The Metalation of Fluoroanisoles: Optional Regioselectivity Due to Metal Mediated Control

Abstract
2- and 4-Fluoroanisole undergo hydrogen/metal exchange at the position next to the alkoxy moiety if butyllithium or tert-butyllithium is employed and at the position next to the halogen atom if the stoichiometric mixture of butyllithium and potassium tert-butoxide serves as the reagent. 3-Fluoroanisole is always attacked at the position flanked by the two heterosubstituents.