. They were evaluated for the asymmetric Michael addition of cyclohexanone with nitrostyrene, in which, catalyst 3 (Fig. 1) exhibited the best catalytic performance. This reaction proceeded under catalyst 3 smoothly at room temperature without any solvent or additive and could give product with high yield (95%) and good stereoselectivity (90% ee, 98 : 2 dr). Encouragingly, catalyst 3 was easily isolated and reused for 16 consecutive runs without obvious loss of reaction enantioselectivity. Furthermore, it was successfully applied to catalyze the reactions of a series of ketones and aldehydes with nitroolefins.