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Ministerio de Ciencia e Innovación (Espanya)
Generalitat de Catalunya. Agència de Gestió d’Ajuts Universitaris i de Recerca |
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Prat Casellas, Irene
Font Gimbernat, David Company Casadevall, Anna Junge, Kathrin Ribas Salamaña, Xavi Beller, Matthias Costas Salgueiro, Miquel |
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A family of iron complexes with general formula [Fe(II)( R,Y,XPyTACN)(CF3SO3)2], where R,Y,XPyTACN=1-[2′-(4-Y-6-X-pyridyl)methyl]-4,7-dialkyl-1,4, 7-triazacyclononane, X and Y refer to the groups at positions 4 and 6 of the pyridine, respectively, and R refers to the alkyl substitution at N-4 and N-7 of the triazacyclononane ring, are shown to be catalysts for efficient and selective alkene oxidation (epoxidation and cis-dihydroxylation) employing hydrogen peroxide as oxidant. Complex [Fe(II)(Me,Me,HPyTACN)(CF 3SO3)2] (7), was identified as the most efficient and selective cis-dihydroxylation catalyst among the family. The high activity of 7 allows the oxidation of alkenes to proceed rapidly (30 min) at room temperature and under conditions where the olefin is not used in large amounts but instead is the limiting reagent. In the presence of 3 mol% of 7, 2 equiv. of H2O2 as oxidant and 15 equiv. of water, in acetonitrile solution, alkenes are cis-dihydroxylated reaching yields that might be interesting for synthetic purposes. Competition experiments show that 7 exhibits preferential selectivity towards the oxidation of cis olefins over the trans analogues, and also affords better yields and high [syn-diol]/[epoxide] ratios when cis olefins are oxidized. For aliphatic substrates, reaction yields attained with the present system compare favourably with state of the art Fe-catalyzed cis-dihydroxylation systems, and it can be regarded as an attractive complement to the iron and manganese systems described recently and which show optimum activity against electron-deficient and aromatic olefins Financial support by ERC-29910, MCYT of Spain through project CTQ2009-08464/BQU to MC. IP, and MC thank MICINN and Generalitat de Catalunya, respectively for PhD grants. MC and XR thank Generalitat de Catalunya for 2009SGR637 and ICREA Acad mia Awards. XR is grateful for finanical support from INNPLANTA project IPN-2011-0059-PCT-42000-ACT1 |
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http://hdl.handle.net/2072/297583 | |
eng | |
Wiley-VCH Verlag | |
Tots els drets reservats | |
Alquens
Alkenes Catà lisi homogènia Homogeneous catalysis Ferro Iron Aigua oxigenada Hydrogen peroxide |
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Fe(PyTACN)-catalyzed cis-dihydroxylation of olefins with hydrogen peroxide | |
info:eu-repo/semantics/article | |
Recercat |