A new cycloaddition profile for ortho -quinone methides: photoredox-catalyzed [6+4] cycloadditions for synthesis of benzo[ b ]cyclopenta[ e ]oxepines.

Visible-light-induced [6+4] cycloaddition reactions of ortho -quinone methides have been developed. The reaction of ortho -quinone methides with pentafulvenes in the presence of a thioxanthylium photoredox catalyst afforded benzo[ b ]cyclopenta[ e ]oxepines. The present reaction represents a promising tool for the synthesis of natural products and bioactive compounds that contain a benzoxepine structure.