- Efficient synthesis of chalcones by a solid base catalyst
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A simple and efficient heterogeneous procedure has been developed for the synthesis of chalcones (α,β-unsaturated ketones) by the Claisen-Schmidt condensation between arylaldehydes and ketones using Mg-Al-OtBu hydrotalcite (HT-OtBu) as catalyst. Copyright Taylor & Francis, Inc.
- Kantam, M.Lakshmi,Veda Prakash,Venkat Reddy
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- Intermolecular [2+2] photocycloaddition of chalcones with 2,3-dimethyl-1,3-butadiene under neat reaction conditions
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The intermolecular [2 + 2] photocycloaddition of chalcones with 2,3-dimethyl-1,3-butadiene under visible-light irradiation for the synthesis of cyclobutane derivatives has been developed. Without using any photosensitizer, metallic catalyst and solvent, the reaction proceeded with high regioselectivity and moderate to high stereoselectivity. Mild reaction conditions and no additives make the reaction easy to operate. Control experiments and density functional theory (DFT) computations demonstrated that the reaction takes place via visible-light activation of chalcones, which is different from the previously reported [2 + 2] cycloaddition of chalcones.
- Tang, Fang,Tang, Li,Guan, Zhi,He, Yan-Hong
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- Synthesis of chalcones catalyzed by aminopropylated silica sol-gel under solvent-free conditions
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Aminopropylated nanosilica was prepared by a simple sol-gel process from tetraethyl orthosilicate (TEOS) and then it was functionalized with different amounts of 3-aminopropyltriethoxysilane (APS) under toluene reflux. The prepared solids were characterized by means of XRD, FT-IR, TGA-DTA, SEM-EDS, and TEM. Their textural properties were determined by adsorption-desorption isotherms of N2 at 77 K. It was proved that the amount of APS used in the preparation process had a great influence on the physicochemical properties of the hybrid organic-inorganic solid materials. The materials were used as catalyst in the Claisen-Schmidt preparation of chalcones for the reaction of substituted acetophenones and benzaldehydes under solvent-free conditions. The result showed that the presence of a high amount of aminopropyl groups was important for a very good performance of the catalyst in the substrate conversion. Also, the influence of different groups in the aromatic ring of acetophenones and benzaldehydes was investigated. In all cases, coproduct formation was not observed; the catalysts were recovered and can be recycled twice without appreciable loss of reactivity.
- Romanelli, Gustavo,Pasquale, Gustavo,Sathicq, ángel,Thomas, Horacio,Autino, Juan,Vázquez, Patricia
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- Simple access to α, β unsaturated ketones by acid-catalyzed solvent- free reactions
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Various chalcones and dibenzylidene cycloalkanones were readily prepared in a few minutes with good yields by simply mixing aromatic aldehydes with substituted acetophenones or benzaldehyde with cycloalkanones in the presence of catalytic amounts of p-toluene sulfonic acid under focused microwave irradiation.
- Le Gall, Erwan,Texier-Boullet, Fran?oise,Hamelin, Jack
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- Aluminosilicate catalysis of chalcone Diels-Alder reactions
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Previously unreported Diels-Alder adducts of substituted chalcones with isoprene and myrcene have been formed at more than 0°C by employing a nanoporous aluminosilicate catalyst. This catalyst eliminates problems with diene polymerization that are encountered with many other Lewis acids. The chalcone component has some size restrictions. Copyright Taylor & Francis Group, LLC.
- Corbett, Jennifer L.,Weavers, Rex T.
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- Quantitative structure-activity relationships of mosquito larvicidal chalcone derivatives
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The mosquito larvicidal activities of a series of chalcones and some derivatives were subjected to a quantitative structure-activity relationship (QSAR) study, using more than a thousand constitutional, topological, geometrical, and electronic molecular descriptors calculated with Dragon software. The larvicidal activity values for 28 active compounds of the series were predicted, showing in general a good approximation to the experimental values found in the literature. Chalcones having one or both electron-rich rings showed high toxicity. However, the activity of chalcones was reduced by electron-withdrawing groups, and this was roughly diminished by derivatization of the carbonyl group. A set of six chalcones being structurally similar to some of the active ones, with a still unknown larvicidal activity, were prepared. Their activity values were predicted by applying the developed QSAR models, showing that two chalcones of such set, both 32 and 34, were expected to be highly active.
- Pasquale, Gustavo,Romanelli, Gustavo P.,Autino, Juan C.,Garcia, Javier,Ortiz, Erlinda V.,Duchowicz, Pablo R.
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- Heteroleptic copper(I) complexes as energy transfer photocatalysts for the intermolecular [2 + 2] photodimerization of chalcones, cinnamates and cinnamamides
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The [2 + 2] photodimerization of chalcones, cinnamates and cinnamamides can be effectively catalyzed by heteroleptic copper(I) complexes. The reactions were carried out under mild reaction conditions and the products were obtained in 20–72% yield under visible light irradiation. The copper-based photocatalyst comprised of the rigid phenanthroline ligand with substituents at the 2,9-positions and the 4,7-positions showed high activity in the photodimerization via an energy transfer pathway.
- Wu, Qing-An,Ren, Chen-Chao,Chen, Feng,Wang, Tian-Qi,Zhang, Yu,Liu, Xue-Fen,Chen, Jian-Bin,Luo, Shu-Ping
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supporting information
(2021/05/10)
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- Modular access to 1,2-allenyl ketones based on a photoredox-catalysed radical-polar crossover process
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Herein, a new protocol dealing with the preparation of 1,2-allenyl ketones has been successfully developedviathe reactions of enynes with radicals enabled by dual photoredox/copper catalysis. Based on the results of a deuteration experiment and the competition reaction between cyclopropanation and allenation, the mechanism based on a photoredox-neutral-catalysed radical-polar crossover process has been proposed. Synthetic applications of allenes have also been demonstrated.
- Du, Chan,Fang, Jianghua,Fang, Yewen,Lei, Wan,Li, Yan,Liu, Yongjun
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supporting information
p. 8502 - 8506
(2021/10/20)
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- Orchestrating a β-Hydride Elimination Pathway in Palladium(II)-Catalyzed Arylation/Alkenylation of Cyclopropanols Using Organoboron Reagents
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The scope of chemoselective β-hydride elimination in the context of arylation/alkenylation of homoenolates from cyclopropanol precursors using organoboronic reagents as transmetalation coupling partners was examined. The reaction optimization paradigm revealed a simple ligand-free Pd(II) catalytic system to be most efficient under open air conditions. The preparative scope, which was investigated with 48 examples, supported the applicability of this reaction to a wide range of substrates tolerating a variety of functional groups while delivering β-substituted enone and dienone derivatives in 62-95% yields.
- Ilangovan, Andivelu,Ramar, Thangeswaran,Subbaiah, Murugaiah A. M.
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- Green method for high-selectivity synthesis of chalcone compounds
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Under the condition of air, the water-soluble inorganic weak base is used as a catalyst to catalyze the hydrogen transfer reaction of the propargyl alcohol compound, so that the green synthesis of the high-trans selective chalcone compound is realized. Reaction temperature: 80 - 120 °C and reaction time 12 - 48 hours. To the technical scheme, any transition metal catalyst and ligand do not need to be used, inert gas protection is not needed, no other byproducts are generated, the atom economy 100%, green and environment friendliness are avoided, and the product is a high-selectivity (E)-type product. The reaction conditions are relatively low in requirement. Compared with the prior art, the alkali catalyst is obvious in advantages, and has a certain application prospect in the fields of organic synthesis, biochemistry, medicine and the like.
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Paragraph 0031-0034
(2021/10/02)
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- Iodine-catalyzed α,β-dehydrogenation of ketones and aldehydes generating conjugated enones and enals
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A transition metal-free α,β-dehydrogenation of ketones and aldehydes was developed. This reaction was conducted in a facile I2/KI/DMSO system to produce the corresponding unsaturated compounds in good to high yields. The gram-scale experiment also indicated the potential synthetic value of this new reaction in organic synthesis. In the reaction, DMSO acted as both solvent and mild oxidant.
- Cao, Yuanjie,Chen, Tieqiao,Huang, Tianzeng,Liu, Long
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supporting information
p. 8697 - 8701
(2020/06/08)
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- Synthesis of 3-fluoro-2,5-disubstituted furans through ring expansion ofgem-difluorocyclopropyl ketones
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The synthesis of 3-fluoro-2,5-disubstituted furans fromgem-difluorocyclopropyl ketones was accomplished using trifluoromethanesulfonic acid (CF3SO3H) through ring expansion owing to the activation of the carbonyl group in the starting material. The present synthesis of 3-fluorofurans tolerates substrates designed for products with aromatic substituents at the C-2 and C-5 positions.
- Amii, Hideki,Matsumura, Chihori,Sugiishi, Tsuyuka
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supporting information
p. 3459 - 3462
(2020/05/25)
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- N-Heterocyclic Carbene Catalyzed Synthesis of Trisubstituted Epoxides via Tandem Amidation/Epoxidation Sequence
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A tandem amidation/epoxidation sequence between various substituted chalcones and N,N-dimethylformamide (DMF) for the synthesis of trisubstituted epoxides employing N-heterocyclic carbene catalysis was developed. This reaction was performed under metal-free conditions in the presence of tert-butyl hydroperoxide (TBHP) as the oxidant. Trisubstituted epoxides bearing a ketone and an amide functionality (N,N-dimethyl formyl group) were synthesized starting from a wide range of chalcones in moderate to good yields with excellent diastereoselectivity.
- Devi, E. Sankari,Pavithra, Thangavel,Tamilselvi,Nagarajan, Subbiah,Sridharan, Vellaisamy,Maheswari, C. Uma
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supporting information
p. 3576 - 3580
(2020/04/20)
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- Antiproliferative effects of chalcones on T cell acute lymphoblastic leukemia-derived cells: Role of PKCβ
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In this study, a series of 20 chalcone derivatives was synthesized, and their antiproliferative activity was tested against the human T cell acute lymphoblastic leukemia-derived cell line, CCRF-CEM. On the basis of the structural features of the most active compounds, a new library of chalcone derivatives, according to the structure–activity relationship design, was synthesized, and their antiproliferative activity was tested against the same cancer cell line. Furthermore, four of these derivatives (compounds 3, 4, 8, 28), based on lower IC50 values (between 6.1 and 8.9 μM), were selected for further investigation regarding the modulation of the protein expression of RACK1 (receptor for activated C kinase), protein kinase C (PKC)α and PKCβ, and their action on the cell cycle level. The cell cycle analysis indicated a block in the G0/G1 phase for all four compounds, with a statistically significant decrease in the percentage of cells in the S phase, with no indication of apoptosis (sub-G0/G1 phase). Compounds 4 and 8 showed a statistically significant reduction in the expression of PKCα and an increase in PKCβ, which together with the demonstration of an antiproliferative role of PKCβ, as assessed by treating cells with a selective PKCβ activator, indicated that the observed antiproliferative effect is likely to be mediated through PKCβ induction.
- Corsini, Emanuela,Facchetti, Giorgio,Esposito, Sara,Maddalon, Ambra,Rimoldi, Isabella,Christodoulou, Michael S.
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- Donor-acceptor fluorophores as efficient energy transfer photocatalysts for [2 + 2] photodimerization
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Mild [2 + 2] photodimerization of enone substrates was induced by donor-acceptor fluorophores. Enone substrates were activated efficiently for anti-head to head dimerizations with a high yield (up to 83%) and high selectivity. The adjustable excited state potential also allows donor-acceptor fluorophores to be used for isomerization of the above substrates, confirming the potential of donor-acceptor fluorophores as energy transfer photocatalysts.
- Chen, Feng,Chen, Hao,Liu, Xue-Fen,Luo, Shu-Ping,Ren, Chen-Chao,Wu, Qing-An,Xu, Liang-Xuan,Yu, Xiao-Cong
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p. 3707 - 3716
(2020/06/03)
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- Highly Enantioselective Epoxidation of α,β-Unsaturated Ketones Using Amide-Based Cinchona Alkaloids as Hybrid Phase-Transfer Catalysts
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A series of 20 one chiral epoxides were obtained with excellent yields (up to 99%) and enantioselectivities (up to >99% ee) using hybrid amide-based Cinchona alkaloids. Our method is characterized by low catalyst loading (0.5 mol %) and short reaction times. Moreover, the epoxidation process can be carried out in 10 cycles, without further catalyst addition to the reaction mixture. This methodology significantly enhance the scale of the process using very low catalyst loading.
- Jurczak, Janusz,Majdecki, Maciej,Tyszka-Gumkowska, Agata
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supporting information
(2020/11/13)
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- DBU-Catalyzed Rearrangement of Secondary Propargylic Alcohols: An Efficient and Cost-Effective Route to Chalcone Derivatives
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A 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-catalyzed rearrangement of diarylated secondary propargylic alcohols to give α,β-unsaturated carbonyl compounds has been developed. The typical 1,3-transposition of oxy functionality, characteristic of Mayer-Schuster rearrangements, is not observed in this case. A broad substrate scope, functional-group tolerance, operational simplicity, complete atom economy, and excellent yields are among the prominent features of the reaction. Additionally, the photophysical properties and crystal-structure-packing behavior of selected compounds were investigated and found to be of interest.
- De, Rimpa,Savarimuthu, Antony,Ballav, Tamal,Singh, Pijush,Nanda, Jayanta,Hasija, Avantika,Chopra, Deepak,Bera, Mrinal K.
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supporting information
p. 1587 - 1592
(2020/08/28)
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- Studies of NMR Chemical Shifts of Chalcone Derivatives of Five-membered Monoheterocycles and Determination of Aromaticity Indices
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A series of the chalcone derivatives of the five-membered monoheterocyclic compounds, (E)-1-aryl-3-heteroarylpropen-1-ones, were prepared by aldol condensation of the corresponding aldehydes of thiophene, pyrrole, and furan with m- and p-substituted acetophenones. Similar condensation of the acetyl compounds of the heterocycles with m- and p-substituted benzaldehydes gave another series of the chalcone derivatives, (E)-1-heteroaryl-3-arylpropen-1-ones. The 13C chemical shift values (δC) of the chalcone derivatives were determined in order to find if they correlated with the Hammett σ values. A good correlation, especially for the β-C for both series, was found for the 13C chemical shift values (δC) of the chalcone derivatives with the Hammett σ values. The chemical shift values of the β-C of the heterocyclic compounds were plotted against those of the benzene derivatives. The resulting slopes were found to be close to the values of the aromaticity indices.
- Jeong, Eun Jeong,Lee, In-Sook Han
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p. 668 - 673
(2019/07/12)
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- A nanoscale iron catalyst for heterogeneous direct: N - And C -alkylations of anilines and ketones using alcohols under hydrogen autotransfer conditions
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Here, we report a commercially available nanoscale Fe catalyst for heterogeneous direct N- and C-alkylation reactions of anilines and methyl ketones with alcohols. A hydrogen autotransfer mechanism has been found to operate in these reactions by deuterium labelling studies. In addition, dehydrogenative quinoline synthesis has been demonstrated from amino benzyl alcohols and acetophenones.
- Nallagangula, Madhu,Sujatha, Chandragiri,Bhat, Venugopal T.,Namitharan, Kayambu
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supporting information
p. 8490 - 8493
(2019/07/22)
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- Basic Anion-Exchange Resin-Catalyzed Aldol Condensation of Aromatic Ketones with Aldehydes in Continuous Flow
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A general method for the aldol condensation of aromatic ketones with aldehydes was developed under continuous-flow conditions using a commercially available, strongly basic anion-exchange resin (A26) as catalyst. This procedure, in addition to exhibiting a wide substrate scope, promoted carbon-carbon bond formation under mild conditions using a quasi-stoichiometric ratio of starting reagents with good to excellent yields, thereby forming a limited amount of waste and allowing the process to be applied to sequential-flow systems. A proof of concept was developed in the first fully heterogeneously catalyzed two-step flow synthesis of donepezil, which is a blockbuster commercial anti-Alzheimer's drug.
- Laroche, Benjamin,Saito, Yuki,Ishitani, Haruro,Kobayashi, Shū
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supporting information
p. 961 - 967
(2019/05/02)
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- Syntheses, structures, and catalytic activity in Friedel–Crafts acylations of substituted tetramethylcyclopentadienyl molybdenum carbonyl complexes
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Reactions of the substituted tetramethylcyclopentadienes [C5HMe4R] [R?=?tBu, Ph, CH2CH2C(CH3)3] with Mo(CO)3(CH3CN)3 in refluxing xylene gave a series of dinuclear molybdenum carbonyl complexes [(η5-C5Me4R)Mo(CO)3]2 [R?=?tBu (1), Ph (2), CH2CH2C(CH3)3 (3)], [(η5-C5MetBu)Mo(μ-CO)2]2 (4)], and [(η5-C5Me4)tBu]2Mo2O4(μ-O) (5)], respectively. Complexes 1–5 were characterized by elemental analysis, IR, 1H NMR, and 13C NMR spectroscopy. In addition, their crystal structures were determined by X-ray crystal diffraction analysis. The catalytic activities of complexes 1–3 in Friedel–Crafts acylation in the presence of o-chloranil has also been investigated; the reactions were achieved under mild conditions to give the corresponding products in moderate yields.
- Li, Tong,Yan, Xin-Long,Li, Zhan-Wei,Ma, Zhi-Hong,Li, Su-Zhen,Han, Zhan-Gang,Zheng, Xue-Zhong,Lin, Jin
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p. 313 - 322
(2018/02/22)
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- Visible Light-Induced Aerobic Epoxidation of α,β-Unsaturated Ketones Mediated by Amidines
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An aerobic photoepoxidation of α,β-unsaturated ketones driven by visible light in the presence of tetramethylguanidine (3b), tetraphenylporphine (H2TPP), and molecular oxygen under mild conditions was revealed. The corresponding α,β-epoxy ketones were obtained in yields of up to 94% in 96 h. The reaction time was shortened to 4.6 h by flow synthesis. The mechanism related to singlet oxygen was supported by experiments and density functional theory (DFT) calculations.
- Wu, Yufeng,Zhou, Guangli,Meng, Qingwei,Tang, Xiaofei,Liu, Guangzhi,Yin, Hang,Zhao, Jingnan,Yang, Fan,Yu, Zongyi,Luo, Yi
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p. 13051 - 13062
(2018/10/25)
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- Synthesis and evaluation of central antinociceptive activity of ring substituted chalcones; molecular docking studies with monoacylglycerol lipase (MAGL) enzyme
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Chalcones possess Michael acceptor property due to the presence of α,β-unsaturated enone moiety in their structure. In the present study, molecular docking was performed to predict binding affinity of ring substituted chalcones with Monoacylglycerol lipase (MAGL), a serine hydrolase enzyme which can inhibited by Michael acceptors such as maleimide derivatives. 3, 4-Dimethoxy derivative, 3 h with -44.45 kJmol-1 of interaction energy, exhibited highest binding affinity and formed Pi-Sulphur interactions with methionine-123 residue of MAGL enzyme. As MAGL is an emerging target for antinociceptive drug development, ring substituted chalcones were synthesized and evaluated for their central antinociceptive activity using tail immersion and hot plate methods. The results revealed that compound 3 h chalcone bearing methoxy groups at 3rd and 4th positions of phenyl ring exhibited good antinociceptive activity in both the models. Good correlation was observed between antinociceptive activity and binding affinity toward MAGL in case of compound 3 hour.
- Begum, Shaheen,Begum, Arifa,Koganti, Bharathi
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p. 1890 - 1897
(2018/09/18)
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- Three-Component Synthesis of a Library of m-Terphenyl Derivatives with Embedded β-Aminoester Moieties
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The three-component reaction between alkyl- or arylamines, β-ketoesters and chalcones in refluxing ethanol containing a catalytic amount of Ce(IV) ammonium nitrate allowed the construction of a large library of highly substituted dihydro-m-terphenyl derivatives containing β-alkylamino- or β-arylamino ester moieties. This process generates three new bonds and one ring and proceeds in high atom economy, having two molecules of water as the only side product. Another domino process, in which the original MCR was telescoped with a subsequent aza Michael/retro-aza Michael sequence, allowed the one-pot preparation of a library of compounds with a N-unsubstituted β-aminoester fragment. Finally, to extend the structural diversity of these libraries, we also examined the aromatization of the central ring of our compounds in the presence of dichlorodicyanoquinone. This reaction sequence did not affect the integrity of a stereogenic center belonging to the amino component.
- Rocchi, Damiano,González, Juan F.,Gómez-Carpintero, Jorge,González-Ruiz, Víctor,Martín, M. Antonia,Sridharan, Vellaisamy,Menéndez, J. Carlos
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p. 722 - 731
(2018/10/20)
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- Highly efficient synthesis of aryl ketones by PEPPSI-palladium catalyzed acylative Suzuki coupling of amides with diarylborinic acids
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An improved acylative cross-coupling of various N-methyl-N-tosyl amides with diarylborinic acids for synthesis of aryl ketones is developed. In most cases, aryl ketones could be obtained in excellent yields by using 1 mol% 2,6-diisopropylphenylimidazolylidene and 3-chloropyridine co-supported palladium chloride as catalyst in the presence of 3 equiv. K2CO3 as base in refluxing THF. The readily prepared and cost-effective substrates, N-methyl-N-tosylamides and diarylborinic acids, and the commercially available catalyst system promise a practical and efficient access to aryl ketones.
- Wang, Chen,Huang, Lingyun,Wang, Fengze,Zou, Gang
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supporting information
p. 2299 - 2301
(2018/05/16)
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- Transition-Metal-Free Catalytic Formal Hydroacylation of Terminal Alkynes
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Although hydroacylation is a very useful reaction for producing ketones from aldehydes with 100% atom efficiency, classical Rh-catalyzed hydroacylation presents several problems, including the need for transition metal catalysts, unwanted decarbonylation of aldehydes, and difficulty in regioselectivity control. However, formal hydroacylation utilizing the nucleophilicity of terminal alkynes can avoid these problems. In this work, we have achieved transition-metal-free formal hydroacylation of terminal alkynes using an Mg3Al-CO3-layered double hydroxide as a heterogeneous catalyst. This system was applicable to the efficient synthesis of α,β-unsaturated ketones with various substituents, and the catalyst can be reused without a significant loss of catalytic performance.
- Yatabe, Takafumi,Mizuno, Noritaka,Yamaguchi, Kazuya
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p. 11564 - 11569
(2018/11/23)
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- CBr4 as a Halogen Bond Donor Catalyst for the Selective Activation of Benzaldehydes to Synthesize α,β-Unsaturated Ketones
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CBr4 has been employed as a halogen bond donor catalyst for the selective activation of aldehyde, to achieve an efficient solvent- and metal-free CC bond forming reaction in the presence of strong acid sensitive groups such as methoxy, cyanide, ester, and ketal for the synthesis of α,β-unsaturated ketones. This unique capability of CBr4 to act as a halogen bond donor has been explored and established using UV-vis as well as IR spectroscopy. Moreover, this unprecedented methodology enables the synthesis of the pharmaceutically important molecule licochalcone A.
- Kazi, Imran,Guha, Somraj,Sekar, Govindasamy
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supporting information
p. 1244 - 1247
(2017/03/14)
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- Photoredox-Catalyzed Cyclopropanation of Michael Acceptors
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A new protocol for the catalytic cyclopropanation of α,β-unsaturated carbonyl compounds with diiodomethane by means of photoredox catalysis has been successfully developed. The transformation is characterized by its mild conditions, functional-group compatibility, and excellent selectivity profile.
- del Hoyo, Ana M.,García Suero, Marcos
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supporting information
p. 2122 - 2125
(2017/04/24)
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- Design, Synthesis, and Docking Study of Pyrimidine–Triazine Hybrids for GABA Estimation in Animal Epilepsy Models
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A series of new pyrimidine–triazine hybrids (4a–t) was designed and synthesized, from which potent anticonvulsant agents were identified. Most of the compounds exhibited promising anticonvulsant activity against the maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) tests, along with minimal motor impairment with higher safety compared to the standard drugs, phenytoin and carbamazepine. In the series, 5-(4-(4-fluorophenyl)-6-(4-hydroxyphenyl)-2-thioxo-5,6-dihydropyrimidin-1(2H)-yl)-1,2-dihydro-1,2,4-triazin-3(6H)-one (4o) and 5-(6-(4-hydroxy-3-methoxyphenyl)-4-(4-hydroxyphenyl)-2-thioxo-5,6-dihydropyrimidin-1(2H)-yl)-1,2-dihydro-1,2,4-triazin-3(6H)-one (4s) emerged as most potent anticonvulsant agents with median doses of 22.54 and 29.40 mg/kg (MES ED50), 285.02 and 293.42 mg/kg (scPTZ ED50), and 389.11 and 412.16 mg/kg (TD50), respectively. Docking studies were also performed for all synthesized compounds to get insight into the binding pattern toward the GABAA receptor as a possible mechanism of their anticonvulsant action, and in silico ADME studies were carried out to predict the safety and stability of the molecules. The increased GABA level in the experimental animals in the neurochemical estimation assay confirmed their GABAergic modulating activity. The most potent compounds were also evaluated for their neurotoxic and hepatotoxic effects. Fortunately, they did not show any sign of neurotoxicity or hepatotoxicity, suggesting that they have a broad spectrum of anticonvulsant activity with a large safety margin. Together, this research suggested that 4o and 4s may serve as leads in the discovery and development of new anticonvulsant drugs.
- Sahu, Meeta,Siddiqui, Nadeem,Naim, Mohd. Javed,Alam, Ozair,Yar, Mohammad Shahar,Sharma, Vidushi,Wakode, Sharad
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- Silver-catalyzed decarboxylative cross-coupling of α-keto acids with alkenes giving approach to chalcones
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A silver-catalyzed decarboxylative cross-coupling of α-keto acids with alkenes is reported. The method, with a wide range of substrate tolerance and mild operational conditions, can produce various chalcone derivatives in moderate to high yields from easily available starting materials.
- Wu, Shang,Yu, Hongheng,Hu, Qinzheng,Yang, Quanlu,Xu, Shouwang,Liu, Tian
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p. 4763 - 4765
(2017/12/01)
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- Domino-Fluorination-Protodefluorination Enables Decarboxylative Cross-Coupling of α-Oxocarboxylic Acids with Styrene via Photoredox Catalysis
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Domino-fluorination-protodefluorination decarboxylative cross-coupling of α-keto acids with styrene has been developed via photoredox catalysis. The critical part of this strategy is the formation of the carbon-fluorine (C-F) bond by the capture of a carbon-centered radical intermediate, which will overcome side reactions during the styrene radical functionalization process. Experimental studies have provided evidence indicating a domino-fluorination-protodefluorination pathway with α-keto acid initiating the photoredox cycle. The present catalytic protocol also affords a novel approach for the construction of α,β-unsaturated ketones under mild conditions.
- Zhang, Muliang,Xi, Junwei,Ruzi, Rehanguli,Li, Nan,Wu, Zhongkai,Li, Weipeng,Zhu, Chengjian
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p. 9305 - 9311
(2017/09/25)
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- Bifunctional Thiourea-Catalyzed Stereoablative Retro-Sulfa-Michael Reaction: Concise and Diastereoselective Access to Chiral 2,4-Diarylthietanes
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Owing to the chiral recognition capacity of bifunctional thioureas, a stereoablative retro-sulfa-Michael reaction has been developed. Utilization of a biphasic system enabled us to render the process catalytic. The usefulness of this methodology was further illustrated by the diastereoselective synthesis of all possible stereoisomers of 2,4-diarylthiethanes.
- Bacsó, András,Szigeti, Mariann,Varga, Szilárd,Soós, Tibor
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p. 429 - 439
(2016/12/24)
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- Iodine-Catalyzed Oxidative Aromatization: A Metal-Free Concise Approach to meta-Substituted Phenols from Cyclohex-2-enones
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A metal-free approach to meta-substituted phenols from cyclohex-2-enone via catalytic oxidative aromatization has been developed. The transformations are initiated with a catalytic amount of molecular iodine as the direct oxidant, while dimethyl sulfoxide is employed as the terminal oxidant. This practical approach is capable of avoiding the use of metal promoters and costly reagents, the lengthy synthesis, and overoxidation of products, and thus facilitates the efficient construction of meta-substituted phenol derivatives from inexpensive commercial chemicals under mild conditions. The synthetic utility of this approach is evident in the de novo syntheses of two bioactive molecules with good total yields, in which easily available chemicals were employed, protective groups were not utilized, and no unwanted carbon atoms were removed in each step. (Figure presented.).
- Wang, Shi-Ke,Chen, Ming-Tao,Zhao, Da-Yuan,You, Xia,Luo, Qun-Li
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p. 4093 - 4099
(2016/12/30)
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- Enantioselective Diels-Alder Reactions of Cyclohexa-1,3-diene and Chalcones Catalyzed by Intramolecular Silicon-Sulfur Lewis Pairs as Chiral Lewis Acids
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The stereoselective preparation of diastereomeric dihydrosilepine-derived silicon cations decorated with another binaphthyl unit at the silicon atom is described. A sulfide donor attached to that additional binaphthyl substituent forms an intramolecular Lewis pair with the electron-deficient silicon atom, as verified by 29Si NMR spectroscopy. Both chiral sulfur-stabilized silicon cations act as catalysts in the difficult Diels-Alder reaction of cyclohexa-1,3-diene and chalcone derivatives. Both Lewis acids induce enantioselectivity, but the S,S relative configuration is superior to the S,R configuration. With the former diastereomer, enantiomeric excesses of close to 60% are obtained. These values are the highest achieved to date in this seemingly trivial cycloaddition.
- Shaykhutdinova, Polina,Oestreich, Martin
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supporting information
p. 2768 - 2771
(2016/09/04)
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- Transition-Metal-Free Synthesis of Homo- and Hetero-1,2,4-Triaryl Benzenes by an Unexpected Base-Promoted Dearylative Pathway
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An unprecedented approach for the synthesis of homo- and hetero-1,2,4-triaryl benzenes has been developed using a simple base-mediated reaction of either α-aryl cinnamyl alcohols or α,γ-di-aryl propanones. The salient feature of this strategy involves the sequential hydride transfer, regiospecific condensation, regiospecific dearylation, and aromatization under metal-free reaction conditions. The synthesis of unsymmetrically substituted triphenylenes by oxidative coupling of the synthesized 1,2,4-triaryl benzenes has also been demonstrated.
- Rehan, Mohammad,Maity, Sanjay,Morya, Lalit Kumar,Pal, Kaushik,Ghorai, Prasanta
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supporting information
p. 7728 - 7732
(2016/07/07)
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- Phosphorous Acid Promoted Hydration-Condensation of Aromatic Alkynes with Aldehydes Affording Chalcones in an Oil/Water Two-Phase System
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A simple and environmentally benign method was developed for the synthesis of chalcones in high to excellent yields by a phosphorous acid promoted alkyne-aldehyde hydration-condensation in an oil/water two-phase system. The method is the first efficient protocol for the preparation of chalcones that is mediated by a simple Bronsted acid in a two-phase system.
- Zhou, Yongbo,Li, Zhongwen,Yang, Xiao,Chen, Xiulin,Li, Mei,Chen, Tieqiao,Yin, Shuang-Feng
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p. 231 - 237
(2016/01/12)
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- Barluenga's reagent with HBF4 as an efficient catalyst for alkyne-carbonyl metathesis of unactivated alkynes
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Barluenga's reagent (IPy2BF4, Py = pyridine) treated with HBF4 efficiently catalyzes the inter- and intramolecular alkyne-carbonyl metathesis of unactivated alkynes with aldehydes or ketones, most of which proceed at room temperature. This work represents the first catalytic application of the Barluenga's reagent.
- Murai, Kosuke,Tateishi, Keiichiro,Saito, Akio
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supporting information
p. 10352 - 10356
(2016/11/18)
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- Synthesis of chalcones via domino dehydrochlorination/Pd(OAc)2-catalyzed Heck reaction
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A new method has been developed for the cross-coupling of aryl halides with β-chloroalkyl aryl ketones and their ester and amide analogs through a domino dehydrochlorination/Pd(OAc)2- catalyzed Heck reaction sequence. The enone intermediates generated in situ reduced the occurrence of side reactions and therefore enhanced the efficiency of the reaction. This reaction exhibited good tolerance to various functional groups on both substrates and provides rapid access to a wide range of chalcone derivatives.
- Guo, Tenglong,Jiang, Quanbin,Yu, Likun,Yu, Zhengkun
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- Iron-facilitated oxidative radical decarboxylative cross-coupling between α-oxocarboxylic acids and acrylic acids: An approach to α,β-unsaturated carbonyls
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The first Fe-facilitated decarboxylative cross-coupling reaction between α-oxocarboxylic acids and acrylic acids in aqueous solution has been developed. This transformation is characterized by its wide substrate scope and good functional group compatibility utilizing inexpensive and easily accessible reagents, thus providing an efficient and expeditious approach to an important class of α,β-unsaturated carbonyls frequently found in bioactive compounds. The synthetic potential of the coupled products is also demonstrated in subsequent functionalization reactions. Preliminary mechanism studies suggest that a free radical pathway is involved in this process: the generation of an acyl radical from α-oxocarboxylic acid via the excision of carbon dioxide followed by the addition of an acyl radical to the α-position of the double bond in acrylic acid then delivers the α,β-unsaturated carbonyl adduct through the extrusion of another carbon dioxide.
- Jiang, Qing,Jia, Jing,Xu, Bin,Zhao, An,Guo, Can-Cheng
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p. 3586 - 3596
(2015/04/22)
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- Organoselenium-catalyzed baeyer-villiger oxidation of α,β-unsaturated ketones by hydrogen peroxide to access vinyl esters
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By carefully screening the organoselenium pre-catalysts and optimizing the reaction conditions, simple dibenzyl diselenide was found to be the best pre-catalyst for Baeyer-Villiger oxidation of (E)-α,β-unsaturated ketones with the green oxidant hydrogen peroxide at room temperature. The organoselenium catalyst used in this reaction could be recycled and reused several times. This new method was suitable not only for methyl unsaturated ketones, but also for alkyl and aryl unsaturated ketones. Therefore, it provided a direct, mild, practical, highly functional group-tolerant process for the chemoselective preparation of the versatile (E)-vinyl esters from the readily available (E)-α,β-unsaturated ketones. A possible mechanism was also proposed to rationalize the activity of the organoselenium catalyst in the presence of hydrogen peroxide in this Baeyer-Villiger oxidation reaction.
- Zhang, Xu,Ye, Jianqing,Yu, Lei,Shi, Xinkang,Zhang, Ming,Xu, Qing,Lautens, Mark
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supporting information
p. 955 - 960
(2015/03/30)
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- Transition-Metal-Free Self-Hydrogen-Transferring Allylic Isomerization
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Phenanthroline and tert-butoxide have been established as powerful radical initiators in reactions such as the SRN1-type coupling reactions due to the cooperation of large heteroarenes and a special feature of tert-butoxide. The first phenanthroline-tert-butoxide-catalyzed transition-metal-free allylic isomerization is described. The resulting ketones are key intermediates for indenes. The control experiments rule out the base-promoted allylic anion pathway. The radical pathway is supported by experimental evidence that includes kinetic study, kinetic isotope effect, isotope-labeling experiments, trapping experiments, and EPR experiments.
- Zheng, Hong-Xing,Xiao, Zu-Feng,Yao, Chuan-Zhi,Li, Qiang-Qiang,Ning, Xiao-Shan,Kang, Yan-Biao,Tang, Yong
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supporting information
p. 6102 - 6105
(2016/01/09)
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- Palladium-catalyzed acylative cross-coupling of amides with diarylborinic acids and sodium tetraarylborates
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Abstract A general and efficient acylative Suzuki coupling of active amides with diarylborinic acids has been achieved by using 1 mol% Pd(PCy3)2Cl2/0.6 mol% PCy3 as catalyst system taking advantage of modifiable reactivities of acyl-nitrogen bonds of amides. Both electronic and steric influences from either aryl or acyl counterparts on the coupling proved to be negligible or small. A variety of aryl ketones including sterically hindered ones could be synthesized by the coupling of diarylborinic acids in good to excellent yields. Sodium tetraarylborates could also be used as high atom-economy aryl source in the palladium-catalyzed cross-coupling with active amides.
- Li, Xijing,Zou, Gang
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p. 136 - 145
(2015/07/27)
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- Gold(I)-catalyzed decarboxylation of propargyl carbonates: Reactivity reversal of the gold catalyst from π-Lewis acidity to σ-Lewis acidity
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A cationic gold(I)-catalyzed decarboxylative etherification of propargyl carbonates to selectively produce propargyl ethers is reported. In the reaction the gold(I) catalyst shows a distinct σ-Lewis acidity rather than the commonly observed π-Lewis acidity, and thus catalyzes the decarboxylation of a variety of propargyl carbonates to give the corresponding propargyl ethers with high selectivity. This reaction represents a rare example of the tunable reactivity of cationic gold(I) complexes between σ-Lewis acidity and π-Lewis acidity.
- Shen, Ruwei,Yang, Jianjun,Zhu, Shugao,Chen, Chao,Wu, Luling
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p. 1259 - 1269
(2015/04/22)
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- Montmorillonite clay-promoted, solvent-free cross-aldol condensations under focused microwave irradiation
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An environmentally benign, clean and general protocol was developed for the synthesis of aryl and heteroaryl trans-chalcones. This method involved solvent-free reaction conditions under microwave irradiation in the presence of a clay-based catalyst, and afforded the target compounds in good yields and short reaction times. Furthermore, the same conditions allowed the synthesis of symmetrical, diarylmethylene-a,a-unsaturated ketones from aromatic aldehydes and ketones.
- Rocchi, Damiano,Gonzalez, Juan F.,Menendez, J. Carlos
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supporting information
p. 7317 - 7326
(2014/07/08)
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- Asymmetric epoxidation of unsaturated ketones catalyzed by heterobimetallic rare earth-lithium complexes bearing phenoxy-functionalized chiral diphenylprolinolate ligand
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Four novel heterobimetallic complexes [REL2]{[(THF)3Li]2(μ-Cl)} stabilized by chiral phenoxy-functionalized prolinolate (RE = Yb (1), Y (2), Sm (3), Nd (4), H2L = (S)-2,4-di-tert-butyl-6-[[2-(hydroxydiphenylmethyl)pyrrolidin-1-yl]methyl]phenol have been synthesized and characterized. These readily available complexes are highly active in catalyzing the epoxidation of α,β-unsaturated ketones, while the enantioselectivity varies according to the ionic radii of the rare earth center. A series of chalcone derivatives were converted to chiral epoxides in 80 → 99% ee at 0 °C using TBHP as the oxidant in the presence of 10 mol % of 1.
- Qian, Qinqin,Tan, Yufang,Zhao, Bei,Feng, Tao,Shen, Qi,Yao, Yingming
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supporting information
p. 4516 - 4519
(2015/01/16)
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- Copper-catalyzed oxidative transformation of secondary alcohols to 1,5-disubstituted tetrazoles
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A mild and convenient oxidative transformation of secondary alcohols to 1,5-disubstituted tetrazoles is uncovered by employing trimethylsilyl azide (TMSN3) as a nitrogen source in the presence of a catalytic amount of copper(II) perchlorate hexahydrate [Cu(ClO4)2 .6 H2O] (5 mol%) and 2,3-dichloro-5,6-dicyano-para- benzoquinone (DDQ) (1.2 equiv.) as an oxidant. This reaction is performed under ambient conditions and proceeds through C-C bond cleavage.
- Rokade, Balaji V.,Gadde, Karthik,Prabhu, Kandikere Ramaiah
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supporting information
p. 946 - 950
(2014/04/03)
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- Evaluation of silica-H2SO4 as an efficient heterogeneous catalyst for the synthesis of chalcones
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We report an efficient silica-H2SO4 mediated synthesis of a variety of chalcones that afforded the targeted compounds in very good yield compared to base catalyzed solvent free conditions as well as acid or base catalyzed refluxing conditions.
- Sultan, Aeysha,Raza, Abdul Rauf,Abbas, Muhammad,Khan, Khalid Mohammed,Tahir, Muhammad Nawaz,Saari, Nazamid
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p. 10081 - 10094
(2013/09/23)
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- Effects of structural and electronic characteristics of chalcones on the activation of peroxisome proliferator-activated receptor gamma
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Chalcones share some structural similarities with GW-1929, a highly-selective and potent agonist for peroxisome proliferator-activated receptor-gamma (PPARγ). In this study, we tested 53 structurally diverse chalcones to identify characteristics essential for PPARγ activation in a GAL4-based transactivation assay. This screen identified several novel chalcone agonists of PPARγ. Our results indicate that chalcones with an electron rich group or sterically large groups such as naphthyl on the carbonyl side tend to activate PPARγ. The absence of any strict structural or electronic requirements suggests that the flexibility of the PPARγ ligand binding pocket may allow binding of diverse chalcones with some preference for a slightly larger electron-rich group on the carbonyl side. We predict that further structure-activity relationship studies on chalcones with naphthalene or electron-rich groups near the carbonyl moiety will lead to the development of more potent PPARγ agonists.
- Schott, Jason Taylor,Mordaunt, Charles Edward,Vargas, Anthony Joseph,Leon, Martin Antonio,Chen, Kevin Hsinwen,Singh, Mandeep,Satoh, Mikiko,Cardenas, Emilio Leal,Maitra, Santanu,Patel, Nilay Vinod,De Lijser, Hubrecht Johan Peter
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p. 229 - 236
(2013/03/14)
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- A facile microwave-assisted "one-Pot" synthesis of piperazino pyrimidinyl acetamides, a class of hybrid bis heterocycles and their structural elucidation using NMR spectral techniques
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An array of novel piperazino pyrimidinyl acetamides, a class of hybrid bis heterocycles are synthesized in "one-pot" by microwave irradiation method catalyzed by heterogeneous NaHSO4.SiO2 catalyst in dry media and are characterized by melting point, elemental analysis, MS, FT-IR, one-dimensional NMR (1H and 13C) and two-dimensional 1H-1H COSY and 1H-13C HSQC spectral data.
- Kanagarajan,How, Ghee Ang,Siu, Choon Ng,Gopalakrishnan
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p. 396 - 402
(2013/05/23)
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- Syntheses and biological activity of chalcones-imidazole derivatives
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A number of novel 13-membered chalcone-imidazole derivatives were prepared and have been synthesized and characterized by IR, 1H NMR, 13C NMR and elemental analysis, the results conformed well to expected structures. Substituted acetophenones and benzaldehydes were condensed using the Claisen-Schmidt base-catalyzed aldol condensation. Methyl on the aromatic ring of chalcones was brominated by NBS, and then the resulting mixture was reacted with imidazole to get the target compound. Several chalcones showed in vitro antibacterial activity against Gram-bacterial. The results showed that these are potential antibacterial compounds.
- Liu, Yu-Ting,Sun, Xiao-Ming,Yin, Da-Wei,Yuan, Fang
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p. 1037 - 1048
(2013/06/04)
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- Palladium-catalyzed conjugate addition of arylsulfonyl hydrazides to α,β-unsaturated ketones
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A palladium-catalyzed desulfitative-denitrogenative conjugate addition of arylsulfonyl hydrazides to α,β-unsaturated ketones is described. The reaction showed very good selectivity and tolerated a wide range of functionalities under an atmosphere of oxygen with or without the aid of a metal co-oxidant. The Royal Society of Chemistry 2013.
- Chen, Wen,Chen, Hui,Xiao, Fuhong,Deng, Guo-Jun
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supporting information
p. 4295 - 4298
(2013/08/23)
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- Copper-catalyzed oxidative coupling of alkenes with aldehydes: Direct access to α,β-unsaturated ketones
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Let's get radical: The first copper-catalyzed oxidative coupling of alkenes and aldehydes was developed. Various aldehydes were utilized as substrates to construct α,β-unsaturated ketones. A preliminary mechanistic study indicated that this reaction is likely to proceed through a single-electron transfer. Copyright
- Wang, Jing,Liu, Chao,Yuan, Jiwen,Lei, Aiwen
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supporting information
p. 2256 - 2259
(2013/04/10)
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- Tin(II) chloride mediated coupling reactions between alkynes and aldehydes
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Tin(II) chloride, which is insensitive to water and air, mediated the coupling reaction between alkynes and aldehydes as a Lewis acid in nitromethane to produce (E)-α,β-unsaturated ketones by a skeletal transformation in which one alkynic carbon atom changed into an oxo carbon atom accompanied by the cleavage of a C=O bond in the starting aldehydes. This coupling reaction was promoted by a catalytic amount of a primary or secondary alkanol. The coupling reaction between 1-deuterio-2-phenylethyne and benzaldehyde with BuOH afforded 1,3-diphenyl-2-deuterio-2-propenone (2-deuteriation: 94 % D), whereas the coupling reaction between phenylethyne and benzaldehyde with BuOD afforded 1,3-diphenyl-2-propenone (2-deuteriation: 0 % D). Because almost no exchange between hydrogen and deuterium at the 2-position of 1,3-diphenyl-2-propenone occurs in either of the reactions, the coupling reaction between alkynes and aldehydes with tin(II) chloride is presumed to proceed by nucleophilic addition of alkynes to aldehydes. The cleavage of the C-O single bond generated by the nucleophilic addition might be induced by the strong oxophilicity of tin. Coupling reactions occur between alkynes and aldehydes mediated by tin(II) chloride as a Lewis acid to produce (E)-α,β-unsaturated ketones by a skeletal transformation in which an alkynic carbon atom changes into an oxo carbon atom accompanied by cleavage of the C=O bond in the starting aldehydes. This coupling reaction is promoted by a catalytic amount of a primary or secondary alkanol. Copyright
- Masuyama, Yoshiro,Takamura, Wataru,Suzuki, Noriyuki
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p. 8033 - 8038
(2014/01/06)
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- Palladium-catalyzed and copper-mediated cross-coupling reaction of aryl- or alkenylboronic acids with acid chlorides under neutral conditions: Efficient synthetic methods for diaryl ketones and chalcones at room temperature
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Palladium-catalyzed cross-coupling reaction of aryl- or alkenylboronic acids with acid chlorides in the presence of copper(I) thiophene-2-carboxylate (CuTC) as an activator in diethyl ether at room temperature under strictly non-basic conditions affords the diaryl ketones or chalcones in moderate to excellent yields. A wide range of substrates bearing an electron-donating or an electron-withdrawing substituent on the aromatic ring are compatible.
- Ogawa, Daisuke,Hyodo, Keita,Suetsugu, Masato,Li, Jing,Inoue, Yoshiaki,Fujisawa, Mamoru,Iwasaki, Masayuki,Takagi, Kentaro,Nishihara, Yasushi
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p. 2565 - 2571
(2013/03/28)
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