Aliphatic C–H Functionalization Using Pyridine <i>N</i>-Oxides as H-Atom Abstraction Agents
Marcel Schlegel, Siran Qian, David A. Nicewicz
Abstract
The alkylation and heteroarylation of unactivated tertiary, secondary, and primary C(sp3)–H bonds was achieved by employing an acridinium photoredox catalyst along with readily available pyridine N-oxides as hydrogen atom transfer (HAT) precursors under visible light. Oxygen-centered radicals, generated by single-electron oxidation of the N-oxides, are the proposed key intermediates whose reactivity can be easily modified by structural adjustments. A broad range of aliphatic C–H substrates with electron-donating or -withdrawing groups as well as various olefinic radical acceptors and heteroarenes were well tolerated.
Topics & Concepts
ChemistryRadicalPyridineHydrogen atom abstractionReactivity (psychology)CatalysisPhotoredox catalysisAlkylationPrimary (astronomy)PhotochemistryHydrogen atomSurface modificationElectron transferOxygen atomMedicinal chemistryCombinatorial chemistryOrganic chemistryMoleculeGroup (periodic table)PhotocatalysisPhysical chemistryPhysicsAstronomyPathologyMedicineAlternative medicineRadical Photochemical ReactionsCatalytic C–H Functionalization MethodsOxidative Organic Chemistry Reactions