抄録
Synthesis of some derivatives in the novel ring system, imidazo [4, 5-e-as]-triazine (6-azapurine) (Va-f), has been described. 2-Benzyl-6-bromo-as-triazine-3, 5 (2H, 4H)-dione (1-benzyl-5-bromo-6-azauracil) (I) reacted smoothly with ammonia and benzylamine, to give 6-amino-(IIa) and 6-benzylamino-2-benzyl-as-triazine-3, 5 (2H, 4H)-dione (IIb) respectively. Selective thionation of these amino derivatives (IIa, b), by heating with phosphorus pentasulphide in pyridine, to lead to 6-amino-(IIIa) and 6-benzylamino-2-benzyl-as-triazin-3 (2H)-one-5 (4H)-thione (IIIb), effectively proceeded, and subsequent aminodethiolation of the latter (IIIa, b) also readily went on to afford 5, 6-diamino-(IVa), 5-amino-6-benzylamino-(IVb), 5-benzylamino-6-amino-(IVc), and 5, 6-dibenzylamino-2-benzyl-as-triazin-3 (2H)-one (IVd). An oxidative mode of cyclisation, by heating with ethyl orthoformate or benzaldehyde in nitrobenzene under reflux for a few hours, furnished a successful procedure for the preparation of 2-benzyl-5H-(Va) and 2, 5-dibenzyl-imidazo [4, 5-e]-as-triazin-3 (2H)-one (Vb), or 2-benzyl-5H-(Vc), 2, 5-dibenzyl-(Vd), and 2, 7-dibenzyl-6-phenyl-imidazo [4, 5-e]-as-triazin-3 (2H)-one (Ve), respectively. An attempted benzylation of Vc yielded a mixture of the products which consisted of Vd, as a minor component, and the alternative isomer assigned tentatively to 2, 4-dibenzyl-6-phenyl-imidazo [4, 5-e]-as-triazin-3 (2H)-one (Vf), as a major one, however, it was not contaminated with any isolable amount of Ve.
