Trifluoroacetic acid → ethyl 5-methyl-1-oxo-2,3,4,5-tetrahydro-1H-[1,4]diazepino[1,2-a]indole-8-carboxylate

Participants

Reaction Steps

To a solution of diethyl 1-{4-[(tert-butoxycarbonyl)amino]butan-2-yl}-1H-indole-2,6-dicarboxylate (1.04 g, 1.8 mmol) in CH2Cl2 (4 mL) is added TFA (4 mL). The reaction mixture is stirred for 1 h and the solvent is removed under vacuum. To a solution of the residue in ethanol (10 mL) is added triethylamine (0.75 mL, 5.4 mmol) and K2CO3 (742 mg, 5.4 mmol). The reaction mixture is refluxed for 3 h. Then the solvent is evaporated, the residue is partitioned between EtOAc and water. The organic layer is then separated, dried (MgSO4) and concentrated to afford crude compound which is purified by flash column chromatography to afford the title compound (300 mg, 59% for two steps).

Provenance & Evidence