Redox-Neutral Cascade Trifluoromethylation of Dienes and Enynes using a Perylene Diimide (PDI) Organophotocatalyst

The Perylene diimide (PDI) is an underexplored synthetic organic dye with significant potential in photoredox catalysis. We have developed a good chemo- and regioselective, atom-economical methodology for synthesizing trifluoroethylated saturated heterocyclic derivatives and trifluoroethyl-containing cyclobutane derivatives. This process involves the generation of trifluoromethyl radical from the Langlois (CF₃SO₂Na) reagent under photoredox conditions, which selectively reacts with the electron-rich terminal double/triple bonds in the diene/enyne framework. The resulting intermediate undergoes a cascade cyclization, yielding the desired compounds in a redox-neutral manner. Our methodology operates under very mild conditions, eliminating the need for transition metals and external oxidizing agents. It is broadly applicable across various substrates and is supported by comprehensive mechanistic insights from regular photophysical experiments.