79186-48-4Relevant articles and documents
Mild copper-catalyzed fluorination of alkyl triflates with potassium fluoride
Dang, Hester,Mailig, Melrose,Lalic, Gojko
, p. 6473 - 6476 (2014/06/24)
A chemoselective catalytic fluorination of alkyl triflates is described using potassium fluoride as a fluoride source. Excellent yields of the desired alkyl fluorides are obtained after one hour at 45°C using 2 mol% of the copper catalyst. With 10 mol% of the catalyst, full conversion can be achieved in less than 10 minutes at 45°C, and thus makes this procedure potentially suited for the preparation of 18F-labeled PET probes. As a result of the mild reaction conditions, only the substitution products are observed with no evidence of common side reactions, such as elimination. Reported is a preliminary study of the reaction scope, which demonstrates that the fluorination can be performed in the presence of a wide range of functional groups. Evidence suggests an unusual role of the [IPrCuOTf] catalyst as a phase-transfer catalyst and points to [IPrCuF] as the active fluorinating reagent (IPr=1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene).
Effect of reaction conditions on the kinetic and activation parameters for the mild introduction of fluorine into α-substituted styrenes with AccufluorTM NFTh
Stavber, Stojan,Pecan, Tjasa Sotler,Zupan, Marko
, p. 1141 - 1146 (2007/10/03)
Kinetic studies on fluorination of α-substituted styrenes with 1-fluoro-4-hydroxy-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (AccufluorTM NFTh) in acetonitrile or in acetonitrile in the presence of methanol or water as nucleophiles were carried out. These reactions exhibited overall second-order kinetics and formed Markovnikov type products. The corresponding second-order rate constants for fluorination of the studied substrates in the presence of methanol at 38.8 deg C are k2 = 1.1 x 10-3 M-1 s-1 for styrene (1a), 3.3 x 10-2 M-1 s-1 for α-methylstyrene (1b) and 3.4 x 10-2 M-1 s-1 for 1,1-diphenylethene (1c). The substitution of methanol as nucleophile by water had very little effect on the rate of the process. Solvent polarity variation (Grunwald-Winstein Ybenzyl) showed a similar small effect, too, indicating negligible change in the polarity of the rate-determining transition state in comparison with the reactants. Activation enthalpies (between 62 and 80 kJ mol-1) and activation antropies (between -74 and 32 J mol-1 K-1) were determined for fluorination of α-substituted styrenes with NFTh in acetonitrile in the presence of methanol and water as nucleophiles. Hammett correlation analysis of the reaction of substituted styrenes with NFTh in MeCN MeCN-H2O and MeCN-MeOH gave reaction constants ρ+ of -1.48, -1.52 and -1.80, respectively, which support our belief in the mainly non-polar character of the rate-determining transition state of the studied reactions.
A mild, selective method for preparation of vicinal fluoro ethers using 'F-Teda-BF4
Stavber,Sotler,Zupan
, p. 1105 - 1108 (2007/10/02)
Vicinal alkoxy fluorides are efficiently formed by room temperature reaction of phenyl substituted alkenes with commercially available 1- chloromethyl-4-fluoro-1,4-diazobicyclo[2.2.2]octane bis tetrafluoroborate (Selectfluor(TM) F-Teda BF4) in
