Lithium Chloride → 7-bromo-4-(1-ethoxyvinyl)-2H-chromen-2-one

Participants

Reaction Conditions

Reaction Steps

To a solution of 7-bromo-2-oxo-2H-chromen-4-yl trifluoromethanesulfonate (prepared as described in U.S. Pat. No. 5,552,437) (5 g, 13.4 mmol) and tributyl(1-ethoxyvinyl)tin (4.75 mL, 14.1 mmol) in 1,4-dioxane (50 mL), lithium chloride (1.7 g, 40.2 mmol) was added. The reaction flask was then purged twice with nitrogen and tetrakis(triphenylphosphine) palladium(0) (774 mg, 0.7 mmol) was added. The reaction was then heated 4 hours at 80° 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 (hexanes/CH2Cl2/acetone, 25:75:0 to 0:95:5) to afford the title compound. 1H NMR (400 MHz, acetone-d6): 7.83 (d, 1H), 7.60 (s, 1H), 7.52 (d, 1H), 6.46 (s, 1H), 4.67 (s, 2H), 4.05 (q, 2H), 1.38 (t, 3H).

Provenance & Evidence