- Rapid synthesis of imidazo[4,5-b]pyridine containing polycyclics by means of palladium-catalyzed amidation of 2-chloro-3-nitropyridine
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Regioselective nucleophilic substitution of 2-chloro 3-nitropyridine with heterocyclic amides under Pd-catalyzed reaction conditions as described by Buchwald yielded imidazo [4,5-b] pyridine-containing polycyclics as novel scaffolds.
- Salomé, Christophe,Schmitt, Martine,Bourguignon, Jean-Jacques
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- Aqueous synthesis of 1-H-2-substituted benzimidazoles via transition-metal-free intramolecular amination of aryl iodides
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A straightforward method has been developed for the synthesis of the benzimidazole ring system through a carbon-nitrogen cross-coupling reaction. In the presence of 2.0 equiv. of K2CO3 in water at 100 °C for 30 h, the intramolecular cyclization of N-(2-iodoaryl)benzamidine provides benzimidazole derivatives in moderate to high yields. Remarkably, the procedure occurs exclusively in water and doesn't require the use of any additional reagent/catalyst, rendering the methodology highly valuable from both environmental and economical points of view.
- Chen, Chunxia,Chen, Chen,Li, Bin,Tao, Jingwei,Peng, Jinsong
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- Sodium sulfide: A sustainable solution for unbalanced redox condensation reaction between o -nitroanilines and alcohols catalyzed by an iron-sulfur system
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Unbalanced redox condensation reaction between o-nitroanilines and alcohols, leading to benzimidazole and quinoxaline heterocycles can be efficiently promoted and catalyzed by sodium sulfide (40 mol%) in combination with iron(III) chloride hexahydrate (1 mol%). Beside the role as a precursor for the iron-sulfur (Fe/S) catalyst formation, hydrated sodium sulfide was shown to be an excellent noncompetitive, multi-electron reducing agent.
- Nguyen, Thanh Binh,Ermolenko, Ludmila,Al-Mourabit, Ali
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- Copper-catalyzed, one-pot, three-component synthesis of benzimidazoles by condensation and C-N bond formation
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Benzimidazoles were synthesized by the copper-catalyzed, one-pot, three-component reaction of 2-haloanilines, aldehydes, and NaN3. The reaction was optimized when 2-iodo- or 2-bromoanilines (1.0 equiv), aldehydes (1.2 equiv), NaN3 (2.0 equiv), 5 mol% of CuCl, and 5 mol % of TMEDA were reacted in DMSO at 120 °C for 12 h. Good yields resulted, and the reaction showed tolerance toward functional groups such as ester, nitro, and chloro. Aliphatic and heteroaromatic aldehydes also afforded the desired products in moderate to good yields.
- Kim, Yong,Kumar, Manian Rajesh,Park, Namjin,Heo, Yumi,Lee, Sunwoo
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- Non-metal-mediated: N -oxyl radical (TEMPO)-induced acceptorless dehydrogenation of N-heterocycles via electrocatalysis
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The development of protocols for direct catalytic acceptorless dehydrogenation of N-heterocycles with metal-free catalysts holds the key to difficulties in green and sustainable chemistry. Herein, an N-oxyl radical (TEMPO) acting as an oxidant in combination with electrochemistry is used as a synthesis system under neutral conditions to produce N-heterocycles such as benzimidazole and quinazolinone. The key feature of this protocol is the utilization of the TEMPO system as an inexpensive and easy to handle radical surrogate that can effectively promote the dehydrogenation reaction. Mechanistic studies also suggest that oxidative TEMPOs redox catalytic cycle participates in the dehydrogenation of 2,3-dihydro heteroarenes. This journal is
- Hou, Huiqing,Ke, Fang,Lin, Mei,Ma, Xinhua,Shi, Sunjie,Sun, Weiming,Wu, Mei,Ye, Yaling,Zheng, Wenhe
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p. 5483 - 5488
(2022/03/01)
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- A heterogeneous catalytic strategy for facile production of benzimidazoles and quinoxalines from primary amines using the Al-MCM-41 catalyst
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This study reports a straightforward heterogeneous catalytic (Al-MCM-41) approach to synthesize nitrogen heterocycle moieties from primary amines under solvent-free conditions. The Al-MCM-41 catalyst was prepared using a hydrothermal method and characterized by various analytical techniques. The probability and limitations of the catalytic methodology were presented with various substrates. The catalytic method grants an attractive route to a wide variety of benzimidazole and quinoxaline moieties with good to excellent yields. The gram scale reaction and reusability (up to five cycles) of the Al-MCM-41 catalyst would greatly benefit industrial applications. This journal is
- Vasu, Amrutham,Naresh, Mameda,Krishna Sai, Gajula,Divya Rohini, Yennamaneni,Murali, Boosa,Ramulamma, Madasu,Ramunaidu, Addipilli,Narender, Nama
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p. 9439 - 9446
(2021/12/09)
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- A one-step synthesis of substituted benzo- and pyridine-fused 1H-imidazoles
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Substituted benzimidazoles and pyrimidazoles are an important group of heterocyclic aromatic organic compounds in the field of medicinal chemistry. A one-step microwave accelerated synthesis of substituted benzo- and pyridine-fused 1H-imidazoles has been described. Mechanistically, the reaction proceeds by reacting substituted 2-fluoronitrobenzene and substituted arylamine through the formation of N-hydroxy intermediate, which at higher temperature cleaves to afford the desired product. This approach achieved reductions in reaction times, higher yields, cleaner reactions than the previously described synthetic processes.
- Bhatt, Ashish,Kant, Ravi,Kumar, Sonu,Reddy, Yella,Sarmah, Manash P.
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- Heteroaromatic Inhibitors of the Astacin Proteinases Meprin α, Meprin β and Ovastacin Discovered by a Scaffold-Hopping Approach
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Astacin metalloproteinases, in particular meprins α and β, as well as ovastacin, are emerging drug targets. Drug-discovery efforts have led to the development of the first potent and selective inhibitors in the last few years. However, the most recent compounds are based on a highly flexible tertiary amine scaffold that could cause metabolic liabilities or decreased potency due to the entropic penalty upon binding to the target. Thus, the aim of this study was to discover novel conformationally constrained scaffolds as starting points for further inhibitor optimization. Shifting from flexible tertiary amines to rigid heteroaromatic cores resulted in a boost in inhibitory activity. Moreover, some compounds already exhibited higher activity against individual astacin proteinases compared to recently reported inhibitors and also a favorable off-target selectivity profile, thus qualifying them as very suitable chemical probes for target validation.
- Tan, Kathrin,J?ger, Christian,K?rschgen, Hagen,Geissler, Stefanie,Schlenzig, Dagmar,Buchholz, Mirko,St?cker, Walter,Ramsbeck, Daniel
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supporting information
p. 976 - 988
(2020/12/25)
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- Oxidative Cyclization Approach to Benzimidazole Libraries
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An efficient approach to the parallel synthesis of benzimidazoles from anilines is described. Library approaches to vary the N1 and C2 vectors of benzimidazoles are well established; however, C4-C7 variation has traditionally relied on 1,2-dianiline build
- Arnold, Eric P.,Mondal, Prolay K.,Schmitt, Daniel C.
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supporting information
p. 1 - 5
(2020/02/20)
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- HETEROAROMATIC INHIBITORS OF ASTACIN PROTEINASES
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The present invention relates to novel hydroxamic acid derivatives useful as inhibitors of astacin metalloproteinases, in particular procollagen C-proteinase (PCP) enzymes, meprins, ovastacin and/or nematode astacins; more particularly human or mammalian
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Paragraph 0110; 0114
(2020/12/22)
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- Catalyst-free one-pot synthesis of benzimidazoles from 1,2-diaminoarenes and alcohols
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A new and efficient protocol is described for the one-pot synthesis of benzimidazoles from a variety of aryl alcohols and 1,2-diaminoarenes. The yields were ranging from moderate to excellent. Moreover, the present method is utilizing alcohols instead of aldehydes and the reactions are carried out under solvent- and catalyst-free conditions, offering an environmentally benign process.
- Marri, Mahender Reddy,Peraka, Swamy,Macharla, Arun Kumar,Mameda, Naresh,Kodumuri, Srujana,Nama, Narender
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supporting information
p. 6520 - 6525
(2015/01/08)
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- Double proton transfer induced twisted intramolecular charge transfer emission in 2-(4a?2- N, N -Dimethylaminophenyl)imidazo[4,5-b]pyridine
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The spectral characteristics of N,N-dimethyl-4-(4-methyl-4H-imidazo[4,5-b] pyridin-2-yl)benzenamine (PyN-Me), 1-methyl-2-(4a?2-(N,N- dimethylaminophenyl)imidazo[4,5-b]pyridine (ImNH-Me), and 2-phenylimidazo[4,5-b] pyridine (PIP) are investigated to unders
- Mishra, Anasuya,Sahu, Saugata,Dash, Nihar,Behera, Santosh Kumar,Krishnamoorthy
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p. 9469 - 9477
(2013/09/12)
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- Regioselective C2-arylation of imidazo[4,5-b]pyridines
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We show that N3-MEM-protected imidazo[4,5-b]pyridines undergo efficient C2-functionalisation via direct C-H arylation. Twenty-two substituted imidazo[4,5-b]pyridines are prepared and iterative, selective elaboration of functionalised imidazo[4,5-b]pyridin
- Macdonald, Jonathan,Oldfield, Victoria,Bavetsias, Vassilios,Blagg, Julian
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p. 2335 - 2347
(2013/04/23)
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- Eco-friendly and facile synthesis of 2-substituted-1H-imidazo[4,5-b]pyridine in aqueous medium by air oxidation
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We report a new environmentally-benign, convenient, and facile methodology for the synthesis of 2-substituted-1H-imidazo[4,5-b]pyridine. The reaction of 2,3-diaminopyridine with substituted aryl aldehydes in water under thermal conditions without the use
- Kale, Rajesh P.,Shaikh, Mohammad U.,Jadhav, Ganesh R.,Gill, Charansingh H.
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scheme or table
p. 1780 - 1782
(2009/07/19)
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- Microwave-assisted one step high-throughput synthesis of benzimidazoles
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One-pot synthesis of benzimidazoles from diamines and carboxylic acids was developed under microwave irradiation condition, which provided a practical and efficient method for high-throughput synthesis of this important class of heterocyclic compounds.
- Lin, Shou-Yuan,Isome, Yuko,Stewart, Ethan,Liu, Ji-Feng,Yohannes, Daniel,Yu, Libing
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p. 2883 - 2886
(2007/10/03)
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- Unambiguous structural assignment of monoanils obtained from 2,3-pyridinediamines
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The reaction of 2,3-pyridinediamine la and its 5-bromo analogue lb independently with aromatic aldehydes results in the formation of 2-amino-and 5-bromo-2-amino-3-arylideneaminopyridines (2a and 2b) respectively. The structure of 2 has been confirmed by single crystal X-ray analysis, thereby ruling out the alternate structure for these compounds.
- Dubey,Kumar, R. Vinod,Kulkarni, Subhash M.,Sunder, G. Hema,Smith, Graham,Kennard, Collin H. L.
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p. 952 - 956
(2007/10/03)
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- Structure and reactions of monoanils obtained from 2,3-pyridinediamines
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The reaction of 2,3-pyridinediamines 1 with aromatic aldehydes results in the formation of 2-amino-3-arylideneaminopyridines 2 respectively. Dehydrogenative cyclisation of 2 with different reagents give 2-aryl-1H-imidazo[4,5-b]pyridines 4. Reactions of 2 with different reagents have been described.
- Dubey,Kulkarni,Vinod Kumar
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p. 361 - 367
(2007/10/03)
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- Studies on aroylation of 2,3-pyridinediamines
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The reaction of 2,3-pyridinediamine 1a and its 5-bromo analogue 1b, independently, with acid chloride or anhydride does not yield the diaroyl derivative and instead yields the cyclised product 3 or the monoaroyl derivative 4 depending upon the conditions.
- Dubey,Vinod Kumar
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p. 746 - 751
(2007/10/03)
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- AN EXPEDIENT ROUTE TO 1H-BENZIMIDAZOLES AND 1H-IMIDAZOPYRIDINES
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1H-Benzimidazoles, 1H-imidazopyridines, and 1H-imidazopyridines can be synthesized readily by reaction of unisolated N-(1-chloroalkyl)pyridinium chlorides with 1,2-benzenediamines, 2,3-pyridinediamine, and 3,4-pyridinediamine, respectively.
- Eynde, Jean-Jacques Vanden,Mayence, Annie,Maquestiau, Andre,Anders, Ernst
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p. 357 - 364
(2007/10/02)
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- Synthesis of Amidines and Attempted Synthesis of Imidazoazines by Reactions of Lithiated β-Aminoazines with Nitriles
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Deprotonation of 3-aminopyridine, followed by reaction of aromatic nitriles, gives N-(3-pyridyl)-benzamidines, and other β-aminoazines (pyridines, quinolines, pyrazines, pyrimidines) react similarly.Attempts to cyclise the amidines to, for example, 2-aryl
- Redhouse, Alan D.,Thompson, Robin J.,Wakefield, Basil J.,Wardell, Jacklyn A.
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p. 7619 - 7628
(2007/10/02)
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- PREPARATION OF 2-ARYL-SUBSTITUTED IMIDAZOPYRIDINES AND IMIDAZOPYRIDINES
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It is proposed that sulfur be used as the oxidizing agent in the synthesis of 2-arylimidazopyridines from o-diaminopyridines and aromatic (heteroaromatic) aldehydes.Benzyl alcohols and benzylpyridinium salts can be used in place of aldehydes. 2-Phenylimid
- Yutilov, Yu. M.,Shcherbina, L. I.
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p. 529 - 535
(2007/10/02)
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- Structure-activity relationships of arylimidazopyridine cardiotonics: Discovery and inotropic activity of 2-[2-methoxy-4-(methylsulfinyl)phenyl]-1H-imidazo[4,5-c]pyridine
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Recently several noncatecholamine, nonglycoside cardiotonic drugs have been discovered that possess both inotropic and vasodilator activities in experimental animals and man. Prototypical compounds include amrinone, sulmazole, and fenoximone. We investigated the structural requirements necessary for optimal inotropic activity in a series of molecules containing a heterocyclic ring fused to 2-phenylimidazole and discovered that 2-phenylimidazo[4,5-c]pyridines were generally 5-10-fold more potent than analogous 2-phenylimidazo[4,5-b]pyridines (e.g., sulmazole) or 8-phenylpurines. Furthermore, all imidazo[4,5-c]pyridine analogues we tested were orally active; in contrast, only one of the imidazo[4,5-b]pyridine derivatives, sulmazole, was significantly active. One of several highly active compounds in the [4,5-c] series was 50 (LY175326, 2-[2-methoxy-4-(methylsulfinyl)phenyl]-1H- imidazo[4,5-c]pyridine hydrochloride). The structure-activity relationship of this series is presented and compared to that of the imidazo[4,5-b]pyridine and purine series.
- Robertson,Beedle,Krushinski,Pollock,Wilson,Wyss,Hayes
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p. 717 - 727
(2007/10/02)
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- Carbon-13 NMR Spectra of Isomeric 2-Arylimidazopyridines
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The 13C NMR spectra of some 2-arylimidazo-- and -pyridines and their protonated forms have been studied.The nitrogen atom of the pyridine ring has been shown to be the most basic nitrogen in these compounds.
- Tretyakov, A. V.,Rudaya, L. I.,El'tsov, A. V.,Larin, M. F.,Lopyrev, V. A.
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- Heterocyclisation via Selective Elimination: Reaction of 2,3-Diaminopyridine with Acyclic Ketones under Thermal Conditions
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Reactions of 2,3-diaminopyridine and its 5-bromo analogue with three symmetrical and nine unsymmetrical acyclic ketones under thermal conditions have been studied.The reactions have yielded 2-substituted-1H-imidazopyridines by the elimination of one of the C2-substituents from the probable, though unisolated, intermediates 2,2-disubstituted-2,3-dihydro-1H-imidazopyridine derivatives.Elimination of one of the groups in the case of symmetrical ketones and preferentially of benzyl group in the case of benzyl methyl ketone has been observed.All the three alkyl phenyl ketones studied afford 2-phenylimidazopyridine by the selective loss of the alkyl group.Elimination of branched alkyl group has been noticed in the reactions involving methyl t-butyl and methyl i-propyl ketones, while the preferential elimination of methyl group is observed in the case of methyl n-alkyl ketones.Suitable explanations have been offered for the observed selective eliminations.
- Dubey, Pramod Kumar,Ratnam, C. V.
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p. 863 - 865
(2007/10/02)
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