Highly Enantioselective Synthesis of Chiral 3-Substituted Indolines by Catalytic Asymmetric Hydrogenation of Indoles

Abstract
N-Tosyl 3-substituted indoles were hydrogenated with high enantioselectivities (95−98% ee) by use of a trans-chelating chiral bisphosphine, (S,S)-(R,R)-PhTRAP ligand. The chiral catalyst, which was generated in situ from [Rh(nbd)2]SbF6, PhTRAP, and Cs2CO3, is useful for enantioselectively synthesizing a range of diverse optically active indolines possessing a chiral carbon at the 3-position.