Direct Hydrofluorination of Methallyl Alkenes Using a Methanesulfonic Acid/Triethylamine Trihydrofluoride Combination
Xavier Bertrand and Jean-François Paquin*
*CCVC, PROTEO, Département de chimie, Université Laval, 1045 Avenue de la Médecine, Québec, Québec, G1V 0A6, Canada,
Email: jean-francois.paquin
chm.ulaval.ca
X. Bertrand, J.-F. Paquin, Org. Lett., 2019, 21, 9759-9762.
DOI: 10.1021/acs.orglett.9b03950
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Abstract
A combination of methanesulfonic acid and triethylamine trihydrofluoride enables a direct hydrofluorination of methallyl-containing substrates under those metal-free conditions that use readily available, cheap, and easy to handle reagents. A range of methallyl alkenes could be converted to their corresponding tertiary fluorides in good yield.
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General procedure
The alkene (1 equiv.) was added to CH2Cl2 (0.2 M) in a polystyrene conical tube. Triethylamine trihydrofluoride (5.0 equiv.) and methanesulfonic acid (5.0 equiv.) were added and the mixture was stirred at room temperature. Upon reaction completion, the mixture was washed with aq. sat. NaHCO3, dried over Na2SO4, filtered and concentrated under reduced pressure. A known amount of 2-fluoro-4-nitrotoluene was added and a NMR yield was determined by 19F NMR. If applicable, purification by flash chromatography afforded the final product.
Hydrohalogenation of Unactivated Alkenes Using a Methanesulfonic Acid/Halide Salt Combination
X. Bertrand, P. Paquin, L. Chabaud, J.-F. Paquin, Synthesis, 2022, 54, 1413-1421.
Key Words
ID: J54-Y2019
