Studies on the origin of stereoselectivity in the synthesis of 1,2-trans glycofuranosyl azides

Štimac, Anton; Kobe, J.

doi:10.1016/s0008-6215(99)00293-1

Cited by 33 publications

(14 citation statements)

References 31 publications

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“…The difference in the reaction rates between 1 and 2 may be explained by the trans-1,2-configuration in the b-anomer, which evidently gives rise to neighboring group participation from the benzoyl group at C2 thus resulting in fast exchange of the 1-Oacetyl group 11 . In order to verify the role of neighboring group participation, we synthesized the analogous 1-O-acetyl-2,3,5-tri-O-benzoyl-a-(6) and b-(7) L-arabinofuranoses, the structures of which are shown in Figure 1.…”

Section: Resultsmentioning

confidence: 99%

Reaction kinetics and mechanism of acid-catalyzed anomerization of 1-O-acetyl-2,3,5-tri-O-benzoyl-l-ribofuranose

Forsman

Wärnå

Murzin

et al. 2009

Carbohydrate Research

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Section: Resultsmentioning

confidence: 99%

Reaction kinetics and mechanism of acid-catalyzed anomerization of 1-O-acetyl-2,3,5-tri-O-benzoyl-l-ribofuranose

Forsman

Wärnå

Murzin

et al. 2009

Carbohydrate Research

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“…The methoxyl group of ld was exchanged for an acetoxyl group using sulfuric acid in acetic anhydride [12], to give compound 2a, predominantly as the or-isomer, in 78% yield. The acetoxyl group of 2a was then replaced with an azido group in 83% yield, using trimethylsilyl azide in the presence of tin(IV) chloride [13], yielding 2b. Hydrogenation of the azido group of 2b gave the amine 2e (76%), and reaction of 2e with succinic anhydride gave the final product 2d, largely as the/3-isomer, in 84% yield, and ready for incorporation into peptides using standard SPPS.…”

Section: Resultsmentioning

confidence: 99%

“…The methoxyl group of lg was exchanged for the acetoxyl group, using sulfuric acid in acetic anhydride [12] to give the acetate 2e in 78% yield. Reaction of acetate 2e with TMSN3 in the presence of fin(IV) chloride [13] gave the azide 2f in 88% yield. Catalytic hydrogenation of the azide 2f gave the corresponding amine 2g, in 76% yield.…”

Section: Resultsmentioning

confidence: 99%

Towards synthetic vaccines built on carbohydrate cores

2001

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SummaryLipophilic polyfunctional carbohydrate core/templates have been designed and developed for drug/vaccine delivery. Three carbohydrate-based templates containing four protected N-terminal arms were synthesised from glucose and galactose. Methyl t~-D-glucopyranoside was converted to two derivatives bearing a carboxylic acid handle for attachment to solid supports, spacer arms of differing hydrophilicity, and phthaloyl-protected amino groups suitable for peptide chain extension./~-D-Galactopyranosyl azide was converted to a template bearing a carboxylic acid handle and four BOC-protected amines. All the templates were found to be suitable for attachment to solid supports and subsequent cleavage from resins, using either BOC-or FMOC-methodologies.

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“…Sample solutions: (a) The compounds39–41 A, Ad 6 , B and Bd 6 (abbreviations: A for α‐ and B for β‐ribofuranosyl azides; Ad 6 and Bd 6 for deuterated α‐ and β‐isopropylidene (d 6 ) compounds) (Scheme ) were dissolved separately (about 0.5 mM each) in anhydrous methanol with 5 mM ammonium acetate, (b) pairs of compounds A + Ad 6 , A + Bd 6 , B + Ad 6 and B + Bd 6 were separately dissolved (0.5 mM each) in methanol with 5 mM NH 4 Ac.…”

Section: Methodsmentioning

confidence: 99%

Electrospray ionization mass spectrometric investigation of ammonium ion complexes with anomeric 2,3‐O‐isopropylidene‐1α‐ and ‐1β‐D‐ribofuranosyl azides: anomeric and kinetic isotope effects in ammonium affinities

Kralj

Kocjan²,

Kobe

2001

Rapid Comm Mass Spectrometry

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[Methanol + ammonium acetate] solutions of anomeric 2,3-O-isopropylidene-1alpha- and 1beta-ribofuranosyl azides were investigated by electrospray ionization mass spectrometry (ESI-MS). The compounds included d6-labeled and/or unlabeled isopropylidene groups that enable the identification of peaks characteristic of the ammonium-attached monomeric (MNH4(+)), ammonium-bound homodimeric ([M]2NH4(+)) and heterodimeric ([MNH4M1](+)) complex ions in ESI mass spectra of solutions of a pair of compounds. The intensities of the product ion peaks obtained by the collisionally activated ammonium-bound dimeric ions are related to the secondary isotope effect k(alpha)/k(alphad6) = 0.88 and k(beta)/k(betad6) = 1.25 or to isotope plus anomeric effects k(alpha)/k(betad6) = 1.43 and k(beta)/k(alphad6) = 0.59 in the ammonium affinities of these compounds. The calculations of solely anomeric effects in the ammonium affinities of alpha and beta anomeric compounds obtained from the data presented previously give two series of values: k(alpha)/k(beta) = (k(alpha)/k(alphad6))(k(alphad6)/k(beta)) = 1.49 and k(alphad6)/k(betad6) = (k(alphad6)/k(beta))(k(beta)/k(betad6)) = 2.12 or k(alpha)/k(beta) = (k(alpha)/k(betad6))(k(betad6)/k(beta)) = 1.14 and k(alphad6)/k(betad6) = (k(alphad6)/k(alpha))(k(alpha)/k(betad6)) = 1.63. The disparities of these results indicate the different structures of hydrogen bonding in ammonium-bound dimeric complexes which decompose to monomeric ions with different rate constants. Comparison of experimental results obtained by the qualitative approach of the kinetic method and ammonium affinities of these compounds calculated by the semi-empirical molecular orbital method (AM1) show that the [MNH4M1](+) dimeric complex ions dissociate to the most stable MNH4(+) and M1NH4(+) monomeric ions. The obtained relative order of ammonium affinities of these compounds is: alphad6 > alpha > beta > betad6.

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Studies on the origin of stereoselectivity in the synthesis of 1,2-trans glycofuranosyl azides

Cited by 33 publications

References 31 publications

Reaction kinetics and mechanism of acid-catalyzed anomerization of 1-O-acetyl-2,3,5-tri-O-benzoyl-l-ribofuranose

Reaction kinetics and mechanism of acid-catalyzed anomerization of 1-O-acetyl-2,3,5-tri-O-benzoyl-l-ribofuranose

Towards synthetic vaccines built on carbohydrate cores

Electrospray ionization mass spectrometric investigation of ammonium ion complexes with anomeric 2,3‐O‐isopropylidene‐1α‐ and ‐1β‐D‐ribofuranosyl azides: anomeric and kinetic isotope effects in ammonium affinities

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