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  • 1980-1984  (3,407)
  • 1925-1929  (1,634)
  • Organic Chemistry  (5,040)
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 616-624 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Structural modifications of multifidene (1), viridiene (2) and ectocarpene (5) led to the synthesis of eleven new pheromone components or imitatin substances mostly by Grignard alkylation of cyclopentene and cycloheptadiene synthons. A new lactone α,ω dienol conversion is reported.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 640-653 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The He(Ia) photoelectron (PE) spectra of the (E,E)-, (E,Z)- and (Z,Z)-isomers of the title compound have been recorded to obtain information about their conformation in the gas phase. For a valid correlation with the PE data of other dienes it is necessary to take the potentials V(ϕ) for internal rotation and the corresponding conformer population densities P (ϕ) into account, as well as the rather complicated way wy in which the π-1 ionization energy gap ΔI(ϕ) depends on the direct π-orbital interaction and the long-range ‘through-space’ interaction between the semi-localized methyl-group orbitals and the π-orbitals. These factors being taken into account, the mean twist angles, ϕ, compatible with the PE-spectroscopic results are ϕ (E,E) ≍ O° ± 30°, ϕ (E,Z) ≍ 80° or 110° within ± 15°, and ϕ (Z,Z) ≍ 85° to 105°. These results are in rough agreement with electron diffraction data by Traetteberg [15], other spectroscopic results and, for the (E, E)- and (Z,Z)-isomers, internal rotation potentials V(ϕ) previously calculated by Roth [17]. On the other hand the potential V (ϕ) proposed for the (E,Z)-isomer does not seem to be compatible with our findings.
    Additional Material: 7 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 olefins 2, 7, 11, and 19, have been reduced using catalytic amounts of cob(I)alamin(I(I)). During a slow saturation, the catalyst is able to differentiate the two diastereotopic faces of the endocyclic double bonds in 11 (t1/2 4 h,. cf. Scheme 3) are reduced much faster. A rationalization of the data can be obtained formulating tertiary alkylcobalamins as intermediates. Of the oxime 6 (cf. Scheme 2) and the p- bromobenzoate 23 (cf. Scheme 5) the structures have been determined by X-ray analysis.
    Additional Material: 2 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: Structural Elucidation of Niphimycin, Part 3. Identity of Scopafungin and Niphimycin I. Position of the Malonyl Residue of Niphimycin and CopiamycinThe identity of scopafungin with niphimycin I was proven by spectroscopic and chromatographic methods and by common degradation products. The position of the malonyl residue in niphimycin I (9) and in copiamycin (14) was deduced by 1H-NMR spin-decoupling experiments of a degradation product (10).
    Additional Material: 2 Tab.
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  • 5
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses, Chemical and Electrical Properties of Tetrathiafulvalene with a 1,6-Methano[10]annulene Moiety and of Chalcogendiimide-DerivativesThe synthesis of the tetrathiafulvalene 6 has been described: the reaction of 1 with the benzenedithoil 2 yielded the bis-dithioacetal 3 of 1,6-methano[10]annulene-dicarbaldehyde 1. The oxidation of 3 in the presence of HBF4 in Et2O yielded the salt 4, elimination of a hydride anion with triphenylmethylium tetrafluoroborate the salt 5, and elimination of a proton in 5 with Et3N the tetrathiafulvalene 6 with a 1,6-methano[10]annulene moiety. The spectroscopic and electrochemical properties of 6 are described, and also the syntheses and properties of charge-trasnfer complexes 7 and 8, including the properties of electric conductivity of 7 and 8. the syntheses of 9-13 are reported and also their spectroscopic properties.
    Additional Material: 1 Tab.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 765-769 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Voltammetric Investigations on the Oxidation Step of Symmetrical Triazacarbocyanine Dyes in Acetonitrile SolutionThe oxidation behaviour of twelve symmetrical triazacarbocyanine dyes with different heterocycles in MeCN (containing tetrabutylammonium perchlorate) has been investigated by means of dc-, ac- and cyclic triangular wave voltammetry. The oxidation mechanism has been found to be of the type ec, with the electrochemical step being reversible to irreversible. Oxidation potentials and transfer coefficients have been measured (E1/2 1.60 to 2.12 V vs. Ag/AgCl) and compared with known properties of carbocyanines. The effect of substituents X has been studied on the compounds 1,3-diethyl-2-[3-(1,3-diethyl-5-X-benzimidazolin-2-ylidene)-1-triazeno]-5-X-benzimidazolium tetrafluoroborate ((1a(X)) and 3-ethyl-2-[3-ethyl-5-X-Δ4-1,3-thiazolin-2-ylidene)-1-triazeno]-5-X-1,3-thiazolium tetrafluoroborate (1g(X)), and ρ-values of 0.425 and 0.565 V, respectively, have been found.
    Additional Material: 5 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 947-952 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantioselective synthesis of (+)- and (-)-cis-2-methyl-4-propyl-1,3-oxathine 8 and 9 form (E)-2-hezen-1-ol (1) as common starting material is described. The two enantiomeric forms exhibit different organoleptic properties.
    Additional Material: 2 Tab.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1003-1011 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Plectranthons A, B, C, and D. Diterpenoid Phenanthrene-1,4-diones from Leaf-glands a Plectranthus sp. (Labiatae)The following structures of four new 1,4-phenanthraquionones, isolated in minute amounts from the coloured leaf-glands of a Plectranthus sp. obtained from the borders of Lake Kiwu2, Rwanda, are proposed: plectranthon A (1; 3-hydroxy-5, 7,8-trimethyl-2-(2-propenyl)phenanthrene-1, 4-dione), plectranthon B (2; 2-(2ξ-acetoxypropyl)-3-hydroxy-5,7,8-trimethylphenanthrene-1,4-dione), plextranthon C (3; 3-hydroxy- 7,8-diemethyl-2-(2-propenyl)phenanthrene-1,4-dione), and plectranthon D (4; 3-hydroxy-7,8,10-trimethyl-2-(2-propenyl)phenanthrene-1,4-dione). 2-(2ξ-Hydroxypropyl)-3,6-dihydroxy-5,7,8-trimethylphenanthrene-1,4-dione (11), a compound very similar to 1-4, was prepared by a Wagner-Meerwein, rearrangement of coleon E (5). Biogenetically, the plectranthons are derived from abietanoic precursors. The compounds 1, 2 and 4 are the first natural C20-phenanthrenes of diterpenoid origin.
    Additional Material: 1 Ill.
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  • 9
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stellvertretende nucleophile Substitution von Wasserstoff in Nitropyridinen durch α-Chloralkylphenylsulfon-CarbanionenNitropyridine und Chlornitropyridine reagieren mit Carbanionen von α-Chloralkylphenylsulfonen unter „stellvertretender nucleophiler Substitution“ von Wasserstoff in o- und p-Stellung zur Nitrogruppe. Als allgemeine Regel wurde beobachtet, daß die „stellvertretende Substitution“ des Wasserstoffs rascher als die nucleophile Substitution von entsprechend aktiviertem Halogen erfolgt. Die Orientierung der Wasserstoff-Substitution wird diskutiert.
    Notes: Nitropyridines and chloronitropyridines react with carbanions of α-chloroalkyl phenyl sulfones yielding products of the vicarious nucleophilic substitution of hydrogen at positions ortho and para to the nitro group. A general rule that the vicarious substitution of hydrogen proceeds faster than the nucleophilic substitution of equally activated halogen is observed. The orientation of the hydrogen substitution is discussed.
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  • 10
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Carbonyl und Thiocarbonylverbindungen: Reaktionen von 4-Chlorxanthion mit Diazoalkanen und Ch-aciden verbindungenWährend 4-Chlorxanthion 1 mit Diazomethan das Dithiolan 2 ergibt, entstehen mit anderen Diazoalkanen die Episulfide 3-5, deren Entschwefelung zu den entsprechenden Ethylenen 6-7 führt. Malononitril und Cyanessigsäure-ethylester reagieren mit 1 zu den Cyanderivaten 8a, b. Mit Hydrazinen und p-Toluidin ergibt 4-Chlorxanthion (1) die Hydrazone 9a, b und die Schiff-Base 9c. In Abhängigkeit von den Reaktionsbedingungen liefert die Oxidation des Hydrazons 9a die Diazoverbindung 10 oder das Ketazin 11. Hydroxylamin reagiert mit 1 zum Oxim 9d, das mit Phenylisocynat zum N-Phenylcarbamat 9e reagiert.
    Notes: While 4-chloroxanthione 1 gives with diazomethane the dithiol 2, it reacts with other diazoalkanes to give the episulfides 3-5, desulfurization of which forms the ethylenes 6 and 7. Malononitrile and ethyl cyanoacetate react with 1 to give the cyano derivatives 8a, b. With hydrazines and p-toluidine, 4-chloroxanthione (1) give the hydrazones 9a, b and the Schiff's base 9c, respectively. The hydrazone 9a on oxidation may give either the corresponding diazo compound 10 or the ketazine 11 according to the reaction conditions. The title compound 1 reacts with hydroxylamine to yield the oxime 9d which forms the N-phenylcarbamate 9e when treated with phenyl isocyanate.
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  • 11
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 196-198 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaktionen von 4-Chlor-9H-xanthen-9-thion mit Tetrachlor-O-benzochinon4-Chlor-9H-xanthen-9-thion (1) reagiert mit Tetrachlor-o-benzochinon zu dem cyclischen Acetal 2. Zur Struktursicherung wurde 2 auf unabhängigen Wegen aus Tetrachlor-o-benzochinon und 4-Chlor-9-diazo-9H-xanthen oder 4-Chlor-9H-xanthen-9-on-hydrazon sowie aus Tetrachlorbrenzcatechin und 4,9,9-Trichlor-9H-xanthen synthetisiert. Die Spaltung der Acetalgruppe in 2 mit Salzsäure, Malononitril, Cyanessigsäure-ethylester und Hydrazinhydrat wurde studiert.
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  • 12
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Polyhydroxyamino Compounds via Diene Synthesis with Nitroso compounds, IX.  -  trans-6-Azido-1,3-cyclohexadien-5-ol as educt for the Synthesis of Kondurodiamine and Streptamine IsomersThe diaminodideoxykonduritols 8a, 8b, and 9 as well as the analogs 10 and 11 of Streptamine have been synthesized starting with O,N-5,6-disubstituted cyclohexadienes.
    Notes: Die Diaminodidesoxykondurite 8a, 8b und 9 sowie die Streptaminanalogen 10 und 11 werden ausgehend von O,N-5,6-disubstituierten Cyclohexadienen synthetisiert.
    Additional Material: 1 Ill.
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  • 13
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1-7 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Thiophosphatidic Acid Esters Containing a C—S—P BondThiophosphatidic acid and the following thiophosphatidic acid esters containing a C—S—P bond were synthesized: O,O-dimethyl S-(2,3-distearoyloxypropyl) thiophosphate (4). O-methyl S-(2,3-distearoyloxypropyl) thiophosphoric acid (4a), and O,O-bis(trimethylsilyl) S-(2,3-distearoyloxypropyl) thiophosphate (6). The structures were proved by NMR and IR spectra. It was demonstrated that O,O-dimethyl S-(2,3-isopropylidenedioxypropyl) thiophosphate (3) can be obtained from 2,3-isopropylidenedioxy-1-propanethiol (1) in good yield and acylated to yield 4.
    Notes: Thiophosphatidsäure und folgende Thiophosphatidsäureester mit C—S—P-Bindung wurden synthetisiert: Thiophosphorsäure-O,O-dimethyl-S-(2,3-distearoyloxypropyl)ester (4), Thiophosphorsäure-O-methyl-S-(2,3-distearoyloxypropyl)ester (4a) und Thiophosphorsäure-O,O-bis(trimethylsilyl)-S-(2,3-distearoyloxypropyl)ester (6). Die Strukturen wurden durch NMR- und IR-Spektren bestätigt. Es wurde gezeigt, daß Thiophosphorsäure-O,O-dimethyl-S-(2,3-isopropylidendioxypropyl)ester (3) mit guter Ausbeute aus 2,3-Isopropylidendioxy-1-propanthiol (1) erhalten und zu 4 acyliert werden kann.
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  • 14
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 15-30 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of 4-Penten-4-olides (γ-Methylene-γ-butyrolactones) vis 4-Pentenoic Acids4-Penten-4-olides (γ-Methylene-γ-butyrolactones) 7 are easily accessible starting from allylic alcohols 1, which on ortho ester Claisen rearrangement and hydrolytic work-up furnish 4-pentenoic acids 5. The latter on iodolactonization and hydrogen iodide elimination by means of 1,8-diaza-bicyclo[5.4.0]undec-7-ene (DBU) furnish 7, in good over-all yield and with variable substitution patterns.  -  Iodolactonization under kinetic control shows moderate 1,2- or 1,3-asymmetric induction (≳ 3:1 and ca. 2:1, respectively). The composition of the iodolactone mixtures 6 as well as the individual relative configurations are deduced from 1H and 13C NMR data.  -  Similarly, the spirobipentenolide 13 is obtained starting from diethyl diallylmalonate (9) via 11 resulting from ester iodocyclization.
    Notes: 4-Penten-4-olide (γ-Methylen-γ-butyrolactone) 7 sind aus Allylalkoholen 1 durch Orthoester-Claisenumlagerung und Hydrolyse zu 4-Pentensäuren 5, anschließende Iodlactonisierung und HI-Abspaltung mit 1,8-Diazabicyclo[5.4.0]undec-7-en (DBU) in guter Gesamtausbeute und variablem Substitutionsmuster leicht zugänglich.  -  Die Iodlactonisierung unter kinetischer Kontrolle zeigt mäßige 1,2- oder 1,3-asymmetrische Induktion (≳ 3:1 bzw. ca. 2:1). Die Zusammensetzungen der Iodlactongemische 6 sowie die relativen Konfigurationen werden aus 1H- und 13C-NMR-Daten abgeleitet.  -  Das Spirobipentenolid 13 wird in ähnlicher Weise aus Diallylmalonsäure-diethylester (9) über 11 (durch Ester-Iodlactonisierung) erhalten.
    Additional Material: 7 Tab.
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  • 15
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigations on the Chemistry of Natural Organic Materials, 89.  -  halogenation Reactions of 1,3-Dihydroxy-10methyl-9(10H)-acridinone and its Ethers  -  A Simple Regiospecific Synthesis of AcroyncineIodination of 1,3-dihydroxy-10-methyl-9-acridone (2c) and its ethers 2a and 2b gave the corresponding 2-iodo derivatives 3a-c. Bromination of 2a with NBS yielded 2-bromo-(10), 4-bromo- (11), as well as small amounts of 2,4-dibromo-1,3-dimethoxy-10-methyl-9-acridone (12). Under the same conditions from 2c 2-bromo-1,3-dihydroxy-10-methyl-9-acridone (13) has been obtained. Chlorination of 2a with SO2Cl2 in CHCl3 gave-4-chloro- (14) and 2,4-dichloro-1-hydroxy-3-methoxy-10-methyl-9-acridone (15). The reaction of 3b with copper(I) phenyl- and copper(I) isopropenylacetylide yielded the corresponding 2-substituted 4-methoxy-6-methylfuro[2,3-α]acridin-11(6H)-ones 6a and 6b, respectively. From the condensation reaction of 3c with 3-chloro-3-methyl-1-butyne noracronycine (8) has been obtained.
    Notes: Die I2/HIO4-Iodierung von 1,3-Dihydroxy-10-methyl-9-acridon (2c) und seiner Ether 2a und 2b ergab die entsprechenden 2-Iod-Derivate 3a-c. Bromierung von 2a mit NBS führte zu 2-Brom-(10), 4-Brom-(11) sowie geringen Mengen von 2,4-Dibrom-1,3-dimethoxy-10-methyl-9-acridon (12). Unter denselben Bedingungen lieferte 2c 2-Brom-1,3-dihydroxy-10-methyl-9-acridon (13). Chlorierung von 2a mit SO2Cl2 in CHCl3 ergab 4-Chlor-(14) und 2,4-Dichlor-1-hydroxy-3-methoxy-10-methyl-9-acridon (15). Umsetzen von 3b mit Kupfer(I)-phenyl- bzw. Kupfer(I)-isopropenylacetylid führte zu den 2-substituierten 4-Methoxy-6-methylfuro[2,3-α]acridin-11(6H)-onen 6a und 6b. Die Reaktion von 3c mit 3-Chlor-3-methyl-1-butin ergab Noracronycin (8).
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  • 16
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 66-77 
    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 Methyl Ether of “Herzgift-Methylreduktinsäure” Starting from D-GlucoseThe methyl ether 5 of „Herzgift-Methylreduktinsäure“ (2), a degradation product of the Calotropis cardenolides, has been synthesized starting from D-glucose as the chiral pool. The configuration of 2, previously based on the results of degradation, is confirmed by the synthesis of 5.
    Notes: Der Methylether 5 der „Herzgift-Methylreduktinsäure“ (2), eines Abbauproduktes der Calotropis-Cardenolide, wird in einer mehrstufigen Synthese aus D-Glucose als chiralem Ausgangsmaterial hergestellt. Damit wird die durch Abbaureaktionen getroffene Konfigurationszuordnung für 2 durch Synthese von 5 bestätigt.
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  • 17
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 85-97 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Aminoethynyl Metallations, 313.  -  Synthesis and Reactions of 3-AminopropiolamidinesThe lithium aminoacetylides 1 react with the carbodiimides 2 to give the lithium propiolamidinates 3, which are hydrolyzed to yield the 3-aminopropiolamidines 4. 3 can directly be converted into the persubstituted ynamine carboxamidines 5 by adding methyl iodide. The amidines 4 with less activated C/C-triple bonds (NR1R2 = N(Me)Ph or NPh2) react with thioformaldehyde dioxide or with diphenyl ketene exclusively at the NH group with formation of the sulfonamides 6 or of an carboxamide 7. The more reactive (diethylaminoacetylene)carboxamidine 4h adds a second molecule of ketene to furnish the cyclobutenone derivative 8. The propiolamidine 4b with a diphenylamino group at the triple bond reacts with concentrated hydrochloric acid under formation of the amidinium salt 9 and partly by addition of a second molecule of hydrochloride to the triple bond to give 10. Adding tosyl azide to 4 we obtained via the triazole 11 by two successive 1,5-cyclizations the 4-amidino-1,2,3-triazoles 12. The 3-aminopropiolamidines 4 bearing at least one aryl group in the amidine moiety cyclize to give the 2,4-diaminoquinolines 17 if they are chromatographed on silica gel. The same or analogously substituted quinolines 17 are obtained by the reaction of the simple ynamines 15(H, Me, or Ph in the β-position) with the corresponding carbodiimides 2 2-Anilino-4-diethylamino-3-methylquinoline (17e) is hydrolyzed in acidic solution to give the 4-quinolone derivative 19.
    Notes: Die Lithium(aminoacetylide) 1 reagieren mit den Carbodiimiden 2 zu den Lithiumpropiolamidinaten 3, deren Hydrolyse die 3-Aminopropiolamidine 4 liefert. Mit Methyliodid entstehen aus 3 die persubstituierten Inamincarboxamidine 5. Die Amidine 4 reagieren bei geringer Aktivierung der Dreifachbindung [NR1R2 = N(Me)Ph oder NPh2] mit Sulfen oder mit Diphenylketen ausschließlich an der NH-Gruppe unter Sulfonamid- bzw. Carboxamidbildung (s. 6 und 7). Das reaktivere (Diethylaminoacetylen)carboxamidin 4h addiert bei der Umsetzung mit Diphenylketen zusätzlich ein Ketenmolekül an der Dreifachbindung zum Cyclobutenonderivat 8. Der Propiolamidinvertreter 4b mit Diphenylaminogruppe an der Dreifachbindung reagiert mit konz. Salzsäure unter Bildung des Amidiniumsalzes 9, und unter Addition von Chlorwasserstoff an die Dreifachbindung zu 10, Mit Tosylazid erhält man nach der Triazolbildung 11 in zwei aufeinanderfolgenden 1,5-Cyclisierungen die 4-Amidino-1,2,3-triazole 12. Die 3-Aminopropiolamidine 4 mit mindestens einer Arylgruppe im Amidinteil cyclisieren im Kontakt mit Silicagel zu den 2,4-Diaminochinolinen 17. Die gleichen oder analog substituierten Chinoline 17 erhält man auch durch Umsetzung der einfachen Inamine 15 (Wasserstoff, Methyl- oder Phenylgruppen in β-Position) mit den entsprechenden Carbodiimiden 2. 2-Anilino-4-diethylamino-3-methylchinolin (17e) wird in saurem Medium zum 4-Chinolonderivat 19 hydrolysiert.
    Additional Material: 3 Tab.
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  • 18
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 127-132 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of Pterocarpan Constituents of Swartzia laevicarpaThe synthesis of 2,8-dihydroxy-3,4-dimethoxy- (1), 2,8-dihydroxy-3,9,10-trimethoxy- (2), 8-hydroxy-3,4,9,10-tetramethoxy- (3), and 2,8-dihydroxy-3,4,9,10-tetramethoxypterocarpan (4)  -  each of them as racemate  -  confirmed the constitution of four new pterocarpans isolated from Swartzia laevicarpa.
    Notes: Durch die eindeutige Synthese von jeweils racemischem 2,8-Dihydroxy-3,9-dimethoxy- (1), 2,8-Dihydroxy-3,9,10-trimethoxy-(2), 8-Hydroxy-3,4,9,10-tetramethoxy-(3) und 2,8-Dihydroxy-3,4,9,10-tetramethoxypterocarpan (4) wurde die Konstitution von vier neuen, aus Swartzia laevicarpa isolierten Pterocarpanen bestätigt.
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  • 19
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 147-156 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Diastereoselective Synthesis of (1RS)-endo-Brevicomin(1RS-endo-Brevicomin (1) is synthesized starting from trans-1-bromo-2-pentene. Synthetic key step is the diastereoselective linkage of erythro-2,3-butanediol to 3,3-dimethoxy-1-(phenylsulfonyl)-butane or methyl 4,4-dimethoxypentanoate.
    Notes: (1RS)-endo-Brevicomin (1) wird ausgehend von trans-1-Brom-2-penten synthetisiert. Schlüsselreaktion ist die diastereoselektive Verknüpfung von erythro-2,3-Butandiol mit 3,3-Dimethoxy-1-(phenylsulfonyl)butan oder 4,4-Dimethoxypentansäure-methylester.
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  • 20
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cycloarenes, a New Class of Aromatic Compounds, IV. - Attempts to Synthesize cyclo-[d.e.e.d.e.e.d.e.e]nonakisbenzene and cyclo[d.e.d.e.d.e.d.e.d.e]decakisbenzeneWith the aim to synthesize 3 the dithiaphane 5 was prepared from which via 6 the [2]anthraceno[2]benzo[c]phenanthrenophane 10 was obtained. The corresponding [2.2]phane-diene 11 was prepared from 5 via 12 and 13. The conformations of 5, 10, and 11 yielded 14 which was dehydrogenated to yield the new aromatic system 15. The second internal ring closure to 3 so far did not succeed. - As precursors for the synthesis of 4 the [2]dibenzo[a, j]anthraceno[2]anthraceno[2]phenanthrenophanes 19 and 20 as well as the corresponding [2.2]phane-dienes 23 and 24 were prepared via 18.Attempts to cyclodehydrogenate to 4 failed. In this context the conformations of 19, 20, 23, and 24 are discussed based on 1H NMR spectra.
    Notes: Mit dem Ziel der Synthese von 3 wurde das Dithiaphan 5 dargestellt, das über 6 in das [2]Anthraceno[2]benzo[c]phenanthrenophan 10 übergeführt wurde. Das entsprechende Phandien 11 wurde aus 5 über 12 und 13 erhalten. Die Konformationsverhältnisse von 5, 10 und 11 werden anhand der 1H-NMR-Spektren diskutiert. - Aus 11 entstand durch nicht-oxidative Photocyclisierung 14, das zu dem neuen aromatischen Bindungssystem 15 dehydriert wurde. Der zweite innere Ringschluß zu 3 gelang bisher nicht. - Als Vorstufen für die Synthese von 4 wurden über 18 die [2]Dibenz[a, j]anthraceno[2]phenanthrenophane 19 und 20 sowie die entsprechenden [2.2]Phandiene 23 und 24 dargestellt. Versuche der Cyclodehydrierung zu 4 schlugen fehl. In diesem Zusammenhang werden die Konformationsverhältnisse von 19, 20, 23 und 24 auf der Basis von 1H-NMR-Daten diskutiert.
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  • 21
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 773-782 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Selective Reactions of Hydroazulenes: Chiral Norcarane Derivatives by the Reaction of a Dihydroazulene with Singlet OxygenPhotosensitized oxygenation of the dihydroazulene 6 affords the two peroxides 7 and 8 in good overall yield. The major product is derived from the “norcaradiene” of 6. The cycloaddition with singlet oxygen occurs stereospecifically. Consecutive reaction of 7 yield chiral norcarane derivatives in stereospecific ways. Thus, by thermolysis of 7 the bisepoxide 10 is formed; reaction of 7 with triethylamine leads to the hydroxyketone 11 with MnO2 the homoquinone 13 is formed. The structures are established by spectroscopic methods.
    Notes: Die Umsetzung des Dihydroazulens 6 mit Singulettsauerstoff ergibt die beiden Peroxide 7 und 8. Das Hauptprodukt 7 leitet sich vom “Norcaradien” des Hydroazulens 6 ab. Die 1O2-Addition erfolgt stereoselektiv. Folgereaktionen von 7 ergeben chirale Norcaranderivate: Thermolyse führt zum Bisepoxid 10, mit Triethylamin entsteht das Hydroxyketon 11 und Triphenylphosphan führt unter Sauerstoffabspaltung zu den Vinyloxiranen 12a und 12b. Bei diesen Reaktionen wird jeweils nur ein Diastereomeres gebildet. Die Oxidation von 11 mit Mangandioxid ergibt das Homochinon 13. Für sämtliche Reaktionsprodukte sind spektroskopische Daten angegeben.
    Additional Material: 1 Ill.
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  • 22
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 791-801 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses of (+)-Oudemansin and (+)-Epioudemansin Starting from Enantiomerically Pure Precursors; Absolute configuration of the Naturally Occurring (-)OudemansinThe syntheses of the four optically pure methyl (E)-3-hydroxy-2-methyl-5-phenyl-4-pentenoates (+)- and (-)-5 as well as (+)- and (-)-6 were achieved by consecutive methylation and protonation of enolates, starting from (+)- and (-)-4. The esters (+)-6 and (-)-5 are used as starting materials to synthesize (+)-oudemansin [(+)-3] and (+)-epioudemansin [(+)-9].
    Notes: Die Darstellung der vier optisch reinen (E)-3-hydroxy-2-methyl-5-phenyl-4-pentensäure-methylester (+)- und (-)-6 gelingt durch aufeinanderfolgende Methylierung und Protonierung von Esterenolaten, ausgehend von (+)- und (-)-4. Die Ester (+)-6 und (-)-5 werden für Synthesen von (+)-Oudemansin [(+)-3] und (+)-Epioudemansin [(+)=9] eingesetzt.
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  • 23
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 820-827 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A Flexible and efficient Synthesis of Methyl 4-Oxo-2-alkenoatesThe title compounds E are obtained in good yield by low temperature ring cleavage of the easily available methyl 2-siloxycyclopropanecarboxylates C with bromine and subsequent elimination of hydrogen bromide. Due to the variability of C a high flexibility concerning substituents R1-R4 in products E is guaranteed. 2-Alkyl- and 2-methylthio-substituted olefins are thus effectively synthesized. In several cases the initally formed methyl 2-bromo-4-oxoalkanoates F are stable enough to be isolated in high yield.
    Notes: Aus den leicht zugänglichen 2-Siloxycyclopropancarbonsäure-methylestern C erhält man durch Ringöffnung mit Brom bei tiefer Temperatur und anschließender Bromwasserstoffeliminierung die Titelverbindungen E in guten Ausbeuten. Aufgrund der Variationsmöglichkeiten bei C ergibt sich bei den Produkten E eine große Flexibilität bezüglich der Reste R1-R4. So sind auch 2-alkyl- und 2-methylthiosubstituierte Olefine effektiv darstellbar. In einigen Fällen sind die primär gebildeten 2-Brom-4-oxoalkansäure-methylester F so stabil, daß sie in hoher Ausbeute isolierbar sind.
    Additional Material: 1 Tab.
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  • 24
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 828-830 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ring Opening of Methyl 2-(Trimethylsilylmethyl)cyclopropanecarboxylateThe reactivity of the title compound 5 is compared with that of methyl 2-siloxycyclopropanecarboxylates. 2. Whereas these are cleaved under various conditions, the less activated derivative 5 undergoes ring opening to yield methyl pentenoate (6a) only with sources of “free” flouride-like tetra-n-butylammonium fluoride.
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  • 25
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 381-388 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 1-Aza- and 1,9-DiazatriptycenesThe polycyclic 1,5-diketone 4 is synthesized via the enamine 2 from ketone 1 and phenyl vinyl ketone (3). On reacting the 1,5-diketone 4 with hydroxylamine the expected ring closure to the 1-azatriptycene 6 competes with a ring cleavage by an anomalous Beckmann rearrangement of the oxime yielding the intermediate nitrile 10 which cyclizes to afford the β-anthracenyl-α-aminopyridine 7. [4 + 2] Cycloaddition of dehydrobenzene, generated by diazotation of anthranilic acid, with the pyrido[3,2-g]quinolines 13a, b produces the diazatriptycenes 15a, b.
    Notes: Aus dem Keton 1 wird via Enamin 2 mit Phenylvinylketon (3) das polycyclische 1,5-Diketon 4 hergestellt. Bei dessen Umsetzung mit Hydroxylamin konkurriert der erwartete Ringschluß zum 1-Azatriptycen 6 mit einer Ringöffnung durch anomale Beckmann-Umlagerung des Oxims 9 zum intermediären Nitril 10, das zum β-Anthracenyl-α-aminopyridin 7 cyclisiert. [4 + 2]-Cycloaddition von Dehydrobenzol, das durch Diazotierung von Anthranilsäure erzeugt wird, mit den Pyrido[3,2-g]chinolinen 13a, b ergibt die Diazatriptycene 15a, b.
    Additional Material: 1 Tab.
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  • 26
    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, XXXV.  -  Voltammetry of Vinylogous Polyenes with Cross-Conjugated End Groups and UV/VIS Spectroscopy of their Radical Anions and CationsMost of the polyenes 1-5, especially of the vinylogous 2.n(n = 0-4) and 5.n(n = 1-4) are as well reversibly reduced as oxidized in two steps. As expected the large semiquinone formation constants decrease with increasing chain length (2: KSEMc = 1013-107; KSEMa = 1011-101). The UV/VIS spectra of the radical anions and cations of system 2.n, generated in solution, belong to the violene type; Δλmax ≈ 135 nm (SEMc) and Δλmax ≈ 160 nm (SEM). The potentials of 5.n and the UV/VIS spectra of the radicals of 5.1 point towards twisted molecules. The systems 2.n are the first polyenes which can exist in five oxidation levels and which form persistent radical anions and cations. The redox potentials of 2.n and the UV/VIS spectra of the radical ions are in accordance with the predictions of the Hückel theory.
    Notes: Die Mehrzahl der Polyene 1-5, insbesondere der Vinylogen 2.n (n = 0-4) und 5.n (n = 1-4) werden sowohl reversibel zweistufig reduziert als auch oxidiert. Erwartungsgemäß nehmen die großen Semichinonbildungskonstanten mit wachsender Kettenlänge ab (2: KSEMc = 1013-107; KSEMa = 1011-101). Die UV/VIS-Spektren der in Lösung erzeugten Radikalanionen und-kationen des Systems 2 (n = 0-4) sind vom Violentyp mit Δλmax ≈ 135 nm (SEMc) und Δλmax ≈ 160nm (SEM). Die Potentiale des Systems 5.n sowie die UV/VIS-Spektren der Radikal-Ionen aus 5.1 weisen auf Verdrillung hin. Mit 2.n liegen erstmals Polyene vor, die in fünf Oxidationsstufen existieren können und deren Radikal-Ionen persistente Lösungen bilden. Sowohl die Redoxpotentiale von 2.n als auch die UV/VIS-Spektren der Radikal-Ionen entsprechen den Erwartungen der Hückel-Theorie.
    Additional Material: 9 Ill.
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  • 27
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Confomational Analysis, XXIV. - determination of the Conformations of Tri-and Tetrasaccharide Sequences of N-Glycoproteins. The problem of the (1 → 6)-glycosidic BondThe preferred solution conformations of the saccharides α-D-Man(1 → 3)-β-D-Man(1 → 4)-D-GIcNAc (1), α-D-Man(1 → 6)-β-Man(1 → 4)-D-GIcNAc (2), and α-D-Man(1 → 3)[α-D-Man(1 → 6)]lβ-D-Man(1 → 4)-D-GIcNAc3), which are known as parts of the core structure of N-glycoproteins, could be established by use of HSEA calculations (HSEA: Hard-Sphere Exo-Anomeric) with the new program GESA (= Geometry of Saccharides) in connection with 1H NMR investigations like NOE experiments, spin-lattice relaxation-time measurements and the observation of selective deshieldings. (1 → 3)- and (1 → 4)-glycosidic bonds show one strongly preferred conformation. The greater flexibility of the (1 → 6)-glycosidic bonds show one strongly preferred conformation. The greater flexibility of the (1 → 6)-glycosidic bond will be discussed in details. For the spectra analysis various 2-D techniques have been used.
    Notes: Von den Sacchariden α-D-Man(1 → 3)-β-D-Man(1 → 4)-D=-GICNAc (1), α-D-Man(1 → 6)-β-D-Man(1 → 4)-D-GIcNAc(2) und α-D-Man(1 → 3)[α-D-Man(1 → 6)]-β-D-Man(1 → 4)-D-GlcNAc(3), die als Core-Struktur in N-Glycoproteinen vorkommen, wurden durch HSEA-Berechnungen (HSEA: Hard-Sphere Exo-Anomeric) mit dem neuen GESA-Programm (GESA: Geometry of Saccharides) die bevorzugten Konformationen bestimmt. Mit Hilfe von 1H-NMR-Experimenten, nämlich NOE-Experimenten, Spin-Gitter-Relaxationszeitmessungen und der Beobachtung selektiver Entschirmungen, ließen sich diese Konformationen in Lösung bestätigen. (1 → 3)- und (1 → 4)-glycosidische Bindungen weisen eine stark bevorzugte Konformation auf. Die weitaus größere Flexibilität der (1 → 6)-glycosidischen Bindung wird besonders diskutiert. Zur Analyse der Spektren wurden verschiedene 2-D-NMR-Techniken angewandt.
    Additional Material: 10 Ill.
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  • 28
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1003-1012 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions with Isocyanides. - Synthesis of Dark-blue Dyes from 1,4-Quinones and Aryl Isocyanides1,4-Benzoquinone reacts with aryl isocyanides 2a-d in boiling toluene or xylene forming darkblue 1:2 and 1:4 adducts, the 4,7-isoindolediones 3a-d and the 1,5- and 1,7-bis(arylamino)-benzodipyrrolediones 4a-c and 5a-c, respectively, which can be separated by chromatography. The structure of the 4-methylphenyl isocyanide adducts 3b, 4b, and 5b is established by NMR spectroscopy. The 1:2 adduct 3b reacts with two moles of 4-methylphenyl isocyanide (2b) affording the isomeric 1:4 adducts 4b and 5b. However, in a similar reaction with 4-chlorophenyl isocyanide (2c) surprisingly only the 1,5-bis(arylamino) derivative 8 is isolated. 1,4-Naphthoquinone (10) reacts with 4-methylphenyl (2b or 4-nitrophenyl isocyanide (2d) to yield the 4,9-benzo[f]isoindoles 11b and d, respectively.
    Notes: 1,4-Benzochinon reagiert mit den Arylisocyaniden 2a-d in siedendem Toluol oder Xylol zu tiefblauen 1:2- und 1:4-Addukten, den 4,7-Isoindoldionen 3a-d bzw. den 1,5- und 1,7-Bis(arylamino)benzodipyrroldionen 4a-c und 5a-c, die chromatographisch getrennt werden. Die Struktur der (4-Methylphenyl)isocyanid-Addukte 3b, 4b und 5b wird NMR-spektroskopisch bewiesen. Das 1:2-Addukt 3b ergibt mit zwei Molen (4-Methylphenyl)isocyanid (2b) die isomeren 1:4-Addukte 4b und 5b; mit (4-Chlorphenyl)isocyanid (2c) wird jedoch überraschenderweise nur das 1,5-Bis(arylamino) Derivat 8 isoliert. 1,4-Naphthochinon (10) bildet mit (4-Methylphenyl)-(2b) bzw. (4-Nitrophenyl)isocyanid (2d) die 4,9-Benzo[f]isoindoldione 11b und d.
    Additional Material: 1 Ill.
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  • 29
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of 1,4-Pentadien-3-ones, 22. - Synthesis and Structure of the Epimers of 3,5-Diaryl-4-hydroxy-1,4-thiazinane 1,1-DioxidesDistyrylsulfones 1 react with the ambident nucleophile hydroxylamine only by double addition of nitrogen to give 4-hydroxy-1,4-thiazinane derivatives 3. In solution 3 consists of a temperature-dependent equilibrium mixture of two epimers. When heated or when crystallized one of the epimers is depopulated. The above phenomena and structures are elucidated by an X-ray analysis and by NMR spectroscopy.
    Notes: Distyrylsulfone 1 reagieren mit dem ambidenten Nucleophil Hydroxylamin ausschließlich unter doppelter Addition des Stickstoffs zu 4-Hydroxy-1,4-thiazinan-Derivaten 3. Diese bilden in Lösung temperaturabhängige Epimeren-Gleichgewichte. Sowohl beim Erwärmen als auch beim Auskristallisieren erfolgt Depopulation eines Epimers. Strukturen und Phänomene werden durch Röntgenstrukturanalyse und NMR-Spektroskopie geklärt.
    Additional Material: 5 Ill.
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  • 30
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1052-1055 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Iodation of Monosaccharide Derivatives with IodotrimethylsilaneWith iodotrimethylsilane generated in situ, iodine can be introduced into carbohydrate derivatives with high selectivity. The rate of iodination at the anomeric center of the C-1-substituted 2,3,4,6-tetra-O-acetyl-D-glucopyranoses 1a-d decreases in the following series: OAc 〉 OBz ≈ OH » OCH3. - Hydroxy groups or their ethers 3b, c react distinctively to give the trimethylsilyl ethers, whereas the primary react to yield the 6-deoxy-6-iodo derivatives 5. The 1-O-acetyl-6-hydroxy derivative 6a and its 6-O-trityl ether form 2,3,4-tri-O-acetyl-6-deoxy-6-iodo-α-D-glucopyranosyl iodide (7).
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  • 31
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1068-1077 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: An Attempted Synthesis of Polystachin[1′RS(3RS)]-1-(2,3-Dihydro-4-hydroxy-6-methoxy-1-benzofuran-3-yl)-2-methyl-1,2-propandiol (21), a partial structure of the title substance 1 was synthetized in 11 steps from phloroglucinol. The key steps were the oxidative rearrangement of the benzylidenacetone derivative 5 by Tl(NO3)3 in methanol to yield the 2-aryl-1,1-dimethoxythane 8 followed by ring closure involving the hydroxy group of 9 liberated by debenzylation. Conversion of 21 into compounds of structure 1 was just as unsuccessful as the synthesis of rac-polystachin (rac-1) from tachrosin (23 via the flavone derivative 29.
    Notes: [1′RS(3RS)]-1-(2,3-Dihydro-4-hydroxy-6-methoxy-1-benzofuran-3-yl)-2-methyl-1,2-propandiol (21), eine Teilstruktur der Titelsubstanz 1, wurde aus Phloroglucin in 11 Schritten synthetisiert. Als Schlüsselreaktion diente die oxidative Umlagerung des Benzalacetonderivates 5 mit Tl(NO3)3 in Methanol zu dem 2-Aryl-1,1-dimethoxyethan 8 gefolgt vom Ringschluß an der durch Entbenzylierung freigesetzten Hydroxygruppe von 9. Die Überführung von 21 in Verbindungen der Struktur 1 blieb ebenso erfolglos wie die Synthese von rac-Polystachin (rac-1) aus Tachrosin (23) über das Flavonderivat 29.
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  • 32
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1109-1116 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemistry of Dimethyl [1α,2β,5α,6β,7α,8β]-3,4-Dioxotricyclo[4.2.1.02,5]nonane-7,8-dicarboxylateThe reaction of the cyclobutanedione 1 with urea or substituted thioureas provides by double addition the heterocyclic compounds 2a-d. Hydrazines react to give monohydrazones 3 or, by loss of nitrogen, hydrazones of type 4; no formation of osazones was observed. The reaction with o-phenylenediamine yields the quinoxaline 5. Reduction of 1 with sodium tetrahydroborate leads stereoselectively to the glycol 6. Treatment of 1 with sodium methoxide causes benzilic acid rearrangement yielding the annulated cyclopropanecarboxylate 7 with retention of the configuration of the other carbon atoms. Ring enlargement reactions yield either by radiation of 1 via oxacarbenes compound 14 or by oxidation the anhydride 8 which can be reduced to yield the γ-lactone 9.
    Notes: Die Umsetzung des Cyclobutandions 1 mit Harnstoff oder substituierten Thioharnstoffen führt durch zweifache Addition unter Cyclisierung zu den Imidazolidinonen bzw. -thionen 2a-d. Hydrazinabkömmlinge liefern Monohydrazone 3 oder unter Stickstoffabspaltung Hydrazone vom Typ 4; Osazonbildung wurde nicht beobachtet. Mit o-Phenylendiamin entsteht unter Kondensation das Chinoxalin 5. Die Reduktion von 1 mit Natrium-tetrahydroborat liefert stereoselektiv das Glycol 6. Mit Natriummethanolat findet eine Benzilsäure-Umlagerung zum anellierten Cyclopropancarbonsäureester 7 unter Erhaltung der Konfiguration der restlichen C-Atome statt. Ringerweiterungen lassen sich sowohl photochemisch über Oxacarbene zu 14 als auch durch Oxidation zum Anhydrid 8 durchführen, das durch anschließende Reduktion das Norbornan-anellierte γ-Lacton 9 liefert.
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  • 33
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 608-611 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Syntheses with α-Metalated Isocyanides, LIII.  -  Synthesis of Methyl 2,3-Epoxy-2-isocyanoalkanoatesThe title compounds were synthesized from methyl α-isocyanoacrylates 2 with H2O2 (in sodium hydroxide solution) or with m-chloroperbenzoic acid (in methanol/sodium methoxide)
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  • 34
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 600-607 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese und biologische Aktivität des Antibiotikums B 371 und seiner StrukturvariantenDie Synthesen der Titelverbindung 1 und einer Reihe von Strukturvarianten des Typs 4 werden beschrieben. Die antimikrobiellen Aktivitäten dieser Vinylisocyanide, die in β-Position entweder ein Indolderivat oder eine Aryl- oder 2-Thienylgruppe tragen, wurden im Plattentest gegenüber Escherichia coli, Bacillus subtilis und Mucor muhei TÜ 284 geprüft (Tab. 1). Einige der Verbindungen 4 sind stärker wirksam als die natürlich vorkommende Stammverbindung 1.  -  Eine Serie von Alkyl-2-isocyanacrylaten des Typs 5 wurde in den Test einbezogen. Einige davon sind außerordentlich stark aktiv (Tab. 2). Die Aktivität geht in allen Fällen verloren, wenn man die Isocyangruppe zur Formamidogruppe hydrolysiert (4 → 6).
    Notes: The synthesis of the title compound 1 is described as well as the syntheses of a series of structural analogs of type 4. The antimicrobial in vitro activity of these vinyl isocyanides, substituted in β-position either by an indole derivative or by an aryl or 2-thienyl group, was tested against Escherichia Coli, Bacillus subtilis, and Mucor muhei TÜ 284 (Table 1). Some of the compounds 4 display higher activity than the naturally occurring parent compound 1.  -  A variety of alkyl 2-isocyanoacrylates of type 5 were included in the biological test. Some of them display exceptionally high antimicrobial activity (Table 2). Upon conversion of the isocyano group into the formamido group (4 → 6), the biological activity is lost.
    Additional Material: 2 Tab.
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  • 35
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 615-617 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: [2.2](2,7)Anthracenophane: Synthesis and Conformational Studies[2.2](2,7)Anthracenophane (3) was synthesized via the dithia[3.3]anthracenophane 6 and the disulfone 7 derived therefrom. From conformational studies based on 1H NMR a rigid anti conformation was assigned to 3, contrary to 6.
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  • 36
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Multistep, Reversible Redox Systems, XXXVI.  -  11,11,12,12-Tetracyano-9,10-anthraquinodimethane (TCNAQ) and its Derivatives: Synthesis and Redox PropertiesTitle compounds 3Ba-d are synthesized from the corresponding anthraquinones and malononitrile with titanium tetrachloride/pyridine. By comparison of the potentials and semiquinone formation constants of 1B-3B with those of the corresponding quinones 1A-3A strong distortion of the biscyanomethylene groups in 2B and especially 3B is derived.
    Additional Material: 1 Tab.
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  • 37
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 636-640 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Stereospezifische Synthesen von D-Ossamin und D-Tolyposamin2,3,4,6-Tetradesoxy-4-(dimethylamino)-D-threo-hexose (D-Ossamin, 7), der Aminozuckerrest des Pilzmetaboliten Ossamycin und 4-Amino-2,3,4,6-tetradesoxy-D-erythro-hexose (D-Tolyposamin, 12), das Enantiomere des Zuckerrestes des antibiotisch wirksamen Tolypomycins wurden aus D-Glucose über Hex-2-enopyranoside synthetisiert.
    Notes: 2,3,4,6-Tetradesoxy-4-(dimethylamino)-D-threo-hexose (D-ossamine, 7), the amino sugar fragment from the fungal metabolite ossamycin, and 4-amino-2,3,4,6-tetradeoxy-D-erythro-hexose (D-tolyposamine, 12), the enantiomeric constituent of the antibiotic tolypomycin, have been synthesized from D-glucose via hex-2-enopyranosides.
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  • 38
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 649-679 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses with Aliphatic Dialdehydes, XXXVIII. - Synthesis and Properties of CycloalkylmalonaldehydesVilsmeier formylation cycloalkyl-substituted enol ethers (7, 14a - c, 23) yields the cycloalkylmalonaldehydes 1- 5 for the first time. In solution 1 - 5 with suitable electrophiles and nucleophiles leads to cycloalkyl-substituted open-chain (29, 30), carbocyclic (31) as well as heterocyclic compounds (32-40) with peculiar properties due to the presence of the lipophilic cycloalkyl group.
    Notes: Durch Vilsmeier-Formylierung cycloalkylsubstituierter Enolether (7, 14a - c, 23) werden die Cycloalkylmalonaldehydes 1 - 5 erstmals dargestellt. In Lösung liegen 1 - 5 in der (E)-s-(E)-Enolform als vinyloge Carbonsäuren vor. Reaktion von 1-5 mit geeigneten Elektrophilen und Nucleophilen führt zu cycloalkylsubstituierten offenkettigen (29, 30), carbocyclischen (31) und heterocyclischen Verbindungen (32-40) mit besonderen, durch die lipophile Cycloalkylgruppe hervorgerufenen Eigenschaften.
    Additional Material: 1 Tab.
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  • 39
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: (2′→5′) and (3′→′)-Tubercidylyl-tubercidins - Synthesis via Phosphite Triester and Investigation of Secondary StructureThe (2′→ 5′)- and (3′→5′)-linked dinucleoside monophosphates 3e and 2e of tubercidin were synthesized by condensation of the monomers 1c or 1b with dichloromethoxyphosphane. By 1H NMR studies it could be demonstrated that the conformation of these nucleobases is different from that in (3′→ 5′)ApA and (2′→ 5′)ApA. From thermodynamic parameters, as well as from hypochromicity, a stronger base - base interaction in 3e than in 2e was deduced. Single-strand specific nuclease S1 hydrolyses 2e at a much higher rate than (3′→ 5′)ApA demonstrating that the enzyme is sensitive towards modification of the aglycone. Condensation of the 5′-deprotected dimer 3b with the monomer 1c followed by complete deprotection yields (2′→ 5′)TupTuTu (4e), which is an analogue of (2′→ 5′)ApApA, the triphosphate of which is antivirally active.
    Notes: Die (2′→ 5′)- und (3′→ 5′)-verknüpften Dinucleosid-monophosphate 3e und 2e des Tubercidins werden aus den Vorstufen 1b oder 1c und 1a durch Kondensation mit Dichlormethoxyphosphan erhalten. Mit 1H-NMR-Untersuchungen konnte gezeigt werden, daß die Nucleobasen eine andere Konformation als im (2′→ 5′)- oder (3′→ 4′)ApA einnehmen. Aus thermodynamischen Parametern sowie der Hypochromizität ergibt sich für 3e eine größere Basenwechselwirkung als für 2e. Einzelstrang-spezifische Nuclease S1 spaltet 2e deutlich schneller als (3′→ 5′)ApA und reagiert damit empfindlich auf die Aglyconmodifikation. Die Kondensation des 5′-entschützten Dimers 3b mit dem Monomer 1c, gefolgt von der Abspaltung der Schutzgruppen, führt zu (2′→ 5′)-TupTupTu (4e). Dies stellt ein Analogon von (2′→ 5′)ApApA dar, das als Triphosphat antiviral wirksam ist.
    Additional Material: 3 Ill.
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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: Chemistry and Stereochemistry of Iridoids, IV. - Synthesis and X-Ray Structure Analysis of 15-Methyl-12-epi-prostaglandin F2βCrystalline(15R)- and (15S)-15-methyl-12-epi-PGF2β [15R)-5b and 5b] are synthesized enantiomerically pure starting from (1S,6R,9R)-(+)-7,9-bis(p-phenylbenzoyloxy)-3-oxabicyclo- [4.3.0]nonan-2-ol (1), which is prepared from catalpol. Contrary to our described synthesis of 12-epi-PGF2β, the intermediate products 2-5a are crystalline by virtue of the introduction of the p-phenylbenzoyl protecting group. Thus, their physical constants could be determined unequivocally. The X-ray structure analysis of (15R)-15-epi-PGF2β proves the correctness of our earlier statements based on analytical and spectroscopical investigations.
    Notes: Ausgehend von dem aus Catalpol hergestellten (1S,6R,7R,9R)-(+)-7,9-Bis(p-phenylbenzoyloxy)-3-oxabicyclo[4.3.0]nonan-2-ol (1) werden (15R)- und (15S)-15-Methyl-12-epi-PGF2β [(15R)-5b und 5b] kristallin und enantiomerenrein synthetisiert. Im Gegensatz zu der von uns beschriebenen Synthese von 12-epi-PGF2β sind durch die Einführung der p-Phenylbenzoyl-Schutzgruppen auch die Zwischenprodukte 2-5a kristallin, so daß ihre physikalischen Konstanten eindeutig bestimmt werden konnten. Die Röntgenstrukturanalyse von (15R)-15-Methyl-12-epi-PGF2β beweist, daß die von uns aus den analytischen und spektroskopischen Untersuchungen gemachten Aussagen richtig sind.
    Additional Material: 2 Ill.
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  • 41
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 877-887 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 5,10-Bridged Pyrido[3,2-g]quinolines via [4+2] Cycloaddition of Dienophiles to Pyrido[3,2-g]quinolinesIn a Diels-Alder reaction, (E)-1,2-dichloroethene (5a), α-acetoxyacrylonitrile (5b), and maleic anhydride (8), respectively, add to the medium ring of some pyrido[3,2-g]quinolines to afford the 5,10-bridged pyrido[3,2-g]quinolines 6a - c, e, f, and 9a - c, respectively. The regioisomeric α-acetoxyacrylonitrile adducts of 4b arise in a ration of 6e:6f = 94.6. On hydrolysis of this mixture, only ketone 7 is obtained. The structures of all compounds are proven by their proton and carbon-13 spectra.
    Notes: (E)-1,2-Dichlorethen (5a), α-Acetoxyacrylnitril (5b) bzw. Maleinsäureanhydrid (8) addieren sich in einer Diels-Alder-Reaktion an den mittleren Ring einiger Pyrido[3,2-g]chinoline 4 zu den 5, 10-überbrückten Pyrido[3,2g]chinolinen 6a - c, e, f bzw. 9a - c. Die regioisomeren α-Acetoxyacrylnitril-Addukte von 4b entstehen dabei im Verhältnis 6e:6f = 94:6. Durch Hydrolyse erhält man daraus das einheitliche Keton 7. Die Strukturen aller Verbindungen wurden 1H- und 13C-NMR-spektroskopisch bewiesen.
    Additional Material: 4 Tab.
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  • 42
    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, X. - Reaction with Aromatic carbodiimides - Synthesis of BenzothiadiazinesDiphenyl- and bis(4-methoxyphenyl)carbodiimide react with N-methyl-N-sulfinylmethanaminium tetrafluoroborate (2) to give benzothiadiazine 1-oxides 3. The structure of the substituted compound 3a was determined, the course of the complex reaction is discussed.
    Notes: Diphenyl- und Bis(4-methoxyphenyl)carbodiimid reagieren mit N-Methyl-N-sulfinylmethanaminium-tetrafluoroborat (2) unter Bildung von Benzothiadiazin-1-oxiden 3. Die Struktur der substituierten Verbindung 3a wurde bestimmt, der Verlauf der komplexen Reaktion wird diskutiert.
    Additional Material: 2 Tab.
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  • 43
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese von Peptiden mit α,β-Dehydroaminosäuren, I. - Synthese von N-(Benzyloxycarbonyl)-und N-(Trifluoracetyl) dipeptiden von Dehydroalanin und DehydrophenylalaninDie Kondensation von Nα-(Benzyloxycarbonyl)- und Nα-(Trifluoracetyl)aminosäureamiden mit Brenztrauben- und Phenylbrenztraubensäure in Gegenwart von p-Toluolsulfonsäure als Katalysator führt zu N-(Benzyloxycarbonyl)- und N-(Trifluoroacetyl)dehydrodipeptiden mit C-ständigem ΔAla bzw. ΔPhe (Tab 2 und 3).
    Notes: Condensation of amides of N-(benzyloxycarbonyl)- and N-(trifluoroacetyl)amino acid with pyruvic and phenylpyruvic acid yields, in the presence of p-toluenesulfonic acid as a catalyst, N-(benzyloxycarbonyl)- and N-(trifluoroacetyl)dehydro dipeptides with C-terminal Δ Ala and ΔPhe, respectively (Table 2 and 3).
    Additional Material: 4 Tab.
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  • 44
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Asymmetric Synthesis via Heterocyclic Intermediates, XXIII. - Studies on the Enantioselective Synthesis of α-Alkyl-α-(2-furyl)glycines by Alkylation of 3-(2-furyl)-3,6-dihydro-2H-1,4-oxazin-2-ones chirally Substituted at C-63-(2-Furyl)-3,6-dihydro-2H-1,4-oxain-2-ones 10 and 11 are synthesized from DL-(2-furyl)glycine and 2-hydroxyalkanoic acids 4. The heterocycles 10 and 11 contain an endocyclic chiral center at C-6. Their potassium derivatives 12 (obtained with potassium tert-butoxide) react with alkyl halides R2 - X in good chemical yields and with d. e. values (d. e. = asymmetric induction) from 50 → 95% to give the adducts 13. These on hydrolysis are cleaved to yield α-alkyl-α-(2-furyl)-glycines 17 and 2-hydroxyalkanoic acids 4.
    Notes: Ausgehend von DL-(2-Furyl)glycin und den 2-Hydroxyalkansäuren 4 werden die 3-(2-Furyl)-3,6-dihydro-2H-1,4-oxazin-2-one 10 und 11 aufgebaut, die an C-6 ein endocyclisches Chiralitätszentrum besitzen. Deren Kaliumverbindungen 12 (erhalten mit Kalium-tert-butylat) reagieren mit Alkylhalogeniden R2 - X an C-3 mit guten chemischen Ausbeuten und mit 50 → 95% d.e.) (d.e. = asymmetrische Induktion). Der Alkylrest R2 tritt trans zu R1 (am induzierenden Zentrum) ein. Bei der Hydrolyse der Addukte 13 werden die 2-Hydroxyalkansäuren 4 und die (optisch aktiven) α-Alkyl-α-(2-furyl)glycine 17 freigesetzt.
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  • 45
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1513-1518 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigations on the Origin of 3,6-Epoxyalkanedioic Acids in Human UrineThe 3,6-epoxyalkanedioic acids 1-4 recently found in human urine are obviously metabolic end products of so far unknown precursors produced in the body.
    Notes: Die im Humanurin kürzlich aufgefundenen 3,6-Epoxyalkandisäuren 1-4 sind offenbar Endabbauprodukte im Körper gebildeter bisher unbekannter Vorstufen.
    Additional Material: 1 Ill.
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  • 46
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984) 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 47
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metalloporphyrine in polymeren Matrizen. Mizellen und Vesikeln, VI. - Hydrophobe und hydrophile Derivate des 3,8-Diformyldeuteroporphyrin-dimethylesters und ihre Wechselwirkung mit Vesikeln3,8-Diformyldeuteroporphyrin-dimethylester (1a) wurde durch Ozonisierung des diprotonierten Dikations von Protoporphyrin-dimethylester 1b erhalten. Mehrere Derivate wurden dargestellt, die entweder hydrophobe Eigenschaften aufweisen oder hydrophile Substituenten in der “nördlichen Hemisphäre” des Porphyrinliganden oder an beiden Seiten tragen. Die Porphyrine wurden in wäßrigen Medien gelöst, die Vesikel mit elektroneutralen, -negativen oder -positiven Oberflächenladungen enthielten. Der Aufenthaltsort der gelösten Porphyrine wurde durch den spektroskopischen Nachweis von Reaktionen der zentralen Porphyrin-Stickstoffatome oder von peripheren Substituenten mit wasserlöslichen Säuren oder Metall-Ionen bestimmt.
    Notes: 3,8-Diformyldeuteroporphyrin dimethyl ester (1a) was obtained by ozonization of the diprotonated dication of protoporphyrin dimethyl ester 1b. Several derivatives have been prepared, which are either hydrophobic, or bear hydrophilic substituents in the „northern hemisphere“ of the porphyrin ligand or on both sides. The porphyrins have then been dissolved in aqueous media containing vesicles with electroneutral, -negative, or -positive surface charges. The localization of the dissolved porphyrin chromophore was determined spectroscopically following reactions of the central porphyrin nitrogen atoms or of peripheral substituents with water-soluble acids or metal ions.
    Additional Material: 4 Ill.
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  • 48
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1740-1745 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Retinoids and Carotenoids, II. - Synthesis of (13Z)-Retinoic AcidsPhosphonium ylides 3 react with (E)-2-methyl-3-(4-methyl-2-oxo-2H-pyran-6-yl)propenal (2) to give 2-pyrone derivatives 4 which undergo ring opening by treatment with sodium tetrahydroborate/potassium hydroxide/methanol affording (13Z)-retinoic acids.
    Notes: Phosphoniumylide 3 reagieren mit (E)-2-Methyl-3-(4-methyl-2-oxo-2H-pyran-6-yl)propenal (2) zu 2-Pyronderivaten 4, bei deren Reduktion mit Natrium-tetrahydroborat/Kaliumhydroxid/Methanol unter Ringöffnung (13Z)-Retinoidsäuren 5 entstehen.
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  • 49
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984) 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 50
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1759-1777 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Pyrans, 100.  -  5,6-Dihydro-2H-pyran-3(4H)-one as a Building Unit for the Synthesis of Pyran-annulated Heterocyclic CompoundsOnly in a few cases 5,6-dihydro-2H-pyran-3(4H-one (3) reacts regioselectively with ortho-substituted phenylcarbonyl compounds to form pyran-annulated heterocyclic compounds like the pyrano[3,2-b]quinoline 7c. Better results are obtained in reactions involving the enamine 15d derived from 3, the silyl enol ether 18 and the lithium enolate 14 derived from 18. These pyran derivatives with 2,3- or 3,4-double bonds are well suited for successful synthesis of 2- or 4-substituted 3-pyranones such as 2, 21a, 21b, 23a-c, 26a-c, 31a-c, 32, and 35a-c. They also allow to synthesize pyrano[3,2-b]- or -[3,4-b]quinolones, -chromones, and -thiochromones 6a, 30a-c, 38a-d.
    Notes: Während 5,6-Dihydro-2H-pyran-3(4H)-on (3) sich mit ortho-substituierten Phenylcarbonylverbindungen nur in Einzelfällen regioselektiv zu pyrananellierten Heterocyclen umsetzt - z. B. zum Pyrano[2,3-b]chinolin 7c -, gelingt das besser mit dem aus 3 hergestellten Enamin 15d, dem Silylenolether 18 und dem daraus gewonnenen Lithiumenolat 14. Diese Pyranderivate mit 2,3-oder 3,4-Doppelbindungen eignen sich zur gezielten Darstellung von 2- oder 4-substituierten 3-Pyranonen - z.B. 2, 21a, 21b, 23a-c, 26a-c, 31a-c, 32, sowie 35a-c - und von Pyrano[3,2-b]- oder -[3,4-b]chinolinen, -chinolonen, -chromonen und -thiochromonen 6a, 30a-c und 38a-d.
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  • 51
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1785-1790 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of Further Eremophilane DerivativesStarting with suitable octalin derivatives two further eremophilane derivatives (9 and 13) isolated from Euryops species were synthesized via the epoxides 5 and 6 by regiospecific ring opening with isopropenylmagnesium bromide in the presence of copper(I) iodide followed by appropriate transformation of the eremophilanes obtained. While the preparation of the racemic ketone 9 caused no problems, the corresponding 2α-hydroxy derivative in the trans-decalin series could not be obtained in satisfactory yields. The configurations of the natural compounds have now finally been elucidated.
    Notes: Ausgehend von geeigneten Octalin-Derivaten werden zwei aus Euryops-Arten isolierte Eremophilan-Derivate (9 und 13) über die Epoxide 5 und 6 durch regiospezifische Ringöffnung mit Isopropenylmagnesiumbromid in Gegenwart von Kupfer(I)-iodid und entsprechende Umwandlung der erhaltenen Eremophilane synthetisiert. Während die Darstellung des racemischen Ketons 9 keine Probleme bereitet, konnte das entsprechende 2α-Hydroxy-Derivat in der trans-Decalin-Reihe nicht in befriedigenden Ausbeuten erhalten werden. Die Konfigurationen der Naturstoffe sind damit endgültig geklärt.
    Additional Material: 1 Tab.
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  • 52
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1696-1701 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Chemistry of Amino Oximes, XVIII. - The Cyclocondensation of (E)-β-(Chloroacetylamino)propiophenone Oxime DerivativesThe (E)-β-(chloroacetylamino)propiophenone oximes 2a-c cyclocondense by reaction with alkali to form 3,11-diphenyl-1,9-dioxa-2,6,10-14- tetraazacyclohexadeca-2,10-diene-7,15-diones 3a-c. From (E)-β-[(benzyl)(chloroacetyl)amino]propiophenone oximes 5a-c the 6-benzyl-5,6-dihydro-3-phenyl-4H- 1,2,6-oxadiazocin-7(8H)-one derivates 6a-c are formed.
    Notes: Die (E)-β-(Chloracetylamino)propiophenon-oxime 2a-c werden durch Alkali zu 3,11-Diphenyl-1,9-dioxa-2,6,10,14-tetraazacyclohexadeca-2,10-dien-7,15-dionen 3a-c cyclokondensiert. Aus (E)-β-[(Benzyl)(chloracetyl)amino]propiophenon-oximen 5a-c entstehen dagegen die 6-Benzyl-5,6-dihydro-3-phenyl-4H-1,2,6-oxadiazocin-7(8H)-on-Derivate 6a-c.
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  • 53
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1711-1718 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Enehydrazines, 37. - Synthesis of a Pyrazole Analogue of 7-AminomitoseneThe 9-step synthesis of 7-amino-10-azamitosene (2b) from 3a is described. The crystal-structure analysis of the precursor 1b of 3a secures the position of the substituted propyl group at N-1 of compounds 1 and 3-7.
    Notes: Die neunstufige Synthese von 7-Amino-10-azamitosen (2b) aus 3a wird beschrieben. Die Kristallstrukturanalyse des Vorläufers 1b von 3a sichert die Stellung des substituierten Propylrestes an N-1 der Verbindungen 1 und 3-7.
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  • 54
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1719-1730 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of 2′-Deoxyribofuranosides of 7H-Pyrrolo[2,3-d]pyrimidine: Influence of the C-2 Substituents on the Fluorescence7-Deaza-2′-deoxynebularine (2a), its 2-methylthio (2b) and 2-amino derivative (2c) have been synthesized via phase-transfer glycosylation of the nucleobases 3a, 3b, and 3c, respectively, with the 2-deoxyhalogenose 6. Glycosylation of 3a leads to the formation of a 3:1 mixture of the anomers 7a and 8a in 48-% total yield, the corresponding reaction of 3b or 3c gives mainly the β anomers in increased yield. Cleavage of the protecting groups yields 2a-c or the anomers 8a and 8c. The 2-methylthio group, as well as the 2-amino group increase the fluorescence of the parent nucleoside 2a.
    Notes: 7-Desaza-2′-desoxynebularin (2a), sein 2-Methylthio- (2b) und sein 2-Aminoderivat (2c) wurden durch Phasentransferglycosylierung der Aglycone 3a, 3b und 3c mit der Desoxyhalogenose 6 dargestellt. Die Glycosylierung von 3a führt in 48proz. Ausbeute zum 3:1-Anomerengemisch der toluoylierten Nucleoside 7a und 8a; die entsprechende Reaktion von 3b und 3c ergibt bei erhöhter Ausbeute hauptsächlich die β-Anomeren. Abspaltung der Schutzgruppen liefert 2a-c bzw. die Anomeren 8a und 8c. Sowohl die 2-Methylthiogruppe als auch der 2-Aminosubstituent verstärken die Fluoreszenz der Stammverbindung 2a.
    Additional Material: 4 Tab.
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  • 55
    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, I. - Miotoxin B and C, two New Macrocyclic Trichothecenes From Baccharis coridifolia DCFrom extracts of the toxic Brazilian plant Baccharis coridifolia, two further macrocyclic trichothecenes were isolated. The structures of these compounds, named by us as miotoxin B and C, were elucidated by application of mass spectrometry and homo- and heteronuclear two-dimensional NMR techniques.
    Notes: Aus Extrakten der brasilianischen Giftpflanze Baccharis coridifolia wurden zwei macrocyclische Trichothecene isoliert. Die Strukturen der von uns als Miotoxin B und C bezeichneten Substanzen wurden durch Massenspektroskopie und durch homo- und heteronucleare zweidimensionale FT-NMR-Techniken aufgeklärt.
    Additional Material: 4 Ill.
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  • 56
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1755-1758 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Contributions to the Chemistry of Tetraketones, III. - Synthesis and Some Reactions of 1,6-Bis(p-hydroxyphenyl)-1,3,4,6-hexanetetroneCondensation of p-hydroxyacetophenone and diethyl oxalate in the presence of sodium ethoxide gave the tetraketone 3 which can be cyclized with o-phenylenediamine, hydrazine, or phenyl-hydrazine to yield the quinoxaline 1 or the 3,3′-bipyrazolyl derivatives 5 and 6, respectively. Transformation of the p-hydroxyphenyl group in compounds 1 and 3 with methyl isocyanate/triethylamine gave the corresponding carbamates 2 and 4. By condensation of 4 with hydrazine or phenylhydrazine the pyrazoles 7 and 8 were prepared. Compounds 4, 7, and 8 showed no progressive inhibitory properties against acetylcholinesterase.
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  • 57
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1778-1784 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: (1α,2α,5α,6α)-3,4-Bis(trimethylsiloxy)tricyclo[4.2.1.02,5]nona-3,7-diene on Treatment with Oxidative Reagents(1α,2α,5α,6α)-3,4-Bis(trimethylsiloxy)tricyclo[4.2.1.02,5]nona-3,7-diene (1) is treated with different oxidative reagents. The reaction with halogens (Br2, Cl2) primarily yields the cyclobutanedione 2 which adds a second mole of halogen at the olefinic double bond. The adduct 3 is stabilized by forming 4a with an intramolecular ether bridge. Addition of chlorine to 2 directly yields 4b.  -  Reaction of 1 with DMSO/Ac2O or Cu(II) acetate in acetic acid causes an oxidative dimerization to yield 5 or 6, respectively. In the case of Cu(II) acetate the anhydride 7 is obtained as a second product.
    Notes: (1α,2α,5α,6α)-3,4-Bis(trimethylsiloxy)tricyclo[4.2.1.02,5]nona-3,7-dien (1) wird mit verschiedenen Oxidationsmitteln behandelt. Die Reaktion mit Halogenen (Br2, Cl2) liefert zunächst das Cyclobutandion 2, das ein weiteres Mol Halogen an die olefinische Doppelbindung addiert. Das Dihalogenaddukt 3 stabilisiert sich durch Ausbildung einer intramolekularen Etherbrücke zu 4a. Addition von Chlor an 2 liefert unmittelbar 4b.  -  Durch Umsetzung von 1 mit DMSO/Ac2O oder mit Cu(II)-acetat/Eisessig findet eine oxidative Dimerisation zu 5 bzw. 6 statt. Im Falle der Oxidation mit Cu(II)-acetat wird als Nebenreaktion eine Ringerweiterung zum Anhydrid 7 beobachtet.
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  • 58
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 223-227 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Nef Reaction, VI.  -  4,5-Dihydro-5-(methyleneamino)-3-furancarboxylatesNitronic acids of the adducts of α-nitroolefines and acetoacetates react with compounds with CH-acidic methylene groups to yield 4,5-dihydro-5-(methyleneamino)-3-furancarboxylates 8. Structure 8b is proved by 13C NMR investigations. Facts supporting the mechanism are reported.
    Notes: Nitronsäuren der Addukte aus α-Nitroolefinen und Acetessigestern reagieren mit CH-aciden Methylengruppen zu 4,5-Dihydro-5-(methylenamino)-3-furancarbonsäureestern 8. 13C-NMR-Untersuchungen beweisen Struktur 8b. Befunde zum Mechanismus werden mitgeteilt.
    Additional Material: 1 Tab.
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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: New Spirosesquiterpenelactones, Germacranolides, and Eudesmanolides from Wunderlichia mirabilisA reinvestigation of the aerial parts of Wunderlichia mirabilis afforded in addition to known compounds ten sesquiterpenelactones, three cis-12,6-germacranolides (7-9), three eudesmanolides (11, 13 and 14), an elemanolide (12) which may be an artifact, and three rearranged eudesmanolides, the spiro compounds 17-19 as well as ylangenyl acetate (1). The structures were elucidated by high-field 1H NMR spectroscopy and some chemical transformations. The stereochemistry of wunderolide (10) and of two onoseriolide (24 and 25) derivatives, which were isolated previously, are corrected.
    Notes: Eine erneute Untersuchung der oberirdischen Teile ovn Wunderlichia mirabilis ergibt zusätzlich zu bekannten Verbindungen zehn Sesquiterpenlactone, drei cis-12,6-Germacranolide (7-9), drei Eudesmanolide (11, 13 und 14), ein Elemanolid (12), das ein Artefact sein könnte, und drei umgelagerte Eudesmanolide, die Spiroverbindungen 17-19 sowie Ylangenylacetat (1). Die Strukturen werden durch Hochfeld-1H-NMR-Spektroskopie und einige chemische Umwandlungen geklärt. Die Stereochemie von Wunderolid (10) und von zwei Onoserioliden (24 und 25), die früher isoliert wurden, wird korrigiert.
    Additional Material: 5 Tab.
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  • 60
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 259-263 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: New Synthetic Methods, 9.  -  S-Alkyl 4-Methylbenzenethiosulfonates, Excellent Reagents for α-Thiolation of Cyclic KetonesS-Alkyl 4-methylbenzenethiosulfonates, easily prepared by alkylation of commercially available potassium 4-methylbenzenethiosulfonate in dry dimethylformamide, thiolate enolates of cyclic ketones in α position in high yield.
    Notes: 4-Methylbenzolthiosulfonsäure-S-alkylester, darstellbar aus dem käuflichen Kaliumsalz der 4-Methylbenzolthiosulfonsäure durch Umsetzen mit Alkylbromiden oder -iodiden in wasserfreiem Dimethylformamid, thiolieren die Enolate cyclischer Ketone in α-Position in hohen Ausbeuten.
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  • 61
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 273-282 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: ara-7-Deazaxanthosine  -  A Xanthine Nucleoside with a Stabile N-Glycosylic Bondara-7-deazaxanthosine (2) has been synthesized via phase-transfer glycosylation from 2,4-dimethoxy-7H-pyrrolo[2,3-d]pyrimidine (5b) and the halogenose 6. The main product of glycosylation was the β anomer 8. Therefrom the benzyl protecting groups have been removed with boron trichloride, and the 2,4-dimethoxy residues have been cleaved with acid. In contrast to xanthosine (1a) the 7-deazapurine nucleoside 2 exhibits a stable N-glycosylic bond in acidic hydrolyses. By comparison of the kinetic data of purine nucleosides with those of compound 2 a reaction mechanism of proton-catalyzed hydrolysis is suggested which explains the stability of the pyrrolo[2,3-d]pyrimidine nucleoside 2.
    Notes: ara-7-Desazaxanthosin (2) wurde durch Phasentransferglycosylierung von 2,4-Dimethoxy-7H-pyrrolo[2,3-d]pyrimidin (5b) mit der Halogenose 6 dargestellt. Von dem bei der Glycosylierung bevorzugt gebildeten β-Anomer 8 wurden die Benzylschutzgruppen mit Bortrichlorid entfernt und die 2,4-Dimethoxyreste mit Säure abgespalten. Das 7-Desazapurin-Nucleosid 2 besitzt im Gegensatz zu Xanthosin (1a) eine bei saurer Hydrolyse stabile N-glycosylische Bindung. Durch Vergleich kinetischer Parameter von Purin-Nucleosiden mit denen von 2 wird ein Reaktionsmechanismus der protonenkatalysierten Hydrolyse beschrieben, der auch die Stabilität des Pyrrolo[2,3-d]pyrimidin-Nucleosids 2 erklärt.
    Additional Material: 3 Tab.
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  • 62
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 395-396 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chemie der Hydroxamsäuren, 10. Eine bequeme Umlagerung von 4-Chinolincarbohydroxamsäure4-Chinolincarbohydroxamsäure wurde in einer Variante des Hydroxamsäure→Isocyanat-Abbaus nach Lossen umgelagert. Dabei wurden je nach Art der Reaktionsbedingungen 4-Aminochinolin (2) oder N-(4-Chinolyl)harnstoff (3) erhalten.
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  • 63
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 401-406 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A New Method for the Degradation of Anthocyanidins, Flavones, Chalcones, and CoumarinsAfter transformation into the corresponding chalcone or flavenol acetates anthocyanidins are oxidatively cleaved with ruthenium tetroxide to yield benzoic acid derivatives of the rings A and B. Flavones, chalcones, and coumarins are degradated by the same method.
    Additional Material: 1 Tab.
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  • 64
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 408-408 
    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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  • 65
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 409-425 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses of Antimicrobial Biscationic 2-(Phenoxyphenyl)indoles and -1-benzofuransTen 2-(phenoxyphenyl)indoles and four 2-(phenoxyphenyl)-1-benzofurans with terminal amidinium or imidazolinium groups were synthesized in respect to growth inhibiting properties.
    Notes: Zehn 2-(phenoxyphenyl)indole und vier 2-(Phenoxyphenyl)-1-benzofurane mit endständigen Amidinium- oder Imidazolinium-Gruppen wurden im Hinblick auf wachstumshemmende Eigenschaften synthetisiert.
    Additional Material: 2 Tab.
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  • 66
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metallporphyrine in polymeren Matrizen, Micellen und Vesikeln, V.  -  5-(1′-Methyl-4,4′-bipyridinium-1-yl)octaethylpophyrin-dichlorid, ein meso- ViologenporphyrinatDer wasserlösliche Zinkkomplex der Titelverbindung wurde durch Thallium(III)-nitrat-Oxidation von Zink-octaethylporphyrinat in Gegenwart von 4,4′-Bipyridin und nachfolgende Behandlung mit Methyliodid und Säure erhalten. Beim Zinkkomplex und beim deprotonierten Dianion wurde im Elektronenspektrum eine 330-nm-Bande beobachtet, die bei der freien Porphyrinbase nicht auftrat. Im diprotonierten Porphyrin-Dikation wurde eine neue langwellige Absorptionsbande bei 750 nm beobachtet, wenn das Viologen-Dikation mit Zink zum Radikal reduziert wurde.  -  Wurde das Methylviologen-Zink-Porphyrinat in Ditetradecylsulfosuccinat-Vesikeln mit negativ geladener Oberfläche gelöst, so reagierte es nicht mit Dithionit. In elektroneutralen Lecithin-Vesikeln wurde es zum Viologen-Radikal reduziert.
    Notes: The water-soluble zinc complex of the title compound was obtained by thallium(III) nitrate oxidation of zinc octaethylporphyrinate in the presence of 4,4′-bipyridine and subsequent treatment with methyl iodide and acid. An absorption band at 330 nm was observed in the electronrich zinc complex and deprotonated dianion which was absent in the spectrum of the free base porphyrin. Another new absorption band at 750 nm was found in the diprotonated porphyrin dication if its bipyridinium substituent was reduced by zinc to the viologen radical.  -  A solution of methylviologen zinc porphyrinate in negatively charged ditetradecylsulfosuccinate vesicles was not reduced by dithionite. In electroneutral lecithin vesicles reduction to the viologen radical was observed.
    Additional Material: 1 Ill.
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  • 67
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 7-Aroyl-1H,7H-s-triazolo (1,3(2H)-diones, a New Class of Compounds from 5-Phenyloxazoles and 4-Phenyl-4H-1,2,4-triazole-3,5-dioneThe 5-aryloxazoles 2a-e and their substituted derivatives 8a-c and 10 react with 4-phenyl-4H-1,2,4-triazole-3,5-dione (3) to give the new 7-aroyl-1H,7H-s-triazolo[1,2-a]- s-triazole-1,3(2H)-diones 5a-e, 9a-c, and 11. The structure is deduced from the 13C NMR spectroscopic data of 5b, 9a, and 11. The mechanism is shortly discussed.
    Notes: Durch Umsetzung der 5-Aryloxazole 2a-e sowie der substituierten Vertreter 8a-c und 10 mit 4-Phenyl-4H-1,2,4-triazol-3,5-dion (3) lassen sich die neuen 7-Aroyl-1H,7Hs-triazolo[1,2-a]-s- triazol-1,3(2H)-dione 5a-e, 9a-c und 11 herstellen. Die Struktur wird aus den 13C-NMR-spektroskopischen Daten von 5b, 9a und 11 abgeleitet. Der Mechanismus der Bildung wird kurz diskutiert.
    Additional Material: 2 Tab.
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  • 68
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 680-691 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Glycosyl Imidates, 10. - Glycosyl Phosphates from Glycosyl TrichloroacetimidatesThe glucosyl trichloroacetimidates 1a-α,β, 8-α, 11-α, 13-α, 15-α and 17-α directly transfer the glycosyl moiety to phosphoric acid mono- and diesters. The acidity of the phosphoric acid derivatives used was sufficient for the activation of the trichloracetimidates, therefore and additional acidic catalyst was not required. From the β- α-glycosyl phophate and from the α-imidates preferentially β-glycosyl phosphates were obtained. Reaction of dibenzyl phosphate (2a) and cetyl phosphate (2c) with 1-α demonstrated that β/α-anomerization is catalyzed by traces of acid. The glycosyl phosphates 3a-α, 3a-β, 3c-β, 3f-α, 9a-β, and 9c-β were partly or totally deprotected. The structures of the synthesized compounds were assigned by 1H. NMR spectroscopy and by comparison with literature data.
    Notes: Die Glycosyl(trichloracetimidate)1-α,β, 8-α 11-αm 13-α, 15-α und 17-α übertragen den Glycosylrest direkt auf Phosphorsäuremono- und -diester. Die Acidität der eingesetzten Phosphorsäurederivate war für die Aktivierung der Trichloracetimidate ausreichend, so daß kein zusätzlicher Katalysator erforderlich war. Dabei wurden aus dem β-Imidat 1-β α-Glycosylphosphat und uas den α-Imidaten bevorzugt β-Glycosylphosphate erhalten. An der Umsetzung von Phosphorsäuredibenzylester (2a) und Phosphorsäure-cetylester (2c) mit 1-α wurde gezeigt, daß die β/α-Anomerisierung durch Spuren Säure katalysiert wird. Die Glycosylphosphosphate 3a-α, 3a-β - 3c-β, 3f-α, 9a-β und 9c-β wurden teilweise oder ganz entschützt. Die Strukturen der synthetisierten Verbindungen wurden 1H-NMR-spektroskopisch und durch Vergleich mit Literaturdaten gesichert.
    Additional Material: 1 Ill.
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  • 69
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 7-(β-D-Arabinofuranosyl)-2,4-dichloro-7H-pyrrolo[2,3-d] pyrimidine - Synthesis, Selective Displacement of Halogen, and Influence of Glyconic Protecting Groups on the Reactivity of the AglyconeSelective N-7 glycosylation of 2,4-dichloro-7H-pyrrolo[2,3-d]pyrimidine (1a) with the arabinohalogenose 5 has been achieved yielding the β-anomer 7a in 67% yield. Debenzylation with boron trichloride results in the formation of the 2,4-dichloronucleoside 2. The assignment of the position of glycosylation was made on the basis of 13C NMR long-range coupling with the anomeric proton. Nucleophilic displacement on compound 2 results in selective substitution of the halogen in position 4. By applying more vigorous conditions the C-4 as well as the C-2 substituents are replaced. Therefore, 2 represents a common intermediate for the synthesis of ara-7-deazapurine nucleosides. In contrast to 2, nucleophilic substitution at the benzyl-protected precursor 7a is hindered.
    Notes: 2,4-Dichlor-7H-pyrrolo[2,3-d]pyrimidin (1a) wurde mit der Arabinohalogenose 5 selektiv an N-7 glycosyliert und das β-Anomer 7a in 67% Ausbeute erhalten. Debenzylierung mit Bortrichlorid ergibt das 2,4-Dichlornucleosid 2, bei dem die Zuordnung der Glycosylierungsposition durch 13C-NMR-Fernkopplung mit dem Anomerenproton erfolgte. Nucleophile Substituenten, womit sich 2 als gemeinsame Vorstufe für die Synthese von ara-7-Desazapurin-Nucleosiden anbietet. Im Gegensatz freien Nucleosid 2 ist die nucleophile Substitution an der benzylgeschützten Vorstufe 7a stark erschwert.
    Additional Material: 1 Ill.
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  • 70
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Pheromonsynthesen, LXIV.  -  Synthese der enantiomeren des 2-methyl-1,7-dioxaspiro[5.6]dodecans, einer Komponente des flüchtigen Mandibulardrüsensekrets von Andrena haemorrhoa F.Die Synthesen der Titelverbindungen (2R,6S)-1 und (2S,6R)-1 aus (R)- und (S)-β-Hydroxybuttersäureester 3 werden beschrieben. Die Bildung des Spiroacetals 1 aus (R)-9 erfolgt stereoselektiv und liefert nur 1 mit (2R,6S)-Konfiguration. (S)-9 ergab (2S,6R)-1.
    Notes: The syntheses of the title compounds (2R,6S)-1 and (2S,6R)-1 from (R)- and (S)-β-hydroxybutyrate 3 are described. The formation of the spiroacetal 1 from (R)-9 proceeded stereoselectively to give only (2R,6S)-1. Similarly (S)-9 yielded (2S,6R)-1.
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  • 71
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    Liebigs Annalen 1984 (1984), S. 186-190 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reaktionen mit 2-Methyl- und 2-Styryl-4-thiochromonenDiazoalkane reagieren mit 2-Methyl- und 2-Styryl-4-thiochromonen zu 1,3-Dithiolanen 1 und/oder Ethylenen 2-4. Letztere werden mit Thionylchlorid zu den entsprechenden Ketonen gespalten während beim Schmelzen mit Schwefel die entsprechenden Thioketone entstehen. 2-Methyl-und 2-Styryl-4-thiochromone kondensieren mit CH-aciden Verbindungen wie Malononitril und Cyanessigsäure-ethylester zu 5. Oxidation der 2-Methyl- und 2-Styryl-4-thiochromone mit gelbem Quecksilber(II)-oxid oder mit Tetrahalogen-o-benzochinon ergibt die entsprechenden Ketone. Die biologische Aktivität ausgewählter Verbindungen gegenüber Gram-positiven und Gramnegativen Bakterien wurde untersucht.
    Notes: Diazoalkanes react with 2-methyl- and 2-styryl-4-thiochromones to yield the 1,3-dithiolanes 1 and/or ethylenes 2-4. The latter are cleaved with thionyl chloride to give the corresponding ketones, while on fusion with sulfur they afford the corresponding thioketones. By condensation with compounds containing active hydrogen, such as malononitrile and ethyl cyanoacetate, the 2-methyl- and 2-styryl-4-thiochromones yield the compounds 5. Oxidation of 2-methyl- and 2-styryl-4-thiochromones was accomplished by yellow mercury(II) oxide as well as with tetrahalo-o-benzoquinones to give the corresponding ketones. The biological activity of some selected compounds prepared during this work has been tested towards Gram-positive and Gram-negative bacteria.
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  • 72
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    Liebigs Annalen 1984 (1984) 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 73
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    Liebigs Annalen 1984 (1984), S. 199-201 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Contributions to the Chemistry of Tetraketones, II.  -  Reaction of 3,4-Dibenzoyl-2,5-hexanedione with HydroxylamineBy treatment of 3,4-dibenzoyl-2,5-hexanedione (1) with hydroxylamine (pH ≍ 8) 3-benzoyl-1-hydroxy-2-methyl-5-phenyl-1H-pyrrole (2), 1-hydroxy-3,4-bis[(hydroxyimino)(phenyl) methyl]-2,5-dimethyl-1H-pyrrole (3), and dimethyldiphenyl-4,4′-biisoxazoles as a mixture of isomers 4a and 4b were isolated from the reaction mixture. The compounds have been characterized by IR, 1H NMR, and mass spectra.
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  • 74
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 240-249 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: New Germacranolides, Heliangolides, and Elemanolides from Cronquistianthus chachapoyensisThe aerial parts of Cronquistianthus chachapoyensis afforded in addition to some known compounds eight new sesquiterpenelactons, the germacranolide acids 1 and 2 and the closely related elemanolides 5 and 6, the germacranolides 7 and 9 as well as the heliangolides 13 and 15 which only could be isolated as their acetates (8, 10, 14, and 16). The structures were elucidated by spectroscopic methods and some chemical transformations.
    Notes: Die oberirdischen Teile von Cronquistiathus chachapoyensis ergeben neben einigen bekannten Verbindungen acht neue Sesquiterpenlactone, die Germacranolidsäuren 1 und 2 und die nahe verwandten Elemanolide 5 und 6, die Germacranolide 7 und 9 sowie die Heliangolide 13 und 15, die nur als Acetate isoliert werden konnten (8, 10, 14 und 16). Die Strukturen werden durch spektroskopische Methoden und einige chemische Umwandlungen erklärt.
    Additional Material: 3 Tab.
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  • 75
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 250-258 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Epoxycannabinolide and Diterpenes with a New Carbon Skeleton from Villanova titicaensisThe aerial parts of Villanova titicaensis afforded in addition to known compounds the new heliangolide 5 and several diterpenes (11-16) with a so far not observed molecular skeleton which is related to helifulvane. The structures were elucidated by spectroscopic methods and by chemical transformations of the diterpenes. The chemotaxonomy is discussed briefly.
    Notes: Die oberirdischen Teile von Villanova titicaensis ergeben zusätzlich zu bekannten Verbindungen das Heliangolid 5 und mehrere Diterpene (11-16) mit einem bisher nicht beobachteten Kohlenstoffgerüst, das mit dem von Helifulvan verwandt ist. Die Strukturen werden durch spektroskopische Methoden und chemische Umwandlungen der Diterpene geklärt. Die Chemotaxonomie wird kurz diskutiert.
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  • 76
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 319-339 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Dimeric Naphthoquinones, IX.  -  Isodiospyrin and Elliptione.  -  Synthesis of 6,6′-Dimeric Bijuglones by Phenol OxidationOxidative coupling of the naphthol 37a gave the potential natural product 7,7′-dimethyl-6,6′-bijuglone (5) and, in lower yield, isodiospyrin (21). Regiospecific syntheses of 5, elliptinone (10), and 6,6′-bijuglone (45a) were achieved by phenol oxidation of suitable substituted p-chloronaphthols.
    Notes: Durch oxidative Kupplung des Naphthols 37b wurde der potentielle Naturstoff 7,7′-Dimethyl-6,6′-bijuglon (5) und in kleinerer Ausbeute Isodiospyrin (21) erhalten. Regiospezifische Synthesen von 5, Elliptinon (10) und 6,6′-Bijuglon (45a) gelangen durch Phenoloxidation geeignet substituierter p-Chlornaphthole.
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  • 77
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1117-1128 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Konformation von Boc-L-Ala-Aib-L-Ala-OMe im Kristall und in LösungBoc-L-Ala-Aib-L-Ala-OMe (1) kristallisert in der Raumgruppe P21 mit a = 11.732(1), b = 6.013(1), c = 14.195(2) Å, β = 91.76(1)→ und Z = 2(R-Faktor für 3089 Reflexe: 0.047). Das Peptid bildet einen neuen Typ eines β-Turns mit einer sehr langen 4→1-Wasserstoffbrücke (3.621 Å). Diese Aufweitung läßt sich wie bei Ac-L-Ala-Aib-L-Ala-OMe mit der Ausbildung eines zweidimensionalen Netzes von starken intermolekularen Wasserstoffbrücken in der bc-Ebene erklären. Temperatur- und Lösungsmittel-abhängige 1H- und 13C-NMR zeigen eine Wasserstoffbrücke von Boc-CO zu NH-3Ala in Lösung, E/Z-Isomerie der Boc-Urethanbindung und eine große magnetische Nichtäquivalenz der beiden geminalen Aib-Methylgruppen. Die ungewöhnliche Konformation von 1 spiegelt sich auch im CD-Spektrum wider, das sich von den meisten Aib-Tripeptiden unterscheidet.
    Notes: Boc-L-Ala-Aib-L-OMe (1) crystallizes in the space group P21 with a = 11.732(1), b = 6.013(1), c = 14.195(2) Å, β = 91.76(1)→, and Z = 2(R value for 3089 reflexions: 0.047). The peptide adopts a new type of β-turn with a very wide 4→1 hydrogen bond distance of 3.621 Å. As for Ac-L-Ala-Aib-L-Ala-Me this distortion can be attributed to strong intermolecular hydrogen bonds forming a two-dimensional network in the bc plane. Temperature and solvent dependent 1H and 13C NMR reveal a hydrogen bond from Boc-CO to NH-3Ala in solution, E/Z isomerism of the Boc urethane bond, and a large magnetic nonequivalence of the two geminal Aib methyl groups. The unusual conformation of 1 is reflected also in its CD spectrum, which differs from most of comparable Aib containing tripeptides.
    Additional Material: 8 Ill.
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  • 78
    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 Alcohols, XVII. - Stereoselective Synthesis of Optically Active α-Multistriatin, the Attractant of the Smaller European Elm Bark Beetle, Scolytus MultistriatusChiral epoxyalcohol (ent-7) and the diethylalkynylalane 9 gave diastereoselectively the diol 10. This was transformed by standard operations into the alcohol 13 and ultimately into (+)-α-multistriatin (ent-1) of 83% isomeric purity.
    Notes: Aus dem chiralen Epoxyalkohol (ent-7) und dem Diethylalkinylalan 9 erhielt man diastereoselektiv das Diol 10. Daraus wurden durch Standardoperationen der Alkohol 13 und weiter (+)-α-Multistriatin (ent-1) von 83% Isomerenreinheit dargestellt.
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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: Structures of the 1:1 Adducts of Aryl Isocyanides to 4-Benzoyl-5-phenylfuran-23-dione and Their Products with Nucleophiles. - Novel Rearrangements of 5,5-Disubstituted 4-Methylenefuran-2,3-dionesThe structures of the previously reported 1:1 adducts of the furan-2,3-dione 8 and aryl isocyanides 2 and their products with nucleophiles are reassigned with the aid of X-ray diffraction, carbon-13 NMR, and mass spectra. Accordingly, the 1:1 adducts of 8 and 2 posses the furo[2,3-b] furan-2,3-dione structure 14. In the reaction of the furo[2,3-b]furan-2,3-diones 14a, b with alcohols, phenol, or carboxylic acids the O-6-C-6a bond is opened affording the furan-2,3-diones 16-21. The Phenol product 19b (C31H23NO5) crystallizes monoclinically in the space group C2/c with eight molecules per cell. On N-acetylation of the butanol products 18 a rearrangement via acyclic intermediates occurs producing the furan-2,3-diones 22. The intermediate butoxy compound 22b is solvolyzed in methanol yielding the methoxy compound 23b. Hydrolysis of the rearranged acetylation products 22a, b and of the non-rearranged acetic acid product 20b as well as attempts to acetylate the nitrogen atom of the alcohol products 16a, 17a, of the phenol product 19a, and of the carboxylic acid products 20a,21a afforded the stable pyrrole-2,5-diones 26a and b, respectively, with concomittant decarboxylation. The pyrroledione 26b (C26H21NO4) crystallizes monoclinically in the space group p21/a with four molecules per cell. The furo 2,3-bfuran-2,3-diones 14 react with 2- and 4-nitroaniline under opening of the O-6-C-6a bond and subsequent furandione-furandione rearrangement affording 28a,b and 28c,d, respectively. The furan-2,3-dione 28b (C31H23N3O6) crystallizes triclinically in the space group P1 with two molecules per cell. In contrast to hydroxy compounds and nitroanilines, aniline and water attack the lactone group of 14a,b yielding as the final products the pyrrole derivatives 31a,b and the furan derivatives 32a,b, respectively. The mechanisms of the various rearrangements and the principle of the furanone-furanedione isomerization are discussed.
    Notes: Die Strukturen bereits früher beschriebener 1:1-Addukte aus dem Furan-2,3-dion 8 und Arylisocyaniden 2 sowie ihrer Produkte mit Nucleophilen werden mit Hilfe von Röntgenstrukturbestimmungen, 13C-NMR- und Massenspektren berichtigt. Demgemäß kommt den 1:1-Addukten aus 8 und 2 die Furo[2,3-d]furan-2,3-dion-Struktur 14 zu. Die Furo[2,3-d]furan-2,3-dione 14a, b reagieren mit Alkoholen, Phenol oder Carbonsäuren unter Öffnung der O-6-C-6a-Bindung zu den Furan-2,3-dionen 16-21. Das Phenolprodukt 19b (C31H23NO5) kristallisiert monoklin in der Raumgruppe C2/c mit acht Molekülen in der Elementarzelle. Bei der N-Acetylierung der Butanolprodukte 18 tritt eine Gerüstumlagerung via acyclische Zwischenstufen zu den Furan-2,3-dionen 22 ein. Die intermediäre Butoxyverbindung 22b wird in Methanol zur Methoxyverbindung 23b solvolysiert. Sowohl Hydrolyse der umgelagerten Acetylierungsprodukte 22a,b und des nicht umgelagerten Essigsäureprodukts 20b als auch Versuche zur N-Acetylierung der Alkoholprodukte 16a,17a, des Phenolprodukts 19a und der Carbonsäureprodukte 20a,21a liefern unter Decarboxylierung die stabilen Pyrrol-2,5-dione 26a bzw. b. Das Pyrroldion 26b(C26H21NO4) kristallisiert monoklin in der Raumgruppe P21/a mit vier Molekülen in der Elementarzelle. Die Furo[2,3-b]furan-2,3-dione 14 reagieren mit 2- und 4-Nitroanilin unter Öffnung der O-6-C-6a-Bindung und anschließender Furandion-Furandion-Umlagerung zu 28a,b bzw. 28c,d. Das Furan-2,3-dion 28b (C31H23N3O6) kristallisiert triklin in der Raumgruppe P1 mit zwei Molekülen in der Elementarzelle. Im Gegensatz zu Hydroxyverbindungen und Nitroanilinen greifen Anilin und Wasser an der Lactongruppe von 14a,b an, wobei letztlich die Pyrrolderivate 31a,b bzw. die Furanderivate 32a,b entstehen. Die Mechanismen der verschiedenen Umlagerungen und das Prinzip der Furandion-Furandion-Isomerisierung werden diskutiert.
    Additional Material: 4 Ill.
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  • 80
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1308-1318 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Application of N-Tritylamino Acid 1-Benzotriazolyl Esters in Peptide SynthesisThe application of N-tritylamino acid 1-benzotriazolyl esters 2 in peptide synthesis is investigated using as model compounds leucine-enkephalin (18) and leucine-enkephalinamide (19). The reactions are performed in solution and on the surface of solids. New spectrophotometric methods, based on the facile cleavage of the N-trityl group and on the measurement of the absorbance of the released triphenylmethanol, are used to monitor the coupling steps and to determine the free amino groups on the solid carrier.
    Notes: Der synthetische Nutzen von N-Tritylaminosäure-(1-benzotriazolylestern) 2 beim Aufbau von Peptiden-wird am Beispiel von Leucin-Enkephalin (18) und Leucin-Enkephalinamid (19) untersucht. Die Synthese wird in Lösung und an Festkörpern durchgeführt. Neue spektrophotometrische Meßmethoden, die auf der leichten Abspaltbarkeit der N-Trityl-Gruppe basieren und bei denen die Absorption des frei gewordenen Triphenylmethanols bestimmt wird, dienen zur Verfolgung der Verknüpfungsschritte und zur Bestimmung der freien Aminogruppen am Festkörper.
    Additional Material: 2 Ill.
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  • 81
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    Liebigs Annalen 1984 (1984), S. 1319-1331 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Piperine - an Example of Individually Different (Polymorph) Metalbolism of an Omnipresent Nutrition ComponentSearching for the origin of components disturbing human urinary steroid profiles, two previously unknown compounds were detected: 5-(3,4-dihydroxyphenyl)valeric acid piperidide (17) and its in position 4 of the piperidine ring hydroxyxlated derivative 18. If nutrition free of pepper is consumed, these peaks disappear in the profiles, if piperine (21) is consumed the peaks appear again. Approximately 15 percent of the tested persons are not able to produce these metabolites. They excrete in their urine 5-(3,4-dihydroxyphenyl)-2,4-pentadienoic acid piperidide (22) if they consume pepper. Such an individually different metabolism of a common and nearly omnipresent nutrition component was previously not known to our knowledge.
    Notes: Auf der Suche nach der Herkunft von Störkomponenten in humanen Harn-Steroid-Profilen fanden wir zwei bisher unbekannte Verbindungen: 5-(3,4-Dihydroxyphenyl)valeriansäure-piperidid (17) und sein in Stellung 4 des Piperidinringes hydroxyliertes Derivat 18. Wird pfefferfreie Nahrung eingenommen, verschwinden diese Peaks in den Profilen, bei Einnahme von Piperin (21) treten sie wieder auf. Etwa 15% der untersuchten Personen sind nicht in der Lage, 17 und 18 zu bilden. Sie scheiden im Harn bei Pfefferkonsum 5-(3,4-Dihydroxyphenyl)-2,4-pentadiensäure-piperidid (22) aus. Eine derartige individuell unterschiedliche (polymorphe) Metabolisierung einer nahezu allgegenwärtigen Nahrungskomponente wurde unseres Wissens bisher noch nicht gefunden.
    Additional Material: 5 Ill.
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  • 82
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1358-1366 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cycloadditions, III. - Reactions of Ynamines with SilylketenesThe ynamines 1a-e react with the silyl aldoketenes 2a and b in a normal way under [2+2] cycloaddition to give the allenecarboxamides 6 and in one case a cyclobutenone derivative. The presence of the silyl group in the adducts gives rise to 1,3-migrations of the geminal hydrogen atom, which transform the primarily formed cyclobutenone 4d into the isolated derivative 7d and a part of the allenes 6 into the isomeric silylacetylenes 8. The tricyclic lactam 10 is formed in low yield during the distillation of 4-(dimethylphenylsilyl)-N,2-dimethyl-2,3-butadienanilide (6c); its formation is caused by an intramolecular Diels-Alder reaction between the aniline nucleus and the second allenic double bond.
    Notes: Die Inamine 1a-e reagieren mit den Silylaldoketenen 2a und b in der üblichen Weise unter [2+2]-Cycloaddition zu den Allencarboxamiden 6 und in einem Fall zu einen. Cyclobutenonderivat. Verursacht durch die Anwesenheit der Silylgruppe in den Addukten, treten 1,3-Verschiebungen des zur Silylgruppe geminal-ständigen Wasserstoffatoms auf, die das Cyclobutenon 4d in das isolierte Derivat 7d und ein Teil der Allene in die isomeren Silylacetylene 8 umwandeln. Bei der Destillation von 4-(Dimethylphenylsilyl)-N,2-dimethyl-2,3-butadienanilid (6c) wird in geringer Ausbeute das tricyclische Lactam 10 isoliert, dessen Bildung durch eine intramolekulare Diels-Alder-Reaktion zwischen dem Anilinkern und der zweiten allenischen Doppelbindung verursacht wird.
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  • 83
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1386-1389 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthese und Reaktivität von 131,132,171,172-TetradehydrodeuteroporphyrinDie 13,17-Propionsäure-methylester-Seitenketten des Deuteroporphyrin-dimethylesters (1a) wurden mit Phenylselenobromid zu 1b dehydriert. Die 12,18-Methylgruppen tauschten in Deuterio-methanol mit Natriummethoxid Wasserstoff gegen Deuterium aus.
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  • 84
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1395-1397 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Note on the Synthesis of 1,2-Benzoxathiine 2,2-Dioxide Derivatives from 3-Chromonesulfonic AcidStarting with 3-chromonesulfonic acid (1) the 1,2-benzoxathiine 2,2-dioxide derivatives 7 and 8 have been obtained by ring transformation of the sulfonyl chloride 4.
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  • 85
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1399-1407 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Albomycins, I. - Enzymatic Cleavage of the Deferri Form of the Albomycins δ1, δ2Enzymatic hydrolyses of albomycin δ2 (1a) were attempted with 23 enzymes or enzyme mixtures. 1a and albomycin δ1 (1b) were cleaved with leucine aminopeptidase (microsomal, hog kidney), subtilisin, aminoacylase I, β-lactamase, proteinase K, and pronase E to give the serine-containing nucleosides 3a and b. With microsomal leucine aminopeptidase a further reaction yields the serine-free nucleosides 4a and b. The hydroxamic acid 6 was also isolated.
    Notes: Enzymatische Hydrolyseversuche an Albomycin δ2 (1a) werden mit 23 Enzymen oder Enzymgemischen durchgeführt. 1a und Albomycin δ1 (1b) werden mit Leucinaminopeptidase (mikrosomal, Schweineniere), Subtilisin, Aminoacylase I, β-Lactamase, Proteinase K und Pronase E zu den serinhaltigen Nucleosiden 3a und b gespalten. Mit der mikrosomalen Leucinaminopeptidase erfolgt eine Weiterreaktion zu den serinfreien Nucleosiden 4a und b. Die Hydroxamsäure 6 konnte ebenfalls rein isoliert werden.
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  • 86
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    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1424-1433 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Albomycins, III. - Synthesis of N5-Acetyl-N5 -hydroxy-L-ornithine from L-Glutamic AcidThe hydroxamic acid N5-acetyl-N5-hydroxy-L-ornithine (2a) is of crucial importance for the biological activity of the siderochromes. L-Glutamic acid (3), a cheap and readily available starting material, can be modified selectively at the γ-carboxylic acid function after protection of the α-amino acid group. An orthogonal protecting group pattern is the precondition for selective cleavages to partially protected amino acids and to the hydroxamic acid 2a.
    Notes: Die Hydroxamsäure N5-Acetyl-N5-hydroxy-L-ornithin (2a) besitzt entscheidende Bedeutung für die biologische Wirkung der Siderochrome. Die preiswerte L-Glutaminsäure (3) kann nach Schutz der α-Aminosäuregruppierung selektiv an der γ-Carbonsäurefunktion derivatisiert werden. Ein orthogonales Schutzgruppenmuster ist Voraussetzung für selektive Spaltungen zu partial geschützten Aminosäuren und zur Hydroxamsäure 2a.
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  • 87
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of rac-Stercobilin IX α with the Configuration of the Natural Product and of Some Urobilins, Half-stercobilins, and Stercobilins with Unequivocal Constitution and configurationFor the first time a stercobilin IX α (12) with the configuration of the natural product and some half-stercobilins, e. g. 9, with the same configuration were synthesized. In addition some bile pigments of the urobilin - half-stercobilin and stercobilin type with determined configuration were prepared.
    Notes: Erstmals wurden ein Stercobilin IX α (12) mit der relativen Konfiguration des Naturproduktes und eine Reihe von Halbstercobilinen, z. B. 9, mit der gleichen Konfiguration dargestellt. Außerdem wurden einige Gallenfarbstoffe der Urobilin - Halbstercobilin- und Stercobilin-Reihe mit definierter Konfiguration synthetisiert.
    Additional Material: 2 Ill.
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  • 88
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    Liebigs Annalen 1984 (1984), S. 1494-1503 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses of α-C-Functionalized N-Nitrodialkylamines: Esters of [(Alkyl)(nitro)amino]methanol and 1-[(Alkyl)(nitro)amino]ethanolThe α-acetoxynitramines 5 and 6 - important derivatives for studying the biological properties of N-nitrodialkylamines 4 - have been synthesized, and the stability of the ester bond has been investigated. The reaction of N-nitroalkylamines 7 with 1-halogenoethyl acetates 9, thought to afford 6, yielded the diazene N-oxides 10 as the main products.
    Notes: Die für das Studium des biologischen Verhaltens von N-Nitrodialkylaminen 4 wichtigen α-Acetoxynitramine 5 und 6 wurden synthetisiert, und die Stabilität der Esterbindung wurde untersucht. Beim Versuch, 6 aus N-Nitroalkylaminen 7 und (1-Halogenethyl)acetaten 9 darzustellen, wurden die Diazen-N-oxide 10 als Hauptprodukte erhalten.
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  • 89
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cycloaddition with Unsaturated Carbohydrates, III. - The Stereochemistry of the Diels-Alder Reaction with Hex-2-enopyranoside and Hex-2-enopyranosid-4-ulosesThe diene addition to ethyl 4,6-di-O-acetyl-2,3-dideoxy-α-D-erythro-hex-2-enopyranoside (1) formed only the α-D-manno adduct 2. With alkyl 2,3-dideoxy-α(β)-D-glycero-hex-2-enopyranosid-4-uloses 3a and b, the L- and D-erythro adducts 4a, b and 5a, b, respectively, are prepared. They tautomerize to give the D- and L-threo stereoisomers 6a, b, and 7b, respectively. The benzo-[2,3]hexopyranosid-4-uloses were reduced stereoselectively by NaBH4 to hexopyranosides. The structure of methyl 2,3-dideoxy-1′,2′,3′,6′-tetrahydro-4′,5′-dimethyl-β-D-glycero-D-threo-benzo-[2,3]hexopyranosid-4-ulose (6b) was determined by an X-ray analysis.
    Notes: Die Dien-Addition an Ethyl-4,6-di-O-acetyl-2,3-didesoxy-α-D-erythro-hex-2-enopyranosid (1) führt ausschließlich zum α-D-manno-Addukt 2. Mit den Alkyl-2,3-didesoxy-α(β)-D-glycero-hex-2-enopyranosid-4-ulosen 3a und b entstehen je ein L- und D-erythro-Addukt 4a, b bzw. 5a, b. Diese tautomerisieren zu den D- und L-threo-Stereoisomeren 6a, b und 7b. Die Benzo[2,3]hexo-pyranosid-4-ulosen wurden mit NaBH4 stereoselektiv zu Hexopyranosiden reduziert. Die Struktur von Methyl-2,3-didesoxy-1′,2′,3′,6′-tetrahydro-4′,5′-dimethyl-β-D-glycero-D-threo-benzo-[2,3]hexopyranosid-4-ulose (6b) wurde durch Röntgenstrukturanalyse bestimmt.
    Additional Material: 1 Ill.
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  • 90
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1563-1576 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Oxidative Deblockierung der 4-Methoxybenzylthioether-Schutzgruppe: Anwendung zur gezielten Synthese von Poly-Cystinyl-PeptidenDie 4-Methoxybenzylthioether-Schutzgruppe läßt sich effektiv in hoher Ausbeute durch Oxidation mit dem homogenen Elektronentransferagens Tris(4-bromphenyl)ammoniumyl (2.⊕) unter Bildung des Disulfids deblockieren. S-(4-Methoxybenzyl)cysteinderivate wie 9 lassen sich auf diese Weise in 90% Ausbeute in die entsprechenden Cystinderivate überführen. Viele N- und Carboxy-Schutzgruppen wie die Boc- und Z-Gruppierung sowie die tert-Butyl- oder Benzylester-Funktionen sind unter den Spaltungsbedingungen stabil. Auf der anderen Seite bleibt die 4-Methoxybenzylthioether-Schutzgruppe völlig unbeeinflußt von den Bedingungen der oxidativen Spaltung der S-Tritylfunktion durch Iod oder durch Rhodanolyse. Diese Verhalten eröffnet neue Möglichkeiten für die gezielte Synthese von Cystinylpeptiden mit mehr als einer intra- oder interchenaren Disulfid-Brücke. Über die Anwendung der neuen Methode zur Synthese eines Cystinylpeptids mit einer intrachenaren S—S-Brücke und eines doppelsträngigen Bis(cystinyl)peptids wird berichtet.
    Notes: The 4-methoxybenzyl thioether protecting group is deblocked efficiently by oxidation with the homogeneous electron transfer agent tris(4-bromophenyl)ammoniumyl (2.⊕) leading to the disulfide in high yields. S-(4-methoxybenzyl)cysteine derivatives like 9 in this way can be transformed into the corresponding cystine derivatives like 10 in 90% yield. Many N and carboxy protecting groups like the Boc and Z group and tert-butyl or benzyl ester functions are stable under the cleavage conditions. On the other hand the 4-methoxybenzyl thioether protecting group is totally unaffected by the conditions for oxidative deblocking of the S-trityl functions by either iodine or rhodanolysis. This opens up new opportunities for the directed synthesis of cystinyl peptides with more than one intra- or interchain disulfide bridge. Application of the new method to the synthesis of a cystine peptide with one intrachain S—S-bridge and a double-chain biscystinyl peptide is reported.
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  • 91
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Enolic Sugar Derivatives, XVI. - Synthesis of a Diastereotopic Proton Probe [(Z-3,7-Anhydro-1,2-dideoxy-D-gluco-oct-2-enitol] for α- and β-D-GlucosylasesFor the elucidation of the stereochemistry in glucosylase-catalyzed proton addition reactions Z)-3,7-anhydro-1,2-dideoxy-D-gluco-oct-2-enitol (1) was synthesized. Starting material for the multistep synthesis is 3,4,5,7-tetra-O-acetyl-2,6-anhydro-1-C-(1,3-diphenyl-2-imidazolidinyl)-D-glycero-D-gulo-heptose (4), which after chain elongation by Grignard reaction yields the separable diastereomeric alcohols 3,7-anhydro-4,5,6,8-tetra-O-benzyl-1-desoxy-D-erythro-L-galacto-octitol (14) and -L-talo-octitol (15). After O tosylation of the hydroxy group in position 2 and replacement of the O benzyl by O acetyl groups in compounds 14 and 15, the resulting isomeric products were subjected to reaction with sodium benzoate. One isomer, 3,7-anhydro-1-deoxy-4,5,6,8-tetra-O-acetyl-2-O-(p-tolylsulfonyl)-D-erythro-L-galacto-octitol (16), yields the title compound 1 in reasonable quantity in addition to the nucleophilic substitution product 19. Several glucosylases catalyze the addition of water to the double bond of 1.
    Notes: Für die Untersuchung der Stereochemie enzymatischer Protonierungsschritte bei Glucosylasen wurde Z)-3,7-Anhydro-1,2-didesoxy-D-gluco-oct-2-enitol (1) synthetisiert. Edukt für die mehrstufige Synthese ist die 3,4,5,7-Tetra-O-acetyl-2,6-anhydro-1-C-(1,3-diphenyl-2-imidazolidinyl)-D-glycero-D-gulo-heptose (4), die nach Kettenverlängerung durch Grignard-Reaktion die diastereomeren Alkohole 3,7-Anhydro-4,5,6,8-tetra-O-benzyl-1-desoxy-D-erythro-L-galacto-octitol (14) und -L-talo-octitol (15) liefert. Letztere werden nach O-Tosylierung der 2-Hydroxygruppe und Austausch der O-Benzylschutzgruppen gegen O-Acetylgruppen der Reaktion mit Natriumbenzoat unterworfen. 3,7-Anhydro-1-desoxy-4,5,6,8-tetra-O-acetyl-2-O-(p-tolylsulfonyl)-D-erythro-L-galacto-octitol (16) liefert neben dem Substitutionsprodukt 19 in nennenswerter Ausbeute 1. Zahlreiche Glucosylasen katalysieren die Umsetzung von 1 zu Additionsprodukten.
    Additional Material: 1 Tab.
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  • 92
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reaktionen von Uracilen, 4. - Einige Aspekte der Chemie von Pyrido[2,3-d]pyrimidinen. Ein neues s-Triazolo[4′, 3′ : 1,6]pyrido[2,3-d]pyrimidinAus dem neuen 7-Hydrazino-1,3-dimethylpyrido[2,3-d]pyrimidin-2,4(1H,3H)-dion (2) werden die Hydrazinderivate 3, 5, 6, 8 und 10 dargestellt. Aus 3 wird das s-Triazolo[4′,3′: 1,6]pyrido-[2,3-d]pyrimidin 4 erhalten, während Ringschlußversuche von 5, 6 und 8 erfolglos blieben. Zwei 6-substituierte Pyrido[2,3-d]pyrimidine werden hergestellt, 13a aus 11 und Benzoylacetonitril, 16 durch Photo-Fries-Umlagerung von 15. In CDCl3-Lösung und in fester Phase überwiegt die tautomere OH-Form 161.
    Notes: The novel 7-hydrazino-1,3-dimethylpyrido[2,3-d]pyrimidine-2,4(1H,3H)-dione (2) gives the hydrazine derivatives 3, 5, 6, 8, and 10. The s-triazolo[4′,3′: 1,6]pyrido[2,3-d]pyrimidine 4 is prepared from 3, while the attempted cyclizations of 5, 6, and 8 failed. Two pyrido[2,3-d]pyrimidines substituted in position 6 are prepared, 13a from 11 and benzoylacetonitrile, 16 by photo-Fries rearrangement of 15. In CDCl3 solution and in solid phase predominates the tautomeric OH form 161.
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  • 93
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1662-1671 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: One-Step Stereoselective Syntheses of C-Branched α-Deoxycyclitols from 1,6-Anhydrohexopyranoses1,6-Anhydro-3,4-O-isopropylidene-β-D-galactopyranose (1) reacts with n-butyllithium to give exclusively 1D-1-C-butyl-2,3-O-isopropylidene-1,2,3,5/4-cyclohexanepentol (2a). 1,6-Anhydro-2,3-O-isopropylidene-β-D-mannopyranose (7) gives 1L-1-C-butyl-2,3-O-isopropylidene-1,2,3/4,5-cyclohexanepentol (8a) and 1L-1-C-butyl-3,4-O-isopropylidene-1,2,5/3,4-cyclohexanpentol(9a) as a by-product. Analogous reactions with methyllithium yield the corresponding C-methyl-branched deoxyinositols 2b, 4, 8b, and 9b.
    Notes: 1,6-Anhydro-3,4-O-isopropyliden-β-D-galactopyranose (1) reagiert mit n-Butyllithium ausschließlich zu 1D-1-C-Butyl-2,3-O-isopropyliden-1,2,3,5/4-cyclohexanpentol (2a). 1,6-Anhydro-2,3-O-isopropyliden-β-D-mannopyranose (7) ergibt mit n-Butyllithium 1L-5-C-Butyl-2,3-O-isopropyliden-1,2,3/4,5-cyclohexanpentol (8a) und als Nebenprodukt 1L-1-C-Butyl-3,4-O-isopropyliden-1,2,5/3,4-cyclohexanepentol (9a). Analoge Reaktionen mit Methyllithium führen zu den entsprechenden C-Methyl-verzweigten Desoxyinositolen 2b, 4, 8b und 9b.
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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: 4-Imidazolidinones from Nitrones and Isocyanides. - Molecular Structure of 5-tert-Butyl-1,2,2-trimethyl-3(2,4,6-tribromophenyl)-4-imidazolidinoneCertain reactions of nitrone 1 and isocyanide 2, in the presence of ether - boron trifluoride, afford 4-imidazolidinones 4 which have been shown to be ring expansion products of the 4-imino-1,2-oxazetidines 3. 1,2,4-Oxadiazolidin-5-ones 5 (rather than 3 or 4) have been obtained from two further reactions of 1 with 2. - The constitution of 4 has been established by an X-ray analysis of the title compound 4c.
    Notes: Aus bestimmten Kombinationen von Nitron 1 und Isocyanid 2 erhält man in Gegenwart von Ether - Bortrifluorid nicht 4-Imino-1,2-oxazetidine 3, sondern deren Ringerweiterungsprodukte, die 4-Imidazolidinone 4. In zwei weiteren Fällen werden statt 3 oder 4 die 1,2,4-Oxadiazolidin-5-one 5 gefunden. - Die Konstitution 4 wird durch Röntgenstrukturanalyse des im Titel genannten Vertreters 4c bewiesen.
    Additional Material: 1 Ill.
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  • 95
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1702-1710 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of 2-Acyl-3-aminofurans by Thorpe CyclizationThe substituted β-(acylmethoxy)acrylonitriles 2 and 11, obtainable by O-alkylation of β-cyanoketones with halomethyl ketones or by the reaction of α-hydroxymethyl ketones with β-chloro-α-cyanocinnamonitrile are cyclized in the presence of bases to yield 2-acyl-3-aminofurans 3 and 12. The phenacyl and acetonyl esters 5 and 8 of 2-(arylhydrazono)-2-cyanoacetic acid and 2-(anilinomethylene)-2-cyanoacetic acid, respectively, can be cyclized in the presence of triethylamine to form substituted 5-acyl-4-amino-2-furanones 6, 9.
    Notes: Die substituierten β-(Acylmethoxy)acrylnitrile 2 und 11, erhältlich durch O-Alkylierung von β-Cyanketonen mit Halogenmethylketonen oder von α-Hydroxymethylketonen mit β-Chlor-α-cyanzimtsäurenitril, cyclisieren basenkatalysiert zu 2-Acyl-3-aminofuranen 3 und 12. - Phenacyl- und Acetonylester 5 und 8 von 2-(Arylhydrazono)-2-cyanessigsäuren und der 2-(Anilinomethylen)-2-cyanessigsäure cyclisieren in Gegenwart von Triethylamin zu substituierten 5-Acyl-4-amino-2-furanonen 6, 9.
    Additional Material: 2 Tab.
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  • 96
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984) 
    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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  • 97
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1288-1297 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Building Units of Oligosaccharides, LIII. - Synthesis of Trisaccharides Containing 3-Deoxy-D-manno-2-octulosonic Acid (KDO)The disaccharide 9 consisting of two glucosamine units reacts with the pyranosyl bromide of 3-deoxy-D-manno-2-octulosonic acid (KDO) 11 to give the KDO-containing trisaccharides 12 and 14 of which the α-glycosidically linked isomer 12 is the most preponderant product. In a series of deblocking steps the free trisaccharide α-KDO-(2→3)-β-D-GlcNAc-(1→6)-D-GlcNAc 18 could be obtained from 12. The assignment to the α-glycosidic linkage of the KDO unit in 12 has been established by converting 19 into the lactone 20.
    Notes: Durch Umsetzung des aus zwei Glucosamin-Einheiten bestehenden Disaccharides 9 mit dem Pyranosylbromid der 3-Desoxy-D-manno-2-octulosonsäure (KDO) 11 sind die KDO-haltigen Trisaccharide 12 und 14 zu erhalten, von denen das α-glycosidisch verknüpfte Produkt 12 sehr stark überwiegt. Durch eine Entblockierungssequenz ist aus 12 das freie Trisaccharid α-KDO-(2→3)-β-D-GlcNAc-(1→6)-D-GlcNAc 18 zu gewinne. Die Zuordnung zur α-glycosidischen Verknüpfung des KDO-Teiles in 12 erfolgte durch Überführung von 19 in das Lacton 20.
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  • 98
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1298-1301 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reaction of Carboxonium -Ions of Cyclic Acetals, VIII. - Synthesis of rac-4,5,6,7-Tetrahydro-3,7-dimethyl-1-benzofuranAcid-catalyzed dehydration of the 4-methylene-1,3-dioxolane 2, β-oxa-γ,δ-enone 4a or 4b leads to rac-4,5,6,7-tetrahydro-3,7-dimethyl-1-benzofuran (9) - an isomer of menthofuran.
    Notes: Durch säurekatalysierte Dehydratisierung des 4-Methylen-1,3-dioxolans 2, des β-Oxa-γ,δ-enons 4a oder 4b entsteht rac-4,5,6,7-Tetrahydro-3,7-dimethyl-1-benzofuran (9) - ein Isomeres des Menthofurans.
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  • 99
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1302-1307 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses of Thiazolo- and [1,3]Thiazino[1,2,4]triazinonesThe syntheses of the thiazolo- and [1,3]thiazino[1,2,4]triazinones 3-6 are described. Preparations of compounds 3 and 5 were achieved regiospecifically by using the compounds 12 and 13.
    Notes: Es werden die Synthesen der Thiazolo- und [1,3]Thiazino[1,2,4]triazinone 3-6 beschrieben. Die Darstellungen der Verbindungen 3 und 5 gelangen regiospezifisch mittels der Verbindungen 12 und 13.
    Additional Material: 5 Tab.
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  • 100
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Albomycins, II. - Absolute Configuration of the Deferri Form of the AlbomycinsChemical and enzymatic hydrolyses afford the degradation products of the albomycins δ2, δ1, and ε (1a - c). The absolute configuration of these degradation products or of there derivatives could be elucidated by the combination of chiroptical, gaschromatographic, and NMR (NOE) spectroscopic methods. N5-Acetyl-N5-hydroxyornithine (4) and serine (3) exist in the L-configuration, while the nucleoside contains the 6-amino-6-deoxy-4-thio-L-glycero-α-L-ido-heptofuranuronic acid. The configuration of this nucleoside could also be established by the X-ray analysis of the sulfoxide 21.
    Notes: Chemische und enzymatische Hydrolysen führen zu Abbauprodukten der Albomycine δ2, δ1 und ε (1a - c). Die absoluten Konfigurationen der Abbauprodukte oder deren Derivate werden durch Kombination chiroptischer, gaschromatographischer und NMR-spektroskopischer (NOE) Methoden abgeleitet. N5-Acetyl-N5-hydroxyornithin (4) und Serin (3) liegen in der L-Konfiguration vor, während das Nucleosid die 6-Amino-6-desoxy-4-thio-L-glycero-α-L-ido-heptofuranuronsäure enthält. Die Konfiguration des Nucleosids wird unabhängig davon durch die Röntgenstrukturanalyse des kristalline Sulfoxids 21 belegt.
    Additional Material: 3 Ill.
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