Reaction Steps
A suspension of quindoline (1 g, 4.6 mmol) from Example 2 and ethyl iodide (3 mL, 37.7 mmol) was heated in a bomb at 135° C. for 15 hours. The excess ethyl iodide was removed and the resulting brown precipitate was collected, washed with ether and dried, yielding 1.5 g (87.7%) of 5-ethylquindolinium hydroiodide. Recrystallization from water afforded bright yellow crystals of 5-ethylquindolinium hydroiodide, mp 256° C. [lit 222-223° C. (Fichter, F.; Boehringer, R. Ber 1906, 3941)]; 1H NMR (DMSO-d6) δ 12.93 (s, 1H, NH), 9.32 (s, 1H, H11), 8.78 (d, J=9.2, 1H, H4), 8.66 (d, J=8.4, 1H, H6), 8.60 (d, J=8.0, 1H, H1), 8.18 (t, J=7.6, 1H, H3), 7.95 (dd, J=8.0, J=7.2, 2H, H2 and H8), 7.87 (d, J=8.4, 1H, H9), 7.55 (t, J=7.6, 1H, H7), 5.55 (q, J=6.8, 2H, NCH2), 1.76 (t, J=7.2, 3H, CH3); 13C NMR (DMSO-d6) δ 145.78, 136.92, 134.34, 133.94, 133.52, 132.71, 130.06, 127.09, 126.42, 125.50, 125.14, 121.81, 117.31, 113.35, 112.80, 47.33, 13.30; MS (EI, m/z) 246 (M+ -1)
