Continuous Flow α‑Trifluoromethylation of Ketones by Metal-Free Visible Light Photoredox Catalysis

A continuous-flow, two-step procedure for the preparation of α-CF₃-substituted carbonyl compounds has been developed. The carbonyl substrates were converted <i>in situ</i> into the corresponding silyl enol ethers, mixed with the CF₃ radical source, and then irradiated with visible light using a flow reactor based on transparent tubing and a household compact fluorescent lamp. The continuous protocol uses Eosin Y as an inexpensive photoredox catalyst and requires only 20 min to complete the two reaction steps