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

In some cases, the position of the N-oxidation depends on the temperature. The reaction of 3-phenyl-1,2,4-benzotiiazine 172 with peracetic acid affords 3-phenyl-l,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-benzo-triazine 176 (R = Me) under the same conditions results in a mixture of 3-methyl-l,2,4-benzotriazine 1-oxide 175 and 2-oxide 177 in 25 and 10% yields, respectively. 

Oxidation of 1,2,4-benzotriazines with peracid leads to a mixture of the 1-oxides, the 2-oxides and the 1,4-dioxides, depending on the reaction conditions used.109 243 Thus, oxidation of 3-methyl-l,2,4-benzotriazine with hydrogen peroxide in acetic add for four days at room temperature yields five products 3-methyl-l,2,4-benzotriazine 1-oxide (12), the 2-oxide 13, 3-methyl-l,2,4-benzotriazine 1,4-dioxide (14), benzotriazole, and 2-methylbenzimidazole.109 Treatment of the same compound with 3-chloroperoxybenzoic acid in benzene at room temperature for four days yields the same two monoxides 12 and 13 and the same dioxide 14. 

Oxidation of 3-methyl-l, 2,4-benzotriazine 1-oxide with 3-chloroperoxybenzoie acid in benzene affords 3-methyl-1,2,4-benzotriazine 1,4-dioxide (14).109... 

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 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). 

Methyl-,242 3-phenyl-,450 or 3-amino-l,2,4-benzotriazine 1-oxide or -2-oxide afford benzo-triazoles 4 when treated with sodium hydroxide377 The same reaction is observed for pyrido-[2,3-e]-l,2,4-triazin-3-amine or pyrido[4,3-e]-l,2,4-triazin-3-amine 1-oxide in sodium hydroxide affording the corresponding products in 77 and 40% yield, respectively.370 379... 

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. 

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. 

For reductive ring contraction of 1,2,3-benzotriazine 3-oxides to 3-aminoindazoles, see Section 9.01.5.6. Reduction of 2-methyl- or 2-aryl-l,2,3-benzotriazinium-4-olate 1-oxides 237 with stannous chloride in concentrated hydrochloric acid/acetic acid at 0-5°C gave benzotriazinium-4-olates 46 (Equation 99) (<1974JOC2710> (A), <1972JOC1587> (B)). 

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