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John F Hartwig - One of the best experts on this subject based on the ideXlab platform.
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effect of ligand structure on the electron density and activity of iridium catalysts for the Borylation of alkanes
ACS Catalysis, 2020Co-Authors: Matthew A Larsen, Raphael J Oeschger, John F HartwigAbstract:An in-depth study of iridium catalysts for the Borylation of alkyl C–H bonds is reported. Although the Borylation of aryl C–H bonds can be catalyzed by iridium complexes containing phen or bpy liga...
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Iridium-Catalyzed C–H Borylation of Cyclopropanes
2016Co-Authors: Carl W. Liskey, John F HartwigAbstract:The Borylation of cyclopropanes catalyzed by the combination of (η6-mes)IrBpin3 or [Ir(COD)OMe]2 and a phenanthroline derivative is reported. The Borylation occurs selectively at the methylene C–H bonds of the cyclopropane ring over methine or methyl C–H bonds. High diasteroselectivities were observed from reactions catalyzed by the combination of iridium and 2,9-Me2phenanthroline. The cyclopropylboronate esters that are generated are versatile synthetic intermediates that can be converted to trifluoroborate salts, boronic acids, cyclopropylarenes, cyclopropylamines, and cyclopropanols
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iridium catalyzed Borylation of primary benzylic c h bonds without a directing group scope mechanism and origins of selectivity
Journal of the American Chemical Society, 2015Co-Authors: Matthew A Larsen, Conner V Wilson, John F HartwigAbstract:Primary benzylic boronate esters are useful intermediates in organic synthesis, but these reagents cannot be prepared by hydroboration. The benzylic C–H Borylation of methylarenes would be a method to form these products, but such reactions without neat methylarene or a directing group are unknown. We report an approach to divert the Borylation of methylarenes from aromatic positions to benzylic positions with a silylborane as reagent and a new iridium catalyst containing an electron-deficient phenanthroline as ligand. This system forms benzylic boronate esters selectively over the corresponding aryl boronate esters. An Ir diboryl monosilyl complex ligated by the phenanthroline was isolated and determined to be the resting state of the catalyst. Mechanistic studies show that this complex is kinetically competent to be an intermediate in the catalytic process. Kinetic studies of benzylic and aryl C–H Borylation catalyzed by various Ir complexes show that the rate of aryl C–H Borylation decreases with decre...
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regioselective Borylation of the c h bonds in alkylamines and alkyl ethers observation and origin of high reactivity of primary c h bonds beta to nitrogen and oxygen
Journal of the American Chemical Society, 2014Co-Authors: Qian Li, Carl W. Liskey, John F HartwigAbstract:Borylation of aliphatic C–H bonds in alkylamines and alkyl ethers to form primary aminoalkyl and alkoxyalkyl boronate esters and studies on the origin of the regioselectivity of these reactions are reported. The products of these reactions can be used directly in Suzuki–Miyaura cross-coupling reactions or isolated as air-stable potassium trifluoroborate salts. Selective Borylation of the terminal C–H bond at the positions β to oxygen and nitrogen occurs in preference to Borylation of the other terminal C–H bonds. Experimental studies and computational results show that C–H bond cleavage is the rate-determining step of the current Borylation reactions. The observed higher reactivity of C–H bonds at the terminal position of ethylamines and ethers results from a combination of attractive Lewis acid–base and hydrogen-bonding interactions, as well as typical repulsive steric interactions, in the transition state. In this transition state, the heteroatom lies directly above the boron atom of one boryl ligand, c...
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iridium catalyzed c h Borylation of heteroarenes scope regioselectivity application to late stage functionalization and mechanism
Journal of the American Chemical Society, 2014Co-Authors: Matthew A Larsen, John F HartwigAbstract:A study on the iridium-catalyzed C–H Borylation of heteroarenes is reported. Several heteroarenes containing multiple heteroatoms were found to be amenable to C–H Borylation catalyzed by the combination of an iridium(I) precursor and tetramethylphenanthroline. The investigations of the scope of the reaction led to the development of powerful rules for predicting the regioselectivity of Borylation, foremost of which is that Borylation occurs distal to nitrogen atoms. One-pot functionalizations are reported of the heteroaryl boronate esters formed in situ, demonstrating the usefulness of the reported methodology for the synthesis of complex heteroaryl structures. Application of this methodology to the synthesis and late-stage functionalization of biologically active compounds is also demonstrated. Mechanistic studies show that basic heteroarenes can bind to the catalyst and alter the resting state from the olefin-bound complex observed during arene Borylation to a species containing a bound heteroarene, lea...
Masaya Sawamura - One of the best experts on this subject based on the ideXlab platform.
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site selective and stereoselective c sp3 h Borylation of alkyl side chains of 1 3 azoles with a silica supported monophosphine iridium catalyst
ChemInform, 2016Co-Authors: Ryo Murakami, Tomohiro Iwai, Masaya SawamuraAbstract:Site-selective and stereoselective C(sp3)–H Borylation of alkyl side chains of 1,3-azoles with bis(pinacolato)diboron was effectively catalyzed by a silica-supported monophosphine-iridium catalyst. The Borylation occurred under relatively mild conditions (2 mol% Ir, 50–90 °C), affording the corresponding primary and secondary alkylboronates. This system was applicable to a variety of 1,3-(benzo)azoles such as thiazoles, oxazoles, and imidazoles.
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site selective c h Borylation of quinolines at the c8 position catalyzed by a silica supported phosphane iridium system
Chemistry-an Asian Journal, 2014Co-Authors: Shota Konishi, Soichiro Kawamorita, Todd B Marder, Patrick G Steel, Tomohiro Iwai, Masaya SawamuraAbstract:Site-selective C-H Borylation of quinoline derivatives at the C8 position has been achieved by using a heterogeneous Ir catalyst system based on a silica-supported cage-type monophosphane ligand SMAP. The efficient synthesis of a corticotropin-releasing factor1 (CRF1) receptor antagonist based on a late-stage C-H Borylation strategy demonstrates the utility of the C8 Borylation reaction.
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ester directed regioselective Borylation of heteroarenes catalyzed by a silica supported iridium complex
ChemInform, 2010Co-Authors: Soichiro Kawamorita, Hirohisa Ohmiya, Masaya SawamuraAbstract:Heteroarenes bearing an ester substituent undergo regioselective Borylation at the position adjacent to the ester group.
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ester directed regioselective Borylation of heteroarenes catalyzed by a silica supported iridium complex
Journal of Organic Chemistry, 2010Co-Authors: Soichiro Kawamorita, Hirohisa Ohmiya, Masaya SawamuraAbstract:The ester-directed regioselective Borylation of arenes catalyzed by a silica-supported monophosphine−Ir complex displayed a significantly broad substrate scope toward heteroaromatic compounds, including thiophene, pyrrole, furan, benzothiophene, benzofuran, indole, and carbazole derivatives. The regioselectivity is complementary to the selectivities observed in the heteroarene C−H Borylation with the dtbpy-Ir catalyst system.
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directed ortho Borylation of functionalized arenes catalyzed by a silica supported compact phosphine iridium system
Journal of the American Chemical Society, 2009Co-Authors: Soichiro Kawamorita, Hirohisa Ohmiya, Kenji Hara, Atsushi Fukuoka, Masaya SawamuraAbstract:An immobilized monophosphine−Ir system, which was prepared in situ from [Ir(OMe)(cod)]2 and a silica-supported, compact phosphine, showed high activities and selectivities for the Borylation of aromatic C−H bonds with bis(pinacolato)diboron. This system was effective not only for the Borylation of benzene but also for the ortho Borylation of arenes with directing groups, such as ester, amide, sulfonate, acetal, alkoxymethyl, and chloro groups, under mild reaction conditions.
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 direct Borylation of five membered heteroarenes by bis pinacolato diboron regioselective stoichiometric and room temperature reactions
ChemInform, 2004Co-Authors: Tatsuo Ishiyama, John F Hartwig, Jun Takagi, 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.
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palladium catalyzed cross coupling reaction of bis pinacolato diboron with 1 alkenyl halides or triflates convenient synthesis of unsymmetrical 1 3 dienes via the Borylation coupling sequence
Journal of the American Chemical Society, 2002Co-Authors: Jun Takagi, Tatsuo Ishiyama, Kou Takahashi, Norio MiyauraAbstract:The synthesis of 1-alkenylboronic acid pinacol esters via a palladium-catalyzed cross-coupling reaction of bis(pinacolato)diboron (pin2B2, pin = Me4C2O2) with 1-alkenyl halides or triflates was carried out in toluene at 50 °C in the presence of KOPh (1.5 equiv) and PdCl2(PPh3)2-2Ph3P (3 mol %). The Borylation of acyclic and cyclic 1-alkenyl bromides and triflates was achieved in high yields with complete retention of configuration of the double bonds. The method was applied to the one-pot synthesis of unsymmetrical 1,3-dienes via the Borylation-coupling sequence.
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mild iridium catalyzed Borylation of arenes high turnover numbers room temperature reactions and isolation of a potential intermediate
Journal of the American Chemical Society, 2002Co-Authors: Tatsuo Ishiyama, Norio Miyaura, Jun Takagi, And Kousaku Ishida, Natia Anastasi R And, John F HartwigAbstract:The Borylation of arenes leads to the formation of synthetically versatile products from unactivated arene reagents. We report that Ir(I) precursors in conjunction with bipyridine ligands catalyze in high yields the Borylation of arenes under mild conditions. These reactions encompase arenes bearing both electron-withdrawing and electron-donating substituents. The temperatures required for the transformation are much lower than those previously reported for direct arene Borylation. The combination of [Ir(COE)2Cl]2 and (4,4-di-t-butyl)bipyridine even allows for reaction at room temperature. The same catalyst system at 100 °C provides remarkably high turnover numbers for a hydrocarbon functionalization process. Mechanistic studies show that the reactions involve uncommon, Ir(II) tris-boryl complexes. An example of this type of complex ligated by di-t-butylbipyridine was isolated and structurally characterized. It reacted rapidly at room temperature to produce aryl boronate esters in high yields.
Jun Takagi - One of the best experts on this subject based on the ideXlab platform.
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syntheses of 4 4 5 5 tetramethyl 1 3 2 dioxaborolan 2 yl arenes through pd catalyzed Borylation of arylbromides with the successive use of 2 2 bis 1 3 2 benzodioxaborole and pinacol
Tetrahedron Letters, 2013Co-Authors: Jun Takagi, Tetsu YamakawaAbstract:Abstract Syntheses of (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)arenes through the Pd-catalyzed Borylation of arylbromides with the successive use of 2,2′-bis(1,3,2-benzodioxaborole) and pinacol were investigated. PdCl 2 (dppf) and AcOK in EtOH or DMSO successfully provided (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)arenes. In particular, this method was more effective in the Borylation of arylbromides bearing sulfonyl groups than the conventional Pd-catalyzed Borylation using pinacolborane or bis(pinacolato)diboron.
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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, John F Hartwig, Jun Takagi, 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.
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palladium catalyzed cross coupling reaction of bis pinacolato diboron with 1 alkenyl halides or triflates convenient synthesis of unsymmetrical 1 3 dienes via the Borylation coupling sequence
Journal of the American Chemical Society, 2002Co-Authors: Jun Takagi, Tatsuo Ishiyama, Kou Takahashi, Norio MiyauraAbstract:The synthesis of 1-alkenylboronic acid pinacol esters via a palladium-catalyzed cross-coupling reaction of bis(pinacolato)diboron (pin2B2, pin = Me4C2O2) with 1-alkenyl halides or triflates was carried out in toluene at 50 °C in the presence of KOPh (1.5 equiv) and PdCl2(PPh3)2-2Ph3P (3 mol %). The Borylation of acyclic and cyclic 1-alkenyl bromides and triflates was achieved in high yields with complete retention of configuration of the double bonds. The method was applied to the one-pot synthesis of unsymmetrical 1,3-dienes via the Borylation-coupling sequence.
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mild iridium catalyzed Borylation of arenes high turnover numbers room temperature reactions and isolation of a potential intermediate
Journal of the American Chemical Society, 2002Co-Authors: Tatsuo Ishiyama, Norio Miyaura, Jun Takagi, And Kousaku Ishida, Natia Anastasi R And, John F HartwigAbstract:The Borylation of arenes leads to the formation of synthetically versatile products from unactivated arene reagents. We report that Ir(I) precursors in conjunction with bipyridine ligands catalyze in high yields the Borylation of arenes under mild conditions. These reactions encompase arenes bearing both electron-withdrawing and electron-donating substituents. The temperatures required for the transformation are much lower than those previously reported for direct arene Borylation. The combination of [Ir(COE)2Cl]2 and (4,4-di-t-butyl)bipyridine even allows for reaction at room temperature. The same catalyst system at 100 °C provides remarkably high turnover numbers for a hydrocarbon functionalization process. Mechanistic studies show that the reactions involve uncommon, Ir(II) tris-boryl complexes. An example of this type of complex ligated by di-t-butylbipyridine was isolated and structurally characterized. It reacted rapidly at room temperature to produce aryl boronate esters in high yields.
Todd B Marder - One of the best experts on this subject based on the ideXlab platform.
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Multidirectional Synthesis of Substituted Indazoles via Iridium-Catalyzed C–H Borylation
2015Co-Authors: Scott A. Sadler, Todd B Marder, Andrew C. Hones, Bryan Roberts, David Blakemore, Patrick G SteelAbstract:In the absence of a steric directing group, iridium-catalyzed C–H Borylation of N-protected indazoles occurs rapidly and selectively at C-3 and the resulting boronate esters can be utilized in a range of downstream conversions. The functional group tolerance of the iridium-catalyzed C–H Borylation reaction enables simple and efficient multidirectional syntheses of substituted indazoles to be realized
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zinc catalyzed Borylation of primary secondary and tertiary alkyl halides with alkoxy diboron reagents at room temperature
ChemInform, 2014Co-Authors: Shubhankar Kumar Bose, Katharina Fucke, Lei Liu, Patrick G Steel, Todd B MarderAbstract:A new catalytic system based on a ZnII NHC precursor has been developed for the cross-coupling reaction of alkyl halides with diboron reagents, which represents a novel use of a Group XII catalyst for C[BOND]X Borylation. This approach gives Borylations of unactivated primary, secondary, and tertiary alkyl halides at room temperature to furnish alkyl boronates, with good functional-group compatibility, under mild conditions. Preliminary mechanistic investigations demonstrated that this Borylation reaction seems to involve one-electron processes.
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site selective c h Borylation of quinolines at the c8 position catalyzed by a silica supported phosphane iridium system
Chemistry-an Asian Journal, 2014Co-Authors: Shota Konishi, Soichiro Kawamorita, Todd B Marder, Patrick G Steel, Tomohiro Iwai, Masaya SawamuraAbstract:Site-selective C-H Borylation of quinoline derivatives at the C8 position has been achieved by using a heterogeneous Ir catalyst system based on a silica-supported cage-type monophosphane ligand SMAP. The efficient synthesis of a corticotropin-releasing factor1 (CRF1) receptor antagonist based on a late-stage C-H Borylation strategy demonstrates the utility of the C8 Borylation reaction.
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dft studies on the Borylation of α β unsaturated carbonyl compounds catalyzed by phosphine copper i boryl complexes and observations on the interconversions between o and c bound enolates of cu b and si
Organometallics, 2008Co-Authors: Li Dang, Zhenyang Lin, Todd B MarderAbstract:The detailed mechanisms for the Borylation of α,β-unsaturated carbonyl compounds, acrolein and methylacrylate, catalyzed by phosphine copper(I) boryl complexes were studied with the aid of density functional theory calculations. The results show that the catalyzed Borylation occurs through C═C insertion into Cu−B to give a β-borylalkyl C-bound Cu(I) enolate intermediate. In the Borylation of acrolein, the C-bound Cu(I) enolate undergoes a keto-to-enol isomerization to give an O-bound enolate intermediate followed by a σ-bond metathesis with a diboron reagent. In the Borylation of methylacrylate, a keto-to-enol isomerization does not occur due to the inertness of the ester group. Alcoholysis or hydrolysis is necessary to convert the C-bound Cu(I) enolate intermediate efficiently to the Borylation product and Cu(I) alkoxide that can easily undergo σ-bond metathesis with a diboron reagent. The different Borylation reaction mechanisms of acrolein and methylacrylate are closely related to the relative thermody...