Thiazete dioxides, formation

The isothiazole-1,1-dioxide 211 has been shown to react with 2 equiv of sodium azide affording the corresponding 4/7-1,2-thiazete carbonitrile 18 accompanied by the [l,2]thiazine carbonitrile 212 and the acyclic sulfamic acid derivative 213 (Equation 21). Prolonged heating of the mixture results only in the formation of the thermally stable 4/7-1,2-thiazete carbonitrile and the 1,2-thiazine carbonitrile <2002T5173>. 

The photochemical decomposition of the thiazete 207 in benzene at 30 °C affords carbazole 208190. The reaction presumably involves the formation of a biradical by S—N bond fission which, on loss of S02, undergoes cyclization to yield the final product. Loss of sulphur dioxide also occurs on irradiation of the sultam 209 yielding the quinomethane imine 210, which ring closes to the azetidine 211181. Irradiation of the sulphobenzimide 212 in benzene yields the amide 213 by a free radical reaction path182. 

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