1-Acetoxy-2-bromoethane → Ethyl 3-[(4-chlorophenyl)sulfonyl]-3-(2,5-difluorophenyl)propionate

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Reaction Steps

Under an argon atmosphere and at −78° C., n-butyl lithium (a 1.57M hexane solution, 7.01 ml) was added to a dimethoxyethane solution (50 ml) of the 2-[(4-chlorophenyl)sulfonylmethyl]-1,4-difluorobenzene (3.03 g, 10.0 mmol) obtained in Example 5. The temperature of the reaction mixture was raised to room temperature, at which stirring was conducted for 15 minutes. After cooling to −78° C., bromoethyl acetate (1.33 ml, 12.0 mmol) was added to the reaction mixture. The mixture was stirred at room temperature for 3 hours. To the reaction mixture was added a saturated ammonium chloride solution, followed by extraction with diethyl ether. The extracts were combined, washed successively with water, a saturated aqueous solution of sodium thiosulfate, and brine, dried over MgSO41 and then distilled under reduced pressure to remove the solvent. The residue thus obtained was recrystallized from hexane, whereby the title compound (1.95 g, 50%) was obtained as colorless needle crystals.

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