A simple and convenient two-step, one-pot synthesis of hetero-imidazoles from nitroaminoaryls catalyzed by Ytterbium triflate

A mild two-step one-pot procedure for the conversion of ortho-nitroamino aromatic heterocycles into corresponding benzo and heteroaromatic fused imidazoles is described. The procedure utilizes iron powder, acetic acid, triethylorthoformate, and a catalytic amount of Ytterbium triflate at 75 °C for the nitro group reduction and cyclization reaction. The optimum stoichiometry of each component is highlighted and the broad utility is demonstrated with high compatibility to numerous functional groups.