Plasmonic Silver-Nanoparticle-Catalysed Hydrogen Abstraction from the C(sp3)−H Bond of the Benzylic Cα atom for Cleavage of Alkyl Aryl Ether Bonds

Abstract

Selective activation of the C(sp3)−H bond is an important process in organic synthesis, where efficiently activating a specific C(sp3)−H bond without causing side reactions remains one of chemistry's great challenges. Here we report that illuminated plasmonic silver metal nanoparticles (NPs) can abstract hydrogen from the C(sp3)−H bond of the Cα atom of an alkyl aryl ether β-O-4 linkage. The intense electromagnetic near-field generated at the illuminated plasmonic NPs promotes chemisorption of the β-O-4 compound and the transfer of photo-generated hot electrons from the NPs to the adsorbed molecules leads to hydrogen abstraction and direct cleavage of the unreactive ether Cβ−O bond under moderate reaction conditions (≈90 °C). The plasmon-driven process has certain exceptional features: enabling hydrogen abstraction from a specific C(sp3)−H bond, along with precise scission of the targeted C−O bond to form aromatic compounds containing unsaturated, substituted groups in excellent yields.