- 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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supporting information
p. 6107 - 6116
(2021/02/01)
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- Photoredox Heterobimetallic Dual Catalysis Using Engineered Covalent Organic Frameworks
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The functionalization of an imine-based layered covalent organic framework (COF), containing phenanthroline units as ligands, has allowed the obtention of a heterobimetallated material. Photoactive Ir and Ni fragments were immobilized within the porous structure of the COF, enabling heterogeneous light-mediated Csp3-Csp2cross-couplings. As radical precursors, potassium benzyl- and alkoxy-trifluoroborates, organic silicates, and proline derivatives were employed, which brings out the good versatility ofIr,Ni@Phen-COF. Moreover, in all the studied cases, an enhanced activity and stability have been observed in comparison with analogous homogenous systems.
- Alemán, José,Imaz, Inhar,López-Magano, Alberto,Mas-Ballesté, Rubén,Maspoch, Daniel,Ortín-Rubio, Borja
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p. 12344 - 12354
(2021/10/12)
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- Photo-Ni-Dual-Catalytic C(sp2)-C(sp3) Cross-Coupling Reactions with Mesoporous Graphitic Carbon Nitride as a Heterogeneous Organic Semiconductor Photocatalyst
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The synergistic combination of a heterogeneous organic semiconductor mesoporous graphitic carbon nitride (mpg-CN) and a homogeneous nickel catalyst with visible-light irradiation at room temperature affords the C(sp2)-C(sp3) cross-co
- Antonietti, Markus,Ghosh, Indrajit,K?nig, Burkhard,Khamrai, Jagadish,Savateev, Aleksandr
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p. 3526 - 3532
(2020/04/09)
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- Development of Versatile Sulfone Electrophiles for Suzuki-Miyaura Cross-Coupling Reactions
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The development of fluorinated sulfone derivatives as versatile electrophiles for Suzuki-Miyaura cross-coupling reactions is described. Introducing electron-withdrawing groups on the aryl ring of the sulfone facilitates the Pd-catalyzed activation of C-SO2 bonds. Cross-coupling reactions with fluorinated sulfone electrophiles are reported, leading to a variety of multiply arylated products in good yields. The reactivity of this unusual electrophile is benchmarked versus common electrophiles and its use in iterative cross-couplings for concise synthesis of biologically active molecules is described.
- Nambo, Masakazu,Keske, Eric C.,Rygus, Jason P. G.,Yim, Jacky C.-H.,Crudden, Cathleen M.
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p. 1108 - 1112
(2017/08/09)
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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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- Direct C(sp2)-C(sp3) cross-coupling of diaryl zinc reagents with benzylic, primary, secondary, and tertiary alkyl halides
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The direct C(sp2)-C(sp3) cross-coupling of diaryl zinc reagents with benzylic, primary, secondary, and tertiary alkyl halides proceeded in the absence of coordinating ethereal solvents at ambient temperature without the addition of a catalyst. The C(sp2)-C(sp3) cross-coupling showed excellent functional-group tolerance, and products were isolated in high yields, generally without the requirement for purification by chromatography. This process represents an expedient, operationally simple method for the construction of new C(sp2)-C(sp3) bonds. Zinc and you'll miss it. Direct C(sp2)-C(sp3) cross-coupling of diaryl zinc reagents with alkyl halides proceeded rapidly at ambient temperature without a coordinating ethereal solvent or an added catalyst (see scheme). This versatile, operationally simple approach to C(sp2)-C(sp3) bond formation enables the expedient construction of a diverse array of carbon-based structural motifs.
- Dunsford, Jay J.,Clark, Ewan R.,Ingleson, Michael J.
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supporting information
p. 5688 - 5692
(2015/05/19)
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- Single-electron transmetalation in organoboron cross-coupling by photoredox/nickel dual catalysis
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The routine application of Csp3-hybridized nucleophiles in cross-coupling reactions remains an unsolved challenge in organic chemistry. The sluggish transmetalation rates observed for the preferred organoboron reagents in such transformations are a consequence of the two-electron mechanism underlying the standard catalytic approach. We describe a mechanistically distinct single-electron transfer-based strategy for the activation of organoboron reagents toward transmetalation that exhibits complementary reactivity patterns. Application of an iridium photoredox catalyst in tandem with a nickel catalyst effects the cross-coupling of potassium alkoxyalkyl- and benzyltrifluoroborates with an array of aryl bromides under exceptionally mild conditions (visible light, ambient temperature, no strong base). The transformation has been extended to the asymmetric and stereoconvergent cross-coupling of a secondary benzyltrifluoroborate.
- Tellis, John C.,Primer, David N.,Molander, Gary A.
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p. 433 - 436
(2014/08/05)
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- Extremely efficient cross-coupling of benzylic halides with aryltitanium tris(isopropoxide) catalyzed by low loadings of a simple palladium(II) acctate/Tris(p-tolyl)phosphine system
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Highly efficient coupling reactions of benzylic bromides or chlorides with aryltitanium tris(isopropoxide) [ArTi(O-i-Pr)3] catalyzed by a simple palladium(II) Acctate/tris(p-tolyl)phosphine [Pd(OAc)2/ P(p-tolyl)3] system are reported. The coupling reactions proceed in general at room temperature employing low catalyst loadings of 0.02 to 0.2 mol%, affording coupling products in excellent yields of up to 99%. For benzylic bromides bearing strong electronwithdrawing cyano (CN) or trifluoromethyl (CF 3) substituents, the reactions require a higher catalyst loading of 1 mol%, or the reactions are carried out at 60°C. The catalytic system also tolerates (1-bromoethyl)benzene bearing β-hydrogen atoms while using a catalyst loading of 1 mol% to afford the coupling product in a 70% yield.
- Chen, Chi-Ren,Zhou, Shuangliu,Biradar, Deepak Baburao,Gau, Han-Mou
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experimental part
p. 1718 - 1727
(2010/09/18)
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- Structure-activity relationship studies on 1-[2-(4- phenylphenoxy)ethyl]pyrrolidine (SC-22716), a potent inhibitor of leukotriene A4 (LTA4) hydrolase
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Leukotriene B4 (LTB4) is a pro-inflammatory mediator that has been implicated in the pathogenesis of a number of diseases including inflammatory bowel disease (IBD) and psoriasis. Since the action of LTA4 hydrolase is the rate-limiting step for LTB4 production, this enzyme represents an attractive pharmacological target for the suppression of LTB4 production. From an in- house screening program, SC-22716 (1, 1-[2-(4- phenylphenoxy)ethyl]pyrrolidine) was identified as a potent inhibitor of LTA4 hydrolase. Structure-activity relationship (SAR) studies around this structural class resulted in the identification of a number of novel, potent inhibitors of LTA4 hydrolase, several of which demonstrated good oral activity in a mouse ex vivo whole blood assay.
- Penning, Thomas D.,Chandrakumar, Nizal S.,Chen, Barbara B.,Chen, Helen Y.,Desai, Bipin N.,Djuric, Stevan W.,Docter, Stephen H.,Gasiecki, Alan F.,Haack, Richard A.,Miyashiro, Julie M.,Russell, Mark A.,Yu, Stella S.,Corley, David G.,Durley, Richard C.,Kilpatrick, Brian F.,Parnas, Barry L.,Askonas, Leslie J.,Gierse, James K.,Harding, Elizabeth I.,Highkin, Maureen K.,Kachur, James F.,Kim, Suzanne H.,Krivi, Gwen G.,Villani-Price, Doreen,Pyla, E. Yvonne,Smith, Walter G.,Ghoreishi-Haack, Nayereh S.
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p. 721 - 735
(2007/10/03)
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- Synthesis of diaryl methanes by Friedel-Craft condensation of benzalazines with aromatic hydrocarbons
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The Friedel-Craft condensation between benzalazines and aromatic hydrocarbons provide a convenient method for the preparation of unsymmetrical diaryl methanes.
- Mathew,Bhattacharjee,Myrboh
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p. 1795 - 1800
(2007/10/02)
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