Pyridine → 8-Bromo-2,3,4,5-tetrahydro-1H-benzo[b]azepine

Participants

Reaction Steps

To a solution of the dihydrobenzazepine (270 mg, 0.70 mmol) from step F above in pyridine (15 mL) were added potassium carbonate (967 mg, 7.0 mmol) and p-toluenesulfonylhydrazide (672 mg, 3.5 mmol) in batches. The reaction solution was heated under reflux for 24 hours and then cooled to room temperature. The resultant reaction mixture was filtered through Celite. The Celite bed was washed with ethyl acetate. The filtrate was concentrated under reduced pressure. The residue dissolved in ethyl acetate was washed with water and brine, dried over sodium sulfate and concentrated under reduced pressure. The residue obtained was purified by flash column chromatography (3% methanol/dichloromethane) to give the desired 8-bromotetrahydrobenzazepine (176 mg, 65%): 1H NMR (500 MHz, CDCl3) δ 7.28 (d, J=2.1 Hz, 1H), 7.19 (dd, J=8.2, 1.7 Hz, 1H), 6.64 (d, J=8.2 Hz, 2H), 6.60-6.56 (m, 2H), 4.31 (t, J=4.4 Hz, 2H), 4.12 (d, J=9.9 Hz, 1H), 3.83 (br, 1H), 3.69 (d, J=14.2 Hz, 1H), 3.26 (t, J=4.4 Hz, 2H), 3.13-3.10 (m, 1H), 2.95-2.90 (m, 1H), 2.89 (s, 3H), 2.32 (s, 3H), 2.24-2.17 (m, 1H), 2.06-2.04 (m, 1H); ESI MS m/z 387, 389 [M+H]+.

Provenance & Evidence