- Investigations on peri-, regio- and stereoselectivities in thermal cycloadditions involving C-(4-oxo-4H[1]benzopyran-3-yl)-N-phenylnitrones: Role of steric factors and secondary interactions in 1,3-dipolar cycloadditions
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Complete peri-, regio- and stereoselectivities in thermal reactions of C-(4-oxo-4H[1]benzopyran-3-yl)-N-phenylnitrones with both electron-rich and electron-deficient olefins have been investigated. This conjugated nitrone undergoes frontier-orbital (LUMO-
- Ishar,Singh, Gurmit,Kumar, Kamal,Singh, Rajinder
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- 3-Formylchromone based topoisomerase IIα inhibitors: Discovery of potent leads
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Substituted 3-formylchromones were synthesized and evaluated as inhibitors of the human DNA topoisomerase IIα (hTopo-IIα) enzyme. The results of the decatenation, relaxation and DNA intercalation assays revealed that the compounds (11b, 12a, 12b, 12d, 12e, 13a and 13b) exhibited potent inhibitory activity against the hTopo-IIα enzyme, and are nonintercalating agents. These compounds also possess significant in vitro cytotoxicity (LC50 ranges from 0.5-8.6 μM) against prostate (PC-3) cancerous cell line as seen in comparison to the standard drug etoposide. To further probe the plausible mode of action of 3-formylchromone derivatives, molecular docking studies have also been carried out, which showed that the compounds under investigation fitted well in the ATP binding pocket of hTopo-IIα enzyme with good docking scores and form nonbonding interactions with the crucial residues of the catalytic site. The Royal Society of Chemistry.
- Singh, Satyajit,Baviskar, Ashish Triambak,Jain, Vaibhav,Mishra, Nidhi,Chand Banerjee, Uttam,Bharatam, Prasad V.,Tikoo, Kulbhushan,Singh Ishar, Mohan Paul
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p. 1257 - 1266
(2013/09/12)
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- Exploring α-chromonyl nitrones as 1,5-dipoles
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N-Phenyl-C-chromonyl nitrones 1 and the allenoate zwitterion 2, generated by addition of phosphine to acetylenedicarboxylates, undergo a cascade reaction sequence involving an unprecedented [5+3] annulation followed by deoxygenative rearrangement leading to dihydropyridine-fused benzopyrones. Unusual electronic control by the N-substituents of 1 directs the annulation pathway, leading to two different ring-systems. Georg Thieme Verlag Stuttgart - New York.
- Wittstein, Kathrin,García, Ana B.,Schürmann, Markus,Kumar, Kamal
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supporting information; experimental part
p. 227 - 232
(2012/03/10)
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- A one-pot rearrangement of 2-(N-Alkyl-N-aryl)aminochromone-3-carbaldehyde to N-Alkyl-3-salicyloyl-2-quinolone - An antileishmanial agent
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2-(N-Aryl)aminochromone-3-carbaldehyde does not show any change on heating in acetic acid, but under the same reaction conditions 2-(N-alkyl-N-aryl) aminochromone-3-carbaldehyde rearranges to 3-salicyloyl-2-quinolones, which exhibits antileishmanial activ
- Maiti, Sourav,Mallick, Suvadip,Panja, Suman Kalyan,Pal, Chiranjib,Bandyopadhyay, Chandrakanta
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p. 2001 - 2004
(2011/10/08)
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- Regio- and stereoselective synthesis of 1-benzopyrano[2,3-b]pyrrolo[2,3-d] pyridines: A microwave-accelerated intramolecular [3+2] cycloaddition reaction of azomethine ylide
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Figure represented. Regio- and stereoselective syntheses of tetracyclic compounds having chromone, pyrrolidine, and piperidine rings have been accomplished by an intramolecular [3+2] cycloaddition reaction involving azomethine ylide. The reactions were ca
- Maiti, Sourav,Lakshmykanth,Panja, Suman Kalyan,Mukhopadhyay, Ranjan,Datta, Ayan,Bandyopadhyay, Chandrakanta
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scheme or table
p. 763 - 768
(2011/09/16)
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- Reaction of amines with nitrones derived from chromone-3-carbaldehyde
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Nitronc 2 derived from 3-formylchromone 1 produces 3-aminomethylene-2- iminochroman-4-one 8 on reaction with primary amine 7, chromenoquinoline 14 with piperidine and dihydrotelraaza[14]annulene 15 with o-phenylenediamine.
- Maiti, Sourav,Panja, Suman Kalyan,Bandyopadhyay, Chandrakanta
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experimental part
p. 1447 - 1452
(2010/03/24)
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- A one-pot synthesis of 3,3′-methylenebis(2-arylamino-4H-chromen-4-one) from C-(4-oxo-4H-1-benzopyran-3-yl)-N-arylnitrone
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2-(Arylamino)-4-oxo-4H-chromene-3-carbaldehyde 3 (R2 = aryl) produces 12H-chromeno[2,3-b]quinolin-12-one 4 when treated with sarcosine, piperidine or diethylamine, but produces 3,3′-methylenebis(2-arylamino-4H-chromen-4-one) 8 when treated with
- Maiti, Sourav,Panja, Suman Kalyan,Bandyopadhyay, Chandrakanta
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experimental part
p. 3966 - 3969
(2009/10/11)
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- Domino routes to substituted benzoindolizines: tandem reorganization of 1,3-dipolar cycloadducts of nitrones with allenic esters/ketones and alternative cycloaddition-palladium catalyzed cyclization pathway
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Reactions of C-(4-oxo-4H[1]benzopyran-3-yl)-N-phenyl nitrones (7) with allenic esters (8a-c) and allenic ketones (18a-d) furnish benzoindolizines (9a-k, 19a-d) in good yields. The formation of benzoindolizines is postulated to involve regioselective addit
- Kapur, Ashish,Kumar, Kamal,Singh, Lakhwinder,Singh, Parminder,Elango, Munusamy,Subramanian, Venkatesan,Gupta, Vivek,Kanwal, Priyanka,Ishar, Mohan Paul S.
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experimental part
p. 4593 - 4603
(2009/10/23)
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- Intramolecular low-temperature 1,3-dipolar cycloadditions of nitrones: synthesis of chromano-heterocycles
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In contrast to the reported facile intramolecular 1,3-dipolar cycloadditions of in-situ generated nitrone on heterocyclic systems, reactions of 2-(N-allyl/crotyl/cinnamyl-anilino)-3-formylchromones with N-phenyl-/methylhydroxylamine under comparable condi
- Singh, Gurpinder,Ishar,Gupta, Vivek,Singh, Gurmit,Kalyan, Mohit,Bhella, Surinderjit Singh
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p. 4773 - 4778
(2007/10/03)
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- One-pot Synthesis of 2-alkyl/arylamino-4-oxo-4H-1-benzopyran-3-carboxaldehyde from 4-oxo-4H-1-benzopyran-3-carboxaldehyde
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Zn/NH4Cl - Mediated reactions of aldehyde 1 with nitro compounds 2 afford 2-(N-alkyl/arylamino)-3-formylchromones 4, which on heating with 70 percent H2SO4 produces 9a-d and 11e-h from 4a-d and 4e-h, respectively.
- Bandyopadhyay, Chandrakanta,Sur, Kumar Ranabir,Patra, Ranjan,Banerjee, Subhabrata
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p. 847 - 856
(2007/10/03)
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- A versatile route to 2-alkyl-/aryl-amino-3-formyl- and hetero-annelated-chromones, through a facile nucleophilic substitution at C2 in 2-(N-methylanilino)-3-formylchromones
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The N-methylanilino group in 2-(N-methylanilino)-3-formylchromones, obtained in high yield by rearrangement of C(4-oxo-4H[1]-benzopyran-3-yl)-N-phenylnitrones to 2-anilino-3-formyl-chromones followed by N-methylation, undergoes facile nucleophilic substitution by a variety of nitrogen nucleophiles, thereby paving the way for synthesis of a variety of novel 2-substituted-3-formylchromone derivatives as well as hetero-annelated chromones.
- Singh, Gurmit,Singh, Rajinder,Girdhar, Navdeep K,Ishar
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p. 2471 - 2480
(2007/10/03)
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- Thermal rearrangements of C-(4-Oxo-4H[1]benzopyran-3-yl)-N- phenylnitrone-a route to novel quinolino[2,3-b] chroman-12-ones
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C-(4-Oxo-4H[1]benzopyran-3-yl)-N-phenylnitrones (1a-c) undergo facile rearrangements on refluxing in benzene, yielding 2-(N-phenylamino)-4-oxo- 4H[1]-benzopyran-3-carboxaldehydes (2a-c,70%) and 3-(phenyliminomethylene)- chroman-2,4-diones (3a-c, 25%). 2a-
- Ishar,Kumar, Kamal,Singh, Rajinder
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p. 6547 - 6550
(2007/10/03)
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