Selective Introduction of Trifluoroacetyl Group to β‐ and δ‐Position of Aromatic Conjugated Esters: Facile Synthesis of Fluorine‐containing Keto Esters

An approach to trifluoroacetylation of aromatic conjugated esters successfully led to the efficient and selective introduction of trifluoroacetyl group to the electron‐deficient β‐ or δ‐carbon atom of ester under mild reaction conditions by magnesium‐promoted reduction, followed by deacetalization with trifluoroacetic acid in moderate to good yields. A variety of fluorinated keto esters derived from ethyl cinnamates and β, γ‐ or γ‐, δ‐unsaturated fluorinated keto esters from aromatic dienoesters with a longer conjugation system were synthesized through this simple methodology utilizing ethyl trifluoroacetate as a fluorine‐containing carbon source.