TRANSMISSION D'UN EFFET STERIQUE PERI A TRAVERS UN NOYAU HETEROAROMATIQUE--II INFLUENCE SUR LA REACTIVITE A LONGUE DISTANCE

Article abstract of DOI:10.1016/S0040-4020(01)97720-8

The quantitative nucleophilic reactivity of alkyl and dialkylimidazo<1,2-a> pyridines towards methyl iodide is described.In the series of monomethyl derivatives the 7-methyl compound is the most activated and the 8-methyl compound the most deactivated.The effects of two alkyl substituants on the rate of alkylation are additive in the absence of intramolecular steric interaction.On the contrary a deactivation on N₁ is observed for the peri disubstituted derivatives and the deactivation increases with the substituent size.Interpretations of these electronic and steric effects are proposed.