Reactivity of halogenothiazoles towards nucleophiles. Kinetics of reactions between 2- and 4-halogenothiazoles and nucleophiles

Abstract

Substitution of halogen by nucleophile in positions 2 and 4 of the thiazole ring is reported. In some cases the reactivity of 4-halogenothiazoles is greater than that of the isomer. For both isomers addition–elimination mechanisms operate and the k₄ : k₂ ratios are very sensitive to the experimental conditions. Changes in nucleophile, the counterion of the nucleophile, and solvent are discussed. Evidence of differing steric hindrance in the nucleophiles (for the two positions considered) is presented.