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

Participants

Reaction Steps

To a solution of the dihydrobenzazepine (2.43 g, 7.31 mmol) from step F above in pyridine (50 mL) were added potassium carbonate (8.08 g, 58.5 mmol) and p-toluenesulfonylhydrazide (5.45 g, 29.3 mmol) in batches. The reaction solution was heated under reflux for 48 h 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 to 5% methanol/dichloromethane) to give the desired 8-bromotetrahydrobenzazepine (1.74 g, 71%): 1H NMR (500 MHz, CDCl3) δ 7.31 (d, J=2.1 Hz, 1H), 7.20-7.16 (m, 1H), 7.13-7.10 (m, 2H), 7.04 (t, J=8.6 Hz, 2H), 6.49 (br, 1H), 4.24 (d, J=9.3 Hz, 1H), 3.88 (d, J=12.2 Hz, 1H), 3.67 (d, J=14.3 Hz, 1H), 3.12-3.09 (m, 1H), 2.98-2.93 (m, 1H), 2.34 (s, 3H), 2.30-2.23 (m, 1H), 2.08-2.04 (m, 1H); ESI MS m/z 334, 336 [M+H]+.

Provenance & Evidence