Visible‐Light Cascade Photooxygenation of Tetrahydrocarbazoles and Cyclohepta[<i>b</i>]indoles: Access to <i>C</i>,<i>N</i>‐Diacyliminium Ions
Mario Frahm, Thorsten von Drathen, Lisa Marie Gronbach, Alice Voss, Felix Lorenz, Jonas Bresien, Alexander Villinger, Frank Hoffmann, Malte Brasholz
Abstract
Tetrahydrocarbazoles and perhydrocyclohepta[b]indoles undergo a catalytic cascade singlet oxygenation in alkaline medium, which leads to chiral tricyclic perhydropyrido- and perhydroazepino[1,2-a]indoles in a single operation. These photooxygenation products are new synthetic equivalents of uncommon C,N-diacyliminium ions and can be functionalized with the aid of phosphoric acid organocatalysis.
Topics & Concepts
PhotooxygenationPhosphoric acidCascadeOrganocatalysisIonChemistryCatalysisSinglet stateSinglet oxygenCombinatorial chemistryPhotochemistryOrganic chemistryEnantioselective synthesisPhysicsOxygenChromatographyNuclear physicsExcited stateAsymmetric Synthesis and CatalysisRadical Photochemical ReactionsCatalytic C–H Functionalization Methods