Step 1: Sodium metal (120 mg, 5.1 mmol) was slowly added to methanol (2.5 mL, 62 mmol) at -5 °C. Subsequently, a solution of dimethyl oxalate (500 mg, 4.2 mmol) and 2-bromoacetophenone (840 mg, 4.2 mmol) in ether (5 mL) was added to this solution. The reaction mixture was stirred at room temperature for 12 hours and then concentrated. The concentrate was partitioned between ether and water, the aqueous layer was separated and cooled in an ice bath. Acetic acid and 1N hydrochloric acid were added sequentially to the cooled aqueous layer until the solution became acidic. The mixture was extracted with ether, the organic layers were combined and dried over anhydrous sodium sulfate. After filtration, the organic layer was concentrated to give methyl 4-(2-bromophenyl)-2,4-dioxobutanoate (1.08 g, 89% yield), which could be used in the next reaction without further purification.LCMS(FA)ES+ m/z: 287.0 [M+H]+.
