Used as an acylating agent in organic synthesis, particularly in the preparation of amides and esters. It reacts with amines to form N-acylpyrrolidine derivatives, which are useful intermediates in pharmaceutical manufacturing. Commonly employed in the synthesis of active pharmaceutical ingredients (APIs) due to its ability to introduce the pyrrolidine carbonyl moiety, enhancing metabolic stability and bioavailability in drug molecules. Also utilized in peptide chemistry for protection and coupling steps. Sensitive to moisture, so reactions are typically carried out under anhydrous conditions.