Electrophilic Substitution of Thiophenes with Arylpalladium(II) and Platinum(II) Complexes: Mechanistic Studies on Palladium-Catalyzed CH Arylation of Thiophenes

Mechanistic studies on palladium-catalyzed CH arylation of thiophenes which has been shown by our group are carried out by a stoichiometric reaction of organometallic complexes. The reaction of arylpalladium(II) halide with 2,3-dibromothiophene in the presence of AgNO 3 /KF as an activator induces electrophilic substitution at the CH bond of the thiophene to give CH arylated product. The similar reaction of arylplatinum(II) halide with thiophene derivatives affords the aryl(thienyl)platinum(II) complex which is an analog of a precursor of the product of the CH arylation reaction. These results suggest that the palladium-catalyzed CH arylation reaction of thiophenes proceeds through electrophilic substitution.