On the synthesis of pyrazino[2,3-b] phenazine and 1H-Imidazo[4,5-b]phenazine derivatives

Several pyrazino[2,3-D]phenazine derivatives were prepared by the reaction of 2,3-diaminophenazine with different 1,2-diketones. Nucleophilic substitu tion of 2,3-dibromomethyl-pyrazino[2,3-b]phenazine with propanol, morpholin e, and potassium thiocyanate gave 2,3-bis(propoxymethyl)-pyrazino[2,3-b]phe nazine 2,3-bis-(4-morpholinylmethyl)-pyrazino[2,3-b]phenazine, and 2,3-bis- (cyanosulfanylmethyl)-pyrazino[2,3-b]phenazine. 2-Aryl-1H-imidazo[4,5-b]phe nazine derivatives were synthesized by a one-pot reaction of 1,3-diaminophe nazine with different aromatic aldehydes or acids. Reaction of 2,3-diaminop henazine with acetic anhydride and formic acid afforded 1H-imidazo[4,5-b]ph enazine and 2-methyl-1H-imidazo[4,5-b]phenazine. Chemical and spectroscopic evidences for the product structures of the new compounds are presented.