[(8-Bromo-6-chloro-4-hydroxy-2-oxo-2H-thiochromene-3-carbonyl)-amino]-acetic acid ethyl ester (22(d)) (500 mg, 1.2 mmol) was dissolved in anhydrous DMF (5 mL). To the solution was added Tributyl-phenyl-stannane (467 uL, 1.43 mmol), bis(triphenylphosphino) palladium(II) dichloride (100 mg, 0.12 mmol) and 4A molecular sieves. The reaction was sealed and the solution was heated to 120 C for 45 minutes. The reaction was cooled, diluted with ethyl acetate (25 mL) and water (25 mL). The organic phase was separated, dried over magnesium sulfate and concentrated residue in vacuo. The residue was filtered through silica to provide the title compound (418 mg) which was used directly without further purification.
