Thiazete dioxides

Unsaturated rings such as 277-1,2-thiazetes 1, 277-1,3-thiazetes 2, 477-1,2-thiazetes 3, 477-1,2-thiazete 1,1- dioxides 4 ... 

Table 1 X-Ray structure-derived bond lengths (A) of molecules A and B of the 1,2-thiazete- 1,1 -dioxide derivative 17 <199617183>...

The presence of a signal associated with a quaternary carbon at S = 86.6 ppm is the main feature of the 4//-1,2-thiazete 1,1-dioxide derivatives 18 <2002T5173>. 

The cycloaddition reaction of compound 6 with N-aryl- and N-aralkylazides 23 was also investigated (967(52)7183). Thiadiazabicyclo[3.1.0]hexene derivatives 25 were obtained from the labile triazoline intermediate 24 through nitrogen elimination. This bicyclic system underwent thermal transformation, producing thiadiazine dioxides 26 as the main product together with thiazete dioxides 27 and pyrazoles 28. 

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 reaction of sodium azide with 5-substituted 3-diethylamino-4-(4-methoxyphenyl)-isothiazole 1,1-dioxides afforded [l,2]thiazete 5,5-dioxides 56. It has been proposed that a nucleophilic addition of the azide ion to C-5 followed by ring closure gave a triazoline intermediate, which cyclized intramolecularly with concomitant nitrogen extrusion <02T5173>. 

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. 

A-(Alkylsulphonyl)imides (138), prepared by treating A-alkylsulphamoyl chlorides with Et3,N, react with enamines that bear no hydrogens jS to the morpholino-group to give 1,2-thiazetidine 1,1-dioxides (139). The preparations and e.s.r. spectra of two relatively stable l,2-thiazet-2-yl radicals have been reported. ... 

H-oxathiazines 32, 577 2H-l,3-Thiazete-thioacylimine tautomerism 32, 577 4H-1,4-Thiazine 1,1-dioxides... 

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