Regioselective acylation, alkylation, silylation and glycosylation of monosaccharides

Lawandi, Janice; Rocheleau, Sylvain; Moitessier, Nicolas

doi:10.1016/j.tet.2016.08.019

Cited by 95 publications

(46 citation statements)

References 221 publications

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“…After global deacetylation, the 6-O-and 4-O-hydroxy groups of GlcN were protected with a(2naphthyl)methylene acetal to afford compound 8.N ext, we investigated the selective 2-O-protection of IdoA, which is particularly challenging for trans-diaxial 1,2-diols.T reatment of 8 with dibutyltin oxide and benzoyl chloride at 70 8 8Cg ave the desired compound 9 as the exclusive product. Although dibutyltin oxide has been widely used for the regioselective protection of cis-1,2-and di-equatorial trans-1,2-diols, [13] to our knowledge,t his is the first successful application of dibutyltin oxide to the regioselective protection of the di-axial trans-2-O-o r3 -O-positions of IdoA. We found that 9fluorenylmethoxycarbonyl (Fmoc), 2,2,2-trichloroethoxycarbonyl (Troc), and benzoyl (Bz) groups could be selectively installed at the 2-O-position of GlcN-IdoA derivatives, whereas the monochloroacetyl (MCA)g roup could be selectively installed at the 3-O-position, highlighting the synthetic utility of this transformation (Table S4).…”

Section: Resultsmentioning

confidence: 99%

Expedient Synthesis of Core Disaccharide Building Blocks from Natural Polysaccharides for Heparan Sulfate Oligosaccharide Assembly

et al. 2019

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The complex sulfation motifs of heparan sulfate glycosaminoglycans (HS GAGs) play critical roles in many important biological processes. However, an understanding of their specific functions has been hampered by an inability to synthesize large numbers of diverse, yet defined, HS structures. Herein, we describe a new approach to access the four core disaccharides required for HS/heparin oligosaccharide assembly from natural polysaccharides. The use of disaccharides rather than monosaccharides as minimal precursors greatly accelerates the synthesis of HS GAGs, providing key disaccharide and tetrasaccharide intermediates in about half the number of steps compared to traditional strategies. Rapid access to such versatile intermediates will enable the generation of comprehensive libraries of sulfated oligosaccharides for unlocking the “sulfation code” and understanding the roles of specific GAG structures in physiology and disease.

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Section: Resultsmentioning

confidence: 99%

Expedient Synthesis of Core Disaccharide Building Blocks from Natural Polysaccharides for Heparan Sulfate Oligosaccharide Assembly

et al. 2019

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“…During the last 30 years, numerous procedures to avoid or decrease protecting group manipulations have been developed for the synthesis of a single oligosaccharide or an oligosaccharide library,, such as glycosylation on unprotected or partially protected acceptors, and random glycosylation on unprotected acceptors. Thiem et al published reviews on random glycosylation in 2008, and glycosylation on unprotected acceptors in 2014.…”

Section: Introductionmentioning

confidence: 99%

Glycosylation on Unprotected or Partially Protected Acceptors

Ding

Prasad²,

Wang

2020

Eur J Org Chem

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Over the last 30 years, there have been several methods developed for the synthesis of oligosaccharides, such as combinatorial synthesis, programmable one‐pot glycosylations, pre‐activation‐based chemo‐selective glycosylation strategy, random glycosylation, chemo‐enzymatic processes, and automated platforms. Distinguishing hydroxyl groups in carbohydrate monomers form the crux of oligosaccharides synthesis. The protection of hydroxyl groups stops glycosylation at undesired positions on carbohydrates, but additional steps are required to install and remove the protecting groups. The targeted functionalization of carbohydrates relies mostly on the protection of hydroxyl groups that are not supposed to undergo glycosylation and to leave the hydroxyl group unprotected where the glycosylation should occur. Numerous procedures to avoid or decrease protecting group manipulations have been developed for the synthesis of a single or an oligosaccharide library, such as glycosylation on unprotected or partially protected acceptors, and random glycosylation on unprotected acceptors. In this review, overall approaches for glycosylation on unprotected or partially protected acceptors in the synthesis of oligosaccharides and oligosaccharide libraries are summarized, the glycosylation on unprotected or partially protected carbohydrate acceptors with or without tin or boron mediation, and random glycosylation on unprotected or partially protected acceptors in solution phase or on solid phase are discussed.

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“…Besides controlling the anomeric configuration during glycosylation, the site-selective derivatization of hydroxyl groups on the sugar ring constitutes a key challenge in carbohydrate synthesis. [24][25][26] Over the past decades, several methods have been introduced to generate subtle differences in reactivity of the hydroxyl groups, such as the use of organotin derivatives, [27,28] the generation of arylboronic acid complexes, [29][30][31][32] the use of cyclic organosilicon derivatives, [33] variation of the counterion of the acylating agent under nucleophilic catalysis, [34] and control of the intramolecular hydrogen bonding network. [35,36] Additional strategies are based on the use of enzymes, [37][38][39][40] palladium(0) nanoparticles, [41] and sterically hindered reagents.…”

Section: Introductionmentioning

confidence: 99%

Regioselective Ring Opening of 1,3‐Dioxane‐Type Acetals in Carbohydrates

et al. 2018

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The (regio)selective manipulation of hydroxyl groups in carbohydrates has been a long‐standing challenge in (bio)organic chemistry and continues to trigger the creative minds of many chemists. Among the various strategies that have been developed to address these issues, mostly relying on multistep procedures involving the use of protecting groups, the regioselective ring opening of 1,3‐dioxane‐type acetals has emerged as a powerful tool. Since the first papers on this subject appeared in the 1960s, a large variety in both acetal types and reagents for their partial cleavage has come to the fore. This review aims to give an overview of the different carbohydrate‐derived ring systems, ranging from four‐ to seven‐membered rings, on which regioselective ring‐openings have been performed, along with the appropriate reagents and combinations thereof. The transformations on 1,3‐dioxane acetals fit in a larger group of ring opening reactions of structurally related cyclic functional groups, including 1,3‐dioxolanes, 1,3‐oxathianes, orthoesters, cyclic carbonates and silylene acetals, which will not be discussed in this review.

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Regioselective acylation, alkylation, silylation and glycosylation of monosaccharides

Cited by 95 publications

References 221 publications

Expedient Synthesis of Core Disaccharide Building Blocks from Natural Polysaccharides for Heparan Sulfate Oligosaccharide Assembly

Expedient Synthesis of Core Disaccharide Building Blocks from Natural Polysaccharides for Heparan Sulfate Oligosaccharide Assembly

Glycosylation on Unprotected or Partially Protected Acceptors

Regioselective Ring Opening of 1,3‐Dioxane‐Type Acetals in Carbohydrates

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