Unexpected Regioselectivity in the Lithiation of Fluoroanisoles

Article abstract of DOI:10.1021/jo00249a004

The regioselectivity of lithiation of a series of fluoroanisoles and fluoroveratroles has been studied by determining the ratio of isomeric aldehydes produced by dimethylformamide quenching.The position of lithiation is influenced by such factors as temperature and time of the reaction.Contrary to published reports, fluorine competes significantly with the methoxy group as an ortho director in lithiation reactions.Lithiation of dimethyl-tert-butylsilyl ethers of fluorophenols proceeds exclusively ortho to fluorine.