Boron tribromide → 1-(2,6-Dichlorophenyl)-5-(2,4-difluorophenyl)-3,4-dihydro-7-hydroxy-2(1H)-quinolinone

To a solution of 18 mg of 1-(2,6-dichlorophenyl)-5-(2,4-difluorophenyl)-3,4-dihydro-7-methoxy-2(1H)-quinolinone (INTERMEDIATE 2) in 1 mL of CH2Cl2 was added 0.1 mL of BBr3. The resulting mixture was stirred 30 min at 0° C., then warmed to room temperature and stirred at this temperature for 1 h. The mixture was concentrated and the resulting residue was purified preparative thin layer chromatography, eluting with 98:2 CH2Cl2-MeOH, to yield 1-(2,6-Dichlorophenyl)-5-(2,4-difluorophenyl)-3,4-dihydro-7-hydroxy-2(1H)-quinolinone. Mass spectrum (ESI) 421.0 (M+1). 1H NMR (500 MHz, CDCl3): δ 7.47 (d, J=8.0 Hz, 2H); 7.33 (t, J=8.0 Hz, 1H); 7.27 (m, 1H); 6.95, (m, 2H); 5.82 (s, 1H); 5.23 (s, 1H); 2.56-3.00 (m, 5H).