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  • American Physical Society  (1,135)
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  • 1
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 472-474 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C/12C ratios of the carboxyl and methyl carbons of acetic acid were determined by two published methods, using the thermal decomposition of sodium acetate and calcium acetate respectively. Comparison of the results obtained on a variety of samples revealed a systematic disagreement of 4.0% between the two methods. The source of this discrepancy is shown to be a fractionation associated with the calcium acetate method.
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  • 2
    Publication Date: 2006-03-29
    Print ISSN: 1539-3755
    Electronic ISSN: 1550-2376
    Topics: Physics
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 24 (1985), S. 905-910 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 24 (1985), S. 1549-1572 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The binding of the antitumor agent CC-1065 to a variety of poly- and oligonucleotides was studied by electronic absorption, CD, and resistance to removal by Sephadex column chromatography. Competitive binding experiments between CC-1065 and netropsin were carried out with calf-thymus DNA, poly(dI-dC) · poly(dI-dC), poly(dI) · poly(dC), poly(rA) · poly(dT), poly(dA- dC) · poly(dG-dT), and poly(dA) · 2poly(dT). CC-1065 binds to polynucleotides by three mechanisms. In the first, CC-1065 binds only weakly, as judged by the induction of zero or very weak CD spectra and low resistance to extraction of drug from the polynucleotide by Sephadex chromatography. In the second and third mechanisms, CC-1065 binds strongly, as judged by the induction of two distinct, intense CD spectra and high resistance to extraction of drug from the polynucleotide, by Sephadex chromatography in both cases. The species bound by the second mechanism converts to that bound by the third mechanism with varying kinetics, which depend both on the base-pair sequence and composition of the polynucleotide. Competitive binding experiments with netropsin show that CC-1065 binds strongly in the minor groove of DNA by the second and third mechanisms of binding. Netropsin can displace CC-1065 that is bound by the second mechanism but not that bound by the third mechanism. CC-1065 binds preferentially to B-form duplex DNA and weakly (by the first binding mechanism) or not at all to RNA, DNA, and RNA-DNA polynucleotides which adopt the A-form conformation or to single-strand DNA. This correlation of strong binding of CC-1065 to B-form duplex DNA is consistent with x-ray data, which suggest an anomalous structure for poly(dI) · poly(rC), as compared with poly(rI) · poly(dC) (A-form) and poly(dI) · poly(dC) (B-form). The binding data indicate that poly(rA) · poly(dU) takes the B-form secondary structure like poly(rA) · poly(dT). Triple-stranded poly(dA) · 2poly(dT) and poly(dA) · 2poly(dU), which are considered to adopt the A-form conformation, bind CC-1065 strongly. Netropsin, which also shows a binding preference for B-form polynucleotides, also binds to poly(dA) · 2poly(dT) and occupies the same binding site as CC-1065. These binding studies are consistent with results of x-ray studies, which suggest that A-form triplex DNA retains some structural features of B-form DNA that are not present in A-form duplex DNA; i.e., the axial rise per nucleotide and the base tilt. Triple-stranded poly(dA) · 2poly(rU) does not bind CC-1065 strongly but has nearly the same conformation as poly(dA) · 2poly(dT) based on x-ray analysis. This suggests that the 2′-OH group of the poly(rU) strands interferes with CC-1065 binding to this polynucleotide. The same type of interference may occur for other RNA and DNA-RNA polynucleotides that bind CC-1065 weakly.
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  • 5
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Durch Kondensation von aliphatischen und aromatischen N-Acyl-D-glucosaminen mit Isonicotinsäurehydrazid wurde eine Anzahl [N-Acyl-D-glucosaminyl]-isonicotinsäurehydrazide hergestellt. Die erhaltenen Verbindungen stellen im allgemeinen ein Gemisch der α- und β-Formen dar und zeigen teils Aufwärts-, teils Abwärtsmutarotation. Die tuberkulostatische Wirksamkeit wird kurz erörtert.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 105 (1972), S. 1097-1110 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies on Glycoside Synthesis, IV. Novel Silver Salts in Glycoside SynthesisThe glykosylation of steroid alcohols (e.g. 4, and 9-12, R==OH) with cis-halogenoses in the presence of various silver salts was investigated. In many cases the silver salts of 2-, 3-, and 4-hydroxyalkanoic acids as well as of 1.3- and 1.4-dicarboxylic acids proved to be superior to the commonly used Ag2CO3 or Ag2O. Good yields (5, 7-12) were obtained in cases in which neighbouring group effects within the anion limit the formation of 1-O-acylglycoses in favour of glycoside formation. The reaction takes place most readily in diethyl ether and is well suited for the glycosylation of chemically sensitive alcohols.
    Notes: Bei der Glykosylierung von Steroidalkoholen (u.a. 4 und 9-12, R == OH) mit cis-Halogenosen in Gegenwart verschiedener Silbersalze erwiesen sich die von 2-, 3-und 4-Hydroxy-carbonsäuren sowie von 1.3- und 1.4-Dicarbonsäuren den üblichen Salzen in vielen Fällen als überlegen. Gute Ausbeuten (an 5, 7-12) wurden dann erhalten, wenn im Anion des Silbersalzes durch eine Nachbargruppenbeziehung die Bildung der 1-O-Acyl-glucose zugunsten der Glykosidbidung eingeschränkt ist. Die Reaktion verläuft in Diäthyläther am besten und ist besonders auch zur Glykosylierung von chemisch empfindlichen Alkoholen gut geeignet.
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  • 7
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Fragmentation Reactions of Carbonyl Compounds with Electronegative ß-Substituents, XXIII cis- and trans-4.4.8.8-Tetraalkyl-2.6-dioxabicyclo[3.3.0]octanes from 1.6-Bis(tosyloxy)-2.2.5.5-tetraalkyl-3.hexandionesDiketoditosylates 8 and 9a-c are prepared and reduced with NaBH4. 8 yields 16a and a cis-trans mixture of 23; 9a-c afford the tetrahydrofuranols 14a-c and the cis-2.6-dioxabicyclo[3.3.0]octanes 21a-c. 14a-c and 16a react with NaOH in methanol to form the pure trans-compounds 21a-c and 23. Solvolysis of 9a with excess NaOH in methanol leads to the tetrahydrofuranone 13a and to the bicyclo acetal 22a. Solvolysis of 9b with only 2 equivalents of NaOH yields thc intermediate 12, which can be isolated and converted to 13b and 22b.The trispiro compound 27 is isolated as an unexpected side product from the NaBH4-reduction of 9b.
    Notes: Die Diketo-ditosylate 8 und 9a-c werden dargestellt und mit NaBH4 reduziert. 8 liefert 16a und ein cis-trans-23-Gemisch, aus 9a-c werden die Tetrahydrofuranole 14a-c und die cis-2.6-Dioxa-bicyclo[3.3.0]octane 21a-c erhalten. 14a-c und 16a reagieren mit NaOH in Methanol zu den reinen trans-Verbindungen 21a-c und 23. Die Solvolyse von 9a mit überschüssigem NaOH in Methanol führt zu dem Tetrahydrofuranon 13a und dem bicyclischen Acetal 22a. Mit 2 Äquivv. NaOH kann aus 9b die Zwischenstufe 12 isoliert und erneut zu 13b und 22b umgesetzt werden.Als ungewöhnliches Nebenprodukt tritt bei der NaBH4-Reduktion von 9b die Trispiroverbindung 27 auf.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 108 (1975), S. 3336-3348 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Degenerate Valence Tautomerism of Tricarbonyl(oxepine)iron Compounds and the Crystal Structure Analysis of a Ketocarbene Fragmentation Product of 2,7-DimethyloxepineBenzene oxide/oxepine (1/2) on light-induced reaction with Fe(CO)5 gives benzene, phenole, and ca. 3% crystalline tricarbonyl(oxepine)iron (3). It was demonstrated by 1H n.m.r., that 3 undergoes a rapid degenerate valence isomerisation. 2,7-Dimethyloxepine on reaction with Fe(CO)5) leads to the formation of o-xylene, 2,6-dimethylphenol, 5% tricarbonyl(2,7-dimethyloxepine)iron (5), and ca. 1% hexacarbonyl[2-4-n:5-6-n-(7-oxo-3,5-octadiene-2,2-diyl)]diiron (Fe - Fe) (11). A multistep reaction involving dipolar intermediates is suggested for the degenerate valence isomerisation of 3 and 5. 11, which formally contains a ketocarbene ligand, has been identified by a crystal structure analysis (C. K.).
    Notes: Die lichtinduzierte Reaktion von Pentacarbonyleisen mit Benzoloxid/Oxepin (1/2) liefert außer Benzol und Phenol ca. 3% kristallines Tricarbonyl(oxepin)eisen (3). Anhand dynamischer 1H-NMR-Spektren wurde eine rasche entartete Valenztautomerie von 3 nachgewiesen. 2,7-Dimethyloxepin gibt bei Umsetzung mit Pentacarbonylesien, neben o-Xylol und 2,6-Dimethylphenol, 5% gelbes Tricarbonyl(2,7-dimethyloxepin)eisen (5) und ca. 1% rotes Hexacarbonyl[2-4-n:5-6n-(7-oxo-3,5-octadien-2,2-diyl)]dieisen(Fe - Fe) (11). Für die entartete Valenztautomerie von 3 bzw. 5 wird ein mehrstufiger Reaktionsverlauf über dipolare Zwischenstufen diskutiert. 11 wurde anhand einer Kristallstrukturanalyse (C. K.) identifiziert; es enthält formal einen Ketocarben-Liganden.
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  • 9
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies on the Reactivity of Metal π-Complexes, XXII. Sandwich-like Dinuclear (Pd-Pd)-Complexes with Bridging Cyclopentadienyl and Allyl LigandsThe reaction of C5H5Pd(2-RC3H4) (2-RC3H4 = 2-R-allyl) with tertiary phosphines or phosphites in the molar ratio of 1:1 produces in practically quantitative yields the dinuclear complexes (C5H5)(2-RC3H4)Pd2L2 (4-20) in which palladium has the oxidation state +1. The crystal structure analysis of 5 (R = CH3, L = P(C6H5)3) and 12 (R = CH3, L = P(OC6H4-o-CH3)3) shows that the cyclopentadienyl as well as the allyl ligand is bonded in a sandwich manner to the Pd-Pd unit. The Pd-Pd distance of 267.9 (in 5) or 268.9 pm (in 12) is suggestive of a metal-metal bond. It is not possible to determine whether the cyclopentadienyl ring in 4-20 exists as a pentahapto- or trihapto-bonded ligand on the basis of the 1H- and 13C n. m. r. data. The reactivity of the dinuclear complexes is in agreement with square planar coordination of the metal atoms.
    Notes: Bei den Reaktionen von C5H5Pd(2-RC3H4) (2-RC3H4 = 2-R-Allyl) mit tertiären Phosphinen oder Phosphiten im Molverhältnis 1:1 entstehen in praktisch quantitativer Ausbeute die Zweikernkomplexe (C5H5)(2-RC3H4)Pd2L2 (4-20), in denen Palladium in der Oxidationszahl +1 vorliegt. Wie die Kristallstrukturanalysen von 5 (R = CH3, L = P(C6H5)3) und 12 (R = CH3, L = P(OC6H4-o-CH3)3) zeigen, sind sowohl der Cyclopentadienyl- als auch der Allyl-Ligand sandwichartig an die Pd2-Einheit gebunden. Der Pd-Pd-Abstand von 267.9 (in 5) bzw. 268.9 pm (in 12) weist auf das Vorliegen einer Metall-Metall-Bindung hin. Aufgrund der 1H- und 13C-NMR-Daten ist nicht zu entscheiden, ob in 4-20 der Cyclopentadienylring als pentahapto-oder trihapto-gebundener Ligand vorliegt. Die Reaktivität der Zweikernkomplexe steht mit einer quadratisch-planaren Koordination der Metallatome in Einklang.
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  • 10
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Double Ylides, II. Synthesis, Properties, and a Crystal Structure Analysis of Some [Methanidobis(dimethylphosphonium methylide)] Complexes of Main Group and Transition Metals (Al, Ga, Ni, Pd, Pt, Au, Zn, Cd)The cyclic dimethylaluminium complex 1 with the novel methanidobis(dimethylphosphonium methylide) ligand is easily accessible from Li[Al(CH3)4] and (CH3)3PCHP(CH3)3F in good yields. The analogous gallium compound 2 is obtained from (CH3)3Ga etherate and (CH3)3-P=C=P(CH3)3. The X-ray structure analysis of 2 has shown that this compound forms six-membered rings with a quasi-tetrahedral configuration of substituents at the Ga and P atoms, which are bridged by two CH2 and one planar CH bridge (PCHP). (CH3)3PCP(CH3)3 undergoes a transylidation reaction with nickel, palladium, and platinum dichloride to yield novel chelate complexes, in which each methanidobis(dimethylphosphonium methylide) ligand is attached to the central atom through two metal-carbon σ-bonds. For these complexes a centrosymmetrical square-planar structure is proposed. Accordingly, with (CH3)3AuCl a dimethylgold chelate complex 4 is obtained.  -  From zinc and cadmium alkyls, upon reaction with 1 the ylide complexes 5a, b with tetrahedral configuration are formed with evolution of alkane.
    Notes: Der cyclische Dimethylaluminium-Komplex 1 mit dem neuartigen Methanidobis(dimethylphosphonium-methylid)-Liganden ist aus Li[Al(CH3)4] und (CH3)3PCHP(CH3)3F gut zugänglich. Die analoge Galliumverbindung 2 kann aus (CH3)3Ga-Etherat und (CH3)3P=C=P(CH3)3 erhalten werden. Die Röntgenstrukturanalyse von 2 ergab, daß diese Verbindung Sechsringmoleküle mit quasi-tetraedrisch konfigurierten Ga- und P-Atomen enthält, die über zwei CH2-und eine planare CH-Brücke (PCHP) verknüpft sind. (CH3)3PCP(CH3)3 reagiert mit Nickel-, Palladium- und Platindichlorid unter Umylidierung zu Chelatkomplexen (3a-c), in denen der Methanidobis(dimethylphosphonium-methylid)-Ligand über je zwei echte Metall-Kohlenstoff-σ-Bindungen an das Zentralatom fixiert ist. Für diese Komplexe wird eine centrosymmetrische quadratisch-planare Struktur vorgeschlagen.  -  Mit (CH3)2AuCl wird entsprechend ein Dimethylgold-Chelatkomplex 4 erhalten.  -  Aus Zink- und Cadmiumalkylen entstehen unter Alkanentwicklung die vermutlich tetraedrisch konfigurierten Ylidkomplexe 5a, b.
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