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Efficient Carbohydrate Synthesis By Intra- and Supramolecular Control
KTH, School of Chemical Science and Engineering (CHE), Chemistry. (Olof Ramström)
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The Lattrell-Dax method of nitrite-mediated substitution of carbohydrate triflates is an efficient method to generate structures of inverse configuration. In this study, the effects of the neighboring group on the Lattrell-Dax inversion were explored. A new carbohydrate/anion host-guest system was discovered and the ambident reactivity of the nitrite anion was found to cause a complicated behavior of the reaction. It has been demonstrated that a neighboring equatorial ester group plays a highly important role in this carbohydrate epimerization reaction, restricting the nitrite N-attack, thus resulting in O-attack only and inducing the formation of inversion compounds in good yields. Based on this effect, efficient synthetic routes to a range of carbohydrate structures, notably β-D-mannosides and β-D-talosides, were designed by use of double parallel and double serial inversion. A supramolecularly activated, triggered cascade reaction was also developed. This cascade reaction is triggered by a deprotonation process that is activated by anions. It was found that the anions can activate this reaction following their hydrogen bonding tendencies to the hydroxyl group in aprotic solvents.

Place, publisher, year, edition, pages
Stockholm: KTH , 2009. , 59 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2009:2
Keyword [en]
Carbohydrate Chemistry, Supramolecular Control, Ambident Reactivity
National Category
Organic Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-9882ISBN: 978-91-7415-207-4 (print)OAI: oai:DiVA.org:kth-9882DiVA: diva2:139802
Public defence
2009-02-05, F3, KTH, Lindstedtsvägen 26, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20100709Available from: 2009-01-27 Created: 2009-01-26 Last updated: 2012-02-23Bibliographically approved
List of papers
1. Reagent-dependent regioselective control in multiple carbohydrate esterifications
Open this publication in new window or tab >>Reagent-dependent regioselective control in multiple carbohydrate esterifications
2007 (English)In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 72, no 4, 1499-1502 p.Article in journal (Refereed) Published
Abstract [en]

Regioselective control in organotin-mediated multiple acylation of carbohydrates is presented. The acylation reagent could be efficiently used to direct the product formation. Reagent-dependent thermodynamic and kinetic control and dynamic assistance mechanisms are suggested, resulting in the efficient preparation of building blocks that normally require many steps with traditional synthesis.

Keyword
D-GLUCOPYRANOSIDE; HYDROXYL GROUP; BENZOYLATION; OLIGOSACCHARIDES; DERIVATIVES; SELECTIVITY; ALKYLATION; ACTIVATION; ACYLATION; SUGARS
National Category
Organic Chemistry
Identifiers
urn:nbn:se:kth:diva-6397 (URN)10.1021/jo0620821 (DOI)000244071100062 ()2-s2.0-33846986010 (Scopus ID)
Note
QC 20100709Available from: 2006-11-22 Created: 2006-11-22 Last updated: 2010-12-03Bibliographically approved
2. Stereospecific Ester Activation in Nitrite-Mediated Carbohydrate Epimerization
Open this publication in new window or tab >>Stereospecific Ester Activation in Nitrite-Mediated Carbohydrate Epimerization
2006 (English)In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 71, no 8, 3306-3309 p.Article in journal (Refereed) Published
Abstract [en]

The Lattrell-Dax method of nitrite-mediated substitution of carbohydrate triflates is an efficient method to generate structures of inverse configuration. In the present study, epimerization of gluco- and galactopyranoside derivatives to the corresponding allo- and gulopyranoside structures by triflation/nitrite treatment has been investigated. It was found that a neighboring ester group was essential for the reactivity of the nitrite-mediated triflate, inversion. Furthermore, a good inversion yield also depended on the relative configuration of the neighboring ester group to the triflate. Only with the ester group in the equatorial position, whatever the configuration of the triflate, did the reaction proceed smoothly, whereas a neighboring axial ester group proved largely inefficient. The results were subsequently used to predict the inversion of glucopyranoside derivatives to the mannopyranoside epimers.

Keyword
stereoselective-synthesis, glycosides, benzoate, anions, sugars
National Category
Organic Chemistry
Identifiers
urn:nbn:se:kth:diva-9883 (URN)10.1021/jo052662i (DOI)000236678100053 ()2-s2.0-33645773127 (Scopus ID)
Note
QC 20100709Available from: 2009-01-27 Created: 2009-01-27 Last updated: 2010-09-15Bibliographically approved
3. Supramolecular Control in Carbohydrate Epimerization: Discovery of a New Anion Host−Guest System
Open this publication in new window or tab >>Supramolecular Control in Carbohydrate Epimerization: Discovery of a New Anion Host−Guest System
2008 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 130, 15270-15271 p.Article in journal (Refereed) Published
Abstract [en]

A new anion-carbohydrate recognition system is described. Pyranosides with axial protons in 1-, 3-, and 5-position proved efficient, forming relatively strong complexes between the anion and the B-face of the carbohydrate. This system could furthermore be used in supramolecular control in Lattrell-Dax epimerization reactions, leading to either activation or deactivation effects.

Keyword
MOLECULAR RECOGNITION; AROMATIC INTERACTIONS; ACTIVATION; INVERSION; COMPLEXES; CHEMISTRY; NITRITE
National Category
Organic Chemistry
Identifiers
urn:nbn:se:kth:diva-9884 (URN)10.1021/ja807044p (DOI)000263311300025 ()2-s2.0-56449123629 (Scopus ID)
Note
QC 20100709Available from: 2009-01-27 Created: 2009-01-27 Last updated: 2010-12-03Bibliographically approved
4. Control of the Ambident Reactivity of the Nitrite Ion inCarbohydrate Epimerization
Open this publication in new window or tab >>Control of the Ambident Reactivity of the Nitrite Ion inCarbohydrate Epimerization
(English)Manuscript (Other academic)
National Category
Organic Chemistry
Identifiers
urn:nbn:se:kth:diva-9885 (URN)
Note
QC 20100709Available from: 2009-01-27 Created: 2009-01-27 Last updated: 2010-07-12Bibliographically approved
5. Efficient Synthesis of β-D-Mannosides and β-D-Talosides by Double Parallel or Double Serial Inversion
Open this publication in new window or tab >>Efficient Synthesis of β-D-Mannosides and β-D-Talosides by Double Parallel or Double Serial Inversion
Show others...
2007 (English)In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 72, no 10, 3694-3701 p.Article in journal (Refereed) Published
Abstract [en]

A neighboring equatorial ester group plays a highly important role in the Lattrell-Dax (nitrite-mediated) carbohydrate epimerization reaction, inducing the formation of inversion compounds in good yields. On the basis of this effect, efficient synthetic routes to beta-D-mannosides and beta-D-talosides, from the corresponding beta-D-galactosides and beta-D-glucosides, have been designed. The present routes are based on multiple regioselective acylation via the respective stannylene intermediates, followed by inversions to the corresponding manno- and talopyranoside structures by nitrite or acetate substitution. It was found that the ester group was able to induce the inversion of its two neighboring groups in high yields following either a double parallel or a double serial inversion process. By combination of direct inversion, and neighboring- as well as remote-group participation, several beta-D-mannoside and beta-D-taloside derivatives were very conveniently obtained in good yields.

Keyword
INTRAMOLECULAR AGLYCON DELIVERY; STEREOSELECTIVE-SYNTHESIS; CORE PENTASACCHARIDE; D-MANNOPYRANOSIDES; N-GLYCANS; CHEMOENZYMATIC SYNTHESIS; LINKED GLYCOPROTEINS; PRACTICAL SYNTHESIS; CHEMICAL-SYNTHESIS; NITRITE ANIONS
National Category
Organic Chemistry
Identifiers
urn:nbn:se:kth:diva-9886 (URN)10.1021/jo062643o (DOI)000246206700013 ()2-s2.0-34248573311 (Scopus ID)
Note

QC 20100709

Available from: 2009-01-27 Created: 2009-01-27 Last updated: 2016-05-09Bibliographically approved
6. Synthesis of Positional Thiol Analogs of β-D-Galactopyranose
Open this publication in new window or tab >>Synthesis of Positional Thiol Analogs of β-D-Galactopyranose
2007 (English)In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, Vol. 29, 4927-4934 p.Article in journal (Refereed) Published
Abstract [en]

Approaches toward the synthesis of thio- beta -D -galactose derivatives are described. These compounds were prepared from the parent carbohydrates: D-galactose, methyl P-D-galactoside and methyl P-D-glucoside, respectively. It was found that not only the strategies of protecting group introduction and selective deprotection, but also the choices of solvent and nucleophilic reagent concentration were crucial to allow the efficient introduction of sulfur at different positions of the galactose ring. The effects from the solvent, the nucleophilic reagent concentration, and the protecting group patterns have been investigated. The results clearly show that ester protecting groups play highly important roles for the synthesis of thio-containing carbohydrates, requiring nonpolar solvents to suppress the neighboring group participation. For the Lattrell-Dax (nitrite -mediated) inversion reaction, employed in the synthetic route to the 2-thio-beta-D-galactoside, intramolecular nucleophilic attack, as well as stronger stereospecific ester activation, are necessary to overcome hindrance from 4,6-O-benzylidene protection.

Keyword
thiosaccharides, galactose, lattrell-dax, inversion
National Category
Organic Chemistry
Identifiers
urn:nbn:se:kth:diva-9887 (URN)10.1002/ejoc.200700364 (DOI)000250367600015 ()2-s2.0-35349025393 (Scopus ID)
Note
QC 20100709. Tidigare titel: Synthesis of Thiogalactose derivatives for S-linked OligosaccharidesAvailable from: 2009-01-27 Created: 2009-01-27 Last updated: 2011-09-06Bibliographically approved
7. Supramolecular activation in triggered cascade inversion
Open this publication in new window or tab >>Supramolecular activation in triggered cascade inversion
2008 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, 1359-1361 p.Article in journal (Refereed) Published
Abstract [en]

An unexpected activation effect from combinations of anionic reagent and amine base resulted in dramatic rate enhancements in multiple carbohydrate cascade inversion.

Keyword
SELF-REPLICATING SYSTEMS; DOMINO REACTIONS; ALTROSIDES; RECEPTORS; CHEMISTRY; EPOXIDES; NITRITE; ANIONS; ALPHA
National Category
Organic Chemistry
Identifiers
urn:nbn:se:kth:diva-9888 (URN)10.1039/b717301f (DOI)000254352900029 ()2-s2.0-41749125230 (Scopus ID)
Note
QC 20100709Available from: 2009-01-27 Created: 2009-01-27 Last updated: 2010-12-03Bibliographically approved
8. Enhanced Basicity by Supramolecular Anion Activation
Open this publication in new window or tab >>Enhanced Basicity by Supramolecular Anion Activation
(English)Manuscript (Other academic)
National Category
Organic Chemistry
Identifiers
urn:nbn:se:kth:diva-9890 (URN)
Note
QC 20100709Available from: 2009-01-27 Created: 2009-01-27 Last updated: 2010-07-09Bibliographically approved

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