Hydrochloric Acid → Methyl 14-cyclohexyl-5,6,7,8-tetrahydroindolo[2,1-a][2,5]benzodiazocine-11-carboxylate

Participants

Reaction Steps

3M aqueous HCl (16 eq) was added to a solution of methyl 2-[2-(aminomethyl)phenyl]-3-cyclohexyl-1-(1,3-dioxolan-2-ylmethyl)-1H-indole-6-carboxylate in THF (0.03 M). The reaction was heated with stirring at reflux for 24 h, before being allowed to cool to RT, basified with aqueous NaOH (2N) and extracted into EtOAc (3 times). The combined organics were washed with water, brine, dried over Na2SO4, filtered and concentrated in vacuo to afford the crude intermediate as a yellow oil. This oil was taken up immediately in MeOH (0.1 M, 1 eq) and the solution acidified to pH 4 with glacial acetic acid. After stirring for 20 min, NaCNBH3 (1.3 eq) was added and the reaction stirred for a further 1 h. The reaction was quenched by addition of sat. aq. NaHCO3 and extracted into EtOAc (×3). The combined organic extracts were washed with brine before being dried over Na2SO4, filtered and concentrated in vacuo. Purification by flash column chromatography (2.5% MeOH/0.5% Et3N/CH2Cl2) gave the title compound as a pale yellow solid (46%); MS (ES+) m/z 389 (M+H)+

Provenance & Evidence