Bimodal concentration-dependent reactivity pattern of a glycosyl donor: Is the solution structure involved?

Kononov, L. O.; Fedina, Ksenia G.; Orlova, A. V.; Kondakov, N. N.; Abronina, Polina I.; Podvalnyy, Nikita M.; Chizhov, Alexander O.

doi:10.1016/j.carres.2016.11.009

Cited by 29 publications

(33 citation statements)

References 81 publications

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“…Apparently, one must consider differences in the structures of reaction solutions in each case, which could include differences in structures of supramers (and references cited therein) formed by both acid reagent , and carbohydrate substrate. This issue deserves a special physico-chemical study, similar to those we conducted − for other systems.…”

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confidence: 68%

A Ring Contraction of 2,3-Di-O-Silylated Thiopyranosides To Give Thiofuranosides under Mildly Acidic Conditions

et al. 2018

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A pyranose ring contraction of ethyl 1-thio-β-d-galactopyranosides has been discovered that proceeds with retention of aglycon under mildly acidic conditions (aq TFA in CH2Cl2). Key factors for success of this rearrangement are the presence of bulky silyl (TIPS or TBDPS) substituents at both O-2 and O-3 and a free hydroxy group at C-4 (derivatives with acid-labile protective groups at O-4 will also engage in this reaction). The rearrangement cleanly proceeds for 2,3-di-O-TIPS derivatives with two hydroxy groups at C-4 and C-6, acid-labile TES groups at O-4 and O-6, or one acyl substituent (Bz, ClAc) at O-6. A possibility to switch the direction of the debenzylidenation reaction in 4,6-O-benzylidene-2,3-di-O-TIPS/TBDPS derivatives by the choice of an acid (TFA, which cleanly gives furanose, versus AcOH, which cleaves benzylidene acetal only) may present an advantage in the divergent synthesis of selectively protected glycosyl donors (either in furanose or pyranose form) useful for the synthesis of biologically important oligosaccharides.

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confidence: 68%

A Ring Contraction of 2,3-Di-O-Silylated Thiopyranosides To Give Thiofuranosides under Mildly Acidic Conditions

et al. 2018

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“…Thus, the reactivity and selectivity of an arabinofuranosylation sequence were demonstrated to vary in a non-linear fashion, with the optimal concentration correlating loosely with a discontinuity in the concentration dependence of specific rotation of a solution of donor (Figure 19). 291…”

Section: Influence Of Solventmentioning

confidence: 99%

“…Kononov has pointed out, however, that alternative explanations exist, most notably the influence of temperature on the mesoscale structuring of the solution. 291…”

Section: Influence Of Temperaturementioning

confidence: 99%

The Experimental Evidence in Support of Glycosylation Mechanisms at the S_N1–S_N2 Interface

et al. 2018

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A critical review of the state-of-the-art evidence in support of the mechanisms of glycosylation reactions is provided. Factors affecting the stability of putative oxocarbenium ions as intermediates at the S1 end of the mechanistic continuum are first surveyed before the evidence, spectroscopic and indirect, for the existence of such species on the time scale of glycosylation reactions is presented. Current models for diastereoselectivity in nucleophilic attack on oxocarbenium ions are then described. Evidence in support of the intermediacy of activated covalent glycosyl donors is reviewed, before the influences of the structure of the nucleophile, of the solvent, of temperature, and of donor-acceptor hydrogen bonding on the mechanism of glycosylation reactions are surveyed. Studies on the kinetics of glycosylation reactions and the use of kinetic isotope effects for the determination of transition-state structure are presented, before computational models are finally surveyed. The review concludes with a critical appraisal of the state of the art.

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“…The coincidence of "critical" temperatures for aqueous solutions of two different derivatives of carbohydrates [43,44], apparently, indicates a common cause of this phenomenon. It is possible that jump-like changes in the specific optical rotation of aqueous carbohydrate solutions with a change in temperature reflect significant changes in the structure of water [45,46], and the molecules of chiral solutes (carbohydrates) act as "probes" that "sense" the slightest changes in their conformation or rearrangement of the microenvironment (in the solvation "shell"), which at the macroscopic level is manifested as a change in the magnitude of the specific rotation (see [19,26] and references cited therein).…”

Section: (Black Circles) and Day 3 (Blue Triangles) Solution # 3 At mentioning

confidence: 99%

“…This new type of "weak" (judging by the magnitude of the interaction energy, which does not exceed k B T [17]), but the extremely effective and spontaneous structuring of liquids has not attracted the attention of researchers for a long time. Only recently has its importance been identified for an adequate description of reactions and other chemical processes [8,9,13,14,[18][19][20][21][22][23][24][25][26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

Polarimetry as a method for studying the structure of aqueous carbohydrate solutions: correlation with other methods

Orlova¹,

Kononov²

2020

RENSIT

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The review provides data indicating that polarimetry is a sensitive tool for studying the structure of aqueous carbohydrate solutions. Using aqueous solutions of D-levoglucosan (1,6-anhydro-D-glucopyranose) as an example, it was demonstrated, using polarimetry, quantum chemical calculations, HPLC, static and dynamic light scattering, that polarimetry allows one to detect changes in the structure of solutions with changes in concentration and temperature, as well as the evolution of the structure of solutions over time. In particular, the phenomenon of the existence of "critical" concentrations and temperatures was discovered at which the specific rotation of the solutions undergo jump-like changes, apparently reflecting rearrangements in the structure of the solution. It is also possible that in the case of aqueous solutions, chiral carbohydrate molecules might act as "probes" that "sense" the slightest changes in their conformation or rearrangement of the environment (in the solvation shell) caused by changes in the structure of water, which at the macroscopic level manifests themselves as change in specific rotation.

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Bimodal concentration-dependent reactivity pattern of a glycosyl donor: Is the solution structure involved?

Cited by 29 publications

References 81 publications

A Ring Contraction of 2,3-Di-O-Silylated Thiopyranosides To Give Thiofuranosides under Mildly Acidic Conditions

A Ring Contraction of 2,3-Di-O-Silylated Thiopyranosides To Give Thiofuranosides under Mildly Acidic Conditions

The Experimental Evidence in Support of Glycosylation Mechanisms at the S_N1–S_N2 Interface

Polarimetry as a method for studying the structure of aqueous carbohydrate solutions: correlation with other methods

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Bimodal concentration-dependent reactivity pattern of a glycosyl donor: Is the solution structure involved?

Cited by 29 publications

References 81 publications

A Ring Contraction of 2,3-Di-O-Silylated Thiopyranosides To Give Thiofuranosides under Mildly Acidic Conditions

A Ring Contraction of 2,3-Di-O-Silylated Thiopyranosides To Give Thiofuranosides under Mildly Acidic Conditions

The Experimental Evidence in Support of Glycosylation Mechanisms at the SN1–SN2 Interface

Polarimetry as a method for studying the structure of aqueous carbohydrate solutions: correlation with other methods

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The Experimental Evidence in Support of Glycosylation Mechanisms at the S_N1–S_N2 Interface