Trifluoromethanesulfonic acid → (6-Bromo-4-hydroxy-2-oxo-1,2-dihydroquinolin-3-yl)(phenyl) iodoniumtrifluoromethane sulfonate

To a suspension of 6-bromo-4-hydroxyquinolin-2(1H)-one (11.0 g, 45.8 mmol, Intermediate 8, step a) and (diacetoxyiodo)benzene (13.4 g, 41.7 mmol) in dichloromethane (180 mL) at 0° C. was added trifluoromethanesulfonic acid (4.06 mL, 45.8 mmol) dropwise. The resulting mixture was stirred in an ice-water bath for 1 hour and at room temperature for 2 hours to receive a suspension which was filtered. The solid product was washed with dichloromethane and dried under vacuum at 50° C. for 12 hours to yield the title compound.