Synthesis and catalytic activities of $Pd^I^I$–phosphine complexes modified poly(ether imine) dendrimers

Krishna, Thatavarathy Rama and Jayaraman, Narayanaswamy (2004) Synthesis and catalytic activities of $Pd^I^I$–phosphine complexes modified poly(ether imine) dendrimers. In: Tetrahedron, 60 (45). pp. 10325-10334.

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Abstract

In this paper, we report synthesis of new alkyldiphenyl phosphine ligand modified poly(ether imine) dendrimers up to the third generation. The phosphinated dendrimers were obtained by functional group transformations of the alcohols present at the periphery of the dendrimers to chloride, followed by phosphination using $LiPPh_2.$ The modification at the peripheries of the dendrimers was performed successfully to obtain up to 16 alkyl diphenylphosphines in the case of a third generation dendrimer, in good yields for each individual step. After phosphination, dendritic ligands were complexed with $Pd(COD)Cl_2$ to give dendritic phosphine–$Pd^{II}$ complexes. Both the ligands and the metal complexes were characterized by spectroscopic and spectrometric techniques including high-resolution mass spectral analysis for the lower generations. Evaluation of the catalytic efficacies of the dendrimer–$Pd^{II}$ metal complexes in mediating a prototypical C–C bond forming reaction, namely the Heck reaction, was performed using various olefin substrates. While the substrate conversion lowered with catalyst in the order from monomer to third generation dendrimer, the second and third generation dendrimers themselves were found to exhibit significantly better catalytic activities than the monomer and the first generation dendrimer.

Item Type:	Journal Article
Publication:	Tetrahedron
Publisher:	Elsevier
Additional Information:	The copyright of this article belongs to Elsevier.
Keywords:	Catalysis;Dendrimers;Heck coupling;Phosphine ligands;Palladium(II) complexes.
Department/Centre:	Division of Chemical Sciences > Organic Chemistry
Date Deposited:	10 Apr 2006
Last Modified:	19 Sep 2010 04:25
URI:	http://eprints.iisc.ac.in/id/eprint/6177

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