1.2.3- Benzotriazine, 4-phenyl-, reaction

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. 

Benzannulated azocines can be prepared starting from 4-phenyl-l,2.3-benzotriazine (16), flash-vacuum pyrolysis of which leads to 2-phenylbenzazete (17) (cf. Houben-Weyl. Vol. E16c, p 939), which is stable until about 40 °C and easily enters into cycloaddition reactions with dienes. With tetraphenylcyclopentadienone, a nonisolable adduct is formed which, by loss of carbon monoxide, gives an azabicyclo[4.2.0]octatriene derivative that isomerizes to the 1 -benzazocine 18.22... 

Interest in the thermal and photochemical reactions of condensed 1,2,3-triazine derivatives dates from 1962, when first Gibson and then Hey, Rees, and Todd reported independently on the reactions of 3-phenyl-l,2,3-benzotriazin-4(3H)-one (10, R = Ph) at elevated... 

Benzyne is produced in the vapor phase by the fragmentation of phthalic anhydride and of o-sulfobenzoic anhydride (11) at 690°C,17 also of 4-phenyl-1,2,3-benzotriazine (12),18 phthaloyl peroxide (13),19 and a variety of other cyclic systems at appropriately high temperatures. From the point of view of studying the reactions of benzyne with heterocycles, these methods are necessarily restricted in their application. 

The transformation of 3-phenylindazol-l-amine (3a) into 4-phenyl-l,2,3-benzotriazine (7a) by reaction with butyllithium and tosyl azide has been reported.115... 

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... 

In view of these results it must be concluded that the other anthranil JV-oxides obtained by oxidation of o-nitrobenzaldehyde phenylhydra-zones,243 or by solvolysis of their a-bromo derivatives,244 should be reformulated as benzotriazinium JV-oxides. However, it is quite likely that 3-arylazoanthranil JV-oxides are intermediates in these reactions and also in the photolytic rearrangement of a-bromo-o-nitrobenzaldehyde phenyl-hydrazones to 3-aryl-l,2,3-benzotriazin-4-ones.245... 

Methyl-l,2,3-benzotriazine 3-oxide in methanol irradiated under Ng with a 450 w. medium-pressure Hg-arc lamp in a Pyrex vessel 3-methylanthranil. Y 80%. -- Also ethyl analog, and different reaction of the phenyl analog s. W. M. Horspool et al., Am. Soc. 95, 2390 (1973). 

Phenyl-6-fluoroquinoline 80 has been obtained through the cycloaddition reaction of bicyclo[2.2.1]heptadiene on 1,2,4-benzotriazine 79, taking place under high pressure conditions (Scheme 31) [51],... 

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