The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Akhilesh K Verma - One of the best experts on this subject based on the ideXlab platform.
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selective synthesis of 4 5 dihydroimidazo and imidazo 1 5 a Quinoxalines via modified pictet spengler reaction
Tetrahedron Letters, 2013Co-Authors: Akhilesh K Verma, Rajeev R Jha, Kasi V Sankar, Ranjan K SinghAbstract:Abstract An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]Quinoxalines 6a–g and imidazo[1,5-a]Quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.
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lewis acid catalyzed selective synthesis of diversely substituted indolo and pyrrolo 1 2 a Quinoxalines and quinoxalinones by modified pictet spengler reaction
European Journal of Organic Chemistry, 2011Co-Authors: Akhilesh K Verma, Rajeev R Jha, Kasi V Sankar, Trapti Aggarwal, Rajendra Singh, Ramesh ChandraAbstract:An efficient tandem process for the selective synthesis of 1,2-annulated α-fused Quinoxalines using benzotriazole methodology by a modified Pictet–Spengler reaction is described. The approach involves the reaction of arylamines 4 with aromatic aldehydes 5 to furnish 6-endo-dig-cyclized products. DihydroQuinoxalines 6 were selectively obtained by using AlCl3 in tetrahydrofuran (THF) at room temperature for two hours. However, after ten hours, Quinoxalines 7 were obtained exclusively in excellent yields. A series of biologically important fluoro- and piperazenyl-substituted Quinoxalines were also synthesized. This developed methodology also provides access to a novel tandem synthesis of quinoxalinones 9.
Kasi V Sankar - One of the best experts on this subject based on the ideXlab platform.
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selective synthesis of 4 5 dihydroimidazo and imidazo 1 5 a Quinoxalines via modified pictet spengler reaction
Tetrahedron Letters, 2013Co-Authors: Akhilesh K Verma, Rajeev R Jha, Kasi V Sankar, Ranjan K SinghAbstract:Abstract An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]Quinoxalines 6a–g and imidazo[1,5-a]Quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.
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lewis acid catalyzed selective synthesis of diversely substituted indolo and pyrrolo 1 2 a Quinoxalines and quinoxalinones by modified pictet spengler reaction
European Journal of Organic Chemistry, 2011Co-Authors: Akhilesh K Verma, Rajeev R Jha, Kasi V Sankar, Trapti Aggarwal, Rajendra Singh, Ramesh ChandraAbstract:An efficient tandem process for the selective synthesis of 1,2-annulated α-fused Quinoxalines using benzotriazole methodology by a modified Pictet–Spengler reaction is described. The approach involves the reaction of arylamines 4 with aromatic aldehydes 5 to furnish 6-endo-dig-cyclized products. DihydroQuinoxalines 6 were selectively obtained by using AlCl3 in tetrahydrofuran (THF) at room temperature for two hours. However, after ten hours, Quinoxalines 7 were obtained exclusively in excellent yields. A series of biologically important fluoro- and piperazenyl-substituted Quinoxalines were also synthesized. This developed methodology also provides access to a novel tandem synthesis of quinoxalinones 9.
Anxin Wu - One of the best experts on this subject based on the ideXlab platform.
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copper catalyzed domino synthesis of 2 imino 1h imidazol 5 2h ones and Quinoxalines involving c c bond cleavage with a 1 3 dicarbonyl unit as a leaving group
Chemistry: A European Journal, 2014Co-Authors: Yan Yang, Anxin Wu, Fan NiAbstract:: Although 2-imino-1H-imidazol-5(2H)-ones have important biological activities in metabolism, their synthesis has rarely been investigated. Quinoxalines as "privileged scaffolds" in medicinal chemistry have been extensively investigated, but the development of novel and efficient synthetic methods remains very attractive. Herein, we have developed two copper-catalyzed domino reactions for the synthesis of 2-imino-1H-imidazol-5(2H)-ones and Quinoxalines involving CC bond-cleavage with a 1,3-dicarbonyl unit as a leaving group. The domino sequence for the synthesis of 2-imino-1H-imidazol-5(2H)-ones includes aza-Michael addition, intramolecular cyclization, CC bond-cleavage, 1,2-rearrangement, and aerobic dehydrogenation reaction, whereas the domino sequence for the synthesis of Quinoxalines includes aza-Michael addition, intramolecular cyclization, elimination reaction, and CC bond-cleavage reaction. The two domino reactions have significant advantages including high efficiency, mild reaction conditions, and high tolerance of various functional groups.
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a new route to construct 1 2 dihydroquinoxaline and 1 4 benzoxazine derivatives stereoselectively and its application to novel pyrazolo 1 5 α quinoxaline oxides
ChemInform, 2013Co-Authors: Dongxue Zhang, Yan Yang, Liuming Wu, Anxin WuAbstract:Both 1,4-benzoxazines (III) and Quinoxalines (VIII) are obtained stereoselectively via a novel approach from easily available 2-methylthio-1,4-enediones.
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logic design and synthesis of Quinoxalines via the integration of iodination oxidation cyclization sequences from ketones and 1 2 diamines
Tetrahedron, 2012Co-Authors: Mi Lian, Anxin WuAbstract:Abstract A novel protocol for the synthesis of Quinoxalines has been developed from simple ketones and 1,2-diamines. This process underwent a logic approach to bis-substituted Quinoxalines via a consecutive iodination/Kornblum oxidation/cyclization in the presence of I2/CuO/DMSO and to mono-substituted Quinoxalines via an iodination/cyclization/aromatization in the presence of I2/CuO/K3PO4·3H2O.
Mahendra Nath - One of the best experts on this subject based on the ideXlab platform.
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an eco friendly pictet spengler approach to pyrrolo and indolo 1 2 a Quinoxalines using p dodecylbenzenesulfonic acid as an efficient broensted acid catalyst
ChemInform, 2015Co-Authors: Amreeta Preetam, Mahendra NathAbstract:An efficient, facile, and environmentally friendly method for the synthesis of various pyrrolo[1,2-a]quinoxaline, dihydropyrrolo[1,2-a]quinoxaline, and spiro[indoline-3,4′-pyrrolo[1,2-a]quinoxalin]-2-one derivatives under mild reaction conditions is developed.
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an eco friendly pictet spengler approach to pyrrolo and indolo 1 2 a Quinoxalines using p dodecylbenzenesulfonic acid as an efficient bronsted acid catalyst
RSC Advances, 2015Co-Authors: Amreeta Preetam, Mahendra NathAbstract:A facile and environmentally benign Pictet–Spengler strategy for the synthesis of a series of biologically important pyrrolo- and indolo[1,2-a]Quinoxalines has been developed by reacting 1-(2-aminophenyl)-pyrrole or 1-(2-aminophenyl)indoles with a wide range of aromatic aldehydes, acetophenones or isatins in ethanol at ambient temperature using p-dodecylbenzenesulfonic acid (p-DBSA) as an efficient Bronsted acid–surfactant combined catalyst. This methodology was found to be applicable to generate diverse quinoxaline derivatives in fairly good yields under mild reaction conditions.
Nalilu Suchetha Kumari - One of the best experts on this subject based on the ideXlab platform.
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synthesis of some new 4 styryltetrazolo 1 5 a quinoxaline and 1 substituted 4 styryl 1 2 4 triazolo 4 3 a quinoxaline derivatives as potent anticonvulsants
European Journal of Medicinal Chemistry, 2009Co-Authors: Shivananda Wagle, Airody Vasudeva Adhikari, Nalilu Suchetha KumariAbstract:4-Methyltetrazolo[1,5-a]quinoxaline (3) was prepared by the azide cyclocondensation of 2-chloro-3-methylquinoxaline (2). The reaction of 3 with aromatic aldehydes furnished 4-styryltetrazolo[1,5-a]Quinoxalines (4a-f). Compound 2, on treatment with hydrazine hydrate gave 2-hydrazino-3-methylquinoxaline (5). The ring closure of 5 was achieved by the reaction of orthoesters and trifluoroacetic acid to yield 4-methyl-1-(substituted)[1,2,4]triazolo[4,3-a]Quinoxalines (7a-c). Further, reaction of 7a-c with different aromatic aldehydes furnished the title compounds, 4-styryl-1-(substituted)[1,2,4]triazolo[4,3-a]Quinoxalines (8a-i) in good yield. In another scheme, the hydrazino compound 5 was treated with different aromatic aldehydes to yield corresponding N-arylidenehydrazino Quinoxalines (6a-d). Further, the oxidative cyclization of hydrazones by nitrobenzene yielded 1-aryl-4-methyl[1,2,4]triazolo[4,3-a]Quinoxalines (7d-g), which on condensation with aromatic aldehydes gave the title compounds, 1-aryl-4-styryl[1,2,4]triazolo[4,3-a]Quinoxalines (8j-u). The newly synthesized compounds have been characterized by FTIR, (1)H NMR, (13)C NMR and mass spectral data, followed by elemental analysis. Some of the compounds were screened for in vivo anticonvulsant activity. Few of them exhibited promising results.
