116470-54-3Relevant articles and documents
A study on applications of N-substituted main-chain NHC-palladium polymers as recyclable self-supported catalysts for the suzuki-miyaura coupling of aryl chlorides in water
Karimi, Babak,Fadavi Akhavan, Pari
, p. 6063 - 6072 (2011)
The preparation and characterization of a number of main-chain organometallic polymers (NHC-Pd MCOP) with different N-alkyl substituted groups such as benzyl (3a), n-hexyl (3b), and n-dodecyl (3c) are described. Among these polymers, 3c bearing the more lipophilic group n-dodecyl was found to be a more reactive and recoverable catalytic system in the Suzuki-Miyaura cross-coupling reaction of chloroarenes, including both deactivated and hindered aryl chlorides with different types of arylboronic acids under aqueous conditions. While the catalysts seem to be highly recyclable, on the contrary, we have provided much compelling evidence, such as kinetic monitoring, poisoning experiments, and average molecular weight determination before and after catalysis, that shows that the described organometallic polymers might be indeed the source of production of active soluble Pd species in the form of either Pd nanoparticles or fragmented NHC-Pd complexes. Our studies showed that in order to assess whether the catalysts are functioning in a heterogeneous pathway or they are simply a source of production of active Pd species, it is crucial to devise a suitable and highly efficient poison that could capture essentially soluble catalytic species. In this regard, we interestingly found that among a variety of well-known catalyst poisons such as Hg(0), SBA-15-PrSH, and cross-linked poly(4-vinylpyridine) (PVP), only PVP could efficiently quench catalysis, thus providing clear evidence of the formation soluble Pd species in our protocol. In addition, several experiments such as bright-field microscopy, dynamic light scattering (DLS) of the reaction mixture, and kinetic monitoring of the reaction at an early stage confirm not only that the described organometallic polymers could be a source of production of trace amounts of Pd nanoparticles but the capsular structures of these lipophilic polymers in water provides a means of entrapment of nanoclusters in a hydrophobic region, thus accelerating the reaction in pure water in the absence of any co-organic solvent.
Pyridyl-supported pyrazolyl-N-heterocyclic carbene ligands and the catalytic activity of their palladium complexes in Suzuki-Miyaura reactions
Zeng, Fanlong,Yu, Zhengkun
, p. 5274 - 5281 (2006)
Palladium complexes of two new types of unsymmetrical pyridyl-supported pyrazolyl-N-heterocyclic carbene ligands were synthesized and structurally characterized. A strategy to release the steric strain of the ligand was realized by the introduction of methylene linkers to the ligand molecule. All the palladium complexes exhibited good to excellent catalytic activity in Suzuki-Miyaura reactions of phenyl or p-tolylboronic acid with aryl halides including iodobenzene, aryl bromides, and activated aryl chlorides under mild conditions, revealing that the new ligands are promising for the construction of highly active transition-metal catalysts.
Microwave-assisted organic acid-base-co-catalyzed tandem Meinwald rearrangement and annulation of styrylepoxides
Shi, Yi,Li, Siqi,Lu, Yang,Zhao, Zizhen,Li, Pingfan,Xu, Jiaxi
, p. 2131 - 2134 (2020/02/27)
A novel organic acid-base-co-catalyzed conversion of styrylepoxides into [1,1′-biaryl]-3-carbaldehydes was realized under microwave irradiation. Styrylepoxides first underwent an acid-catalyzed Meinwald rearrangement followed by a tandem base-catalyzed Michael addition, aldol addition, and aromatization sequence to generate [1,1′-biaryl]-3-carbaldehydes.
Functionalised [(NHC)Pd(allyl)Cl] complexes: Synthesis, immobilisation and application in cross-coupling and dehalogenation reactions
Collinson, John-Michael,Wilton-Ely, James D.E.T.,Díez-González, Silvia
, p. 78 - 81 (2016/09/23)
A novel NHC–palladium(II) (NHC?=?N-heterocyclic carbene) complex and its immobilised version have been prepared and fully characterised. Optimisation studies led to good catalytic activities in Suzuki-Miyaura cross coupling and chloroarene dehalogenation reactions. Furthermore, the unexpected palladium-mediated transfer hydrogenation of a carbonyl compound is reported.
