Ethanol → 4-[5-(2-Amino-ethanesulfonyl)-isoquinolin-7-yl]-phenol

To {2-[7-(4-methoxy-phenyl)-isoquinoline-5-sulfonyl]-ethyl}-carbamic acid tert-butyl ester (25.00 g, 56.49 mmol) in dichloromethane (1 L) at 0° C. add BBr3 (1.0 M in dichloromethane, 200 mL, 200 mmol) over 40 min with vigorous overhead stirring. Remove the cooling bath and stir at room temperature overnight. Cool to 0° C. and add methanol (500 mL) dropwise over 1 h. Filter the resulting slurry, rinse the flask with dichloromethane (100 mL) and wash the solids with the rinse. Wash the solids with additional dichloromethane (150 mL) and dry under vacuum filtration. Slurry the solids in methanol (400 mL) with stirring, then concentrate under vacuum to a thin paste. Add additional methanol (400 mL) and further slurry the solids with stirring. Concentrate the slurry under vacuum to dryness, and dry the solids overnight under vacuum. Pulverize the solids to a powder and slurry in methanol (1 L). Add Amberlyst® A-21 resin (75 g) and stir until the powder is dissolved. Filter the resin, slurry the filtered resin in methanol (220 mL) and filter the resin again, combining the filtrates. Wash the filtered resin with methanol (100 mL) and add this wash to the filtrates. Combine the filtrates with ethanol (200 mL) and concentrate the mixture under vacuum to a volume of about 200 mL to afford a slurry. Add ethanol (400 mL), warm the slurry to 50° C. for about 15 min, then concentrate under vacuum to a volume of about 200 mL. Cool the slurry to room temperature, filter and rinse the filter cake with ethanol (2×15 mL), then dry under vacuum to afford the title compound (10.22 g, 55%) as a tan solid. Mass spectrum (LCMS) m/z=329.0 (M+H+).