Copper‐Catalyzed Stereoselective Defluoroalkylation or ‐arylation of gem‐Difluoroallenes To Form Monofluoroallenes under Mild Conditions

Abstract Herein, we demonstrate the formation of monofluoroallenes through copper‐catalyzed defluoroalkylation or defluoroarylation of gem ‐difluoroallenes using affordable and readily available Grignard reagents. Additionally, alkyl lithium or alkyl zinc reagents proved successful in these transformations. Under mild conditions, monofluoroallenes can be converted into fluorinated olefinic compounds or non‐fluorinated alkyne compounds. Initial mechanistic studies suggest that the reaction may start with an organocopper reagent and undergo a rapid β‐F elimination step. Although the current enantiomeric excess is low, chiral ligands could facilitate the asymmetric transformation of this reaction.