Ammonia → 4-Bromo-5,6,7,8-tetrahydroisoquinolin-8-amine

Participants

Reaction Conditions

Reaction Steps

4-Bromo-6,7-dihydroisoquinolin-8(5H)-one (4.81 g, 21.3 mmol), titanium (IV) isopropoxide (12.5 mL, 42.6 mmol) and ammonia, 2.0 M solution in MeOH (53.2 mL, 106 mmol) were stirred at RT for 5 h. The reaction was cooled to 0° C. and NaBH4 (1.21 g, 31.9 mmol) was added portionwise over 10 min; the resulting mixture was stirred at RT for an additional 2 h. The reaction was quenched by pouring it into aq. ammonium hydroxide (25%), the precipitate was filtered and washed with EtOAc (3×, each time suspended in AcOEt and stirred for 5 min). The organic layer was separated and the remaining aqueous layer was extracted with EtOAc. The combined organic extracts were extracted with 1 M HCl. The acidic aqueous extracts were washed with ethyl acetate (1×), then treated with aqueous sodium hydroxide (2 M) to give pH 10-12, and extracted with EtOAc (3×). The combined second organic extracts were washed with brine, dried (Na2SO4), and concentrated in vacuo to afford the title compound (4.11 g, 85%) as brown solid. MS: 225 (M+, 1 Br).

Provenance & Evidence