Trifluoromethanesulfonic anhydride → trifluoromethanesulfonic acid 4-{1-ethyl-1-[(E)-4-(3-ethyl-3-hydroxy-1-pentenyl)-3-methyl-phenyl]-propyl}-2,6-dimethyl-phenyl Ester

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Reaction Conditions

Reaction Steps

Diisopropylethylamine (2.2 mL, 12.92 mmol) and trifluoromethanesulfonic anhydride (1.3 mL, 7.75 mmol) were added to a solution of 4-{1-ethyl-1-[(E)-4-(3-ethyl-3-hydroxy-1-pentenyl)-3-methyl-phenyl]-propyl}-2,6-dimethyl-phenol (Example 38-(4); 2.55 g, 6.46 mmol) in dichloromethane (30 mL) at −40° C., and the mixture was stirred at −40° C. for 10 minutes. A saturated aqueous sodium bicarbonate solution was added to the reaction mixture, which was then heated to room temperature and extracted with dichloromethane. The organic layer was dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure. The resulting residue was purified by silica gel chromatography (hexane:ethyl acetate=100:0 to 50:50, 40 minutes) to give the target compound as a colorless oil (2.92 g, 86%).

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