Poly supports phosphination

In 1993 Bergbreiter prepared two soluble polymer-supported phosphines that exhibited an inverse temperature-dependent solubility in water [52]. Although PEG-supported phosphine undergoes a phase-separation from water at 95-100 °C, the PEO-poly(propylene oxide)-PEO supported catalyst was superior as it is soluble at low temperatures and phase-separates at a more practical 40-50 °C. Treatment of a diphenylphosphinoethyl-terminated PEO-PPO-PEO triblock copolymer... 

Polybutenes, polymerization with metallocenes, 4, 1078 Poly(4-/< r/-butylstyrene) supports, phosphine-derived, for Pd complexes, 12, 679... 

Poly(acrylamide) and poly(acrylate) supports have been prepared and used in organic synthesis and catalysis. Water-soluble poly(Wisopropyl)acrylamide (PNIPAM) has been derivitized to prepare a supported phosphine onto... 

Living atom-transfer radical copolymerization (ATPR) of4-styryldiphenylpho-sphine (SDPP) with styrene was applied by Poli s group as a new method for the construction of polymer-supported phosphine ligands (Scheme 2.44) [142]. Copolymers with a statistical distribution of the monomers were obtained by means of CuBr/MegTREN as catalyst. Ethyl bromoisobutyrate was used as initiator. A small amount of CuBr2 was added to prevent a slower deactivation... 

This review has shown that the analogy between P=C and C=C bonds can indeed be extended to polymer chemistry. Two of the most common uses for C=C bonds in polymer science have successfully been applied to P=C bonds. In particular, the addition polymerization of phosphaalkenes affords functional poly(methylenephosphine)s the first examples of macromolecules with alternating phosphorus and carbon atoms. The chemical functionality of the phosphine center may lead to applications in areas such as polymer-supported catalysis. In addition, the first n-conjugated phosphorus analogs of poly(p-phenylenevinylene) have been prepared. Comparison of the electronic properties of the polymers with molecular model compounds is consistent with some degree of n-conjugation in the polymer backbone. 

Amphiphilic resin supported ruthenium(II) complexes similar to those displayed in structure 1 were employed as recyclable catalysts for dimethylformamide production from supercritical C02 itself [96]. Tertiary phosphines were attached to crosslinked polystyrene-poly(ethyleneglycol) graft copolymers (PS-PEG resin) with amino groups to form an immobilized chelating phosphine. In this case recycling was not particularly effective as catalytic activity declined with each subsequent cycle, probably due to oxidation of the phosphines and metal leaching. 

Asymmetric hydrogenations catalyzed by supported transition metal complexes have included use of both chiral support materials (poly-imines, polysaccharides, and polyalcohols), and bonded chiral phosphines, although there have been only a few reports in this area. 

The most straightforward way to obtain polymeric phosphonium salts involves introducing the phosphonio groups on to a suitable polymeric structure, for example by reacting tertiary phosphines with a poly(chloromethylstyrene) (reaction 99). The polymeric phosphonium salts obtained in this way are mostly used as polymer-supported phase-transfer catalysts for nucleophilic substitutions reactions under triphase conditions. 

Wentworth, P., Jr. Vandersteen, A. M. Janda, K. D. Poly (ethylene glycol) (PEG) as a Reagent Support The Preparation and Utility of a PEG-triaryl-phosphine Conjugate in Liquid-Phase Organic Synthesis (LPOS), Chem. Commun. 1997, 8, 759. 

Bimetallic complexes, such as RuPt(CO)5(PPh3)3, have been immobilized on phosphinated poly(styrene-divinyl-benzene) by a similar hgand-substitution reaction (equation 10). The resulting supported bimetallic complexes have been characterized by IR spectroscopy and are found to act as ethylene Hydrogenation catalysts. 

Some of the most widely studied organic reactions at this time are palladium catalysed carbon-carbon cross coupling reactions, which have been extensively investigated in water. For example, palladium catalysed Suzuki reactions can be performed in water in the presence of poly (ethylene glycol) (PEG). It should be noted that the PEG may be playing the role of a surfactant (PTC) and/or a support for the metal catalyst in water. Interestingly, in this example, no phosphine is needed and the products are easily separated and the catalyst phase reused. Unfortunately, diethyl ether was used to extract the product and as this solvent is hazardous (low flash point and potential peroxide formation), the overall process would be greener if an alternative solvent could be used. 

Poly(ethylene glycol) (PEG) was used as a soluble polymeric support in the efficient preparation of the 2-benzazepine 58 via a phosphine-free palladium-catalysed Heck reaction from 57 <06T10456>. 

Transition metal complexes can be immobilized on organic polymers such as polystyrene-divinylbenzene, polypropylene, poly (vinyl chloride), etc., as well as on the surface of inorganic oxides such as silica, y-Al203, glass, and molecular sieves (cf. Section 3.1.1.3). The metal complexes are attached to the supports via phosphine (-PR2), amine (-NR2) or other groups (-SH, -CN) linked to organic or inorganic support, e. g. Structures 1 and 2, where M = Pt, Rh, Pd, Ru, or Ni. 

Andersson [10 a, c] has used both acidic and basic polymeric supports based on phosphine-substituted poly(acrylic acid) (PAA) and poly(ethyleneimine) (PEI) respectively (polymer-bound ligands 4a, 4b and 5). In the latter case, presumably a branched dendritic PEI was employed, and the phosphine ligand was bound selectively to the multiple end groups. 

Other means of immobilizing ferrocenyl phosphine ligands include covalent see Covalent Bonds) attachment to either silica gel (see Siiica) or solid support poly (ethylene glycol) (TantaGel), or confinement within mesoporous MCM-41... 

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