Bichromophoric Ruthenium Complexes for Photocatalyzed Late-Stage Synthesis of Trifluoromethylated Indolizines

Indolizines are a promising class of biologically active compounds. However, photocatalytic methods for their selective derivatization are scarce in the literature. Herein, a mild, simple, and chemoselective protocol for the synthesis of 3-(trifluoromethyl)indolizine has been developed. The desired products were obtained in good to excellent yields and can be easily obtained on a gram scale. By tuning the redox properties of a Ru-based photocatalyst, it is possible to achieve competitive yields and further apply the optimized conditions to a broad variety of substrates. This method tolerates many functional groups and, therefore, can be used for late-stage functionalization. Our combined theoretical and spectroscopic findings revealed that the superior dyad-like ruthenium catalyst developed in this study has a completely different electronic nature of both key species that are crucial for efficient photoredox catalysis compared to commonly used homoleptic ruthenium complexes.