Used as a key reagent in organic synthesis, particularly for the preparation of sulfonamide-based compounds. It reacts readily with primary and secondary amines to form sulfonamide derivatives, which are important in pharmaceutical development due to their biological activity. Commonly employed in the synthesis of protease inhibitors and other bioactive molecules. Also utilized in the modification of peptides and proteins, where it introduces a sulfonyl group for enhanced stability or altered reactivity. Its highly reactive sulfonyl chloride moiety allows for efficient sulfonylation under mild conditions, making it valuable in medicinal chemistry and bioconjugation applications.