Photoinduced Arylation of Acridinium Salts: Tunable PhotoredoxCatalysts for C-O Bond Cleavage

A photoinduced arylation of N-substituted acridi-nium salts has been developed and has exhibited a high functionalgroup tolerance (e.g., halogen, nitrile, ketone, ester, and nitro). Abroad range of well-decorated C9-arylated acridinium-basedcatalysts withfine-tuned photophysical and photochemical proper-ties, namely, excited-state lifetimes and redox potentials have beensynthetized in a one-step procedure. These functionalizedacridinium salts were later evaluated in the photoredox-catalyzedfragmentation of 1,2-diol derivatives (lignin models). Among them,2-bromophenyl substitutedN-methyl acridinium has outperformedall photoredox catalysts, including commercial Fukuzumi's catalyst,for the selective C beta O-Ar bond cleavage of diol monoarylethers toafford 1,2-diols in good yields.