1423-07-0Relevant articles and documents
Solvent-induced reduction of palladium-aryls, a potential interference in pd catalysis
Molina De La Torre, Jesus A.,Espinet, Pablo,Albeniz, Ana C.
, p. 5428 - 5434 (2013)
The decomposition of the Pd-aryl complex (NBu4) 2[Pd2(μ-Br)2Br2(C 6F5)2] (1) to the reduction product C 6F5H was checked in different solvents and conditions. 1 is not stable in N-alkyl amides (DMF, NMP, DMA), cyclohexanone, and diethers (1,4-dioxane, DME) at high temperatures (above 80 C). Other solvents such as nitriles, THF, water, or toluene are safe, and no significant decomposition occurs. The solvent is the source of hydrogen, and the decomposition mechanisms have been identified by analyzing the reaction products coming from the solvent. β-H elimination involving the methyl group in a N-coordinated amide is the predominant pathway for amides. An O-coordinated diether undergoes β-H elimination and subsequent deprotonation of the resulting oxonium salt to give an enol ether. A palladium enolate from cyclohexanone leads to cyclohexenone, a reaction favored by the presence of a base. Oxygen strongly increases the extent of decomposition, and we propose this occurs by reoxidation of the Pd(0) species formed in the process and regeneration of active Pd(II) complexes.
Photoreductive defluorination of hexafluorobenzene on metal-doped ZnS photocatalysts under visible light irradiation
Kohtani, Shigeru,Ohama, Yoshihiko,Ohno, Yu,Tsuji, Issei,Kudo, Akihiko,Nakagaki, Ryoichi
, p. 1056 - 1057 (2005)
Metal-(Cu, Ni, or Pb) doped ZnS photocatalysts have the ability to photoreductively defluorinate hexafluorobenzene under visible light irradiation; the defluorination mechanism on Pb-, or Cu-doped ZnS is different from that on Ni-doped ZnS. The role of Pb and Cu dopants in ZnS is not only to extend the photocatalytic response toward visible light but also to act as redox reaction sites in the photoreductive defluorination. Copyright
Selective room temperature hydrogenolysis of aromatic fluorocarbons mediated by a low-valent zirconium complex
Kiplinger, Jaqueline L.,Richmond, Thomas G.
, p. 1115 - 1116 (1996)
Treatment of fluorinated aromatic compounds with (C5H5)2ZrCl2, HgCl2, Mg or (C5H5)2ZrCl2, PMe3, Mg results in selective room temperature hydrogenolysis of aromatic C-F bonds.
Pyridine-enabled copper-promoted cross dehydrogenative coupling of C(sp2)-H and unactivated C(sp3)-H bonds
Wu, Xuesong,Zhao, Yan,Ge, Haibo
, p. 5978 - 5983 (2015)
The pyridine-enabled cross dehydrogenative coupling of sp2 C-H bonds of polyfluoroarenes and unactivated sp3 C-H bonds of amides was achieved via a copper-promoted process with good functional group compatibility. This reaction showed great site-selectivity by favoring the sp2 C-H bonds ortho to two fluoro atoms of arenes and the sp3 C-H bonds of α-methyl groups over those of the α-methylene, β- or γ-methyl groups of the aliphatic amides. Mechanistic studies revealed that sp3 C-H bond cleavage is an irreversible but not the rate-determining step, and the sp2 C-H functionalization of arenes appears precedent to the sp3 C-H functionalization of amides in this process.
Synthesis, reactivity and X-ray crystal structure of tris(pentafluorophenyl)silanol (C6F5)3SiOH
Cariati, Elena,Carlucci, Lucia,D'Alfonso, Giuseppe,Giovenzana, Tommaso,Lucenti, Elena,Maggioni, Daniela,Sironi, Angelo
, (2022/01/26)
Tris(pentafluorophenyl)silanol (C6F5)3SiOH was prepared from the corresponding chlorosilane (C6F5)3SiCl by an unconventional controlled hydrolysis. The X-ray structure and the reactivity of
Ranking Ligands by Their Ability to Ease (C6F5)2NiIIL → Ni0L + (C6F5)2Coupling versus Hydrolysis: Outstanding Activity of PEWO Ligands
Ponce-De-León, Jaime,Gioria, Estefania,Martínez-Ilarduya, Jesús M.,Espinet, Pablo
supporting information, p. 18287 - 18294 (2020/12/23)
The NiII literature complex cis-[Ni(C6F5)2(THF)2] is a synthon of cis-Ni(C6F5)2 that allows us to establish a protocol to measure and compare the ligand effect on the NiII → Ni0 reductive elimination step (coupling), often critical in catalytic processes. Several ligands of different types were submitted to this Ni-meter comparison: Bipyridines, chelating diphosphines, monodentate phosphines, PR2(biaryl) phosphines, and PEWO ligands (phosphines with one potentially chelate electron-withdrawing olefin). Extremely different C6F5-C6F5 coupling rates, ranging from totally inactive (producing stable complexes at room temperature) to those inducing almost instantaneous coupling at 25 °C, were found for the different ligands tested. The PR2(biaryl) ligands, very efficient for coupling in Pd, are slow and inefficient in Ni, and the reason for this difference is examined. In contrast, PEWO type ligands are amazingly efficient and provide the lowest coupling barriers ever observed for NiII complexes; they yield up to 96% C6F5-C6F5 coupling in 5 min at 25 °C (the rest is C6F5H) and 100% coupling with no hydrolysis in 8 h at-22 to-53 °C.
Palladium-Catalyzed Direct C-H Allylation of Electron-Deficient Polyfluoroarenes with Alkynes
Zheng, Jun,Breit, Bernhard
supporting information, p. 1866 - 1870 (2018/04/16)
A palladium-catalyzed intermolecular direct C-H allylation of polyfluoroarenes with alkynes is reported. Unlike classic hydroarylation reactions, alkynes are used as allylic electrophile surrogates in this direct aromatic C-H allylation. As an atom-economic and efficient method, various linear allylated fluoroarenes were synthesized from two simple and easy-to-access feedstocks in good to excellent yields, as well as regio- and stereoselectivity.
Metal-Free sp2-C-H Borylation as a Common Reactivity Pattern of Frustrated 2-Aminophenylboranes
Chernichenko, Konstantin,Lindqvist, Markus,Kótai, Bianka,Nieger, Martin,Sorochkina, Kristina,Pápai, Imre,Repo, Timo
, p. 4860 - 4868 (2016/05/10)
C-H borylation is a powerful and atom-efficient method for converting affordable and abundant chemicals into versatile organic reagents used in the production of fine chemicals and functional materials. Herein we report a facile C-H borylation of aromatic and olefinic C-H bonds with 2-aminophenylboranes. Computational and experimental studies reveal that the metal-free C-H insertion proceeds via a frustrated Lewis pair mechanism involving heterolytic splitting of the C-H bond by cooperative action of the amine and boryl groups. The adapted geometry of the reactive B and N centers results in an unprecedentently low kinetic barrier for both insertion into the sp2-C-H bond and intramolecular protonation of the sp2-C-B bond in 2-ammoniophenyl(aryl)- or -(alkenyl)borates. This common reactivity pattern serves as a platform for various catalytic reactions such as C-H borylation and hydrogenation of alkynes. In particular, we demonstrate that simple 2-aminopyridinium salts efficiently catalyze the C-H borylation of hetarenes with catecholborane. This reaction is presumably mediated by a borenium species isoelectronic to 2-aminophenylboranes.
PROCESS FOR PRODUCING METHANOL
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Page/Page column 20, (2011/05/05)
The present invention relates to a novel process for the production of methanol. The process comprises the heterolytic cleavage of hydrogen by a frustrated Lewis pair comprising a Lewis acid and a Lewis base; and the hydrogenation of CO2 with the heterolytically cleaved hydrogen to form methanol.
Polyfluoroorganoboron-oxygen compounds. 2 [1]: Base-catalysed hydrodeboration of polyfluorophenyl(dihydroxy)boranes
Frohn,Adonin,Bardin,Starichenko
, p. 2834 - 2838 (2008/10/08)
Polyfluorinated phenyl(dihydroxy)boranes C6H5-nFnB(OH)2 (n = 3 - 5) underwent hydrodeboration (formal replacement of the (dihydroxy)boryl group by hydrogen) in the presence of bases (MeOH, 33% H2O-MeO
