Benzimidazole, 2-phenyl

Phenylbenzimidazole is nitrated first at the 5-position with mixed acid, and subsequent reaction produces 5-nitro-2-(4-nitrophenyl)-and 5-nitro-2-(3-nitrophenyl)-benzimidazole. 2-Phenyl-, 2-(4-nitro-phenyl)- and 5-nitro-2-phenyl-benzimidazole are nitrated as their conjugate acids. ... 

Substituted imidazoles can be acylated at the 2-position by acid chlorides in the presence of triethylamine. This reaction proceeds by proton loss on the (V-acylated intermediate (241). An analogous reaction with phenyl isocyanate gives (242), probably via a similar mechanism. Benzimidazoles react similarly, but pyrazoles do not (80AHC(27)24l) cf. Section 4.02.1.4.6). 

Ishidaa, T., Suzuki, T., Hirashimaa, S., Mizutani, K., Yoshida, A., Ando, I., Ikeda, S., Adachi, T., Hashimoto, H. Benzimidazole inhibitors of hepatitis C virus NS5B polymerase identification of 2-[(4-diarylmethoxy)phenyl]-benzimidazole. Bioorg. Med. Chem. Lett. 2006, 36, 1859-1863. 

In addition to palladium catalysts, Co(OAc)2 shows a catalytic activity for the arylation of heterocycles, including thiazole, oxazole, imidazole, benzothiazole, benzoxazole, and benzimidazole.78 As shown in Scheme 6, the catalytic system Co(OAc)2/9/Cs2C03 gives G5 phenylated thiazole, while the bimetallic system Co(OAc)2/CuI/9/Cs2C03 furnishes the G2 phenylated thiazole. The rhodium-catalyzed reaction of heterocycles such as benzimidazoles, benzoxazole, dihydroquinazoline, and oxazoline provides the arylation product with the aid of [RhCl(coe)]2/PCy3 catalyst.79 The intermediacy of an isolable A-heterocyle carbene complex is proposed. 

Additional work around the benzimidazole scaffold on compounds related to 29 [72,73] suggested that the dihedral angle between the heterocycle and the phenyl ring is a crucial determinant of binding affinity, leading to the design of tetracyclic compounds with the aromatic moieties linked [74], Thus, indole... 

Two approaches have been applied for the synthesis of imidazo[2,l + thia/,ole ring systems. Reaction of 2-mercapto-benzimidazole with perfluoro-2-methylpent-2-ene in the presence of triethylamine gave compound 419 (Equation 192), and cyclocondensation of 2-imidazolidinethione with the alkynyl(phenyl)iodonium salt 420 afforded product 421 (Equation 193) <2001RCB1446, 2003JCM715>. 

Sardesai and Sunthankar studied the cyclization of diethyl )V-(2-amino-phenyl)aminomethylenemalonate (162, R = H) (57MI2 59MI1). No cyclization occurred in refluxing xylene in the presence or absence of a catalyst (p-toluenesulfonic acid or sodium hydroxide), or in acetic anhydride, or in a mixture of acetic anhydride and concentrated sulfuric acid. Benzimidazole and benzimidazolone were obtained in 20% and 66% yields, respectively, when 162 (R = H) was distilled in vacuo. Benzimidazolone was the product when 162 (R = H) was heated in boiling diphenyl ether, o-Phenylenediamine was reacted with diethyl acetylmalonate at 140°C for 4 hr to give 2-methylbenzimidazole and diethyl malonate (85S555). 

Pyrrolo[l,2-a]benzimidazoles [181] (R = H, Me, Ph R = Me, CH2Ph), unsubstituted at the 1- and 3-positions, protonate in trifluoroacetic acid exclusively on C-1 (Alekseeva et al., 1972b). A methyl substituent in the 1-position leads to mixtures of C-1 and C-3 protonated forms, the relative amounts depending on the presence and nature of substituents at C-3. Without a C-3 substituent, the extent of protonation at the position is 81%, but decreases to 18% in the 3-methyl- and 3-phenyl derivatives the basicity of the derivatives increases simultaneously. 

A facile method for the synthesis of N-substituted 2-benzimidazolinones 142 has been developed by Romero et al. (96TL2361) using A-substituted ureas 139, which are cyclized to 142 with IBTA as an oxidant. The reaction probably proceeds via intermediates 140 and 141. Besides the iV-alkyl or aryl substituent, presence of the 1-methoxy group is necessary for the success of this cyclization. Another benzimidazoles synthesis involves cycli-zation of N-phenyl-C-alkyl formimidamides with IBD [95JCS(P1)615]... 

This comprises a copolymer containing 72 to 95 wt.% of ethylene and 28 to 5 wt.% of vinyl acetate and a small amount of organic composite having a bactericidal action contained therein, which is composed mainly of N,N-dimethyl-N -phenyl-N -(fluorodichloromethylthio)sulphamide, 1,2-benzisothiazoline-3-on, diiodomethyl-p-tolylsulphone and methyl(benzimidazol-2-yl)carbamate. It is suitable as cushioning material for floors and walls and as a material for building blocks and babies toys. 

Bis(benzimidazol-2-yl)disulfide (214) treated with phenyl isothiocyanate gives the 1,2,4-dithiazole derivative (215) as a result of electrophilic attack by the isothiocyanate group on the nitrogen atom... 

Die auBerordentliche Stabilitat des Imidazol-Rings gegeniiber Reduktionsreaktionen auBert sich z. B. darin, daB Phenyl-imidazole zu Cyclohexyl-imidazolen und Benzimidazole zu 4,5,6,7-Tetrahydro-benzimidazolen hydriert werden (Bd. IV/lc, S. 311). EineHydrierung des Imidazol-Rings gelingt nur unter acylierenden Bedingungen (Bd.1V/lc, S. 311). Auch in Purin-Derivaten wird selektiv der anellierte 6-Ring hydriert (Bd. IV/lc, S. 320). 

H CHS c6h5 1h Riickfl. 1 -Amino-benzimidazol l-Amino-2-methyl-... l-Amino-2-phenyl-... 70 69 59 156-156,5 164-165 204-205 ... 

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