Synthesis and NMR Spectra of Substituted 1,4,5,8‐Tetraazaphenanthrenes(TAP)

The synthesis of ring A substituted TAP'S starts from 5,6‐diaminoquinoxaline (II), which is condensed with n‐butylglyoxylate to give a mixture of 2‐ and 3‐hydroxy‐TAP, which reacted with POCl3/PCl5 to afford the corresponding monochlorocompound. Similarly, the condensation of II and ethyl oxalate produces 2,3‐dihydroxy‐TAP; this gives 2,3‐dichloro‐TAP with the same chlorinating agents. Nucleophilic substitution of the chlorine atom(s) (sodium methoxide, piperidine, hydrazine) occurs with high yields. The monohydrazino‐TAP's were oxidized into the corresponding monodeuterated derivatives, which allow an unambiguous assignment of the 1H NMR spectrum of TAP itself.