1.2.4- Benzotriazine 4-oxides

The condensation of 3-amino-1,2,4-benzotriazine 1-oxides 29 with a-halo-carbonyl compounds results in imidazo[2,l-c]-l,2,4-benzotiiazine 1-oxides 30 (82JHC61, 86MI). 

With hydrogen peroxide in acetic acid 1,2,4-benzotriazine gave 1,2,4-benzotriazine 1-oxide and benzotriazole, but oxidation with MCPBA afforded a mixture of the 1-oxide and the 2-oxide (82T1793). 

Benzotriazine 1-oxide, 3-amino-, condensation with 2-bromomethyl 1,3-dioxolan, 59, 95... 

Treatment of l,2,4-benzotriazin-3-one 1-oxide (131) with sodium hydroxide afforded benzotriazole (132a). Similarly, 3-amino-1,2,4-benzotriazine 1-oxide (133) with a base gave benzotriazole or 1-acetylbenzotriazole (132b) while 3-amino-l,2,4-benzotriazine 2-oxide (134) was converted into benzotriazole and benzotriazole-1-carboxamine (132c) (62JOC185). 

Treatment of 2-nitrophenylcarboximidamides with base affords 1,2,4-benzotriazine 1-oxides.15 5a c Similar treatment of the 2-nitrophenylureas, thioureas and guanidines leads to the 3-hydroxy-, 3-sulfanyl- and 3-amino-l,2,4-benzotriazine 1-oxides or their tautomers.155a c... 

Benzimidazoles are isolated when 1,2,4-benzotriazine 1-oxides 2 are reduced or reacted with phenylmagnesium bromide.37 375... 

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. 

---