To a stirred solution of 1-ethyl-6,7-dimethoxyisoquinolin-3-ol SLA 28136 (200 mg, 0.86 mmol) in toluene (10 mL) in a 20 mL microwave vial equipped with a magnetic stirrer was added 3-(chloromethyl)-6-methoxy-N-methylquinolin-2-amine hydrochloride SLA 28154 (234 mg, 0.86 mmol) at RT followed by a 2 N aq. LiOH solution (0.86 mL, 1.72 mmol) and the mixture was stirred at 150° C. for 1.5 h under microwave irradiation. After cooling to RT, the mixture was diluted with a mixture CH2Cl2:MeOH=9:1 (150 mL), washed with brine (20 mL), dried over Na2SO4, filtered, and concentrated at 40° C. under vacuum. Purification by column chromatography (SiO2, eluent CH2Cl2:MeOH=100:0 to 92:8) provided 21 mg of 1-ethyl-6,7-dimethoxy-4-((6-methoxy-2-(methylamino)quinolin-3-yl)methyl)isoquinolin-3-ol as a brown solid. This free base was dissolved in CH2Cl2 (2 mL) in a 10 mL round-bottomed flask equipped with a magnetic stirrer before addition of a 0.49 M HCl solution in MeOH (0.40 mL). The reaction mixture was stirred for 5 min at RT then concentrated at 40° C. under vacuum to afford 1-ethyl-6,7-dimethoxy-4-((6-methoxy-2-(methylamino)quinolin-3-yl)methyl)isoquinolin-3-ol dihydrochloride 39 as a yellow solid (20.0 mg, 5% yield).
