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big molecules – EUREKAMOMENTS IN ORGANIC CHEMISTRY https://amcrasto.theeurekamoments.com DR ANTHONY MELVIN CRASTO Ph.D, WorldDrugTracker, Glenmark scientist ( Ph.D, ICT) helping millions with chemistry websites, million hits on google sites, Intention is to help chemists across the world, content is academic Tue, 22 Oct 2013 20:51:09 +0000 en-US hourly 1 https://wordpress.org/?v=6.5.2 Star-Shaped Macromolecule Grabs Large Anions-Chemists at Indiana University Bloomington have created a symmetrical, five-sided macrocycle that is easy to synthesize and has characteristics that may help expand the molecular tool box available to researchers in biology, chemistry and materials sciences. https://amcrasto.theeurekamoments.com/2013/06/17/star-shaped-macromolecule-grabs-large-anions-chemists-at-indiana-university-bloomington-have-created-a-symmetrical-five-sided-macrocycle-that-is-easy-to-synthesize-and-has-characteristics-that-may-he/ Mon, 17 Jun 2013 11:45:32 +0000 http://amcrasto.theeurekamoments.com/?p=969 Continue reading Star-Shaped Macromolecule Grabs Large Anions-Chemists at Indiana University Bloomington have created a symmetrical, five-sided macrocycle that is easy to synthesize and has characteristics that may help expand the molecular tool box available to researchers in biology, chemistry and materials sciences.]]>

This model shows the five-sided cyanostar macrocycle capturing perchlorate at its center. (Credit: Amar Flood)], Chemists at Indiana University Bloomington have created a symmetrical, five-sided macrocycle that is easy to synthesize and has characteristics that may help expand the molecular tool box available to researchers in biology, chemistry and materials sciences.The molecule, which the researchers call cyanostar, was developed in the lab of Amar Flood, associate professor in the Department of Chemistry in the College of Arts and Sciences. It is described in an article in the journal Nature Chemistry, scheduled for publication in August and available online. Semin Lee, Chun-Hsing Chen, Amar H. Flood. A pentagonal cyanostar macrocycle with cyanostilbene CH donors binds anions and forms dialkylphosphate [3]rotaxanes. Nature Chemistry, 2013; DOI: 10.1038/nchem.1668

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]]> Efficient Synthesis of Thiolactoside Glycoclusters by Ruthenium-Catalyzed Cycloaddition Reaction of Disubstituted Alkynes on Carbohydrate Scaffolds (pages 972–983) https://amcrasto.theeurekamoments.com/2013/02/11/efficient-synthesis-of-thiolactoside-glycoclusters-by-ruthenium-catalyzed-cycloaddition-reaction-of-disubstituted-alkynes-on-carbohydrate-scaffolds-pages-972-983/ Mon, 11 Feb 2013 11:50:12 +0000 http://amcrasto.theeurekamoments.com/?p=560 Continue reading Efficient Synthesis of Thiolactoside Glycoclusters by Ruthenium-Catalyzed Cycloaddition Reaction of Disubstituted Alkynes on Carbohydrate Scaffolds (pages 972–983)]]>  

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Efficient Synthesis of Thiolactoside Glycoclusters by Ruthenium-Catalyzed Cycloaddition Reaction of Disubstituted Alkynes on Carbohydrate Scaffolds (pages 972–983)Alejandro J. Cagnoni, Oscar Varela, María Laura Uhrig and José Kovensky

European Journal of Organic Chemistry

Volume 2013, Issue 5, pages 972–983, February 2013

Article first published online: 13 DEC 2012 | DOI: 10.1002/ejoc.201201412

http://onlinelibrary.wiley.com/doi/10.1002/ejoc.201201412/abstract

Ruthenium-catalyzed cycloaddition of symmetric disubstituted alkynes bearing two thiosugar units and azide-containing carbohydrate scaffolds afforded multivalent thiolactosides. A tetravalent glycoconjugate based on a trehalose scaffold displayed the best multivalent effect on binding to plant lectin, peanut agglutinin.

Abstract

Lectin-carbohydrate interactions are responsible for several cellular processes involved in the immune system and the development of certain types of cancer. To further understanding of the cellular responses triggered by these interactions, complex carbohydrates are designed and prepared. Here, we describe the synthesis of a family of multivalent glycoclusters based on carbohydrate cores bearing thiolactosides or thiogalactosides as recognition elements with structural valencies ranging from 2 to 8. The synthetic strategy involves a key ruthenium-catalyzed cycloaddition reaction between symmetric disubstituted alkynes bearing two thiosugar units and azide-containing carbohydrate scaffolds. This methodology afforded high-valency glycoconjugates in good to excellent yields. Binding affinities of the synthetic β-thiolactosides for peanut lectin were measured by isothermal titration calorimetry. These titrations revealed micromolar affinities as well as a multivalent effect. A tetravalent glycoconjugate based on a trehalose scaffold displayed the highest binding affinity.
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