The reaction was carried out in the presence of copper(I) iodide (1.2 mg, 6.3 μmol) in DMF (45 mL) at reflux for 6 h. The reaction was carried out in the presence of 2-(3,3-dimethyl-1-butyn-1-yl)-4-nitroaniline (2.7 g, 12.4 mmol). Upon completion of the reaction, volatiles were removed by distillation under reduced pressure and the black residue obtained was purified by silica gel column chromatography (eluent: 20% ethyl acetate/hexane). The target product was collected and ground with hexane to give 2.34 g (87% yield) of 2-tert-butyl-5-nitroindole as a yellow crystalline solid. The product was confirmed by 1H NMR (CDCl3): δ 8.51 (d, J = 1.9 Hz, 1H), 8.33 (br s, 1H), 8.07 (dd, J = 8.9, 2.3 Hz, 1H), 7.35 (d, J = 8.8 Hz, 1H), 6.44 (d, J = 1.9 Hz, 1H), 1.44 (s, 9H). Mass spectrometry (MS) showed a molecular ion peak m/z of 219 ([MH]+).
