An anomalous course of the reduction of 2-(3-oxo-3,4-dihydro-quinoxalin-2-yl)benzene diazonium salt. Synthesis of a new quinoxalino[1,2-c][1,2,3]benzotriazine system

By diazotization of 3‐(2‐aminophenyl)quinoxaline‐2(lH)‐one la and 3‐(2‐aminophenyl)‐6,7‐dimethylquinoxaline‐2(lH)‐one 1b followed by the reaction with sodium sulphite new quinoxalino[1,2‐c]‐[1,2,3]benzotriazins 4a and 4b were prepared, respectively.