- Mechanistic studies of the rhodium NHC catalyzed hydrodefluorination of polyfluorotoluenes
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The six-membered-ring NHC complexes Rh(6-NHC)(PPh3)2H (6-NHC = 6-iPr (1), 6-Et (2), 6-Me (3)) have been employed in the catalytic hydrodefluorination (HDF) of C6F5CF3 and 2-C6Fs
- Schwartsburd, Leonid,Mahon, Mary F.,Poulten, Rebecca C.,Warren, Mark R.,Whittlesey, Michael K.
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- Gallium Hydrides and O/N-Donors as Tunable Systems in C?F Bond Activation
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The gallium hydrides (iBu)2GaH (1 a), LiGaH4 (1 b) and Me3N?GaH3 (1 c) hydrodefluorinate vinylic and aromatic C?F bonds when O and N donor molecules are present. 1 b exhibits the highest reactivity. Quantitative conversion to the hydrodefluorination (HDF) products could be observed for hexafluoropropene and 1,1,3,3,3-pentafluoropropene, 94 % conversion of pentafluoropyridine and 49 % of octafluorotoluene. Whereas for the HDF with 1 b high conversions are observed when catalytic amounts of O donor molecules are added, for 1 a, the addition of N donor molecules lead to higher conversions. The E/Z selectivity of the HDF of 1,1,3,3,3-pentafluoropropene is donor-dependent. DFT studies show that HDF proceeds in this case via the gallium hydride dimer–donor species and a hydrometallation/elimination sequence. Selectivities are sensitive to the choice of donor, as the right donor can lead to an on/off switching during catalysis, that is, the hydrometallation step is accelerated by the presence of a donor, but the donor dissociates prior to elimination, allowing the inherently more selective donorless gallium systems to determine the selectivity.
- Jaeger, Alma D.,Walter, Ruben,Ehm, Christian,Lentz, Dieter
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supporting information
p. 2908 - 2915
(2018/09/20)
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- Photocatalytic hydrodefluorination: Facile access to partially fluorinated aromatics
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Polyfluorinated aromatics are essential to materials science as well as the pharmaceutical and agrochemical industries and yet are often difficult to access. This Communication describes a photocatalytic hydrodefluorination approach which begins with easily accessible perfluoroarenes and selectively reduces the C-F bonds. The method allows facile access to a number of partially fluorinated arenes and takes place with unprecedented catalytic activity using a safe and inexpensive amine as the reductant.
- Senaweera, Sameera M.,Singh, Anuradha,Weaver, Jimmie D.
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supporting information
p. 3002 - 3005
(2014/03/21)
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