4-Sulfanylmethyl- and 4-sulfonylmethyl-substituted N,N′-diarylimidazolium salts as new proligands in the synthesis of Pd complexes with N-heterocyclic carbenes.

The reaction of readily available N,N′-diaryl-4-chloromethylimidazolium chlorides with thiols afforded 4-(alkyl)arylsulfanylmethyl-N,N′-diarylimidazolium salts. The oxidation of these salts with hydrogen peroxide catalyzed by ammonium paramolybdate gave the previously unknown 4-(alkyl)arylsulfonylmethyl-N,N′-diarylimidazolium salts. The synthesized imidazolium salts can be used as sources of N-heterocyclic carbenes (NHCs). The conditions were found for the selective palladation of these compounds involving the C(2) atom of the imidazole ring. Palladium complexes with NHC ligands functionalized with RSCH2 and RSO2CH2 groups were synthesized. The potential applicability of these complexes as catalysts for cross-coupling reactions was demonstrated. [ABSTRACT FROM AUTHOR]