Visible-light-induced generation of alkenyl radicals from alkenyl sulfonium salts: direct synthesis of 11-alkenyl-substituted dibenzodiazepines

A method involving visible-light-induced generation of alkenyl radicals from vinylsulfonium salts derived from di(alkylthio)-substituted alkenes has been developed. Using the alkenyl radicals each as a key intermediate, the tandem cyclization of alkenyl sulfonium salts with <i>o</i>-isocyanodiaryl amines has been performed. The reaction provides a novel and highly efficient strategy for the synthesis of 11-alkenyl-substituted dibenzodiazepines in a single step.