Ulosonic Acids Research Articles

Magnesium(II)-coordinated Claisen rearrangement: a direct approach towards ulosonic acid derivatives

Unprecedented magnesium dihalide-catalysed Claisen rearrangement of 2-alkoxycarbonyl allyl vinyl ethers derived from α-chloroglycidic esters is reported in the glucidic series. A first application of this reaction concerns the stereoselective construction of a disaccharide analogue including a galactosyl and an ulosonic isopropyl ester moieties.

Synthesis and antibacterial activity of mechanism-based inhibitors of KDO8P synthase and DAH7P synthase

KDO8PS (3-deoxy- d- manno-2-octulosonate-8-phosphate synthase) and DAH7PS (3-deoxy- d- arabino-2-heptulosonate-7-phosphate synthase) are attractive targets for the development of new anti-infectious agents. Both enzymes appear to proceed via a common mechanism involving the reaction of phosphoenolpyruvate (PEP) with arabinose 5-phosphate or erythrose-4-phosphate, to produce the corresponding ulosonic acids, KDO8P and DAH7P, respectively. The synthesis of new inhibitors closely related to the supposed tetrahedral intermediate substrates for the enzymes is described. The examination of the antibacterial activity of these derivatives is reported.

Carbohydrates: From ‘Chirons’ to New Glycosubstances

Synthesis of C-glycosides, C-linked saccharides and new glycosubstances has been the subject of considerable interest in carbohydrate, enzymatic and metabolic chemistry, since some of such compounds exhibit exciting biological properties. As a consequence, the design and implementation of stereo selective strategies for preparing bio-active carbohydrates became a prominent issue. This article is mainly aimed at the presentation of the research findings of our group on the synthesis of C-alkyl and C-aryl glycosides, higher sugars; ‘de novo’ construction of disaccharides from furanyl and propargyl sugars; [3+3] annulation routes to carbocycles and pseudo saccharides; 1,3-dipolar cycloaddition to isoxazolidine sugars and saccharides; radical routes to spiro acetal saccharides and ulosonic acid derivatives. Keywords: Carbohydrates, 1,3-dipolar cycloaddition, spiro acetal saccharides, C-aryl glycosides

Transketolase and fructose-1,6-bis-phosphate aldolase, complementary tools for access to new ulosonic acid analogues

A new approach to the synthesis of ulosonic acids KDO and DAH is described. The key step is the C 5–C 6 bond formation catalysed by fructose-1,6-bisphosphate aldolase (for KDO) or transketolase (for DAH) using substituted acrylonitrile α-hydroxyaldehyde. All asymmetric carbon configurations are determined in an enzymatic step by the means of deshydrogenase or lipase. This strategy, using a non-metabolism pathway, allows access to novel precursors of KDO, DAH and analogues.

Chemical Syntheses of the Seven‐ and Eight‐Membered Ulosonic Acids DAH and KDO

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of a Serine-Based Neuraminic Acid C-Glycoside

Cell-surface carbohydrates are classified by the nature of their linkages to the protein as either N-linked or O-linked. O- and N-glycans are involved in a number of important biological functions. These activities can be lost on glycoprotein catabolism when these glycan linkages are enzymatically hydrolyzed. The design and synthesis of novel C-linked glycans should provide catabolically stable glycoproteins useful for understanding and regulating important biological processes. Our efforts are currently directed toward the synthesis of C-glycosides of ulosonic acids. This paper describes the first synthesis of a serine-based neuraminic acid C-glycoside. The protecting group chemistry required for both carbohydrate and peptide syntheses complicates this approach. Different protecting group strategies were investigated for use in the samarium diiodide mediated C-glycosylation reaction. The key elements of our synthetic approach involve the following: (i) the substitution of homoserine for serine in the C-glycosylation reaction to introduce a carbon in place of the O-glycosidic oxygen, (ii) the use of benzyloxycarbonyl as a homoserine protecting group, compatible with samarium diiodide mediated C-glycosylation reaction, and (iii) the reduction of the carbonyl group in homoserine early in the synthesis to improve C-glycosylation yield and to avoid lactone formation. Using this combined approach, we prepared 4-O-acetyl-4-[2-C-(1-methyl 5-acetamido 4,7,8,9-tetra-O-acetyl-2,6-anhydro-3,5-dideoxy-d-erythro-l-manno-nononate)]-2S-(benzyloxycarbonyl)amino-1-carboxylic acid (1), which will be used in peptide synthesis to prepare glycopeptides containing catabolically stable C-linked neuraminic acid.

Esterase Mediated Regioselective Deacetylation of Ulosonic Acid.

The regioselective deacetylation of peracetylated derivatives of N-acetylneuraminic acid and KDN was achieved by hydrolysis with esterase isolated from Rhodosporidium toruloides.

ChemInform Abstract: New Approaches in the Synthesis of Ulosonic Acids and Analogues.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

New Approaches in the Synthesis of Ulosonic Acids and Analogues

New Approaches in the Synthesis of Ulosonic Acids and Analogues

ChemInform Abstract: Stereospecific Synthesis of α‐Glycosides and α‐Disaccharides of Ulosonic Acids via Direct Addition of Alcohols to Sugar Ketene Dithioacetal.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Sulfonomethyl analogues of aldos-2-ulosonic acids. Synthesis of a new sialyl Lewis X analogue

Sulfonomethyl derivatives of aldos-2-ulosonic acids have been synthesized by addition of the ethyl methanesulfonate carbanion to aldonolactones. A sulfonylated mimic molecule of the sialyl Lewis X tetrasaccharide has been prepared by using a new sulfonomethyl ulosonic acid analogue.

ChemInform Abstract: A General Method for the Stereospecific Synthesis of C‐Glycosides of Ulosonic Acids by Samarium‐Mediated Reductive Dechlorination.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A General Method for the Stereospecific Synthesis of C-Glycosides of Ulosonic acids by Samarium-Mediated Reductive Dechlorination

A General Method for the Stereospecific Synthesis of C-Glycosides of Ulosonic acids by Samarium-Mediated Reductive Dechlorination

An Efficient Approach to the 2-Nonulosonic Acid Skeleton Through a Hetero-Diels-Alder Reaction

The hetero-Diels-Alder reaction of 1,3-diene-polyols with glyoxylates is an expeditious way to build up the skeleton of ulosonic acids. This paper reports an efficient means to improve the yields and the stereoselectivity associated with the hetero-cycloaddition of the activated 1,3-diene, 2S,3S-4E-1-O-Benzyl-2,3-O-isopropylidene-6-ter-butyldimethylsilyloxyhepta-4,6-diene-1,2,3-triol (3) with the dienophile ethyl glyoxylate. The effects of temperature, catalyst, and solvent on the outcome of the Diels-Alder reaction were investigated. The cycloaddition can proceed smoothly even at −78°C and the complex bis [3-(heptafluorobutyryl)camphorato]oxovanadium (8) was found to be a very efficient catalyst for the cycloaddition reaction. The satisfactory selectivity (endo/exo: 97:3 and re/si: 82:18) observed in this catalytic reaction shows that there is a match effect between the substrate and catalyst.

ChemInform Abstract: Stereoselective Synthesis of α‐Substituted Ulosonic Acids by Magnesio‐Reformatsky Reactions.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Stereoselective synthesis of α-substituted ulosonic acids by magnesio-reformatsky reactions

A new method of homologation of aldonolactones allowing the incorporation of propionate units with excellent chemo- and stereoselectivity is performed by the magnesium-graphite mediated reaction between Oppolzer sultam derived α-halogenated amides and an aldonolactone.

Polyclonal catalytic antibody for hetero-cycloaddition of hepta-1,3-diene with ethyl glyoxylate an approach to the synthesis of 2-nonulosonic acid analogs

Polyclonal antibody raised from a product analogue for a Diels-Alder reaction has been found to catalyze the planned endo-cycloaddition between ethyl glyoxylate hydrate and diene. adduct of which would be useful for the synthesis of ulosonic acid and its analogs.

A mild oxidative decarboxylation of carbohydrate acids

The oxidative decarboxylation of carbohydrate uronic or ulosonic acids with simultaneous replacement by an acetoxy group has been accomplished using the (diacetoxyiodo)benzene and iodine system under mild conditions. A general synthesis of derivatives of tetrodialdoses, and pentodialdoses in furanose or pyranose form is described.

ChemInform Abstract: Selective Conjugate Addition of Benzylamine to 2‐Thiazolyl α,. beta.‐Enone Derived from D‐Glyceraldehyde Acetonide. An Exploratory Study Toward the Synthesis of Aminated Ulosonic Acids.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Specificity of rabbit antisera against the rough lipopolysaccharide ofSalmonella minnesotastrain R7 (chemotype Rd1P−)

Rabbit polyclonal antibodies against the lipopolysaccharide (LPS) of the Rd1P- mutant strain R7 of Salmonella minnesota were serologically characterized using R7 LPS, dephosphorylated LPS, deacylated LPS, deacylated, dephosphorylated and reduced LPS, and synthetic partial structures. The latter comprised partial structures of the core region of Rd1P- LPS bound to the beta 1-->6-linked glucosamine dissacharide with two amide-linked 3-hydroxytetradecanoic acid residues or artificial glycoconjugates comprised of the synthetic oligosaccharides coupled to bovine serum albumin. Using a passive hemolysis and an enzyme immunoassay, absorption and inhibition experiments, the antibody specificites present could be determined. One group of antibodies required components of the core region and the phosphorylated glucosamine disaccharide of the lipid A moiety for binding. The majority of phosphate-independent antibodies was directed against the trisaccharide L-glycero-alpha-D-manno-heptopyranose(1-->3)- L-glycero-alpha-D-manno-heptopyranose(1-->5)3-deoxy-D-manno-oct ulo sonic acid. Antibodies against the 1-->3- and 1-->7-linked heptose disaccharides and against a single heptose were also detected, however, with low titers. No antibodies were found which required the presence of fatty acids.