A visible-light-induced photoredox-catalyzed tandem radical addition/cyclization of 2-alkenylphenols and CBr4 is developed. This protocol features mild and redox-neutral reaction conditions, good functional group tolerance, and operational simplicity, providing efficient and practical access to various 4-arylcoumarins in a one-pot fashion. Preliminary mechanistic investigations confirm a radical process and the significant role of the additive water.
