1.2.4- Triazoles 3-amino— from

Other non-traditional preparations of 1,2,3-triazoles have been reported. The rearrangement in dioxane/water of (Z)-arylhydrazones of 5-amino-3-benzoyl-l,2,4-oxadiazole into (2-aryl-5-phenyl-27/-l,2,3-triazol-4-yl)ureas was investigated mechanistically in terms of substituents on different pathways <06JOC5616>. A general and efficient method for the preparation of 2,4-diary 1-1,2,3-triazoles 140 from a-hydroxyacetophenones 139 and arylhydrazines is reported <06SC2461>. 5-Alkylamino-] //-], 2,3-triazoles were obtained by base-mediated cleavage of cycloadducts of azides to cyclic ketene acetals <06S1943>. Oxidation of N-... 

Releases of thiocyanate to soil result from anthropogenic and natural sources. Anthropogenic releases occur primarily from direct application in herbicidal formulations (e.g., amitrol-T, a mixture of ammonium thiocyanate and amino-1,2,4-triazole) and from disposal as byproducts from industrial processes. Nonanthropogenic sources include damaged or decaying tissues of plants from the family Brassica (e.g., mustard, rape) (Brown and Morra 1993). Thiocyanate has been detected in soil samples collected at 2 of the 8 hazardous waste sites, and in sediment samples at 3 of the 8 hazardous waste sites where thiocyanate has been detected in some medium (HazDat 1996). The HazDat information used includes data from both NPL and other Superfund sites. 

A survey of the above-mentioned reactions will now be given. The alcoholysis135 of 2-amino-l,3,4-oxadiazoles with alcoholic KOH yields 3-alkoxy-l,2,4-triazoles (54) from which l,2,4-triazolin-5-ones may be prepared by heating with concentrated hydrochloric acid. 

The acetates of acetamidine and benzamidine were condensed with 4-aminotriazole-S-carboxamide (73a) and its 7- and 8-methyl derivatives to give 2-metoyl- and 2-phenyl-8-azapurin-6-ones, respectively, in 80-90% yield, after refluxing for 4 - 8 h in butanol, hexanol, or octanol (toe choice of solvent determined toe optimal yield in each case). The reaction with tri-chlOFoacetamidine terminated at, e.g., (a-amino-i ) )9-trichloroethyliden-amino) 1,2,3-triazole (84) (from 73a). These intermediates were cyclized to 2-trichlorometoyl-8-azapurin-6-ones, in excellent yields, by stirring with 0.5 N potassium hydroxide (24°C, 5 h). This reaction gave only poor yields with 73b,c. 

To obtain 2-amino-l,6-dihydro-8-azapurine, 96 (and its 2-methyl and 3-benzyl analogs) were refluxed with cyanogen bromide in methanol (4 h), giving 40-75% yields of the correspondingly alkylated products. 4-Amino-5-ethoxycarbonylaminomethyl-l,2,3-triazole (99) (from 96 and ethyl chloroformate), when refluxed in butanolic sodium butoxide (1 h), produced 7-methyl-l,6-dihydro-8-azapurin-2-one the 8-methyl and 9-ben-zyl analogs were made similarly (76-92% yield). ... 

Dehalogenation of 1,1- or 1,2-Dihaloalkenes and Other Eliminations of Two Vicinal Leaving Groups Oxidative Decomposition of 12-Dihydrazones and 1-Amino-123-Triazoles Elimination from 12,3-Selenadiazoles... 

Synthesis of 5-Mercapto-l,2,3-Triazole Derivatives from 5-Amino-l,2,3-Thiadiazoles... 

Synthesis of triazole derivatives from 2-mercaptobenzothiazole has been achieved in four steps under microwave irradiation. LiBr potentially replace solvents and corrosive acids in this method resulting in a facile, efficient and enviro-economic synthesis of 5-[(l,3-benzothiazol-2-ylsulfanyl)methyl]-4-[(phenyl substi-tuted)amino]-4H-l, 2, 4-triazole-3-thiol with catalytic amount of LiBr using basic alumina as inorganic solid support (Ameta et al., 2010b). 

Nonetheless, the usefulness of the method was somewhat limited due to the lability of triazole or active methylene compound under the vigorous reaction conditions employed. Thus, 1-substituted 5-amino-1//-1,2,3-triazoles are liable to undergo a Dimroth rearrangement to yield 4-substituted amino derivatives and also alkyl or benzyl azides with certain active methylene compounds give only moderate or poor yields of the desired products. Some success in improving the yields was achieved by the use of potassium t-butoxide as base at room temperature, which gave good yields of 5-amino-LW-l,2,3-triazoles 9 from benzyl and -hexyl azides with phenylacetonitrile 8 (Scheme 4.3) [5], but with methyl ketones, yields of the product were variable due to dimerization of the ketones and other side reactions. 

Cyanopyrazole is obtained from treatment of 4-amino-3-halopyridazines with potassium amide in liquid ammonia, while 4-amino-3,6-dihalopyridazines are rearranged under the same conditions to 3-cyanomethyl-l,2,4-triazole. 

The 4- and 5-amino-l,2,3-triazoles are diazotizable, e.g. the diazonium salt from 4-aminotriazole-5-carboxamide with potassium iodide gives the 4-iodo derivative, and that from 4-amino-l,5-diphenyltriazole gives 1,5-diphenyltriazole in ethanol (74AHC(16)33). 

Amino-l,2,4-triazole has been prepared by evaporating formylguanidine nitrate with sodium carbonate, and from 5(3)-amino-1,2,4-triazole carboxjdic acid-3(S) by heating above its melting point, or by a long digestion with acetic acid. ... 

Amino-l,2,4-triazole [61-82-5] M 84.1, m 159 , pKj 4.04, pK 11.08. Crystd from EtOH (charcoal), then three times from dioxane [Williams, McEwan and Henry J Phys Chem 61 261 1957]. 

A similar procedure was developed in greater detail by Domow and Heiberg. They proceeded from aryl or aralkyl azid and cyanacetamide (176) and the 1-aryl- or l-aralkyl-5-amino-i -triazole-... 

A combination of the preceding type of synthesis and of cyclization of 4-amino-5-arylazopyrimidine can be seen in the novel procedure of Richter and Taylor. Proceeding from phenylazomalonamide-amidine hydrochloride (180), they actually close both rings in this synthesis. The pyrimidine ring (183) is closed by formamide, the triazole (181) one by oxidative cyclization in the presence of cupric sulfate. Both possible sequences of cyclization were used. The synthetic possibilities of this procedure follow from the combination of the two parts. The synthesis was used for 7-substituted 2-phenyl-l,2,3-triazolo[4,5-d]-pyrimidines (184, 185). An analogous procedure was employed to prepare the 7-amino derivatives (188) from phenylazomalondiamidine (186). 

Other examples of nucleophilic attack on a furoxan ring leading to ring opening/recyclization are the formation of 1,2,3-triazole 1-oxides 198 from 4-alkylamino-3-nitrofuroxans 197 and alkylamines (Scheme 129). 3-Amino-4-nitrofurazan was observed as by-product (95MC194, 96CHE580, 96KGS675). 

Simple 1,2,4-triazole derivatives played a key role in both the synthesis of functionalized triazoles and in asymmetric synthesis. l-(a-Aminomethyl)-1,2,4-triazoles 4 could be converted into 5 by treatment with enol ethers <96SC357>. The novel C2-symmetric triazole-containing chiral auxiliary (S,S)-4-amino-3,5-bis(l-hydroxyethyl)-l,2,4-triazole, SAT, (6) was prepared firmn (S)-lactic acid and hydrazine hydrate <96TA1621>. This chiral auxiliary was employed to mediate the diastereoselective 1,2-addition of Grignard reagents to the C=N bond of hydrazones. The diastereoselective-alkylation of enolates derived from ethyl ester 7 was mediated by a related auxiliary <96TA1631>. 

An interesting Mossbauer study has been reported on the dinuclear SCO complex [Fe2 (PMAT)2](BF4)4-DMF (PMAT 4-amino-3,5-bis [(2-pyridylmethyl) amino]methyl -4H-1,2,4-triazole), where thermal ST occurs from [HS-HS] to the stable endproduct [HS-LS] [32]. The molecular structure and magnetic behavior of this complex was reported earlier by Brooker et al. [33, 34] (Fig. 8.15). At ca. 225 K, the complex undergoes a sharp half ST from the HS state, T2, to a state containing 50% HS and 50% LS, Af, isomers. The single-crystal structural analysis... 

Process development of the synthesis of iodoaniline 28 began with an improved synthesis of l-(4 -aminobenzyl)-l,2,4-triazole (6) (Scheme 4.7), which was prepared in the medicinal chemistry synthesis, albeit with poor regioselectivity (Scheme 4.1). We found that this aniline intermediate 6 could be readily prepared in three steps in >90% overall yield from 4-amino-l,2,4-triazole (30) and 4-nitrobenzyl bromide (4) based on a modified literature procedure [9]. The condensation of 30 and 4 in isopropyl alcohol followed by deamination gave the nitro... 

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