Nitro derivatives of 1,3-dihydrobenzimidazol-2-one: I. Synthesis of <Emphasis Type="Italic">N</Emphasis>-nitrobenzimidazol-2-ones

1,3,5,6-Tetranitro-2,3-dihydro-1H-benzimidazol-2-one, 1,5,6-trinitro-2,3-dihydro-1H-benzimidazol-2-one, and 1,4,5,6-tetranitro-2,3-dihydro-1H-benzimidazol-2-one were synthesized for the first time by nitration of 5,6-di- and 4,5,6-trinitro-2,3-dihydro-1H-benzimidazol-2-ones with concentrated nitric acid in acetic anhydride.     

Acid-catalyzed rearrangement of 3-(β-2-aminostyryl)quinoxalin-2(1H)ones—a new and efficient method for the synthesis of 2-benzimidazol-2-ylquinolines

A highly efficient, one-step, versatile method for the synthesis of 2-benzimidazol-2-ylquinolines has been developed on the basis of an acid-catalyzed rearrangement proceeding via a novel ring contraction of 3-(β-2-aminostyryl)quinoxalin-2(1H)ones.     

A new approach to 1-alkyl-1,3-dihydro-2H-benzimidazol-2-ones

A new procedure for preparing 1-alkyl-1,3-dihydro-2H-benzimidazol-2-ones fromo-nitroanilines by successive ethoxycarbonylation, catalytic hydrogenation and thermal cyclization under neutral conditions is described.

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Eine neue Synthese von 1-Alkyl-1,3-dihydro-2H-benzimidazol-2-onen

Zusammenfassung Eine neue Methode zur Darstellung von 1-Alkyl-1,3-dihydro-2H-benzimidazol-2-onen auso-Nitroanilinen durch Ethoxycarbonylierung, katalytische Hydrierung und thermische Cyclisierung wird beschrieben.

     

Reaction of Diethyl Vinylphosphonate with Benzimidazole and 2-Aminobenzimidazole

Benzimidazole reacted with diethyl vinylphosphonate to give diethyl 2-(1H-benzimidazol-1-yl)- ethylphosphonate. The addition of 2-aminobenzimidazole to vinylphosphonate involved the endocyclic nitrogen atom with formation of diethyl 2-(2-imino-2,3-dihydro-1H-benzimidazol-1-yl)ethylphosphonate.     

Benzazoles: II. Synthesis and arenesulfonylation of 1-methyl-1H-benzimidazol-2-amine

The reaction of 1-methyl-1H-benzimidazol-2-amine with arenesulfonyl chlorides in the presence of triethylamine afforded 1-arenesulfonyl-3-methyl-2,3-dihydro-1H-benzimidazol-2-imines instead of expected N-(1-methyl-1H-benzimidazol 2-yl)arenesulfonamides.     

Synthesis,antimicrobial and cytotoxic activity of novel azetidine-2-one derivatives of 1H-benzimidazole

A series of 1-methyl-N-[(substituted-phenylmethylidene)-1H-benzimidazol-2-amines (4a–4g) were prepared via the formation of 1-methyl-1H-benzimidazol-2-amine (3), which was prepared by the cycloaddition of o-phenylenediamine (1) with cyanogen bromide in the presence of aqueous base followed by N-methylation with methyl iodide in the presence of anhydrous potassium carbonate in dry acetonitrile. Moreover, the four-membered β-lactam ring was introduced by the cycloaddition of 4a–4g and chloroacetyl chloride in the presence of triethylamine catalyst to give 3-chloro-1-(1-methyl-1H-benzimidazol-2-yl)-(4′-substituted)-phenylazetidin-2-one 5a–5g. A total of 14 compounds were synthesized and characterized by IR, ¹H NMR, ¹³C NMR and Mass spectral technique, in addition they were evaluated for anti-bacterial and cytotoxic properties. Among the chemicals tested 4a, 4b, 5a, 5b, 5g exhibited good antibacterial activity and 5f, 5g shown good cytotoxic activity in vitro.     

Oxidation products of fused 2-hetarylimidazole derivatives

Oxidation of 5-(1-methyl-1H-benzimidazol-2-yl)thiophene-, and -selenophene-2-carbaldehydes with potassium dichromate in 20% aqueous sulfuric acid afforded the corresponding carboxylic acids. Analogous reaction with 5-(1-methyl-1H-benzimidazol-2-yl)furan-2-carbaldehyde led to the formation of 1-methyl-1H-benzimidazole as a result of decarboxylation of the primary oxidation product and subsequent decomposition of the furan ring. Probable factors responsible for instability of 5-(1H-benzimidazol-2-yl)-hetarene-2-carboxylic acids were considered. The oxidation of 2-furylnaphtho[2,3-d]- and 2-hetarylphenanthro-[9,10-d]imidazoles gave, respectively, an anthraquinone analog and 6,7-quinones. π-Electron-rich heterocycles in 2-furyl- and 2-pyrrolylphenanthro[9,10-d]imidazoles were oxidized completely, being replaced by hydrogen.     

Modification of 2-trifluoromethyl-1H-benzimidazole with hydroxyalkyl substituents

Alkylation of 2-(trifluoromethyl)-1H-benzimidazole with 4-bromobutyl acetate gave 4-[2-(trifluoromethyl)-1H-benzimidazol-1-yl]butyl acetate which was deacylated by the action of hydrogen chloride in anhydrous ethanol. 4-[2-(Trifluoromethyl)-1H-benzimidazol-1-yl]butan-1-ol thus formed showed a moderate tuberculostatic activity. Alkylation of the title compound with chloromethyloxirane afforded a mixture of 1-chloro-3-[2-(trifluoromethyl)-1H-benzimidazol-1-yl]-propan-2-ol and 1-(oxiran-2-ylmethyl)-2-trifluoromethyl-1H-benzimidazole. A new procedure was proposed for the synthesis of 2-[(2-trifluoromethyl-1Hbenzimidazol-1-yl)methoxy]ethyl acetate.     

New Strategy of the Synthesis of 3,4-Dihydropyrimido[1,2-<Emphasis Type="Italic">a</Emphasis>]benzimidazol-2(1<Emphasis Type="Italic">H</Emphasis>)-ones

A new procedure has been developed for preparative synthesis of 3,4-dihydropyrimido[1,2-a]-benzimidazol-2(1H)-ones by thermal intramolecular heterocyclization of 3-[2-(propylsulfanyl)- and 2-(benzylsulfanyl)-1H-benzimidazol-1-yl]propanehydrazides and 3-[2-(benzylsulfanyl)-1H-benzimidazol-1-yl]-propanamide.     

Synthesis of some 1- and 2-carboxyalkyl substituted benzimidazoles and their derivatives

Mono- and disubstituted benzimidazoles were synthesized during alkaline hydrolysis or reactions with ethyl chloroacetate of 1-phenyl substituted 4-(1H-benzimidazol-2-yl)-2-pyrrolidinones. The properties of the synthesized ethyl-[2-(1-(substituted phenyl)-5-oxopyrrolidinyl-3-yl)-1H-benzimidazolyl]ethanoates have been investigated and their benzimidazolium chlorides, 1-carboxymethylbenzimidazoles, condensation products of 2-{2-[1-(3-methylphenyl)-5-oxo-3-pyrrolidinyl]-1H-benzimidazol-1-yl}acetohydrazide with various aromatic aldehydes and aliphatic ketones have been obtained.     

Effektive Synthese von 3,1′-Spiro[3,4-dihydro-2H-[1,3]oxazino[3,2-a]benzimidazol] cyclo- bzw. benzocycloalkanen sowie ihrer Thia-Analogen Über Spirane, 23. Mitt.

Ten new constitutionally unsymmetrical azaspiran systems were synthesized upon condensation of Na-derivatives of 2,3-dihydro-1H-benzimidazol-2-one and 2,3-dihydro-1H-benzimidazol-2-thione, respectively, with 1,1-bis(bromomethyl)-and 1,1-bis(iodomethyl)- and ditosylate of 1,1-bis(hydroxymethyl) cycloalkanes.

Vorgetragen auf dem 28. IUPAC-Kongreß in Vancouver (August 1981).     

Synthesis of 1,5,6,7-tetrahydro-4<Emphasis Type="Italic">H</Emphasis>-benzimidazol-4-one derivatives from 2,6-bis(hydroxyimino)cyclohexan-1-one

The reaction of 2,6-bis(hydroxyimino)cyclohexan-1-one with aldehydes and ammonia afforded 2-substituted 4-hydroxyimino-4,5,6,7-tetrahydro-1H-benzimidazol-1-ols which were hydrolyzed to 1-hydroxy- 2-R-1,5,6,7-tetrahydro-4H-benzimidazol-4-ones. The N-hydroxy group in the latter can readily by removed by the action of chloroacetone in the presence of a base (potassium carbonate or triethylamine); as a result, 2-substituted 1,5,6,7-tetrahydro-4H-benzimidazol-4-ones were obtained.     

Synthesis and bioassay of benzimidazole conjugates with adamantane

The synthesis of 2-adamantyl-6-[(1H-benzimidazol-1-ylcarbonyl)amino]hexanoate and 2-adamantyl-7-(1H-benzimidazol-1-yl)-7-oxo-heptanoate, and the results of their cytotoxicity assay against human lung carcinoma cells A549 are presented in the paper. The impossibility of adding 5-(2-adamantyloxycarbonyl)pentyl isocyanate to nocodazole under various conditions was shown.     

A facile synthesis of new 3-(2-benzimidazolyl)-2-alkyl-4-(3H)-quinazolinones under microwave irradiation

Preparation of 2-amino-N-(1-H-benzimidazol-2-yl)benzamide and a variety of new 3-(2-benzimidazolyl)-2-alkyl-4-(3H)-quinazolinones using isatoic anhydride, 2-aminobenzimidazole and orthoesters under microwave irradiation are described.     

SYNTHESIS AND REACTVITY OF N-[N-PHOSPHORAMIDO-1H-BENZIMIDAZOL-2-YL] IMIDATES

N-(-1H-Benzimidazol-2-yl) imidates 1a–c react with chlorophosphoramide to give the N-[-1-N,N,N′,N′-tetramethylphosphoramidoyl-1H-benzimidazol-2-yl]-imidates 2a–c or with dichlorophosphoramide to yield the bis[(N-1-benzimidazol-2-yl)-imidate] phosphoramide derivatives 3a–b. The reaction of compounds 2a–c toward primary amines is studied. The obtained amidine derivatives 4a–b were unambiguously characterized by different spectroscopic techniques (IR, ¹H, ¹³C, and ³¹P NMR, and in some cases MS).     

Unique substituted 3-oxo-1,2,3,4-tetrahydropyrazino[1,2-a]benzimidazole-1-carboxamides generated by Ugi 3CC using bifunctional starting material

2-(2-Formyl-1H-benzimidazol-1-yl)acetic acid, as a bifunctional formyl-acid was prepared in four steps. This compound underwent one-pot reaction with primary amines, and alkyl isocyanides under Ugi conditions. A series of novel 3-oxo-1,2,3,4-tetrahydropyrazino[1,2-a]benzimidazole-1-carboxamides were obtained in moderate to excellent yields.     

Potential antitumor agents. IV. Pyrrole analogues of oncodazole

The synthesis of alkyl [5-(1H-pyrrol-2-ylcarbonyl)-1H-benzimidazol-2-yl]carbamates and alkyl [5-(1H-pyrrol- 1-ylmethyl)-1H-benzimidazol-2-yl]carbamates is described. The new pyrrole derivatives are related to oncodazole, a recent synthetic derivative showing antifungal, antitumor and anthelmintic properties.     

Über die Synthese von 4,9-Dihydro-9-(2-dimethylaminoäthyl)-4-methyl-thieno[3,4-b][1,5]benzodiazepin-10-on

The synthesis of the title compound6 c, starting with the condensation of o-phenylenediamine and methyl 4-oxotetrahydrothiophene-3-carboxylate (1) to 1.3.4.9-tetrahydrothieno[3.4-b] [1.5]benzodiazepin-10-one (2), is described. The structures of other products of this condensation, 1.3-dihydro-1-[3-(2.5-dihydrothienyl)]-benzimidazol-2-one (3) and 1.3-dihydro-1-[3-(2.3-dihydrothienyl)]-benzimidazol-2-one (4), are confirmed by their¹H-NMR-spectra and by the¹H-NMR-spectra of their desulfurization products.     

Phosphorylation of Benzimidazole-2-thiones by Chloroethynylphosphonate

The reaction of chloroethynylphosphonates with N-substituted benzimidazole-2-thiones proceeded chemo- and regioselectively with the formation of cyclic zwitterions, namely alkyl (9H-benzo[4,5]imidazo[2,1-b]-thiazol-3-yl-4-ium)phosphonates. Chemo- and regioselective reaction of N-unsubstituted benzimidazole-2-thione with chloroethynylphosphonates led to the production of linear Z-1,2-bis(1H-benzimidazol-2-ylsulfanyl)-ethenylphosphonates.     

Derivatives of α,β-dehydroamino acids: V. Intramolecular cyclization of 2-{2-[(<Emphasis Type="Italic">Z</Emphasis>)-1-Benzamido-2-phenylvinyl]acetamidomethyl}benzimidazole

Reaction of 4-benzylidene-2-phenyl-1,3-oxazol-5(4H)-one with 2-(1H-benzimidazol-2-yl)ethaneamine led to the formation of 2-{2-[(Z)-1-benzamido-2-phenylvinyl]acetamidomethyl}benzimidazole that in a reaction with hexamethyldisilazane in DMF gave 5-benzylidene-1-(1H-benzimidazol-2-yl)-2-phenyl-3,5-dihydro-4H-imidazol-4-one. In the presence of K₂CO₃ in dioxane the reaction with hexamethyldisilazane resulted in the product of intramolecular addition, N-(4-benzyl-3-oxo-1,2,3,4-tetrahydropyrazino[1,2-a]-benzimidazol-4-yl)benzamide