The use of O-trifluoroacetyl protection and profound influence of the nature of glycosyl acceptor in benzyl-free arabinofuranosylation

Abronina, Polina I.; Fedina, Ksenia G.; Podvalnyy, Nikita M.; Zinin, Alexander I.; Chizhov, Alexander O.; Kondakov, N. N.; Торгов, В. И.; Kononov, L. O.

doi:10.1016/j.carres.2014.05.017

Cited by 39 publications

(16 citation statements)

References 46 publications

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“…The influence of the acceptor on the outcome of glycosylation reactions, evident to every practitioner of the art, and the source of Paulsen’s oft-quoted comment on every glycosylation reaction being different, is illustrated many times over in Barresi and Hindsgaul’s catalog of all glycosylation reactions published in the year 1994 . Systematic studies, however, are more limited and begin with the 1991 publication of Spijker and van Boeckel comparing the silver triflate-promoted reaction of a pair of enantiomeric fucosyl bromides with a single enantiomerically pure acceptor (Scheme ), for which the reversal in selectivity was interpreted in terms of Horeau’s concept of double diastereodifferentiation and matched and mismatched pairs. , Further examples of the same phenomenon were reviewed through 2009 by Bohé and Crich, and the effect continues to be invoked even if not always rigorously established. − It follows from the concept of double diastereodifferentiation that different glycosyl donors will exhibit differing regioselectivity in their coupling reactions with di- and polyols and, self-evidently, with different acceptor alcohols as commented in the reciprocal donor–acceptor selectivity principle of Fraser-Reid and co-workers. , …”

Section: Influence Of the Acceptormentioning

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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Section: Influence Of the Acceptormentioning

confidence: 99%

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

et al. 2018

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“…Ito and co-workers studied the influence of tethering the 3- and 5-OH by a 3,5- O -(tetraisopropyldisilylene)acetal and also found the arabinofuranolysations to be β-selective, despite the more flexible system [ 63 ]. Interestingly it was recently found that exchanging the 3,5-DTBS group with trifluoroacetates retained a high β-selectivity, which suggests that the stereoselectivity is also related to the deactivating properties of the protective group [ 64 ].…”

Section: Reviewmentioning

confidence: 99%

Silyl-protective groups influencing the reactivity and selectivity in glycosylations

Bols¹,

Pedersen²

2017

Beilstein J. Org. Chem.

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Silyl groups such as TBDPS, TBDMS, TIPS or TMS are well-known and widely used alcohol protective groups in organic chemistry. Cyclic silylene protective groups are also becoming increasingly popular. In carbohydrate chemistry silyl protective groups have frequently been used primarily as an orthogonal protective group to the more commonly used acyl and benzyl protective groups. However, silyl protective groups have significantly different electronic and steric requirements than acyl and alkyl protective groups, which particularly becomes important when two or more neighboring alcohols are silyl protected. Within the last decade polysilylated glycosyl donors have been found to have unusual properties such as high (or low) reactivity or high stereoselectivity. This mini review will summarize these findings.

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“…Motivated by the importance of the targets and the fundamental challenges outlined above, several research groups have developed elegant strategies for the construction of 1,2- cis - O -furanoses, including intramolecular aglycone delivery, − conformationally locked oxocarbenium formation, − and selective opening of 2,3-anhydro sugars, among others. − These strategies are highly effective in specific cases, but they each rely on specialized protecting and/or directing groups on the glycosyl donor, thereby limiting their generality.…”

Section: Introductionmentioning

confidence: 99%

Stereospecific Furanosylations Catalyzed by Bis-thiourea Hydrogen-Bond Donors

et al. 2020

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We report a new method for stereoselective O-furanosylation reactions promoted by a precisely tailored bis-thiourea hydrogen-bond-donor catalyst. Furanosyl donors outfitted with an anomeric dialkylphosphate leaving group undergo substitution with high anomeric selectivity, providing access to the challenging 1,2-cis substitution pattern with a range of alcohol acceptors. A variety of stereochemically distinct, benzyl-protected glycosyl donors were engaged successfully as substrates. Mechanistic studies support a stereospecific mechanism in which rate-determining substitution occurs from a catalyst–donor resting-state complex.

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The use of O-trifluoroacetyl protection and profound influence of the nature of glycosyl acceptor in benzyl-free arabinofuranosylation

Cited by 39 publications

References 46 publications

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

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

Silyl-protective groups influencing the reactivity and selectivity in glycosylations

Stereospecific Furanosylations Catalyzed by Bis-thiourea Hydrogen-Bond Donors

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The use of O-trifluoroacetyl protection and profound influence of the nature of glycosyl acceptor in benzyl-free arabinofuranosylation

Cited by 39 publications

References 46 publications

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

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

Silyl-protective groups influencing the reactivity and selectivity in glycosylations

Stereospecific Furanosylations Catalyzed by Bis-thiourea Hydrogen-Bond Donors

Contact Info

Product

Resources

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

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