Search results for "element"

Polycondensed nitrogen heterocycles. X. 5,6,7,8-Tetrahydropyrrolo[1,2-e][1,5]benzodiazocin-7-ones. A new ring system

1981

The synthesis of a new heterocyclic ring system is described. Condensation of 1,4-diketones 1a,b with β-alanine gave the substituted propionic acids 2a,b which upon reduction with palladium on charcoal afforded compounds 3a,b. Title compounds 4a,b were obtained by refluxing 3a,b in toluene with p-toluenesulphonic acid as catalyst.

A new method for the regioselective synthesis of β-enamino acid derivatives

1993

Abstract A mild, simple and efficient route to β-enamino imidazole carbonilic derivatives 3 by reaction of ketimines with N,N′ -carbonyl diimidazole in the presence of boron triflouride as catalyst has been developed. The conversion of 3 to esters has also been explored.

Coordinative Stabilization ofCyclo-Tetratellurium as[Te4{Cr(CO)5}4]: The First Organometallic Derivative of a Tellurium Allotrope

1997

Long-term Effects of Bioaccumulation in Ecosystems

2005

Extensive damage to organisms and declines in wildlife populations have been observed together with long-term bioaccumulation and biomagnification of persistent xenobiotic chemicals. Heavy metals, especially organic or biomethylated mercury, lead, cadmium and organic tin compounds have caused environmental damage through bioaccumulation on a local scale. Effects on wildife caused by bioaccumulation of persistent organochlorine compounds are more widespread. However, the causal relationship between a biomagnified compound and the long-term effects have been established in only a few cases. Metabolic transformations, and occurrence of several toxic contaminants together in many cases, complic…

ChemInform Abstract: Boron Functionalization of BODIPY by Various Alcohols and Phenols

2014

The synthesis of new B–O BODIPY derivatives functionalized with different alkoxy or diarylalkoxy derivatives is described. These compounds were synthesized from the reaction of different B–F BODIPY precursors with various alcohols and phenols, in the presence of AlCl3. Water-soluble dyes could be synthesized as well with this method, specifically by the introduction of polyethyleneglycol (PEG) groups. A photophysical study of the different compounds was performed, and showed that the B–O BODIPY derivatives exhibit rich fluorescence properties. Finally, the conjugation of the BODIPY core has been extended using two distyryl groups, hence providing NIR emitting BODIPY derivatives, in which on…

The reaction of enones with electrophiles

2010

Über die authoxydation ungesättigter verbindungen. VI. Mitt. Die autoxydation des 9,11-octadecadiensäuremethylesters

1956

9,11-Octadecadiensauremethylester reagiert mit molekularem Sauerstoff in 1,2- und 1,4-Stellung unter Bildung von relative niedermolekularen Sauerstoff-Copolymerisation. Diese polymeren Peroxyde sind bei der Authoxydation autokatalytisch wirksam. Sie sind recht bestandig; die buldung von Aldehyden wurde dei der Aufbewahrung nicht beobachtet. Die Reaktion von end- und von kettenstandigen Doppelbindungen, die in Nachbarschaft zu Peroxygruppen stechen, mit Perbenzoesaure wird am Beispiel des Allyl-tert.-Butyl- und des Cyclohexenylmethylperoxyds untersucht. The Me-ester of 9,11-octadecadienoic acid reacts in 1.2 and 1.4-position with moleculare oxygen to give relatively low molecular oxygen-copo…

ChemInform Abstract: Donor-Stabilized Phosphenium Adducts as New Efficient and Immobilizing Ligands in Palladium-Catalyzed Alkynylation and Platinum-…

2009

The straightforward synthesis of a new donor-stabilized phosphenium ligand 3d by addition of bromodifurylphosphine to 1,3-dimethylimidazolium-2-carboxylate 1 is described. The obtained ligand exhibits a very strong π-acceptor character, comparable to that of triphenyl phosphite [P(OPh) 3 ] or of tris-halogenophosphines, with a v CO (A 1 ) at 2087 cm ―1 for its nickel tricarbonyl complex. This ligand, as well as the related 3a which was obtained from chlorodiphenylphosphine, were tested in palladium-catalyzed aryl alkynylation and in the platinum-catalyzed selective hydrogenation of chloronitrobenzenes, both in an ionic liquid phase. In C―C bond cross-coupling we observed that the increase o…

Die Reaktion von 1,4-Bis(1-phenylvinyl)benzol mit Lithium

1975

Die Reaktion von 1,4-Bis(1-phenylvinyl)benzol (1) mit Lithium in THF, die vorwiegend zu einem dimeren α,ω-Dien-dianion 3 fuhrt, wird diskutiert. Die durch Umsetzung des Dianions 3 mit Methanol, Kohlendioxid und Methyljodid erhaltenen Reaktionsprodukte 4, 6 und 7 werden durch ihre IR-, NMR- und Massenspektren charakterisiert. The reaction of 1,4-bis(1-phenylvinyl)benzene (1) with lithium in THF yielding predomaintly the dimeric α,ω-diene dianion 3 is discussed. The products 4, 6, and 7 resulting from the reaction of the dianion 3 with methanol, carbon dioxide and methyl iodide are characterized by IR, NMR and mass spectra.

Über die anionische polymerisation von acrolein. Polymere acroleine. 34. Mitt.1

1967

Acrolein wurde mit Lithium-, Natrium- oder Kaliumcyanid in Tetrahydrofuran bzw.in Toluol polymerisiert. Die Abhangigkeit der Polymerisationsgeschwindigkeit und der Struktur der Polymeren von Reaktionsmedium, Temperatur und Gegenion wurde untersucht. Unterhalb -10°C polymerisiert Acrolein mit Natriumcyanid nur uber die CO. Doppelbindung. Es entstehen hochmolekulare, losliche Poly-3,4-acroleine. Oberhalb -10°C wird dagegen auch Polymerisation uber die Vinylgruppe beobachtet. Die Kurve fur die Abhangigkeit der Polymerisationsgeschwindigkeit von der Reaktionstemperatur durchlauft Extremwerte. Es wird ein Mechanismus aufgestellt, der die jeweilige Struktur des Polymeren als Ergebnis von Gleichge…