A lanthanum picrate complex of a 1,2-bisamide substituted calix[4]arene

The synthesis and structural characterization of a lanthanum picrate complex of the proximally-substituted calix[4]arene bisamide, 5,11,17,23-tetra-tert-butyl-25,26- bis(diethylcarbamoylmethoxy)-27,28-dihydroxycalix[4] arene (L), is reported. The complex is formulated as [La(L-H)(picrate)2]2.75CH2Cl2 and crystallises with two inequivalent metal complexes in the unit cell. The differing dispositions of the picrate anions in the two complexes suggest that intramolecular interactions between the aromatic rings of the picrate and calixarene are less significant than the forces involved in the crystal packing of the complexes

eta(6)-mesityl,eta(1)-imidazolinylidene-carbene-ruthenium(II) complexes: Catalytic activity of their allenylidene derivatives in alkene metathesis and cycloisomerisation reactions

WOS: 000183225200020PubMed ID: 12772307The reaction of electron-rich carbene-precursor olefins containing two imidazolinylidene moieties [(2,4,6-Me3C6H2CH2)NCH2CH2N(R)C=](2) (2a: R = CH2CH2OMe, 2b R = CH(2)Mes), bearing at least one 2,4,6-trimethylbenzyl (R = CH(2)Mes) group on the nitrogen atom, with [RuCl2(arene)](2) (arene = p-cymene, hexamethylbenzene) selectively leads to two types of complexes. The cleavage of the chloride bridges occurs first to yield the expected (carbene) (arene)ruthenium(H) complex 3. Then a further arene displacement reaction takes place to give the chelated eta(6)-mesityl,eta'-carbene-ruthenium complexes 4 and 5. An analogous eta(6)-arene-eta(1)-carbene complex with a benzimidazole frame 6 was isolated from an in situ reaction between [RuCl2(p-cymene)](2), the corresponding benzimidazolium salt and cesium carbonate. On heating, the RuCl2(imidazolinylidene) (p-cymene) complex 8, with p-methoxybenzyl pendent groups attached to the N atoms, leads to intramolecular p-cymene displacement and to the chelated eta(6)-arene,eta(1)-carbene complex 9. On reaction with AgOTf and the propargylic alcohol HC=CCPh20H, compounds 4-6 were transformed into the corresponding ruthenium allenylidene intermediates (4-->10, 5-->11, 6-->12). The in situ generated intermediates 10-12 were found to be active and selective catalysts for ring-closing metathesis (RCM) or cycloisomerisation reactions depending on the nature of the 1,6-dienes. Two complexes [RuCl2-{eta(1)-CN(CH2C6H2Me3-2,4,6)CH2CH2N- (CH2CH2OMe)}(C6Me6)] 3 with a monodentate carbene ligand and [RuCl2-{eta(1)-CN[CH2(eta(6)-C6H2Me3-2,4,6)]CH2CH2N-(CH2C6H2Me3-2,4,6)}] 5 with a chelating carbene-arene ligand were characterised by X-ray crystallography

Access to 3-methyl-4-methylene-N-tosylpyrrolidine and 3,4-dimethyl-N-tosylpyrroline by ruthenium-catalyzed cascade cycloisomerization/isomerization reactions

WOS: 000188711900028New RuCl2(benzimidazole)(arene) complexes have been prepared. Upon reaction with 1,1-diphenylprop-2-ynol they generate catalyst precursors which perform the cycloisomerization of diallyltosylamide into 3-methyl-4-methylene-N-tosylpyrrolidine. The presence of N-(2,4,6-trimethyl-benzyl)benzimidazole as ligand leads to a subsequent isomerization and gives the 3,4-dimethyl-N-tosylpyrroline. (C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004