Eine formal nucleophile Substitution an Bilatrienen-abc

Reaction of Aetiobiliverdine-IV- with cyanide ion in dimethylsulfoxide yieldsvia nucleophilic addition and oxidation the 10-cyano derivative exclusively. Its structure was established from its spectroscopic properties.     

Elektrophile Substitution und nucleophile Addition an 3,4-Dihydro-5(1H)-pyrromethenonen

3,4-Dihydro-5(1H)-pyrromethenones are easier attacked at themeso-position by electrophiles than 5(1H)-pyrromethenones. This is demonstrated both by aMannich-type-substitution or deuterium-exchange-experiments and by the addition of O-, S-, and N-Nucleophiles to the exocyclic double bond of the model-dihydropyrromethenone (Z)-1 under very mild reaction conditions. Applying these results to the chemistry of 2,3-dihydro-bilatrienes-abc, their chemical characteristics—especially their tautomeric behavior and their dominant C-5-selectivity towards electrophiles—become better understandable.

     

Triacetoxysilan und Tris(trifluoracetoxy)silan

Zusammenfassung Die Darstellung der bisher unbekannten Verbindungen (CH₃COO)₃SiH und (CF₃COO)₃SiH wird beschrieben, ihre Schwingungs- und Kernresonanzspektren werden mitgeteilt. Die extrem liegenden Werte der Fluorverbindung werden im Zusammenhang mit den bisher bekannten Werten diskutiert.

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Triacetoxy silane and tris(trifluoroacetoxy) silane

The preparation of the formerly unknown compounds (CH₃COO)₃SiH and (CF₃COO)₃SiH is described, their vibrational and NMR-spectra are reported. Some extreme values of the latter compound are discussed.

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Mit 1 Abbildung

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Herrn Prof. Dr.A. Wacek zum 75. Geburtstag gewidmet.     

Photoinduzierte nucleophile Substitution von 3-substituierten 2,1-Benzisoxazolen (unter Ringöffnung)

On UV.-irradiation in strongly acidic solution 3-alkyl- and 3-aryl-2,1 benzisoxazoles, respectively, yield 5-substituted 2-aminophenylketons.     

Darstellung und Kristallstruktur von Tetrakis(pentafluorphenylamino)silan

Synthesis and Crystal Structure of Tetrakis(pentafluorophenylamino)silane Colourless single-crystals of Tetrakis(pentafluorophenylamino) silane were obtained from the reaction of SiCl₄ with monolithiated pentafluoroaniline at low temperatures. The aminosilane has been characterized by various spectroscopic methods and its crystal structure has been determined by x-ray diffraction (for details see “Inhaltsübersicht”). Thermal condensation has not been achieved. However, reaction of silicon(IV)-chloride with pentafluoroaniline in the presence of triethylamine yielded the respective tricyclosilazane.     

Heteroatomfunktionalisierte Methylgold-Komplexe: Synthese und Struktur von Chlormethyl(triphenylphosphin)- und Phenylthiomethyl(trimethylphosphin)gold

Heteroatom-functionalized Methylgold Complexes: Synthesis and Structure of Chloromethyl(triphenylphosphine)- and Phenylthiomethyl(trimethylphosphine)gold [AuCl(PPh₃)] reacts with Mg(CH₂Cl)Cl, prepared in situ from CH₂ClI and iPrMgCl, in ether at –65 °C to give [Au(CH₂Cl)(PPh₃)] ( 1 a ). 1 a reacts with LiI, NaOMe and PPh₃ to give [Au(CH₂I)(PPh₃)] ( 2 ), [Au(CH₂OMe)(PPh₃)] ( 3 ) and [Au(CH₂PPh₃)(PPh₃)]Cl ( 4 ), respectively. 2 decomposes rapidly at room temperature, yielding ethylene and [AuI(PPh₃)]. The reaction of [AuCl(PMe₃)] with LiCH₂SPh in THF affords [Au(CH₂SPh)(PMe₃)] ( 5 ). The chloromethyl and the phenylthiomethyl complex 1 a and 5 were isolated and characterized by NMR (¹H, ¹³C, ³¹P) spectroscopy as well as by single-crystal X-ray structure analysis. In the solid state discrete molecules of 1 a and 5 are found with linear C–Au–P units [C–Au–P 179,8(4)° ( 1 a ), 179,1(1)° ( 5 )]. The angle Au–C–Cl (115,4(6)°) in 1 a is slightly greater than the tetrahedral angle.     

Versuche zum Nachweis von Bis(Chlormethyl)ether (BCME) bei der Spanplattenherstellung

Summary A method has been developed for the determination of bis(chloromethyl)ether (BCME) in the atmosphere. It is based on preconcentration in a Porapak Q tube and subsequent gas-chromatographic determination with a halogen-specific detector. No BCME could be detected in the waste air of a press for the manufacture of chip boards using urea-formalin resin and ammonium chloride as catalyst. The limit of detection was 1 ppb (v/v) BCME.     

Substitution nucleophile radicalaire en chaîne (srn1): 12eme memoire1a (p)-nitrobenzyls disubstitues et fonctionnalises en α

Variously disubstituted and functionalized $\text{p}$-nitrobenzyl substrates 1 and 2 undergo S_RN1 reactions on treatment with a series of nucleophiles, showing the generality of the extension to functionalized substrates and nucleophiles.     

Bis(bis(trimethylsilyl)phosphino)silan [(Me3Si)2P]2SiH2 und 1,2-Bis(bis(trimethylsilyl)phosphino)disilan [(Me3Si)2PSiH2]2

The compounds H₂Si[P(SiMe₃)₂]₂ and [H₂SiP(SiMe₃)₂]₂ were prepared and characterized by ²⁹Si NMR, ³¹P NMR, IR and Raman spectroscopy. After thermolysis of these compounds no cyclic silylphosphanes could be detected in the reaction mixture,although this did contain P(SiMe₃)₃.