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  • 1
    ISSN: 0899-0042
    Keywords: chiral HPLC ; principal component analysis (PCA) ; hierarchical clustering ; hydrogen bonding ability ; solvation of carbamate phases ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chromatographic resolution of 12 derivatives in the 4a-methyl-2,3,4,4a-tetrahydro-1H-fluorene and 4a-methyl-1,2,3,4,4a,9a-hexahydrofluoren-9-one series differing by the framework around position 9 and substitution in position 6, are reported on Chiralcel OD, Chiralpak AD, and Chiralpak AS under two elution conditions and according to the two classes of enantiomers. Results from principal component analysis (PCA) as well as hierarchical clustering show a clustering of the actual compounds depending on properties around position 9, the effect of the substituent in position 6 (methyl, chloro or fluoro) not being strong enough to intermesh the data. Carbamate phases show very different properties when they are used in the separation of a series of ketones C and α-chloroketones D, which differ in basicity and the steric requirement around the carbonyl. Analysis of the effect of 2-PrOH content in hexane on the retention is consistent with a large difference in solvation of the carbamate moiety by 2-PrOH, in the order Chiralcel OD 〉 Chiralpak AD 〉 Chiralpak AS. 4a-Methyl-2,3,4,4a-tetrahydro-1H-fluorene derivatives, which lack hydrogen bonding sites, are not discriminated on these CSPs and show identical k′ responses to 2-PrOH content changes on the three CSPs. Chirality 10:770-777, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
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  • 2
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Branched and Chain-extended Sugars, XXX.  -  Diastereoselective Synthesis of L-glycero-D-manno-Heptose, a Constituent of the Inner Core Region of LipopolysaccharidesReaction of 2,3;5,6-di-O-isopropylidene-D-mannofuranose (1) with 2-lithio-1,3-dithiane affords diastereoselectively the 3,4;6,7-di-O-isopropylidene-D-glycero-D-galacto-heptose trimethylene dithioacetal (3). Conversion of compound 3 by a sequence of steps gives the tri-O-isopropylidene-D-glycero-D-galacto-heptit 16 which is oxidized with 1,1′-(azodicarbonyl)-dipiperidine to give the tri-O-isopropylidene-L-glycero-D-manno-heptose 17. Finally, compound 17 is transferred via the acetate 19 into the L-glycero-D-manno-heptopyranose 18.
    Notes: 2,3;5,6-Di-O-isopropyliden-D-mannofuranose (1) reagiert diastereoselektiv mit 2-Lithio-1,3-dithian zum 3,4;6,7-Di-O-isopropyliden-D-glycero-D-galacto-heptose-trimethylendithioacetal (3). Nach Umwandlung von 3 über eine Reihe von Zwischenstufen zum Tri-O-isopropyliden-D-glycero-D-galacto-heptit 16 läßt sich dieser mit 1,1′-(Azodicarbonyl)dipiperidin zur Tri-O-isopropyliden-L-glycero-D-manno-heptose 17 oxidieren. Hieraus ist über das Acetat 19 die freie L-glycero-D-manno-heptopyranose 18 zu gewinnen.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1988 (1988), S. 1061-1071 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Building Units of Oligosaccharides, XC. - Synthesis of Structures of the Inner Core Region of Lipopolysaccharides2-O-Acetyl-3,4,6,7-tetra-O-benzyl-L-glycero-α-D-manno-heptopyranosyl chloride (6) reacts with KDO-glycosyl acceptor 14 stereoselectively to give the α(1→5)-linked disaccharide 24. Removal of protecting groups of 24 leads to L-α-D-Hepp-(1→5)-β-KDOp-OMe (30). Coupling of 6 with 22 and 35 gives the α(1→3)- and α(1→7)-linked disaccharides 31 and 36, respectively, After deblocking of 31 and 36 L-α-D-Hepp-(1→3)-LD-Hepp (34) and L-α-D-Hepp-(1→7)-LD-Hepp (39), respectively, are obtained.
    Notes: 2-O-Acetyl-3,4,6,7-tetra-O-benzyl-L-glycero-α-D-manno-heptopyranosylchlorid (6) läßt sich mit dem KDO-Glycosylakzeptor 14 stereoselektiv zu dem α(1→5)-glycosidisch verknüpften Disaccharid 24 umsetzen, dessen Entblockierung zu L-α-D-Hepp-(1→5)-β-KDOp-OMe (30) führt. Die Umsetzung von 6 mit 22 führt stereoselektiv zum α(1→3)-glycosidisch verknüpften Heptosedisaccharid 31, die von 6 mit 35 zum α(1→7)-glycosidisch verknüpften Heptosedisaccharid 36. Die Entblockierung von 31 führt zu L-α-D-Hepp-(1→3)-LD-Hepp (34), die von 36 zu L-α-D-Hepp-(1→7)-LD-Hepp (39).
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1988 (1988), S. 1073-1078 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Building Units of Oligosaccharides, XCI. - Synthesis of Disaccharides from L-glycero-D-manno-Heptose and 2-Amino-2-deoxy-D-glucoseCoupling of 3,4,6-tri-O-acetyl-2-azido-2-deoxy-α-D-glucopyranosyl bromide (9) with benzyl 2,3,5,6-tetra-O-benzyl-L-glycero-α-D-manno-heptofuranoside (10) gives in the presence of silver triflate stereoselectively the α-glycoside 12, in the presence of silver silicate the β-glycoside 14. Removal of protecting groups of 12 leads to α-D-GlcpN-(1→7)-LD-Hepp (20), a partial structure of the core of Aeromonas hydrophila and Bordetella pertussis LPS. β-D-GlcpN(1→7)-LD-Hepp (21), a core structure of Vibrio ordalii LPS, is obtained after deblocking of 14.
    Notes: Die Umsetzung von 3,4,6-Tri-O-acetyl-2-azido-2-desoxy-α-D-glucopyranosylbromid (9) mit Benzyl-2,3,5,6-tetra-O-benzyl-L-glycero-α-Dmanno-heptofuranosid (10) ergibt bei Gegenwart von Silbertriflat stereoselektiv das α-glycosidisch verknüpfte Disaccharid 12, bei Gegenwart von Silbersilicat dagegen stereoselektiv das β-glycosidisch verknüpfte Disaccharid 14. Aus 12 ist durch Entblockierung α-D-GlcpN-(1→7)-LD-Hepp (20), ein Element der Core-Struktur des LPS von Aeromonas hydrophila und Bordetella pertussis, zugänglich. Aus 14 wird durch Entblockierung die Struktur β-D-GlcpN-(1→7)-LD-Hepp (21) aus Vibrio ordalii erhalten.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 673 (1964), S. 96-101 
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Das 1.3.3-Triphenyl-isoindolenin (I) wurde aus Benzophenonimin, aus Benzophenonimin und Benzophenondichlorid, sowie aus 1.3.3-Trichlor-isoindolenin und Benzol nach FRIEDEL-CRAFTS dargestellt und damit seine Konstitution bewiesen. Diaryl- bzw. Monoarylderivate sowie aliphatisch substituierte Isoindolenine ließen sich auf diesen bzw. analogen Wegen nicht erhalten. I steht bei Temperaturen über 300° im Gleichgewicht mit 1.2.3-Triphenyl-isoindol (III). IR- und UV-Spektren von I und III werden miteinander verglichen.
    Additional Material: 3 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 655-663 
    ISSN: 0170-2041
    Keywords: Heptose oligosaccharides ; KDO oligosaccharides ; Lipopolysaccharides ; Carbohydrates ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Building Units of Oligosaccharides, XCII. - Synthesis of Trisaccharid Units of the Inner Core Region of LipopolysaccharidesL-glycero-D-manno-Heptose derivative 9 reacts with KDO-glycosyl acceptor 6 stereoselectively to give the α(1→5)-linked disaccharide 10. Coupling of now available KDO-glycosyl acceptor 12 with KDO bromide 2 leads to the branched α(2′→4)-α(1″→5)-linked trisaccharide 21. After removal of protecting groups in 10 and 21 3-deoxy-5-O-(L-glycero-α-D-manno-heptopyranosyl)-D-manno-2-octulopyranosonic acid (18) and 3-deoxy-4-O-(3-deoxy-α-D-manno-octulopyranosylonic acid)-5-O-(L-glycero-α-D-manno-heptopyranosyl)-D-manno-2-octulopyranosonic acid (27), respectively, are obtained.
    Notes: Das L-glycero-D-manno-Heptose-Derivat 9 läßt sich stereoselektiv mit dem KDO-Glycosyl-Akzeptor 6 zu dem α(1→5)-glycosidisch verknüpften Disaccharid 10 umsetzen. Der hieraus erhältliche Akzeptor 12 wird mit dem KDO-Glycosyl-Donator 2 stereoselektiv zu dem verzweigten α(2′→4)-α(1″→5)-verknüpften Trisaccharid 21 umgesetzt. Nach der Entblockierung von 10 und 21 ist 3-Desoxy-5-O-(L-glycero-α-D-manno-heptopyransyl)-D-manno-2-octulopyranosonsäure (18) und 3-Desoxy-4-O-(3-desoxy-α-D-manno-octulopyranosylonsäure)-5-O-(L-glycero-α-D-manno-heptopyransyl)-D-manno-2-octulopyranosonsäure (27) zu erhalten.
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