A mixture of N-(4-methoxybenzyl)-2-oxo-N-(1-oxo-1,3-dihydroisobenzofuran-4-yl)-2-phenylacetamide (4.7 g, 11.7 mmol) and anhydrous Na2SO4 (16.6 g, 117 mmol) in anhydrous ethyl propionate (120 mL) was cooled to 0° C. Then a solution of sodium ethoxide in ethanol (sodium (673 mg, 29.2 mmol) in anhydrous ethanol (70 mL)) was added dropwise. After the addition, the mixture was stirred at room temperature for 18 hr. The mixture was quenched with water (100 mL) and solvent was removed in vacuum. The residue was dissolved in water, and then extracted with ethyl acetate (250 mL×4). The combined organic layers were washed with brine, dried over anhydrous sodium sulfate, and concentrated to give product (4.02 g, yield 80%). LC-MS (ESI) m/z: 430 (M+1)+. 1H-NMR (400 MHz, DMSO-d6) δ (ppm): 1.23-1.26 (t, J=6.8 Hz, 3H), 3.69 (s, 3H), 4.21-4.23 (m, 2H), 5.46 (s, 1H), 6.86-6.88 (d, J=7.6 Hz, 2H), 7.11-7.18 (m, 3H), 7.36-7.55 (m, 7H), 10.59 (s, 1H).
