ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Natural products  (22)
  • Wiley-Blackwell  (22)
  • International Union of Crystallography (IUCr)
  • 1995-1999  (22)
  • 1980-1984
  • 1945-1949
  • 1930-1934
  • 1925-1929
  • 1999  (22)
Collection
Keywords
Publisher
  • Wiley-Blackwell  (22)
  • International Union of Crystallography (IUCr)
  • Springer  (1)
Years
  • 1995-1999  (22)
  • 1980-1984
  • 1945-1949
  • 1930-1934
  • 1925-1929
Year
  • 1
    Electronic Resource
    Electronic Resource
    2D-NMR-Guided Constitutional Analysis of Organic Compounds Employing the Computer Program COCON[#] (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 573-577 
    Details
    ISSN: 1434-193X
    Keywords: Structure elucidation ; Constitutional analysis ; Natural products ; HMBC ; Computational chemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -The computer program COCON is introduced as a tool for the comprehensive structure elucidation of unknown organic compounds. In particular, structural proposals made on the basis of the molecular formula and of 2D-NMR experiments can be analyzed for the existence of alternative constitutions being in agreement with the same data set. The computational speed grounds on the evaluation of ambiguous long-range connectivity information during the process of structure generation. The data set experimentally obtained for the marine natural product oroidin (1) was selected, because proton-poor compounds usually cause uncertainties in NMR-based structure determinations. The calculation results encourage to move from the experience-based analysis of NMR chemical shifts or of MS fragmentations to the automated evaluation of routinely available connectivity information.Supporting information for this article is available on the WWW under -http://www.wileY-Vch.de/contents/jc_2046/1999/98241_s.pdf or from the author.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    Radical Cyclizations - Synthesis of γ-Lycorane (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1925-1933 
    Details
    ISSN: 1434-193X
    Keywords: γ-Lycorane ; Radicals ; Cyclizations ; Natural products ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (±)-γ-Lycorane has been synthesized in ten steps from piperonylic alcohol. Two radical reactions were used successively to build the D and B rings. A formal synthesis of (+)-γ-lycorane was achieved via an optically active unsaturated aldehyde intermediate.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 3
    Electronic Resource
    Electronic Resource
    A Chiral β,δ-Dioxo-ε-sulfinyl Ester in a Convergent Enantioselective Synthesis towards the C1-C13 Polyol Fragment of Amphotericin B (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 3021-3026 
    Details
    ISSN: 1434-193X
    Keywords: Natural products ; Antibiotics ; Macrolides ; Asymmetric synthesis ; Chiral sulfoxide ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper describes an efficient stereocontrolled and convergent approach towards the C1-C13 polyol fragment of amphotericin B. The strategy is based on the stereoselective reduction of a chiral β,γ-dioxo-ε-sulfinyl ester to obtain anti- or syn-1,3-diols.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 4
    Electronic Resource
    Electronic Resource
    A COCON Analysis of Proton-Poor Heterocycles - Application ofCarbon Chemical Shift Predictions for the Evaluation of Structural Proposals (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 579-586 
    Details
    ISSN: 1434-193X
    Keywords: Structure elucidation ; Computational method ; Natural products ; HMBC ; Constitutional analysis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -The application of the new computer program COCON (Constitutions from Connectivities) to the 2D-NMR data sets of three different complex natural products is described. The investigated compounds are proton-poor and therefore underdetermined systems. For such molecules the number of possible constitutions and the computational speed of COCON are of interest. Our investigation is focused on how methods of 13C-NMR chemical shift prediction can assist chemists with regard to refining the selection among the constitutions proposed by COCON.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    Synthesis of rac-(E)-Opposita-4(15),7(11)-dien-12-al (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 675-678 
    Details
    ISSN: 1434-193X
    Keywords: rac-(E)-Opposita-4(15),7(11)-dien-12-al ; Natural products ; Vetiver oil ; Octahydroindene derivatives ; Fragrances ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -rac-(E)-Opposita-4(15),7(11)-dien-12-al (1) was synthesized in 12 steps via the aldehyde 11 as the key compound. The spectroscopic data of rac-1 are identical with those of the corresponding natural product, previously isolated from Vetiver oil. Synthetic rac-1 has a strong, green woody odor with soft-floral undertones, which confirms that 1 is an olfactorily important constituent of Vetiver oil.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 6
    Electronic Resource
    Electronic Resource
    Isolation and Structural Elucidation of Crellastatins B-H: Cytotoxic Bis(steroid) Derivatives from the Vanuatu Marine Sponge Crella sp. (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 949-953 
    Details
    ISSN: 1434-193X
    Keywords: Natural products ; Dimeric steroids ; Crellastatins ; Sponge ; Crella sp. ; 2D NMR ; Antitumor agents ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Seven new cytotoxic dimeric steroids, namely crellastatins B-H (2-8), have been isolated from the Vanuatu sponge Crella sp. They have been structurally characterized on the basis of 2D-NMR (500 MHz) and FAB-MS data. All the new compounds show the same unprecedented junction between the monomeric units, formed via their side-chains, whereas they differ from A (1) in the hydroxylation pattern of the two tetracyclic cores. Like crellastatin A (1), crellastatins B-H (2-8) exhibit in vitro antitumor activity against human bronchopulmonary non-small-cell lung carcinoma cell lines (NSCLC) with IC50 values in the range of 2-10 μg/mL.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 7
    Electronic Resource
    Electronic Resource
    Metabolites from the Wood-Rotting Basidiomycete Hapalopilusmutans (Aphyllophorales) (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1051-1055 
    Details
    ISSN: 1434-193X
    Keywords: Fungus ; Dihydroxybenzoic acids ; Benzoquinones ; Spirodiones ; Natural products ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Fruit bodies of the wood-rotting North American fungus Hapalopilusmutans produce a mixture of dihydroxybenzoic acids 1, dihydroxybenzoquinones 2 and a novel type of spirodiones, e.g. mutadione A (4a). All compounds carry long alkyl chains, which may be partially unsaturated. The structures of the metabolites were established by spectroscopic methods.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 8
    Electronic Resource
    Electronic Resource
    EPC Syntheses of Trifluorocitronellol and of Hexafluoropyrenophorin - A Comparison of Their Physiological Properties with the Nonfluorinated Analogs (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 2533-2544 
    Details
    ISSN: 1434-193X
    Keywords: (S)-4,4,4-Trifluoro-3-hydroxybutanoic acid ; 2-Trifluoromethyl-3-hydroxypropanoic acid (F3-Roche acid) ; Chiral CF3-containing synthetic building blocks ; Natural products ; Cyclizations ; Olfactory comparison ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The natural products pyrenophorin (1a) and citronellol (2a), in which CH3 groups are replaced by CF3, were synthesized in enantiomerically pure form from simple four-carbon trifluorohydroxy acids (obtained by resolution). The cyclizations of analogous CH3 and CF3 seco acids (cf. 9) to give pyrenophorin derivatives require different methodologies; the F6 derivative 10a could be obtained in only very poor yield; in contrast to pyrenophorin. Most surprisingly, F6-pyrenophorin (1d) has an extremely poor solubility in common organic solvents, and has essentially no antimicrobial activity (see Table 2). The synthesis of F3-citronellol is the first application of an enantiopure F3-Roche acid (12) as a synthetic builiding block (see its derivatives 17-23). An olfactory comparison of F3-citronellol [(R)-(+)-2b] with citronellol and ent-citronellol (Scheme 6) shows that the fluorine derivative has a “very metallic, aggressive” character and lacks totally the “sweetness” of (R)-(+)- and (S)-(-)-2a. A number of generally useful, CF3-substituted electrophilic (iodides 4, 18, 37, tosylates 19, 33, aldehydes 5, 29, 39) and nucleophilic (Li dithiane precursor of 5, Li compounds 20, 38) reagents are described for the first time.Supporting information for this article is available on the WWW under //http://www.wiley-vch.de/contents/jc_2046/1999/99137_s.pdf or from the author.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 9
    Electronic Resource
    Electronic Resource
    A New Tyrosine Kinase Inhibitor from a Marine Isolate of Ulocladium botrytis and New Metabolites from the Marine Fungi Asteromyces cruciatus and Varicosporina ramulosa (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 2949-2955 
    Details
    ISSN: 1434-193X
    Keywords: Marine fungi ; Tyrosine kinase ; Natural products ; Macrodiolides ; Polyketides ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The sponge-derived fungi Ulocladium botrytis and Asteromyces cruciatus, and the algal-derived fungus Varicosporina ramulosa, were isolated and extracts from cultures investigated for their metabolite production. Investigations of the extract of the culture of U. botrytis guided by bioassay yielded the new tyrosine kinase (p56lck) inhibitor ulocladol (1) together with 1-hydroxy-6-methyl-8-(hydroxymethyl)xanthone (3), which showed antifungal activity. The extract of the culture medium of A. cruciatus yielded the new metabolite (+)-2,4-dimethyl-4,5-dihydrofuran-3-carbaldehyde (4) together with the known compounds (3S,5R)-dimethyldihydrofuran-2-one (5) and tri-O-acetyl glycerol. From V. ramulosa the five macrodiolides grahamimycin A1 (6), colletoketol (7), (6R,11R,12R,14R)-colletodiol (8), 9,10-dihydro-(6R,11S,12S,14R)-colletodiol (9) and 9,10-dihydro-(6R,11R,12R,14R)-colletodiol (10) together with ergosterol were obtained, 9 and 10 being new fungal metabolites.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 10
    Electronic Resource
    Electronic Resource
    Structure of Neuritogenic Active Ganglioside from the Sea Cucumber   Stichopus japonicus (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 3171-3174 
    Details
    ISSN: 1434-193X
    Keywords: Glycosphingolipid ; Ganglioside ; Sea cucumber ; Stichopus japonicus ; Neuritogenic activity ; Natural products ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A ganglioside molecular species SJG-1 has been obtained from the n-hexane soluble lipid fraction of the chloroform/methanol extract of the sea cucumber Stichopus japonicus. On the basis of chemical and spectroscopic evidence, the structure of SJG-1 has been determined. SJG-1 possesses an N-glycolylneuraminic acid (sialic acid), nonhydroxy fatty acids and phytosphingosine-type long-chain bases as major ceramide components. The ganglioside SJG-1 exhibits neuritogenic activity toward the rat pheochromocytoma cell line PC12 cells in the presence of NGF.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 11
    Electronic Resource
    Electronic Resource
    A General Approach to Indolizidine Alkaloids From 1-Benzyloxy-5-(p-toluenesulfonamido)-3-alken-2-ols: Synthesis of (+)-Monomorine I (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 3277-3280 
    Details
    ISSN: 1434-193X
    Keywords: Alkaloids ; Asymmetric synthesis ; Palladium ; Amino alcohols ; Natural products ; Monomorine I ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A versatile method for the preparation of indolizidine alkaloids from 1-benzyloxy-5-(p-toluenesulfonamido)-3-alken-2-ols as stereodefined key intermediates has been developed. The utility of this approach was demonstrated by the synthesis of (+)-monomorine I.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 12
    Electronic Resource
    Electronic Resource
    Synthesis of Modified Ingenol Esters (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 3413-3420 
    Details
    ISSN: 1434-193X
    Keywords: Natural products ; Diterpenes ; Ingenol ; Antitumor agents ; Isosters ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthetic protocols for the manipulation of the polyhydroxylated southern region of ingenol (1a) were developed, and a series of isosteres of the anticancer compound ingenol 3,20-dibenzoate (1b) was prepared. The biological evaluation of these compounds showed that cytotoxicity was relatively tolerant to changes at C-20, while PKC activation was markedly affected by these modifications. These data suggest that chemical manipulation can effectively dissect cytotoxicity and tumour-promoting activity (or potential) of ingenoids, affording more optimal candidates for development, like 20-deoxy-20-fluoroingenol 3,20-dibenzoate (5b). In mild acidic medium, an unexpected vinylogous retro-pinacol rearrangement of ingenol to a tigliane derivative was observed.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 13
    Electronic Resource
    Electronic Resource
    Partial Synthesis of a Sea Cucumber Ganglioside Analogue from a Starfish Cerebroside (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 145-147 
    Details
    ISSN: 1434-193X
    Keywords: Natural products ; Ganglioside ; Cerebroside ; Sphingolipids ; Echinoderms ; Sea cucumber ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -A sea cucumber ganglioside analogue 7 (NGNAα2→ 6Glcβ1→1Cer), which contains a phytosphingosine as a long-chain base and an α-hydroxy fatty acid, has been synthesized. Coupling of the methyl 2-thioglycoside derivative 5 of N-glycolylneuraminic acid with a cerebroside derivative 3, prepared from acanthacerebroside A (1), afforded protected ganglioside analogue 6, which was deprotected to give the corresponding ganglioside 7.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 14
    Electronic Resource
    Electronic Resource
    Dasypogalactone, a New C3-Symmetric Macrolactone from the Indonesian Lichen Usnea Dasypoga Rohl (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1719-1721 
    Details
    ISSN: 1434-193X
    Keywords: Natural products ; Trilactide ; Lichen ; Macrocycles ; Lactones ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A structurally novel 24-membered C3-symmetrical macrolactone 2a, composed of three units of 3,7-dihydroxy-2,4-dimethyloctanoic acid, was isolated from the Indonesian lichen Usnea dasypoga Rohl.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 15
    Electronic Resource
    Electronic Resource
    Epoxycaulerpenynes: Reactivity, and Diastereoselective and Highly Regioselective Synthesis by Dimethyldioxirane Oxidation of Caulerpenyne (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1985-1990 
    Details
    ISSN: 1434-193X
    Keywords: Caulerpa taxifolia ; Natural products ; Chemoselectivity ; Epoxidation ; Regioselectivity ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Caulerpenyne (1), the abundant sesquiterpene of the green seaweed Caulerpa taxifolia, has been epoxidized with dimethyldioxirane. The reaction proceeds with significant regioselectivity and moderate diastereoselectivity, the addition of oxygen occurring preferentially at the C(6)=C(7) double bond thereby giving (6S,7S)- and (6R,7R)-epoxycaulerpenynes 10 and 12 in an approximately 2:1 molar ratio besides a small amount of 10,11-epoxycaulerpenyne as an equimolecular diastereomeric mixture 8. The epoxides underwent rearrangement under acidic conditions; the 6,7-epoxides were easily converted into allylic alcohols, whereas the 10,11 isomers required more drastic acidic conditions and gave complex mixtures containing two diastereoisomeric 1,4-dioxanes and an enynone. The high reactivity of 6,7-epoxycaulerpenynes suggests their involvement in the biogenetic pathways of the alga.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 16
    Electronic Resource
    Electronic Resource
    Melithiazols A-N: New Antifungal β-Methoxyacrylates from Myxobacteria (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 2601-2608 
    Details
    ISSN: 1434-193X
    Keywords: β-Methoxyacrylates ; Melithiazols ; Myxobacteria ; Natural products ; Fungicides ; Structure-activity relationships ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: From cultures of Melittangium lichenicola, Archangium gephyra and Myxococcus stipitatus, thirteen new β-methoxyacrylate (MOA) fungicides related to myxothiazols (1) have been isolated. Melithiazols A (2a), D (2b), K (2c), and L (2d) are characterized by a thiazoline-thiazole system, whereas melithiazols B (3a), E (3b), F (3c), G (3d), H (3e), I (3f), M (3g), and N (3h) are bis(thiazoles). Melithiazol C (4), as the first representative of this class of compounds, contains only one thiazole ring. The structures were established on the basis of spectroscopic data, and confirmed in the case of melithiazol E (3b), including its relative configuration, by an X-ray structure analysis. The absolute configuration of melithiazols A (2a) and B (3a) was determined by degradation and CD spectroscopy. Antifungal and cytotoxic activities, inhibition of NADH oxidation, and lipophilicities of melithiazols 2-4, myxothiazols 1, and strobilurin-type compounds are compared.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 17
    Electronic Resource
    Electronic Resource
    Stereoselective Synthesis of Highly Substituted Piperidines (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 3353-3362 
    Details
    ISSN: 1434-193X
    Keywords: Aza-conjugate addition ; Imines ; Natural products ; Piperidines ; Cope rearrangement ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enantiopure piperidines 4 may be accessed in very good overall yields and high stereoselectivity from the bifunctional products 2 of the silyloxy Cope rearrangement of chiral aldol products 1 by sequential nucleophilic addition of primary amines and subsequent hydrogenation. The reaction is proposed to proceed by initial imine formation followed by an intramolecular aza-conjugate addition to the α,β-unsaturated imide. The stereoselectivity is controlled by A(1.2) strain between the imine N-alkyl group and the conjugate double bond. In an alternate approach, polyalkyl-substituted piperidines were prepared by the addition of organozinc reagents to cyanopiperidines readily obtained from the Cope products in the presence of a silver salt.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 18
    Electronic Resource
    Electronic Resource
    Asymmetric Synthesis of (+)- and (-)-Streptenol A (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 751-756 
    Details
    ISSN: 1434-193X
    Keywords: Asymmetric synthesis ; Streptenol A ; Synthetic methods ; Natural products ; SAMP/RAMP hydrazones ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -The asymmetric synthesis of (+)-streptenol A was carried out in ten steps and with high enantioselectivity (ee ≥ 96%). The key steps are the α-alkylation of 2,2-dimethyl-1,3-dioxan-5-one RAMP hydrazone A (1), subsequent deoxygenation and elaboration of the side chain via aldehyde B to furnish (+)-streptenol A in 23% overall yield. In analogy, the enantiomer (-)-streptenol A was synthesized using the corresponding SAMP hydrazone in 18% overall yield.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 19
    Electronic Resource
    Electronic Resource
    Isolation and Structure of a New Ganglioside Molecular Species (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 771-774 
    Details
    ISSN: 1434-193X
    Keywords: Natural products ; Glycosphingolipids ; Gangliosides ; Starfish ; Linckialaevigata ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -A ganglioside molecular species [LLG-3 (1)] has been obtained from the water-soluble lipid fraction of the CHCl3/MeOH extract of the starfish Linckialaevigata. On the basis of chemical and spectroscopic findings, the structure of 1 has been elucidated. Negative-ion FABMS provided important information concerning both the structure of the sugar moiety and the molecular mass of the ganglioside. On the other hand, positive-ion FABMS/MS of [M + Na]+ ions obtained in the positive-ion FABMS of the ceramide lactoside (4) derived from 1 indicated the structure of the fatty acid chain of the ceramide moiety. 1 represents a new ganglioside molecular species possessing a 2→11-linked tandem-type disialosyl moiety.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 20
    Electronic Resource
    Electronic Resource
    Studies on the Synthesis of Natural Products with Bicyclo[4.4.0]decene Skeleton: Synthesis and Uncatalysed Intramolecular Diels-Alder Reactions of the Decatrienone Substrates (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1377-1384 
    Details
    ISSN: 1434-193X
    Keywords: Natural products ; Intramolecular Diels-Alder reactions ; 2-Siloxycyclopropanecarboxylates ; 1,7,9-Decatrien-3-ones ; Octalones ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Starting from enones 7 and 8 siloxydienes 9 and 12 were synthesized. Cyclopropanation and subsequent alkylation with sorbyl bromide provided tetrasubstituted siloxycyclopropanes 15 and 16 in good overall efficiency. Their ring cleavage with fluoride reagents gave 1,7,9-decatrienones 5 and 17; the latter was converted into the protected compound 6. The thermal intramolecular Diels-Alder reactions of 5 and 6 were compared with those of related trienones 3 and 4. Octalones 1, 2, 21, and 22 were formed as mixtures of three or four diastereomers. Thus, for the stereoselective construction of natural products such as α-eudesmol or dihydromevinolin alternative reaction conditions for the cycloaddition step have to be developed.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 21
    Electronic Resource
    Electronic Resource
    New Piperidine Alkaloids from Two Ladybird Beetles of the Genus Calvia (Coccinellidae) (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1749-1755 
    Details
    ISSN: 1434-193X
    Keywords: Natural products ; Piperidines ; Alkaloids ; Coccinellidae ; Calvia14-guttata ; Calviaguttata ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The alkaloids of two coccinellid beetles, Calvia14-guttata and C.10-guttata have been studied. The major alkaloid of these two species is the new piperidinic cis-lactone 1a, for which the name calvine has been coined. The corresponding trans-lactone 1b (2-epicalvine) is also present as a minor constituent (±10%) in both species. We report here the structure determination and the total synthesis of these compounds. Kept in methanolic solution, these lactones undergo epimerisation as well as opening of the lactone ring leading to a complex mixture of nine main components.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 22
    Electronic Resource
    Electronic Resource
    Biomimetic Synthesis of the Flavanone Leridol, Revision of the Structure of the Natural Product (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 2309-2314 
    Details
    ISSN: 1434-193X
    Keywords: Flavanone ; Leridol ; Biomimetic synthesis ; Natural products ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two independent syntheses of 5-hydroxy-6-hydroxymethyl-7-methoxy-8-methylflavanone (1), which was supposed to be natural leridol, demonstrated that this structure assignment was wrong and that the natural flavanone leridol was indeed 5-hydroxy-8-hydroxymethyl-7-methoxy-6-methylflavanone (2).
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...