Sulfuric Acid → (R)-isobutyl 1-(2-(2-hydroxyphenyl)-7-methylquinazolin-4-yl)pyrrolidin-3-ylcarbamate sulfate

A 0.5 M solution of H2SO4 in acetonitrile (2.38 mL) was added to a solution of ((R)-isobutyl 1-(2-(2-hydroxyphenyl)-7-methylquinazolin-4-yl)pyrrolidin-3-ylcarbamate (0.5 g, 1.19 mmol) in dry THF (2.0 mL), and the reaction was stirred at RT for 2 h. The formed gelatinous white slurry was filtered, washed with THF, and dried under vacuum to give (R)-isobutyl 1-(2-(2-hydroxyphenyl)-7-methylquinazolin-4-yl)pyrrolidin-3-ylcarbamate sulfate as a yellow solid. 1H NMR (400 MHz, DMSO-d6) δ 8.29 (d, J=8.2 Hz, 1H), 8.15 (d, J=7.1 Hz, 1H), 7.76 (s, 1H), 7.61 (s, 1H), 7.55-7.51 (m, 2H), 7.12-7.04 (m, 2H), 4.40-4.02 (m, 4H), 3.98 (d, J=9.0 Hz, 1H), 3.84-3.75 (m, 2H), 2.54 (s, 3H), 2.27-2.22 (m, 1H), 2.10-2.08 (m, 1H), 1.98-1.79 (m, 1H), 0.88 (d, J=6.4 Hz, 6H) ppm. LC/MS: m/z 421.1 (M+H)+ at 2.71 min (10%-99% CH3CN (0.035% TFA)/H2O (0.05% TFA)).