4-Bromo-2-benzofuran-1[3H]-one is a versatile reactant used in various syntheses. It is used in preparation of Citalopram (C505000) analogs via Suzuki coupling. 4-Bromo-2-benzofuran-1[3H]-one is used in the synthesis of butylphthalide derivatives possessing vasorelaxant activity. Also used in the synthesis of Pentacyclines that are Tetracycline (T291400) analogs.