Palladium-catalyzed Enantioselective Cacchi Reaction: Asymmetric Synthesis of Axially Chiral 2,3-Disubstituted Indoles.

Abstract

We report herein the first examples of palladium-catalyzed enantioselective Cacchi reaction for the synthesis of indoles bearing a\xa0chiral C2-aryl axis.\xa0In the presence of a catalytic amount of Pd(OAc)2\xa0and (R,R)-QuinoxP* ligand, reaction of\xa0N-aryl(alkyl)sulfonyl-2-alkynylanilides with arylboronic acids under oxygen atmosphere afforded enantioenriched 2,3-disubstituted indoles in high yields and enantioselectivities.\xa0The indole ring was\xa0de novo\xa0constructed in this process and a\xa0complexation-induced chirality transfer was proposed to account for the\xa0observed enantioselectivity.