Synthesis and pharmacological activity of 2-(biphenyl-4-yl)imidazo[1,2-a]benzimidazoles

Russian Chemical Bulletin - An efficient method for the synthesis of novel 9H-imidazo[1,2-a]benzimidazole derivatives containing a biphenyl substituent at position 2 was developed. These compounds,...     

Reaction of [3-(Dimethylamino)-2-Azaprop-2-en-1-Ylidene] Dimethylammonium Chloride with Grignard Reagents

Abstract

We recently reported¹ that [3-(Dimethylamino)-2-azaprop-2-en-1-ylidene] dimethylammonium chloride² (1) could be reacted with anions derived from ketones or amides to produce enaminones or acylamidines, respectively.     

Synthesis of pyrido[1,2-a]benzimidazoles from 2-acylmethyl-1H-benzimidazoles

Methods are proposed for the synthesis of previously unknown pyrido[1,2-a]benzimidazoles via the cyclocondensation of 2-acylmethyl-1H-benzimidazoles with malononitrile, triethylorthoformate ester, or ethoxymethylenemalononitrile. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1073–1079, July, 2006.     

Reaction of [3-(Dimethylamino)-2-Phenyl-Prop-2-en-1-Ylidene] Dimethylammonium Perchlorate with Grignard and Lithium Reagents

Abstract

The reaction of simple iminium salts, such as the Eschenmoser reagent (1) with Grignard and lithium reagents has been recently described¹.     

Research on imidazo[1,2-a]benzimidazole derivatives. 22. Synthesis of 2,3-dihydroimidazo[1,2-a]benzimidazoles starting from 2-imino-3-(2-hydroxyethyl)benzimidazolines

A -elimination reaction with the formation of 2-imino-3-vinylbenzimidazolines occurs simultaneously with intramolecular alkylation and the formation of an imidazoline ring in the action of alcoholic alkali on 2-imino-3-(2-chloroethyl) benzimidazolines. The thermolysis of 3-chlorethyl-substituted imines without a solvent or in an inert solvent leads exclusively to 2,3-dihydroimidazo[1,2-a] benzimidazoles. An attempt to obtain the latter directly from 2-imino-3-(2-hydroxyethyl) benzimidazolines by the action of a mixture of thionyl chloride and acetic anhydride on them also leads to ambiguous results.See [1] for communication 21.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 918–925, July, 1986.     

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.     

Synthesis of pyrimido[1,2-a]benzimidazoles from ethyl 2-ethoxymethylidene-3-oxo-3-(polyfluoroalkyl)propionates

Cyclization of ethyl 2-ethoxymethylidene-3-oxo-3-polyfluoroalkylpropionates with benzimidazol-2-amine in boiling 1,4-dioxane followed two concurrent pathways with participation of fluoroacyl and ethoxycarbonyl fragments and formation of, respectively, ethyl 4-hydroxy-4-polyfluoroalkyl-1,4-dihydropyrimido-[1,2-a]benzimidazole-3-carboxylates and 3-polyfluoroacylpyrimido[1,2-a]benzimidazol-4-ols. Dihydropyrimido[1,2-a]benzimidazole derivatives undergo dehydration to give ethyl 4-(polyfluoroalkyl)pyrimido[1,2-a]benzimidazole-3-carboxylates, whereas the hydroxy group in 3-polyfluoroacylpyrimido[1,2-a]benzimidazol-4-ols is capable of being replaced by the amino group of the second benzimidazole molecule with formation of 4-(1H-benzimidazol-2-ylamino)-3-polyfluoroacylpyrimido[1,2-a]benzimidazoles.     

Synthesis of pyrazolo[1′,5′:1,2]-1,3,5-triazino[5,6-a]benzimidazoles

The synthesis of a new class of tetracyclic bridgehead heterocycle pyrazolo[1′,5′:1,2]-1,3,5-triazino[5,6-a] benzimidazoles is reported. The key intermediate 2-(3-aminopyrazol-2-yl)benzimidazoles were prepared by the reaction of 2-hydrazinobenzimidazole with an appropriate reagent such as ethyl ethoxymethylenecyanoacetate, ethoxymethylenemalononitrile, β-cyanoacetophenone or α-formylphenylacetonitrile. The treatment of these key intermediates with triethylorthoesters afforded the corresponding pyrazolo[1′,5′:1,2]-1,3,5-triazino[5,6-a]benzimidazoles.     

Reaction of Polymer-supported Selenovinyl Bromide with Grignard Reagents： A Facile Route to the Synthesis of （E）-1, 2-Disubstituted Olefins

Polymer-supported selenovinyl bromide, easily prepared from polymer-supported selenenyl bromide with acetylene, reacts with different Grignard reagents using a step-by-step strategy to obtain （E）-1, 2-disubstituted ethenes in good yields.     

Imine-enamine tautomerism in dihydroazolopyrimidines. 2. Synthesis and tautomerism of 1,4(3,4)-dihydropyrimido[1,2-a]benzimidazoles

Cyclocondensation of 2-aminobenzimidazole with unsaturated ketones or the hydrochlorides of Mannich bases has yielded aromatic substituted 1,4(3,4)-dihydropyrimido[1,2-a]benzimidazoles. The dependence of the tautomer composition of the products on steric factors and on the electronic character of the substituents introduced has been studied.For Communication 1, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1215–1219, September, 1991.     

Synthesis of N-alkyl- and N-(β-hydroxyalkyl)-2-(acylmethylthio)benzimidazoles and their properties

N-alkyl- and N-(β-hydroxyalkyl)-2-(acylmethylthio)benzimidazoles have been obtained by the reaction of N-alkyl- and N-(β-hydroxyalkyl)benzimidazoline-2-thiones with α-haloketones. The structures of the substances synthesized have been confirmed by IR, PMR, and mass spectra. The biological properties of the compounds obtained have been studied.     

New Synthesis of peri-Fused Tetrahydro[1,3]diazepino[1,2-a]benzimidazoles from 1-Aroylmethyl-2-[(4-hydroxybutyl)amino]benzimidazoles

Russian Journal of Organic Chemistry - Treatment of 2-[(4-hydroxybutyl)amino]-1H-benzimidazole with ω-bromoacetophenones gave 1-aroylmethyl-substituted derivatives which underwent cyclization...     

Research on imidazo[1,2-a]benzimidazole derivatives. 23. Syntheses based on 2-(2-hydroxyethylamino)benzimidazoles

The possibility of annelation of the imidazoline ring on the basis of 2(2-hydroxyethylamino)-benzimidazoles was studied. It was shown that the action of hydrobromic, sulfuric, nitrosylsulfuric, and polyphosphoric acids, acetic anhydride, and phosphorus oxychloride on them does not lead to 2,3-dihydroimidazo[1,2-a]-benzimidazoles. In the case of POCl₃ the products were 2-(2-chloroethylamino)benzimidazoles, treatment of which with alcoholic alkali led primarily to nucleophilic substitution of the chlorine atom by a methoxy group. Three-ring imidazolines are formed in 12–15% yields in this case. It was established that the reaction proceeds through the intermediate formation of aziridine derivatives.See [1] for communication 22.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 59–63, January, 1987.     

Synthesis of 3-dimethylphenylsilyl-substituted pyrido[1,2-a]benzimidazoles

Reductive cyclization of 1-(2,4-dinitrophenyl)-3-methyl-4-dimetkylphenyisililpyridinium chloride by the action of phenylkydrazine or hydrogen in the presence of Pd/C gave, for the first time, 7-nitro (amino)-3 dimethylphenylsilylpyrido[l, 2-affienzimidazoles.Russian University of the Friendship of Nations, Moscow, 117923. Translated from Khimiya Geterots ikl icheskikh Soedinenii, No, 3, pp. 338–341, March, 1996. Original article submitted November 27, 1995.