We report here the design and synthesis of a series of 4-anilinoquinazoline derivatives, of which 7 compounds were crystallographically characterized, as epidermal growth factor receptor (EGFR) inhibitors by modifications on the aniline ring or at the 6-alkoxy site of the 6,7-dimethoxy-4-anilinoquinazoline pharmacophore. The relative inhibition efficiency on EGFR of all as-prepared compounds were measured and ordered, and the IC50 values of nine highly active compounds were determined by ELISA. Docking studies indicated that all 4-anilinoquinazoline derivatives could be inserted into the ATP-binding pocket of the EGFR via indirect docking, and that the modifications at the 3'-position of the anilino group and 6-alkoxy site of the quinazoline ring have little interference with the formation of the two essential H-bonds between the N3 of the quinazoline ring and Thr766 through a water molecule, and the N1 of the quinazoline ring and N-H of Met769. The displacing of the phenyl at 4-position with pyridinyl dramatically reduces the activity of the quinazoline pharmacophore, the resulting derivative (10) being the least active compound. The docking results also showed that the formation of new H-bonds between the N-H of the ethylenediamine group linked to the 6-alkoxy site and Asp776/Cys773 in the binding pocket of EGFR makes compounds 19 (IC50=12.1±1.6 nM) and 20 (IC50=13.6±0.8 nM) the most potent EGFR inhibitors in this class and worthy of further modification to obtain more potent anticancer compounds.
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