Preparation of diversely protected 2-azido-2-deoxyglycopyranoses from glycals

Czernecki, S.; Ayadi, Ebtissam

doi:10.1139/v95-046

Cited by 31 publications

(8 citation statements)

References 20 publications

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“…Their ratio was calculated from integral intensities of the corresponding anomeric proton signals (Figure 1). The NMR data of compounds 2 – 5 correlated well with the published data [18,20] . Unfortunately, attempts to reproduce the reported high yield of 2 were unsuccessful, the total yield of only 48 % was achieved (entry 2, Table 1).…”

Section: Resultssupporting

confidence: 78%

“…Azidophenylselenylation reactions of acetylated glucal 18 were also examined on a 3.7 mmol scale under three types of conditions described above for galactal 1 (Table 1, entries 2, 3, 5). Under Czernecki's conditions, [18] the reaction produced an inseparable mixture of gluco and manno 2‐azido‐2‐deoxy‐α‐phenylselenoglycosides 19 and 20 , and 2‐deoxy‐2‐phenylseleno‐α‐mannosyl azide 21 (Table 3, entry 1) that were identified by NMR spectroscopy; NMR data for 19 and 20 were in agreement with published values [41] . The product ratio (5 : 5 : 2) was calculated from integral intensities of corresponding signals for anomeric protons in the 1 H NMR spectrum (Figure 3, Table 3).…”

Section: Resultsmentioning

confidence: 97%

“…The NMR data of compounds 2-5 correlated well with the published data. [18,20] Unfortunately, attempts to reproduce the reported high yield of 2 were unsuccessful, the total yield of only 48 % was achieved (entry 2, Table 1). Poor scalability of heterogeneous APS was already mentioned earlier.…”

Section: Resultsmentioning

confidence: 99%

“…in 1991 [14] . Later, Santoyo‐González [15] and Czernecki [16–18] applied this protocol to d ‐glucal and d ‐galactal for preparation of phenyl 2‐azido‐2‐deoxy‐1‐seleno‐α‐ d ‐gluco‐ and galactopyranosides. However, insufficient reproducibility and scalability of the heterogeneous APS reaction was mentioned [19] .…”

Section: Introductionmentioning

confidence: 99%

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Further Investigation of the 2‐Azido‐phenylselenylation of Glycals

et al. 2021

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Derivatives of 2‐azido‐2‐deoxysugars are widely applied as precursor of 2‐amino‐2‐deoxysugars in the synthesis of various oligosaccharides of bacterial, fungal and mammalian origin. Heterogeneous or homogeneous azidophenylselenylation (APS) of glycals, i. e., reaction of glycals with Ph2Se2, PhI(OAc)2 and NaN3 or TMSN3 as azide radical donors, is a straightforward way to phenyl 2‐azido‐2‐deoxy‐1‐selenoglycosides that can be directly used as glycosyl donors. However, heterogeneous APS is characterized by insufficient reproducibility and scalability. We have studied the effect of reaction conditions on the product distribution in heterogeneous APS of 3,4,6‐tri‐O‐acetyl‐d‐galactal and found the conditions that enabled reliable preparation of crystalline phenyl 2‐azido‐2‐deoxy‐1‐seleno‐α‐d‐galactopyranoside triacetate in yield of 58 % on the 3.7 mmol scale. APS of 3,4,6‐tri‐O‐acetyl‐d‐glucal under those conditions produced a ∼1 : 1 mixture of phenyl 2‐azido‐2‐deoxy‐1‐seleno‐α‐d‐gluco‐ and mannopyranosides in total yield of 78 %. Acetoxyphenylselenylation of differently protected galactals and 3,4,6‐tri‐O‐acetyl‐d‐glucal under the action of Ph2Se2 and PhI(OAc)2 has been shown to be a convenient method for the synthesis of 1‐O‐acetyl‐2‐seleno‐2‐deoxy derivatives, valuable intermediates in chemistry of 2‐deoxysugars. 2‐Seleno‐2‐deoxy sugars were characterized in detail by NMR data including 77Se chemical shifts and nJSe−H coupling constant values.

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Section: Resultssupporting

confidence: 78%

Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Further Investigation of the 2‐Azido‐phenylselenylation of Glycals

et al. 2021

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“…The galactosyl phosphate derivative 357 , the coupling partner of Man-I derivative 354 , was synthesized from the previously reported 2-azido selenoglycoside 361 146 in four steps, including regioselective benzylidene cleavage, napthylmethylation at O-4, Staudinger reduction followed by N-trichloroacetylation, and finally formation of the glycosyl phosphate by treatment with NIS/dibutyl phosphate. The Man-I acceptor 354 and galactosyl phosphate donor 357 combined in the presence of TMSOTf to give the β disaccharide 362 , which was treated with DDQ to remove the Nap group, furnishing compound 363 quantitatively over two steps.…”

Section: Diversity-oriented Approachesto Gpi Synthesismentioning

confidence: 99%

Chemical Synthesis of Glycosylphosphatidylinositol Anchors

Swarts

Guo

2012

Advances in Carbohydrate Chemistry and Biochemistry

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Many eukaryotic cell-surface proteins and glycoproteins are anchored to the plasma membrane by glycosylphosphatidylinositols (GPIs), a family of glycolipids that are post-translationally attached to proteins at their C-termini. GPIs and GPI-anchored proteins play important roles in many biological and pathological events, such as cell recognition and adhesion, signal transduction, host defense, and acting as receptors for viruses and toxins. Chemical synthesis of structurally defined GPI anchors and GPI derivatives is a necessary step toward understanding the properties and functions of these molecules in biological systems and exploring their potential therapeutic applications. In the first part of this comprehensive article on the chemical synthesis of GPIs, classic syntheses of naturally occurring GPI anchors from protozoan parasites, yeast, and mammals are covered. The second part of the article focuses on recent diversity-oriented strategies for the synthesis of GPI anchors containing unsaturated lipids, “click chemistry” tags, and highly branched and modified structures.

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Advances in Free Radical Reactions of Organoselenium and Organotellurium Compounds

Press

Back²

2011

Patai's Chemistry of Functional Groups

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Free radical reactions of organoselenium and tellurium compounds have been widely studied and exploited since the first two volumes of this series appeared. Alkyl aryl selenides and tellurides undergo alkyl C‐Se or C‐Te cleavage with stannanes or silanes to generate alkyl radicals that can be employed in reductions, allylations and both intermolecular and intramolecular additions to a large variety of unsaturated substrates, terminated by either hydrogen or arylchalcogen transfer. Selenoesters, telluroesters and related species generate acyl radicals that are useful in overall decarboxylations of carboxylic acids, and in addition and radical cyclization processes, including cascade reactions of polyenes to afford polycyclic products. Homolytic cleavage of diselenides and ditellurides produces selenyl and telluryl radicals that can be employed in additions to unsaturated acceptors, while the dichalcogenides themselves function as effective trapping agents for radicals produced in a variety of other ways, as from Barton thiohydroxamates. Selenols are efficient hydrogen donors that are of importance in kinetic studies of radical processes. When selenium and tellurium are joined to other heteroatoms, the resulting reagents effect radical 1,2‐additions to unsaturated substrates, as in the case of selenosulfonation and azidoselenenylation reactions. Other radical processes include oxidations, S H 2 substitutions, single electron transfers, extrusions and fragmentations, and reactions performed on solid supports. The synthetic utility of these processes, as well as mechanistic considerations are covered in this chapter.

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Preparation of diversely protected 2-azido-2-deoxyglycopyranoses from glycals

Cited by 31 publications

References 20 publications

Further Investigation of the 2‐Azido‐phenylselenylation of Glycals

Further Investigation of the 2‐Azido‐phenylselenylation of Glycals

Chemical Synthesis of Glycosylphosphatidylinositol Anchors

Advances in Free Radical Reactions of Organoselenium and Organotellurium Compounds

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