Supported manganese catalysts achieve highly efficient C–H bond oxidation and olefin epoxidation

Abstract

Enantioselective oxidation reactions represent potent methodologies for creating chiral C–O bonds. Although extensive research and development efforts have been conducted on chiral homogeneous catalysts, their exploration remains challenging and underdeveloped. It is important to note that some catalysts may exhibit a lower catalytic efficiency or lose their high enantioselectivity when supported on a solid surface. Therefore, we propose a strategy wherein the support not only serves as a scaffold but also acts as a side arm (bulky group) to modify the catalytic monomer, thereby enhancing the enantioselectivity. Herein, we reported a porous polymer-supported chiral heterogeneous manganese catalyst that exhibited superior catalytic performance compared with that of the catalytic monomer without bulky group modification in catalyzing hydroxylation (up to 99% ee, >95 : 5 dr, 74% yield) and ketonization (chiral spirocyclic β,β′-diketones, up to 97% ee, 87% yield) of benzyl C–H bonds and epoxidation (up to 99% ee, 97% yield) of α,β-unsaturated olefins. Various pharmaceutical intermediates and natural products were successfully obtained. Additionally, we demonstrated its continuous flow gram-scale conversion capability by conducting a 900 min reaction of chalcone (2.06 g product, 99% ee, 92% yield) without observing any significant decrease in the catalytic activity.