A toluene solution (9 mL) of compound 99 (1.0 g, 2.89 mmol), Pd(dba)2 (70 mg, 0.12 mmol) and PPh3 (30 mg, 0.12 mmol) was stirred at room temperature under argon for 15 min. Then, (1-ethoxyvinyl)tri(n-butyl)stannane (1.08 mL, 3.18 mmol) in toluene (6 mL) was added and the resulting mixture was stirred overnight at 110° C., cooled to room temperature and filtered on Celite, washed with EtOAc and concentrated under reduced pressure. Purification on silica gel (Petroleum ether 100% to EtOAc 100%) afford the product which was placed in presence of an aqueous solution of HCl 1M for 30 minutes at room temperature. After neutralization with a saturated aqueous solution of NaHCO3, aqueous phase was extracted with dichloromethane and the combined organic layers were dried over magnesium sulfate to afford the title compound 103 (Yield 475 mg, 96%) which was used without further purification.
