To a solution of 6-[2-iodo-1-(3,4,5-trimethoxy-benyl)-vinyl]-2,2-dimethyl-2H-chromene (974 mg, 1.98 mmol) in 1,4-dioxane (9 mL) is added tri-n-butylethenyl-stannane (650 mg, 2.05 mmol), LiCl (252 mg, 594 mmol), Pd(PPh3)4 (46 mg, 0.04 mmol), and a few crystals of 2,6-di-tert-butyl-4-methyl phenol. The resulting suspension is heated to reflux for 4 hours, cooled to room temperature and treated with pyridine (1 mL) and pyridinium fluoride (2 mL, 1.4 M solution in THF, 2.8 mmol). The resulting mixture is stirred at room temperature for 16 hours and then diluted with diethyl ether and filtered through a small pad of diatomaceous earth (Celite®). The filtrate is washed with water, 10% HCl, water, brine, and dried over sodium sulfate, filtered, and concentrated. Crude material is used in the next step without further purification.
