- SILICA GEL FUNCTIONALIZED WITH AMINO GROUPS AS A NEW CATALYST FOR KNOEVENAGEL CONDENSATION UNDER HETEROGENEOUS CATALYSIS CONDITIONS
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Knoevenagel condensation has been carried out under heterogeneous catalysis conditions using amino groups immobilized on silica gel: the results show that the catalytic support is recoverable without regeneration, and that the matrix probably participates to the catalysis mechanism.
- Angeletti, Enrico,Canepa, Carlo,Martinetti, Giovanni,Venturello, Paolo
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- Lipase-catalyzed Knoevenagel condensation between α,β- unsaturated aldehydes and active methylene compounds
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A simple and efficient Knoevenagel condensation between α,β-unsaturated aldehydes and active methylene compounds is reported. Notably, this condensation can be catalyzed by PPL (lipase from porcine pancreas) with satisfied yields (49%-92%). Moreover, PPL induces moderate Z/E selectivity in the Knoevenagel condensation.
- Wang, Zhi,Wang, Chun-Yu,Wang, Hao-Ran,Zhang, Hong,Su, Ya-Lun,Ji, Teng-Fei,Wang, Lei
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- Enzyme catalytic promiscuity: The papain-catalyzed Knoevenagel reaction
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Papain as a sustainable and inexpensive biocatalyst was used for the first time to catalyze the Knoevenagel reactions in DMSO/water. A wide range of aromatic, hetero-aromatic and α,β-unsaturated aldehydes could react with less active methylene compounds acetylacetone and ethyl acetoacetate. The products were obtained in moderate to excellent yields with Z/E selectivities of up to 100:0. This case of biocatalytic promiscuity not only widens the application of papain to new chemical transformations, but also could be developed into a potentially valuable method for organic synthesis.
- Hu, Wen,Guan, Zhi,Deng, Xiang,He, Yan-Hong
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experimental part
p. 656 - 661
(2012/05/04)
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- Biocatalytic Knoevenagel reaction using alkaline protease from Bacillus licheniformis
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BLAP (alkaline protease from Bacillus licheniformis) was used as a biocatalyst in the Knoevenagel condensations of aromatic, hetero-aromatic and α;β-unsaturated aldehydes with less reactive acetylacetone or ethyl acetoacetate. The reactions were performed in organic solvent in the presence of water. The functionalized trisubstituted alkenes and α,β,γ, δ-unsaturated carbonyl compounds could be obtained in moderate to good yields with E/Z selectivities up to >99:1. This biocatalytic reaction provided an alternative pathway for Knoevenagel condensation, which also demonstrates a novel case of unnatural activity of existing enzymes.
- Xie, Bang-Hua,Guan, Zhi,He, Yan-Hong
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experimental part
p. 238 - 244
(2012/06/30)
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- Natural α-amino acid l-lysine-catalyzed knoevenagel condensations of α,β-unsaturated aldehydes and 1,3-dicarbonyl compounds
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Knoevenagel condensations of α,β-unsaturated aldehydes and 1,3-dicarbonyl compounds were catalyzed by primary natural amino acid L-lysine. The reactions were carried out at room temperature in dimethylsulfoxide. It provides a facile entry to a wide variety of α,β,γ,δ- unsaturated dicarbonyl compounds. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications to view the free supplemental file.
- He, Yan-Hong,Hu, Ying,Guan, Zhi
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experimental part
p. 1617 - 1628
(2011/06/21)
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- A simple method for the preparation of functionalized trisubstituted alkenes and α,β,γ,δ-unsaturated carbonyl compounds by using natural amino acid l-tryptophan
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Primary natural amino acid l-tryptophan was used, for the first time, as a catalyst in Knoevenagel condensations of aliphatic, aromatic, hetero-aromatic and α,β-unsaturated aldehydes with less reactive acetylacetone and ethyl acetoacetate. The reactions were carried out at room temperature and gave good yields. It is a convenient entry for preparation of functionalized trisubstituted alkenes and α,β,γ,δ-unsaturated carbonyl compounds.
- Hu, Ying,He, Yan-Hong,Guan, Zhi
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scheme or table
p. 656 - 659
(2010/11/05)
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- Aldol condensation of β-diketones and β -ketoesters with aldehydes catalyzed by samarium (III) iodide
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Catalyzed by SmI3 β-diketones and β-ketoesters condense with aldehydes to give benzylidene substituted β -diketones and β -ketoesters at room temperatures in fair yields. Copyright
- Bao, Weiliang,Zhang, Yongmin,Wang, Jingang
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p. 3025 - 3028
(2007/10/03)
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- Amino Groups Immobilized on Silica Gel: an Efficient and Reusable Heterogeneous Catalyst for the Knoevenagel Condensation
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Silica gel functionalized with amino groups is a useful insoluble catalyst for the Khoevenagel condensation: the reaction can be carried out under continuous-flow conditions and good yields are obtained when aromatic aldehydes, cyclohexanone, and acetophenone react with ethyl acetoacetate, ethyl cyanoacetate, and malononitrile.Lower yields are obtained in the case of ethyl benzoylacetate and acetylacetone; this fact and the easy dehydration of the aldol intermediate strongly suggest the participation of the residual free silanol groups of the matrix in the catalysis mechanism.
- Angeletti, Enrico,Canepa, Carlo,Martinetti, Giovanni,Venturello, Paolo
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p. 105 - 107
(2007/10/02)
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