P-Xylene → (2,5-Dimethylphenyl)(fluoromethyl)(p-tolyl)sulfonium tetrafluoroborate

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Reaction Steps

1-((fluoromethyl)sulfinyl)-4-methylbenzene (535 mg, 3.38 mmol) of example 5 was dissolved in dry diethyl ether (15 mL) under an argon atmosphere. P-xylene (0.42 mL, 1.0 eq) was added to the previous solution. The mixture was cooled to a temperature below −50° C. After stabilizing the temperature, trifluoromethanesulfonic anhydride (0.52 mL, 0.92 eq) was added slowly maintaining the same temperature. The mixture was stirred, at the same temperature, until the reaction was complete. HBF4 in diethyl ether solution (54%, 1.29 mL, 2.77 eq) was added. The resulting suspension was stirred for 30 minutes. The precipitate tetrafluoroborate salt was isolated by filtration and washed with diethyl ether at 0° C. The desired product was obtained as a slightly yellow oily solid (2.25 g). after heating at room temperature

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