338998-93-9Relevant articles and documents
C-H Borylation Catalysis of Heteroaromatics by a Rhenium Boryl Polyhydride
Donnelly, Liam J.,Faber, Teresa,Morrison, Carole A.,Nichol, Gary S.,Thomas, Stephen P.,Love, Jason B.
, p. 7394 - 7400 (2021/06/30)
Transition metal complexes bearing metal-boron bonds are of particular relevance to catalytic C-H borylation reactions, with iridium polyboryl and polyhydrido-boryl complexes the current benchmark catalysts for these transformations. Herein, we demonstrate that polyhydride boryl phosphine rhenium complexes are accessible and catalyze the C-H borylation of heteroaromatic substrates. Reaction of [K(DME)(18-c-6)][ReH4(Bpin)(ν2-HBpin)(κ2-H2Bpin)] 1 with 1,3-bis(diphenylphosphino)propane (dppp) produced [K(18-c-6)][ReH4(ν2-HBpin)(dppp)] 2 through substitution of two equivalents of HBpin, and protonation of 2 formed the neutral complex [ReH6(Bpin)(dppp)] 3. Combined X-ray crystallographic and DFT studies show that 2 is best described as a σ-borane complex, whereas 3 is a boryl complex. Significantly, the boryl complex 3 acted as a catalyst for the C(sp2)-H borylation of a variety of heteroarenes (14 examples including furan, thiophene, pyrrole and indole derivatives) and displayed similar reactivity to the iridium analogues.
Manganese-Catalyzed C(sp2)-H Borylation of Furan and Thiophene Derivatives
Britton, Luke,Skrodzki, Maciej,Nichol, Gary S.,Dominey, Andrew P.,Pawlu?, Piotr,Docherty, Jamie H.,Thomas, Stephen P.
, p. 6857 - 6864 (2021/06/28)
Aryl boronic esters are bench-stable, platform building-blocks that can be accessed through metal-catalyzed aryl C(sp2)-H borylation reactions. C(sp2)-H bond functionalization reactions using rare- and precious-metal catalysts are well established, and while examples utilizing Earth-abundant alternatives have emerged, manganese catalysis remains lacking. The manganese-catalyzed C-H borylation of furan and thiophene derivatives is reported alongside an in situ activation method providing facile access to the active manganese hydride species. Mechanistic investigations showed that blue light irradiation directly affected catalysis by action at the metal center, that C(sp2)-H bond borylation occurs through a C-H metallation pathway, and that the reversible coordination of pinacolborane to the catalyst gave a manganese borohydride complex, which was as an off-cycle resting state.
Iron-catalysed C(sp2)-H borylation enabled by carboxylate activation
Britton, Luke,Docherty, Jamie H.,Dominey, Andrew P.,Thomas, Stephen P.
supporting information, (2020/02/22)
Arene C(sp2)-H bond borylation reactions provide rapid and efficient routes to synthetically versatile boronic esters. While iridium catalysts are well established for this reaction, the discovery and development of methods using Earth-abundant alternatives is limited to just a few examples. Applying an in situ catalyst activation method using air-stable and easily handed reagents, the iron-catalysed C(sp2)-H borylation reactions of furans and thiophenes under blue light irradiation have been developed. Key reaction intermediates have been prepared and characterised, and suggest two mechanistic pathways are in action involving both C-H metallation and the formation of an iron boryl species.
C(sp2)-H Borylation of Heterocycles by Well-Defined Bis(silylene)pyridine Cobalt(III) Precatalysts: Pincer Modification, C(sp2)-H Activation, and Catalytically Relevant Intermediates
Arevalo, Rebeca,Pabst, Tyler P.,Chirik, Paul J.
supporting information, p. 2763 - 2773 (2020/07/24)
Well-defined bis(silylene)pyridine cobalt(III) precatalysts for C(sp2)-H borylation have been synthesized and applied to the investigation of the mechanism of the catalytic borylation of furans and 2,6-lutidine. Specifically, [(ArSiNSi)CoH3]·NaHBEt3 {ArSiNSi = 2,6-[EtNSi(NtBu)2CAr]2C5H3N, where Ar = C6H5 (1-H3·NaHBEt3) or 4-MeC6H4 (2-H3·NaHBEt3)} and trans-[(ArSiNSi)Co(H)2BPin] {Ar = C6H5 [1-(H)2BPin] or 4-MeC6H4 [2-(H)2BPin], and Pin = pinacolato} were prepared and employed as single-component precatalysts for the C(sp2)-H borylation of 2-methylfuran, benzofuran, and 2,6-lutidine. The cobalt(III) precursors, 2-H3·NaHBEt3 and 2-(H)2BPin, also promoted C(sp2)-H activation of benzofuran, yielding [(ArSiNSi)CoH(Bf)2] {Ar = 4-MeC6H4 [2-H(Bf)2], and Bf = 2-benzofuranyl}. Monitoring the catalytic borylation of 2-methylfuran and 2,6-lutidine by 1H NMR spectroscopy established the trans-dihydride cobalt(III) boryl as the catalyst resting state at low substrate conversions. At higher conversions, two distinct pincer modification pathways were identified, depending on the substrate and the boron source.
Method for efficiently catalyzing selective boronation reaction of five-membered heterocycle
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Paragraph 0021-0024, (2020/05/02)
The invention relates to a method for efficiently catalyzing a selective boronation reaction of a five-membered heterocycle. A heterocyclic borate product can be smoothly prepared through convenientlycatalyzing a selective boronation reaction of furan and thiophene derivatives and a cheap and easily available organic boron reagent under a mild condition by a cheap ruthenium metal complex taken asa catalyst. Compared with a reported method, the method of the invention has the obvious advantages of specific reaction selectivity, low catalyst dosage, convenience in operation, no need of addinga reaction solvent and the like, and an efficient and high-selectivity reaction strategy is provided for laboratory preparation or industrial production of the heterocyclic borate product.
Catalytic C?H Borylation Using Iron Complexes Bearing 4,5,6,7-Tetrahydroisoindol-2-ide-Based PNP-Type Pincer Ligand
Kato, Takeru,Kuriyama, Shogo,Nakajima, Kazunari,Nishibayashi, Yoshiaki
, p. 2097 - 2101 (2019/05/28)
Catalytic C?H borylation has been reported using newly designed iron complexes bearing a 4,5,6,7-tetrahydroisoindol-2-ide-based PNP pincer ligand. The reaction tolerated various five-membered heteroarenes, such as pyrrole derivatives, as well as six-membered aromatic compounds, such as toluene. Successful examples of the iron-catalyzed sp3 C?H borylation of anisole derivatives were also presented.
Alkylammoniotrifluoroborate functionalized polystyrenes: Polymeric pre-catalysts for the metal-free borylation of heteroarenes
Bouchard, Nicolas,Fontaine, Frédéric-Georges
supporting information, p. 4846 - 4856 (2019/04/17)
Three polymeric versions of ansa-N,N-dialkylammoniumtrifluoroborate ambiphilic molecules based on the styrene motif (poly(1-NMe2H+-2-BF3--4-styrene) (P-Me), poly(1-NEt2H+-2-BF3--4-styrene) (P-Et) and poly(1-piperidinyl-H+-2-BF3--4-styrene) (P-Pip)) were synthesized, characterized and tested as heterogeneous pre-catalysts for the borylation of electron-rich heteroarenes. These heterogeneous versions of previously reported pre-catalysts show similar reactivity patterns and represent the first examples of solid-supported FLP metal-free catalysts for the C-H borylation of heteroarenes.
Regiodivergent hydrosilylation, hydrogenation, [2π + 2π]-cycloaddition and C-H borylation using counterion activated earth-abundant metal catalysis
Agahi, Riaz,Challinor, Amy J.,Dunne, Joanne,Docherty, Jamie H.,Carter, Neil B.,Thomas, Stephen P.
, p. 5079 - 5084 (2019/05/24)
The widespread adoption of earth-abundant metal catalysis lags behind that of the second- and third-row transition metals due to the often challenging practical requirements needed to generate the active low oxidation-state catalysts. Here we report the development of a single endogenous activation protocol across five reaction classes using both iron- and cobalt pre-catalysts. This simple catalytic manifold uses commercially available, bench-stable iron- or cobalt tetrafluoroborate salts to perform regiodivergent alkene and alkyne hydrosilylation, 1,3-diene hydrosilylation, hydrogenation, [2π + 2π]-cycloaddition and C-H borylation. The activation protocol proceeds by fluoride dissociation from the counterion, in situ formation of a hydridic activator and generation of a low oxidation-state catalyst.
Iridium(I)-Catalyzed C?H Borylation in Air by Using Mechanochemistry
Pang, Yadong,Ishiyama, Tatsuo,Kubota, Koji,Ito, Hajime
supporting information, p. 4654 - 4659 (2019/03/17)
Mechanochemistry has been applied for the first time to an iridium(I)-catalyzed C?H borylation reaction. By using either none or just a catalytic amount of a liquid, the mechanochemical C?H borylation of a series of heteroaromatic compounds proceeded in air to afford the corresponding arylboronates in good-to-excellent yields. A one-pot mechanochemical C?H borylation/Suzuki–Miyaura cross-coupling sequence for the direct synthesis of 2-aryl indole derivatives is also described. The present study constitutes an important milestone towards the development of industrially attractive solvent-free C?H bond functionalization processes in air.
Ortho-Selective C-H Borylation of Aromatic Ethers with Pinacol-borane by Organo Rare-Earth Catalysts
Xue, Can,Luo, Yong,Teng, Huailong,Ma, Yuanhong,Nishiura, Masayoshi,Hou, Zhaomin
, p. 5017 - 5022 (2018/05/14)
The regioselective C-H borylation of aromatic ethers such as anisoles is of much interest and importance, but has remained a challenge to date. We report herein the catalytic ortho-selective C-H borylation of a wide range of aromatic ethers with pinacolborane (HBpin) by rare-earth metallocene complexes. This protocol offers an efficient and straightforward route for the synthesis of a variety of borylated aromatic ether derivatives. A proper metal/ligand combination for the rare-earth metal catalysts was found to be critically important to promote this transformation.
