the EGFR wild‐type A431 cells and 5c with an IC50 of 0.001 μm against the gefitinib‐sensitive HCC827 cells (EGFR del E746‐A750) was identified as highly active EGFRinhibitors. It was also significant that the discovered analogue 2f, not only has high potency against the gefitinib‐sensitivecells (IC50 = 0.031 μm), but also possesses remarkably improvedactivity against the gefitinib‐resistant cells