Synthesis of gem­-difluorocyclobutanes: Organolanthanum enabled synthesis and divergent catalytic functionalization of gem-difluorocyclobutanols

Fluorinated cycloalkyl motifs continue to receive intense interest in medicinal chemistry due to their potential to modulate physicochemical properties. In recent years, this interest has extended to gem-difluorocyclobutanes as small, polar yet lipophilic moieties. However, strategies to access gem­difluorocyclobutanes remain extremely limited preventing routine investigation. Here, we report the synthesis and divergent functionalization of gem-difluorocyclobutanols to generate a diverse range of 1,1-disubstituted-3,3-difluorocyclobutanes. The use of organolanthanum reagents is crucial to achieve the addition of carbon nucleophiles to commercially available difluorocyclobutanone to avoid undesired elimination of HF by controlling nucleophile basicity. The generated difluorocyclobutanols enable functionalization through carbocation and radical intermediates, providing diverse 1,1-disubstitued difluorocyclobutanes, and expediting access to new design options for medicinal or materials chemistry.