PEPPSI-type 2-methyl-2-propenyl-functionalized N-heterocyclic carbene-palladium complexes: Synthesis, structural characterization and catalytic activity on Suzuki-Miyaura reaction

摘要

N-Heterocyclic carbenes (NHCs) have been known to be efficient ligands for the Suzuki-Miyaura cross-coupling. In this work, four novel 2-methyl-2-propenyl substituted N-heterocyclic carbene ligands (1a-d) were synthesized and they were used to produce four novel air-stable PEPPSI-type palladium-NHC complexes (2a-d). All of the new compounds were fully characterized by elemental analysis, H-1, C-13 NMR and FT-IR spectroscopies. In addition, prepared complexes (2a-d) were investigated as catalysts in the Suzuki-Miyaura coupling reaction under very mild conditions using a mixture of i-PrOH/water as a solvent and a base at the room temperature. Under optimal reaction conditions, the expected biaryl products were obtained in moderate to high yields. (C) 2018 Elsevier B.V. All rights reserved.