The Experts below are selected from a list of 9993 Experts worldwide ranked by ideXlab platform
Eiichi Nakamura - One of the best experts on this subject based on the ideXlab platform.
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efficient formation of ring structures utilizing multisite activation by indium catalysis
Journal of the American Chemical Society, 2008Co-Authors: Yoshimitsu Itoh, Masaharu Nakamura, Kohei Endo, Hayato Tsuji, Kenichi Yamagata, Iku Tanaka, Eiichi NakamuraAbstract:Lewis acidic indium(III) salts, in particular In(NTf2)3, effect the conversion of α-(ω′-alkynyl)-β-Ketoesters and ω-alkynyl-β-Ketoesters to the corresponding cyclic products in a manner known as the Conia-ene reaction. This reaction can lead to the creation of five- to fifteen-membered-ring carbocycles and heterocycles in good to excellent yields. The synthetic features of the reaction are a relatively low catalyst loading, as low as 0.01 mol % in the best case, as well as no requirement of solvent for five-membered-ring formation and the requirement of only moderately dilute reaction conditions for medium-sized-ring formation. The high reactivity of indium salts is due to the double activation of the β-Ketoester substrate containing an acetylene function. The indium metal activates the β-Ketoester moiety by the formation of an indium enolate, and this indium metal electrophilically activates the alkyne moiety. Such a strong push−pull activation of the substrate by a single metal circumvents the disadvant...
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indium triflate catalyzed vinylation of β Ketoesters with acetylene gas
Organic Letters, 2005Co-Authors: Masaharu Nakamura, Kohei Endo, Eiichi NakamuraAbstract:An In(OTf)3-catalyzed addition of a β-Ketoester to acetylene in the presence of molecular sieves produces a α-vinylated Ketoester in good to excellent yield. The vinylation reaction proceeds without any loss of elements in starting molecules under solvent-free conditions and allows the use of welding-grade acetylene, providing a practical method for synthetic utilization of acetylene gas.
Ulrich Koert - One of the best experts on this subject based on the ideXlab platform.
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Total Synthesis of (-)-Preussochromone D.
Organic letters, 2019Co-Authors: Eric Kerste, Klaus Harms, Ulrich KoertAbstract:An efficient, stereoselective synthesis of the natural product (-)-preussochromone D is reported. The tricyclic skeleton was assembled by a diastereoselective intramolecular aldol addition of a chromanone to an α-Ketoester. Further key steps are an asymmetric 1,4-addition of diisopropenyl zinc to a chromenone and an intermolecular diastereoselective aldol addition of methyl diazoacetate to an aldehyde. The diazo group was oxidized to generate the α-Ketoester while oxidative side reactions at the chromanone could be prevented by the use of a difluoromethyl ether as a protecting group.
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hauser heck efficient synthesis of γ aryl β Ketoesters en route to substituted naphthalenes
Organic Letters, 2015Co-Authors: Frederic Wagner, Klaus Harms, Ulrich KoertAbstract:γ-Aryl-β-Ketoesters can be prepared in one step from aryl bromides and bis(trimethylsilyl) enol ethers using catalytic amounts of Pd(dba)2/t-Bu3P and stoichiometric amounts of Bu3SnF. The wide range of γ-(hetero)aryl-β-Ketoesters that can be obtained illustrate the scope and limitations of this novel Hauser–Heck combination. γ-Aryl-β-Ketoesters with a 1,3-dioxane acetal in the ortho position can easily be transformed into the hydroxy naphthoate in very good yield. Aqueous formic acid at 65 °C provides optimal conditions for this deprotective aromatization.
Janusz Zakrzewski - One of the best experts on this subject based on the ideXlab platform.
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Friedel−Crafts Type Reaction of Ferrocene with β-Ketoesters
The Journal of organic chemistry, 2002Co-Authors: Damian Plażuk, Janusz ZakrzewskiAbstract:The reaction of ferrocene with β-Ketoesters in the presence of BF3·Et2O or CF3SO3H affords β-ferrocenyl-α,β-unsaturated esters in 56−83% yield. In the case of α-unsubstituted-β-Ketoesters the reaction is totally E-stereoselective.
Dan Huang - One of the best experts on this subject based on the ideXlab platform.
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Unusual reaction of aryldiazoacetates with enamines: highly effective synthesis of γ-Ketoesters
Tetrahedron Letters, 2004Co-Authors: Ming Yan, Wei‐jie Zhao, Dan HuangAbstract:The reaction of aryldiazoacetates with enamines catalyzed by copper and rhodium complexes provided γ-Ketoesters in good yields. Careful analysis of the crude reaction mixture revealed a substituted enamine as the primary product, which was hydrolyzed over silica gel to give a γ-Ketoester as the final product. A reaction mechanism involving nucleophilic addition of an enamine to a metal carbene and subsequent hydrogen transfer was proposed.
Hongbin Zhai - One of the best experts on this subject based on the ideXlab platform.
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Copper-catalyzed decarboxylative propargylation/hydroamination reactions: access to C3 β-Ketoester-functionalized indoles.
Chemical Communications, 2018Co-Authors: Sasa Wang, Xinzheng Chen, Huifei Wang, Hongbin ZhaiAbstract:A copper-catalyzed reaction of ethynyl benzoxazinanones with readily accessible β-Ketoesters via a decarboxylative propargylation/hydroamination sequence has been developed. This protocol furnished a diverse range of C3 β-Ketoester-functionalized indoles in good to excellent yields.
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copper catalyzed decarboxylative propargylation hydroamination reactions access to c3 β Ketoester functionalized indoles
Chemical Communications, 2018Co-Authors: Sasa Wang, Xinzheng Chen, Huifei Wang, Hongbin Zhai, Miao LiuAbstract:A copper-catalyzed reaction of ethynyl benzoxazinanones with readily accessible β-Ketoesters via a decarboxylative propargylation/hydroamination sequence has been developed. This protocol furnished a diverse range of C3 β-Ketoester-functionalized indoles in good to excellent yields.
