- An efficient recyclable polymer-supported bis-quaternary onium phase-transfer catalyst for the synthesis of dihalocyclopropyl derivatives at low alkaline concentration-comparative kinetic aspects
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In this work, a new polystyrene-bound bis-onium phase-transfer catalyst was synthesized, and their catalytic activities were investigated in the synthesis of dichlorocyclopropyl derivatives of olefins. The new polymer-anchored multi-site phase-transfer catalyst showed significant high catalytic activity as compared to single-site phase-transfer catalyst. The comparative kinetic investigation reveals that the dichlorocyclopropanation of 1-methyl-4-vinyl benzene is faster than styrene in the presence of the new catalyst. This catalyst can be used several times with consistent catalytic activity. Experimental observations support an interfacial-type mechanism. Furthermore, its catalytic utility was examined in alkylation reactions.
- Vivekanand,Wang, Maw-Ling
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- Acid-catalyzed cleavage of C-C bonds enables atropaldehyde acetals as masked C2 electrophiles for organic synthesis
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Acid-catalyzed tandem reactions of atropaldehyde acetals were established for the synthesis of three important molecules, 2,2-disubstituted indolin-3-ones, naphthofurans and stilbenes. The synthesis was realized using novel reaction cascades, which involved the same two initial steps: (i) SN2′ substitution, in which the atropaldehyde acted as an electrophile; and (ii) oxidative cleavage of the carbon-carbon bond of the generated phenylacetaldehyde-type products. Compared with literature methods, the present protocol not only avoided the use of expensive noble metal catalysts, but also enabled a simple operation.
- Chen, Shaomin,Gu, Yanlong,Li, Minghao
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p. 10431 - 10434
(2021/10/12)
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- Spectroscopic analysis of the products of the cycloaddition reaction of 1-Aryl-2-chlorocyclopropenes and cyclopentadiene
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The treatment of a series of 1-aryl-2,2-dihalocyclopropanes with t-BuOK at -10 °C produces the corresponding 1-aryl-2-halocyclopropenes, which react with cyclopentadiene to produce fairly good yield of [4+2]-cycloaddition products with more than 90% of the endo-isomer. The higher yield obtained from hexane medium then from methanol and ionic liquid demonstrates that the reaction is a nonpolar process. The treatment of a series of 1-aryl-2,2- dihalocyclopropanes with t-BuOK at -10 °C produces the corresponding 1-aryl-2-halocyclopropenes, which react with cyclopentadiene to produce fairly good yield of [4+2]-cycloaddition products with more than 90% of the endo-isomer. The higher yield obtained from hexane medium then from methanol and ionic liquid demonstrates that the reaction is a nonpolar process. Copyright
- Ding, Mei-Fang,Lee, Chuan-Chen,Lin, Lian-Chun,Lin, Shaw-Tao
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p. 285 - 289
(2014/05/06)
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- PEG400-enhanced synthesis of gem-dichloroaziridines and gem-dichlorocyclopropanes via in situ generated dichlorocarbene
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PEG400 is employed as an efficient phase transfer catalyst for the cycloaddition reaction of imines with dichlorocarbene, which is generated in situ from chloroform and sodium hydroxide, to give gem-dichloroaziridines in moderate to excellent yields at ambient temperature. This protocol is also extended to the synthesis of cyclopropanes from a variety of alkenes. In this study, PEG400 behaves as a phase transfer reagent thanks to its ability to coordinate with alkali metal cations. Notably, the one-pot synthesis of gem-dichloroaziridines from benzaldehyde and aromatic amines has also been successfully performed. The in situ generated acid, derived from CO2 and H2O, can also be effectively applied to promote the amide synthesis via the gem-dichloroaziridine pathway. The application of the gem-dichlorocyclopropane as a platform chemical is also briefly demonstrated, to afford the 2-phenylacrylaldehyde derivative via a ring-opening reaction. The Royal Society of Chemistry 2013.
- Song, Qing-Wen,Yu, Bing,Liu, An-Hua,He, Ying,Yang, Zhen-Zhen,Diao, Zhen-Feng,Song, Qing-Chuan,Li, Xue-Dong,He, Liang-Nian
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p. 19009 - 19014
(2013/10/22)
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- Ionic liquids accelerating cycloaddition between 1-aryl-2-halocyclopropenes and furan
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Treatment of a series of 1-aryl-2,2-dihalocyclopropanes with t-BuOK at-10 °C gave the corresponding 1-aryl-2-halocyclopropenes, which react with furan in a RTIL to give a fair good yield of the [4+2]-cycloadducts with more than 90% of the exo-isomer. The imidazolium type ionic liquids are able to accelerate this cycloaddition process with high steric selectivity. Neither pyrrole nor thiophene undergoes the cycloaddition with cyclopropene to form the [4+2]-cycloadduct. 1-Aryl-3,3-difluoro-2-halocyclopropenes are inert towards furan even at a temperature higher than 100 °C.
- Ding, May-Fan,Lin, Shaw-Tao,Chang, Woan-Ju
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experimental part
p. 240 - 247
(2010/09/16)
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- Synthesis and utility of α,α'-bis (triethyl ammonium methylene chloride) β-phenyl ethene in hydroxide ion initiated reactions - A new multi-site phase transfer catalyst
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A three step synthesis of novel 'multi-site' water soluble phase transfer catalyst viz, α,α'-bis(triethyl ammonium methylene chloride) β-phenyl ethene and its utility in various organic biphase reactions are described.
- Balakrishnan,Jayachandran
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p. 3821 - 3830
(2007/10/03)
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