Trimethylsulfoxonium iodide is a sulfoxonium salt. It is used to generate dimethyloxosulfonium methylide by reaction with sodium hydride. The latter compound is used as a methylene-transfer reagent, and is used to prepare epoxides.
This compound is commercially available. It may be prepared by the reaction of dimethyl sulfoxide and iodomethane:
: (CH)SO + CHI → (CH)SOI