- Protodeboronation of (Hetero)Arylboronic Esters: Direct versus Prehydrolytic Pathways and Self-/Auto-Catalysis
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The kinetics and mechanism of the base-catalyzed hydrolysis (ArB(OR)2→ ArB(OH)2) and protodeboronation (ArB(OR)2→ ArH) of a series of boronic esters, encompassing eight different polyols and 10 polyfluoroaryl and heteroaryl moieties, have been investigated by in situ and stopped-flow NMR spectroscopy (19F,1H, and11B), pH-rate dependence, isotope entrainment,2H KIEs, and KS-DFT computations. The study reveals the phenomenological stability of boronic esters under basic aqueous-organic conditions to be highly nuanced. In contrast to common assumption, esterification does not necessarily impart greater stability compared to the corresponding boronic acid. Moreover, hydrolysis of the ester to the boronic acid can be a dominant component of the overall protodeboronation process, augmented by self-, auto-, and oxidative (phenolic) catalysis when the pH is close to the pKaof the boronic acid/ester.
- Hayes, Hannah L. D.,Wei, Ran,Assante, Michele,Geogheghan, Katherine J.,Jin, Na,Tomasi, Simone,Noonan, Gary,Leach, Andrew G.,Lloyd-Jones, Guy C.
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supporting information
p. 14814 - 14826
(2021/09/13)
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- An efficient method for the hydrolysis of potassium organotrifluoroborates promoted by montmorillonite K10
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An efficient and non-expensive method for conversion of diverse potassium organotrifluoroborates to their corresponding boronic acids promoted by montmorillonite K10 using water as the reaction solvent is described. Further interconversion of potassium organotrifluoroborates to their corresponding boronic esters, via boronic acid intermediates was also successfully accomplished. The products were obtained in good yields, being the rate of hydrolysis influenced by the type of substituent present in the boronic acid.
- Silva, Renato L.,Santos, Cosme S.,Santos, Jonh A. M.,Oliveira, Roberta A.,Menezes, Paulo H.,Freitas, Juliano C. R.
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p. 1777 - 1785
(2018/09/04)
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- 1-cyclopropyl-4-oxo-7-fluoro-8-methoxy -1,4-dihydro-quinoline-3-carboxylic acid synthesizing method
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The invention discloses a synthesis method of 1-cyclopropyl-4-oxo-7-fluoro-8-methoxy-1,4-dihydroquinolyl-3-carboxylic acid. The synthesis method comprises the following reaction steps: reacting m-difluorophenyl with an organolithium reagent, reacting an obtained aryllithium intermediate with borate, quenching to obtain 2,6-difluorophenylboronic acid and 2,6-difluorophenylborate, reacting 2,6-difluorophenol obtained through oxidation with a methylating reagent, reacting the obtained 2,6-difluorophenylmethyl ether with the organolithium reagent, reacting the obtained corresponding aryllithium intermediate with carbon dioxide, reacting the obtained product with an acylchlorinating reagent to obtain 2,4-difluoro-3-methoxy benzoyl chloride, and performing cyclization, hydrolysis and the like to obtain the 1-cyclopropyl-4-oxo-7-fluoro-8-methoxy-1,4-dihydroquinolyl-3-carboxylic acid. The synthesis method has the advantages as follows: raw materials are easy to obtain; the yield in each step is high; the atom economy is high; the synthesis method is suitable for industrial application.
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Paragraph 0023; 0066; 0067
(2017/01/26)
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- Iron trichloride promoted hydrolysis of potassium organotrifluoroborates
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In the presence of iron trichloride, the hydrolysis of potassium organotrifluoroborates occurs smoothly at room temperature to afford the corresponding organoboronic acids in good to excellent yields. The hydrolysis is effective for aryltrifluoroborates as well as alkenyl- and alkyl- trifluoroborates.
- Blevins, David W.,Yao, Min-Liang,Yong, Li,Kabalka, George W.
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experimental part
p. 6534 - 6536
(2011/12/22)
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- Synthesis and mesomorphic properties of some fluorinated benzoate liquid crystals
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Three series of [4-(4′-n-alkyloxyphenyl)acetylenyl]-2,6- difluorophenyl fluorinated benezoates and one series of fluorinated benzoates with 2,3,5,6-tetrafluorophenylene group and semi-perfluorocarbon chain have been synthesized. Their phase transition temperatures have been measured by texture observation in a polarizing microscope and confirmed by DSC. For the series without fluorocarbon chains, increasing the quantity of fluorosubstituents on the terminal phenyl groups decreased nematic stability (TN-I), but the breadth of the SmA phase range was increased. Lateral fluorosubstitution in the central group lowered the nematic stability (TN-I) and decreased the breadth of the SmA phase range. The series with semiperfluorocarbon chains were more likely to form SmA phases than the series with hydrogencarbon chains, and with the increasing of fluorosubstituents quantity on the terminal phenyl groups nematic and SmA stability (TN-I and TsmA-N) were both decreased.
- Yang, Yong Gang,Chen,Tang,Wen
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- Indazole compounds, pharmaceutical compositions, and methods for mediating or inhibiting cell proliferation
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Indazole compounds that modulate and/or inhibit cell proliferation, such as the activity of protein kinases are described. These compounds and pharmaceutical compositions containing them are capable of mediating, e.g., kinases-dependent diseases to modulate and/or inhibit unwanted cell proliferation. The invention is also directed to the therapeutic or prophylactic use of pharmaceutical compositions containing such compounds, and to methods of treating cancer as well as other disease states associated with unwanted angiogenesis and/or cellular proliferation, such as diabetic retinopathy, neovascular glaucoma, rheumatoid arthritis, and psoriasis, by administering effective amounts of such compounds.
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- Polyfluoroorganoboron-oxygen compounds. 1: Polyfluorinated aryl(dihydroxy)boranes and tri(aryl)boroxins
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A general preparative procedure for polyfluorinated aryl(dihydroxy)boranes C6H5-nFnB(OH)2 (n = 3 - 5) is described. Polyfluorinated aryl(dihydroxy)boranes are easily dehydrated to the corresponding tri(aryl)boroxins (C6H5-nFnBO)3 by thermal or chemical treatment. The property of the acids C6H5-nFnB(OH)2 to condensate depends on the number and on the position of the fluorine atoms in the aryl group. Examples of both classes of boron compounds were isolated as pure individuals and characterized by multinuclear NMR spectroscopy.
- Frohn,Adonin,Bardin,Starichenko
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p. 2827 - 2833
(2008/10/08)
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- (Fluoroorgano)fluoroboranes and -fluoroborates I: Synthesis and spectroscopic characterization of potassium fluoroaryltrifluoroborates and fluoroaryldifluoroboranes
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A convenient preparation of K[ArBF3] (Ar=2-C6H4F, 3-C6H4F, 4-C6H4F, 2,6-C6H3F2, 3,5-C6H3F2, 2,4,6-C6H2F3, 3,4,5-C6H2F3, 2,3,4,5-C6HF4 and C6F5) is offered and the IR and multinuclear NMR spectra of these salts are reported. Treatment of the trifluoroborate salts with BF3 in chlorocarbon solvents provides an easy synthetic route to the corresponding aryldifluoroboranes ArBF2. The multinuclear NMR spectra of ArBF2 are presented. The electron substituent effect of the [-BF3]--group shows this substituent as one of the strongest σ-electron donors, while its π-electron influence is negligible (σI=-0.32, σR=-0.07).
- Frohn,Franke,Fritzen,Bardin
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p. 127 - 135
(2007/10/03)
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