Pyridin-2-ylsulfinylfluoroacetate Reagent for the Stereoselective Synthesis of Z‑Monofluoroalkenes

Abstract

We report a practical modification of the classical Allmendinger-type reagent for the stereoselective synthesis of Z‑monofluoroalkenes. Replacement of the phenylsulfinyl group with a pyridin-2-ylsulfinyl moiety provides a reagent that affords cleaner reaction mixtures and facilitates product isolation. This difference translates into improved isolated yields and enhanced compatibility with acid-sensitive substrates while maintaining the overall efficiency of the reaction. The utility of this method was demonstrated for representative alkyl halides as well as structurally complex substrates derived from amino acids and carbohydrates, including the synthesis of a Z‑fluoroalkene analogue of acetylated lysine. This study emphasizes practical reliability rather than exhaustive substrate scope, and highlights the advantage of the pyridyl sulfoxide framework as a useful alternative for the preparation of Z‑fluoroalkenes.