An improved process for preparing 4-[(3-chloro-4-fluorophenyl)amino]-6-{[4-(N,N-dimethylamino)-1-oxo-2-buten-1-yl]amino}-7-((S)-tetrahydrofuran-3-yloxy)-quinazoline and related aminocrotonyl compounds and the preparation of a suitable salt of 4-[(3-chloro-4-fluorophenyl)amino]-6-{[4-(N,N-dimethylamino)-1-oxo-2-buten-1-yl]amino}-7-((S)-tetrahydrofuran-3-yloxy)-quinazoline for use as a pharmaceutically active substance.本發明係關於一種用於製備4-[(3-氯-4-氟苯基)胺基]-6-{[4-(N,N-二甲基胺基)-1-氧代-2-丁烯-1-基]胺基}-7-((S)-四氫呋喃-3-基氧)-喹唑啉以及相關之胺基巴豆基化合物之改良方法,以及用作醫藥活性物質之4-[(3-氯-4-氟苯基)胺基]-6-{[4-(N,N-二甲基胺基)-1-氧代-2-丁烯-1-基]胺基}-7-((S)-四氫呋喃-3-基氧)-喹唑啉之適宜之鹽之製備。