K2S2O8‐Mediated C‐3 Formylation of Imidazopyridines Using Glyoxylic Acid

Abstract

AbstractA metal‐free formylation of imidazopyridines by direct decarboxylative cross‐coupling of glyoxylic acid in presence of K2S2O8 as oxidant under mild and neutral conditions is described. This reaction features a broad substrate scope, good functional group tolerance, and generates products in good yields between 68–85 %. The translational capacity of the reaction from a laboratory methodology to gram‐scale synthesis has also been ensured. The involvement of a radical pathway has been demonstrated by radical trapping experiments with 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) and 2,6‐di‐tert‐butyl‐4‐methylphenol (BHT).