- Organocatalytic Enantioselective Conjugate Alkynylation of β-Aminoenones: Access to Chiral β-Alkynyl-β-Amino Carbonyl Derivatives
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Readily available potassium alkynyltrifluoroborates were used for organocatalytic asymmetric conjugate alkynylation of β-enaminones. The interception of a modified binaphthol catalyst and in situ generated organodifluoroboranes proved important to access functionalized β-alkynyl-β-amino carbonyls and derivatives with improved chemo-reactivity and enantio-induction. Mechanistic studies revealed the impact of molecular sieves on efficiency and stereocontrol. The products undergo additional functionalization to yield a diverse set of valuable β-alkynyl-β-amino carbonyl scaffolds.
- Mao, Bin,Meng, Xin,Wang, Jian-Fei,Yu, Chuan-Ming,Zhang, Chao-Huan
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supporting information
p. 7427 - 7432
(2020/10/09)
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- Carbonylative Acetylation of Heterocycles
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Herein, a new procedure for the carbonylative acetylation of heterocycles has been developed. In this process, organic peroxide acts as the methyl source. Various heterocycles were transformed into the corresponding methyl heterocyclic ketones in moderate to good yields.
- Zhang, Youcan,Yin, Zhiping,Wu, Xiao-Feng
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p. 213 - 216
(2020/01/22)
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- Synthesis of Some Benzimidazole-based Heterocycles and their Application as Copper Corrosion Inhibitors
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A series of new substituted benzimidazoles embedded with a variety of function groups has been synthesized from N-methyl-2-bromoacetylbenzimidazole. The synthesized compounds were fully characterized, and their structures were elucidated based on elemental analysis, spectral data, and alternative synthetic pathways, whenever possible. Some of benzimidazole derivatives were tested as corrosion inhibitors.
- Eldebss, Taha M. A.,Farag, Ahmad M.,Shamy, Adel Y. M.
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p. 371 - 390
(2019/01/08)
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- CYCLIC SULFAMIDE COMPOUNDS AND METHODS OF USING SAME
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The present disclosure provides, in part, cyclic sulfamide compounds, and pharmaceutical compositions thereof, useful as modulators of Hepatitis B (HBV) core protein, and methods of treating Hepatitis B (HBV) infection.
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Page/Page column 352
(2018/09/21)
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- Synthesis, crystal structure, and antioxidant property of a new Co(III) coordination polymer based on ligand (E)-2-{2-[1-(1-methyl-1H-benzo[d]imidazol-2-yl)ethylidene]hydrazinyl}benzo[d]thiazole
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A new Co(III) complex, [CoL2](ClO4)(CH3CN) (1) (HL = (E)-2-{2-[1-(1-methyl-1H-benzo[d]imidazol-2-yl)ethylidene]hydrazinyl}benzo[d]thizole), has been prepared by solvent evaporation method, and characterized by single-crystal X-ray diffraction, bond valence sum, and elemental analysis. The result of single-crystal X-ray diffraction analysis indicates that each Co(III) ion is six-coordinated by six nitrogen atoms from two L- to form distorted octahedral geometry. The hydrogen bonds and π.π stacking interactions ensure the cohesion of crystal lattice in a 3D supramolecular framework in the solid state. The antioxidant activities of HL and 1 were also studied.
- Deng, Wen-Ting,Liu, Jia-Cheng,Cao, Ping,Xu, Ya-Qin
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p. 667 - 672
(2015/04/16)
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- A New Facile Sulfenylation of 2-Acetylbenzimidazoles
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A facile sulfenylation of 2-acetylbenzimidazoles has been achieved by using N-(phenylthio)phthalimide in the presence of potassium tert-butoxide in DMSO. The latter gave N-alkyl-β-phenylsulfenyl-2-acetylbenzimidazole on reaction with alkylating agents in the presence of potassium carbonate in N,N-dimethylformamide.
- Kumar, P. Praveen,Dathu Reddy,Ramana Reddy, Ch. Venkata,Rama Devi,Dubey
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p. 1775 - 1779
(2015/10/29)
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- A green and simple synthesis of N-alkyl-2-acetylbenzimidazoles
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A green and simple synthesis of N-alkyl-2-substituted benzimidazoles has been developed. In this method, 2-acetyl benzimidazole compound (1) was alkylated with reagents such as dimethyl sulfate/diethyl sulfate/benzyl chloride under green conditions i.e., by physical grinding in presence of a mild base like K2CO3 or by using green solvents like PEG-600, ethanol etc. or by using micro-wave irradiation technique to obtain N-alkyl-2-acetylbenzimidazoles compound (2).
- Kumar, P. Kishore,Dubey
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experimental part
p. 3249 - 3250
(2012/08/29)
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- Alkylation studies on pyrazolyl and isoxazolyl benzimidazoles
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2-Acetylbenzimidazole (1) on heating with dimethyl formamide dimethyl acetal gave 1-(1 H-benzimidazolyl)-3-dimethylaminopropenone (2) which on reaction with hycirazpne hydrate gave 2-(1 H-pyrazolyl)-1 H-benzimidazole (3), The reaction of 3 with DMS/DES/ PhCH2CI in CH3CN containing K2CO3 as base and triethylbenzylammonium chloride (TEBAC) as phase trasfer catalyst (PTC) resulted in the formation of 2-(3-pyrazolyl)-1 - substitutedbenzimidazole (4). Alkylation of I with DMS/DES/PhCH2CI under PTC conditions gave the previously known 1-substituted -2-acetyl benzimidazoles (5) which with DMF-DMA gave I -substituted-2-(2-benzimidazolyl)-3.dimethylaminopropenone (6). The latter could also be obtained from 2 by alkylation under PTC conditions. Treatment of 6 with hydrazine hydrate in methanol yielded 4. Reaction of 2 with hydroxylammonium chloride yielded 1 H-(2-benzimidazolyl)-3-isoxazole (8) which on alkylation under PTC conditions gave 1-substituted (2-benzimidazolyl)-3-isoxazole (9). The latter could also be obtained from 6 by treatment with hydroxylammonium chloride.
- Kumar, Kishore,Hemasunder,Naidu,Dubey
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p. 393 - 398
(2013/09/24)
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- Microwave-assisted synthesis of 2-substituted 4-biarylyl-1,3-thiazoles by carbon-carbon cross-coupling in water
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Suzuki-Miyaura and Heck-Mizoroki C-C cross-coupling reactions of 4-(halophenyl)-1,3-thiazoles with aryl(hetaryl)boronic acids or olefins, respectively, were investigated by using a catalytically active benzimidazole-based palladium(II) complex under both thermal and microwave heating conditions in water. The factors affecting the optimization of such reactions were evaluated.
- Dawood, Kamal M.,El-Deftar, Moteaa M.
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scheme or table
p. 1030 - 1038
(2010/06/16)
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- Facile and simple synthesis of novel 1-Methyl-2-(2-substituted-oxazol-4-yl) -1H-benzimidazole derivatives
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Novel 1-methyl-2-(2-substituted-oxazol-4-yl)-1H-benzimidazole derivatives were obtained in good yields and purity by treating corresponding 2-benzimidazolyl esters with acetamide in the presence of BF3- etherate, a Lewis acid.
- Reddy, E. Vishnu Vardhan,Prakash, P. Bhanu,Khobare, Sandip,Ramanatham,Devanna
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scheme or table
p. 414 - 422
(2010/04/02)
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- Synthesis of novel benzimidazole β-keto sulfones and β-hydroxy sulfones and their regiospecific alkylation studies
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The synthesis of benzimidazole β-keto sulfides 5a-f by the reaction of W-alkyl-α-bromo-2-acetylberizirnidazoles 3a-b with 5-substituted- benzimidazole-2-thiols 4a-c followed by successive oxidation with H 2O2 to give β-keto sulfones 8a-f and reduction with NaBH4 to give β-hydroxy sulfones 9a-f is described. Reaction of 5a, 8a, 9a and 10a with DMS in the presence of K2CO3 and TBAB as PTC, resulted in the regiospecific N-methylation of benzimidazole moiety of 12a, 11a, 14a and 13a respectively.
- Dubey,Kumar, N.D. Mahesh,Chaitanya,Naidu,Vineel, B. George
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body text
p. 937 - 943
(2010/10/18)
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- Synthesis and antiprotozoal activity of novel 1-methylbenzimidazole derivatives
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In this paper are reported the synthesis and antiprotozoal activity in vitro of 24 1-methylbenzimidazole derivatives (13-36) substituted at position 2 with aminocarbonyl, N-methylaminocarbonyl, N,N-dimethylaminocarbonyl, ethoxycarbonyl, 1-hydroxyethyl and acetyl groups, some of them with chlorine atoms at the benzenoid ring. Compounds 13-36 were more active than metronidazole, the choice drug against Giardia intestinalis and most of them against Trichomonas vaginalis. The most active group of compounds for both parasites was that with a 2-ethoxycarbonyl group (16, 22, 28, 34), independently of the substitution pattern at the benzenoid ring.
- Valdez-Padilla, David,Rodriguez-Morales, Sergio,Hernandez-Campos, Alicia,Hernandez-Luis, Francisco,Yepez-Mulia, Lilian,Tapia-Contreras, Amparo,Castillo, Rafael
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experimental part
p. 1724 - 1730
(2009/08/08)
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- Solid phase synthesis of benzimidazole ketones and benzimidazole chalcones under solvent-free conditions
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Oxidation of 1-alkyl/aralkyl-2-(α-hydroxyalkyl/aryl)benzimidazoles 1 with KMnO4 on neutral alumina under solid phase conditions gives the corresponding ketones, 1-alkyl/aralkyl-2-acyl-benzimidazoles 2. Compound 2a (R2 = CH3) on condensation with aromatic aldehydes in the presence of solid NaOH under solvent-free conditions, yields the corresponding chalcones, 1-alkyl/aralkyl-2-benzimidazole aryl vinyl ketone 3.
- Dubey,Kumar, C. Ravi,Babu, Balaji
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p. 3128 - 3130
(2007/10/03)
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- Benzimidazolium dichromates: Efficient reagents for selective oxidation of alcohols to carbonyl compounds
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Benzimidazolium dichromates have been used for the selective and efficient oxidation of simple alcohols to carbonyl compounds. 2-Methylbenzimidazolium dichromate has been used as a standard compound. It has been found to oxidize selectively, primary alcohols to aldehydes, without any over-oxidation, and secondary alcohols to ketones. Of the several solvents explored, acetic acid at RT has been found to be the best medium for oxidation.
- Ramaiah,Dubey,Ramanatham,Kumar, C. Ravi,Grossert
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p. 1765 - 1767
(2007/10/03)
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- Lanthanide triple helical complexes with a chiral bis(benzimidazole)pyridine derivative
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The ligand neopentyl 2,6-bis[(1-methylbenzimidazol-2-yl)]-pyridine-4-carboxylate (L12) has been synthesised to test the effect of the chiral neopentyl ester group in the 4-position of the pyridine ring on (i) the helical wrapping, (ii) the diastereomeric induction and (iii) the thermodynamic and photophysical properties of the [Ln(L12)3]3+ complexes. The crystal structure of ligand L12 shows the expected trans-trans conformation of the tridentate binding unit. The ligand forms stable 1:3 complexes in anhydrous acetonitrile (logβ3 in the range 17.3-19.0, logK3 in the range 2.9-4.6). The triple helical structure in solution is responsible for the four times larger specific rotary dispersion measured in the complexes. Circularly polarised luminescence of the Eu triple helical complex displays a weak effect, suggesting a small diastereomeric excess in solution. Ligand L12 appears to favour a 37ππ*-to-Ln energy transfer process for Eu, but temperature-dependent nonradiative processes lead to a very small quantum yield. High-resolution luminescence spectra indicate that the Eu complex has a distorted D3 local symmetry at the metal ion site. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002).
- Muller, Gilles,Riehl, James P.,Schenk, Kurt J.,Hopfgartner, Gerard,Piguet, Claude,Buenzli, Jean-Claude G.
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p. 3101 - 3110
(2007/10/03)
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- Investigation of alkylating, antineoplastic and anti-HIV potentials of the chalcones: 2-(3-arylpropenoyl)benzimidazole and their corresponding N1-methyl derivatives
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A series of 2-(3-Arylpropenoyl)benzimidazole, 3a-d, and their corresponding N1-methyl analogues, 3e-h, were synthesized from p-substituted benzaldehyde and 2-acetylbenzimidazole or 2-acetyl-1-methylbenzimidazole, respectively. The in vitro alkylating activities of these α-β-unsaturated ketones were investigated using L-cysteine as a model of cellular thioles at pH 7.4 and 37°C. No significant difference between the alkylating activities of 3a-d and 3e-h as expressed from the pseudo first-order rate constants of the reactions of these derivatives with L-cysteine monitored by HPLC. However, significant variations in the rates of alkylation among these derivatives relative to the p-substituted group on the aryl moiety were observed, which is attributable to the electronic parameters of the substituted groups. The in vitro cytotoxic activity provided that the p-nitro derivative; 3d has some selectivity for cell lines of leukemia, renal cancer and breast cancer. The compounds were completely inactive as anti-HIV agents. Molecular modeling for all derivatives was undertaken.
- Aboul-Fadl,El-Shorbagi,Hozien,Sarhan
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p. 228 - 234
(2007/10/03)
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- An unusual resistance to α-bromination by arylacetyl compound: Studies on bromination of 2-acetylbenzimidazoles and their subsequent reactions with sulphur nucleophiles - Synthesis of novel β-ketosulphone derivatives of benzimidazoles
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Condensation of o-phenylenediamine with lactic acid under Phillips' conditions gave the known 2(α-hydroxyethyl)benzimidazole 1 which on oxidation with acid dichromate furnishes 2-acetylbenzimidazole 2. Reaction of 2 with bromine in acetic acid at room temp. give a novel product 3 but not the expected 2-(α-bromoacetyl)benzimidazole 4. Rational explanation is offered for this anamolous behaviour of 2. Compound 2 on alkylation, give 1- alkyl derivatives which undergo smooth bromination with bromine in acetic acid to give the corresponding 1-alkyl-2(α-bromoacetyl)benzimidazoles. Reactions of latter with sulphur nucleophiles such as PhS-, ArSO2- etc., resulting in substitution of bromine, leading to novel β-ketosulphone derivatives of benzimidazoles, are reported. Products have been characterised by IR, NMR (1H and 13C) and mass spectral data.
- Ramaiah,Dubey,Ramanatham,Grossert,Hooper
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p. 302 - 307
(2007/10/03)
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