Catalytic Performance of Silica Supported Cinchona Alkaloids as Heterogeneous Catalysts for Asymmetric Michael Reaction

Abstract

Silica supported cinchona alkaloids were prepared by thio-ene coupled reaction so as to develop novel highly efficient heterogeneous organocatalysts for asymmetric Michael reaction. As-prepared supported cinchona alkaloids were used as heterogeneous catalysts to catalyze the asymmetric Michael reaction between 1,3-dicarbonyl compounds and N-benzylmaleimide, and their catalytic performance was evaluated. It was found that, when toluene is employed as the solvent, silica supported cinchona alkaloid catalysts can catalyze the aforementioned Michael reaction with medium enantiomeric excess (ee) values (up to 87 %) and significant diastereo ratio (dr) values (up to 96:4). In the meantime, they can be recovered and reused for at least five cycles while their stereo-selectivity remains almost unchanged. This means that the title catalysts could be highly efficient organocatalysts for the investigated Michael reaction.