Abstract A heteroaromatic compound 3,6-diaminodipyrido[3,2-a: 2′,3′-c]phenazine was synthesized with an improved method to convert 1,10-phenanthroline derivatives to the corresponding 5,6-diones. It was shown that the electron-donating effects of amino substituents were extended not only to pyridine rings but also to the phenazine ring.