To a mixed solution of 7-bromo-1,2,3,4-tetrahydroisoquinoline (1 g, 4.71 mmol) and sodium carbonate (1 g, 9.4 mmol) in tetrahydrofuran/water (16 mL/6 mL) was added di-tert-butyl dicarbonate (1.51 mL, 7.06 mmol). The reaction mixture was stirred at room temperature overnight. After the reaction was completed, the reaction mixture was diluted with water (50 mL) and extracted with ethyl acetate (50 mL x 3). The organic phases were combined, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure to afford tert-butyl 7-bromo-3,4-dihydroisoquinoline-2(1H)-carboxylate as a colorless oil (1.46 g, 100% yield).
