- Oxidation Potential-Guided Electrochemical Radical-Radical Cross-Coupling Approaches to 3-Sulfonylated Imidazopyridines and Indolizines
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Oxidation potential-guided electrochemical radical-radical cross-coupling reactions between N-heteroarenes and sodium sulfinates have been established. Thus, simple cyclic voltammetry measurement of substrates predicts the likelihood of successful radical-radical coupling reactions, allowing the simple and direct synthetic access to 3-sulfonylated imidazopyridines and indolizines. The developed electrochemical radical-radical cross-coupling reactions to sulfonylated N-heteroarenes boast the green synthetic nature of the reactions that are oxidant- and metal-free.
- Kim, Wansoo,Kim, Hun Young,Oh, Kyungsoo
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p. 15973 - 15991
(2021/07/26)
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- Design, synthesis and anticancer activity of sulfenylated imidazo-fused heterocycles
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We report herein, the design, synthesis and study of anticancer properties of sulfenylated 2-phenylimidazo[1,2-a]pyridines and their analogues. A set of twenty sulfenylated imidazo[1, 2-a]pyridine derivatives were synthesized. Whereby elusive amendments to the imidazo[1,2-a]pyridine motif confer dramatic changes in functional affinity of a novel action to modulate anticancer activity in seven different human cancer cell lines i.e.: MDA MB 231 (breast), HepG2 (liver), Hela (cervical), A549 (lung), U87MG (glioblastoma), SKMEL-28 (skin melanoma) and DU-145 (prostate) by employing MTT assay. Among the series, compounds 4e (naphthalene), 4f (styrene) and 4h (thiomethyl) showed potent activity towards human liver cancer cells HepG2. Cell cycle analysis results revealed that these compounds arrested the cell cycle at G2/M phase and induced apoptosis in human liver cancer cells HepG2. It was further confirmed by Hoechst staining, Measurement of mitochondrial membrane potential (ΔΨm) and Annexin V-FITC assay.
- Chitrakar, Ravi,Rawat, Deepa,Sistla, Ramakrishna,Subbarayappa, Adimurthy,Vadithe, Lakshma Nayak
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supporting information
(2021/08/13)
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- CuCl2-catalyzed N[sbnd]O bond cleavage of oxime esters: Approach to imidazoheterocycles and furo[3,2-c]chromenyl fused imidazoles
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An articulate approach to a diverse set of imidazoheterocycles in good to high yields via a copper-catalyzed aza-annulation of several oxime esters with a group of 2-amino-azaarenes was developed. The above cyclization reaction probably proceeds via a single electron transfer process which embodies a new technique for creating two new C[sbnd]N bonds for imidazole ring synthesis. Gratifyingly, the implementation of this chemistry could be further stretched to the synthesis of a novel class of fused imidazoles bearing a furo[3,2-c]chromene moiety via a sequential C[sbnd]N bond formation, followed by C(sp2)-H functionalization/5-endo-dig-oxacyclization (C[sbnd]C and C[sbnd]O bonds) of in situ produced fused imidazoles with cyclic enynones in the presence of copper(II) as a π-electrophilic Lewis acid catalyst.
- Gudimella, Santosh K.,Kaur, Amanpreet,Kumar, Ram,Samanta, Sampak
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- Transition-Metal-Free Direct Trifluoromethylation and Perfluoroalkylation of Imidazopyridines under Mild Conditions
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The first transition-metal-free method for direct C?H trifluoromethylation of imidazo[1,2-a]pyridine derivatives with readily available Ruppert-Prakash reagent TMSCF3 under mild conditions was described. Moreover, this method could be applied to direct C?H perfluoroalkylation of imidazopyridines, affording a series of novel perfluoroalkylated products in moderate to good yields. Notable advantages of this protocol include easy operation, high-efficiency and wide substrate scope. (Figure presented.).
- Han, Shuaijun,Gao, Xianying,Wu, Qingsong,Li, Jingya,Zou, Dapeng,Wu, Yangjie,Wu, Yusheng
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supporting information
p. 1559 - 1563
(2019/02/19)
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- Iodine mediated oxidative cross coupling of 2-aminopyridine and aromatic terminal alkyne: A practical route to imidazo[1,2-: A] pyridine derivatives
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A novel, transition-metal free route leading to imidazo[1,2-a]pyridine derivatives via iodine mediated oxidative coupling between 2-aminopyridine and aromatic terminal alkyne has been demonstrated. This newly developed method discloses an operationally simple way for the construction of imidazoheterocycles. Commercially available antiulcer drug zolimidine may readily be synthesized employing this method.
- Samanta, Surya Kanta,Bera, Mrinal K.
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p. 6441 - 6449
(2019/07/10)
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- Electrochemically initiated intermolecular C-N formation/cyclization of ketones with 2-aminopyridines: An efficient method for the synthesis of imidazo[1,2-: A] pyridines
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Electrochemical intermolecular C-N formation/cyclization of ketones with 2-aminopyridines using catalytic hydriodic acid as the redox mediator was developed, providing imidazo[1,2-a]pyridines under more environmentally benign conditions. The reaction proceeds in a simple undivided cell, using low toxic ethanol as the solvent, without external oxidants, and exhibits high atom economy. A variety of ketones including acetophenones, unsatruated and alkyl ketones are amenable to this reaction, affording the corresponding products in moderate to excellent yields. A three-component tandem reaction realizing C-N, C-S/C-Se bond formation can also be achieved under standard conditions.
- Feng, Mei-Lin,Li, Shu-Qi,He, Hui-Zi,Xi, Long-Yi,Chen, Shan-Yong,Yu, Xiao-Qi
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supporting information
p. 1619 - 1624
(2019/04/08)
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- Iron(III)-catalyzed three-component domino strategy for the synthesis of imidazo[1,2-a]pyridines
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An efficient, one-pot, three-component domino strategy has been demonstrated for the synthesis of imidazo[1,2-a]pyridines using a catalytic amount of Fe(III) chloride in high yields in air. A library of imidazo[1,2-a]pyridines was synthesized by the reaction of easily available aldehydes and 2-aminopyridines in a mixture of nitroalkane and DMF (2:1). This transformation presumably occurs by a sequential aza-Henry reaction/cyclization/denitration. The use of readily available chemicals as starting materials, inexpensive metal catalyst, aerobic reaction conditions, tolerance of a wide range of functional groups, and operational simplicity are the notable advantages of this present protocol.
- Santra, Sougata,Mitra, Shubhanjan,Bagdi, Avik Kumar,Majee, Adinath,Hajra, Alakananda
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supporting information
p. 5151 - 5155
(2014/12/10)
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- Iron(III)-catalyzed denitration reaction: One-pot three-component synthesis of imidazo[1,2-a]pyridine derivatives
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An iron(III)-catalyzed one-pot three-component cross-coupling nitration reaction of 2-aminopyridines, aldehydes and nitroalkanes, straightforwardly forms imidazo[1,2-a]pyridine derivatives and is described in this report. The system shows good functional-group tolerance and proceeds smoothly in moderate to good yields. An iron(III)-catalyzed one-pot three-component cross-coupling nitration reaction of 2-aminopyridines, aldehydes, and nitroalkane, leading to the straightforward formation of imidazo[1,2-a]pyridine derivatives has been reported. In this procedure, the starting materials are commercially available. The system shows good functional-group tolerance and proceeds smoothly in moderate to good yields. Copyright
- Yan, Hao,Wang, Yuling,Pan, Congming,Zhang, Hao,Yang, Sizhuo,Ren, Xiaoyu,Li, Jian,Huang, Guosheng
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p. 2754 - 2763
(2014/05/06)
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- Copper(I) iodide-catalysed aerobic oxidative synthesis of imidazo [1,2-α]pyridines from 2-aminopyridines and methyl ketones
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We report here an operationally simple copper-catalysed synthesis of imidazo [1,2-α]pyridines through C-H activation with oxidative linkage of two C-N bonds under very mild conditions using molecular oxygen as a sole oxidant. The process allows the quick assembly of imidazo [1,2-α]pyridines including the antiulcer drug zolimidine from inexpensive and readily available 2-aminopyridines and methyl ketones with broad range of functional group tolerance.
- Mohan, Darapaneni Chandra,Donthiri, Ramachandra Reddy,Rao, Sadu Nageswara,Adimurthy, Subbarayappa
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p. 2217 - 2221
(2013/10/01)
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- Iron(III)-Catalyzed Cascade Reaction between Nitroolefins and 2-Aminopyridines: Synthesis of Imidazo[1,2-a]pyridines and Easy Access towards Zolimidine
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The iron(III)-catalyzed one-pot cascade reaction between nitroolefins and 2-aminopyridines has been demonstrated for the synthesis of imidazo[1,2-a] pyridines by exploiting the bielectrophilic nature of nitroolefins. This methodology could be successfully
- Santra, Sougata,Bagdi, Avik Kumar,Majee, Adinath,Hajra, Alakananda
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supporting information
p. 1065 - 1070
(2013/06/05)
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- Copper-catalyzed synthesis of imidazo[1,2-a]pyridines through tandem imine formation-oxidative cyclization under ambient air: One-step synthesis of zolimidine on a gram-scale
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A new copper-catalyzed oxidative cyclization via C-H amination between 2-aminopyridines and methyl aryl/heteroaryl ketones has been developed under ambient air. Imidazo[1,2-a]pyridines containing a wide range of functional groups have been synthesized from basic and easily available starting materials. This simple, one-pot reaction protocol is applicable for the direct preparation of zolimidine (a marketed antiulcer drug) on a large scale. Copyright
- Bagdi, Avik Kumar,Rahman, Matiur,Santra, Sougata,Majee, Adinath,Hajra, Alakananda
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supporting information
p. 1741 - 1747
(2013/07/11)
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- Heteroaromatic imidazo[1,2-a]pyridines synthesis from C-H/N-H oxidative cross-coupling/cyclization
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A novel silver-mediated highly selective C-H/N-H oxidative cross-coupling/cyclization between 2-aminopyridines and terminal alkynes has been demonstrated. This approach provided a simple way to construct heteroaromatic imidazo[1,2-a]pyridines. By using this protocol, the marketed drug zolimidine (antiulcer) could be synthesized easily.
- He, Chuan,Hao, Jing,Xu, Huan,Mo, Yiping,Liu, Huiying,Han, Juanjuan,Lei, Aiwen
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supporting information
p. 11073 - 11075,3
(2012/12/12)
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- Heteroaromatic imidazo[1,2-a]pyridines synthesis from C-H/N-H oxidative cross-coupling/cyclization
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A novel silver-mediated highly selective C-H/N-H oxidative cross-coupling/cyclization between 2-aminopyridines and terminal alkynes has been demonstrated. This approach provided a simple way to construct heteroaromatic imidazo[1,2-a]pyridines. By using this protocol, the marketed drug zolimidine (antiulcer) could be synthesized easily.
- He, Chuan,Hao, Jing,Xu, Huan,Mo, Yiping,Liu, Huiying,Han, Juanjuan,Lei, Aiwen
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supporting information
p. 11073 - 11075
(2013/01/15)
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