4- Amino-3-methyl-5-thione-1,2,4-triazole

Amino-3-methyl-5-thione-l,2,4-triazole with [HgR(MeCOO)] (R = Me, Ph) gives complexes 186, where coordination occurs via the sulfur and amino nitrogen atoms (93JOM(450)41). In the crystalline state, intermolecular interaction of the mercury site with the endocyclic nitrogen atom of the neighboring unit is also observed. 

In the ring closure of 5-amino-2,3-dihydro-17/-l,2,4-triazolo-3-thione 431 (R = NH2) with 1,2-dibromoethane in the presence of sodium methoxide (2equiv), compound 42 was formed as the main product (Scheme 50) <2003JHC821>. Similarly, the same type of functionalized thiazolo[3,2-A][l,2,4]triazoles 440 and 441 were isolated in the reaction of 1,2-dibromoethane with 2,3-dihydro-17/-l,2,4-triazolo-3-thione (431, R = H) or 2,3-dihydro-5-methyl-l/7-l,2,4-triazolo-3-thione (431, R = Me), using DMF as the solvent in the presence of potassium carbonate and benzyltriethylammonium chloride (CBTEA) (Scheme 50) <2004PS(179)1799>. 

The Schiff base derivatives 73 of the 3-hetaryl-substituted 4-amino-3-thiol-l,2,4-triazoles, on treatment with acetic anhydride, undergo cyclization to give the corresponding 3-substituted-5-acetyl-5,6-dihydro-6-phenyl[l,2,4]triazolo[3,4-7][l,3,4]thiadiazoles 76 (Equation 16) <1990IJB135>. Similar treatment of 4-(A-bcnzoylamino)-4,5-dihydro-l-methyl-3-mcthylthio-1 //-[ 1,2,4 triazolc-5-thione 77 leads to the [l,2,4]triazolo[3,4-4][l,3,4]thiadiazolium trifluoromethanesulfonate 78 (Equation 17) <1986LA1540>. 

Contrasting with the reported formation of fused [l,3,4]thiadiazole rings in the course of the reaction of 3-substituted-4-amino-5-thio-47/-[l,2,4]triazoles 83 with various isothiocyanates (cf. Section 11.07.8.3, Table 3), the reactions with methyl isothiocyanate and with phenylisocyanate afford 3,7-disubstituted-6,7-dihydro-57/-[l,2,4]triazolo[4,3-f] [l,2,4]triazole-6-thiones 110 and -triazole-6-ones 111, respectively (Equation 29) <1986MI607, 1992IJB167>.The same reaction of 4-amino-l-methyl-3,5-bis(methylthio)[l,2,4]triazolium iodide 112 with aryl isothiocyanates yields the mesoionic compounds 113 (Equation 30) <1984TL5427, 1986T2121>. 

Similarly, the reaction of 4-amino-l-mcthyl-3-methylthio-l//-[l,2,4]tnazol-5(4//)-onc 116 furnishes 6-aryl-2-methyl-7//-[l,2,4]triazolo[4,3-/d[l,2,4]triazol-3(2//)-ones 117 (Equation 32) <1985BCJ735> and the 4-amino[l,2,4]triazole-5(4//)-thione 118 furnishes 6-aryl-l,3-dimethyl-l//-[l,2,4]triazolo[4,3-3][l,2,4]triazoles 119 (Equation 33)... 

Artemov and Shvaika treated a number of 2-aryl-l,3,4-oxadiazole-5(4//)-thiones (293) with methylhydrazine (R = Me) and obtained a mixture of 1-methyl-1,4-dihydro-1,2,4,5-tetrazine-6(5/f)-thiones (294) and 4-methylamino-l,2,4-triazole-3-thiones (295 R = Me) (71KGS905). A similar reaction was reported by Konig and his coworkers, who treated 5-(4-pyridyl)-l,3,4-oxadiazole-2-thione (293 Ar = py) with hydrazine (R = H) and obtained a compound which was either the l,2,4,5-tetrazine-6-thione (294 R = H) or the 4-amino-l,2,4-triazole-3-thione (295 R = H) (54CB825,56GEP953801). 

G2N3 N N N C c l,3-Dimethyl-4-(l,2,3-triazolyl)sulfide 3-methyl-2-phenyl-l,2,3-triazol-l-ine-4-thione 2-(4-chlorophenyl)-4-amino-5-benzoyl-l,2,3-triazoleaf... 

Cyclizing 4-amino-3-methylthio-l,2,4-triazoles (167) (83S415) or 4-amino-2-methyl-l,2,4-triazolo-3-thiones (169) (85H2613) with aromatic (83S415 85H2613) or heterocyclic nitriles (85H2613) in the presence of potassium /-butoxide afforded the corresponding 1,2,4-triazolo[4,3-h]-... 

Ethoxymethylenamino- 2-methyl-1,2,3-triazole-5-carbonitrile (90) (also its 1-methyl and 3-benzyl analogs), when refluxed with ethanolic sodium hydrogen sulfide for 10 h, produced 8-methyl-, 7-methyl-, and 9-ben-zyl-8-azapurine-6-thione in 83 - 97% yields. 4-Amino-1,2,3-triazole-5-car-bonitrile and its 2-methyl and 9-benzyl derivatives were refluxed (2 h) with potassium 0-ethyldithiocarbonate in dimethylformamide (or alternatively with carbon disulfide in pyridine) to produce 8-azapurine-X6-dithione (or its respective alkyl derivatives) in 88-95% yields. ... 

A derivative of a hitherto unknown nucleus was produced when 4-amino-5-aminomethyl-3-methyltriazole was refluxed with carbon disulfide and triethylamine in pyridine, which yielded 3-methyl-3,7-dihydro-l,2,3-triazolo-[4,5-d][l,3]thiazine-5-thione (98) (3 hr, 53%) the 3-benzyl analog was made similarly (63%) [80JCS(P1)2009]. Cyclization of 4-anilino-5-ethoxycarbonyltriazole with polyphosphoric acid produced 1 f/-triazolo-[4,5-h]quinol-4-one (99) [80EUP(A)2562]. Similarly, ring closure of 4-(2-pyridylamino)triazole-5-carboxylic acid (or its esters) gave l//-pyrido-[l,2-a]-l,2,3-triazolo[4,5-d]pyrimidin-4-one (100) (77GEP2757929). 4-Amino-5-formyl-3-methyltriazole and pentane-2,4-dione, set aside in 20% sulfuric acid, yielded 3,5-dimethyl-3//-l,2,3-triazolo [4,5-6] pyridin-6-yl... 

Reaction of thio- and alkylthio derivatives of A -aminoazoles with aryl isothiocyanates leads to annelation of a 1,3,4-thiadiazole or a 1,2,4-triazole ring. Thus, 4-amino-3-methyl-l,2,4-triazoline-5-thione, on reaction with aryl isothiocyanates under mild conditions, gives products of addition (388), which on heating are transformed to 2-arylaminotriazolo[3,4-/>]thia-diazoles (389) (83S411 87JHC1173). 

Amino-3,5-bismethylthio-1,2,4-triazole is converted by alkylating agents in refluxing DMF into the corresponding l-alkyl-4-amino-5-methyl-thiotriazoline-3-thiones [Eq. (108)] (83S414). 

The isolable potassium salts (74) (available from the nucleophilic addition of 4-amino-l-methyl-3-methylthio-l -l,2,4-triazole-5(4//)-thiones (73) to aromatic nitriles in the presence of base) upon acidification with hydrochloric acid cyclize to give 7/7-[l,2,4]triazolo[4,3-fc][l,2,4]triazole-3(2//)-thiones (75) (Scheme 5) <85BCJ735>. 

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