1,2,4-Benzoxadiazines

Abstract

1,2,4-Benzoxadiazines (1) have been prepared by two new methods: (a) the reaction of N-aryl-SS-dimethylsulphimides with nitrile oxides, and (b) the oxidation of N-arylamidoximes. Both reactions are shown to involve the intermediacy of N-aryl-C-nitroso-imines, which can be reversibly intercepted in a Diels-Alder reaction with thebaine. Earlier publications on the synthesis of 1,2,4-benzoxadiazines have been re-assessed, and some of the structures proposed by previous workers have been revised.