To a solvent mixture of methanol (20 mL) and saturated aqueous sodium carbonate (20 mL) was added 1-(6-bromo-3,4-dihydroisoquinolin-2(1H)-yl)-2,2,2-trifluoroacetophenone mixed with 1-(8-bromo-3,4-dihydroisoquinolin-2(1H)-yl)-2,2,2-trifluoroethanone (3 g, 9.7 mmol). The reaction mixture was heated to reflux overnight and subsequently concentrated. The residue was extracted with dichloromethane, the organic layers were combined, washed sequentially with water and saturated sodium chloride solution, dried over anhydrous sodium sulfate and the solvent was evaporated under reduced pressure. The crude product was purified by silica gel column chromatography (230-400 mesh) with 0-2% methanol/chloroform solution as eluent to give 8-bromo-1,2,3,4-tetrahydroisoquinoline (first fraction, colorless viscous oil, 0.45 g, 22% yield) and 6-bromo-1,2,3,4-tetrahydroisoquinoline (second fraction, white solid, 1.0 g, 48% yield) sequentially. Mass spectrum (MS) m/z: 211.9 [M + H]+.
