25015-63-8Relevant articles and documents
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
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.
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.
