Synthese eines Isomeren des Pentadesoxydisaccharids vom CB‐Typ in Anthracyclin‐Glycosiden

Thiem, Joachim; Holst, Monika; Schwentner, Jens

doi:10.1002/cber.19801131107

Cited by 10 publications

References 31 publications

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Transformation of Glycals into 2,3‐Unsaturated Glycosyl Derivatives

Ferrier

Zubkov

2003

Organic Reactions

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Various elimination procedures conducted on appropriate pyranoid and furanoid carbohydrate derivatives, especially on O ‐protected glycosyl halides afford cyclic vinyl ethers which Fischer (inappropriately) named glycals. These are used extensively in general organic synthesis and for the preparation of non‐carbohydrate natural products as well as biologically important complex carbohydrates and glycoconjugates. The best known member, tri‐ O ‐acetyl‐D‐glucal, is normally made from tetra‐ O ‐acetyl‐alpha‐D‐glucopyranosyl bromide, is commercially available, and is used very frequently in this chapter to represent the family in examples of the reactions under discussion. Because of the pronounced region‐ and stereoselectivities with which their addition reactions can be conducted, glycal derivatives are of major importance in synthesis. They also, however, take part in rearrangement processes that, likewise, have proved useful for synthesis. The principal one involves nucleophilic substitution of the allylic group with allylic rearrangement and results in products having double bonds in the 2, 3 positions and new substituents at the anomeric centers. By far the simplest and most commonly used way to this conversion involves the removal of the allylic substituent of the glycal and the generation of highly resonance‐stabilized oxocarbenium ion intermediate. This may then react with nucleophiles at the anomeric center to give products as mixtures of diastereomers. Many examples and variations of this theme are described and form the major part of this chapter, but other ways are also considered Almost no formal mechanistic studies have been carried out on the reactions in this chapter. Categorization of mechanism required for the treatment of this topic has been done on the basis of conditions used, product identification and largely, chemical intuition.

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Transformation of Glycals into 2,3‐Unsaturated Glycosyl Derivatives

Ferrier

Zubkov

2003

Organic Reactions

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Darstellung der terminalen Pentadesoxydisaccharideinheit CB von Anthracyclin‐Antibiotica

1980

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Durch sauer-katalysierte Addition des 2,3-Anhydro-ff-~-allopyranosids 2 an Diacetyl-L-rhamnal (1) wird unter Allylumlagerung das a,l -+ Cverkniipfte Disaccharid 3 gewonnen. Die Epoxidoffnung rnit Lithiumiodid fiihrt zu einem 1 : 4-Gemisch aus 4 rnit 3-iod-glum-und 7 rnit 2-iod-altroKonfiguration. Bei deren Reaktionen mit Natriumiodid erhdt man die entsprechenden Diiodide 5 bzw. 8. Letzteres gibt nach der Hydrierung das Pentadesoxydisaccharid 6 mit C-Iso-B-Struktur. In einer selektiven Hydrierung wird aus 7 das 6-Brom-2,6-didesoxy-Derivat 9 gewonnen, aus dem sich durch Umsetzung rnit Silberfluorid das exocyclische Glycal 12 darstellen lafit. Die nachfolgende Hydrierung erlaubt die Synthese des terminalen C -B-Pentadesoxydisaccharids 13 verschiedener Anthracyclin-Antibiotica. Preparation of the Terminal Pentadeoxy Disaccharide Unit C -B of Anthracycline AntibioticsDiacetyl-L-rhamnal (1) and 2,3-anhydro-a-~-allopyranoside 2 undergo an acid-catalyzed allylic rearrangement to yield the a , l -+ 4-linked disaccharide 3. Opening of the epoxide with lithium iodide results in a 1 : 4 mixture of 4 with 3-iodo-gluco and 7 with 2-iodo-altro configuration. Their reactions with sodium iodide give the corresponding diiodides 5 and 8, respectively. By hydrogenation of the latter the pentadeoxy disaccharide 6 with C-iso-B structure is obtained. The selective hydrogenation of 7 leads to the 6-bromo-2,6-dideoxy derivative 9 which is transformed into the exocyclic glycal 12 by reaction with silver fluoride. Subsequent hydrogenation allows the synthesis of the terminal C -B pentadeoxy disaccharide 13 of various anthracycline antibiotics.

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Ein Verfahren zur Synthese von α‐Glycosiden der 3‐Amino‐2,3,6‐tridesoxyhexopyranosen aus Glycalen

et al. 1981

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Das Anomerengemisch der Hex-2-enopyranosylazide 2 und 3, die jeweils mit den 3-Azidoglycalen 5 bzw. 6 im Gleichgewicht stehen, wird mit Cyclohexanol und N-Iodsuccinimid zu den 3-Azido-2-iod-Derivaten mit a-D-oltro-(4) und a-D-manno-Konfiguration (9) umgesetzt. Deren reduktive Aufarbeitung nebst Acetylierung ermdglicht die Synthese von 3-Acerylamino-2,3-didesoxy-aglycosiden der D-ribo-(7) und der D-arabino-Struktur (8). In einer vergleichbaren Reaktionssequenz wird aus Di-0-acetyl-L-rhamnal(10) in nur drei Stufen die Synthese des a-L-Ristosaminids (16) sowie des a-L-Acosaminids (17) realisiert. A Procedure for an a-Glycoside Synthesis of 3-Amino-2,3,6-trideoxyhexopyranoses from GlycalsThe anomeric mixture of the hex-2-enopyranosyl azides 2 und 3, either of which adopts an equilibrium with the 3-azidoglycals 5 and 6 , reacts with cyclohexanol and N-iodosuccinimide to give the 3-azido-2-iodo derivatives having a-D-aho-(4) and a-D-manno configuration (9). By reductive work-up and subsequent acetylation the synthesis of 3-acetylamino-2,3-dideoxy-a-glycosides of D-ribo (7) and of D-UrUbinO structure (8) is achieved. By a corresponding reaction sequence starting with di-0-acetyl-L-rhamnaI(10) a three step synthesis of both a-L-ristosaminide (16) as well as a-L-acosaminide (17) is realized.Aus den umfangreichen Untersuchungsbefunden der letzten Jahre iiber SaccharidAntibiotica kiRt sich ein allgemeines, natiirliches Bauprinzip ableiten, wonach als Kohlenhydratkomponente unterschiedliche, aber eng verwandte 3-Amino-2,3,6-tridesoxyhexopyranosen bzw. deren N-alkylierte Derivate auftreten. Vielfaltig untersudht werden derzeit die therapeutisch interessanten Anthracyclin-Antibiotica, wobei in Erganzung zu den Synthesen und Modifizierungen der Aglyca'-') zunehmend die Herstellung der Saccharidkomponenten sowie deren Glycosidier~ngsreaktionen~-~) im Blickpunkt stehen.Neben der klassischen Synthese des Saccharids aus Daunorubicing) und ahnlichen Derivaten, dem Daunosamin (3-Amino-2,3,6-tridesoxy-~-lyxo-hexopyranose)~~~ sowie den verwandten Darstellungen der Methylglycoside von L-Ristosamin (3-Amino-2,3,6-tridesoxy-~-ribo-hexopyranose)") und L-Acosamin (3-Amino-2,3,6-tridesoxy-~-arabio-hexopyranose)~~~ basieren andere Herstellungen von ~-Daunosamin"), D-14) und ~-Ristosamin") auf dem Einsatz des einfach verfiigbaren Methyl-4,6-O-benzyliden-2-desoxy-a-~-er~fhro-he~-3-u~opyranosids~~~. Besonders beachtenswert sind der vom Konzept her bestechende Aufbau von N-Acetyl-L-acosamin aus Sorbinsaure-Derivaten"), die kompakte Synthese von L-Acosaminid und L-Ristosaminid aus 3-AzidoChem. Ber. 114(1981)

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Synthese eines Isomeren des Pentadesoxydisaccharids vom CB‐Typ in Anthracyclin‐Glycosiden

Cited by 10 publications

References 31 publications

Transformation of Glycals into 2,3‐Unsaturated Glycosyl Derivatives

Transformation of Glycals into 2,3‐Unsaturated Glycosyl Derivatives

Darstellung der terminalen Pentadesoxydisaccharideinheit CB von Anthracyclin‐Antibiotica

Ein Verfahren zur Synthese von α‐Glycosiden der 3‐Amino‐2,3,6‐tridesoxyhexopyranosen aus Glycalen

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