Used primarily as a key intermediate in the synthesis of pharmaceutical compounds, particularly in the development of selective adrenergic receptor antagonists. Its sulfonyl chloride functional group allows for easy attachment to amines or alcohols, making it valuable in constructing biologically active molecules. It is also employed in the preparation of fluorescent probes and labeling agents due to its stable aromatic backbone and reactivity profile. Commonly found in research settings for modifying molecular structures to enhance binding affinity or metabolic stability in drug candidates.