1,2-Dibromoethane → Methyl 2-chloro-3-(1-cyanocyclopropyl)benzoate

A solution of methyl 2-chloro-3-(cyanomethyl)benzoate (20.0 g, 95.3 mmol) in dimethylsulfoxide (200 mL) was cooled to 15° C., 60% sodium hydride (11.6 g, 289 mmol) was added by small portions, and the mixture was stirred at room temperature for 30 min. To the suspension was dropwise added 1,2-dibromoethane (16.5 mL, 191 mmol) at 15° C. over 10 min, and the mixture was stirred at room temperature for 4 hr. To the reaction mixture was added aqueous ammonium chloride solution (200 mL), and the mixture was extracted with diethyl ether/ethyl acetate (1:1, 3×200 mL). The combined organic layer was washed successively with water (200 mL) and saturated brine (100 mL), and dried over anhydrous magnesium sulfate. The insoluble material was filtered off, and the filtrate was concentrated under reduced pressure. The obtained residue was purified by silica gel column chromatography (hexane/ethyl acetate=95/5→65/35) to give the title compound (13.5 g, 60%) as a white powder.