[Synthesis]
General procedure for the synthesis of 6-bromo-4-hydroxyisoquinoline from the compound (CAS: 1235382-79-2): 6-bromo-2-(phenylsulfonyl)-2,3-dihydroisoquinolin-4(1H)-one was first prepared from 4-bromobenzyl bromide with reference to the method reported in Tetrahedron 61 (2005) 8282 (29 g, 79.2 mmol ). The product was then suspended in ethanol (300 mL). To this suspension was added 21% sodium ethoxide/ethanol solution (88.6 mL, 238 mmol) and the reaction was stirred for 1 hour at room temperature. Upon completion of the reaction, 5 M hydrochloric acid (~50 mL) was added to the reaction solution for neutralization, followed by removal of ethanol by distillation under reduced pressure. The precipitated solid precipitate was collected by filtration. The resulting solid was dried and purified by silica gel column chromatography (eluent: dichloromethane/methanol, gradient from 100:0 to 50:50, v/v), resulting in the target product 6-bromo-4-hydroxyisoquinoline (13.2 g, 75% yield).1H-NMR (DMSO-d6) δ: 7.79 (1H, dd, J = 8.7, 1.8 Hz),. 8.03 (1H, d, J = 8.7 Hz), 8.11 (1H, s), 8.25-8.27 (1H, m), 8.82 (1H, s), 10.62 (1H, s). |