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Glycosylimidate, 18. Regioselektive Reaktionen partiell geschützter Zucker Einfache Synthese von 3,4-Diazido-3,4-didesoxy-L-arabinose aus D-Arabinose (1985)

Schmidt, Richard R. ; Faas, Michael ; Jung, Karl-Heinz

Weinheim : Wiley-Blackwell

Liebigs Annalen 1985 (1985), S. 1546-1556

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ISSN: 0170-2041

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Description / Table of Contents: Glycosyl Imidates, 18.- Regioselective Reactions of Partially Protected Sugars Convenient Synthesis of 3,4-Diazido-3,4-dideoxy-L-arabinose from D-ArabinoseBenzyl β-D-arabinopyranoside (1) gave with 1.5 equivalents of mesyl chloride exclusively the 2,3-di-O-mesyl compound 2. Treatment with NaN3 in DMF caused inversion at C-2, C-3, and C-4 and yielded benzyl 3,4-diazido-3,4-dideoxy-α-L-arabinopyranoside (11). Acid-catalyzed debenzylation and subsequent base-catalyzed treatment with trichloroacetonitrile gave the 1-O-activated trichloroacetimidate 16; reaction with the 3,4-O-unprotected 2-azido-2-deoxyxylopyranoside 18 gave regiospecifically the 3-O-connected disaccaride 20. Reduction of the azido groups, N-acetylation, and O-deacetylation led to the O-unprotected disaccaride 23. the structures of the compounds obtained or their O-acetylated derivatives, respectively, were assigned by 1H NMR data.

Notes: Umsetzung von Benzyl-β-D-arabinopyranosid (1) mit 1.5 äquivalenten Mesylchlorid lieferte ausschließlich die 2,3-Di-O-mesyl-Verbindung 2. Behandlung mit Natriumazid in DMF ergab unter Inversion an C-2, C-3 und C-4 Benzyl-3,4-diazido-3,4-didesoxy-α-L-arabino-pyranosid (11). Säurekatalysierte Debenzylierung und anschließende basenkatalysierte Umsetzung mit Trichloracetonitril führte zum 1-O-aktivierten Trichloracetimidat 16, das mit dem 3,4-O-ungeschützten 2-Azido-2-desoxyxylopyranosid 18 regiospezifisch das 3-O-ver-knüpfte Disaccharid 20 lieferte. Reduktion der Azidgruppen, N-Acetylierung und O-Des-acetylierung führte zum O-ungeschützten Disaccharid 23. Die Strukturen der erhaltenen Verbindungen wurden, soweit erforderlich, über O-acetylierte Derivate 1H-NMR-spektroskopisch gesichert.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.198519850804

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Glycosyl Imidates, 42 Selectively Protected Lactose and 2-Azido Lactose, Building Blocks for Glycolipid Synthesis (1989)

Jung, Karl-Heinz ; Hoch, Monika ; Schmidt, Richard R.

Weinheim : Wiley-Blackwell

Liebigs Annalen 1989 (1989), S. 1099-1106

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ISSN: 0170-2041

Keywords: Lactose ; Azidolactose ; Glycosyl acceptors ; Glycosyl donors ; Regioselective protection ; Carbohydrates ; Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Description / Table of Contents: Glycosylimidate, 42. - Selektiv geschützte Lactose und 2-Azidolactose als Bausteine für die Synthese von GlycolipidenDurch regioselektive Alkylierung der 3′-OH-Gruppe von Benzyl-β-lactosid mit der Stannylierungsmethode wurden die 3′-OH- und 4′-OH-ungeschützten Lactosederivate 5 und 10 sowie das 4′-OH-ungeschützte Lactosederivat 9 hergestellt, das aufgrund seiner unterschiedlichen Schutzgruppe für 3′-OH für weitere Umwandlungen geeignet ist. Diese Bausteine sind wertvolle Glycosylakzeptoren für die Synthese von Glycolipiden. Zur Synthese von Glycosyldonoren mit Gal(β1 → 4)GlcNAc-Struktur wurde das 2-Azidolactosederivat 19 verwendet. Durch regioselektive Alkylierung der 3′-OH-Gruppe mit der Stannylierungsmethode sowie durch Anwendung anderer regioselektiver Schutzgruppen-Verfahren wurden die Trichloroacetimidate 17, 24 und 30 hergestellt, die aufgrund ihrer speziellen Schutzgruppen für 3′-OH, 4′-OH und 6′-OH für weitere Umwandlungen geeignet sind.

Notes: Performing regioselective alkylation at 3′-OH of benzyl β-lactoside 1 by the stannylation method we prepared the 3′-OH- and 4′-OH-unprotected lactose derivatives 5 and 10 and the 4′-OH-unprotected lactose derivative 9 containing a different protecting group at 3′-OH, suitable for further transformations. These building blocks are valuable glycosyl acceptors in glycolipid synthesis. For the synthesis of glycosyl donors with Gal(β1 → 4)GlcNAc-structure we used the 2-azido lactose derivative 19. By regioselective alkylation of 3′-OH by the stannylation method and application of other common regioselective protecting procedures we prepared the trichloroacetimidates 17, 24, and 30 containing special protecting groups at 3′-OH, 4′-OH, and 6′-OH which are suitable for further transformations in these positions.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.198919890276

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Synthese von N-Ethylguanosin-5′-carboxamid (1988)

Jung, Karl-Heinz ; Schmidt, Richard R.

Weinheim : Wiley-Blackwell

Liebigs Annalen 1988 (1988), S. 1013-1014

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ISSN: 0170-2041

Keywords: Chemistry ; Organic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Synthesis of N-Ethylguanosine-5′-carboxamideN-Ethylguanosine-5′-carboxamide (5) was prepared by condensation of O-benzoyl-protected riburonic acid glycosyl halide 1 and N2-acetylguanine (2) with mercury(II) cyanide as a catalyst. The N7-isomer, obtained as a byproduct, was separated by reversed-phase medium-pressure liquid chromatography. The structures were determined by NMR and UV spectroscopy.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jlac.198819881017

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