3- Methyl-1,2,4-benzotriazine 1 -oxide

In some cases, the position of the N-oxidation depends on the temperature. The reaction of 3-phenyl-1,2,4-benzotriazine 172 with peracetic acid atfords 3-phenyl-1,2,4-benzotriazine 1-oxide 173 at 50°C and 2-oxide 174 at room temperature (57JCS3186). Only the 1-oxide 175 was obtained by the oxidation of 3-unsubstituted 1,2,4-benzotriazine 176. The oxidation of 3-methyl-1,2,4-benzotriazine 176 (R = Me) under the same conditions results in a mixture of 3-methyl-1,2,4-benzotriazine 1-oxide 175 and 2-oxide 177 in 25 and 10% yields, respectively. 

The photodecomposition of benzotriazine A/ -oxides produced 3-substituted 2,1-benzisoxazoles (Scheme 183) (73JA2390). The photolysis of cinnoline 1-oxides produced 3-methyl-2,1-benzisoxazoles (Scheme 183) (74TL2643, 74T2645). 

Methyl-1,2,4-benzotriazm-3(4//)-one 1-oxide 122 can be obtained in good yield by the diazotization of 121 to give 3-diazo-7-methyl-l,2,4-benzotriazine 1-oxide followed by the substitution of the diazo group with water (82JHC497). 

The reaction of benzofurazan iV-oxide with diethylamine affords 3-methyl-1,2,4-benzotriazine 4-oxide 160 (79T681, 82T1793). 

Evidence from nanosecond flash photolysis studies indicates that an oxa-ziridine precursor to the diazoketone is unlikely. Photoelimination of nitrogen is also observed in 4-methyl-1,2,3-benzotriazine 3-oxide and affords 3-methylanthranil a mechanism involving loss of nitrogen from an intermediate oxaziridine has been proposed.74... 

Alternative procedures for the preparation of 4-alkyl- and 4-aryl-1,2,3-benzotriazines have also been investigated by Rees. Thus, the diazoazide (11) undergoes smooth decomposition in refluxing benzene to give 4-methyl-1,2,3-benzotriazine (8, R = Me) in 70% )deld. Oxidation of the o-aminohydrazones (12, R = Me, Ph,p-MeOCsH4) with lead tetraacetate also gives the corresponding triazines (8) in moderate yield. 

The product of methylation of l,2,4-benzotriazin-3-one 1-oxide (210) with methyl iodide was identified as 4-methyl-1,2,4-benzotriazin-3-one 1-oxide (211) (59JOC813). Like the amines in the monocyclic series mentioned above, 3-amino-l,2,4-benzotriazine 1-oxides (133) are acylated on the amino group (54JA3551). 

The reaction of benzofurazan oxide (605) with amines has been studied by Haddadin et al. (79T681). With diethylamine, beside other products, 3-methyl-l,2,4-benzotriazine (606) and its 4-oxide (607) were isolated, the production of which was explained by the intermediate formation of (608) and (609). 

Both the 1- and 2-oxides of 3-methyl-l,2,4-benzotriazine can be obtained by direct oxidation of the parent heterocycle with peracid, and both give benzotriazole in low yield on brief treatment with 2% aqueous NaOH. 

A somewhat similar result97 is obtained in the reduction of 4-methyl-l,2,3-benzotriazine-3-oxide (94) to 3-methylindazole (95) and hy-droxylamine by a four-electron reduction. At pH 4 94 gives two four-electron waves the second wave is probably caused by the reduction of the intermediate oxime (96). Both waves disappear during the electrolysis at the potential of the first wave (Scheme 11). 

Oxidation of 3-methyl-4-methylene-3,4-dihydro-l,2,3-benzotriazine (9) with oxygen or ozone afforded 3-methyl-l,2,3-benzotriazin-4(3/f)-one.212... 

The reaction of benzofurazan 1-oxide with amines has been studied.209 Using diethylamine as the amine, in addition to other products, 3-methyl-l,2,4-benzotriazine 2 and its 4-oxide 3 were isolated. The formation of both products has been explained by the formation of the intermediates shown. 

---