Synthesis of [2.2]paracyclophane-based bidentate oxazoline-carbene ligands for the asymmetric 1,2-silylation of N-tosylaldimines

A series of novel oxazoline-substituted imidazolium salts with planar and central chirality has been successfully synthesized and applied to copper-catalyzed enantioselective 1,2-silylation of N-tosylaldimines. The oxazoline-carbene copper complex generated in situ by the reaction of the oxazoline-substituted imidazolium and Cu2O demonstrated an exceptionally high catalytic activity in the asymmetric 1,2-silylation of N-tosylaldimines, affording chiral alpha-amino silanes with excellent yields and enantioselectivities. (C) 2017 Elsevier Ltd. All rights reserved.