Imidazolium-modified poly(l-leucine) catalyst: an efficient and recoverable catalyst for Juliá-Colonna reactions

A novel, easily recyclable imidazolium-modified poly(amino acid) catalyst was prepared. This catalyst exhibits high activity for the asymmetric epoxidation of α,β-unsaturated ketones without any pre-activation. The enantioselectivity was up to 99% ee for epoxidation of p-methoxychalcone. Compared to classical Juliá-Colonna catalysts, this insoluble, powdery catalyst can dramatically reduce the reaction time and can be easily recycled by a simple filtration after the reaction. More importantly, the recycled catalyst has been successfully reused for seven cycles without deterioration in catalytic efficiency.