To a solution of 7-methyl-2-oxo-2H-chromen-4-yl trifluoromethanesulfonate (prepared as described in U.S. Pat. No. 5,552,437) (2.5 g, 8.1 mmol) and tributyl(1-ethoxyvinyl)tin (2.88 mL, 8.5 mmol) in 1,4-dioxane (25 mL), lithium chloride (1.03 g, 24.3 mmol) was added. The reaction flask was then purged twice with nitrogen and tetrakis(triphenylphosphine) palladium(0) (468 mg, 0.405 mmol) was added. The reaction was then heated overnight at 100° C. After cooling, the reaction mixture was concentrated under reduced pressure and the crude residue obtained was diluted with ethyl acetate, washed with a saturated ammonium chloride aq. solution, water and brine, dried over MgSO4, filtered and concentrated. The crude residue obtained was purified by column chromatography (EtOAc/hexanes, 25:75 to 40:60) to afford the title compound. 1H NMR (400 MHz, acetone-d6): 7.76 (d, 1H), 7.22 (s, 1H), 7.19 (d, 1H), 6.35 (s, 1H), 4.64 (d, 1H), 4.61 (d, 1H), 4.04 (q, 2H), 2.47 (s, 3H), 1.40 (t, 3H).
