Olefins dendrimer polymers

Ring-Opening Olefin Metathesis Polymerization (ROMP) Dendrimers Polymers That Look Like Trees Silicones Summing Up References Cited Other Reading... 

Olefin metathesis has become a very important reaction in polymer chemistry and natural product synthesis [47-49]. Garber et al. have used the physical properties of dendrimers in order to improve the separation between the dendritic metathesis catalyst and products on silica gel column chromatography [50]. The Van Koten group has reported on the synthesis of different generations of carbosilane dendrimers functionalized with ruthenium metathesis catalysts [51]. 

Water soluble polymers such as poly(enolato-co-vinyl alcohol-co-vinyl acetate) (PEW) act as polymeric ligands to Rh in the biphasic hydroformylation of olefins.170 Another type of polymeric ligands are phosphinated dendrimers, i.e., regularly branched polymers with an almost spherical morphology, which carry PPh2 substituents on the surface, suitable, e.g., for attaching ruthenium complexes.171... 

A few examples of polymer supported olefin metathesis have been reported recently. Hoveyda formed styrenyl ether complexes of several mthenium-based olefin metathesis catalysts that were then incorporated into a dendrimer stmcture (273) (Scheme 23), reporting good conversions over 6 cycles albeit with diminishing mthenium content. Yao used a similar chelating ligand to incorporate olefin... 

Another advantage of dendrimer-based catalysts concerns their easy recovery by stabilization at the surface of a polymer. The principal activities in dendritic catalysis lie in homogeneous catalysis, including Kharash addition of CC14 to methacrylate, palladium-catalyzed allylic alkylation, hydrogenation of olefins, hydroformylation, cyclopropanation, and oxidation.258 Dendrimers with redox-active cores have been proposed as promising materials for miniaturized information-storage circuits.259... 

Polymer-stabilized palladium nanoparticles (or nanoclusters) [125-127] have recently received increasing attention in the field of synthetic organic chemistry [128, 129]. Thus, for example, the poly(iV-vinyl-2-pyrrolidone) (PVP)-supported Pd particle catalyzed the Suzuki-Miyaura coupling in water [130]. Poly(amidoamine) (PAMAM) dendrimer-encapsulated palladium nanoparticles were designed and prepared to provide highly selective catalysts for hydrogenation of olefins [131-133]. Hyperbranched aromatic amides (aramids) and PS-DVB-methacryloylethylenesulfonic acid resin have also been... 

THE OLEFIN METATHESIS REACTIONS COMBINED WITH ORGANO-mON ARENE ACTIVATION TOWARDS DENDRIMERS AND POLYMERS... 

Figure 35).Another alternative to dendritic monomers involves the preparation of a dendritic core terminated in olefins which are available for metathesis with a catalyst s alkylidene such that the catalyst becomes incorporated at the ends of the dendrimer. From there, ROMP of monomers such as norbomene elongates the dendritic ends into linear arms to yield a star polymer with a dendritic core (Figure 36). Interestingly, prior to ROMP, the catalysts attached to the dendrimer reversibly dimerized at low temperatures and high concentrations. 

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