Aryl–aryl cross-coupling reactions without reagents or catalysts: photocyclization of ortho-iodoaryl ethers and related compounds via triplet aryl cation intermediates

Abstract

Cyclisations of benzyl ortho-iodoaryl ethers to benzo[c]chromenes can be effected without reagents or catalysts by irradiation with UVC under flow. Reactions proceed via triplet aryl cation generation, 5-exo and 3-exo-cyclisations, and rearomatisation. They have wide scope, are easy to effect and extend to a myriad of related ring systems.