A. M. Simonov

Transformations of 2-formyl-n-nitroarylimidazoles

Esters of-1-aryl-β-2-imidazolylacrylic acid were synthesized by the Wittig reaction from 2-formyl-1-arylimidazoles. The reaction of these aldehydes with arylamines and 1,2-dianilinoethane was examined.

Relative reactivities of the pyridine and benzimidazole systems in the chichibabin reaction

Abstract1-α (orγ)-Pyridyl- and 1-α (orγ)-pyridylethylbenzimidazoles were synthesized, and their behavior with respect to methyl iodide and sodium amide was studied. The results are discussed from the point of view of the basicities, magnitudes of the dipole moments, interaction of the heterorings, and the electron density distribution in them, calculated by the Hückel MO method or estimated on the basis of the relative position of the chemical shifts in the PMR spectra. It was established that the benzimidazole system undergoes the Chichibabin reaction considerably more readily than the pyridine system. On the basis of the PMR spectral data for the pyridine and benzimidazole bases and cations, it is assumed that this is due to the greater polarizability of the C = N bond of benzimidazole as compared with the C = N bond of pyridine during coordination with NaNH2.

2-Substituted imidazoles. 1. Reactions of 1-methyl-2-(2-furyl)imidazole with electrophiles

Abstract1-Methyl-2-(2-furyl)imidazole has been synthesized. Electrophilic attack (bromination, nitration, formylation, acylation, and hydroxymethylation) occurs in most cases at the free α-position of the furan ring.

Synthesis and transformation of 2-aminobenzimidazoles (review)

A review of papers published after 1965 that deals with methods for the synthesis of 2-aminobenzimidazoles and their properties is given.

3-α-Halocarbonyl derivatives of pyrazolo[1,5-a] benzimidazole and their reactions

Abstract3-(α-haloacyl)-2,4-dialkylpyrazolo[1,5-a]benzimidazoles can be obtained either by brominating 3-acetylpyrazolo[1,5-a]benzimidazoles with bromine in acetic acid, or by acylating the 3-unsubstituted pyrazolobenzimidazoles with haloacetic halides. Halogenation of 3-acetylpyrazolo[1,5-a]benzimidazoles with bromine in acetic acid in the presence of sodium acetate, and bromination with N-bromosuccinimide or 1-chlorobenzotriazole, result in deacylation to give 3,6(7)-dibromo- and 3-chloropyrazolo[1,5-a]benzimidazoles. The mono- and trihaloketones obtained have been used to prepare the corresponding aminoketones, the 3-carboxylic acid, and its derivatives.

1-Amino-2-alkylaminobenzimidazoles and their reactions with carbonyl-containing compounds

Abstract1-Amino-2-alkylaminobenzimidazoles were synthesized by a reaction involving exchange of the sulfo group in 1-aminobenzimidazole-2-sulfonic acid. 3-Alkyl-3H-1, 2,4-triazolo [1,5-a] benzimidazoles and 4-alkyl-4H-1,2,4-triazinol[2,3-a]benzimidazol-3-ones were obtained on the basis of them.

Research on the chemistry of 2-hetarylbenzimidazoles. 5. Acylation of 1-methyl-2-(2′-hetaryl)benzimidazoles

The acylation of 1-methyl-2-(2′-furyl)- and 1-methyl-2-(2′-thienyl)benzimidazoles was studied. A convenient method for the formylation of the furan and thiophene rings by the action of urotropin in polyphosphoric acid (PPA) was found. Acylation of the furan and thiophene rings was realized by the action of acetic acid and aromatic carboxylic acids in PPA.

Unusual cleavage of phenacyl-substituted benzimidazolium salts. Synthesis of 1,4-diarylimidazoles

The action of ammonium acetate in acetic acid on 1-alkyl(aralkyl)-3-phenacylbenzimidazolium bromides leads, in addition to the formation of a new imidazole ring, to cleavage of the benzimidazole fragment of the molecule at the 1,2 bond to give 1-alkyl(aralkyl)aminoaryl-4-arylimidazoles. 1,2-Dimethyl-3-(p-nitrophenacyl)benzimidazolium bromide is converted under similar conditions to the corresponding 2-methylimidazole. 4,4′-Dimethyl-2,2′-bis(p-nitrophenyl)-1,1′-dipyrrolo[1,2-a]benzimidazole was isolated as a side product of this reaction.

Research on benzimidazole derivatives

The acylation of 2-amino derivatives of benzimidazole and pyridine withβ-aryl-α, β-unsaturated carboxylic acid chlorides gave the corresponding amides, which were converted to 2-oxo derivatives of pyrimido [1,2-a]benzimidazole and pyridine by the action of bases.

Heterocyclic diazo-compounds. 3. Structure and unusual properties of primary 2-nitrosoaminobenzimidazoles

Primary nitrosamines of the benzimidazole series are highly stable, as a result of the existence of the polarized nitrosoimino-form. They have been used to obtain some benzimidazole derivatives.