To a solution of 350 (600 mg, 0.879 mmol) in DCM (15 ml) was added HCl in dioxane (2 ml, 7.17 eq, 8 mmol, 4M in dioxane) and the reaction mixture was stirred at RT for 3 hours. The mixture wad diluted with water and solid NaHCO3 was added. The reaction mixture was extracted with EtOAc then the organic phase was collected, dried over Na2SO4, filtered and concentrated. Trituration of the residue with EtOAc afforded the desired compound 351 as an off-white solid (314 mg, 61% yield). 1H NMR (do-DMSO): 10.90 (s, 1H), 8.89 (s, 1H), 8.50 (d, J=5.48 Hz, 1H), 7.98 (m, 1H), 7.95 (s, 1H), 7.72 (m, 1H), 7.41 (m, 1H), 7.28-7.20 (m, 3H), 7.04 (m, 1H), 6.68 (d, J=5.28 Hz, 1H), 4.28 (s, 2H), 3.92 (s, 3H), 3.61 (m, 2H), 3.27 (s, 3H), 3.13 (m, 2H).
