Ruthenium Complex-catalyzed Novel and Facile Synthesis of Imidazo[1,2-a]pyridines from 2-Aminopyridines and vicinal-Diols

Abstract
Ruthenium complex-catalyzed N-heterocyclization of 2-aminopyridines with vicinal-diols offers a novel synthetic method for various imidazo[1,2-a]pyridines. For example, the reaction of 2-amino-4-methylpyridine with 1,2-cyclohexanediol in the presence of a catalytic amount of RuCl2(PPh3)3 under reflux in diglyme for 24 h afforded 2-methyl-6,7,8,9-tetrahydropyrido[1,2-a]benzimidazole in 74% yield.