The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Kengo Hanaya - One of the best experts on this subject based on the ideXlab platform.
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recognition of the remote chiral center in lipase catalyzed kinetic resolution of 2 methyl 2 2 naphthyl 1 3 benzodioxol 4 yl methyl acetate the precursor of 2 methyl 2 2 naphthyl 1 3 benzodioxole 4 carboxylic acid mnb carboxylic acid
Journal of Molecular Catalysis B-enzymatic, 2014Co-Authors: Naoki Natori, Kaoruko Nakagawara, Mitsuru Shoji, Takeshi Sugai, Kengo HanayaAbstract:Abstract To access the enantiomers of 2-Methyl-2-(2′-naphthyl)-1,3-benzodioxole-4-carboxylic acid (MNB carboxylic acid), lipase-catalyzed kinetic resolution of racemic [2-Methyl-2-(2′-naphthyl)-1,3-benzodioxol-4-yl]methyl acetate was examined with Burkholderia cepacia lipase (Amano PS-IM) and Candida antarctica lipase B (Novozym 435) under transesterification conditions. Enantioselectivity of B. cepacia lipase ( E = 72) was higher than that of C. antarctica lipase B ( E = 1.7), and these lipases showed a reversal of enantiopreference in the recognition of a remote chiral center. The computational study showed that the tetrahedral intermediate complex of B. cepacia lipase with ( R )- 4a , the fast isomer, was more stable than that with ( S )- 4a , the slow isomer. The repetitive use of B. cepacia lipase and further chemical transformation provided both enantiomers [( R )-: 99.4% ee and ( S )-: 99.4% ee] of MNB carboxylic acid as methyl esters.
Hoongkun Fun - One of the best experts on this subject based on the ideXlab platform.
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2 amino 5 methyl pyridinium 2 hy droxy benzoate
Acta Crystallographica Section E-structure Reports Online, 2010Co-Authors: Ching Kheng Quah, Madhukar Hemamalini, Hoongkun FunAbstract:In the title compound, C6H9N2+·C7H5O3−, the protonated 2-amino-5-methylpyridinium cation and the 2-hydroxybenzoate anion are both essentially planar, with maximum deviations of 0.026 (2) and 0.034 (1) A, respectively. The anion is stabilized by an intramolecular O—H⋯O hydrogen bond, which forms an S(6) ring motif. In the solid state, the anions are linked to the cations via pairs of intermolecular N—H⋯O hydrogen bonds forming R22(8) ring motifs. The crystal structure is further stabilized by N—H⋯O and C—H⋯O interactions which link the molecules into chains along [010]. A π–π stacking interaction [centroid–centroid-distance = 3.740 (2) A] is also observed.
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2 amino 5 methyl pyridinium 2 carb oxy benzoate
Acta Crystallographica Section E-structure Reports Online, 2010Co-Authors: Madhukar Hemamalini, Hoongkun FunAbstract:In the title salt, C6H9N2+·C8H5O4−, the hydrogen phthalate anion is essentially planar, with a maximum deviation of 0.011 (2) A. In the crystal structure, the protonated N atom of the pyridine ring and the 2-amino group of the cation are hydrogen bonded to the carboxylate O atoms of the anion via a pair of N—H⋯O hydrogen bonds, forming an R22(8) ring motif. In the hydrogen phthalate anion, there is a very strong, almost symmetric, intramolecular O—H⋯O hydrogen bond, generating an S(7) motif [O⋯O = 2.382 (3) A]. Furthermore, these two molecular motif rings are connected by a bifurcated N—H⋯(O,O) hydrogen-bonded motif R12(4), forming a supramolecular ribbon along the b axis. The crystal structure is further stabilized by π–π interactions between the cations and anions [centroid–centroid distance = 3.6999 (10) A].
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2 amino 4 methyl pyridinium 2 carb oxy benzoate
Acta Crystallographica Section E-structure Reports Online, 2010Co-Authors: Ching Kheng Quah, Madhukar Hemamalini, Hoongkun FunAbstract:In the title molecular salt, C6H9N2+·C8H5O4−, the anion is stabilized by an intramolecular O—H⋯O hydrogen bond, which generates an S(7) ring motif. In the crystal, the cations and anions are linked to form extended chains along [001] by O—H⋯O and N—H⋯O hydrogen bonds. Adjacent chains are crosslinked via C—H⋯O interactions into sheets lying parallel to (100).
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2 amino 4 methyl pyridinium 2 hy droxy benzoate
Acta Crystallographica Section E-structure Reports Online, 2010Co-Authors: Madhukar Hemamalini, Hoongkun FunAbstract:The asymmetric unit of the title molecular salt, C6H9N2+·C7H5O3−, contains two cations and two anions. Both the salicylate anions contain an intramolecular O—H⋯O hydrogen bond, which generates an S(6) ring. Both the 2-amino-4-methylpyridine molecules are protonated at their pyridine N atoms. In the crystal, both cations form two N—H⋯O hydrogen bonds to their adjacent anions, forming ion pairs. Further N—H⋯O links generate sheets lying parallel to the ab plane. In addition, weak C—H⋯O bonds and aromatic π–π stacking interactions [centroid–centroid distances = 3.5691 (9) and 3.6215 (9) A] are observed between the cations and anions.
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methyl 2 acetamido 2 1 acetyl 3 hydr oxy 2 oxoindolin 3 yl propanoate
Acta Crystallographica Section E-structure Reports Online, 2010Co-Authors: Hoongkun Fun, Jia Hao Goh, Yang Liu, Yan ZhangAbstract:In the title isatin compound, C16H18N2O6, the pyrrolidine ring adopts an envelope conformation and is inclined at a dihedral angle of 7.31 (5)° with respect to the benzene ring. The acetyl group is disordered over two positions with refined occupancies of 0.503 (4) and 0.497 (4). These groups make dihedral angles of 12.6 (6) and 19.6 (7)° with the pyrrolidine ring. In the crystal structure, intermolecular C—H⋯O hydrogen bonds link neighbouring molecules into infinite chains along the b axis. These chains are further interconnected by intermolecular O—H⋯O hydrogen bonds into two-dimensional arrays parallel to the bc plane. Weak intermolecular C—H⋯π interactions further stabilize the crystal structure.
Naoki Natori - One of the best experts on this subject based on the ideXlab platform.
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recognition of the remote chiral center in lipase catalyzed kinetic resolution of 2 methyl 2 2 naphthyl 1 3 benzodioxol 4 yl methyl acetate the precursor of 2 methyl 2 2 naphthyl 1 3 benzodioxole 4 carboxylic acid mnb carboxylic acid
Journal of Molecular Catalysis B-enzymatic, 2014Co-Authors: Naoki Natori, Kaoruko Nakagawara, Mitsuru Shoji, Takeshi Sugai, Kengo HanayaAbstract:Abstract To access the enantiomers of 2-Methyl-2-(2′-naphthyl)-1,3-benzodioxole-4-carboxylic acid (MNB carboxylic acid), lipase-catalyzed kinetic resolution of racemic [2-Methyl-2-(2′-naphthyl)-1,3-benzodioxol-4-yl]methyl acetate was examined with Burkholderia cepacia lipase (Amano PS-IM) and Candida antarctica lipase B (Novozym 435) under transesterification conditions. Enantioselectivity of B. cepacia lipase ( E = 72) was higher than that of C. antarctica lipase B ( E = 1.7), and these lipases showed a reversal of enantiopreference in the recognition of a remote chiral center. The computational study showed that the tetrahedral intermediate complex of B. cepacia lipase with ( R )- 4a , the fast isomer, was more stable than that with ( S )- 4a , the slow isomer. The repetitive use of B. cepacia lipase and further chemical transformation provided both enantiomers [( R )-: 99.4% ee and ( S )-: 99.4% ee] of MNB carboxylic acid as methyl esters.
Taeko Izumi - One of the best experts on this subject based on the ideXlab platform.
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synthesis of ethyl 5 cyano 6 hydroxy 2 methyl 4 1 naphthyl nicotinate
Tetrahedron Letters, 2008Co-Authors: Yongchang Zhou, Tatsuro Kijima, Shunsuke Kuwahara, Masataka Watanabe, Taeko IzumiAbstract:Abstract A novel ethyl 5-cyano-6-hydroxy-2-methyl-4-(1-naphthyl)-nicotinate is successfully synthesized and the structure is determined by XRD, GC–MS analysis, element analysis and NMR spectroscopic in detail. A reaction mechanism for the reaction is proposed.
Nuri Kiraz - One of the best experts on this subject based on the ideXlab platform.
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synthesis and antibacterial activities of some 1 2 substituted pyrrol 1 yl ethyl 2 methyl 5 nitroimidazole derivatives
European Journal of Medicinal Chemistry, 1999Co-Authors: Seref Demirayak, Ahmet Cagri Karaburun, Nuri KirazAbstract:In this study, some 1-[2-(substituted pyrrol-1-yl)ethyl]-2-methyl-5-nitroimidazole derivatives were synthesized by reacting 2-(2-methyl-5-nitro-1H-imidazolyl)ethylamine dihydrochloride, which was prepared using metronidazole, with some 1,4-dicarbonyl compounds. The structure elucidation of the compounds was performed by IR, 1H-NMR and mass spectroscopic data and elemental analysis results. Antimicrobial activities of the compounds were examined and notable activity was obtained.