Readily accessible chiral frustrated Lewis pair catalysts: Asymmetric hydrosilylation of imines and quinolines

Summary

Although frustrated Lewis pair (FLP) chemistry has found numerous applications, FLPs are best known for their utility in catalytic, metal-free reductions. In the last decade, FLP catalysts have been applied to a wide range of substrates, and a few efficient chiral FLP catalysts achieving highly stereoselective reductions have emerged. Nonetheless, access to such metal-free catalysts typically involves multi-step and synthetically challenging processes, thus precluding wider use. In this work, we report facile access to a family of chiral FLP catalysts via the hydroboration of derivatives of a commercially available steroid precursor. These catalysts are shown to be highly selective catalysts for the enantioselective hydrosilylation of imines and quinolines, producing chiral amines and tetrahydroquinolines.