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

Participants

Reaction Steps

To a mixture of diethyl 1-{3-[(tert-butoxycarbonyl)amino]-2-methylpropyl}-1H-indole-2,6-dicarboxylate and diethyl 1H-indole-2,6-dicarboxylate (3.2 g, 7.4 mmol) in CH2Cl2 (70 mL) is added TFA (30 mL). The mixture is stirred at room temperature for 2 h. The reaction is concentrated and the residue is dried in vacuo for 1 h. To a solution of the residue in ethanol (150 mL) are added triethylamine (3.1 mL, 22.2 mmol) and K2CO3 (6.1 g, 44.2 mmol). The mixture is heated at 80° C. for 5 h. Water (300 mL) is added and the mixture is extracted with EtOAc (3×200 mL). The organic layers are combined, dried (Na2SO4) and concentrated and the crude compound is purified by flash column chromatography to afford the title compound (1.4 g, 66% for 3 steps).

Provenance & Evidence