The compound with CAS number 314771-76-1, known as N4-(3-chloro-4-fluorophenyl)-7-[[(3S)-tetrahydro-3-furanyl]oxy]-4,6-quinazolinediamine, is a key intermediate in the synthesis of the anticancer drug Afatinib (BIBW 2992). It is a quinazoline derivative featuring a 3-chloro-4-fluorophenyl group and a (S)-tetrahydrofuran-3-yloxy substituent. Afatinib is a second-generation, irreversible tyrosine kinase inhibitor (TKI) that targets the epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2). It is approved for the treatment of patients with metastatic non-small cell lung cancer (NSCLC) harboring specific EGFR mutations. This intermediate is crucial for constructing the core pharmacophore of Afatinib during its chemical manufacturing process. As a specialized synthetic building block, its primary and definitive application is confined to the pharmaceutical production of this specific active pharmaceutical ingredient (API). It is not a general-purpose reagent for broad organic synthesis.