The first enantioselective organocatalytic hydride reduction has been accomplished. The use of iminium catalysis has provided a new organocatalytic strategy for the enantioselective reduction of beta,beta-substituted alpha,beta-unsaturated aldehydes to generate beta-stereogenic aldehydes. The use of imidazolidinone 2 as the asymmetric catalyst has been found to mediate the transfer of hydrogen ...

The cis-trans chloride isomerization of a ruthenium olefin metathesis catalyst is studied using quantum mechanics (B3LYP DFT), including the Poisson-Boltzmann (PBF) continuum approximation. The predicted geometries agree with experiment. The energies in methylene chloride, lead to DeltaG = -0.70 kcal/mol and a cis:trans ratio of 76:24, quite close to the experimental value of DeltaG = -0.78 kca...

Stereoselective synthesis of variably protected α- and β-l-Ara4N glycosyl H-phosphonates as key intermediates in the syntheses of β-l-Ara4N-modified LPS structures and α-l-Ara4N-containing biosynthetic precursors is reported. A facile one-pot approach toward β-l-Ara4N glycosyl H-phosphonates includes anomeric deallylation of protected 4-azido β-l-Ara4N via terminal olefin isomerization followed...

Mo and W MonoAryloxide-Pyrrolide (MAP) olefin metathesis catalysts can couple terminal olefins to give as high as >98% Z-products in moderate to high yields with as little as 0.2% catalyst. Results are reported for 1-hexene, 1-octene, allylbenzene, allyltrimethylsilane, methyl-10-undecenoate, methyl-9-decenoate, allylB(pinacolate), allylOBenzyl, allylNHTosyl, and allylNHPh. It is proposed that ...

The review presents synthetic approaches to modern rhenium-based catalysts. Creation of an active center is considered as a process of obtaining a nanoparticle or a molecule, immobilized within a matrix of the substrate. Selective chemical routes to preparation of particles of rhenium alloys, rhenium oxides and the molecules of alkyltrioxorhenium, and their insertion into porous structure of ze...

lanthanide(iii) chloro complexes of 4[n-(4’-hydroxy-3’-methoxybenzalidene) amino] antipyrine semicarbazone (hmbaaps) (i) and 4[n-(3’,4’,5’-trimethoxybenzalidene) amino] antipyrine semicarbazone (tmbaaps) (ii) with the general composition lncl3.2l (ln = la, pr, nd, sm, gd, tb, dy or ho; l = hmbaaps or tmbaaps) are reported. all the complexes were synthesized in ethanolic medium and refluxed the ...

To assess the antioxidant behavior of trans-1, we first synthesized trans-allyl ether 4 by opening an (S)-glycidol derivative with an (E)-alk-2-en-ol, and then produced the unnatural E-enol ether 1 by a stereoselective iridium(I)-catalyzed olefin isomerization. Natural cis-1 was preferentially degraded by HOCl and was more protective than trans-1 against lipid peroxidation induced by a free-rad...

A novel Pd/sulfoxide-catalyzed macrolactonization reaction of linear omega-alkenoic acids is reported that proceeds via serial ligand-catalyzed allylic C-H oxidation. The scope of this macrolactonization appears to be very broad. Aryl, alkyl, and (Z)-alpha,beta-unsaturated acids are all competent nucleophiles for this reaction, with the latter undergoing macrolactonization with no olefin isomer...

Traditional systems for olefin/paraffin separation, like low-temperature distillation, are expensive and very energy consuming, and therefore, alternative separation methods are desired. Facilitated transport membranes are new tools for this separation to be substituted in large scale separation of olefin-paraffin mixtures. To design a membrane process for olefin-paraffin separation, equilibriu...