Intermediate 1 (500 mg), phenylboronic acid (300 mg), tetrakis(triphenylphosphine)palladium (0) (150 mg) are dissolved in tetrahydrofuran (20 ml), and thereto are added cesium carbonate (850 mg) and water (10 ml). The mixture is heated under reflux for 18 hours under argon atmosphere. The reaction solution is extracted with ethyl acetate, and the organic layer is dried over sodium sulfate, and the solvent is evaporated under reduced pressure. The residue is purified by silica gel column chromatography (eluent: gradient from 0% to 100% hexane/ethyl acetate) to give the desired compound (360 mg).
