To a solution of carbazole (33) (45 mg, 0.12 mmol) prepared as described in example 79 in acetic anhydride (4.0 mL) was added 35% perchloric acid (2 drops). The resulting solution was stirred at room temperature for 30 minutes before being poured onto ice water, basified by the addition of solid potassium bicarbonate and extraction with ethyl acetate. The organic phase was dried, the drying agent was removed and the solution was concentrated to dryness. Chromatography on silica eluting with ethyl acetate/hexane (2:3), followed by trituration from ethyl acetate gave acetamide (338) (40 mg, 80%) as a pale yellow powder, mp 277–280° C. 1H NMR δ [(CD3)2SO] 11.46 (br s, 1H), 8.74 (d, J=2.8 Hz, 1H), 8.53 (s, 1H), 8.17 (d, J=9.2 Hz, 1H), 7.60 (m, 1H), 7.54–7.47 (m, 3H), 7.32 (dd, J=9.2, 2.8 Hz, 1H), 3.93 (s, 3H), 2.91 (s, 3H). Found: C, 65.50; H, 3.49; N, 6.61. C23H15ClN2O4.1/4H2O requires: C, 65.26; H, 3.69; N, 6.62.
