4H-1,2,3-Triazoles

Three plausible mechanisms were postulated to explain these observations the free nitrene route (pathway a), Ng extrusion in concert with three-membered ring formation (pathway b), and cyclization to a 4H-1,2,3-triazole followed by rearrangement to azirine (pathway c). ... 

Chloro-2-(3-methyl-4H-1,2,4-triazol-4-yDbenzophenone (Oxidation of 7solution prepared by adding sodium periodate (2 g) to a stirred suspension of ruthenium dioxide (200 mg) in water (35 ml). The mixture became dark. Additional sodium periodate 18 g) was added during the next 15 minutes. The ice-bath was removed and the mixture was stirred for 45 minutes. Additional sodium periodate (4 g) was added and the mixture was stirred at ambient temperature for 18 hours and filtered. The solid was washed with acetone and the combined filtrate was concentrated in vacuo. The residue was suspended in water and extracted with methylene chloride. The extract was dried over anhydrous potassium carbonate and concentrated. The residue was chromatographed on silica... 

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... 

Oxazole Isoxazole 1,2,4-Triazole 4H-1,2,4-T riazole 1H-1,2,3-T riazole 2H-1,2,3-Triazole... 

Oxo-8-phenylhydrazono-3a,4,7,8-tetrahydro-4H-(indazolo[4.5-c]furazan> wird mit Alkalimetall-Laugen bei 20° zu 8-Hydroximino-4-oxo-2-phenyl-2,4,5,8-tetrahydro-(indazoto[5,6-d]-1,2,3-triazol) umgesetzt94 ... 

Structures of guanazo- and pyroguanazoles, and reaction of dicyandiamide with 3-amino-5-substituted-4H- 1,2,4-triazoles)... 

CA Registry No [288-36-8]. This structure also exists as the tautomeric forms, 2H-1,2,3-Triazole with a CA Registry No [288-35-7], and in a 4H-form, which is relatively rare... 

The 1,3-dipolar cycloaddition of azidoalkylphosphonates to enamines afforded A2-1,2,3-triazoles which are further converted to the 1,2,3-triazoles [95H(40)543] fused triazoles are similarly obtained when a cyclic enamine was employed. Fused 1,2,3-triazole (88), a xanthine oxidase inhibitor, was prepared by the reaction of an alkyl azide with cyanoacetamide with further elaboration of intermediate (87) by treatment with HMDS in xylene [95FES257]. The fused 4H-l,2,3-triazolo[l,5- ][l,4]benzodiazepin-6(5H)-one (90) was obtained from propargylamide (89) via an intermediate azide [95S647]. 

Cyclopropan 1-Azido-l-dimethyl-amino- E17b, 1593 (OH - N3) Guanidin 4-Cyan-l-propyl- E4,1299 (OR - NH-C3H7) lH-Tetrazol 1-Butyl- E8d, 679 [HC(OR)3 + R-NH2/NaN3] 4H-1,2,4-Triazol... 

H-1,2,4-Triazol 5-(2-Aminocar-bonyl-hydrazino)-3-phenyl-E16a, 786 (Ringschl.)... 

Irradiation of 2H-1,2,3-triazoles (91) in ether gives 22% MeCN, and in the presence of excess cyclopentene it affords the adduct (92) (68CC977). 4H-Triazolines (93) bearing methoxycarbonyl and alkyl groups at the j3 -position give, on thermolysis, 2H- 1,2,3-triazoles (94) and/or 3-amino-2i/-azirines on photolysis, only azirines are formed (80CC940). 

Few examples of photocycloaddition of the nitrogen-nitrogen double bond to alkenes are known and these are usually restricted to molecules in which the double bonds are held in close proximity to each other. A hitherto unknown [6 + 2] intramolecular addition to a benzene ring has been reported in the azoalkane (141) which is converted on irradiation into the 1, 2-diazetidine (142). Irradiation of 4-phenyl-4H-1,2,4-triazole-3,5-dione (143) in the presence of naphthalene, however, affords the [4 + 2] photoadduct... 

Ainino-4-mcrcapto-3-methyl-l-phenyl- 660 5(3)-(4-Amino-5-mercapto-4H-1.2.4-triazol-3-yl)-... 

AHMT (4-amino-3-hydrazino-5-mercapto-4H-1,2,4-triazole) reacts on aldehydes in strongly alkaline media to form a colorless intermediate product. This product is oxidized by atmospheric oxygen to give a purple-colored dye. The resulting chromophore has four conjugated double bonds the molecular formula shown in Eq. (4) is one of... 

An improved synthesis of 5-substituted 4-amino-3-mercapto-(4H)-1,2,4-triazoles (105) has been reported which involves the reaction of thiocarbohydrazide with carboxylic acids at the melting temperature. The crude triazoles (105) then provided easy access to the 3,6-disubstituted l,2,4-triazolo[3,4-b][l,3,4]thiadiazoles (106) by reaction with carboxylic acids or their acid chlorides <97JHC1255>. 

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