Synthesis and Reactivity of 4′-Deoxypentenosyl Disaccharides

Padungros, Panuwat; Fan, Renhua; Casselman, Matthew D.; Cheng, Gang; Khatri, Hari; Wei, Alexander

doi:10.1021/jo500449h

Cited by 14 publications

(9 citation statements)

References 61 publications

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“…3c ). As expected, Ph 2 SO/Tf 2 O activating condition was not compatible with unprotected hydroxyl glycosyl donor 50 , 51 . We reached the conclusion that without a free hydroxyl group to react, Bu 2 BOTf inhibited the activation process and slowed down the reaction.…”

Section: Resultssupporting

confidence: 56%

A minimalist approach to stereoselective glycosylation with unprotected donors

Hoang

Báti

et al. 2017

Nat Commun

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Mechanistic study of carbohydrate interactions in biological systems calls for the chemical synthesis of these complex structures. Owing to the specific stereo-configuration at each anomeric linkage and diversity in branching, significant breakthroughs in recent years have focused on either stereoselective glycosylation methods or facile assembly of glycan chains. Here, we introduce the unification approach that offers both stereoselective glycosidic bond formation and removal of protection/deprotection steps required for further elongation. Using dialkylboryl triflate as an in situ masking reagent, a wide array of glycosyl donors carrying one to three unprotected hydroxyl groups reacts with various glycosyl acceptors to furnish the desired products with good control over regioselectivity and stereoselectivity. This approach demonstrates the feasibility of straightforward access to important structural scaffolds for complex glycoconjugate synthesis.

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Section: Resultssupporting

confidence: 56%

A minimalist approach to stereoselective glycosylation with unprotected donors

Hoang

Báti

et al. 2017

Nat Commun

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“…[7] Undoubtedly, ozonolysis has been one of the indispensable methods in synthetic toolbox due to its mild conditions, high atom economy, high efficiency, and compatibility with various functional groups. [8] Despite these obvious benefits, it is relatively underutilized due to the limited accessibility of laboratory ozone generators, which are generally far too expensive for underfunded laboratories, especially in developing countries. [9] Even when the budget is not a problem, investment in the acquisition of dedicated ozonolysis equipment may not be worthwhile if the reaction is to be performed only occasionally.…”

Section: Introductionmentioning

confidence: 99%

Household Ozone Disinfector as An Alternative Ozone Generator for Ozonolysis of Alkenes

et al. 2021

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Ozonolysis is an oxidative cleavage reaction of alkenes with ozone that is indispensable and has found many applications in organic synthesis. However, dedicated laboratory ozone generators are quite expensive equipment and may not be affordable by many laboratories. Recently, lowcost ozone disinfectors have become more common as a household appliance. Herein, we demonstrate the applicability of a household ozone disinfector, which can produce ozone in the order of 10 mmol/h, as alternative equipment for the laboratory scale ozonolysis of alkenes. The ozonolysis of 14 styrene derivatives bearing electron-donating and electron-withdrawing groups on aromatic rings including those with αand β-substituents, as well as 8 natural products containing olefinic moieties were investigated. Ozonolysis of these alkenes at millimole scales proceeded to completion within 30-40 minutes and the carbonyl products were obtained in 68% to quantitative yields. Preparative-scale ozonolysis of 4-methoxystyrene (6.17 g, 46 mmol) was also demonstrated. The reaction proceeded smoothly to yield 4anisaldehyde in 92% yield, which was subsequently converted to p-anisaldehyde dimethyl acetal in 66% yield. This work presents household ozone disinfector as an affordable, compact size, and practical synthetic equipment that does not require extra modification. Thus, the household ozone disinfector offers convenient access to ozonolysis or other reactions involving ozone for low-budget laboratories.

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“…The synthesis of armed donors D1, D3, and D5 (Scheme ) having a 2-naphthylmethyl (NAP or just naphthyl) group at O3 of the reducing end residue started from previously described disaccharides 1 , 4 , and 6 . Acetal 1 was hydrolyzed at 80 °C for 2 h using a solution of 80% AcOH(aq), which gave diol 2 in 82% yield. Compounds 2 , 4 , and 6 had their O -acyl groups removed under standard conditions employing a solution of 1 M NaOMe in MeOH, and the resulting hexaol 3 , pentaol 5 , and tetraol 7 were obtained in 90–92% yield.…”

Section: Resultsmentioning

confidence: 99%

Structure–Reactivity Relationships of Conformationally Armed Disaccharide Donors and Their Use in the Synthesis of a Hexasaccharide Related to the Capsular Polysaccharide from Streptococcus pneumoniae Type 37

2017

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To advance the field of glycobiology, efficient synthesis methods of oligosaccharides and glycoconjugates are a requisite. In glycosylation reactions using superarmed donors, both selectivity and reactivity issues must be considered, and we herein investigate these aspects for differently protected β-linked 2-O-glycosylated glucosyl donors carrying bulky tert-butyldimethylsilyl groups to different extents. The acceptors in reactions being secondary alcohols presents a challenging situation with respect to steric crowding. Conformational pyranose ring equilibria of the superarmed disaccharide donors with axial-rich substituents contained skew and boat conformations, and three-state models were generally assumed. With NIS/TfOH as the promotor, 2,6-di-tert-butyl-4-methylpyridine as the base, and a dichloromethane/toluene solvent mixture, ethyl 1-thio-β-d-glucosyl disaccharide donors having 6-O-benzyl group(s) besides tert-butyldimethylsilyl groups were efficiently coupled at -40 °C to the hydroxyl group at position 3 of glucopyranosyl acceptors to form β-(1 → 2),β-(1 → 3)-linked trisaccharides, isolated in excellent 95% yield. The more axial-rich donors in skew and boat conformations are thus preorganized closer to the assumed transition state in these glycosylation reactions. The developed methodology was subsequently applied in the synthesis of a multibranched hexasaccharide related to the capsular polysaccharide from Streptococcus pneumoniae type 37, which consists of a β-(1 → 3)-linked backbone and a β-(1 → 2)-linked side chain of d-glucosyl residues in disaccharide repeating units.

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Synthesis and Reactivity of 4′-Deoxypentenosyl Disaccharides

Cited by 14 publications

References 61 publications

A minimalist approach to stereoselective glycosylation with unprotected donors

A minimalist approach to stereoselective glycosylation with unprotected donors

Household Ozone Disinfector as An Alternative Ozone Generator for Ozonolysis of Alkenes

Structure–Reactivity Relationships of Conformationally Armed Disaccharide Donors and Their Use in the Synthesis of a Hexasaccharide Related to the Capsular Polysaccharide from Streptococcus pneumoniae Type 37

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