Intramolecular PCET of α-Keto Acids: Synthesis of Trifluoromethyl Ketones via Ketyl Radicals

Due to favourable pharmacological properties, the introduction of the fluorine atom into small molecules has become increasingly more common over the past few decades. In particular, the trifluoromethyl ketone group is of great interest due to its role as a carboxylic acid bioisostere. Recently, these fragments have been accessed via acyl radical equivalents. Herein, we disclose an unconventional intramolecular proton-coupled electron transfer activation of α-keto acids by photoredox catalysis to generate ketyl radicals toward accessing functionalizable lactones. These lactones serve as synthons for modular one-pot syntheses of trifluoromethyl ketones in a net dicarbofunctionalization of electron-rich olefins.