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 fert-butoxide serves as the reagent 3-Fluoroanisole is always attacked at the position flanked by the two hetero-substituents.