Results 211 to 220 of about 210,013 (270)
, 2014 : A benign and efficient synthesis of chiral macrocyclic ‘aza-crown ’ ethers of varying ring size is reported. The synthesis involves a Schiff base condensation of ether linked dialdehydes of varying chain length and (1R,2R)-(–)-1,2-diaminocyclohexane ...
Characterisation Macrocyclic +3 more
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Journal of Inclusion Phenomena and Molecular Recognition in Chemistry, 1988
The discovery of the crown ethers stemmed from efforts to control the catalytic activity of vanadium and copper by complexation with multidentate ligands. The first crown ether, 2,3,11,12-dibenzo-1,4,7,10,13,16-hexaoxacyclo-octadeca-2,11-diene, was obtained in 0.4% yield during an attempt to prepare a phenolic ligand from catechol and bis(2-chloroethyl)
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The discovery of the crown ethers stemmed from efforts to control the catalytic activity of vanadium and copper by complexation with multidentate ligands. The first crown ether, 2,3,11,12-dibenzo-1,4,7,10,13,16-hexaoxacyclo-octadeca-2,11-diene, was obtained in 0.4% yield during an attempt to prepare a phenolic ligand from catechol and bis(2-chloroethyl)
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Antifungal Activity of Crown Ethers
Journal of Inclusion Phenomena, 1984Some crown ethers were found to show significant antifungal activity against some wood-decay fungi, phytopathogenic fungi and eumycetes,Trichophytons for dermatomycosis. Their toxicity was evaluated by the paper disc method as well as by determining the values of ED50, i.e., the concentration which inhibits the mycelium growth by 50%.
Koji Yagi +5 more
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Novel crown ethers by oxidative cycloaddition of thiopheno crown ethers
Journal of the Chemical Society, Perkin Transactions 1, 1994The synthesis of the thiopheno crown ethers 4 is described. The oxidative cycloaddition of these and the known thiopheno crown ethers 2 with N-phenylmaleimide is reported. The resulting sulfoxy-bridged cycloadducts 15 and 16 are transformed oxidatively into the phthalimido crown ethers 14 and 17.
YuanQiang Li +3 more
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1996
Abstract Crown ethers are perhaps the most widely used family of host compounds in supramolecular chemistry-the chemistry of the non-covalent bond. The fortuitous discovery of the macrocyclic polyethers by Pedersen in 1967 laid the foundation for an exhaustive study of their preparation and complexing abilities, primarily with metal ...
David B Amabilino +2 more
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Abstract Crown ethers are perhaps the most widely used family of host compounds in supramolecular chemistry-the chemistry of the non-covalent bond. The fortuitous discovery of the macrocyclic polyethers by Pedersen in 1967 laid the foundation for an exhaustive study of their preparation and complexing abilities, primarily with metal ...
David B Amabilino +2 more
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Crown ethers of low symmetry. Spiro crown ethers and 16-crown-5 derivatives
The Journal of Organic Chemistry, 1983Synthese des spirocrowns; evaluation de leur aptitude a la coordination pour l'etude de l'extraction des picrates alcalins. Equilibres d'extraction.
Mikio Ouchi +5 more
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AIP Conference Proceedings, 2012
We use the combined conformational and vibrational analysis methodology to predict in what conformation different crown ethers and some of their complexes exist. Comparison between the structure of some of the low and high energy conformations allows the prediction of the factors that affects the conformational stability of the studied crown ether ...
A. A. El-Azhary +5 more
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We use the combined conformational and vibrational analysis methodology to predict in what conformation different crown ethers and some of their complexes exist. Comparison between the structure of some of the low and high energy conformations allows the prediction of the factors that affects the conformational stability of the studied crown ether ...
A. A. El-Azhary +5 more
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Liquid Crystalline Crown Ethers
2011In this chapter, a comprehensive review over the entire reserarch on liquid crystalline crown ethers since their discovery will be given. Monomeric and polymeric molecules containing crown ethers as well as aza crown ethers, thia crown ethers and crown ethers with several different heteroatoms will be presented.
Martin, Kaller, Sabine, Laschat
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The synthesis of anthracene crown ethers derived from benzo-crown ethers
Tetrahedron, 1998Abstract The sulfuric acid-promoted reaction of benzo-15-crown-5 (3) and benzo-18-crown-6 (6) with aliphatic aldehydes, leading to the formation of anthracene crown ethers, was studied. A substantial substituent effect on the reaction course was found.
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The synthesis of novel crown ethers, part ix, 3‐phenyl chromenone‐crown ethers
Journal of Heterocyclic Chemistry, 2001Abstract3‐Phenyl‐ and 3‐(p‐methoxyphenyl)‐7,8‐dihydroxy and ‐6,7‐dihydroxychromenones were prepared from ethyl 3‐oxo‐2‐phenylpropanoate, ethyl 3‐oxo‐2‐(4‐methoxyphenyl)‐propanoate and the trihydroxy benzenes in H2SO4. 3‐Aryl‐7,8‐ and 3‐aryl‐6,7‐dihydroxy‐2H‐chromenones reacted with the bis‐dihalides of poly‐glycols in DMF/MeCO3 to afford 12‐Crown‐4, 15‐
M. Bulut, Ç L. Erk
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