A practical synthesis of 2-(N-substituted)-aminobenzimidazoles utilizing CuCl-promoted intramolecular cyclization of N-(2-aminoaryl)thioureas

A practical protocol for synthesis of 2-(N-substituted)-aminobenzimidazoles was developed. N-(2-Aminoaryl)thioureas undergo a CuCl-promoted intramolecular cyclization to give the corresponding 2-(N-substituted amino)benzimidazoles in good to excellent isolated yields.     

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.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 867–887, July, 1979.     

Iodine-mediated direct synthesis of multifunctional 2-aminobenzimidazoles from N-substituted o-diaminoarenes and isothiocyanates

Multifunctional 2-aminobenzimidazoles were directly synthesized through sequential addition of N-substituted o-diaminoarenes to isothiocyanates, formation of carbodiimides via I₂-mediated oxidative desulfurization, and intramolecular cycloaddition. This efficient and eco-friendly synthetic process provides a facile access to diverse 2-aminobenzimidazole derivatives from readily accessible substrates under mild reaction conditions in a scalable fashion.     

A one-pot method for the synthesis of 2-aminobenzimidazoles and related heterocycles

A rapid and efficient one-pot method for the synthesis of 2-aminobenzimidazoles and related heterocycles is described. The reaction is mediated by a polymer-supported carbodiimide, which simplifies product isolation. The scope and limitations of this method are described.     

Dithiocarbamate and CuO promoted one-pot synthesis of 2-(N-substituted)-aminobenzimidazoles and related heterocycles

A rapid and efficient one-pot method for the synthesis of 2-(N-substituted)-aminobenzimidazoles is described. The reaction is promoted by dithiocarbamate and catalytic CuO. This procedure is general and can be applied to synthesize many potential drug candidates.     

Parallel solid-phase synthesis of 2-imino-4-oxo-1,3,5-triazino[1,2-a]benzimidazoles via tandem aza-Wittig/heterocumulene-mediated annulation reaction

The parallel synthesis of a large number of 2-imino-4-oxo-1,3,5-triazino[1,2-a]benzimidazole derivatives via a solid-phase 1,3,5-triazino-annulation reaction is described. The solid-phase approach involves the in situ generation of iminophosphorane derivatives derived from resin-bound 2-aminobenzimidazoles employing Mitsunobu conditions. The subsequent Aza-Wittig reaction of the iminophosphoranes with isocyanates leads to highly reactive carbodiimides, which undergo an intramolecular heterocyclization reaction to form tetrasubstituted 2-imino-4-oxo-1,3,5-triazino[1,2-a]benzimidazoles in high yields (74-94%) and good purity (>80%).     

Imidazole derivatives that contain potentially labile groupings attached to the N atom. 7. Synthesis of 1-substituted 2-aminobenzimidazoles by ammonolysis of 1-R-3-methoxybenzimidazolium salts

A new method for the synthesis of 1-substituted 2-aminobenzimidazoles, which are difficult or impossible to obtain by direct amination with sodium amide, is proposed. The method consists in the action of liquid ammonia on 1-R-3-methoxybenzimidazolium salts. The reaction is accompanied by the addition of the amide ion in the 2 position and elimination of a methoxy group.See [1] for Communication 6.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1086–1088, August, 1982.     

One-pot synthesis of 2-aminobenzimidazoles using 2-chloro-1,3-dimethylimidazolinium chloride (DMC)

2-Chloro-1,3-dimethylimidazolinium chloride (DMC or DMC-Cl) has been found to effectively and rapidly generate 2-aminobenzimidazoles from 1,2-diaminoarenes and isothiocyanates in moderate to good yields at room temperature in a one-pot operation.     

Investigations of benzimidazole derivatives

The synthesis of 1-tert-butyl-, 1-nonyl-, and 1-undecylbenzimidazoles is described. The behavior of these compounds with respect to sodium amide and dilute alkali was studied. A number of new 2-aminobenzimidazoles and benzimidazolones were synthesized.See [1] for communication XXVI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 665–668, May, 1971.     

Behavior of N-alkoxybenzimidzoles with respect to nucleophilic reagents. Attempts to synthesize N-hydroxy-2-aminobenzimidazoles

Various possibilities for the synthesis of N-hydroxy- and N-alkoxy derivatives of 2-aminobenzimidazoles — reductive cyclization of o-nitrophenylureas, the action of sodium amide on 1-alkoxybenzimidazoles, the ammonolysis of 1-alkoxy-2-iodobenzimidazoles, etc. — were investigated. Organometallic compounds of 1-alkoxybenzimidazoles were obtained for the first time, and their reactivities with respect to benzophenone, iodine, and 1-substituted benzimidazoles were studied. 2,2-Dibenzimidazolyls that contain an alkoxy group in the 1 position were synthesized.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 200–206, February, 1979.     

Condensation reactions of vinyl and ethyl derivatives of 2-amino-and 2-formylimidazoles

New Schiff bases of 1-vinyl- and 1-ethyl-substituted imidazoles and benzimidazoles were synthesized. The condensation reactions of 2-amino- and 2-formylimidazoles with 2-aminobenzimidazoles are virtually independent of the nature of the substituent (CH=CH₂ or Et) at position 1 of the heterocycle. The structures of the azomethines synthesized were established by¹H NMR and IR spectroscopy. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 5, pp. 971–974, May, 1999.     

Synthesis of 4-and 5-substituted 2-methyl-and 2-(2-carboxyethyl)-1,2,4-triazino-[2,3-a]benzimidazol-4(5)H-3-ones

Condensation of 2-alkylamino-1-aminobenzimidazoles and quaternary 1,2-diamino-3R-benzimidazolium salts with pyruvate and α-ketoglutaric acid has given 4-and 5-substituted 2-methyl-and 2-(2-carboxyethyl)-1,2,4-triazino[2,3-a]benzimidazol-4(5)H-3-ones. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 738–747, May, 2006.     

Investigations of imidazo[1,2-a]benzimidazoles 26. 2-Halomethylimidazo[1,2-a]benzimidazoles and their reactive properties

Treatment of 2-aminobenzimidazoles with 1,3-dichloroacetone or radical bromination of 3-alkoxycarbonyl- or 3-acetyl-2-methylimisazo[1,2-a]benzimidazoles leads to the 2-halomethyl derivatives of this heterocycle. The lability of the halogen atom in the synthesized compounds has been demonstrated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 369–376, March, 1994.     

Researches in the field of benzimidazole derivatives XVII. Azomethines based on 2-aminobenzimidazoles and furan series aldehydes

Azomethines containing benzimidazole and furan rings are synthesized from 2-aminobenzimidazoles and 5-substituted furfurals. Some of the resulting azomethines are converted to iodomethylates. The imidazole ring of 2-furfurylideneaminobenzimidazoles has a diminished reactivity to electrophilic reagents because the -electrons of the imidazole and furan rings are conjugated across an N=CH group.For Part XVI see [1].     

A facile synthesis of 5,7-dihydro-5-oxopyrido[3′,2′:5,6]pyrimido[1,2-a]benzimidazoles. A new heterocyclic ring system

Reaction between 2-chloropyridine-3-carbonyl chloride and 1-alkyl-2-aminobenzimidazoles afforded the N-(1-alkylbenzimidazole-2-yl)-2-chloropyridine-3-carboxamides, which were cyclized to 5,7-dihydro-5-oxopyrido[3′,2′:5,6]pyrimido[1,2-a]benzimidazoles. The assigned structures of these hitherto unknown heterocyclic compounds were confirmed by their ir and ¹H nmr spectra and chemical evidence.     

Imidazole derivatives containing potentially labile groupings attached to an N-atom

The action of benzyl alcohol on 2-aminobenzimidazoles in the presence of alkali has given a high yield of a number of 2-benzylaminobenzimidazoles which have been converted subsequently into 2-dibenzylaminobenzimidazoles and 2-benzyliminobenzimidazolines.For part IV, see ¦1¦.     

Carbon suboxide and some of its reactions

Reaction of carbon suboxide with some 2-aminobenzimidazoles is investigated, and some corresponding 2, 3-(dioxotetrahydropyrimido) benzimidazoles obtained, which arylate to enol form derivatives.For Part XXIII see [3].     

Site-specific cleavage of RNA by a metal-free artificial nuclease attached to antisense oligonucleotides

RNA cleaving tris(2-aminobenzimidazoles) have been attached to DNA oligonucleotides via disulfide or amide bonds. The resulting conjugates are effective organocatalytic nucleases showing substrate and site selectivity as well as saturation kinetics. The benzimidazole conjugates also degrade enantiomeric RNA. This observation rules out contamination effects as an alternative explanation of RNA degradation. The pH dependency shows that the catalyst is most active in the deprotonated state. Typical half-lifes of RNA substrates are in the range of 12-17 h. Thus, conjugates of tris(2-aminobenzimidazoles) can compete with the majority of metal-dependent artificial nucleases.     

Synthesis of condensed pyrimidine systems based on 2,4,6-triphenylpyrylium perchlorate

1,3-Diphenylpyrimido[1,2-a]benzimidazolium perchlorates were obtained by reaction of 2,4,6-triphenylpyrylium perchlorate with 2-aminobenzimidazoles.