Green-Light-Driven Fe(III)(btz)(3) Photocatalysis in the Radical Cationic [4+2] Cycloaddition Reaction

Abstract

Green-light-driven Fe-III(btz)(3) photocatalysis for the radical cationic [4+2] cycloaddition of terminal styrenes and nucleophilic dienes has been investigated. The Fe-MIC (mesoionic carbene) complex forms a ligand-to-metal charge-transfer transition state with relatively high excited-state reduction potentials that can selectively oxidize terminal styrene derivatives. Unique multisubstituted cyclohexenes and structurally complex biorelevant cyclohexenes were constructed, highlighting the usefulness of this mild and practical first-row transition metal complex system.