Author
Sumit Kumar Karak
Bio: Sumit Kumar Karak is an academic researcher from University of Calcutta. The author has contributed to research in topics: Benzopyrans & Benzopyran. The author has an hindex of 3, co-authored 12 publications receiving 52 citations.
Topics: Benzopyrans, Benzopyran, Phenylhydrazine, Hydroxylamine, Pyrazole
Papers
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TL;DR: The 3-cyanochromone 3-oxide 4-oxo-4H1-benzopyran-3-yl moiety is referred to as Chr-X as discussed by the authors.
31 citations
TL;DR: In this article, the chromone 2A (X = H(A), Me(B), Cl(C)) gives a mixture of the dihydropyridine 4A and pyranopyridine 15A, 2B gives 4B, and 2C gives varying amounts of the substituted enamine 3C, pyridone 4Cand benzophenone 8.
Abstract: With ethyl (3-aminocrotonate, the chromone 2A (X = H(A), Me(B), Cl(C)) gives a mixture of the dihydropyridine 4A and pyranopyridine 15A, 2B gives 4B, and 2C gives varying amounts of the substituted enamine 3C, pyridone 4Cand benzophenone 8. 5-Hydroxy-5H-[1]benzopyrano-[4,3-b]pyridine 11 (< 3%) was obtained in each case. Palladised charcoal dehydrogenates dihydropyridines 4A and 4B to respectively 12A and 12B and ammonia converts 12A into the diazanaphthalene 13.
5 citations
TL;DR: The pyridinium methylid (5), generated from 1-(4-oxo-4H-1-benzopyran-2-yl)methylpyrinium iodide (4) in the presence of a base, undergoes cycloaddition with dimethyl acetylenedicarboxylate and ethyl propiolate, thecycloadducts rapidly aromatising to the indolizines (8) and (9) respectively as discussed by the authors.
Abstract: The pyridinium methylid (5), generated from 1-(4-oxo-4H-1-benzopyran-2-yl)methylpyridinium iodide (4) in the presence of a base, undergoes [3+2] cycloaddition with dimethyl acetylenedicarboxylate and ethyl propiolate, thecycloadducts rapidly aromatising to the indolizines (8) and (9), respectively. Similar cycloaddition of 5 with ethyl acrylate and acrylonitrile is also followed by dehydrogenation giving respectively the indolizines (9) and (10).
5 citations
TL;DR: The chromone 5, obtained by bromination of 3-acetyl-2-methylchromone (3), gives [1]benzoxepino[4,3-d]isoxazole (10) with hydroxylamine and phen... as mentioned in this paper.
Abstract: The chromone 5, obtained by bromination of 3-acetyl-2-methylchromone (3), gives [1]benzoxepino[4,3-d]isoxazole (10) and [1]benzoxepino[3,4-c]pyrazole (11), respectively, with hydroxylamine and phen...
4 citations
TL;DR: A comprehensive survey of the synthesis and chemistry of the title nitrile covering the literature published during 2005-2014 can be found in this paper, where a review article is designed to complement an earlier one (J. Heterocycl. Chem. 2005, 42, 1035-1042).
Abstract: The review article, primarily designed to complement an earlier one (J. Heterocycl. Chem. 2005, 42, 1035-1042), gives a comprehensive survey of the synthesis and chemistry of the title nitrile covering the literature published during 2005-2014.
3 citations
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TL;DR: In this article, the pyrone ring of 3-polyfluoroacyl-4 H -chromeno[3,4- d ]isoxazol-4-ols was opened by nucleophilic 1, 4-addition and subsequent cyclization to 4 polyfluoroalkyl)-4 H-chromeno, which was then converted to 3-R F -4-salicyloylisoxazoles by simple heating.
45 citations
TL;DR: A library of benzoindolizines has been synthesized using poly(ethylene glycol) (PEG) as soluble polymer support and in the presence of TPCD the reaction of 3 with 11 afforded indolizine 8, which was discovered firstly.
44 citations
TL;DR: In this paper, a proof of structures and a probable reaction pathway for 3-substituted chromones with hydroxylamine in alkaline medium were presented, and a possible reaction pathway was presented for 3-(diaminomethylene)chroman-2,4-dione.
43 citations
TL;DR: The chemistry and application of the title aldehyde and some simple derivatives thereof are reviewed in this paper, where the authors propose a simple derivative of the aldehydes, which they call simple aldeheeds.
42 citations
TL;DR: Another aspect concerning chromone chemistry leading to the one-pot synthesis of functionalized novel spirobenzofuranones has been described, and a plausible mechanistic rationale is proposed.
Abstract: Another aspect concerning chromone chemistry leading to the one-pot synthesis of functionalized novel spirobenzofuranones has been described. The synthesis involves reaction of the zwitterionic intermediates formed by the 1:1 interaction between isocyanides and acetylenecarboxylates with 3-cyanochromones, whereupon through an unexpected and unprecedented reaction of the chromone moiety the isolated benzofuranones are formed. The regioselectivity of the reaction was investigated by DFT calculations. The geometries of the intermediates, transition structures, and intermediate products, leading to the final products, were optimized using the B3LYP functional with the 6-31G(d) basis set. The structures of the products were elucidated by 1D and 2D NMR experiments. Full assignment of all (1)H and (13)C NMR chemical shifts has been achieved. A plausible mechanistic rationale is proposed.
35 citations