Imidazole 4-nitro-1-phenyl

Aus Benzoesaure-chlorid-(4-nitro-benzylimid) und Oxalsaure-ethylester-nitril entsteht ein Gemisch aus 5(4)-Ethoxycarbonyl-4(5)-(4-nitro-phenyl)-2-phenyl- (21%) und 5(4)-Ethoxy-carbonyl-2-(4-nitro-phenyl)-4(5)-phenyl-imidazol (6%)301 ... 

Aus den Synthesekomponenten C —N-C—N + C ist nur die Herstellung von 5-(2,6-Dimethyl-anilino)- -(2,6-dimethyl-phenyl)-4-(1-ethoxycarbonyl-ethenyl)-2-(4-nitro-phenyl)-imidazol in 89% Ausbeute aus 2,6-Dimethyl-phenylisocyanid mit 4-Nitro-benzoesaure-(2,6-dimethyl-phe-nylimid)-(2-ethoxycarbonyl-l-propenylidenamid) beschrieben306. 

Bei der Nitrierung von Phenyl-imidazolen wird der Phenyl-Rest leichter nitriert als der Imid-azol-Ring1135 1137 (vgl. S.146). Die Nitrierung von Phenyl-Resten findet im allgemeinen in der 4-Stellung statt1135,1136 und ist schon mit rauchender Salpetersaure ohne Schwefelsaure moglich1137 [l-(Nitro-phenyl)-imidazole]. 

Data for the reactions of several cyclic tertiary amines with phenyl, 4-nitro-phenyl and 2,4-dinitrophenyl acetates, at 25°C and ionic strength 1.0, appear in Table 40, and as a Bronsted plot in Fig. 20. The usual irregularities of such plots for nucleophilic attack are evident. Linear relationships between log k and pKa are generally found for groups of compounds of closely similar structure, as for the substituted pyridines in Fig. 20. The data for the two tricyclic amines fall on separate curves, and the points for imidazole clearly fall on neither of the first two sets of lines. The separate lines for the reactions of particular classes of nucleophile are approximately parallel, as is usually found. 

Fig. 2 Use of imidazole units (13) binding the pyridine derivative (14) to generate imprinted polymers with esterolytic activity towards 4-nitro-phenyl-esters (15)...

Fig. 11.6 (A) Spectroscopic detection of acetylimidazole in the imidazole-catalysed hydrolysis of 4-nitro-phenyl acetate at pH 5 (D) and at pH 6 (E) curves are calculated from data in reference [12] and the curve for the acetate ion product (C) is for pH 5. (B) Reaction of imidazole with 4-nitrophenyl acetate (k) and the hydrolysis of acetyl imidazole (k2) curves constructed from data in references [13] and [12].

Further nitration of 4-methyl-2-(4-nitrophenyl) imidazole using mixed acid gives the 5-nitro product (21JCSI893), and dinitration of 4-methyl-2-phenylimidazole using fuming nitric acid, produces 5-nitro-2-(4-nitro-phenyl)-imidazole (40JPJ312). 

Imidazol 2-Cyclobutyl-4,5-dicar-boxy- E8c, 13 [HOOC-CH(OH) - CH(OH) - COOH/ HN03 + R-CHO(NH3)] Methan (2,4-Dimethyl-phenyl)-dinitro- IV/la. 765 Methannitronsaure (4-Nitro-phenyl)- -ethylester X/l, 158, 446... 

Reductive cyclization of 2-(t>/X t>-nitro)phenyl imidazoles 817, 819 (Scheme 203) in the presence of an orthoester or a ketone is promoted by a low-valent titanium reagent TiCU-Zn to afford imidazo[l,2-f]quinazolines 818 and 5,6-dihydroimidazo[l,2-r ]quinazolines 820 <2005JHC173>. Notably, halogens are not reduced under these conditions. 

Both these copolymers were found to enhance the catalytic effect of the polymer, per imidazole residue, on the hydrolysis rate of p-nitro-phenyl acetate 45). In the case of VI/VP, the relative catalytic efficiency of a copolymer with two-thirds of VP residues, as compared to the PVI homopolymer, increased from 1.4 at pH 7.4 to 1.7 at pH 8.2 and to 8.9 at pH 9.1. This result suggests strongly that a cooperative attack of a phenolate and an imidazole residue on the ester group makes an important contribution to the catalysis at higher pH values. With the VI/VA copolymers, the enhancement of the imidazole catalysis by hydroxyl groups attached to the same chain was less marked, leading to efficiencies increased by factors which reached, in the most favorable case, only 1.7. 

The preparation of pol)rmeric catalysts and substrates containing imidazole groups and nitro-phenyl esters, respectively, grafted onto crosslinked polystyrene beads has been described and the effects of the acyl chain length in the substrate in the aqueous alcohol solvent systems on the rate of hydrolysis of 3-nitro-4-acyloxybenzoic acid substrates catalyzed by insoluble catalysts were determined. 

Usthyl-l-fd-nitro-phenyll-pyrazol 23, S3. l-Methyl-2-[4-iiitro-phenyl]-imidazol... 

Methyl-l thyl-2-[4-nitro-phenyl]>benz imidazol 2 242. 

Nitto-l -phenyl-2.(4.nitro-phenyl ]-benz< imidazol 22, 237. 

This paper reports that we synthesized amino-6-CD to compare catalytic activity with 3-CD-histamine and it was clear that an imidazole group acted as an active site in the hydrolysis of p-nitro-phenyl acetate. And it also shows that in the hydrolytic reactions, 3-CD-histamine has a structural selectivity for substrates which are structurally different to each other. 

CD-histamine has an imidazole group and a secondary amino group (Figure 1). It is thought that the active site in the hydrolysis of p-nitro-phenyl acetate is an imidazole group which has a high activity at around neutral pH value. But a secondary amino group has a possibility to act as a catalytic site. 

Examples of micellar systems are given below where the surfactant provides the medium for catalysis but does not directly participate in the reaction. For instance, JV-acetyl histidine can bring about the hydrolysis of p-nitro-phenyl esters via an acyl-imidazole intermediate. 

A mixture of l,5-dimethyl-2-nitroimidazole and benzaldehyde in ethanolic KOH stirred 22.5 hrs. at room temp, under Ng l-methyl-2-nitro- -phenyl-5-imidazole-ethanol (Y 59%) added at room temp, to a stirred mixture of coned. H2SO4 and acetic acid, heated 20 min. at 110 in an oil bath l-methyl-2-nitro-5-styryl-imidazole (Y 86%). - This 2-stage process gives a better yield than direct condensation to the styryl deriv. G. Asato and G. Berkelhammer, J. Med. Chem. 15,1086 (1972). 

Imidazole, 1 -methyl-5-nitro-2-styryl-ozonolysis, 5, 437 Imidazole, l-methyl-2-phenyl- C NMR, 5, 354 Imidazole, l-methyl-4-phenyl- C NMR, 5, 355 Imidazole, 2-methyl-4-phenyl-acylation, 5, 402... 

Die 1-Aminierung mit O-Diphenylphosphinyl-hydroxylamin und Natriumhydrid in 1-Methyl-2-oxo-pyrrolidin ist sowohl fur wasserlosliche als auch fur wasserunlosliche Imidazole geeignet. Auch hier werden die Produkte iiblicherweise iiber die 1-Benzylidenamino-imidazole ge-reinigt. Auf diese Weise werden 1-Amino-611, l-Amino-4-nitro-611, l-Amino-2-methyl-4-ni(ro-611, l-Amino-2-methyl-61s und l-Amino-2-phenyl-imidazol678 hergestellt. 

Die analoge Umsetzungmit l,2-Dimethyl-5-nitro-imidazol fiihrt zu l-Methyl-5-nitro-2-(2-oxo-2-phenyl-ethyl)-imidazol iV>17,. Mit Oxalsaure-chlorid-ethylester als Acylierungsreagens wird 2-(2-Ethoxycarbonyl-2-oxo-ethyl)-l-methyl-5-nitro-imidazol erhalten1073. 

Bei der Photolyse von l-(2,4-Dinitro-phenyl)-4-phcnyl-imidazol in Ethanol wird der Heterocyclus in einer intramolekularen Redox-Reaktion gespalten. Unter Recyclisierung erhalt man 2-Benzoyl-6-nitro-benzimid-azol [50% Schmp. 255° (Zers.)]326. 

---