Palladium complexes of the N-fused heterocycle derived abnormal N-heterocyclic carbenes for the much-preferred Cu-free and the amine-free Sonogashira coupling in air
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Title |
Palladium complexes of the N-fused heterocycle derived abnormal N-heterocyclic carbenes for the much-preferred Cu-free and the amine-free Sonogashira coupling in air
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Creator |
JOHN, A
MODAK, S MADASU, M KATARI, M GHOSH, P |
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Subject |
Palladium
Abnormal N-heterocyclic carbene (NHC) Sonogashira reaction Cu-free Amine-free DFT studies COPPER-FREE SONOGASHIRA RING-OPENING POLYMERIZATION CHARGE DECOMPOSITION ANALYSIS TRANSITION-METAL-COMPLEXES MIXED AQUEOUS-MEDIUM SET MODEL CHEMISTRY RHODIUM COMPLEXES HECK ALKYNYLATION ARYL HALIDES HETEROGENEOUS CATALYSIS |
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Description |
Abnormal N-heterocyclic carbenes of the N-fused heterocycles were employed in stabilizing a series of PEPPSI (Pyridine Enhanced Precatalyst Preparation Stabilization and Initiation) themed complexes of the type (abnormal-NHC)Pdl(2)(pyridine). Specifically, imidazo[1,2-a]pyridine based abnormal complexes, trans-{(1-ethyl-2-(4-R-phenyl)-imidazol-3-ylidene[1,2-a]pyridine)}Pdl(2)(pyridine) [R= F (1b), Cl (2b), Br (3b) and Me (4b)] were synthesized from the reaction of corresponding imidazo[1,2-a]pyridinium iodide salts (1-4)a with PdCl2 in pyridine in the presence of K2CO3 as a base. The (1-4)b complexes carried out the Sonogashira couplings of the aryl bromide and iodide substrates with terminal alkynes in a mixed aqueous medium in air under the Cu-free and amine-free conditions. The density functional theory studies revealed that in the (1-4)b complexes, the C-carbene-Pd sigma-bonding interaction was significantly stronger than the trans Pd-N-pyridine sigma-bonding interaction. (C) 2013 Elsevier Ltd. All rights reserved.
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Publisher |
PERGAMON-ELSEVIER SCIENCE LTD
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Date |
2014-10-16T12:27:35Z
2014-10-16T12:27:35Z 2013 |
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Type |
Article
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Identifier |
POLYHEDRON, 6420-29
http://dx.doi.org/10.1016/j.poly.2013.01.062 http://dspace.library.iitb.ac.in/jspui/handle/100/15545 |
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Language |
en
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