Journal ArticleDOI
A Rapid Route to Hex-1-enopyran-3-uloses
Reads0
Chats0
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
More filters
Journal ArticleDOI
Synthese der invarianten pentasaccharid-core-region der kohlenhydrat-ketten der N-glycoproteine☆☆☆
Hans Paulsen,Rolf Lebuhn +1 more
TL;DR: A block synthesis of 9 with benzyl 2-acetamido-3,6-di- O -benzyl-2-deoxy-α-d -glucopyran osyl chloride (9) gave a trisaccharide that was deblocked to yield O -β- d -mannopyranosyl-(1→4)- O -(2-acet amido-2,deoxy)-β-d-naphosyl)-(1→ 4)-2.
Journal ArticleDOI
On the Stereoselectivity of Fluorine and Acetylhypofluorite Additions to Glycals: The Synthesis of 2-Deoxy-2-Fldorohexoses
TL;DR: In this article, the authors investigated the reaction mechanism based on the product distribution analysis by 19F NMR and showed that the relative stabilities of these intermediates control the product distributions and are governed by the anomeric effect (axial vs equatorial preference of C(1) electronegative substituents in pyranose rings), dipole-dipole interactions of the lone pairs of electrons on the ring oxygen and the electrone-gative substitution on C(2), and the gauche relationship that exists between the C( 2) fluor
Journal ArticleDOI
From Glycals to Metal Pyranosylidenes: Diastereoselective Addition of Electrophiles to Metal Carbene Enolate Intermediates
Christoph Jäkel,Karl Heinz Dötz +1 more
TL;DR: In this paper, a 2-deoxy-pyranosylidenes (2-PDP) was introduced to the C-2-manno complex, i.e., the chromium carbene enolate equivalents.
Book ChapterDOI
Oxidation Adjacent to Oxygen of Alcohols by Other Methods
TL;DR: In this paper, the main emphasis is on reagents which exhibit selectivity of some kind, such as mildness, mildness and availability of a reagent for a specific selective transformation.
Journal ArticleDOI
Synthesen und Reaktionen 3-C-methylverzweigter Glycale der D-Reihe. Darstellungen von Isomeren der endständigen Disaccharide aus Olivomycin A und Mithramycin
Joachim Thiem,Jürgen Elvers +1 more
TL;DR: In this paper, the isomeric 3-C-methyl-branched disaccharide derivatives of the D-series were derived using the N-iodosuccinimide procedure.