An efficient synthetic route of quinoxalines from diols catalyzed by [RuCl2(p-cymene)]2/1,4-bis(diphenylphosphino)butane

Abstract

An efficient and convenient homogeneous catalytic system is developed from commercially available Ru complex ([Ru(p-cymene)Cl2]2) and 1,4-bis(diphenylphosphino)butane (dppb) for coupling aromatic diamines and vicinal diols to produce quinoxaline derivatives, an important class of N-heterocycles, via one-step alcohol acceptorless dehydrogenation route. Under the optimized condition, quinoxaline derivatives are obtained in excellent yields (up to 93%) and high turnover numbers (up to 744). This homogeneous system for the synthesis of quinoxaline derivatives is performed under a practically neutral condition, and thus gives new threads to develop novel transition metal complexes for convenient and efficient synthesis of N-heterocycle compounds without the use of complicated ligand and stoichiometric amount of strong base, which are usually used in most reported homogeneous systems.