Under an argon atmosphere, stirring and cooling with ice, diethyl azodicarboxylate (40% toluene solution, 3.80 mL, 8.38 mmol) was added dropwise to a solution of 2-[4-(tri-fluoromethyl)phenyl]ethanol (1.59 g, 8.36 mmol), isovanillin (1.28 g, 8.41 mmol) and triphenylphosphine (2.20 g, 8.39 mmol) in anhydrous tetrahydrofuran (50 mL). After completion of the dropwise addition, the mixture was stirred for 1 hour under cooling with ice, and then allowed to stand overnight at room temperature. The reaction mixture was concentrated and the residue was purified by silica gel column chro-matography (eluent: n-hexane:ethyl acetate=6:1 v/v) to afford 1.96 g (72%) of the title compound as colorless crystals.
