The reaction of dry tetramethylammonium fluoride (TMAF) with 1-methyl-2,4,5-tribromoimidazole in different polar aprotic solvents was investigated. Products of reductive debromination were obtained rather than fluorine substitution, indicating that TMAF is strongly basic in such conditions. A reaction carried out in d6-DMSO showed that the solvent is the proton source. Dimethylformamide was less effective that DMSO, N,N-dimethylacetamide or N-methylpirrolidone as a proton donor and we were able to effect significant fluorination in this solvent.
tribroimidazole; fluoroimidazole; reductive debromination
