A solution of N-(4-chlorobenzyl)-1-([(4-chlorophenyl)sulfanyl]methyl)-6-(4-morpholinylmethyl)-4-oxo-1,4-dihydro-3-quinolinecarboxamide (0.11 gm) from Example No. 101 in dichloromethane (2 mL) at 0° C. is treated with p-toluenesulfonic acid hydrate (0.04 gm) followed by m-chloroperoxybenzoic acid (˜85%) (0.09 gm). The mixture is stirred for 0.75 hr. The reaction mixture is diluted with dichloromethane, washed with saturated aqueous sodium sulfite, saturated aqueous sodium bicarbonate, brine, dried (Na2SO4) and concentrated under reduced pressure. The crude product is purified by recrystallization from acetonitrile to afford 0.09 gm of the title compound as a white solid.
