Benzotriazoles reaction

Benzolriazine, 3-hydrazino-cyclization with orthoesters, 59, 141 reaction with nitrous acid, 59, 152 Benzotriazoles, reaction with 6-azido-uracils, 55, 186 Benzotriazole chlorination, 59, 272 fluorination, 59, 272 2W-Benzotriazoles, 2-aryl-4-arylazo-,... 

As we saw briefly in Chapter 53, the photochemical version of the Graebe-Ullmann carbazole-carboUne synthesis can be an excellent route to these heterocycles. Similar to this benzotriazole reaction is the photolysis of aryl azides to give carbazoles and related fused indoles. 

UVA 2,2 -dihydroxy-4-methoxybenzophenone 2-(2H-benzotriazol-2-yl)-p-cresol 2-benzotriazol-2-yl-4,6-di-tert-butylphenol phenol, 2-(5-chloro-2H-benzotriazole-2-yl)-6-(1,1 -dimethylethyl)-4-methyl- 2-(2H-benzotriazole-2-yl)-4,6-di-tert-pentylphenol 2-(2H-benzotriazole-2-yl)-4-(1,1,3,3-tetraethylbutyl)phenol 2-(2H-benzotriazol-2-yl)-4,6-bis(1 -methyl-1 -phenylethyl)phenol 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol, branched linear 2,4-di-tert-butyl-6-(5-chloro-2H-benzotriazole-2-yl)-phenol 2-(3-sec-butyl-5-tert-butyl-2-hydroxyphenyl) benzotriazole reaction product of methyl 3(3-(2H-benz-otriazole-2-yl)-5-t-butyl-4-hydroxyphenyl propionate/PEG 300 ethyl-2-cyano-3,3-diphenylacrylate (2-ethylhexyl)-2-cyano-3,3-diphenylacrylate N-(2-ethoxyphenyl)-N -(4-isododecylphenyl)oxamide N-(2-ethoxyphenyl)-N -(2-ethylphenyl)oxamide benzoic acid, 4-[[(methylphenylamino) methylene]amino]-, ethyl ester Screeners carbon black ... 

Azoles containing a free NH group react comparatively readily with acyl halides. N-Acyl-pyrazoles, -imidazoles, etc. can be prepared by reaction sequences of either type (66) -> (67) or type (70)->(71) or (72). Such reactions have been carried out with benzoyl halides, sulfonyl halides, isocyanates, isothiocyanates and chloroformates. Reactions occur under Schotten-Baumann conditions or in inert solvents. When two isomeric products could result, only the thermodynamically stable one is usually obtained because the acylation reactions are reversible and the products interconvert readily. Thus benzotriazole forms 1-acyl derivatives (99) which preserve the Kekule resonance of the benzene ring and are therefore more stable than the isomeric 2-acyl derivatives. Acylation of pyrazoles also usually gives the more stable isomer as the sole product (66AHCi6)347). The imidazole-catalyzed hydrolysis of esters can be classified as an electrophilic attack on the multiply bonded imidazole nitrogen. 

A new type of rearrangement has been reported for certain l-(o-nitrophenyl)pyrazoles (169), giving cis- and trans-benzotriazole 1-oxides (170 Scheme 12) (73TL891). The reaction was rationalized in terms of an intermediate azo compound (171 formed in turn either from the diradical species (172) or from the intramolecular 1,4-adduct (173). Subsequently... 

Similar isomerization reactions were observed in CDCI3 solutions of N-( -aminomethyl)-l,2,4-triazoles and -tetrazoles (90T633). As for the analogous benzotriazoles, these reactions are-intermolecular and slow at 20°C in the NMR time scale. 

Reaction of 2-[(benzotriazol-l-yl)alkylamino]pyridines 341 with open-chain electron-rich alkenes 342 in the presence of BF3-Et20 gave 4-substituted 1,2,3,4-tetrahydropyrido[l, 2-n]pyrimidinium tetrafluorobo-rates 343 (98S704). 

Ceftiofur (57) differs from the preceding cephalosporin derivatives in that it ha.s a thioester moiety at C-3. This can be introduced by displacement of the C-3 acetyl group of 7-aminocepha-losporanic acid (40) with hydrogen sulfide and esterification with 2-furylcarboxylic acid to give synthon 5reacted with trimethylsilylated oximinoether derivative 55 (itself obtained from the corresponding acid by reaction with dicyclohexylcarbodiimide and 1-hydroxy-benzotriazole) to produce, after deprotecting, ceftiofur (57) [18]. 

Anodic inhibitors limit the oxidation of iron by sharing the lone pair electrons on the nitrogen with a metal ion or atom and supressing the anodic reaction. Examples are benzotriazole (at high concentrations), pyridines, thiols, and quinolines. 

The reaction also proceeds readily with A/-monosubstituted 1,2-diaminobenzenes (6.45, R = alkyl, aryl, acyl). Kroupa and Matrka (1970) investigated optimal reaction conditions for the synthesis of 1,2,3-benzotriazole from 1,2-diaminobenzene. 

An alternative approach towards the PASP synthesis of isocyanides was developed by Bradley [100,101]. It involved the use of a polymer-supported sul-fonyl chloride in the presence of base to afford the dehydration of formamides (Scheme 21). The formamides required could be easily prepared by reaction of the corresponding amines with a formylated benzotriazole resin. Opti-... 

Hie reactions of 4-chloropyridines and quinolines 17 with benzotriazoles 18 in a modified Graebe-Ullman synthesis give excellent yields of Y arbolines and their benzo-fused derivatives 20. Excellent yields for preparation of the penultimate benzotriazole precursors 19 are reported as well. In the optimized one-pot conditions, the combined neat substrates are heated with microwave irradiation (MW) for short (7-10 min) durations. The crude 19 is treated with H4P2O7 and irradiated futher (4-6 min). The resultant y-carbolines 20 were methylated to form the quaternary salts. These were tested and found to lack DNA intercalation properties <96JOC5587>. 

Ethoxycaibonylation of the 7-methylpyrrolotetrazolide ion gave the Nl-substituted product 18 preferentially <96JOC5646>. The 1,3-dipolar cycloaddition reactions of 19 with alkenes was investigated <96JHC335> as was the formation and reactivity of the tetrazoyl(benzotriazol-l-yl)methane 20 <96JHC1107>. 

Moreover, a dramatic increase of the reaction rate was observed when the coupUng of aromatic imines mediated by samariiun diiodide was carried out in the presence of both water and a tertiary amine or tetramethylethylene-diamine (TMEDA) [29], causing the almost instantaneous formation of the 1,2-diamine, although with undetermined diastereoselectivity. Similarly, the samarium diiodide promoted reductive coupling of iminiiun ions formed in situ by reacting ahphatic aldehydes with secondary amines and benzotriazole occurred at temperatures as low as - 70 °C [30]. Even in this case a mixture of diastereomers with undetermined ratio was obtained nevertheless, the item of diastereoselectivity induced by a chiral amine (auxiliary) is worthy of investigation. 

FD-MS is also an effective analytical method for direct analysis of many rubber and plastic additives. Lattimer and Welch [113,114] showed that FD-MS gives excellent molecular ion spectra for a variety of polymer additives, including rubber accelerators (dithiocar-bamates, guanidines, benzothiazyl, and thiuram derivatives), antioxidants (hindered phenols, aromatic amines), p-phcnylenediamine-based antiozonants, processing oils and phthalate plasticisers. Alkylphenol ethoxylate surfactants have been characterised by FD-MS [115]. Jack-son et al. [116] analysed some plastic additives (hindered phenol AOs and benzotriazole UVA) by FD-MS. Reaction products of a p-phenylenediaminc antiozonant and d.v-9-lricoscnc (a model olefin) were assessed by FD-MS [117],... 

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