25015-63-8Relevant academic research and scientific papers
Ruthenium-catalyzed regiospecific borylation of methyl C-H bonds
Murphy, Jaclyn M.,Lawrence, Joshua D.,Kawamura, Kazumori,Incarvito, Christopher,Hartwig, John F.
, p. 13684 - 13685 (2006)
We report the regiospecific, ruthenium-catalyzed borylation of saturated terminal C-H bonds. Alkylboronates were obtained in 78-98% yields. The borylations of alkanes, trialkylamines, protected alcohols, and fluoroalkanes occurred regiospecifically at the methyl group that is least sterically hindered. In contrast to most organometallic C-H activation, the reactions of alkanes occurred in higher yields than the reactions of arenes. Reactions were conducted that probed steric and electronic effects on the alkyl borylation. These reactions showed that the borylation occurred preferentially at the methyl group that is least sterically hindered and most electron-deficient. Ruthenium compounds containing boryl ligands were synthesized, and one was characterized by X-ray crystallography. One of these compounds contained a rare bridging boryl ligand and served as a catalyst precursor for the borylation of octane. Copyright
Synthesis of catechol-, pinacol-, and neopentylglycolborane through the heterogeneous catalytic B-B hydrogenolysis of diboranes(4)
Braunschweig, Holger,Guethlein, Frank,Mailaender, Lisa,Marder, Todd B.
, p. 14831 - 14835 (2013)
A new synthetic approach to hydroboranes catechol-, pinacol-, and neopentylglycolborane has been developed. Starting from diboranes(4) B 2cat2, B2pin2, or B 2neop2, the respective boranes were obtained by heterogeneously catalyzed cleavage of the B-B bond in the respective diboranes with hydrogen. Group10 metals were found to be effective catalysts for this reaction. Copyright
Metal-Organic Framework Stabilizes a Low-Coordinate Iridium Complex for Catalytic Methane Borylation
Feng, Xuanyu,Song, Yang,Li, Zhe,Kaufmann, Michael,Pi, Yunhong,Chen, Justin S.,Xu, Ziwan,Li, Zhong,Wang, Cheng,Lin, Wenbin
, p. 11196 - 11203 (2019)
Catalytic borylation has recently been suggested as a potential strategy to convert abundant methane to fine chemicals. However, synthetic utility of methane borylation necessitates significant improvement of catalytic activities over original phenanthroline-and diphosphine-Ir complexes. Herein, we report the use of metal-organic frameworks (MOFs) to stabilize low-coordinate Ir complexes for highly active methane borylation to afford the monoborylated product. The mono(phosphine)-Ir based MOF, Zr-P1-Ir, significantly outperformed other Ir catalysts in methane borylation to afford CH3Bpin with a turnover number of 127 at 110 °C. Density functional theory calculations indicated a significant reduction of activation barrier for the rate limiting oxidative addition of methane to the four-coordinate (P1)IrIII(Bpin)3 catalyst to form the six-coordinate (P1)IrV(Bpin)3(CH3)(H) intermediate, thus avoiding the formation of sterically encumbered seven-coordinate IrV intermediates as found in other Ir catalysts based on chelating phenanthroline, bipyridine, and diphosphine ligands. MOF thus stabilizes the homogeneously inaccessible, low-coordinate (P1)Ir(boryl)3 catalyst to provide a unique strategy to significantly lower the activation barrier for methane borylation. This MOF-based catalyst design holds promise in addressing challenging catalytic reactions involving highly inert substrates.
A boron-nitrogen transborylation enabled, borane-catalysed reductive cyanation of enones
Benn, Kieran,Nicholson, Kieran,Langer, Thomas,Thomas, Stephen P.
supporting information, p. 9406 - 9409 (2021/09/22)
Cyanation offers a simple method for the introduction of a nitrile group into organic molecules and an orthogonal route for the installation of a wide array of functional groups using simple transformations. Cyanation methods are dominated by transition metal catalysis and the use of hydrogen cyanide gas. Here, the electrophilic cyanation of enones was achieved using a main-group catalyst and a non-toxic, electrophilic cyanide source. This protocol was applied across a broad substrate scope including those containing reducible functional groups. Mechanistic studies indicated an amino-borane intermediate which underwent B-N transborylation (B-N/B-H exchange) to achieve catalytic turnover.
Hydrogen Evolution from Telescoped Miyaura Borylation and Suzuki Couplings Utilizing Diboron Reagents: Process Safety and Hazard Considerations
Borkar, Indrakant,Brewer, Alison Campbell,Buser, Jonas Y.,Campos, Odilon,Fleming, Jeffrey,Forst, Mindy B.,Hansen, Caoimhe,Humenik, Ashley,Jeffery, Stephen,Kokitkar, Prashant B.,Kolis, Stanley P.,Lambertus, Gordon R.,Martinelli, Joseph R.,McCartan, Ciaran,Merritt, Jeremy M.,Moursy, Hossam,Murphy, Donal,Murray, Michael M.,O'Donnell, Kevin,O'Sullivan, Rita,Richardson, Gary A.,Xia, Han
, (2021/08/30)
The hazard assessment of a telescoped Miyaura borylation and Suzuki coupling reaction employing bis(pinacolato)diboron (BisPin), used in the developmental synthesis of an intermediate for abemaciclib, led to the observation of hydrogen being generated. Quantitative headspace GC and solution 11B NMR were used to show that the rapid decomposition of the excess BisPin from the borylation under the aqueous basic conditions of the Suzuki reaction was responsible for H2 generation. The moles of H2 observed were found equal to the BisPin excess, which is rationalized by mass balance and a stoichiometric reaction. The possible generation of the stoichiometric levels of H2 should be considered in hazard assessments of this class of reaction. Kinetic and process modeling was used to minimize the risk upon scale-up, and results for commercial manufacturing batches are presented, which showed good agreement with the lab scale data. Furthermore, the hydrogen evolution potentials of other common borylating agents including bisboronic acid (BBA) and pinacol borane were demonstrated.
Regioselective Synthesis of α-Functional Stilbenes via Precise Control of Rapid cis- trans Isomerization in Flow
Lee, Hyune-Jea,Yonekura, Yuya,Kim, Nayoung,Yoshida, Jun-Ichi,Kim, Heejin
supporting information, p. 2904 - 2910 (2021/05/05)
The rapid cis-trans isomerization of α-anionic stilbene was regioselectively controlled by using flow microreactors, and its reaction with various electrophiles was conducted. The reaction time was precisely controlled within milliseconds to seconds at -50 °C to selectively give the cis- or trans-isomer in high yields. This synthetic method in flow was well-applied to synthesize precursors of commercial drug compound, (E)- and (Z)-tamoxifen with high regioselectivity and productivity.
Synthesis of DBpin using Earth-abundant metal catalysis
Cummins, Andrew W. M.,Docherty, Jamie H.,Li, Shuyang,Muilu, Tommi,Thomas, Stephen P.,Willcox, Dominic R.
supporting information, (2020/03/10)
The synthesis of DBpin was achieved using (EtBIP)CoCl2 or (tBuPNN)FeCl2 as pre-catalysts activated with NaOtBu. (EtBIP)CoCl2 was used as a pre-catalyst for the hydrogen isotope exchange of HBpin with D2, and (tBuPNN)FeCl2 for deuterogenolysis of B2pin2. The one-pot, tandem hydrogenolysis-hydroboration/deuterogenolysis-deuteroboration reaction of terminal alkenes could be catalysed by (tBuPNN)FeCl2 to give alkyl boronic esters.
A highly efficient cobalt-catalyzed deuterogenolysis of diboron: Synthesis of deuterated pinacolborane and vinylboronates
Qiao, Lin,Zhang, Lei,Liu, Guixia,Huang, Zheng
supporting information, p. 4138 - 4142 (2019/04/10)
Highly efficient hydrogenolysis and deuterogenolysis of diboron compounds have been realized by the use of a cobalt catalyst, affording TON up to 48201. Furthermore, a one-pot two-step procedure comprising sequential deuterogenolysis of diboron and deuteroboration of alkynes under the same cobalt catalyst has been developed for the efficient, atom-economical synthesis of deuterated vinylboronates with high deuterium incorporation and excellent regio- and stereoselectivity.
Air-Stable α-Diimine Nickel Precatalysts for the Hydrogenation of Hindered, Unactivated Alkenes
Léonard, Nadia G.,Chirik, Paul J.
, p. 342 - 348 (2018/01/17)
Treatment of a mixture of air-stable nickel(II) bis(octanoate), Ni(O2CC7H15)2, and α-diimine ligand, iPrDI or CyADI (iPrDI = [2,6-iPr2-C6H3N=C(CH3)]2, CyADI = [C6H11N=C(CH3)]2) with pinacolborane (HBPin) generated a highly active catalyst for the hydrogenation of hindered, essentially unfunctionalized alkenes. A range of tri- and tetrasubstituted alkenes was hydrogenated and a benchtop procedure for the hydrogenation of 1-phenyl-1-cyclohexene on a multigram scale was demonstrated and represents an advance in catalyst activity and scope for the nickel-catalyzed hydrogenation of this challenging class of alkenes. Deuteration of 1,2-dimethylindene with the in situ-generated nickel catalyst with iPrDI exclusively furnished the 1,2-syn-d2-dimethylindane. With cyclic trisubstituted alkenes, such as 1-methyl-indene and methylcyclohexene, deuteration with the in situ generated nickel catalyst under 4 atm of D2 produced multiple deuterated isotopologues of the alkanes, signaling chain running processes that are competitive with productive hydrogenation. Stoichiometric studies, titration, and deuterium labeling experiments identified that the borane reagent served the dual role of reducing nickel(II) bis(carboxylate) to the previously reported nickel hydride dimer [(iPrDI)NiH]2 and increasing the observed hydrogenation activity. Performing the catalyst activation procedure with D2 gas and HBPin generated both HD and DBPin, establishing that the borane is involved in H2 activation as judged by 1H and 11B nuclear magnetic resonance spectroscopies.
Kinetic Resolution of Secondary Allyl Boronates and Their Application in the Synthesis of Homoallylic Amines
Villar, Laura,Orlov, Nikolai V.,Kondratyev, Nikolay S.,Uria, Uxue,Vicario, Jose L.,Malkov, Andrei V.
supporting information, p. 16262 - 16265 (2018/10/20)
Highly enantioenriched, chromatographically-stable secondary allyl boronates featuring a 1,1,2,2-tetraethyl-1,2-ethanediol fragment (Epin) were obtained by kinetic resolution of their racemic mixtures. The Epin group at boron considerably improved stability of allyl boronates allowing them to be readily isolated by chromatography on silica. The resolved reagents were applied in stereoselective synthesis of homoallylic amines with an internal double bond employing unprotected imines formed in situ from aldehydes and ammonia. The reactions proceeded with an excellent transfer of chirality.
