- Oxidative esterification of alcohols by a single-side organically decorated Anderson-type chrome-based catalyst
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The direct esterification of alcohols with non-noble metal-based catalytic systems faces great challenges. Here, we report a new chrome-based catalyst stabilized by a single pentaerythritol decorated Anderson-type polyoxometalate, [N(C4H9)4]3[CrMo6O18(OH)3C{(OCH2)3CH2OH}], which can realize the efficient transformation from alcohols to esters by H2O2oxidation in good yields and high selectivity without extra organic ligands. A variety of alcohols with different functionalities including some natural products and pharmaceutical intermediates are tolerated in this system. The chrome-based catalyst can be recycled several times and still keep the original configuration and catalytic activity. We also propose a reasonable catalytic mechanism and prove the potential for industrial applications.
- Wang, Jingjing,Jiang, Feng,Tao, Chaofu,Yu, Han,Ruhlmann, Laurent,Wei, Yongge
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supporting information
p. 2652 - 2657
(2021/04/21)
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- Enantioselective Synthesis of Pyroglutamic Acid Esters from Glycinate via Carbonyl Catalysis
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Direct α-functionalization of NH2-free glycinates with relatively weak electrophiles such as α,β-unsaturated esters still remains a big challenge in organic synthesis. With chiral pyridoxal 5 d as a carbonyl catalyst, direct asymmetric conjugated addition at the α-C of glycinate 1 a with α,β-unsaturated esters 2 has been successfully realized, to produce various chiral pyroglutamic acid esters 4 in 14–96 % yields with 81–97 % ee's after in situ lactamization. The trans and cis diastereomers can be obtained at the same time by chromatography and both of them can be easily converted into chiral 4-substituted pyrrolidin-2-ones such as Alzheimer's drug Rolipram (11) with the same absolute configuration via tert-butyl group removal and subsequent Barton decarboxylation.
- Ma, Jiguo,Zhou, Qinghai,Song, Guanshui,Song, Yongchang,Zhao, Guoqing,Ding, Kuiling,Zhao, Baoguo
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supporting information
p. 10588 - 10592
(2021/04/06)
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- In situ synthesis of carbon nanotube-encapsulated cobalt nanoparticles by a novel and simple chemical treatment process: Efficient and green catalysts for the Heck reaction
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In this study, we present a novel, fast and easy method for supporting metal nanoparticles onto the internal surface of multi-walled CNTs; these CNT-encapsulated nanoparticles as heterogeneous, efficient, inexpensive and green catalysts promote the Heck cross-coupling of a large library of functional substrates under mild and sustainable conditions. Remarkably, the introduced catalytic system could be reused for at least nine successive runs without a discernible decrease in its catalytic activity.
- Hajipour, Abdol R.,Khorsandi, Zahra,Farrokhpour, Hossein
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supporting information
p. 8215 - 8219
(2019/06/07)
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- Fabrication of Pd/CuFe2O4 hybrid nanowires: A heterogeneous catalyst for Heck couplings
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The development of environmentally benign transformations is indispensable in organic synthesis. Herein, a hybrid heterogeneous catalyst, palladium(0) on copper ferrite nanowires, has been synthesized, characterized, and for the first time, employed in the Jeffrey Heck reaction between iodoarenes and allylic alcohols, and good to excellent yields have been obtained. In addition, the catalyst was found to be suitable for the usual Heck coupling. The nanocatalyst was recovered and reused up-to multiple runs without any noticeable loss of its catalytic activity.
- Lakshminarayana,Mahendar,Ghosal,Sreedhar,Satyanarayana,Subrahmanyam, Ch.
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p. 1646 - 1654
(2018/02/09)
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- Diastereoselective Synthesis of Highly Substituted, Amino- and Pyrrolidino-Tetrahydrofurans as Lead-Like Molecular Scaffolds
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A series of highly substituted tetrahydrofurans (THFs), decorated with modifiable 2-aryl, 3-carboxy and 4-amino substituents, has been prepared for biological evaluation within the European Lead Factory. Diastereoselective reductive amination of pre-functionalised 4-oxofurans, readily prepared from cinnamate esters via oxa-Michael/Dieckmann annulation, provided the requisite THF cores on gram scale with three contiguous stereocentres, including full substitution at C-3. In a second series, a pyrrolidine ring was fused to the same oxofuran scaffold via an intramolecular reductive amination, inverting the configuration at C-4 relative to the other ring substituents. The resulting compounds, which displayed desirable physical properties as lead-like scaffolds, were derivatised into a small library of 24 compounds, demonstrating their ability to serve as starting points for drug discovery. Ultimately, this chemistry enabled the preparation of 1948 THF-containing compounds for inclusion in the Joint European Compound Library.
- Wales, Steven M.,Merisor, Elena G.,Adcock, Holly V.,Pearce, Christopher A.,Strutt, Ian R.,Lewis, William,Hamza, Daniel,Moody, Christopher J.
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supporting information
p. 8233 - 8239
(2018/06/15)
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- Ligand-Free C–C Coupling Reactions Promoted by Hexagonal Boron Nitride-Supported Palladium(II) Catalyst in Water
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A micron-scale palladium(II) material has been successfully prepared using Schiff base-modified hexagonal boron nitride as a support and used for the first time as an efficient and recyclable catalyst in organic synthesis. The morphology, composition, metal loading and thermal stability of the catalyst were studied using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), infrared spectroscopy (FT-IR), inductively coupled plasma (ICP) and thermogravimetric (TG) analyses. Then, the micron material was tested in various C–C cross-coupling reactions and exhibited excellent catalytic activities in the Suzuki and Heck reactions. Moreover, the catalyst could be easily recovered by simple filtration and reused at least ten times without significant loss of its catalytic activity. In general, this work demonstrates the possibility of using Schiff-base@hexagonal boron nitride as an efficient support for heterogeneous catalysts. (Figure presented.).
- Cheng, Xu,Li, Weijian,Nie, Ruifang,Ma, Xiaojun,Sang, Rui,Guo, Li,Wu, Yong
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supporting information
p. 454 - 466
(2017/02/10)
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- Novel cyclodextrin-modified h-BN@Pd(II) nanomaterial: An efficient and recoverable catalyst for ligand-free C-C cross-coupling reactions in water
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An environmentally friendly palladium(II) catalyst supported on cyclodextrin-modified h-BN was successfully prepared. The catalyst was characterized by FT-IR, SEM, TG, XRD and XPS, and the loading level of Pd in h-BN@β-CD@Pd(II) was measured to be 0.088?mmol g?1 by ICP. It exhibits excellent catalytic activity for the Suzuki and Heck reactions in water, and can be easily separated and consecutively reused for at least nine times. In addition, a series of pharmacologically interesting products were successfully synthesized using this catalyst to demonstrate its potential applications in pharmaceutical industries. Above all, this work opens up an interesting and attractive avenue for the use of cyclodextrin-functionalized h-BN as an efficient support for hydrophilic heterogeneous catalysts.
- Ma, Xiaojun,Lv, Guanghui,Cheng, Xu,Li, Weijian,Sang, Rui,Zhang, Yong,Wang, Qiantao,Hai, Li,Wu, Yong
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- Palladium nanoparticles immobilized on amphiphilic and hyperbranched polymer-functionalized magnetic nanoparticles: An efficient semi-heterogeneous catalyst for Heck reaction
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To address the obstacles facing the use of palladium-based homogeneous and heterogeneous catalysts in C─C cross-coupling reactions, a novel semi-heterogeneous support was developed based on hyperbranched poly(ethylene glycol)-block-poly(citric acid)-functionalized Fe3O4 magnetic nanoparticles (Fe3O4@PCA-b-PEG). Because of the surface modification of the Fe3O4 nanoparticles with amphiphilic and hyperbranched polymers (PCA-b-PEG), these hybrid materials are not only soluble in a wide range of solvents (e.g. water, ethanol and dimethylformamide) but also are able to trap Pd2+ ions via complex formation of free carboxyl groups of the PCA dendrimer with metal ions. The reduction of trapped palladium ions in the dendritic shell of Fe3O4@PCA-b-PEG leads to immobilized palladium nanoparticles. The morphology and structural features of the catalyst were characterized using various microscopic and spectroscopic techniques. The catalyst was effectively used in the palladium-catalysed Mizoroki–Heck coupling reaction in water as a green solvent. In addition, the catalyst can be easily recovered from the reaction mixture by applying an external magnetic field and reused for more than ten consecutive cycles without much loss in activity, exhibiting an example of a sustainable and green methodology.
- Tabatabaei Rezaei, Seyed Jamal,Shamseddin, Azin,Ramazani, Ali,Mashhadi Malekzadeh, Asemeh,Azimzadeh Asiabi, Pegah
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- Palladium(II)-Schiff base complex immobilized covalently on h-BN: An efficient and recyclable catalyst for aqueous organic transformations
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A moisture- and air-stable palladium(II)-Schiff base complex supported on h-BN was simply prepared by using commercially available reagents. This nanomaterial was applied as an excellent and recyclable heterogeneous catalyst for the Suzuki and Heck cross-coupling reactions. And it has been characterized by FT-IR, XRD, SEM, XPS, TG and ICP-AES techniques. High yields, ligand-free, low reaction time, water as solvent, non-toxicity and recyclability of the catalyst are the main merits of these protocols. In addition, a series of pharmacologically relevant products were successfully synthesized using this catalyst. Above all, this work opens up an interesting and attractive avenue for the use of h-BN as an efficient support for heterogeneous catalysts.
- Li, Weijian,Lv, Guanghui,Cheng, Xu,Sang, Rui,Ma, Xiaojun,Zhang, Yong,Nie, Ruifang,Li, Jie,Guan, Mei,Wu, Yong
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supporting information
p. 8557 - 8564
(2016/12/07)
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- Magnetic iron oxide nanoparticles–N-heterocyclic carbene–palladium(II): a new, efficient and robust recyclable catalyst for Mizoroki–Heck and Suzuki–Miyaura coupling reactions
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A new and efficient nanoparticle–N-heterocyclic carbene–palladium complex was synthesized and characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, field emission scanning electron microscopy, energy-dispersive X-ray analysis, X-ray diffraction, transmission electron microscopy, elemental analysis, inductively coupled plasma analysis and vibrating sample magnetometry. This catalytic system was found to be a highly active catalyst in the Mizoroki–Heck and Suzuki–Miyaura cross-coupling reactions. These reactions were best performed in dimethylformamide and water, respectively, in the presence of only 0.054 mol% of palladium under mild conditions. Moreover, the catalyst could be recovered easily and reused at least ten times without any considerable loss of its catalytic activity. Copyright
- Hajipour, Abdol R.,Tadayoni, Nayereh S.,Khorsandi, Zahra
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p. 590 - 595
(2016/07/16)
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- Catalytic asymmetric bromochlorination of aromatic allylic alcohols promoted by multifunctional Schiff base ligands
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It was found that the tridentate O,N,O-type Schiff base ligand bearing suitable substituents was a highly effective promoter in the catalytic asymmetric bromochlorination reaction, in which the corresponding aromatic bromochloroalcohols with vicinal halogen-bearing stereocenters were formed with perfect regioselectivity, with moderate to excellent enantioselectivities (up to 93% ee), and with good yields and chemoselectivities.
- Huang, Wei-Sheng,Chen, Li,Zheng, Zhan-Jiang,Yang, Ke-Fang,Xu, Zheng,Cui, Yu-Ming,Xu, Li-Wen
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supporting information
p. 7927 - 7932
(2016/08/30)
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- Cross-Linked Thiazolidine Network as Support for Palladium: A New Catalyst for Suzuki and Heck Reactions
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A thiazolidine-based material was used for the first time as support for palladium. The support was prepared by starting from a highly cross-linked thiazolium-based material, obtained by radical oligomerization of a bisvinylthiazolium dibromide salt in the presence of 3-mercaptopropyl-modified silica SBA-15. Palladium was immobilized by treatment with tetrachloropalladate salt. Reduction with sodium borohydride afforded a thiazolidine-based material that acted as ligands for the Pd species. The thiazolidine-based palladium catalyst was fully characterized and, working in only 0.1 mol% amount, displayed good activity in the Suzuki-Miyaura and in the Heck reactions. Several biphenyl and alkene compounds could be prepared in high yields. The catalytic material proved to be fully recoverable and it was representatively used for three times in the Suzuki-Miyaura reaction without showing any decrease in its activity.
- Bivona, Lucia Anna,Giacalone, Francesco,Vaccaro, Luigi,Aprile, Carmela,Gruttadauria, Michelangelo
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p. 2526 - 2533
(2015/08/24)
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- A straight forward synthesis of 4-aryl substituted 2-quinolones via Heck reaction
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A variety of aryl halides have been successfully coupled with different olefins via Heck reaction in the presence of an active stimulant (Pd-NHC). An efficient one pot protocol for the easy access of structurally diverse 4-aryl-2-quinolones via domino Heck/cyclization reaction has been developed. This journal is
- Gupta, Sumanta,Ganguly, Bhaskar,Das, Sajal
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p. 41148 - 41151
(2015/02/05)
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- A robust first-pass protocol for the heck-mizoroki reaction
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The Heck-Mizoroki (HM) reaction is one of the most widely used C-C bond-forming methods of contemporary synthesis. Notwithstanding this, these reactions frequently require significant optimization before efficient transformations can be obtained. We describe here the results of a study that aimed to establish a generic experimental protocol for HM reactions which enables acceptable yields from first-pass experiments. The methodology utilizes readily available stable catalysts and can be applied to a broad range of coupling partners.
- Murray, Paul M.,Bower, John F,Cox, David K,Galbraith, Ewan K,Parker, Jeremy S,Sweeney, Joseph B.
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p. 397 - 405
(2013/04/24)
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