Tetrasulfur tetranitride, ring

The only heterocyclic seven-membered ring system with maximum unsaturation containing six heteroatoms is 1,3A4,5,2,4,6-trithiatriazepine (1). The methoxycarbonyl derivative 2 is a minor product (14%) of the complex reaction of tetrasulfur tetranitride with dimethyl acetylenedicarboxylatc in refluxing toluene, which gives mainly dimethyl l,2,5-thiadiazole-3,4-dicarboxylate (3, 67%) (see Houben-Wcyl, Vol. E8d, pl54ff which includes an experimental procedure). Two other products are the trithiadiazepine 4 (5%, see Section 4.4.1.1.1.) and the 1,2,4-thiadiazole derivative 5 (3%).385... 

The polyazapolysulfur ring system 1,3,2,4,6-dithiatriazine 15 is obtained by reacting 1-aryl-2,2,2-trifluoroethanone oximes with tetrasulfur tetranitride in refluxing toluene. However, the yield is only moderate <%JHC295>. 

Tetrasulfur tetranitride (S4N4) is perhaps the most widely reported reagent for the [3 -f 2] (type A or B) formation of the 1,2,5-thiadiazole ring (Table 5) <90MI 409-01>. 

Compounds which contain sulfur-nitrogen rings were known in the last century, but many new ones have been prepared in the last decade. It is currently an area of considerable interest. The ammonolysis of sulfur monochloride. S CIj, either in solution in an inert solvent or heated over solid ammonium chloride, yields tetrasulfur tetranitride ... 

Diazoalkanes react with tetrasulfur tetranitride to give red crystalline l,3/l 5, 5,2,4-trithiadiazines (85), a new ring system with an almost planar ring. Thus, addition of ethereal diazomethane to S4N4 in dichloromethane at room temperature affords, after 0.5 h, the 1,3,5,2,4-trithiadiazine in 37% yield. Similar reaction of S4N4 with aryldiazomethanes gives open chain compounds as major... 

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