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 β ‐amino alcohols.