Visible-light initiated oxidative cyclization of phenyl propiolates with sulfinic acids to coumarin derivatives under metal-free conditions.

A visible-light initiated oxidative cyclization of phenyl propiolates with sulfinic acids has been developed. The arylsulfonylation of alkynes was performed at room temperature under metal-free conditions to generate coumarin derivatives with wide functional group tolerance, good yields and high regioselectivity.