Einwirkung von Quecksilbersalzen auf Aceto‐halogenzucker, IV. Mitteil.: Direkte Darstellung der Alkylbioside der α‐Reihe

Zemplén, Geža; Gerecs, Árpád

doi:10.1002/cber.19300631008

Cited by 43 publications

(9 citation statements)

References 3 publications

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“…New methodologies are still being developed with more advanced variations in the mechanistic pathways. Later Zémplén and Gerecs, and subsequently Helferich and Wedermeyer, illustrated the principle of the metal(II) salt‐induced removal of leaving groups . With the general standardization of glycosyl protocols, efforts were made to control the stereochemical outcome of glycosylations.…”

Section: General Aspectsmentioning

confidence: 99%

Chemical O‐Glycosylations: An Overview

2016

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The development of glycobiology relies on the sources of particular oligosaccharides in their purest forms. As the isolation of the oligosaccharide structures from natural sources is not a reliable option for providing samples with homogeneity, chemical means become pertinent. The growing demand for diverse oligosaccharide structures has prompted the advancement of chemical strategies to stitch sugar molecules with precise stereo‐ and regioselectivity through the formation of glycosidic bonds. This Review will focus on the key developments towards chemical O‐glycosylations in the current century. Synthesis of novel glycosyl donors and acceptors and their unique activation for successful glycosylation are discussed. This Review concludes with a summary of recent developments and comments on future prospects.

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Section: General Aspectsmentioning

confidence: 99%

Chemical O‐Glycosylations: An Overview

2016

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“…Haq aiid Whelan (13) synthesized nigerose, compound 4 of this paper, by a chemically related route. The modification of the Koenigs-Knorr reaction involving the use of mercuric cyanide as condensing agent, introduced by ZemplCn and Gerecs (14) and used by Matsitda (15) for the synthesis of a-D-glucopyranosides, failed (9) to provide 1 but did provide nigerose (15,16). The chemical nature of this approach to the synthesis of a-D-glucopyranosides remains obscure (17) but it has provided syntheses of a number of complex a-D-glucopyrar~osides in low yield (18)(19)(20).…”

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confidence: 99%

Chemical Syntheses of α-Linked Disaccharides

Lemieux¹,

James²,

Nagabhushan³

1973

Can. J. Chem.

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Chemical syntheses of six a-linked disaccharides are described, namely, 6-0-(a- [Traduit par le journal]DCan J Cheili 51 J? (1973) This paper presents syntheses of the six a-linked disaccharides (I to 6) from previously reported (1) oximino-disaccharide structures; namely, the tri-0-acetyl-2-oxin7ino-a-D-arabiko-hexopyranosyl and tri-0-acetyl-2-oxirnino-a-D-/jlxo-hexopyranosyl derivatives of 1,2;5,6-di-0-isopropyiidene-a-D-glucofuranose and of 1,2;3,4-di-0-isopropylidene-a-D-galaclopyranose. The latter compounds were deoximated (2) and the resulting ketonic substances were reduced with sodium borohydride (3) without prior purification. In the preparation of compounds 4, 5, and 6, the use of acetaldehyde in acetonitrilehydrochloric acid reagent (2) for deoximation caused substantial loss of the acid labile 5,6-0-isopropylidene protecting group. However, in the preparation of compounds 1, 2, and 3, deoxirnation under similar conditions caused only small losses of the 0-In view of the high degree of stereoselectivity observed in the reductions to a-D-glucopyranosides (3), the preparations of compounds B and 4 proceeded with little difficulty in 54 and 67% yields, respectively. Although both the interme-propylidene-a-u-galactopyranose and its tetraacetate failed to crystallize, both 3-0-(a-D-glucopyranosyl) -1,2 i5.6-di-0-isopropylidene-a-D-glucofuranose and its tetraacetate were obtained in crystalline condition.As previously reported (3), the reduction of a tri-0-acetyl-a-D-lyxo-hexosuloside with sodium borohydride leads to a mixture of galactosides and talosides. 6-0-(Tetra-0-acetyl-x-D-galactopyranosyl) -1,2:3,4-di-0-isopropylidene-a -D-galactopyranose was obtained crystalline in 51%yield and was readily separated from 6-0-(tetraisopropylidene groups. Treatment of the crude 0-acetyl-a-D-talopyranosy1)-1 ,2:3,4-di-0-isoproketones in these cases with 2,2-dirnethoxypropane pylidene-a-D-galactopyranose (30$/: yield as a andp-to!uenesulfonic acid monohydrate re-intro-syrup) by column chromatography on silicic acid. duced these groups in near quantitative yields. This was not the case in the preparation of compounds 4, 5, and 6. Therefore, lor the syl~tllesis of these compounds deoximation under neutral conditions with titanium trichloride (3, 4) was used. Reduction followed by 0-acetylation enabled compounds 1 to 4 to be isolated as the O-(tetra-8-acetyl-31-~-P1exopyranosy~)-di-0-isopropylidene-D-hexoses. 'Presented at the ihlst National American Chemical Society Meeting, Eos Angeles, California, March 28,1971. 'University of Alberta Postdoctoral Fellow, 1970. 3Professional Research Associate, 1970 Column chromatography on a resin in the hydroxide fornu (5) was used to separate 3-0-(a-Dgalactopyranosyl) -1,2:5,6-di -0 -isopropylidener-D-glucofuranose from the talo-isomer. Both compou~lds were obtained crystalline. The disaccharides (I to 6) were prepared from the di-0-isopropylider?e derivatives by hydrolysis of the isopropylidene groups using aqueous triAuoroacetic acid (6) followed by chromatographic purificat...

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“…Lemieux and Brice (3) have shown that the treatment of pentaacetyl-0-Dglucopyranose (I) with stannic chloride in chlorofornl solutiol~ resulted in a rapid dissociation of the C1 to acetoxy group bond to yield carbonium ions of which the resonance stabilized 1,2-cyclic ion (11) is the predominant type. Treatment of 1,2,3,4-tetraacetyl-/3-D-glucose under these conditions yielded the internal glucoside, triacetyl-D-glucosan (1,5) P (1, 6) (3).…”

Section: Introductionmentioning

confidence: 99%

A NEW SYNTHESIS OF Β-Glucopyranosides

Lemieux¹,

Shyluk²

1953

Can. J. Chem.

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Reaction of equivalent amounts of pentaacetyl-P-D-glucopyranose and methanol in benzene or chloroform solution in the presence of 0.5 or more moles of stannic chloride oer mole of methanol pave 50-60Yn vields of methvl tetra-acetyl-8-u-gl~~copyranosidc. a-Xcetocl~lorogl~~cose was ;I by-protltlct of thc rcaction. The mechanisn~ of the reaction is disct~ssed. 'l'he n~etl~otl was applicaClle for the preparation of phenyl tetraacetyl-13-D-glucopyranoside. INTRODUCTIONLemieux and Brice (3) have shown that the treatment of pentaacetyl-0-Dglucopyranose (I) with stannic chloride in chlorofornl solutiol~ resulted in a rapid dissociation of the C1 to acetoxy group bond to yield carbonium ions of which the resonance stabilized 1,2-cyclic ion (11) is the predominant type. Treatment of 1,2,3,4-tetraacetyl-/3-D-glucose under these conditions yielded the internal glucoside, triacetyl-D-glucosan (1,5) P (1, 6) (3). Thus, it was reasonable to expect that treatment of pentaacetyl-/3-D-glucopyranose with stannic chloride in cl~loroform containing an alcohol \srould lead to glucoside formation. Since the ion I1 would predominate and the reaction of this ion with the alcohol under the ,prevailing acidic conditions would be accon~panied by an inversion of the anomeric center, it was expected that the initial reaction 0-0-0-HC-OAcproduct would be the acetylated P-D-glucopyranoside (111). Since pentaacetyl-P-~glucopyranose was found to be rapidly dissociated by stannic chloride (3), it was anticipated that the p-glucoside would be fonned rapidly a t the boiling point of the reaction mixture. Pacsu (8) has shown that stannic chloride can catalyze the anomerization of methyl tetraacetyl-p-D-glucopyranoside only slowly. Consequently, it was expected that the reaction of pentaacetyl-P-D-glucopyranose with methanol in the presence of stannic chloride would afford a good yield of methyl tetraacetyl-P-D-glucopyranoside. Lindberg (5) has shown that the rate of anomerization of a P-glucopyranoside depends greatly on the nature of theaglucon.

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Einwirkung von Quecksilbersalzen auf Aceto‐halogenzucker, IV. Mitteil.: Direkte Darstellung der Alkylbioside der α‐Reihe

Cited by 43 publications

References 3 publications

Chemical O‐Glycosylations: An Overview

Chemical O‐Glycosylations: An Overview

Chemical Syntheses of α-Linked Disaccharides

A NEW SYNTHESIS OF Β-Glucopyranosides

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