551-62-2Relevant academic research and scientific papers
A Predictive Model for the Decarboxylation of Silver Benzoate Complexes Relevant to Decarboxylative Coupling Reactions
Crovak, Robert A.,Hoover, Jessica M.
, p. 2434 - 2437 (2018/02/28)
Decarboxylative coupling reactions offer an attractive route to generate functionalized arenes from simple and readily available carboxylic acid coupling partners, yet they are underutilized due to limitations in the scope of carboxylic acid coupling partner. Here we report that the field effect parameter (F) has a substantial influence on the rate of decarboxylation of well-defined silver benzoate complexes. This finding provides the opportunity to surpass current substrate limitations associated with decarboxylation and to enable widespread utilization of decarboxylative coupling reactions.
NHC·Alane Adducts as Hydride Sources in the Hydrodefluorination of Fluoroaromatics and Fluoroolefins
Schneider, Heidi,Hock, Andreas,Jaeger, Alma D.,Lentz, Dieter,Radius, Udo
, p. 4031 - 4043 (2018/09/11)
We present herein the utilization of NHC-stabilized alane adducts of the type (NHC)·AlH3 [NHC = Me2Im (1), Me2ImMe (2), iPr2Im (3), iPr2ImMe (4), Dipp2Im (5)] and (NHC)·AliBu2H [NHC = iPr2Im (6), Dipp2Im (7)] as novel hydride transfer reagents in the hydrodefluorination (HDF) of different fluoroaromatics and hexafluoropropene. Depending on the alane adduct used, HDF of pentafluoropyridine to 2,3,5,6-tetrafluoropyridine in yields of 15–99 % was observed. The adducts 1, 2, and 5 achieved a quantitative conversion into 2,3,5,6-tetrafluoropyridine at room temperature immediately after mixing the reactants. Studies on the HDF of fluorobenzenes with the (NHC)·AlH3 adducts 1, 3, and 5 and (Dipp2Im)·AliBu2H (7) showed the decisive influence of the reaction temperature on the H/F exchange and that 135 °C in xylene afforded the best product distribution. Although the HDF of hexafluorobenzene yielded 1,2,4,5-tetrafluorobenzene in moderate yields with traces of 1,2,3,4-tetrafluorobenzene and 1,2,4-trifluorobenzene, pentafluorobenzene was converted quantitatively into 1,2,4,5-tetrafluorobenzene, with (Dipp2Im)·AliBu2H (7) showing the highest activity and reaching complete conversion after 12 h at 135 °C in xylene. The HDF of hexafluoropropene with (Me2Im)·AlH3 (1) occurred even at low temperatures and preferably at the CF2 group with the formation of 1,2,3,3,3-pentafluoropropene (with 0.4 equiv. of 1) or 2,3,3,3-tetra-fluoropropene (with 0.9 equiv. of 1) as the main product.
Transition-Metal-Free Catalytic Hydrodefluorination of Polyfluoroarenes by Concerted Nucleophilic Aromatic Substitution with a Hydrosilicate
Kikushima, Kotaro,Grellier, Mary,Ohashi, Masato,Ogoshi, Sensuke
supporting information, p. 16191 - 16196 (2017/11/27)
A transition-metal-free catalytic hydrodefluorination (HDF) reaction of polyfluoroarenes is described. The reaction involves direct hydride transfer from a hydrosilicate as the key intermediate, which is generated from a hydrosilane and a fluoride salt. The eliminated fluoride regenerates the hydrosilicate to complete the catalytic cycle. Dispersion-corrected DFT calculations indicated that the HDF reaction proceeds through a concerted nucleophilic aromatic substitution (CSNAr) process.
Base-Catalyzed Aryl-B(OH)2 Protodeboronation Revisited: From Concerted Proton Transfer to Liberation of a Transient Aryl Anion
Cox, Paul A.,Reid, Marc,Leach, Andrew G.,Campbell, Andrew D.,King, Edward J.,Lloyd-Jones, Guy C.
supporting information, p. 13156 - 13165 (2017/09/26)
Pioneering studies by Kuivila, published more than 50 years ago, suggested ipso protonation of the boronate as the mechanism for base-catalyzed protodeboronation of arylboronic acids. However, the study was limited to UV spectrophotometric analysis under acidic conditions, and the aqueous association constants (Ka) were estimated. By means of NMR, stopped-flow IR, and quenched-flow techniques, the kinetics of base-catalyzed protodeboronation of 30 different arylboronic acids has now been determined at pH > 13 in aqueous dioxane at 70 °C. Included in the study are all 20 isomers of C6HnF(5-n)B(OH)2 with half-lives spanning 9 orders of magnitude: a and Sδ values, kinetic isotope effects (2H, 10B, 13C), linear free-energy relationships, and density functional theory calculations, we have identified a mechanistic regime involving unimolecular heterolysis of the boronate competing with concerted ipso protonation/C-B cleavage. The relative Lewis acidities of arylboronic acids do not correlate with their protodeboronation rates, especially when ortho substituents are present. Notably, 3,5-dinitrophenylboronic acid is orders of magnitude more stable than tetra-and pentafluorophenylboronic acids but has a similar pKa.
A decarboxylation multi-monofluoro-benzene multifluoro-benzoic acid by the method of preparation (by machine translation)
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Paragraph 0047; 0048, (2017/03/25)
This invention relates to a kind of the ammonia in the high-temperature liquid aqueous medium, in the copper-containing solid acid catalyst, reaction [...] multifluoro-benzoic acid by the method of preparation multi-monofluoro-benzene. The method disclosed by the present invention do not need to use organic solvent, cheap catalyst, has fast reaction speed, reaction time is short, the advantage of high product yield. (by machine translation)
Method for preparing 2,3,4,5-tetrafluoro benzoic acid and 1,2,3,4-tetrafluorobenzene
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Paragraph 0039; 0040, (2016/11/28)
The present invention discloses a method for preparing 2,3,4,5-tetrafluoro benzoic acid and 1,2,3,4-tetrafluorobenzene through a decarboxylation reaction of tetrafluoro phthalic acid at a reaction temperature of 180-250 DEG C in an ammonia-containing high-temperature liquid-state water medium. The method of the present invention has characteristics of high decarboxylation reaction rate, short decarboxylation reaction time, high yield, and green environmental protection.
Hydrodefluorination of fluoroaromatics by isopropyl alcohol catalyzed by a ruthenium NHC complex. An unusual role of the carbene ligand
Mai, Van Hung,Nikonov, Georgii I.
, p. 7956 - 7961 (2018/05/23)
The NHC (NHC = N-heterocyclic carbene) complex Cp*(IPr)RuH3 catalyzes hydrodefluorination of aromatic fluorides at 70 °C with isopropyl alcohol as the reducing reagent. The reaction is selective for aromatic fluorides, as almost negligible C(sp3)?F bond reduction takes place. The activity decreases from more to less fluorinated substrates, but polyaromatic monofluorides, such as 1-fluoronaphthalene and 6-fluoro-2-methylquinoline, can also be reduced in moderate to good yields. Kinetic studies are consistent with a mechanism based on elimination of NHC and reversible substrate coordination, followed by coordination of the alcohol.
Competition of Nucleophilic Aromatic Substitution, σ-Bond Metathesis, and syn Hydrometalation in Titanium(III)-Catalyzed Hydrodefluorination of Arenes
Krüger, Juliane,Leppkes, Jakob,Ehm, Christian,Lentz, Dieter
, p. 3062 - 3071 (2016/11/13)
Several functionalized and non-functionalized perfluoroarenes were catalytically transformed into their para-hydrodefluorinated products by using catalytic amounts of titanocene difluoride and stoichiometric amounts diphenylsilane. Turnover numbers of up to 93 were observed. Solution density functional theory calculations at the M06-2X/TZ(PCM)//M06-2X/TZ(PCM) level of theory provided insight into the mechanism of TiIII-catalyzed aromatic hydrodefluorination. Two different substrate approaches, with a Ti–F interaction (pathway A) and without a Ti–F interaction (pathway B), are possible. Pathway A leads to a σ-bond metathesis transition state, whereas pathway B proceeds by means of a two-step mechanism through a syn-hydrometalation intermediate or through a Meisenheimer intermediate. Both pathways are competitive over a broad range of substrates.
Rhodium catalyzed, carbon-hydrogen bond directed hydrodefluorination of fluoroarenes
Ekkert, Olga,Strudley, Sebastian D. A.,Rozenfeld, Alisa,White, Andrew J. P.,Crimmin, Mark R.
supporting information, p. 7027 - 7030 (2015/05/19)
[CpRhCl(μ-Cl)]2 is reported as a highly efficient and selective precatalyst for the hydrodefluorination of perfluoroarenes using a hydrocarbon-soluble aluminum dihydride as the terminal reductant. Reactions are directed to cleave a C-F bond adjacent to an existing C-H bond with high regioselectivity (98.5-99%). A heterobimetallic complex containing an extremely rare Al-H-Rh functional group has been isolated and shown to be catalytically competent.
Hydrodeboration of potassium polyfluoroaryl(fluoro)borates with alcohols
Adonin, Nicolay Yu.,Shabalin, Anton Yu.,Bardin, Vadim V.
, p. 111 - 120 (2015/03/05)
Potassium polyfluoroaryltrifluoroborates, K[ArFBF3] (ArF = C6F5, HC6F4, MeC6F4, 4-MeOC6F4, 4-indol-1-ylC6F4, 4-i
