Into a 100 mL round bottom flask is weighed out 1.31 g (1.22 mmol) of 24. This is dissolved in 25 mL of dimethylformamide. Then 0.81 mL of triethylamine is added, and finally 0.623 g (1.162 mmol) of 17. The reaction mixture is left overnight, then the solution is concentrated to ˜10 mL and the resultant precipitate is filtered off, using a sintered glass filter funnel. The solid is washed with generous volumes of methanol (stirring the sludge in the filter with the methanol before applying the vacuum) several times and ether. When the effluent is clear and essentially colorless, the deep violet precipitate is dried in vacuo to afford 1.5 g (90%) of the desired product. 1H NMR (DMSO-d6) δ 11.96 (s, indole NH, 1H), 11.76 (s, indole NH, 1H), 11.69 (s, indole NH, 1H), 8.43 (d, J-2.4 Hz, aromatic proton, 1H), 8.35-8.20 (m, aromatic protons, 4H), 8.19 (d, J=9 Hz, aromatic protons, 2H), 7.85-7.75 (m, aromatic protons, 3H), 7.66 (d, J=9Hz, aromatic protons, 2H), 7.45-7.18 (m, aromatic protons, 12H), 7.10 (s, aromatic proton, 1H), 7.01 (s, aromatic proton, 1H), 6.99 (m, aromatic protons, 3H), 6.88 (d, J=9 Hz, aromatic protons, 4H), 4.61 (m, aliphatic protons, 6H), 4.14 (t, J=8.5 Hz, aliphatic protons, 2H), 3.71 (s, 2×CH3O, 6H), 3.59 (m, aliphatic protons, 2H), 3.43 (m, aliphatic protons, 6H), 3.34 (m, obscured by water signal, aliphatic protons, 2H), 3.22 (m, aliphatic protons, 2H), 3.08 (t, J=5 Hz, aliphatic protons, 2H), 2.5 (t, obscured by DMSO signal, COCH2—, 2H), 1.89 (br m, aliphatic protons, 4H).
