Polystyrene-supported copper

Polystyrene-supported copper(I) chloride exhibits rapid and reversible adsorption of carbon monoxide 109). For the adsorbent prepared by using toluene as solvent, the equilibrium molar ratio of adsorbed CO to the charged copper(I) chloride is 0.83 at 20 °C under 1 atm. 

A heterogeneous source of copper, the well-characterized, strongly basic, copper-exchanged fluorapatite (CuFAP), is formed as the (mainly) Cu(II) species from Caio(P04)6(F)2 upon treatment with Cu(OAc)2. CuFAP mediates displacement of all aryl halides (F, Cl, Br, I) in DMF (X = F, Cl) or DMSO (X = Br, I), as shown below (Eqn. 1-6). Less basic CHAP [from Caio(P04 (OH)2 + Cu(OAc)2], Cu(OAc)2, CuI alone, or Cu powder are inactive. Interestingly, in 3-chloro-4-fluoronitrobenzene, the C-F bond reacts selectively with imidazole in high yield (85%, isolated). Polymer-supported copper (1) and copper (II) on polystyrene have both been shown usefUl for arylations of anilines and heteroaromatics with boronic acids. 

Given the utility of chiral Cu(II)/bisoxazoline complexes in enantioselective Mukaiyama aldol reactions, a number of reports detailing the development of polymer-bound or dendritic bisoxazoline copper (I I) complexes have been developed. Development of such catalyst systems provides the potential for easy recovery and reuse of the relatively expensive catalyst. To this end, Salvadori and CO workers reported Mukaiyama aldol addition of ketene thioacetal (57) to methyl pyruvate catalyzed by a Cu(OTf)2 complex of polystyrene-supported bisoxazoline (89) (Scheme 17.18) [23]. The enantioselectivity of the addition remained high over eight cycles of the catalyst, however, reactivity was gradually reduced over time. 

Vinylations and arylations of polystyrene-bound 2-bromofurans have been accomplished by treatment with stannanes [98] or boronic acids [99] in the presence of palladium complexes. Alternatively, 2-furylstannanes can be coupled with support-bound aryl iodides or bromides in the presence of palladium or copper complexes (Entries 5-7, Table 15.8). 

The resulting triazoles can be N-alkylated by treatment with alkyl halides (0.25 mol/L, 30 equiv., DMF, NaOH), but mixtures of the 1-alkylated and 2-alkylated triazoles are obtained [255]. 1,2,4-Triazoles have also been prepared from N-amino-amidines (amidohydrazones Entry 4, Table 15.20), which were prepared from resin-bound thioamides by S-alkylation with methyl triflate followed by treatment with hydrazine [256]. 1,2,4-Tri azoles undergo Michael addition to polystyrene-bound a-acetamido acrylates to yield triazole-derived a-amino acids (Entry 7, Table 15.20). Benzotriazoles have been N-arylated on insoluble supports by treatment with aryl-boronic acids in the presence of catalytic amounts of copper salts (Entry 8, Table... 

Immobilized catalysts have been studied in metal-catalyzed living radical polymerization for, in part, easy removal of the catalysts from the products. In most examples, the catalytic metal centers are attached to solid supports, such as silica gel and polystyrene beads, via spacers and/or coordinating ligands (Figure 7). The central metals thus far employed include copper and ruthenium. 

An early example of a Diels-Alder reaction catalyzed by a polymer-supported Lewis acid involves the use of copper-loaded polystyrene-based polymers in the reaction of furan with 2-cyanoacrylonitrile [41]. Nafion-supported scandium... 

The applications reported for polymer-supported, soluble oxidation catalysts are the use of poly(vinylbenzyl)trimethylammonium chloride for the autooxidation of 2,6-di-tert-butylphenol [8], of copper polyaniline nanocomposites for the Wacker oxidation reaction [9], of cationic polymers containing cobalt(II) phthalocyanate for the autooxidation of 2-mercaptoethanol [10] and oxidation of olefins [11], of polymer-bound phthalocyanines for oxidative decomposition of polychlorophenols [12], and of a norbornene-based polymer with polymer-fixed manganese(IV) complexes for the catalytic oxidation of alkanes [13], Noncatalytic processes can also be found, such as the use of soluble polystyrene-based sulfoxide reagents for Swern oxidation [14], The reactions listed above will be described in more detail in the following paragraphs. 

Sajiki et al. [43] developed a copper catalyst supported on DIAION CRll and DIAION CR20. These are actually polystyrene-divinylbenzene-based polymers possessing iminodiacetic acid moieties and polyamine moieties which... 

Two main approaches using HPLC are (1) covalent bonding of chiral ligands (which can complex copper (II) ions) to solid supports (such as polystyrene and polyacrylamide) and resolution of amino acids by eluting with a mobile phase containing copper (II) ions (2) introduction of chirality into the mobile phase. Metal ions such as Cu(ll), Zn(n), Co(II), and Mg(II), in conjunction with chiral ligands are added to the mobile phase. Thus, a Cu(n)-L proline complex as the chiral additive can be operated in conventional cation-exchange resin. 

Ayres, N., Haddleton, D.M., Shooter, A.J., and Pears, D.A. 2002. Synthesis of hydrophilic polar supports based on poly(dimethylacrylamide) via copper-mediated radical polymerization from a cross-linked polystyrene surface Potential resins for oligopeptide solid-phase synthesis. Macromolecules 35 3849-55. 

---