Visible-light-promoted tandem radical fluoroalkylation/cyclization to access fluoroalkyl-containing chromones/chroman-4-ones

Abstract

A visible-light-induced cascade radical fluoroalkylation/cyclization of o-hydroxyaryl enaminones/2-(allyloxy)benzaldehydes with CF₃Br/1,2-dibromotetrafluoroethane in the presence of fac-Ir^III(ppy)₃ and K₂HPO₄ has been developed, which efficiently provides 3-fluoroalkyl-substituted chromone and chroman-4-one derivatives in good yields. In particular, the industrially available and low cost CF₃Br and 1,2-dibromotetrafluoroethane are used as fluoroalkyl reagents in this process, endowing the process with the potential to be used on a large scale. The mechanism was proposed based on the control experiments. The protocol also has the advantages of broad substrate scope and green energy source.