Trifluoroacetic acid → 8-chloro-7-(difluoromethoxy)-2-[(4,6-dimethyl-2-oxo-1,2-dihydropyridin-3-yl)methyl]-3,4-dihydroisoquinolin-1(2H)-one

To a solution of 2-{[2-(benzyloxy)-4,6-dimethylpyridin-3-yl]methyl}-8-chloro-7-(difluoromethoxy)-3,4-dihydroisoquinolin-1(2H)-one (1i, 0.08 g, 0.169 mmol) in CH2Cl2 (10 mL) was added TFA (10 mL) at room temperature. The resulting mixture was stirred at room temperature for 4 hours. The mixture was concentrated under vacuum to give a residue, which was dissolved in CH2Cl2 (20 mL) and then washed with sat. NaHCO3 (5 mL), brine (5 mL), dried over Na2SO4, and concentrated under vacuum. The residue was purified by prep. TLC (EtOAc) to obtain the title compound (Example 1, 43.1 mg, 67%) as a white solid. 1H NMR (400 MHz, methanol-d4) δ 7.36-7.34 (m, 1H), 7.24-7.22 (m, 1H), 7.00-6.63 (m, 1H), 6.11 (s, 1H), 4.76 (s, 2H), 3.51-3.48 (m, 2H), 2.90-2.87 (m, 2H), 2.29 (s, 3H), 2.25 (s, 3H); MS 382.9 [M+1].