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Peter Langer - One of the best experts on this subject based on the ideXlab platform.
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chemoselective suzuki miyaura cross coupling reactions of methyl 4 bromo 3 trifluoromethylsulfonyloxy 2 Naphthoate
Tetrahedron Letters, 2013Co-Authors: Zien Khaddour, Nadi Eleya, Omer A Akrawi, Aws M Hamdy, Tamas Patonay, Alexander Villinger, Peter LangerAbstract:Arylated naphthalenes were prepared by Suzuki–Miyaura cross-coupling reactions of methyl 4-bromo-3-(trifluoromethylsulfonyloxy)-2-Naphthoate. The reactions proceeded with very good chemoselectivity in favor of the triflate group, due to additive electronic ortho electronic effects.
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site selective suzuki miyaura cross coupling reactions of the bis triflate of methyl 3 7 dihydroxy 2 Naphthoate
Synlett, 2013Co-Authors: Zien Khaddour, Nadi Eleya, Omer A Akrawi, Aws M Hamdy, Tamas Patonay, Alexander Villinger, Peter LangerAbstract:Arylated naphthalenes were prepared by Suzuki–Miyaura reactions of the bis(triflate) of methyl 3,7-dihydroxy-2-Naphthoate. The reactions proceeded with very good site-selectivity in favor of the sterically less hindered position 7, despite the proximity of position 3 to the electron-withdrawing ester group which plays a decisive role for the site-selectivity of Suzuki–Miyaura reactions of related substrates.
Chenho Tung - One of the best experts on this subject based on the ideXlab platform.
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enhancement of diastereoselectivity in photodimerization of alkyl 2 Naphthoates with chiral auxiliaries via inclusion within γ cyclodextrin cavities
Journal of Organic Chemistry, 2012Co-Authors: Sufang Cheng, Chenho Tung, Liping Zhang, Xiujie Yang, Bin Chen, Yue Chen, Weihai Fang, Richard G WeissAbstract:Irradiations of alkyl 2-Naphthoates are known to result in four isomeric “cubane-like” photodimers: antiHH-2, synHH-2, antiHT-2, and synHT-2 where the antiHH-2, antiHT-2, and synHT-2 consist of pairs of diastereomers. Here, chiral auxiliary and chiral microreactor strategies have been combined to achieve high diastereoselectivity in photodimerizations of an enantiomeric pair of 2-Naphthoates with (R)- and (S)-1-methoxycarbonylethyl esters as chiral auxiliaries (1R and 1S). Thus, irradiations of their γ-cyclodextrin (γ-CD) complexes have been conducted. Fluorescence, IR, and NMR spectra of both enantiomers of 1 demonstrate that their γ-CD complexes are mainly 2:2 with the molecules of 1 in head-to-head orientations. Irradiation of the complexes in the solid state mainly resulted in antiHH-2. The absolute configuration of each diastereomer of antiHH-2 has been established for the first time here. The diastereomeric excesses (de's) of antiHH-2 from 1R and 1S were 94% and 86%, respectively. These de's are muc...
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stereoselective photodimerization of alkyl 3 alkoxyl 2 Naphthoates
Tetrahedron Letters, 2011Co-Authors: Bin Chen, Liping Zhang, Chenho TungAbstract:Photodimerization of methyl 3-alkoxyl-2-Naphthoates with chiral auxiliaries in the alkoxyl groups (1a and 1b) in organic solutions results in cubane-like photodimers. Asymmetric induction up to 90% diastereomeric excess (de) has been achieved and the absolute configuration of the pair of the diastereomers has been established.
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semiconductor photoinduced cycloreversion of the dimer of methyl 2 Naphthoate
Chinese Journal of Chemistry, 2010Co-Authors: Chenho Tung, Yunming YingAbstract:The dimer of methyl 2-Naphthoate (1) has been found to undergo efficient cycloreversion to its monomer, methyl naphthalene-2-carboxylate (2) on illuminated ZnO and TiO2 but not on CdS An electron transfer and cation radical chain mechanism is proposed. Quantum yields, solvent effect., the role of oxygen, and the quenching of the reaction were investigated, and were consistent with the proposed mechanism.
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cucurbit 8 uril mediated photodimerization of alkyl 2 Naphthoate in aqueous solution
Tetrahedron Letters, 2008Co-Authors: Lei Lei, Lin Luo, Guihong Liao, Chenho TungAbstract:The photodimerization of methyl 2-Naphthoate (1), ethyl 2-Naphthoate (2) and butyl 2-Naphthoate (3) in cucurbituril (CB) aqueous solution was investigated. The product distribution and fluorescence spectral changes suggest that CB[8] can encapsulate two molecules of alkyl 2-Naphthoate (1 or 2) and thereby facilitate a cubane-like photodimer formation. Subtle changes in either cavity size of CB[n] or alkyl substitutes can significantly modulate the interaction of CB[n] with 2-Naphthoate derivatives affording remarkable alterations in their photochemical reactivity.
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stereochemistry of a cubane like photodimer of methyl 2 Naphthoate
Tetrahedron Letters, 2006Co-Authors: Lei Lei, Lin Luo, Guihong Liao, Chenho Tung, Liping Zhang, Kuiling DingAbstract:Abstract A novel type of C2-symmetric-chiral ligand, based on a cubane-like photodimer 1 of methyl 2-Naphthoate, is reported in this work. Crystal analysis reveals that the methyl carboxylate functionality is in an anti-head-to-head conformation and 1 is highly rigid. The optically pure enantiomers of 1 can be obtained simply by HPLC resolution.
Zien Khaddour - One of the best experts on this subject based on the ideXlab platform.
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chemoselective suzuki miyaura cross coupling reactions of methyl 4 bromo 3 trifluoromethylsulfonyloxy 2 Naphthoate
Tetrahedron Letters, 2013Co-Authors: Zien Khaddour, Nadi Eleya, Omer A Akrawi, Aws M Hamdy, Tamas Patonay, Alexander Villinger, Peter LangerAbstract:Arylated naphthalenes were prepared by Suzuki–Miyaura cross-coupling reactions of methyl 4-bromo-3-(trifluoromethylsulfonyloxy)-2-Naphthoate. The reactions proceeded with very good chemoselectivity in favor of the triflate group, due to additive electronic ortho electronic effects.
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site selective suzuki miyaura cross coupling reactions of the bis triflate of methyl 3 7 dihydroxy 2 Naphthoate
Synlett, 2013Co-Authors: Zien Khaddour, Nadi Eleya, Omer A Akrawi, Aws M Hamdy, Tamas Patonay, Alexander Villinger, Peter LangerAbstract:Arylated naphthalenes were prepared by Suzuki–Miyaura reactions of the bis(triflate) of methyl 3,7-dihydroxy-2-Naphthoate. The reactions proceeded with very good site-selectivity in favor of the sterically less hindered position 7, despite the proximity of position 3 to the electron-withdrawing ester group which plays a decisive role for the site-selectivity of Suzuki–Miyaura reactions of related substrates.
Shigeaki Harayama - One of the best experts on this subject based on the ideXlab platform.
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structure of the ring cleavage product of 1 hydroxy 2 Naphthoate an intermediate of the phenanthrene degradative pathway of nocardioides sp strain kp7
Journal of Bacteriology, 1999Co-Authors: Kyoko Adachi, Tokuro Iwabuchi, Hiroshi Sano, Shigeaki HarayamaAbstract:1-Hydroxy-2-Naphthoate (compound I) is a metabolite of the phenanthrene-degradative pathway in Nocardioides sp. strain KP7. This singly hydroxylated aromatic compound is cleaved by 1-hydroxy-2-Naphthoate dioxygenase. In this study, the structure of the ring cleavage product generated by the action of homogeneous 1-hydroxy-2-Naphthoate dioxygenase was determined upon separation by high-performance liquid chromatography at pH 2.5 by using nuclear magnetic resonance (NMR) and mass spectroscopic techniques. The ring cleavage product at this pH existed in equilibrium between two forms, 2-oxo-3-(3-oxo-1,3-dihydro-1-isobenzofuranyl)propanoate (compound III) and 2,2-dihydroxy-3-(3-oxo-1,3-dihydro-1-isobenzofuranyl)propanoate (compound IV). After the pH of the solution was raised to 7.5, the structure of the major species became (E)-4-(2-carboxylatophenyl)-2-oxo-3-butenoate (compound II; common name, trans-2′-carboxybenzalpyruvate), which was in equilibrium with compound III. Direct monitoring of the enzymatic formation of the ring cleavage product by 1H-NMR in a deuterated potassium phosphate buffer (pH 7.5) detected only compound II as a product, and the proton on carbon 3 of compound II was not exchanged with deuterium. Thus, compound II is likely to be the first stable product of dioxygenation of 1-hydroxy-2-Naphthoate.
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biochemical and molecular characterization of 1 hydroxy 2 Naphthoate dioxygenase from nocardioides sp kp7
Journal of Biological Chemistry, 1998Co-Authors: Tokuro Iwabuchi, Shigeaki HarayamaAbstract:Abstract 1-Hydroxy-2-Naphthoate dioxygenase, which cleaves the singly hydroxylated aromatic ring, was purified from phenanthrene-degrading Nocardioides sp. strain KP7. The purified enzyme had a molecular mass of 45 kDa by SDS-polyacrylamide gel electrophoresis and 270 kDa by gel filtration chromatography. The apparent K m and k cat values of this enzyme for 1-hydroxy-2-Naphthoate were 10 μm and 114 s−1, respectively. One mole of molecular oxygen was consumed when 1 mol of 1-hydroxy-2-Naphthoate was oxidized. This enzyme contained 1 mol of Fe(II)/mol of the subunit and was inactivated byo-phenanthroline. The enzyme that had been inactivated byo-phenanthroline was reactivated by incubating with FeSO4 and ascorbic acid. Thus, Fe(II) was required for the enzyme to exhibit activity. The structural gene for this enzyme was screened from a cosmid library and then sequenced, the length of the 1-hydroxy-2-Naphthoate gene being 1161 base pairs. The deduced amino acid sequence of this enzyme was different from those of other ring-cleaving dioxygenases that cleave the doubly hydroxylated aromatic ring.
Alexander Villinger - One of the best experts on this subject based on the ideXlab platform.
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chemoselective suzuki miyaura cross coupling reactions of methyl 4 bromo 3 trifluoromethylsulfonyloxy 2 Naphthoate
Tetrahedron Letters, 2013Co-Authors: Zien Khaddour, Nadi Eleya, Omer A Akrawi, Aws M Hamdy, Tamas Patonay, Alexander Villinger, Peter LangerAbstract:Arylated naphthalenes were prepared by Suzuki–Miyaura cross-coupling reactions of methyl 4-bromo-3-(trifluoromethylsulfonyloxy)-2-Naphthoate. The reactions proceeded with very good chemoselectivity in favor of the triflate group, due to additive electronic ortho electronic effects.
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site selective suzuki miyaura cross coupling reactions of the bis triflate of methyl 3 7 dihydroxy 2 Naphthoate
Synlett, 2013Co-Authors: Zien Khaddour, Nadi Eleya, Omer A Akrawi, Aws M Hamdy, Tamas Patonay, Alexander Villinger, Peter LangerAbstract:Arylated naphthalenes were prepared by Suzuki–Miyaura reactions of the bis(triflate) of methyl 3,7-dihydroxy-2-Naphthoate. The reactions proceeded with very good site-selectivity in favor of the sterically less hindered position 7, despite the proximity of position 3 to the electron-withdrawing ester group which plays a decisive role for the site-selectivity of Suzuki–Miyaura reactions of related substrates.
