Synthesis of glucopyranoside benzimidazolium-based ionic liquids for Pd-catalyzed aqueous Suzuki reaction

Several novel benzimidazolium-based ionic liquids (BzIm ILs) with free and acetyl protected glucopyranoside unit were synthesized and used as ligand for Pd-catalyzed environment-friendly Suzuki reaction. The BzIm ILs with the acetyl protection shows the highest activity, probably because the sugar has a large steric hindrance and acetyl groups can coordinate with Pd. The nuclear magnetic resonance spectra of Pd(OAc)₂/Glc-BzIm ILs free glucopyranoside indicate that Pd-C is formed. The Pd nanoparticles protected by ILs with a size of 5.3 (0.6) nm are considered to be real active species. A series of fluorene core arylfluorene derivatives were prepared with isolated yields above 90%.