Heck reaction catalysed by palladium supported with an electron-rich benzimidazolylidene generated in situ: remarkable ligand electronic effects and controllable mono- and di-arylation
作者:Gang Zou、Wen Huang、Yuanjing Xiao、Jie Tang
DOI:10.1039/b601833e
日期:——
The Heckreactions of arylbromides and chlorides are efficiently catalysed by palladium supported with benzimidazolylidenes generated in situ from N,N-dialkylbenzimidazolium salts in molten tetrabutylammonium bromide (TBAB) as ionic liquid reaction medium. Remarkable electronic effects from the benzimidazoliums on the catalysis have been observed. Reaction of 4-chloroacetophone with butyl acrylate
Palladium complexes of o-xylylene-linked alkoxybenzimidazolin-2-ylidenes containing aryl N-substituents: examples of C–H activation and the formation of a tri-nuclear palladium complex
作者:Peter V. Simpson、David H. Brown、Brian W. Skelton、Allan H. White、Murray V. Baker
DOI:10.1007/s10847-015-0515-x
日期:2015.6
Palladium complexes of new bidentate N-heterocyclic carbene (NHC) incorporating benzimidazolin-2-ylidene units have been synthesized and structurally and spectroscopically characterised. The NHC ligands are furnished with aryl substituents on the nitrogen atoms and electron-donating butoxy groups on the benzo-fused ring. The incorporation of these aryl substituents on the bis(NHC) ligands leads to interesting and unexpected conformations around the palladium atoms, and interesting reactivity, including cyclometallation and the formation of a tri-nuclear species. One of the complexes has been studied in an initial series of Mizoroki–Heck and Suzuki–Miyaura cross-coupling reactions but shows moderate to poor activity.
Synthesis and Characterisation of (Alkoxybenzimidazolin‐2‐ylidene)palladium Complexes: The Effect of Ancillary Ligands on the Behaviour of Precatalysts
作者:Murray V. Baker、David H. Brown、Peter V. Simpson、Brian W. Skelton、Allan H. White
DOI:10.1002/ejic.200801154
日期:2009.5
A series of new N-heterocyclic carbene (NHC)–palladium(II) complexes bearing electron-rich benzimidazolin-2-ylidene ligands are described and structurally and spectroscopically characterised. These (benzimidazolin-2-ylidene)palladiumcomplexes bear butoxy groups to increase the solubility and perhaps influence the catalytic activity by increasing the electron density around the metal centre. The effect
Azolium-Linked Cyclophanes: Effects of Structure, Solvent, and Counteranions on Solution Conformation Behavior
作者:Murray V. Baker、David H. Brown、Charles H. Heath、Brian W. Skelton、Allan H. White、Charlotte C. Williams
DOI:10.1021/jo801860d
日期:2008.12.5
of some xylyl-linked imidazolium and benzimidazolium cyclophanes decorated with alkyl or alkoxy groups. The addition of alkyl/alkoxy chains to the cyclophanes allows for studies in chlorinated solvents, whereas previous solution studies of azolium cyclophanes have generally required highly polar solvents. The azolium cyclophanes may exist in a syn/syn conformation (azolium rings mutually syn, arene rings
Synthesis and Characterisation of Mono‐ and Bidentate Alkoxybenzimidazolin‐2‐ylidene Palladium Complexes: Interesting Solution Behaviour and Application in Catalysis
作者:Peter V. Simpson、Brian W. Skelton、David H. Brown、Murray V. Baker
DOI:10.1002/ejic.201001318
日期:2011.4
catalysts. The two types of palladiumcomplexes presented, which possess either a bidentate bis(NHC) or a mixed NHC/allyl ligand system, demonstrate significantly different activities in the Mizoroki–Heck cross-coupling reactions but similar activities in the Suzuki–Miyaura and Buchwald–Hartwig reactions. Interestingbehaviour of the mixed NHC/allyl palladiumcomplexes in solution has been investigated.