Reaction of a series of 2, 5-dibromo-substituted aromatic systems with 1 equiv of n- butyllithium at-100" C results in high selectivity of halogen-metal exchange when the substituent contains unshared electrons. The results suggest that product distribution at-100" C is determined by thermodynamic rather than kinetic factors. Fair to excellent yields of derivatives of the monolithium intermediates have been obtained. Reaction of 2, 5- ...
