Thiohydrazides, 1,2,3,4-thiatriazoles

Thiazyl halides, aromaticity of, 357 Thienotropylium cation, salts of, 65 Thiocarbamoyl azides, 264 Thiohydrazides, 1,2,3,4-thiatriazoles firom, 265... 

The most general route to 1,2,3,4-thiatriazoles involves treatment of a thiohydrazide with nitrous acid [Eq. (1)]. Thus, 5-amino-... 

From thiohydrazides, R CS NHNHg, in which R is an aromatic or a heterocyclic group, 1,2,3,4-thiatriazoles may in general be obtained in good yield by treatment with nitrous acid. ... 

Thiohydrazides 136 react with nitrous acid or aryldiazonium salts to give 5-substituted 1,2,3,4-thiatriazoles 9... 

Thiatriazoles 9 with an aromatic or heteroaromatic substituent in the position 5 of the ring are rather stable and may thus be easily prepared from thiohydrazides and nitrous acid. The very unstable 5-tert-huty - and 5-cyclohexyl-1,2,3,4-thiatriazoles can also be prepared by this reaction, but this method is not generally applicable because of difficulties in obtaining the starting thiohydrazides <1961ACS1104, 1961JOC5221>. 

Treatment of thiohydrazides with nitrous acid leads to formation of thiatriazoles. 5-Amino-l,2,3,4-selenatriazoles may be prepared in the same manner from the corresponding selenosemicarbazides (83 R1 = R -Et, ca. 60%) but the reaction is accompanied by the formation of elemental selenium. A comparable yield is achieved by use of an aza transfer reagent (55-70%) (equation 54). The best yield and purest material are obtained from the... 

The 5-substituted 1,2,3,4-thiatriazoles 758 are prepared by the generation of intermediate azidothiocarbonyl compounds 757 followed by 1,5-electrocyclic reaction (Scheme 326). The intermediate compounds 757 have never been isolated they can be generated by treatment of derivatives of thiohydrazides 756 with either nitrous acid or with arenediazonium salts, and in reactions of thiophosgene (or dithiocarboxylates) 755 (X = Cl, SR) with either sodium- or trimethylsilyl azide (Scheme 326) . For example, thiatriazoles 760 can be prepared in high yields by the reaction of or A-thioacyl dithiophosphates 759 with sodium azide (Scheme 327) <2002J(P1)1271>. 

The salts of thiatriazole-5-thiol react with alkyl and acyl halides to give 5-alkyl and 5-acyl derivatives. A table with references to 1,2,3,4-thiatriazolethiols was published in the 1964 review (64AHC(3)263). A number of 5-(acylthio)thiatriazoles has been prepared by Christophersen (71ACS1160,71ACS1162,761745). Nitrosation of a thiohydrazide can also be used for the preparation of mercaptothiatriazoles (e.g. equation 44) (71ACS2015.71JIC843). 

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