Directed lithiation of substituted aromatics and heterocycles containing a directing metalating group with alkyllithium in anhydrous tetrahydrofuran or diethyl ether at low temperature provides the corresponding lithium intermediates. Reaction of the lithium reagents obtained in situ with various electrophiles gives the corresponding substituted derivatives in high yields. The process has been applied for various derivatives and has proven to be a convenient method for modification of ring systems.