• With n-BuLi and TMEDA at -60 o, lithiation occurs predominantly at the 2-position, with some 4-lithiation: Tetrahedron, 39, 2009 (1983). With LDA at -60 o, exclusive 4-lithiation occurs: J. Org. Chem., 47, 2633 (1982); Heterocycles, 35, 151 (1993).