Generation of e,e-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 e,e-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.