Imidazole 1.5- diphenyl-2-methyl

Imidazole, 2-methyl-1,4-dinitro-rearrangement, 5, 378 Imidazole, 5-methyl-1,4-dinitro-denitration, 5, 378 Imidazole, l-methyl-4,5-diphenyl-synthesis, 5, 478... 

Imidazole, 2-methyl-4,5-diphenyl-l-vinyl-synthesis, S, 488 Imidazole, 1-methylnitro-reactions... 

Reactions of Imidazoles. Thermolysis of 1-triphenylmethylimidazole results in migration of the imidazolyl group to yield compound (286). Sensitized photo-oxygenation of 4,5-diphenylimidazole in methanol affords a mixture of the imidazolinone (287) and the imidazolidinone (288). The imidazole (289 R = H) undergoes lithiation at C-5 subsequent treatment with diphenyl disulphide gives the di(phenylthio)-derivative (289 R = PhS). Copyrolysis of 2,4-dimethylimidazole and chloroform results in a complex mixture, containing imidazole and methyl-, dimethyl-, and chloromethyl-pyrimidines and -pyrazines. The confusion about the structures of N-methyl derivatives of iodo-nitro-imidazoles has been cleared up the supposed 1-methyl-2,5-di-iodoimidazole is actually the 4,5-di-iodo-compound it yields 4-iodo-l-methyl-5-nitroimidazole on nitration. The reaction of the bromo-... 

Imidazole, 2-amino-1 -methyl-4,5-diphenyl-tautomerism, 5, 368 Imidazole, 2-aroyl-mass spectra, 5, 360 synthesis, 5, 391, 402 UV spectra, 5, 356 Imidazole, 4-aroyl-synthesis, 5, 474 Imidazole, C-aroyl-UV spectra, 5, 356 Imidazole, aryl-nitration, 5, 396, 433 oxidation, 5, 433 Imidazole, 1-aryl-dipole moments, 5, 351 dearylation, 5, 449 ethylation, 5, 448 H NMR, 5, 353 hydroxymethylation, 5, 404 rearrangement, 5, 108 synthesis, 5, 390 thermal rearrangement, 5, 363 Imidazole, 2-aryl-chlorosulfonation, 5, 397 synthesis, 5, 475 Imidazole, 4-aryl-bromination, 5, 399 Imidazole, C-aryl-electrophilic substitution, 5, 432-433 nitration, 5, 433 Imidazole, N-aryl-reactions, 5, 448-449 structure, 5, 448-449 Imidazole, arylmercapto-... 

The structure of a second polymorph of 4,5-diphenyl- lH-imidazole has been discussed, with the new form exhibiting significantly different phenyl/imidazole dihedral angles and mode of crystal packing relative to the known form [53], A new triclinic polymorph of 1,4-dibenzoyl-butane was found, differing from the monoclinic form in the torsional angles of the central chain [54], Two polymorphs of diphenyl-(4-pyridyl)methyl methacrylate have been found, where the molecules in the two forms contain weak C—H— n and C—H O/N contacts that lead to the existence of different conformations [55]. 

Because of the electron withdrawing effect of the extra nitrogen atom, the deprotonation of 1,5-disubstituted 1,2,3-triazoles at the 4-position is a more facile process than that for the related imidazoles, and the metalation of 1,5-diphenyl-l, 2,3-triazole occurred readily, as was shown by the isolation of the 4-methyl derivative in 99% yield (7ICJC1792). A different result was observed in the case of a 5-methyl group, however, where lateral metalation was found to be the preferred mode of reaction (Scheme 63) (71CJC1792). 

Diphenyl-2H-imidazoles 120 have been shown to form methosalts 121 in high yields (Scheme 29) ethyl iodide, however, gave only small amounts of ethosalts. In 4-amino compounds, methylation occurs at the ring N-3. ... 

Dagegen tritt bei 2-Amino-4,5-diphenyl-4-hydroxy-4H-imidazol keine Umlagerung ein, da kei-ne Methyl-Gruppe vorhanden ist. Es wird stattdessen in konz. Salzsaure zu 2-Amino-4,5-di-hydroxy-4,5-diphenyl-4,5-dihydro-imidazol hydratisiert129. Mit Methanol/Salzsaure erhalt man 2-Amino-4,5-dimethoxy-4,5-diphenyl-4,5-dihydro-imidazol129 ... 

Wird die Ringerweiterung statt mit Bortrifluorid mit Meerwein-Reagens durchgefuhrt, so erhalt man mit Benzonitril aus 2-Methyl-3-phenyl-2H-azirin hauptsachlich l-Ethyl-2,5-diphe-nyl-4-methyl-imidazol und aus 3-Methyl-2-phenyl-2H-azirin 1-Ethyl-2,4-diphenyl-5-methyl-imidazol44°. 

Auch bei der Umsetzung von 4-Methyl-benzolsulfonsaure-imidazolid und Kalium-imidazolid mit Diphenyl-methanol wird C-Alkylierung beobachtet. Hier entsteht ein Gemisch aus 1-(22%), 2- (12%) und 4(5)-Diphenylmethyl-imidazol (24%)845. Beim Belichten von Imidazol und Diazo-diphenyl-methan in Tetrahydrofuran entsteht das gleiche Produktgemisch845. 

Aus 1-Methyl-2,4,5-triphenyl- bzw. 1,2-Dimethyl-4,5-diphenyl-imidazol und Acetonitril werden beim Belichten ebenfalls [2 4- 2]-Cycloadditionsprodukte erhalten1250 1251. Dagegen findet mit 1-unsubstituierten Imidazolen wie z.B. 2-Phenyl- und 2,4,5-Triphenyl-imidazol unter Iso-merisierung zu 2H-Imidazolen cine Additon in 2-Stellung statt1250 12S1. 

Alkynes bearing an adjacent Al-heterocycle, such as 5-ethynyl-1 -methyl-imidazole and 1-propargylbenzotriazole, readily alkylate benzene in the presence of triflic acid to yield diphenyl-substituted products.308 Isomeric ethynylpyridines exhibit distinct differences in reactivity 3-ethynylpyridine exhibits the highest reactivity, whereas 2-ethynylpyridine is the least reactive [Eq. (5.116)]. This is consistent with the involvement of dicationic intermediates as the de facto alkylating agents. Indeed,... 

The reaction of 1-methyl-lH-imidazole with 2equiv. iodobenzene gives its 5-phenyl derivative as the major product, with the 2,5-diphenyl derivative. Interestingly, addition of 2 equiv. Cul as promoter produces the 2-phenyl derivative together with the 2,5-diphenyl derivative no 5-phenyl derivative is formed (Eq. 13) [3],... 

An interesting photochemical approach to 4,5-disubstituted N-alkylimidazoles consists of the photolysis of 2,3-dihydro-5,6-disubstituted-pyrazines that can be easily prepared from 1,2-diketones and 1,2-diamino-alkanes. For example, the preparative-scale photolysis, in absolute EtOH with high-pressure Hg lamp (Pyrex filter), of 5,6-dimethyl- or 5,6-diphenyl-2,3-dihydropyrazines 54, yields the corresponding N-methyl-imidazoles 57 in high yields (Scheme 12.16). The reaction mechanism involves the formation of an enediimine intermediate 55, followed by cyclization and re-aromatization [41]. 

Vinyl and ethynyl groups attached to an imidazole ring can be catalytically reduced to the saturated (or less unsaturated) species and cleaved by oxidation. The corresponding 4-carbaldehyde is formed in 71% yield when l-methyl-2,5-diphenyl-4-styrylimidazole is oxidized with osmium tetroxide. However, they may not react like aliphatic alkenes and alkynes not all addition reactions occur normally, Michael additions are known, and the compounds can act as dienophiles in DielsAlder reactions (e.g., Scheme 132). 

Cyan-l,1-diphenyl- E16a, 818 (R2N-NH2 + Br-CN) 2-(4-Cyan-phenyl)-l-phenyl- El6a, 604 (-NH2 + HO-NH-) Imidazol 4-(2-Quinolyl)-l-methyl-IV/la, 746... 

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