Base-mediated intramolecular aryl-aryl coupling in pyrazolyl-containing iodolium salts

Pyrazolyl-containing aryliodolium salts undergo transformation to iodopyrazoles accompanied by the formation of a new C sp 2 -C sp 2 bond in the presence of a base (DIPEA, NaOH, or K 2 CO 3 ). The plausible mechanism of the base-mediated reaction is suggested. The catalytic activity of the iodine-containing species is studied in the model reaction. The base-catalyzed reaction might proceed not via the previously suggested radical route, but via the nucleophilic attack on the meta -position to the iodine( iii ) center, which rise another view on the reactivity of aryliodolium salts.