The Influence of Imidazolylidene Ligands with Bulky Resorcinarenyl Substituents on Catalysts for Suzuki-Miyaura Coupling
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, no.7, pp.1115-1120, 2016 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Volume: Issue: 7
- Publication Date: 2016
- Doi Number: 10.1002/ejic.201501238
- Journal Name: EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
- Page Numbers: pp.1115-1120
- Keywords: Calixarenes, Cavitands, N-Heterocyclic carbenes, Palladium, Cross-coupling, IMIDAZOLIUM SALTS, EFFICIENT LIGANDS, CROSS-COUPLINGS, ARYL CHLORIDES, COMPLEXES, BIARYLS, PRECURSORS
- Inonu University Affiliated: Yes
Abstract
PEPPSI-type imidazolylidene palladium complexes having their carbenic ring N-substituted with an aryl ring and a cavity-shaped unit [25,26,27,28-tetrapropyloxycalix[4]aren-5-yl or 6(10),12(16),18(22)-tetramethylenedioxy-2,8,14,20-tetrapentylresorcin[4]aren-5-yl (TPR)] have been prepared and assessed in Suzuki-Miyaura cross-couplings. Remarkable efficiency in the coupling of aryl chlorides with sterically hindered arylboronic acids was observed for the carbene ligand having its N atoms (N1, N2) substituted by a mesityl and a TPR group, respectively. This good performance possibly arises from strong steric interactions between the pentyl-substituted cavitand unit and the catalytic centre, which favours reductive elimination. Two of the imidazolium salts used for complex synthesis were characterised by X-ray diffraction analysis.