An efficient synthesis of chromenylphenylpropanone derivatives as warfarine-like analogues was developed by the Michael addition of 4-hydroxycoumarin to α,β-unsaturated compounds in the presence of polyvinylpolypyrrolidone supported antimony(III) chloride (PVPP-SbCl3) as a new polymeric Lewis acid catalyst in chloroform at reflux conditions without formation of 2,4-...

The RNA world hypothesis holds that in the evolutionary events that led to the emergence of life RNA preceded proteins and DNA and is supported by the ability of RNA to act as both a genetic polymer and a catalyst. On the other hand, biosynthesis of nucleic acids requires a large number of enzymes and chemical synthesis of RNA under presumed prebiotic conditions is complicated and requires many...

Short Abstract 3-Formylsalicylic acid (Hfsal) covalently bound to chloromethylated polystyrene (PS) cross-linked with 5% divinylbenzene reacts with DL-alanine and L-isoleucine to give the Schiff-base tridentate ligands PS-H2fsal-DL-Ala and PS-H2fsal-L-isoleu, respectively. These anchored ligands on reaction with VOSO4 and Cu(CH3COO)2.H2O form complexes PS-[VO(fsal-DL-Ala)(H2O)], PS-[Cu(fsal-DLA...

The asymmetric transfer hydrogenation of imines was performed with the use of a polymer-immobilized chiral catalyst. The chiral catalyst, prepared from crosslinked polystyrene-immobilized chiral 1,2-diamine monosulfonamide, was effective in the asymmetric transfer hydrogenation of N-benzyl imines in CH(2)Cl(2) to give a chiral amine in high yield and good enantioselectivity. Furthermore, an amp...

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The heterogenization of homogeneous catalysts onto a solid support is step towards more sustainable chemistry. recovery and reuse extremely important from practical, economic environmental point view. In this regards, we report series polymer-supported tetrahydropyran-based hybrid dipeptides that serve as active for the enantioselective Michael addition aldehydes to β-nitrostyrenes. These suppo...

a novel rice-husk-silica supported n-propyl bipyridinium chloride (rhprbpcl) has been prepared. due to the basicity of rhprbpcl, it was decided to evaluate its catalytic activity in the one-pot preparation of tetrahydrobenzo[b]pyran, dihydropyrano[3,2-c]chromene and dihydropyrano[4,3-b]pyran derivatives. the catalyst was characterized by ft-ir, sem and tga analyses. this methodology offers seve...

A novel heterogeneous Pd/polymer catalyst containing co-catalytic functional groups catalyses the direct alkenylation of anisole with ethyl trans-cinnamate under oxygen. The properties of the polymeric catalyst were compared to other immobilised catalysts. The activity of the polymeric catalyst typically increased with temperature and oxygen pressure exhibiting the optimal activity up to 100 TO...

Accurate active-site counts are necessary for the establishment of olefin polymerization kinetics, yet current techniques are often tedious and limited in sensitivity. Herein, we describe the development of a novel method for determining the fraction of initiated catalyst using standard gel-permeation chromatography (GPC). The first insertion of monomer into the chromophore-bearing zirconocene ...