A mixture of ethyl 2,3-dihydro-9-iodo-1-benzoxepin-4-carboxylate (1.03 g), 2-formylbenzeneboronic acid (0.49 g), tetrakis(triphenylphosphine)palladium(0) (0.35 g), and triethylamine (0.92 ml) in N,N-dimethylformamide (10.3 ml) was stirred at 100° C. under nitrogen atomsphere for 2.5 hours and partitioned between ethyl acetate and water. The organic layer was washed successively with 1N hydrochloric acid, saturated aqueous sodium bicarbonate, and brine, dried over anhydrous magnesium sulfate, and evaporated in vacuo. The residue was purified by medium pressure liquid chromatography (silica gel) using a mixture of ethyl acetate and n-hexane (1:30˜1:9) to give a solid of ethyl 2,3-dihydro-9-(2-formylphenyl)-1-benzoxepin-4-carboxylate (0.63 g).
