9-Thiourea Cinchona alkaloid supported on mesoporous silica as a highly enantioselective, recyclable heterogeneous asymmetric catalyst

A readily recycled and regenerated heterogeneous catalyst of 9-thiourea epi-quinine supported on mesoporous silica exhibits enhanced enantioselectivity (up to 99.2%) in the asymmetric Friedel–Crafts reaction of imines with indoles.