1,2,3,4 Thiatriazoles

4- Thiatriazoles.—5-Arylamino-l,2,3,4-thiatriazoles (270 R = NHAr) have been prepared by allowing the corresponding thiosemicarbazides RNHC(S)NHNH2 to react with nitrous acid, and the reaction between PhSC(S)Cl and potassium thiotosylate gives PhSC(S)S—STos, which reacts with sodium azide to give (270 R = PhS).  

Burger, R. Ottlinger, A. Proksch, and J. Firl, J. Chem. Soc., Chem. Commun., 1979, 80. 

Significant rearrangements occur on reacting the amino compound 297 

The phenyliminothiatriazole 314 (R = Me, R =Ph) reacts with ethyl cyanoformate or p-toluensulphonyl cyanide to afford directly the phenyli-minothiadiazolines 316 (R = COOEt, p-MeC6H4S02) as a result of two consecutive reactions going through methylimino isomers 315 (91JHC333). In acetone solvent, the intermediate formation of the oxathiazolidine 317 

324 and/or 326. For this reaction, which we consider beyond the scope of the present treatment, we refer to the original papers (88JHC1459 89BSB879 90BSB391, 90JHC199, 90T1281). 

The 4-substituted-5-sulfonylimino-l,2,3,4-thiatriazoles also rearrange on reaction with unsaturated reagents [75JOC1728 80AG(E)276 82T3537  

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CN3S s N N N — 5-Phenyl-l,2,3,4-thiatriazole 5-amino-l,2,3,4-thiatriazole 5-phenyl-1,2,3,4-thiatriazole 3-oxide... 

Thiatriazoles readily decompose thermally into nitrogen, sulfur and an organic fragment, usually a cyanide, e.g. (27) Bu OCN + + S (76AHC(20)145). 

Phenylthiazirine (40) can be isolated as an intermediate in the photolysis of 5-phenyl-1,2,3,4-thiatriazole and also from other five-membered ring heterocycles capable of losing stable fragments see Scheme 2 (81AHC(28)231). Photolysis of 5-phenylthiatriazole in the presence of cyclohexene yields cyclohexene episulfide (60CB2353) by trapping the sulfur atom. 

Substituted 1,2,3,4-thiatriazoles (93) are alkylated only under very forcing conditions with triethyloxonium fluoroborate, but then give the expected products (94) (75JOC431). 

There are many related examples which are now known as the general Dimroth rearrangement. For example, 3-ethylamino-l,2-benzisothiazole (419) is in equilibrium in aqueous solution with the 2-ethyl-3-imino isomer (420) <72AHCf 14)43). Dimroth rearrangements are known in the 1,2,4-thiadiazole series (421- 422), and in the 1,3,4-thiadiazole series as products of reactions of halogeno-l,3,4-thiadiazoles see Section 4.02.3.9.1 <68AHC(9)165). For a similar example in the 1,2,3,4-thiatriazole series, see Section 4.02.3.1.9. 

Thiatriazole, 5-arylamino-alkylation, 6, 596 anticancer activity, 6, 598 methylation, 6, 590 reactions... 

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