A new functional group transformation allowing the synthesis of methyl-dithioesters from readily available trifluoromethyl arenes via defluorinative functionalization has been developed. This microwave-assisted method is operationally simple, rapid, and eliminates the need for pre-functionalization while accommodating a broad range of functional groups. In addition, it does not rely on highly odorous thiol sources, and utilizes the commercially available reagent BF3SMe2 complex as a multifunctional Lewis acid/sulfur source/defluorination and demethylation agent. Finally, this approach is suitable for late-stage functionalizations, as shown by the transformation of pharmaceuticals leflunomide, flufenamic acid and celecoxib into novel methyl-dithioester derivatives.