General procedure for the synthesis of 1,2,3,4-tetrahydroisoquinolin-6-ol hydrobromide from 6-methoxy-1,2,3,4-tetrahydroisoquinoline: 6-methoxy-1,2,3,4-tetrahydroisoquinoline (2.12 g, 13.0 mmol) was dissolved in 48% aqueous hydrobromic acid. The reaction mixture was stirred at 120°C for 3 hours. After completion of the reaction, the solvent was removed by vacuum concentration. The obtained residue was suspended in ethyl acetate and the solvent was evaporated again to afford 1,2,3,4-tetrahydroisoquinolin-6-ol hydrobromide (2.99 g, 95% yield) as a reddish brown solid. The product was characterized by 1H NMR (300 MHz, D2O): δ 7.10 (d, J = 8.4 Hz, 1H), 6.82-6.75 (m, 2H), 4.28 (s, 2H), 3.48 (t, J = 6.3 Hz, 2H), 3.05 (t, J = 6.3 Hz, 2H).
