Arenesulfenyl Fluorides: Synthesis, Structure, and Reactivity

Sulfenyl fluorides are organic compounds of sulfur in formal oxidation state +2 with the formula R–S–F. Although the chloride, bromide, and iodide analogues have been extensively described in the literature, organic sulfenyl fluorides remain essentially unstudied. These structures have been implicated as putative intermediates in established processes to access polyfluorinated sulfur species; however, definitive and direct evidence of their existence has not been achieved, nor has a systematic understanding of their reactivity. Here, we report the synthesis, isolation, and spectroscopic characterization of several arenesulfenyl fluorides, including structural analysis of 2,4-dinitrobenzenesulfenyl fluoride by single-crystal X-ray diffraction. The functional group undergoes direct, efficient, and highly regioselective anti-addition to alkenes and alkynes, as well as insertion by carbenes. The resulting α- or β-fluoro thioether adducts can be readily transformed into useful fluorinated motifs, for example by modification of the sulfur groups (to sulfonamides or sulfonyl fluorides), by sulfur elimination (to generate formal C–H fluorination products), or by Julia–Kocienski olefination (to form vinyl fluorides). Thus, we establish that sulfenyl fluorides are unexpectedly accessible and stable compounds. Further, they serve as versatile reagents for the production of fluorinated organic compounds.