Scheme 1. Design and Synthesis of Hydroxyindole Carboxylic Acid Based Libraries 11a–d.

Conditions: (a) FmocOSu, THF, reflux, 20 h, 81.4%; (b) Pd(PPh₃)₂Cl₂, CuI, Na₂CO₃, DMF, 44%; (c) I₂, NaHCO₃, CH₂Cl₂ or AcCN, rt, 86%; (d) 50% diethylamine in DCM, 3 h, 85%; (e) 5% LiOH/THF = 1:2, 80 °C, 2 h, 97.2%; (f) corresponding acyl chloride, Et₃N, DMF, 0 °C, 80–90%; (g) 5% LiOH/THF = 1:2, rt, 2 h, 80–90%; (h) 192 amines, HOBT, HBTU, DIPEA, DMF, rt, overnigh,. 60–80%.