ACTION DU N-BUTYLLITHIUM SUR LES BROMO-3 HALOGENO-2 PYRIDINES FLUOREE, CHLOREE ET BROMEE PRINCIPE ET ETUDE D'UNE POSSIBILITE REACTIONNELLE NOUVELLE: L'HOMOTRANSMETALLATION

Article abstract of DOI:10.1016/S0040-4020(01)96696-7

Apart from the common bromine-lithium exchange reaction in brominated aromatic compounds, it is possible to obtain a lithio-derivative quite different from the one usually described in such a reaction.This new reaction, which results from a special experimental condition is called 'homotransmetalation', and it occurs when using n-buthyllithium and 3-bromo 2-halogenopyridines (1).Different behaviour is observed with the three similar compounds (1:X = F,Cl,Br).Explanations are proposed of these results.It is then possible to compare the relative stabilities of the proposed lithio-structures.It is evident that nucleophilic substitution of bromine in position 4 of the pyridine ring is easier than is usually recognised.