Hydrogen Bromide → 1,2,3,4-Tetrahydroisoquinolin-6-ol hydrobromide

A solution of 8.00 g (49 mmol) of 6-Methoxy-1,2,3,4-tetrahydro-isoquinoline in 196 mL of 48% hydrobromic acid was refluxed for 3 h. The mixture was then concentrated and coevaporated several times with ethanol. The resulting slurry was filtered and dried under vacuum to give 7.43 g of 1,2,3,4-Tetrahydro-isoquinolin-6-ol hydrobromide as a solid. To 7.38 g of the crude hydrobromide dissolved in 117 mL each of dioxane and water was added 6.34 g (35.3 mmol) of benzyl chloroformate with ice bath cooling. A 1 M solution of potassium carbonate was slowly added until a pH of 10 was maintained. The mixture was stirred overnight at room temperature. Excess dioxane was removed by evaporation, and the resulting aqueous mixture was acidified with 1 N HCl and the product extracted with ethyl acetate. The organic portion was washed with water and brine, dried over Na2SO4 and concentrated to give 10.4 g of an oil which was crystallized from ether/hexane to give 7.05 g of 7D as a solid.