PEG化的聚合物载体树脂研究进展

组合化学已成为发现和优化新药、亲和配体和催化过程中的重要组成部分.高分子载体树脂在组合化学中起着关键的作用,各种类型的聚合物树脂在有机合成中已被广泛开发为载体、反应物和催化剂.与传统的Merrifield树脂相比较,聚乙二醇(PEG)化的聚合物树脂具有与极性溶剂更好的相容性、更高的溶剂吸收和溶胀性能.本文主要综述与PEG相关联的聚合物树脂在有机合成载体领域中的最新成果.     

Phosphine-functionalised polymer resins as Pd scavengers

Three phosphine-functionalised polymer resins were used as scavengers of palladium catalysts from Buchwald-Hartwig aryl amination reactions. The purity of the products was assessed, and residual palladium analysed by ICP-AES. Scavenging efficiencies of up to >98.5% were demonstrated.     

Epoxy resins cured with ionic liquids as novel supports for metal complex catalysts

In this work, the application of an epoxy resin cured with ammonium ionic liquids as a support for palladium complex catalyst is reported. Supports based on epoxy resin were obtained as a result of the use of ionic liquids: didecyldimethylammonium tetrafluoroborate [d₂m₂am][BF₄], 1-methyltheobromine tetrafluoroborate [mthb][BF₄], didecyldimethylammonium theobrominate [d₂m₂am][thb], didecyldimethylammonium theophyllinate [d₂m₂am][thp] as cross-linking agents. The characterization of polymeric supports and heterogenized palladium catalysts has involved research methods like time-of-flight secondary ion mass spectrometry (TOF-SIMS), infrared spectroscopy (IR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS). The activity and stability during long-term use of the investigated catalytic systems were tested in a model Heck reaction. The influence of the type of ILs used as epoxy hardeners on the catalytic properties of epoxy-supported palladium catalysts is discussed.     

Metal-catalyzed radical polyaddition as a novel polymer synthetic route

A new class of polymerizations was developed via metal-catalyzed C-C bond forming radical polyaddition; the monomers were designed to have a reactive C-Cl bond, which can be activated by the metal catalysts to generate a carbon radical species, along with a C=C double bond, to which the carbon radical generated from another molecule adds to form a C-C backbone polymer with an inactive C-Cl pendant.     

Uniform polymer in synthetic polymer chemistry

The preparation of uniform polymers and their use in fundamental polymer chemistry are reviewed. A typical method of preparation is a combination of living polymerization and supercritical fluid chromatography separation. Synthetic uniform polymers allow us to solve ambiguous problems in polymer chemistry due to molecular weight distribution and are of significant importance for studies on structure–property relationships. A close inspection of an isotactic uniform chloral oligomer with a symmetrical chemical structure reveals that oligomers are the first examples of stable atropisomers of aldehyde oligomers and that their chiroptical properties are due only to their helical geometries. A molecular-level understanding of the mechanism and stoichiometry of the association process of polymer molecules is possible only with uniform polymers, and stereocomplex formation between isotactic and syndiotactic poly(methyl methacrylate)s in acetone has vigorously been studied by size exclusion chromatography (SEC) and NMR. End-functionalized uniform polymers have enabled us to prepare uniform polymer architectures, such as block, graft, comb, and star polymers. A uniform stereoblock poly(methyl methacrylate) with an isotactic (methyl methacrylate)₄₆-syndiotactic (methyl methacrylate)₄₆ structure shows a single SEC peak in chloroform but three peaks in acetone, which are ascribable to intermolecularly and intramolecularly associated complexes and nonassociated molecules. A three-arm star polymer with one isotactic chain and two syndiotactic chains shows a peculiar SEC behavior in acetone due to a braid type of intramolecular stereocomplex formation. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 416–431, 2004     

Functionalized cross-linked poly(vinyl alcohol) resins as reaction scavengers and as supports for solid-phase organic synthesis

New hydrophilic poly(vinyl alcohol) (PVA-OH) resins were prepared by an inverse suspension polymerization using epichlorohydrin as a cross-linker. These novel resins swell in a variety of solvents commonly used in solid-phase organic synthesis, such as dicholomethane, dioxane, methanol, tetrahydrofuran, and dimethylformamide. In addition, PVA-OH shows excellent swelling in water. The cross-linked PVA-OH beads were functionalized with an aldehyde group and were tested as scavengers for primary amines in three different reactions: amide bond formation, reductive amination reaction, and urea formation. With 1-2 equiv of the PVA aldehyde resin, all the excess primary amines were successfully scavenged. The utility of PVA-OH resins as solid supports in mono- and dipeptide synthesis was also investigated using symmetrical anhydride and MSNT/MeIm (2,4,6-mesitylenesulfonyl-3-nitro-1,2,4-triazolide in the presence of 1-methylimidazol) methods.     

Micelle-derived polymer supports for enantioselective catalysts

The BINOL moieties are successfully immobilized on the surface of a micelle-derived polymer. Ti-BINOLate complexes prepared from the polymer with Ti(O-i-Pr)₄ exhibited high catalytic activity for the asymmetric alkylation of benzaldehyde with Et₂Zn to afford the adduct in up to 96% yield with 84% ee.     

Immobilization of synthetic glycopeptides on polymeric supports

The synthesis of the 6-aminohexyl -glycoside of O-(N-acetylglucosaminyl)-(14)-MDP (GMDP) is described. Conjugates with polyacrylamide, including lipophilic conjugates (containing phosphatidylethanolamine residues) and biotinylated polymeric probes with MDP specificity have been obtained on the basis of -spacered glycopeptides. Conjugates of MDP with dextran have also been synthesized.Simferopol' State University, 4 Yaltinskaya ul., Simferopol', Crimea, Ukraine. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 104–111, January–February, 1998.     

Large uniform-sized polymer beads for use as solid-phase supports prepared by ascension polymerization

Large uniform-sized polymer beads are desirable for "one-bead-one-compound" applications in the combinatorial synthesis of compound libraries. We have developed a technique for the preparation of large polymer spheres with narrow size distributions. Uniform-sized poly(styrene-co-divinylbenzene) beads with diameters in excess of 1 mm have been prepared by free radical polymerization in an ascension process through a heated column. The size of the beads can be adjusted by the diameter of the injection needle and the injection speed. The resin beads can be made porous by the incorporation of a porogen during the preparation; they reach a specific surface area in excess of 200 m(2)/g. The mechanical properties of the spheres and their use in organic synthesis have been studied.     

Preparation and characterization of azlactone functionalized polymer supports and their application as scavengers

A series of cross-linked porous copolymer supports based on N-(p-vinylbenzoyl)-2-methylalanine (VBM), styrene and divinylbenzene was prepared by aqueous suspension copolymerization in the presence of butan-2-ol used as porogen. The cross-linked copolymer beads were characterized by elemental analysis, scanning electron microscopy (SEM), FT-IR and confocal Raman spectrometries. It was observed that the VBM incorporation was effective and homogeneous within the beads. Those VBM functionalized supports were converted into azlactone functionalized supports using acetic anhydride and their scavenging efficiency towards different amines was measured. It appeared that 90% of benzylamine was quenched after 5 h.     

Synthetic resins as designable supports for metal-based chemistry: The issue of their nanomorphology and molecular accessibility

Macromolecular cross-linked ligands containing pyridyl pendant groups are characterized by a combination of inverse steric exclusion chromatography, ESR and NMR spectrometries in water and methanol. On the basis of the relevant results, methanol is seen to be clearly the best swelling agent and it is chosen as medium for Cu^II coordination.     

The biodeterioration of synthetic resins used in conservation

Synthetic resins have been extensively employed by artists in their works of art, e.g. as paint binders, or by conservators for conservation treatments, e.g. as stone consolidants and protectives. It is generally thought that synthetic resins are less prone to chemical, physical and biological deterioration than other organic products but there are many articles in the scientific literature and some reports in the conservation of cultural heritage literature claiming that microorganisms are capable of degrading synthetic resins. This paper reviews the researches on the biodeterioration of synthetic resins used in the conservation of cultural heritage, including stone, painting and textile materials, carried out in the last fifty years.     

Photoconductivity of synthetic dopa-melanin polymer

The photoconductivity effect in synthetic dopa-melanin polymer with relation to the charge hopping conduction has been investigated. Measurements of the rise and decay of photocurrents upon visible radiation (400-800 nm) and at temperatures of 293-326 K allowed the determination of the major trapping levels as follows: 56, 35 and 26 kJ/mol. Spectral response of the steady-state photocurrent in the range 367-1100 nm showed significant departures from the absorption spectrum of melanin. The high concentration of traps or recombination centers can explain the long time-constants calculated from the photocurrent rise and decay curves. The results obtained can support the postulated earlier polarons and hopping model of conductivity in synthetic dopa-melanin.     

Development of new acid-functionalized resins for combinatorial synthesis on solid supports

New methods for the synthesis of acid-functionalized polystyrene and TentaGel resins are described; these methods serve to overcome problems with currently available resins and will be instrumental in spurring the use of carboxylic acid resins in solid phase chemistry.     

Polystyrene resins cross-linked with di- or tri(ethylene glycol) dimethacrylates as supports for solid-phase peptide synthesis

Polystyrene resins cross-linked with di(ethylene glycol) dimethacrylate (DEGDMA) and tri(ethylene glycol) dimethacrylate (TEGDMA), DEGDMA-PS and TEGDMA-PS, were synthesized by suspension copolymerization. Four functionalized resins, chloromethyl resin, 4-hydroxymethylphenoxymethyl resin (Wang resin), 4-methylbenzhydrylamine resin (MBHA resin) and 2-chlorotrityl chloride resin, were prepared from DEGDMA-PS and TEGDMA-PS. DEGDMA-PS and TEGDMA-PS showed high reactivity in the functionalization reactions in comparison with Merrifield resin (polystyrene cross-linked with divinylbenzene, DVB-PS). DEGDMA-PS-Wang resin and TEGDMA-PS-Wang resin were used as the solid-phase support for the synthesis of a difficult sequence, the fragment of acyl carrier protein 65-74. The yields of the crude peptide synthesized using DEGDMA-PS-Wang resin, TEGDMA-PS-Wang resin and DVB-PS-Wang resin were 92.3%, 91.6% and 78.8%, respectively. The purities of the crude peptides were 85.7%, 88.1% and 73.3%, respectively.     

Reactivity of ester groups on insoluble polymer supports

A study was made of the comparative rates of reaction of active ester functional groups (p-nitrophenyl and 2,4-dinitrophenyl esters) situated on three types of insoluble support polymers and on small, soluble analogs of the polymer molecules. The supports consisted of a styrene—divinylbenzene bead-type polymer (2% DVB), a styrene—divinylbenzene popcorn polymer (0.2% DVB), and a popcorn polymer with 2,3-dimethylbutadiene and substituted styrene units in the chain. p-Nitrophenyl benzoate and 2,4-dinitrophenyl p-isopropylbenzoate were used as soluble analogs. Rates of aminolysis by small molecules (2-aminoethanol and n-tetradecylamine) in pyridine and of solvolysis in alcohols catalyzed by both small (N-methylimidazole) and large (polyvinylimidazole) molecules were determined. With the small amines, finely divided particles of popcorn and bead type styrene polymers reacted at about the same rate, which was approximately 1/5 the rate of reaction of the homogeneous analogs. With a high molecular weight reagent, polyvinylimidazole, the heterogeneous reactions were much slower and the popcorn polymer reacted faster than the bead polymer. In catalyzed solvolyses, the styrene popcorn derivative reacted faster in benzyl alcohol and slower in 1-hexanol than the dimethylbutadiene popcorn polymer derivatives.