Stereoselectivity investigation on glycosylation of oxazolidinone protected 2-amino-2-deoxy-d-glucose donors based on pre-activation protocol

Geng, Yixing; Zhang, Lihe; Ye, Xin‐Shan

doi:10.1016/j.tet.2008.03.103

Cited by 52 publications

(26 citation statements)

References 34 publications

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“…Interestingly, in the absence of TTBP, the stereochemistry of the glycoside product was completely reversed giving α‐linked glycoside products. The effect of the base on stereochemical outcome was found to be dependent upon the N‐substituent of the oxazolidinone and protective group on the glycan ring , . In addition to TTBP, other additives such as tetrabutylammonium bromide (TBAB), tetrabutylammonium iodide (TBAI) and thiophene had been investigated to modulate stereoselectivity in pre‐activation of oxazolidinone‐protected amino sugar thioglycoside donors .…”

Section: 23‐oxazolidinone Effectmentioning

confidence: 99%

Pre‐Activation‐Based Stereoselective Glycosylations

Yang

Ramadan

et al. 2018

Eur J Org Chem

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Due to the wide presence of carbohydrates in nature and their crucial roles in numerous important biological processes, oligosaccharides have attracted a lot of attention in synthetic organic chemistry community. Many innovative synthetic methods have been developed for oligosaccharide synthesis, among which the pre-activation based glycosylation is particularly noteworthy. Traditionally, glycosylation reactions are carried out when the glycosyl donor and the acceptor are both present when the promoter is added. In comparison, the pre-activation based glycosylation is unique, where the glycosyl donor is activated by the promoter in the absence of the acceptor. Upon complete donor activation, the acceptor is added to the reaction mixture enabling glycosylation. The key step in any oligosaccharide synthesis is the stereoselective formation of the glycosidic bond. As donor activation and acceptor glycosylation are temporally separated, pre-activation based glycosylation can bestow unique stereochemical control. This review systematically discusses factors impacting the stereochemical outcome of a pre-activation based glycosylation reaction including substituents on the glycosyl donor, reaction solvent, and additives. Applications of pre-activation based stereoselective glycosylation in assembly of complex oligosaccharides are also discussed.

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Section: 23‐oxazolidinone Effectmentioning

confidence: 99%

Pre‐Activation‐Based Stereoselective Glycosylations

Yang

Ramadan

et al. 2018

Eur J Org Chem

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“…Higher temperature and the use of a nonpolar solvent results in an increase in the thermodynamically controlled a-anomer product. [40] Recently, our group demonstrated an application of the oxazolidinone protecting moiety in the construction of the repeating GalpNAc-a-(1!4)-GalpNAc unit in high isolated yield. The use of the N-acetyloxazolidinone-protected thioglycosides as the glycosyl donor and acceptor was effective in providing the exclusive a-stereoselective glycosylation.…”

Section: Oxazolidinones and Carbonatementioning

confidence: 99%

Preactivation: An Alternative Strategy in Stereoselective Glycosylation and Oligosaccharide Synthesis

Yang

Qin

2013

Asian J Org Chem

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The multifaceted biological importance of carbohydrates has made them very popular targets in modern synthetic chemistry. Great progress has been made in stereoselective glycosylation methods and the construction of complex oligosaccharides. This Focus Review highlights the versatile applications of preactivation strategies in stereoselective glycosylation and oligosaccharide synthesis. Recent advances in synthetic methods, such as 4,6-O-benzylidene-acetal-directed b-mannosylation, the 1,2-cis-glycosylation mediated by a chiral auxiliary, the use of an oxazolidinone or carbonate protecting group, and glycosylation with participating additives, are described. Various examples of sequential glycosylation based on preactivation protocols for efficient oligosaccharide assembly are also summarized. Scheme 4. Mechanism for the 4,6-O-benzylidene-directed formation of a-and b-gluco-and mannopyranosides. CIP = contact ion pairs; SSIP = solvent-separated ion pairs Scheme 5. Fluorinated, deoxy, and deoxyfluoro glycosyl donors.

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“…The synthetic cascade to the desirable hexasaccharide 10 is presented in Scheme 1 . Trichloroacetimidate 1 [ 20 , 23 ] was linked with glycosyl acceptor 2 [ 24 – 25 ] using TMSOTf as promoter to obtain disaccharide 4 in 90% yield. Likewise, reaction of glycosyl donor 1 with monosaccharide 3 [ 26 ] and subsequent O -TBS group cleavage with Olah's reagent [ 27 ], afforded disaccharide 5 in 86% yield.…”

Section: Resultsmentioning

confidence: 99%