I - -l ,2,4-triazole

Following on the triazole mohf a series of new iridium(I) l,2,4-triazole-3-ylidene NHC complexes [lr(cod)(NHC)L]BF4 (56a-c, L=PPh3, pyridine Scheme 4.23) were synthesized and tested and good results found for TH on C=0, C=N and C=C double bonds in 2-propanol with K2CO3 [52]. 

There are some literature reports on the reactions of 1,2,4-triazoles. 2-Amino-4-aryl-5-( I //-l, 2,4-triazol-1 -yl)thiazolc derivatives were synthesized from the reaction of a-bromo substituted acetophenone and thiourea <07SC199>. 5-Amino-l-methyl-l//-[l,2,4]triazole-3-carboxylic acid were employed as precursors in peptide synthesis <07SC1917>. 3-... 

In the solid state 6-hydroxy-2-phenyl-5,6-dihydrothiazolo[3,2- )][l,2,4]triazole (63) is the form present. In solution an equilibrium appears to exist with the chain form (5-phenyl-[l,2,4]triazol-3-yl)thioacetaldehyde (64). Reactions of both the bicyclic form (63) (see Section 8.05.6.1.3 and 8.05.7.3) and the chain form (64) have been observed. When treated with sodium hydroxide, the compound reacts in its chain form (64) as an aldehyde undergoing aldol condensation to give compound (65) <87AP328>. Boiling compound (65) in ethanol converts it into its ring tautomer (66) (Scheme 1) <87AP328>. Both tautomers (65) and (66) by treatment with sulfuric acid are converted into 2-phenyl-6-(2-phenyl-5,6-dihydrothiazolo[3,2-A][l,2,4]triazol-5-yl) thiazolo[3,2-i][l,2,4]triazole (146) (see Section 8.05.7.4 and 8.05.9.1.9) <87AP328>. 

Hydrazine and primary amines induce ring opening of the thiazole ring of 5,6-dihydrothiazolo[3,2-i][l,2,4]triazole-6-ones (105) forming the respective 2-([l,2,4]thiazol-2-yl)alkanoic acid hydrazides and amides (125) (Equation (23)) <83JPR869>. 

By treatment with alkaline hydrogen peroxide 3,7,7a-trimethyl-2,3,5,6,7,7a-hexahydro-l//-imid-azo[l,5-i>][l,2,4]triazole-2,5-dithione (142) is converted into the corresponding -2,5-dione (143) (Equation (28)) <93TH 805-01, 95FES379>. 

Imidoyl chlorides (303) react with primary aromatic amines to give 2,3-diaryl-5-phenyl-3//-imidazo[l,2-i][l,2,4]triazoles (304) (Equation (88)) <89JCR(S)262>. 

The cyclocondensation of 3-(2,4-dichlorophenyl)-5-sulfonyl[l,2,4]triazole (345) with chloroacetic acid affords 2-(2,4-dichlorophenyl)-5,6-dihydrothiazolo[3,2-i][l,2,4]-triazol-6-ones (346) (Equation (109)) <9iH(32)23i>. The same reaction in the presence of an aromatic aldehyde gives rise to 6-arylidene-2-(2,4-dichlorophenyl)-5,6-dihydrothiazolo[3,2-6][l,2,4]triazol-6-ones (103) (see Section 8.05.6.2.1) <91H(32)231>. 

Hydrazidoyl halides react with 2-amino[l,2,4]triazole to give 5-substituted 6-arylhydrazono-6//-imidazo[l,2-i][l,2,4]triazoles (350) and 6-arylhydrazono-5,6-dihydro-4//-imidazo[l,2-/>][ 1,2,4]-triazol-5-ones (351), respectively the latter products are not determined with respect to the tautomeric structures of the H-, 3H-, or 4/7-form (Scheme 32) <83JHC639>. 

The reaction of the a-ketohydroximoyl chlorides converts 2-amino[l,2,4]triazole into a mixture of 5-aryl-6-nitrosoimidazo[l,2-i][l,2,4]triazoles (352) and 3-aroyl-5/f-[l,2,4]triazolo[3,2-c][l,2,4j-triazoles (353) (Equation (112)) <84JHC1029>. 

The electrolysis of the 4-nitrophenylhydrazone of 4-dimethylaminobenzaldehyde generates the corresponding diarylnitrilimine intermediate (156) which in the presence of [l,2,4]triazole (155) undergoes 1,3-dipolar cycloaddition to give the 7,7a-dihydro-lFf-[l,2,4]triazolo[4,3-i]-[l,2,4]triazole (157) (Equation (45)) <85ZC443>. 

In the reactions of iminophosphoranes with carbonyl and unsaturated compounds, both normal and abnormal aza-Wittig processes can be observed. Thus, the tandem aza-Wittig reaction of the iminophosphorane (6 with isocyanate or CS2 generated the 3,5-dthydro-6/f-imidazo[l,2-6]-l,2,4-triazol-6-ones in satisfactory yields, and the vinyl iminophosphorane (6 was transformed by normal aza-Wittig reactions to carbodiimides (as part of the synthetic route to 3,5-dihydro-6//-imidazo[l,2-i)]-l,2,4-triazol-6-ones). By contrast, a re-examination of the reaction of the iminophosphorane (67) with the aromatic isocyanate PhNCO showed that it gives an unexpected mixture of carbodiimides." In another example (Scheme 5), the... 

Triazole has been prepared by the oxidation of substituted 1,2,4-triazoles, by the treatment of urazole with phosphorus pentasulfide, by heating equimolar quantities of formyl-hydrazine and formamide, by removal of the amino function of 4-amino-l,2,4-triazole, by oxidation of l,2,4-triazole-3(5)-thiol with hydrogen peroxide, by decarboxylation of 1,2,4-triazole-3(5)-carboxylic acid, by heating hydrazine salts with form-amide,by rapidly distilling hydrazine hydrate mixed with two molar equivalents of formamide, i by heating N,N -diformyl-hydrazine with excess ammonia in an autoclave at 200° for 24 hours, and by the reaction of 1,3,5-triazine and hydrazine monohydrochloride. ... 

Most 3-hydroxy-l,2,4-triazoles exist in the hydroxy form 123 [76AHC(S1), pp. 377,389 84CHEC-I(5)733]. An exception is the 5-nitro derivative, which in the solid state possesses the 0x0 structure 124 (97JPC3605). 

Similarly to aminoazoles, diaminoazoles prefer their amino forms 210 for 3,5-diaminopyrazole [76AHC(S1), p. 460 84CHEC-I(5)167 96CHEC-11(3)1] 211 for 3,5-diamino-l,2,4-triazole and 212 for 3,5-diaminoisothiazole [76AHC(S1), p. 460]. Ilie triamino structure 213 was proven by an X-ray crystallographic study of 4-aminoquinazine hydrobromide [73JCS(P2)lj. 

Diazotization of 5-amino[l, 2,3]triazole 692 afforded (88BSB179) triaz-olo[l, 5-i>][l, 2,4]triazine 694 as a result of a Dimroth rearrangement of the initially formed isomeric structure triazolo[5,l-c][l,2,4]triazine 693. Molecular structure of 694 was determined by single X-ray diffraction (Scheme 146). 

The extranuclear C-nitrosoquinoxalines are typified by 3-(a-methoxycarbonyl-a-nitrosomethyl)-2(l/i)-quinoxalmone (66), made by nitrosation of 3-(methoxy-carbonylmethyl)-2(l/f)-quinoxalmone (65) [AcOH, CI3CO2H, C5H11ONO, 20°C, 3 h 91% spectra suggest that the hydroxyimino tautomer (67) may predominate] and was subsequently reduced to afford 3-(a-amino-a-methoxycarbonylmethyl)-2(l//)-quinoxafinone (68) (PtOa, H2, 1 atm, THF, EtOH, 20°C, 4 h 59%) also by 3-[a-(4-amino-5-methyl-4//-l,2,4-triazol-3-yl)-a-nitrosomethyl]-2(l//)-quinoxa-linone (69, R = NO), prepared by nitrosation of 3-(4-amino-5-methyl-4//-1,2,4-triazol-3-ylmethyl)-2(177)-quinoxalinone (69, R = H) [NaN02 ( 1.25 equiv), AcOH, H2O, no further details 79%]." ... 

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. ... 

Tebuconazole (provided by Bayer), Q -[2-(4-chlorophenyl)ethyl]-o -(l,l-dimethyl-ethyl)-li/-l,2,4-triazole-l-ethanol. Molar mass 307.8, (M- -H)+ ion observed at approximately m/z 308.1 [liquid chromatography/mass spectrometry (LC/MS)] Tebuconazole-fnflzoZe-i,2,4-- fV3 (provided in acetonitrile solution by Bayer), [ NsJtebuconazole stable-isotope internal standard, o -[2-(4-chlorophenyl)ethyl]-Q -(l,l-dimethylethyl)-li/- A3-l,2,4-triazole-l-ethanol. Molar mass 310.8, (M -I- H)+ ion observed at approximately m/z 311.1 (LC/MS)... 

US patent 6,713,481, Crystalline antifungal polymorph [104]. This patent discloses the crystalline polymorph Form I of ( )-4-[4-[4-[4-[[(2R-cA)-5-(2,4-difluoro-phenyl)tetrahydro-5-( 1H-1,2,4-triazol- l-ylmethyl)furan-3-yl]methoxy]phenyl]-1 -piper azinyl]phenyl-2,4-dihydro-2-[(S)-l-ethyl-2(S)-hydroxylpropyl]-3H-l,2,4-triazol-3-one,... 

Microwave irradiation of a reaction mixture containing aromatic nitriles, hydrazine hydrate, hydrazine dihydrochloride, and ethylene glycol as solvent in a one-pot process gave 3,5-disubstituted 4-amino-l,2,4-triazoles 98a-i in excellent yields (Equation 35 and Table 14) <2000TL1539>. 

Two kinds of pyrazolotriazole magenta dyes are used in color photographic materials. One is the I //-pyrazolo[5,1 -r]-[l,2,4]triazole skeleton, and the other is the l//-pyrazolo[ 1,5+][ 1,2,4]triazole skeleton as shown in the representative azomethine dye 1 (Figure 1) <1994J(P2)531>. 

SNSI (Dibenzothiazol-2-yl)tetraazathiapentalene 15 < 2004EJ04203> NNSI 6-(4 -methoxyphenyl)thiazolo-[3,2- ][l,2,4]triazol-5-yl (/i-tolyl)methanone 16 <20000L429> (Figure 3), 6-(4-nitrobenzyl)-2-phenylthiazolo[3,2- ]-[l,2,4]triazole 17 <2005TL1607>, 5-benzylidene-2-(2 -cholorophenyl)thiazolo[3,2- ][l,2,4]triazol-5(677)-one 18... 

Synthesis of fused [l,2,4]triazoles with the same heteroatomic arrangement (i.e., [l,2,4]triazolo[2,3- /][l,2,4]tri-azines) has been published also by Heravi et al. <2005JHC1021>. These authors found that the IV-aminotriazinone... 

A/ -ally derivative + /V4-allyf (4.5%) derivative.r /V -prop-l-cnyl derivative. /V -propargyl derivative. Unstable N-azolylallene formed. bis-l,2,4,-triazol-I-yImethanc. Addition of alumina increases yield (81%)and totally inhibits isomerism.w Af -allyl (61%) + A -allyl (24%) derivatives. With K CO, (20 mmol) and RX (10 mmol) at 80°C for... 

Acylaminobiguanides are cyclised by alkalis without difficulty, with loss of water, to 5-guanidino-l,2,4-triazoles. Their interaction with formic acid affords the expected guanamines in the majority of examples 391, 392) (see also Section VII, I). Contrary to a previous claim 91), isonicotinic acid hydrazide dihydrochloride and cyanoguanidine do not give the biguanide under neutral conditions, but form merely a molecular adduct of the reactants 416). 

Interest in polynitroarylenes has resumed over the past few decades as the demand for thermally stable explosives with a low sensitivity to impact has increased. This is mainly due to advances in military weapons technology but also for thermally demanding commercial applications i.e. oil well exploration, space programmes etc. Explosives like 1,3-diamino-2,4,6-trinitrobenzene (DATB) (13), l,3,5-triamino-2,4,6-trinitrobenzene (TATB) (14), 3,3 -diamino-2,2, 4,4, 6,6 -hexanitrobiphenyl (DIPAM) (15), 2,2, 4,4, 6,6 -hexanitrostilbene(HNS, VOD 7120 m/s, = 1.70 g/cm ) (16) and A,A -bis(l,2,4-triazol-3-yl)-4,4 -diamino-2,2, 3,3, 5,5, 6,6 -octanitroazobenzene (BTDAONAB) (17) fall into this class. TATB is the benchmark for thermal and impact insensitive explosives and finds wide use for military, space and nuclear applications. 

Alkenylidene cyclopropanes react readily with 246 to yield 1,4-diazo-bicyclo[3,3,0]oxtanes, whereas methylidene cyclopropane reacts only very slowly with 246 to yield a 2 + 2 cycloadduct (73AJ1553). Compound 246 also reacts with 5-methylfuran-2(3//)-one in an acyl-ene reaction to yield 7-acetyl-6,7-dihydro-2-phenyl-2.ff-pyrazolo[I,2-a]-l,2,4,-triazol-l,3, 5-trione [80JCS(P1)843]. 

Not surprisingly, it is rather difficult to separate the different contributions of the different interactions as they occur in the micellar Stern region. In an attempt to solve this problem, the group of Engberts used a series of hydrolysis reactions of activated esters and amides to probe the reaction environment offered by micelles. The reactions initially involved the water-catalyzed pH-independent hydrolysis reactions of i-methoxy-phenyl dichloroacetate 4 and l-benzoyl-3-phenyl-l,2,4-triazole 5, as extensive information on the rate retarding effects of added cosolutes on this reaction was available. ... 

R> = Me, R = R3 = Ph, K = H, R = N=CHAr), which with ammonia in chloroform solution give novel derivatives (224) of meso-ionic l,2,4-triazol-3-imines (216). These compounds are of interest in that they belong to a new type of meso-ionic heterocycle in which the exocyclic substituent f (see Table I) is a stabilized carbanionoid residue,... 

The NMR spectra and dipole moments of l,2,4-triazole-3-thiones support their meso-ionic formulation (227). For example, the compound (227, R = Me, R = R = Ph) has a dipole moment of 9.1 D in dioxan solution. The effect of solvent polarity upon the ultraviolet and visible spectra of the triphenyl derivative (227, R = R = R = Ph) has been reported but no direct interpretation was made. The meso-ionic l,2,4-triazole-3-thiones (227) form hydrochlorides (234, R = H, X = Cl) and methiodides (234, R = Me, X = I) they yield 1,2,4-triazolidine-3-thiones by lithium aluminum hydride reduction. ... 

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