To a solution of 4-oxochroman-7-yl trifluoromethanesulfonate (Preparation 2C, 2.00 g, 6.75 mmol) in dioxane (10 mL) in a sealed tube was added sequentially tributyl(vinyl) stannane (2.18 mL, 7.43 mmol) and lithium chloride (0.859 g, 20.3 mmol). The mixture was degassed under reduced pressure and charged with nitrogen (2×). To the mixture was added tetrakis(triphenylphosphine) palladium(0) (0.780 g, 0.675 mmol), and the mixture was stirred under a strong stream of nitrogen for 5 min. The reaction mixture was sealed, immersed in an oil bath at 100° C., and stirred overnight. The reaction mixture was cooled to room temperature and filtered under reduced pressure. The solid was washed with ethyl acetate (4×50 mL), and the filtrate was concentrated. The crude product mixture was diluted with ether (˜100 mL), sonicated for several minutes, and filtered (the cake was rinsed with ether). The filtrate was concentrated under reduced pressure, and the residue was purified by flash silica gel chromatography using a mixture of ethyl acetate in hexane (5%-12%-15%) to give 7-vinylchroman-4-one (0.938 g, 5.38 mmol, 80% yield) as a yellow oil. The product had a HPLC ret. time=1.93 min. (condition A); LC/MS M+1=174.9; 1H NMR (400 MHz, CDCl3) δ ppm 2.78-2.85 (m, 2H), 4.52-4.58 (m, 2H), 5.42 (d, J=10.78 Hz, 1H), 5.88 (d, J=17.61 Hz, 1H), 6.69 (dd, J=17.61, 11.00 Hz, 1H), 6.98 (d, J=1.54 Hz, 1H), 7.09 (dd, J=8.25, 1.43 Hz, 1H), and 7.87 (d, J=8.14 Hz, 1H).
