Aryl Pyrazoles from Photocatalytic Cycloadditions of Arenediazonium
Luana Cardinale, Michael Neumeier, Michal Májek, Axel Jacobi von Wangelin
Abstract
A photocatalytic synthesis of 1,5-diaryl pyrazoles from arenediazoniums and arylcyclopropanols is reported. The reaction proceeded under mild conditions (rt, 20 min) with catalytic [Ru(bpy)3]2+ under blue-light irradiation and exhibited compatibility with several functional groups (e.g., I, SF5, SO2NH2, N3, CN) and perfect levels of regiocontrol. Mechanistic studies (luminescence spectroscopy, CV, DFT, radical trapping, quantum yield determination) documented an initial oxidative quenching of the excited photocatalyst and the operation of a radical-chain mechanism.
Topics & Concepts
ChemistryPhotocatalysisPhotochemistryQuantum yieldQuenching (fluorescence)ArylCatalysisYield (engineering)SpectroscopyExcited stateLuminescenceOxidative phosphorylationReaction mechanismIrradiationCombinatorial chemistryOrganic chemistryFluorescenceBiochemistryMetallurgyQuantum mechanicsPhysicsAlkylNuclear physicsMaterials scienceOptoelectronicsRadical Photochemical ReactionsCatalytic C–H Functionalization MethodsOxidative Organic Chemistry Reactions