Scheme 4.

Preparation of indolyl quinol analogues containing a melamine moiety. Reagents and conditions: (a) 2-Iodoaniline, pyridine, THF, 25 °C, 16 h, 62%; (b) (i) KOH, H₂O, 100 °C, 1 h; (ii) HCl, H₂O, 0 °C, 1 h, 95%; (c) 1, CuI, Pd(PPh₃)₄, DMAc, H₂O, ⁱPr₂NH, 100 °C, 10 min, 14%; (d) DIC, DIPEA, DMF, 0–25 °C, 18 h, 67%; (e) 42, TBTU, HOAt, DIPEA, DMF, 25 °C, 16 h, purification not successful; (f) 45, TBTU, HOAt, DIPEA, DMF, 25 °C, 16 h, 11%; (g) 1, CuI, Pd(PPh₃)₄, DMF, H₂O, ⁱPr₂NH, 100 °C (MW), 10 min, 40%.