BITS Faculty Publications
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Item Copper catalyzed tandem oxidative C–H amination/cyclizations: Direct access to imidazo[1,2-a]pyridines(RSC, 2013) Khungar, Bharti; Kumar, AnilA simple and convenient strategy is described for the synthesis of imidazo[1,2-a]pyridines via inexpensive copper-catalyzed tandem imine formation and intramolecular aerobic oxidative C–H bond amination/cyclizations. An array of imidazo[1,2-a]pyridines were prepared by the reaction of readily available acetophenones and 2-aminopyridines in good to excellent yields (48–92%). The scope of the method was validated by a single step synthesis of Zolimidine, a drug used for peptic ulcers, in 61% yield.Item Synthesis of Naphtho-Fused Imidazo[1,2-a]pyridines through Copper-Catalyzed Cascade Reactions(Wiley, 2015-09-15) Kumar, AnilA library of π-extended naptho-fused imidazo[1,2-a]pyridines were assembled by a copper-catalyzed cascade reaction using simple starting materials and mild reaction conditions. This protocol has high functional group tolerance and afforded the heterocyclic products in moderate to excellent yields (35–91 %). Photophysical studies show that these naphtho[1′,2′:4,5]imidazo[1,2-a]pyridines emit with high fluorescence quantum yields. EWG=electron-withdrawing group.Item Copper-catalyzed tandem Ullmann type C–N coupling and dehydrative cyclization: synthesis of imidazo[1,2-c]quinazolines(RSC, 2016) Kumar, AnilA simple and efficient one-pot protocol has been demonstrated for the synthesis of imidazo[1,2-c]quinazoline derivatives through a copper catalyzed tandem reaction between substituted 2-(2-bromophenyl)-1H-imidazoles and formamide. The synthetic protocol involves initial Ullmann-type C–N coupling followed by intramolecular dehydrative cyclization. The method uses readily available 2-(2-bromophenyl)-1H-imidazoles as the starting materials to afford imidazo[1,2-c]quinazolines in moderate to good yields and provided 610 mg (71%) yield of 3a from a gram scale reaction.Item Copper-catalyzed synthesis of quinoline derivatives via tandem Knoevenagel condensation, amination and cyclization(RSC, 2016) Kumar, Anil; Kumar, DalipA novel regioselective synthesis of 2-aminoquinolines and 2-arylquinoline-3-carbonitriles is described via copper-mediated tandem reaction. Formation of substituted quinolines involves Knoevenagel condensation of ortho-bromobenzaldehyde with active methylene nitriles followed by copper-catalyzed reductive amination and intramolecular cyclization.Item A Facile Synthesis of Quinazolin-4(3H)-ones via Copper-Catalyzed One-Pot, Three-Component Tandem Reaction(Wiley, 2017-09-13) Kumar, Anil; Kumar, DalipA simple and convenient one-pot, three-component tandem reaction has been developed for the synthesis of substituted quinazolin-4(3H)-ones using CuI/L-proline as catalytic system. A series of 35 quinazolin-4(3H)-ones was synthesized in good to high yield. The method involves copper-catalyzed double C−N coupling, reductive amination, condensation, cyclization and aerobic oxidation. Good functional group tolerance, mild reaction condition, readily available starting materials and user friendly procedure makes this protocol practically good and attractive method for the synthesis of quinazolin-4(3H)-ones.Item Copper-Catalyzed Tandem Imine Formation, Sonogashira Coupling and Intramolecular Hydroamination: A Facile Synthesis of 3-Aryl-γ−carbolines(Wiley, 2021-11-25) Kumar, Anil; Kumar, DalipA one-pot, atom-economical multicomponent reaction of 2-bromoindole-3-carbaldehydes, alkynes and ammonia was developed in the presence of copper catalyst for the synthesis of a series of 3-aryl-γ−carboline derivatives in good to high yields. The developed reaction involved formation of imine followed by copper-catalyzed directed Sonogashira coupling and intramolecular hydroamination sequence of reactions. This multicomponent approach features mild reaction conditions and good functional group tolerance to access variety of 3-aryl γ-carbolines.Item Copper-Catalyzed One-Pot Tandem Reaction for the Synthesis of Imidazo[1,2-c][1,2,3]triazolo[1,5-a]quinazolines(Wiley, 2007-10-06) Kumar, AnilA Cu-catalyzed tandem reaction of 2-(2-bromoaryl)imidazoles/2-(2-bromoaryl)benzmidazoles, alkynes, and sodium azide is developed for the synthesis of imidazo[1,2-c][1,2,3]triazolo[1,5-a]quinazolines in moderate to excellent yields. This one-pot protocol includes copper-catalyzed azide–alkyne cycloaddition (CuAAC), intramolecular cross-dehydrogenative coupling (CDC), and Ullmann-type C–N coupling.Item Sequential Copper-Catalyzed Sonogashira Coupling, Hydroamination and Palladium-Catalyzed Intramolecular Direct Arylation: Synthesis of Azepino-Fused Isoindolinones(Wiley, 2017-11-09) Kumar, AnilA modular synthesis of azepino-fused isoindolinones has been developed in form of a sequential copper- and palladium-catalyzed tandem reaction. The developed protocol involved the formation of one carbon–nitrogen and two carbon–carbon bonds in a one-pot fashion. The palladium-catalyzed intramolecular direct-arylation step involves the formation of an unusual eight-membered palladacycle.