4-Amino-1,2,3-triazoles synthesis

Fig. 4.6. Dependence of on time for 3,5-diphenyl-4-amino-triazole synthesis at 130 °C.

Synthesis of the amino-triazole derivative (43) was performed in the authors laboratory by Pati et al. [52] (Scheme 7). Substituted benzyl bromide was reacted with triphenylphosphine to produce the phosphonium bromide starting material, 44. The Wittig reagent, obtained by treatment with sodium hydride, was reacted with 3,4,5-trimethoxybenzaldehyde 18 to generate the nitro-stilbene 45 in good yields. The alkyne 46 was obtained by bromination of the stilbene, followed by didehydrobromination. Compound 46 was then reacted under thermal conditions with benzyl azides... 

Vilsmeier reaction, 4, 1051 Furo[3,2-6]pyrroles MO calculations, 6, 979 synthesis, 4, 1069 6, 1009 Furo[3,4-a]pyrrolo[2,1,5-cd]indolizine nomenclature, 1, 22 Furopyrylium salts, 4, 993-995 Furoquinolines biosynthesis, 4, 992 occurrence, 4, 988 pharmacology, 4, 992 reactions, 4, 988 synthesis, 4, 989 Furo[3,2-c]quinolines, 4, 991 Furo[3,4-fe]quinoxaline, 1,3-diphenyl-synthesis, 4, 993 Furoquinoxalines, 4, 992 Furo[2,3-6]quinoxalines synthesis, 4, 992 Furosemide toxicity, 1, 136 Furospinulosin UV spectra, 4, 587 Furospongin-I mass spectrometry, 4, 583 Furo[3,4-d][l,2,3]triazole, 2,6-dihydro-synthesis, 6, 996 Furo[3,4 -d][ 1,2,3]triazoles synthesis, 6, 996 Furoxan, 4-amino-3-aryl-tautomerism, 6, 404 Furoxan, 4-amino-3-methyl-synthesis, 4, 414 Furoxan, 4-aryl-3-methyl-rearrangement, 6, 408 Furoxan, 3-aryl-4-nitro-synthesis, 6, 414 Furoxan, 4-benzoyl-3-methyl-oxime... 

The formation of relatively unstable amino-1,2,3-triazolines (3.1>7) from enamines is another traditional route employed for trisubstituted 1,2,3-triazole synthesis. Munk and Kim demonstrated the great regiospecificity of such reactions (Eq. 8). " Pocar and his collaborators have extended the use of enamines, including the following examples (Eqs. 9,10). - An especially interesting example involves an acid-catalyzed rearrangement (Eq. 11). ... 

Dimroth Triazole Synthesis Methyl 5-amino-l-(4-iiitrophenyl)-liy-l,23-triazoIe-4-carboxylate (18) ... 

Triazoles and Benzotriazoles.—1,2,3-Triazoles. The X-ray structure of the amino-triazole ester (603) has been reported. " A new general synthesis of 1-alkyl-u/c-triazoles is exemplified by the reaction of the lithiated nitrosoamine LiCH2NMeNO with benzonitrile to yield (604). The bis-toluene-p-sulphonyl-hydrazone of benzil cyclises to the triazole (605) in in the presence of mercury(ii)... 

An experimental and theoretical investigation of electronic effects in ruthenium catalyzed cycloadditions with internal diarylalkynes has shown that 5-electron-donating group substituted triazoles should be favored [155]. This effect was further observed in the synthesis of 5-amino-triazoles from ynamides (Scheme 65) [156]. 

Pyrazolino[2,3-c][l,2,3]triazoles, 5, 702 Pyrazolium hydroxide, l,2-dimethyl-3,5-diphenylanhydro-4-hydroxy-IR spectra, 5, 201 Pyrazolium salts dequatemization, 5, 269 H NMR, 5, 185 hydrogen exchange at ring carbon, 5, 245 mesoionic compounds, 5, 171 nitrodebromination, 5, 237 reactivity, 5, 217 reduction, 5, 68, 243 synthesis, 5, 156 UV spectra, 5, 199 Pyrazolium salts, amino-reactions, 5, 262 Pyrazolium salts, bromo-nucleophilic displacements, 5, 266 Pyrazolium salts, 1,2-dimethyl-deuteration, 5, 175, 245 hydrogen exchange, 5, 71 acid-catalyzed, 5, 239 reactions... 

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). 

Regarding the series of hetero aromatic pentacyclic compounds with three heteroatoms, an accelerated synthesis of 3,5-disubstituted 4-amino-1,2,4-triazoles 66 under microwave irradiation has been reported by thermic rearrangement of dihydro-1,2,4,5 tetrazine 65 (Scheme 22). This product was obtained by reaction of aromatic nitriles with hydrazine under microwave irradiation [53]. The main limitation of the method is that exclusively symmetrically 3,5-disubstituted (aromatic) triazoles can be obtained. 

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>. 

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... 

Tandem azidination- and hydroazidination-Hiiisgen [3 +2] cycloadditions of ynamides are regioselective and chemoselective, leading to the synthesis of chiral amide-substituted 1,2,3-triazoles <06OBC2679>. A series of diversely l-substituted-4-amino-l,2,3-triazoles 132 were synthesized by the copper-catalyzed [3+2] cycloaddition between azides 130 and ynamides 131 <06T3837>. 

Superheating of the solvent was believed to be responsible of the observed rate enhancement under microwave irradiation in the synthesis of 3,5-disubstituted 4-amino-1,2,4-triazoles when conducted in 1,2-ethylene glycol as (polar) solvent (Eq. 4) [32]. 

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