1073338-90-5Relevant articles and documents
Iron-catalysed C(sp2)-H borylation enabled by carboxylate activation
Britton, Luke,Docherty, Jamie H.,Dominey, Andrew P.,Thomas, Stephen P.
, (2020)
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-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.
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.
