1.2.4- Benzotriazine 1,2,4-trioxide

Reaction of benzofuroxan 470 with nitrile oxides affords 1,2,4-benzotriazine 1,2,4-trioxides 47 (Scheme 246) <1989CC986> this ring expansion is similar to the Beirut reaction (see Section 4.4.6.4). 

Reaction of benzofuroxan (470) with nitrile oxides in refluxing dichloromethane affords 1,2,4-benzotriazine 1,2,4-trioxides (471) (Equation (64)) <89CC986>. The reaction has also been applied to the formation of 1,2,4-triazino[5,6-Z)]quinoxaline trioxides <91S83>. 

The two main approaches to iV-oxides of 1,2,4-triazines are (a) iV-oxidation (Section 6.11.5.4), and (b) ring synthesis by closure to an oxime group (Scheme 78). See also Equation (25). Other methods can be applied to 1,2,4-benzotriazine oxides, including the rather spectacular trioxide synthesis (Equation (60)). 

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