To a stirred solution of diethyl [(6-bromo-2-[(E)-(hydroxyimino)methyl]quinolin-7-yl)(difluoro)methyl]phosphonate (520 mg, 1.189 mmol) in acetonitrile (30 mL) at room temperature were added triphenylphosphine (1.248 g, 4.76 mmol) and carbon tetrachloride (230 μL, 2.383 mmol). The reaction mixture was stirred at 100° C. for 1 hour. It was concentrated to dryness in vacuo, pre-adsorbed in silica gel for flash chromatography eluting with ethyl acetate in toluene (20% to 30%) to afford diethyl [(6-bromo-2-cyanoquinolin-7-yl)(difluoro)methyl]phosphonate.
