The Use Of Poly(Ethylene Glycol) In The Palladium-catalyzed Coupling Reactions

In this thesis, study on the use of poly(ethylene glycol) in the palladium-catalyzedcoupling reactions, the synthesis, characterization and crystal structures of a series ofnew N-Heterocyclic carbenes adducts of palladacycles were reported. Thesecomplexes have been successfully used in palladium-catalyzed coupling reactions ofaryl bromides and aryl chlorides. The use of5－PEG(10000) and12－PEG(10000) ascatalysts for α-arylation of ketones was examined.1. Ten new N-Heterocyclic carbenes adducts of palladacycles and5－PEG(10000)and12－PEG(10000) have been easily prepared and well characterized by elementalanalysis, IR spectra, ESI-MS,1H NMR and single-crystal X-ray analysis. 2. The use of these N-Heterocyclic carbenes adducts of palladacycles3and4ascatalysts for Heck reactions was examined.4was found to be very efficient for theHeck reaction of a range of aryl bromides with acrylic acid ethyl ester although theywere not particularly useful for the activation of aryl chlorides.3. The use of these N-Heterocyclic carbenes adducts of palladacycles2and5ascatalysts for Suzuki reactions and C-N bond forming reaction was examined. Typically,using0.5-1mol%of catalyst in the presence of3equivalents of KtOBu as base inPEG-400[poly(ethylene glycol-400)] at120oC provided coupling products inexcellent yields. Moreover, the5/PEG-400system could be recycled and reused threetimes without any loss of catalytic activity.4. The use of these N-Heterocyclic carbenes adducts of palladacycles9and12ascatalysts for α-arylation of ketones with aryl chlorides was examined. Typically, using1mol%of catalyst in the presence of1.5equivalents of KtOBu as base in dioxane at100oC provided coupled products in good yields. The use of5－PEG(10000) and12－PEG(10000) as catalysts for α-arylation of ketones was examined. The abovesystem could be recycled.