Journal ArticleDOI
A Rapid Route to Hex-1-enopyran-3-uloses
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TLDR
In this article, it was shown that triacetyl glucal can be converted to 6-O-triphenylmethyl ether or 6 O-benzoyl ester to promote solubility in chloroform, and the derivatives are oxidized in that solvent in 12 h or less.Abstract:
Whereas the pseudo-axial 3-hydroxyl group of allal derivatives is known to be inert to manganese dioxide oxidation, the equatorial counterpart in glucal derivatives is shown to be readily oxidized. Thus glucal is converted to the 6-O-triphenylmethyl ether or 6-O-benzoyl ester to promote solubility in chloroform, and the derivatives are oxidized in that solvent in 12 h or less.Acetonation of glucal is readily accomplished in 45 min using 2,2-dimethoxypropane and p-toluenesulfonic acid in dimethylformamide; the product may be oxidized directly either with manganese dioxide or dipyridine chromium oxide. Thus it is possible to obtain 1–3-g quantities of the crystalline acetonated enone from triacetyl glucal (via deacetylation, acetonation, and oxidation) in 3–4 h.If the acetonation medium stands for 2 h methyl 2,3-dideoxy-4,6-O-isopropylidene-α-D-erythro-hex-2-enopyranoside is obtained. The mechanism of its formation in the reaction medium is discussed.read more
Citations
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Journal ArticleDOI
An approach to the synthesis of optically active trichothecenes from tri-O-acetyl-D-glucal☆
TL;DR: A chiral synthesis of the B-C ring system of trichothecenes from tri-O-acetyl-D-glucal by using a photochemical cycloaddition of acetylene to the unsaturated ketone 7, followed by acid-catalyzed rearrangement is described in this article.
Journal ArticleDOI
Synthese von pentasaccharid- und octasaccharid-sequenzen der kohlenhydrat-kette von N-glycopropteinen☆
Hans Paulsen,Rolf Lebuhn +1 more
TL;DR: The block synthesis starting with 3,6-di O -acetyl-2,4-di- O -benzyl-β-d -mannopyranosyl)-(1→4)-1,6 -anhydro-2-azido-3- O-benzylon-2deoxy-β -d -glucopyranose and O -β- d -galactopyranoyl bromide gave two pentasaccharides and one octasac-charide as mentioned in this paper.
Journal ArticleDOI
Methyl 5-acetamido-2,6-anhydro-3,5-dideoxy-d-manno-non-2-en-4-ulosonate ☆
Reference EntryDOI
The Oxidation of Alcohols by Modified Oxochromium(VI)–Amine Reagents
TL;DR: The use of oxochromium(VI)-amine reagents as oxidants in organic synthesis has evolved since the early studies of Sisler which described the use of adducts of heterocyclic nitrogen bases and chromium-VI oxide as mentioned in this paper.
Journal ArticleDOI
Synthèses et réductions de sucres fonctionnels mono et diinsaturés
TL;DR: This article showed that 1,5-anhydro-1,2,6 and 2,3:5,6 di-unsaturated sugars starting from 3,4,6-tri-O -acetyl-1.