Diethyl carbonate (23.6 g, 200 mmol, 4.0 eq.) was slowly added to a stirred mixture of sodium hydride suspension (60% dispersed in mineral oil, 7.20 g, 180 mmol, 3.6 eq.) and toluene (300 mL) at room temperature. After stirring for 15 minutes, o-toluidine (6.70 g, 50.0 mmol, 1.0 eq.) was added and the reaction mixture was heated to reflux and maintained for 18 hours. Subsequently, glacial acetic acid (15 mL) was added dropwise over 10 minutes, followed by careful addition of ice water (150 mL). The mixture was extracted with ethyl acetate and the combined organic layers were dried over magnesium sulfate and subsequently concentrated under reduced pressure. The resulting residue was purified by silica gel fast column chromatography (elution gradient: 0 to 5% ethyl acetate in pentane solution) to afford 7.94 g (77% yield) of ethyl 3-oxo-3-(2-methylphenyl)propanoate as an oil (ketone/enol interconjugate isomer ratio 4:1).1H NMR (ketone interconjugate isomer) (400 MHz, CDCl3) δ: 7.66 (s 1H), 7.41 (s, 1H), 7.30-7.25 (m, 2H), 4.22-4.15 (m, 2H), 3.96-3.94 (m, 2H), 2.55 (s, 3H), 1.28-1.22 (m, 3H).
