15802-62-7Relevant articles and documents
Synthesis, characterization, crystal structure, Hirshfeld surface analysis, antioxidant properties and DFT calculations of a novel pyrazole derivative: Ethyl 1-(2,4-dimethylphenyl)-3-methyl-5-phenyl-1H-pyrazole-4-carboxylate
Kumar, A. Dileep,Kumar, K. Ajay,Kumara, Karthik,Lokanath, N. K.,Naveen, S.,Warad, Ismail,Zarrouk, Abdelkader
, (2021)
An effective route for the direct synthesis of substituted pyrazole through 3+2 annulation method was described. (E)-ethyl 2-benzylidene-3-oxobutanoate was prepared from ethyl acetoacetate and benzaldehyde via Knoevenagel approach. The cyclocondensation r
Immobilized proton sponge on inorganic carriers: The synergic effect of the support on catalytic activity
Corma,Iborra,Rodriguez,Sanchez
, p. 208 - 215 (2002)
1,8-bis(dimethylaminonaphthalene) (DMAN), a proton sponge, was grafted onto amorphous and pure-silica MCM-41. The results show that DMAN supported on MCM-41 is an excellent base catalyst for the Knoevenagel condensation between benzaldehyde and different active methylene compounds as well as for the Claisen-Schmidt condensation of benzaldehyde and 2′-hydroxyacetophenone to chalcones and flavanones. The influence of the solvent and the polarity of the support on the activity of the catalysts was studied. It was found that the activity of the supported catalyst is directly related to the polarity of the inorganic support. Moreover, the support can also preactivate the reagents by interaction of the carbonyl groups with the weakly acidic silanol groups of the MCM-41. This preactivation step enables DMAN, anchored onto MCM-41, to abstract protons with a higher pKa than that of the DMAN. Finally, the study of the deactivation and recycling of the DMAN anchored onto MCM-41 catalysts showed that it is a stable material with respect to deactivation and leaching and results in comparable rates in successive batch reactions.
Binary caesium-lanthanum oxide supported on MCM-41: A new stable heterogeneous basic catalyst
Kloetstra,Van Laren,Van Bekkum
, p. 1211 - 1220 (1997)
Heterogeneous mesoporous stable basic catalysts have been prepared by wet or solid-state impregnation of MCM-41 with caesium acetate and lanthanum nitrate followed by thermal decomposition. 133Cs MAS NMR data of CsLa/MCM-41 show an increase in
Asymmetric Synthesis of Pentasubstituted Cyclohexanes through Diphenylprolinol Silyl Ether Mediated Domino Michael/Michael Reaction
Hayashi, Yujiro,Matoba, Hiroaki,Mori, Naoki,Odoh, Amaechi Shedrack,Umekubo, Nariyoshi,Aidanp??, Louise
supporting information, p. 6670 - 6673 (2021/12/31)
An asymmetric domino Michael/Michael reaction of α,β-unsaturated aldehydes 1 and α-acetyl-β-substituted-α,β-unsaturated esters 2 catalyzed by diphenylprolinol silyl ether was developed. This is a formal carbo [4+2] cycloaddition reaction affording penta-s
Highly Efficient Synthesis of Substituted 3,4-Dihydropyrimidin-2-(1H)-ones (DHPMs) Catalyzed by Hf(OTf)4: Mechanistic insights into reaction pathways under metal Lewis acid catalysis and solvent-free conditions
Kong, Rui,Han, Shuai-Bo,Wei, Jing-Ying,Peng, Xiao-Chong,Xie, Zhen-Biao,Gong, Shan-Shan,Sun, Qi
, (2019/02/01)
In our studies on the catalytic activity of Group IVB transition metal Lewis acids, Hf(OTf)4 was identified as a highly potent catalyst for”one-pot, three-component” Biginelli reaction. More importantly, it was found that solvent-free conditions, in contrast to solvent-based conditions, could dramatically promote the Hf(OTf)4-catalyzed formation of 3,4-dihydro-pyrimidin-2-(1H)-ones. To provide a mechanistic explanation, we closely examined the catalytic effects of Hf(OTf)4 on all three potential reaction pathways in both “sequential bimolecular condensations” and “one-pot, three-component” manners. The experimental results showed that the synergistic effects of solvent-free conditions and Hf(OTf)4 catalysis not only drastically accelerate Biginelli reaction by enhancing the imine route and activating the enamine route but also avoid the formation of Knoevenagel adduct, which may lead to an undesired byproduct. In addition, 1H-MMR tracing of the H-D exchange reaction of methyl acetoacetate in MeOH-d4 indicated that Hf(IV) cation may significantly accelerate ketone-enol tautomerization and activate the β-ketone moiety, thereby contributing to the overall reaction rate.
