共查询到20条相似文献,搜索用时 15 毫秒
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Poly(vinylpyrrolidone) (PVP) has solubility properties that make it an attractive material for polymer-assisted synthesis applications; however, the naked polymer lacks reactive groups upon which to do chemistry. Furthermore, large differences in radical reactivity between 1-vinylpyrrolidin-2-one (NVP) and most other monomers lead to compositional drift during copolymerization, further complicating the introduction of functional groups into the polymer using this method. Monomers that are derivatives of NVP itself are expected to show smaller differences in radical reactivity and therefore provide a way of preparing PVP with adjustable properties. Three monomers introducing hydroxyl-functional groups and a new cross-linker, all derivatives of NVP, were synthesized and used in the preparation of a new type of hydrophilic polymer beads by aqueous suspension polymerization. These lightly cross-linked beads contain hydroxyl groups at a functional loading of 0.21-0.29 mmol/g and swell extensively in a broad range of solvents. 相似文献
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De Luca L Giacomelli G Porcheddu A Salaris M Taddei M 《Journal of combinatorial chemistry》2003,5(4):465-471
The synthesis of libraries of substituted pyrazoles and isoxazoles has been developed via in situ generation of polymer-bound enaminones. The synthetic protocol makes use of commercially available aniline cellulose, a low-cost and versatile biopolymer, under very mild conditions. This new support allowed us to carry out reactions in polar solvents under both conventional heating and MW irradiation without degradation of the polymer. The reaction between cellulose-bound enaminone and hydroxylamine or hydrazines to afford the target heterocycles in high yields directly in solution is the key step. The support can be conveniently recycled. 相似文献
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Matthew Kwok Wai Choi 《Tetrahedron》2004,60(12):2875-2879
A new cross-linked polystyrene-supported thioanisole reagent is reported. This reagent incorporates the flexible JandaJel™ cross-linker and can be treated with methyl trifluoromethanesulfonate to form the corresponding sulfonium salt. This salt can in turn be deprotonated to form a polymer-supported sulfur ylide that is able to react with aldehydes and ketones to form epoxides. The thioanisole reagent can also be oxidized to form an insoluble sulfoxide reagent that is useful in Swern oxidation reactions. In these reactions, the polymer-supported thioanisole-based reagents can be recovered, regenerated and reused. 相似文献
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Triazenes (RN=N-NR'R") are a class of compounds that hold much promise in preparative chemistry as they are reactive groups which are both stable and adaptable to numerous synthetic transformations. Useful to scientists in pharmacology, total synthesis, polymer technology, and the construction of novel ring systems, to name a few areas, triazenes also have a tendency to surprise chemists with new reactions and increasing applicability. This review highlights some of the recent advances and diversity possible with these types of systems. 相似文献
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Jacqueline Ficini 《Tetrahedron》1976,32(13):1449-1486
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Boschetti F Denat F Espinosa E Guilard R 《Chemical communications (Cambridge, England)》2002,(4):312-313
Selectively functionalised tetraazacycloalkanes are obtained from the open-chain tetraamine by using a bisaminal moiety acting both as a template agent and as a N-protecting group. 相似文献
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The concepts and use of "volatilizable" solid supports are presented. Such supports, which are completely removed by volatilization following decomposition, improve the efficiency of the solid-phase synthesis of both individual and mixtures of low-molecular weight acyclic and heterocyclic compounds as well as peptides, peptidomimetics, and protected peptide fragments. The "volatilizable" silica-based solid supports and linkers used to illustrate this concept were found to be completely removed by their decomposition and ultimate "volatilization" during the final cleavage step of synthetic process to yield solely the desired synthetic product(s) in the final reaction vessel. 相似文献
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A novel polymer support has been prepared in which functional link points are located on the surface of polymer nano-beads; the use of the support has been demonstrated in the syntheses of unsymmetrical porphyrins. 相似文献
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Zhu XX Zhang JH Gauthier M Luo JT Meng FS Brisse F 《Journal of combinatorial chemistry》2006,8(1):79-84
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. 相似文献
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《Tetrahedron letters》1986,27(41):4933-4936
A solid-phase copolymer of 4-vinylpyridine is shown to be a highly effective reagent/ catalyst for the synthesis of acid anhydrides from mixtures containing equimolar quantities of carboxylic acids and acid chlorides. The process may be carried out in batch or column mode. 相似文献
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[reaction: see text] A new soluble polymer support synthesis of nucleosides is described. The photochemical ring expansion of cyclobutanones in the presence of poly(ethylene glycol) (PEG) results in polymer-supported ribosides. These photoadducts can be cleaved from the polymer under Vorbrüggen coupling conditions with TMS-protected purines and pyrimidines to give ribonucleosides. The method has been extended to include modified PEGs with dendritic end-groups in order to improve the loading levels for these coupling reactions. 相似文献
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This review discusses the synthesis and application of glycosyl thioimidates in chemical glycosylation and oligosaccharide assembly. Although glycosyl thioimidates include a broad range of compounds, the discussion herein centers on S-benzothiazolyl (SBaz), S-benzoxazolyl (SBox), S-thiazolinyl (STaz), and S-benzimidazolyl (SBiz) glycosides. These heterocyclic moieties have recently emerged as excellent anomeric leaving groups that express unique characteristics for highly diastereoselective glycosylation and help to provide a streamlined access to oligosaccharides. 相似文献
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4-(4-Hydroxyphenyl)-2-phenylamino-1,8-naphthyridine was prepared via cyclisation of N-phenyl-N′-3-(4-hydroxyphenethen-1-yl)pyridin-2-ylthiourea in the presence of mercuric oxide. Derivatives of 4-methyl-2-aminoquinolines were prepared in a similar manner from 2-vinylphenylthioureas. 相似文献
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Phenacyl bromides are used as a building blocks in synthetic organic chemistry, which serves as a key model for the development of various biologically important heterocyclic compounds and other industrially important scaffolds. This review covers recent synthetic advances in the preparation of heterocyclic compounds utilizing various phenacyl bromides. A wide range of five- and six-membered heterocyclic compounds as well as fused heterocyclic compounds were synthesized efficiently from the phenacyl bromide precursors through one-pot multicomponent reactions. 相似文献
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Haag R 《Chemistry (Weinheim an der Bergstrasse, Germany)》2001,7(2):327-335
Polymeric supports have become a big necessity for automated synthesis and combinatorial chemistry, yet, the loading capacities of most polystyrene resins are very limited (typically < 1.5 mmol x g(-1)). Dendrimers and hyperbranched polymers have been discussed for this application and now became readily available. These soluble polymers can either be used directly as high-loading supports for substrates, reagents, and catalysts or alternatively in hybrid polymers linked to conventional polystyrene resins. 相似文献