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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 811-813 
    ISSN: 0170-2041
    Keywords: Liquid crystals ; 1-O-Alkyl-D-glucitols ; Glycoside hydroboration ; Carbohydrates ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The endocyclic acetal bonds of alkyl D-glucopyranosides (hexyl to decyl, 1a - e) are regioselectively hydroborated with ethyldiboranes(6) in the presence of 9-methylsulfonyloxy-9-borabicyclo[3.3.1]nonane (MSBBN) after conversion to their 2,3,4,6-tetra-O-diethylboryl derivatives 2a - e. Subsequent deboronations give the mesogenic 1-O-alkyl-D-glucitols 3a - e.
    Additional Material: 1 Ill.
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  • 2
    ISSN: 0170-2041
    Keywords: Ethyl(dimethoxy)borane ; O-Ethylboranediyl protection ; Methyl α-D-lyxo(or manno)furanosides ; Glycosidation ; Carbohydrates ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ethyl(dimethoxy)borane is prepared by a two-step method involving reaction of triethylboroxin with 1,4-butanediol in a molar ratio of 1:3 to give oligomeric 1,4-butanediyldioxy-ethylboranes which are then treated with methanol. D-Lyxose (1) reacts selectively with ethyl(dimethoxy)borane in the presence of acidic ion exchange resin to form methyl 2,3-O-ethylboranediyl-α-D-lyxofuranoside (2) which is deboronated to give methyl α-D-lyxofuranoside (4). Similarly, D-mannose (6) reacts to give methyl 2,3:5,6-bis-O-ethylboranediyl-α-D-mannofuranoside (7), the deprotection of which yields methyl α-D-mannofuranoside (8).
    Additional Material: 5 Tab.
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  • 3
    ISSN: 0170-2041
    Keywords: Liquid crystals ; Carbohydrates ; 4(6)-O-Alkyl-D-glucitols ; Acetal hydroboration ; Amphiphilic ethers ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Both the hemiacetal and acetal groups of 4,6-O-alkylidene-α/β-D-glucopyranoses (hexylidene-decylidene, 1a-e) are quantitatively reduced by ethyldiboranes(6) in the presence of 9-methylsulfonyloxy-9-borabicyclo[3.3.1]nonane (MSBBN) after conversion to their 1,2,3-tri-O-diethylboryl derivatives 2a-e. Subsequent deboronations give ca. 1:1 mixtures of 4-O-alkyl-D-glucitols 3a-e and 6-O-alkyl-D-glucitols 4a-e, which are separated to give mesogenic 3 and 4. Both 3 and 4 exhibit smectic A liquid crystalline phases.
    Additional Material: 2 Ill.
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  • 4
    ISSN: 0170-2041
    Keywords: Carbohydrates ; Liquid crystals ; 1-Thio-α,β-D-glucopyranosides ; Glucitol derivatives ; Glycoside hydroboration ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkyl 1-thio-α,β-D-glucopyranosides (hexyl to decyl, 1a-e) are prepared by reaction of penta-O-acetyl-β-D-glucopyranose with the respective thiols in the presence of diethyl ether  -  trifluoroborane, followed by deacetylation. 1a-e are converted into their tetra-O-diethylboryl derivatives 2a-e and reduced with ethyldiboranes(6) in the presence of the catalyst 9-methylsulfonyloxy-9-borabicyclo[3.3.1]nonane (9-BBN-mesylate, MSBBN) to give the mesogenic 1-alkylthio-1-deoxy-D-glucitols 3a-e after deboronation.
    Additional Material: 1 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 1093-1096 
    ISSN: 0170-2041
    Keywords: Organoboron monosaccharides ; β-D-Lyxofuranosides ; Glycosides ; Carbohydrates ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methyl and phenyl β-D-lyxofuranoside (3a and 3b) are prepared by reaction of 5-O-acetyl-2,3-O-ethylboranediyl-α-D-lyxofuranosyl bromide (1) with sodium methoxide and sodium phenoxide to give the protected glycosides 2a, b followed by deboronation and deacetylation. The protected α-D-lyxofuranosyl disaccharides 2c, d are synthesized by treatment of 1 with 1,2:3,4-di-O-isopropylidene-α-D-galactopyranose and 1,2:5,6-di-O-isopropylidene-α-D-glucofuranose after the former has been converted to its sodium organooxytriethylborate and the latter has been O-tributylstannylated. 2c and 2d are deboronated and deacetylated to give 3c and 3d, respectively. 2,3,5-Tri-O-acetyl-β-D-lyxofuranosyl glycosides (4a-d) are obtained from 3a-d by acetylation.
    Additional Material: 3 Tab.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1993 (1993), S. 1063-1067 
    ISSN: 0170-2041
    Keywords: Carbohydrates ; 4-O-Alkyl-D-glucoses ; Liquid crystals, smectic ; Bromodiethylborane-sodium triethylhydroborate reducing system ; Amphiphilic glucoses ; X-ray diffraction, small angle ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 4,6-O-alkylidene derivatives (hexylidene-decylidene, 2a-e) are prepared by condensation of methyl α- or β-D-glucopyranoside 1 with alkanals in the presence of pyridinium tosylate. O-diethylborylation of 2 gives 3 which are allowed to react firstly with bromodiethylborane and subsequently with sodium triethylhydroborate to yield methyl 4-O-alkyl-D-glucopyranosides 5 after deborylation. Acid hydrolysis of 5 gives mesogenic 4-O-alkyl-D-glucopyranoses 6a-e. The amphiphilic 6 exhibit the smectic A liquid crystalline phase on melting.
    Additional Material: 1 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 189 (1877), S. 338-357 
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 8
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Note on the Preparation of 5-Deoxylactobionic Acid via Radiation Chemistry.60Co-γ-irradiation of crystalline α-lactose monohydrate yields 5-deoxylactobionic acid (1) with a G-value2) of about 40 [dose 4⋅1020 eV/g; dose rate 1.3⋅1018 eV/(g⋅min)]. A 60% yield was obtained at a total conversion of 12%.
    Notes: Durch 60Co-γ-Bestrahlung von kristallinem α-Lactose-monohydrat entsteht mit einem G-Wert2) von ca. 40 [Dosis 4⋅1020 eV/g, Dosisleistung 1.3⋅1018 eV/(g⋅min)] 5-Desoxylactobionsäure (1) bei einem 12 proz. Gesamtumsatz in 60 proz. Ausbeute.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1975 (1975), S. 752-788 
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Boron Compounds, XXX. - O-Dialkylborylation of Saccharides and PolyolsThe hydroxy groups of polyalcohols [e. g. glycerol, erythritol, pentaerythritol, ribitol, mannitol, meso-inositol], of monosaccharides [o-arabinose (l), u-ribose (2), D-xylose (3), L-rhamnose (4), D-galactose (5), D-glucose (6), D-mannose (7). D-fructose (8), L-sorbose (9)], of their derivatives with e. g. C-amino-, C-nitro-, O-methyl-, O-trityl-, O-isopropylidene, O-tosyl groups, of saccharide acids, their lactones and salts [e. g. ascorbic acid, galactaric acid, gluconic acid-y- lactone, galacturonic acid], of disaccharides [cellobiose (10). lactose (11), maltose (12), saccharose (13). trehalose (14)], of raffinose (15), of cycloamyloses (16) and of polysaccharides [starch (17). cellulose (18), glycogen (19), inulin (20)] can be quantitatively converted in to diethylboryloxy groups using triethylborane. The triethylborane is activated by the addition of 0.1 - 1 mol- O/b of pivalic acid or diethylboryl pivalate. The preparative O-perdiethylborylation of mono-, di-, oligo- and polysaccharides is quantitative. The corresponding dipropyl- boryl derivatives are obtained using activated tripropylborane. The hydrocarbon-soluble products which are distillable up to the Cs-compounds are characterised using chemical (B- and BC-content) and spectroscopic ([α]20D, 1H-NMR, 11B-NMR, MS, IR) methods. The boron-free polyols and saccharides may be regenerated in high yield with the help of methanol or acetylacetone. The quantitative determination of the hydroxy groups in saccharides and polyalcohols is performed volumetrically by measuring the amount of ethane which is evolved on reaction of the particular compound with activated triethylborane. The diethylborylation and deborylation procedure is suitable for the dehydration of polyhydroxy compounds [e. g. D-glucose (6). cycloamyloses (16), 5-deoxylactobionic acid (21)], for the separation of mono- and disaccharides and also for the separation of various types of starch (17)(17) into the amylose (17a) and amylopectin (17b) components.
    Notes: Die Hydroxygruppen der Polyalkohole [z. B. Glycerin, Erythrit, Pentaerythrit, Ribit, D- Mannit, meso-Inosit], der Monosaccharide [D-Arabinose (I), D-Ribose (2), D-Xylose (3). r-Rhamnose (4), D-Galactose (5), D-Glucose (6). D-Mannose (7), D-Fructose (8), L-Sorbose (9)] und ihrer Derivate mit z. B. C-Amino-, C-Nitro-, O-Methyl-, O-Trityl-, O-Isopropyliden- und O-Tosylresten sowie der Saccharidsäuren, deren Lactone und Salze [z. B. Ascorbinsäure, Galactarsäure, Gluconsäure-γ-lacton, Galacturonsäure], der Disaccharide [Cellobiose (l0), Lactose (11), Maltose (12), Saccharose (13), Trehalose (14)], der Raffinose (15), der Cycloamylosen (16) und der Polysaccharide [Stärke (17), Cellulose (18). Glycogen (19), Inulin (20)] lassen sich quantitativ mit Triäthylboran in Diäthylboryloxygruppen umwandeln. Die Aktivierung des Triäthylborans erfolgt dabei durch Zusatz von 0.1 - 1 Mol-% Pivalinsäure oder Diäthylborylpivalat. - Die präparative Gewinnung der 0-perdiäthylborylierten Mono-, Di-, Oligo- und Polysaccharide gelingt quantitativ. Mit aktiviertem Tripropylboran erhält man die entsprechenden 0-Dipropylborylderivate. - Die in Kohlenwasserstoffen löslichen, bis zu den C6-Grundverbindungen unzersetzt destillierbaren Produkte werden durch chemische (B- und BC-Gehalt) und spektroskopische ([α]20D, 1H-NMR, 11B-NMR, MS, IR) Methoden charakterisiert. - Die borfreien Polyalkohole und Saccharide lassen sich aus den O-Dialkylborylderivaten mit Hilfe von Methanol oder von Acetylaceton in hohen Ausbeuten wiedergewinnen. - Die Hydroxygruppen der Saccharide und Polyalkohole können durch Volumetrie des bei der Reaktion mit aktiviertem Triäthylboran entwickelten Äthans quantitativ bestimmt werden. Die Ergebnisse dieser Methode werden mit den durch Einwirkung von Dialkylboranen erhaltenen Werten verglichen. - Durch Diäthylborylierung und Entborylierung ist es möglich, Polyhydroxyverbindungen [z. B. D-Glucose (6), Cycloamylosen (16) oder 5-Desoxylactobionsäure (21)] zu entwässern und Mono- von Disacchariden oder verschiedene Stärken 17 in Amylose (17a) und Amylopektin (17b) quantitativ voneinander zu trennen.
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  • 10
    ISSN: 0947-3440
    Keywords: Wittig reactions ; Amphiphiles ; L-Fucose analogues ; Nucleotides ; Fucosyltransferase ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Starting from the 6-O-tert-butyldimethysilyl-2,3;4,5-di-O-isopropylidene-D-galactose diethyl dithioacetal (4) and proceeding through a Wittig reaction and Swern oxidation, a series of L-fucose analogues, which unlike the normal L-fucose possess an extended alkyl-chain at C-5, can be produced. The elongated carbon backbone in the L-fucitols (22-25) as well as in the L-fucose derivatives (30-33) increases the hydrophobic nature of the sugar molecule, promoting liquid-crystalline properties in both series. The further derivatization of the L-fucose analogues 30, 31 leads to the corresponding β-L-galacto-deco- and dodeco-pyranosyl phosphates 46, 47 and, in turn, to the respective pyranosyl guanosine 5-diphosphates 48, 49. The reaction of the β-L-galactopyranosyl guanosine 5-diphosphate 48 with 8-methoxycarbonyloctyl 2-acetamido-2-deoxy-4-O-(β-D-galactopyranosyl)-β-D-glucopyranoside (50) in the presence of a 3/4-α-fucosyltransferase furnished an O-glycosidic linkage of the α-L-galactopdecopyranose 30 at the 3-O-position of the N-acetyllactosamine glycoside 50. The chemo-enzymatic coupling reaction proves that the synthesized carbon-backbone-elongated L-galactopyranosyl guanosine 5-diphosphates are suitable substrates for the α-fucosyltransferases.
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