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  • 1
    Electronic Resource
    Electronic Resource
    A New Method for the Preparation of (E)-3-Acylprop-2-enoic AcidsPresented in part at the autumn meeting of the Swiss Chemical Society in Bern on October 21, 1988.Dedicated to Prof. R. E. Ireland on the occasion of his 60th birthday (1989)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 117-122 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new method for the preparation of (E)-3-acylprop-2-enoic acids ( = (E)-3-acylacrylic acids) of type II via acid-catalyzed isomerization of the corresponding 3-acylprop-2-ynal acetals of type I (Scheme 1) has been found. The described reaction gives a rapid and quite general access to these compounds known to exhibit a number of interesting biological activities. Some studies toward the elucidation of the reaction mechanism have been made, and a hypothetical mechanism is proposed.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19890720115
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  • 2
    Electronic Resource
    Electronic Resource
    Dediazoniations of arenediazonium ions. Part 26Part 25: See [1].Presented in part at the 8th IUPAC Conference on Physical Organic Chemistry, Tokyo, 1986. Influence of Substituents on the Formation of Benzoic Acids in Reactions of Aryl-Cation-Type Intermediates with CO (1988)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 71 (1988), S. 515-520 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The N2-molecule-aryl-cation pair formed as the first intermediate in dediazoniations of arenediazonium ions can be trapped with CO in H2O with formation of the corresponding arenecarboxylic acids. This reaction is considered as a model for the reverse of dediazoniation, since CO is isoelectronic with N2. The evaluation of the yields of arenecarboxylic acids formed from substituted benzenediazonium ions using Taft's dual substituent parameter treatment demonstrates that the field reaction constant pF and the resonance reaction constant pR are positive and negative, respectively, as expected for a reaction which corresponds electronically to the addition of N2 to aryl cations.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19880710303
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  • 3
    Electronic Resource
    Electronic Resource
    The molecular and electronic structure of dipiperidinosquaraine (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 2118-2126 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Molekulare und elektronische Struktur von DipiperidinoquadratainDipiperidinoquadratain (9) kristallisiert im orthorhombischen Gitter, Raumgruppe Pnab, mit 4 Molekülen in einer Elementarzelle mit den Abmessungen a = 7.1798(9), b = 9.5362(8) und c = 18.788(2) Å. Das Molekül liegt auf einem Symmetriezentrum, d.h. der Vierring (C — C = 1.456(1) Å) ist genau planar; die Stickstoff- und Sauerstoffatome sind fast mit dem Ring coplanar, mit C — O = 1.2396(7) und C — N = 1.3112(7) Å. Sowohl die experimentellen als auch die theoretischen Daten zeigen beachtliche C — N- und C — O-π-Bindungen, aber nur eine geringfügige C — C-π-Bindung im Quadratainsystem. Die Berechnungen ergeben starke 1,3-abstoßende Wechselwirkungen im Vierring. Ringfaltung, ein sonst üblicher Mechanismus bei der Vermeidung solcher Abstoßungen, wird hier durch die starke C — N-π-Bindung verhindert.
    Notes: Dipiperidinosquaraine (9) crystallizes in the orthorhombic system, space group Pnab, with four molecules in a cell of dimensions a = 7.1798(9), b = 9.5362(8), and c = 18.788(2) Å. The molecule is located over a center of symmetry, so the four-membered ring (C - C = 1.456(1) Å av) is exactly planar; the nitrogen and oxygen atoms are nearly coplanar with the ring, with C — O = 1.2396(7) and C — N = 1.3112(7) Å. Both experimental and theoretical evidence indicates the presence of considerable C — N and C — O π-bonding, but only a small amount of C — C π-bonding in the squaraine system. The calculations indicate the presence of strong 1,3-repulsive interactions within the four-membered ring. Ring puckering, which is a common mechanism to alleviate these repulsions, is prevented here by the extensive C — N π-bonding.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851180531
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  • 4
    Electronic Resource
    Electronic Resource
    Oxidative Addition einer C—H-Bindung an ein zweifach koordiniertes Phosphenium-Kation (1986)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 119 (1986), S. 3208-3211 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oxidative Addition of a C—H Bond at a Two-coordinated Phosphenium CationReaction of ArP(Cl)SAr (1) [Ar = 2,4,6-(t-Bu)3C6H2] with AgSbF6 in ether at 0°C affords the compound . This exists in two different forms 2a and 2b. Form 2a is a phosphonium cation. In the IR and 31P{1H} NMR spectra of 2b an interaction between the and SbF6- units is observed. 2a and 2b are in an equilibrium which depends on the temperature. 2 is formed via the unstable (arylthio)-phosphenium cation with a σ2,λ3-phosphorus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19861191027
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  • 5
    Electronic Resource
    Electronic Resource
    Synthese und Strukturanalyse von 1,2,3,4-Tetrahydrobenzo[g]chinoxalin-5,10-chinonen (1987)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 1125-1132 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Structure Analysis of 1,2,3,4-Tetrahydrobenzo[g]-quinoxaline-5,10-quinones2,3-Diamino-1,4-dihydroxynaphthalene reacts with different aromatic aldehydes to give 2,3-disubstituted 1,2,3,4-tetrahydrobenzo[g]quinoxaline-5,10-quinones (1-7). In the course of the reaction a new C-C bond is formed stereoselectively. The yields are in the range of 80%. The corresponding benzoquinoxalinequinone 8 with different substituents in 2- and 3-positions is formed by a two-step preparation. Oxidation of these trans products leads to the benzo[g]quinoxaline-quinones and subsequent catalytic reduction yields the cis isomers. The structures and the configuration of 1 and 9 were determined by X-ray crystallography. The conformations of the new heterocycles are discussed with respect to the results obtained in solid and liquid phase.
    Notes: 2,3-Diamino-1,4-naphthohydrochinon reagiert mit Benzaldehyden unter Cyclisierung und Protonenwanderung stereoselektiv zu 2,3-disubstituierten 1,2,3,4-Tetrahydrobenzo[g]chinoxalin-5,10-chinonen (1-7) (Ausbeuten ca. 80%). Benzochinoxalin-5,10-chinon 8, das in 2- und 3-Stellung unterschiedlich substituiert ist, wird durch eine zweistufige Reaktion erhalten. Die Anordnung der Phenylreste in 2- und 3-Stellung wird für 1 und 9 durch Röntgenstrukturanalysen ermittelt; beide Spezies liegen in trans-Konfiguration vor. Durch Oxidation zu Benzo [g]chinoxalin-chinonen und anschließende katalytische Hydrierung werden cis-Isomere erhalten. Unter Berücksichtigung der Ergebnisse aus den Kristallstruktur- und NMR-Untersuchungen werden verschiedene Konformationen diskutiert.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19871200709
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  • 6
    Electronic Resource
    Electronic Resource
    GeH3-substituierte Carbonylmetallate und Carbonyl(cyclopentadienyl)-metallate mit V, Nb, Cr, Mo, W, Re, Co und Ni Präparative und röntgenographische Untersuchungen (1988)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 1427-1433 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: GeH3-Substituted Carbonyl Metallates and carbonyl (cyclopentadienyl) Metallates with V, Nb, Cr, Mo, W, Re, Co, and Ni. - Preparative and X-Ray InvestigationsKGeH3 reacts with different metal carbonyls and cyclopentadienyl-metal carbonyls with substitution of one CO group and formation of GeH3-substituted carbonyl metallates [M(CO)3(η5-C5H5)GeH3]⊖ [M: V (1), Nb (2)], [M(CO)5GeH3]⊖ [M: Cr (3), Mo (4), W (5)], [Re(CO)2(η5-C5H5)GeH3]⊖ (6), [Ni(CO)3-GeH3]⊖ (7), [Ni(CO)2(PPh3)GeH3]⊖ (8), and [Co(CO)(η5-C5R5)-GeH3]⊖ [R: H (9), Me (10)]. The K salts thus obtained are very air-sensitive and in most cases rather thermolabile. Reaction with [PPh4]Br in aqueous solution yields the somewhat more stable and better crystallizable phosphonium salts. They have been characterized by elemental analysis, spectroscopy (IR, 1H-NMR), and X-ray methods in the cases of 1, 4, 5, 7, and 8. Their short Ge-metal distances are remarkable, although disorder problems prevented a higher precision in most cases.
    Notes: KGeH3 reagiert mit verschiedenen Metallcarbonylen und Cyclopentadienylmetallcarbonylen unter Substitution einer CO-Gruppe und Bildung von GeH3-substituierten Metallaten [M(CO)3(⊖5-C5H5)GeH3]⊖ [M: V (1), Nb (2)], [M(CO)5GeH3]⊖ [M: Cr (3), Mo (4), W (5)], [Re(CO)2(η5-C5H5)GeH3]⊖ (6), [Ni(CO)3GeH3]⊖ (7), [Ni(CO)2(PPh3)GeH3]⊖ (8) und [Co-(CO)(η5R5)GeH3]⊖ [R: H (9), Me (10)]. Die so gebildeten K-Salze sind sehr luftempfindlich und meist ziemlich thermolabil. Umsetzung mit [PPh4]Br in wäßriger Lösung ergibt die etwas stabileren und besser kristallisierenden Phosphonium-Salze. Sie wurden elementaranalytisch und spektroskopisch (IR, 1H-NMR) charakterisiert und im Falle von 1, 4, 5, 7 und 8 auch röntgenographisch untersucht. Auffallend sind ihre kurzen Ge-Metall-Abstände, obgleich wegen Fehlordnungsproblemen meist keine große Genauigkeit erreichbar war.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19881210812
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  • 7
    Electronic Resource
    Electronic Resource
    Metal complexes with tetrapyrrole ligands, LIV: Synthesis, spectra, structure, and redox properties of cerium(IV) Bisporphyrinates with identical and different porphyrin rings in the sandwich system (1989)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 2219-2228 
    Details
    ISSN: 0009-2940
    Keywords: Bisporphyrinates, cerium(IV) ; Lanthanoid porphyrins ; Metalloporphyrins ; Tetrapyrrole complexes, sandwich-like ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metallkomplexe mit Tetrapyrrol-Liganden, LIV.  -  Synthese, Spektren, Struktur und Redox-Chemie von Cer(VI)-Bisporphyrinaten mit gleichen und verschiedenen Porphyrin-Ringen im Sandwich-SystemWeitere symmetrische Cer(IV)-Bisporphyrinate werden aus Cer-(III)-acetylacetonat und Tetraphenylporphyrin, Tetra-p-chlorphenylporphyrin, und Hexadecahydrotetrabenzporphyrin hergestellt. Aus dem letzteren Porphyrin entsteht auch ein Biscer(III)-Tripeldecker; ein solcher bildet sich als einziges Produkt aus Octamethylporphyrin. Aus einem Gemisch zweier verschiedener Porphyrine, nämlich Octaethylporphyrin [H2(OEP)], und Tetraphenyl-porphyrin [H2(TPP)] oder Tetra-p-chlorphenylporphyrin [H2-(TClP)] erhält man neben den symmetrischen Spezies Ce(OEP)2 und Ce(TPP)2 die unsymmetrischen („gemischten“) Doppeldecker Ce(OEP)(TPP) oder Ce(OEP)(TClP), die verschiedene Porphyrin-Ringe im Sandwich-System haben und sich trennen lassen. Die Kristallstrukturanalyse von Ce(OEP)(TPP) zeigt CeIV in quadratisch-antiprismatischer Umgebung der Pyrrol-N-Atome der Porphyrin-Ringe. Während die IR- und NMR-Spektren der unsymmetrischen Doppeldecker-Überlagerungen der Spektren, die einzelnen Ringe darstellen, zeigen ihre UV/VIS-Spektren und die cyclischen Voltammogramme, daß die zwei unterschiedlichen Porphyrin-Ringe sich wie ein gemeinsames π-Elektronensystem verhalten. Die Darstellung der π-Kation-Radikal-Salze [Ce(OEP)2]-ClO4 und [Ce(OEP)(TPP)]SbCl6 wird ebenfalls beschrieben. In letzterem scheint sich das Defektelektron bevorzugt im OEP-Ring aufzuhalten.
    Notes: Further symmetrical cerium(IV) bisporphyrinates are prepared from cerium(III) acetylacetonate and tetraphenylporphyrin, tetra-p-chlorophenylporphyrin, and hexadecahydrotetrabenzporphyrin. In the latter case, a biscerium(III) triple-decker is also found which is the only product in the case of octamethylporphyrin. From a mixture of two different porphyrins, namely octaethylporphyrin [H2(OEP)] and either tetraphenylporphyrin [H2(TPP)] or tetra-p-chlorophenylporphyrin [H2(TClP)], besides the symmetrical species Ce(OEP)2 and Ce(TPP)2, the unsymmetrical (“mixed”) double-deckers Ce(OEP)(TPP) or Ce(OEP)(TClP) are obtained which have different porphyrin rings in the sandwich system and can be separated by chromatography. The crystal structure analysis of Ce(OEP)(TPP) shows CeIV in a square-antiprismatic geometry of the pyrrole N atoms of the porphyrin rings. While the IR and NMR spectra of the unsymmetrical double-deckers are superpositions of the spectra of the individual rings, their UV/VIS spectra and cyclic voltammograms indicate that the two porphyrin rings behave as a common π-electron system. The preparation of the π-cation radical salts [Ce(OEP)2]ClO4 and [Ce(OEP)(TPP)]SbCl6 is also described. In the latter, the defect electron seems to reside preferentially in the OEP ring.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19891221203
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  • 8
    Electronic Resource
    Electronic Resource
    1-(2,2-Dimethylpropyl)-3,5-dimethylbenzol, ein unerwartetes Nebenprodukt (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 4006-4013 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 1-(2,2-Dimethylpropyl)-3,5-dimethylbenzene, an Unexpected Side ProductThe title compound 4 is formed in fair yield in addition to the oligomers of isobutene during synthesis of 3-tert-butyl-2,4-pentanedione (2) from 2,4-pentanedione (1) with tert-butylalcohol and perchloric acid in nitromethane. Acid-catalyzed condensation of 1 with isooctene 5 is discovered to be responsible for the formation of 4. This reaction yields other meta-neopentyl-substituted benzene derivatives (19, 20, 21) with several β-diketones.
    Notes: Bei der Synthese von 3-tert-Butylacetylaceton (2) aus Acetylaceton (1) und tert-Butylalkohol mit Perchlorsäure in Nitromethan entsteht neben den Oligomeren des Isobutens die Titelverbindung 4 in reichlicher Ausbeute. Für die Bildung wird die säurekatalysierte Kondensation von 1 mit Isoocten 5 ausfindig gemacht. Diese Reaktion führt auch mit anderen β-Diketonen zu meta-neopentyl-substituierten Benzolderivaten (19, 20, 21).
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851181013
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  • 9
    Electronic Resource
    Electronic Resource
    Notiz zur Autoxidation von 3-Alkyl-2,4-pentandionen (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 1271-1272 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Note on the Autoxidation of 3-Alkyl-2,4-pentanedionesAcetic acid (2) and 2,3-diketones (3) as well as 3-hydroxy-2-ketones (4) are formed as main products from 3-methyl- and 3-ethyl-2,4-pentanediones 1 under the influence of air.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851180341
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  • 10
    Electronic Resource
    Electronic Resource
    Synthesen mit Alkendiazoniumsalzen, IV. 1H-1,2,3-Triazole, 2-Diazoimine und Imidoester aus Alkendiazoniumsalzen mit primären Aminen, Hydrazinen und Hydroxylaminethern (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 2626-2634 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses with Alkenediazonium Salts, IV 1H-1,2,3-Triazoles, 2-Diazoimines, and Imido Esters from Alkenediazonium Salts and Primary Amines, Hydrazines, and Hydroxylamine EthersReaction of alkenediazonium salts 1 with „amines“ 2 (primary amines, hydrazines, hydroxylamine ethers) leads to 2-diazoimines 4, 1H-1,2,3-triazoles 6, and imido esters 8 and 9, respectively, depending on the substituents R. Condensation of 1-amino-1H-1,2,3-triazole 6Ceα with acetone yields hydrazone 13.
    Notes: Die Umsetzung von Alkendiazoniumsalzen 1 mit „Aminen“ 2 (primäre Amine, Hydrazine, Hydroxylaminether) führt in Abhängigkeit der Substituenten R zu 2-Diazoiminen 4, 1H-1,2,3-Triazolen 6 bzw. Imidoestern 8 und 9. Kondensation von 1-Amino-1H-1,2,3-triazol 6 Ceα mit Aceton liefert das Hydrazon 13.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851180706
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