- Nickel-Catalyzed Electrochemical C(sp3)?C(sp2) Cross-Coupling Reactions of Benzyl Trifluoroborate and Organic Halides**
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Reported here is the redox neutral electrochemical C(sp2)?C(sp3) cross-coupling reaction of bench-stable aryl halides or β-bromostyrene (electrophiles) and benzylic trifluoroborates (nucleophiles) using nonprecious, bench-stable NiCl2?glyme/polypyridine catalysts in an undivided cell configuration under ambient conditions. The broad reaction scope and good yields of the Ni-catalyzed electrochemical coupling reactions were confirmed by 50 examples of aryl/β-styrenyl chloride/bromide and benzylic trifluoroborates. Potential applications were demonstrated by electrosynthesis and late-stage functionalization of pharmaceuticals and natural amino acid modification, and three reactions were run on gram-scale in a flow-cell electrolyzer. The electrochemical C?C cross-coupling reactions proceed through an unconventional radical transmetalation mechanism. This method is highly productive and expected to find wide-spread applications in organic synthesis.
- Luo, Jian,Hu, Bo,Wu, Wenda,Hu, Maowei,Liu, T. Leo
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p. 6107 - 6116
(2021/02/01)
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- Nitrenium Salts in Lewis Acid Catalysis
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Molecular compounds featuring nitrogen atoms are typically regarded as Lewis bases and are extensively employed as donor ligands in coordination chemistry or as nucleophiles in organic chemistry. By contrast, electrophilic nitrogen-containing compounds are much rarer. Nitrenium cations are a new family of nitrogen-based Lewis acids, the reactivity of which remains largely unexplored. In this work, nitrenium ions are explored as catalysts in five organic transformations. These reactions are the first examples of Lewis acid catalysis employing nitrogen as the site of substrate activation. Moreover, these compounds are readily accessed from commercially available reagents and exhibit remarkable stability toward moisture, allowing for benchtop transformations without the need to pretreat solvents.
- Mehta, Meera,Goicoechea, Jose M.
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supporting information
p. 2715 - 2719
(2020/01/24)
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- Alumina grafted SBA-15 sustainable bifunctional catalysts for direct cross-coupling of benzylic alcohols to diarylmethanes
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AlSBA-15 catalysts possessing Br?nsted acid and Lewis acid-base bifunctionalities catalyze the direct arylation of benzyl alcohols to diarylmethanes with an 85% product yield through C-O bond activation. 2 and 4wt%AlSBA-15 catalysts have been synthesised by adopting a simple and efficient post-synthetic metal implantation route. The synthesised catalysts were characterized using XRD, N2 adsorption and desorption, 27Al MAS NMR, XPS, HR-TEM, NH3 and CO2-temperature-programmed desorption (TPD) and pyridine-transmission-FTIR spectroscopy techniques to confirm the existence of Br?nsted acid and Lewis acid-base bifunctionalities. Through various control experiments, it is verified that Br?nsted acid sites activate the benzyl alcohol and Lewis base sites interact with phenylboronic acid concurrently to accomplish the coupling reaction. In the recyclability study, 4wt%AlSBA-15 preserves its activity and stability up to 5 cycles. The 4wt%AlSBA-15 catalyst unlike homogeneous catalysts does not require additives, long reaction time and expensive metals.
- Rajendran, Chandran,Satishkumar, Govindaswamy,Lang, Charlotte,Gaigneaux, Eric M.
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p. 2583 - 2592
(2020/05/14)
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- Potassium trimethylsilanolate enables rapid, homogeneous suzuki-miyaura cross-coupling of boronic esters
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Herein, a mild and operationally simple method for the Suzuki-Miyaura cross-coupling of boronic esters is described. Central to this advance is the use of the organic-soluble base, potassium trimethylsilanolate, which allows for a homogeneous, anhydrous cross-coupling. The coupling proceeds at a rapid rate, often furnishing products in quantitative yield in less than 5 min. By applying this method, a >10-fold decrease in reaction time was observed for three published reactions which required >48 h to reach satisfactory conversion.
- Delaney, Connor P.,Kassel, Vincent M.,Denmark, Scott E.
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- Combined Photoredox/Enzymatic C?H Benzylic Hydroxylations
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Chemical transformations that install heteroatoms into C?H bonds are of significant interest because they streamline the construction of value-added small molecules. Direct C?H oxyfunctionalization, or the one step conversion of a C?H bond to a C?O bond, could be a highly enabling transformation due to the prevalence of the resulting enantioenriched alcohols in pharmaceuticals and natural products,. Here we report a single-flask photoredox/enzymatic process for direct C?H hydroxylation that proceeds with broad reactivity, chemoselectivity and enantioselectivity. This unified strategy advances general photoredox and enzymatic catalysis synergy and enables chemoenzymatic processes for powerful and selective oxidative transformations.
- Betori, Rick C.,May, Catherine M.,Scheidt, Karl A.
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supporting information
p. 16490 - 16494
(2019/11/03)
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- A SO2F2 mediated mild, practical, and gram-scale dehydroxylative transforming primary alcohols to quaternary ammonium salts
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A simple, practical and gram-scale process for direct transformation of primary alcohols or silyl ethers to ammonium salts was developed. This method has the feathers of easy work-up (a simple filtration), mild condition, high yield, great practicality and robustness. And the application of the ammonium salts in Suzuki coupling reaction was also accomplished.
- Zhao, Chuang,Zha, Gao-Feng,Fang, Wan-Yin,Alharbi, Njud S.,Qin, Hua-Li
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p. 4648 - 4656
(2019/07/12)
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- Construction of Di(hetero)arylmethanes Through Pd-Catalyzed Direct Dehydroxylative Cross-Coupling of Benzylic Alcohols and Aryl Boronic Acids Mediated by Sulfuryl Fluoride (SO2F2)
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A practical Pd-catalyzed direct dehydroxylative coupling of (hetero)benzylic alcohols with (hetero)arylboronic acids for the constructions of di(hetero)arylmethane derivatives under SO2F2 was described. This new method provided a strategically distinct approach to di(hetero)arylmethane derivatives from readily available and abundant benzylic alcohols under mild condition.
- Zhao, Chuang,Zha, Gao-Feng,Fang, Wan-Yin,Rakesh,Qin, Hua-Li
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p. 1801 - 1807
(2019/02/07)
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- Super electron donor-mediated reductive desulfurization reactions
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The desulfurization of thioacetals and thioethers by a pyridine-derived electron donor is described. This methodology provides efficient access to the reduced products in high yields and does not require the use of transition-metals, elemental alkali-metals, or hydrogen atom donors.
- Nozawa-Kumada, Kanako,Ito, Shungo,Noguchi, Koto,Shigeno, Masanori,Kondo, Yoshinori
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supporting information
p. 12968 - 12971
(2019/11/05)
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- Phosphonic acid mediated practical dehalogenation and benzylation with benzyl halides
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For the first time, by using H3PO3/I2 system, various benzyl chlorides, bromides and iodides were dehalogenated successfully. In the presence of H3PO3, benzyl halides underwent electrophilic substitution reactions with electron-rich arenes, leading to a broad range of diarylmethanes in good yields. These transformations feature green, cheap reducing reagents and metal-free conditions. A possible mechanism was proposed.
- Gao, Jing,Han, Li-Biao,Ma, Yonghao,Tang, Zilong,Wu, Xiaofang,Xiao, Jing
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p. 22343 - 22347
(2019/07/31)
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- Palladium-Catalyzed Hiyama Coupling of Benzylic Ammonium Salts via C-N Bond Cleavage
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The first palladium-catalyzed Hiyama cross-coupling of arylsilanes with benzyltrimethylammonium salts is reported. The reaction proceeds smoothly to facilitate C(sp2)-C(sp3) bond formation via cleavage of the C-N bond and provides a useful approach to various diarylmethanes with a broad substrate scope and excellent functional group tolerance in good to excellent yields.
- Han, Chunyu,Zhang, Zhenming,Xu, Silin,Wang, Kai,Chen, Kaiting,Zhao, Junfeng
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p. 16308 - 16313
(2019/12/25)
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- The Dual Role of Benzophenone in Visible-Light/Nickel Photoredox-Catalyzed C?H Arylations: Hydrogen-Atom Transfer and Energy Transfer
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A dual catalytic protocol for the direct arylation of non-activated C(sp3)?H bonds has been developed. Upon photochemical excitation, the excited triplet state of a diaryl ketone photosensitizer abstracts a hydrogen atom from an aliphatic C?H bond. This inherent reactivity was exploited for the generation of benzylic radicals which subsequently enter a nickel catalytic cycle, accomplishing the benzylic arylation.
- Dewanji, Abhishek,Krach, Patricia E.,Rueping, Magnus
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supporting information
p. 3566 - 3570
(2019/02/26)
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- Cross coupling of benzylammonium salts with boronic acids using a well-defined N-heterocyclic carbene-palladium(ii) precatalyst
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N-heterocyclic carbene-palladium(ii)-catalyzed cross-coupling of benzylammonium salts with arylboronic acids for the synthesis of diarylmethane derivatives via C-N bond activation has been developed. Notably, in the presence of the easily prepared and bench-stable Pd-PEPPSI precatalyst, the Csp3-N bond activation of the benzylammonium salt even proceeded smoothly in isopropanol at room temperature.
- Wang, Tao,Guo, Jiarui,Wang, Xiaojuan,Guo, Han,Jia, Dingli,Wang, Hengjin,Liu, Lantao
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p. 5738 - 5741
(2019/03/02)
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- Bisulfate Salt-Catalyzed Friedel-Crafts Benzylation of Arenes with Benzylic Alcohols
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We report here a method of direct Friedel-Crafts benzylation of arenes with benzylic alcohols using cheap and readily available bisulfate salt as the catalyst in hexafluoroisopropanol. The catalytic system is powerful with a quite diverse group of functionalized arenes and benzylic alcohols. These mild conditions provide a straightforward synthesis of a variety of unsymmetrical diarylmethanes in high yield with good to high regioselectivity. An SN1 mechanism involving activation of the hydroxy group through a hydrogen bond is proposed.
- Tang, Ren-Jin,Milcent, Thierry,Crousse, Benoit
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p. 14001 - 14009
(2018/11/23)
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- Nickel-Catalyzed Cross-Electrophile Coupling between Benzyl Alcohols and Aryl Halides Assisted by Titanium Co-reductant
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A nickel-catalyzed cross-electrophile coupling reaction between benzyl alcohols and aryl halides has been developed using a homolytic C-O bond cleavage protocol that has recently been established. The treatment of a benzyl alcohol and aryl halide with a nickel catalyst and low-valent titanium reagent generated from TiCl4(lutidine) (lutidine = 2,6-lutidine) and manganese powder afforded the cross-coupled product in high yield. A mechanistic study indicated the intermediacy of the benzyl radicals that originate from the benzyl alcohols.
- Suga, Takuya,Ukaji, Yutaka
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supporting information
p. 7846 - 7850
(2019/01/14)
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- Chlorotrimethylsilane and Sodium Iodide: A Remarkable Metal-Free Association for the Desulfurization of Benzylic Dithioketals under Mild Conditions
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A novel metal-free process allowing the reductive desulfurization of various benzylic dithioketals to afford diarylmethane and benzylester derivatives with good to excellent yields is reported. At room temperature, this mild reduction process requires only the use of TMSCl and NaI in CH2Cl2 and tolerates a large variety of functional groups. (Figure presented.).
- Zhao, Guangkuan,Yuan, Ling-Zhi,Alami, Mouad,Provot, Olivier
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p. 2522 - 2536
(2018/05/14)
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- An Efficient Ga(OTf)3/Isopropanol Catalytic System for Direct Reduction of Benzylic Alcohols
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This study aims to report the first gallium-catalyzed direct reduction of benzylic alcohols using isopropanol as a reductant. The reaction proceeds via gallium catalyst-assisted hydride transfer of the in situ-generated benzylic isopropyl ether. The method generates only water and acetone as byproducts and thus provides an atom-economic and environmentally friendly approach to the synthesis of di- and triarylmethanes, which are important substructures in various bioactive compounds and functional materials. (Figure presented.).
- Sai, Masahiro
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supporting information
p. 4330 - 4335
(2018/10/15)
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- Nickel-Catalyzed Csp2-Csp3 Bond Formation via C-F Bond Activation
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A nickel-catalyzed cross coupling of aryl fluorides via C-F bond activation has been developed. The alkylation method allows selective replacement of aryl fluorides by alkyl groups and enables the synthesis of diverse and otherwise difficult to access scaffolds in good yields.
- Ho, Yee Ann,Leiendecker, Matthias,Liu, Xiangqian,Wang, Chengming,Alandini, Nurtalya,Rueping, Magnus
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supporting information
p. 5644 - 5647
(2018/09/12)
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- Transition-Metal-Free Synthesis of Biarylmethanes from Aryl Iodides and Benzylic Ketones
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An original metal-free procedure for the synthesis of biarylmethanes is disclosed herein. The reactions occur with high selectivity starting from aryl iodides and benzylic ketones in the presence of superbasic media (CsOH/DMSO). This procedure allows a straightforward access to a wide range of biarylmethane derivatives substituted with electron-withdrawing and -donating substituents.
- Pichette Drapeau, Martin,Tlili, Anis,Zaid, Yassir,Toummini, Dounia,Ouazzani Chahdi, Fouad,Sotiropoulos, Jean-Marc,Ollevier, Thierry,Taillefer, Marc
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supporting information
p. 17449 - 17453
(2018/11/10)
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- Cross-Coupling of Phenol Derivatives with Umpolung Aldehydes Catalyzed by Nickel
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A nickel-catalyzed cross-coupling to construct the C(sp2)-C(sp3) bond was developed from two sustainable biomass-based feedstocks: phenol derivatives with umpolung aldehydes. This strategy features the in situ generation of moisture/air-stable hydrazones from naturally abundant aldehydes, which act as alkyl nucleophiles under catalysis to couple with readily available phenol derivatives. The avoidance of using both halides as the electrophiles and organometallic or organoboron reagents (also derived from halides) as the nucleophiles makes this method more sustainable. Water tolerance, great functional group (ketone, ester, free amine, amide, etc.) compatibility, and late-stage elaboration of complex biological molecules exemplified its practicability and unique chemoselectivity over organometallic reagents.
- Lv, Leiyang,Zhu, Dianhu,Tang, Jianting,Qiu, Zihang,Li, Chen-Chen,Gao, Jian,Li, Chao-Jun
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p. 4622 - 4627
(2018/05/22)
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- Nickel-catalyzed cross-coupling of aldehydes with aryl halides: Via hydrazone intermediates
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Traditional cross-couplings require stoichiometric organometallic reagents. A novel nickel-catalyzed cross-coupling reaction between aldehydes and aryl halides via hydrazone intermediates has been developed, merging the Wolff-Kishner reduction and the classical cross-coupling reactions. Aromatic aldehydes, aryl iodides and aryl bromides are especially effective in this new cross-coupling chemistry.
- Tang, Jianting,Lv, Leiyang,Dai, Xi-Jie,Li, Chen-Chen,Li, Lu,Li, Chao-Jun
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supporting information
p. 1750 - 1753
(2018/02/21)
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- Dinuclear NHC–palladium(II) complexes: synthesis,characterization and application to Suzuki–Miyaura cross-coupling reactions
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Abstract: Four dinuclear N-heterocyclic carbene–palladium(II) complexes 1–4 were prepared and characterized by elemental analysis and spectroscopic methods. The X-ray crystal structure of complex 2 showed a dinuclear framework in which N-heterocyclic ligands bridge between two square planar palladium(II) units. Each palladium center is surrounded by an imidazolylidene, a nitrogen atom from the central linking ligand, and two trans-chloride ligands. These dinuclear NHC–palladium(II) complexes exhibited efficient catalytic activities for the Suzuki–Miyaura coupling of aryl and benzyl chlorides with arylboronic acids.
- Wang, Tao,Xu, Kai,Wang, Wanli,Zhang, Anan,Liu, Lantao
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p. 347 - 353
(2018/03/23)
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- A Zwitterionic Palladium(II) Complex as a Precatalyst for Neat-Water-Mediated Cross-Coupling Reactions of Heteroaryl, Benzyl, and Aryl Acid Chlorides with Organoboron Reagents
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The Suzuki–Miyaura cross-coupling (SMC) reactions of several heteroaryl chlorides, benzyl chlorides, and aryl acid chlorides with (hetero)arylboron reagents have been investigated in the presence of [Pd(HL1)(PPh3)Cl2] (I) [HL1 = 3-[(2,6-diisopropylphenyl)-1-imidazolio]-2-quinoxalinide] as catalyst and K2CO3 as base in neat water. The synthesis of the heterocycle-containing biaryls required the addition of 2 mol-% of a phosphine ligand (PPh3 or X-Phos). A combination of more than 115 substrates were screened and it was found that I is a versatile catalyst that can produce heterocycle-containing biaryls, diarylmethanes, and benzophenones in moderate-to-excellent yields.
- Ramakrishna, Visannagari,Rani, Morla Jhansi,Reddy, Nareddula Dastagiri
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p. 7238 - 7255
(2018/01/01)
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- A Zinc Catalyzed C(sp3)?C(sp2) Suzuki–Miyaura Cross-Coupling Reaction Mediated by Aryl-Zincates
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The Suzuki–Miyaura (SM) reaction is one of the most important methods for C?C bond formation in chemical synthesis. In this communication, we show for the first time that the low toxicity, inexpensive element zinc is able to catalyze SM reactions. The cross-coupling of benzyl bromides with aryl borates is catalyzed by ZnBr2, in a process that is free from added ligand, and is compatible with a range of functionalized benzyl bromides and arylboronic acid pinacol esters. Initial mechanistic investigations indicate that the selective in situ formation of triaryl zincates is crucial to promote selective cross-coupling reactivity, which is facilitated by employing an arylborate of optimal nucleophilicity.
- Procter, Richard J.,Dunsford, Jay J.,Rushworth, Philip J.,Hulcoop, David G.,Layfield, Richard A.,Ingleson, Michael J.
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supporting information
p. 15889 - 15893
(2017/10/24)
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- Feedstocks to Pharmacophores: Cu-Catalyzed Oxidative Arylation of Inexpensive Alkylarenes Enabling Direct Access to Diarylalkanes
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A Cu-catalyzed method has been identified for selective oxidative arylation of benzylic C-H bonds with arylboronic esters. The resulting 1,1-diarylalkanes are accessed directly from inexpensive alkylarenes containing primary and secondary benzylic C-H bonds, such as toluene or ethylbenzene. All catalyst components are commercially available at low cost, and the arylboronic esters are either commercially available or easily accessible from the commercially available boronic acids. The potential utility of these methods in medicinal chemistry applications is highlighted.
- Vasilopoulos, Aristidis,Zultanski, Susan L.,Stahl, Shannon S.
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p. 7705 - 7708
(2017/06/20)
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- An Efficient Synthetic Approach to trans-(NHC)2Pd(R)Br Type Complexes and Their Use in Suzuki–Miyaura Cross-Coupling Reactions
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Mixed organohalidopalladium complexes of the type trans-(NHC)2Pd(R)Br were conveniently obtained from trans-(NHC)2PdBr2 type complexes by a ligand-substitution reaction. In particular, the trans-[1-(1S)-menthyl-4-(R1)-1,2,4-triazol-5-ylidene]2Pd(R2)Br [R1 = Et, R2 = CH2Ph (3a1); R1 = Et, R2 = o-OMeC6H4 (3a2); R1 = R2 = CH2Ph (3b1); R1 = CH2Ph, R2 = o-OMeC6H4 (3b2)] complexes were obtained from the corresponding palladium(II) precursor complexes, 2a,b, by reaction with the respective Grignard reagents, in good to excellent yields (74–93 %). Three of the four mixed organohalidopalladium complexes, 3a1,a2,b1, have been structurally characterized by single-crystal X-ray diffraction, which revealed the trans disposition of the NHC ligands around the palladium center. The use of these mixed organohalidopalladium complexes in the Suzuki–Miyaura cross-coupling reaction was established for all of the complexes, 3a1–b2, which yielded the desired cross-coupled products upon treatment with various ArB(OH)2 [Ar = 1-naphthyl, 4-(1,1′-biphenyl), 9-phenanthrenyl, 4-FC6H4, and 2,6-Me2C6H3] compounds, in the presence of NaOH as a base, in CH3CN, in three hours, under reflux conditions.
- Kumar, Anuj,Prakasham,Gangwar, Manoj Kumar,Vishnoi, Pratap,Butcher, Raymond J.,Ghosh, Prasenjit
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p. 2144 - 2154
(2017/04/21)
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- Synthesis of Di- and Triarylmethanes through Palladium-Catalyzed Reductive Coupling of N -Tosylhydrazones and Aryl Bromides
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A palladium-catalyzed reductive coupling between N-tosylhydrazones and aryl bromides has been developed. The reaction provides an efficient method for the synthesis of diarylmethanes and triarylmethanes via the formation of C(sp2)-C(sp3) single bonds. This new methodology for the synthesis of diarylmethanes and triarylmethanes is featured by the ready availability of the starting materials, mild reaction conditions, and the tolerance of wide range of functional groups. The reaction follows a pathway including palladium carbene formation, migratory insertion, and reduction of the alkylpalladium(II) intermediate.
- Xia, Yamu,Hu, Fangdong,Xia, Ying,Liu, Zhenxing,Ye, Fei,Zhang, Yan,Wang, Jianbo
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p. 1073 - 1086
(2017/02/24)
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- Facile Hydrogenolysis of C(sp3)–C(sp3) σ Bonds
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The modification of benzylic quaternary, tertiary, and secondary carbon centers through palladium-catalyzed hydrogenolysis of C(sp3)–C(sp3) σ bonds is presented. When benzyl Meldrum's acid derivatives bearing quaternary benzylic centers are treated under mild hydrogenolysis conditions – palladium on carbon and atmospheric pressure of hydrogen – aromatics substituted with tertiary benzylic centers and Meldrum's acid are obtained with good to excellent yield. Analogously, substrates containing tertiary or secondary benzylic centers yield aromatics substituted with secondary benzylic centers or toluene derivatives, respectively. Furthermore, this strategy is used for the high yielding synthesis of diarylmethanes. The scope of the reductive dealkylation reaction is explored and the limitations with respect to steric and electronic factors are determined. A mechanistic analysis of the reaction is described that consisted of deuterium labelling experiments and hydrogenolysis of enantioenriched derivatives. The investigation shows that the C(sp3)–C(sp3) σ bond-cleaving events occur through a hybrid SN1/SN2 mechanism, in which the palladium center displaces a carbon-based leaving group, namely Meldrum's acid, with inversion of configuration, followed by reductive elimination of palladium to furnish a C?H bond. (Figure presented.).
- Fillion, Eric,Beaton, Eric,Nguyen, Yen,Wilsily, Ashraf,Bondarenko, Ganna,Jacq, Jér?me
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p. 3422 - 3434
(2016/11/13)
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- Cobalt-Catalyzed Reductive Cross-Coupling Between Benzyl Chlorides and Aryl Halides
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A new protocol for the direct reductive cobalt-catalyzed arylation of benzyl chlorides has been developed in order to form functionalized diarylmethanes. A variety of reactive groups either on the aryl or the benzyl halide was employed. This represents the first cobalt-catalyzed reductive cross-coupling which does not require any ligand and pyridine. A reaction pathway is proposed involving a radical benzyl species. (Figure presented.).
- Pal, Suman,Chowdhury, Sushobhan,Rozwadowski, Elodie,Auffrant, Audrey,Gosmini, Corinne
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supporting information
p. 2431 - 2435
(2016/08/16)
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- Ferrocenyl-derived electrophilic phosphonium cations (EPCs) as Lewis acid catalysts
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Oxidation of diphenylphosphinoferrocene and 1,1′-bis(diphenylphosphino)ferrocene with XeF2, resulted in the formation of CpFe(η5-C5H4PF2Ph2) 1 and Fe(η5-C5H4PF2Ph2)22 respectively. Subsequent reactions with [SiEt3][B(C6F5)4] yielded [CpFe(η5-C5H4PFPh2)][B(C6F5)4] 3 and [Fe(η5-C5H4PFPh2)2] [B(C6F5)4]24. PhP(η5-C5H4)2Fe 5 was prepared, converted to [PhMeP(η5-C5H4)2Fe][O3SCF3] 6 and then to [PhMeP(η5-C5H4)2Fe][B(C6F5)4] 7. The ability of the salts 3, 4 and 7 to catalyze Friedel-Crafts dimerization of 1,1-diphenylethylene, dehydrocoupling of phenol and triethylsilane, deoxygenation of acetophenone and hydrodefluorination of 1-fluoropentane were probed. While compound 7 proved to be ineffective, compounds 3 and 4 were useful Lewis acid catalysts. Compounds 3 and 4 were shown to catalyze the deoxygenation of a series of ketones.
- Mallov, Ian,Stephan, Douglas W.
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supporting information
p. 5568 - 5574
(2016/04/09)
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- Nickel-Catalyzed Cross-Electrophile Coupling with Organic Reductants in Non-Amide Solvents
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Cross-electrophile coupling of aryl halides with alkyl halides has thus far been primarily conducted with stoichiometric metallic reductants in amide solvents. This report demonstrates that the use of tetrakis(dimethylamino)ethylene (TDAE) as an organic reductant enables the use of non-amide solvents, such as acetonitrile or propylene oxide, for the coupling of benzyl chlorides and alkyl iodides with aryl halides. Furthermore, these conditions work for several electron-poor heterocycles that are easily reduced by manganese. Finally, we demonstrate that TDAE addition can be used as a control element to ‘hold’ a reaction without diminishing yield or catalyst activity.
- Anka-Lufford, Lukiana L.,Huihui, Kierra M. M.,Gower, Nicholas J.,Ackerman, Laura K. G.,Weix, Daniel J.
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supporting information
p. 11564 - 11567
(2016/08/05)
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- N-heterocyclic carbene-palladium(II) complexes with benzoxazole or benzothiazole ligands: Synthesis, characterization, and application to Suzuki-Miyaura cross-coupling reaction
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A series of novel N-heterocyclic carbene-palladium(II) complexes 3 were conveniently prepared from commercially available imidazolium salts, palladium chloride, and benzoxazole or benzothiazole in one step. All of the new complexes have been fully characterized by elemental analysis, 1H, 13C NMR, and IR spectra. In addition, the molecular structures of complexes 3a-d have also been determined by X-ray single-crystal diffraction. The obtained palladium(II) catalysts showed efficient catalytic activity toward the Suzuki-Miyaura coupling of aryl as well as benzyl chlorides with arylboronic acids. Under the optimal reaction conditions, the expected biaryl products were obtained in moderate to high yields.
- Wang, Tao,Xie, Huanping,Liu, Lantao,Zhao, Wen-Xian
-
-
- Synthesis and characterization of trinuclear N-heterocyclic carbene-palladium(II) complexes and their applications in the Suzuki-Miyaura cross-coupling reaction
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Five novel trinuclear N-heterocyclic carbene-palladium(ii) complexes 5a-e were conveniently synthesized through one-pot reactions of imidazolium salts, tridentate N-heterocycles {tris(4-(pyridin-4-yl)phenyl)amine or tris(4-(pyridin-3-yl)phenyl)amine} and palladium chloride in one step. All of the new complexes have been fully characterized by elemental analysis, 1H, 13C NMR, and IR spectra. Among them, the molecular structures of complex 5d have been determined by X-ray single-crystal diffraction. Moreover, the obtained trinuclear palladium(ii) complexes were the effective catalyst precursors for the Suzuki-Miyaura coupling of aryl as well as benzyl chlorides with arylboronic acids. Under the optimal reaction conditions, the expected biaryl products were obtained in good to almost quantitative yields.
- Wang, Tao,Liu, Lantao,Xu, Kai,Xie, Huanping,Shen, Hui,Zhao, Wen-Xian
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p. 100690 - 100695
(2016/11/09)
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- Iron catalysed Negishi cross-coupling using simple ethyl-monophosphines
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Monophosphines prepared by iron catalysed hydrophosphination have been used as pro-ligands in iron catalysed Negishi cross-coupling of alkyl bromides and diphenyl zinc reagents. The cross-coupling has been investigated with monophosphines with varying electronic properties and we find the simplest, unsubstituted phosphine to offer the optimum reaction conditions (both in terms of yield of diarylmethane product and cost-effectiveness of the phosphine). In situ catalyst generation from monophosphine and FeCl2 was used in catalysis; however, preparation of a discrete homonuclear iron complex was also achieved and this four-coordinate iron-phosphine complex was isolated and used in catalysis.
- Brown, Caleb A.,Nile, Terence A.,Mahon, Mary F.,Webster, Ruth L.
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p. 12189 - 12195
(2016/01/15)
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- Ethers as hydrogen sources in BF3·OEt2 promoted reduction of diphenylmethyl alcohols, ethers and esters to hydrocarbons
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A novel ether/BF3 reductive system has been described, in which diphenylmethanols and their ether and ester derivatives are used as starting materials. Reductions are performed in ether under reflux and an argon atmosphere, and the addition of extra water is beneficial to this reduction. A series of alkanes are able to be prepared with good to excellent yields. A deuterated experiment exhibits that the reductive hydrogen is generated from ether. The mechanism is discussed in detail to explain the observed reactivity.
- Li, Jiaqiang,Liu, Qing,Shen, Hang,Huang, Ruofeng,Zhang, Xiaohui,Xiong, Yan,Chen, Changguo
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p. 85291 - 85295
(2015/11/02)
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- Catalytic Ketone Hydrodeoxygenation Mediated by Highly Electrophilic Phosphonium Cations
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Ketones are efficiently deoxygenated in the presence of silane using highly electrophilic phosphonium cation (EPC) salts as catalysts, thus affording the corresponding alkane and siloxane. The influence of distinct substitution patterns on the catalytic effectiveness of several EPCs was evaluated. The deoxygenation mechanism was probed by DFT methods.
- Mehta, Meera,Holthausen, Michael H.,Mallov, Ian,Pérez, Manuel,Qu, Zheng-Wang,Grimme, Stefan,Stephan, Douglas W.
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supporting information
p. 8250 - 8254
(2015/07/07)
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- N-Heterocyclic carbene-palladium(II)-1-methylimidazole complex-catalyzed Suzuki-Miyaura coupling of benzyl carbamates with arylboronic acids
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The Suzuki-Miyaura coupling of benzyl carbamates with arylboronic acids was achieved in an environmentally benign medium. Using water as the sole solvent, such transformation took place very well to give the desired diarylmethane derivatives in good to almost quantitative yields in the presence of a well-defined NHC-Pd(ii)-Im complex under mild conditions. It is worth noting here that this is the first example of benzyl carbamates used in coupling reaction, thus affording a new method for the formation of diarylmethanes by palladium-catalyzed C-O bond activation.
- Wang, Xiao-Xia,Luo, Mao-Jun,Lu, Jian-Mei
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p. 11438 - 11444
(2015/12/04)
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- N-heterocyclic carbene-palladium(II)-1-methylimidazole complex-catalyzed Suzuki-Miyaura coupling of benzyl sulfonates with arylboronic acids
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The first example of palladium-catalyzed Suzuki-Miyaura coupling between benzyl sulfonates and arylboronic acids was reported in this paper. In the presence of a well-defined, air-stable and easily available NHC-Pd(ii)-Im complex, all reactions worked well to give the desired products in good to almost quantitative yields under the optimal conditions. Electron-rich, -neutral, -poor and sterically-hindered substituents on both substrates are tolerated in such transformation, providing a convenient, efficient and alternative method for the synthesis of diarylmethanes.
- Wang, Xiao-Xia,Xu, Bin-Bin,Song, Wen-Ting,Sun, Kai-Xin,Lu, Jian-Mei
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p. 4925 - 4930
(2015/05/05)
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- Efficient synthesis of diarylmethane derivatives by PdCl2 catalyzed cross-coupling reactions of benzyl chlorides with aryl boronic acids in aqueous medium
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The research provides a simple and efficient method for preparing diarylmethane derivatives using the cross-coupling reaction of benzyl chlorides and aryl boronic acids catalyzed by palladium chloride in DMF aqueous solution without additional ligand.
- Zhao, Guangkuan,Zhang, Kena,Wang, Liang,Li, Jingya,Zou, Dapeng,Wu, Yangjie,Wu, Yusheng
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supporting information
p. 6700 - 6703
(2016/02/03)
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- Visible light mediated efficient oxidative benzylic sp3 C-H to ketone derivatives obtained under mild conditions using O2
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A photooxygenation of benzylic sp3 C-H reaction has been demonstrated using O2 mediated by visible light. This protocol provides a simple and mild route to obtain ketones from benzylic sp3 C-H bonds. Various benzylic sp3 C-H bonds can be transformed into the desired ketone derivatives in moderate to good yields. The 18O2 labelling experiments demonstrated that the oxygen introduced into ketone originated from dioxygen. A plausible mechanism has been proposed accordingly.
- Yi, Hong,Bian, Changliang,Hu, Xia,Niu, Linbin,Lei, Aiwen
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supporting information
p. 14046 - 14049
(2015/09/15)
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- Iron-catalyzed hetero-cross-dehydrogenative coupling reactions of sulfoximines with diarylmethanes: A new route to N-alkylated sulfoximines
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An efficient iron-catalyzed C-N bond formation by hetero-cross- dehydrogenative coupling (CDC) between sulfoximines and diarylmethanes is described. The reaction shows good functional group tolerance and provides N-alkylated sulfoximines in moderate to go
- Cheng, Ying,Dong, Wanrong,Wang, Long,Parthasarathy, Kanniyappan,Bolm, Carsten
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supporting information
p. 2000 - 2002
(2014/05/06)
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- Synthesis of diarylmethanes through palladium-catalyzed coupling of benzylic phosphates with arylsilanes
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An efficient approach to the benzylation of arenes has been developed. The reactions described provide straightforward access to diarylmethanes through Pd-catalyzed coupling of benzylic phosphates with arylsilanes in good to excellent yields. The reaction tolerates a wide range of functionalities such as halide, alkoxyl, and nitro groups.
- Zhang, Pengbo,Xu, Jian,Gao, Yuzhen,Li, Xueqin,Tang, Guo,Zhao, Yufen
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p. 2928 - 2932
(2015/01/16)
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- Palladium-catalyzed benzylation of arylboronic acids with N,N-ditosylbenzylamines
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The palladium-catalyzed coupling of N,N-ditosylbenzylamines with arylboronic acids has been investigated, and the resulting diarylmethanes were obtained in high yields. Conversion of the amine to a N,N-ditosylimide group provided an efficient leaving group for the Pd-catalyzed benzylation of arylboronic acids.
- Yoon, Sangeun,Hong, Myeng Chan,Rhee, Hakjune
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p. 4206 - 4211
(2014/05/20)
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- Iridium-catalyzed diborylation of benzylic C-H bonds directed by a hydrosilyl group: Synthesis of 1,1-benzyldiboronate esters
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We describe a regioselective diborylation of primary benzylic C-H bonds catalyzed by [Ir(COD)OMe]2 and 4,4′-di-tert-butyl-2,2′- bipyridine (dtbpy). The hydrosilyl group acts as a traceless directing group, providing access to a range of 1,1-benzyldiboronate esters in good yields. Transformations of the 1,1-benzyldiboronate ester products include chemoselective Suzuki-Miyaura cross-couplings and synthesis of tetrasubstituted alkenyl boronate esters.
- Cho, Seung Hwan,Hartwig, John F.
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p. 694 - 698
(2014/01/17)
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- Synthesis of structurally diverse diarylketones through the diarylmethyl sp3 C-H oxidation
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Under open-flask conditions, an efficient method to assemble a series of diversely functionalized diarylketones in the presence of commercially available NBS has been developed. Yields of up to 99% have been achieved employing diarylmethanes as starting material. Based on 18O-labeled experiment, the addition of stoichiometric water eventually leads to excellent yields in all carbonylation cases.
- He, Chao,Zhang, Xiaohui,Huang, Ruofeng,Pan, Jing,Li, Jiaqiang,Ling, Xuege,Xiong, Yan,Zhu, Xiangming
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supporting information
p. 4458 - 4462
(2014/08/05)
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- Synthesis of Ni(II) complexes with unsymmetric [O,N,O′]-pincer ligands and their use as precatalysts in carbon-carbon bond formations to access diarylmethanes
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1-Acetyl-[1a,3,5-CF3,1-C(=O)CH3] and 1-benzoyl-5-hydroxypyrazolines [1b, 3,5-CF3, 1-C(=O)C 6H5] have been synthesized and reacted with Ni(OAc) 2·4H2O in the presence of PPh3 to form square planar nickel complexes, which revealed a O,N,O′-coordination. An additional coordination site on the nickel center is occupied by one triphenylphosphane ligand. After having investigated the properties of the complexes, catalytic experiments have been carried out to synthesize diarylmethanes. Applying the complexes in the nickel-catalyzed carbon-carbon cross coupling of aryl halides with benzylzinc bromide excellent yields and selectivities of the corresponding diarylmethane have been obtained. Moreover, various experiments have been performed to shed light on the underlying reaction mechanism.
- Someya, Chika I.,Irran, Elisabeth,Enthaler, Stephan
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p. 136 - 144
(2014/07/08)
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- Cyclometalated 2-phenylimidazole palladium carbene complexes in the catalytic Suzuki-Miyaura cross-coupling reaction
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We present the syntheses of 12 cyclometalated palladium C-N 2-phenylimidazole carbene complexes with different N-1 groups as well as different substituents at the C-2 phenyl group of the cyclometalating imidazole. We investigated the influence of these substituents by comparing the catalytic performance of the complexes in the Suzuki-Miyaura cross-coupling reaction of aryl chlorides. We can show a strong dependence between the steric demand of the N-1 substituent of the cyclometalating imidazole and the catalytic activity in the cross-coupling reaction. The most active complex shows a wide substrate scope, where several aryl as well as benzyl chlorides could be coupled with different boronic acids in excellent yields using very low catalyst concentrations of 0.05 mol %.
- Micksch, Maik,Tenne, Mario,Strassner, Thomas
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p. 3966 - 3976
(2014/09/30)
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- A highly efficient catalyst for Suzuki-Miyaura coupling reaction of benzyl chloride under mild conditions
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Diarylmethane derivatives, essential building blocks in organic synthesis, are usually synthesized through the traditional electrophilic substitution reaction i.e., Friedel-Crafts reaction, which suffers from the rearrangement and weak reactivity of aromatic compounds with deactivating/electron-withdrawing groups. The Suzuki-Miyaura coupling reaction of low-cost benzyl chloride as an alternative method overcomes these defects. Pd(ii) organometallic catalysts immobilized on the triphenylphosphine-functionalized microporous knitting aryl polymer (KAPs(Ph-PPh3)-Pd) as a novel heterogeneous catalyst was employed in Suzuki-Miyaura coupling reaction of benzyl chloride and exhibited excellent catalytic activity under mild conditions with a turnover frequency (TOF) up to 76 min-1 (4569 h-1). This work reveals that the microporous structure of the catalyst can rapidly adsorb substrates, consequently facilitating their interaction, and eventually promoting the catalytic efficiency. the Partner Organisations 2014.
- Guan, Zhenhong,Li, Buyi,Hai, Guoliang,Yang, Xinjia,Li, Tao,Tan, Bien
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p. 36437 - 36443
(2014/11/08)
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- Direct electrosynthesis of ketones from benzylic methylenes by electrooxidative C-H activation
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Electrify your chemistry! Direct electrosynthesis of ketones from benzylic methylenes in an undivided cell was realized in moderate to good yields (see scheme). In this electrosynthesis, electrons instead of conventional oxidants and catalysts are employed to make the reaction environmentally benign. Moreover, the reaction intermediate radical was detected by ESR spectroscopy and the reaction mechanism was clarified.
- Meng, Li,Su, Jihu,Zha, Zhenggen,Zhang, Li,Zhang, Zhenlei,Wang, Zhiyong
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p. 5542 - 5545
(2013/05/23)
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- Coupling of benzyl halides with aryl Grignard reagents catalyzed by iron(III) amine-bis(phenolate) complexes
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Reaction of benzylamino-N,N-bis(2-methylene-4,6-di-tert-amylphenol), H 2L1, with anhydrous ferric chloride in the presence of a base yields FeCl(THF)L1 (1). In the solid state, complex 1 exists as a monomeric iron(III) species with a distorted trigonal bipyramidal geometry. Complex 1 is an air-stable, non-hygroscopic, single-component catalyst for C-C cross-coupling of aryl Grignard reagents with benzyl halides, including chlorides. Moderate to good yields of cross-coupled products can be obtained in diethyl ether at room temperature. Preliminary investigations include the screening of electron-donating and electron-withdrawing groups on both the benzylic substrate and the aryl Grignard reagent.
- Chard, Elliott F.,Dawe, Louise N.,Kozak, Christopher M.
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- IRON BISPHENOLATE COMPLEXES AND METHODS OF USE AND SYNTHESIS THEREOF
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The present application, relates to iron bisphenolate complexes and methods of use and synthesis thereof. The iron complexes are prepared from tridentate or tetradentate ligands of Formula I: wherein R1 and R2 are as defined herein. Also provided are methods and processes of using the iron bisphenolate complexes as catalysts in cross-coupling reactions and in controlled radical polymerizations.
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Paragraph 00282-00284
(2013/04/25)
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