- The use of methyl 2,2-difluoro-2-(fluorosulfonyl)acetate as the difluorocarbene source to generate an in situ source of difluoromethylene triphenylphosphonium ylide
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Under moderate conditions in the presence of a demethylating reagent, such as iodide, methyl 2,2,-difluoro-2-(fluorosulfonyl)acetate (MDFA) releases difluorocarbene, which in the presence of triphenylphosphine forms difluoromethylene triphenylphosphonium ylide. When the process is carried out also in the presence of aldehydes or activated ketones, the ensuing in situ Wittig-type reaction of the ylide with the carbonyl reactants produces 1,1-difluoroalkenes in good yield. Density Functional Theory calculations were used to provide new estimates of the energies and structures of singlet and triplet states of CH2:, CHF:, and CF2: carbenes, as well as those of their respective triphenylphosphonium ylides.
- Thomoson, Charles S.,Martinez, Henry,Dolbier Jr., William R.
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- Reductive transformations of organofluorine compounds: II. Hydrodechlorination of chloropolyfluoroarenes by the action of zinc
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Polyfluoroarenes containing chlorine atoms in the aromatic ring and/or in the benzylic position undergo hydrodechlorination by the action of zinc in aqueous dimethylformamide. The use of Zn/Cu and addition of salts (NaCl, Na2SO4, NH4Cl) favor reductive dechlorination of the Carom - Cl bond. Polyfluorobenzotrichlorides react with excess zinc to give the corresponding CH3-substituted derivatives, otherwise CH2Cl- and CHCl2-containing compounds are formed. The reduction of C6F5CCl3 and C6F5CH2Cl with zinc in the presence of copper provides lower yields of the hydrodechlorination products and leads to formation of 1,2-bis(pentafluorophenyl)ethane.
- Krasnov,Platonov
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p. 1488 - 1499
(2007/10/03)
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- A New Route for the Preparation of Substituted 2,2-Difluorostyrenes and a Convenient Route to Substituted (2,2,2-Trifluoroethyl)benzenes
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The (2,2-difluoroethenyl)zinc reagent II is coupled with aryl iodides or bromides in the presence of Pd(PPh3)4 in DMF to give the corresponding 2,2-difluorostyrenes IV. The 4-substituted (tetrafluoroaryl)copper reagents are coupled with 2,2-difluoro-1-iodoethylene (I) to produce the corresponding styrene derivatives VII. Both methods provide good yields of the coupled products. These products react with wet KF in DMF or DMSO to form the (2,2,2-trifluoroethyl)benzene derivatives VIII in good yields.
- Nguyen, Ba V.,Burton, Donald J.
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p. 7758 - 7764
(2007/10/03)
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- PREPARATION AND SYNTHETIC UTILITY OF FLUORINATED PHOSPHONIUM SALTS, BISPHOSPHONIUM SALTS AND PHOSPHORANIUM SALTS
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The reaction of tertiary phosphines with fluorohalomethanes provides a rapid and high yield synthesis of various types of fluorinated phosphonium salts, bis-phosphonium salts and phosphoranium salts.These salts are useful precursors to fluorine-containing
- Burton, Donald J.
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p. 339 - 358
(2007/10/02)
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- Proton-Transfer Reactions. 3. Differences in the Protonation of Localized and Delocalized Carbanion Intermediates
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Rates, activation parameters, and product distributions are reported for the reaction of methanolic sodium methoxide with XC6H4CH = CF2 (V) and C6F5CH = CF2 (IX) and compared to previously reported results for C6H5C(CF3) = CF2 (I).A ρ = 3.5 was calculated
- Koch, Heinz F.,Koch, Judith G.,Koch, Nanci H,,Koch, Andrew S.
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p. 2388 - 2393
(2007/10/02)
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- Metal Dehalogenation Route To Reactive Fluoroolefins
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Metal dehalogenation of bromodifluoromethyltriphenylphosphonium bromide with Cd, Zn, or Hg provides a practical route to fluoroolefins that contain an allylic halogen or a pentafluorophenyl group.No SN2' or ring substituted products are observed.
- Burton, D. J.,Kesling, H. S.,Naae, D. G.
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p. 293 - 298
(2007/10/02)
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