Preparation of 2,3,4,6-Tetra-<i>O</i>-benzyl-<scp>d</scp>-mannose

Koto, Shinkiti; Morishima, Naohiko; Miyata, Yoko; Zen, Shonosuke

doi:10.1246/bcsj.49.2639

Cited by 110 publications

(28 citation statements)

References 19 publications

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“…16.5 g (48.5 mmol, 75%)) of 2 was obtained as a white powder. Solvation and reconcentration of 2 gave a fast crystallizing residue, which is nearly insol- 13.8 g (23.6 mmol) of 11 was dissolved in a mixture of 300 ml of acetonitrile, 10 ml of water and 1 ml of hydrochloric acid (37%). 4.2 g (23.8 mmol) of N-bromosuccinimide was added and the solution was stirred for 20 min.…”

Section: Methodsmentioning

confidence: 99%

Convenient Syntheses of 2,3,4,6‐Tetra‐O‐Alkylated D‐Glucose and D‐Galactose

Käsbeck

Kessler

1997

Liebigs Ann./Recl.

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Convenient syntheses of the 2,3,4,6-tetra-O-benzylated and -allylated o-glucopyranoses 1 and 2 and the corresponding D-galactopyranoses 3 and 4 are described. The D-glucose derivatives 1 and 2 were obtained from inexpensive sucrose by peralkylation and subsequent acid hydrolysis. In this reaction sequence an alkylated D-fructofuranosyl cation is generated which was trapped by different nucleophiles to afford 4-benzyloxymethylenefurfural ( 8 ) and the alkylated D-fructosides 7, 8 and 10. On the other hand 2,3,4,6-tetra-O-benzyl-~-ga- In this paper we describe eficient methods for the synthesis of 2,3,4,6-tetra-o-benzylated and -allylated D-glucose 1 and 2 by alkylation of sucrose and the preparation of the protected D-galactose derivatives 3 and 4. The allylated compounds 2 and 4 represent synthetically useful building blocks since ally1 ethers are important relatively acid-stable protecting groups besides benzyl ethers without neighboring-group participation.Acid hydrolysis of octa-0-methylsucrose has been known since 1 903 [14], the analogous cleavage of octa-0-benzylsucrose was published in 1970[151 but did not receive further attention for the preparation of 2,3,4,6-tetra-O-benzyl-~-glucose (1). We reinvestigated this reaction by using perbenzylated as well as perallylated sucrose 5 and 9, which are easily accessible by different alkylation procedures ['2,'6.i7] Using water as nucleophile in the cleavage of octa-0-benzylsucrose 5, we succeeded in crystallizing 2,3,4,6-tetra-0-benzybglucose (1) directly in high yields. 4-Benzyloxymethylenefurfural (6) was isolated as a by-product.

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Section: Methodsmentioning

confidence: 99%

Convenient Syntheses of 2,3,4,6‐Tetra‐O‐Alkylated D‐Glucose and D‐Galactose

Käsbeck

Kessler

1997

Liebigs Ann./Recl.

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“…For the manno series, we chose the b-pyridyl sulfone 25, the preparation of which is outlined in Scheme 6. The readily accessible tetrabenzylmannopyranose 26 [28] was converted to the a-trichloroacetimidate 27, followed by the introduction of a pyridylsulfide unit by treatment of the latter with mercaptopyridine and catalytic amounts of BF 3 :Et 2 O. This afforded a chromatographically separable mixture of a and b anomers 28 and 29.…”

Section: Reductive Samariation Of D D-gluco and D D-galactopyranosyl mentioning

confidence: 99%

A General Approach to 1,2-trans-C-Glycosides via Glycosyl Samarium(III) Compounds

et al. 1998

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Abstract:The samarium diiodide reduction of glycosyl pyridyl sulfones with ketones or aldehydes under Barbier conditions leads to the instantaneous and stereospecific formation of 1,2-trans-C-glycosides in good to acceptable yields. Mannosyl pyridyl sulfones 5 a ± c,h produce a-C-glycosides 7 ± 10, 12, 13, 15 ± 17, and 57 in yields up to 86 % with minimal b elimination. In contrast, glucosyl pyridyl sulfones 19 a and 19 b lead to the corresponding b-C-glycosides 20 ± 22 in yields up to 56 % with increased b elimination. Similarly, galactosyl pyridyl sulfones 23 a and 23 b afford b-C-galactoside 24. The stereochemical discrepancies between these reactions are probably based on the intermediacy of a common a-anomeric glycosyl samarium(iii) compound (kinetic product) with an axially oriented C1 ± Sm bond after reduction of the pyridyl sulfone group. The thermodynamically more stable anomeric organosamarium with an equatorially oriented C1 ± Sm bond may then be obtained by a least energy pathway in the form of either a conformational ring-flip (in the manno series) or as a configurational change (in the gluco or galacto series). The tendency towards b elimination can be explained by the preference of glycosyl organosamarium compounds to undergo an unprecedented syn-elimination mechanism more easily achieved in the gluco and galacto series. C2-Unsubstituted 2-deoxy sugars display little or no stereoselectivity at C1 upon C-glycosylation.

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“…[21] As shown in Scheme 1, the preparation of compounds 10, 11, and 12 was achieved in six steps starting from the galactose derivative 15 [22] by way of a chain extensionÀaminationÀcyclization sequence. The key synthetic step involved an intramolecular amidomercuration reaction.…”

Section: Naturally Occurring Iminosugars As Immunomodulating Agentsmentioning

confidence: 99%

Iminosugars as Immunomodulating Agents: Synthesis and Biological Activities of 1‐Deoxynojirimycin and Related Compounds

Qin

2015

Israel Journal of Chemistry

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Iminosugars are an extremely interesting and versatile class of compounds and have many potential therapeutic applications. However, the use of iminosugar derivatives as immunomodulating agents is an area that is less explored. This review describes recent advances in the field of iminosugars as immunomodulating agents with a particular emphasis on 1‐deoxynojirimycin analogues and related compounds. Both chemical and biological aspects concerning their preparation and/or occurrence in nature, as well as their immunomodulatory properties, are discussed.

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Preparation of 2,3,4,6-Tetra-O-benzyl-d-mannose

Abstract: 2,3,4,6-Tetra-O-benzyl-d-mannopyranose was prepared from methyl α-d-mannopyranoside. Improved preparations of 2,3,4,6-tetra-O-benzyl-α-d-glucopyranose and -galactopyranose are described.

Cited by 110 publications

References 19 publications

Convenient Syntheses of 2,3,4,6‐Tetra‐O‐Alkylated D‐Glucose and D‐Galactose

Convenient Syntheses of 2,3,4,6‐Tetra‐O‐Alkylated D‐Glucose and D‐Galactose

A General Approach to 1,2-trans-C-Glycosides via Glycosyl Samarium(III) Compounds

Iminosugars as Immunomodulating Agents: Synthesis and Biological Activities of 1‐Deoxynojirimycin and Related Compounds

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