A Tin-Free Route to trans-Diels-Alder Motifs by Visible Light Photoredox Catalysis

A tin-free trans-Diels-Alder paradigm for the stereoselective synthesis of trans-fused polycyclic systems was developed through the photocatalytic reductive dehalogenation of alpha-haloketones promoted by visible light. Good to excellent diastereoselectivities were observed in the stereoselective construction of trans-fused octalone derivatives under mild reaction conditions.