Frustrated Lewis Pairs Catalyse the Solvent‐Assisted Synthesis of Azoles from ortho‐Substituted Anilines, CO2 and H2.

Synthesizing azoles from ortho‐substituted anilines, CO2 and H2 has proved difficult due to the low nucleophilicity of anilines, which hinders their N‐formylation, i. e., the first step of the reaction. This study demonstrates that R3SnX Lewis acids (LA), N‐methylmorpholine (NMM) or DBU and polyethyleneimine (PEI) or N‐formylmorpholine efficiently catalyse the synthesis of benzimidazole and other azoles from ortho‐substituted anilines, CO2 and H2 by reductive coupling of CO2 to nucleophilic amine‐based solvents, PEI or morpholine, followed by in‐situ transfer of the formyl group to the appropriate ortho‐substituted aniline. Under these reaction conditions, spontaneous cyclization of the N‐formylated intermediate yields the corresponding azole in up to 98 % yield. [ABSTRACT FROM AUTHOR]