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Eric N Jacobsen - One of the best experts on this subject based on the ideXlab platform.
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macrocyclic bis Thioureas catalyze stereospecific glycosylation reactions
Science, 2017Co-Authors: Yongho Park, Kaid C Harper, Nadine Kuhl, Eugene E Kwan, Richard Y Liu, Eric N JacobsenAbstract:Carbohydrates are involved in nearly all aspects of biochemistry, but their complex chemical structures present long-standing practical challenges to their synthesis. In particular, stereochemical outcomes in glycosylation reactions are highly dependent on the steric and electronic properties of coupling partners; thus, carbohydrate synthesis is not easily predictable. Here we report the discovery of a macrocyclic bis-Thiourea Derivative that catalyzes stereospecific invertive substitution pathways of glycosyl chlorides. The utility of the catalyst is demonstrated in the synthesis of trans-1,2-, cis-1,2-, and 2-deoxy-β-glycosides. Mechanistic studies are consistent with a cooperative mechanism in which an electrophile and a nucleophile are simultaneously activated to effect a stereospecific substitution reaction.
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enantioselective acylation of silyl ketene acetals through fluoride anion binding catalysis
ChemInform, 2012Co-Authors: James A Birrell, Jeannicolas Desrosiers, Eric N JacobsenAbstract:The reaction is best catalyzed by the complex chiral Thiourea Derivative in combination with 4-pyrrolidinopyridine to afford the target α,α-disubstituted butyrolactone products with high yields and enantioselectivities.
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highly enantioselective direct conjugate addition of ketones to nitroalkenes promoted by a chiral primary amine Thiourea catalyst
Journal of the American Chemical Society, 2006Co-Authors: Hongbing Huang, Eric N JacobsenAbstract:Primary amine−Thiourea Derivative 1 is an active and highly enantioselective catalyst for the conjugate addition of ketones to nitroalkenes. Broad substrate scope is described, with nitroalkenes bearing either aromatic or aliphatic substituents and a wide variety of ketones shown to be useful reacting partners. Ethyl ketones react preferentially, generating anti products with methyl-bearing stereocenters with good-to-excellent diastereoselectivity. An enamine mechanism is indicated, with cooperative activation of the electrophile by the Thiourea and of the ketone by the primary amine.
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highly enantioselective direct conjugate addition of ketones to nitroalkenes promoted by a chiral primary amine Thiourea catalyst
Journal of the American Chemical Society, 2006Co-Authors: Hongbing Huang, Eric N JacobsenAbstract:Primary amine−Thiourea Derivative 1 is an active and highly enantioselective catalyst for the conjugate addition of ketones to nitroalkenes. Broad substrate scope is described, with nitroalkenes be...
Federica Balzano - One of the best experts on this subject based on the ideXlab platform.
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Thiourea Derivative of 2 1r 1 aminoethyl phenol a flexible pocket like chiral solvating agent csa for the enantiodifferentiation of amino acid Derivatives by nmr spectroscopy
Journal of Organic Chemistry, 2020Co-Authors: Alessandra Recchimurzo, Cosimo Micheletti, Gloria Uccellobarretta, Federica BalzanoAbstract:Thiourea Derivatives of 2-[(1R)-1-aminoethyl]phenol, (1S,2R)-1-amino-2,3-dihydro-1H-inden-2-ol, (1R,2R)-(1S,2R)-1-amino-2,3-dihydro-1H-inden-2-ol, and (R)-1-phenylethanamine have been compared as chiral solvating agents (CSAs) for the enantiodiscrimination of derivatized amino acids using nuclear magnetic resonance (NMR) spectroscopy. Thiourea Derivative, prepared by reacting 2-[(1R)-1-aminoethyl]phenol with benzoyl isothiocyanate, constitutes an effective CSA for the enantiodiscrimination of N-3,5-dinitrobenzoyl (DNB) Derivatives of amino acids with free or derivatized carboxyl functions. A base additive 1,4-diazabicyclo[2.2.2]octane(DABCO)/N,N-dimethylpyridin-4-amine (DMAP)/NBu4OH) is required both to solubilize amino acid Derivatives with free carboxyl groups in CDCl3 and to mediate their interaction with the chiral auxiliary to attain efficient differentiation of the NMR signals of enantiomeric substrates. For ternary systems CSA/substrate/DABCO, the chiral discrimination mechanism has been ascertained through the NMR determination of complexation stoichiometry, association constants, and stereochemical features of the diastereomeric solvates.
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Thiourea Derivative of 2 1r 1 aminoethyl phenol a flexible pocket like chiral solvating agent csa for the enantiodifferentiation of amino acid Derivatives by nmr spectroscopy
Journal of Organic Chemistry, 2020Co-Authors: Alessandra Recchimurzo, Cosimo Micheletti, Gloria Uccellobarretta, Federica BalzanoAbstract:Thiourea Derivatives of 2-[(1R)-1-aminoethyl]phenol, (1S,2R)-1-amino-2,3-dihydro-1H-inden-2-ol, (1R,2R)-(1S,2R)-1-amino-2,3-dihydro-1H-inden-2-ol, and (R)1-phenylethanamine have been compared as ch...
Hongbing Huang - One of the best experts on this subject based on the ideXlab platform.
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highly enantioselective direct conjugate addition of ketones to nitroalkenes promoted by a chiral primary amine Thiourea catalyst
Journal of the American Chemical Society, 2006Co-Authors: Hongbing Huang, Eric N JacobsenAbstract:Primary amine−Thiourea Derivative 1 is an active and highly enantioselective catalyst for the conjugate addition of ketones to nitroalkenes. Broad substrate scope is described, with nitroalkenes bearing either aromatic or aliphatic substituents and a wide variety of ketones shown to be useful reacting partners. Ethyl ketones react preferentially, generating anti products with methyl-bearing stereocenters with good-to-excellent diastereoselectivity. An enamine mechanism is indicated, with cooperative activation of the electrophile by the Thiourea and of the ketone by the primary amine.
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highly enantioselective direct conjugate addition of ketones to nitroalkenes promoted by a chiral primary amine Thiourea catalyst
Journal of the American Chemical Society, 2006Co-Authors: Hongbing Huang, Eric N JacobsenAbstract:Primary amine−Thiourea Derivative 1 is an active and highly enantioselective catalyst for the conjugate addition of ketones to nitroalkenes. Broad substrate scope is described, with nitroalkenes be...
Alessandra Recchimurzo - One of the best experts on this subject based on the ideXlab platform.
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Thiourea Derivative of 2 1r 1 aminoethyl phenol a flexible pocket like chiral solvating agent csa for the enantiodifferentiation of amino acid Derivatives by nmr spectroscopy
Journal of Organic Chemistry, 2020Co-Authors: Alessandra Recchimurzo, Cosimo Micheletti, Gloria Uccellobarretta, Federica BalzanoAbstract:Thiourea Derivatives of 2-[(1R)-1-aminoethyl]phenol, (1S,2R)-1-amino-2,3-dihydro-1H-inden-2-ol, (1R,2R)-(1S,2R)-1-amino-2,3-dihydro-1H-inden-2-ol, and (R)-1-phenylethanamine have been compared as chiral solvating agents (CSAs) for the enantiodiscrimination of derivatized amino acids using nuclear magnetic resonance (NMR) spectroscopy. Thiourea Derivative, prepared by reacting 2-[(1R)-1-aminoethyl]phenol with benzoyl isothiocyanate, constitutes an effective CSA for the enantiodiscrimination of N-3,5-dinitrobenzoyl (DNB) Derivatives of amino acids with free or derivatized carboxyl functions. A base additive 1,4-diazabicyclo[2.2.2]octane(DABCO)/N,N-dimethylpyridin-4-amine (DMAP)/NBu4OH) is required both to solubilize amino acid Derivatives with free carboxyl groups in CDCl3 and to mediate their interaction with the chiral auxiliary to attain efficient differentiation of the NMR signals of enantiomeric substrates. For ternary systems CSA/substrate/DABCO, the chiral discrimination mechanism has been ascertained through the NMR determination of complexation stoichiometry, association constants, and stereochemical features of the diastereomeric solvates.
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Thiourea Derivative of 2 1r 1 aminoethyl phenol a flexible pocket like chiral solvating agent csa for the enantiodifferentiation of amino acid Derivatives by nmr spectroscopy
Journal of Organic Chemistry, 2020Co-Authors: Alessandra Recchimurzo, Cosimo Micheletti, Gloria Uccellobarretta, Federica BalzanoAbstract:Thiourea Derivatives of 2-[(1R)-1-aminoethyl]phenol, (1S,2R)-1-amino-2,3-dihydro-1H-inden-2-ol, (1R,2R)-(1S,2R)-1-amino-2,3-dihydro-1H-inden-2-ol, and (R)1-phenylethanamine have been compared as ch...
Julio Duque - One of the best experts on this subject based on the ideXlab platform.
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synthesis structural and spectroscopic studies of 1 2 furoyl 3 phenylThiourea a theoretical and experimental approach
Journal of Sulfur Chemistry, 2016Co-Authors: O Estevezhernandez, Fernando Federico Salomon, Julio Duque, J Rodriguezhernandez, Diego M GilAbstract:ABSTRACTThe Thiourea Derivative 1-(2-Furoyl)-3-phenylThiourea (FPT) was synthesized and characterized by using spectroscopic (IR, Raman, UV–VIS, 1H and 13C NMR) and structural methods (powder X-ray diffraction data). The experimental measurements were complemented with quantum chemical calculations. FPT crystallizes in the monoclinic crystal system, space group P21/c, with cell parameters a = 4.7679(5) A, b = 20.9704(2) A, c = 12.5109(5) A and β = 109.811(10)°, V = 1176.87(3) A3. In the crystal structure, the Thiourea group makes dihedral angle of 43.8(5)° with the furoyl group, whereas the benzene ring is inclined by 24.3(4)°. The anti-syn geometry of the Thiourea unit is stabilized by intramolecular N–H … O hydrogen bond between the H atom of the syn thioamide and the carbonyl O atom. In the crystal structure, molecules of FPT are packed through N–H···S, C–H···O and C–H···C hydrogen bonds, and a π–π interaction with offset arrangement. Hirshfeld surface analysis was performed in order to evaluate and qu...
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Synthesis, structural and spectroscopic studies of 1-(2-FUROYL)-3-phenylThiourea: a theoretical and experimental approach
2016Co-Authors: Osvaldo Estévez-hernández, Fernando Federico Salomon, Julio Duque, Joelis Rodríguez-hernández, Diego M GilAbstract:The Thiourea Derivative 1-(2-Furoyl)-3-phenylThiourea (FPT) was synthesized and characterized by using spectroscopic (IR, Raman, UV–VIS, 1H and 13C NMR) and structural methods (powder X-ray diffraction data). The experimental measurements were complemented with quantum chemical calculations. FPT crystallizes in the monoclinic crystal system, space group P21/c, with cell parameters a = 4.7679(5) Å, b = 20.9704(2) Å, c = 12.5109(5) Å and β = 109.811(10)°, V = 1176.87(3) Å3. In the crystal structure, the Thiourea group makes dihedral angle of 43.8(5)° with the furoyl group, whereas the benzene ring is inclined by 24.3(4)°. The anti-syn geometry of the Thiourea unit is stabilized by intramolecular N–H … O hydrogen bond between the H atom of the syn thioamide and the carbonyl O atom. In the crystal structure, molecules of FPT are packed through N–H···S, C–H···O and C–H···C hydrogen bonds, and a π–π interaction with offset arrangement. Hirshfeld surface analysis was performed in order to evaluate and quantify intermolecular interactions. The Hirshfeld surface analysis indicated that the H···H interactions comprise the majority of interactions. Shape index and curvedness clearly indicate π–π interactions in the compound FPT.
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structural vibrational and electronic characterization of 1 benzyl 3 furoyl 1 phenylThiourea an experimental and theoretical study
New Journal of Chemistry, 2015Co-Authors: Maria Eliana Defonsi Lestard, Mauricio F Erben, O Estevezhernandez, Julio Duque, Diego M GilAbstract:1-Benzyl-3-furoyl-1-phenylThiourea is a Thiourea Derivative synthesized and characterized by means of vibrational spectroscopy (IR and Raman) multinuclear NMR (1H and 13C) and elemental analysis. The geometrical parameters of this compound obtained from XRD studies were compared with the calculated values [B3LYP/6-311++G(d,p)] showing a good agreement. As determined by XRD analysis performed previously, the title compound exhibits the U-shape conformation with the CO and CS double bonds in anticlinal geometry. This conformational feature is mainly dictated by the substitution degree on the Thiourea core and the ability to form an intramolecular N–H⋯OC hydrogen bond. The UV-visible absorption spectra of the compound in methanol solution were recorded and analyzed using time dependent density functional theory (TD-DFT). Molecular stability was investigated by applying the natural bond (NBO) analysis. Intermolecular interactions were evaluated by means of the AIM approach. The calculated HOMO and LUMO energies show that the charge transfer occurs in the molecule. The molecular electrostatic potential map was calculated by the DFT method. Non-linear optical (NLO) behavior of the title compound was investigated by determining the electric dipole moment, polarizability α, and hyperpolarizability β using B3LYP/6-311++G(d,p) approximation.