To a DMF solution (2.5 ml) of N-(3-bromo-phenyl)-N-methyl-acetamide (114 mg) obtained in Step B, palladium acetate (1.1 mg), S-Phos (4.1 mg) and potassium phosphate (212.3 mg), 1-ethylpiperazine (76.2 μl) was added, and then the mixture was degassed under ultrasonic irradiation. This was stirred at 100° C. for 5 hours, followed by addition of water (10 ml), which was extracted with ethyl acetate (10 ml×2), and the organic layer was dried over sodium sulfate. After the sodium sulfate was filtered off, the solvent was distilled off under reduced pressure, followed by purification by silica gel column chromatography (dichloromethane/methanol=20/1 to 10/1), to obtain the desired compound (104.9 mg, 80%).
