The Experts below are selected from a list of 4713 Experts worldwide ranked by ideXlab platform
Yasuyuki Kita - One of the best experts on this subject based on the ideXlab platform.
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metal free oxidative cross coupling reaction of thiophene iodonium salts with pyrroles
European Journal of Organic Chemistry, 2016Co-Authors: Koji Morimoto, Akira Nakamura, Toshifumi Dohi, Yasuyuki KitaAbstract:The hypervalent-iodine-mediated oxidative metal-free cross-coupling reaction of Thiophenes with various pyrroles was developed. The corresponding thiophene–pyrrole derivatives were obtained in moderate to high yields (up to 85 %). This method features high efficiency and regioselectivity and broad functional group tolerance. We further determined the highly planar characteristics of the 3,4-ethylenedioxythiophene–pyrrole biaryls caused by intramolecular hydrogen bonding.
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highly regioselective nucleophilic carbon carbon bond formation on furans and Thiophenes initiated by pummerer type reaction
Organic Letters, 2004Co-Authors: Shuji Akai, Norihito Kawashita, Hideharu Satoh, Yasufumi Wada, Keisuke Kakiguchi, Ikumi Kuriwaki, Yasuyuki KitaAbstract:The reactions of (phenylsulfinyl)furans or -Thiophenes with carbon nucleophiles in the presence of trifluoroacetic anhydride allowed the nucleophilic installation of carbon functional groups on the furan and thiophene nuclei with complete regioselectivity.
Igor Larrosa - One of the best experts on this subject based on the ideXlab platform.
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ag i c h activation enables near room temperature direct α arylation of benzo b Thiophenes
Journal of the American Chemical Society, 2018Co-Authors: Chiara Colletto, Adyasha Panigrahi, Jaime Fernandezcasado, Igor LarrosaAbstract:The first example of near-room-temperature α-arylation of benzo[b]Thiophenes is reported. The discovery rests on the observation of a switch in α-/β-regioselectivity at different loadings of Pd2(dba)3·CHCl3 in the coupling between benzo[b]thiophene and 4-iodotoluene. We show that this unprecedented regioselectivity switch is driven by a Ag(I)-mediated C–H activation at the α-C–H position, which becomes the dominant mode of reactivity at low concentrations of Pd. Competition experiments, kinetic studies, KIE, and D/H scrambling experiments have been carried out supporting this mechanism.
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Ag(I)–C–H Activation Enables Near-Room-Temperature Direct α‑Arylation of Benzo[b]Thiophenes
2018Co-Authors: Chiara Colletto, Adyasha Panigrahi, Jaime Fernández-casado, Igor LarrosaAbstract:The first example of near-room-temperature α-arylation of benzo[b]Thiophenes is reported. The discovery rests on the observation of a switch in α-/β-regioselectivity at different loadings of Pd2(dba)3·CHCl3 in the coupling between benzo[b]thiophene and 4-iodotoluene. We show that this unprecedented regioselectivity switch is driven by a Ag(I)-mediated C–H activation at the α-C–H position, which becomes the dominant mode of reactivity at low concentrations of Pd. Competition experiments, kinetic studies, KIE, and D/H scrambling experiments have been carried out supporting this mechanism
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room temperature direct β arylation of Thiophenes and benzo b Thiophenes and kinetic evidence for a heck type pathway
Journal of the American Chemical Society, 2016Co-Authors: Chiara Colletto, Saidul Islam, Francisco Juliahernandez, Igor LarrosaAbstract:The first example of a regioselective β-arylation of benzo[b]Thiophenes and Thiophenes at room temperature with aryl iodides as coupling partners is reported. This methodology stands out for its operational simplicity: no prefunctionalization of either starting material is required, the reaction is insensitive to air and moisture, and it proceeds at room temperature. The mild conditions afford wide functional group tolerance, often with complete regioselectivity and high yields, resulting in a highly efficient catalytic system. Initial mechanistic studies, including 13C and 2H KIEs, suggest that this process occurs via a concerted carbo-palladation across the thiophene double bond, followed by a base-assisted anti-elimination.
Gladys Wang - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of Polysubstituted BenzoThiophenes and Sulfur-Containing Polycyclic Aromatic Compounds via Samarium Diiodide Promoted Three-Component Coupling Reactions of Thiophene-2-carboxylate
Journal of Organic Chemistry, 2002Co-Authors: Shyh-ming Yang, Jiun-jie Shie, Syn-hung Lu, Suman Kumar Nandy, Hung-yu Chang, Jim-min Fang, Gladys WangAbstract:By the promotion of samarium diiodide, thiophene-2-carboxylate reacted with 2 equiv of ketones at the C-4 and C-5 positions to give diols such as 2 and 9. Because the intermediary organosamarium species were oxophilic but not too basic, the double hydroxyalkylations with various ketone substrates, including alkyl aryl ketones, acetylThiophenes, cyclohexanone, α-tetralone, and α-phenylacetophenones, were realized without complication of side reactions. The diol products underwent an acid-catalyzed dehydration to give dienes such as 3 and 10, which were treated with DDQ to give either polysubstituted Thiophenes (e.g., 4 and 11) or benzoThiophenes (e.g., 5, 13, and 14) depending on the reaction conditions. Oxidative annulations of 4,5-diarylThiophenes 11 and 4,5,6,7-tetraphenylbenzoThiophenes 14 were carried out by photochemical or chemical methods to give the sulfur-containing polycyclic aromatic compounds, such as phenanthro[9,10-b]thiophene-2-carboxylate, piceno[13,14-b]thiophene-2-carboxylate, and triben...
Jan Paradies - One of the best experts on this subject based on the ideXlab platform.
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palladium catalyzed c s coupling access to thioethers benzo b Thiophenes and thieno 3 2 b Thiophenes
Organic Letters, 2011Co-Authors: Marius Kuhn, Florian C Falk, Jan ParadiesAbstract:The first C–S bond formation/cross-coupling/cyclization domino reaction using thiourea as a cheap and easy to handle dihydrosulfide surrogate has been developed. Structurally important biarylthioether, benzo[b]Thiophenes, and thieno[3,2-b]thiophene scaffolds are provided in high yield.
George J. Wullems - One of the best experts on this subject based on the ideXlab platform.
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effect of exogenous auxin on root morphology and secondary metabolism in tagetes patula hairy root cultures
Physiologia Plantarum, 1995Co-Authors: R R J Arroo, Anton F. Croes, A Develi, H Meijers, E Van De Westerlo, A Kemp, George J. WullemsAbstract:In this paper the effects of indole-3-acetic acid (IAA) on growth of Tagetes patula hairy root cultures and secondary product formation are presented. The biosynthesis of Thiophenes, sulfurous compounds with nematicidal activity, was inhibited by IAA application, as was evident from a decrease of [ 35 S]sulfur incorporation. The inhibition only occurred after the roots had developed numerous laterals as a result of auxin action. However, in roots cultured in the absence of IAA, there was no significant correlation between branching and thiophene accumulation. Therefore, development of lateral roots is not a sufficient condition for a low capacity to synthesize Thiophenes. The highest rate of thiophene accumulation in the roots is found during the late exponential growth phase, when the weight increase of a root culture is at its maximum. Hence, growth and the production of Thiophenes appear to be compatible in T. patula hairy roots
