Citric Acid → tert-butyl 6-[2-(benzoylamino)ethyl]-1,4,5,6-tetrahydroazepino[4,5-b]indole-3(2H)-carboxylate

Participants

Reaction Steps

tert-Butyl 6-(2-aminoethyl)-1,4,5,6-tetrahydroazepino[4,5-b]indole-3(2H)-carboxylate (0.0401 g, 0.122 mmol) was dissolved in THF (2 mL) at rt under N2. Diisopropylethylamine (0.028 mL, 0.0205 g, 0.158 mmol, 1.30 equiv.) and benzoyl chloride (0.017 mL, 0.0205 g, 0.146 mmol, 1.20 equiv.) were added, then the reaction mixture was stirred for 19 h. Citric acid (10%) was added and the reaction mixture was stirred for 15 min. The reaction mixture was extracted with EtOAc and the organic layer was washed sequentially with 10% citric acid, saturated aqueous NaHCO3, and brine. The organic layer was dried over MgSO4, filtered and concentrated. The crude product (0.056 g) was chromatographed (SiO2 25 g, eluted with 1:1 hexane:EtOAc) to give tert-butyl 6-[2-(benzoylamino)ethyl]-1,4,5,6-tetrahydroazepino[4,5-b]indole-3(2H)-carboxylate (0.0398 g) in 75% yield. 1H NMR (300 MHz, CDCl3) δ 1.45, 1.48, 2.96-3.05, 3.60-3.70, 3.74, 4.36-4.42, 6.29, 7.10-7.19, 7.31-7.43, 7.46-7.53, 7.63; MS (ESI+) for C26H31N3O3 m/z 434.1 (M+H)+.

Provenance & Evidence