A mixture solution of Intermediate 8 (4.70 g, 22.5 mmol), 4-methoxycarbonylphenylboronic acid (4.01 g, 22.5 mmol), K2CO3 (6.53 g, 47.2 mmol), Pd(dppf)Cl2 (470 mg, 0.407 mmol) in DMF (20 mL) and H2O (4 mL) was stirred under N2 atmosphere at 130° C. for 5 hours. The mixture was cooled, acidified with aqueous HCl (1M) until pH=6 and extracted with EtOAc (80 mL×3). The combined organic layers were washed with brine (150 mL), dried over anhydrous Na2SO4 and concentrated in vacuo. The residue was washed with EtOAc (50 mL), the mixture was filtered then concentrated to give the product (3.20 g, yield 46%) as an off-white solid.
