Mechanism of the Visible Light-Mediated Gold-Catalyzed Oxyarylation Reaction of Alkenes

A systematic theoretical study has been carried out on the visible light-mediated gold-catalyzed oxyarylation of alkenes. The detailed mechanism of the dual Au and photoredox-catalyzed difunctionalization, including both the photoredox and gold catalytic cycles, has been investigated. The calculation results show that the oxidative quenching of the photoredox catalyst is more favorable than reductive quenching. The favorable gold catalytic cycle is the sequence of radical addition, single electron transfer (SET), coordination, cyclization, and reductive elimination. The facility of the favorable mechanism is determined by two factors: First, both oxidation steps (i.e., radical addition and SET) occur prior to the cyclization step to generate the feasible cyclization precursor of the Au­(III) complex. Second, the radical addition formally increases the electron density on the gold center and thus favors the radical addition followed by SET sequence.