To a mixture of 6-bromo-1,2,3,4-tetrahydroisoquinoline and 8-bromo-1,2,3,4-tetrahydroisoquinoline (22.1 mmol) in THF (100 mL) was added DIPEA (22.1 mmol) and BOC2O (24 mmol). The reaction mixture was allowed to stir at rt over the weekend and then concentrated. Water (5 mL) was added to the residue and the pH was adjusted to 2 by the addition of 1N H3PO4. The mixture was extracted with EtOAc. The organic solutions were combined, dried over Na2SO4, filtered and concentrated. The residue was purified by column chromatography to give tert-butyl 6-bromo-3,4-dihydroisoquinoline-2(1H)-carboxylate and tert-butyl 8-bromo-3,4-dihydroisoquinoline-2(1H)-carboxylate (6.04 g, 88%) as a yellow oil.
