Engaging visible light-induced triplet sensitization towards intramolecular [4+2] cycloadditions of naphthalenes and quinolines

Herein, we report the visible light-promoted intramolecular [4+2] cycloadditions of alkene-tethered naphthalenes and quinolines by employing a metal-free photocatalyst. The endeavor leverages the triplet sensitization of the designed substrates to give a wide range of monoxolane-bearing 3D scaffolds in high yields and selectivities. The appended mechanistic studies elucidate the proposed reaction pathway that involves triplet energy transfer catalysis.