Reaction Steps
A mixture of the product obtained from Step A (200 mg, 0.51 mmol), Me2NH (40% aq solution, 4 mL, 35 mmol) and DMF (10 mL) was placed in a sealed tube. The tube was then heated at 110° C. for 14 h. After cooled to room temperature, the reaction was diluted with dichloromethane (50 mL) and washed with water, brine, dried and concentrated. The residue was purified by a medium pressure chromatography (eluent: MeOH/EtOAc 1:9) to give [6-(4-benzo[b]thiophen-5-yl-2-methyl-1,2,3,4-tetrahydroisoquinolin-7-yl)-pyridazin-3-yl]-dimethylamine (200 mg, 98%) as a yellow semi-solid. The compound was dissolved in methanol (2 mL), and to this solution was added fumaric acid (60 mg, 0.52 mmol). To this solution was added water (15 mL). The resulting suspension was lyophilized on a freeze dryer overnight to give (+)-[6-(4-benzo[b]thiophen-5-yl-2-methyl-1,2,3,4-tetrahydroisoquinolin-7-yl)-pyridazin-3-yl]-dimethylamine, fumarate salt (230 mg, 88%, 98.0% AUC HPLC) as an off-white solid: [α]25D+32.5° (c 0.08, methanol); mp 116-119° C.; 1H NMR (500 MHz, CD3OD) δ 7.92 (d, J=8.3 Hz, 1H), 7.87 (bs, 1H), 7.81 (d, J=10.0 Hz, 1H), 7.77 (bs, 1H), 7.75 (d, J=8.3 Hz, 1H), 7.61 (d, J=5.4, 1H), 7.35 (d, J=5.4 Hz, 1H), 7.22 (d, J=8.3 Hz, 1H), 7.19 (d, J=9.6 Hz, 1H), 7.04 (d, J=8.3 Hz, 1H), 6.71 (s, 4H), 4.73-4.67 (m, 1H), 4.60-4.49 (m, 2H), 3.81-3.77 (m, 1H), 3.50-3.43 (m, 1H), 3.21 (s, 6H), 2.99 (s, 3H); ESI-MS m/z 401 [M+H]+; Anal Calcd. For C22H24N4S.2.0C4H4O4.0.25H2O: C, 60.32; H, 5.14; N, 8.79. Found: C, 60.03; H, 4.94; N, 8.87.
