共查询到20条相似文献,搜索用时 15 毫秒
1.
Shubhasish MukherjeeKevin W.C Poon Daniel L Flynn Paul R Hanson 《Tetrahedron letters》2003,44(38):7187-7190
Application of a capture-ROMP-release strategy for the chromatography-free purification of Mitsunobu reaction products is described. Norbornenyl-tagged reagents are utilized for standard solution phase Mitsunobu chemistry. Post-reaction phase-switching is accomplished via in situ ring-opening metathesis polymerization (ROMP) followed by precipitation of the polymer with methanol. Release of the product from the polymer affords amines and alkyl hydrazine derivatives with good yields and purities. 相似文献
2.
The ring-opening addition of methyl 2,3-dimethoxy-6-iodobenzoate to oxabenzonorbornadienes followed by cyclization in the presence of NiBr2(dppe) and Zn metal powder in acetonitrile at 80 degrees C to give the corresponding benzocoumarin derivatives is described. This methodology was then applied to the synthesis of natural product arnottin I, first isolated from Xanthoxylum arnottianum Maxim, using protecting group chemistry. After deprotection and subsequent ring closure, arnottin I was obtained in 21% overall yield after six steps starting from catechol. 相似文献
3.
Stereospecific Stille coupling reactions of 2-metallo-dihydropyrans with Z-vinyl iodo alcohols and subsequent cyclisation provides rapid access to 1,7-dioxaspiro[5.5]undecane family of spiroketals. 相似文献
4.
Hartwig Hcker 《Macromolecular Symposia》1996,101(1):1-9
In the present survey the limitations for the industrial application of polymer syntheses are discussed as well as the directions, syntheses may go. As particular examples the living anionic polymerization and the respective ring-opening polymerization and copolymerization are discussed. Under the aspect of future developments some examples of biotechnological polymerization and particular features of biopolymers are given 相似文献
5.
Spyros MourtasChristina Katakalou Andriana NicolettouChryssoula Tzavara Dimitrios GatosKleomenis Barlos 《Tetrahedron letters》2003,44(1):179-182
Aminothiols were attached through their thiol group onto the 4,4′-dimethoxytrityl (Dmt)-, 4-methoxytrityl (Mmt)-, 4-methyltrityl (Mtt)-, trityl (Trt)- and 2-chlorotrityl (Clt)-resins. The new resins were used in the solid-phase synthesis of aminothiol containing peptides utilizing N-Fmoc amino acids. The synthesized peptides were cleaved from the resins by treatment with trifluoroacetic acid (TFA) solutions using triethylsilane (TES) or ethanedithiol (EDT) as scavengers. 相似文献
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7.
[reaction: see text] The stereoselective synthesis of pyridinones was accomplished by the nucleophilic addition of Grignard reagents to a chiral pyridinium salt derived from 4-methoxypyridine. This methodology was applied to an expedient synthesis of (-)-barrenazine A and B. After N-functionalization and 1,4-reduction of the pyridinone system, the corresponding alpha-amino piperidinones readily undergo dimerization to give the hexahydrodipyridinopyrazine skeleton of the barrenazine alkaloids. 相似文献
8.
[reaction: see text] Methyl-l-callipeltose, the carbohydrate associated with callipeltoside A, has been synthesized in eight steps and 23% overall yield from enantioenriched allylsilane 6 and acetaldehyde. The key steps are a highly diastereoselective formal [4 + 2] annulation and a Cr(VI)-catalyzed oxidative C-C bond cleavage to produce lactone 11. 相似文献
9.
Warner DL Hibberd AM Kalman M Klapars A Vedejs E 《The Journal of organic chemistry》2007,72(22):8519-8522
Hindered N-silylamines were examined for their utility to serve as protecting groups for the labile aziridine nitrogen found within the highly sensitive aziridinomitosene framework. tert-Butyldiphenylsilyl and modified tert-butyldiphenylsilyl groups were the most resistant to nitrogen-silicon bond cleavage under various reaction conditions and were thus employed in transformations relevant to aziridinomitosene synthesis. The N-silylaziridines 7a, 21a, and 21b underwent azomethine ylide cycloaddition and afforded, upon deprotection, the N-H aziridine 24 in 18-32% overall yield for the three steps. 相似文献
10.
[reaction: see text] Pyridinedithioesters can be used as efficient heterodienophiles when activated by complexation with BF(3), by protonation, or by oxidation of the nitrogen atom of the pyridine moiety. The hetero-Diels-Alder reaction using 3-pyridinedithioester as a heterodienophile was the key step in a new synthesis of Aprikalim in racemic form. The methodology can be reliably extended to prepare new analogues of Aprikalim. 相似文献
11.
Silacyclopentanes have been prepared from vinyl(homoallyl)silanes or vinyl(homopropargyl)silanes and organolithium reagents by a tandem intermolecular-intramolecular sequence involving a 5-exo cyclisation process. The unexpected stereochemical outcome of the sequence involving a 5-exo-dig cyclisation is rationalised. 相似文献
12.
A series of 3-arylthio-1,3-disubstituted-oxindoles were prepared in good yields by the reaction of α-diazocarbonyl compounds and sulfenamides. The reaction involves a Rh-catalyzed thia-Sommelet-Hauser-type rearrangement. 相似文献
13.
[reaction: see text] A new iterative strategy for the synthesis of unsymmetrically substituted polyynes has been developed. The starting bromoalkyne is homologated by one acetylene unit through palladium-catalyzed cross-coupling with a TIPS-protected terminal acetylene and a subsequent in situ one-pot AgF-mediated desilylative bromination. The utility of this new synthetic method is demonstrated by its application to the total synthesis of (S)-(E)-15,16-dihydrominquartynoic acid. 相似文献
14.
An anionic chiral auxiliary mediated asymmetric alkylation of carbamate 2 provides 3-substituted isoindolinones 4 in high ee. This methodology was used in the first asymmetric synthesis of (+)-lennoxamine. 相似文献
15.
[reaction: see text] The asymmetric synthesis of the fully elaborated macrocyclic core of cytotrienins A-D, potent apoptosis-inducing agents, is described. Synthetic highlights include the construction of the aniline bond using a copper-mediated amidation and the use of a ring-closing metathesis (RCM) reaction to efficiently install the (E,E,E)-triene and simultaneously construct the macrocyclic lactam. 相似文献
16.
Nawel Cheikh Nathalie BarNourredine Choukchou-Braham Bachir Mostefa-KaraJean-François Lohier Jana Sopkova 《Tetrahedron》2011,67(8):1540-1551
We have developed the synthesis of twenty four new iminolactones, bis-iminolactones and bis-lactones by subsequent esterification-condensation or addition-condensation reactions according to two strategies from α-hydroxyketones. The X-ray diffraction data of a bis-iminolactone is described and present an interesting helical column packing. 相似文献
17.
Karynne C. Souza Nelcy D. S. Mohallem Edésia M. B. Sousa 《Journal of Sol-Gel Science and Technology》2010,53(2):418-427
The synthesis of nanostructured magnetic materials has been intensively researched because of their large field of applications as magnetic carriers in drug targeting, hyperthermia in tumor treatment, among others. Much effort has been invested in magnetic nanoparticles for bioapplications. However, as these nanoparticles present high specific surface area, unprotected nanoparticles can easily form aggregates and react with oxygen in the air. They can also rapidly biodegrade when directly exposed to biological systems. In this context, we have explored the possibility of synthesizing a mesoporous SiO2–Fe3O4 nanocomposite and its AC magnetic-field-induced heating properties. The magnetite nanocomposite was obtained by impregnation of an iron precursor into a silica framework. The proposed method involves the preparation of an iron oxide precursor in ethanol and the subsequent impregnation of SBA-15 mesoporous hexagonal silica. Iron oxide was formed inside the porous structure, thus producing the magnetic device. The nanocomposite was characterized by X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FTIR), N2 adsorption, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Measurements of AC magnetic-field-induced heating properties of the obtained nanocomposite, both of the solid form and in aqueous solution, under different applied magnetic fields showed that it is suitable as a hyperthermia agent for biological applications. 相似文献
18.
Solidification of fluidic ionic liquids into porous materials yields porous ionic networks that combine the unique characteristics of ionic liquids with the common features of polymers and porous materials. This minireview reports the most recent advances in the design of porous ionic liquids. A summary of the synthesis of ordered and disordered porous ionic liquid-based nanoparticles or membranes with or without templates is provided, together with the new concept of room temperature porous ionic liquids. As a versatile platform for functional materials, porous ionic liquids have shown widespread applications in catalysis, adsorption, sensing, actuation, etc. This new research direction towards ionic liquids chemistry is still in its early stages but has great potential. 相似文献
19.
Nanocrystal-micelle: synthesis, self-assembly and application 总被引:1,自引:0,他引:1
Fan H 《Chemical communications (Cambridge, England)》2008,(12):1383-1394
Nanocrystals (NCs) are one of the important building blocks for fabrication of nanostructured arrays for wide range of optical, electronic, magnetic, catalytic and biosensing applications. Here, our recent advances in the synthesis, self-assembly and application of NC-micelles are highlighted. The NCs are encapsulated inside the core of surfactant micelles in a rapid, interfacially driven micro-emulsion process. The flexible surface chemistry of the NC-micelles causes them to be water-soluble and allows further self-assembly into two- and three-dimensional ordered arrays. The NC-micelles are biocompatible, of interest for bio-labeling. Finally, integration of the ordered arrays and charge transport property are discussed. 相似文献
20.
The data on the synthesis, properties, and practical application of porphyrazines (tetraazaporphines), the nearest structural analogs of porphyrins and phthalocyanines, have been systematized.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2320–2336, December, 1995.This work was financially supported by the Russian Government and the International Science Foundation (Grant No. MEY300). 相似文献