Control of Site-Selectivity in Hydrogen Atom Transfer by Electrostatic Interaction: Proximal-Selective C(sp<sup>3</sup>)–H Alkylation of 2-Methylanilinium Salts Using a Decatungstate Photocatalyst
Jialin Zeng, Takeru Torigoe, Yoichiro Kuninobu
Abstract
Site-selective C(sp3)–H alkylation of 2-methylanilinium salts via radical intermediates was developed. The anionic decatungstate photocatalyst ([W10O32]4–) interacts with the ammonium group of the substrate through electrostatic interaction and selectively abstracts a hydrogen atom from the proximal benzylic carbon atom under UV irradiation. A variety of 2-methylanilinium salts reacted with electron-deficient alkenes. The alkylated product was successfully converted into an aryl iodide via cleavage of the C–N bond and a tetrahydrobenzoazepinone derivative by intramolecular cyclization. Mechanistic studies clearly show the existence of the interactions between [W10O32]4– and the ammonium group.
Topics & Concepts
ChemistryAlkylationIntramolecular forcePhotochemistrySelectivityPhotocatalysisArylHydrogen atomBond cleavageHydrogen bondMedicinal chemistryIodideCatalysisStereochemistryOrganic chemistryMoleculeGroup (periodic table)AlkylCatalytic C–H Functionalization MethodsRadical Photochemical ReactionsPolyoxometalates: Synthesis and Applications