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Polymeric reagents offer a range of unique advantages. Intramolecular reactions, such as the cyclization of peptides or Dieckmann cyclizations, can be brought about by attaching the reactive molecules at remote points along a polymer chain. In contrast, if the reactive molecules are anchored in close proximity on a polymeric support then intermolecular reactions occur, as demonstrated for a ketone synthesis. Apart from such proximity effects, cooperative effects can also be exploited, e.g. in the formation of a 2:1 complex of a crown ether and an alkali metal ion. The hydrolysis of an ester with polyvinylimidazole provides a detailed illustration of hydrophobic interactions. The simple separation of polymer-bound and low-molecular compounds by filtration is another significant advantage. 相似文献
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Hamid Salimi Azam Rahimi Ali Pourjavadi 《Monatshefte für Chemie / Chemical Monthly》2007,138(4):363-379
Summary. Polymer supported reagents have found many applications in recent years. Scientists in research laboratories of agrochemical
and pharmaceutical industries now routinely utilize these compounds to prepare ensembles of small organic molecules for screening.
This review is aimed to highlight some of the most important applications of these promising materials in organic synthesis.
Furthermore, an extensive listing of polymeric reagents that were recently used in organic synthesis is included. 相似文献
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Hamid Salimi Azam Rahimi Ali Pourjavadi 《Monatshefte für Chemie / Chemical Monthly》2007,14(1):363-379
Polymer supported reagents have found many applications in recent years. Scientists in research laboratories of agrochemical
and pharmaceutical industries now routinely utilize these compounds to prepare ensembles of small organic molecules for screening.
This review is aimed to highlight some of the most important applications of these promising materials in organic synthesis.
Furthermore, an extensive listing of polymeric reagents that were recently used in organic synthesis is included. 相似文献
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有机锡试剂在有机合成中的某些新应用 总被引:1,自引:0,他引:1
本文阐述有机锡试剂在有机台成巾的一些新应用。在钯催化下,有机锡试剂与亲电试剂进行偶联,条件温和,收率高。有机锡试剂促进醇醛缩合,可用于不对称合成中。 相似文献
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Dr. Thomas Q. Davies Prof. Michael C. Willis 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(35):8918-8927
Sulfinylamines (R−N=S=O), monoaza analogues of sulfur dioxide, have been known for well over a century, and their reactivity as sulfur electrophiles and in Diels-Alder reactions is well-established. However, they have only rarely been used in organic synthesis in recent decades despite the increasing prominence of compounds containing N=S=O functionality, such as sulfoximines and sulfonimidamides. This Minireview aims to bring wider visibility to the unique chemistry enabled by this class of compounds. We focus on advances from the last 10 years, including the first examples of their use in the one-pot syntheses of sulfoximines and sulfonimidamides. Also covered are the reactions of sulfinylamines with carbon-centred radicals, their use for formation of heterocycles through cycloadditions, and catalytic enantioselective allylic oxidation of alkenes via a hetero-ene reaction. These examples highlight the different reactivity modes of sulfinylamines and their underappreciated potential for forming molecules which contain high- or low-valent sulfur, or even no sulfur at all. 相似文献
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Aleksandra Skowronska Piotr Dybowski 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):275-278
Abstract Novel general routes to thiolophosphates 1 and selenophosphates 2 and their application to regio- and stereoselective synthesis of olefins, functionalized olefins and heterofunctionalized dienes-1, 3 is described. 相似文献
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汉斯酯(Hantzsch Esters)在1881年被合成以来一直被用作还原剂参与加氢还原反应, 近年来科学家发现4-取代的汉斯酯可以发生碳碳键断裂而发生烷基迁移反应. 随后大量以4-取代的汉斯酯类化合物作为烷基化试剂的反应被报道出来, 科学家发现这类烷基化反应的历程主要是烷基自由基的迁移历程. 随着近年自由基化学的快速发展, 为这类新型烷基化试剂的应用发展提供了有力基础. 本文按照该烷基化试剂参与的反应类型分类, 进行简单介绍. 相似文献
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Sarussi Lili Blum Jochanan Avnir David 《Journal of Sol-Gel Science and Technology》2000,19(1-3):17-22
We advance the use of reactive doped sol-gel materials as heterogeneous reagents for organic-chemistry synthesis. Three approaches were demonstrated with SiO2-based materials: Direct physical entrapment of the organic reagent; in-situ generation of an inorganic reagent within the matrix; and covalent attachment of the reagent to the matrix. With the first, entrapped p-toluenesulfonic acid facilitated the 100% yield esterification of benzoic acid with 1-pentanol, and the 100% dehydration of 1-tetralol to 1,2-dihydronaphthalene; with the second approach, a sol-gel oxidant, SiO2/MnO2 was used to convert benzyl alcohol to benzaldehyde and 1-tetralol to 1-tetralone; and with the third, anchored propylamine facilitated dehydrobromination reactions resulting in double-bond formation. Several other reactions with these reagents are described, and their reactivities analyzed. 相似文献
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The ability of the Reformatsky reagent BrZnCH2CO2 tBu 1 to undergo substitution reactions has been verified with several substituted bromides. 相似文献
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The review summarizes published data on the application of N-halocuccinimides in organic synthesis and in natural compounds chemistry. Halogenation, imidation, oxidation, and other reactions are discussed. 相似文献
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Anders Lennartson Susanne Olsson Jonas Sundberg Mikael Håkansson Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(17):3137-3140
Voilà, optical activity : Both enantiomers of 1‐chloroindene have been synthesized in high selectivity from solely achiral starting materials, and without using optically active catalysts (see scheme). These symmetry‐breaking syntheses provide a proof‐of‐concept for a new approach to asymmetric synthesis. NCS=N‐chlorosuccinimide.
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The addition of carbanionic organometallic compounds (usually RLi or RMgX) to a carbonyl group—a key step in numerous syntheses—is not always straightforward. Depending on the substrate, various complications and problems may arise, but in many cases these can be remedied by addition of (RO)3TiCl, (RO)3ZrCl or (R2N)3TiX to the classic lithium and Grignard reagents. This usually leads to formation of stable organo-titanium and -zirconium compounds which react highly selectively with carbonyl groups. For example, CH3Ti(OiPr)3 reacts five orders of magnitude faster with benzaldehyde than with acetophenone at room temperature; reagents of the type RTi(OiPr)3 add smoothly to nitro-, ido-, or cyano-subsituted benzaldehyde, and the reactions may be performed in chlorinated solvents or acetonitrile; the zirconium analogues have particularly low basicity and add in high yield to α- and β-tetralones or to substrates containing a nitroaldol group; the inclusion of chiral OR* groups gives enantioselective reagents (up to 90% ee); allylic (RO3)Ti- derivatives react only at the more highly substituted carbon atom and, in addition, react diastereoselectively (up to 98% ds) with unsymmetrical ketones. Finally, titanium reagents have also been found to effect novel transformations such as direct geminal dialkylation (C?O→CMe2) and alkylative amination [C?O→CR(NR)]. The modification and finetuning (“taming”) of carbonyl reactivity obtainable by use of the new reagents is not dearly bought; starting materials are the cheap and harmless “titanates”, “zirconates” and the corresponding tetrachlorides. 相似文献
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聚乙二醇支持的底物或试剂参与的小分子化合物的合成 总被引:1,自引:0,他引:1
对近年来聚乙二醇为可溶性聚合物支持体支持的底物或试剂参与的小分子化合物的液相有机合成反应进行了总结。参考文献36篇。 相似文献