Enantioselective Synthesis of 2-Aryl-3,3-Disubstituted Indolines from 3H-Indoles via Deracemization

An enantioselective synthesis of 2-aryl 3,3-disubstituted 3H-indoles has been successfully developed via a deracemization process involving borane-catalyzed hydrogenation and chiral phosphoric-acid-catalyzed asymmetric transfer hydrogenation. A variety of 3H-indoles were effective substrates to afford the desired indolines in 86–95% yields with 45–92% ee’s.