- Bifunctional acid-base ionic liquid organocatalysts with a controlled distance between acid and base sites
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Bifunctional acid-base ionic liquid organocatalysts with different distances between the two sites have been synthesised, and their activity for the Knoevenagel condensation has been tested. As has been found to be the case with enzymes, the distance betw
- Boronat, Mercedes,Climent, Maria J.,Corma, Avelino,Iborra, Sara,Monton, Raquel,Sabater, Maria J.
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- A simple modification creates a great difference: New solid-base catalyst using methylated N-substituted SBA-15
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A simple modification, methylation of the nitrogen-substituted mesoporous silica SBA-15, enhances the basicity of a solid-base catalyst. The methyl group donates an electron to the nitrogen atom in the silica framework. This catalyst accelerates Knoevenag
- Sugino, Kotaro,Oya, Nobuhiro,Yoshie, Naoko,Ogura, Masaru
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- Synthesis, characterization, and catalytic activity of ionic liquids based on biosources
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New room-temperature ionic liquids were synthesized from natural and easily available feedstocks (choline hydroxide and amino acids) following an economical and green route in which the only by-product was water. They were successfully applied as catalyst
- Moriel,García-Suárez,Martínez,García,Montes-Morán,Calvino-Casilda,Ba?ares
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- Gem-diamines as highly active organocatalysts for carbon-carbon bond formation
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Diamines with neighbour nitrogen atoms have been used as base catalysts in the Knoevenagel condensation reaction between benzaldehyde and ethyl cyanoacetoacetate. The catalytic results show that a good basic catalyst requires a combination of two factors: high proton affinity and the ability to return the proton to the oxoanion intermediate. Computational chemistry calculations show this by characterizing the reactants, products, and transition states and by calculating the activation energies of the different reaction steps. A diamine, di(3-methylpiperidine)methane (B), has been found with a higher catalytic activity than DMAN despite its lower proton affinity, demonstrating that not only the proton affinity, but also the steric ability to abstract the protons, are important in explaining the catalytic results.
- Climent, Maria J.,Corma, Avelino,Dominguez, Irene,Iborra, Sara,Sabater, Maria J.,Sastre, German
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- Mg/Al-CO3 layered double hydroxide nanorings
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Mg/Al-CO3 Layered Double Hydroxide (LDH) nanorings with a 750 nm exterior diameter and 250 nm interior diameter were synthesized in an organic/water solvent system via a urea hydrolysis method, using Mg 10(OH)18Cl2/s
- Yang, Miaosen,Liu, Junfeng,Chang, Zheng,Williams, Gareth R.,O'Hare, Dermot,Zheng, Xuehan,Sun, Xiaoming,Duan, Xue
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- Flow-synthesis of mesoporous silicas and their use in the preparation of magnetic catalysts for Knoevenagel condensation reactions
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Mesoporous silica MCM-41 was successfully prepared by flow synthesis in a microreactor at shorter reaction times (i.e., minutes versus day) at high yield (i.e., 60% calcined sample) to give particles of more uniform size and shape compared to MCM-41 prepa
- Chen, Xinqing,Arruebo, Manuel,Yeung, King Lun
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- Alkaline carbons as effective catalysts for the microwave-assisted synthesis of N-substituted-gamma-lactams
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The selective construction of new CC or Cheteroatom bonds is frequently the fundamental step in the synthesis of derivatives with high added value. In particular, molecules with CN bonds are of great interest due to their widespread use and intrinsic impo
- Calvino-Casilda,Martín-Aranda,López-Peinado
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Read Online
- Active Base Hybrid Organosilica Materials based on Pyrrolidine Builder Units for Fine Chemicals Production
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The catalytic activity of “pyrrolidine type” fragments included or anchored in the mesoporous silica supports or polymeric frameworks have been fully reported for enantioselective transformation. Nevertheless, low attention was focused on their catalytic abilities to perform base-catalyzed reaction. Accordingly, hybrid materials including pyrrolidine fragments in the mesoporous silica supports were prepared following different synthesis methods, such as micellar and fluoride sol-gel routes in absence of structural directing agents. Their great catalytic performance was explored for various base-catalyzed reactions to the formation of C?C bond through Knoevenagel, Claisen-Schmidt and Henry condensations under microwave irradiation. The benefits of microwave irradiation combined with suitable catalytic properties of pyrrolidine hybrid materials with strong base sites and high accessibility to active centers, allowed carrying out successfully base-catalyzed condensation reactions for the production of fine chemicals. Moreover, the hybrid catalyst exhibited high selectivity and good stability over different catalytic cycles contributing to environmental sustainability.
- Llopis, Sebastián,Velty, Alexandra,Díaz, Urbano
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p. 5012 - 5024
(2021/10/19)
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- A facile, efficient and solvent-free titanium (IV) ethoxide catalysed knoevenagel condensation of aldehydes and active methylenes
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Titanium ethoxide has been employed as a novel and efficient reagent for the Knoevenagel condensation of aldehydes with active methylenes such as diethyl malonate and ethyl cyanoacetate under solvent free conditions to afford substituted olefins in high to excellent yields. The reaction is suitable for a variety of aromatic, aliphatic and heteroaromatic aldehydes with various active methylenes. Parallel to this, microwave irradiation has been utilized to achieve improved reaction rates and enhanced yields. Herein, we illustrated a convenient method for the preparation of α,β-unsaturated compounds using both conventional and microwave irradiation methods. An efficient and solvent free Knoevenagel condensation between aldehydes and active methylenes was developed using titanium ethoxide. The procedure proved to be successful with a wide range of substrates such as aromatic, aliphatic and heterocyclic aldehydes and various active methylenes to afford substituted olefins. The reaction was also carried out under microwave irradiation to accomplish the corresponding olefins with improved reaction rates, yields and cleaner reaction profiles.We have developed an efficient and novel methodology for the synthesis of olefinic compounds by Knoevenagel condensation under solvent-free conditions using titanium ethoxide, for the first time, as a reagent as well as a solvent. This method is appropriate for the synthesis of a variety of aromatic aldehydes containing various electron-donating and withdrawing groups, aliphatic and heteroaromatic aldehydes. The significant advantages offered by this methodology could be applied to various active methylenes in order to offer the corresponding Knoevenagel products. Thus, we believe that this method delivers high conversions, cleaner reaction profiles under solvent-free reaction conditions and shorter reaction times, all of which make it a very useful and attractive approach for the preparation of a wide range of substituted olefins.
- Ramaiah, Manjunatha M.,Shivananju, Nanjunda Swamy,Shubha, Priya Babu
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p. 107 - 115
(2020/02/04)
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- Johnson-Corey-Chaykovsky fluorocyclopropanation of double activated alkenes: Scope and limitations
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Johnson-Corey-Chaykovsky fluorocyclopropanation of double activated alkenes utilizing S-monofluoromethyl-S-phenyl-2,3,4,5-tetramethylphenylsulfonium tetrafluoroborate is an efficient approach to obtain a range of monofluorocyclopropane derivatives. So far, fluoromethylsulfonium salts have displayed the broadest scope for direct fluoromethylene transfer. In contrast to more commonly used fluorohalomethanes or freon derivatives, diarylfluoromethylsulfonium salts are bench stable, easy-to use reagents useful for the direct transfer of a fluoromethylene group to alkenes giving access to the challenging products-fluorocyclopropane derivatives. Interplay between the reactivity of the starting materials and stability of the fluorocyclopropanes formed determines the outcome of the process.
- Kazia, Armands,Melngaile, Renate,Mishnev, Anatoly,Veliks, Janis
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supporting information
p. 1384 - 1388
(2020/03/03)
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- Highly active hybrid mesoporous silica-supported base organocatalysts for C–C bond formation
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New base hybrid catalysts, based on silyl-derivatives of molecules carrying amino, diamino, pyrrolidine, pyrazolium and imidazolium functionalities have been successfully achieved through post synthetic grafting onto M41S-type support. Different character
- Erigoni,Hernández-Soto,Rey,Segarra,Díaz
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p. 227 - 236
(2019/10/28)
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- Highly Active Bisamino Functionalized Zr(IV)-UiO-67 Metal-Organic Framework for Cascade Catalysis
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This work reports the synthesis and characterization of Zr(IV)-based UiO-67-(NH2)2 (called 1) metal-organic framework. Activated 1 (named 1') was shown to be an efficient tandem catalyst in the conversion of benzaldehydedimethyl acet
- Das, Aniruddha,Anbu, Nagaraj,Mostakim,Dhakshinamoorthy, Amarajothi,Biswas, Shyam
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supporting information
p. 2830 - 2834
(2020/07/04)
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- Green and selective toluene oxidation–Knoevenagel-condensation domino reaction over Ce- and Bi-based CeBi mixed oxide mixtures
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Both Bi- and Ce-based CeBi mixed oxides were prepared by a modified sol-gel process from their precursor salts. The mixed as well as the parent oxides were characterized by X-ray diffractometry, Raman, XPS, UV–DRS and X-ray photoelectron spectroscopies, ICP–OES method, scanning and transmission electron microscopies as well as BET surface area, CO2- and NH3-temperature-programmed desorption measurements. After characterizing the morphology, the acid-base properties, the oxidation states of the cationic components and the porosity of these structures, their catalytic activities were probed in the Koevenagel condensation of benzaldehyde and diethyl malonate and the toluene oxidation to benzaldehyde reactions. Based on the catalytic activities of the oxides in the individual reactions, a catalyst mixture from the Bi- and Ce-based mixed oxides was used successfully in the toluene to benzaldehyde oxidation and benzaldehyde to benzylidene malonate Knoevenagel condensation domino reaction under environmentally benign conditions.
- Varga, Gábor,Kukovecz, ákos,Kónya, Zoltán,Sipos, Pál,Pálinkó, István
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p. 308 - 315
(2019/11/29)
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- Solvent-Free FeCl3-Assisted Electrophilic Fluorine-Catalyzed Knoevenagel Condensation to Yield α,β-Unsaturated Dicarbonyl Compounds and Coumarins
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A highly environmentally friendly procedure was developed for the Knoevenagel condensation of aromatic aldehydes with diethyl malonate in the presence of FeCl3 and N-fluorobenzenesulfonimide as a source of electrophilic fluorine under solvent-free conditions. The scope of the reaction was explored using commercially available substrates. The reaction with substituted salicylaldehydes afforded the corresponding coumarin derivatives which attract interest due to their potential medicinal importance.
- Yang, Lu,Zhu, Jiang,Xie, Fukai,Peng, Xiaoshi,Lin, Bin,Liu, Yongxiang,Cheng, Maosheng
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p. 1053 - 1060
(2019/09/06)
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- Metal free biomimetic deaminative direct C-C coupling of unprotected primary amines with active methylene compounds
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An unprecedented direct C-C coupling reaction of unprotected primary amines with active methylene compounds is reported. The reaction involves a biomimetic deamination of amines which was achieved under conditions free of metallic reagents and strong oxidizing agents. A wide range of primary amines was reacted with different active methylene compounds to provide structurally diverse trisubstituted alkenes and dihydropyridines. A kinetic study revealed an activation barrier of 10.1 kcal mol-1 for the conversion of a key intermediate of the reaction.
- Ghosh, Santanu,Jana, Chandan K.
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supporting information
p. 10153 - 10157
(2019/12/26)
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- Organic photocatalysis for the radical couplings of boronic acid derivatives in batch and flow
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We report an acridium-based organic photocatalyst as an efficient replacement for iridium-based photocatalysts to oxidise boronic acid derivatives by a single electron process. Furthermore, we applied the developed catalytic system to the synthesis of four active pharmaceutical ingredients (APIs). A straightforward scale up approach using continuous flow photoreactors is also reported affording gram an hour throughput.
- Lima, Fabio,Grunenberg, Lars,Rahman, Husaini B. A.,Labes, Ricardo,Sedelmeier, Joerg,Ley, Steven V.
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supporting information
p. 5606 - 5609
(2018/06/04)
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- Development of the First Two-Pore Domain Potassium Channel TWIK-Related K+ Channel 1-Selective Agonist Possessing in Vivo Antinociceptive Activity
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The TWIK-related K+ channel, TREK-1, has recently emerged as an attractive therapeutic target for the development of a novel class of analgesic drugs, suggesting that activation of TREK-1 could result in pain inhibition. Here, we report the synthesis of a series of substituted acrylic acids (1-54) based on our previous work with caffeate esters. The analogues were evaluated for their ability to modulate TREK-1 channel by electrophysiology and for their in vivo antinociceptive activity (acetic acid-induced writhing and hot plate assays), leading to the identification of a series of novel molecules able to activate TREK-1 and displaying potent antinociceptive activity in vivo. Furyl analogue 36 is the most promising of the series.
- Vivier, Delphine,Soussia, Ismail Ben,Rodrigues, Nuno,Lolignier, Stéphane,Devilliers, Ma?ly,Chatelain, Franck C.,Prival, Laetitia,Chapuy, Eric,Bourdier, Geoffrey,Bennis, Khalil,Lesage, Florian,Eschalier, Alain,Busserolles, Jér?me,Ducki, Sylvie
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p. 1076 - 1088
(2017/02/19)
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- H3PW12O40/mpg-C3N4 as an efficient and reusable bifunctional catalyst in one-pot oxidation-Knoevenagel condensation tandem reaction
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A single-site bifunctional catalyst for the oxidation-Knoevenagel condensation tandem reaction was prepared by the immobilization of phosphotungstic acid (HPW) on mesoporous graphitic carbon nitride (mpg-C3N4) via electrostatic interaction (HPW/mpg-C3N4). The results of Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), solid-state 31P nuclear magnetic resonance (solid-state 31P NMR), zeta potentials, X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) demonstrated that HPW was successfully immobilized on the protonated mpg-C3N4 by electrostatic interaction. The acid amounts of the catalysts were determined by NH3 temperature programmed desorption (NH3-TPD). The textural properties and morphology of HPW/mpg-C3N4 were characterized by N2 adsorption-desorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). 30% HPW/mpg-C3N4 shows the best catalytic performance in the tandem reaction with 98.4% benzyl alcohol conversion and 96.2% selectivity to benzylidene malononitrile. The excellent catalytic performance of 30% HPW/mpg-C3N4 in the tandem reaction is due to the good catalytic performance of HPW in the oxidation and Knoevenagel condensation, respectively. Furthermore, protonated mpg-C3N4 not only acts as a support to facilitate good dispersion of HPW but also promotes the Knoevenagel condensation reaction effectively. Moreover, the HPW/mpg-C3N4 catalyst could be recycled easily without significant loss of catalytic activity.
- Wang, Hefang,Wang, Cunyue,Yang, Yongfang,Zhao, Meng,Wang, Yanji
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p. 405 - 417
(2017/08/14)
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- A novel bifunctional Pd-ZIF-8/rGO catalyst with spatially separated active sites for the tandem Knoevenagel condensation-reduction reaction
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A novel bifunctional catalyst with spatially separated active sites was prepared by the immobilization of Pd nanoparticles (NPs) via covalent interaction and coordination of a zeolitic imidazolate framework (ZIF-8) on the surface of graphene oxide (GO), respectively, which was used as an efficient catalyst for the Knoevenagel condensation-reduction tandem reaction. The results of Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Raman spectroscopy, UV-vis spectroscopy, X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) demonstrated that Pd and ZIF-8 were successfully immobilized on the surface of GO, and the GO was reduced to reduced graphene oxide (rGO) using NaBH4 as the reductant in the preparation of Pd-ZIF-8/rGO. The textural properties and morphology of Pd-ZIF-8/rGO were characterized by N2 adsorption-desorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Pd-ZIF-8/rGO shows excellent catalytic performance in the tandem reaction with 100% benzaldehyde conversion and 98.3% selectivity to benzylmalononitrile. The excellent catalytic performance of Pd-ZIF-8/rGO in the tandem reaction is due to the high catalytic activities of spatially separated Pd NPs and ZIF-8 active sites and concentrated reactants on the surface of Pd-ZIF-8/rGO due to the π-π interaction between rGO and the reactants. The anchoring and stabilization effects of oxygenated groups of GO inhibit the aggregation and leakage of active sites, leading to good catalytic recyclability with almost unchanged catalytic activity for more than eight cycles in the tandem reaction.
- Wang, Hefang,Wang, Yansu,Jia, Aizhong,Wang, Cunyue,Wu, Luming,Yang, Yongfang,Wang, Yanji
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p. 5572 - 5584
(2017/12/07)
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- Polyoxometalate-Intercalated Layered Double Hydroxides as Efficient and Recyclable Bifunctional Catalysts for Cascade Reactions
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The polyoxometalate (POM) intercalated layered double hydroxides (LDHs) have been widely used as heterogeneous catalysts. However, the application of POM-LDHs as bifunctional catalysts for cascade reaction has seldom been studied compared to the noble-metal-based catalysts. Herein, a series of POM-LDHs catalysts of Tris-LDH-X4(PW9)2 (X=Mn, Fe, Co, Ni, Cu, and Zn; Tris=Tris(hydroxymethtyl)aminomethane) have been prepared. The efficacy of Tris-LDH-Zn4(PW9)2 as efficient bifunctional catalyst has been demonstrated for cascade reactions involving oxidation of benzyl alcohol to benzaldehyde followed by Knoevenagel condensation with ethyl cyanoacetate to produce benzylidene ethyl cyanoacetate. The combination of POM's redox/acidic sites and LDHs's basic sites led to a composite catalyst with excellent activity (99 %) and selectivity (≥99 %) under mild and soluble-base-free conditions. This work offers a new design strategy for the fabrication of efficient bifunctional catalysts for the promotion of one-pot cascade reactions.
- Liu, Kai,Xu, Yanqi,Yao, Zhixiao,Miras, Haralampos N.,Song, Yu-Fei
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p. 929 - 937
(2016/03/15)
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- A bionic aqueous heterogeneous catalytic system catalytic aromatic aldehydes with malonic acid diester method of the condensation reaction between
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The invention discloses a method for catalyzing the condensation reaction between aromatic aldehyde and malonic diester with a bionic water-containing heterogeneous catalytic system. According to the method, aromatic aldehyde and malonic diester are adopt
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Paragraph 0068; 0073; 0075-0077; 0079-0082
(2018/01/19)
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- Bi-functional NH2-MIL-101(Fe) for one-pot tandem photo-oxidation/Knoevenagel condensation between aromatic alcohols and active methylene compounds
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Tandem reactions, which enable multistep reactions in one pot, offer enormous economical advantages. For the first time, this manuscript reported that NH2-MIL-101(Fe), an earth abundant Fe-containing MOF material, can catalyze efficiently the one-pot reaction between aromatic alcohols and active methylene compounds via a tandem photo-oxidation/Knoevenagel condensation under visible light and at room temperature. NH2-MIL-101(Fe) acts as a photocatalyst for the oxidation of aromatic alcohols to aldehydes as well as a base catalyst for Knoevenagel condensation between the as-formed aldehydes and the active methylene compounds. The comparison of the reactions over NH2-MIL-101(Fe) and another two MOFs (NH2-UiO-66(Zr) and NH2-MIL-125(Ti)) reveals that the strength of the basic sites in the MOFs influences significantly the efficiency of the tandem reaction. This study highlights the great potential of MOFs as multifunctional photocatalysts for one-pot tandem reactions.
- Wang, Dengke,Li, Zhaohui
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p. 1623 - 1628
(2015/04/27)
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- Further insights into the SAR of α-substituted cyclopropylamine derivatives as inhibitors of histone demethylase KDM1A
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Epigenetics alterations including histone methylation and acetylation, and DNA methylation, are thought to play important roles in the onset and progression of cancer in numerous tumour cell lines. Lysinespecific demethylase 1 (LSD1 or KDM1A) is highly ex
- Pieroni, Marco,Annunziato, Giannamaria,Azzali, Elisa,Dessanti, Paola,Mercurio, Ciro,Meroni, Giuseppe,Trifiró, Paolo,Vianello, Paola,Villa, Manuela,Beato, Claudia,Varasi, Mario,Costantino, Gabriele
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p. 377 - 386
(2015/03/05)
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- Synthesis and bifunctional catalysis of metal nanoparticle-loaded periodic mesoporous organosilicas modified with amino groups
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The present article describes the development of a periodic mesoporous organosilica (PMO)-based bifunctional catalyst that includes both oxidative and base catalytic activities. Periodic mesoporous ethylenesilica (PME) was selected as a catalyst support and modified with ethylenediamine through epoxidation of bridging ethylene moieties and the following nucleophilic addition in order to construct base sites. FT-IR measurements for the resulting material, PME-ED, reveal the successful introduction of amino groups into the bridging ethylene moieties. PME-ED can promote Knoevenagel condensation between benzaldehyde and various active methylene compounds as a solid base catalyst. The scope of applicable active methylene compounds in this catalytic system shows the base strength of PME-ED, in which a proton can be abstracted from diethyl malonate (pKa: 16.4) but not from benzyl cyanide (pKa: 21.9). Moreover, the generation of bifunctional catalytic properties to promote a one-pot tandem reaction consisting of alcohol oxidation and Knoevenagel condensation is realised by loading of Au nanoparticles within PME-ED. This catalyst design methodology can be also extended to developing another bifunctional catalyst that is composed of Pd nanoparticles and PME modified with N,N-dimethylethylenediamine in order to promote a Tsuji-Trost reaction.
- Horiuchi, Yu,Do Van, Dang,Yonezawa, Yusuke,Saito, Masakazu,Dohshi, Satoru,Kim, Tae-Ho,Matsuoka, Masaya
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p. 72653 - 72658
(2015/09/15)
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- Graphene based material as a base catalyst for solvent free Aldol condensation and Knoevenagel reaction at room temperature
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Graphene oxide (GO) acts as a highly active heterogeneous base catalyst for a wide variety of reactions. Here we have described the catalytic activities of GO in the condensation reaction of various substituted benzaldehydes with acetophenone (aldol condensation) and with active methylene compound malononitrile (Knoevenagel reaction) at room temperature under solvent free condition. GO is characterized by powder X-ray diffraction (XRD), UV-visible spectra, Fourier transform infrared spectroscopy (FT-IR) and AFM. The experimental results showed that the GO had higher catalytic activity and it can be recycled without significant loss of its activity.
- Islam, Sk Manirul,Roy, Anupam Singha,Dey, Ram Chandra,Paul, Sumantra
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- Knoevenagel condensation of diethylmalonate with aldehydes catalyzed by immobilized bovine serum albumin (BSA)
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Knoevenagel condensation between aldehydes and diethylmalonate is catalyzed efficiently by bovine serum albumin (BSA) immobilized covalently on an epoxy-functionalized polymeric support, Immobead IB-350. The reaction is carried out conveniently at room temperature in DMSO in which aliphatic, heterocyclic and aromatic aldehydes react efficiently. After extraction with heptane and treatment with Candida antarctica lipase CAL B, the products are obtained in >95% purity and 85-89% yield. The solvent DMSO, unreacted diethylmalonate and immobilized BSA were easily recovered. Immobilized BSA and recovered DMSO were recycled 5 times without any appreciable loss in yield.
- Ramesh, Perla,Shalini, Basetty,Fadnavis, Nitin W.
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p. 7368 - 7373
(2014/02/14)
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- Synthesis of monosubstituted 1,1-dicarbonyl ester 1,3-dienes
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The synthesis of various electron-deficient 1,1-dicarbonyl ester 1,3-dienes substituted in position 2 or 3 of the diene moiety has been developed. Georg Thieme Verlag Stuttgart. New York.
- Rousseau, Olivier,Delaunay, Thierry,Robiette, Rapha?l
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supporting information
p. 519 - 522
(2014/03/21)
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- DABCO-mediated isocyanide-based multicomponent reaction: Synthesis of highly substituted cyclopentenes
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Highly substituted cyclopentenes can be accessed rapidly from isocyanides, aldehydes and malononitrile or ethyl cyanoacetate (AB2C2) using DABCO as a catalyst under solvent-free conditions at 40 °C within 30 min. This journal is
- Wen, Li-Rong,Lan, Ming-Chao,Yuan, Wen-Kui,Li, Ming
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p. 4628 - 4632
(2014/06/24)
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- Integration of heterogeneous catalysts into complex synthetic routes: Sequential vs. one-pot reactions in a (Knoevenagel + Mukaiyama-Michael + hydrogenation + transesterification) sequence
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Heterogeneous catalysts of different nature can be combined in one-pot tandem reactions, but the compatibility issues of catalysts with reagents, products, and by-products make more convenient the application of a sequential procedure, in which the catalyst is filtered after each reaction and the crude is used in the following reaction without purification. In this way the recovery and reuse of each catalyst can be optimized to obtain the maximum productivity. The nature of the reactions, and the catalysts involved in them, conditions the maximum number of successive steps in the sequence. In the case of the (Knoevenagel + Mukaiyama-Michael + hydrogenation + transesterification) process tested in this work, the optimal results are obtained when the sequential method is applied to only three reactions, whereas the four reactions sequence shows limitations in the yield of the last transesterification step. The Royal Society of Chemistry 2013.
- Fraile, Jose M.,Garcia, Nuria,Herrerias, Clara I.,Mayoral, Jose A.
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p. 436 - 443
(2013/03/28)
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- Tin oxide nanoparticles (NP-SnO2): Preparation, characterization and their catalytic application in the Knoevenagel condensation
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Tin oxide (SnO2) nanoparticles were synthesized by modified thermal decomposition process. Taguchi analysis was used and three important synthetic factors, molar concentration ratio of [NaNO3]/[SnCl 4], temperature and tim
- Sharghi, Hashem,Ebrahimpourmoghaddam, Sakineh,Memarzadeh, Raheleh,Javadpour, Sirous
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p. 141 - 149
(2013/02/25)
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- A formyl peptide substituted with a conformationally constrained phenylalanine residue evokes a selective immune response in human neutrophils
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Formyl-Met-Leu-Phe-OH (fMLP) binds to formyl peptide receptors, FPR1 and FPR2, and evokes migration and superoxide anion production in human neutrophils. To obtain a more effective and selective ligand, fMLP analogs in which the Phe residue was substitute
- Hayashi, Ryo,Miyazaki, Masaya,Osada, Satoshi,Kawasaki, Hiroshi,Fujita, Ichiro,Hamasaki, Yuhei,Kodama, Hiroaki
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p. 668 - 675
(2013/02/25)
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- Asymmetric michael addition of N-tert-butanesulfinyl imidate with α,β-unsaturated diesters: Scope and application to the synthesis of indanone derivatives
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An additive-free and highly diastereoselective Michael addition reaction of an N-tert-butanesulfinyl imidate to α,β-unsaturated diesters has been developed using LDA as a base with good to excellent yields. The utility of this chemistry is further demonstrated by the asymmetric synthesis of 3-substituted indanone derivatives 8a, 8d, 8e, and 8i with high enantiomeric excess, which are potential building blocks for preparing biologically active lead compounds.
- Wang, Jinfang,Zhou, Yu,Zhang, Lei,Li, Zeng,Chen, Xianjie,Liu, Hong
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supporting information
p. 1508 - 1511
(2013/06/27)
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- Synthesis of coumarins via PIDA/I2-mediated oxidative cyclization of substituted phenylacrylic acids
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A variety of functionalized coumarins were synthesized from substituted phenylacrylic acids via PIDA/I2-mediated and irradiation-promoted oxidative carbon-oxygen bond formation. Our studies show that the oxygen in the pendant carboxylic acid group cyclizes favorably to the aryl ring that is cis to it. The main advantages of this method include good functional group tolerance and the transition-metal-free characteristic. The Royal Society of Chemistry 2013.
- Li, Jinming,Chen, Huiyu,Zhang-Negrerie, Daisy,Du, Yunfei,Zhao, Kang
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p. 4311 - 4320
(2013/04/24)
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- Substituted 3(2H)-Furanones by a tandem michael addition/palladium- catalyzed ring-closing protocol
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A novel palladium-catalyzed route for the synthesis of substituted 3(2H)-furanones from activated alkenes and 4-chloroacetoacetate was developed. The first step of the tandem reaction is the Michael addition of an acetoacetate to the alkene followed by palladium-catalyzed ring closure of the adduct to form the furanone. The reaction was extended to a number of substituted alkenes, and the corresponding substituted 3(2H)-furanones were obtained in good to excellent yields. Copyright
- John, Jubi,Hopf, Henning
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supporting information
p. 841 - 845
(2013/03/14)
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- Nickel(ii)-catalyzed enantioselective 1,3-dipolar cycloaddition of azomethine imines with alkylidene malonates
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We demonstrated an asymmetric 1,3-dipolar cycloaddition of azomethine betaines with alkylidene malonates by using a chiral N,N'-dioxide- NiII complex as a catalyst. Both aromatic- and aliphatic-substituted alkylidene malonates were found to be suitable for the reaction. A range of transpyrazolone derivatives was exclusively obtained with excellent yields (up to 99% yield) and good enantioselectivities (up to 97% ee) under mild reaction conditions. The reaction could be carried out on a gram scale with the good results being maintained. Control experiments were performed to elucidate the specific diastereoselectivity of the reaction. The formation of single trans isomers was dominated by secondary orbital interactions between the ester groups of the dipolarophile and the azomethine imine. On the basis of the experimental results and previous reports, a possible catalytic model was assumed.
- Li, Jiangting,Lian, Xiangjin,Liu, Xiaohua,Lin, Lili,Feng, Xiaoming
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supporting information
p. 5134 - 5140
(2013/07/05)
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- Determination of thermodynamic affinities of various polar olefins as hydride, hydrogen atom, and electron acceptors in acetonitrile
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A series of 69 polar olefins with various typical structures (X) were synthesized and the thermodynamic affinities (defined in terms of the molar enthalpy changes or the standard redox potentials in this work) of the polar olefins obtaining hydride anions, hydrogen atoms, and electrons, the thermodynamic affinities of the radical anions of the polar olefins (X ?-) obtaining protons and hydrogen atoms, and the thermodynamic affinities of the hydrogen adducts of the polar olefins (XH?) obtaining electrons in acetonitrile were determined using titration calorimetry and electrochemical methods. The pure Ci - 'C π-bond heterolytic and homolytic dissociation energies of the polar olefins (X) in acetonitrile and the pure Ci - 'C π-bond homolytic dissociation energies of the radical anions of the polar olefins (X?-) in acetonitrile were estimated. The remote substituent effects on the six thermodynamic affinities of the polar olefins and their related reaction intermediates were examined using the Hammett linear free-energy relationships; the results show that the Hammett linear free-energy relationships all hold in the six chemical and electrochemical processes. The information disclosed in this work could not only supply a gap of the chemical thermodynamics of olefins as one class of very important organic unsaturated compounds but also strongly promote the fast development of the chemistry and applications of olefins.
- Cao, Ying,Zhang, Song-Chen,Zhang, Min,Shen, Guang-Bin,Zhu, Xiao-Qing
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p. 7154 - 7168
(2013/08/23)
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- Chiral-Zn(NTf2)2-complex-catalyzed diastereo- and enantioselective direct conjugate addition of arylacetonitriles to alkylidene malonates
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Chiral N,N′-dioxide/Zn(NTf2)2 complexes were demonstrated to be highly effective in the direct asymmetric conjugate addition of arylacetonitriles to alkylidene malonates under mild conditions. A wide range of substrates were tolerated to afford their corresponding products in moderate-to-good yields with high diastereoselectivities (82:18->99:1 d.r.) and enantioselectivities (81-99 % ee). The reactions performed well, owing to the high Lewis acidity of the metal triflimidate and a ligand-acceleration effect. The N,N′-dioxide also benefited the deprotonation process as a Bronsted base. The catalytic reaction could be performed on the gram-scale with retention of yield, diastereoselectivity, and enantioselectivity. The products that contained functional groups were ready for further manipulation. In addition, a possible catalytic model was proposed to explain the origin of the asymmetric induction. Copyright
- Yao, Jingjing,Liu, Xiaohua,He, Peng,Zhu, Yin,Lian, Xiangjin,Lin, Lili,Feng, Xiaoming
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supporting information
p. 16424 - 16430
(2013/12/04)
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- Designing bifunctional acid-base mesoporous hybrid catalysts for cascade reactions
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Bifunctional mesoporous hybrid materials, containing both proton sponges and acid groups, have been prepared following different synthetic routes: co-condensation processes (sol-gel or micellar one-pot routes) or post-synthetic grafting of the organic functionalities. 1,8-Bis(dimethylamino)naphthalene (DMAN), a proton sponge with high pKa, was used as an organic functional builder base and 3-mercaptopropyltriethoxysilane (MPTES) as a pendant precursor of sulfonic acids. The bifunctional hybrid materials were extensively characterized and were investigated as heterogeneous catalysts for various one-pot C-C bond-forming cascade reactions such as deacetalization-Knoevenagel condensation or deacetalization-nitroaldol (Henry) reaction.
- Gianotti, Enrica,Diaz, Urbano,Velty, Alexandra,Corma, Avelino
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p. 2677 - 2688
(2013/09/24)
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- Efficient protocol for knoevenagel condensation in presence of the diazabicyclo[5.4.0]undec-7-ene-water complex
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A simple and efficient protocol for Knoevenagel condensation has been developed in the presence of diazabicyclo[5.4.0]undec-7-ene (DBU)/water complex. A widely range of carbonyl compounds (aliphatic and aromatic aldehydes, ketones) could react smoothly with methylene active ingredients (malononitrile, ethyl cyanoacetate, diethyl malonate and acetylacetone), which can not proceed by conven- tional catalyst. Other significant features of this method include readily work-up, good recyclability of catalytic system and short reaction time.
- Ying, An-Guo,Wu, Cheng-Lin,He, Guang-Hong
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experimental part
p. 653 - 656
(2012/07/28)
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- Schiff base structured acid-base cooperative dual sites in an ionic solid catalyst lead to efficient heterogeneous knoevenagel condensations
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An acid-base bifunctional ionic solid catalyst [PySaIm]3PW was synthesized by the anion exchange of the ionic-liquid (IL) precursor 1-(2-salicylaldimine)pyridinium bromide ([PySaIm]Br) with the Keggin-structured sodium phosphotungstate (Na
- Zhang, Mingjue,Zhao, Pingping,Leng, Yan,Chen, Guojian,Wang, Jun,Huang, Jun
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p. 12773 - 12782
(2012/11/07)
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- Organic amine grafting on mesoporous silica as a hybrid catalyst for heterogeneous three-component one-pot reaction
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The organic-inorganic hybrid catalyst was prepared by immobilizing 3-methylaminopropyl moiety onto mesoporous silica, MCM-41, and applied for solid base catalyst of three-component one-pot reaction, i.e. Knoevenagel condensation of aldehyde with the active methylene compound to yield an electron deficient alkene which is subjective to be reacted with nitromethane by Michael addition to form tri-substituted primary nitro compound. The catalyst was characterized by powder-XRD, TG-DTA, FT-IR, nitrogen adsorption-desorption measurement and solid-state cross polarization magic angle spinning (CP/MAS) NMR, and exhibited high catalytic activity in three-component one-pot reaction; however, with poor reusability.
- Komura, Kenichi,Mishima, Yuta,Koketsu, Mamoru
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p. 128 - 132
(2013/02/21)
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- Strong organic bases as building blocks of mesoporous hybrid catalysts for C-C forming bond reactions
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1,8-Bis(tetramethylguanidino)naphthalene (TMGN), a neutral organic base that combines the properties of guanidine and the properties of proton sponges, was used as a building block to produce organic-inorganic silica-based mesoporous hybrids with strong basic properties. The TMGN-based mesoporous hybrids (TMGN/SiO2) were prepared by a sol-gel route working at a neutral pH and low temperatures, which avoided the use of SDAs. TMGN has been modified in order to have two terminal reactive silyl groups able to perform co-condensation with a conventional organosilane (TMOS) used as a silicon source. This synthesis has allowed us to directly introduce the unmodified, functionalized TMGN as part of the walls of the mesoporous silica by a one-pot synthesis. TMGN/SiO2 hybrid materials present excellent catalytic properties for C-C bond forming reactions: Knoevenagel, Henry (nitroaldol), and Claisen-Schmidt condensations. The activity of the hybrid materials is higher than that of the counterpart homogeneous catalyst. The TMGN/SiO2 hybrid catalyst was synthesized using 1,8-bis(tetramethylguanidino)naphthalene (TMGN). It combines the properties of guanidine and of proton sponges. A functionalized TMGN builder was introduced directly into a nonordered mesoporous silica by the NH4F-catalyzed sol-gel route. This catalyst shows good catalytic performances in C-C bond forming reactions. Copyright
- Gianotti, Enrica,Diaz, Urbano,Velty, Alexandra,Corma, Avelino
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p. 5175 - 5185
(2013/01/15)
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- Solvent-free Knoevenagel condensation over iridium and platinum hydroxyapatites
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The Knoevenagel condensation between various aldehydes (benzaldehyde, p-methoxybenzaldehyde and 1-naphthaldehyde) and esters (ethylcyanoacetate, ethylacetoacetate and diethylmalonoester) was carried out under solvent-free condition in the presence of iridium or platinum hydroxyapatites as a catalyst.
- Pillai,Singh,Jonnalagadda
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experimental part
p. 536 - 539
(2011/10/31)
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- The non-metathetic role of Grubbs' carbene complexes: From hydrogen-free reduction of α,β-unsaturated alkenes to solid-supported sequential cross-metathesis/reduction
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An efficient and high-yielding "hydrogen-free" reduction of α,β-unsaturated alkenes was carried out employing Grubbs' catalyst in a non-metathetic role and Et3SiH. Conditions were optimized under microwave irradiation. Application to the solid-phase organic synthesis allows a facile construction of sp3-sp3 carbon bonds through a sequential cross metathesis/olefin reduction.
- Poeylaut-Palena, Andres A.,Testero, Sebastian A.,Mata, Ernesto G.
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supporting information; experimental part
p. 1565 - 1567
(2011/03/20)
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- Sc(OTf)3-catalyzed tandem [3+2] cycloaddition/nucleophilic ring-opening reaction of cyclopropane 1,1-diesters with azomethine ylides
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A new Sc(OTf)3-catalyzed tandem reaction combined with a dimerized self-[3+2] cycloaddition of azomethine ylide and a nucleophilic ring-opening of cyclopropane 1,1-diester has been developed. A series of polyfunctionalized imidazolidine derivatives were synthesized by this reaction (Yield 44-77 %). In some cases, this tandem reaction was also accompanied by a cross-[3+2] cycloaddition of cyclopropane 1,1-diester with imine.
- Fang,Hu,Ren,Wang
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experimental part
p. 1479 - 1487
(2011/12/22)
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- Synthesis and substitution reactions of 4(6)-chlorodihydropyrimidines
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Chlorination of the corresponding ketones with phenylphosphonic dichloride (PhPOCl2) provided ethyl 6(4)-chloro-2-methyl-4(6)-phenyl-1,4(6)- dihydropyrimidine-5-carboxylate in good yield. The cross-coupling reactions of organoboronic acids or t
- Cho, Hidetsura,Yasui, Yoshizumi,Kobayashi, Satoshi,Kwon, Eunsang,Arisawa, Mieko,Yamaguchi, Masahiko
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body text
p. 1807 - 1818
(2011/09/21)
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- Urea-functionalized mesoporous polymeric catalyst: A cooperative effect between support and secondary amine on water-medium Knoevenagel reactions
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Urea-functionalized mesoporous polymers (urea-MPs) were synthesized through the surfactant-directed urea-phenol-formaldehyde oligomers self-assembly approach. The as-prepared urea-MPs material exhibited superior catalytic activity than parent urea in water-medium Knoevenagel condensation reactions and could be used repetitively for seven times. The excellent activity could be attributed to the synergic effect derived from the secondary amine with the surface phenolic groups in the mesoporous support, which generated the acid-base cooperative catalytic behavior. Meanwhile, the urea functional groups embedded in the mesopore wall could inhibit the leaching of active species and thus resulted in the relatively good durability.
- Zhu, Ruixing,Shen, Jian,Wei, Yongyi,Zhang, Fang
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experimental part
p. 1861 - 1866
(2011/10/10)
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- Synthesis and anti-tumor activity of novel ethyl 3-aryl-4-oxo-3,3a,4,6- tetrahydro-1H-furo[3,4-c]pyran-3a-carboxylates
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A series of ethyl 3-aryl-4-oxo-3,3a,4,6-tetrahydro-1H-furo[3,4-c]pyran-3a- carboxylates were prepared through the metal-catalyzed domino reaction of alkylidene malonates and 1,4-butynediol under a one-pot reaction condition at room temperature. Their in vitro anti-proliferative activities were subsequently evaluated in A549, QGY and HeLa cells. The majority of the compounds showed potent anti-tumor activity against HeLa cells. In particular, compound 3l was the most potent compound with IC50 value of 5.4 μM. For the first time, the X-ray structure of the anti-tumor ethyl 3-aryl-4-oxo-3,3a,4,6- tetrahydro-1H-furo[3,4-c]pyran-3a-carboxylates is determined.
- Wang, Tiantian,Liu, Jia,Zhong, Hanyu,Chen, Huan,Lv, Zhiliang,Zhang, Yikai,Zhang, Mingfeng,Geng, Dongping,Niu, Chunjuan,Li, Yongmei,Li, Ke
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scheme or table
p. 3381 - 3383
(2011/06/24)
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- Phosphine-catalyzed [4+2] annulations of 2-alkylallenoates and olefins: Synthesis of multisubstituted cyclohexenes
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From our investigations on phosphine-catalyzed [4+2] annulations between α-alkyl allenoates and activated olefins for the synthesis of cyclohexenes, we discovered a hexamethylphosphorous triamide (HMPT)-catalyzed [4+2] reaction between α-alkyl allenoates
- Tran, Yang S.,Martin, Tioga J.,Kwon, Ohyun
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body text
p. 2101 - 2106
(2011/10/11)
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- Dehydrogenative functionalization of C(sp3)-H bonds adjacent to a heteroatom mediated by oxoammonium salts
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The first oxoammonium salt mediated formation of C-C bonds from, benzylic C(sp3)-H bonds adjacent to an oxygen or nitrogen, atom by dehydrogenative coupling with enolizable carbonyls has been developed. The use of these oxi- dants in combination with catalytic amounts of Fe(OTf)2 as Lewis acid, allows the reaction to be carried out under mild conditions, leading to the corresponding coupling products in moderate to good yields.
- Richter, Heinrich,Mancheno, Olga Garcia
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experimental part
p. 4460 - 4467
(2010/10/04)
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- Facile separation catalyst system: Direct diastereoselective synthesis of (E)-α,β-unsaturated ketones catalyzed by an air-stable Lewis acidic/basic bifunctional organobismuth complex in ionic liquids
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The catalyst system that comprises an air-stable bifunctional Lewis acidic/basic organobismuth complex and [Bmim]BF4 is highly efficient in the cross-condensation of aldehydes with ketones. Through switching the reaction from homogeneous to heterogeneous, the system shows facile separation ability and facile reusability.
- Qiu, Renhua,Qiu, Yimiao,Yin, Shuangfeng,Song, Xingxing,Meng, Zhengong,Xu, Xinhua,Zhang, Xiaowen,Luo, Shenglian,Au, Chak-Tong,Wong, Wai-Yeung
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supporting information; scheme or table
p. 1767 - 1771
(2011/02/23)
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- Highly efficient and selective synthesis of (E)-α,β-unsaturated ketones by crossed condensation of ketones and aldehydes catalyzed by an air-stable cationic organobismuth perfluorooctanesulfonate
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An air-stable cationic organobismuth perfluorooctanesulfonate possessing both acidic and basic characters was synthesized, and showed high catalytic activity, diastereoselectivity, stability, and reusability in the one-pot synthesis of (E)-α,β-unsaturated ketones through highly selective crossed condensation of ketones and aldehydes in water.
- Qiu, Renhua,Qiu, Yimiao,Yin, Shuangfeng,Xu, Xinhua,Luo, Shenglian,Au, Chak-Tong,Wong, Wai-Yeung,Shimada, Shigeru
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experimental part
p. 153 - 162
(2010/06/19)
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- Solvent-free knoevenagel condensation over cobalt hydroxyapatite
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The Knoevenagel condensation between various aldehydes (benzaldehyde, 1-naphthaldehyde, p-bromobenzaldehyde and p-methoxybenzaldehyde) and esters (ethylcyanoacetate, ethylacetoacetate and diethylmalonoester) was carried out under solvent free condition in the presence of cobalt hydroxyapatite (CoHAp), as a catalyst. Good to excellent yields (35-96%) were obtained. The catalyst is found to be superior over fluorapatite and several other heterogeneous catalysts. The catalyst can be recycled at least 3 times. Copyright
- Pillai, Manoharan Karuppiah,Singh, Sooboo,Jonnalagadda, Sreekanth B.
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experimental part
p. 3710 - 3715
(2010/12/25)
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