Hypervalent iodine mediated synthesis of imidazo[1,2-a]pyridine ethers: consecutive methylene linkage and insertion of ethylene glycol

Abstract

Hypervalent iodine mediated selective synthesis of imidazo[1,2-a]pyridine ethers using ethylene glycol as a methoxy ethanol source as well as solvent under metal-free conditions is described. The method is also applicable to other fused heterocycles such as benzo[d]imidazo[2,1-b]thiazoles, 2-(thiophen-2-yl)benzo[d]imidazo [2,1-b]thiazole and indazole. Control experiments suggest that, when the C-3 position of imidazo[1,2-a]pyridine is blocked, the reaction does not take place at any other position showing the regioselectivity of the present protocol.