Dearomative Cycloadditions Utilizing an Organic Photosensitizer: An Alternative to Iridium Catalysis.

A highly efficient, cheap, and organic alternative to the commonly used iridium photosensitizer (Ir[dF(CF3)ppy]2(dtbpy))PF6 ([Ir-F]) is presented for visible-light energy transfer catalysis. The organic dye 2CzPN surpasses [Ir-F] in selectivity while at the same time being easily accessible in one step. The catalyst is recyclable and, due to its uncharged nature, soluble in nonpolar solvents such as toluene. Furthermore, the scope of molecular scaffolds that are compatible substrates for visible-light catalyzed dearomative cycloadditions is expanded.