1,2,3,4-Tetramethylbenzene → (Bromomethyl)(phenyl)(2,3,4,5-tetramethylphenyl)sulfonium tetrafluoroborate

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Reaction Steps

Bromomethyl phenyl sulfoxide (1 g, 4.58 mmol) of example 32 was dissolved in dry diethyl ether (30 mL) under an argon atmosphere. 1,2,3,4-tetramethylbenzene (0.678 g, 1.09 eq) was added to the previous solution and then the mixture was cooled to a temperature below −60° C. After stabilizing the temperature, trifluoromethanesulfonic anhydride (0.77 mL, 1 eq) was added slowly, maintaining the same temperature. The mixture was stirred until the reaction was complete. After 3 hours at −60° C., HBF4 in diethyl ether was added (54%, 1.11 mL, 1.75 eq). The resulting suspension was stirred for 30 minutes. The precipitated tetrafluoroborate salt formed was isolated by filtration and dried under vacuum. 1.24 g (62%) of the desired product was obtained as a white solid. mp: 140-142° C.

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