Metal-Free Catalytic Asymmetric Fluorination of Keto Esters Using a Combination of Hydrogen Fluoride (HF) and Oxidant: Experiment and Computation

A chiral iodoarene organocatalyst for the catalytic asymmetric fluorination has been developed. The catalyst was used in the asymmetric fluorination of carbonyl compounds, providing the products with a quaternary stereocenter with high enantioselectivities. Chiral hypervalent iodine difluoride intermediates were generated in situ by treatment of the catalyst with an oxidant and hydrogen fluoride as fluoride source. As such, the alpha-fluorination of a carbonyl compound was achieved with a nucleophilic fluorine source. A combined computational and experimental approach provided insight into the reaction mechanism and the origin of enantioselectivity.