(2E)-N-[3,4-Dihydro-4-oxo-7-[[(3S)-tetrahydro-3-furanyl]oxy]-6-quinazolinyl]-4-(dimethylamino)-2-butenamide, s an impurity of Afatinib (A355300), an aminocrotonylamino-substituted quinazoline derivative used for treating cancer and diseases of the respiratory tract, lungs, gastrointestinal tract, bile duct, and gallbladder.
