Computational evaluation of the η6-arene during the ATH of imines on Noyori’s RuII catalyst
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POSTER PRESENTATION Open Access Computational evaluation of the h6-arene during the ATH of imines on Noyori’s RuII catalyst Petr Kacer * , Sot Petr, Jan Pechacek, Jakub Januscak, Marek Kuzma From 9th German Conference on Chemoinformatics Fulda, Germany. 10-12 November 2013 Asymmetric hydrogenation ranks to the most intensively researched way of preparation of enantiomerically pure compounds which are demanded e.g. in pharmaceutical industry, cosmetics or agriculture. In the field of asym- metric transfer hydrogenations (ATH) of C=N and C=O double bonds Noyori’s ruthenium (II) complexes represent significant breakthrough. This catalytic system consists of three integral parts - chiral monotosylated diamine ligand – i.e. N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine (TsDPEN), h 6 -coordinated aromatic molecule (e.g. benzene or p-cymene) and halogen counteranion (usually chloride). General formula of the catalyst can be written as [RuCl(h 6 - arene)(N-arylsulfonylDPEN)]. Aforementioned fragments/ ligands offer countless number of possibilities for structural modifications – e.g. elongation of carbonaceous spacer between phenyl rings within 1,2-diphenylethylendiamino fragment, alkylation of amino group, usage of diversely sub- stituted h 6 -aromatic molecule, employment of different aryls within arylsulfonyl fragment etc. Systematic evaluation of these modifications has multilateral benefits because it not only helps to clarify mechanistic phenomena but also contributes to the deeper understanding of relationship between structure and catalytic activity. With sufficiently big and rich data base it should be possible to tailor cata- lyst’s properties specifically for given substrate (or class of substrates) and reaction conditions (solubility, stability, etc.). Our research is focused primarily on comprehension of role of the h 6 -aromatic molecule during asymmetric transfer hydrogenation of imines. This ligand plays very important mechanistic role because its structure (respec- tively interaction with the substrate) allows asymmetric course of the reaction. Arene ligand can in certain cases form stabilizing CH/π interaction between aromatic part of substrate and therefore lower energy of transition state. This led us to the hypothesis that alteration of its structure could strongly affect enantioselectivity and reaction rate. This hypothesis has been brought up and discussed but only in case of ATH of C=O bonds, which dramatically dif- fers from hydrogenation of C=N bonds. Usually only simply alkyl-substituted arene molecules are used as aromatic ligands. In our study we have prepared and compared four catalysts with different aromatic ligands (benzene, p-cym- ene, mesitylene, 1,2,3,4,5,6-hexamethylbenzene) according to their performance (reaction rate, enantioselectivity) dur- ing hydrogenation of variously substituted 3,4-dihydroiso- quinolines and tried to interpret obtained results via means of computational chemistry. Acknowledgements This work has been financially supported by the Grant Agency of the Czech Republic (Grant GACR 106/12/1276). Published: 11 March 2014 doi:10.1186/1758-2946-6-S1-P39 Cite this article as: Kacer et al.: Computational evaluation of the h6- arene during the ATH of imines on Noyori’s RuII catalyst. Journal of Cheminformatics 2014 6(Suppl 1):P39. Open access provides opportunities to our colleagues in other parts of the globe, by allowing anyone to view the content free of charge. Publish with ChemistryCentral and every scientist can read your work free of charge W. Jeffery Hurst, The Hershey Company. available free of charge to the entire scientific community peer reviewed and published immediately upon acceptance cited in PubMed and archived on PubMed Central yours you keep the copyright Submit your manuscript here: http://www.chemistrycentral.com/manuscript/ * Correspondence: [email protected] Institute of Chemical Technology, Prague, 166 28, Czech Republic Kacer et al. Journal of Cheminformatics 2014, 6(Suppl 1):P39 http://www.jcheminf.com/content/6/S1/P39 © 2014 Kacer et al; licensee Chemistry Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http:// creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
Transcript of Computational evaluation of the η6-arene during the ATH of imines on Noyori’s RuII catalyst
POSTER PRESENTATION Open Access
Computational evaluation of the h6-arene duringthe ATH of imines on Noyori’s RuII catalystPetr Kacer*, Sot Petr, Jan Pechacek, Jakub Januscak, Marek Kuzma
From 9th German Conference on ChemoinformaticsFulda, Germany. 10-12 November 2013
Asymmetric hydrogenation ranks to the most intensivelyresearched way of preparation of enantiomerically purecompounds which are demanded e.g. in pharmaceuticalindustry, cosmetics or agriculture. In the field of asym-metric transfer hydrogenations (ATH) of C=N and C=Odouble bonds Noyori’s ruthenium (II) complexes representsignificant breakthrough. This catalytic system consists ofthree integral parts - chiral monotosylated diamine ligand –i.e. N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine(TsDPEN), h6-coordinated aromatic molecule (e.g. benzeneor p-cymene) and halogen counteranion (usually chloride).General formula of the catalyst can be written as [RuCl(h6-arene)(N-arylsulfonylDPEN)]. Aforementioned fragments/ligands offer countless number of possibilities for structuralmodifications – e.g. elongation of carbonaceous spacerbetween phenyl rings within 1,2-diphenylethylendiaminofragment, alkylation of amino group, usage of diversely sub-stituted h6-aromatic molecule, employment of differentaryls within arylsulfonyl fragment etc. Systematic evaluationof these modifications has multilateral benefits because itnot only helps to clarify mechanistic phenomena but alsocontributes to the deeper understanding of relationshipbetween structure and catalytic activity. With sufficientlybig and rich data base it should be possible to tailor cata-lyst’s properties specifically for given substrate (or class ofsubstrates) and reaction conditions (solubility, stability,etc.). Our research is focused primarily on comprehensionof role of the h6-aromatic molecule during asymmetrictransfer hydrogenation of imines. This ligand plays veryimportant mechanistic role because its structure (respec-tively interaction with the substrate) allows asymmetriccourse of the reaction. Arene ligand can in certain casesform stabilizing CH/π interaction between aromatic part ofsubstrate and therefore lower energy of transition state.This led us to the hypothesis that alteration of its structure
could strongly affect enantioselectivity and reaction rate.This hypothesis has been brought up and discussed butonly in case of ATH of C=O bonds, which dramatically dif-fers from hydrogenation of C=N bonds. Usually only simplyalkyl-substituted arene molecules are used as aromaticligands. In our study we have prepared and compared fourcatalysts with different aromatic ligands (benzene, p-cym-ene, mesitylene, 1,2,3,4,5,6-hexamethylbenzene) accordingto their performance (reaction rate, enantioselectivity) dur-ing hydrogenation of variously substituted 3,4-dihydroiso-quinolines and tried to interpret obtained results via meansof computational chemistry.
AcknowledgementsThis work has been financially supported by the Grant Agency of the CzechRepublic (Grant GACR 106/12/1276).
Published: 11 March 2014
doi:10.1186/1758-2946-6-S1-P39Cite this article as: Kacer et al.: Computational evaluation of the h6-arene during the ATH of imines on Noyori’s RuII catalyst. Journal ofCheminformatics 2014 6(Suppl 1):P39.
Open access provides opportunities to our colleagues in other parts of the globe, by allowing
anyone to view the content free of charge.
Publish with ChemistryCentral and everyscientist can read your work free of charge
W. Jeffery Hurst, The Hershey Company.
available free of charge to the entire scientific communitypeer reviewed and published immediately upon acceptancecited in PubMed and archived on PubMed Centralyours you keep the copyright
Submit your manuscript here:http://www.chemistrycentral.com/manuscript/* Correspondence: [email protected]
Institute of Chemical Technology, Prague, 166 28, Czech Republic
Kacer et al. Journal of Cheminformatics 2014, 6(Suppl 1):P39http://www.jcheminf.com/content/6/S1/P39
© 2014 Kacer et al; licensee Chemistry Central Ltd. This is an Open Access article distributed under the terms of the Creative CommonsAttribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction inany medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
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