Tandem Catalytic Indolization/Enantioconvergent Substitution of Alcohols by Borrowing Hydrogen to Access Tricyclic Indoles

Abstract

An efficient tandem catalysis method is achieved for the direct conversion of alcohol‐containing alkynyl anilines to valuable chiral 2,3‐fused tricyclic indoles. This method relies on a tandem indolization followed by enantioconvergent substitution of alcohols via borrowing hydrogen to construct two rings in one step, enabled by relay and cooperative catalysis of a chiral iridium complex with a chiral phosphoric acid. Highly diastereoselective transformations of the tricyclic indole products also provide efficient access to a diverse array of complex polycyclic indoline compounds.

Recent advances in C/N-alkylation with alcohols through hydride transfer strategies

“…In continuation, Legault and coworkers 73 In 2021, Zhao's team reported an Ir-catalyzed domino annulation, including the borrowing-hydrogen process to access tricyclic indols (Scheme 63). 74 The bulkiness of the R group was of great importance in terms of enantioselectivity. The larger groups and branched alkyl chains led to tricyclic products with higher enantiomeric ratios.…”