Synthesis of Partially Fluorinated Alkyl Triflates by Electrochemical Fluorination (Simons Process)

A scalable straightforward synthesis of monofluoro- and difluoromethyl triflate CF3SO2OCH2F (MH2F) and CF3SO2OCHF2 (MHF2) through electrochemical fluorination (ECF, Simons process) of methyl triflate MH3 in anhydrous hydrogen fluoride at nickel anodes is presented. The ECF method is also feasible for the preparation of the deuterated analogues CF3SO2OCD2F (MD2F) and CF3SO2OCDF2 (MD2F). Surprisingly, no H/D exchange occurs during ECF of CF3SO2OCD3 (MD3); this provides further evidence for a NiF3/NiF4-mediated ECF mechanism. The ECF of selected partially fluorinated ethyl triflates is described, and electrochemical fluorination of CF3SO2OCH2CF3 (EH2F3) leads to the until now unknown chiral CF3SO2OCHFCF3 (EHFF3). The analogous fluoromethyl and fluoroethyl nonaflates are also accessible by ECF. This study contains detailed spectroscopic, structural, and thermal data on (fluoro)methyl and fluoro(ethyl) triflates. The electrosynthesis of partially fluorinated alkyl triflates and nonaflates by using electrochemical fluorination (ECF) has been developed; it provides access to CF3SO2OCH2F and CF3SO2OCHF2 as well as their deuterated analogs. Selected ethyl triflates and nonaflates are also accessible through ECF.image