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Palladium complexes of abnormal n-heterocyclic carbenes as precatalysts for the much preferred cu-free and amine-free sonogashira coupling in air in a mixed-aqueous medium

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Title Palladium complexes of abnormal n-heterocyclic carbenes as precatalysts for the much preferred cu-free and amine-free sonogashira coupling in air in a mixed-aqueous medium
 
Creator JOHN, A
SHAIKH, MM
GHOSH, P
 
Subject ring-opening polymerization
phenylene ethynylene oligomers
pd-peppsi-ipr
copper-free
aryl bromides
heterogeneous catalysis
coordination chemistry
acetylene derivatives
vibrational-spectra
terminal acetylenes
 
Description A series of new PEPPSI (Pyridine Enhanced Precatalyst Preparation Stabilization and Initiation) themed precatalysts of abnormal N-heterocyclic carbenes for the highly desirable Cu-free and amine-free Sonogashira coupling in air in a mixed-aqueous medium is reported. Specifically, the PEPPSI themed (NHC) PdI(2)(pyridine) type precatalysts, 1b-4b, efficiently carried out the highly convenient Cu-free and amine-free Sonogashira coupling of aryl bromides and iodides with terminal acetylenes in air in a mixed aqueous medium. Complexes, 1b-4b, were synthesized by the direct reaction of the corresponding imidazo[1,2-a] pyridinium iodide salts, 1a-4a, with PdCl(2) in pyridine in the presence of K(2)CO(3) as a base while the imidazo[1,2-a] pyridinium iodide salts, 1a-4a, were in turn synthesized by the alkylation reactions of the respective imidazo[1,2-a] pyridine derivatives with alkyl iodides. The density functional theory (DFT) studies revealed that these imidazol-3-ylidene[1,2-a] pyridine derived abnormal carbenes are strongly sigma-donating and consequently significantly weaken the catalytically important labile trans pyridine ligand in 1b-4b.
 
Publisher ROYAL SOC CHEMISTRY
 
Date 2011-10-15T06:43:49Z
2011-12-15T09:16:23Z
2011-10-15T06:43:49Z
2011-12-15T09:16:23Z
2009
 
Type Review
 
Identifier DALTON TRANSACTIONS,(47)10581-10591
1477-9226
http://dx.doi.org/10.1039/b913068c
http://dspace.library.iitb.ac.in/xmlui/handle/10054/13940
http://hdl.handle.net/100/3134
 
Language en