eFluorination for the Rapid Synthesis of Fluorothioformates from Oxalic Acid Monothioesters

An efficient and practical electrochemical method for synthesizing fluorothioformate derivatives, an underexplored functional group, is reported. The strategy is based on the anodic decarboxylation of oxalic acid monothioesters, which rapidly generates highly reactive alkyl (oxomethylidene)sulfonium intermediates. These intermediates are effectively trapped by the inexpensive and commercially available triethylamine trihydrofluoride (Et₃N·3HF), which acts as both a nucleophilic fluoride source and a supporting electrolyte, leading to the formation of the desired fluorothioformates. This methodology enables the rapid and scalable synthesis of fluorothioformate derivatives, enabling their broader exploration in organic chemistry. In particular, these compounds can be readily and selectively converted to S-thiocarbamates and urea derivatives in a one-pot process through reactions with amines, demonstrating their synthetic utility. The scalability of this electrochemical fluorination was validated, showing no loss of yield. Cyclic voltammetry studies were carried out to shed some light on the mechanism of these novel transformations.