TRIAZOLYL GROUP

Other applicable imidazole-transfer reagents include JV V -sulfinyldiimidazole (B), diimidazolylsulfide (C) and tris(imidazolyl)phosphine (D). The 1,2,4-triazolyl group is transferred by A AT -sulfinyldi-1,2,4-triazole (E) or tris(l,2,4-triazolyl)phosphine (F). 

Activation of an oxygen function has also been accomplished by 4-chlorophenyl phospho-rodichloridate using a method in which 6-bromo-2-(pivaloylamino)pyrido[2,3-c/]pyrimidin-4(3//)-one (10) exchanges its 4-oxygen for a 1,2,4-triazolyl group.331... 

In contrast to the normal amino function which in nucleophilic substitution reactions is a rather poor leaving group, azolyl substituents represent a special case. Thus, the triazolyl group in 6-bromo-2-(pivaloylamino)-4-(l,2,4-triazoI-l-yl)pyrido[2,3-c/]pyrimidine (30) is substituted by a methoxy substituent.331... 

An early synthesis, published in 1983 and 1984 [83], requires three steps from 2-chloro-N-(2,4-dichlorophenyl)acetamide (Scheme 17.17). First, the amide group is transformed into imidoyl chloride with phosphorus pentachloride, followed by displacement of the two non-aromatic chlorine atoms by two equivalents of the potassium salt of 1,2,4-triazole. The triazolyl group borne by the imino bond being the best leaving group is replaced when reacted with a good nucleophile such as (4-chlorophenyl)methanethiol. The stereochemistry (E or Z) of the double bond is not stated in the literature. 

HBr added to a stirred mixture of p-methoxybenzyl 6,6-dibromopenicillanate la-oxide, a little PbBr2, and finely cut Al foil in 4 5 methanol/dichloromethane, and stirred at 30° for 3 h- p-methoxybenzyl penicillanate la-oxide. Y 95%. Chlorine, the 1,2,3-triazolyl group, and benzhydryl, methyl and allyl esters remained unaffected. F.e. inch reduction of 6-bromopenicillinates s. H. Tanaka et ah. Bull. Chem. Soc. Japan 62, 627-9 (1989). 

B. Yue, L. Yan, S. Han, L. Xie, Proton transport pathways in acid-base complex consisting of phosphonic acid group and 1,2,3-triazolyl group, J. Phys. Chem. B 117 (2013) 7941-7949. 

As already stated in SectionIIIA,trialkyl-andtriaryltinderivativesof pyrrole, pyrazole, and benzpyrazole are decomposed by water. The same holds for a few compounds in which two 1,2,4-triazolyl groups are bound to tin. In... 

Amino acids activated at the amino group by a benzotriazolide moiety react with amino acids under elimination of benzotriazole and C02 to give peptides. Reaction is achieved by warming up equimolar amounts of the components in anhydrous acetonitrile or aqueous acetone.[45] The benzotriazolylcarbonylamino acids are prepared from benzo-triazolyl-1-carboxylic acid chloride and amino acids.[46]... 

Structure determinations of several Fe(II) compounds of 2-triazolyl-l,10-phenanthroline and its methyl-substituted derivatives proved that in addition to the two nitrogen donor atoms of the 1,10-phenanthroline entity, the N-4 of the 1,2,4-triazole ring participates in coordination, even when a methyl substituent occupies the position adjacent to this donor atom [15, 16]. All compounds obtained exhibit Fe(II) spin crossover behaviour, its extent depending on the nature of the anionic groups and the solvent content. 

A -Aryl substituents which are activated by nitro groups can be removed by nucleophilic di.splacement of the triazolyl anion by potassium hydroxide or by hydrazine. Oxidative removal of a p-aminophenyl substituent by potassium permanganate has also been reported. ... 

Similarly, cyclization of 3-amino-l, 2,4-triazoles (65) with methyl propio-late or methyl phenylpropiolate gave a mixture of the l,2,4-triazolo[4,3-a]pyrimidin-7-ones 97 and the l,2,4-triazolo[l,5-a]pyrimidin-7-ones 98 (70CB3266 71CB2702). In addition, methyl tram-3-(3-amino-l,2,4-triazol-l-yl)acrylates (99) were also obtained. Production of the 1,2,4-triazolopy-rimidines 97 and 98 started by condensation of the ester function with the amino group of 65, followed by cycloaddition of the triazole N4 or N1 of the two tautomeric intermediates 96a and 96b, respectively, onto the carbon-carbon triple bond of the side chain. In contrast, formation of the triazolyl acrylates 99 took place through addition only of the triazole N1 onto the propiolate carbon-carbon triple bond. The relative amounts of products were found to depend on the reaction conditions (temperature, solvent, and time) (70CB3266) (Scheme 42). 

Triazole derivatives of the dichlobutrazole and paclobutrazole types are closely related chemically to the triazolyl-0,N-acetals previously mentioned. The oxygen atom of the acetal function was merely replaced by a methylene group. Dichlobutrazole (ICI) was developed for the control of powdery mildew, rust and scab in cereals. Paclobutrazole is under development as a growth regulator. 

Reaction of 5-halo-l,2,3-thiadiazoles with 1,3-diaminopropane leads to bis(l,2,3-triazolyl-l,2,3-thiadiazolyl)sulfide 105. Further intramolecular cyclization affords bis-[l,2,3]triazolo[l,3,7]thiadiazocine ring system 106 in 79% yield (Scheme 25 <20030BG4030>). The role of the ester groups on both the 1,2,3-triazole and 1,2,3-thiadiazole rings in the formation of the final product is essential. 

Diastereocontrolled reduction of amino ketones represents an attractive route to amino alcohols, many of which are pharmacologically important, and has been exhaustively reviewed. Even in the case of a-amino ketones, examples of high stereoselectivity were rare with conventional metal hydride reagents, and mixtures were common as the amino group became more distant. In contrast, a-triazolyl ketones (64) were reduced with high stereoselectivity by tetraalkylammonium borohydrides to the syn-alcohols (63) in dichloromethane or to the anti isomers (65) when titanium tetrachloride was added (Scheme 10). ... 

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