Synthesis, characterization, and microwave-assisted catalytic activity in Heck, Suzuki, Sonogashira, and Buchwald{Hartwig cross-coupling reactions of novel benzimidazole salts bearing N-phthalimidoethyl and benzyl moieties

Abstract

Abstract:Five novel benzimidazole salts ( 1 { 5 ) having N-phthalimidoethyl and 4-substituted benzyl were synthesized and identi ed by 1 H NMR, 13 C NMR, and IR spectroscopic methods and microanalysis. A mixture of the benzimidazole salts ( 1 { 5 ), Pd(OAc) 2 , and K 2 CO 3 in DMF-H 2 O catalyzed, in high yield, the Suzuki{Miyaura and the Heck{Mizoroki cross-coupling reactions assisted by microwave irradiation in 5 min. The novel benzimidazole salts ( 1 { 5 ), Pd(OAc) 2 , Cs 2 CO 3 , PEG, and Cu nanoparticles catalyzed, in high yield, the Sonogashira coupling reaction promoted by microwave irradiation in 10 min. The same benzimidazole salts ( 1 { 5 ), Pd(OAc) 2 , Cs 2 CO 3 , and TBAB catalyzed, in moderate or low yield, the Buchwald{Hartwig reaction assisted by microwave irradiation in 60 min. The efficiency of the catalyst system in these four reactions was discussed as well as the electron-releasing and withdrawing substituent effects on the benzimidazole ligands.