- Magnetically recoverable silica catalysed solvent-free domino Knoevenagel-hetero-Diels-Alder reaction to access divergent chromenones
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A three-component domino Knoevenagel-hetero-Diels-Alder (DKHDA) reaction between 1,3-dicarbonyl, aldehydes/ketones, and alkenes/alkynes leading to the divergent synthesis of chromenones, dihydrochromenones, and spirocyclic chromenones is reported. The reaction was carried out under solvent-free conditions using a magnetically separable silica (Fe3O4?SiO2) catalyst. While two component DKHDA reactions are known, this is the first example of a three component DKHDA reaction involving 1,3-dicarbonyl, ketones, and alkynes producing spirocyclic pyranone derivatives. Twenty-six different highly substituted chromenones were synthesized using this methodology. A wide substrate scope due to the multicomponent nature of the reaction, high atom economy, the use of inexpensive and non-Toxic recyclable silica as the catalyst, and solvent free reaction conditions make it an advantageous process. The catalyst was characterized using different analytical techniques such as XRD, IR, HRTEM, VSM, and TGA. Based on the earlier reports a mechanism has also been proposed.
- Das, Pankaj,Gogoi, Chinu,Hussain, Farhaz Liaquat,Pahari, Pallab,Suri, Mrinaly
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supporting information
p. 2058 - 2062
(2020/03/27)
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- Alkaline earth metal catalyzed cascade, one-pot, solvent-free, and scalable synthesis of pyranocoumarins and benzo[b]pyrans
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Ca(OTf)2 catalyzed, cascade, one-pot, conjugate addition and annulation of various nucleophiles to the α,β-unsaturated carbonyl compounds for the synthesis of biologically potent pyranocoumarins and benzo[b]pyrans has been illustrated. This one
- Yaragorla, Srinivasarao,Saini, Pyare Lal,Singh, Garima
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supporting information
p. 1649 - 1653
(2015/03/14)
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- InBr3-catalyzed annulations of cyclic 1,3-diketones with aryl propargyl alcohols: a novel synthesis of 2,4-diaryldihydropyrans
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The cyclic 1,3-dicarbonyl compounds undergo smooth cyclization with aryl propargyl alcohols in the presence of 10 mol % indium tribromide in refluxing dichloroethane to produce 2,4-diarylpyran derivatives in good yields with high selectivity.
- Yadav,Subba Reddy,Raghavendra Rao,Narender
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experimental part
p. 3963 - 3965
(2009/10/04)
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- Preparation of 5-oxo-5,6,7,8-tetrahydro-4H-benzo-[b]-pyran derivatives in ionic liquids
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A novel preparation of 5-oxo-5,6,7,8-tetrahydro-4H-benzo-[b]-pyran derivatives promoted by lnCI3·4H2O/TMSCI in ionic liquid ([bmin]BF4) is described. The preparative procedure presented in this paper is operationally simple and environmentally friendly. The reaction media and catalyst used can be recovered and reused for at least four times without loss in the catalytic activity. This method is promising for a mass-production process.
- Li, Qiang,Hu, Xueyuan,Li, Wei,Yang, Fei,Yang, Xiaoian,Sun, Lili,Zhou, Liping,Qi, Junsheng,Yu, Yu
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experimental part
p. 331 - 333
(2009/06/18)
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- HETEROCYCLIZATION OF TRIKETONES OF THE 2-(3-OXOPROPYL)CYCLOHEXANE-1,3-DIONE SERIES
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Triketones of the 2-(3-oxopropyl)cyclohexane-1,3-dione series have been shown for the first time to react with boron trifluoride etherate to give the novel 5-oxo-5,6,7,8-tetrahydrochromylium fluoroborates, which in turn react with ammonia to give 5-oxo-5,
- Kharchenko, V. G.,Markova, L. I.,Kazarinova, T. D.,Yudovich, L. M.
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p. 758 - 761
(2007/10/02)
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- SYNTHESIS AND CATALYTIC HYDROGENATION OF 5-OXOTETRAHYDRO-4H-CHROMENES
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A systematic investigation was undertaken into the intramolecular heterocyclization of 2-(3-oxopropyl)-1,3-cyclohexanediones by the action of chemical reagents.It was established that the direction of the heterocyclization reactions depends on the structure of the initial compound, the temperature, and the cyclizing agent.It was shown that the investigated compounds can undergo cyclization with the formation of 5-oxo-5,6,7,8-tetrahydro-4H-chromenes, which are capable of being converted into hexahydrochromans and 5-oxo-1-oxabicyclodec-9-enes under the conditions of catalytic hydrogenation.
- Kharchenko, V. G.,Markova, L. I.,Smirnova, N. S.,Korshunova, K. M.,Rybina, G. I.
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p. 1926 - 1930
(2007/10/02)
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