Nickel-catalyzed reductive defluorination of iodo allylic gem-difluorides: allenyl monofluoride synthesis.

As a potential fluorinated synthon, there have been only limited reports on fluorinated allene synthesis and applications due to concerns about their stability. Here, we developed a nickel-catalyzed reductive defluorination of iodo allyl gem-difluorides to afford allenyl monofluorides under mild conditions with good functional group tolerance, which were easily converted to other C-F bond compounds, such as alkyl and alkenyl fluorides. Preliminary mechanistic studies suggested that monofluoroallenes were yielded by β-F elimination of the alkenyl C-Ni intermediates from the oxidative addition of C-I bonds to a nickel(0) catalyst, while zinc regenerates the catalyst and closes the catalytic cycle.