Radical α-Trifluoromethoxylation of Ketones under Batch and Flow Conditions by Means of Organic Photoredox Catalysis

The first light-driven method for the alpha-trifluoromethoxylation of ketones is reported. Enol carbonates react with N-trifluoromethoxy-4-cyano-pyridinium, using the photoredox catalyst 4-CzIPN under 456 nm irradiation, affording the alpha-trifluoromethoxy ketones in <= 50% isolated yield and complete chemoselectivity. As shown by 29 examples, the reaction is general and proceeds very rapidly under batch (1 h) and flow conditions (2 min). Diverse product manipulations demonstrate the synthetic potential of the disclosed method in accessing elusive trifluoromethoxylated bioactive ingredients.

Automated summary

A light-driven method for the alpha-trifluoromethoxylation of ketones has been developed, showing good generality and efficiency under batch and flow conditions. The method demonstrates the potential in accessing a variety of elusive trifluoromethoxylated bioactive ingredients.