To a mixture of tert-butyl 1,4,5,6-tetrahydroazepino[4,5-b]indole-3(2H)-carboxylate (3.557 g, 12.42 mmol) and N,N-dimethylformamide (30 mL) was added 60% sodium hydride (0.596 g, 14.90 mmol). The mixture stirred for 1 h, and then cooled in a 0° C. bath. Ethyl bromoacetate was added, and the mixture warmed to room temperature. Water then was added and the mixture was evaporated in vacuo. The residue was taken up in ethyl acetate and washed with water. Evaporation and trituration with hexanes provided 3.289 g of the title compound, the structure of which is shown in FIG. 6 as (23) (where n=1).
