1,2,3-Benzotriazine 2-oxides

4-Methoxy-1,2,3-benzotriazine, like the 4-methyl and 4-phenyl compounds, forms the 2-oxide on N-oxidation; this is hydrolysed to the acidic 3,4-dihydro-4-oxo-1,2,3-benzotriazine 2-oxide, which is N-methylated by diazomethane at the 3-position. The 4-methoxy 2-oxide was converted into 4-amino- and 4-hydrazine-derivatives. 5-Amino-3-methylisoxazole-2-carbonitrile forms 3,4-dihydro-5-methyl-4-oxoisoxazolo[5,4-d]-1,2,3-triazine 2-oxide on reaction with nitric and sulphuric acids. The 15N n.m.r. spectra of some 1,2,3-benzotriazines and their N-oxides are reported.