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  • 1980-1984  (3,407)
  • Organic Chemistry  (3,406)
  • Nuclear reactions
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  • 101
    Electronic Resource
    Electronic Resource
    Darstellung konfigurationsisomerer 3,4-Dihydrobilirubinsäurederivate als Bausteine für Gallenfarbstoffsynthesen (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1441-1453 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of Stereoisomeric 3,4-Dihydrobilirubinic Acid Derivatives as Building Blocks for the Synthesis of Bile PigmentsBy reduction of 5′-carboxyneoxanthobilirubinic acid 3 with sodium amalgam in hot water the stereoisomeric 5′-carboxy-3,4-dihydrobilirubinic acids 9 and 15 are formed and from the isomer 4 the stereoisomers 10 and 16 can be obtained. The stereoisomers can be separated by preparative HPLC on reversed-phase silica gel. The unequivocal determination of the configuration was performed with the aldehydes 11, 12 and 17, 18.
    Notes: Durch Reduktion der 5′-Carboxyneoxanthobilirubinsäure 3 mit Natriumamalgam in heißem Wasser gewinnt man die stereoisomeren 5′-Carboxy-3,4-dihydroneobilirubinsäuren 9 und 15 und aus dem Isomeren 4 entsprechend die Stereoisomeren 10 und 16. Die Stereoisomeren lassen sich durch präparative HPLC an Reversed-Phase-Kieselgel voneinander trennen. Die eindeutige sterische Zuordnung erfolgt bei den Aldehyden 11, 12 und 17, 18.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840807
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  • 102
    Electronic Resource
    Electronic Resource
    Chemie der Nitrosamine, IV. Synthesen von α-C-funktionellen N-Nitrosodialkylaminen: Ester und Ether von 1-[(Alkyl)(nitroso)amino]alkoholen (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1468-1493 
    Details
    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 Nitrosamines, IV. - Syntheses of α-C-Functionalized N-Nitrosodialkylamines:Esters and Ethers of 1-[(Alkyl)(nitroso)amino]alcoholsImines (Schiff's bases) and nitrosyl chloride react to give N-alkyl-1-chloro-N-nitrosoalkylamines 13. Nucleophilic substitution by acetate or p-nitrobenzoate affords the acetates 7 and 9 and p-nitrobenzoates 8 and 10, respectively. The spectroscopic and chemical data of the newly synthesized compounds are discussed.
    Notes: Imine (Schiff-Basen) addieren Nitrosylchlorid unter Bildung von N-Alkyl-1-chlor-N-nitrosoalkyl-aminen 13. Durch nucleophile Substitution mit Acetat oder p-Nitrobenzoat sind daraus die Acetate 7 und 9 sowie die p-Nitrobenzoate 8 und 10 zugänglich. Die spektroskopischen Daten und die chemischen Eigenschaften der neu dargestellten Verbindungen werden diskutiert.
    Additional Material: 9 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840808
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  • 103
    Electronic Resource
    Electronic Resource
    Tetrahydrofuransäuren - eine neue Klasse von Verbindungen des Humanstoffwechsels (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1504-1512 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Tetrahydrofuran Acids - A New Class of Compounds in Human MetabolismA previously unknown acid, tetrahydro-2,5-furandiacetic acid (3,6-epoxyoctanedioic acid) (1a) is excreted in human urine in daily rates in a 3 to 5-mg range. The homologues 2a, 3a, 4a, and 5a were also found, but they occur only in trace amounts.
    Notes: Im Humanurin wird die bisher als Naturstoff unbekannte Tetrahydro-2,5-furandiessigsäure (3,6-Epoxyoctandisäure) (1a) in täglichen Mengen von etwa 3-5 mg ausgeschieden. Höhere Homologe 2a, 3a, 4a und 5a werden ebenfalls gefunden, sie kommen aber nur in Spuren vor.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840810
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  • 104
    Electronic Resource
    Electronic Resource
    1,6-Anhydrofuranosen, XIV Selektive Monotosylierung der 1,6-Anhydro-β-D-mannofuranose (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1591-1596 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 1,6-Anhydrofuranoses, XIV. - Selective Monotosylation of 1,6-Anhydro-β-D-mannofuranoseMonotosylation of 1,6-anhydro-β-D-mannofuranose (1) with p-toluenesulfonyl chloride in pyridine gives the 5-O-tosylate 2a in high yield (79%). As by-products of the reaction small amounts of the 3-O-monotosylate 3a (0.4%) as well as the 2,5- and 3,5-di-O-tosylates 4a (3.5%) and 5a (1.2%), respectively, are isolated. Product identification was achieved by 1H NMR spectroscopy in comparison with the data for the acetates 2b, 3b, 4b, and 5b. Observed selectivities are rationalized by concerning steric and electronic effects.
    Notes: Die Monotosylierung der 1,6-Anhydro-β-D-mannofuranose (1) mit Tosylchlorid in Pyridin liefert hochselektiv das 5-O-Tosylat 2a (79%). Daneben konnten in geringer Menge das 3-O-Monotosylat 3a (0.4%) sowie die 2,5- und 3,5-Di-O-tosylate 4a (3.5%) bzw. 5a (1.2%) isoliert werden. Die Identifizierung der Produkte erfolgte durch 1H-NMR-Spektroskopie unter Berücksichtigung der Daten für die Acetate 2b, 3b, 4b und 5b. Die beobachteten Selektivitäten werden unter Beachtung elektronischer und sterischer Faktoren interpretiert.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840907
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  • 105
    Electronic Resource
    Electronic Resource
    Synthesen mesitylsubstituierter Azulene (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1605-1615 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese of Mesityl-substituted AzulenesThe five position isomer mesityl-substituted azulenes 1-5 have been prepared for the first time. 1- and 5-mesitylazulene (1 and 4) have been obtained by addition of mesityl-Li to appropriate ketonic precursors followed by dehydration and dehydrogenation with sulfur. 2- and 6-mesitylazulene (2 and 5) have been prepared by Hafner syntheses from correspondingly substituted precursors, and 4-mesitylazulene (3) was synthesized via nucleophilic addition of mesityl-Li to azulene. The physical properties as well as electronic spectra are compared and discussed.
    Notes: Die fünf stellungsisomeren mesitylsubstituierten Azulene 1-5 wurden erstmals dargestellt. 1- und 5-Mesitylazulen (1 und 4) wurden durch Addition von Mesityl-Li an geeignete Ketonvorstufen mit nachfolgender Dehydratisierung und Dehydrierung mit Schwefel erhalten. 2- und 6-Mesitylazulen (2 und 5) wurden durch Hafner-Synthesen aus geeignet mesitylsubstituierten Vorstufen dargestellt, und 4-Mesitylazulen (3) wurde über nucleophile Addition von Mesityllithium an Azulen erhalten. Die physikalischen Eigenschaften und Elektronenspektren dieser Verbindungen werden vergleichend diskutiert.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840909
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  • 106
    Electronic Resource
    Electronic Resource
    Masthead (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984) 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419841001
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  • 107
    Electronic Resource
    Electronic Resource
    Antibiotika aus Basidiomyceten, XX Synthese von Strobilurin A und Revision der Stereochemie der natürlichen Strobilurine (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1616-1625 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Antibiotics from Basidiomycetes, XX. - Synthesis of Strobilurin A and Revision of the Stereochemistry of Natural StrobilurinsCondensation of cinnamaldehyde (5) with 2-oxobutyric acid (6) leads to the (E,E)-keto acid 7 which is converted into (9E)-strobilurin (1a) via methyl ester 9 and Wittig reaction of the latter with (methoxymethylene)triphenylphosphorane. On irradiation 1a undergoes inversion at the double bond in position 9 and yields strobilurin A (1b) which is identical with the natural product. Due to this result the (9Z) stereochemistry has to be assigned to all natural strobilurins 1b-4b, contrary to former formulations. This assignment is further supported by spectral comparison of 1a and 1b as well as by thermal cyclization of 1b to the biphenyl derivative 11. The latter can also be obtained by condensation of methyl 2-(methoxymethylene)acetoacetate (13) with cinnamylidenetriphenylphosphorane (12). Base-catalyzed condensation of 13 yields dimethyl 4-hydroxyisophthalate (14).
    Notes: Kondensation von Zimtaldehyd (5) mit 2-Oxobuttersäure (6) liefert die (E,E)-Ketosäure 7, die nach Überführung in den Methylester 9 und Wittig-Reaktion mit (Methoxymethylen)triphenylphosphoran (9E)-Strobilurin A (1a) ergibt. Inversion der 9-Doppelbindung durch Belichten führt zu Strobilurin A (1b), das mit dem Naturprodukt identisch ist. Danach besitzen alle natürlichen Strobilurine 1b-4b im Gegensatz zu früheren Angaben die (9Z)-Konfiguration. Diese Zuordnung wird durch den spektroskopischen Vergleich von 1a und 1b sowie durch thermische Cyclisierung von 1b zum Biphenyl-Derivat 11 gesichert. 11 kann auch durch Reaktion von 2-(Methoxymethylen)acetessigsäure-methylester (13) mit Cinnamylidentriphenylphosphoran (12) erhalten werden. Kondensation von 13 unter basischen Bedingungen liefert 4-Hydroxyisophthalsäure-dimethylester (14).
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840910
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  • 108
    Electronic Resource
    Electronic Resource
    Chelating Vesicles Made From N,N-Dihexadecyl-1,2-ethanediamine-N′,N′-diacetic Acid (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1634-1640 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chelatisierende Vesikel aus N, N-Dihexadecyl-1,2-ethandiamin-N′,N′-diessigsäureWäßrige Suspensionen von N,N-Dihexadecyl-1,2-ethandiamin-N′,N′-diessigsäure (1d) ergeben bei pH = 3.5 und 9.0 stabile Vesikel, wenn sie mit Ultraschall behandelt werden. Die äußere Vesikeloberfläche chelatisiert Kupfer(II)- und Eisen(III)-Ionen, ohne daß die Vesikel ausfallen.
    Notes: Aqueous suspensions of N,N-Dihexadecyl-1,2-ethanediamine-N′,N′-diacetic acid (1d) give stable vesicles on sonication at pH = 3.5 and 9.0. The outer vesicle surface chelates copper(II) and iron(III) ions without vesicle precipitation.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419841003
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  • 109
    Electronic Resource
    Electronic Resource
    Azolide, 7 Phosphonat- und Phosphatgruppen-Übertragung mit Pyrazoliden (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1641-1652 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Azolides, 7. - Phosphonate and Phosphate Group Transfer with PyrazolidesThe tert-butylammonium-α-diazophosphinates 7 add onto acceptor-substituted acetylenes 8 with formation of N-phosphorylpyrazoles: Primarily formed 3H-pyrazoles 9 undergo spontaneous sigmatropic [1,5] shift of the anionic PO-group to yield 10. α-Diazophosphonates of the same type (12) react by [3 + 2] cycloaddition also with 8, but the subsequent rearrangement reaction finally leads to the C-phosphorylated pyrazoles 11. In contrast to this the same tert-butylammonium α-diazophosphonates 12, when reacted with dimethyl acetylenedicarboxylate (14), prefer formation of the N-phosphorylated pyrazoles 15. - The azolides 10 and 15 transfer their anionic phosphoryl group under mild conditions onto protic nucleophiles. With amines tert-butylammonium amidophosphonates (10a + R1R2NH → 16 + 19) or tert-butylammonium-amidophosphates (15a + R1R2NH → 16 + 21 + 22) are formed; with alcohols 15a yields the phosphates 20.
    Notes: Die tert-Butylammonium-α-diazophosphinate 7 addieren sich an akzeptorsubstituierte Acetylene 8 unter Bildung von N-Phosphorylpyrazolen: Primär gebildete 3H-Pyrazole 9 gehen spontane sigmatrope [1,5]-Verschiebung der anionischen PO-Gruppe zu 10 ein. α-Diazophosphonate des gleichen Typs (12) reagieren zunächst ebenfalls unter [3 + 2]-Cycloaddition mit 8, doch führt die nachfolgende Umlagerung vorzugsweise zu den C-phosphorylierten Pyrazolen 11. Im Gegensatz dazu bevorzugen die gleichen tert-Butylammonium-α-diazophosphonate 12 mit Acetylendicarbonsäure-dimethylester (14) die Bildung der N-phosphorylierten Pyrazole 15. - Die Azolide 10 und 15 übertragen ihre anionische Phosphorylgruppe unter milden Bedingungen auf protische Nucleophile. Mit Aminen werden tert-Butylammonium-amidophosphonate (10a + R1R2NH → 16 + 19) bzw. tert-Butylammonium-amidophosphate (15a + R1R2NH → 16 + 21 + 22) gebildet; mit Alkoholen liefert 15a die Phosphate 20.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419841004
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  • 110
    Electronic Resource
    Electronic Resource
    Die Struktur von Stenothricin - Korrektur eines früheren Strukturvorschlags (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1672-1684 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Structure of Stenothricin - Revision of a Previous Structure AssignmentA deviation from the previously assumed molecular mass was proved by fast-atom bombardment mass-spectrometry for the peptide antibiotic stenothricin. Recent investigations of a partial hydrolyzate revealed the presence of α-ketobutyrylvaline formed by hydrolysis of an α,β-dehydroaminobutyric acid (DH-Abu) moiety. Fragments obtained by partial hydrolysis of stenothricin after catalytic hydrogenation show that the previously identified tripeptide D-aThr-L-Ser-L-Dpr is linked over DH-Abu to the tetrapeptide L-Val-D-Ser-L-Lys-Sar. The carboxy group of Sar is esterified with the hydroxy group of D-aThr. The N-terminus is formed by D-cysteic acid, which is N-acylated by β-ketoacyl residues and is connected to the cyclic octapeptide lactone via the amino group of D-a Thr.
    Notes: Die durch Fast-Atom-Bombardment-Massenspektrometrie gegenüber früheren Annahmen nachgewiesene Abweichung der Molmasse von Stenothricin erforderte eine erneute Untersuchung dieses Peptidantibiotikums. Gegenüber früheren Befunden konnte im Partialhydrolysat zusätzlich α-Ketobutyrylvalin identifiziert werden, das durch Verseifung von α,β-Dehydroaminobuttersäure (DH-Abu) entsteht. Nach katalytischer Hydrierung von Stenothricin durch Partialhydrolyse erhaltene Fragmente zeigen, daß das schon früher identifizierte Tripeptid D-aThr-L-Ser-L-Dprüber DH-Abu an das Tetrapeptid L-Val-D-Ser-L-Lys-Sar gebunden ist. Die Carboxygruppe von Sar ist außerdem mit der Hydroxygruppe von D-aThr verestert. Die durch β-Ketoacylreste N-acylierte D-Cysteinsäure bildet den N-Terminus und ist über die Aminogruppe von D-aThr mit dem Octapeptidlacton verknüpft.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419841007
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  • 111
    Electronic Resource
    Electronic Resource
    Mehrstufige reversible Redoxsysteme, XXXIV. Polyene als vierstufige Redoxsysteme: Synthese und Spektroskopie (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 340-353 
    Details
    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, XXXIV.  -  Polyenes as Four-Step Redox Systems: Synthesis and SpectroscopyThe synthesis of the pentaenes 2.0-4.0 and of the polyenes 2.1-2.4 is described. All alkenes carry rigid, cross-conjugated end groups. The Dienone 6, the polyene aldehydes 18 and 19 as well as the phosphorous ylid 22 serve as crucial intermediates. 1H NMR and UV/VIS spectra of all polyenes are discussed.
    Notes: Es wird die Synthese der Pentaene 2.0-4.0 sowie der Polyene 2.1-2.4 beschrieben. Alle Alkene verfügen über starre, gekreuzt konjugierte Endgruppen. Wichtige Zwischenstufen sind das Dienon 6, die Polyenaldehyde 18 und 19 sowie das Phosphorylid 22. Die 1H-NMR- und UV/VIS-Spektren aller Polyene werden diskutiert.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840215
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  • 112
    Electronic Resource
    Electronic Resource
    Biologisch aktive Glycoside aus Asteroidea, VII. Steroid-Oligoglycoside aus dem Seestern Luidia maculata Müller et Troschel, 2 Die Strukturen von zwei neuen Oligoglycosidsulfaten (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 296-305 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Biologically Active Glycosides from Asteroidea, VII.  -  Steroid Oligoglycosides from the Starfish Luidia maculata Müller et Troschel, 2.  -  The Structures of Two New Oligoglycoside SulfatesFrom the water extract of the whole bodies of Luidia maculata Müller et Troschel two further oligoglycoside sulfates could be isolated after separations on Amberlite XAD-2, droplet counter current chromatography, and column chromatography on silica gel, Sephadex LH-20, and RP-8. The structures of these two glycosides were elucidated by chemical and spectroscopic means to be the monosodium salt of 6α-[(O-β-D-fucopyranosyl-(1 → 2)-O-β-D-quinovopyranosyl-(1 → 4)-O-[β-D-quinovopyranosyl-(1 → 2)]-O-β-D-quinovopyranosyl-(1 → 3)-β-D-glucopyranosyl)oxy]-3β-(sulfooxy)-5α-cholesta-9(11),24-dien-23-one (1) and the monosodium salt of 6α-[(O-β-D-fucopyranosyl-(1 → 2)-O-β-D-quinovopyranosyl-(1 → 4)-O-[β-D-quinovopyranosyl-(1 → 2)]-O-β-D-quinovopyranosyl-(1 → 3)-β-D-glucopyranosyl)oxy]-3β-(sulfooxy)-5α-cholest-9(11)-en-23-one (2).
    Notes: Aus dem wäßrigen Extrakt der ganzen Seesterne Luidia maculata Müller et Troschel konnten nach Trennungen an Amberlite XAD-2, “Droplet-counter-current”-Chromatographie, sowie Chromatographie an Kieselgel, Sephadex LH-20 und RP-8 zwei weitere Oligoglycosidsulfate isoliert werden, deren Strukturen mittels chemischer und spektroskopischer Methoden als Mononatriumsalz von 6α-[(O-β-D-Fucopyranosyl-(1 → 2)-O-β-D-chinovopyranosyl-(1 → 4)-O-[β-D-chinovopyranosyl-(1 → 2)]-O-β-D-chinovopyranosyl-(1 → 3)-β-D-glucopyranosyl)oxyl]-3β-(sulfooxy)-5α-cholesta-9(11), 24-dien-23-on (1) und als Mononatriumsalz von 6α-[(O-β-D-Fucopyranosyl-(1 → 2)-O-β-D-chinovopyranosyl-(1 → 4)-O-[β-D-chinovopyranosyl-(1 → 2)]-O-β-D-chinovopyranosyl-(1 → 3)-β-D-glucopyranosyl)oxy]-3β-(sulfooxy)-5α-cholest-9(11)-en-23-on (2) ermittelt wurden.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840212
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  • 113
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    Electronic Resource
    Borkomplexe von Malonsäureamiden und Malonsäureamidinen (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 370-380 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Boron Complexes of Malonamides and MalonamidinesN,N,N′,N′-Tetramethylmalonamide (4) reacts with triethyloxonium tetrafluoroborate in boiling tetrachloroethane or with diethyl ether  -  boron trifluoride at room temperature to form the tetrafluoroborate 6a which was deprotonated with triethylamine to give 4,6-bis(dimethylamino)-2,2-difluoro-3-oxa-1-oxonia-2-borata-4,6-cyclohexadiene (7). With 4 and boron trichloride in CCl4 the neutral complex 9 is obtained, in CH2Cl2 the chelate complex 10. Similar to diethyl ether  -  boron trifluoride (2-aminoethoxy)diphenylborane (12) and triethylborane (15) condense with 4 to yield the salts 13 and 17, respectively, and the neutral complexes 14 and 16, respectively. N,N,N″,N″- Tetramethylmalonamidine (20) reacts with triethylborane (21a), ethoxydiphenylborane (21b) and trimethoxyborane (21c) to give the neutral complexes 22a-c which partly can be protonated with HBF4 to form the salts 23a, b.
    Notes: N,N,N′,N′-Tetramethylmalonsäurediamid (4) bildet mit Triethyloxonium-tetrafluoroborat in siedendem Tetrachlorethan oder mit Diethylether  -  Bortrifluorid bei Raumtemperatur das Tetrafluoroborat 6a, das sich mit Triethylamin zum 4,6-Bis(dimethylamino)-2,2-difluor-3-oxa-1-oxonia-2-borata-4,6-cyclohexadien (7) deprotonieren läßt. Bortrichlorid liefert mit 4 in CCl4 den Neutralkomplex 9, in CH2Cl2 den Chelatkomplex 10. Ähnlich wie Diethylether  -  Bortrifluorid kondensieren auch (2-Aminoethoxy)diphenylboran (12) und Triethylboran (15) mit 4 zu den Salzen 13 bzw. 17 und zu den Neutralkomplexen 14 bzw. 16. N,N,N″N″-Tetramethylmalonamidin (20) bildet mit Triethylboran (21a), Ethoxydiphenylboran (21b) und Trimethoxyboran (21c) die Neutralkomplexe 22a-c, die sich mit HBF4 teilweise zu den Salzen 23a,b protonieren lassen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840217
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  • 114
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    Electronic Resource
    Masthead (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984) 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840401
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  • 115
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    Synthesis of Deoxyoligonucleotide Linker Fragments for Genetic Engineering Using Improved Preparative and Analytical Techniques (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 835-853 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese von Desoxyoligonucleotid-Fragmenten zur Anwendung in der Genverknüpfung unter Einsatz verbesserter präparativer und analytischer MethodenZur Untersuchung der Expression rekombinanter DNS haben wir Oligonucleotide als Genverknüpfungsfragmente dargestellt, die spezifische Spaltstellen sowohl in die DNA wie in das zugehörige Protein einführen. Ihr Aufbau ist so, daß die Spaltung eines Fusionsproteins entweder durch Bromcyan oder durch Kollagenase erfolgen kann. Die Synthese wurde nach dem Triesterschema durchgeführt, wobei schnellere und einfachere Wege zu funktionalisierten Dinucleotid-Baueinheiten entwickelt wurden. Die Felddesorptions-Massenspektrometrie diente als Routine-methode für den Strukturbeweis und die Reinheitskontrolle dieser Baueinheiten.
    Notes: For studies on the expression of recombinant DNA, linker fragments have been prepared which serve to introduce specific points of cleavage on the DNA as well as the protein level. Such linkers were designed for cyanogen bromide as well as for collagenase cleavage of fused proteins. The preparation was done according to the triester synthesis scheme using improved and simpler routes to functionalized dinucleotide building blocks. Field desorption mass spectrometry was used as a routine tool for the identification and control of the purity of these units.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840502
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  • 116
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    Iturin AL: Struktur und Derivate eines Peptidolipids mit hohem C16-Iturinsäurenanteil (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 854-866 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Iturin AL: Structure and Derivatives of a Peptidolipid with a High Content of C16-Iturinic AcidsBacillus subtilis A 114 produces the peptidolipid iturin AL with high antifungal activity. Iturin AL is a difficultly separable mixture due to homologous β-amino fatty acid (iturinic acid) units, which differs from other iturins by its high content of C16-acids. The octapeptide ring of iturin AL has the following iturinic acid composition: 3-amino-12-methyltridecanoic acid (3%), 3-aminotetradecanoic acid (31%), 3-amino-13-methyltetradecanoic acid (15%), 3-amino-12-methyltetradecanoic acid (9%), 3-amino-14-methylpentadecanoic acid (35%), and 3-aminohexadecanoic acid (5%). The D-tyrosine ring of the antibiotic was acetylated, methylated, iodinated, nitrated, and aminated. Each derivative was chromatographed and characterized by spectroscopy.
    Notes: Bacillus subtilis A 114 produziert das Peptidolipid Iturin AL (1) mit hoher antifungischer Aktivität. Iturin AL ist ein schwierig zu trennendes Gemisch aufgrund homologer β-Aminofettsäure-(Iturinsäure-)Bausteine, wobei im Gegensatz zu anderen Iturinen ein ungewöhnlich hoher Anteil an C16-Säuren auftritt. Der Octapeptidring von Iturin AL hat folgende Iturinsäurenzusammensetzung: 3-Amino-12-methyltridecansäure (3%), 3-Aminotetradecansäure (31%), 3-Amino-13-methyltetradecansäure (15%), 3-Amino-12-methyltetradecansäure (9%), 3-Amino-14-methylpentadecansäure (35%) und 3-Aminohexadecansäure (5%). Der D-Tyrosinring des Antibiotikums wurde acetyliert, methyliert, iodiert, nitriert und aminiert. Jedes Derivat wurde chromatographiert und spektroskopisch charakterisiert.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840503
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  • 117
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    Lactonic Constituents of Angelica glauca (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 888-893 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Inhaltsstoffe mit Lactonstruktur aus Angelica glaucaDie Struktur eines zweiten neuen Lacton-Dimeren, des Angelicolids (4), das aus den Wurzeln von Angelica glauca Edgew. isoliert wurde, ist mit spektroskopischen Methoden und durch Röntgenstrukturanalyse aufgeklärt worden. Angelicolid erwies sich als symmetrisches Dimeres des Butylidenphthalids 1 (E-Ligustilid).
    Notes: The structure of a second new dimeric lactone, angelicolide (4), isolated from the roots of Angelica glauca Edgew., has been assigned by spectroscopy and X-ray analysis. Angelicolide has been found to be a symmetric dimer of the butylidenephthalide 1 (E-ligustilide).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840506
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  • 118
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    Chemie reaktiver Kationen von Schwefeldioxidanalogen, IX. Umsetzung mit aliphatischen Carbodiimiden (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 900-903 
    Details
    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, IX. - Reactions with Aliphatic CarbodiimidesN-Methyl-N-sulfinylmethanaminium-tetrafluoroborat (2) yields with aliphatic carbodiimides (1) 1,2,4-thiadiazetium salts (3).
    Notes: N-Methyl-N-sulfinylmethanaminium-tetrafluoroborat (2) reagiert mit aliphatischen Carbodiimiden (1) zu 1,2,4-Thiadiazetiumsalzen (3).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840508
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  • 119
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    Heterocyclen aus α-Nitroolefinen, VII. 4,5-Dihydro-2-methyl-5-methylenamino-3-furancarbonsäureester aus α-Nitroolefinen, Acetessigestern und Verbindungen mit aktiver Methylengruppe (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 911-919 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Heterocycles from α-Nitroolefins, VII. - 4,5-Dihydro-2-Methyl-5-methyleneamino-3-furancarboxylates from α-Nitroolefins, Acetoacetates, and Compounds with an Active methylene Group4,5-Dihydro-2-methyl-5-methyleneamino-3-furancarboxylates 5 are prepared by three preparative methods from α-nitroolefins 1, acetoacetates 2, and compounds with an active methylene group 4. - For 1H NMR investigations which prove the homoallylic system of the 4,5-dihydro-2-methyl-3-furancarboxylates 5 the two 4,5-dihydro-2-methyl-5-methyleneamino-4-([D5]phenyl)-[4-D]-3-furancarboxylates [D6]5e and [D6]5f have been synthesized.
    Notes: 4,5-Dihydro-2-methyl-5-methylenamino-3-furancarbonsäureester 5 werden nach drei präparativen Verfahren aus α-Nitroolefinen 1, Acetessigestern 2 und Verbindungen mit aktiver Methylengruppe 4 hergestellt. - Für 1H-NMR-Untersuchungen, die das Homoallylsystem der 4,5-Dihydro-2-methyl-3-furancarbonsäureester 5 beweisen, werden die zwei 4,5-Dihydro-2-methyl-5-methylenamino-4-[D5]phenyl)[4-D]-3-furancarbonsäureester [D66]5e und [D6]5f synthetisiert.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840510
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  • 120
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    Dehydrierungsreaktionen mit Gallussäureestern (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 929-938 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Dehydration Reactions with Gallic Acid EstersGallic acid methyl ester (1) is oxidized by horseradish peroxidase giving the benzotropolone compound 3 and dimethyl 3,3′,4,4′,5,5′-hexahydroxy-2,2′-diphenate (2) which easily forms ellagic acid (4). By the analgous reaction with the gallic acid esters of ethanediol, 1,3-propanediol, 1,4-butanediol, trans-1,2-cyclohexanediol, 3,6-digalloylglucose, and pentagalloylglucose only 4 is formed. Oxidation of 1 by air in alkaline medium yields 4 and the 1-benzofuran derivative 9. If 9 is treated with alkali the furan ring is opened to give an intermediate from which the acconitic acid derivative 11 or the naphthalene system 12 or the benzoxepine compound 14 are obtained. By oxidation of 1 with iron(III) chloride the furan 15 is obtained.
    Notes: Gallussäure-methylester (1) liefert mit Meerrettich-Peroxidase den 3,3′,4,4′,5,5′-Hexahydroxy-2,2′-diphensäure-dimethylester (2), der leicht in Ellagsäure (4) übergeht, sowie Purpurogallin-4-carbonsäure-methylester (3). Die analoge Reaktion mit den Digalloylestern von Ethandiol, 1,3-Propandiol, 1,4-Butandiol, trans-1,2-Cyclohexandiol, 3,6-Digalloylglucose und Pentagalloylglucose führt nicht zu den Diphensäurederivaten, sondern nur zu 4. Luftoxidation von 1 in alkalischem Milieu führt teils zu 4, zum anderen Teil zum 1-Benzofuranderivat 9, dessen bemerkenswerte Reaktionen beschrieben werden. Unter Einwirkung von Alkali wird zunächst der Furanring geöffnet, und von hier aus gelangt man zum Acconitsäurederivat 11, zum Naphthalinsystem 12 oder zur Benzoxepinverbindung 14. Mit Eisen(III)-chlorid als Oxidationsmittel wird aus 1 Ellagsäure (4) und das Furanderivat 15 erhalten.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840512
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  • 121
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    Synthesen und absolute Konfigurationen von (+)-(6R,2′S)-Cryptocaryalacton und (-)-(6S,2′S)-Epicryptocaryalacton (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 977-981 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses und absolute Configurations of (+)-(6R,2′S)-Cryptocaryalactone and (-)-(6S,2′S)-EpicryptocaryalatoneThe naturally occurring (+)-cryptocaryalactone [(+)-4] and the (-)-epicryptocaryalactone [(-)-5] have been synthesized starting from the optically active aldehyde. 1. The absolute configuraitons of these unsaturated lactones were determined by circular dichroism measurements.
    Notes: Das natürliche (+)-Cryptocaryalacton [(+)-4] und das (-)-Epicryptocaryalation [(-)-5] wurden, ausgehend von optisch aktivem Aldehyd 1, synthetisiert. Die absoluten Konfigurationen dieser ungesättigten Lactone wurden mit Hilfe des Circulardichroismus bestimmt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840515
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  • 122
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    Reactions of Glutaconic and Homophthalic Anhydrides with Imidates, Imidoyl Chlorides, and 1-Chloroisoquinoline (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 389-394 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reaktionen von Glutacon- und Homophthalsäureanhydriden mit Imidoestern, Imidoylchloriden und 1-ChlorisochinolinGlutaconsäureanhydrid (9) reagiert mit N-substituierten Benzimidoylchloriden 3 zu den entsprechenden (Z)-3-[(Amino)(phenyl)methylen]pyrandionen 12 und mit 1-Chlorisochinolin (4) zum Benzo[a]chinolizinon 13. Die Umsetzung von α-Methylhomophthalsäureanhydrid (10) mit 3 und dem Imidat 7 liefert die 1 (2H)-Isochinolinone 14 bzw. 19 und die mit 4 das 13-Methyldibenzo-[a,g]chinolizinon 15. Die zu α-Kondensationsprodukten führende Reaktion von 1a, b mit 3 wird untersucht.
    Notes: Glutaconic anhydride (9) reacts with N-substituted benzimidoyl chlorides 3 to give the corresponding (Z)-3-[(amino)(phenyl)methylene]pyrandiones 12, whereas with 1-chloroisoquinoline (4) the benzo[a]quinolizinone 13 is obtained. The reactions of α-methylhomophthalic anhydride (10) with 3 and the imidate 7 lead to the 1 (2H)-isoquinolinones 14 and 19, respectively, and with 4 to the 13-methyldibenzo[a,g]quinolizinone 15. The interaction of homophthalic anhydrides 1a, b with 3 aiming at the preparation of α-condensation products is investigated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840219
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  • 123
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    Neue Inhaltsstoffe von Levisticum officinale Koch (Liebstöckel) (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 397-400 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New Constituents of Levisticum officinale KochFalcarindiol (1) was identified as the antibiotic principle in roots of Levisticum officinale (Umbelliferae). In addition (Z)-ligustilide (2), angeolide (3), and five new dimers of ligustilide were isolated. Structures were elucidated by spectroscopic methods.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840221
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  • 124
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    Berichtigung zu dem Betrag (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 407-407 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840223
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  • 125
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    Lithiumenolate von Kohlenhydraten, 2. Axiale α-C-Methylierung und -Hydroxymethylierung von Kohlenhydratulosen (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1094-1099 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Lithium Enolates of Carbohydrates,, 2. Axial α-C-Methylation and -Hydroxymethylation of Carbohydrate UlosesLithium diisopropylamide generates regiospecifically enolates of the carbohydrate uloses 1, 5 and 8 which are treated with methyl iodide to yield stereospecifically the α-C-methyluloses 2a, 6a and 9. With formaldehyde the enolates yield the corresponding hydroxymethylated compounds 2b and 6b. In two cases subsequent reduction of the carbonyl function to 7 and 11 is observed.
    Notes: Die Kohlenhydratulosen 1, 5 und 8 ergeben mit Lithiumdiisopropylamid regiospezifisch Enolate, die mit Methyliodid stereospezifisch zu den α-C-Methylulosen 2a, 6a und 9 reagieren. Mit Formaldehyd werden die entsprechenden hydroxymethylierten Produkte 2b und 6b erhalten. In zwei Fällen tritt nachfolgende Reduktion der Carbonylgruppe zu 7 und 11 ein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840606
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  • 126
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    Synthese und Furanosid/Pyranosid-Isomerisierung von 7-Desaza-2′-desoxy-7-methylguanosin (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 708-721 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Furanoside/Pyranoside Isomerization of 7-deaza-2′-deoxy-7-methylguanosine7-Deaza-2′deoxy-7-methylguanosine (2), an isoster of the zwitterionic 2′-deoxy-7-methylguanosine (1) and its α anomer 10b was synthesized. Phase-transfer glycosylation of 2-amino-4-methoxy-5-methyl-7-H-pyrrolo[2,3-d]pyrimidine (6b) with 1-chloro-2-deoxy-3,5-O-(p-toluoyl)-α-D-erythro-pentofuranose (7a) caused regioselective glycosylation of position 7 to give the anomers 8 and 9 in 87% yield. Deprotection of the sugar moiety by sodium methanolate gave the nucleosides 10a and 11; subsequent cleavage of the 4-methoxy group by aluminium chloride in DMF leads to 2 and its α anomer 10b. Treatment of 10a with 7 N HCI/dioxane resulted in isomerization and demethylation forming the furanosides 10b and 2 and the pyranosides 12b and 13b. Isomerization of 10a without demethylation was achieved with 1 N hydrochloric acid and gave the furanosides 10a and 11 as well as the pyranosides 12a and 13a.
    Notes: 7-Desaza-2′-desoxy-7-methylguanosin (2), ein Isoster des zwitterionischen 2′-Desoxy-7-methyl-guanosins (1) und sein α-Anomer 10b wurden synthetisiert. Phasentransferglycosylierung von 2-Amino-4-methoxy-5-methyl-7H-pyrrolo[2,3-d]pyrimidin (6b) mit 1-Chlor-2-desoxy-3,5-di-O-(p-toluoyl)-α-D-erythro-pentofuranose (7a) führt in regioselektiver 7-Glycosylierung zu den Anomeren 8 und 9 in 87proz. Ausbeute. Nach Abspaltung der Schutzgruppen am glyconischen Rest mit Natriummethanolat erhält man die Nucleoside 101a und 11, deren 4-Methylether mit Aluminiumchlorid/DMF zu 2 und dessen α-Anomeren 10b gespalten werden. Wird 10a mit 7 n HCI/Dioxan demethyliert, so erfolgt Isomerisierung zu den Furanosiden 10b und 2 sowie den Pyranosiden 12b und 13b. Isomerisierung von 10a zu den Furanosiden 10a und 11 sowie den Pyranosiden 12a und 13a kann ohne Demethylierung in 1 n Salzsäure erreicht werden.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840408
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    Eine einfache Methode zur Herstellung von 2-Arylbenzofuranen und die Synthese von Moracin A und B (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 734-741 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A Practical Method for the Preparation of 2-Arylbenzofurans and the Synthesis of Moracin A and BOxidative rearrangement of 2-benzyloxychalcones 2 with Ti(No3)3 in methanol to 1,2-diaryl-3,3-dimethoxy-1-propanones 3, alkaline degradation to aryl 2-benzyloxybenzyl ketones 4, debenzylation, and ring closure gave 2-arylbenzofurans 1. In this way moracin A and B (1a, b), further 2-(2,4-dihydroxyphenyl_-5,6-dimethoxybenzofuran (1c) were synthesized. The latter was not identical with a substance isolated from Myroxylon balsamum for which structure 1c was claimed.
    Notes: Die oxidative Umalgerung von 2-Benzyloxychalkonen J. Amer. Chem. Soc.2 mit Ti(NO3)3 in Methanol, alkalischer Abbau der entstandenen 1,2-Diaryl-3,3-dimethoxy-1-propanone 3 zu Aryl(2-benzyloxybenzyl)-ketonen 4, Entbenzylierung und Ringschluß führte zu 2-Arylbenzofuranen 1. Mit dieser Methode wurden u. a. Moracin A und b (1a, b) sowie 2-(2,4-Dihydroxyphenyl)-5,6-dimethoxybenzofuran (1c) synthetisiert. Letzteres war mit einer aus Myroxylon balsamum isolierten und als 1c beschriebenen Substanz nicht identisch.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840410
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    Reaktionen partiell acylierter Aldohexopyranoside, II. Regioselektive Oxidatin partiell acylierter Aldohexopyranoside mit Pyridiniumchlorochromat und ein neues photochemisches Verfahren zur Darstellung von Methyl-3,6-didesoxy-α-D-ribo- hexopyranosid (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 783-790 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of Partially Acylated Aldohexopyranosides, II. - Regioselective Oxidation of Partially Acylated Aldohexopyranosides with Pyridinium Chlorochromate and a New photochemical Method for the Preparation of Methyl 3,6-Dideoxy-α-D-ribo-hexopyranosideRegioselective oxidation of methyl 2,6-di-O-pivaloyl-α-D-glucopyranoside (1) with pyridinium chlorochromate yields methyl 2,6-di-O-pivaloyl-α-D-ribo-hexopyranosid-3-ulose (2) as well as a ten-membered cyclic diester. If methyl 3,6-di-O-benzoyl- (7) and methyl 3,6-di-O-pivaloyl-α-D-mannopyranoside (8) is treated with the same reagent, methyl 3,6-di-O-benzoyl- (9) and methyl 3,6-di-O-pivaloyl-α-D-arabino-hexopyranosid-2-ulose (10) are obtained in good yields. Reduction of these products leads to the corresponding glucose derivatives 11-13 with high diastereoselectivity. Irradiation of the so obtained methyl 3,6-di-O-pivaloyl-α-D-glucopyranoside (12) in hexamethylphosphoric triamide/water (97:3) leads to methyl 3,6-dideoxy-α-D-ribo-hexopyranoside (14, methyl α-D-paratoside). Application of sodium tetradeuterioborate in the first reduction step, results in the specifically deuterated dideoxy sugar 16.
    Notes: Die regioselektive Oxidation von Methyl-2,6-di-O-pivaloyl-α-D-glucopyranosid (1) mit Pyridiniumchlorochromat ergibt Methyl-2,6-di-O-pivaloyl-α-D-ribo-hexopyranosid-3-ulose (2) sowie einen zehngliedrigen cyclischen Diester. Bei der Umsetzung von Methyl-3,6-di-O-benzoyl-)7) sowie Methyl-3,6-di-O-pivaloyl-α-D-mannopyranosid (8) mit dem gleichen Reagenz werden Methyl-3,6-di-O-benzoyl- (9) und Methyl-3,6-di-O-pivaloyl-α-D-arabino-hexopyranosid-2-ulose (10) in guten Ausbeuten erhalten. Die Reduktion dieser Produkte führt mit hoher Diastereoselektivität zu den entsprechenden Glucosederivaten 11-13. Die Bestrahlung des auf diese Weise zugänglichen Methyl-3,6-di-O-pivaloyl-α-D-glucopyranosids (12) in Hexamethylphosphorsäuretriamid/Wasser (97:3) ergibt Methyl-3,6-didesoxy-α-D-ribo-hexopyranosid (14, Methyl-α-D-paratosid). Bei Verwendung von Natrium-tetradeuterioborat im ersten Reduktionsschritt ist der spezifisch deuterierte Didesoxyzucker 16 zugänglich.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840414
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    Ringöffnungsreaktionen von 2-Siloxycyclopropancarbonsäuremethylestern zu 4-Oxoalkansäurederivaten (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 802-819 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Ring Opening Reactions of Methyl 2-Siloxycyclopropanecarboxylates to 4-Oxoalkanoic Acid DerivativesA great variety of methyl 2-(trialkylsiloxy)cyclopropanecarboxylates C1-C31 are cleaved under very mild condition and with excellent yields providing 4-oxoalkanoic esters D1-D31 Which are important synthetic building blocks. Even sensible esters with formyl, vinyl ketone, or trimethylsiloxy functions can be prepared. Corresponding to the regioselective synthesis of C isomeric pairs of D Can deliberately be constructed. In the presence of an electrophile alkylating ring opening delivers 4-oxoalkanoates substituted in position 2, however, the degree of alkylation does not exceed 60%. Several other cleavage variations allow syntheses of other 4-oxoalkanoic acid derivatives in effective one-pot procedures.
    Notes: Die in großer Vielfalt zur Verfügung stehenden 2-(Trialkylsiloxy)cyclopropancarbonsäuremethylester C1-C31 werden unter sehr milden Bedingungen und in hohen Ausbeuten in die 4-Oxoalkansäure-methylester D1-D31 übergeführt, die als Synthesebausteine von Bedeutung sind. Es können auch empfindliche Ester mit Formyl-, Vinylketon- oder Trimethylsiloxyfunktion dargestellt werden. Der regioselektiven Synthese von C entsprechend kann man gezielt isomere 4-Oxoalkansäureester D aufbauen. Die alkylierende Ringöffnung in Gegenwart eines Elektrophils führt zu 2-substituierten 4-Oxoalkansäureestern, deren Alkylierungsgrad allerdings 60% nicht übersteigt. Weitere Spaltungsvarianten, die im Eintopfverfahren andere 4-Oxoalkansäurederivate liefern, werden mitgeteilt.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840416
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    An Efficient, One-Step Synthesis of 2-Imidazolin-4(5)-one (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 831-834 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Eine ergiebige, einstufige Synthese von 2-Imidazolin-4(5)-onDie Titelverbindung 4, das lange bekannte biologische Zwischenprodukt beim Abbau von Xanthin zu N-(Iminomethyl)glycin, wird in einer einstufigen Umsetzung von Aminoacetonitrilhydrochlorid mit überschüssigem Trimethyl-orthoformat mit einer Ausbeute von Mehr als 90% erhalten. Der Mechanismus der Reaktion wird diskutiert.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840419
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  • 131
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    Masthead (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984) 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840501
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  • 132
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    1,2-Oxazetidin-3-one aus (2-Thienyl)glycolohydroxamsäuren und 1,1′-Carbonyldiimidazol (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 894-899 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 1,2-Oxazetidin-3-ones from (2-Thienyl)glycolohydroxamic Acids and 1,1′-CarbonyldiimidazoleReaction of (2-thienyl)glycolohydroxamic acids 6 with 1,1′-carbonyldiimidazole yields 1,2-oxaze-tidin-3-ones 3B in high yields. The conversion of 6 into 3B proceeds via the intermediate 5B which can be isolated under suitable conditions.
    Notes: (2-Thienyl)glycolohydroxamsäuren 6 reagieren mit 1,1′-Carbonyldiimidazol in hohen Ausbeuten über die unter geeigneten Bedingungen isolierbare Zwischenstufe 5B zu 1,2-Oxazetidin-3-onen 3B.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840507
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  • 133
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    Synthese des Lycopodium-Alkaloids rac-Lucidulin aus Hexahydro-7-methylchinolin (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1519-1528 
    Details
    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 Lycopodium Alkaloid rac-Luciduline from Hexahydro-7-methylquinolineThe 1,4 addition of malonic acid to the eneimine functional group of 2 leads to diastereomeric imines which via disproportionation can be transformed into the pyridine derivative 9. From 9 the ester 5b is obtained stereoselectively. Oxidation of 5b with potassium permanganate and crown ether yields the lactam ester 15. The cyclization and transformation of 15 into rac-luciduline (1) is described. 5b can also be obtained in a simple, nonstereoselective synthesis from the ketone 10.
    Notes: Durch 1,4-Addition von Malonsäure an die Eniminfunktion in 2 entstehen diastereomere Imine, die sich durch Disproportionierung in das Pyridinderivat 9 umwandeln lassen. Stereoselektiv wird daraus der Ester 5b gewonnen, der mit Kaliumpermanganat und Kronenether den Lactamester 15 liefert. Die Cyclisierung und Umwandlung von 15 zum rac-Lucidulin (1) ist beschrieben. Der Ester 5b wird in einer einfachen, nicht stereoselektiven Synthese auch aus dem Keton 10 erhalten.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840812
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  • 134
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    Feodor Lynen 1911-1979 (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. I 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840902
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  • 135
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    Antibiotika aus Gleitenden Bakterien, XXII. Die Biosynthese des Antibiotikums Myxopyronin A aus Myxococcus fulvus Stamm Mx f50 (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1088-1093 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Antibiotics from Gliding Bacteria, XXII. - The Biosynthesis of Myxopyronin A, an Antibiotic from Myxococcus fulvus, Strain Mx f50The biosynthesis of the antibiotic myxopyronin A (1) from acetate, glycine, and methionine was investigated by feeding experiments with the corresponding 13C- and 15N labeled precursors and observing the labeling pattern by 13C-NMR. The carbon skeleton of the antibiotic is derived from two polyacetate chains. Glycine is incorporated as starting unit into one of the chains. Two of the three methyl groups are incorporated from methionine, the third one from C-2 of acetate.
    Notes: Die Biosynthese des Antibiotikums Myxopyronin A (1) aus Acetat, Glycin und Methionin wurde durch Einbauversuche mit den entsprechenden 13C- und 15N-markierten Vorstufen anhand der 13C-NMR-Spektren aufgeklärt. Das Molekülgerüst wird aus zwei Polyacetat-Ketten aufgebaut, wobei Glycin in einem Fall als Starter fungiert. Zwei der drei Methylverzweigungen stammen aus Methionin, die dritte aus einem C-2-Atom von Acetat.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840605
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  • 136
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    1,6-Anhydrofuranosen, XV Konkurrierende Darstellung der 1,6:2,5- und 1,6: 3,5-Dianhydro-α-L-gulofuranosen, Ringöffnung der 1,6: 3,5-Dianhydro-α-L-gulofuranose (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1597-1604 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 1,6-Anhydrofuranoses, XV. - Competitive Preparation of 1,6: 2, 5- and 1,6:3,5-Dianhydro-α-L-gulofuranoses, Ring Opening of 1,6:3,5-Dianhydro-α-L-gulofuranose1,6-Anhydro-5-O-tosyl-β-D-mannofuranose (1) shows two hydroxy groups in sterically favourable positions for intramolecular substitution at position 5. In accordance with exspectation, heating of 1 in DMF gives a mixture of the dianhydrides 2a and 3, from which the 1,6: 3,5-dianhydride 2a predominates (ratio 2a:3 as 40:1). Treatment of 2a with HCl in methanol opens both anhydro rings yielding the methyl glycofuranosides 4a and 5a of presumably α-D-manno configuration. The mass spectra of all known isomeric dianhydrohexofuranoses, despite anhydro sugar epoxides, are discussed.
    Notes: 1,6-Anhydro-5-O-tosyl-β-D-mannofuranose (1) trägt zwei Hydroxygruppen in Positionen, die jeweils intramolekulare Substitution der Tosylgruppe erlauben sollten. Die Umsetzung von 1 in DMF bei erhöhter Temperatur führt zu den möglichen Dianhydriden 2a und 3, wobei das 1,6: 3,5-Dianhydrid 2a jedoch weitaus überwiegt (Verhältnis 2a:3 wie 40:1). Durch Umsetzung mit HCl in Methanol werden in 2a beide Anhydroringe geöffnet. Hierbei werden die Methyl-glycofuranoside 4a und 5a mit wahrscheinlich α-D-manno-Konfiguration gebildet. Die Massen-spektren der bekannten isomeren Dianhydrohexofuranosen, soweit es sich nicht um Epoxide handelt, werden diskutiert.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840908
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  • 137
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    Berichtigung zu dem Beitrag Reaktionen enolischer Zuckerderivate, XVI. - Die Synthese einer diastereotopen Protonensonde [(Z)-3,7-Anhydro-1,2-didesoxy-D-gluco-oct-2-enitol] für α- und β-D-Glucosylasen (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1626-1626 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840911
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  • 138
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    Benzothiazole durch C—C-Spaltung von α-[(2-Nitrophenyl)thio]ketonen (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1100-1108 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Benzothiazoles by C-C Cleavage of α-[(2-Nitrophenyl)thio] KetonesReaction of α-[(2-nitrophenyl)thio] ketone 4, 11a-c and 16 with ammonia and sodium hydroxide solution, resp., leads to C—C cleavage and formation of the benzothiazole N-oxide derivatives 8, 12a-c and 17. The 3-[(2-nitrophenyl)thio]-4-piperidone derivative 22 yields 2-benzothiazolecarbaldehyde 23.
    Notes: Einwirkung von Ammoniak bzw. Natronlauge auf die α-[(2-Nitrophenyl)thio]ketone 4, 11a-c und 16 führt unter C—C-Spaltung zu den Benzothiazol-N-oxid-Derivaten 8, 12a—c und 17; aus dem 3-[(2-Nitrophenyl)thio]-4-piperidon-Derivat 22 entsteht der 2-Benzothiazolcarbaldehyd 23.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840607
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  • 139
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    Naphthylendi(heteroarene), III. Synthese und spektroskopisches Verhalten von 2,2′-Naphthylendibenzazolen (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1129-1136 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Naphthylenedi(heteroarenes), III. - Synthesis and Spectroscopic Properties of 2,2′-NaphthylenedibenzazolesStarting from 2,2′-(1,4-naphthylene)dibenzoxazole, used as fluorescent whitening agent for polyester fibers and plastics, it is systematically investigated how structural modifications affect spectroscopic properties such as absorption, fluorescence, extinction, and quantum yield.
    Notes: Ausgehend von dem als optischer Aufheller für Polyesterfasern und Kunststoffe verwendeten 2,2′-(1,4-Naphthylen)dibenzoxazol wird systematisch untersucht, wie sich Strukturabwandlungen auf spektroskopische Eigenschaften wie die Lage der Absorptions- und Fluoreszenzbande, die Oszillatorenstärke und Quantenausbeute auswirken.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840610
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  • 140
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    Stereoselektive Synthese von Alkoholen, XVIII. Synthese von (3S,4S)-4-Methyl-3-heptanol und von (5S,6S)-Anhydroserricornin (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1170-1179 
    Details
    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, XVIII. - Synthesis of (3S,4S)-4-Methyl-3-heptanol and of (5S,6S)-AnhydroserricorninYeast reduction of methyl tetrahydro-4-oxo-2H-thiopyran-3-carboxylate (5) led to the β-hydroxy ester 6 of 98% diastereomeric and ca. 85% enantiomeric purity. 6 was converted into enantiomerically pure anti-4-methyl-3-heptanol (4) and via the key intermediate 11 into enantiomerically pure anhydroserricornin (3).
    Notes: Durch Hefe-Reduktion des Tetrahydro-4-oxo-2H-thiopyran-3-carbonsäure-methylesters (5) erhielten wir mit 98% Diastereoselektivität und ca. 85% Enantioselektivität den β-Hydroxyester 6. Daraus wurde enantiomerenreines anti-4-Methyl-3-heptanol (4) und über die Schlüsselverbindung 11 enantiomerenreines Anhydroserricornin (3) dargestellt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840613
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  • 141
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    1,5-Dimethylbicyclo[3.3.0]octan-2,6-dion und 1,5-Dimethyl-bicyclo[3.3.0]octa-3,7-dien-2,6-dion. - Grundbausteine substituierter Semibullvalene (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1180-1192 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 1,5-Dimethylbicyclo[3.3.0]octane-,6-dione and 1,5-Dimethylbicyclo[3.3.0]octa-3,7-diene-2,6-dione. - Basic Building Blocks for Substituted SemibullvalenesMichael reaction of dimethyl methylmalonate (13) and tert-butyl acrylate (14) affords almost quantitatively the triester 15a which is selectively hydrolyzed to yield the diester-acid 15b. When subjected to Kolbe electrolysis, this produced a 1:1 mixture (28% yield) of the diastereomeric tetraesters rac-12b and meso-12b. After Dieckmann condensation of this mixture followed by hydrolysis of the intermediate β-keto esters 16 and 17 and decarboxylation of the β-keto acids a 93% yield of the bicyclo[3.3.0]octane-2,6-dione 4 and a 61% yield of the crystallized cyclopentanone ester-acid 18 were isolated. On bromination of the diketone 4 using four moles of copper(II) dibromide in chloroform/ethyl acetate as solvent, the α,α′-dibromo diketone 19 is formed as the major product. Dehydrobromination of the crude bromination product of 4 using four moles of copper(II) dibromide in chloroform/ethyl acetate as solvent, the α,α′-dibromo diketone 19 is formed as the major product. Dehydrobromination of the crude bromination product of 4 by means of calcium carbonate in dimethylacetamide as solvent afforded a 67% yield of the α,β-unsaturated diketone 5 besides 4-8% of the unsaturated α-bromo diketone 21. All reactions can be readily carried out on large scale.
    Notes: Michael-Addition von Methylmalonsäure-dimethylester (13) an tert-Butyl-acrylat (14) führt nahezu quantitativ zum Triester 15a, der selektiv zur Diestersäure 15b hydrolysiert wird. Deren Kolbe-Elektrolyse ergibt mit 28% Ausbeute ein (1:1)-Gemisch der diastereomeren Tetraester rac-12b und meso-12b. Nach Dieckmann-Kondensation dieses Gemisches, anschließender Verseifung der intermediären β-Ketoester 16 und 17 und Decarboxylierung der β-Ketosäuren isoliert man 93% Bicyclo[3.3.0]octandion 4 und 61% kristallisierte Cyclopentanonestersäure 18. Bei der Bromierung des Diketons 4 mit 4 mol Kupfer(II)-dibromid in Essigester/Chloroform entsteht hauptsächlich das α,α′-Dibromdiketon 19. Durch Dehydrobromierung des rohen Bromierungsprodukts von 4 mit Calciumcarbonat in Dimethylacetamid erhält man 67% α,β-ungesättigtes Diketon 5 und 4-8% ungesättigtes α-Bromdiketon 21. Alle Reaktionen können sehr einfach im größeren Maßstab durchgeführt werden.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840614
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  • 142
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    Synthese des ersten Leaf Movement Factors aus Mimosa pudica L. (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1230-1239 
    Details
    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 First Leaf Movement factor from Mimosa pudica L.In the following we describe the synthesis of the first Leaf Movement Factor from Mimosa pudica L. (M-LMF 1). Proceeding from functionalized derivatives of 2,5-dihydroxybenzoic acid (gentisic acid) and D-glucose we obtained by Koenigs-Knorr reaction the protected aryl β-D-glucoside 7. By several reaction steps the SnCl4-catalyzed conversion by means of a 1-O-acetyl derivative of the D-apiofuranose 13 leads to the synthetic Leaf Movement Factor.
    Notes: Es wird die Synthese des ersten Leaf Movement Factors aus Mimosa pudica L. (M-LMF 1) be schrieben. Ausgehend von funktionalisierten Derivaten der 2,5-Dihydroxybenzoesäure (Gentisinsäure) und D-Glucose gelangt man durch Koenigs-Knorr-Reaktion zum geschützten Aryl-β-D-glucosid 7. Die SnCl4-katalysierte Umsetzung mit einem 1-O-Acetylderivat der D-Apiofuranose 13 führt über mehrere Stufen zum synthetischen Leaf Movement Factor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840618
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  • 143
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    Synthesen und Eigenschaften von 2,2′-Bipyridin-3-olen und -3,3′-diolen (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1731-1739 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Properties of 2, 2′-Bipyridin-3-ols and -3,3′-diolsThe synthesis of the 2-furyl ketones 5-7 and 13 and their reaction with ammonium acetate in boiling acetic acid to 3-substituted 2,2′-bipyridines and to 2-(2-pyrimidinyl)-3-pyridinol (14) via a ring-transformation reaction are described. Strong intramolecular hydrogen bonds are responsible for their physical and chemical properties.
    Notes: Die neu dargestellten 2-Furylketone 5-7 und 13 sowie deren Ketimine reagieren mit Ammoniumacetat in siedender Essigsäure über eine Ringtransformation zu 3-substituierten 2,2′-Bipyridinen bzw. zu 2-(2-Pyrimidinyl)-3-pyridinol (14). Starke intramolekulare Wasserstoffbrücken bestimmen deren physikalisches und chemisches Verhalten.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419841013
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  • 144
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    Pteridine, LXXIV. Acylierungen des Lumazin-Systems durch radikalische nucleophile Substitution (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1798-1814 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Pteridines, LXXIV.  -  Acylations of Lumazines by Radical Nucleophilic SubstitutionLumazines are prone to radical nucleophilic substitutions and form with acyl radicals at the unsubstituted pyrazine moiety in a regioselective reaction 7-acyllumazines (12-21). Alkyl substituents in 7-position direct the entering acyl residue into the 6-position (23-27). Donor-substituents such as amino, hydroxy, alkoxy, and methylthio groups, respectively, in 6- (28-32) or 7-position (48-52, 55) support the radical substitution at the adjacent C-atom to give the products (34-45) generally in reasonable yields. The newly synthesized compounds have been characterized by pKa determinations, UV, and NMR spectra.
    Notes: Lumazine sind der radikalischen nucleophilen Substitution zugänglich und liefern bei fehlenden Substituenten am Pyrazinteil der Moleküle in regioselektiver Reaktion mit Acylradikalen die entsprechenden 7-Acyllumazine (12-21). Alkylsubstituenten in 7-Stellung dirigieren den eintretenden Acylrest in die 6-Position (23-27). Donatorsubstituenten, wie die Amino-, Hydroxy-, Alkoxy- bzw. Methylthio-Gruppe, in 6- (28-32) und 7-Position (48-52, 55) begünstigen die radikalische Acylierung (34-35) in der Nachbarstellung und verlaufen teilweise mit recht guten Ausbeuten. Die neuartigen Verbindungen werden durch pKa-Werte, UV- und NMR-Spektren charakterisiert.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419841106
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  • 145
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    Annulated 1,2,3-triazoles, I. Synthesis of 8-Azapurin-6-ones and 8-Azapurin-6-imines from Ethyl 5-Acetylamino-1,2,3-triazole-4-carboxylates (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1848-1859 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Anellierte 1,2,3-Triazole, I.  -  Synthese von 8-Azapurin-6-onen und 8-Azapurin-6-iminen aus 5-Acetylamino-1,2,3-triazol-4-carbonsäure-ethylesternDie neuen 8-Azapurin-6-one 3 und die entsprechenden 8-Azapurin-6-imine 4 werden durch Cyclokondensation von 5-Acetylamino-1,2,3-triazol-4-carbonsäure-ethylestern 2 mit Amin-hydrochloriden in Gegenwart von Phosphorpentoxid und N,N-Dimethylcyclohexylamin hergestellt. Für die Bildung von 3 und 4 wird ein Reaktionsmechanismus vorgeschlagen. Einige der Produkte 3 wurden auf ihre fungizide Wirksamkeit getestet.
    Notes: The new 8-azapurin-6-ones 3 and the corresponding 8-azapurin-6-imines 4 are prepared by cyclocondensation of ethyl 5-acetylamino-1H-1,2,3-triazole-4-carboxylates 2 with amine hydrochlorides in the presence of phosphorus pentoxide and N,N-dimethylcyclohexylamine. A reaction pathway is proposed for the formation of 3 and 4. Various products 3 have been tested for fungicide activity.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419841109
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  • 146
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    Synthesis of New Tetrahydrofuran and Tetrahydropyran Derivatives from α-Pinene and 3-Carene (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1860-1863 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthese von neuen Tetrahydrofuran- und Tetrahydropyranderivaten aus α-Pinen und 3-CarenAusgehend von (+)-α-Pinen und (+)-3-Caren wurden die neuen cyclischen Ether 3-7 synthetisiert. Ihre spektroskopischen Daten, optischen Rotationen und Geruchs-Charakteristika werden angegeben.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419841110
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  • 147
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    Inhaltsstoffe von Cupuliferae, 9. Ein ungewöhnlicher Diester des Astragalins mit cis- und trans-p-Cumarsäure aus Quercus ilex L. (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1867-1868 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Constituents of Cupuliferae, 9.  -  An Unusual Diester of Astragalin with cis- and trans-p-Coumaric Acid from Quercus ilex L.From leaves of Quercus ilex L. a new acylated astragalin has been isolated and identified as 3-O-kaempferol 2,6-di-O-(trans/cis-p-coumaroyl)-β-D-glucopyranoside (1).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419841112
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  • 148
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    Thiosubstitutierte Butine und Butadiene aus Polychlorbuten und Thiolen (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1873-1877 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thio-substituted Butynes and Butadienes from Polychlorobutenes and ThiolsHexachlorobutene (1) yields compounds 2-4 with thiolates in water-containing ethanol solutions at room temperature. Reaction of 2b with potassium tert-butoxide yields compound 5b. The tris(arylthio) derivative 4b is formed by reaction of 3b with sodium 4-(methylthio)phenolate in DMSO. A tris(arylthio)-substituted butatriene 7b is formed by HCl elimination from 4b. The butatriene 7b obtained partly isomerizes to give the tris(arylthio)butenyne 8b at room temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419841114
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  • 149
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    Masthead (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984) 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419841201
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  • 150
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    Mehrstufige reversible Redoxsysteme, XXXVII. Biazulenyle und ω,ω′-Biazulenylpolyene: Synthesen und spektroskopische Eigenschaften (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1905-1935 
    Details
    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, XXXVII.  -  Biazulenyls and ω,ω′-Biazulenylpolyenes: Syntheses and Spectroscopic PropertiesThe ω,ω′-biazulenylpolyenes 2-12 were selected to study the dependence of their redox properties from the linkage position. This paper describes the syntheses of the mostly unknown systems 2.1-9.n via Wittig, Horner-Emmons, and McMurry reactions. UV/VIS and 1H NMR spectra confirm the depicted structures and configurations.
    Notes: Zum Studium der Abhängigkeit des Redoxverhaltens von der Verknüpfungsposition in den ω,ω′-Biazulenylpolyenen 2-12 werden durch Wittig-, Horner-Emmons- und McMurry-Reaktionen die Systeme 2.1-9.n größtenteils erstmals synthetisiert. UV/VIS-und 1H-NMR-Spektren bestätigen die angegebene Konstitution und Konfiguration.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419841203
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  • 151
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    Mehrstufige reversible Redoxsysteme, XXXIX. Isomere Biazulenyle: UV/VIS-Spektroskopie, Voltammetrie und HMO-Energien (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1952-1958 
    Details
    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, XXXIX.  -  Isomeric Biazulenyls: UV/VIS Spectroscopy, Voltammetry, and HMO EnergiesUV/VIS spectra and voltammetrically determined redox properties of isomeric biazulenyls depend strongly on the positions of linkage between the azulenyl groups. All isomers can be reversibly reduced in two steps (KSEMc = 2·103 to 6·1010), however, only the 1,1′-isomer (4.0) can be reversibly oxidized (in two steps; KSEMa = 1.4·106). Comparison of redox potentials and HOMO/LUMO energies allows estimation of steric effects caused by different degrees of twisting of the isomers. Besides, in some cases the possibility of triplet states can be derived.
    Notes: UV/VIS-Spektren und voltammetrisch bestimmtes Redoxverhalten der isomeren Biazulenyle hängen stark von der Verknüpfungsposition ab. Während sämtliche Isomere reversibel zweistufig reduzierbar sind (KSEMc = 2·103 bis 6·1010), ist nut das 1,1′-Isomere (4.0) auch reversibel (zweistufig) oxidierbar (KSEMa = 1.4·106). Durch Vergleich der Potentiale mit den HOMO/LUMO-Energien läßt sich die Auswirkung des unterschiedlichen Verdrillungsgrades abschätzen und die Möglichkeit der Bildung von Triplettzuständen bei einigen Isomeren erkennen.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419841205
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  • 152
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    Anomere Tubercidine mit 2-Methylthio- und N4-(Δ2Isopentenyl)rest (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1972-1980 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Anomers of Tubercidin Derivatives with 2-Methylthio and N4-(Δ2-Isopentenyl) ResiduesStarting with the chloronucleosides 3a and 4a the anomers 1 and 2 or 2-(methylthio)tubercidin were prepared. They are desulfurized to tubercidin (3c) and its α-anomer 4c. Desulfurization of the N4-(Δ2-isopentenyl) compounds 3b and 4b yields 3d and 4d; due to hydrogenation the by-products 3e and 4e are formed. Isopentenylation of tubercidin followed by Dimroth rearrangement also give N4-(Δ2-isopentenyl)tubericidin (3d). From the 1J(C,H) coupling constants of the glyconic moiety the sequence of the 13C signals of the α-anomer 2 was deduced. The 3J(C-6,1′-H) couplings of tubercidins gave the torsion angle χ which is found to be in the anti region.
    Notes: Die anomeren 2-(Methylthio)tubercidine 1 und 2 wurden aus den Chlornucleosiden 3a und 4a dargestellt und zu Tubercidin (3c) und seinem α-Anomer 4c entschwefelt. Die Entschwefelung der (Δ2-Isopentenyl)verbindungen 3b und 4b führt zu 3d und 4d sowie teilweise unter Reduktion zu 3e und 4e. N4-(Δ2-Isopentenyl)tubercidin (3d) ist auch durch Isopentenylierung von Tubercidin nach Dimroth-Umlagerung zugänglich. Die 1J(C,H)-Kopplungen des glyconischen Restes führen zur Zuordnung der 13C-Signale beim α-Anomeren 2 und die 3J(C-6,1′-H)-Kopplung zum Torsionswinkel χ, der bei den Tubercidinen im anti-Bereich liegt.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419841207
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  • 153
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    A Convenient Synthesis of Phenylpropargylaldehyde Diethyl Acetal (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1529-1530 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Eine einfache Synthese von Phenylpropargylaldehyd-diethylacetalEs wird die Synthese von Acetylencarbaldehyd-acetalen am Beispiel des Phenylpropargylaldehyd-diethylacetals beschrieben.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840813
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  • 154
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    Masthead (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984) 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840901
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  • 155
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    Ring-Ketten-Isomerie bei N-(1-Carboxyalkyl)nitronen, I C-Aryl-N-(1-carboxyalkyl)nitrone (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1545-1562 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Ring-Chain Isomerism of N(1-Carboxyalkyl)nitrones, I. - C-Aryl-N-(1-carboxyalkyl)nitronesN-(1-Carboxyalkyl)nitrones 3 are prepared by alkylation of aromatic (Z)-aldoximes 1 or by condensation of α-(hydroxyamino)carboxylic acids 2 and aromatic aldehydes. The ring-chain isomerism between the nitrone 3 and the N-hydroxyoxazolidine 4 could not be proved by spectroscopical methods. Acylation of 3 with diphenylborinic acid leads to diphenylboron chelates 5 of the open-chain nitrone form, whereas acylation with carboxylic acids or isocyanate results in the formation of N-(acyloxy)oxazolidones 8. alkylation of 3 with phenacyl bromide gives the ester 12.
    Notes: N-(1-Carboxyalkyl)nitrone 3 werden durch Alkylierung aromatischer (Z)-Aldoxime 1 oder durch Kondensation von α-(Hydroxyamino)carbonsäuren 2 mit aromatischen Aldehyden dargestellt. Die Ring-Ketten-Isomerie zwischen Nitron 3 und N-Hydroxyoxazolidon 4 ließ sich spektroskopisch nicht nachweisen. Die Acylierung von 3 mit Diphenylborinsäure führt zu den Diphenylborchelaten 5 der offenkettigen Nitronform, während durch Acylierung mit Carbonsäuren oder Isocyanat N-(Acyloxy)oxazolidone 8 erhalten werden. Bei der Alkylierung von 3 mit Phenacylbromid bilden sich die Ester 12.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840904
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  • 156
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    Über Verbindungen mit Urotropin-Struktur, LX Orthooxalsäure- und Orthokohlensäurederivate mit Adamantanstruktur (1984)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 1577-1590 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Compounds with Urotropine Structure, LX. - Orthooxalic and Orthocarbonic Acid Derivatives with Adamantane StructureMethyl trimethoxyacetate (1) and cis-1,3,5-cyclohexanetriol (2) easily react to give methyl 2,4,10-trioxaadamantane-3-carboxylate (3). Based on 3, further derivates of 2,4,10-trioxaadamantane are prepared. By degradation reactions, 3-bromo- and 3-amino-2,4,10-trioxaadamantane 20 and 21 are obtained. Both are new derivates of orthocarbonic acid, their structure elements being unknown up to now.
    Notes: Aus Trimethoxyessigsäure-methylester (1) und cis-1,3,5-Cyclohexantriol (2) ist 2,4,10-Trioxaadamantan-3-carbonsäure-methylester (3) leicht zugänglich. Aus 3 werden weitere Derivate des 2,4,10-Trioxaadamantans erhalten. Durch Abbaureaktionen gelangt man zu 3-Brom- und 3-Amino-2,4,10-trioxaadamantan 20, 21. Beide sind neue Orthokohlensäureabkömmlinge mit bisher unbekannten Strukturelementen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198419840906
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  • 157
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    Alkyl Shifts between Transition Metals and Coordinated Main Group Atoms (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1-17 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This work considers the theoretical aspects of the shift of an alkyl(or aryl) group from a coordinated phosphine to the 16-electron d8 transition metal to which it is coordinated. This rearrangement at first seems to resemble an anionic [1,2]-sigmatropic shift. But a detailed analysis of the relatively low barrier calculated for the reaction shows how all traces of the forbiddeness of the reaction have vanished. Phenyl migration should eb still more facile. We also analyze in some detail the possible pathways of alkyl halide addition to a phenyl-Pt complex. An alkyl migration, now from metal to coordinated C-atom, could possibly intervene in this process.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670102
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  • 158
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    Metal complexes with macrocyclic ligands. Part XIXPart XVIII: [1].. Synthesis and Cu2+-complexes of a series of 12-, 14- and 16-membered cis- and trans-N2S2-macrocycles (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 29-38 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of 12-, 14-, and 16-membered N2S2-macrocycles (9-11 and 19-21) with cis and trans-arrangement of the heteroatoms have been synthesized by high-dilution cyclization and subsequent reduction of the amides with B2H6. With these ligands the corresponding Cu2+-complexes were prepared and their UV/VIS spectra, their electrochemistry and their EPR properties have been studied. Generally three absorption bands at 270-320 nm, 330-370 nm and 530-620 nm can be observed in aqueous solution and these have been assigned to the N→Cu2+ and S→Cu2+ charge-transfer bands and to the d-d* transition, respectively. The cyclic voltammetry in CH3CN shows in all cases a reversible or quasi-reversible Cu2+/Cu+-transition at potentials of 10-480 mV against SHE. The values of g‖ and A‖ obtained from EPR spectra indicate that the geometry of the Cu2+-complex of the 14-membered cis-N2S2-macrocycle is less distorted than that of the other complexes.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670105
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  • 159
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    The Synthesis of cis- and trans- 7-Phenylkacetamido-O-2-isocephemO-2-Isocephems are alternatively called isooxacephems (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 902-905 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the title compounds is described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670331
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  • 160
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    Mitteilungen-Communiacations (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 928-930 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670335
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  • 161
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    Synthese und Struktur von Zink-Komplexen von 2-Amino-1-azetinen (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 927-933 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis ad Structure of Zinc Complexes of 2-Amino-1-azetinesThe 2-dimethylamino-3,3-dimethyl-1-azetines 7a and 7b have been synthesized in analogy to the procedure reported by Ghosez et al. [1] (Scheme). The crystal structure of 1-benzhydryl-azetidindimethyliminium chloride 5a, a precursor of azetine 7a, has been established by X-ray diffraction analysis. Treatment of azetines 7a and 7b with ZnBr2 in CH2Cl2/MeCN yielded tetrahedral bis (azetine)dibromozinc complexes 8a and 8b, respectively (Scheme 2). The molecular structure of 8a has been determined by X-ray diffraction analysis too.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670402
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  • 162
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    Radical Ions of Conjugated Polycyclic Hydrocarbons Containing Two Phenalenyl π-Systems (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 934-938 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The radical cations and the radical of 1,2-bis(phenalen-1-ylidene)ethane (1), 1,2-bis(phenalen-1-ylidene)ethene (2) and pentaleno[1,2,3-cd: 4,5,6-c′ d′]diphenalene (3) have been characterized by ESR and ENDOR spectroscopy. The ease of formation of these radical ions and their π-spin distributions are interpreted in terms of a simple model correlates the frontier orbitals of 1, 2 and 3 with the nonbonding MO's of two phenalenyl π-systems.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670403
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  • 163
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    Aliphatic Liquid Crystals with Positive Dielectric Anisotropy (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 959-963 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyanothyl-subsituted cylohexyl cyclohexanoates, bi(cyclohexanes) and phenyl cyclohexanes were synthisized. Their mesmorphic behaviour is compared to that of the corresponding cyano derivatives. (Cyanoethyl)cyclohexyl cyclohenxanoates show mesmorphic properties in contrast to the corresponding cyano derivative. Separation of the cyano substituent from the rigid core of an anisotropic aliphatic compound by methylene groups enhances the thermodynamic stability of the mesophase. In aromatic compound, the cyanoethyl group leads to lower clearing points. These phenomena are attributed to teh influence of steric effects on the packing density and to the dependence of the clearing point on molecular association.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670407
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  • 164
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    1,2-Epoxycarotinoide. 4. Mitteilung. Synthese, 1H-NMR- und CD-Studien von (S)-1,2-Epoxy-1,2-dihydrolycopin und (S)-1′,2′-Epoxy-1′,2′-dihydro-γ-carotin (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 968-985 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,2-Epoxycarotenoids: Synthesis, 1H-NMR and CD Studies of (S)-1,2-Epoxy-1,2-dihydrolycopene and (S)-1′,2′-Epoxy-1′, 2′ -dihydro-γ-caroteneThe synthesis of (S)-1,2-epoxy-1,2-dihydrolycopene ((S)-1) and (S)-1′, 2′ -epoxy- 1′, 2′ -dihydro-γ-carotene ((S)-2) are described. The CD spectra of the (all-E)-isomers and of the isomers (7Z, S)-1 and (7′Z, S)-2 are discussed. The comparison of the CD spectra of the synthetic (S)-1 and the compound isolated from the tomatoes proves the (S)-configuration of the natural product.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670409
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  • 165
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    Stereoselective Control in the Base-Catalyzed H/D Exchange of 5,6-Dimethylidene-2-bicyclo[2.2.n]alkanone Tricarbonyliron Complexes. Revision of the Structures of Tricarbonyliron Complexes of 5,6-Dimethylidenebicyclo[2.2.2]oct-2-ene and 5,6-Dimethylidenebicyclo[2.2.1]hept-2-eneA preliminary communication was presented at the Autumn Meeting of the Swiss Chemical Society, Bern, October 14, 1983. (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 986-999 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oxidative hydroboration of exo- (1) and end-Fe(CO)3 (2) complexes of 5,6-dimethylidenebicyclo[2.2.2]oct-2-ene are highly stereoselective and give endo -alcohol 3 and exo -alcohol 4 as major products, respectively, Collins oxidations of 3 and 4 furnish the corresponding exo -Fe(CO)3 -complexed 5,6-dimethylidene-2-bicyclo-[2.2.2]octanone 7 and 8. NaBH4 reduction of exo-complexes 7 gives a mixture of 3 and isomeric exo-alcohol 18, whereas reduction of endo-complexes 8 gives the endo-alcohol, endo-complexes 19, as the sole product. The base-catalyzed H/D exchange of 7 and 8 afford the dideuterated exo-complex 35 and the monodeuterated endo-complex 32, respectively. Oxidative hydroborations of the exo-(9) and endo-Fe(CO)3 (10) complexes of 5,6-dimethylidenebicyclo[2.2.1]hept-2-ene give the corresponding exo-alcohols 39 and 40. Oxidation of 39 and 40 gives the exo- and endo-complexes 41 and 42, respectively, of 5,6-dimethylidene-2-bicyclo[2.2.]heptanone. Only Hexo —C(3) can be exchanged in 42, wheres both H-atoms at C(3) in 41 are exchangeable. The endo-Fe(CO)3 group in 8 and 42 blocks the base-catalyzed H/D exchange of Hendo —C(3), thus providing a test for the configuration of Fe(CO)3 group in these systems. These studies have led to a revision of the iron configurations proposed by Hansen et al, [2] for 1, 2, 9 and 10.
    Additional Material: 1 Tab.
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    Oxygenation of Dimethylsulfoxide and Copper-Catalyzed Autoxidation of Substituted Benzoins (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1019-1025 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The catalytic activity of autoxidized copper (I) in the oxidation of para-disubstituted benzoins in dimethylsulfoxide by O2 was studied both kinetically and by product analysis. Stoichiometry (1), accounts for more than 80% of the reaction. The catlytic oxydation was followed by monitering th consumption of O2 manometrically by a fully automatic apparatus. (X = H, CH3, OCH3, C6H5 CI)A redox shuttle mechanism is proposed, where the rate-determining step is the autoxidation of Cu(I) followed by a rapid oxidation of the substrate by an oxocupric species. The redox stiochiometry (I) corresponds to that found for external monooxy-genases (or mixed-function oxidases), and the significance of our results with respect to analogous catalytic systems is discussed.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19840670414
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  • 167
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    Kobalt-katalysiert Cycloadditionen von Alkinen und Nitrilen zu Pyridinen: Ein neuer Zugang zu Pyridoxin (Vitamin B6) (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1274-1282 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cobalt-Catalyzed Cycloaddition of Alkynes and Nitriles to Pyridines: A New Route to Pyridoxine (Vitamin B6)A new synthesis of pyridoxine hydrochloride (1) based on a Co-catalyzed cycloaddition of MeCN with substituted di(2-propynyl) ethers (3 and 16) is described. The reaction sequences following cycloaddition and leading to 1 involve as key steps the rearrangement f the pyridine-N-oxide 6 to the 3-hydroxypyridine 7 with Ac2O and a modified Curtius rearrangement of the acid 19 and subsequent diazotation and hydrolysis to the same pyridoxine precursor 7, respectively. The intermediate 7 is transformed to 1 by well-known procedures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670513
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  • 168
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    Synthèse facile de dérivés du diphényl-2,4-aza-3-bicyclo[3.3.1]nonane et du diphényl-7,8-aza-8-bicyclo[4.3.1]décaneUne partie de ce travail a fait l'object d'une communication préliminaire [1]. (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1291-1297 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Facile synthesis of derivatives of 2,4-diphenyl-3-azabicyclo[3.3.1]nonane and 7,9-diphenyl-8-azabicyclo[4.3.1]decaneThe facile synthesis of hydantoins, cyanhydrins and aminonitriles derived from 2,4-diphenyl-3-azabicyclo[3.3.1]nonanone and 7,9-diphenyl-8-azabicyclo[4.3.1]decanone is described. Configurations at C(9) or C(10) of the new compounds wth pharmaceutical and synthetical utility is deduced from their spectral properties.
    Additional Material: 4 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19840670515
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  • 169
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    Messkette zur direkten potentiometrischen Bestimmung des Enantiomerenüberschusses von 1-Phenyläthylmmonium-Ionen (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1439-1447 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cell Assembly for the Potentiometric Determinatin of the Enantiomeric Excess of 1-Phenylethylammonium-IonsA cell assembly with two membranes containing each one enantiomer of the ionophor N,N,N′,N′,N″,N″,N‴,N‴-octabutyl-1,4,7,10,16-hexaoxacyclooctadecane-2,3,11,12-tetracarboxamide is used for the direct potentiomewtirc determination of the enantiomeric excess ee of 1-phenylethylammonium ions in aqueous solutions. The preference for the (R)-over the (S)-1-phenylethylammonium ion by the (2R,3R,11R,12R)-ionophor of 2.7 allows a reliable determination of ee even in the presence of known concentrations of the heavy interferent KCl.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19840670603
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  • 170
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    Drüsenfarbstoffe aus tropischen Labiaten: Parviflorone aus Plectranthus strigosus BENTH. (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1531-1534 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Red-Coloured Abietanoids from Leaf-Glands of Plectranthus strigosus BENTH.Chromatographic examination of the red-coloured diterpenoids from the South-African title plant yielded the following compounds: parviflorone A(1), parviflorone B (2), parviflorone C(3), parviflorone E (4) parviflorone D (5), parviflorone F (6), parviflorone G (7), and parviflorone H (8). Compounds 7 and 8 represent new variants of these quinone methides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670617
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  • 171
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    An Example of Head-to-Head Dimerization of β4.4-Helices (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1588-1592 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1H-NMR and vapor-pressure osmometry results are presented, which indicate the occurrence of a rapid equilibrium involving the head-to-head dimerization of β44-helices in chloroform solutions of HCO-L-Ile-(D-AIle-L-Ile)4-OMe. This equilibrium typifies the one that, in Urry's view, would be responsible for the formation and breaking down of the ion-conducting channels formed by gramicidin A in lipid bilayers.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19840670625
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  • 172
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    Synthese von neuen Morphin-Teilstrukturen des Typs 15,16-Secomorphinan (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1598-1602 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of New Morphine Partial Structure 15,16-SecomorphinanThe synthesis of a new morphine partial structure, 15,16-secomorphinan, is described. One of the series, (±)-15, 16-secocyclorphan (5), has the analgesic potency of morphine and exhibits good binding to the opiate receptor.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/hlca.19840670627
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  • 173
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    Synthese eines cyclischen Depsipeptides mittels Amidcyclisierung (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 526-533 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of a Cyclic Depsipeptide via an Amide CyclizationThe synthesis of (S)-Pms-(R)-Pro-(S)-Ala-Aib-N(CH3)2 (12) has been achieved according to Scheme 3. For the formation of fragment 11, the reaction of Z-alanine (Z = benzyloxycarbonyl) and 3-dimethylamino-2,2-dimethyl-2-azirine (1) has been used, whereby 1 serves as an aminoisobutyric-acid dimethylamide (aib-N(CH3)2) equivalent. Treatment of a suspension of 12 in toluene with HCl gas at 100° led to the cyclic depsipeptide 13 in 72% yield (Scheme 4). In presence of water, the acid 14 was isolated as the sole product. A mechanism for the formation of 13 and 14 via an oxazolinone intermediate, is postulated in Scheme 4.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670221
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  • 174
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    Isolierung und Struktur von Pteridinen (Lumazinen) aus Russula sp. (Täublinge; Basidiomycetes) (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 550-569 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Isolation and Structure Elucidation of Pteridines (Lumazines) from Russula sp. (Basidiomycetes)Extensive chromatogaphic separations and spectroscopic investigations have led to the isolation and identification of several water-soluble pteridines from Russula sp., the so-called russupteridines, namely: 1-(5-amino-2-6-dioxo-1,2,3,6-tetrahydeopyrimidin-4-yl)amino-1-deoxy-D-ribitol (1; a pro-lumazine; first identification in a basidiomycete(; l-deoxy-l-(6-methyl-2-4,7-trioxo-1,2,3,4,7,8-hexahydro-pteridin-8-yl)-D-ribitol (3) and l-deoxy-1-(2,4,7-trioxo-1,2,3,4,7,8-hexahydeopteridin-8-yl)-D-ribitol (4); both compounds found for the first time in higher fungi; they belong to the components with the strongest violet-blue fluorescence in Russula sp.; riboflavine (6; now recognized as an important yellow colorant in a great many of Russula sp.); russupteridine-yellow I (= l-(6-amino-7-(N-fromylimino)-2,4-dioxo-1,2,3,4,7,8-hexahydropteridin-8-yl)-1-deoxy-D-ribitol; 5; a component with very strong fluorescence; the first derivative of the novel 6,7-diamino-lamazine); russupteridine-yellow IV (= l-deoxy-1-)(2,6,8-trioxo-2,4,5,6,7,8-hexahydro-1H-imidazolo[4,5-g]pteridin-4-yl)-D-ribitol (7)). Two further yellow russupteridines (yellow II and Yellow V) with very strong fluorescence have been isolated and characterized.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19840670223
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    Stabilities and Structures of Cu(II) Complexes with Linear Pentadentate Ligands by EPR Spectroscopy (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 2164-2174 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pH-dependent equilibria between Cu(II) and the potentially pentadentate ligands 4,7,10-triazatridecane-1,13-diamine (1) and 1,9bis(2-hydroxyphenyl)-2,5,8-triazanonane (2) have been studied in aq. solution at 298 K by EPR titration. Each ligand forms complexes CuLHx (x=1,2,3) with strongly overlapping spectra. By using a recently developed algorithm, which does not need nay information with regard to the spectra of the species, stability constants and spectra were calculated from the EPR titration data. The anisotropic EPR spectra of the complexes were measured at 153 K and display axial or nearly axial symmetry (g∥ 〉 g⊥) in each case. Based on the spectral parameters the assignment of the structures of the complexes was possible. With 1 and 2 the protonated complexes are equatorially coordinated, whereas in the fully deprotonated complexes an additional axial interaction occurs which is stronger with 2 than with 1.The results of this study show that EPR spectroscopy is a useful method for investigating equilibrium systems of Cu2+ even in complicated cases where minor species occur and where the individual spectra are unknown and strongly overlapping.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19840670817
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  • 176
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    Synthese von N-(4-Aminobutyl)-16-aza-19-nonadecanlactam und N-(4-Aminobutyl)-17-aza-20-icosanlactam (Desoxoinandenin) (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 2178-2185 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of N-(4-Aminobutyl)-16-aza-19-nonadecanelactam and N-(4-Aminobutyl)-17-aza-20-icosanelactam (Desoxoinandenine)According to Scheme 1, the two homologous macrocyclic spermidine derivatives 12 and 23 were synthesized. Key steps in both cases were two different types of ring-enlargement reactions. Compound 12 was identical with a degradation product of the naturally occurring spermidine alkaloids of inandenine-type.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670819
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  • 177
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    Nukleophile Reaktionen an 2-Phenylindolenin-3-onen (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 2186-2191 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nucleophilic Reactions on 2-Phenylindolenin-3-onesNucleophilic reagents such as 4-nitrophenylhydrazine, malonic acid derivatives, and hydrogen peroxide react with 2-phenylindolenin-3-ones giving, in the first step, addition products to the (d) N=C(2) bond. This addition can be reversible, but in most cases new rearrangement products are formed. The structure of the new compounds were elucidated by 1H- and 13C-NMR spectroscopy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670820
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  • 178
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    Stereoselectivity in reactions of metal complexes IXPart VIII, see [1]. Stereoselective formation of cobalt(III) complexes with new linear pentadentate ligands (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 796-803 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of cobalt(III) complexes with the new linear pentadentate ligands meso- and racemic 2,6-bis(3S)-3-carboxy-4-methyl-2-azapentylpyridine (2) are described. Only one of the different possible isomers is obtained from each ligand. The structure of the complexes has been assigned on the basis of their 1H-NMR and CD spectra. The structure of the aqua-cobalt(III)-1a and the aqua-cobalt(III)-1b has been confirmed by X-ray analysis. Partial resolution of optical antipodes of the aquacobalt(III)-1b was achieved by column chromatography and a tentative assignment of their absolute configuration is made.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19840670321
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  • 179
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    Electron-Transfer-Induced Conformational Changes. The Example of 1,8-Dimethyl[14]annulene (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1368-1373 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This communication reports ESR-spectroscopic investigations of the radical anion of 1,8-dimethyl[14]annulene (1) which possesses a flexible molecular framework allowing configurational and conformational mobility. The ESR and ENDOR spectra indicate that at higher temperatures (T 〉 160 K), \documentclass{article}\pagestyle{empty}\begin{document}$ 1^{- \atop \dot{}} $\end{document} exists as a mixture of several distinct isomers. One of them, the sole product at T 〈 160 K, is found to be energetically preferred. The configuration and the conformation of this species can be determined by interpretation of the hyperfine data in terms of a singly occupied MO of the 14-membered π-perimeter.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19840670523
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    Ein meta-Xylylen durch Bamford-Stevens-Reaktion eines Fulven-Keten-Addukts (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1379-1385 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A meta-Xylylene by Bamford-Stevens Reaction of a Fulvene-Ketene-AdductHeating the sodium salt 8 of the tosylhydrazone 4 of 4-isopropyliden-7,7-dimethylbicyclo[3.2.0]hept-2-en-6-one (3; obtained by the addition of dimethylketene to 6,6-dimethylfulvene (1)), in diglyme at 130° led to the cotamethyl-[2.2]metacyclophane 10 (17%). The latter probably was formed by dimerization of the non-Kékulé molecule m-xylylene 14, which, in turn, could have arisen via the homofulvene 13 from the carbene 12. A second product in the thermolysis of 8 was the tricycle 9 (9 %), as a result of an intramolecular insertion of the carbene C-atom in 12 into a methyl C,H-bond. Further products were the azines 11a, 11b (50%), of the type known as byproducts in Bamford-Stevens reactions. Heating dry 8 afforded 9 (9%) and the two benzene derivatives 15 (9%) and 16 (3%). The tosylhydrazone 4 could be recovered by reaction of 11a, 11b with p-toluenesulfonohydrazide.
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    URL: http://dx.doi.org/10.1002/hlca.19840670525
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    Etudes sur les composés organométalliques partie XXPartie XIX, v. [5]. Sélectivité de l'addition 1,4 de composés benzyliques du titane IV avec la benzylidéneacétone (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1475-1477 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Studies of Organometallic Compounds, XX. Selectivity of 1,4-Addition of Benzyltitanium Compounds with BenzylildenacetoneTetrabenzyltitanium and dialkoxydibenzyltitanium compounds give essentially 1,4- addition with trans-4-phenyl-3-buten-2-one.
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    URL: http://dx.doi.org/10.1002/hlca.19840670608
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    Photochemistry of 8,8,9,9-tetramethyl-1,3,4,6,7,8-hexahydro-1,4-ethanonaphthalene-2,5-dione, a δ-oxo-β,γ-unsaturated ketone (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1493-1495 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The oxa-di-π-methane rearrangement product 4,4,9,9-tetramethyltetracyclo [6.4.0.01,5.02,8]dodecane-7,12-dione (2) is formed selectively in a variety of solvents on either direct (λLD = 254, 300, 350 nm) or sensitized (xanthone, acetone, benzene) irradiation of the title compound 1. The efficiency for this rearrangement is higher on So-S1 excitation (Φ-1 = 0.67) than on either So-S2 or So-S3 excitation (Φ-1 = 0.58).
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19840670611
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    Novel, racemic or nearly-racemic antibacterial bromo- and chloroquinols and γ-lactams of the verongiaquinol and the cavernicolin type from the marine sponge Aplysina (= Verongia) cavernicolaPresented in preliminary form in a lecture by F. P. at the 7th International Diving Science Symposium, Padova, September 15-18th, 1983. (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1484-1492 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Butanolic extracts of the Mediterranean sponge Aplysina (= Verongia) cavernicola have given, by reverse-phase HPLC, the antibacterial quinols (±)-3-bromoverongiaquinol (= (±)-3-bromo-1-hydroxy-4-oxo-2,5-cyclohexadine-1-acetamide; 1d) and (±)-3-bromo-5-chloroverongiaquinol (= (±)-3-bromo-5-chloro-1-hydroxy-4-oxo-2,5-cyclohexadine-1-acetamide; 1c) besides the products of their formal cyclization 5-chlorohexadiene-1-acetamide; 1c) besides the products of their formal cyclization 5-chlorocavernicolin (= 5-cloro-3,3a,7,7aβ-tetrahydro-3aβ-hydroxy-2,6(1H)-indoledione; 6), the C(7)-epimerizing 7β-bromo-5-chlorocavernicolin (=7 β-bromo-5-chloro-3,3a,7,7aβ-tetrahydro-3aβ-hydroxy-2,6(1H)-indoledione; 4a and 7α-bromo-5-chlorocavernicolin (4b), and the C(7)-epimerizing 5-bromo-7β-chlorocavernicolin ( = 5-bromo-7β-chloro-3,3a,7,7aβ-tetrahydro-3aβ-hydroxy-2,6(1H)-indoledione; 5a) and 5-bromo-7α-chlorocavernicolin (5b). The latter four were isolated as mixtures of C(7)-epimerizing monoacetates 4a′/4b′ and 5a′/5b′. Both 1 and 1c proved to be racemic from NMR examination of their esterification products with (-)-methyl-oxyacetic acid, whilst 6 had a ca. 6% enantiomeric purity as shown by a 1H-NMR study of its monoacetate 6′ in the presence of a chiral shift reagent. These chiroptical data of the first chiral quinols from the Verongida and of 6 suggest phenol oxidative routes from tyrosine precursors for their formation. In view of their bioactivities, 1d and 1c have been synthesized from (p-hydroxyphenyl)acetic acid byt phenol oxidative routes.
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    Studies on the Stereochemistry of 2-(Nitromethylidene)-HeterocyclesContribution No. 57 from the Research Centre.Nitroenamines, Part X. For Part IX see [1]. (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1669-1680 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 1H-NMR spectra of 2-(nitromethylidene)pyrrolidine (7), 1-methyl-2-(nitromethylidene)imidazolidind (10) and 3-(nitromethylidene)tetrahydrothiazine (11) in CDCl3 and (CD3)2SO indicate that these compounds have the intramolecularly H-bonded structures (Z)-7, (E)-10 and (Z)-11 while the N-methyl derivative 8 of 7 is (E)-configurated in both solvents. 1-Benzylamino-1-(methyltio)-2-nitroehtylene (13), an acylic model, has the H-bonded configuration (E)-13 in CDCl3 and in (CD3)2SO. 2-(Nitromethylidene)thiazolidine (3) has the (E)-configuration in CDCl3 but exists in (CD3)2SO as a mixture of (Z)- and (E)-isomers with the former predominating. Both species are detected to varying proportions in a mixture of the two solvents. 15N-NMR spectroscopy of 3 ruled out unambiguously the nitronic acid structure 6 and the nitromethyleimine structure 5. The N-methyl derivative 4 of 3 is (Z)-configurated in (CD3)2SO. Comparison of the olefinic proton shifts of (Z)-3 and (Z)-4 with those of analogues and also of 1,1-bis(methylti)-2-nitroethylene (12) shows decreased conjugation of the lone pair of electrons of the ring N-atom in (Z)-3 and (Z)-4. This is also supported by 13C-NMR studies. Plausible explanations for the phenomenon are offered by postulating that the ring N-atoms are pyramidal in (Z)-3 and (Z)-4 and planar in other cases or, alternatively, that the conjugated nitroenamine system gets twisted due to steric interaction between the NO2-group and the ring S-atom. Single-crystal X-ray studies of 3 and 8 show that the former exists in the (Z)-configuration and the latter in (E)-configuration; the ring N-atom in the former has slightly more pyramidal character than in the latter.
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  • 185
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    The Persistence of Ribbon Orbitals in Polycyclic AlkanesPart II of ‘The Equivalent Bond Orbital Model Revisited’. Part I. cf. [1]. (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1681-1690 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Equivalent bond orbital (EBO) calculations by a procedure based on recalibrated, localized bond orbitals derived from an ab initio model, suggest that the two frontier ‘ribbon’ orbitals ϕHOMO, ϕHOMO-1 of polycyclic hydrocarbons consisting of all-trans-connected six-membered rings are well separated in energy from the remaining manifold of σ-orbitals. Assuming the validity of Koopmans' theorem, a PE-spectroscopic investigation of perhydroanthracenes, 2-methylperhydrophenalene and perhydroperylene have shown that this is indeed the case. According to the theoretical treatment these ribbon orbitals are evenly delocalized over the whole of the molecular frame and they conserve the characteristic phase relationship postulated by Hoffmann et al. [16] for cyclohexane moieties. Their behaviour under the successive introduction of centres of unsaturation, i.e., of double bonds is discussed.
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  • 186
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    Total Synthesis of (±)-2-PupukeanonePresented at the Swiss Chemical Society in Bern, October 1981 by Jean Wenger. (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1702-1706 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (±)-2-Pupukenone (4) has been synthesized, the key step being the intramolcular Diels-Alder reaction of the intermediate 13 to 14 (42%) and 15 (14%). The bromodiene 12 has been obtained from the reaction of α-isopropylidene-γ-lactone (Scheme 2) 12 with sodium phenylselenide and subsequent esterification to 9, oxidation and thermal elimination of which furnished 10. Reduction of 10 with diisobutylaluminimum hydride and treatment of the resulting alcohol 11 with PBr3 led to the required bromodiene 12. Finally, hydrogenation of the 14 on Pt(C) in CH3OH gave a 4:1 mixture of 2-pupukeanone (4) and epi-2-pupukeanone 16.
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  • 187
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    A New Pyranocoumarin Diester from Polygala paniculata L (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1729-1733 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new coumarin diester has been isolated from Polygala paniculata L. (Polygalaceae) by a combination of flash chromatography on silica gel and preparative reversed-phase chromatography. Its structure has been determined as 3′-O-acetyl-4′-O-benzoylkhellactone (= 9-acetoxy-9,10-dihydro-8,8-dimethyl-2-oxo-2 H,8H-benzo[1,2-b:3,4-b′]dipyranh-10-yl benzoate) by spectroscopic methods (UV, IR, 1H-NMR, EI-and CI-MS) and by X-ray analysis.
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  • 188
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    Photochemical reactions. 140th Communication139th Communication, see [1]. Acid-catalyzed rearrangement and electron transfer photooxygenation of cyclopropanols and their silyl ethers (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 1748-1754 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On acid-catalyzed hydrolysis, the tricyclic compounds 2 and 10, incorporating cyclopropyl-silyl-ether moieties undergo rearrangement to the cis-decalones 3 and 7, respectively. Hydrolysis of 2 and 10 in the presence of oxygen leads additionally to the formation of the 1,2-dioxolan-3-ols 9 and 13, respectively, which involves an electron-transfer oxygenation process as could be demonstrated by photooxygenation of the silyl ether 10 and the cyclopropanol 14 in the presence of 9,10-dicyanoanthracene. The configurations of 3 and 9 were assigned by X-ray analysis of the latter compound as well as of the p-nitrobenzoate 8 of 3.
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  • 189
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    On the Stereochemistry of Natural Irones, Dihydroirones, and their Precursors (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 318-324 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Natural irones from the essential oil of Iris rhizomes develop by oxidative degradation of C31-triterpenoids produced by the plant. Two enantiomeric forms of irones are found in Iris, oils of different origin. The optical properties and CD spectra of irones, dihydroirones and their C31-precursors are reported and their absolute stereochemistry is determined.
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  • 190
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    Mitteilungen - Communications (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 361-364 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670143
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  • 191
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    Die diasteromeren Aurochrome: Synthese, Analytik und Chiroptische Eigenschaften (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 471-487 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Diastereomeric Aurochromes: Their Synthesis, Analysis and Chiroptical Properties(all-E)-Aurochrome (5,8:5′,8′-diepoxy-5,8,5′,8′-tetrahydro-β,β-carotene; 1) has two pairs of constitutionally identical chiral centres and, therefore, is expected to exist in four pairs of enantiomers and two meso-forms. Using starting materials with well-defined configuration, we performed the syntheses of the following pure aurochromes: (5R,8R,5′R,8′R)-aurochrome (2) and its racemate, Meso-(5R,8R,5′S,8′S)-aurochrome (3), (5 R,8 S,5′ R,8′ S)-aurochrome (4) and its racemate, meso-(5R,8S,5′S,8′R)-aurochrome (5), (5R,8R,5′R,8′S)-aurochrome (6) and its racemate. The (5RS,8RS,5′SR,8′RS)-aurochrome (7) was detected chromatographically, using a HPLC system that allows clean separation of the four racemic- (or optically active) and the two meso-aurochromes. The optically active autochromes 2 and 4 exhibit non-conservative CD spectra with strong Cotton effects of opposite but not mirror-like tracings. Solutions of aurochromes in CHCl3, in the presence of HCl, undergo epimerization at C(8). Those epimers with CH3 trans to C(9) slightly predominate under equilibrium conditions. Deprotonation of the phosphonate (±)-14 with strong base causes isomerization at the terminal oxirane into a dihydrofuran. This reaction allowed convenient syntheses of the diastereoisomeric aurochromes (±)-2, 3, (±)-4, 5, (±)-6, and (±)-7 and of (5RS, 8RS)- and (5RS, 8SR)-12′-apo-aurochrome-12′-als (21 and 22, respectively).
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19840670218
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    Synthesis of cyclosporinePart III; for Part I and II, s. [1a] and [1b], respectively.Part of the work has already been presented at the autumn session of the Swiss Chemical Society in Berne (October 15, 1983), for more details and previous presentations see [1c].. Total syntheses of ‘cyclosporin A’ and ‘cyclosporin H’, two fungal metabolites isolated from the species Tolypocladium inflatum GAMS (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 502-525 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The heptapeptide H-MeBmt-Abu-Sar-MeLeu-Val-MeLeu-Ala-OBzl (20) was synthesized for coupling with the previously described cyclosporine tetrapeptide sequence Boc-D-Ala-MeLeu-MeVal-OH (21). The product of the coupling, the undecapeptide Boc-D-Ala-MeLeu-MeLeu-MeVal-MeBmt-abu-Sar-MeLeu-Val-MeLeu-Ala-OBzl (22), was then deprotected and cyclized to cyclosporine (1).The tetrapeptide diastereoisomer Boc-D-ala-MeLeu-MeLeu-D-MeVAl-OH (23) could also be used as a starting material to produce selectively the desired undecapeptide 22. In this case, the N-methyl-D-valine unit, was selectively isomerized to the L-from by using the appropriate condensing agent. The diastereoisomeric undecapeptide Boc-D-ala-MeLeu-MeLeu-D-MeVal-MeBmt-Abu-Sar-MeLeu-Val-MeLeuAla-OBzl (24) was also synthesized starting from 21 by using the mixed pivalic anhydride method to selectively invert the configuration of the N-methyl-L-valine. The structure of the undecapeptide 24 was confirmed by deprotection and cyclization to ‘cyclosporin H’, a natural product known to have the structure [D-MeVal11]cyclosporine (2).
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  • 193
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    1,3-Dipolare Cycloadditionen von Nitrilium-Betainen mit 4,4-Dimethyl-2-phenyl-2-thiazolin-5-thion (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 534-549 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,3-Dipolar cycloadditions of Nitrilium Betaines with 4,4-Dimethyl-2-phenyl-2-thiazolin-5-thioneBenzonitrile ylides, imines, and oxides undergo smooth 1,3-dipolar cycloaddition reactions with the exocyclic, C,S-double bond of 4,4-dimethyl-2-phenyl-2-thiazolin-5-thione (1), yielding heterocyclic spiro-compounds. The structure of the cycloadducts 5c, 5c′, and 3f (Fig.) have been established by x-ray structure analysis.With the benzonitrile ylides, the two regioisomeric cycloaddition modes have been observed, depending on the substituents of the ylide-C-atom. It is questionable, whether the reaction of 1 and the oxazaphosphol 8 (Schemes 8 and 13) proceeds via the corresponding nitrile ylide as an intermediate.
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  • 194
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    Mitteilungen - Communications (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 625-627 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670231
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  • 195
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    Masthead (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984) 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670301
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  • 196
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    Preparation and Properties of Bis[μ-S-(2-tiolatoethyl)-diphenylphosphine][(2-thiolatoethyl)diphenyl-phosphine]dinickel(+1) Ion, a Novel Unsymmetrical Thiolate-bridged complex (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 654-663 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title cation ( = Ni2L+3) is formed in a variety of reactions (Schemes 1 and 2) in systems containing Ni2+ and (2-thiolatoethyl)-diphenylphosphine (= L-) in the absence of coordinating anions at Ni2+/L- ratios 〉 0.5 in apolar or moderately polar media. Solid [Ni2L3]CIO4 and [Ni2L3]BPh4 have been isolated. Job's plots confirm the Ni2L+3- stoichiometry in solution. 31P-NMR data are consistent with ≥ 97% Ni2L+3 (vs. ≤ 3% of hypothetical Ni3L2+4) at equilibrium and support the suggested configuration (Fig. 2). The equilibrium between NiL2 + NiL2Br2 and Ni2L+3 + Br- varies with the solvent composition in CH23Cl2/EtOH mixtures. The rate of formation of Ni2L2Br2 from Ni2L+3 and bromide (in high excess) in CH2Cl2 is first-order in [Ni2L+3]tot but depends on the ratio [Bu4NBr]tot/[Ni2L3 · ClO4]tot, even at a high excess of bromide. This is interpreted by efficient competition in ion-aggregate formation between the small perchlorate concentration introduced as the counterion of Ni2L+3, and the large excess of bromide.
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  • 197
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    Protolytic Opening of Two Diastereoisomeric Cyclopropanols12th Communication in the series ‘Cob(I)alamin as Catalyst’: for the 11th communication see [1a]. (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 684-689 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cob(I) alamin (1(I))-catalyzed reduction of the aldehyde 2 led to the two crystalline cyclopropanols 3 and 4 (see Scheme 2). The protolytic ring-opening starting from 3 produced the saturated aldehydes 6 and 7;8 was formed in traces only (see Scheme 3). The protolysis starting from 3 led, therefore, mainly to retention of configuration at the spiro C-atom (7); ring-opening with inversion was observed in traces only (8). Starting from 4, the protolysis produced 9 and 7; the absence of 8 showed this protolysis to proceed 9 and 7; the absence of 8 showed this protolysis to proceed exclusively with inversion of configuration at the spiro center. Of the p-bromobenzoate 5 (cf. Scheme 2) the structure has been determined by X-ray analysis.
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  • 198
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    NMR Conformational Study of Aminoalkylbenzamides, Aminoalkyl-o-anisamides, and Metoclopramide, a Dopamine Receptor Antagonist (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 706-716 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational behaviour of metoclopramide, a neuroleptic benzamide, and model compounds was investigated byt 1 H-NMR spectroscopy. An intramolecular amide-methoxy H-bond is shown to exist in CDCl3-solution, but not in D2O-solution, independently of the length and protonation state of the basic side-chain. This H-bond creates a virtual cycle which may be a key feature for the binding of neuroleptic benzamides to the dopamine receptor. The conformational behaviour of the aminoethyl side-chain is shown to be markedly condition-dependent. For metoclopramide and its analogues in their protonated form, the gauche- and trans- rotamers have identical energies in D2O-as well as in CDCl3-solutins. For the non-protonated molecules, the trans-rotamer is favoured in D2O-solutin, while the gauche-rotamer is favoured in CDCl3-solution (ΔG°≃|0.5|kcal/mol in both cases). The side-chain conformation of neuroleptic benzamides is discussed in terms of receptor affinity.
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    URL: http://dx.doi.org/10.1002/hlca.19840670310
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  • 199
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    Asymmetric Aldol Condensation of 1-Naphtol and Pyruvates in the Presence of Lewis Acids Preliminary Communication (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 739-742 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Lewis acids catalyze teh condensation of methyl pyruvate and l-naphtol to give menthyl 2-hydroxy-2-(l-hydroxy-2-naphtyl)propionate in a ratio of up 96:4 in favor of the levorotatory diastereoisomer. Epimerization, at 25°C for five days, occurs on benzylic carbon atom to give a 30:70 mixture enriched with the dextrorotatory isomer.
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  • 200
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    Estimation of Dimerisation Constants from Complexatin-Induced Displacements of 1H-NMR Chemical Shifts: Dimerisation of Caffeine (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 754-764 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The determination of the dimerisation constant (KD) for the weak self-association of a compound C in dilute solution according to the equilibrium, 2C⇌C2 is described. The method uses chemical shifts measured on a series of solutions of C at different concentrations: the optimum KD is defined by a linear regression best-fit procedure, which simultaneously determines optimum values for δo and also for δ∞, the intrinsic chemical shifts for nuclei in the monomer and dimer species. The dimerisation of caffeine in D2O is used as a model to demonstrate the working of the method and the quality of results obtained. The most probable value of KD for caffeine at 30.5° is found in the range 5.5-6.0 kg solution · mol-1, and the enthalpy and entropy of dimerisation are found to be ΔH⊖ = -15.1 kJ · mol-1 and ΔS⊖ = -35.3 J · °C-1 · mol-1, respectively. The influence of small errors in δo on the confidence limits of KD is discussed.
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    URL: http://dx.doi.org/10.1002/hlca.19840670316
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