Reaction Steps
Free base 8l was added to methanesulfonic acid at 0° C. and the resulting mixture was allowed to warm to room temperature and stir for 2 h. The reaction mixture was then poured into cold MeOH (between −10° C. and 0° C.) and the precipitated solid was filtered, washed with MeOH (100 mL) and dried in vacuo. The dried solid was then dissolved in water (˜200 mL) and lyophilized to provide the methanesulfonate monohydrate salt 8l. (1.020 g, 84%). 1H NMR (DMSO-D6): δ 1.75-1.85 (m, 2H), 2.35 (s, 3H), 2.78-2.84 (m, 2H), 2.96-3.12 (m, 4H), 3.36 (d, J=12.3 Hz, 2H), 3.61 (t, J=11.4 Hz, 2H), 3.94 (d, J=12.9 Hz, 2H), 4.03 (s, 2H), 7.49-7.55 (m, 1H), 7.76-7.84 (m, 3H), 7.99 (d, J=0.9 Hz, 1H), 8.15 (d, J=8.4 Hz, 1H), 8.25 (d, J=8.4 Hz, 1H), 9.59 (s, 1H), 12.42 (s, 1H); 13C NMR (DMSO-D6): δ 24.27, 33.86, 51.89, 54.51, 64.02, 119.70, 120.39, 123.53, 126.09, 126.45, 128.63, 133.66, 135.80, 138.71, 141.21, 144.57, 163.29; Anal. Calcd for C24H31N3O8S2: C, 52.06; H, 5.46; N, 7.59, Karl-Fisher, 3.36. Found: C, 51.85; H, 5.35, N, 7.30, Karl-Fisher, 4.32. Similarly, HCl, H2SO4, CH3COOH, and succinic acid salts of 8l were prepared by substituting methanesulfonic acid with HCl, H2SO4 and CH3COOH, respectively
