Asymmetric ring opening of meso-epoxides with aromatic amines catalyzed by a new proline-based N,N′-dioxide-indium tris(triflate) complex

The catalytic asymmetric ring opening of meso-epoxides with aromatic amines was achieved using a new proline-based N,N'-dioxide-indium tris(triflate) complex in high yields (up to 99%) with excellent enantioselectivities (up to 99% ee) under mild conditions. The coordination ability of N,N'-dioxide 1c was investigated by X-ray and NMR analysis. A plausible seven-coordinate transition state model was proposed. The chiral N,N'-dioxides surveyed were synthesized from proline through only three conventional steps. The procedure could be run on a gram-scale without any loss of enantioselectivity. This protocol provides a highly practical and useful tool for the bulky preparation of optically pure beta-amino alcohols.