Asymmetric C(sp3)-H/C(Ar) coupling reactions. Highly enantio-enriched indolines via regiodivergent reaction of a racemic mixture

Abstract

N-Aryl, N-branched alkyl carbamates react with in situ generated chiral Pd-NHC catalysts by coupling a Pd-Ar moiety with an aliphatic C–H bond at high temperature to give enantioenriched 2-substituted and 2,3-disubstituted indolines. Prochiral precursors give single products with very high asymmetric induction. Chiral racemic precursors react in a regiodivergent reaction of a racemic mixture to yield enantioenriched indolines resulting from either methyl C–H activation or asymmetric methylene C–H activation. In favorable cases this can result in a complete separation of an enatiomeric mixture into two different highly enantioenriched indolines.