3- Hydroxy-l,2,4-triazole

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). 

Amino-3-oXY-l.2,4-triazole or 4-Amino-3-hydroxy-l 2,4-triazole[Called in Beil 4-Amino-1.2.4-triazolon-(5)], HC=N-NH or HC=N-N... 

The presence of catalytic tetrabutylammonium bromide was necessary for the reaction of sodium salt of l-phenyl-3-hydroxy-l,2,4-triazole M7 with l-(chloro-acetoxy)alkylphosphonates M3 to get better yields. The experiment also showed that this reaction was affected by reaction temperamre, base, and water. We observed that both the carboxylate ester bond and phosphonate ester bond in compounds M3 or IK were easy to cleave by hydrolysis in the presence of base and water at a higher temperature. It was found that the carboxylate ester bond was easier to cleave than the phosphonate ester bond in diethyl phosphonate however, the phosphonate ester bond was easier to cleave than the carboxylate ester bond in... 

All of IK showed very weak inhibitory activity (<20 % inhibition) against barnyard grass, crab grass, rape, setose thistle, cucumber, and lettuce for preemergence and post-emergence applications. It is noteworthy that there is no substituent on the benzene ring of l-phenyl-3-hydroxy-l,2,4-triazole moiety in IK. 

To a stirred mixture of phenyl hydrazine (1 mol) and urea (1 mol) in dimethyl benzene (500 mL), concentrated hydrochloric acid was added. The mixture was stirred at 135 °C for 2.5 h with a water separator to remove water. When the mixture was cooled to 90 °C, 85 % formic acid (2.5 mol) followed by concentrated sulfuric acid (0.25 mol) were added. The mixture was kept at 90 °C for 6 h and then the mixture was cooled. The solid was collected by filtration and washed by water, and dried at 100 °C in vacuo to give phenylhydrazide M6 as a white solid (mp 280-283 °C) in yield of 83 %. The hydrazide M6 (0.5 mol) was dissolved in 0.6 M NaOH solution and stirred for 1-2 h. The mixture was filtered and the solid product was dried at 100 °C in vacuo to give the sodium salt of l-phenyl-3-hydroxy-l,2,4-triazole M7 [19]. 

General procedure To a stirred solution of the appropriate (9,(9-dialkyl l-(chloroacetoxy)alkylphosphonates M3 (0.01 mol) in 50 mL of dry acetonitrile, sodium salt of l-phenyl-3-hydroxy-l,2,4-triazole M7 (0.01 mol) and tetrabutyl-ammonium bromide (0.4 mmol) were added at room temperature. The mixture was stirred at 40-50 °C for 4—5 h. The solid was filtered off and the filtrate was concentrated under reduced pressure. The residue was purified by column chromatography on silica gel and eluted with petroleum ether/acetone (2/1, v/v) to give the corresponding pure IK as yellow crystals or a sticky yellow liquid. A series of IK could be obtained by this procedure in yields of 66-85 % [19]. 

Iminoimidazolin-4-ones 227b are the only tautomers detected for 4-hydroxy-2-aminoimidazoles (R = H, Ph R = H) (91KGS62). Similar tautomeric forms are also characteristic of l-methyJ-2-imino-5-benzylideneim-idazole-4-one 228 (91KGS62) and 3-amino-l,2,4-triazol-5-ones 229 (R = R = H, COMe) (Scheme 78) [76AHC(S1), p. 482]. 

U,4-Triazol-3-ones Anhydro-3-hydroxy-l,2,4-triazolium Hydroxides) (200)... 

BAS 111 l-Phenoxy-3-(lH-l,2,4-triazole-l-yl)-4-hydroxy-5,5-dimethylhexane [9003-11-6] (BAS 111) (46) is a triazole that has plant growth inhibiting properties. It exerts its influence by inhibiting the production of gibberellic acid in plants this has been demonstrated in canola (31,37). 

Two 4-substituted 1,2,4-triazole 1-oxides, namely 2-(l -hydroxymethylene-2-oxo-l,2,3,4-tetrahydroquinoxaline-1-yl)-4-allyl-5-methylthio 1,2,4-triazole 1-oxide 530 (1984H695) and 4-hydroxy-l,2,4-triazole 1-oxide 531 (1995J CS(P1)243), (Scheme 157) derived from the parent species 528 (Scheme 156), have been described. The compounds were characterized by their H NMR and C NMR spectra. 

The behaviour of alkyl groups situated on the triazole ring is comparable with those of benzene thus their oxidation followed by decarboxylation has been much used in synthesis. Derived functions such as CH2X (X = OH, hal) also behave as expected cf. 55JA1538), but acetoxylation (Scheme 43) of 4-hydroxy-3-methyl-l,2,4-triazole (125) with acetic anhydride to give (126) is remarkable (70JPR610). 

Bis(hydroxymethyl)phosphonic acid esters that incorporated thymine were employed as a backbone to prepare short oligonucleotide chains. This chain was prepared by condensation of the bis(4,4 -dimethoxytrityl) protected phosphonic acid and iV or N -(2-hydroxyethyl)thymine in the presence of l-(2-mesitylenesul-fonyl)-3-nitro-l,2,4-triazole or by an Appel reaction with or N -(2-aminoethyl)thymine (89a-h). Selective removal of one DMT-group and phos-phitylation yielded the building blocks for solid supported synthesis of the short oligomers by the phosphoramidite approach. Holy has reported the synthesis of 8-amino and 8-substituted amino derivatives of acyclic purine nucleotide analogues. The 8-amino, 8-methylamino- and 8-dimethylamino-adenine and -guanine analogues of iV-(2-phosphonomethoxyethyl) and (S)-iV-(3-hydroxy-2-phosphono-methoxy-propyl) derivatives of purines (90a-i), were prepared by... 

There are also a number of reports on 1,2,4-triazine-to-1,2,4-triazole ring transformations initiated by the addition of nucleophiles at C-5 (68CR9041, 68CR1726 70BSF1590, 70BSFI599 72BSFI511 79JHC199). For instance, when treated with aqueous sodium hydroxide, 6-amino-l,2,4-triazine-3,5-dione (156) is converted into 3-hydroxy-1,2,4-triazole-5-carboxylic acid (157), as shown in Scheme 87. In a similar way, the... 

Hydroxy-4-(l-methyl-hydrazino)-l,3-thiazol geht in Gegenwart von waBrigem Ammoniak eine Umlagerung zum 5-Mercaptomethyl-l-methyl-3-oxo-2,3-dihydro-l,2,4-triazol ein1433 ... 

In one preparation of 5-methylamino-4-nitro-l-phenylpyridazin-6-one from the corresponding 5-hydroxy compound and aqueous methylamine, an equal amount of l-phenyl-3-nitropyrazole was obtained.563 4-Amino-3-halopyridazines with excess of potassium amide in liquid ammonia are rearranged to 4-cyanopyrazole (265), whereas the 3,6-dihalo analog gives 3-cyanomethyl-l,2,4-triazole (266).564 The proposed mechanism involves... 

Acid-catalyzed elimination of water from 6-hydroxy-2-phenyl-5,6-dihydrothiazolo[2,3-Z>][l,2,4]triazole (144) forms 2-phenylthiazolo[3,2-Z>][l,2,4]triazole (52) <87AP(330)528>. 

Acid catalyzed dehydration of l-[(3-phenyl-l,2,4-triazol-5-yl)thio-2-(5-hydroxy-5,6-dihydro-2-phenylthiazolo[3,2-Z)][l,2,4]triazol-6-yl)ethene (145) brings about aromatization and formation of a new fused ring, giving 2-phenyl-6-(2-phenyl-5,6-dihydrothiazolo[3,2-Z7][l,2,4]triazol-5-yl)thia-zolo[3,2-Z)][l,2,4]triazole (146) (Equation (30)) (see Section 8.05.9.1.9) <87AP(320)528>. 

Most photographic materials contain 7-hydroxy-5-methyl-l,2,4-triazolo[l,5-a]pyri-midine (65) as an emulsion stabilizer. It is prepared by cyclocondensation of ethyl acetoacetate with 3-amino-l,2,4-triazole [276]. 

Saloutin, Chupakhin et al. applied a related condensation involving 1,2,4-triazolyldiazonium resulting in the formation of 6-benzoyl-7-hydroxy-7-triflu-oromethyl-4,7-dihydro[l,2,4]tiiazolo[5,l-c][l,2,4]triazine 151 (59 %) [132], Rusinov et al. reported on another successful example of this reaction involving lithium p-diketonates and 3-amino-l,2,4-triazole and affording 7-fluoromethyl-l,2,4-triazolo[l,5-a]pyrimidine 152 [133]. 

IK could be synthesized by the reaction of l-(chloroacetoxy)alkylphosphonate M3 with the sodium salt of l-phenyl-3-hydroxy-1,2,4-triazole M7 (Scheme 2.22). 

As shown in Scheme 2.22, phenyl hydrazine reacted with urea to give phen-ylhydrazide M6. Condensation of M6 with formic acid followed by addition of concentrated sulfuric acid gave l-phenyl-3-hydroxy-1,2,4-triazole M6 which was converted to the sodium salt of l-phenyl-3-hydroxy-1,2,4-triazole M7. l-(Chloro-acetoxy)alkylphosphonates M3 were prepared from 0,0-diaIkyl 1-hydrox-yalkylphosphonate M2 and chloroacetic chloride in the presence of pyridine. IK-l-IK-7 in Table 2.52 could be obtained by the reaction of M7 with M3 in acetonitrile using tetrabutylammonium bromide as a catalyst. The systhestic procedures of M3 and M7 are introduced in the Sects. 9.1.4 and 9.1.8, respectively. 

---