- Solar light induced carbon-carbon bond formation via TiO2 photocatalysis
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Solar light irradiation of a TiO2 suspension in MeCN containing maleic anhydride and 4-methoxybenzyl(trimethyl)silane gives benzylated succinic acid (or anhydride) on a gram scale.
- Cermenati, Laura,Richter, Christoph,Albini, Angelo
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- Synthesis of ethylene bis [(2-hydroxy-5,1,3-phenylene) bis methylene] tetraphosphonic acid and their anticorrosive effect on carbon steel in 3%NaCl solution
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The inhibition performance of the newly synthesized Ethylene bis [(2-hydroxy-5,1,3-phenylene) bis methylene] tetraphosphonic acid (ETPA) toward carbon steel in 3% NaCl was investigated at different concentrations using potentiodynamic polarization (PDP) and impedance spectroscopy (EIS) methods. It was found that the inhibition capability was increased with increasing inhibitor dose and reach 92% at 10?3 mol/L. Also, Polarization curves showed that ETPA acts as a mixed type inhibitor with predominantly control of anodic reaction. The new inhibitor was investigated by different spectroscopic methods such as 1H, 13C and 31PNMR. The quantum parameters such as absolute electronegativity (χ), energy gap ΔE (EHOMO-ELUMO), global softness (σ), global hardness (η), electrophilicity index (ω) and the number of transfer electrons (ΔN) are calculated by density functional theory (DFT). The experimental also correlated with density functional theory results. The calculations show that ETPA has high density of negative charge located on the oxygen atoms of the phosphonate group facilitating the adsorption of ETPA on the surface of carbon steel. The inhibition efficiency of ETPA was discussed in terms of blocking of electrode surface by adsorption of ETPA molecules through active centers. The adsorption of ETPA on the surface of carbon steel obeyed the Langmuir isotherm paradigm.
- Sait,Aliouane,Toukal,Hammache,Al-Noaimi,Helesbeux,Duval
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- Synthesis of Dibenzyls by Nickel-Catalyzed Homocoupling of Benzyl Alcohols
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Dibenzyls are essential building blocks that are widely used in organic synthesis, and they are typically prepared by the homocoupling of halides, organometallics, and ethers. Herein, we report an approach to this class of compounds using alcohols, which are more stable and readily available. The reaction proceeds via nickel-catalyzed and dimethyl oxalate assisted dynamic kinetic homocoupling of benzyl alcohols. Both primary and secondary alcohols are tolerated.
- Pan, Feng-Feng,Guo, Peng,Huang, Xiaochuang,Shu, Xing-Zhong
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p. 3094 - 3100
(2021/04/23)
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- Dynamic Kinetic Cross-Electrophile Arylation of Benzyl Alcohols by Nickel Catalysis
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Catalytic transformation of alcohols via metal-catalyzed cross-coupling reactions is very important, but it typically relies on a multistep procedure. We here report a dynamic kinetic cross-coupling approach for the direct functionalization of alcohols. The feasibility of this strategy is demonstrated by a nickel-catalyzed cross-electrophile arylation reaction of benzyl alcohols with (hetero)aryl electrophiles. The reaction proceeds with a broad substrate scope of both coupling partners. The electron-rich, electron-poor, and ortho-/meta-/para-substituted (hetero)aryl electrophiles (e.g., Ar-OTf, Ar-I, Ar-Br, and inert Ar-Cl) all coupled well. Most of the functionalities, including aldehyde, ketone, amide, ester, nitrile, sulfone, furan, thiophene, benzothiophene, pyridine, quinolone, Ar-SiMe3, Ar-Bpin, and Ar-SnBu3, were tolerated. The dynamic nature of this method enables the direct arylation of benzylic alcohol in the presence of various nucleophilic groups, including nonactivated primary/secondary/tertiary alcohols, phenols, and free indoles. It thus offers a robust alternative to existing methods for the precise construction of diarylmethanes. The synthetic utility of the method was demonstrated by a concise synthesis of biologically active molecules and by its application to peptide modification and conjugation. Preliminary mechanistic studies revealed that the reaction of in situ formed benzyl oxalates with nickel, possibly via a radical process, is an initial step in the reaction with aryl electrophiles.
- Guo, Peng,Wang, Ke,Jin, Wen-Jie,Xie, Hao,Qi, Liangliang,Liu, Xue-Yuan,Shu, Xing-Zhong
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p. 513 - 523
(2021/01/12)
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- Molybdenum-Catalyzed Deoxygenation Coupling of Lignin-Derived Alcohols for Functionalized Bibenzyl Chemicals
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With the growing demand for sustainability and reducing CO2 footprint, lignocellulosic biomass has attracted much attention as a renewable, carbon-neutral and low-cost feedstock for the production of chemicals and fuels. To realize efficient utilization of biomass resource, it is essential to selectively alter the high degree of oxygen functionality of biomass-derivates. Herein, we introduced a novel procedure to transform renewable lignin-derived alcohols to various functionalized bibenzyl chemicals. This strategy relied on a short deoxygenation coupling pathway with economical molybdenum catalyst. A well-designed H-donor experiment was performed to investigate the mechanism of this Mo-catalyzed process. It was proven that benzyl carbon-radical was the most possible intermediate to form the bibenzyl products. It was also discovered that the para methoxy and phenolic hydroxyl groups could stabilize the corresponding radical intermediates and then facilitate to selectively obtain bibenzyl products. Our research provides a promising application to produce functionalized aromatics from biomass-derived materials.
- Jiang, Huifang,Lu, Rui,Luo, Xiaolin,Si, Xiaoqin,Xu, Jie,Lu, Fang
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supporting information
p. 1292 - 1296
(2020/12/09)
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- Enantioselective Radical SN2-Type Alkylation of Morita-Baylis-Hillman Adducts Using Dual Photoredox/Palladium Catalysis
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An enantioselective radical alkylation of 4-alkyl-1,4-dihydropyridines with Morita-Baylis-Hillman (MBH) adducts has been reported. The SN2-type products are predominant. This reaction is enabled by dual photoredox/palladium catalysis. The alkylation products are provided in good yields with good regio- and enantioselectivity. The use of Ding's spiroketal-based bis(phosphine) (SKP) ligand is crucial to achieving satisfactory regio- and enantioselectivity. The resultant α,β-unsaturated ester can be easily reduced to a synthetically useful chiral allyl alcohol.
- Bai, Xiangbin,Qian, Linlin,Zhang, Hong-Hao,Yu, Shouyun
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supporting information
p. 8322 - 8326
(2021/11/13)
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- A heavy-metal-free desulfonylative Giese-type reaction of benzothiazole sulfones under visible-light conditions
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A visible-light-induced desulfonylative Giese-type reaction has been developed. Essential to the success is the employment of Hantzsch ester to activate benzothiazole sulfones without any heavy-metal additives. Not only benzylic benzothiazole sulfones but also alkyl ones were viable substrates and reacted with electron-deficient alkenes and a propiol amide.
- Inuzuka, Toshiyasu,Iwama, Haruka,Ogawa, Daichi,Sengoku, Tetsuya,Yoda, Hidemi
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supporting information
p. 9858 - 9861
(2021/10/12)
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- Boron carbonitride photocatalysts for direct decarboxylation: The construction of C(sp3)-N or C(sp3)-C(sp2) bonds with visible light
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A metal-free protocol is established for the decarboxylative N-H or C(sp2)-H functionalization of acidsviametal-free boron carbon nitride (BCN) photocatalysis, delivering the desired products under ambient conditions. This methodology is applicable to the late-stage modification of pharmaceutical molecules and gram-scale experiments as well as in the recovery and reuse of the photocatalysts without the loss of reactivity. The developed photochemical reaction system fulfills the requirements of green and sustainable chemistry.
- Shi, Jiale,Wang, Rong,Wang, Xinchen,Yuan, Tao,Zheng, Meifang
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supporting information
p. 3945 - 3949
(2021/06/17)
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- Photocatalytic Reductive C-O Bond Cleavage of Alkyl Aryl Ethers by Using Carbazole Catalysts with Cesium Carbonate
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Methods to activate the relatively stable ether C-O bonds and convert them to other functional groups are desirable. One-electron reduction of ethers is a potentially promising route to cleave the C-O bond. However, owing to the highly negative redox potential of alkyl aryl ethers (Ered -2.6 V vs SCE), this mode of ether C-O bond activation is challenging. Herein, we report the visible-light-induced photocatalytic cleavage of the alkyl aryl ether C-O bond using a carbazole-based organic photocatalyst (PC). Both benzylic and non-benzylic aryl ethers underwent C-O bond cleavage to form the corresponding phenol products. Addition of Cs2CO3 was beneficial, especially in reactions using a N-H carbazole PC. The reaction was proposed to occur via single-electron transfer (SET) from the excited-state carbazole to the substrate ether. Interaction of the N-H carbazole PC with Cs2CO3 via hydrogen bonding exists, which enables a deprotonation-assisted electron-transfer mechanism to operate. In addition, the Lewis acidic Cs cation interacts with the substrate alkyl aryl ether to activate it as an electron acceptor. The high reducing ability of the carbazole combined with the beneficial effects of Cs2CO3 made this otherwise formidable SET event possible.
- Yabuta, Tatsushi,Hayashi, Masahiko,Matsubara, Ryosuke
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p. 2545 - 2555
(2021/02/01)
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- A Bisphenolic Honokiol Analog Outcompetes Oral Antimicrobial Agent Cetylpyridinium Chloride via a Membrane-Associated Mechanism
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Targeting Streptococcus mutans is the primary focus in reducing dental caries, one of the most common maladies in the world. Previously, our groups discovered a potent bactericidal biaryl compound that was inspired by the natural product honokiol. Herein, a structure activity relationship (SAR) study to ascertain structural motifs key to inhibition is outlined. Furthermore, mechanism studies show that bacterial membrane disruption is central to the bacterial growth inhibition. During this process, it was discovered that analog C2 demonstrated a 4-fold better therapeutic index compared to the commercially available antimicrobial cetylpyridinium chloride (CPC) making it a viable alternative for oral care.
- Ochoa, Cristian,Solinski, Amy E.,Nowlan, Marcus,Dekarske, Madeline M.,Wuest, William M.,Kozlowski, Marisa C.
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- Dehydrogenative Coupling of Benzylic and Aldehydic C-H Bonds
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A photoinduced dehydrogenative coupling reaction between benzylic and aldehydic C-H bonds is reported. When a solution of an alkylbenzene and an aldehyde in ethyl acetate is irradiated with visible light in the presence of iridium and nickel catalysts, a coupled α-aryl ketone is formed with evolution of dihydrogen. An analogous C-C bond forming reaction occurs between a C-H bond next to the nitrogen of an N-methylamide and an aldehydic C-H bond to produce an α-amino ketone. These reactions provide a straightforward pathway from readily available materials leading to valued structural motifs of pharmacological relevance.
- Ishida, Naoki,Kawasaki, Tairin,Murakami, Masahiro
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supporting information
p. 3366 - 3370
(2020/03/06)
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- Photo-catalytic preparation method of bibenzyl compounds
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The invention relates to a preparation method of bibenzyl compounds. A compound represented by a formula (A) and a compound represented by a formula (C) carry out reactions under the action of an organic tungsten catalyst and an alkali in the presence of light to generate bibenzyl compounds represented by the formula (B). The method is simple and is easy to operate. The yield is high, and the application range is wide. Moreover, the invention also provides an application of a tungsten complex in organic chemical reactions as a photocatalyst.
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Paragraph 0058-0061; 0063; 0068-0071
(2020/02/27)
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- Luminescent tungsten(vi) complexes as photocatalysts for light-driven C-C and C-B bond formation reactions
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The realization of photocatalysis for practical synthetic application hinges on the development of inexpensive photocatalysts which can be prepared on a large scale. Herein an air-stable, visible-light-absorbing photoluminescent tungsten(vi) complex which can be conveniently prepared at the gram-scale is described. This complex could catalyse photochemical organic transformation reactions including borylation of aryl halides, such as aryl chloride, reductive coupling of benzyl bromides for C-C bond formation, reductive coupling of phenacyl bromides, and decarboxylative coupling of redox-active esters of alkyl carboxylic acid with high product yields and broad functional group tolerance.
- Chan, Kaai-Tung,Che, Chi-Ming,Du, Lili,Liu, Yungen,Phillips, David Lee,To, Wai-Pong,Tong, Glenna So Ming,Wu, Liang-Liang,Yu, Daohong
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p. 6370 - 6382
(2020/07/15)
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- The synergy between the CsPbBr3nanoparticle surface and the organic ligand becomes manifest in a demanding carbon-carbon coupling reaction
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We demonstrate here the suitability of CsPbBr3nanoparticles as photosensitizers for a demanding photoredox catalytic homo- and cross-coupling of alkyl bromides at room temperature by merely using visible light and an electron donor, thanks to the cooperative action between the nanoparticle surface and organic capping.
- Casadevall, Carla,Claros, Miguel,Galian, Raquel E.,Lloret-Fillol, Julio,Pérez-Prieto, Julia,Rosa-Pardo, Ignacio,Schmidt, Luciana
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supporting information
p. 5026 - 5029
(2020/05/18)
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- Ni-Catalyzed Iterative Alkyl Transfer from Nitrogen Enabled by the in Situ Methylation of Tertiary Amines
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Current methods to achieve transition-metal-catalyzed alkyl carbon-nitrogen (C-N) bond cleavage require the preformation of ammonium, pyridinium, or sulfonamide derivatives from the corresponding alkyl amines. These activated substrates permit C-N bond cleavage, and their resultant intermediates can be intercepted to affect carbon-carbon bond-forming transforms. Here, we report the combination of in situ amine methylation and Ni-catalyzed benzalkyl C-N bond cleavage under reductive conditions. This method permits iterative alkyl group transfer from tertiary amines and demonstrates a deaminative strategy for the construction of Csp3-Csp3 bonds. We demonstrate PO(OMe)3 (trimethylphosphate) to be a Ni-compatible methylation reagent for the in situ conversion of trialkyl amines into tetraalkylammonium salts. Single, double, and triple benzalkyl group transfers can all be achieved from the appropriately substituted tertiary amines. Transformations developed herein proceed via recurring events: The in situ methylation of tertiary amines by PO(OMe)3, Ni-catalyzed C-N bond cleavage, and concurrent Csp3-Csp3 bond formation.
- Nwachukwu, Chideraa Iheanyi,McFadden, Timothy Patrick,Roberts, Andrew George
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p. 9979 - 9992
(2020/09/03)
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- 1-PHENYL-2-PHENYLETHANE DERIVATIVE
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PROBLEM TO BE SOLVED: To provide a compound which has an activity of selectively activating estrogen receptor β. SOLUTION: A compound represented by the following formula (1) or a salt thereof. [In the formula, X shows a hydrogen atom or group R1/su
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Paragraph 0109-0112
(2020/08/13)
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- Nickel catalyzed deoxygenative cross-coupling of benzyl alcohols with aryl-bromides
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A nickel-catalyzed cross-electrophile coupling of benzyl alcohols with aromatic bromides has been developed. This deoxygenative cross-coupling occurs under mild reaction conditions at ambient temperature affording diarylmethanes, or 1,3-diarylpropenes from benzyl allyl alcohols. The system demonstrated good chemoselectivity tolerating an assortment of reactive functional groups.
- Kumar Chenniappan, Vinoth,Peck, Devin,Rahaim, Ronald
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supporting information
(2020/03/03)
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- Method for preparation of bibenzyl compounds by photocatalytic one-step process
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The invention relates to a brand new low-cost method for synthesis of bibenzyl compounds. The method adopts green and clean light energy as the reaction energy, and takes toluene or a toluene derivative as the raw material to prepare bibenzyl compounds under the catalysis of a solid photocatalyst. The method is carried out at room temperature, and can prepare bibenzyl compounds directly by illumination. The reaction process includes: mixing a toluene derivative, a catalyst and a solvent, then putting the mixture into a pressure-resistant quartz container (larger than 1MPa), and performing replacement with inert gas, conducting illumination stirring at room temperature, and carrying out reaction for 1 or more hour. At the end of the reaction, the catalyst can be easily separated from the reaction system and can be recycled repeatedly, the reaction product can be separated by crystallization, and the yield of bibenzyl compounds can reach 3.21g (g catalyst)h. The method can be used for direct preparation of 1, 2-diphenylethane and natural bibenzyl drugs.
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Paragraph 0045-0046
(2019/07/04)
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- Visible-Light-Driven Self-Coupling of Methylarenes Catalyzed by Ni2P?Cd0.5Zn0.5S Nanoparticles
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The Ni2P?Cd0.5Zn0.5S nanoparticles photocatalyzed self-coupling of p-xylene was reported here, and the corresponding coupling product 1,2-di-p-tolylethane was obtained. The reaction could be extended to toluene derivatives with electron-donating and electron-withdrawing substituents. Ni2P?Cd0.5Zn0.5S nanoparticles had already been characterized by XRD, ICP-AES, SEM, TEM, UV/Vis, FL, XPS. The Mott–Schottky curves of Ni2P?Cd0.5Zn0.5S were made through electrochemical methods. An active carbon free-radical was captured through ESR measurement under irradiation. The research demonstrated this photocatalytic system feasible for the self-coupling reaction of toluene derivatives.
- Yang, Dan-Dan,Hu, Jia-Jun,Zhang, Hong,Lv, Xiao-Jun,Chen, Yong,Fu, Wen-Fu
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p. 1384 - 1392
(2020/01/08)
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- Novel preparation of N-arylmethyl-N-arylmethyleneamine N-oxides from benzylic bromides with zinc and isobutyl nitrite
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Treatment of benzylic bromides with Zn and LiCl, followed by the reaction with i-butyl nitrite gave N-arylmethyl-N-arylmethyleneamine N-oxides in moderate yields. The present reaction is a novel and simple method for the preparation of nitrones from benzylic bromides, although the yields are moderate.
- Yanai, Kei,Togo, Hideo
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p. 3523 - 3529
(2019/05/24)
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- Nickel-catalyzed anti-Markovnikov hydroarylation of alkenes
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We have developed a nickel-catalyzed hydroarylation of alkenes using aryl halides as coupling partners. Excellent anti-Markovnikov selectivity is achieved with aryl-substituted alkenes and enol ethers. We also show that hydroarylation occurs with alkyl substituted alkenes to yield linear products. Preliminary examination of the reaction mechanism suggests irreversible hydrometallation as the selectivity determining step of the hydroarylation.
- Nguyen, Julia,Chong, Andrea,Lalic, Gojko
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p. 3231 - 3236
(2019/03/21)
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- Photoredox-Catalysis-Modulated, Nickel-Catalyzed Divergent Difunctionalization of Ethylene
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Divergent synthesis that enables a catalytic reaction to selectively produce different products from common substrates will allow the charting of wider chemical space and the unveiling of distinct mechanistic paradigms. A common strategy for it employs different ligands to modulate organometallic catalysts. Dramatic developments in photocatalysis have enabled previously inaccessible transformations. In particular, photoredox catalysis modulates the oxidation state of transition-metal complexes, offering enormous opportunities for methodology development. Herein, we developed a photo-mediated divergent ethylene difunctionalization via modulating oxidation states of the nickel catalyst by using different photoredox catalysts. This work will inspire new perspectives for value-added chemical synthesis using ethylene as a feedstock and shed light on photoredox-catalyst-based divergent synthesis, which fundamentally differs from ligand-controlled transition-metal catalysis.Divergent synthesis represents a powerful strategy for directly accessing different molecular scaffolds originating from the same starting materials. Access to different end products via transition-metal catalysis is conventionally achieved by ligand control. We herein demonstrate the use of ethylene feedstock and commercially available aryl halides to accomplish the divergent synthesis of 1,2-diarylethanes, 1,4-diarylbutanes, or 2,3-diarylbutanes in a highly selective fashion through the synergistic combination of nickel and photoredox catalysis. Mechanistic studies suggest that the observed selectivity was due to different active states of Ni(I) and Ni(0) modulated by Ru- and Ir-based photoredox catalysts, respectively. The ability to access different organometallic oxidation states via photoredox catalysis promises to inspire new perspectives for synergistic transition-metal-catalyzed divergent synthesis.Functionalization of ethylene without polymerization is challenging under photo-irradiation conditions. We have demonstrated that the photo-transformation of ethylene can be controllable by merging photoredox and transition-metal catalysis. In our study, the use of different photoredox catalysts was able to modulate the oxidation state of the nickel catalyst. Through different oxidation states, the nickel-catalyzed couplings proceeded via distinct pathways to generate divergent ethylene difunctionalization products selectively from the same feedstock.
- Li, Jiesheng,Luo, Yixin,Cheo, Han Wen,Lan, Yu,Wu, Jie
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supporting information
p. 192 - 203
(2019/01/21)
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- Sulfonic acid anchored on silica, SiO2@SO3H: A superior solid acid catalyst for quick and solvent-free reductive-deoxygenation of ketones with NaBH3CN
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NaBH3CN as a modified hydroborate agent and due to a strong withdrawing CN group does not show any reducing ability to reduce functional groups in the absence of acidic media (pH ~ 3–4). In this study, the immobilized sulfonic acid on silica, SiO2@SO3H, was prepared and applied as a new solid acid catalyst for extremely enhancing the reducing ability of NaBH3CN. The influence of SiO2@SO3H was highlighted by performing the quick and green reduction of structurally diverse carbonyl compounds involving aldehydes, ketones, α,β-unsaturated enals and enones, α-diketones, and acyloins to the corresponding alcohols or alkanes with NaBH3CN. By the NaBH3CN/SiO2@SO3H system, aldehydes were reduced to the corresponding alcohols and ketonic compounds to alkanes as reductive-deoxygenation products. All reduction reactions were carried out within 3 min at room temperature and under solvent-free conditions to afford the products in high to excellent yields (90–98%).
- Zeynizadeh, Behzad,Kouhkan, Mehri
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p. 1521 - 1528
(2018/11/23)
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- Nickel-Catalyzed Decarboxylative Alkylation of Aryl Iodides with Anhydrides
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We present the anhydride-based decarboxylative alkylation of aryl iodides catalyzed by nickel. This method of decarboxylative coupling works with a broad scope of aliphatic carboxylic anhydrides and tolerates synthetically useful aromatic substituents. Assisted by a redox system of pyridine N-oxide and zinc additives, the current reaction occurs under mild conditions and without the assistance of photocatalyst. Notably, this method features high chemoselectivity toward alkyl migration with mixed aliphatic/aromatic anhydrides. Thus, it provides a powerful synthetic tool to modify high-valued aliphatic carboxylic acids by converting them into mixed anhydrides using readily available aryl carboxylic acids such as p-toluic acid. We propose a catalytic cycle that involves the key steps of free radical-based decarboxylation and subsequent alkyl transfer to nickel that precedes an oxidatively induced C-C reductive elimination from Ni(III).
- Chen, Hui,Hu, Lu,Ji, Wenzhi,Yao, Licheng,Liao, Xuebin
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p. 10479 - 10485
(2018/10/24)
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- Reductive Homocoupling of Organohalides Using Nickel(II) Chloride and Samarium Metal
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A homocoupling method for organohalides and organosulfonates promoted by samarium metal and HMPA, and catalyzed by NiCl2 has been developed. Various organohalides (benzyl, aryl, heterocyclic, alkenyl and alkyl halides), α-haloacetophenones, and phenyl organosulfonates were tolerated, and the reaction afforded coupling products with high efficiency. Excellent chemoselectivity was exhibited between halides and other groups, such as ?COOH, ?NO2, halogen, heterocyclic ring, ester, and ketone groups. The stereoselectivity suggested that the reaction mechanism might involve an organosamarium species.
- Liu, Yongjun,Xiao, Shuhuan,Qi, Yan,Du, Feng
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p. 673 - 678
(2017/03/22)
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- Thermal Rearrangement of Sulfamoyl Azides: Reactivity and Mechanistic Study
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The rearrangement of sulfamoyl azides under thermal conditions to form a C-C bond while breaking two C-N bonds is reported. Mechanistic study shows that this reaction goes through a Curtius-type rearrangement to form a 1,1-diazene, then which rearranges possibly through both a concerted rearrangement process and a stepwise radical process. This rearrangement could be used in the synthesis of complex biologically active molecules, such as sterols, and piperine derivatives.
- Zou, Xiaodong,Zou, Jiaqi,Yang, Lizheng,Li, Guigen,Lu, Hongjian
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p. 4677 - 4688
(2017/05/12)
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- Cobalt-catalyzed (Z)-selective semihydrogenation of alkynes with molecular hydrogen
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Cobalt-catalyzed highly (Z)-selective semihydrogenation of alkynes using molecular H2 was developed using commercially available and cheap cobalt precursors. A variety of (Z)-alkenes were obtained in moderate to excellent selectivities [(Z)-alkene/(E)-alkene/alkane ratio up to >99 : 1 : 1] and it was found that the readily available ethylenediamine ligand is crucial in determining the selectivity.
- Chen, Caiyou,Huang, Yi,Zhang, Zongpeng,Dong, Xiu-Qin,Zhang, Xumu
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supporting information
p. 4612 - 4615
(2017/04/28)
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- Synthesis and structure–activity relationships of 1-benzylindane derivatives as selective agonists for estrogen receptor beta
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The estrogen receptor beta (ERβ) selective agonist is considered a promising candidate for the treatment of estrogen deficiency symptoms in ERβ-expressing tissues, without the risk of breast cancer, and multiple classes of compounds have been reported as
- Yonekubo, Shigeru,Fushimi, Nobuhiko,Miyagi, Takashi,Nakanishi, Osamu,Katsuno, Kenji,Ozawa, Motoyasu,Handa, Chiaki,Furuya, Noritaka,Muranaka, Hideyuki
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supporting information
p. 5895 - 5910
(2016/10/30)
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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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- An unprecedented oxidative intermolecular homo coupling reaction between two sp3C–sp3C centers under metal-free condition
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An unprecedented formation of benzylic sp3C–sp3C coupled dibenzylic products has been illustrated. The reactions have been carried out in the presence of three oxidizing reagents, i.e., diacetoxy-iodobenzene (IBDA), N-fluorobenzenesulfonimide (NFSI), and pyridine (Py) using toluene derivatives.
- Sahoo, Santosh K.
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supporting information
p. 3476 - 3480
(2016/07/15)
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- A well-defined low-valent cobalt catalyst Co(PMe3)4 with dimethylzinc: a simple catalytic approach for the reductive dimerization of benzyl halides
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Herein, we report the first catalytic version of a cobalt-catalysed reductive homocoupling of benzyl halides which proceeds with low catalyst loadings (0.5 to 5 mol%). By synthetizing each cobalt intermediate we demonstrate that reaction proceeds through two single electron transfers (SET) and that dimethylzinc is only involved in the regeneration of the catalytic species.
- Fallon, Brendan J.,Corcé, Vincent,Amatore, Muriel,Aubert, Corinne,Chemla, Fabrice,Ferreira, Franck,Perez-Luna, Alejandro,Petit, Marc
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p. 9912 - 9916
(2016/12/07)
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- Iron complexes of a bidentate picolyl-NHC ligand: Synthesis, structure and reactivity
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The synthesis, structure and reactivity of bidentate picolyl N-heterocyclic carbene (NHC) iron compounds were studied. Compounds [FeBr(HL)2]Br (1), [FeBr(HL)(HMDS)] (2) and [FeBr2(HL)] (3) (HL = 1-mesityl-3-(pyridin-2-ylmethyl)imidazol-1-ylidene, HMDS = hexamethyldisilazide) were prepared from H2LBr with suitable amounts of Fe(HMDS)2 or in situ prepared [Fe(HMDS)Br]. The deprotonation of 1 with 2 eq. of LiHMDS gave [FeL2] (4), featuring dearomatized pyridine moieties with exocyclic C-C double bonds. The protonation of 4 with 2 eq. of PPh3·HBr results in the formation of 1. Attempted deprotonation of 3 using benzyl Grignard as the base resulted in transmetalation products [FeBnBr(HL)] (5) and [FeBn2(HL)] (6). Exposure of 6 to CO resulted in the formation of diamagnetic compound [Fe(CO)3(HL)] (7) and dibenzyl ketone. Prolonged exposure of 7 to CO with heating induces pyridine dissociation, affording [Fe(CO)4(HL-κC)] (8). Treatment of compound 6 with an equimolar amount of p-methoxybenzyl bromide yielded homo- and cross-coupling products.
- Liang, Qiuming,Janes, Trevor,Gjergji, Xhoana,Song, Datong
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supporting information
p. 13872 - 13880
(2016/09/09)
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- Combining visible light catalysis and transfer hydrogenation for in situ efficient and selective semihydrogenation of alkynes under ambient conditions
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By combining visible light catalysis and transfer hydrogenation, we are able to convert a series of alkynes to their corresponding alkenes in high chemical yields. Then the visible light catalytic transfer hydrogenation reaction can couple photoisomerization to produce E-alkenes or Z-alkenes exclusively depending on the aryl or alkyl substituted alkynes.
- Zhong, Jian-Ji,Liu, Qiang,Wu, Cheng-Juan,Meng, Qing-Yuan,Gao, Xue-Wang,Li, Zhi-Jun,Chen, Bin,Tung, Chen-Ho,Wu, Li-Zhu
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supporting information
p. 1800 - 1803
(2016/02/05)
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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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- Dioxomolybdenum Complexes as Excellent Catalysts for the Deoxygenation of Aryl Ketones to Aryl Alkenes
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This work describes a new methodology for the selective deoxygenation of aryl ketones to the corresponding aryl alkenes catalyzed by dioxomolybdenum complexes using silanes as reducing agents. The best results were obtained with the system PhSiH3/MoO2Cl2(H2O)2 (5-10 mol %), which was very efficient for the deoxygenation of a large variety of aryl ketones to alkenes in excellent yields. This new methodology has the advantages of using an inexpensive, environmentally friendly, easily prepared, and air-stable catalyst in ether solution.
- Fernandes, Tiago A.,Fernandes, Ana C.
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p. 3503 - 3507
(2015/11/10)
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- E-Selective Semi-Hydrogenation of Alkynes by Heterobimetallic Catalysis
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A unique cooperative H2 activation reaction by heterobimetallic (NHC)M′-MCp(CO)2 complexes (NHC = N-heterocyclic carbene, M′ = Cu or Ag, M = Fe or Ru) has been leveraged to develop a catalytic alkyne semi-hydrogenation transformation. The optimal Ag-Ru catalyst gives high selectivity for converting alkynes to E-alkenes, a rare selectivity mode for reduction reactions with H2. The transformation is tolerant of many reducible functional groups. Computational analysis of H2 activation thermodynamics guided rational catalyst development. Bimetallic alkyne hydrogenation and alkene isomerization mechanisms are proposed.
- Karunananda, Malkanthi K.,Mankad, Neal P.
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supporting information
p. 14598 - 14601
(2015/12/08)
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- Heterogeneous photocatalytic C-C coupling: Mechanism of plasmon-mediated reductive dimerization of benzyl bromides by supported gold nanoparticles
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The use of gold nanoparticles supported on TiO2 (Au@TiO2) as photocatalysts was extended to include photoinduced reductive C-C coupling. Surface plasmon excitation of supported AuNPs in the presence of an amine leads to the C-C coupling of a variety of substituted benzyl bromides at room temperature with good yields in a free radical-mediated reaction. The overall efficiency of the C-C coupling is largely dependent on the nature of the amine used.
- Lanterna, Anabel E.,Elhage, Ayda,Scaiano, Juan C.
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p. 4336 - 4340
(2015/09/01)
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- Photogenerated α,n-didehydrotoluenes from chlorophenylacetic acids at physiological pH
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Aromatic diradicals are recognized as promising intermediates for DNA cleavage, but their formation has thus far been limited to the Bergman and Myers-Saito cycloaromatizations. We report here the phototriggered generation of all isomers of the potential DNA-cleaving α,n-didehydrotoluene diradicals at physiological pH, accomplished by the irradiation of chlorophenylacetic acids under mild conditions. The desired diradicals were formed upon photolysis of the chosen aromatic in aqueous phosphate buffer solution (pH = 7.3), with the consecutive elimination of biologically compatible chloride ion and carbon dioxide. Theoretical simulations reveal that the efficient decarboxylation of the primarily generated phenyl cations involves a previously not known diradical structure.
- Ravelli, Davide,Protti, Stefano,Fagnoni, Maurizio
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supporting information
p. 852 - 858
(2015/03/05)
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- Identification of dihydrostilbenes in Pholidota chinensis as a new scaffold for GABAA receptor modulators
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A dichloromethane extract of stems and roots of Pholidota chinensis (Orchidaceae) enhanced GABA-induced chloride currents (IGABA) by 132.75 ± 36.69% when tested at 100 μg/mL in a two-microelectrode voltage clamp assay, on Xenopus laevis oocytes
- Rueda, Diana C.,Sch?ffmann, Angela,De Mieri, Maria,Raith, Melanie,J?hne, Evelyn A.,Hering, Steffen,Hamburger, Matthias
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p. 1276 - 1284
(2014/03/21)
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- A clean and selective radical homocoupling employing carboxylic acids with titania photoredox catalysis
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A titania photoredox catalysis protocol was developed for the homocoupling of C-centered radicals derived from carboxylic acids. Intermolecular reactions were generally efficient and selective, furnishing the desired dimers in good yields under mild neutral conditions. Selective cross-coupling with two acids proved unsuccessful. An intra-molecular adaptation enabled macrocycles to be prepared, albeit in modest yields. (Chemical Equation Presented).
- Manley, David W.,Walton, John C.
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supporting information
p. 5394 - 5397
(2015/02/19)
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- Nickel-Catalyzed Kumada Coupling of Benzyl Chlorides and Vinylogous Derivatives
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Conditions for the fast Ni-catalyzed Kumada-type cross-coupling of functionalized benzyl and allyl chlorides with alkylmagnesium reagents were discovered. The use of Ni(acac)2-TMEDA (acac = acetylacetonate, TMEDA = N,N,N′,N′-tetramethyl-1,2-ethylenediamine) allows the presence of reactive functional groups on the electrophile. On the other hand, the use of diallyl ether was shown to provide fast coupling at low temperature with a low catalyst loading. The reaction seems to follow a radical pathway.
- Soler-Yanes, Rita,Guisán-Ceinos, Manuel,Bu?uel, Elena,Cárdenas, Diego J.
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supporting information
p. 6625 - 6629
(2016/02/19)
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- Understanding the reactivity of enol ether radical cations: Investigation of anodic four-membered carbon ring formation
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The reactivity of enol ether radical cations was investigated in anodic four-membered carbon ring formations, advancing the mechanistic understanding of these reactions. The mono-ring-containing aromatic cations were reduced through inter- or intramolecular electron transfer to give mono- or bis-ring-containing compounds, respectively. Small structural changes in the hydrocarbon linkers tethering two aromatic rings exerted a powerful effect on the efficiency of such electron transfer events.
- Yamaguchi, Yusuke,Okada, Yohei,Chiba, Kazuhiro
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p. 2626 - 2638
(2013/04/23)
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- Easy eco-friendly phenonium ion production from phenethyl alcohols in dimethyl carbonate
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An efficient and simple one-pot procedure for selective etherification of 2-aryl-ethylalcohols has been achieved through Amberlyst 15-catalyzed reaction in dimethyl carbonate (DMC). Moreover, the polymer catalyst could be recovered and reused with no effect on its activity. The reaction mechanism involves the formation of phenonium ion which has been demonstrated by a C-C bond forming reaction. Theoretical studies are in agreement with and thus explain experimental results.
- Barontini,Proietti Silvestri,Nardi,Bovicelli,Pari,Gallucci,Spezia,Righi
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supporting information
p. 5004 - 5006
(2013/08/28)
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- Ni-catalyzed reductive homocoupling of unactivated alkyl bromides at room temperature and its synthetic application
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A room-temperature Ni-catalyzed reductive approach to homocoupling of unactivated primary, secondary, and tertiary alkyl bromides is described. The catalytic system can be easily generated from air-stable and cheap materials and demonstrates broad functional group tolerance, thus allowing facile access to useful dimeric triterpene and lignan-like molecules. Moreover, the dimerization of tertiary bromide 6 efficiently establishes sterically hindered vicinal quaternary carbons (C3a and C3a′), which is a key linkage of intriguing bispyrrolo[2,3-b]indoline alkaloids, thereby enabling us to complete the total syntheses of racemic chimonanthine (9) and folicanthine (10). In addition, this dimerization method can be expanded to the highly stereoselective synthesis of bisperhydrofuro[2,3-b]furan (5a) and the dimeric spiroketal 5b, signifying the involvement of possible radical species.
- Peng, Yu,Luo, Long,Yan, Chang-Song,Zhang, Jian-Jian,Wang, Ya-Wen
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p. 10960 - 10967
(2013/11/19)
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- Iron nanoparticle-promoted Cu (I)-catalysed homocoupling of arylmethyl halides for the synthesis of 1,2-diarylethanes
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Carbon-carbon bond formation is important in organic synthesis for the preparation of natural products, organic materials and polymers and so on. An efficient and mild reductive homocoupling of arylmethyl halides is now described. Treatment of various benzylic halides in the presence of zero valent iron nanoparticles (nZVI) and a catalytic amount of CuBr in air and water at room temperature afforded 1,2-diarylethanes in excellent yields.
- Shekarriz, Marzieh,Adib, Mehdi,Biabani, Tayebe,Taghipoor, Sohrab
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experimental part
p. 29 - 30
(2012/04/04)
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- Palladium-catalyzed coupling reactions of (ArCH2)Ti(O-i-Pr) 3 with aromatic or heteroaromatic bromides
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Three benzyltitanium compounds of (ArCH2)Ti(O-i-Pr)3 (Ar = Ph (1a), 4-MeOC6H4 (1b), 4-FC6H 4 (1c)) were prepared and used as benzyl nucleophiles for coupling reactions with aromatic or heteroaromatic bromides. The simple catalytic system of 1 mol % Pd(OAc)2 and 2 mol % PCy3 worked efficiently for a wide variety of aromatic bromides, producing diarylmethanes in good to excellent yields of up to 96%. Coupling reactions of hindered aromatic bromides or aromatic bromides containing electron-withdrawing substituents were slower over longer reaction times of 3-6 h. Reactions of heteroaromatic bromides of bromopyridines, bromofurans, or bromothiophenes with benzyl reagents of 1a or 1b required either longer reaction times of 12-24 h or a higher reaction temperature of 80 °C, producing pyridyl-, furyl-, and thienyl-arylmethanes in moderate yields.
- Chang, Shu-Ting,Li, Qinghan,Chiang, Ruei-Tang,Gau, Han-Mou
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experimental part
p. 3956 - 3962
(2012/07/02)
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- Ti-catalyzed homolytic opening of ozonides: A sustainable C-C bond-forming reaction
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The unprecedented homolytic opening of ozonides promoted and catalyzed by titanocene(III) is reported. This novel reaction proceeds at room temperature under neutral, mild conditions compatible with many functional groups and provides carbon radicals suitable to form C-C bonds via both homocoupling and cross-coupling processes. The procedure has been advantageously exploited for the straightforward synthesis of the natural product brittonin A.
- Rosales, Antonio,Munoz-Bascon, Juan,Lopez-Sanchez, Cristobal,Alvarez-Corral, Miriam,Munoz-Dorado, Manuel,Rodriguez-Garcia, Ignacio,Oltra, J. Enrique
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experimental part
p. 4171 - 4176
(2012/06/18)
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- Unsurpassed cage effect for the photolysis of dibenzyl ketones in water-soluble dendrimers
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Amphiphilic water-soluble poly(alkyl aryl ether) dendrimers Gn (n = 1-3) with charge-neutral tetraethylene glycol monomethyl ethers at their periphery were synthesized as microreactors to control the photochemical reactions of dibenzyl ketone derivatives in aqueous solutions. Photophysical studies demonstrated that Gn can encapsulate organic molecules and provide a hydrophobic microenvironment. The product distribution of photolysis of dibenzyl ketone derivatives can be successfully controlled by encapsulating the substrates within dendrimers, and an unsurpassed cage effect of 1.00 is reached in high generation dendrimers, revealing that a thick and compact "shell" was formed at the periphery of the dendrimers. The cage effect is also significantly influenced by the substituent at the para-position of the guest molecules. The higher generation dendrimers exhibit a better confined microenvironment and the aggregates possess more compact cavities to "lock" the guests than the corresponding unimolecular dendrimers. After photolysis, the separation of products can be easily achieved by extracting from the dendrimer solutions and the dendrimers are simply recovered and reused.
- Yuan, Zhao,Chen, Jinping,Zeng, Yi,Li, Ying-Ying,Han, Yongbin,Li, Yi
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experimental part
p. 6256 - 6264
(2011/10/09)
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- Facile and efficient reductive homocoupling of benzyl and aryl halides catalyzed by ionic liquid [C12mim][CuCl2] in the presence of metallic zinc and copper
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A facile and efficient synthesis of bibenzyl and biaryl derivatives by reductive homocoupling reaction is described. Treatment of benzyl and aryl halides with metallic zinc and copper powder in the presence of a catalytic amount of [C12mim][CuCl2] under ligand- and base-free conditions gives the corresponding bibenzyls and biaryls in good to high yields. The product can be isolated by a simple extraction with organic solvent, and the catalytic system can be recycled or reused without any significant loss of catalytic activity.
- Hu, Yu-Lin,Li, Fu,Gu, Guo-Liang,Lu, Ming
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experimental part
p. 467 - 473
(2011/12/05)
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- Catalytic double C-Cl bond activation in CHlby iron(III) salts with grignard reagents
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Cross-coupling of Grignard reagents with dichloromethane is achieved using iron(III) catalysts. Aryl- and benzylmagnesium bromides show a range of activity toward double C-Cl bond activation resulting in the insertion of methylene fragments between two equivalents of the nucleophilic partner. Georg Thieme Verlag Stuttgart.
- Qian, Xin,Kozak, Christopher M.
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experimental part
p. 852 - 856
(2011/06/21)
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- Raney Ni-Al alloy-mediated reduction of benzils in wate
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Raney Ni-Al alloy in a dilute aqueous alkaline solution has been shown to be a powerful reducing agent and is highly effective for the reduction of alkylbenzils and alkoxybenzils to afford the corresponding 1,2-diarylethers at 90°C, in the absence of organic solvents. 4,4'-Dinitrobenzil was transformed selectively to 1,2-bis(4-aminophenyl) ethane.
- Liu, Guo-Bin,Zhao, Hong-Yun,Dai, Lu,Thiemann, Thies,Tashiro, Hideki,Tashiro, Masashi
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experimental part
p. 579 - 581
(2010/02/28)
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