A Bench‐Stable Monofluoroallylsulfonium Salt for Highly Regioselective Monofluoroallylation

A bench‐stable and scalable monofluoroallylsulfonium salt (MFAS) has been developed for highly regioselective mono‐fluoroallylation. This reagent is synthesized from the inexpensive industrial chemical 3,3,3‐trifluoropropene in three steps with high efficiency. The reaction of alkylzinc reagents with MFAS proceeds smoothly under copper catalysis, yielding allylic monofluorides with excellent regioselectivity and high reaction efficiency. The synthetic utility of this reagent is demonstrated by transformations of the monofluoroallylated products.