Under argon atmosphere, a solution of ethyl 7-bromo-2,3-dihydro-1-benzoxepine-4-carboxylate (1.0 g), 4-methylthiophenyl borate (622 mg) and potassium carbonate (0.93 g) in toluene-ethanol-water (30-3-3 ml) was stirred at room temperature for 1 hour. To the reaction mixture was added tetrakistriphenyl-phosphinepalladium (117 mg), and the mixture was refluxed for 16 hours. To the reaction mixture was added tetrakistriphenyl-phosphinepalladium (0.13 g), and the mixture was refluxed for 24 hours and cooled to room temperature. The organic layer was washed with saturated sodium chloride solution, dried with magnesium sulfate and concentrated under reduced pressure. The residue was separated and purified with column chromatography (ethyl acetate/hexane=1:10) to give ethyl 7-(4-methylthiophenyl)-2,3-dihydro-1-benzoxepine-4-carboxylate (442 mg) as colorless crystals.
