4 Phenyl 5-anilino-1 ,2,3-triazole

Ogata, Y., Takagi, K., Hayashi, E. Photochemical Dimroth rearrangement of 1,4-diphenyl-5-amino- and 4-phenyl-5-anilino-1,2,3-triazoles. 

Nitron (4.5-Dihvdro-l, 4-diphenyl-3,5-phenyl-imine-1,2,4-triazole, or l,4-Diphenyl-3,5-endo-anilino-4,5-dihydro-l, 2,4-triazole). N C(NFh>2.CH.N.Ph, C20H16N4, mw 312.36 ... 

Morpholino-3-[4-phenyl(thiosemicarbazido)carbonyl]quinoxaline (129) gave 2-morpholino-3-(4-phenyl-5-thioxo-5,6-drhydro-4//-l,2,4-triazol-3-yl)quin-oxaline (130) (2M NaOH, reflux, 3 h 35%), 2-(5-anilino-l,3,4-thiadiazol-2-yl)-3-morpholinoquinoxaline (131, X = S) (98% H2SO4, 0°C, 1 h, then 20°C, 12 h 89%), or 2-(5-anilino-l,3,4-oxadiazol-2-yl)-3-morpholinoquinoxaline (131, X = O) (NaOH, H2O, EtOH, I/Kii dropwise, 5°C 95°C, 4 h 81%) analogs of all three products were made similarly. ... 

The present method is a modification of that first reported by Dim-roth.6 The method of irreversible isomerization in boiling pyridine was first reported by Dimroth 7 for the conversion of l-phenyl-5-amino-1,2,3-triazole to 5-anilino-l,2,3-triazole. 

B. 4-Phenyl-5-anilino-l,2,3-triazole. Six grams (0.025 mole) of 1,4-diphenyl-5-amino-l,2,3-triazole is dissolved in 20 g. of dry pyridine (distilled from solid sodium hydroxide) and heated under reflux for 24 hours (Note 6). The reaction mixture (Note 7) is poured into 11. of ice water. The product separates as a slightly yellowish milky oil which is converted to white needle-like crystals by stirring the mixture and scratching the beaker with a glass rod. The product is collected by suction filtration, washed with water, suction-dried, and recrystallized from aqueous ethanol (Note 8). The yield is 5.5-5.6 g. (92-93%) of fine white needle-like crystals, m.p. 167-169° (Note 9), soluble in hot water and ether, but difficultly soluble in benzene. 

The yield and purity of the product, i.e., with respect to decreased content of acidic isomer (4-phenyl-5-anilino-l,2,3-triazole), depends upon maintaining a low temperature throughout the entire reaction. 

The reaction of 2-anilino-l,4-naphthoquinone 374 with benzoylacetic acid hydrazide gives 3-hydrazino-pyrazolyl derivative 375, that is acetylated to produce 5-[[l,4-dihydro-l,4-dioxo-3-(phenylamino)-2-naphthalenyl]sulfonyl]-3-methyl-6-phenyl-5/7-pyrazolo[5,l-c][l,2,4]triazole 51. This latter derivative is also obtained in 51% yield from reaction of 374 with benzoylacetic acid hydrazide in the presence of a mixture of acetic acid-sodium acetate <2004PS(179)1907> (Scheme 39). 

Oxidation of 5-anilino-4-phenyl- -triazole may give a 4 -triazolone derivative as an intermediate (Scheme 39). ... 

The effects of the 1,2,3-triazole and 1-amino-1,2,3-triazole heterocycles on the chemical shift of the carbon atoms in the phenyl ring of compounds (40) and (41) (X = H) are compared with the value for benzene. With regard to the effects of substituent X para and meta) on the 1,2,3-triazole carbons, C(4) is deshielded by electron-withdrawing groups, whereas C(5) is shielded. Reasonable correlations with Hammett a values are observed for the chemical shifts of both C(4) and C(5) of (41) <86MRC53>. The chemical shifts of C(4) and C(5) in 5-amino-l-aryl-l,2,3-triazoles are shifted upheld by 2-5 ppm compared with the corresponding 5-anilino-1,2,3-triazoles. In 5-anilino-... 

Ethyl-2-hydrazino- E16a. 750 (Cl - NH-NH2) 3-Methyl-2-(l-methyl-hydrazino)-E16a, 750 (Cl - NR —NH2) Triazen 3-(Cyan-methyl)-3-methyl-3-(4-methyl-phenyl)- El6a. 1196 (Ar —Nf + Amin) lH-l,2,3-Triazol 3-Anilino-5-ethyl- E8d, 484 [H5C2-CO-NH-NH-C( = NH) - NH - Ar/Base] 5-Methyl-3-(4-methyl-anilino)- E8d, 484 [H3C-CO-NH-NH-C( = NH) - NH - Ar/Base]... 

Similarly, the 2-azidoethylene-l,l-dicarbonitriles (92) were found to react with aniline to give the corresponding anilino derivatives 121 Reaction of phenyl ethynyl ketone with sodium azide in an aqueous medium, it will be recalled, gave the isoxazole 74 (R = H). When this reaction was carried out in dimethylformamide, quite different results were found in this case the sodium salt of 4-benzoyl-1,2,3-triazole was isolated in good yield . The formation of this product... 

Amino-1-methyl-1,2,3-triazole-5-carbonitrile, when refluxed in pyridine with phenyl isothiocyanate, gave 6-anilino-7-methyl-8-azapurine-2-... 

Irradiation of 4-amino-3,5-diphenyl-1,2,3-triazole, in ethanol with a high-pressure mercury lamp for 40 hr, gave an equilibrium mixture of starting material and the Dimroth-rearrangement product, 4-anilino-5-phenyl-l,2,3-triazole (35% yield), separated by thin-layer chromatography. When the product was similarly irradiated, the equilibrium was reestablished (see also... 

Several addition reactions of unsaturated phosphonic and phosphinic esters have been reported during the course of the year. Dithiophosphoric acids add to 2-alkoxy-vinylphosphine esters in the expected manner, and in the addition of phenyl azide to vinylphosphonates, the initial triazole (95) may be thermolysed to a C-phosphory-lated aziridine, but in the presence of triethylamine the final products are 2-anilino-vinylphosphonates. ... 

Upon UV irradiation, ethyl 5-amino-l-phenyl-l,2,3-triazole-4-carboxylate (40) does not expel N2 to give ketenimines or aziridines. Instead, in the presence of triphenylene as photosensitizer, 40 is smoothly isomerized, as a first example of a photo-Dimroth rearrangement,163 to ethyl 5-anilino-1,2,3-triazole-4-carboxylate (298).164 The mechanism is explained by a radical rearrangement, e.g., 2971-297III (cf. Scheme 81). This isomerization type was observed also with 5-amino-1,4-diphenyl-1,2,3-triazoles.165... 

Heating 4-substituted 5-amino-l-phenyl-1,2,3-triazole (277) in acetic anhydride afforded the acetyl derivative of the isomeric 4-substituted 5-anilino-1,2,3-triazole (278). However, the anilino isomers and their acetyl derivatives retrogress to the acetyl derivatives of the amino compounds on prolonged heating in acetic anhydride [71 JCS(C)706] (Scheme 90). 

Reaction of phenyl azide and benzyl cyanide (in EtOH in the presence of EtONa at r.t.) surprisingly does not lead to the expected product of a 1,3-dipolar cycloaddition (A), but to 5-amino-l,4-diphenyl-l,2,3-triazole (B, 80%). Triazole B isomerizes readily on heating in pyridine solution to give 5-anilino-4-phenyl-1,2,3-triazole (C). 

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