Di-tert-butyl dicarbonate (3.52 g, 16.14 mmol) was slowly added to a solution of 6-bromo-1,2,3,4-tetrahydroisoquinoline (3.26 g, 15.37 mmol) in tetrahydrofuran (45 mL) at room temperature. The reaction mixture was stirred continuously for 15 h at room temperature. After completion of the reaction, the solvent was removed by distillation under reduced pressure. The crude product was purified by silica gel column chromatography using solvent gradient elution (0→8% ethyl acetate/hexane) to afford the target compound tert-butyl 6-bromo-3,4-dihydroisoquinoline-2(1H)-carboxylate (5.05 g, 16.18 mmol, quantitative yield) as a colorless oil.1H NMR (300 MHz, CDCl3) δ: 1.49 (9H, s) ), 2.80 (2H, t, J = 5.9 Hz), 3.62 (2H, t, J = 5.9 Hz), 4.51 (2H, s), 6.97 (1H, d, J = 8.7 Hz), 7.28-7.32 (2H, m).
