The mechanistic and synthetic chemistry of imidazole-based superelectrophiles has been studied. The protonated imidazole ring, or imidazolium group, is shown to enhance the electrophilic reactivity of an adjacent carboxonium group (compared to a related monocationic species). This leads to efficient condensation reactions between imidazole aldehydes and ketone with arenes in the Brønsted superacid CF3SO3H. The imidazole-based superelectrophiles are shown to be useful in other reactions leading to functionalized heterocycles. The imidazolium group may also trigger charge migration reactions in dicationic species.

1,2-Indandione reacts efficiently with arenes to give 2,2-diaryl-1-indanones by the hydroxyalkylation reaction. The Brønsted superacid CF3SO3H (triflic acid) is an effective catalyst for these condensation reactions. The requisite 1,2-indandiones were prepared from the 1-indanones.

Imidazole derivatives R 0190Superelectrophilic Chemistry of Imidazoles. -Treatment of imidazole ketones, aldehydes, and alcohols with TfOH results in formation of dicationic species which smoothly react with arenes to afford products like (III), (V), and (VII). Under appropriate conditions, charge migration can be observed yielding derivatives such as (VIII). In some cases intramolecular cyclization is possible to give fused imidazoles. N-Acylated imidazoles smoothly undergo acyl transfer reaction in the presence of TfOH. -(SHEETS, M. R.; LI, A.; BOWER, E. A.; WEIGEL, A. R.; ABBOTT, M. P.; GALLO, R. M.; MITTON, A. A.; KLUMPP*, D. A.; J.

Superacid-Promoted Hydroxyalkylation of 1,2-Indandiones. -2,2-Diaryl--1-indanones (III) are efficiently obtained by TfOH-promoted condensation of 1,2-indandiones with arenes. -(TRACY, A. F.; ABBOTT, M. P.; KLUMPP*, D. A.; Synth. Commun. 43 (2013) 16, 2171-2177, http://dx.