Synthese von 2‐Acyloxy‐ und 2‐Alkyloxy‐3‐ketoglycalen und ihren Bromaddukten

Kunz, Horst; Weiß, Joachim E.; Müller, Martin Anton

doi:10.1002/jlac.198319830912

Cited by 9 publications

(4 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This approach led to 3,5, and cellobiose-derived 8 in overall yields of 18 -20% Eor the six steps from glucose and cellobiose, respectively. In the same utility rangeoverall yields of about 20%, based on glucoseis the alternate approach, employing 3~O-benzyl-~-glucose as a readily accessible intermediate, which by the sequence acylation (or methylation), hydrogenolysis of the benzyl group, and oxidation with R u 0 4 or dimethyl sulfoxide/acetic anhydride, that entails elimination of the anomeric group, afforded the dihydropyranones 3",'*), 4 lo), 6 I*), and 7 12).…”

mentioning

confidence: 99%

Enantiomerically Pure Building Blocks from Sugars, 10 2,3‐Dihydropyranones with Contiguous Chiral Centers: Practical Routes for Their Aquisition and Evaluation of their Reaction Potential

1989

View full text Add to dashboard Cite

Due to their ready accessibility') and the almost inexhaustible prodigality of addition reactions to the enediol double bond3), hydroxyglycal esters of type I have proven to be key intermediates for the preparation of a large variety of versatile chiral building blocks 4), particularly suited for the synthesis of non-carbohydrate natural products in enantiomerically pure form4,'). Similar synthetic potential attends to the 3-0x0 analogues of hydroxyglycal esters, i.e. acylated dihydropyranones of type 11, which in view of the carbonyl-engendered reasonance stabilization (cf. arrows in 11) and the lack of a displaceable allylic acyloxy group are apt to undergo addition reactions with high regio-and diastereoselectivity . OR 84R o + J r , Ro7$yR R'Although a sizable number of dihydropyranones of type 11 have been recorded in literatureinvariably prepared from D-glucose or its disaccharides and hence of D-erythroor (R,R)-configurationtheir accessibility is all but satisfactory. The free enediolone 1, for example, is a capricious, instable compound which has been obtained in low yield by base-induced elimination of methanol from methyl P-D-ribohexosid-3-ulose6), whereas the acetyl derivatives 2 and 3 evolved from studies on the base-catalyzed degradation of carbohydrates',') comprising acetylated hexos-2-uloses as key intermediates and a multistep sequence from D-glucose clearly inadequate for their obtention on a preparative scale.Subsequent developments of alternate routes for their preparation proceeded along two veins, one making use of the facile peroxidation of hydroxyglycal esters (I) to peracylglycos-2-uloses9) and their ready conversion into 2,3-enediol esters by acetylation" in which the anomeric substituent is eliminated with concomitant liberation of the carbonyl function simply by treatment with A1Cl3 lo). This approach led

show abstract

mentioning

confidence: 99%

Enantiomerically Pure Building Blocks from Sugars, 10 2,3‐Dihydropyranones with Contiguous Chiral Centers: Practical Routes for Their Aquisition and Evaluation of their Reaction Potential

1989

View full text Add to dashboard Cite

show abstract

“…We therefore conclude that the deglycosylation reaction is caused by the Pd catalyst, either via an E1cB elimination or via overoxidation (see Figure S2 for a proposed mechanism). In the first pathway, enolization of the carbonyl group is followed by E1cB elimination of the anomeric substituent [33,34] . In the second pathway, C2‐OH is oxidized, which can then enolize and after formation of an hemiaminal hydrolysis takes place.…”

Section: Resultsmentioning

confidence: 99%

“…In the first pathway, enolization of the carbonyl group is followed by E1cB elimination of the anomeric substituent. [33,34] In the second pathway, C2-OH is oxidized, which can then enolize and after formation of an hemiaminal hydrolysis takes place. This was supported by the observation of small signal corresponding to the overoxidized product (m/z = 937, (Figure 2C, Figure 2D).…”

Section: Chemoselective Oxidation Of Model Glycopeptidesmentioning

confidence: 99%

Palladium‐Catalyzed Oxidation of Glucose in Glycopeptides**

et al. 2022

View full text Add to dashboard Cite

Selective modification of carbohydrate residues in glycopeptides is highly relevant as a tool in glycobiology. In particular, oxidation allows for subsequent ligation with a label or handle and can be effectuated enzymatically or chemically. Chemical oxidation of carbohydrate residues in glycopeptides is nearly invariably done using periodate cleavage, leading to aldehydes. In this work, we applied palladium-catalyzed oxidation for the same purpose. The catalyst, [(neocuproine)PdOAc] 2 OTf 2 , developed for the site-selective oxidation of mono-and oligosacchar-ides on preparative scale, proved suitable for the oxidation of glucose residues in a series of glucopeptides. Careful optimization of the reaction conditions is necessary to get acceptable conversions without excessive over-oxidation of amino acid side-chains, in particular threonine. The resulting carbonyl function can be used for an oxime-ligation to biotin. A protocol for the analysis of the products using mass spectrometry is also reported.

show abstract

“…In the first pathway, enolization of the carbonyl group is followed by E1cB elimination of the anomeric substituent (see Figure S2 for a proposed mechanism). 44,45 In the second proposed pathway, C2-OH is oxidized, which can then enolize and after formation of an hemiaminal hydrolysis takes place. A small signal corresponding to the overoxidized product (m/z = 939) was observed (Figure 2).…”

Section: Chemoselective Oxidation Of Model Glycopeptidesmentioning

confidence: 99%

Site-Selective Palladium-Catalyzed Oxidation of Glucose in Glycopeptides

Nr¹,

Yakovlieva²,

Marinus³

et al. 2021

Preprint

View full text Add to dashboard Cite

Here we report a novel method of site-selective oxidation of glucose moieties on individual glycopeptides and on a mixture of tryptic glycopeptides. The organometallic catalyst [(neocuproine)PdOAc]2OTf2, that was previously shown to perform regioselective C3-oxidation of glucosides, was used in the scope of this work. The selectivity of the catalyst towards glucose and the sensitivity of specific amino acid residues to oxidation was explored by screening a select panel of glycopeptides in the oxidation reactions. We reveal that glucosylated peptides are more readily oxidized compared to galactosylated peptides, and Thr/Ser-oxidation is a concomitant side-reaction. The oxidation methodology was also applied to the complex mixture of tryptic glucopeptides that was generated from the fragment of Haemophilus influenzae adhesin glycoprotein. The resulting keto-group of the glucose was further transformed into an oxime functionality, which allows introduction of various groups of interest. The methodology outlined in this work will allow to perfrom late-stage modification of glucopeptides as well as selective oxidation and functionalization of tryptic glucopeptides for proteomics analysis.

show abstract

Synthese von 2‐Acyloxy‐ und 2‐Alkyloxy‐3‐ketoglycalen und ihren Bromaddukten

Cited by 9 publications

References 28 publications

Enantiomerically Pure Building Blocks from Sugars, 10 2,3‐Dihydropyranones with Contiguous Chiral Centers: Practical Routes for Their Aquisition and Evaluation of their Reaction Potential

Enantiomerically Pure Building Blocks from Sugars, 10 2,3‐Dihydropyranones with Contiguous Chiral Centers: Practical Routes for Their Aquisition and Evaluation of their Reaction Potential

Palladium‐Catalyzed Oxidation of Glucose in Glycopeptides**

Site-Selective Palladium-Catalyzed Oxidation of Glucose in Glycopeptides

Contact Info

Product

Resources

About