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Dipolar Cycloaddition Reaction (dipolar + cycloaddition_reaction)

Distribution by Scientific Domains
Chemistry71%

Selected Abstracts

ChemInform Abstract: Preparation of Highly Substituted Tetrahydropyrans via a Metal Assisted Dipolar Cycloaddition Reaction.

CHEMINFORM, Issue 16 2010
Eric A. Allart
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

ChemInform Abstract: Recognition-Mediated Regiocontrol of a Dipolar Cycloaddition Reaction.

CHEMINFORM, Issue 37 2001
Sarah J. Howell
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

ChemInform Abstract: Dipolar Cycloaddition Reactions of Isatin Derived Azomethine Ylide with 3,4-Diphenylcyclobutene-1,2-dione: Synthesis of Novel Spiro[oxindole-3,2,-pyrrolidine] Derivatives.

CHEMINFORM, Issue 3 2001
Vijay Nair
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

Synthesis of Furo[2,3- b]pyrazine Nucleoside Analogues with 1,2,3-Triazole Linkage

MOLECULAR INFORMATICS, Issue 11-12 2007
Denis
Abstract Sonogashira coupling reaction with the readily available 1-(4-methoxybenzyl)-3,5-dichloropyrazin-2(1H)-ones was followed by mild silver-catalyzed cyclization to provide the corresponding 2-chlorofuro[2,3- b]pyrazines in excellent yields. A second Sonogashira cross-coupling reaction resulted in the formation of 2-ethynylfuro[2,3- b]pyrazines, which were coupled with D -ribose and 2-deoxy- D -ribose using a microwave-assisted Cu(I)-catalyzed Huisgen [2+3] dipolar cycloaddition reaction, to generate a small library of new nucleoside analogues. [source]

Synthesis of dendrimer,carbon nanotube conjugates

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2008
A. García
Abstract We describe the coupling between Carbon Nanotubes (CNTs) and a second-generation cyanophenyl-based dendrimer. The goal of our work is the synthesis of highly functionalized CNTs without provoking damage to the conjugated ,-system. One approach is the attachment of dendrimers with a high density of functional groups to the CNTs. These groups serve as anchor points for further reactions. With this aim, we have carried out a primary modification on CNTs by the use of 1,3 dipolar cycloaddition reaction. We have employed Single Wall Carbon Nanotubes (SWNTs) as well as Multi Wall Carbon Nanotubes (MWNTs) obtaining 238 ,mol and 511 ,mol of pyrrolidine groups per gram, respectively. The amount of amino groups introduced in the system was measured by the Kaiser test as well as thermogravimetric analyses. As a second step, dendrimer incorporation was performed by carbodiimide chemistry. Thermogravimetric Analysis, Raman Spectroscopy and Atomic Force Microscopy characterization techniques are reported for the characterization of the final CNT,dendrimer conjugate. The results show that the dendrimer has been attached covalently to the previously generated amine groups. Morphologically, the attached dendrimer with an estimated theoretical molecular length of 6.4 nm, generates a wrapping of 8 nm thick around the CNTs walls. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Synthesis and Photoinduced Electron-Transfer Properties of Phthalocyanine,[60]Fullerene Conjugates

CHEMISTRY - A EUROPEAN JOURNAL, Issue 12 2008
Maurizio Quintiliani Dr.
Abstract A series of three novel ZnPc,C60 conjugates (Pc=phthalocyanine) 1,a,c bearing different spacers (single, double, and triple bond) between the two electroactive moieties was synthesized and compared to that of ZnPc,C60 conjugate 2, in which the two electroactive moieties are linked directly. The synthetic strategy, towards the preparation of 1,a,c, involved palladium-catalyzed cross-coupling reactions over a monoiodophthalocyanine precursor 4 to introduce the corresponding spacer, and subsequent dipolar cycloaddition reaction to C60. Detailed photophysical investigations of 1,a,c and 2 prompted an intramolecular electron transfer that evolves from the photoexcited ZnPc to the electron-accepting C60. In particular, with the help of femtosecond laser photolysis charge separation was indeed confirmed as the major deactivation channel. Complementary time-dependent density functional calculations supported the spectral assignment, namely, the spectral identity of the ZnPc.+ radical cation and the C60., radical anion as seen in the differential absorption spectra. The lifetimes of the correspondingly formed radical ion-pair states depend markedly on the solvent polarity: they increase as polarity decreases. Similarly, although to a lesser extent, the nature of the linker impacts the lifetime of the radical ion-pair states. In general, the lifetimes of these states tend to be shortest in the system that lacks any spacer at all (2), whereas the longest lifetimes were found in the system that carries the triple-bond spacer (1,a). [source]

Facile Access to an Efficient Solid-Supported Click Catalyst System Based on Poly(ethyleneimine)

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 1 2009
Lies Bonami
Abstract A novel heterogeneous copper(I) catalyst system, which is based on readily available poly(ethyleneimine), has been used as a recyclable catalyst for Cu(I) catalyzed "click" 1,3 dipolar cycloaddition reactions of azides and alkynes in organic media. Branched poly(ethyleneimine) was first methylated and then cross-linked with 1,9-dibromononane. Subsequently, after the immobilization of Cu(I)Br, this system was applied for heterogeneous copper catalyzed click chemistry of a few model reagents and polymeric compounds. [source]