Used as a key intermediate in the synthesis of afatinib and related irreversible tyrosine kinase inhibitors for targeted cancer therapies. Afatinib selectively inhibits mutant forms of the epidermal growth factor receptor (EGFR), blocking signaling pathways that drive tumor growth and progression. This compound is employed in the final acylation step, where the 4-bromo group facilitates the introduction of the acrylamide functionality essential for covalent binding to EGFR, supporting treatments for non-small cell lung cancer and enhancing efficacy against resistant variants while reducing off-target effects.