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  • 1
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Surface Modification of Carbon Electrodes by Polymers Consisting of Epoxy Resins and a Derivative of Vitamin B12A derivative of vitamin B12 containing a 3,5-diaminobenzoyl group in the c side-chain has been synthesized. It was used as the amine component in the formation of an optically active cross-linked epoxy-polymer. Surface modification of carbon electrodes (basal plane graphite and carbon felt) has been achieved by impregnating them with solutions of the monomers followed by thermal curing at 120°C. Electrochemical responses of the Co(II)/Co(I) redox system from sub-mono to multilayer coverages have been observed. The polymer exhibits catalytic activities typical for monomeric vitamin B12 as shown by spectroscopic and electrochemical techniques. Polymermodified electrodes with large specific surfaces have been used in organic electrosynthesis, i.e. the exclusive formation of valeronitrile by reductive cross-coupling of ethyl iodide and acrylonitrile.
    Additional Material: 4 Ill.
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  • 2
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The diastereoisomeric 18-nor- and 19-norambrox ((6α)- and (6β)-dodecahydro-3a,6,9a-trimethylnaphtho[2,1-b]furans resp.) as well as the corresponding 18,19-dinor-derivatives (dodecahydro-3a,9a-dimethylnaphtho[2,1-b]furans) have been synthesized and subjected to sensory evaluation. Threshold data and odor determination give an enlarged insight into the structure-activity relationship (SAR) in ambrox-type ambergris fragrances. As a general conclusion, the accumulation of axial CH3 groups in the tricyclic ethers 1-12 leads to the strongest receptor affinity.
    Additional Material: 2 Tab.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 940-944 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Macrocyclic Oligolactams Based on Terephthalic Acid as Ionophores with Selectivity Depending on Included Guest MoleculesMacrocyclic 20- to 60-membered oligolactam hosts exhibit ion selectivities in poly(vinyl chloride) membranes which depend on the ring size and on the substituents of the amide N-atoms. The selectivity may be changed by loading the macrocyclic host with CHCl3 as guest molecule.
    Additional Material: 4 Ill.
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  • 4
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An overall enantioselective substitution of the R-group of an α-hydroxy- or α-amino acid 1 [R—CH(XH)COOH] by another R-group is possible through heterocycles 2 obtained from 1 with pivaladehyde (1 → 7). The rac- and the (S)-(+)-heterocycles 8 (title compounds of type 5) are prepared from glycine and O-benzyl-(S)-serine, respectively. Their enolates (cf. 9, type 6) are alkylated with iodomethane, iodobutane, 2-iodopropane, benzyl bromide, and acetone to give the trans-disubstituted imidazolidinones 10 with ≥ 95% diastereoselectivity. The configuration of the products is established by chemical correlation with alanine, phenylalanine, and valine.
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  • 5
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compound 7 and two related novel ergolines have been synthesised from (5R,8R,10R)-8-(methyl-thiomethyl)ergoline-6-carbonitrile (4). The guanidine function of 7 induces a boat conformation of ergoline-ring D, as demonstrated by a careful NMR spectroscopic analysis of 7 and its N-hydroxy congener 6. Diphenylphosphinodithioic acid has been used to convert the cyanamide function of 4 into the thiourea function at (5R,8R,10R)-8-(methylthiomethyl)ergoline-6-thiocarboxamide (5).
    Additional Material: 4 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 1078-1079 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 2,5-dimethylidene-3,6-bis[(Z)-(2-nitrophenyl)sulfenylmethylidene]-7-oxabicyclo[2.2.1]heptane (13) can be used to generate polyfunctional and multicyclic molecules with high regio- and stereoselectivity via two successive Diels-Alder additions using two different dienophiles. This principle has been applied to the synthesis of (±)-11-deoxydaunomycinone (7), the aglycone of an important antitumor drug. The 2,3-didehydroanisole adds to 13 and gives the monoadduct 14 with high regioselectivity. No trace of bis-adduct is observed. The 1,4-epoxy-1,2,3,4-tetrahydro-5-methoxy-3-methylidene-2-[(Z)-(2-nitrophenyl)sulfenylmethylidene]anthracene (15) obtained on treating 14 with K2CO3 adds to methyl vinyl ketone to give [(1RS, 2SR, 5RS,12RS)-5,12-epoxy-1,2,3,4,5,12-hexahydro-7-methoxy-1-(2-nitrophenyl)sulfenyl-2-naphthacenyl]methyl ketone (16) with high regio- and stereoselectivity. The acid-catalyzed 7-oxanorbornadiene→phenol rearrangement of 16 is regioselective and gives (5-acetoxy-3,4-dihydro-7-methoxy-2-naphthacenyl) methyl ketone (20) which was transformed into (±)-7,11-dideoxydaunomycinone ((±)-24), a known precursor of 7.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 1079-1088 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The methylene-blue sensitized photooxygenation of heptamethyl Coα,Coβ-dicyanocobyrinate (1, cobester) at ca. -45° and in (D3)acetonitrile solution proceeds readily to the stage of selective double cleavage of the corrin macrocycle. It furnishes the bisected heptamethyl Coα,Coβ-dicyano-5,6:14,15-tetraoxo-5,6:14,15-disecocobyrinate (3) in 91% yield after warming the photooxygenation mixture to room temperature. Complex 3 is also obtained by photooxygenation of the secocorrinoid oxygenation products of 1, namely of heptamethyl Coα,Coβ-dicyano-5,6-dioxo-5,6-secocobyrinate (2a) and of its isomer heptamethyl Coα,Coβ-dicyano-14,15-dioxo-14,15-secocobyrinate (2b). When the raw photooxygenation product of 1 is kept at low temperature, 3 is not formed in a significant amount; spectral analysis reveals 4 as intermediate that is transformed into 3 quantitatively upon warm-up and storage at r.t. Compound 4 is assigned the structure of heptamethyl Coα,Coβ-dicyano-5,6-epidioxy-5,6-dihydro-14,15-dioxo-14,15-secocobyrinate, based on NMR-spectral data and since 4 is also formed cleanly in the corresponding low-temperature photooxygenation of 2b. Catalytic reduction of the Co(III) complex 3 (H2, Pt/C) in the presence of EDTA produces a colourless oil, from which the bicyclic fragments 5 (corresponding to rings A and D of 1) and 6 (corresponding to rings B and C of 1) are obtained in 99 and 91% yield, respectively, after chromatographic separation.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 1133-1139 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Diels-Alder Reactions with Activated 4-Methyl-1,3-pentadienesEthyl 4-methyl-1,3-pentadienyl ether, trimethyl[(4-methyl-1,3-pentadienyl)oxy]silane, and 1-(4-methyl-1,3-pentadienyl)pyrrolidine and the corresponding piperidine analogue have been used in Diels-Alder reactions with acrylonitrile, ethyl acetylenedicarboxylate, maleic anhydride, and 2,6-dimethyl-p-benzoquinone.
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  • 10
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Derivatives of the unknown 2-amino-6H-1,3-oxazin-6-one 2 have been synthesized for the first time in two steps and in excellent yields, starting from N-cyanocarbonimidates 3a-c and cyanoacetates. The structures of 2a-c are assigned by NMR-spectroscopic methods and corroborated by an X-ray structure analysis of 2c.
    Additional Material: 1 Ill.
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  • 11
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: MNDO and STO-3G calculations rationalize the relative instability of the title propellanes vis-à-vis the title products that are formed exclusively.
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  • 12
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Factor F430 from Methanogenic Bacteria: On the Nature of the Isolation Artefacts of F430, a Contribution to the Chemistry of F430 and the Conformational Stereochemistry of the Ligand Periphery of Hydroporphinoid Nickel(II) ComplexesFactor F430 (1), a coenzyme from methanogenic bacteria, when heated in aqueous solution isomerizes to 12,13-di-epi-F430 (5) via 13-epi-F430 (3). The equilibrium mixture of the three F430 isomers in aqueous phosphate buffer solution (pH 7, 100°) contains 88 % of 5, 8 % of 3, and 4 % of 1 (Scheme 1). The structural assignment for the F430 isomers rests on FAB-MS-, UV/VIS-, 1H- and 13C-NMR spectra of their pentamethyl esters. Chemical proof for the double epimerization at the two chiral centers of F430's ring C was provided by ozonolytic degradation of the di-epimer to give a ring-C-derived succinimide derivative that was shown to be the enantiomer of the one previously obtained by ozonolysis of F430M (see Scheme 2). The two F430 ring-C epimers 3 and 5 are the isolation artefacts described in the earlier F430 literature. F430 is susceptible to autoxidation in air and the product, that absorbs at 560 nm, was shown to be the 12,13-didehydro derivative 8 of F430 by spectroscopic characterization of its pentamethyl ester 9. The dehydrogenation product 8 can be diastereoselectively reduced with Zn in AcOH to give natural F430 as the main product rather than the thermodynamically more stable F430-di-epimer (Scheme 3). In the double epimerization of F430, the two ring-C side chains change from a trans-quasi-diaxial arrangement to the (locally) enantiomorphic position in which the same side chains are again in a trans-quasi-diaxial arrangement. This equilibrium paradox as well as the kinetic diastereoselectivity of the reduction of 12,13-didehydro-F430 (8) are rationalized to be consequences of the general phenomenon documented earlier (see the preceding paper) according to which hydroporphinoid Ni(II) complexes all show a characteristic conformational ruffling of their ligand system due to the tendency of the (small) Ni(II) ion to contract the size of the ligand's central coordination hole (see Fig. 5 and 6).
    Additional Material: 1 Ill.
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  • 13
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Influence of Solvents, Viscosity, Acid, and Substituents on the Photoisomerization and the Relaxation of Symmetrical Triazacarbocyanine Dyes at 283 to 323 KPhotobleaching and the reverse dark reaction of seven symmetrical triazacarbocyanine dyes with different heterocycles were studied dependent on solvent effects (protic and aprotic solvents), on effects of viscosity (glycerol/EtOH mixtures), and on effects of added acid. No effects of dissolved O2 or added I2 has been observed. Kinetic data (ΔH≠, ΔS≠, and ΔG298 K≠) of the reverse reaction are given. The effect of the substituents has been studied on two series of substituted triazacarbocyanine dyes. The mechanism of the reverse reaction is discussed.
    Additional Material: 3 Ill.
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  • 14
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal N2 exchange of a number of 15N-labelled diazo compounds was studied in solution. The compounds involved were 3-diazo-1-methylindolin-2-one (1), 9-diazofluorene (2), 5-diazo-1,3-cyclopentadiene-1,2,3,4-tetracarbonitrile (3), 2-diazo-2H-imidazole-4,5-dicarbonitrile (4), 4-diazocyclohexa-2,5-dienone (5), and the conjugate acids of 4 and 5, namely 4,5-dicyano-1H-imidazole-2-diazonium ion (6) and 4-hydroxybenzenediazonium ion (7). Only 1, 4, 6, and 7 exchange their diazo group with ‘external’ molecular N2. The results are explained on the hypothesis that only organic species which have an empty σ orbital and which are effective in π electron back-donation are able to react with N2. Thus, reaction with carbenes is likely to occur only if the carbene is in the 1A2 singlet state and if its electrophilicity is high.
    Additional Material: 1 Ill.
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  • 15
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The gas-phase protonation of alkyl-substituted furan compounds is investigated in equilibrium proton-transfer reactions conducted in an ion cyclotron resonance (ICR) spectrometer. From the effects of substituents on the stability of protonated species, it is concluded that protonation of the majority of these systems occurs specifically on the C(α)-atom to form carbenium ions. Parallel MO calculations performed on different structures of the products reinforce the experimental conclusions and provide energy values for the less stable structures. The solution reactivity of these compounds towards electrophilic agents and NMR spectra of protonated species obtained in strong acidic media have been investigated.
    Additional Material: 4 Tab.
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  • 16
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Viridiene ((+)-6; (+)-(3R,4S)-3-((1Z)-1,3-butadienyl)-4-vinylcyclopentene) and aucantene ((+)-18; (+)-(4R,5R)-4-((1E)-1-propenyl)-5-vinylcyclohexene) are constituents of the pheromone bouquets of several brown algae species. Key synthons to the title compounds are optically active γ-lactones with known or experimentally determined absolute configurations. Horse liver alcohol dehydrogenase, which catalyses the oxidation of meso- and racemic non-meso diols to chiral lactones, and pig-liver esterase, which catalyzes the saponification of meso-diesters to chiral half-esters, were utilized for the asymmetric synthesis of such precursors. The racemic non-meso diol rac-1 is converted to the two stereoisomeric γ-lactones (+)-2 and (+)-3 which are readily separated. meso-Diol 12 is oxidized to the chiral γ-lactone (-)-11. Its enantiomer (+)-11 is obtained by enantioselective saponification of the meso-diester 9 with pig-liver esterase. Appropriately designed syntheses lead from these chiral intermediates to both enantiomers (+)- and (-)-6 of viridiene and (+)- and (-)-18 of aucantene. In addition, kinetically controlled reduction of the racemic aldehydes rac-5a and rac-15 with horse liver alcohol dehydrogenase offers a convenient alternative to the enantioselective preparation of the enantiomers of the two hydrocarbons 6 and 18. Chromatography of 6 on triacetylated cellulose as a stationary chiral phase confirms the enantiospecificity of the synthetic routes designed.
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  • 17
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985) 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 18
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 2140-2147 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ring Expansion during the Reaction of a 1,3-Cyclohexanedione with DiphenylcyclopropenoneThe reaction of 5,5-dimethyl-1,3-cyclohexanedione (1) in form of its Na-salt with diphenylcyclopropenone (2) in DMF yielded the bicyclic triketone 3 (58 %), the structure of which was deduced as an enolizeable bicyclo[5.2.0]nonane-β-diketone from spectral data and from the following reactions: hydrolysis or methanolysis of 3 cleaved the β-dicarbonyl moiety, thereby opening the 4-membered ring to yield the keto acid 9 or its methyl ester 10. Methylation of 3 afforded the two enol ethers 4 and 5. The ether 5 readily underwent a thermal electrocyclic ring opening to the monocyclic enol ether 8, whereas the ether 4 was thermally stable. The same electrocylic ring opening (in boiling benzene) converted 3 (probably via 3b) to the monocyclic triketone 7, which was also the hydrolysis product of the ring-opened enol ether 8. By heating 3 in DMF/H2O, a partial (56 %) conversion to the lactone 6 took place. The tricyclic intermediate 11 was found useful to rationalize the ring expansion during the formation of 3 from 1 and 2 as well as the corresponding ring contraction during the conversion of 3 into 6.
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  • 19
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 2158-2164 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rate constants (log k) for solvolysis of 2-, 3-, and 4-substituted bicyclo[2.2.2]octyl p-nitrobenzenesulfonates 10, 11 and 12, respectively, correlate linearly with the corresponding inductive substituent constants s̰Iq. The formation of the ion pairs 9 is, therefore, controlled by the I effect of neighboring substituents. It follows from the corresponding reaction constants ρ1 of -1.54, -1.12, and -1.22 that inductivity is highest at the positions α to C(1). It is lower and practically equal at the β- and γ-positions. Therefore, charge dispersal is similar to that previously observed in the quinuclidinium ion 7.
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  • 20
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 2177-2181 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of 15-Hydroxy[9]metacyclophane3-(1-Nitro-2-oxocyclododecyl)propanal (1) was converted to 15-hydroxy[9]metacyclophane (3) on two different routes. In the first case the internal aldol reaction product of 1 was treated with K2CO3/THF to give 3 in 29 % yield with regard to cyclododecanone. Alternatively, the aldehyde 1 reacted with a primary amine to form e.g. 4 which gave 3 in the presence of CH3I/K2CO3 in 48 % yield.
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  • 21
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The base-catalyzed intramolecular cyclization of polycyclic olefinic alcohols of type a (10-endo-hydroxy-anti9,10-tricyclo [4.2.1.12,5]dec-7-en-9-ones (type h), anti9,10-tricyclo[4.2.1.12,5] dec-3-en-9-endo-ols (type j), and anti10,11-tricyclo[4.3.1.12,5]undec-3-en-10-endo-ols (type 1)) to the ethers d and f, resp., has been studied. A mechanism for the nucleophilic addition of the corresponding alkoxide anion b to the isolated C,C—double bond is discussed. It is proposed that b is formed (fast acid/base equilibrium) in the first step. For the subsequent reaction sequence, there are two well distinguishable pathways: (a) Compounds with an additional carbonyl group (h) cyclize via a homoenolate-like intermediate c, which is protonated stereoselectively on the exo-side by the hydroxylic solvent. (b) Compounds without a carbonyl group (j and l) cyclize 102-104 times slower, and the reaction proceeds via a carbanion-like transition state e. The proton transfer from the hydroxylic solvent is clearly coupled with the C,O—bond formation. Steric compression in the olefinic alcohols a influences the cyclization rate: (a) Alcohols with a smaller ring (h, X = CH2CH2) cyclize 70-200 times faster than the ones with a larger ring (1, X = CH2CH2CH2). (b) Replacement of the H-atom at the carbinol C-atom by a CH3 group enhances the rate of ether formation by a factor of 50-100. Due to through-bond interactions between the C,C-double bonds, olefinic alcohols with an additional endocyclic C,C-double bond (h and j, X = CH=CH) cyclize 20-300 times faster than the corresponding monoolefinic ones (h and j, X = CH2CH2).
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  • 22
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By a simple process, 3-methoxyjuglone (= 8-hydroxy-2-methoxy-1,4-naphthoquinone; 9) has been synthesized from 1,2,4-trimethoxybenzene (5) and converted, after prenylation, to α-caryopterone (1; Scheme 1), a pyranojuglone pigment from Caryopteris clandonensis. On the other hand, juglone (= 5-hydroxy-1,4-naphthoquinone; 12) was regioselectively prenylated at C(2) via its 1-methoxy-cyclohexa-1,3-diene adduct 15 (Scheme 2). The 2-prenyljuglone (4) thus formed led to 1 after oxidation and other reactions.
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  • 23
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure elucidation of four new constituents from the roots of Echinacea purpurea is described. They are shown to be cinnamoyl esters of sesquiterpene alcohols with a germacrane or a guaiane skeleton. First pharmacological results indicate immunological activities.
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  • 24
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chiral Building Blocks for Syntheses by Kolbe Electrolysis of Enantiomerically Pure β-Hydroxybutyric-Acid Derivatives. (R)- and (S)-Methyl-, and (R)-Trifluoromethyl-γ-butyrolactones, and -δ-valerolactonesThe coupling of chiral, non-racemic R* groups by Kolbe electrolysis of carboxylic acids R*COOH is used to prepare compounds with a 1.4- and 1.5-distance of the functional groups. The suitably protected β-hydroxycarboxylic acids (R)- or (S)-3-hydroxybutyric acid, (R)-4,4,4-trifluoro-3-hydroxybutyric acid (as acetates; see 1-6), and (S)-malic acid (as (2S,5S)-2-(tert-butyl)-5-oxo-1,3-dioxolan-4-acetic acid; see 7) are decarboxylatively dimerized or ‘codimerized’ with 2-methylpropanoic acid, with 4-(formylamino)butyric acid, and with monomethyl malonate and succinate. The products formed are derivatives of (R,R)-1,1,1,6,6,6-hexafluoro-2,5-hexanediol (see 8), of (R)-5,5,5-trifluoro-4-hydroxypentanoic acid (see 9,10), of (R)- and (S)-5-hydroxyhexanoic acid (see 11) and its trifluoro analogue (see 12, 13), of (S)-2-hydroxy- and (S,S)-2,5-dihydroxyadipic acid (see 23, 20), of (S)-2-hydroxy-4-methylpentanoic acid (‘OH-leucine’, see 21), and of (S)-2-hydroxy-6-aminohexanoic acid (‘OH-lysine’, see 22). Some of these products are further converted to CH3- or CF3-substituted γ- and δ-lactones of (R)- or (S)-configuration (14, 16-19), or to an enantiomerically pure derivative of (R)-1-hydroxy-2-oxocyclopentane-1-carboxylic acid (see 24). Possible uses of these new chiral building blocks for the synthesis of natural products and their CF3 analogues (brefeldin, sulcatol, zearalenone) are discussed. The olfactory properties of (R)- and (S)-δ-caprolactone (18) are compared with those of (R)-6,6,6-trifluoro-δ-caprolactone (19).
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  • 25
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    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 2451-2453 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 26
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 961-968 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Selective Preparation of l- or u-Aldols from Ethyl Trityl Ketone and Aromatic Aldehydes through Lithium and Aluminium Enolates, RespectivelyThe ethyl trityl ketone (1) is deprotonated to the (Z)-enolate 2 which adds to aromatic aldehydes with relative topicity ul to give the aldols 3(-78°, THF, kinetic control). If, on the other hand, 1 is heated with trimethylaluminium in toluene, the aluminium enolate formed combines with aromatic aldehydes and with cinnamic aldehyde with opposite relative topicity (lk) to the aldols 5 (+20°, toluene, 2 d, precipitation of the aluminium aldolate 4, thermodynamic control). The mechanism is discussed (cf. Fig. 1). The adducts to benzaldehyde (3a, 5a), furfural (3f, 5f), and cinnamaldehyde (3i, 5i) are O-(2-methoxyethoxy)methyl (MEM) protected and cleaved by lithium triethylborohydride to the 1,3-diol derivatives 9-11 with a free primary and a protected secondary OH-group. Analogous conversions of 1 and other ketones may also be diastereoselective, but turned out to be of less preparative value (see 6-8, 12).
    Additional Material: 1 Ill.
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  • 27
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of penta- and hexapeptides of the structure Ac-Lxn- …-Lx1-Ly1-…-Lym-NH2 with phenylalanine or tyrosine in Lx1 and glycine or alanine in the other positions were synthesized using elastase and δ-chymotrypsin to catalyse the formation of the peptide bonds adjacent to the aromatic residue. Such oligopeptides are useful substrates for studying the secondary specificity of chymotrypsin-like proteases.
    Additional Material: 3 Tab.
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  • 28
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Multiple chlorinations and arylations at the tertiary positions of adamantane are promoted by FeCl3-doped K10 montmorillonite in CCl4 or in aromatic solvents. The process, remarkably easy to implement, can be tailored to selective formation of monosubstituted 1-adamantyl derivatives or 1,3-disubstituted adamantanes. The process achieves alkylation at the meta- and para-positions of toluene leading to a purely statistical distribution and displays no substrate specificity in competition experiments between toluene and benzene.
    Additional Material: 6 Tab.
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  • 29
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 1226-1234 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two synthetic approaches to the novel C10H16 hydrocarbon tricyclo[4.4.0.03,9]decane (1; 2-homotwistbrendane), one of the 19 members of the adamantaneland, and its Lewis-acid-catalyzed rearrangement are described. One route starts from tricyclo[4.3.0.03,8]nonan-2-one (2; 2-twistbrendanone). The missing tenth C-atom is introduced by ring enlargement (Tiffeneau-Demjanov method). Starting from methyl 8,9,10-trinorborn-5-ene-2-endo-carboxylate (8), ring enlargement by one C-atom, regio- and stereoselective introduction of a C1 unit to a 2-endo,6-endo-disubstituted bicyclo[3.2.1]octane, and ring closure by acyloin condensation are the key steps in the second approach.
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  • 30
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 1251-1275 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The phenolic compounds of the fern Dryopteris aitoniana were analyzed by improved methods avoiding alcaline reagents and contact with unbuffered SiO2, which can cause deterioration. We confirmed the presence of five of the formerly (1971) reported six compounds, while the sixth, formerly incorrectly assumed to be aspidin (based on a spot in TLC), has now been isolated as cristals (TR-1579). It has the empirical formula C27H52O2, but its structure is still unknown. Five other compounds were isolated in pure form, tetra-albaspidin BBBB (25-BBBB) a known but rare phloroglucinol, and four new compounds: penta-albaspidin BBBBB (37-BBBBB), hexa-albaspidin BBBBBB (38-BBBBBB), tetraflavaspidic acid BBBB (26-BBBB) and hexaflavaspidic acid BBBBBB (39-BBBBBB). The structures were established by degradation NMR and partly by field-desorption and fast-atom-bombardment (FAB) mass spectra. The oligoflavaspidic acids are very unstable compounds, deteriorating during isolation procedures using the older ‘standard method’.
    Additional Material: 9 Ill.
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  • 31
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The isolation and characterisation of [CoCl(en)(L)]ZnCl4, L = NH2CH2CH=NCH2CH2NH2 (1,4,7-triazahept-3-ene), as a by-product (∼ 8% yield) from the H2O2 synthesis of trans-CoCl2(en)2+, is described.
    Additional Material: 1 Tab.
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  • 32
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Optically Active Carotenoids with (R)-4-Hydroxy β-End GroupsWe describe the synthesis of optically active iso-β-kryptoxanthin (12; (R)-β,β-caroten-4-ol), iso-α-kryptoxanthins 14 ((4R,6′RS)-β,ε-caroten-4-ol) and 16 ((4R,6′R)-β,ε-caroten-4-ol), 4′-hydroxyechinenone (18; (R)-4′-hydroxy-β,β-caroten-4-one), and isorubixanthin (20; (R)-β,ω,-caroten-4-ol), their 400-MHz-1H-NMR spectra, CD spectra and HPLC behaviour.
    Additional Material: 8 Ill.
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  • 33
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sugar Free Radicals. VIII. Spin-Labeled Nucleosides AnalogsA series of 5′-deoxy-5′-hydroxylamino derivatives of adenosine and uridine have been prepared by reduction of the corresponding oxime or nitrone. ‘Second generation’ 3′-deoxy-3′-N-aryl(or N-alkyl) hydroxylamino-β-D-xylofuranosyluracils have also been synthesized by a one-pot reaction including the following elementary steps: deblocking of the starting material, reduction of the 3′-deoxy-3′-oximinouridine, condensation of the resulting hydroxylamine with an aldehyde, reduction of the nitrone formed. The deoxy-hydroxylaminonucleosides oxidized spontaneously in the air (or in presence of traces of PbO2) to give the corresponding nitroxide free radicals, ESR spectra of which furnished useful informations on their structures. Some of these modified nucleosides bore notable cytotoxic or antiviral activities.
    Additional Material: 2 Tab.
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  • 34
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985) 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 35
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 433-434 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Notiz über die Reaktion von Aminoacetonitril-hydrochlorid mit Orthoameisensäure-trimethylesterAminoacetonitril-hydrochlorid (1) liefert mit Orthoameisensäure-trimethylester (2) N-Formyl-aminoacetonitril (5) und nicht - wie berichtet - das 5(4H)-Imidazolon (3). Als Zwischenprodukt dieser Reaktion entsteht N-(Cyanmethyl)formimidsäure-methylester (4).
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  • 36
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 439-447 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On a New Synthesis of N-Aryl-N-glucosides and N-Aryl-N-glucosiduronic Acid Methyl EstersMixtures of O- and N-trimethylsilyl derivatives obtainable from (acyl)(aryl)amines give with the peracetates of β-D-glucopyranose or methyl β-D-glucopyranuronate, respectively, under catalysis with trimethylsilyl trifluoromethanesulfonate the corresponding β-D-N-(acyl)(aryl)-N-glycosides. Under these conditions the exclusively reacting O-TMS derivative is continuously generated from its N-TMS isomer, the yields are, therefore, mostly very high. The N-(p-anisyl)amine 4 affords solely the N-TMS derivative and thus does not react to give its N-glycoside. Selective deacetylation at the N atom is achieved with triethyloxonium fluoroborate/NaHCO3, saponification of all O-esters with sodium methanolate.
    Notes: Die aus (Acyl)(aryl)aminen zugänglichen Gemische ihrer O- und N-Trimethylsilyl-Derivate ergeben unter Trifluormethansulfonsäure-trimethylsilylester-Katalyse mit den Peracetaten von β-D-Glucopyranose oder β-D-Glucopyranuronsäure-methylester die entsprechenden β-D-N-(Acyl)-(aryl)-N-glycoside. Unter den Reaktionsbedingungen wird das sich allein umsetzende O-TMS-Derivat laufend aus seinem N-TMS-Isomeren nachgebildet, die Ausbeuten sind daher meist sehr gut. Das N-(p-Anisyl)amid 4 ergibt ausschließlich das N-TMS-Derivat und reagiert daher nicht zum N-Glycosid. Selektive Entacetylierung am Stickstoff gelingt mit Triethyloxonium-fluoroborat/NaHCO3, Verseifung aller O-Estergruppen mit Natriummethanolat.
    Additional Material: 3 Tab.
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  • 37
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 453-461 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemistry of Reactive Cations Derived from Sulfur Dioxide Analogues, XIII. - Preparation and Cycloaddition Reactions of Cationic Sulfur DiimidesTwo types of unsymmetrically substituted cationic sulfur diimides (1 and 2) have been synthetized. Diels-Alder reactions with 1 and 2 proceed regiospecifically in accordance with earlier hypotheses5,6).
    Notes: Es wurden zwei Typen von unsymmetrisch substituierten kationischen Schwefeldiimiden (1 und 2) synthetisiert. Diels-Alder-Reaktionen mit 1 und 2 erfolgen regiospezifisch, in Übereinstimmung mit früheren Vorstellungen5,6).
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  • 38
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 468-476 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Carbonyl Cyanide (Mesoxalonitrile) with Steroidal DienesCarbonyl cyanide (1) reacts with 2,4-cholestadiene (2) to give the [4 + 2] cycloadducts 3a and 3b. 1,3-Cholestadiene (7), 7,8-didehydrocholesteryl acetate (10), and ergosteryl acetate (14) give, on the contrary, with 1 ene-reaction products, affording the dicyano cyanoformate 8 (from 7) or the corresponding dicyanohydroxy compounds 11a and 15 (from 10 or 14, respectively). The products of the ene-reaction give quantitatively carboxylic acid derivatives with silica gel; this is a convenient method for the introduction of a C1 unit.
    Notes: Carbonylcyanid (1) reagiert mit 2,4-Cholestadien (2) zu den [4 + 2]-Cycloaddukten 3a und 3b. Mit 1,3-Cholestadien (7), 7,8-Didehydrocholesteryl-acetat (10) und Ergosteryl-acetat (14) liefert 1 dagegen Produkte der En-Reaktion, wobei aus der Umsetzung mit 7 das Dicyan-cyanformat 8, mit 10 oder 14 die entsprechenden Dicyanhydroxyverbindungen 11a und 15 entstehen. Die Produkte der En-Synthese ergeben an Kieselgel quantitativ Carbonsäure-Derivate; dies bietet eine brauchbare Methode zur Einführung eines C1-Bausteines.
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  • 39
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 477-484 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Di- and Polyamino Sugars, XXXI. - Substitution Reactions of 2-Amino-2-deoxy-β-D-glucopyranosides at Position 3Neighboring-group participations obstruct nucleophilic substitutions of N-protected 2-amino-2-deoxy-3-O-mesyl-β-D-glucopyranosides with azide ions. From the N-dinitrophenyl derivative 8 besides the allopyranoside 10 the isomeric products 9 and 11 are formed, the latter via the aziridine 15. The N-acyl derivatives 3 and 13 yield the allopyranosides 5 and 19 as well as the oxazoline 4. Structure proofs were given by spectroscopy and by independent syntheses.
    Notes: Nachbargruppenreaktionen stören die nucleophile Substitution von N-geschützten 2-Amino-2-desoxy-3-O-mesyl-β-D-glucopyranosiden mit Azid-Ionen. Das Dinitrophenyl-Derivat 8 liefert neben dem Allopyranosid 10 die isomeren Produkte 9 und 11 über das Aziridin 15. Die N-Acylderivate 3 und 13 liefern die Allopyranoside 5 und 19 sowie das Oxazolin 4. Die Konstitutionsbeweise wurden sowohl anhand der Spektren als auch durch unabhängige Synthesen geführt.
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  • 40
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Conformational Analysis, XXV. - Conformations of Octasaccharide and Pentasaccharide Sequences in N-Glycoproteins of the Lactosamine TypeThe oligosaccharide sequences [β-D-Gal(1 → 4)β-D-GlcNAc(1 → 2)α-D-Man(1 → 3)]β-D-Gal-(1 → 4)β-D-GlcNAc(1 → 2)α-D-Man(1 → 6)β-D-Man(1 → 4)-D-GlcNAc (2), β-D-Gal(1 → 4)β-D-GlcNAc(1 → 2)α-D-Man(1 → 6)β-D-Man(1 → 4)-D-GlcNAc (3), β-D-Gal(1 → 4)β-D-GlcNAc(1 → 2)-α-D-Man(1 → 3)β-D-Man(1 → 4)-D-GlcNAc (4), and β-D-Gal(1 → 4)β-D-GlcNAc(1 → 2)α-D-Man-OMe (5), found in N-glycoproteins, were investigated by means of HSEA calculations with the program GESA to reveal the preferred solution conformations of these compounds. Experimental evidence of the calculated conformations was given by 1H and 13C NMR studies like NOE experiments, spin-lattice relaxation-time measurements and observation of special deshielding effects. NMR spectra analysis required application of 2-D-NMR techniques. As a conclusion of experimental and theoretical results the common sequences in the saccharides 2, 3, 4, and 5 exhibit very similar conformations. The pentasaccharide 4 takes up a linear conformation whereas 5 shows a bent arrangement of the pyranose rings (‚gt conformation‘) which results in a relatively close contact between the α-D-Man unit and the reducing D-GlcNAc unit. Analogously, both conformations, the linear and the bent one, occur in the octasaccharide 2.
    Notes: Die bevorzugten Konformationen der in N-Glycoproteinen vorkommenden Oligosaccharid-Sequenzen [β-D-Gal(1 → 4)β-D-GlcNAc(1 → 2)α-D-Man(1 → 3)] β-D-Gal(1 → 4)β-D-GlcNAc-(1 → 2)α-D-Man(1 → 6)β-D-Man(1 → 4)-D-GlcNAc (2), β-D-Gal(1 → 4)β-D-GlcNAc(1 → 2)α-D-Man(1 → 6)β-D-Man(1 → 4)-D-GlcNAc (3), β-D-Gal(1 → 4)β-D-GlcNAc(1 → 2)α-D-Man(1 → 3)-β-D-Man(1 → 4)-D-GlcNAc (4) und β-D-Gal(1 → 4)β-D-GlcNA(1 → 2)α-D-Man-OMe (5) wurden durch HSEA-Berechnungen mit dem Programm GESA bestimmt. Die Überprüfung der Rechnungen erfolgte durch 1H- und 13C-NMR-spektroskopische Experimente wie NOE-Untersuchungen, Spin-Gitter-Relaxationszeitmessungen und Beobachtung spezieller Abschirmungseffekte. Die Interpretation der NMR-Spektren erfolgte mit Hilfe von 2-D-NMR-Techniken. Die in 2, 3, 4, und 5 gemeinsam auftretenden Sequenzen haben alle sehr ähnliche bevorzugte Konformationen. Während 4 eine weitgehend gestreckte Konformation aufweist, zeigt 5 bevorzugt eine gebogene gt-Konformation, bei der die α-D-Man-Einheit der reduzierenden D-GlcNAc-Einheit nahe steht. Beide Formen kommen in 2 entsprechend vereint vor.
    Additional Material: 10 Ill.
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  • 41
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of the Coenzyme Metabolite 1,6-Dihydro-6-oxo-1-(β-D-ribofuranosyl)-3-pyridinecarboxamideThe NAD(P) coenzyme metabolite 1,6-dihydro-6-oxo-1-(β-D-ribofuranosyl)-3-pyridinecarboxamide (9) which is excreted in human urine and its 3-carboxylic acid 8 were synthesized by condensation of silylated 6-oxo-3-pyridinecarboxamide 4 and the corresponding silylated 3-carboxylic acid 2 with 1,2,3,5-tetra-O-acetyl-β-D-ribofuranose in acetonitrile in the presence of tin tetrachloride. The ribosidation site in 8 and 9 was assigned by 1H and 13C NMR spectroscopy.
    Notes: Der NAD(P)-Coenzymmetabolit 1,6-Dihydro-6-oxo-1-(β-D-ribofuranosyl)-3-pyridincarbonsäureamid (9), der im menschlichen Harn ausgeschieden wird, und die entsprechende 3-Carbonsäure 8 wurden durch Kondensation von silyliertem 6-Oxo-3-pyridincarbonsäureamid 4 sowie dem Silylderivat 2 der entsprechenden 3-Carbonsäure mit 1,2,3,5-Tetra-O-acetyl-β-D-ribofuranose in Acetonitril bei Gegenwart von Zinntetrachlorid synthetisiert. Die Ribosidierungsposition in 8 und 9 wurde durch 1H- und 13C-NMR-Spektroskopie bestimmt.
    Additional Material: 1 Ill.
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  • 42
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 529-535 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Cycloaddition Reactions of Novel Thiocoumarin-3-carboxamidesThe synthesis of the novel thiocoumarin-3-carboxamides 5a - e by treatment of the azomethines 1a - e with carbon suboxide as well as their physical properties are described. 5c combines with 2,3-dimethyl-1,3-butadiene or 1,2-bis(methylene)cyclohexane to produce the [4 + 2] cycloadducts 6 or 7, respectively.
    Notes: Die Synthese der neuen Thiocumarin-3-carbonsäureamide 5a - e durch Behandlung der Azomethine 1a - e mit Kohlensuboxid und deren physikalische Eigenschaften werden beschrieben. 5c vereinigt sich mit 2,3-Dimethyl-1,3-butadien oder 1,2-Bis(methylen)cyclohexan zu den [4 + 2]-Cycloaddukten 6 bzw. 7.
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  • 43
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 1-21 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Organophosphorus Compounds, 110.  -  Specific Fluorescence Labelling of Serine EnzymesCompounds of the type R1R2P(O)X [X = F, OC6H4NO2-(4)] are OH-selective and react with the serine hydroxy group in the active site of esterases (α-chymotrypsine, trypsine, butyrylcholinesterase, acetylcholinesterase, and subtilisine) to form the corresponding inactive phosphoryl esters [R1R2P(O)-O-Ser-esterase]. The fluorescent and chemoselective reagents 1-7 are synthesized using the following ligands: R1 = 5-(dimethylamino)naphthyl and 5-methoxynaphthyl, R2 = alkyl, aryl, O-alkyl. They inhibit the above mentioned esterases specifically. The dependence of the inhibition from the concentration of the inhibitors was determined. It was proved by gel electrophoresis that the fluorescent inhibitor is covalently linked to the esterase. On the basis of linear dependency of the intensity of fluorescence and activity of α-chymotrypsine a ratio of 1:1 was found for the ratio of esterase: inhibitor. This opens a new method for the analytical determination serine enzymes. The inhibited esterases are reactivated with varied success by 2-PAM or toxogonine.
    Notes: Verbindungen vom Typ R1R2P(O)X [X = F, OC6H4NO2-(4)] sind OH-selektiv und reagieren mit der Serinhydroxygruppe im aktiven Zentrum von Esterasen (α-Chymotrypsin, Trypsin, Butyrylcholinesterase, Acetylcholinesterase und Subtilisin) unter Bildung des entsprechenden inaktiven Phosphorylesters [R1R2P(O)-O-Ser-Esterase]. Mit R1 = 5-(Dimethylamino)naphthyl bzw. 5-Methoxynaphthyl und R2 = Alkyl, Aryl, O-Alkyl erhält man die chemoselektiven, fluoreszierenden Reagenzien 1-7, welche die oben genannten Esterasen spezifisch hemmen. Es wurde a) die Abhängigkeit der Inhibierung von der Konzentration der Inhibitoren bestimmt und b) durch Gelelektrophorese des inhibierten Enzyms gezeigt, daß der fluoreszierende Inhibitor covalent mit dem Enzym verknüpft ist. Aus der linearen Abhängigkeit der Fluoreszenzintensität von der Enzym-Aktivität ergibt sich bei α-Chymotrypsin ein Verhältnis für Esterase/Inhibitor von 1:1 Dieses Verhalten ist die Grundlage für eine quantitative Bestimmung der oben genannten Serin-Enzyme. Die inhibierten Esterasen können mit unterschiedlichem Erfolg durch 2-PAM oder Toxogonin reaktiviert werden.
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  • 44
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 40-50 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Potentiostatic Electroreductive Cleavage of S—S Bridges and Fluorescence Marking of Insuline (Beef)The three S—S bridges of insuline are cleaved galvanostatically forming the SH-A and the SH-B chain (mixture of products I). The selective reductive cleavage of the interchenaric S-S bonds of insuline is possible by using potentiostatic techniques (-1.3 V vs. SCE) forming the mixture of products II. The four SH groups in the product mixture II are blocked by reaction with the vinyl sulfone 1 (mixture of products III). The intrachenaric S—S bridge of the partially with 1 blocked chain A in the product mixture III is potentiostatically opened at -1.8 V (vs. SCE) and blocked by the fluorescent aryl vinyl sulfone 2 (mixture of products IV). In the same way the SH groups in the product mixtures I and II are selectively blocked and marked by the fluorescent vinyl sulfones 2 and 3.
    Notes: Die drei S—S-Brücken im Insulin können galvanostatisch unter Bildung der SH-A-Kette und der SH-B-Kette (Produktgemisch I) aufgespalten werden. Potentiostatisch gelingt bei -1.3 V (vs. SCE) die selektive Öffnung der zwei interchenaren Disulfidbrücken (Produktgemisch II). Die vier SH-Gruppen im Produktgemisch II werden mit dem Vinylsulfon 1 blockiert (Produktgemisch III). Im Produktgemisch III wird die intrachenare Disulfidbrücke in der teilblockierten A-Kette bei -1.8 V (vs. SCE) potentiostatisch reduktiv geöffnet und mit dem fluoreszierenden Arylvinylsulfon 2 geschützt (Produktgemisch IV). Auch die SH-Gruppen in den Produktgemischen I und II werden durch die fluoreszierenden Vinylsulfone 2 und 3 selektive verschlossen und damit fluoreszenzmarkiert.
    Additional Material: 8 Ill.
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  • 45
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 58-64 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Alkylation, Acylation, and Carbamoylation Products of 5-Methylene-1,3-thiazolidine-2-thioneThe reaction product of prop-2-inylamine and carbon disulfide was contrary to earlier results identified as 5-methylene-1,3-thiazolidine-2-thione (3a). This was reacted with alkyl halides, acyl, carbamoyl, and thiocarbamoyl chlorides. The structures of the N- respective S-substitution products and the tautomeric relations were confirmed by 13C NMR spectroscopy.
    Notes: Das Umsetzungsprodukt von Prop-2-inylamin und Schwefelkohlenstoff wurde entgegen früheren Befunden als 5-Methylen-1,3-thiazolidin-2-thion (3a) identifiziert und dieses mit Alkylhalogeniden, Acyl-, Carbamoyl- und Thiocarbamoylchloriden umgesetzt. Die Strukturzuordnung der N- bzw. S-Substitutionsprodukte sowie die Tautomerieverhältnisse wurden durch 13C-NMR-Spektroskopie geklärt.
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  • 46
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemistry of Reactive Cations Derived from Sulfur Dioxide Analogues, XII.  -  Stereochemistry of the Heterometathesis with Cyclic Sulfoxides  -  Turnstile Rotation in the Intermediate σ-SulfuranesIn the heterometathesis of cyclic sulfoxides with N-Methyl-N-sulfinylmethanaminium tetrafluoroborate (1a), both diastereomers yield the same product, in each case, the reactions proceed with retention or inversion, respectively. This behavior is explained by turnstile rotations in the intermediate σ-sulfuranes, the most stable form of which are observed in the NMR spectra.
    Notes: Bei der Heterometathesereaktion cyclischer Sulfoxide mit N-Methyl-N-sulfinylmethanaminium-tetrafluoroborat (1a) geben jeweils beide Diastereomere dasselbe Produkt - unter Retention bzw. Inversion der Konfiguration. Zur Erklärung wird Turnstile-Rotation in den σ-Sulfuran-Zwischenprodukten zur stabilsten (im NMR-Spektrum nachweisbaren) Form angenommen.
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  • 47
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 90-102 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nonproteinogenic Amino Acids, II.  -  Synthesis and Determination of the Absolute Configuration of (2S,4S)-(-)- and (2S,4R)-(+)-5,5,5-TrifluoroleucineThe synthesis (Scheme 1) of racemic 4,4,4-trifluoro-3-methyl-1-butanol (5) and the resolution of its enantiomers is described. The absolute configuration of the negatively rotating enantiomer of 5 is correlated to that of the optically active fermentation amyl alcohol (S-10) via (S)-(-)-1,1,1-trifluoro-2-methylbutane (S-8) (Scheme 2). Oxidation of optically pure (R)-(+)-4,4,4-trifluoro-3-methyl-1-butanol (R-5) yields the aldehyde R-6 which is employed as starting material for the asymmetric Strecker synthesis of (2S,4R)-(+)-5,5,5-trifluoroleucine (13a). The analogous synthesis with (+)-4,4,4-trifluoro-3-methyl-1-butanol (6) via the aminonitrile 11 affords the optically pure (2S,4S)-diastereoisomer 11b which leads to enantiomerically pure (2S,4S)-(-)-5,5,5-trifluoroleucine (13b).
    Notes: Es werden Synthese (Schema 1) und Enantiomerentrennung von racemischem 4,4,4-Trifluor-3-methyl-1-butanol (5) beschrieben. Die absolute Konfiguration von (-)-5 wird an die des optisch aktiven Gärungs-Amylalkohols (S-10) über das (S)-(-)-1,1,1-Trifluor-2-methylbutan (S-8) angeschlossen (Schema 2). Durch Oxidation des optisch reinen (R)-(+)-4,4,4-Trifluor-3-methyl-1-butanols (R-5) wird der Aldehyd R-6 hergestellt, der als Edukt für die asymmetrische Strecker-Synthese (Schema 3) von (2S,4R)-(+)-5,5,5-Trifluorleucin (13a) eingesetzt wird. Durch analoge Synthese mit (+)-4,4,4-Trifluor-3-methyl-1-butanal (6) läßt sich auf der Stufe der Aminonitrile 11 das (2S,4S)-Diastereomere 11b optisch rein erhalten, das zu enantiomerenreinem (2S,4S)-(-)-5,5,5-Trifluorleucin (13b) führt.
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  • 48
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 113-128 
    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, XXVIII.  -  Synthesis of 6-Amino-6-deoxyhepturonic AcidsThe reaction of the xylo-dialdehyde 1 with ethyl nitroacetate yields the adduct 3 which by treatment with Raney nickel in acetic anhydride leads to the chromatographically separable derivatives of 6-acetamido-6-deoxy-D-glycero-D-gluco-hepturonic acid 5 and 6-acetamido-6-deoxy-L-glycero-D-gluco-hepturonic acid 7. The configuration at C-5 of 5 and 7 was confirmed by conversion into the pyranoses 18 and 23 and analysis of their NMR spectra. The configuration at C-6 of 5 and 7 was based on the NMR data of the benzylidene derivatives 19, 20, and 24 which were accessible from 15 and 21. Stepwise deblocking reactions of compounds 5 and 7 furnish the unblocked 6-acetamido-6-deoxyheptopyranosuronic acids 27 and 30.
    Notes: Die Umsetzung des xylo-Dialdehydes 1 mit Nitroessigsäure-ethylester führt zum Addukt 3, das mit Raney-Nickel in Acetanhydrid zu den chromatographisch trennbaren Derivaten der 6-Acetamido-6-desoxy-D-glycero-D-gluco-hepturonsäure 5 und der 6-Acetamido-6-desoxy-L-glycero-D-gluco-hepturonsäure 7 führt. Die Konfigurationszuordnung an C-5 von 5 und 7 erfolgte durch Überführung in die Pyranosen 18 und 23 und Analyse ihrer NMR-Spektren. Die Zuordnung der Konfiguration an C-6 von 5 und 7 gelang durch NMR-spektroskopische Untersuchungen der über 15 und 21 darstellbaren Benzylidenverbindungen 19, 20 und 24. Durch stufenweise Entblockierung sind die freien 6-Acetamido-6-desoxyheptopyranuronsäuren 27 und 30 zugänglich.
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  • 49
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 142-148 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Phosphorpentoxid in der Organischen Synthese, XII.  -  Synthese von 7H-Pyrrolo[2,3-d]-pyrimidin-4-aminenEs wird ein einstufiges Verfahren zur Herstellung einiger neuer substituierter 7H-Pyrrolo[2,3-d]-pyrimidin-4-amine 2 beschrieben. Dazu werden die entsprechenden Pyrrolo[2,3-d]pyrimidin-4(3H)-one 1 in einer Mischung aus Phosphorpentoxid, N,N-Dimethylcyclohexylamin und dem geeigneten Amin-hydrochlorid erhitzt. Bei Hydrochloriden aromatischer Amine verläft die Reaktion glatt bei 200-220°C innerhalb von 1-4h, Hydrochloride aliphatischer Amine hingegen reagieren langsamer und liefern die Produkte 3 in geringer Ausbeute. Im Fall von Diethylamin-hydrochlorid wird zusammen mit dem erwarteten Produkt 3e das dimere Kondensationsprodukt 5 isoliert. Ferner werden die Ergebnisse von Pestizid-Eignungstests mitgeteilt.
    Notes: A one-step synthesis for the preparation of a new series of substituted 7H-pyrrolo[2,3-d]pyrimidin-4-amines 2 is described. The method consists in heating the corresponding pyrrolo [2,3-d]pyrimidin-4(3H)-ones 1 in a mixture of phosphorus pentoxide, N,N-dimethylcyclohexylamine, and the appropriate amine hydrochloride. With aromatic amine hydrochlorides the reaction proceeds smoothly at 200-220°C for 1-4 h, whereas with aliphatic amine hydrochlorides, the reaction takes place at slower rate affording the products 3 in lower yields. With diethylamine hydrochloride, the condensed dimeric product 5 is isolated together with the expected product 3e. The results from pesticide screenings are reported.
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  • 50
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 149-159 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Protonation and Acylation Reactions of Acyclic Enamino Ketonesα,β-Unsaturated β-dialkylamino ketones 4 are converted by means of tetrafluoroboric acid into thermodynamically stable Cα-protonated iminium salts 5. β-(Dialkylamino)vinyl ketones are shown to exist preferentially in the E-s-cis and E-s-trans configuration 6, respectively. With tetrafluoroboric acid they form iminium salt mixtures of E/Z-isomers 7 which are protonated at the oxygen.  -  Enamino ketones of type 4 are substituted by trichloroacetyl or benzoyl chloride at the carbon in γ-position to the carbonyl group under formation of dihydropyran salts 10. With sodium carbonate these are converted into enamino diketones of type 8. As shown for 8a, for example, from these elimination of chloroform can be achieved by reaction with piperidine to form α-pyrones 14.
    Notes: α,β-Ungesättigte β-Dialkylaminoketone 4 reagieren mit Tetrafluoroborsäure zu den thermodynamisch stabilen Cc-protonierten Iminiumsalzen 5. β-(Dialkylamino)vinylketone liegen bevorzugt in der E-s-cis- und E-s-trans-Konfiguration 6 vor und bilden mit Tetrafluoroborsäure E/Z-Isomeren-Gemische am Sauerstoff protonierter Iminiumsalze 7.  -  Enaminoketone des Typs 4 werden durch Trichloracetyl- oder Benzoylchlorid an dem zur Carbonylgruppe γ-ständigen Kohlenstoff unter Bildung von Dihydropyransalzen 10 substituiert, deren Umsetzung mit Natriumcarbonat zu Enaminodiketonen 8 führt. Diese reagieren mit Piperidin, wie am Beispiel von 8a gezeigt wird, unter Abspaltung von Chloroform zu α-Pyronen 14.
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  • 51
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 194-202 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: First Synthesis of rac-Homofenchone (1,4,4-Trimethylbicyclo[3.2.1]octan-3-one)The rac-homofenchone (2), which was previously unknown, is prepared starting from the cyclohexenecarboxylate 4 via the bicyclo[3.2.1]octene 13 by two independent routes. The key steps are either the intramolecular acylation of a C=C bond in 9 induced by trifluoroacetic acid anhydride, or the BF3-catalyzed decomposition of the diazomethyl ketone 15. From 13 a direct path leads to homofenchone (2), the NMR spectra of which were fully assigned.
    Notes: Das bislang unbekannte rac-Homofenchon (2) läßt sich ausgehend vom Cyclohexencarbonsäureester 4 über das Bicyclo[3.2.1]octen 13 auf zwei unabhängigen Wegen gewinnen. Schlüsselschritte stellen dabei wahlweise entweder die mit Trifluoressigsäureanhydrid induzierte innermolekulare Acylierung einer C=C=Bindung in 9 dar, oder die BF3-katalysierte Zersetzung des Diazomethylketons 15. Von 13 führt ein direkter Weg zum Homofenchon (2), dessen Kernresonanz-Spektren vollständing zugeordnet wurden.
    Additional Material: 1 Ill.
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  • 52
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 210-213 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Functionalized Crown Ethers of the Type [18]Crown-6The synthesis of crown ethers1) of the type [18]crown-6 with two functionalized and nonvicinal groups is described. The first hydroxy compound of this type has been synthesized and the chemical and complexing properties have been investigated. The new compounds are especially useful for further syntheses of [18]crown-6 derivatives.
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  • 53
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stereoselective Synthesis of Long-chain 1-O-(β-D-Maltosyl)-3-O-alkyl-sn-glycerols (Alkyl Glyceryl Ether Lysoglycolipids)The synthesis of long-chain 2-O-benzyl-3-O-benzyl-3-O-alkyl-sn-glycerols 5 was improved, making these compounds easily accessible for glycosylation experiments. Glycosylation with α-acetobromomaltose following a modified Koenigs-Knorr procedure after removal of the protective groups yielded the title compounds 9 in good yields. These compounds represent examples of alkyl glyceryl ether lysoglycolipids. Some properties of these amphiphilic compounds with a nonionic carbohydrate head-group differ not much (critical micell concentration, hemolytic activity), other properties differ very much (antitumor efficiency) from the properties of the analogous compounds with a zwitterionic phosphorylcholine head-group.
    Notes: Die Synthese langkettiger 2-O-Benzyl-3-O-alkyl-sn-glycerine 5 konnte so verbessert werden, daß diese Verbindungen in ausreichenden Ausbeuten für Glycosylierungsversuche zur Verfügung stehen. Die Glycosylierung dieser Verbindungen mit α-Acetobrommaltose nach einem modifizierten Koenigs-Knorr-Verfahren führt nach Entfernung der Schutzgruppen in guten Ausbeuten zu den Titelverbindungen 9, die Vertreter der Alkylglycerylether-Lysoglycolipide sind. Einige Eigenschaften dieser amphiphilen Verbindungen mit einer nichtionischen Kohlenhydratkopfgruppe unterscheiden sich kaum (kritische Micellenkonzentration, hämolytische Aktivität), andere sehr stark (Antitumorwirkung) von den Eigenschaften der analogen Verbindungen mit zwitterionischer Phosphorylcholinkopfgruppe.
    Additional Material: 1 Tab.
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  • 54
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 251-274 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Dimeric Naphthoquinones, XII.  -  On the Selectivity of the Addition of Diazomethane to Benzenoid-substituted 1,4-NaphthoquinonesPure isomeres of 1-methylbenz[f]indazolequinones (type 6b) were synthesized for the first time by “diazomethane degradation” of regiospezifically formed 2,2′-bi-1,4-naphthoquinones (20, 21). With knowledge of their behaviour, the ratio of isomers obtained by addition of diazomethane to 2,3-unsubstituted 1,4-naphthoquinones was determined and correlated with predictions from HMO calculations.
    Notes: Durch “Diazomethan-Abbau” regiospezifisch gebildeter 2,2′-Bi-1,4-naphthochinone (20, 21) wurden erstmals isomerenreine 1-Methylbenz[f]indazol-4,9-chinone (Typ 6b) definierter Struktur erhalten. Mit Kenntnis von deren Eigenschaften konnte das Verhältnis der aus 2,3-unsubstituierten 1,4-Naphthochinonen (23a-58a) und Diazomethan entstehenden Regioisomeren bestimmt und mit Vorhersagen aus HMO-Rechnungen korreliert werden.
    Additional Material: 1 Ill.
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  • 55
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 301-306 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the “Normalizing Factor” for the Tomato Mutant chloronerva, XX  -  Homologues of NicotianamineThe syntheses of the nicotianamine homologues (2S,αS)-α-〈[(4S)-4-amino-4-carboxybutyl]-amino)-2-carboxy-1-azetidinepentanoic acid (8) and the corresponding proline compound 11 were achieved by stepwise combination of the ethyl esters of (S)-2-azetidinecarboxylic acid or (S)-proline with ethyl (S)-5-oxo-2-(trifluoroacetylamino)pentanoate (4) via reductive coupling. The amino acids 8 and 11 exhibit no biological effect on the phenotypical normalization of the tomato mutant chloronerva.
    Notes: Die Homologen des Nicotianamins (2S,αS)-α-〈[(4S)-4-Amino-4-carboxybutyl]amino〉-2-carboxy-1-azetidinpentansäure (8) und die entsprechende Prolin-Verbindung 11 wurden durch stufenweise reduktive Vereinigung der Ethylester von (S)-2-Azetidincarbonsäure oder (S)-Prolin mit (S)-5-Oxo-2-(trifluoracetylamino)pentansäure-ethylester (4) synthetisiert. Die Aminosäuren 8 und 11 zeigen keine biologische Wirkung auf die phänotypische Normalisierung der Tomatenmutante chloronerva.
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  • 56
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 275-300 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Formation and Reactivity of Hydroxy-substituted γ- and δ-LactonesHydrolysis of the esters (Z)-6-8 with H2SO4 in acetone leads to a mixture of γ- (17-19) and δ-Lactones (13-15) in various ratios. From (Z)-9 the rearrangement product 20 is obtained. By reaction of (Z)-6-9 with Et2O-BF3 the δ-lactones 13-16 are formed only. The saturated esters 10-12 hydrolyze to give a γ/δ-lactone mixture 24-26/21-23. Changing to BF3 favors the rearrangement 10 → 30.  -  The δ-lactones 13-16 are not dehydrated with POCl3 in pyridine but chlorinated to afford 31  -  34. On heating in pyridine 33 and 34 are dehydrochlorinated to give the α-pyrones 38 and 39. Dechlorination with zinc in acetic acid leads to β,γ-unsaturated δ-lactones (31, 35, → 44; 32 → 45; 33 → 46). The mixture of saturated γ/δ-lactones 21b/24a/24b yields with POCl3 the elimination products 50 and 51, while a 23/26a/26b mixture furnishes the unsaturated γ-lactones 53a, b, and 54 as well as the chlorinated δ-lactone 55. Hydrogenation (44 → 56; 45 → 57; 46 → 58; 51 → 59; 53/54 → 60) gives the saturated parent compounds.
    Notes: Hydrolyse der Ester (Z)-6-8 mit H2SO4 in Aceton führt zu Gemischen von γ- (17-19) und δ-Lactonen (13-15) in wechselnden Anteilen. Aus (Z)-9 wird das Umlagerungsprodukt 20 erhalten. Bei der Reaktion von (Z)-6-9 mit Et2O-BF3 werden dagegen einheitlich die δ-Lactone 13-16 gebildet. Die gesättigten Ester 10-12 hydrolysieren zu einem γ/δ-Lactongemisch 24-26/21-23. Hier begünstigt der Wechsel zu BF3 die Umlagerung 10 → 30. Die δ-Lactone 13-16 werden mit POCl3 in Pyridin nicht dehydratisiert, sondern zu 31  -  34 chloriert. Durch Erhitzen in Pyridin werden 33 und 34 zu den α-Pyronen 38 und 39 dehydrochloriert. Entchlorierung mit Zink in Essigsäure führt zu β,γ-ungesättigten δ-Lactonen (31, 35 → 44; 32 → 45; 33 → 46). Das gesättigte γ/δ-Lactongemisch 21b/24a/24b ergibt mit POCl3 nur die Eliminierungsprodukte 50 und 51, während ein 23/26a/26b-Gemisch die ungesättigten γ-Lactone 53a, b und 54 sowie das chlorierte Lacton 55 liefert. Hydrierung (44 → 56; 45 → 57; 46 → 58; 51 → 59; 53/54 → 60) führt zu den gesättigten Grundgerüsten.
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  • 57
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 345-364 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 13C-NMR-Spektroskopische Synthesekontrolle von Alamethicin F 30 und seinen SegmentenAlle zur Totalsynthese des Alamethicin F 30 (1) aufgebauten Segmente wurden mittels 13C-NMR-Spektroskopie methanolischer Lösungen untersucht. Mit wenigen Ausnahmen waren alle Signale eindeutig durch Vergleich mit anderen Peptidspektren, gekoppelte Spektren und vor allem durch J-modulierte Spin-Echo-Experimente zuzuordnen. Erstmals konnte ein synthetisches und hochreines Alamethicin-Präparat durch 13C-NMR-Spektroskopie bei 100.6 MHz untersucht werden. Alle Resultate sind in voller Übereinstimmung mit den synthetisierten Zwischenstufen und dem Endprodukt sowie deren Konformationen, die aus dem Circulardichroismus und aus Röntgenstrukturanalysen entnommen werden können. Es wurde eine zum Teil überraschende Erhaltung der Konformation beim Übergang von kleineren zu größeren Segmenten beobachtet.
    Notes: All segments built up for the total synthesis of the α-helical antibiotic alamethicin F 30 (1) were investigated by 13C NMR spectroscopy of methanolic solutions. With a few exceptions the signals were unequivocally assignable by comparison with spectra of related peptides, by coupled spectra and J-modulated spin-echo experiments. For the first time a synthetic and highly pure alamethicin F 30 preparation could be studied by 13C NMR spectroscopy at 100.6 MHz. All results were in full agreement with the synthesized intermediates and the final product, and with their conformations as derived from circular dichroism and X-ray analysis. Partially there is a striking retention of conformation from smaller to larger segments.
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  • 58
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 321-344 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Totalsynthese des α-helikalen Eikosapeptid-Antibiotikums AlamethicinDas spannungsabhängige Membranporen-bildende Polypeptidantibiotikum Alamethicin F 30 (Ac-Aib-Pro-Aib-Ala-Aib-Ala-Gln-Aib-Val-Aib-Gly-Leu-Aib-Pro-Val-Aib-Aib-Glu-Gln-Phl, 1) wurde durch Segmentkondensationen synthetisiert. Es wurde über die Segmente 2 - 11 (4a) und 12 -20 (3a) racematfrei ( 〈0.8% D-Anteile) mit der Dicyclohexylcarbodiimid/1-Hydroxybenzotriazol- und der Mischanhydrid-Methode erhalten. Die Zwischenstufen wurden eindeutig charakterisiert durch chromatographische und physikalische Methoden einschließlich 13C-NMR, Circulardichroismus und Gaschromatographie an chiraler Phase. Die Segmente 2 - 6 (5a) und 12-20 (3) wurden auch durch Röntgenstrukturbestimmung untersucht.  -  Das Endprodukt 1 (150 mg) wurde ohne HPLC-Trennung in sehr hoher Reinheit und kristallin erhalten. Nach allen analytischen Daten und bei spektroskopischem und chromatographischem (HPLC, DC) Vergleich ist das Produkt 1 identisch mit der Hauptkomponente F 30 des mikroheterogenen, aus Trichoderma viride isolierten antibiotischen Metaboliten. Die antibiotischen Aktivitäten von synthetischem Alamethicin (1) und die stimulierende Wirkung auf die Calcium/Calmodulin-abhängige Guanylatcyclase von Paramecium sind identisch mit denen von natürlichem Alamethicin. Das einheitliche synthetische Alamethicin (1) zeigt bei Messungen an Lipiddoppelschicht-Membranen perfekt homogene Leitwerte von Einzelporen, wie sie bisher weder von einem synthetischen noch von einem gereinigten natürlichen Präparat berichtet wurden.
    Notes: The voltage-dependent membrane pore-forming polypeptide antibiotic alamethicin F 30 (Ac-Aib-Pro-Aib-Ala-Aib-Ala-Gln-Aib-Val-Aib-Gly-Leu-Aib-Pro-Val-Aib-Aib-Glu-Gln-Phl, 1) was synthesized by segment condensations. It was obtained free of racemate ( 〈0.8% D-components) via the segments 2 - 11 (4a) and 12-20 (3a) using the dicyclohexylcarbodiimide/1-hydroxybenzotriazole and the mixed anhydride methods. The intermediates were unequivocally characterized by chromatographic and physical methods including 13C NMR, circular dichroism, and chiral phase gas chromatography. The segments 2-6 (5a) and 12-20 (3) were also proven by X-ray structure determinations.  -  The final product 1 (150 mg) was obtained without HPLC separations in very high purity and in crystalline form. According to all analytical data and the comparison by spectroscopy and chromatographic analyses (HPLC, DC) the product 1 is identical with the main component F 30 of the microheterogeneous antibiotic metabolite isolated from Trichoderma viride. The antibiotic activities of synthetic alamethicin (1) and the stimulating effect on calcium/calmodulin-dependent guanylate cyclase of Paramecium are identical with those of natural alamethicin. - The uniform synthetic alamethicin (1) shows perfectly homogeneous conductance states of single pores on measurements in lipid bilayer membranes which had not been reported so far for any synthetic or purified natural preparation.
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  • 59
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Formation of Chiral, Alicyclic Ethers by Addition of Carbohydrates to Cyclohexene in Hydrogen FluorideD-Ribose (1a) reacts with cyclohexene in liquid hydrogen fluoride to give (2R,3R3aR,4aR, 8 aS, 8bR)-perhydro-2-(hydroxymethyl)furo[3,2-b]benzofuran-3-ol (2a) and (3R,4R,4aR,5 aR,9 aS,9 bR)-perhydro-pyrano[3,2-b]benzofuran-3,4-diol (3a). Use of 5-O-methyl-D-ribofuranose (1b) leads exclusively to the formation of 2c, the 9-O-methyl derivative of 2a. Reaction of D-mannose (4), L-rhamnose (7), and D-erythro-pentulofuranose (9) yields the substitutionally isomeric, tricyclic ethers 5a, 6a, 8a, and 10; besides 10, sample 9 also yields the two tricyclic spiro ethers 11a and 11b.  -  The structure of 2a has been confirmed by an X-ray analysis.
    Notes: D-Ribose (1a) reagiert mit Cyclohexen in flüssigem Fluorwasserstoff zu (2R,3R3aR,4aR, 8 aS, 8bR)-Perhydro-2-(hydroxymethyl)furo[3,2-b]benzofuran-3-ol (2a) und (3R,4R,4aR,5 aR,9 aS,9 bR)-Perhydro-pyrano[3,2-b]benzofuran-3,4-diol (3a). Der Einsatz von 5-O-Methyl-D-ribofuranose (1b) führt zur ausschließlichen Bildung von 2c, dem 9-O-Methyl-Derivat von 2a. Die Umsetzung von D-Mannose (4), L-Rhamnose (7) sowie D-erythro-Pentulofuranose (9) führt zu den substitutionsisomeren tricyclischen Ethern 5a, 6a, 8a und 10; 9 liefert neben 10 auch die beiden tricyclischen Spiro-Ether 11a und 11b.  -  Die Struktur von 2a wurde durch eine röntgenographische Untersuchung bestätigt.
    Additional Material: 1 Ill.
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  • 60
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Terpenes and Terpenoid Compounds, 15.  -  Preparation of Tetramethylated Perillyl Alcohol [3,3,5,5-Tetramethyl-4-(1-methylethenyl)-1-cyclohexene-1-methanol] and Related MonoterpenoidsLithium perchlorate-induced rearrangement of 1,3,3,5,5-pentamethyl-4-(1-methylethenyl)-7-oxabicyclo[4.1.0]heptane (2) in toluene furnishes the epimeric tetramethylated dihydrocarvones 4t, c and 2,2,4,4-tetramethyl-6-methylene-3-(1-methylethenyl)-trans-cyclohexanol (5) in varying ratio. In acetic acid and formic acid the allylic alcohol 5 rearranges smoothly into the corresponding esters 6a and 6b which have been saponified quantitatively to yield tetramethylperillyl alcohol 7. Oxidation of tetramethylperillaldehyde 8 with air affords tetramethylperillic acid 9 in 54% yield. The epoxidation products of 5, 6a, and 7 are described.
    Notes: Die Lithiumperchlorat-induzierte Umlagerung von 1,3,3,5,5-Pentamethyl-4-(1-methylethenyl)-7-oxabicyclo[4.1.0]heptan (2) in Toluol liefert die epimeren Tetramethyldihydrocarvone 4t, c sowie 2,2,4,4-Tetramethyl-6-methylen-3-(1-methylethenyl)-trans-cyclohexanol (5) in variablem Verhältnis. In Essigsäure und Ameisensäure lagert sich der Allylalkohol 5 glatt in die entsprechenden Ester 6a und 6b um, die mit Alkali quantitativ zum Tetramethylperillaalkohol 7 verseift werden. Oxidation von Tetramethylperillaaldehyd 8 mit Luftsauerstoff ergibt Tetramethylperillasäure 9 in 54% Ausbeute. Die Produkte der Epoxidierung von 5, 6a und 7 werden beschrieben.
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  • 61
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 421-425 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis-Crown Ethers of TalopyranoseThe syntheses of mono- and bis-crown ethers of talopyranose 3a, b and 5a, b are described. A ‚sandwich effect′′ is not observed during complexation of tert-butylammonium rhodanide with 5a, b. The corresponding Ka values are surprisingly low. The ammonium ion seems to associate with the ligands preferentially from the ß face.
    Additional Material: 1 Tab.
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  • 62
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 430-432 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemoselective Fluorescence Studies with Subtilisin and “Thiosubtilisin”The serine hydroxy group in the active site of subtilisin is selectively “phosphylated”3). This is demonstrated using the fluorescent phosphinic fluoride 1. “Thiosubtilisin” does not react with 1 but with the SH-selective and fluorescent vinyl sulfone 2.
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  • 63
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 950-958 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Sila-Perfumes and Isosteric Compounds of Perfumes, 91). - Sila-β-ionone and Related CompoundsSynthesis of sila-β-cyclocitral 5, sila-β-ionone 7, of an rac-isomer 10 and of a dehydro compound 13 of sila-β-ionone was achieved. The preparations of the sila-β-cyclogeranium acid (6) and of the rac-sila-β-ionol (14) are also described. Comparison of the physical data and odors of the natural perfumes and their sila derivatives is given.
    Notes: Sila-β-Cyclocitral (5), Sila-β-Jonon (7), ein rac-Isomeres 10 und ein Dehydroderivat 13 des Sila-β-Jonons konnten dargestellt werden. Darüber hinaus gelang die Synthese der Sila-β-Cyclogeraniumsäure (6) und des rac-Sila-β-Jonols (14). Physikalische Daten und Gerüche der natürlichen Duftstoffe und ihrer Sila-Derivate werden verglichen.
    Additional Material: 1 Tab.
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  • 64
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cyclitol Reactions, XII. - Enantioselective Synthesis of the Central Pseudodisaccharide Unit of α-Glycosidase Inhibitors of the Oligostatine TypeA pseudodisaccharide unit of the α-glycosidase inhibitors of the oligostatine type has been synthesized. At first a synthesis of the enantiomeric pure derivative of the branched amino inositol 26 has been developed. A linkage of 26 with the reactive epoxide group of the 1,6:3,4-dianhydro sugar 36 yields the pseudodisaccharide 45, producing the desired linkage via an imino group. The opening of the 1,6-anhydro ring in the pseudodisaccharide 46 succeeds with acetanhydride/boron trifluoride. From the pseudodisaccharide the pure octaacetates 51 and 52 of the α- and β-anomers can be obtained. Deblocking of 51 and 52 to the free pseudodisaccharide causes a spontaneous rearrangement to the tricyclus 53 which contains a pyrrolidine sugar unit. In the pyranose form, the pseudodisaccharide can only exist as blocked compound or as glycoside.
    Notes: Eine Pseudodisaccharid-Einheit der α-Glycosidase-Inhibitoren des Oligostatin-Typs wurde synthetisiert. Hierzu wird zunächst eine Synthese des enantiomerenreinen Derivates des verzweigten Aminoinosits 26 entwickelt. Eine Verknüpfung von 26 mit der reaktiven Epoxidgruppe des 1,6:3,4-Dianhydrozuckers 36 führt zum Pseudodisaccharid 45, unter Herstellung der gewünschten Verknüpfung über eine Iminogruppe. Die öffnung des 1,6-Anhydroringes im Pseudodisaccharid 46 gelingt mit Acetanhydrid/Bortrifluorid. Vom Pseudodisaccharid sind die Octaacetate 51 und 52 der α- und β-Anomeren in reiner Form zu gewinnen. Bei Entblockierung von 51 und 52 lagert sich das freie Pseudodisaccharid spontan in den Tricyclus 53 um, der eine Pyrrolidinzucker-Einheit enthält. Das Pseudodisaccharid ist in der Pyranoseform nur als blockierte Verbindung oder als Glycosid beständig.
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  • 65
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Compounds with Reduced Porphin π-Systems: Synthesis of 12,13,17,18-Tetranorporphin, the Parent Compound of the IsobacteriochlorinsFor a comparison of the properties of porphin and isobacteriophin (4a), a synthesis of 4a via the macrocyclic diamine 3a was elaborated. The copper complex 3b can be dehydrogenated with platinum oxide in refluxing toluene to give 4b. Using the same reaction conditions, isobacteriophin (4a) and its platinum complex 4c were obtained only in very poor yields. 4a, however, is accressible in 2% yield by flash vacuum-thermodehydrogenation of 3a. The UV spectrum of 4a is similar to spectra of isobacteriochlorin derivatives. From comparison of the 1H NMR spectra of 4a and octaethylisobacteriochlorin and enhanced planarity of the conjugated system may be deduced as a consequence of the removal of the ethano bridges.
    Notes: Für einen Vergleich der Eigenschaften des Porphins und des Isobakteriophins (4a) wurde dieses über das makrozyklische Diamin 3a dargestellt. Der Kupfer-Komplex 3c läßt sich mit Platinoxid in siedendem Toluol zum Kupfer-Isobakteriophin (4b) dehydrieren. Die gleiche Reaktion an 3a ergibt nur geringe Mengen des Isobakteriophins (4a) und seines Platin-Komplexes 4c, 4a wird aus 3a in 2% Ausbeute durch Thermoflash-Dehydrierung erhalten. Das UV-Spektrum von 4a weist für Isobakteriochlorine typische Banden auf. Aus einem Vergleich der 1H-NMR-Spektren von 4a und Octaethylisobakteriochlorin läßt sich eine vermehrte Planarität des Konjugationssystems beim Fortfall der Ethanobrücken ableiten.
    Additional Material: 3 Tab.
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  • 66
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    Liebigs Annalen 1985 (1985), S. 1036-1040 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese von 5′-[(3-Aminooxypropyl)amino]-5′-desoxyadenosinDie Synthese der Titelverbindung 2 wird beschrieben. N-Alkylierung von 5′-Amino-5′desoxy-2′,3′-O-(1-methylethyliden)adenosin (3) mit [(3-Iodpropoxy)methyl]benzol gab nach Entfernung der Benzylgruppe das 5′-Desoxyadenosin-Derivat 4b. Nach Schützen der NH-Gruppe an C-5′ konnte die terminale OH-Gruppe mit Triphenylphosphan, Diethyl-azodicarboxylat und N-Hydroxyphthalimid umgesetzt werden. Man erhält einen vollständig geschützten Vorläufer von 2, der nach Behandlung mit Hydrazinhydrat und Schwefelsäure die Zielsubstanz 2 als Sesquisulfat ergibt.
    Notes: The synthesis of the title compound 2 is described. N-Alkylation of 5′-amino-5′-deoxy-2′,3′-O-(1-methylethylidene)adenosine (3) with [(3-iodopropoxy)methyl]benzene gave after debenzylation the 5′-deoxyadenosine derivative 4b. After derivatization of the 5′-NH, the terminal hydroxy group was reacted with triphenylphosphane, diethyl azodicarboxylate, and N-hydroxyphthalimide to yield a full protected derivative of 2. Sequential deprotection (H2NNH2, then H2SO4) afforded the target molecule 2 as its sesquisulfate salt.
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  • 67
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 1041-1062 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Sequenz und Konformation von Suzukacillin ADie Sequenz des spannungsabhängige Membranporen bildenden Polypeptidantibiotikums Suzukacillin A wurde bestimmt durch eine Kombination von trifluoracetolytischer Spaltung, präparativer Isolierung von Fragmenten und Analyse durch Gaschromatographie - Massenspektrometrie sowie Felddesorptions- und Fast-Atom-Bombardment-Massenspektrometrie. Suzukacillin A ist ein mikroheterogenes Eikosapeptidantibiotikum (Ac-Aib-L-Ala-Aib-Ala-Aib-Ala(Aib)-Gln-Aib-Aib(Leu)-Aib-Gly-Leu-Aib-Pro-Val-Aib-Aib(D-Iva)-Gln-Gln-Phl) mit einer Sequenz, einer α-helicalen Konformation (nach13C-NMR- und Circulardichroismus-Messungen) und membranmodifizierenden Eigenschaften, die dem Alamethicin ähnlich sind.
    Notes: The sequence of the potential-dependent membrane pore-forming polypeptide antibiotic suzukacillin A was determined by a combination of trifluoroacetolytic cleavage, preparative isolation of fragments, and analysis by gas chromatography - mass spectrometry, field-desorption and fast-atom bombardment mass spectrometry. Suzukacillin A is a microheterogeneous eicosapeptide antibiotic (Ac-Aib-L-Ala-Aib-Ala-Aib-Ala(Aib)-Gln-Aib-Aib(Leu)-Aib-Gly-Leu-Aib-Pro-Val-Aib-Aib(D-Iva)-Gln-Gln-Phl) with a sequence, an α-helical conformation (according to 13C NMR and circular dichroism), and membrane-modifying properties related to alamethicin.
    Additional Material: 13 Ill.
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  • 68
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemistry and Stereochemistry of Iridoids, V. - Crystal and Molecular Structure of Hexaacetylleonuride - Stereochemical Correlations of Some Iridoid GlucosidesLeonuride (ajugol, 1a) and myoporoside (2) are C-6 epimers, the configurations of which are specified differently in the literature. By X-ray structure analysis of hexaacetylleonuride (1d) the absolute configuration of leonuride (1a) is fixed, to which the configurations of catalpol (3a), antirrhinoside (6a), and harpagide (7a) as well as procumbide (14a) and 6-epi-harpagide (15a) are linked by chemical correlation.
    Notes: Leonurid (Ajugol, 1a) und Myoporosid (2) sind C-6-Epimere, deren Konfigurationen in der Literatur verschieden angegeben werden. Durch Röntgenstrukturanalyse des Hexaacetylleonurids (1d) wird die absolute Konfiguration von Leonurid (1a) festgelegt, an die durch chemische Korrelation die Konfigurationen von Catalpol (3a), von Antirrhinosid (6a) und Harpagid (7a) sowie von Procumbid (14a) und 6-epi-Harpagid (15a) angeschlossen werden.
    Additional Material: 7 Tab.
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  • 69
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    Liebigs Annalen 1985 (1985), S. 1093-1094 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Note on the Synthesis of 3-[Alkyl(Aryl)thio]isoindolinones from Methyl 2-FormylbenzoateIn a one-pot procedure the isoindolinone derivatives 6 have been obtained from methyl 2-formylbenzoate, primary amines, and thiols via the intermediate imines 1.
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  • 70
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    Liebigs Annalen 1985 (1985), S. 579-588 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 2-Oxosulfonamides, II. - Reactions of 2-Oxosulfonamides with Carbonyl CompoundsIn reactions with carbonyl compounds 2-oxosulfonamides not only act monofunctionally as ketones, active-hydrogen compounds or sulfonamides, but often they react bifunctionally with formation of cyclic compounds. They thus can serve as novel building blocks for the synthesis of heterocycles.
    Notes: In Reaktionen mit Carbonylverbindungen fungieren 2-Oxosulfonamide nicht nur monofunktionell als Keton, methylenaktive Verbindung oder Sulfonamid, sondern häufig auch bifunktionell unter Bildung cyclischer Verbindungen. Sie können somit als neuartige Bausteine für die Synthese von Heterocyclen dienen.
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  • 71
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nonproteinogenic Amino Acids, III. - Syntheses of the Enantiomerically Pure 2-(2-Thienyl)-and 2-(3-Thienyl)glycines. - Molecular Structure of the Intermediate Schiff's BasesThe syntheses of enantiomerically pure D-(-)- and L-(+)-2-(2-thienyl)- and 2-(3-thienyl)glycines (6a - d) are described. Preparing the amino nitriles 4 directly from 2-thiophenecarbaldehyde (1a) or 3-thiophenecarbaldehyde (1b), respectively, and (4S, 5S)-(+)-5-amino-2,2-dimethyl-4-phenyl-1,3-dioxane (2), and hydrocyanic acid (one-step procedure), the aminonitriles 4a and 4b, respectively, are formed in excess. By crystallization they are obtained diastereomerically pure leading to enantiomerically pure D-amino acids 6a and 6b. If, however, the intermediate Schiff's bases 3 are isolated as crystals and then converted with hydrocyanic acid into the respective aminonitriles 4 (two-step procedure), the diastereomeric aminonitriles 4c and 4d, respectively, crystallize resulting in enantiomerically pure L-amino acids 6a and 6d. X-ray structure analyses of the Schiff's bases 3c and 3e revealed the previously postulated E-configuration of the C = N bond and its chiral shielding by the phenyl substituent at C4.
    Notes: Es wird die Synthese von enantiomerenreinem D-(-)-und L-(+)-2-(2-Thienyl)- und 2-(3-Thienyl)-glycin (6a - d) beschrieben. Werden die Aminonitrile 4 direkt aus 2-Thiophencarbaldehyd (1a) oder 3-Thiophencarbaldehyd (1b), (4S,5S)-(+)-5-Amino-2,2-dimethyl-4-phenyl-1,3-dioxan (2) und Blausäure hergestellt (Einstufen-Verfahren), so entstehen im Überschuß die Aminonitrile 4a und 4b, die durch Kristallisation diastereomerenrein erhalten werden und zu den enantiomerenreinen D-Aminosäuren 6a und 6b führen. Werden dagegen die Schiffschen Basen 3 kristallin isoliert und mit Blausäure zu den entsprechenden Aminonitrilen 4 umgesetzt (Zweistufen-Verfahren), so kristallisieren die diastereomeren Aminonitrile 4c und 4d aus, die zu den enantiomerenreinen L-Aminosäuren 6c und 6d führen. Die Röntgenstrukturanalysen der Schiffschen Basen 3c und 3e bestätigen die früher angenommene E-Konfiguration der C = N-Bindung und deren chirale Abschirmung durch den Phenylsubstituenten an C4.
    Additional Material: 1 Ill.
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  • 72
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 605-619 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Dimeric Naphthoquinones, XIV. - Intermediates of the cyclo- Trimerization of Naphthoquinone: Synthesis of Hydroxyhepta[2.2.2]starphenequinonesDehydrogenation of hepta[2.2.2]starphene-5,6,11,12,17,18-hexaol (3a) with one molar equivalent of 1,4-naphthoquinone (1) yields nearly quantitatively the blue-green 5,12,17,18-tetra-hydroxyhepta[2.2.2]starphene-6,11-quinone 4. Oxidation of 3a with two molar equivalents of 1 affords a 4/6 mixture of the expected diquinone 5. From the yellow tetraacetate 7b were obtained by regioselective deacetylation the blue triacetate 7c, the blue-green diacetate 9, its isomer 11 and, by rearrangement, red 14a. Oxidation of 7c yields 8a, the acetate of the intermediate 5 of the 3a dehydrogenation. 9 and 11 are oxidized by silver oxide to give the green diquinone 10a and the violet 12a, respectively, which both rearrange in pyridine by acyl migration forming 8a. The colour of the quinones is due to donor-acceptor interactions.
    Notes: Dehydrierung von Hepta[2.2.2]starphen-5,6,11,12,17,18-hexaol (3a) mit einem Moläquivalent 1,4-Naphthochinon (1) führt fast quantitativ zu blaugrünem 5,12,17,18-Tetrahydroxyhepta-[2.2.2]starphen-6,11-chinon (4). Oxidation von 3a mit zwei Moläquivalenten 1 liefert dagegen statt des erwarteten Dichinons 5 ein 4/6-Gemisch. Aus dem gelben Tetraacetat 7b von 4 erhält man durch gezielte regioselektive Entacetylierung das blaue Triacetat 7c, das blaugrüne Diacetat 9, sein Isomeres 11 und unter Umlagerung rotes 14a. Ammonium-cer(IV)-nitrat oxidiert 7c zum Diacetat 8a des gesuchten Zwischenproduktes 5 der 3a-Dehydrierung. Silberoxid überführt 9 in das grüne Dichinon 10a und 11 in das violette Dichinon 12a, die sich in Pyridin unter Acylwanderung in 8a umlagern. Die Farben der Chinone lassen sich durch Donor-Acceptor-Wechselwirkungen erklären.
    Additional Material: 1 Tab.
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  • 73
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Macrocyclic Trichothecenes from Baccharis coridifolia, II. - Miotoxin D and Isomiotoxin D, Two New Macrocyclic Trichothecenes from Baccharis coridifolia DCFrom the chloroform extract of the toxic South Brazilian plant Baccharis coridifolia, two further macrocyclic trichothecenes were isolated. The structures of these new substances, named miotoxin D (2a) and isomiotoxin D (2b), were elucidated by two-dimensional NMR techniques and FD-mass spectrometry.
    Notes: Aus dem Chloroformextrakt der toxischen südbrasilianischen Pflanze Baccharis coridifolia wurden zwei weitere macrocyclische Trichothecene isoliert. Die Strukturen dieser neuen, als Miotoxin D (2a) und Isomiotoxin D (2b) bezeichneten Substanzen wurden durch zweidimensionale FT-NMR-Techniken und FD-Massenspektroskopie aufgeklärt.
    Additional Material: 4 Ill.
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  • 74
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    Liebigs Annalen 1985 (1985), S. 644-649 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemical Modification of Kanamycin A. - Derivatives Containing a 4,5-Double Bond in the Kanosamine PartOxidation of the primary alcohol group in the kanamycin A derivative 2b with simultaneous β-elimination gave the α,β-unsaturated aldehyde 3a of which the derivatives 3b - e were prepared by acetalisation, oxidation, or reduction. Hydrogenation of the double bond led to 4 ‚-deoxy-5‘-epi-kanamycin A derivatives.
    Additional Material: 1 Tab.
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  • 75
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    Liebigs Annalen 1985 (1985), S. 653-655 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthetische Wege zu Aminozuckern. - Effiziente Eintopfsynthese von einigen neuen DiazidodidesoxyzuckernDie Synthese der Diazidodidesoxyzucker 3 - 6 wird erstmalig beschrieben. Sie wurden durch ihre physikalischen Eigenschaften und spektroskopischen Daten charakterisiert. Ein neuer Zugang zu 2,4- und 3,4-Diaminodidesoxyzuckern der xylo- und arabino-Konfiguration wird von diesen Verbindungen vorgesehen.
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  • 76
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    Liebigs Annalen 1985 (1985), S. 673-682 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Hetero-Cope Rearrangements, III. - Vinylindoles via Hetero-Cope RearrangementThe reaction of N-phenylnitrones 1 with allenes 2 which are substituted with electron acceptor groups gives various products via addition and [3,3] sigmatropic rearrangements depending on the specific acceptor group. In this manner one obtains 2-substituted indoles 8a, 8b, and 10 from propadienyl trichloromethyl sulfoxide. Using phenyl propadienyl sulfone a derivative 4a of tetrahydro-1-benzazepin-4-one is obtained. Reactions with allenecarbonitril proceed via several steps and yield 2-vinylindoles of type 6. Intermediate products could not be isolated.
    Notes: Die Reaktion von N-Phenylnitronen 1 mit acceptorsubstituierten Allenen 2 führt via Addition und [3,3]-sigmatrope Umlagerung in Abhängigkeit vom Acceptor zu unterschiedlichen Produkten. So erhält man mit (Propadienyl)(trichlormethyl)sulfoxid 2-substituierte Indole 8a, 8b und 10. Mit (Phenyl)(propadienyl)sulfon wird ein Tetrahydro-1-benzazepin-4-onderivat 4a gebildet. Umsetzungen mit Allencarbonitril liefern über einen Mehrstufenprozeß direkt diverse 2-Vinyl-indole des Typs 6. Zwischenprodukte ließen sich nicht isolieren.
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  • 77
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Porphyrine in polymeren Matrizen, Micellen und Vesiklen, VII. - Hexadecahydro-29H, 31H-tetrabenzo[b,g,l,q]prophin und -octayl-octaacetatDie Titelverbindungen 5 und 10a wurden synthetisiert. Das Octaacetat 10a ergab bei Hydrolyse ein wasserlösliches Porphyrin, dessen Wechselwirkungen mit Vesikelmembranen charakterisiert wurden.
    Notes: The title compounds 5 and 10a were synthesized. The octaacetate 10a was hydrolyzed to give a water-soluble porphyrin. Its interactions with vesicle membranes were characterized.
    Additional Material: 2 Ill.
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  • 78
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 708-714 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Multistep Reversible Redox Systems, XLI. - 4,4′-Vinylenebis(pyrylium) SaltsThe redox systems 1a and 1b are synthesized by a new route and characterized by their UV/VIS spectra. Their redox potentials and semiquinone formation constants KSEM (1a: 3.2·103; 1b: 2.2·103) are compared with those of related systems.
    Notes: Die Redoxsysteme 1a und 1b werden auf einem neuen Wege dargestellt und durch ihre UV/VIS-Spektren charackterisiert. Ihre Redoxpotentiale und Semichinonbildungskonstanten KSEM (1a: 3.2·103; 1b: 2.2 · 103) werden mit denen verwandter Systeme verglichen.
    Additional Material: 2 Tab.
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  • 79
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Multistep Reversible Redox Systems, XLIII. - Voltammetry of α-Strylpyrylium Salts, (1,3-Cyclobutanediyl)-, and (1,3-Cyclobutanediylidene)bis(pyrylium) SaltsCyclic voltammetry of the α-styrylpyrylium salts 2, 4, and 6 discloses irreversible reduction and oxidation steps which can be interpreted according to Scheme 1. 1,3-Bis(pyrylium)cyclobutanes 7, 8, and 9 are reductively cleaved to give styrylpyrylium salts by an ECE mechanism (Scheme 2). By two-electron transfer bis(pyranylidene)cyclobutanes 22 are reversibly transformed into short-lived bicyclobutanes K, which isomerize to yield butadienes M. Thus, the electrochemical behaviour of the pyrylium derivatives investigated closely resembles that of the corresponding pyridine derivatives.
    Notes: Cyclische Voltammetrie der α-Styrylpyrylium-Salze 2, 4 und 6 zeigt irreversible Reduktions- und Oxidationsstufen, die sich nach Schema 1 interpretieren lassen. Die 1,3-Bis(pyrylium)cyclobutane 7, 8 und 9 werden nach einem ECE-Mechanismus reduktiv zu α-Styrylpyrylium-Salzen gespalten (Schema 2). Die Bis(pyraniliden)cyclobutane 22 gehen durch Zweielektronentransfer reversibel in die kurzlebigen Bicyclobutane K über, die zu den Butadienen M isomerisieren. Damit ähnelt das elektrochemische Verhalten der untersuchten Pyryliumderivate weitgehend dem der entsprechenden Pyridinderivate.
    Additional Material: 4 Ill.
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  • 80
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Multistep Reversible Redox Systems, XLIV. - Synthesis, Spectroscopic and Electrochemical Properties of 1-Substituted 4-(Dimethylamino)pyridinium SaltsVia reversible one-electron reduction of the models 3a - e it is demonstrated that the unique behaviour of R = CN in system 1e is due to the form 1eOX. The effect is interpreted as π-donation of the cyano group to the electron deficient bipyridinium system.
    Notes: Mit Hilfe der reversiblen Einelektronenreduktion der Modelle 3a - e wird nachgewiesen, daß die Sonderrolle von R = CN im System 1e der Form 1eOX zukommt. Zur Interpretation wird die π-Donorfunktion der Cyangruppe gegenüber dem elektronenarmen Bipyridinium-System herangezogen.
    Additional Material: 1 Ill.
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  • 81
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 775-784 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: α-Glucosidase Inhibitors, 3. - 4-Alkylamino-4,6-dideoxy Sugars via Reductive AminationAlkylamino sugars structurally derived from acarbose were obtained by reductive amination of aldehydes or ketones, respectively, and amino sugars mainly with sodium cyanotrihydroborate as reducing agent. Amino sugars investigated were the 4-amino-4,6-dideoxy-D-glucose derivative 5, the O-protected and O-unprotected 4′-amino-4′6′-dideoxymaltoside derivatives 9 and 11, and the O-protected 4′-amino-4′,6′-dideoxy-α-D-galactopyranosyl-(1→4)-α-D-glucopyranoside 16.
    Notes: Für die Synthese von (Alkylamino)zuckern, welche sich von der Struktur der Acarbose herleiten, wurden reduktive Aminierungen zwischen Aldehyden oder Ketonen und Aminozuckern vor allem mit Natrium-cyanotrihydroborat als Reduktionsmittel durchgeführt. Als Aminozucker wurden das 4-Amino-4,6-didesoxy-D-glucose-Derivat 5, die O-geschützten bzw. O-ungeschützten 4′-Amino-4′,6′-didesoxymaltosid-Derivate 9 und 11 und das O-geschützte 4′-Amino-4′,6′-didesoxy-α-D-galactopyranosyl-(1→4)-α-D-glucopyranosid 16 eingesetzt.
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  • 82
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 802-812 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Structure of 2,3-Disubstituted 1,2-Thiazetidine 1,1-Dioxides2-Alkylamino-2-phenylethanesulfonic acids 3 are prepared from sodium 2-phenylethenesulfonate (2). Compounds 3 are chlorinated and cyclized to yield the title compounds 5. Their structures are characterized by IR and NMR spectroscopy and compared to those of analogous β-lactams. An X-ray analysis of the β-sultam 5d establishes the proposed structure.
    Notes: Aus Natrium-(2-phenylethensulfonat) (2) werden die 2-Alkylamino-2-phenylethansulfonsäuren 3 hergestellt, aus denen nach Chlorierung durch Ringschluß die Titelverbindungen 5 erhalten werden. Ihre Strukturen werden durch IR- und NMR-Spektren charakterisiert und mit denen analoger β-Lactame verglichen. Eine Röntgenstrukturanalyse von 5d bestätigt die vorgeschlagene Struktur.
    Additional Material: 1 Ill.
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  • 83
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Enhydrazines, 38. Discrimination between 1,5,6,7-Tetrahydro-4H- and 2,5,6,7-Tetrahydro-4H-indazol-4-ones in the 13C NMR SpectrumFrom the title compounds the isomeric pairs 1a, b, 4a, b, and 5a, b were prepared. The spectroscopic properties of the regioisomers were investigated. Only the 13C NMR signals of the C atoms 3 and 7 a are significantly different within a pair and can be used for a reliable assignment. The structure of 1b was assigned by an X-ray analysis.
    Notes: Von den Titelverbindungen wurden die Isomerenpaare 1a, b, 4a, b und 5a, b dargestellt. Von den spektroskopischen Eigenschaften der Regioisomeren sind nur die 13C-NMR-Signale der C-Atome 3 und 7 a innerhalb eines Paares signifikant verschieden und für eine sichere Zuordnung geeignet. 1b wurde durch eine Röntgenstrukturanalyse gesichert.
    Additional Material: 1 Ill.
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  • 84
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Antibiotics from Gliding Bacteria, XXIV. - Corallopyronin A, B, and C - Three Novel Antibiotics from Corallococcus coralloides, Cc c127 (Myxobacterales)Three new antibiotics, corallopyronin A (1), B (2), and C (4) have been isolated from the culture broth of Corallococcus coralloides, strain Cc c127 (DSM 2550), by phase distribution and chromatography. The corallopyronins are closely related to myxopyronin A (5) and B (6), two homologous 3-acyl-4-hydroxy-α-pyrons with an α,β-unsaturated methyl carbamate function. Structurally the new antibiotics differ from the myxopyronins in an elongated 3-acyl side chain with two additional double bonds and one hydroxy function in corallopyronin A (1) and B (2) or an 3-acyl residue with a tetrahydrofuran ring in the component C (4).
    Notes: Aus dem Kulturmedium von Corallococcus coralloides, Stamm Cc c127 (DSM 2550), wurden drei neue Antibiotika, die Corallopyronine A (1), B (2) und C (4) durch Phasenverteilung und Chromatographie isoliert. Die Corallopyronine sind mit den Myxopyroninen A (5) und B (6), zwei homologen 3-Acyl-4-hydroxy-α-pyronen mit α,β-ungesättigter Methylcarbamatfunktion, nahe verwandt. Die neuen Antibiotika unterscheiden sich strukturell von den Myxopyroninen durch einen verlängerten 3-Acylrest mit zwei zusätzlichen Doppelbindungen und einer Hydroxyfunktion in Corallopyronin A (1) und B (2) oder durch einen 3-Acylrest mit einem Tetrahydrofuranring in der Komponente C (4).
    Additional Material: 3 Ill.
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  • 85
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 853-856 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cycloaddition Reactions of Azabenzenes, XVI. - Reactions of Pyridazinecarboxylates with Norbornene, Norbornadiene, and DicyclopentadieneReaction of trimethyl 3,4,6-pyridazinetricarboxylate (1a) and tetramethyl 3,4,5,6-pyridazine-tetracarboxylate (1b) with norbornadiene (2) yields trimethyl 1,2,4-benzenetricarboxylate (8a) and tetramethyl 1,2,3,4-benzenetetracarboxylate (8b), respectively. 1b and norbornene (3) or dicyclopentadiene (4) afford the polycyclic compounds 12 and 13.
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  • 86
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985) 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 87
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 866-868 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Note on the Preparation of scyllo-InositolA simplified synthesis of scyllo-inositol (4) from myo-inositol (1) via the pentaacetate of myo-inosose (3) is described.
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  • 88
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 901-912 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Novel [4 + 2] Cycloaddition Reactions of Coumarin Derivatives1)The synthesis and physical properties of the coumarin derivatives 5a - d, 7a - d, and 11 from the azomethines 1a - d and 6a - d are described. By thermal reaction of 5b - d or 7b with 2,3-dimethyl-1,3-butadiene the new cycloadducts 12a - c or 13 are formed, whereas 5c, d or 7b combine with 1,2-bis(methylene)cyclohexane to produce the polycyclic systems 15a, b or 14, respectively.
    Notes: Die Synthese sowie die physikalischen Eigenschaften der Cumarin-Abkömmlinge 5a - d, 7a - d und 11 aus den Azomethinen 1a - d und 6a - d werden beschrieben. Durch thermische Umsetzung von 5b - d oder 7b mit 2,3-Dimethyl-1,3-butadien werden die neuen Cycloaddukte 12a - c bzw. 13 gebildet, während 5c, d oder 7b mit 1,2-Bis(methylen)cyclohexan die Polycyclen 15a, b bzw. 14 ergeben.
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  • 89
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 913-920 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Conformational Analysis of Homotropanes. - Synthesis and Determination of the Configuration of Isomeric HomotropanolsThe conformation of homotropinone (1) and homotropane (2) was established by NMR and dipole moment measurements. The isomeric alcohols 8 and 9 formed from 1 by reduction were prepared in pure form, the C-3 configuration of which was determined with the aid of NMR and preparative methods.
    Notes: Die Konformation von Homotropinon (1) und Homotropan (2) wurde durch NMR- und Dipolmomentmessungen bestimmt. Die bei der Reduktion von 1 entstehenden Alkohole 8 und 9 wurden rein dargestellt, die relative Konfiguration von C-3 konnte mit Hilfe von NMR- und präparativen Methoden ermittelt werden.
    Additional Material: 1 Tab.
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  • 90
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Phosphorpentoxid in der Organischen Synthese, XVI1). - Eine Eintopf-Synthese von 2-Methyl-N6-aryladeninen aus 5-Acetylamino-1H-imidazol-4-carboxamid-hydrochlorid2-Methyl-6-(arylamino)purine 3 lassen sich aus 5-Amino-1H-imidazol-4-carboxamid-hydrochlorid über 5-Acetylamino-1H-imidazol-4-carboxamid-hydrochlorid (1) durch Erhitzen (180°C) mit Phosphorpentoxid, Triethylamin-hydrochlorid und einem geeignet substituierten Anilin herstellen.
    Notes: 5-Amino-1H-imidazole-4-carboxamide hydrochloride has been converted into a series of 2-methyl-6-(arylamino)purines 3 via 5-acetylamino-1H-imidazole-4-carboxamide hydrochloride (1) which was heated with phosphorus pentoxide, triethylamine hydrochloride, and an appropriate substituted aniline at 180°C.
    Additional Material: 5 Tab.
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  • 91
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 1501-1507 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A General Synthetic Method for Dibenzo[b,j][x,z]phenanthrolines with x,z = 1,7; 4,7, and 1,10When 2-aminoacetophenone (1) and 2-aminobenzophenone (4) are reacted with 1,3-, 1,2-, or 1,4-diiodobenzene, dibenzophenanthrolines 2, 6, 8, and 10 with fusion patterns [b,j][1,7]; [b,j][1,10], and [b,j][4,7], respectively, are obtained either directly or after acid-catalyzed cyclization of the primarily isolated intermediates 3, 4, 7, and 9.
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  • 92
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985) 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 93
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 1513-1536 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of Glycosides of Mono-, Sesqui-, and Diterpene AlcoholsThe β-D-glucopyranosides of the monoterpene alcohols (S)-(-)-β-citronellol (1), (S)-cis-verbenol (5), (3R)-(-)-linalool (8), dihydromyrcenol (11), terpinen-4-ol (14), of the norcarotinoides β-ionol (17), α-ionol (22), and of the sesquiterpene alcohol (+)-cedrol (27) as well as of the diterpene alcohols sclareol (33) and cis-abienol (40) have been synthesized. An α-D-glucopyranoside was obtainable from cembradiol (43). For all glycoside syntheses pyranosyl bromides have been applied as glycosyl donors. Most of the glycosylation reactions have been accomplished with silver silicate as catalyst.
    Notes: Es wurden die β-D-Glucopyranoside der Monoterpenalkohole (S)-(-)-β-Citronellol (1), (S)-cis-Verbenol (5), (3R)-(-)-Linalool (8), Dihydromyrcenol (11), Terpinen-4-ol (14), der Norcarotinoide β-Ionol (17), α-Ionol (22) und des Sesquiterpenalkohols (+)-Cedrol (27) sowie der Diterpenalkohole Sclareol (33) und cis-Abienol (40) synthetisiert. Ein α-D-Glucopyranosid war vom Cembradiol (43) erhältlich. Bei allen Glycosidsynthesen wurden Pyranosyl-bromide als Glycosyldonatoren eingesetzt. Als Katalysator wurde in der Mehrzahl der Glycosylierungsreaktionen reaktives Silbersilicat verwendet.
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  • 94
    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.
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  • 95
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chiral Building Units from Carbohydrates, XI.- 2-Lithio-1,3-dithiane-induced Reactions of 5,6-Dideoxy-5-iodohexofuranoses Leading to Open-chained Heptose Trimethylene DithioacetalsThe reaction of 5,6-dideoxy-5-iodohexofuranoses 5b, 7c, 8, 8a, and 20 with a large excess of 2-lithio-1,3-dithiane (1) yields the open-chained heptose trimethylene dithioacetals 21, 23, 24, 25, and 26. L-Configurated 5-iodides give Z-olefines, D-configurated E-olefines. The configuration of the hydroxy group at the newly created chiral center at C-2 is L in all examples which was proved by NMR spectroscopic and chiroptical methods. A reaction mechanism is discussed.
    Notes: Umsetzung der 5,6-Didesoxy-5-iod-hexofuranosen 5b, 7c, 8, 8a und 20 mit einem großen Überschuß von 2-Lithio-1,3-dithian (1) ergibt die offenkettigen Heptosetrimethylendithioacetale 21, 23, 24, 25 und 26. Dabei werden aus L-konfigurierten 5-Iodiden Z-, aus D-konfigurierten E-Olefine erhalten. In allen Fällen sind die Hydroxygruppen am neu geschaffenen chiralen Zentrum an C-2 L-konfiguriert, was durch NMR-spektroskopische und chiroptische Methoden nachgewiesen wurde. Es wird ein Reaktionsmechanismus diskutiert.
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  • 96
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Improved Preparation of Meerwein's Ester and Structure of Neutral By-products: Pentamethyl 1,1,3,3,5-Cyclohexanepentacarboxylate and Methyl 1-PiperidinecarboxylateIn a simplified procedure on a 10 mole scale, Meerwein's ester (2) is obtained from dimethyl malonate and formaldehyde in 48- 52% yield if the reaction time is extended and the disodium salt of 2 is isolated. Methyl 1-piperidinecarboxylate (7) and pentamethyl 1,1,3,3,5-cyclohexanepentacarboxylate (8) are formed as neutral by-products. The structure of the latter is confirmed by spectroscopic methods. The mechanism of formation of 8 is discussed.
    Notes: Auf vereinfachte Weise erhält man Meerwein-Ester (2) aus Malonsäure-dimethylester und Formaldehyd im 10-mol-Maßstab mit 48- 52% Ausbeute, wenn die Reaktionsdauer verlängert und das Dinatriumsalz von 2 isoliert wird. Als neutrale Nebenprodukte entstehen 1-Piperidincarbonsäure-methylester (7) und 1,1,3,3,5-Cyclohexanpentacarbonsäure-pentamethylester (8), dessen Struktur durch spektroskopische Methoden gesichert wird. Der Bildungsmechanismus von 8 wird diskutiert.
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  • 97
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Antibiotics from Gliding Bacteria, XXVI.- The Constitution and Absolute Configuration of the Epimeric Myxovirescins A1 and A2Extensive 1H and 13C NMR spectroscopy, including 2D spectra, on myxovirescin A1, A2 (1a, b) and the derivatives 2- 8 together with the results of degradation experiments, proved that myxovirescin A1 and A2 are 28-membered macrocyclic lactam-lactones. This constitution has been confirmed by an X-ray analysis of the bisacetal (8) of myxovirescin A1. The knowledge of the absolute configuration of the degradation product (2S)-(-)-sodium 2-hydroxyvalerate (9) of 1a, b reveals the absolute configuration of the seven asymmetric centers in myxovirescin A1: 2S, 6S, 8S, 9R, 16R, 25R, 27S. From the isolation of (2S, 4S)-(+)-dimethyl 2,4-dimethyl-1,9-nonanedicarboxylate (10) after oxidative degradation of myxovirescin A2 follows the (25S)-configuration of the epimeric center in myxovirescin A2.
    Notes: Ausführliche 1D- und 2D-1H-sowie 13C-NMR-Untersuchungen an den Myxovirescinen A1 und A2 (1a, b) und den Derivaten 2- 8 führten zusammen mit Ergebnissen von Abbaureaktionen zu der angegebenen Konstitution eines 28gliedrigen Lactam-Lacton-Systems. Die Konstitutionsermittlung konnte mittels einer Röntgenstrukturanalyse des Bisacetals von Myxovirescin A1 (8) abgesichert werden. Weiterhin ermöglichte die Röntgenstrukturanalyse mit Kenntnis der absoluten Konfiguration des Abbauproduktes (2S)-(-)-Natrium-2-hydro-xyvalerat (9) von 1a, b die Zuordnung der absoluten Konfigurationen der sieben Asymmetriezentren im Myxovirescin A1 als 2S, 6S, 8S, 9R, 16R, 25R und 27S. Die Isolierung des rechtsdrehenden Dimethylesters der (2S, 4S)-2,4-Dimethyl-1,9-nonandisäure (10), erhalten aus Myxovirescin A2 durch oxidativen Abbau, legt für das Epimere A2 die (25S)-Konfiguration fest.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 98
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Photochemie des Phthalimid-Systems, 371). - Thiazacycloalkanole durch Photocyclisierung von S-substituierten N-(Thioalkyl)phthalimidenDurch Bestrahlung N-substituierter Phthalimide (1, 2), die in der Seitenkette eine terminale Thioetherfunktion haben, mit einer Hochdruck-Quecksilberlampe werden unter bevorzugter γ-, δ-, ∊- und ζ-Wasserstoffabtraktion (Tab. 1) eine Anzahl von Thiazacycloalkanol-Derivaten (3, 7, 9-13, 16, 17) mit mäßigen bis nahezu guten Ausbeuten erhalten.
    Notes: N-Substituted phthalimides (1, 2) possessing a terminal thioether function in their side chain were irradiated with a high-pressure mercury lamp to give a variety of thiazacycloalkanol derivatives (3, 7, 9-13, 16, 17) with favored γ-, δ-, ∊-, and ζ-hydrogen abstractions (Table 1), in moderate to fairly good yields.
    Additional Material: 13 Tab.
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  • 99
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Heterocycles from α-Nitroolefins, IX1). - N-Substituted 3-Pyrrolecarboxylates from 4,5-Dihydro-5-(methyleneamino)-3-furancarboxylatesCatalytic hydrogenation of 4,5-dihydro-5-(methyleneamino)-3-furancarboxylates 1 yields N-substituted pyrroles 6a-u with enolizable rests at nitrogen and 6v  -  y with non-enolizable rests at nitrogen. The N-substituted pyrroles 6, 7 react with sodium hypochlorite at the rests standing at nitrogen to yield chlorination products 8. O-Methylated products 9 have been prepared from several N-substituted pyrroles 6 and their enoles 7 with diazomethane; the N-substituted pyrrole 6x yields the C-methylated product 10x.
    Notes: Katalytische Hydrierung überführt 4,5-Dihydro-5-(methylenamino)-3-furancarbonsäureester 1 in N-substituierte Pyrrole 6a-u mit enolisierbaren und 6v-y mit nichtenolisierbaren Resten am Stickstoff. Die N-substituierten Pyrrole 6, 7 reagieren mit Natriumhypochlorit an den am Stickstoff stehenden Resten zu Chlorierungsprodukten 8. Aus mehreren N-substituierten Pyrrolen 6 bzw. den zugehörigen Enolen 7 werden mit Diazomethan die O-Methylierungsprodukte 9 dargestellt; das N-substituierte Pyrrol 6x liefert das C-Methylierungsprodukt 10x.
    Additional Material: 6 Tab.
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  • 100
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1985 (1985), S. 1145-1167 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Peptide Conformations, 361). - Conformational Investigations of Four Cyclic Heptapeptides by NMR SpectroscopyThe synthesis and conformational analysis of the four cyclic heptapeptides cyclo[Ala-Ile-Val-Ser(Bzl)-Xxx-Phe-Gly-] (1: Xxx = Pro, 2: Xxx = Aib), cyclo[-Gly-Phe-Leu-Ala-Lys(Z)-Tyr(Bzl)-Gly-] (3), and cyclo[-D-Trp-Lys(Z)-Thr-Val-Pro-Gly-Phe-] (4) by 1H, 13C and partially 15N NMR spectroscopy is described. 3 contains the sequence of Leu-enkephaline, whereas 4 contains the active sequence of somatostatin (Phe6-Thr10). The deprotected compounds 3 and 4 exhibit no biological activity. Spectral assignments were performed via homo- and heteronuclear correlated 2D NMR techniques. 2 and 3 exhibit only trans peptide bonds while the Ser - Pro bond in 1 is cis configurated. From the temperature dependence of the NH signals, the coupling constants, and the NOE effects a structure is derived which gives for 1 and 2 a conformation similar to a β-pleated sheet around Gly-Ala-Ile-Val. The glycine carbonyl group is an acceptor for two NH-hydrogen bonds (Ile, Val). The peptides 1 and 2 differ in their conformations in the region Ser-Xxx-Phe, substitution of Pro (in 1) by Aib (in 2) leads to elimination of a βVI turn Val-C=O ← H - N-Phe in 1. Unusually clearcutted differentiation of amide NH temperature gradients have been observed in cyclus, this can be interpreted in terms of a relatively rigid ring framework. A structure similar to a β pleated sheet and a γ turn Ala C=O → H-N- Tye around lysine has been proven for 3. Cyclus 4 is inhomogeneous following the usual interpretations of NMR data.
    Notes: Die Synthese und Konformationsanalyse der vier cyclischen Heptapeptide cyclo[-Ala-Ile-Val-Ser-(Bzl)-Xxx-Phe-Gly-] (1: Xxx=Pro, 2: Xxx = Aib), cyclo[-Gly-Phe-Leu-Ala-Lys(Z)-Tyr(Bzl)-Gly-] (3) und cyclo[-D-Trp-Lys(Z)-Thr-Val-Pro-Gly-Phe-] (4) durch 1H-, 13C- und zum Teil 15N-NMR-Untersuchungen werden beschrieben. 3 enthält die Sequenz des Leu-Enkephalins, während 4 die aktive Sequenz des Somatostatins (Phe6-Thr10) enthält. Die nach Abspaltung der Schutzgruppen von 3 und 4 getesteten Verbindungen wiesen keine biologische Aktivität auf. Die Zuordnung der Spektren erfolgte durch homo- und heteronuklear korrelierte 2D-NMR-Techniken. 2 und 3 weisen nur trans-Peptidbindungen auf, die Ser - Pro-Bindung in 1 ist cis-konfiguriert. Aus den Temperaturabhängigkeiten der NH-Signale, den Kopplungskonstanten und den NOE-Effekten wird für 1 und 2 eine im Bereich von Gly-Ala-Ile-Val β-Faltblatt-ähnliche Struktur abgeleitet. Die Glycin-Carbonylgruppe fungiert dabei als Akzeptor für Wasserstoffbrücken von zwei NH-Gruppen (Ile, Val). Im Bereich Ser-Xxx-Phe unterscheiden sich beide Konformationen erheblich, der Einbau von Aib (in 2) anstelle von Pro (in 1) führt zum Wegfall der in 1 auftretenden βVI-Schleife Val-C = O ← H - N-Phe. Cyclus 3 besitzt eine ungewöhnlich scharfe Differenzierung der Amid-NH-Temperaturgradienten, welche auf ein hohes Maß an Rigidität des Gerüsts deutet. Nachgewiesen werden konnten eine β-Faltblatt-ähnliche Struktur sowie eine γi-Schleife Ala-C = O ← H - N-Tyr. Das Cyclopeptid 4 ist konformationell nicht einheitlich.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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