反应详情

To a solution of 2,2-difluoropropanoic acid (330 mg, 2.97 mmol) in DCM (5 mL) was added P2O5 (3.3 g, 29.7 mmol) at room temperature and the mixture was stirred for 2 days to give 2,2-difluoropropanoic anhydride. To a suspension of Intermediate A-2a (170 mg, 0.59 mmol) in TEA (5 mL) was added dropwise the 2,2-difluoropropanoic anhydride in DCM at 0˜10° C. The mixture was stirred at room temperature for 2 h. The volatiles were evaporated and the residue was purified by prep-TLC (PE:EA=1:1) to afford methyl 4-(2-(1,1-difluoroethyl)-7-hydroxy-4-oxo-4H-chromen-3-yl)benzoate as brown oil (45 mg, 21%).