Unsymmetric-1,3-disubstituted imidazolium salt for palladium-catalyzed Suzuki–Miyaura cross-coupling reactions of aryl bromides

Abstract

A series of 1-(ferrocenylethyl)-3-substituted-imidazolium salts [3-substitute = 2,6-di( iso-propyl)phenyl ( 1a), 2,4,6-trimethylphenyl ( 1b), tert-butyl ( 1c), 1-Ad ( 1d), cyclohexyl ( 1e)] have been synthesized from a racemic ferrocenylethyl acetate and the corresponding N-substituted imidazole in high yields (70–94%). A combination of Pd(OAc) 2 and 1a– d was found to form an excellent catalyst system for the Suzuki–Miyaura cross-coupling reactions of aryl bromides with phenylboronic acid in the presence of Cs 2CO 3.