Generation of ϵ,ϵ‐Difluorinated Metal‐Pentadienyl Species through Lanthanide‐Mediated C−F Activation

Abstract

Heavy metal on Lewis acid: The combination of lanthanide metals and AlCl₃ has been employed for selective single C-F activation in benzofulvenes comprising an exocyclic CF₃ substituent. Intermediate ϵ,ϵ-difluorinated metal-dienyl species react with a large variety of aldehydes in a highly regio- and diastereoselective fashion to afford 1,1-disubstituted indenes bearing a difluorovinyl group. These new building blocks have been further transformed through a hydrogenation-cyclization process into fluorinated heterocyclic spiro compounds.