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Membered Macrocycles (membered + macrocycle)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

ChemInform Abstract: Crown Ethers with Azo or Azoxy Unit and Sulfur Atom(s) in 16-Membered Macrocycle.

CHEMINFORM, Issue 44 2001
J. Szczygelska-Tao
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

Bis(,4 -butane-1,4-dithiolato)bis[hexacarbonyldiiron(II)(Fe,Fe)]

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 11 2007
Yue Zhang
The novel title double-butterfly Fe/S cluster complex, [Fe4(C4H8S2)2(CO)12], which is structurally similar to the active site of the Fe-only hydrogenases, contains two inversion-related Fe2S2(CO)6 subcluster cores connected by two equivalent butyl chains to afford a 16-membered macrocycle. The formation of the 16-membered macrocycle has an influence on the C,S,Fe angles, while the Fe,Fe and Fe,S bond lengths remain similar to those in related complexes. [source]

Rhodium(I)-Catalysed Intramolecular [2+2+2] Cyclotrimerisations of 15-, 20- and 25-Membered Azamacrocycles: Experimental and Theoretical Mechanistic Studies

CHEMISTRY - A EUROPEAN JOURNAL, Issue 21 2009
Anna Dachs
Abstract Number of members makes a difference: The [2+2+2] intramolecular cyclotrimerisation of a new series of 20- and 25-membered azamacrocycles catalysed by the Wilkinson's catalyst are reported (see scheme). The 20- and 25-membered azamacrocycles show different reactivity. Why? Theoretical calculations give insight into the reactivity differences observed for the 20- and 25-membered macrocycles. A new series of 20- and 25-membered polyacetylenic azamacrocycles have been satisfactorily prepared and completely characterised by spectroscopic methods. Various [2+2+2] cyclotrimerisation processes catalysed by the Wilkinson's catalyst, [RhCl(PPh3)3], were tested in the above-mentioned macrocycles. The 25-membered azamacrocycle (like the previously synthesised 15-membered azamacrocyle) led to the expected cyclotrimerised compound in contrast to the 20-membered macrocycle, which is characterised by its lack of reactivity. The difference in reactivity of the 15-, 20- and 25-membered macrocycles has been rationalised through density functional theory calculations. S,ha sintetitzat i caracteritzat espectroscòpicament una nova sèrie de macrocicles nitrogenats poliacetilènics de 20- i 25-membres. Amb aquests macrocicles s'han dut a terme les reaccions de ciclotrimerització [2+2+2] catalitzades pel catalitzador de Wilkinson, [RhCl(PPh3)3]. El macrocicle nitrogenat de 25-membres (de la mateixa manera que el macrocicle nitrogenat de 15-membres) permet l,obtenció del compost ciclotrimeritzat. Per contra, el macrocicle de 20-membres es caracteritza per la seva falta de reactivitat. El diferent comportament de reactivitat dels macrocicles de 15-, 20-, i 25-membres ha estat estudiat mitjançant càlculs teòrics basats en la teoria del funcional de la densitat. [source]

Studies of Pyridinyl-Containing 14-Membered Macrocyclic Copper(II) Complexes

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 7 2003
Sabrina Autzen
Abstract Six copper(II) complexes of tetracoordinating, pyridinyl-containing 14-membered macrocycles with varying ratios of nitrogen and oxygen donor atoms were prepared and characterized by IR, UV/Vis, and EPR spectroscopy and cyclic voltammetry. A distorted tetragonal coordination of the copper center in the solid-state was established by X-ray crystallography for the tetraazamacrocyclic complex Cu-3 carrying a methoxybenzyl pendent arm and the trioxaaza complex Cu-6. The superoxide dismutase-like activity of the CuII complexes was investigated by inhibition of NADH oxidation. Although the UV/Vis and EPR spectra of the complexes were strongly affected when the coordinating nitrogen atoms were successively replaced by oxygen atoms, no significant change in their reactivity towards superoxide was observed. In all cases a 1:1 or 1:2 stoichiometry for the reaction with superoxide was found, with the exception of the methoxybenzyl-substituted tetraaza complex, which showed a low catalytic activity with a turnover number of about 10. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

Synthesis of 2,4-Furanophanes by Palladium-Catalyzed Macrocyclization Reactions of 1,n -Diallenyl Diketones

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 9 2004
A. Stephen K. Hashmi
Abstract The 1,n -diallenyl diketones 8a,j were prepared and subjected to reactions with the [PdCl2(MeCN)2] catalyst. Upon decreasing the length of the bridge between the allenyl ketone units, first we obtained the (E) isomer 10 as the macrocyclic product and then the (Z) isomer 11 accompanied by the exocyclic double bond isomer 12. In all cases, the open-chained 1,n -difuryl alkanes were isolated as side-products. The analogous preparation and conversion of the diallenyl diketones 19 and 24, which have even longer bridges and ether-functionalities, delivered the 20- to 52-membered macrocycles 21a, 21b, 26a, and 26b with only the expected (E) configuration of the double bond. The ring closure of a furan derivative, having vinyl groups in its substituents at the 2- and 4-positions, to a related product by Ru-catalyzed olefin metathesis delivered yields similar to the Pd-catalyzed macrocyclization, but provided a mixture of both double bond isomers. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

Rhodium(I)-Catalysed Intramolecular [2+2+2] Cyclotrimerisations of 15-, 20- and 25-Membered Azamacrocycles: Experimental and Theoretical Mechanistic Studies

CHEMISTRY - A EUROPEAN JOURNAL, Issue 21 2009
Anna Dachs
Abstract Number of members makes a difference: The [2+2+2] intramolecular cyclotrimerisation of a new series of 20- and 25-membered azamacrocycles catalysed by the Wilkinson's catalyst are reported (see scheme). The 20- and 25-membered azamacrocycles show different reactivity. Why? Theoretical calculations give insight into the reactivity differences observed for the 20- and 25-membered macrocycles. A new series of 20- and 25-membered polyacetylenic azamacrocycles have been satisfactorily prepared and completely characterised by spectroscopic methods. Various [2+2+2] cyclotrimerisation processes catalysed by the Wilkinson's catalyst, [RhCl(PPh3)3], were tested in the above-mentioned macrocycles. The 25-membered azamacrocycle (like the previously synthesised 15-membered azamacrocyle) led to the expected cyclotrimerised compound in contrast to the 20-membered macrocycle, which is characterised by its lack of reactivity. The difference in reactivity of the 15-, 20- and 25-membered macrocycles has been rationalised through density functional theory calculations. S,ha sintetitzat i caracteritzat espectroscòpicament una nova sèrie de macrocicles nitrogenats poliacetilènics de 20- i 25-membres. Amb aquests macrocicles s'han dut a terme les reaccions de ciclotrimerització [2+2+2] catalitzades pel catalitzador de Wilkinson, [RhCl(PPh3)3]. El macrocicle nitrogenat de 25-membres (de la mateixa manera que el macrocicle nitrogenat de 15-membres) permet l,obtenció del compost ciclotrimeritzat. Per contra, el macrocicle de 20-membres es caracteritza per la seva falta de reactivitat. El diferent comportament de reactivitat dels macrocicles de 15-, 20-, i 25-membres ha estat estudiat mitjançant càlculs teòrics basats en la teoria del funcional de la densitat. [source]