N-Acylimidazoles-Trifluoroacetic Acid System as the Acylating Agent for Aromatic Hydrocarbons

Article abstract of DOI:10.1246/bcsj.53.1638

N-Benzoylimidazole in trifluoroacetic acid could benzoylate electron-rich aromatic compounds, such as durene, p-dimethoxybenzene, mesitylene, anisole, thiophene, and fluorene, to give the corresponding benzophenone derivatives in good yields.It was further elucidated, in the reaction of fluorene, that N-acylimidazoles composed of a variety of acyl groups also could be used for the ketone synthesis.Therein, the imidazolides of aliphatic carboxylic acids or substituted benzoic acid with an electron-donating group gave ketones in high yields.The above-mentioned aromaticcompounds were also acylated with N-trifluoroacetylimidazole and free carboxylic acids in trifluoroacetic acid.The mechanism for these reactions was assumed to proceed via a mixed anhydride between trifluoroacetic acid.