One-pot aqueous-phase synthesis of quinoxalines through oxidative cyclization of deoxybenzoins with 1,2-phenylenediamines catalyzed by a zwtterionic Cu(II)/calix[4]arene complex

Abstract A green protocol for the synthesis of quinoxalines has been developed from catalytic oxidative cyclization of deoxybenzoins with 1,2-phenylenediamines in water. The optimal conditions are involved in the use of a water-soluble mononuclear copper(II) complex of a zwitterionic calix[4]arene [Cu(II)L(H 2 O)]I 2 ( 1 , H 4 L = [5,11,17,23–tetrakis (trimethylammonium)–25,26,27,28–tetrahydroxycalix[4]arene]) as a catalyst in alkali solution after refluxing for 15 h in O 2 . The target quinoxaline and its derivatives were obtained in good yields (up to 88%). The procedure described in this paper is simple, practical and environmentally benign.