850567-47-4Relevant academic research and scientific papers
Cross-Coupling through Ag(I)/Ag(III) Redox Manifold
Demonti, Luca,Mézailles, Nicolas,Nebra, Noel,Saffon-Merceron, Nathalie
supporting information, p. 15396 - 15405 (2021/10/12)
In ample variety of transformations, the presence of silver as an additive or co-catalyst is believed to be innocuous for the efficiency of the operating metal catalyst. Even though Ag additives are required often as coupling partners, oxidants or halide scavengers, its role as a catalytically competent species is widely neglected in cross-coupling reactions. Most likely, this is due to the erroneously assumed incapacity of Ag to undergo 2e? redox steps. Definite proof is herein provided for the required elementary steps to accomplish the oxidative trifluoromethylation of arenes through AgI/AgIII redox catalysis (i. e. CEL coupling), namely: i) easy AgI/AgIII 2e? oxidation mediated by air; ii) bpy/phen ligation to AgIII; iii) boron-to-AgIII aryl transfer; and iv) ulterior reductive elimination of benzotrifluorides from an [aryl-AgIII-CF3] fragment. More precisely, an ultimate entry and full characterization of organosilver(III) compounds [K]+[AgIII(CF3)4]? (K-1), [(bpy)AgIII(CF3)3] (2) and [(phen)AgIII(CF3)3] (3), is described. The utility of 3 in cross-coupling has been showcased unambiguously, and a large variety of arylboron compounds was trifluoromethylated via [AgIII(aryl)(CF3)3]? intermediates. This work breaks with old stereotypes and misconceptions regarding the inability of Ag to undergo cross-coupling by itself.
Organophosphorus-catalyzed relay oxidation of H-Bpin: electrophilic C-H borylation of heteroarenes
Lipshultz, Jeffrey M.,Fu, Yue,Liu, Peng,Radosevich, Alexander T.
, p. 1031 - 1037 (2021/02/06)
A nontrigonal phosphorus triamide (1, P{N[o-NMe-C6H4]2}) is shown to catalyze C-H borylation of electron-rich heteroarenes with pinacolborane (HBpin) in the presence of a mild chloroalkane reagent. C-H borylation proceeds for a range of electron-rich heterocycles including pyrroles, indoles, and thiophenes of varied substitution. Mechanistic studies implicate an initial P-N cooperative activation of HBpin by1to giveP-hydrido diazaphospholene2, which is diverted by Atherton-Todd oxidation with chloroalkane to generateP-chloro diazaphospholene3. DFT calculations suggest subsequent oxidation of pinacolborane by3generates chloropinacolborane (ClBpin) as a transient electrophilic borylating species, consistent with observed substituent effects and regiochemical outcomes. These results illustrate the targeted diversion of established reaction pathways in organophosphorus catalysis to enable a new mode of main group-catalyzed C-H borylation.
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
supporting information, 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.
Nickel-Catalyzed C(sp2)-H Borylation of Arenes
Das, Arpan,Hota, Pradip Kumar,Mandal, Swadhin K.
, (2019/09/12)
In this study, C(sp2)-H borylation of arenes was accomplished by a nickel catalyst, resulting in good yield. Alkyl and alkoxy arenes were successfully functionalized, affording C(sp2)-H borylated compounds. It was unraveled that the well-defined abnormal N-heterocyclic carbene based Ni(II) complex breaks into Ni nanoparticles (Ni-NPs), which act as catalytically active species. A series of controlled reactions under stoichiometric conditions along with spectroscopic studies and single-crystal X-ray crystallographic study helped us to understand the formation of Ni-NPs along with formation of a boron(III) compound during this reaction.
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.
Cobalt-Catalyzed C-H Borylation of Alkyl Arenes and Heteroarenes Including the First Selective Borylations of Secondary Benzylic C-H Bonds
Jayasundara, Chathurika R. K.,Sabasovs, Dmitrijs,Staples, Richard J.,Oppenheimer, Jossian,Smith, Milton R.,Maleczka, Robert E.
, p. 1567 - 1574 (2018/06/04)
A cobalt di-tert-butoxide complex bearing N-heterocyclic carbene (NHC) ligands has been synthesized and characterized. This complex is effective at catalyzing the selective monoborylation of the benzylic position of alkyl arenes using pinacolborane (HBpin) as the boron source. This same cobalt complex enables selective monoborylation of N-methylpyrrole, N-methylpyrazole, and N-methylindole. Catalysis can be achieved with as little as 2-3 mol % of the cobalt precatalyst at 80 °C.
Significantly improved performance of dye-sensitized solar cells by optimizing organic dyes with pyrrole as the isolation spacer and utilizing alkyl chain engineering
Wang, Jinfeng,Liu, Siwei,Chai, Zhaofei,Chang, Kai,Fang, Manman,Han, Mengmeng,Wang, Yiyi,Li, Sheng,Han, Hongwei,Li, Qianqian,Li, Zhen
, p. 22256 - 22265 (2018/11/24)
The optimization of interfacial and intramolecular charge transfer of organic dyes is crucial to the photovoltaic performance of dye-sensitized solar cells. In this study, an efficient strategy was afforded by the introduction of alkylated pyrrole as the isolation spacer into organic dyes. The interfacial charge transfer can be organized by the tunable alkyl chains as a barrier layer to inhibit electron recombination, and the pull-push system can be strengthened by the incorporation of electron-withdrawing units (benzothiadiazole) and electron-rich moieties (pyrrole) into the conjugated bridge simultaneously, resulting in excellent light-harvesting capability. Therefore, the high conversion efficiency of 9.70% was achieved by LI-124 with suitable alkyl chains and device optimization.
Practical and Scalable Synthesis of Borylated Heterocycles Using Bench-Stable Precursors of Metal-Free Lewis Pair Catalysts
Jayaraman, Arumugam,Misal Castro, Luis C.,Fontaine, Frédéric-Georges
supporting information, p. 1489 - 1499 (2018/10/26)
A practical and scalable metal-free catalytic method for the borylation and borylative dearomatization of heteroarenes has been developed. This synthetic method uses inexpensive and conveniently synthesizable bench-stable precatalysts of the form 1-NHR2-2-BF3-C6H4, commercially and synthetically accessible heteroarenes as substrates, and pinacolborane as the borylation reagent. The preparation of several borylated heterocycles on 2 and 50 g scales was achieved under solvent-free conditions without the use of Schlenk techniques or a glovebox. A kilogram-scale borylation of one of the heteroarene substrates was also achieved using this cost-effective green methodology to exemplify the fact that our methodology can be conveniently implemented in fine chemical industries.
PRECATALYSTS AND PROCESS FOR THE METAL-FREE FUNCTIONALIZATION OF SP2 CARBONS USING THE SAME
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Paragraph 0185; 0186; 0187; 0188; 0189; 0206; 0207, (2018/10/24)
Precatalysts of formula I and IV, and processes for the functionalization of SP2-carbons using the same are described herein. The precatalysts comprise a fluoroborate salt protected intramolecular frustrated lewis pair (FLP). The precatalysts are bench stable with improved stability towards moisture and/or air. The precatalysts can be used to generate in situ the corresponding FLP catalyst.
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.
