Reaction Steps
A stream of O3 generated from an ozonator was passed though the solution of Intermediate 238 (200 mg, 0.43 mmol, 1.0 equiv.) in MeOH (30 mL) at −78° C. until the color of the reaction solution became blue (˜10 min). NaBH4 (49 mg, 1.3 mmol, 3.0 equiv.) was added at −78° C. The reaction solution was warmed to room temperature and partitioned between EtOAc and brine. The organic layer was separated, dried over Na2SO4 and concentrated. The crude product was purified by column chromatography with EtOAc/hexanes as eluents to afford the title compound (140 mg, 0.30 mmol, 70% yield) as a white solid. 1H NMR (500 MHz, CDCl3) δ 8.95-8.88 (d, J=4.9 Hz, 2H), 7.81-7.73 (dd, J=7.8, 1.7 Hz, 1H), 7.67-7.58 (dd, J=7.7, 1.6 Hz, 1H), 7.50-7.44 (t, J=4.9 Hz, 1H), 7.43-7.36 (t, J=7.8 Hz, 1H), 6.95-6.83 (d, J=8.1 Hz, 1H), 5.62-5.44 (m, 1H), 4.06-3.89 (m, 2H), 3.66-3.56 (ddd, J=14.7, 6.1, 4.6 Hz, 1H), 3.44-3.34 (ddd, J=14.7, 7.7, 4.9 Hz, 1H), 3.20-3.14 (t, J=5.9 Hz, 1H), 1.88-1.71 (d, J=7.0 Hz, 3H). 13C NMR (151 MHz, CDCl3) δ 165.5, 159.0, 155.5, 147.4, 138.3, 133.1, 132.2, 129.2, 129.1 (q, JC—F=31.5 Hz), 128.5 (q, JC—F=5.2 Hz), 126.8, 122.5 (q, JC—F=273.4 Hz), 120.7, 61.1, 41.4, 27.3, 20.7. HRMS-ESI (m/z): [M+H]+ calcd for C18H17ClF3N6O2, 441.1048. found, 441.1038.
