- Scope of chemical fixation of carbon dioxide catalyzed by a bifunctional monomeric tungstate
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The tungsten-oxo moiety in a simple monomeric tungstate, TBA 2[WO4] (I, TBA = tetra-n-butylammonium), showed bifunctional activation of both CO2 and 1,2-phenylenediamine (1a). It was confirmed by 1H, 13C, and 183W NMR spectroscopies that adducts I-1a and I-(CO2)n (n = 1 and 2) were formed by the reactions of I with 1a and CO2, respectively. These adducts played important roles in formation of the corresponding carbamic acid intermediates. The present bifunctionality could be applied to chemical fixation of CO2 even at atmospheric pressure with various kinds of structurally diverse aryl diamines, primary monoamines, propargylic alcohols, and propargylic amines into cyclic urea derivatives, 1,3-disubstituted urea derivatives, cyclic carbonates, and cyclic carbamates, respectively.
- Kamata, Keigo,Kimura, Toshihiro,Sunaba, Hanako,Mizuno, Noritaka
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p. 160 - 166
(2014/03/21)
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- DBU-based ionic-liquid-catalyzed carbonylation of o-phenylenediamines with CO2 to 2-benzimidazolones under solvent-free conditions
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Herein, a new route was presented to synthesize 2-benzimidazolones via the carbonylation of o-phenylenediamines with CO2 catalyzed by 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-based ionic liquids under solvent-free conditions. DBU acetate ([DBUH][OAc]) displayed high efficiency for catalyzing the reactions of CO2 with o-phenylenediamines, and a series of benzimidazolones were obtained in high yields. It was demonstrated that [DBUH][OAc] could serve as a bifunctional catalyst for these reactions with the cation activating CO2 and the anion activating o-phenylenediamines. This protocol provides an effective and environmentally friendly alternative route for production of benzimidazolones, and extends the chemical utilization of CO2 in organic synthesis as well.
- Yu, Bo,Zhang, Hongye,Zhao, Yanfei,Chen, Sha,Xu, Jilei,Hao, Leiduan,Liu, Zhimin
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p. 2076 - 2082
(2013/09/24)
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- A bifunctional tungstate catalyst for chemical fixation of CO2 at atmospheric pressure
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No pressure: A simple monomeric tungstate, [WO4]2-, serves as a highly efficient homogeneous catalyst for various transformations of CO2 at atmospheric pressure. The tungsten-oxo moiety activates CO2 and the substrate simultaneously. The catalyst system is high yielding and applicable to a wide range of substrates such as amines (see scheme), 2-aminobenzonitriles, and propargylic alcohols. Copyright
- Kimura, Toshihiro,Kamata, Keigo,Mizuno, Noritaka
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supporting information; experimental part
p. 6700 - 6703
(2012/08/28)
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- HZSM-5 catalysed regiospecific benzoylation of activated aromatic compounds
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HZSM-5 has been shown to display a remarkable reaction selectivity in the liquid-phase benzoylation of activated arenes to benzophenones in high yields.
- Paul, Vincent,Sudalai,Daniel, Thomas,Srinivasan
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p. 2601 - 2602
(2007/10/02)
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