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  • 11
    Electronic Resource
    Electronic Resource
    [(n-C4H9)4N]2Mo5Cl13  -  eine Verbindung mit der Baugruppe [Mo5Cl8i]Diese Arbeit wurde von der Deutschen Forschungsgemeinschaft und dem Fonds der Chemischen Industrie unterstützt. Wir danken Herrn Dr. K. Peters für die Messungen am Vierkreisdiffraktometer. (1975)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 87 (1975), S. 594-595 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19750871613
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  • 12
    Electronic Resource
    Electronic Resource
    Periodische Potentialflächen in KristallstrukturenIn memoriam Wilhelm Klemm (1986)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 98 (1986), S. 111-113 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19860980133
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  • 13
    Electronic Resource
    Electronic Resource
    Ring Expansion of Heterocyclic Ketene N,X-Acetals and 2-Alkylidenedihydroindoles with Methanesulphonyl Azide by [3 + 2] Cycloaddition and Subsequent Extrusion of Molecular Nitrogen (1996)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1996 (1996), S. 1541-1549 
    Details
    ISSN: 0947-3440
    Keywords: [3 + 2] Cycloaddition ; Ketene N,X-acetals, cyclic ; Azides, electrophilic ; Amidines, cyclic N-sulphonyl- ; Ring expansion of heterocycles ; 1,2-Shift of carbon, nitrogen, sulphur, or selenium ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methanesulphonyl azide (2) reacts readily with isolated cyclic ketene N,X-acetals of type 1, viz. 10a, d, 15b, d, and 22a-c, or those that are generated in situ by deprotonation of the corresponding 2-alkylbenzazolium tetrafluoroborates, i.e. 14a → 15a, 14b → 15b, and 18 → 19. Ring-expanded products are formed by extrusion of molecular nitrogen from intermediate labile [3 + 2] cycloadducts 3 with concomitant 1,2-shift of N (route A1 → 12, 24) or X (route A2 → 16, 20, 21). In addition, 3 may undergo [3 + 2] cycloreversion into N-sulphonylimine 5 and diazoalkane 6 (route B → 13, 17, 25). The configurations of the cyclic N-sulphonylamidines 16b and 21b, the N-sulphonylimine 24 and the N-sulphonylamine 27 are elucidated by means of X-ray diffraction analyses. The ratio of the (useful) ring-expansion reactions vs. the unwanted formation of 5 + 6 is hardly influenced by the solvent employed and temperature of the experiment but strongly by the nature of the potential migrating atom and the substituents at the α-carbon atom.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199619961008
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  • 14
    Electronic Resource
    Electronic Resource
    Transannular Ring Expansion in the Acid-Catalyzed Reaction of the Oxirane Derived from Spirocyclopropane-Substituted Bicyclo[2.2.2]oct-2-ene (1987)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 705-712 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Das durch [4+2]-Cycloaddition aus Methylencyclopropan und 1,3-Cyclohexadien zugängliche Spiro[bicyclo[2.2.2]oct-5-en-2,1′-cyclopropan] (1) wurde zu den exo- und endo-Epoxiden 2 epoxidiert. Das exo-Epoxid 2 reagierte mit Trifluoressigsäure unter transannularer Ringerweiterung des Spirocyclopropansubstituenten mit (oder ohne) Gerüstumlagerung des bicyclischen Systems zu dem 7,9-disubstituierten Homobrendan 7b (Hauptprodukt) und zu dem 2,6-disubstituierten Isotwistan 7a (Nebenprodukt). 1,2-trans-Additionsprodukte wurden nicht nachgewiesen, im Gegensatz zur Reaktion von 1 mit Arensulfenylchlorid, in der aber keine Umlagerungsprodukte beobachtet wurden. Das Isomerengemisch der vier gebildeten 1,2-trans-Additionsprodukte bewies den fehlenden Einfluß des Spirocyclopropansubstituenten auf die Regio- und Stereoselektivität, die im Fall des Bicyclo[2.2.2]oct-2-en-5-on mit Arensulfenylchlorid nachgewiesen werden konnte. Das Hauptprodukt war (exo-5,endo-6)-6-Chlor-5-(p-tolylthio)-bicyclo[2.2.2]octan-2-on (5a), dessen Stereochemie über das entsprechende Sulfoxid 6a mittels Röntgenstrukturanalyse ermittelt wurde.
    Notes: Spiro[bicyclo[2.2.2]oct-5-ene-2,1′-cyclopropane] (1), obtained by [4+2] cycloaddition of 1,3-cyclohexadiene to methylenecyclopropane, was epoxidized to give the exo and endo epoxides 2. The exo epoxide 2 gave with trifluoroacetic acid the 7,9-disubstituted homobrendane 7b (main product) and the 2,6-disubstituted isotwistane 7a (minor product) via transannular ring expansion of the spirocyclopropane substituent with and without skeletal rearrangement of the bicyclic ring system, respectively. No 1,2-trans adducts were observed, as is the case in the reaction of the spiroalkene 1 with arenesulfenyl chloride, which in turn gave no ring-expanded products. The fact that an isomeric mixture of all four possible 1,2-trans adducts 4 were obtained, proves that the spirocyclopropane substituent promotes neither regio- nor stereoselectivity. In contrast, bicyclo[2.2.2]oct-2-en-5-one proceeded with arenesulfenyl chloride regio- and stereoselectively, leading to (exo-5,endo-6)-6-chloro-5-(p-tolylthio)bicyclo[2.2.2]octan-2-one (5a). The stereochemistry of the latter was established by means of X-ray analysis of its sulfoxide derivative 6a.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19871200507
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  • 15
    Electronic Resource
    Electronic Resource
    1,3-Dipolar Cycloadditions with the Keto- and Spirocyclopropane-Substituted Norbornenes Bicyclo[2.2.1]hept-5-en-2-one and Spiro[bicyclo[2.2.1]hept-5-ene-2,1′-cyclopropane] (1987)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 695-703 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Die keto- und spirocyclopropansubstituierten Norbornene K und S wurden mit Diazomethan (1), Diphenyldiazomethan (2), Phenylazid (3) und Benzonitriloxid (4) umgesetzt und führten zu den korrespondierenden regioisomeren 1,3-Cycloaddukten K-2a, b bis K-4a, b und S-1a, b bis S-4a, b, die in ca. 1:1-Verhältnissen vorlagen. Die Keto- bzw. Spirocyclopropansubstituenten beeinflussen die π-Systeme dieser Norbornene nur schwach, so daß die Regioselektivität in der Cycloaddition mit den hier untersuchten 1,3-Dipolen nicht nachweisbar war. Kombination von NOE- und 1H-NMR-Spektroskopie sowie Röntgenstrukturanalyse war notwendig zur Strukturzuordnung der Regioisomeren.
    Notes: The keto- and spirocyclopropane-substituted norbornenes K and S, respectively, were submitted to 1,3-dipolar cycloaddition with diazomethane (1), diphenyldiazomethane (2), phenyl azide (3), and benzonitrile oxide (4) leading in equal proportions to the corresponding regioisomers of the cycloadducts K-2a, b through K-4a, b and S-1a, b through S-4a, b. The keto and spirocyclopropane substituents perturb the π systems of these norbornenes too weakly to sense any significant regioselectivity for the 1,3-dipoles employed here. A combination of NOE differential 1H-NMR spectroscopy and X-ray analysis was essential to assign the structures of these regioisomers.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19871200506
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  • 16
    Electronic Resource
    Electronic Resource
    Transannular Ring Expansion in Electrophilic Reactions of Spirocyclopropane-Substituted Norbornene and Its Oxirane and Azirane Derivatives (1987)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 521-529 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Transannulare Ringerweiterung von Spirocyclopropan-substituierten Norbornenen sowie deren Oxiran- und Aziranderivaten in elektrophilen ReaktionenAus dem Spironorbornen N entstanden mit Toluolsulfenylchlorid als Nebenprodukt das 1,2-trans-Additionsprodukt N-1a und als Hauptprodukte die disubstituierten Brendane N-2a,b. Das Dispironorbornen D lieferte nur Spuren des 1,2-trans-Additionsprodukts D-1a und fast ausschließlich das umgelagerte, disubstituierte Brendan D-2a. Andererseits führte das Oxiran O unter Einwirkung von Trifluoressigsäure zu den Hydroxyestern O-2a,b, die zu den entsprechenden Diolen O-2c,d hydrolysiert wurden. Auch das Aziran A lieferte die Aminoester A-2a,b, die zu den entsprechenden Aminoalkoholen A-2c,d hydrolysiert wurden. Weder in der säurekatalysierten Reaktion des Oxirans noch in der des Azirans konnten 1,2-trans-Additionsprodukte beobachtet werden. Die 2,6-disubstituierten Brendane (Nebenprodukte) wurden durch direkte transannulare Ringerweiterung der Spirocyclopropaneinheit im Kation 3 gebildet, das aus elektrophilem Angriff auf die Norbornenderivate resultierte. Die 3,8-disubstituierten Brendane (Hauptprodukte) entstanden durch Gerüstumlagerungen in den Kationen 3 mit nachfolgenden transannularen Ringerweiterungen. Kristallstrukturanalysen der Sulfone N-1b und N-2c sowie des 3,8-Diols O-2d bewiesen zweifellos deren Strukturen.
    Notes: The spironorbornene N gave on treatment with toluenesulfenyl chloride as minor product the 1,2-adduct N-1a and as major products the disubstituted brendanes N-2a,b. The dispironorbornene D gave trace amounts of the 1,2-adduct D-1a and essentially exclusively the skeletally rearranged disubstituted brendane D-2a. On the other hand, the oxirane O led on treatment with trifluoroacetic acid to the hydroxy esters O-2a,b which were hydrolyzed to give the respective diols O-2c,d, while the azirane A afforded the amino esters A-2a,b, which were hydrolyzed to yield the respective amino alcohols A-2c,d. Neither for the oxirane nor for the azirane were 1,2-adducts observed in these acidcatalyzed reactions. The 2,6-disubstituted brendanes (minor products) were formed via direct transannular ring expansion of the spirocyclopropane moiety in the bridged cations 3 that result from electrophilic attack on the norbornenes. Alternatively, the bridged cations 3 first underwent skeletal rearrangement and subsequent transannular ring expansion led to the 3,8-disubstituted brendanes (major products). X-ray analysis was essential to elucidate rigorously the structures of the sulfones N-1b and N-2c and the 3,8-diol O-2d.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19871200411
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  • 17
    Electronic Resource
    Electronic Resource
    Concave Reagents, 71) Concave Benzoic Acids (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 397-402 
    Details
    ISSN: 0009-2940
    Keywords: Concave acid ; Macrocycle ; m-Terphenyl ; Benzoic acids ; Acidity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Based on m-terphenyl units, concave benzoic acids 11a and 12a were prepared via the 2,6-diarylbenzoic acid 7a. Bromination of 7a with NBS gave 9, and cyclization of 9 with dithiols 10 led to the bimacrocyclic concave acids 11a and 12a. Their relative acidities were determined by photometric titrations in ethanol, and the three-dimensional structure of 11a was determined by X-ray analysis.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240225
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  • 18
    Electronic Resource
    Electronic Resource
    Mehrstufige reversible Redoxsysteme, LV. Kristallstruktur des CT-Komplexes 2,5-Me2-DCNQI/TTF aus N,N′-Dicyan-2,5-dimethyl-1,4-benzochinondiimin und Tetrathiafulvalen sowie des Acceptors 2,5-Me2-DCNQI (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2001-2004 
    Details
    ISSN: 0009-2940
    Keywords: π-Acceptor ; Charge-transfer complex ; 1,4-Benzoquinone diimine, N,N′-dicyan, 2,5-dimethyl- ; Tetrathiafulvalene ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Multi-Step Redox Systems, LV. - Crystal Structure of the CT Complex 2,5-Me2-DCNQI/TTF from N,N′-Dicyano-2,5-dimethyl-1,4-benzoquinone Diimine and Tetrathiafulvalene and of the Acceptor 2,5-Me2-DCNQIThe crystal structure of the title compound is described and discussed in terms of a neutral non-conducting mixed-stack CT complex. X-ray data for the acceptor 2,5-Me2-DCNQI are given for comparison.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240920
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  • 19
    Electronic Resource
    Electronic Resource
    2,3-Dioxo-2,3-dihydrofurane, 2 Vielseitige Synthese von 2,3-Dioxo-2,3-dihydrofuranen und Alkylidenbutenoliden. - Kristall- und Molekülstruktur von 5-(4-Chlorphenyl)-4-methoxycarbonyl-2,3-dioxo-2,3-dihydrofuran (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2289-2295 
    Details
    ISSN: 0009-2940
    Keywords: 2,3-Dihydrofuran-2,3-diones ; Alkylidenebutenolides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2,3-Dioxo-2,3-dihydrofurans, 2. - Versatile Synthesis of 2,3-Dioxo-2,3-dihydrofurans and Alkylidenebutenolides. - Crystal and Molecular Structure of 5-(4-Chlorophenyl)-4-methoxycarbonyl-2,3-dioxo-2,3-dihydrofuranReaction of the 1,3-dicarbonyl compounds 5a - f, containing at least one α-hydrogen atom in R1 and/or R2, with oxalyl halides 2 in the presence of magnesium chloride yields regioand on the whole stereospecifically the previously unknown (Z)-alkylidenebutenolides 7a - f. Similarly, the 4-alkoxycarbonyl-5-aryl-2,3-dioxo-2,3-dihydrofurans 6g - p are obtained (X-ray structure of 61) starting from 3-aryl-3-oxo-propanoates 5g - p. Correspondingly, malondiamides 8a, b, e, f react with oxalyl chloride (2a) to give the 2,3-dioxo-2,3-dihydrofurans 9a,b and 11a,b. Having mono(alkyl/aryl)amino substituents in position 5, compounds 11a,b spontaneously tautomerize to give imino enols 12a,b. Hydrochlorides 10a,b are formed on treatment of malondiamides 8c,d with oxalyl chloride (2a). In the case of the β-oxocarboxamides 13/14 the substituents at the amide nitrogen atom control the regiochemistry. Starting from 13 (R2 = Ph) and oxalyl chloride (2a), 4-acetyl-5-diphenylamino-2,3-dioxo-2,3-dihydrofuran (15) is formed regiospecifically, whereas under the same conditions 13/14 (R2 = CH2Ph) afford 4-dibenzylcarbamoyl-5-methyl/phenyl-2,3-dioxo-2,3-dihydrofurans 16/17. Furanone 16 spontaneously enolizes to give 4-dibenzylcarbamoyl-3-hydroxy-5-methylene-2(5H]-furanone (18). Similarly, the N-monosubstituted β-oxocarboxamides 19a,b readily react regiospecifically with oxalyl chloride (2a) to give via the 2,3-dioxo-2,3-dihydrofurans 20a,b the imino enols 21a,b.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911241022
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  • 20
    Electronic Resource
    Electronic Resource
    2,4,6,8-Tetraphenylbarbaralan - ein orangeroter, thermochromer Kohlenwasserstoff ohne Chromophor[1,2] (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1047-1060 
    Details
    ISSN: 0009-2940
    Keywords: Bicyclo[3.3.1]nonane, derivatives of ; 2-Oxatwistane, derivative of ; 2-Oxatricyclo[4.4.0.03,8]decane, derivative of ; Phenyllithium-cerium(III) chloride reagent ; 1,2-Addition to carbonyl groups ; Transannular reaction ; Dipotassium tetraphenylbicyclo[3.3.1]nonadienediide by deprotonation with butylpotassium ; Barbaralane, 2,4,6,8-tetraphenyl-, by oxidation of dipotassium tetraphenylbicyclo[3.3.1]nonadienediide with 1,2-dibromo-ethane ; Thermochromism ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2,4,6,8-Tetraphenylbarbaralane - an Orange-Red, Thermochromic Hydrocarbon Devoid of a Chromophore[1,2]The diphenylbicyclo[3.3.1]nonanedione 6 adds phenylcerium-(III) dichloride to afford a high yield of the triphenyl-2-oxa-twistanol 8. In contrast, phenyllithium yields a mixture of tri-phenylhydroxyketone exo-7, tetraphenylbicyclo[3.3.1]nona-nediol 9, and 8. The latter is dehydrated by sulfuric acid in acetic acid to produce the triphenylbicyclo[3.3.1]nonenone 10 in almost quantitative yield. Addition of phenylcerium(III) dichloride to 10 affords a 3:2 mixture of the tetraphenylbicy-clo[3.3.1]nonenols exo- and endo-11 which may be separated by chromatography. Dehydration of the mixture yields quantitatively the tetraphenyldiene 12. On treatment with an excess of butylpotassium in pentane, 12 is converted to the deep violet, crystalline dipotassium salt 17 which may be purified by reprecipitation from its tetrahydrofuran solution with pentane. When the solution of 17 in tetrahydrofuran is slowly added to an excess of 1,2-dibromoethane at -60°C, the dianion is immediately oxidized to produce the tetraphenylbarbara-lane 4 which is isolated in 30% yield as orange-red crystals after chromatography. - The structures of the new compounds are based on spectroscopic evidence and X-ray diffraction analyses of 4, 8, exo-11, and 12. The conformations in solution are inferred on the basis of vicinal proton coupling constants and a comparison with coupling constants calculated with the aid of the Karplus equation from torsional angles obtained by X-ray diffraction analyses. The conformation of exo-11 in solution closely resembles that present in the crystal. - While the barbaralane 4 exists as a pair of very rapidly rearranging degenerate valence tautomers in solution, the degeneracy is lifted in the crystal lattice. As a result, the crystal consists of two rapidly rearranging but non-equivalent valence tautomers in a ratio of 9:1 as estimated from the apparent atomic distance C2-C8 of 4 and the C2-C8 bond length of the model barbaralane 18. - The orange-red colour of 4 in the crystal and in solution results from a pronounced shoulder in the UV/Vis spectrum at 430 nm, the intensity of which strongly depends on the temperature. Thus, 4 is the first barbaralane which exhibits colour though it is lacking a classical long-wavelength chromophore.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260427
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