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Miloš Sedlák - One of the best experts on this subject based on the ideXlab platform.
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Henry reaction catalyzed by new series of imidazolidine-4-one Cu-complexes
Tetrahedron-asymmetry, 2015Co-Authors: Pavel Drabina, Zdeňka Růžičková, Eva Horáková, Miloš SedlákAbstract:Abstract A series of 5- tert -butyl-2-(pyridine-2-yl)imidazolidine-4-ones have been prepared and their Cu(II) complexes studied as enantioselective catalysts of the asymmetric Henry reaction of various aldehydes with nitromethane. It was found that these compounds were effective catalysts for this reaction, with enantiomeric excesses being as high as 97%. The enantioselectivities of individual derivatives were different and depended on the substituents attached to stereogenic centers and the configuration of imidazolidine-4-one cycle. High enantiomeric excesses were obtained irrespective of the solvent used. The most effective derivative was chosen for preparation of the key intermediate for Salmeterol medical drug and an enantiomeric excess of 92% was obtained.
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enantiocatalytic activity of substituted 5 benzyl 2 pyridine 2 yl imidazolidine 4 one ligands
ChemInform, 2013Co-Authors: Pavel Drabina, Sergej Karel, Illia Panov, Miloš SedlákAbstract:The copper(II) complexes of newly synthesized chiral ligands (I) are studied as enantioselective catalysts for the Henry reaction.
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enantiocatalytic activity of substituted 5 benzyl 2 pyridine 2 yl imidazolidine 4 one ligands
Tetrahedron-asymmetry, 2013Co-Authors: Pavel Drabina, Sergej Karel, Illia Panov, Miloš SedlákAbstract:Abstract Currently, asymmetric synthesis represents one of the main streams of organic synthesis. Although an extensive research has been carried out in this area, the synthesis of chiral compounds with the required enantiomeric purity is still a challenging issue. Herein, we focus on the preparation of new enantioselective catalysts based on pyridine-imidazolidinones. The substituted 5-benzyl-2-(pyridine-2-yl)imidazolidine-4-ones 5–8 were prepared by condensation of chiral amino acid amides (α-methylDOPA and α-methylphenylalanine) with 2-acetylpyridine and pyridine-2-carbaldehyde. The individual isomers of the described ligands 5 – 8 were separated chromatographically. The copper(II) complexes of these chiral ligands were studied as enantioselective catalysts for the asymmetric Henry reaction of substituted aldehydes with nitromethane or nitroethane. The ligands containing a methyl group at the 2-position of the imidazolidinone ring 6a and 8a exhibit a high degree of enantioselectivity (up to 91% ee). The nitroaldols derived from nitroethane (2-nitropropan-1-ols) were obtained with a comparable enantiomeric purity to derivatives of 2-nitroethanol. This group of ligands represents a new and promising class of enantioselective catalysts, which deserve further attention.
Pavel Drabina - One of the best experts on this subject based on the ideXlab platform.
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Henry reaction catalyzed by new series of imidazolidine-4-one Cu-complexes
Tetrahedron-asymmetry, 2015Co-Authors: Pavel Drabina, Zdeňka Růžičková, Eva Horáková, Miloš SedlákAbstract:Abstract A series of 5- tert -butyl-2-(pyridine-2-yl)imidazolidine-4-ones have been prepared and their Cu(II) complexes studied as enantioselective catalysts of the asymmetric Henry reaction of various aldehydes with nitromethane. It was found that these compounds were effective catalysts for this reaction, with enantiomeric excesses being as high as 97%. The enantioselectivities of individual derivatives were different and depended on the substituents attached to stereogenic centers and the configuration of imidazolidine-4-one cycle. High enantiomeric excesses were obtained irrespective of the solvent used. The most effective derivative was chosen for preparation of the key intermediate for Salmeterol medical drug and an enantiomeric excess of 92% was obtained.
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enantiocatalytic activity of substituted 5 benzyl 2 pyridine 2 yl imidazolidine 4 one ligands
ChemInform, 2013Co-Authors: Pavel Drabina, Sergej Karel, Illia Panov, Miloš SedlákAbstract:The copper(II) complexes of newly synthesized chiral ligands (I) are studied as enantioselective catalysts for the Henry reaction.
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enantiocatalytic activity of substituted 5 benzyl 2 pyridine 2 yl imidazolidine 4 one ligands
Tetrahedron-asymmetry, 2013Co-Authors: Pavel Drabina, Sergej Karel, Illia Panov, Miloš SedlákAbstract:Abstract Currently, asymmetric synthesis represents one of the main streams of organic synthesis. Although an extensive research has been carried out in this area, the synthesis of chiral compounds with the required enantiomeric purity is still a challenging issue. Herein, we focus on the preparation of new enantioselective catalysts based on pyridine-imidazolidinones. The substituted 5-benzyl-2-(pyridine-2-yl)imidazolidine-4-ones 5–8 were prepared by condensation of chiral amino acid amides (α-methylDOPA and α-methylphenylalanine) with 2-acetylpyridine and pyridine-2-carbaldehyde. The individual isomers of the described ligands 5 – 8 were separated chromatographically. The copper(II) complexes of these chiral ligands were studied as enantioselective catalysts for the asymmetric Henry reaction of substituted aldehydes with nitromethane or nitroethane. The ligands containing a methyl group at the 2-position of the imidazolidinone ring 6a and 8a exhibit a high degree of enantioselectivity (up to 91% ee). The nitroaldols derived from nitroethane (2-nitropropan-1-ols) were obtained with a comparable enantiomeric purity to derivatives of 2-nitroethanol. This group of ligands represents a new and promising class of enantioselective catalysts, which deserve further attention.
Rosario Herranz - One of the best experts on this subject based on the ideXlab platform.
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chameleonic reactivity of α amino nitrile derived ureas synthesis of highly functionalized imidazolidin 2 one and imidazolidine 2 4 dione derivatives
ChemInform, 2014Co-Authors: Pilar Ventosaandres, Juan A Gonzalezvera, Teresa M Garcialopez, Rosario HerranzAbstract:Neutral, basic or mild acidic reaction conditions are evaluated for N-cyanoalkyl-substituted ureas of type (I) and (III) resulting in cyclization to imidazolidine derivatives.
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chameleonic reactivity of α amino nitrile derived ureas synthesis of highly functionalized imidazolidin 2 one and imidazolidine 2 4 dione derivatives
Tetrahedron, 2014Co-Authors: Pilar Ventosaandres, Juan A Gonzalezvera, Teresa M Garcialopez, Rosario HerranzAbstract:Abstract The potential of α-amino nitrile-derived ureas for the synthesis of Imidazolidin-2-One derivatives has been studied in the context of a medicinal chemistry project focused on the search of antagonists of the thrombin receptor PAR1. In this study α-amino nitrile-derived ureas have shown chameleonic reactivity. Thus, under neutral, basic or mild acid media they cyclize to 4-iminoImidazolidin-2-One derivatives, which tautomerize to 4-amino-2,3-dihydro-1 H -imidazol-2-ones. This tautomerism triggers epimerization at the C 5 of the imidazolidine ring, as well as its oxidation. However, they give stable highly functionalized hydantoin derivatives under strong acid media, by a no-epimerizing two-step hydrolysis.
Joaquín Tamariz - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of exo-Imidazolidin-2-One Dienes, Their Isomerization, and Selectivity in Diels–Alder Cycloadditions
The Journal of organic chemistry, 2018Co-Authors: Carlos Espinoza-hicks, Rafael Bautista, Francisco Delgado, Pablo A. Montoya, Hugo A. Jiménez-vázquez, Luz María Rodríguez-valdez, Alejandro Camacho-dávila, Fernando P. Cossío, Joaquín TamarizAbstract:An efficient and alternative synthesis of exo-Imidazolidin-2-One dienes is described. A condensation reaction was carried out with bis-imino derivatives, diacetyl, and triphosgene, affording symmetrically N,N-disubstituted dienes. The use of alkyl methyl α-diketones led to the formation of nonsymmetrical dienes, which underwent isomerization to provide more stable inner-outer-ring dienes under Lewis acid conditions. Evaluation was made of the reactivity as well as regio- and stereoselectivity of these dienes in Diels–Alder reactions. They proved to be highly reactive and selective. DFT calculations of the transition states accounted for their behavior.
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Synthesis and Diels—Alder Cycloadditions of exo-Imidazolidin-2-One Dienes.
ChemInform, 2012Co-Authors: Rafael Bautista, Pablo Bernal, Rafael Herrera, Blanca M. Santoyo, J. Miguel Lazcano-seres, Francisco Delgado, Joaquín TamarizAbstract:Base-mediated coupling of imines of type (III) with isocyanates allows an efficient access to novel title compounds.
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Synthesis and Diels–Alder Cycloadditions of exo-Imidazolidin-2-One Dienes
The Journal of organic chemistry, 2011Co-Authors: Rafael Bautista, Pablo Bernal, Rafael Herrera, Blanca M. Santoyo, J. Miguel Lazcano-seres, Francisco Delgado, Joaquín TamarizAbstract:An efficient and versatile synthesis of novel exo-Imidazolidin-2-One dienes is described. This involves the base-assisted condensation/cyclization cascade reaction of the monoimino derivatives of diacetyl with a series of isocyanates. This methodology enables preparation of symmetrical dienes, as long as the substrates have the same N substituent. Moreover, use of different N-substituted starting materials leads to formation of nonsymmetrical dienes. The reactivity of these dienes was evaluated in Diels–Alder reactions, showing a high reactivity.
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Synthesis and DielsAlder Cycloadditions of exo-Imidazolidin- 2-one Dienes
2011Co-Authors: Rafael Bautista, Pablo Bernal, Rafael Herrera, Blanca M. Santoyo, J. Miguel Lazcano-seres, Francisco Delgado, Joaquín TamarizAbstract:ABSTRACT:An efficient and versatile synthesis of novel exo-Imidazolidin-2-One dienes is described. This involves the base-assistedcondensation/cyclizationcascade reactionofthemonoiminoderivatives ofdiacetylwithaseriesofisocyanates.Thismethodologyenables preparation of symmetrical dienes, as long as the substrates have the same N substituent. Moreover, use of differentN-substituted starting materials leads to formation of nonsymmetrical dienes. The reactivity of these dienes was evaluated inDiels Alder reactions, showing a high reactivity.’INTRODUCTIONConjugated dienes represent a privileged molecular system forevaluatingthestereospecificity,endo/exostereoselectivity,regios-electivity, and π-facial control, among other properties, inDiels Alder cycloaddition. 1 Owing to the seminal importanceof this process from a theoretical point of view, 2 as well as to itspotential in synthesis, 3 a diversity of dienes have been designed,includingouter-ringo-carbodimethylenes. 4 Inparticular,therehasbeen considerable interest in the preparation and study of thereactivity of exo-heterocyclic dienes,
Pilar Ventosaandres - One of the best experts on this subject based on the ideXlab platform.
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chameleonic reactivity of α amino nitrile derived ureas synthesis of highly functionalized imidazolidin 2 one and imidazolidine 2 4 dione derivatives
ChemInform, 2014Co-Authors: Pilar Ventosaandres, Juan A Gonzalezvera, Teresa M Garcialopez, Rosario HerranzAbstract:Neutral, basic or mild acidic reaction conditions are evaluated for N-cyanoalkyl-substituted ureas of type (I) and (III) resulting in cyclization to imidazolidine derivatives.
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chameleonic reactivity of α amino nitrile derived ureas synthesis of highly functionalized imidazolidin 2 one and imidazolidine 2 4 dione derivatives
Tetrahedron, 2014Co-Authors: Pilar Ventosaandres, Juan A Gonzalezvera, Teresa M Garcialopez, Rosario HerranzAbstract:Abstract The potential of α-amino nitrile-derived ureas for the synthesis of Imidazolidin-2-One derivatives has been studied in the context of a medicinal chemistry project focused on the search of antagonists of the thrombin receptor PAR1. In this study α-amino nitrile-derived ureas have shown chameleonic reactivity. Thus, under neutral, basic or mild acid media they cyclize to 4-iminoImidazolidin-2-One derivatives, which tautomerize to 4-amino-2,3-dihydro-1 H -imidazol-2-ones. This tautomerism triggers epimerization at the C 5 of the imidazolidine ring, as well as its oxidation. However, they give stable highly functionalized hydantoin derivatives under strong acid media, by a no-epimerizing two-step hydrolysis.