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1

Digitale Medien

Tartaric Acid Chloralides: Isolation and X-ray Analysis of the Third Existing Stereoisomer. Force-Field and AM1 Calculation of all Six Possible Structures (1989)

Uray, Georg ; Lindner, Wolfgang ; Keller, Walter ; [weitere]

Weinheim : Wiley-Blackwell

Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1203-1205

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ISSN: 0009-2940

Schlagwort(e): AM1 calculations ; Chloralide ; Dioxolane ; Force-field calculations ; Tartaric acid ; Chemistry ; Inorganic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: Isolation of a third diastereoisomer (1c) of (R,R)-tartaric acid chloralide is described. A comparison of structural data derived by X-ray analysis with calculated parameters is given. Structures are generated by the ALCHEMY force-field program as well as by AM1 calculations.

Zusätzliches Material: 3 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/cber.19891220629

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2

Digitale Medien

Stoffwechselprodukte von Mikroorganismen. 231. Mitteilung230. Mitteilung s. [1].. Bafilomycin-A1-21-O-(α-L-rhamnopyranosid): Strukturaufklärung durch chemische Verknüpfung mit Bafilomycin A1 und Leucanicidin (1985)

Meyer, Michael ; Keller-Schierlein, Walter ; Drautz, Hannelore ; [weitere]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 68 (1985), S. 83-94

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: Isolation of Bafilomycin-A1-21-O-(α-L-rhamnopyranoside). Structural Determination by Chemical Correlation with Bafilomycin A1 and LeucanicidinFrom cultures of an actinomycete strain, the known antifungal and insecticidal antibiotic leucanicidin (1) and a hitherto unknown antifungal antibiotic, bafilomycin-A1-21-O-(α-L-rhamnopyranoside) (2), were isolated. The latter is spectroscopically closely related to 1 and bafilomycin A1 (3) and gave degradation products identical with compounds obtained by analogous degradation of 1 and 3.

Zusätzliches Material: 5 Tab.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19850680111

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3

Digitale Medien

Photochemical reactions. 145th Communication144th Communication: [1].. Carbonyl vs. epoxyketone photochemistry: Photolysis of 1,2;3,4-diepoxy-2,6,6-trimethyl-1-cyclohexyl methyl ketone (1985)

Phaff, Rox ; Bischofberger, Norbert ; Mathies, Peter ; [weitere]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 68 (1985), S. 1204-1216

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: The synthesis and photolysis of the title compound 3 is described. Irradiation (λ 〉 280 nm, MeCN) of the di-epoxyketone 3 leads predominantly to γ-H abstraction. Cyclization furnishes the cyclobutanols 22-24, while cleavage gives compound 25, presumably via the allene-oxide intermediate 36. Further, products 27 and 28 are formed by Norrish fragmentation and by initial cleavage of the C(α)—O bond of the oxirane, respectively. The structures of the products 22-25, 27, and 28 were assigned on the basis of the spectral data of the photolysis products of the 13C-labelled diepoxyketone[6,6-dimethyl-13C2]-3 and by X-ray analysis of the compounds 24 and 35, the latter being the p-nitrobenzoate of 22.

Zusätzliches Material: 2 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19850680517

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4

Digitale Medien

Unusual Acid-Catalyzed Rearrangement of Two α,α′-Diimino-oximesDedicated to Prof. Albert Eschenmoser on the occasion of his 60th birthday (1985)

Fuhrer, Walter ; Rasetti, Vittorio ; Rihs, Grety

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 68 (1985), S. 1235-1242

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: 2-[2-(Alkylimino)-2-phenylethylidene]pyrrolidines (vinamidines, 3-6) were obtained either via activation of the corresponding vinologous amide 1 with Meerwein salt and subsequent treatment of the intermediate 2 with an amine, or more directly by acid-catalyzed condensation of the Schiff bases derived from acetophenone with 2-ethoxy-1-pyrroline. Nitrosation of these vinamidines led to α,α′-diimino-oximes. In two cases (10, 11), these oximes underwent acid-catalyzed rearrangement with formation of a 5,6,7,8-tetrahydroimidazo[1,2-a]pyridine ring system (12, 13). X-Ray analysis of one of these products (13) and also of one of the vinamidine salts (6) are presented.

Zusätzliches Material: 2 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19850680520

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5

Digitale Medien

Konfigurationsbestimmung von geometrischen Isomeren mittels selektiver 13C{1H}-NOE-Differenzspektroskopie (1986)

Neidlein, Richard ; Kramer, Walter ; Ullrich, Volker

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 69 (1986), S. 898-904

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: Application of Selective 13C{1H}-NOE Difference Spectroscopy in Determination of the Configuration of (Z)/(E)-IsomersHeteronuclear 13C{1H}-NOE studies have been performed to elucidate the configuration at the imino double bond in N,N′-Dicyanoquinonediimines. Selective low-power irradiation of the neighbouring ring protons in compounds 1-5 increases the signal intensities of CN as well as of the imino-C-atoms in the 13C-NMR spectra. The increase of signal intensity can easily be detected by the difference spectroscopy. The results of this investigation are in good agreement with a recently published study on the stereochemistry of N,N′-Dicyanoquinonediimines, based on the interpretation of 13C-chemical shifts.

Zusätzliches Material: 4 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19860690417

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6

Digitale Medien

Perimeter-Type Structures in Charged [4n + 2] Annuleno [4n + 2] annulenes. The Importance of the Frontier-Orbitals (1986)

Huber, Walter ; Müllen, Klaus ; Schnieders, Christoph ; [weitere]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 69 (1986), S. 949-954

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: The tetra(tert-butyl)[14]annuleno[14]annulene 1 is transformed, via alkali metal reduction, into its radical monoanion, dianion, radical trianion, and tetraanion. The paramagnetic species are characterized by ESR and ENDOR spectroscopy and the diamagnetic species by 1H- and 13C-NMR spectroscopy. Well-resolved ESR and NMR spectra can only be obtained, if the reduction is carefully monitored. For the interpretation of the data, the ions derived from the structurally related [14]- and [22]annulenes 3 and 5 as well from the tetra(tert-butyl)[14]annuleno[18]annulene 2 serve as suitable model compounds. While the behavior of the neutral annulenoannulene 1 is governed by that of the [14]annulene-subunit, the corresponding ionic systems can best be described as macrocyclic perimeters. This outcome can be rationalized by the nodal properties of the frontier MO's.

Zusätzliches Material: 2 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19860690423

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7

Digitale Medien

Stoffwechselprodukte von Mikroorganismen. 237. Mitteilung236. Mitt.: [1]. (2S, 3R, 4R, 6R)-2,3,4-Trihydroxy-6-methylcyclohexanon aus zwei Actinomyceten-Stämmen (1986)

Müller, André ; Keller-Schierlein, Walter ; Bielecki, Jacek ; [weitere]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 69 (1986), S. 1829-1832

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: (2S, 3R, 4R, 6R)-2,3,4-Trihydroxy-6-methylcyclohexanone from Two Strains of ActinomycetesA tetrazolium-blue positive compound was isolated from two strains of acinomycetes. Its constitution and relative configuration 1 were determined by spectroscopic methods, and the absolute configuration by degradation to (+)-(R)-methylsuccinic acid.

Zusätzliches Material: 1 Tab.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19860690807

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8

Digitale Medien

Stoffwechselprodukte von mikroorganismen. 238. Mitteilung237. Mitt.: [1].. Isolierung und Strukturaufklärung von Differolid (1986)

Keller-Schierlein, Walter ; Bahnmüller, Urs ; Dobler, Max ; [weitere]

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 69 (1986), S. 1833-1836

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: Isolation and Structure Elucidation of DifferolideFrom cultures of a new actinomycete, Streptomyces aurantiogriseus (PREOBRAZHENSKAYA 1975), strain Tü 3149, a compound C12H12O4 was isolated, which enhances the formation of aerial mycelium and spores of Streptomyces glaucescens. The structure determined by X-ray diffraction studies was that of racemic dilactone 1 ((±)-differolide).

Zusätzliches Material: 1 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19860690808

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9

Digitale Medien

Synthese von 2-Hydeoxy-3-methyl-2-hexen-4-olid (1987)

Stach, Hans ; Huggenberg, Walter ; Hesse, Manfred

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 369-374

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: Synthesis of 2-Hydroxy-3-methyl-2-hexen-4-olidThe title compound 13a, a substance used in food-flavoring, was synthesized in 89% overall yield, starting from methyl 2-hydeoxy-3-butenoate (3a). The key step in this transformation is the isomerization of the C=C bond in 3a which yielded methyl 2-oxobutanoate as an intermediate. The latter underwent a self-condensation yielding 2-hydroxy-4-(methoxycarbonyl)-3-methyl-2-hexen-4-olid (11a), which, after hydrolysis and decarboxylation, gave 13a. In addition, the syntheses of five other compounds related to 13a are reported.

Zusätzliches Material: 1 Tab.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19870700214

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10

Digitale Medien

Diels-Alder-Reaktionen von 2,4-Bis{[(tert-butyl)dimethylsilyl]oxy}-3-aza-1,3-pentadien mit HeterodienophilenTeil der geplanten Dissertation von U. R. [1]. (1987)

Ried, Walter ; Reiher, Uwe ; Jan, W. Bats

New York, NY : Wiley-Blackwell

Helvetica Chimica Acta 70 (1987), S. 1255-1260

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ISSN: 0018-019X

Schlagwort(e): Chemistry ; Organic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Beschreibung / Inhaltsverzeichnis: Diels-Alder Reactions of 2,4-Bis{[(tert-Butyl)dimethylsilyl]oxy}-3-aza--1,3-pentadien with HeterodienophilesThe 2,4-bis{[(tert-butyl)dimethylsilyl]oxy}-3-aza-1,3-pentadien(2) reacts via the Diels-Alder adducts 3, 6a-c, and 8a, b, which cannot be isolated, giving the triazines 4, 7a-c, and the oxadiazines 9a, b. The hydrolysis of 4 in MeOH affords the N-acetyl-acetamid derivative 5. The formula of 9a is proven by an X-ray-structure analysis.

Notizen: No. Abstract.

Zusätzliches Material: 1 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/hlca.19870700504

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