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Makoto Yamashita - One of the best experts on this subject based on the ideXlab platform.
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formation of a dinuclear rh i rh i complex exhibiting mmct absorption from dianionic diborane 4 through c h bond cleavage
Chemistry Letters, 2020Co-Authors: Seiji Akiyama, Makoto YamashitaAbstract:Reaction of dianionic diborane(4) with [Rh(cod)Cl] afforded a dinuclear Rh(I)−/Rh(I)+ complex through C–H bond cleavage. The resulting complex was characterized by NMR spectroscopy and X-ray analys...
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reactivity of highly lewis acidic diborane 4 toward c n and n n bonds uncatalyzed addition and n n bond cleavage reactions
Angewandte Chemie, 2019Co-Authors: Yuhei Katsuma, Seiji Akiyama, Zhenyang Lin, Makoto YamashitaAbstract:The diboration of the C≡N bond in organic nitriles, and the N=N bond in azobenzene and pyridazine, by the highly Lewis-acidic tetra(o-tolyl)diborane(4) are reported. In the reactions with nitriles, azobenzene, and pyridazine, the addition of diborane(4) to the C≡N and N=N bonds was observed. Conversely, the N=N bond in phthalazine was cleaved by an addition/rearomatization sequence.
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reaction of b2 o tol 4 with co and isocyanides cleavage of the c o triple bond and direct c h borylations
Angewandte Chemie, 2018Co-Authors: Yuhei Katsuma, Zhenyang Lin, Nana Tsukahara, Makoto YamashitaAbstract:The reaction of highly Lewis acidic tetra(o-tolyl)diborane(4) with CO afforded a mixture of boraindane and boroxine by the cleavage of the C≡O triple bond. 13 C labeling experiments confirmed that the carbon atom in the boraindane stems from CO. Simultaneously, formation of boroxine 3 could be considered as borylene transfer to capture the oxygen atom from CO. The reaction of diborane(4) with t Bu-NC afforded an azaallene, while the reaction with Xyl-NC furnished cyclic compounds by direct C-H borylations.
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cleaving dihydrogen with tetra o tolyl diborane 4
Journal of the American Chemical Society, 2017Co-Authors: Nana Tsukahara, Hiroki Asakawa, Ka Ho Lee, Zhenyang Lin, Makoto YamashitaAbstract:Tetra(o-tolyl)diborane(4), 1, was synthesized and characterized experimentally as well as theoretically by density functional theory (DFT) calculations. Exposure of 1 to H2 (1 bar) at room temperature afforded the corresponding di(o-tolyl)hydroborane through cleavage of the H–H and B–B bonds. DFT calculations suggested a diarylboryl anion character for the transition state.
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Cleaving Dihydrogen with Tetra(o‑tolyl)diborane(4)
2017Co-Authors: Nana Tsukahara, Hiroki Asakawa, Ka Ho Lee, Zhenyang Lin, Makoto YamashitaAbstract:Tetra(o-tolyl)diborane(4), 1, was synthesized and characterized experimentally as well as theoretically by density functional theory (DFT) calculations. Exposure of 1 to H2 (1 bar) at room temperature afforded the corresponding di(o-tolyl)hydroborane through cleavage of the H–H and B–B bonds. DFT calculations suggested a diarylboryl anion character for the transition state
Zhenyang Lin - One of the best experts on this subject based on the ideXlab platform.
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reactivity of highly lewis acidic diborane 4 toward c n and n n bonds uncatalyzed addition and n n bond cleavage reactions
Angewandte Chemie, 2019Co-Authors: Yuhei Katsuma, Seiji Akiyama, Zhenyang Lin, Makoto YamashitaAbstract:The diboration of the C≡N bond in organic nitriles, and the N=N bond in azobenzene and pyridazine, by the highly Lewis-acidic tetra(o-tolyl)diborane(4) are reported. In the reactions with nitriles, azobenzene, and pyridazine, the addition of diborane(4) to the C≡N and N=N bonds was observed. Conversely, the N=N bond in phthalazine was cleaved by an addition/rearomatization sequence.
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reaction of b2 o tol 4 with co and isocyanides cleavage of the c o triple bond and direct c h borylations
Angewandte Chemie, 2018Co-Authors: Yuhei Katsuma, Zhenyang Lin, Nana Tsukahara, Makoto YamashitaAbstract:The reaction of highly Lewis acidic tetra(o-tolyl)diborane(4) with CO afforded a mixture of boraindane and boroxine by the cleavage of the C≡O triple bond. 13 C labeling experiments confirmed that the carbon atom in the boraindane stems from CO. Simultaneously, formation of boroxine 3 could be considered as borylene transfer to capture the oxygen atom from CO. The reaction of diborane(4) with t Bu-NC afforded an azaallene, while the reaction with Xyl-NC furnished cyclic compounds by direct C-H borylations.
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cleaving dihydrogen with tetra o tolyl diborane 4
Journal of the American Chemical Society, 2017Co-Authors: Nana Tsukahara, Hiroki Asakawa, Ka Ho Lee, Zhenyang Lin, Makoto YamashitaAbstract:Tetra(o-tolyl)diborane(4), 1, was synthesized and characterized experimentally as well as theoretically by density functional theory (DFT) calculations. Exposure of 1 to H2 (1 bar) at room temperature afforded the corresponding di(o-tolyl)hydroborane through cleavage of the H–H and B–B bonds. DFT calculations suggested a diarylboryl anion character for the transition state.
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Cleaving Dihydrogen with Tetra(o‑tolyl)diborane(4)
2017Co-Authors: Nana Tsukahara, Hiroki Asakawa, Ka Ho Lee, Zhenyang Lin, Makoto YamashitaAbstract:Tetra(o-tolyl)diborane(4), 1, was synthesized and characterized experimentally as well as theoretically by density functional theory (DFT) calculations. Exposure of 1 to H2 (1 bar) at room temperature afforded the corresponding di(o-tolyl)hydroborane through cleavage of the H–H and B–B bonds. DFT calculations suggested a diarylboryl anion character for the transition state
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ring contraction of a pinacolatoboryl group to form a 1 2 oxaboretane ring reaction of unsymmetrical diborane 4 with 2 6 dimethylphenyl isocyanide
Organometallics, 2016Co-Authors: Yuhei Katsuma, Hiroki Asakawa, Ka Ho Lee, Zhenyang Lin, Makoto YamashitaAbstract:An unsymmetrical diborane(4), pinB-BMes2, reacted with 2,6-dimethylphenyl isocyanide to give a spirocyclic 1,2-oxaboretane or isocyanide-coordinated boraalkene. The former product formed via ring contraction of the pinacolatoboryl group. DFT calculations revealed the ring contraction proceeded via a carbocationic intermediate. This new degradation pathway from the Bpin group would provide important information in Bpin-related chemistry.
Ka Ho Lee - One of the best experts on this subject based on the ideXlab platform.
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cleaving dihydrogen with tetra o tolyl diborane 4
Journal of the American Chemical Society, 2017Co-Authors: Nana Tsukahara, Hiroki Asakawa, Ka Ho Lee, Zhenyang Lin, Makoto YamashitaAbstract:Tetra(o-tolyl)diborane(4), 1, was synthesized and characterized experimentally as well as theoretically by density functional theory (DFT) calculations. Exposure of 1 to H2 (1 bar) at room temperature afforded the corresponding di(o-tolyl)hydroborane through cleavage of the H–H and B–B bonds. DFT calculations suggested a diarylboryl anion character for the transition state.
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Cleaving Dihydrogen with Tetra(o‑tolyl)diborane(4)
2017Co-Authors: Nana Tsukahara, Hiroki Asakawa, Ka Ho Lee, Zhenyang Lin, Makoto YamashitaAbstract:Tetra(o-tolyl)diborane(4), 1, was synthesized and characterized experimentally as well as theoretically by density functional theory (DFT) calculations. Exposure of 1 to H2 (1 bar) at room temperature afforded the corresponding di(o-tolyl)hydroborane through cleavage of the H–H and B–B bonds. DFT calculations suggested a diarylboryl anion character for the transition state
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ring contraction of a pinacolatoboryl group to form a 1 2 oxaboretane ring reaction of unsymmetrical diborane 4 with 2 6 dimethylphenyl isocyanide
Organometallics, 2016Co-Authors: Yuhei Katsuma, Hiroki Asakawa, Ka Ho Lee, Zhenyang Lin, Makoto YamashitaAbstract:An unsymmetrical diborane(4), pinB-BMes2, reacted with 2,6-dimethylphenyl isocyanide to give a spirocyclic 1,2-oxaboretane or isocyanide-coordinated boraalkene. The former product formed via ring contraction of the pinacolatoboryl group. DFT calculations revealed the ring contraction proceeded via a carbocationic intermediate. This new degradation pathway from the Bpin group would provide important information in Bpin-related chemistry.
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direct and base catalyzed diboration of alkynes using the unsymmetrical diborane 4 pinb bmes2
Journal of the American Chemical Society, 2016Co-Authors: Chiemi Kojima, Zhenyang Lin, Ka Ho Lee, Makoto YamashitaAbstract:In the absence of transition metal catalysts, the unsymmetrical diborane(4), pinB-BMes2, reacted with alkynes to afford diborylalkenes. The isomer ratio of the products could be controlled via temperature, solvent, and additive(s). A reaction mechanism was proposed on the basis of two isolated intermediates, and this reaction could furthermore be applied to synthesize a luminescent molecule.
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Ring Contraction of a Pinacolatoboryl Group To Form a 1,2-Oxaboretane Ring: Reaction of Unsymmetrical Diborane(4) with 2,6-Dimethylphenyl Isocyanide
2016Co-Authors: Yuhei Katsuma, Hiroki Asakawa, Ka Ho Lee, Zhenyang Lin, Makoto YamashitaAbstract:An unsymmetrical diborane(4), pinB-BMes2, reacted with 2,6-dimethylphenyl isocyanide to give a spirocyclic 1,2-oxaboretane or isocyanide-coordinated boraalkene. The former product formed via ring contraction of the pinacolatoboryl group. DFT calculations revealed the ring contraction proceeded via a carbocationic intermediate. This new degradation pathway from the Bpin group would provide important information in Bpin-related chemistry
Holger Braunschweig - One of the best experts on this subject based on the ideXlab platform.
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Pseudodiborenes: hydride-bridged diboranes(5) as two-electron reductants of chalcogens.
Chemical Communications, 2019Co-Authors: Dominic Prieschl, Maximilian Dietz, Jonas H. Muessig, Katharina Wagner, Ivo Krummenacher, Holger BraunschweigAbstract:The reactivity of two nucleophilic neutral sp2-sp3 diboranes towards chalcogens is presented herein. Both diboranes(5) serve as two-electron reductants, incorporating oxygen, sulfur and selenium atoms. Treatment with chalcogen sources results in the oxidative insertion of one chalcogen atom into the B-B single bond, while depending on the negative inductive effect of the chalcogen and the boron bound aryl substituent further N-heterocyclic carbene (NHC) ring expansion and hydride migration can occur. These reactions provide access to unprecedented six- or seven-membered heterocycles and help to illuminate the pseudo-multiple bonding character of hydrogen-bridged B-B single bonds.
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diboryldiborenes π conjugated b4 chains isoelectronic to the butadiene dication
Angewandte Chemie, 2018Co-Authors: Alexander Hermann, Ivo Krummenacher, Rian D Dewhurst, Michael J Ingleson, James D Mattock, Alfredo Vargas, Holger BraunschweigAbstract:sp2–sp3 diborane species based on bis(catecholato)diboron and N-heterocyclic carbenes (NHCs) are subjected to catechol/bromide exchange selectively at the sp3 boron atom. The reduction of the resulting 1,1-dibromodiborane adducts led to reductive coupling and isolation of doubly NHC-stabilized 1,2-diboryldiborenes. These compounds are the first examples of molecules exhibiting pi-electron delocalization over an all-boron chain.
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Quaternizing diboranes(4): highly divergent outcomes and an inorganic Wagner-Meerwein rearrangement.
Journal of the American Chemical Society, 2013Co-Authors: Holger Braunschweig, Katharina Wagner, Rian D Dewhurst, Krzysztof Radacki, Alexander Damme, Thomas Kramer, Thomas Kupfer, Eva Siedler, Alexandra Trumpp, Christine WernerAbstract:Apart from a few compounds under heavy use in organic chemistry, diboranes are relatively exotic and poorly understood. Recently, interest in these molecules has intensified with the advent of so-called “sp2–sp3” diboranes which exhibit useful reactivity toward organic substrates. In our hands, addition of Lewis bases to dihalodiorganyl diboranes(4) has previously shown some very surprising reactivity, including a substituent exchange between the boron atoms, and diboranes in which halide atoms bridge the B–B bond. Herein we have expanded the range of diborane(4) and Lewis base reaction partners, in the process uncovering three new reactivity patterns as well as some cases where mixtures are obtained. Trends are established for the preferential formation of certain products which rationalize the results based on electronic and steric effects. The substituent exchange, clearly based on an inorganic version of the well-known Wagner–Meerwein rearrangement, was also found to be an equilibrium reaction with th...
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Quaternizing Diboranes(4): Highly Divergent Outcomes and an Inorganic Wagner–Meerwein Rearrangement
2013Co-Authors: Holger Braunschweig, Katharina Wagner, Rian D Dewhurst, Krzysztof Radacki, Alexander Damme, Thomas Kramer, Thomas Kupfer, Eva Siedler, Alexandra Trumpp, Christine WernerAbstract:Apart from a few compounds under heavy use in organic chemistry, diboranes are relatively exotic and poorly understood. Recently, interest in these molecules has intensified with the advent of so-called “sp2–sp3” diboranes which exhibit useful reactivity toward organic substrates. In our hands, addition of Lewis bases to dihalodiorganyl diboranes(4) has previously shown some very surprising reactivity, including a substituent exchange between the boron atoms, and diboranes in which halide atoms bridge the B–B bond. Herein we have expanded the range of diborane(4) and Lewis base reaction partners, in the process uncovering three new reactivity patterns as well as some cases where mixtures are obtained. Trends are established for the preferential formation of certain products which rationalize the results based on electronic and steric effects. The substituent exchange, clearly based on an inorganic version of the well-known Wagner–Meerwein rearrangement, was also found to be an equilibrium reaction with the halide-bridged Lewis adducts on the other side
Hiroki Asakawa - One of the best experts on this subject based on the ideXlab platform.
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cleaving dihydrogen with tetra o tolyl diborane 4
Journal of the American Chemical Society, 2017Co-Authors: Nana Tsukahara, Hiroki Asakawa, Ka Ho Lee, Zhenyang Lin, Makoto YamashitaAbstract:Tetra(o-tolyl)diborane(4), 1, was synthesized and characterized experimentally as well as theoretically by density functional theory (DFT) calculations. Exposure of 1 to H2 (1 bar) at room temperature afforded the corresponding di(o-tolyl)hydroborane through cleavage of the H–H and B–B bonds. DFT calculations suggested a diarylboryl anion character for the transition state.
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Cleaving Dihydrogen with Tetra(o‑tolyl)diborane(4)
2017Co-Authors: Nana Tsukahara, Hiroki Asakawa, Ka Ho Lee, Zhenyang Lin, Makoto YamashitaAbstract:Tetra(o-tolyl)diborane(4), 1, was synthesized and characterized experimentally as well as theoretically by density functional theory (DFT) calculations. Exposure of 1 to H2 (1 bar) at room temperature afforded the corresponding di(o-tolyl)hydroborane through cleavage of the H–H and B–B bonds. DFT calculations suggested a diarylboryl anion character for the transition state
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ring contraction of a pinacolatoboryl group to form a 1 2 oxaboretane ring reaction of unsymmetrical diborane 4 with 2 6 dimethylphenyl isocyanide
Organometallics, 2016Co-Authors: Yuhei Katsuma, Hiroki Asakawa, Ka Ho Lee, Zhenyang Lin, Makoto YamashitaAbstract:An unsymmetrical diborane(4), pinB-BMes2, reacted with 2,6-dimethylphenyl isocyanide to give a spirocyclic 1,2-oxaboretane or isocyanide-coordinated boraalkene. The former product formed via ring contraction of the pinacolatoboryl group. DFT calculations revealed the ring contraction proceeded via a carbocationic intermediate. This new degradation pathway from the Bpin group would provide important information in Bpin-related chemistry.
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Ring Contraction of a Pinacolatoboryl Group To Form a 1,2-Oxaboretane Ring: Reaction of Unsymmetrical Diborane(4) with 2,6-Dimethylphenyl Isocyanide
2016Co-Authors: Yuhei Katsuma, Hiroki Asakawa, Ka Ho Lee, Zhenyang Lin, Makoto YamashitaAbstract:An unsymmetrical diborane(4), pinB-BMes2, reacted with 2,6-dimethylphenyl isocyanide to give a spirocyclic 1,2-oxaboretane or isocyanide-coordinated boraalkene. The former product formed via ring contraction of the pinacolatoboryl group. DFT calculations revealed the ring contraction proceeded via a carbocationic intermediate. This new degradation pathway from the Bpin group would provide important information in Bpin-related chemistry
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Facile scission of isonitrile carbon-nitrogen triple bond using a diborane(4) reagent.
Nature Communications, 2014Co-Authors: Hiroki Asakawa, Ka Ho Lee, Zhenyang Lin, Makoto YamashitaAbstract:The cleavage of triple bonds can be achieved through the use of transition metal catalysts; however, it is less well explored for metal-free systems. Here, the authors show complete cleavage of a carbon–nitrogen triple bond under mild conditions through the use of a diborane(4) reagent.