A mixture of (E)-4-(4-((dimethylamino)methyl)benzylideneamino)isobenzofuran-1(3H)-one (588 mg, 2 mmol) and 4-isopropylbenzaldehyde (296 mg, 2 mmol) in ethyl propionate (15 mL) was cooled to 0° C. Then a solution of sodium ethoxide in ethanol (sodium (138 mg, 6 mmol) in ethanol (5 mL)) was added dropwise. After the addition, the mixture was stirred at room temperature for 3 hr. The mixture was quenched with water (10 mL) and solvent was removed in vacuum. The residue was dissolved in water, and then extracted with ethyl acetate (100 mL×4). The combined organic layers were washed with brine, dried over anhydrous sodium sulfate, and concentrated to give crude product, which was then purified by column chromatography (silica gel, petroleum ether/ethyl acetate=1:1) to give the title compound (210 mg, yield 22%). LC-MS (ESI) m/z: 471 (M+1)+.
