Multifunctional cyclodextrin-based N,N-bidentate ligands for aqueous Heck arylation

Novel Pd(II) complexes coordinated by N,N-bidentate ligands derived from cyclodextrins have been synthesized by copper-catalyzed azide alkyne 1,3-cycloaddition (CuAAC). Depending on the nature of the N,N-bidentate ligand, fast or slow equilibriums between the free N,N-bidentate ligand and the Pd-species were detected by NMR measurements. The new Pd(II) complexes acted as efficient water soluble catalysts for the Heck reaction of aryl iodides in aqueous medium. The reaction could tolerate aerobic conditions and affords the coupling products in good yields. Once the reaction was complete, the product and the catalyst could be recovered separately by simple decantation. (C) 2014 Elsevier B.V. All rights reserved.