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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 1673-1679 
    ISSN: 0947-3440
    Keywords: Selective glycosidation ; Trimethylsilyl bromide ; TMS triflate ; Long-chain alcohols ; Phase-transfer catalysis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stereoselective synthesis of glycosides (glucosides, galactosides, mannosides, and xylosides) is reported using long-chain alcohols with 0-4 ethoxy spacers as potential anchored cryoprotectors.
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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 structure of the bisindole alkaloid amataine (= grandifoline, subsessiline)Amataine (1) was isolated from the roots of Hedranthera barteri (HOOK. F.) PICHON (Apocynaceae). In comparison to the alkaloid vobtusine (5), which was isolated from the same plant, 1 contains two hydrogen atoms less. By reduction of 1 with H2/PtO2 or with NaBH4 dihydromataine ( = isovobtusine, 13) was formed which is isomeric to 5. Acid catalysed water addition to 1 afforded hydratoamataine (15), which was reduced to 5 with NaBH4. Thermolysis of 15 gave 1. The difference between the two isomeric bases 5 and 13 has to be attributed to a different configuration at the spirocenter C(7). In contrast to 5 amataine (1) contains an ether bridge instead of a hydroxy group; this bridge is located between C (2′) and C (8).
    Additional Material: 1 Ill.
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  • 3
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Structure of bis-indoline alkaloids of a novel typeThe structure of folicangine 4, a bis-indoline alkaloid from the leaves of Voacanga africana, is obtained by correlation with voafolidine 3a and isovoafolidine 3b. It requires an ether bridge between the two parts of the molecule, as in subsessiline (amataine 5a). Subsessiline-lactone, from the leaves of Voacanga thouarsii has structure 5b proved by correlation with 5a. The CD. curves of double-indole alkaloids of vobtusine type are given (Table 3).
    Additional Material: 2 Tab.
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  • 4
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alstonia scholaris: The structure of the indole alkaloid narelineBesides the known akuammidine, picralinal, picrinine and pseudoakuammigine a new indole alkaloid called nareline (M=352) was isolated from Alstonia scholaris R. BR., which belongs to the plant family of Apocynaceae. Its structure 2 was deduced by single crystal X-ray diffraction. 2 represents the absolute configuration. The spectroscopic data of 2 and its derivatives (Scheme 1) as well as their chemical behavior support this structure. In biogenetic sense nareline is related to the bases akuammiline (4) and picraline (5) (Scheme 2). In contrast to those the C-atom 5 is exocyclic and represents an aldehyde group which forms together with the oxygen atom of the N (4)-hydroxylamine group a cyclic half acetale. - By oxidation (CrO3/CH3COOH) of 2 the oxindol derivative 19 (oxonareline) is formed which contains a cyclic acetal as a partial structure element (Scheme 4).
    Additional Material: 1 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 58 (1975), S. 1881-1886 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stability constants of the Ni2+ and Co2+ complexes with 1,5-diazacyclooctane-N,N′-diacetic acid (H2DACODA) have been determined potentiometrically in 0.5M KNO3 at 25°. Only M(DACODA) and M(DACODA)OH- were observed.In addition the formation and dissociation kinetics of the pentacoordinate complexes M(DACODA) has been studied in aqueous solution using a stopped-flow technique. Formation follows the rate law vf = kf [M2+] [HDACODA-]/[H+], which can be interpreted as a bimolecular process either between M2+ and DACODA2- (kM,LML) or between MOH+ and HDACODA- (kMOH,HLML). The second order rate constants kM,LML are much higher than those expected from water exchange and can only be explained by a strong internal conjugate base effect. In the limiting case, however, this is equivalent to the second possible explanation, which assumes MOH+ and HDACODA- as reactive species. The dissociation rate is given by vd = (kML + kHML [H+]) · [M(DACODA)].
    Additional Material: 3 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 33 (1950), S. 802-812 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Durch Einwirkung von Lithiumaluminiumhydrid auf Corynanthein (I oder II) gelang es, zwei Reduktionsprodukte zu gewinnen: Desmethyl-corynanthein-alkohol(III) und Desmethoxy-corynantheinalkohol (VIIa oder VIIb), die durch Verseifung der Äthergruppe des Corynantheins und Reduktion der Estergruppe entstanden sind. Die Weiterreduktion des Desmethoxy-corynanthein-alkohols ergab den Dihydro-desoxy-corynanthein-alkohol (VIII). Durch vorsichtige Verseifung des Corynantheins mit einer Lösung von Chlorwasserstoff in Aceton und Äther wurde das Desmethyl-corynanthein (IV) erhalten, welches sich durch die braunrote Eisenchlorid-Reaktion und leichte Decarboxylierbarkeit zum Descarboxy-corynanthon (VI) als β-Ketosäure zu erkennen gibt. Descarboxy-corynanthon ist mit Yohimbon nicht identisch. Ob der Unterschied auf sterische Verschiedenheit von Corynanthein und Yohimbin zurückzuführen ist, oder ob Carboxyl- und Methylgruppe im Ring E des Corynantheins eine andere Lage als die Carboxyl- und OH-Gruppe im Yohimbin besitzen, muss weiter abgeklärt werden.
    Additional Material: 1 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 35 (1952), S. 316-329 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Durch Kondensation von aromatischen Ketonen mit Thiodiphenylamin und Phenoxazin wird eine Reihe neuer Farbsalze der Triphenylmethanreihe aufgebaut, ausserdem einige Pyryliumsalze in analoger Weise aus Cumarin und Flavon. Die Vergleichsfarbstoffe aus Diphenylamin werden ebenfalls synthetisiert. Es ergibt sich, dass Thiodiphenylamin und Phenoxazin einen ungewöhnlich starken bathochromen Effekt ausüben (in der Mehrzahl der Fälle starke Ultrarotabsorption). Eine scheinbare Ausnahme bei den Farbstoffen aus Michler's Keton, deren Hauptmaxima bei relativ kurzen Wellen liegen, erklärt sich aus der Überlagerung der langwelligen Bande durch eine kürzerwellige Bande.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1992 (1992), S. 387-393 
    ISSN: 0170-2041
    Keywords: Push-pull alkenes ; Thiophenes ; Thieno[2,3-b]thiophenes ; Thiazolidin-4-ones ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Treatment of β-keto enolates 1 with carbon disulfide in the presence of sodium hydride and subsequent alkylation yield the open-chain or cyclic acylformylketene S,S-acetals 3 and 4, respectively. Thiophenes 5, 6, or 7 and thieno[2,3-b]thiophenes 8 are formed by using as alkylating agents first methyl iodide and then an α-CH-acidic halo compound or only two equivalents of the latter. β-Keto enolates 1 also react with phenyl isothiocyanate to give acylformylketene S,N-acetals 10, aroylthiophenes 11 or thiazolidin-4-ones 12.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1993 (1993), S. 437-439 
    ISSN: 0170-2041
    Keywords: Centperazine ; Antifilarial drug ; 6H-Pyrazino[1,2-c]pyrimidines ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 7-Ethyl-octahydro-2-methyl-6H-pyrazino[1,2-c]pyrimidin-6-one (centperazine) (1), an antifilarial candidate drug, currently undergoing phase II clinical trials, has been synthesized by a more economically viable alternative route. Condensation of N,N′-dibenzylethylenediamine (2) with 3,4-dibromobutyronitrile (3) gives 2-(1,4-dibenzyl-2-piperazinyl)acetonitrile (4), which, on catalytic reduction, debenzylation, cyclocarbamation and N-alkylation yields the target molecule 1 in 10.1% overall yield.
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