Trimethylsulfoxonium chloride is a key reagent in organic synthesis, primarily utilized to generate dimethylsulfoxonium methylide (via deprotonation with a base) for the Corey-Chaykovsky reaction. This ylide facilitates the stereospecific conversion of aldehydes and ketones to epoxides, as well as the addition to α,β-unsaturated carbonyl compounds to form cyclopropanes. These transformations are essential in the production of pharmaceuticals, agrochemicals, and fine chemicals. It also finds applications as a mild methylating agent for certain substrates and in the preparation of other sulfur-based intermediates. Its high stability and controlled reactivity make it ideal for both laboratory research and industrial-scale precise synthetic processes.