Scheme 5. Synthesis of analog 46 and 47 a.
aReagents and conditions: (a) iPr2NEt, CH2Cl2, 0 °C, 1 h, 96% (b) Fe, NH4Cl, EtOH, reflux, 94% (c) t-BuBrettPhos, t-BuBrettPhos-palladacycle, LHMDS, THF, 80 °C, 14 h, 62–83% (d) K2CO3, 125 °C, 14 h, 60% e) TFA, CH2Cl2, 100 °C, MW, 15 min.