Method A: In a two-necked round-bottomed flask equipped with a reflux condenser and a magnetic stirring bar, 2-bromobenzoic acid (20 mmol) and freshly distilled methanol (25 mL) were added. The mixture was heated in a hot water bath and concentrated. Sulfuric acid (8 mmol) was slowly added, followed by refluxing the reaction mixture for 24 hours. After completion of the reaction, it was cooled to room temperature and about half the volume of solvent was removed under reduced pressure. The residue was partitioned between water (50 mL) and ether (70 mL). The organic layer was separated and washed sequentially with saturated sodium bicarbonate solution (2 x 50 mL), water (50 mL) and brine (50 mL), dried over anhydrous magnesium sulfate, and the volatiles were removed under reduced pressure. The resulting crude product was purified by silica gel fast column chromatography to give alkyl 2-halobenzoate.
(0023) Alkyl 2-halobenzoate (22.5 mmol) was dissolved in freshly distilled anhydrous tetrahydrofuran (30 mL) under argon protection in a two-necked, round-bottomed flask fitted with a reflux condenser and a magnetic stir bar. The solution was cooled to 0 °C using an ice bath and sodium hydride (60% dispersed in mineral oil, 15 mmol) was added in batches. After stirring for 15 min, anhydrous tetrahydrofuran (30 mL) solution of alkyl acetate (15 mmol) was added slowly and dropwise at 0 °C. The reaction mixture was gradually warmed to room temperature with stirring for 2 hours, followed by heating and refluxing for 24 hours. Upon completion of the reaction, it was cooled to room temperature, about half the volume of solvent was removed under reduced pressure and the reaction mixture was diluted with toluene (50 mL). The resulting solution was washed sequentially with 2N hydrochloric acid (50 mL), saturated ammonium chloride solution (50 mL), dried over anhydrous magnesium sulfate, and the volatiles were removed under reduced pressure. The crude product was purified by silica gel fast column chromatography to afford alkyl 3-(2'-halogenated phenyl)-3-oxopropanoate 1.
