Chemo‐/Regioselective [5+1] Annulation with <i>gem</i>‐Difluoromethylene Allenes for the Assembly of Fluorinated 2<i>H</i>‐Chromenes and Dihydroquinolines

Abstract A variety of fluorinated 2 H ‐chromenes and dihydroquinolines was synthesized by virtue of gem ‐difluoromethylene allenes as versatile coupling partners to participate in the transition metal‐catalysed cascade C−H activation/[5+1] annulation of 2‐alkenylphenols/anilines. This protocol features specific chemo‐/regioselectivity, redox‐neutral manner and good compatibility, providing a straightforward synthetic route to intriguing motifs with the equipment of attractive fluoroalkenyl moiety. The distinctive gem ‐difluorine effect induced an unexpected protonolysis of σ carbon‐metal bond, thus accounting for the observed selectivity via sequential C−H activation/allene insertion/protonolysis/cyclization/β‐F elimination process.