Kalpana Mishra
Banaras Hindu University
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Featured researches published by Kalpana Mishra.
Organic chemistry frontiers | 2017
Kalpana Mishra; Jay Bahadur Singh; Tanu Gupta; Radhey M. Singh
A convenient method for the facile synthesis of 1-trifluoromethyl-3-alkylidene-1,3-dihydrofuro[3,4-b]quinolines was developed from the TBAB-catalyzed nucleophilic addition/cyclization reaction of o-arylalkynylquinoline aldehydes with trimethyl trifluoromethyl silane, cesium fluoride, and water; the product was obtained in good to excellent yields. The reaction proceeded smoothly via 5-exo-dig selectivity and anti co-planarity addition, affording Z-selective products in an aerobic atmosphere at room temperature. The dihydrofuroquinoline derivatives formed are structurally related to the well-known furoquinoline alkaloids of the rutaceae family.
Organic chemistry frontiers | 2017
Kalpana Mishra; Jay Bahadur Singh; Tanu Gupta; Radhey M. Singh
Ag(I)-Catalyzed one-pot synthesis of 4-fluorobenzo[b][1,6]naphthyridines is described from o-alkynylquinolinyl aldehydes through imines in good to excellent yields. Selectfluor is used as a fluorinating reagent and the reaction proceeded at room temperature in an open atmosphere. Reactions employed in this synthesis method are also applied for the synthesis of 8-fluoro-1,6-naphthyridine, 7-fluoro-pyrazolo[4,3-c]pyridine and 4-fluoroisoquinoline derivatives. Standardized conditions were also applied on a gram scale reaction and gave a good yield of the product.
RSC Advances | 2017
Tanu Gupta; Jay Bahadur Singh; Kalpana Mishra; Radhey M. Singh
We carried out simple and facile syntheses of acridines and phenanthridines from MBH acetates of 2-chloro-quinoline-3-carbaldehydes with active methylene compounds (AMCs). Formation of products was found to be dependent on the functional group of the AMC. For example, ethylcyanoacetate and malononitrile favoured the formation of acridines and cyanoacetamide, and ethyl nitroacetate and malonic esters favoured formation of angularly-fused phenanthridines. The reactions leading to the formation of phenanthridines proceeded through single bond rotation of SN2′ intermediate which was attributed to electronic/steric repulsion between the functional groups of AMCs and the nitrogen of quinoline.
New Journal of Chemistry | 2018
Jay Bahadur Singh; Kalpana Mishra; Tanu Gupta; Radhey M. Singh
Cu-catalyzed cascade reaction of 2-chloroquinoline-3-carbonitriles with benzyl amines and sodium hydroxide in aerobic atmosphere has been developed for the synthesis of pyrimido[4,5-b]quinoline-4-ones. The reaction proceeds sequentially via Ullmann-coupling and conversion of nitrile to amide followed by nucleophilic addition of amide nitrogen onto iminium carbon and air oxidation. Reagents and substrates are cheap and easily available/accessible. Plausible mechanism of reaction is also discussed.
Tetrahedron Letters | 2014
Durgesh Nandini; Mrityunjaya Asthana; Kalpana Mishra; Rajpal Singh; Radhey M. Singh
Organic and Biomolecular Chemistry | 2016
Kalpana Mishra; Ashok Kumar Pandey; Jay Bahadur Singh; Radhey M. Singh
ChemistrySelect | 2017
Jay Bahadur Singh; Kalpana Mishra; Tanu Gupta; Radhey M. Singh
European Journal of Organic Chemistry | 2018
Tanu Gupta; Jay Bahadur Singh; Kalpana Mishra; Biswajit Maiti; Radhey M. Singh
Tetrahedron Letters | 2014
Neha Sharma; Mrityunjaya Asthana; Ritush Kumar; Kalpana Mishra; Radhey M. Singh
Tetrahedron Letters | 2018
Kalpana Mishra; Kishor Chandra Bharadwaj; Radhey M. Singh