The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Webster L Santos - One of the best experts on this subject based on the ideXlab platform.
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substrate assisted transition metal free diboration of alkynamides with mixed Diboron regio and stereoselective access to trans 1 2 vinylDiboronates
Angewandte Chemie, 2017Co-Authors: Astha Verma, Carla Slebodnick, Russell F Snead, Yumin Dai, Yinuo Yang, Fu Yao, Webster L SantosAbstract:A substrate-assisted diboration of alkynamides using the unsymmetrical pinacolato-1,8-diaminonaphthalenato Diboron (pinBBdan) is described. The transition-metal-free reaction proceeds in a regio- and stereoselective fashion to exclusively afford trans-vinylDiboronates in good to excellent yields. Notably, Bdan and Bpin are installed on the α- and β-carbon atoms, respectively.
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unexpected copper ii catalysis catalytic amine base promoted β borylation of α β unsaturated carbonyl compounds in water
Organic Letters, 2012Co-Authors: Steven B Thorpe, Joseph A Calderone, Webster L SantosAbstract:Using bis(pinacolato)Diboron, catalytic amounts of CuII, and various amine bases in water under atmospheric conditions at rt, acyclic and cyclic α,β-unsaturated ketones and esters are β-borylated in up to 98% yield. Mechanistic investigations using UV–vis spectroscopy, 11B NMR, and solvent kinetic isotope effect suggest that the role of the amine is not only to coordinate to CuII but also to activate a nucleophilic water molecule to form the reactive sp2–sp3 Diboron complex.
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regio and stereoselective copper catalyzed β borylation of allenoates by a preactivated Diboron
ChemInform, 2011Co-Authors: Steven B Thorpe, Xi Guo, Webster L SantosAbstract:Mild and efficient copper-catalyzed borylation of electron-deficient allenoates (I) using the sp2-sp3 mixed hybridized Diboron compound (II) regioselectively installs a boron moiety on the β-position with complete stereocontrol.
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structure and reactivity of a preactivated sp2 sp3 Diboron reagent catalytic regioselective boration of α β unsaturated conjugated compounds
Journal of Organic Chemistry, 2011Co-Authors: Ming Gao, Christian Kleeberg, Steven B Thorpe, Carla Slebodnick, Todd B Marder, Webster L SantosAbstract:A novel sp2–sp3 Diboron reagent has been developed for the copper-catalyzed β-boration of α,β-unsaturated conjugated compounds. The reaction proceeds under mild conditions with various substrates, i.e., α,β-unsaturated esters, ketones, nitriles, ynones, amides, and aldehydes, in the absence of additives such as phosphine and sodium tert-butoxide to provide β-borylhomoenolates in good to excellent yields. The presence of an sp3-hybridized boron center, unambigously confirmed by X-ray crystallography, sufficiently activates the unsymmetrical pinacolato diisopropanolaminato Diboron (PDIPA Diboron, 2) to transfer the sp2-hybridized boron moiety chemoselectively. These observations suggest that the activation of one of the boron atoms is an essential step in the Cu-catalyzed β-boration catalytic cycle.
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sp2 sp3 hybridized mixed Diboron synthesis characterization and copper catalyzed β boration of α β unsaturated conjugated compounds
Organic Letters, 2009Co-Authors: Ming Gao, Steven B Thorpe, Webster L SantosAbstract:A novel sp2−sp3 hybridized mixed Diboron and its reactivity on the copper-catalyzed β-boration of α,β-unsaturated conjugated compounds to afford the corresponding β-borated compounds is reported. The presence of sp3-hybridized boron provides a mild β-boration condition in the absence of phosphine and base additives. Finally, our investigations demonstrate that the sp2-hybridized boron of the mixed Diboron is selectively transferred to the β-carbon of conjugated substrates.
Todd B Marder - One of the best experts on this subject based on the ideXlab platform.
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Diboron 4 compounds from structural curiosity to synthetic workhorse
ChemInform, 2016Co-Authors: Emily C Neeve, Stephen A Westcott, Stephen J Geier, Ibraheem A I Mkhalid, Todd B MarderAbstract:Although known for over 90 years, only in the past two decades has the chemistry of Diboron(4) compounds been extensively explored. Many interesting structural features and reaction patterns have emerged, and more importantly, these compounds now feature prominently in both metal-catalyzed and metal-free methodologies for the formation of B–C bonds and other processes.
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room temperature ring expansion of n heterocyclic carbenes and bb bond cleavage of Diboron 4 compounds
Chemistry: A European Journal, 2015Co-Authors: Sabrina Pietsch, Ursula S D Paul, Udo Radius, Ian A Cade, Michael J Ingleson, Todd B MarderAbstract:We report the isolation and detailed structural characterization, by solid-state and solution NMR spectroscopy, of the neutral mono- and bis-NHC adducts of bis(catecholato)Diboron (B2 cat2 ). The bis-NHC adduct undergoes thermally induced rearrangement, forming a six-membered -B-C=N-C=C-N-heterocyclic ring via C-N bond cleavage and ring expansion of the NHC, whereas the mono-NHC adduct is stable. Bis(neopentylglycolato)Diboron (B2 neop2 ) is much more reactive than B2 cat2 giving a ring expanded product at room temperature, demonstrating that ring expansion of NHCs can be a very facile process with significant implications for their use in catalysis.
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efficient synthesis of aryl boronates via zinc catalyzed cross coupling of alkoxy Diboron reagents with aryl halides at room temperature
ChemInform, 2015Co-Authors: Shubhankar Kumar Bose, Todd B MarderAbstract:A novel Zn/NHC-catalyzed cross-coupling reaction of aryl and hetaryl iodide and bromides with Diboron compounds (II) and (V) is reported.
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efficient synthesis of aryl boronates via zinc catalyzed cross coupling of alkoxy Diboron reagents with aryl halides at room temperature
Organic Letters, 2014Co-Authors: Shubhankar Kumar Bose, Todd B MarderAbstract: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.
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structure and reactivity of a preactivated sp2 sp3 Diboron reagent catalytic regioselective boration of α β unsaturated conjugated compounds
Journal of Organic Chemistry, 2011Co-Authors: Ming Gao, Christian Kleeberg, Steven B Thorpe, Carla Slebodnick, Todd B Marder, Webster L SantosAbstract:A novel sp2–sp3 Diboron reagent has been developed for the copper-catalyzed β-boration of α,β-unsaturated conjugated compounds. The reaction proceeds under mild conditions with various substrates, i.e., α,β-unsaturated esters, ketones, nitriles, ynones, amides, and aldehydes, in the absence of additives such as phosphine and sodium tert-butoxide to provide β-borylhomoenolates in good to excellent yields. The presence of an sp3-hybridized boron center, unambigously confirmed by X-ray crystallography, sufficiently activates the unsymmetrical pinacolato diisopropanolaminato Diboron (PDIPA Diboron, 2) to transfer the sp2-hybridized boron moiety chemoselectively. These observations suggest that the activation of one of the boron atoms is an essential step in the Cu-catalyzed β-boration catalytic cycle.
Tatsuo Ishiyama - One of the best experts on this subject based on the ideXlab platform.
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iridium i catalyzed vinylic c h borylation of 1 cycloalkenecarboxylates with bis pinacolato Diboron
Chemical Communications, 2013Co-Authors: Ikuo Sasaki, Takao Kikuchi, Hana Doi, Toshiya Hashimoto, Hajime Ito, Tatsuo IshiyamaAbstract:Ir(I)-catalyzed C–H borylation of 1-cycloalkenecarboxylic derivatives with bis(pinacolato)Diboron affords various alkenylboronates with functional groups in excellent yields. This reaction was also used in a one-pot borylation/Suzuki–Miyaura cross-coupling procedure.
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iridium catalyzed ortho c h borylation of aryl ketones with bis pinacolato Diboron
ChemInform, 2012Co-Authors: Hiroshi Itoh, Tatsuo Ishiyama, Takao Kikuchi, Norio MiyauraAbstract:ortho-Selective C–H borylation of aryl ketones with bis(pinacolato)Diboron proceeded at 120 °C in octane in the presence of a catalytic amount of iridium(I) complexes comprising 1/2[Ir(OMe)(cod)]2 ...
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ortho c h borylation of benzoate esters with bis pinacolato Diboron catalyzed by iridium phosphine complexes
ChemInform, 2010Co-Authors: Tatsuo Ishiyama, Takao Kikuchi, Hironori Isou, Norio MiyauraAbstract:Iridium complexes generated from [Ir(OMe)(COD)]2 and tris[3,5-bis(trifluoromethyl)phenyl]phosphine efficiently catalyzed the ortho-C–H borylation of benzoate esters with bis(pinacolato)Diboron in octane at 80 °C to produce the corresponding arylboronates in high yields with excellent regioselectivities.
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iridium catalyzed vinylic c h borylation of cyclic vinyl ethers by bis pinacolato Diboron
ChemInform, 2008Co-Authors: Takao Kikuchi, Jun Takagi, Tatsuo Ishiyama, Norio MiyauraAbstract:Vinylic C–H borylation of cyclic vinyl ethers by bis(pinacolato)Diboron was effectively catalyzed by iridium complexes comprised of 1/2[Ir(OMe)(cod)]2 and 4,4′-di-tert-butyl-2,2′-bipyridine in hexa...
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iridium catalyzed direct borylation of five membered heteroarenes by bis pinacolato Diboron regioselective stoichiometric and room temperature reactions
ChemInform, 2004Co-Authors: Tatsuo Ishiyama, Jun Takagi, John F Hartwig, Yuhei Yonekawa, Norio MiyauraAbstract:An iridium(I) complex generated from 1/2[Ir(OMe)(COD)]2 and 4,4′-di-tert-butyl-2,2′-bipyridine catalyzed the direct borylation of 2-substituted thiophenes, furans and pyrroles in stoichiometric amounts relative to bis(pinacolato)Diboron in hexane at room temperature. The heteroarylboronates from regioselective CH activation at the 5-position were formed in high yields. Similar borylations of unsubstituted heteroarenes with an equimolar amount of the Diboron regioselectively provided 2,5-bis(boryl)heteroarenes.
Steven B Thorpe - One of the best experts on this subject based on the ideXlab platform.
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unexpected copper ii catalysis catalytic amine base promoted β borylation of α β unsaturated carbonyl compounds in water
Organic Letters, 2012Co-Authors: Steven B Thorpe, Joseph A Calderone, Webster L SantosAbstract:Using bis(pinacolato)Diboron, catalytic amounts of CuII, and various amine bases in water under atmospheric conditions at rt, acyclic and cyclic α,β-unsaturated ketones and esters are β-borylated in up to 98% yield. Mechanistic investigations using UV–vis spectroscopy, 11B NMR, and solvent kinetic isotope effect suggest that the role of the amine is not only to coordinate to CuII but also to activate a nucleophilic water molecule to form the reactive sp2–sp3 Diboron complex.
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regio and stereoselective copper catalyzed β borylation of allenoates by a preactivated Diboron
ChemInform, 2011Co-Authors: Steven B Thorpe, Xi Guo, Webster L SantosAbstract:Mild and efficient copper-catalyzed borylation of electron-deficient allenoates (I) using the sp2-sp3 mixed hybridized Diboron compound (II) regioselectively installs a boron moiety on the β-position with complete stereocontrol.
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structure and reactivity of a preactivated sp2 sp3 Diboron reagent catalytic regioselective boration of α β unsaturated conjugated compounds
Journal of Organic Chemistry, 2011Co-Authors: Ming Gao, Christian Kleeberg, Steven B Thorpe, Carla Slebodnick, Todd B Marder, Webster L SantosAbstract:A novel sp2–sp3 Diboron reagent has been developed for the copper-catalyzed β-boration of α,β-unsaturated conjugated compounds. The reaction proceeds under mild conditions with various substrates, i.e., α,β-unsaturated esters, ketones, nitriles, ynones, amides, and aldehydes, in the absence of additives such as phosphine and sodium tert-butoxide to provide β-borylhomoenolates in good to excellent yields. The presence of an sp3-hybridized boron center, unambigously confirmed by X-ray crystallography, sufficiently activates the unsymmetrical pinacolato diisopropanolaminato Diboron (PDIPA Diboron, 2) to transfer the sp2-hybridized boron moiety chemoselectively. These observations suggest that the activation of one of the boron atoms is an essential step in the Cu-catalyzed β-boration catalytic cycle.
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sp2 sp3 hybridized mixed Diboron synthesis characterization and copper catalyzed β boration of α β unsaturated conjugated compounds
Organic Letters, 2009Co-Authors: Ming Gao, Steven B Thorpe, Webster L SantosAbstract:A novel sp2−sp3 hybridized mixed Diboron and its reactivity on the copper-catalyzed β-boration of α,β-unsaturated conjugated compounds to afford the corresponding β-borated compounds is reported. The presence of sp3-hybridized boron provides a mild β-boration condition in the absence of phosphine and base additives. Finally, our investigations demonstrate that the sp2-hybridized boron of the mixed Diboron is selectively transferred to the β-carbon of conjugated substrates.
Jie Zhang - One of the best experts on this subject based on the ideXlab platform.
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sandmeyer type reaction to pinacol arylboronates in water phase a green borylation process
ChemInform, 2012Co-Authors: Jie Zhang, Xiaolong Wang, Haitao Yu, Jiahai YeAbstract:Copper-catalyzed cross-coupling of aryl diazonium salts with Diboron (II) proceeds under mild conditions and allows the direct synthesis of arylboronates bearing halogen and acidic substituents.
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sandmeyer type reaction to pinacol arylboronates in water phase a green borylation process
Synlett, 2012Co-Authors: Jie Zhang, Xiaolong Wang, Haitao Yu, Jiahai YeAbstract:Copper(I)-catalyzed cross-coupling reactions of aryl diazonium salts with bis(pinacolato)Diboron can proceed smoothly in the water phase at room temperature to give the corresponding arylboronate esters in good to high yields. The Sandmeyer-type borylation not only provides direct access to arylboronates bearing halo and acidic substituents, but also achieves a green borylation process.