These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Air-stable, convenient to handle Pd based PEPPSI (pyridine enhanced precatalyst preparation, stabilization and initiation) themed precatalysts of N/O-functionalized N-heterocyclic carbenes and its utility in Suzuki-Miyaura cross-coupling reaction.
    Author: Ray L, Shaikh MM, Ghosh P.
    Journal: Dalton Trans; 2007 Oct 28; (40):4546-55. PubMed ID: 17928912.
    Abstract:
    Several new air-stable, convenient to handle and easily synthesized Pd based PEPPSI (Pyridine Enhanced Precatalyst Preparation, Stabilization and Initiation) type precatalysts supported over N/O-functionalized N-heterocyclic carbenes (NHC) namely, trans-[1-(benzyl)-3-(N-t-butylacetamido)imidazol-2-ylidene]Pd(pyridine)Cl2 (), trans-[1-(2-hydroxy-cyclohexyl)-3-(benzyl)imidazol-2-ylidene]Pd(pyridine)Cl2 () and trans-[1-(o-methoxybenzyl)-3-(t-butyl)imidazol-2-ylidene]Pd(pyridine)Br2 (), have been designed. Specifically, the Pd-NHC complexes, , and , were conveniently synthesized from their respective imidazolium halide salts by the reaction with PdCl2 in pyridine in presence of K2CO3 as a base. A new imidazolium chloride salt, 1-(benzyl)-3-(N-t-butylacetamido)imidazolium chloride () was synthesized by the alkylation reaction of benzyl imidazole with N-t-butyl-2-chloroacetamide. The molecular structures of the imidazolium chloride salt, , and the Pd-NHC complexes, , and , have been determined by X-ray diffraction studies. The density functional theory studies of the , and complexes were carried out to in order to gain insight about their structure, bonding and the electronic properties. The nature of the NHC-metal bond in these complexes was examined using Charge Decomposition Analysis (CDA), which revealed that the N-heterocyclic carbene ligands are effective sigma-donors. In addition, the catalysis studies revealed that the Pd-NHC complexes, , and , are effective catalysts for the Suzuki-Miyaura type C-C cross-coupling reactions.
    [Abstract] [Full Text] [Related] [New Search]