4,6-di-O-benzoyl-3-O-benzyl-α-d-arabino-hexopyranos-2-ulosyl bromide: A conveniently accessible glycosyl donor for the expedient construction of diantennary β-d-mannosides branched at O-3 and O-6

Lichtenthaler, Frieder W.; Kläres, Ulrich; Szurmai, Zoltán; Werner, Bernd

doi:10.1016/s0008-6215(97)00249-8

Cited by 44 publications

(15 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The only exceptions are the 3, O B boat and the 3 S 5 skew‐boat conformations in the cases of α‐Alt and α‐Ido, with the relative free energies in the range 8–15 kJ mol −1 , corresponding to equilibrium populations of 0.2–4%. Interestingly, the occurrence of thermally accessible non‐chair conformations has been suggested for both compounds considering the interpretation of experimental NMR measurements ( 3 S 5 for both Alt96, 345, 346 and Ido,123 reported in the former articles as O S 2 ). The occurrence of non‐chair conformations with non‐negligible populations for these two compounds is again in line with the above suggestion that the destabilization of the 4 C 1 α‐pyranose conformation by steric (axial) crowding promotes the appearance of unusual isomers and conformers (furanose form, 1 C 4 α‐pyranose form, and non‐chair, conformations).…”

Section: Resultsmentioning

confidence: 85%

A reoptimized GROMOS force field for hexopyranose‐based carbohydrates accounting for the relative free energies of ring conformers, anomers, epimers, hydroxymethyl rotamers, and glycosidic linkage conformers

2010

View full text Add to dashboard Cite

This article presents a reoptimization of the GROMOS 53A6 force field for hexopyranose-based carbohydrates (nearly equivalent to 45A4 for pure carbohydrate systems) into a new version 56A(CARBO) (nearly equivalent to 53A6 for non-carbohydrate systems). This reoptimization was found necessary to repair a number of shortcomings of the 53A6 (45A4) parameter set and to extend the scope of the force field to properties that had not been included previously into the parameterization procedure. The new 56A(CARBO) force field is characterized by: (i) the formulation of systematic build-up rules for the automatic generation of force-field topologies over a large class of compounds including (but not restricted to) unfunctionalized polyhexopyranoses with arbritrary connectivities; (ii) the systematic use of enhanced sampling methods for inclusion of experimental thermodynamic data concerning slow or unphysical processes into the parameterization procedure; and (iii) an extensive validation against available experimental data in solution and, to a limited extent, theoretical (quantum-mechanical) data in the gas phase. At present, the 56A(CARBO) force field is restricted to compounds of the elements C, O, and H presenting single bonds only, no oxygen functions other than alcohol, ether, hemiacetal, or acetal, and no cyclic segments other than six-membered rings (separated by at least one intermediate atom). After calibration, this force field is shown to reproduce well the relative free energies of ring conformers, anomers, epimers, hydroxymethyl rotamers, and glycosidic linkage conformers. As a result, the 56A(CARBO) force field should be suitable for: (i) the characterization of the dynamics of pyranose ring conformational transitions (in simulations on the microsecond timescale); (ii) the investigation of systems where alternative ring conformations become significantly populated; (iii) the investigation of anomerization or epimerization in terms of free-energy differences; and (iv) the design of simulation approaches accelerating the anomerization process along an unphysical pathway.

show abstract

Section: Resultsmentioning

confidence: 85%

A reoptimized GROMOS force field for hexopyranose‐based carbohydrates accounting for the relative free energies of ring conformers, anomers, epimers, hydroxymethyl rotamers, and glycosidic linkage conformers

2010

View full text Add to dashboard Cite

show abstract

“…It has to be noted that a decade ago, Lichetenthaler and coworkers [77][78][79] found that α-cycloaltrin could exist as a fast equilibrating mixture of three different conformations conformers. Thus, in this work we will use these theoretical estimates as a reference when testing new force field parameter sets.…”

Section: Nmr Conformational Analysis Of D-altrosementioning

confidence: 99%

Puckering free energy of pyranoses: A NMR and metadynamics-umbrella sampling investigation

Autieri

Sega

Pederiva

et al. 2010

The Journal of Chemical Physics

View full text Add to dashboard Cite

We present the results of a combined metadynamics-umbrella sampling investigation of the puckered conformers of pyranoses described using the gromos 45a4 force field. The free energy landscape of Cremer-Pople puckering coordinates has been calculated for the whole series of α and β aldohexoses, showing that the current force field parameters fail in reproducing proper puckering free energy differences between chair conformers. We suggest a modification to the gromos 45a4 parameter set which improves considerably the agreement of simulation results with theoretical and experimental estimates of puckering free energies. We also report on the experimental measurement of altrose conformers populations by means of NMR spectroscopy, which show good agreement with the predictions of current theoretical models.

show abstract

“…Cleavage of the isopropylidene groups with Dowex H + resin in hot water afforded 8 in excellent yield. 31 Conveniently, upon concentrating the crude reaction mixture, the β-anomer crystallized selectively. Acetylation proceeded with minimal epimerization at the anomeric center to produce 9.…”

Section: Preparation Of Glucose Monomermentioning

confidence: 99%

Synthetic Studies toward Mycobacterium tuberculosis Sulfolipid-I

Leigh

Bertozzi

2008

J. Org. Chem.

View full text Add to dashboard Cite

Sulfolipid-I (SL-I) is an abundant metabolite found in the cell wall of Mycobacterium tuberculosis that is comprised of a trehalose 2-sulfate core modified with four fatty acyl substituents. The correlation of its abundance with the virulence of clinical isolates suggests a role for SL-I in pathogenesis, although its biological functions remain unknown. Here we describe the synthesis of a SL-I analogue bearing unnatural lipid substituents. A key feature of the synthesis was application of an intramolecular aglycon delivery reaction to join two differentially protected glucose monomers, one prepared with a novel α-selective glycosylation. The route developed for the model compound can be readily extended to the synthesis of native SL-I as well as additional analogues for use in the investigation of SL-I's functions.

show abstract

4,6-di-O-benzoyl-3-O-benzyl-α-d-arabino-hexopyranos-2-ulosyl bromide: A conveniently accessible glycosyl donor for the expedient construction of diantennary β-d-mannosides branched at O-3 and O-6

Cited by 44 publications

References 37 publications

A reoptimized GROMOS force field for hexopyranose‐based carbohydrates accounting for the relative free energies of ring conformers, anomers, epimers, hydroxymethyl rotamers, and glycosidic linkage conformers

A reoptimized GROMOS force field for hexopyranose‐based carbohydrates accounting for the relative free energies of ring conformers, anomers, epimers, hydroxymethyl rotamers, and glycosidic linkage conformers

Puckering free energy of pyranoses: A NMR and metadynamics-umbrella sampling investigation

Synthetic Studies toward Mycobacterium tuberculosis Sulfolipid-I

Contact Info

Product

Resources

About