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Fe(PyTACN)-catalyzed cis-dihydroxylation of olefins with hydrogen peroxide

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

Wiley-VCH Verlag

Manager: Ministerio de Ciencia e Innovación (Espanya)
Generalitat de Catalunya. Agència de Gestió d’Ajuts Universitaris i de Recerca
Author: Prat Casellas, Irene
Font Gimbernat, David
Company Casadevall, Anna
Junge, Kathrin
Ribas Salamaña, Xavi
Beller, Matthias
Costas Salgueiro, Miquel
Abstract: 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
Document access: http://hdl.handle.net/2072/297583
Language: eng
Publisher: Wiley-VCH Verlag
Rights: Tots els drets reservats
Subject: Alquens
Alkenes
Catàlisi homogènia
Homogeneous catalysis
Ferro
Iron
Aigua oxigenada
Hydrogen peroxide
Title: Fe(PyTACN)-catalyzed cis-dihydroxylation of olefins with hydrogen peroxide
Type: info:eu-repo/semantics/article
Repository: Recercat

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