The Br undergoes selective displacement with Na alkoxides in NMP, in the presence of CuBr: Tetrahedron, 48, 3633 (1992). Lithiation with LDA at -75o results mainly in deprotonation ortho to F; subsequent reaction with CO2 gives 5-bromo-2-fluorobenzoic acid: Tetrahedron Lett., 33, 7495 (1992). Improved yields are obtained by the use of Li 2,2,6,6-tetramethylpiperidide (LTMP) as base: Tetrahedron Lett., 37, 6551 (1996).
