Conformational and hydrodynamic properties of the homopolymer of 2-deoxy-2-methacrylamido-D-glucose and its copolymers with acrylic acid and methacrylic acid

Hydrodynamic properties of the homologous series of the homopolymer 2-deoxy-2-methacryla-mido-D-glucose and the copolymers of 2-deoxy-2-methacrylamido-D-glucose with unsaturated acids in 0.2 M NaCl are studied via static and dynamic light scattering, viscometry, refractometry, and translational diffusion. The copolymers synthesized via the free-radical copolymerization of 2-deoxy-2-methacrylamido-D-glucose with acrylic acid or methacrylic acid contain ～20 mol % acid units. At this amount of acid units, the equilibrium rigidity of copolymer chains corresponds to that of homopolymer chains. The copolymers are distinguished by the hydrodynamic characteristics of molecules. The copolymer with methacrylic acid is similar to the homopolymer, whereas the copolymer with acrylic acid features substantially different parameters of relationships relating the hydrodynamic characteristics of homologs to their molecular masses.     

Asymmetric syntheses of methyl N-Boc-2-deoxy-2-amino-l-erythroside,methyl N-Boc-2-deoxy-2-amino-d-threoside and methyl N-Boc-2,3-dideoxy-3-amino-l-arabinopyranoside

The asymmetric syntheses of methyl N-Boc-2-deoxy-2-amino-l-erythroside and methyl N-Boc-2-deoxy-2-amino-d-threoside have been achieved from sorbic acid, in six and eight steps, and in 35 and 13% overall yield, respectively. Diastereoselective aminohydroxylation of tert-butyl sorbate gives access to two diastereoisomeric α-hydroxy-β-amino-γ,δ-unsaturated esters. Reduction of the ester functionality and ozonolysis of the double bond gives the corresponding aldehyde, which exists exclusively in the ring-closed (furanose) form. An alternative synthesis of methyl N-Boc-2-deoxy-2-amino-l-erythroside was also developed, reliant on aminohydroxylation of an α,β-unsaturated ester bearing an acetal functionality at the γ-position, and this synthesis proceeded in five steps and 54% overall yield from acrolein diethyl acetal. This approach was extended to permit the synthesis of methyl N-Boc-2,3-dideoxy-3-amino-l-arabinopyranoside in six steps and 58% overall yield from ethyl 3,3-diethoxypropanote.     

Reactivity of 2-deoxy-2-iodoglycosyl isothiocyanates with O-, S-, and N-nucleophiles. Synthesis of glycopyranoso-fused thiazoles

The reactivity of 2-deoxy-2-iodoglycosyl isothiocyanates toward O- and S-nucleophiles gives an easy access to 2-deoxy-2-iodoglycopyranosyl thiocarbamates and dithiocarbamates. Internal nucleophilic displacement of the iodine by the sulfur atom in these compounds allows the preparation of glycopyranoso[1,2-d]-1,3-thiazoles and glycopyranoso[1,2-d]-1,3-thiazolidin-2-one or -2-thione. Reaction with amines or polyamines as N-nucleophiles led directly to 2-aminoglycopyranoso[1,2-d]-1,3-thiazoles without isolation of the intermediate thioureas. Methyl 2-deoxy-2-iodoglycopyranosyl thiocarbamates also allow the synthesis of 2-deoxyglycopyranosyl thiocarbamates or 2-deoxy-2-iodoglycopyranosyl carbamates.     

Arsenic-containing ribofuranosides and dimethylarsinic acid in green seaweed,Codium fragile

Three water-soluble arsenic compounds were isolated from the green seaweed Codium fragile. These compounds were identified as 1-glycerophosphoryl-2-hydroxy-3-[5′-deoxy-5′-(dimethylarsinoyl)-β-ribofuranosyloxy]propane (1a), 1′ -(1,2-dihydroxypropyl)-5′ -deoxy-5′ -(dimethylarsinoyl)-β-ribofuranoside (1b), and dimethylarsinic acid ((CH₃)₂AsOOH). The structures of these compounds were ascertained by ¹H NMR spectroscopy. Compounds 1a and 1b accounted for 60 % and dimethylarsinic acid for 5% of the water-soluble arsenic.     

Variable strategy toward carbasugars and relatives. 6. Diastereoselective synthesis of 2-deoxy-2-amino-5a-carba-beta-L-mannopyranuronic acid and 2-deoxy-2-amino-5a-carba-beta-L-mannopyranose

Efficient, total syntheses of novel 2-deoxy-2-amino-5a-carba-beta-L-mannopyranuronic acid (1) and 2-deoxy-2-amino-5a-carba-beta-L-mannopyranose (2), a positional stereoisomer of validamine, have been achieved in 28% and 24% overall yields and in 12 steps and 13 steps, respectively, from 2-[(tert-butyldimethylsilyl)oxy]furan (3) and (2S)-2,3-O-isopropylideneglyceraldehyde N-benzyl imine (4) via two highly diastereoselective Mukaiyama aldol-related chemical maneuvers. The strategy, which furnishes the targeted carbasugars in enantiopure forms, allows for complete control of the configuration at all five contiguous stereocenters of the targets by utilizing the sole element of chirality present in the aldimine progenitor 4.     

Über 2-Deoxy-2,3-dehydro-sialinsäuren, 1. Mitt.: Synthese und Eigenschaften von 2-Deoxy-2,3-dehydro-N-acylneuraminsäuren und deren Methylestern

Zusammenfassung Wenn nach Behandlung der 2-Chlor-2-deoxy-4,7,8,9-tetra-O-acetyl-N-acetylneuraminsäure mit HCl-abspaltenden Mitteln oder nach längerem Erhitzen der in Dioxan gelösten 2,4,7,8,9-Penta-O-acetyl-N-acetylneuraminsäure das Reaktionsprodukt O-deacetyliert wurde, entstand eine Verbindung, die mit Resorcin die für Sialinsäurederivate typische Farbreaktion gab. Sie gab mit CH₂N₂ einen Methylester, der bei der katalyt. Hydrierung 1 Mol H₂ pro Mol aufnahm und 2 Mol Natriummetaperjodat pro Mol verbrauchte. Diese Eigenschaften sowie die Elementaranalyse, das UV-, IR- und NMR-Spektrum der Verbindung wiesen diese als eine 2-Deoxy-2,3-dehydro-N-acetylneuraminsäure aus.Analog zur Darstellung des Methylesters der 2-Deoxy-2,3-dehydro-N-acetylneuraminsäure wurden von uns die Methylester der 2-Deoxy-2,3-dehydro-N-glykolyl-, 2-Deoxy-2,3-dehydro-N-propionyl-, 2-Deoxy-2,3-dehydro-N-butyryl-, 2-Deoxy-2,3-dehydro-N-benzoyl-und 2-Deoxy-2,3-dehydro-N-carbobenzoxyneuraminsäure erhalten.

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2-deoxy-2.3-dehydro-sialic acids, I: Synthesis and properties of 2-deoxy-2.3-dehydro-N-acyl-neuraminic acids and their methyl esters

When 2-chloro-2-deoxy-4.7.8.9-tetra-O-acetyl-N-acetylneuraminic acid was treated with HCl-eliminating agents or when 2.4.7.8.9-penta-O-acetyl-N-acetylneuraminic acid was heated for several hours in dioxan solution and the reaction product was subsequently O-deacetylated, a compound was obtained which gave the resorcinol colour reaction characteristic of sialic acid derivatives. Its methyl ester upon catalytic hydrogenation took up 1 mole of hydrogen per mole and upon oxidation with sodium metaperiodate consumed 2 moles of the oxidant. These properties as well as the elementary analysis and the UV-, IR- and NMR-spectra of the new compound showed that it was 2-deoxy-2.3-dehydro-N-acetylneuraminic acid.The methyl esters of 2-deoxy-2.3-dehydro-N-glycolyl-, 2-deoxy-2.3-dehydro-N-propionyl-, 2-deoxy-2.3-dehydro-N-butyryl-, 2-deoxy-2.3-dehydro-N-benzoyl- and 2-deoxy-2.3-dehydro-N-carbobenzoxy-neuraminic acid were obtained by reactions analogous to those used for the preparation of the methyl ester of 2-deoxy-2.3-dehydro-N-acetylneuraminic acid.

     

Ethyl 2-acetamido-4,6-di-O-benzyl-2,3-N,O-carbonyl-2-deoxy-1-thio-beta-D-glycopyranoside as a versatile GlcNAc donor

The title donor, ethyl 2-acetamido-4,6-di-O-benzyl-2,3-N,O-carbonyl-2-deoxy-1-thio-beta-D-glycopyranoside, is shown to be an excellent glycosyl donor giving immediate and efficient access to variant GlcNAc-containing oligosaccharides.     

Synthesis of [2-C]-oleanolic acid and [2-C]-myricerone

Synthetic way for ¹³C-labeled oleanolic acid 1 and myricerone 2 has been developed, starting from the parent 1 and 2. The procedure involves ring opening and closure of the A rings of these oleanane triterpenes. ¹³C was introduced into the 2-position by ¹³C-MeLi as an isotope source. Chelation controlled addition of methyllithium to -hydoxypentanone 11 is a common crucial step for labeling of 1 and 2, and judicious choice of protecting groups is essential for 2.     

Formation of 1,5-lactones from 3-deoxy-d-manno-2-octulosonic acid derivatives.

Acylation of ammonium 3-deoxy-α-D-manno-2-octulopyranosonate (1a) leads to the formation of peracetylated 3-deoxy-α-D-manno-2-octulopyranosono- 1,5-lactones (3a,b). Theproposed structures were confirmed by independent syntheses. The 1,7-lactone was not formed even when only OH-7 was available for lactonisation.     

Iodoacetoxylation of glycals using cerium(IV) ammonium nitrate, sodium iodide, and acetic acid: stereoselective synthesis of 2-deoxy-2-iodo-alpha-mannopyranosyl acetates

[formula: see text] The reactions of glycals with ceric(IV) ammonium nitrate and sodium iodide in the presence of acetic acid provides 2-deoxy-2-iodo-alpha-mannopyranosyl acetates with good stereoselectivity. In the majority of the cases examined, the selectivity was considerably better than that from reactions using N-iodosuccinimide and HOAc.     

A facile synthesis of 2-deoxy-2,3-didehydroneuraminic acid derivatives

The 2-thio- or 2-selenoglycosides of N-acetylneuraminic acid methyl ester were transformed by successive treatment with dimethyl(methylthio)sulfonium triflate (DMTST) and 1,8-diazabicyclo[5.4.0]-7-undecene (DBU) to give the corresponding methyl 2-deoxy-2,3-didehydroneuraminates in excellent yields. Their acids and their analogues are sialidase inhibitors of pharmaceutical interest.     

Stereoselective synthesis of the alpha-allyl C-glycoside of 3-deoxy-D-manno-2-octulosonic acid (KDO) by use of radical chemistry.

Methyl 2-C-allyl-2,6-anhydro-3-deoxy-4,5:7,8-di-O-isopropylidene-D-glycero- D-talo-octonate (9a), the protected alpha-allyl C-glycoside of 3-deoxy-D-manno-2-octulosonic acid (KDO), has been synthesized using a photochemically initiated radical reaction. A phenyl thioglycoside (8) was used as the substrate and allyltributyltin as the acceptor. The stereoselectivity of the reaction was 90:10 in favour of the talo-isomer (alpha-).     

Synthese und Eigenschaften von 2-Deoxy-2,3-dehydroneuraminsäure sowie neuer N-Acylderivate

Zusammenfassung Wurde 2-Deoxy-2,3-dehydro-N-benzyloxycarbonylneuraminsäure mit H₂ in Gegenwart von Pd/BaSO₄ behandelt, entstand in guter Ausbeute 2-Deoxy-2,3-dehydroneuraminsäure. Elementaranalyse, UV-, IR- und NMR-Spektren der Säure stehen mit der vorgeschlagenen Struktur im Einklang. Mit Diphenyldiazomethan gab 2-Deoxy-2,3-dehydroneuraminsäure den Benzhydrylester. Sowohl die Säure als auch ihr Ester dienten zur Darstellung einer Reihe sonst nur schwer zugänglicher N-Acyl-2-deoxy-2,3-dehydroneuraminsäuren.

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2-Deoxy-2.3-dehydrosialic acids. III.: Synthesis and properties of 2-deoxy-2.3-dehydroneuraminic acid and of new N-acyl derivatives Über 2-Deoxy-2,3-dehydro-sialinsäure, 3. Mitt.

2-Deoxy-2.3-dehydroneuraminic acid was obtained in good yield by hydrogenolytic cleavage of 2-deoxy-2.3-dehydro-N-benzyloxycarbonylneuraminic acid. Elemental analysis, UV-, IR- and NMR-spectra of the acid are in full agreement with the proposed structure. The benzhydryl ester of 2-deoxy-2.3-dehydroneuraminic acid was formed by reaction of the acid with diphenyldiazomethane. Both the acid and its ester allowed the synthesis of a series of N-acyl-derivatives which otherwise would be difficult to obtain.

     

NMR study of 4-deoxy-α-L-threo-4-enohexopyranosyluronic acid (1 → 3)2-acetamido-2-deoxy-D-hexoses produced in the enzymic digestion of hyaluronate,chondroitin and chondroitin sulfates

The conformation of 4-deoxy-α-L -threo-4-enohexopyranosyluronic acid (1 → 3)2-acetamido-2-deoxy-d-hexoses was analyzed by NMR spectroscopy. The half-chair (H₁²) conformation was found in the unsaturated uronide moiety and the chair (Cl) conformation in the hexosamine moiety.     

Partial Synthesis of 3′-Hydroxy-2′-deoxy-2″,3″,4″,5″-tetrahydroverrucarin A. Verrucarins and roridins, 38th Communication [1]

The macrocyclic trichothecene triester 3′-hydroxy-2′-deoxy-2",3",4",5"-tetrahydroverrucarin A ( 37 ), has been synthesized starting from the sesquiterpene alcohol verrucarol ( 3 ), adipic acid and a derivative of mevalonic acid ( 14 ). The latter has been prepared from 4-(tetrahydro-2-pyranyloxy)-2-butanone ( 9 ).     

Stereocontrolled transformation of nitrohexofuranoses into cyclopentylamines via 2-oxabicyclo[2.2.1]heptanes. Part 6: synthesis and incorporation into peptides of the first reported 2,3-dihydroxycyclopentanecarboxylic acid

Herein we report the intramolecular alkylation of nitronates of methyl-5-O-benzyl-3,6-deoxy-6-nitro-β-d-glucofuranoside and methyl-5-O-benzyl-3,6-deoxy-6-nitro-α-d-glucofuranoside into the corresponding 2-oxabicyclo[2.2.1]heptane derivatives. Similarly, methyl-3-O-benzyl-5-deoxy-5-nitromethyl-β-d-xylofuranoside and methyl-3-O-benzyl-5-deoxy-5-nitromethyl-α-d-xylofuranoside were cyclized to (1R,3R,4S,5R,7R)-7-benzyloxy-3-methoxy-5-nitro-2-oxabicyclo[2.2.1]heptane and (1R,3S,4S,5R,7R)-7-benzyloxy-3-methoxy-5-nitro-2-oxabicyclo[2.2.1]heptane, respectively. These 2-oxabicyclo[2.2.1]heptane derivatives were eventually transformed into enantiopure methyl (1S,2S,3R,4S,5R)-2-amino-2,3-dihydroxycyclopentanecarboxylate and this novel β-amino acid was incorporated into peptides.     

Synthesis and antiviral evaluation of 2'-deoxy-2'-C-trifiuoromethyl beta-D-ribonucleoside analogues bearing the five naturally occurring nucleic acid bases

2'-Deoxy-2'-C-trifluoromethyl-beta-D-ribonucleoside derivatives bearing the five naturally occurring acid bases have been synthesized. All these derivatives were prepared by glycosylation reactions of purine and pyrimidine bases with a suitable peracylated 2-deoxy-2-C-trifluoromethyl sugar precursor to afford anomeric mixtures of protected nucleosides. After separation and deprotection, the resulting beta-nucleoside analogues were tested for their activity against HIV, HBV and several RNA viruses. However, none of these compounds showed significant antiviral activity nor cytotoxicity.     

Structural determination of salsolins A and B, new antioxidant polyoxygenated triterpenes from Salsola baryosma, by 1D and 2D NMR spectroscopy

Salsolins A (1) and B (2), the new triterpenes, have been isolated from the chloroform soluble fraction of Salsola baryosma along with 2alpha,3beta,23,24-tetrahydroxyurs-12-en-28-oic acid (3) reported for the first time from this species. Their structures have been assigned from 1H and 13C NMR spectra, DEPT and by 2D COSY, NOESY, HMQC and HMBC experiments. The compounds 1-3 showed significant antioxidant activity.     

Synthesis of 2-iodoglycals, glycals, and 1,1'-disaccharides from 2-Deoxy-2-iodopyranoses under dehydrative glycosylation conditions

Treatment of 2-deoxy-2-iodopyranoses under dehydrative glycosylation conditions afforded pyranose glycals, 2-iodoglycals, and 1,1'-disaccharides instead of the expected glycoside products. While the product distribution revealed that this reaction is very sensitive to the configuration of the 2-deoxy-2-iodopyranose, 2-iodopyranoid glycals can be obtained almost exclusively in good yields by employing 3,4-O-isopropylidene as a cyclic bifunctional protecting group. The behavior of 2-deoxy-2-iodopyranoses during the dehydrative elimination reaction has been analyzed in detail.     

Structure elucidation and complete NMR spectral assignments of three new lanostanoid triterpenes with unprecedented Delta(16, 17) double bond from Ganoderma lucidum

Three new lanostanoid triterpenes named 3beta,7beta-di- hydroxy-11,15,23-trioxo-lanost-8,16-dien-26-oic acid (1), 3beta,7beta-dihydroxy-11,15,23-trioxo-lanost-8,16-dien-26-oic acid methyl ester (2), and 12beta-acetoxy-3beta,7beta-dihydroxy-11,15,23-trioxo-lanost-8,16-dien-26-oic acid (3) were isolated from the fruit bodies of Ganoderma lucidum. They all show a Delta(16, 17) double bond unprecedented in such types of lanostanoid triterpenes possessing the side chain at C-17. The complete NMR assignments for these compounds were carried out using (1)H, (13)C, DEPT, COSY, HSQC, HMBC, and ROESY NMR experiments.