Asymmetric ring-opening of epoxides on chiral Co(Salen) catalyst synthesized in SBA-16 through the “ship in a bottle” strategy

Abstract

Chiral Co(Salen) complex was synthesized in the mesoporous cage of SBA-16 through the “ship in a bottle” method. The pore entrance size of SBA-16 was precisely tailored by varying the autoclaving time and silylation with phenyltrimethoxysilane to trap Co(Salen) complex in the cage of SBA-16. Chiral Co(Salen) trapped in SBA-16 shows enantioselectivity (up to 87–96% ee) as high as that of the homogeneous catalyst for the asymmetric ring opening of terminal epoxides and can be recycled at least 10 times with no apparent loss of activity. The activity for the catalyst trapped inside SBA-16 can be significantly increased when the surface is modified with organic groups. This work extends the “ship in a bottle” synthesis from microporous materials to mesoporous cage-like materials and develops an effective strategy to trap metal complex catalyst with large molecular size into the nanopores or cavities of mesoporous materials.