Reaction Steps
A solution of 75 (171 mg, 0.238 mmol) and TFA (2 mL) in DCM (10 mL) was stirred at RT for 2 h. The TFA was removed by co-evaporation with DCM, diluted with a minimum of water, and the pH was adjusted to around 10 with a saturated aqueous solution of sodium bicarbonate and a few drops of 1N NaOH at the end. The resultant suspension was sonicated for 15 min. The solid was collected by filtration, rinsed with water and dried under high vacuum. The crude product was purified by Biotage (SiliaFlash 12 g cartridge; 2% of ammonium hydroxide in MeOH/DCM: 5/95 to 15/85 over 20 CV, then 15/85 to 20/80 over 10 CV), to afford the title compound 76 (110 mg, 0.178 mmol, 74% yield) as a white sticky solid. 1H NMR (400 MHz, DMSO-d6) δ (ppm): 8.75 (s, 1H), 8.57 (d, J=1.6 Hz, 1H), 8.52 (d, J=5.3 Hz, 1H), 8.34 (s, 1H), 8.25 (d, J=8.2 Hz, 1H), 7.88 (dd, J=8.1, 2.1 Hz, 1H), 7.73 (dd, J=13.5, 2.5 Hz, 1H), 7.38 (t, J=9.0 Hz, 1H), 7.21 (bd, J=8.8 Hz, 1H), 6.65 (d, J=5.3 Hz, 1H), 6.61 (bd, J=2.5 Hz, 1H), 3.59 (s, 2H), 3.54-3.42 (m, 5H), 2.59-2.51 (m, 1H), 2.48-2.28 (m, 4H), 2.20-1.80 (m, 2H), 1.74-1.62 (m, 1H), 0.87 (d, J=6.8 Hz, 3H), 0.78 (d, J=6.7 Hz, 3H), 0.73-0.58 (m, 2H), 0.50-0.36 (m, 2H). MS (m/z): 519.6 and 618.7 (M+H).
