Polymers Sonogashira reaction

Concerning other metals, Sonogashira coupling products have also been observed in the reaction of Ag(l)-carbenes [133] and Au(I)-supported carbenes [134] in low to moderate yields, but only under harsh conditions (more than 100°C). In this regard, NHC based catalysts for Sonogashira reactions have been supported on different materials that include clays [135], polymers [136] and peptides [137]. 

The suitability of the polymer-Hnker conjugate was examined for a variety of transformations, in particular Pd°-catalyzed reactions. For instance, the polymer-bound aryl iodide (63) was transformed quantitatively in a Heck reaction to a cinnamic acid ester (64) and to biphenyl (66) in a Suzuki reaction. It gave an alkyne (65) in a Sonogashira reaction (Scheme 10.12). 

The chemical structure of the polymers was confirmed by NMR and elemental analysis, and spectroscopically characterized in comparison with monodisperse low molecular weight model compounds. Scheme 5 outlines the approach to the model compounds. Model compounds 31-34 were synthesized by complexation of the ruthenium-free model ligands 29/30 with 3/4. The model ligands were synthesized in toluene/diisopropylamine, in a similar fashion as the polycondensation using Pd(PPh3)4 and Cul as catalyst (Sonogashira reaction) [34,47-49]. 

Jutand, A. Dual role of nucleophiles in palladium-catalyzed Heck, Stille, and Sonogashira reactions. Pure Appl. Chem. 2004, 76, 565-576. Li, C.-J., Slaven, W. T., John, V. T., Banerjee, S. Palladium catalyzed polymerization of aryl diiodides with acetylene gas in aqueous medium a novel synthesis of areneethynylene polymers and oligomers. Chem. Commun. 1997,1569-1570. 

SYNTHESIS OF 1 - [4-(2-PHEN YLETHYNYL)PHEN YL] ETHAN -1-ONE VIA SONOGASHIRA REACTION BY THE USE OF POLYMER-SUPPORTED PALLADACYCLE CATALYST... 

Yamamoto and Plenio introduced ferrocene units into PAEs and prepared redox-active PAEs 70 [107,109]. Yamamoto coupled l,l -diiodoferrocene to a diethynylarene by either a Sonogashira reaction or by utilizing alkynylgrignard reagents (Scheme 6.25). Plenio reported poly(l,3-ferrocenyleneethyny-lene)s 70d (Scheme 6.26) by a clever metallation strategy. Polymers 70 are structurally novel but have not found any applications. They might be useful as active layers in transistor-types due to their ease of oxidation. 

Scheme 9.10 Bis(pyrimidine)-based Pd-bound polymer 30 active in the Sonogashira reaction obtained by ring-opening metathesis polymerization (ROMP) of the norbornene 31 with the diene 32 and subsequent treatment with PdClj [110].

In 2007, Lee and coworkers reported the synthesis of a core-shell type polymer-supported (NHC)-Pd catalyst 28 (Figure 4.8), which was used to catalyze copper-free Sonogashira reactions under ambient atmosphere [39]. The... 

Finally, Fukase and coworkers have used the Sonogashira reaction to anchor glycoside moieties with a pendant acetylenic side chain to polymer-bound aryl iodides, forming a novel alkyne linker system [100]. 

Likewise, Hu, Fathi and coworkers have employed the Sonogashira reaction as a key step in the preparation of a 2,3-diarylbenzo[h]furan library [102]. Five different polymer-bound iodophenols were coupled with seven acetylenic compounds under Sonogashira conditions employing IRORl... 

Another palladium-catalyzed coupling reaction that has been successfully performed on soluble polymers is the Sonogashira coupling. Xia and Wang have presented an approach in which the PEG 4000 utilized simultaneously serves as polymeric support, solvent, and phase-transfer catalyst (PTC) in both the coupling and... 

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