Mesoporous helical silica immobilizing manganese(III)-salen complex for oxidative kinetic resolution of secondary alcohols

Abstract

Mesoporous helical silica were prepared by doping of chiral diammoniumcyclohexane mono-tartrate salt in a sol–gel process, then functionalized to immobilize Mn(III)-salen complexes for oxidative kinetic resolution of secondary alcohols. Characterization revealed the doped silica significantly changed chiral recognition, porosity and hydrolysis resistance compared with blank-doped one. In catalysis, helical silica-supported Mn(III)-salen showed satisfactory conversion, enantioselectivity and selectivity factor, while major configuration of resolution products was determined by configuration of silica supports more than Mn(III)-salen. Furthermore, linkage of (S,S)-diammonium salt-doped silica with Mn(III)-(R,R)salen showed better enantioselectivity than other combinations. At last, in addition to iodobenzene diacetate, hydrogen peroxide (30 wt%) was another effective terminal oxidant. This work not only provided new chiral silica materials, but also explored their application in catalytic resolution.