- Iridium-catalyzed C-H coupling reaction of heteroaromatic compounds with bis(pinacolato)diboron: Regioselective synthesis of heteroarylboronates
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The C-H coupling of aromatic heterocycles with bis(pinacolato)diboron was carried out in octane at 80-100°C in the presence of a 1/2[IrCl(COD)]2-(4,4′-di-tert-butyl-2,2′-bipyridine) catalyst (3 mol%). The reactions of five-membered substrates such as thiophene, furan, pyrrole, and their benzo-fused derivatives exclusively produced 2-borylated products, whereas those of six-membered heterocycles including pyridine and quinoline selectively occurred at the 3-position. Regioselective synthesis of bis(boryl)heteroaromatics was also achieved by using an almost equimolar amount of substrates and the diboron.
- Takagi, Jun,Sato, Kazuaki,Hartwig, John F,Ishiyama, Tatsuo,Miyaura, Norio
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- Light- and Manganese-Initiated Borylation of Aryl Diazonium Salts: Mechanistic Insight on the Ultrafast Time-Scale Revealed by Time-Resolved Spectroscopic Analysis
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Manganese-mediated borylation of aryl/heteroaryl diazonium salts emerges as a general and versatile synthetic methodology for the synthesis of the corresponding boronate esters. The reaction proved an ideal testing ground for delineating the Mn species responsible for the photochemical reaction processes, that is, involving either Mn radical or Mn cationic species, which is dependent on the presence of a suitably strong oxidant. Our findings are important for a plethora of processes employing Mn-containing carbonyl species as initiators and/or catalysts, which have considerable potential in synthetic applications.
- Firth, James D.,Hammarback, L. Anders,Burden, Thomas J.,Eastwood, Jonathan B.,Donald, James R.,Horbaczewskyj, Chris S.,McRobie, Matthew T.,Tramaseur, Adam,Clark, Ian P.,Towrie, Michael,Robinson, Alan,Krieger, Jean-Philippe,Lynam, Jason M.,Fairlamb, Ian J. S.
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supporting information
p. 3979 - 3985
(2021/02/03)
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- Polysulfide Anions as Visible Light Photoredox Catalysts for Aryl Cross-Couplings
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Polysulfide anions are endowed with unique redox properties, attracting considerable attentions for their applications in alkali metals-sulfur batteries. However, the employment of these anionic species in redox catalysis for small molecule synthesis remains underdeveloped due to their moderate-poor electrochemical potential in the ground state, whereas some of them are characterized by photoabsorptions in visible spectral regions. Herein, we disclose the use of polysulfide anions as visible light photoredox catalysts for aryl cross-coupling reactions. The reaction design enables single-electron reduction of aryl halides upon the photoexcitation of tetrasulfide dianions (S42-). The resulting aryl radicals are engaged in (hetero)biaryl cross-coupling, borylation, and hydrogenation in a redox catalytic regime involving S4?-/S42- and S3?-/S32- redox couples.
- Li, Haoyu,Tang, Xinxin,Pang, Jia Hao,Wu, Xiangyang,Yeow, Edwin K. L.,Wu, Jie,Chiba, Shunsuke
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supporting information
p. 481 - 487
(2021/01/13)
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- Transformations of Aryl Ketones via Ligand-Promoted C?C Bond Activation
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The coupling of aromatic electrophiles (aryl halides, aryl ethers, aryl acids, aryl nitriles etc.) with nucleophiles is a core methodology for the synthesis of aryl compounds. Transformations of aryl ketones in an analogous manner via carbon–carbon bond activation could greatly expand the toolbox for the synthesis of aryl compounds due to the abundance of aryl ketones. An exploratory study of this approach is typically based on carbon–carbon cleavage triggered by ring-strain release and chelation assistance, and the products are also limited to a specific structural motif. Here we report a ligand-promoted β-carbon elimination strategy to activate the carbon–carbon bonds, which results in a range of transformations of aryl ketones, leading to useful aryl borates, and also to biaryls, aryl nitriles, and aryl alkenes. The use of a pyridine-oxazoline ligand is crucial for this catalytic transformation. A gram-scale borylation reaction of an aryl ketone via a simple one-pot operation is reported. The potential utility of this strategy is also demonstrated by the late-stage diversification of drug molecules probenecid, adapalene, and desoxyestrone, the fragrance tonalid as well as the natural product apocynin.
- Dai, Hui-Xiong,Li, Hanyuan,Li, Ling-Jun,Liu, Qi-Sheng,Ma, Biao,Wang, Mei-Ling,Wang, Xing,Wang, Zhen-Yu,Xu, Hui
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p. 14388 - 14393
(2020/07/06)
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- Efficient Synthesis of Aryl Boronates via Cobalt-Catalyzed Borylation of Aryl Chlorides and Bromides
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An efficient catalytic system based on a Co(II)-NHC precursor has been developed for the cross coupling of bis(pinacolato)diboron with aryl halides including aryl chlorides, affording the aryl boronates in good to excellent yields. A wide range of functional groups are tolerated under mild reaction conditions. The reaction shows excellent chemoselectivity for bromide over chloride. Preliminary mechanistic investigations show that the catalytic cycle may rely on a cobalt(I)-(III) redox couple.
- Verma, Piyush Kumar,Mandal, Souvik,Geetharani
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p. 4049 - 4054
(2018/05/22)
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- Chemoselective coupling of 1,1-bis[(pinacolato)boryl]alkanes for the transition-metal-frec borylation of aryl and vinyl halides: A combined experimental and theoretical investigation
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A new transition-metal-frec borylation of aryl and vinyl halides using l,l-bis[(pinacolato)boryl]alkanes as boron sources is described. In this transformation one of the boron groups from 1,1-bis[(pinacolato)boryl]alkanes is selectively transferred to aryl and vinyl halides in the presence of sodium tert-butoxide as the only activator to form organoboronate esters. Under the developed borylation conditions, a broad range of organohalides are borylated with excellent chemo-selectivity and functional group compatibility, thus offering a rare example of a transition-metal-frec borylation protocol. Experimental and theoretical studies have becn performed to elucidate the reaction mechanism, revealing the unusual formation of Lewis acid/base adduct betwecn organohalides and α-borylcarbanion, generated in situ from the reaction of l,l-bis[(pinacolato)boryl]alkanes with an alkoxide base, to facilitate the borylation reactions.
- Lee, Yeosan,Baek, Seung-Yeol,Park, Jinyoung,Kim, Seoung-Tae,Tussupbayev, Samat,Kim, Jeongho,Baik, Mu-Hyun,Cho, Seung Hwan
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p. 975 - 984
(2017/05/16)
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- Heterocyclic compound with Wnt signal path inhibitory activity and application thereof
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The invention provides a heterocyclic compound with Wnt signal path inhibitory activity. The heterocyclic compound and chemically acceptable salt, isotope, isomer and a crystal structure thereof are provided with a structure shown as the general formula I (see the formula in the description). The invention further provides application of the heterocyclic compound with the Wnt signal path inhibitory activity. The heterocyclic compound with the Wnt signal path inhibitory activity serves as effective antagonist of a Wnt signal path, and can be used for treating or preventing diseases caused by abnormity of the Wnt signal path.
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Paragraph 0058; 0059; 0060; 0061
(2016/10/08)
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- Condensed derivatives of imidazole useful as pharmaceuticals
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The invention relates to the compounds (I) and their acids and bases salts: wherein: the dotted line indicates a double bond; X is N or C-R1 and Y is N or C-R2, X and Y not being simultaneously N; A is selected from the group consisting of phenyl, naphthyl and (5-11) membered monocyclic or bicyclic unsaturated cycle or heterocycle possibly substituted as defined in the application, and A can also comprise either a further (4-7) membered heterocycle, said heterocycle being a monocycle, fused, saturated or unsaturated, the polycyclic system then comprising up to 14 members and up to 5 heteroatoms selected from N, O and S; B is Hydrogen or a substituent as defined in the application, or B is a (4-10) membered mono or bicyclic saturated or unsaturated heterocycle containing 1-3 heteroatoms selected from N, O and S, and possibly substituted as defined in the application; B not being Hydrogen when X is N and Y is C-R2; R1 is Hydrogen or a substituent as defined in the application; B and R1 cannot be simultaneously Hydrogen; R2 is Hydrogen or Halogen; their preparation, their use in the antibacterial prevention and therapy, alone or in association with antibacterials, antivirulence agents or drugs reinforcing the host innate immunity, and pharmaceutical compositions and associations containing them.
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Paragraph 0446; 0725
(2015/09/23)
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- Boryl substitution of functionalized aryl-, heteroaryl- and alkenyl halides with silylborane and an alkoxy base: expanded scope and mechanistic studies
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A transition-metal-free method has been developed for the boryl substitution of functionalized aryl-, heteroaryl- and alkenyl halides with a silylborane in the presence of an alkali-metal alkoxide. The base-mediated boryl substitution of organohalides with a silylborane was recently reported to provide the corresponding borylated products in good to high yields, and exhibit good functional group compatibility and high tolerance to steric hindrance. In this study, the scope of this transformation has been extended significantly to include a wide variety of functionalized aryl-, heteroaryl- and alkenyl halides. In particular, the boryl substitution of (E)- and (Z)-alkenyl halides proceeded smoothly to afford the corresponding alkenyl boronates in good to high yields with retention of the configuration using modified reaction conditions. The results of the mechanistic studies suggest that this boryl substitution proceeds via a carbanion-mediated mechanism.
- Yamamoto, Eiji,Ukigai, Satoshi,Ito, Hajime
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p. 2943 - 2951
(2015/06/17)
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- SiliaCat diphenylphosphine palladium(II) catalyzed borylation of aryl halides
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We investigate the heterogeneously catalyzed direct synthesis of boronic acid pinacol esters using a wide range of aryl chlorides, bromides, and iodides, and bis(pinacolato)diboron as the borylating agent over the sol-gel entrapped SiliaCat diphenylphosphine palladium(II) catalyst. Optimization of the reaction conditions, scale-up of the optimized process, and analysis of palladium leaching enabled us to establish a new selective route for direct access to a diverse set of boronic acid pinacol esters. Clean borylation for scale-up: With the easy access and broad availability of diverse borylated species, the Suzuki-Miyaura reaction has become routine in industry and in research labs. We report a new selective route for direct access to a diverse set of boronic acid pinacol esters over the sol-gel entrapped SiliaCat diphenylphosphine palladium(II) catalyst that can be easily scaled-up.
- Pandarus, Valerica,Marion, Olivier,Gingras, Genevieve,Beland, Francois,Ciriminna, Rosaria,Pagliaro, Mario
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p. 1340 - 1348
(2014/05/20)
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- Efficient synthesis of aryl boronates via zinc-catalyzed cross-coupling of alkoxy diboron reagents with aryl halides at room temperature
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A zinc(II)/NHC system catalyzes the borylation of aryl halides with diboron (4) reagents in the presence of KOMe at rt. This transformation can be applied to a broad range of substrates with high functional group compatibility. Radical scavenger experiments do not support a radical-mediated process.
- Bose, Shubhankar Kumar,Marder, Todd B.
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supporting information
p. 4562 - 4565
(2015/01/08)
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- Synthesis of pinacol arylboronates from aromatic amines: A metal-free transformation
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A metal-free borylation process based on Sandmeyer-type transformation using arylamines derivatives as the substrates has been developed. Through optimization of the reaction conditions, this novel conversion can be successfully applied to a wide range of aromatic amines, affording borylation products in moderate to good yields. Various functionalized arylboronates, which are difficult to access by other methods, can be easily obtained with this metal-free transformation. Moreover, this transformation can be followed by Suzuki-Miyaura cross-coupling without purification of the borylation products, which enhances the practical usefulness of this method. A possible reaction mechanism involving radical species has been proposed.
- Qiu, Di,Jin, Liang,Zheng, Zhitong,Meng, He,Mo, Fanyang,Wang, Xi,Zhang, Yan,Wang, Jianbo
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p. 1923 - 1933
(2013/03/29)
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- PROCESS FOR PRODUCTION OF HETEROARYL-TYPE BORON COMPOUNDS WITH IRIDIUM CATALYST
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The present invention provides an economically and industrially superior simple process that enables the selective production of an aromatic heterocyclic monoboron compound and aromatic heterocyclic diboron compound at a satisfactory yield and in a desired ratio by reacting an aromatic heterocyclic compound and a boron compound in a single step under mild conditions while changing only the charged ratios of the raw materials. The present invention provides a production process of a heteroaryl mono- or diboron compound comprising an aromatic heterocyclic compound and a boron compound in the form of bis(pinacolate)diboron or pinacolate diborane in the presence of a iridium-containing catalyst and a ligand such as a bipyridyl ligand.
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