A Metal-Free Synthesis of 3-Phenoxyimidazo Heterocycles by Catalytic Oxidative Cyclization of 2-Amino-azaarenes with Lignin Models

Abstract

A metal-free catalytic oxidative cyclization of 2-aminopyridines and 2-aminobenzothiazole with lignin model 2-phenoxyacetophenones was developed, in which inexpensive iodine was used as the catalyst and tert-butyl hydroperoxide (TBHP) was the oxidant. The reaction proceeded smoothly under an air atmosphere to produce valuable 3-phenoxyimidazo[1,2-a]pyridines and 3-phenoxybenzo[d]imidazo[2,1-b]thiazoles, respectively, in moderate to good yields.