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Yoshiaki Nishibayashi - One of the best experts on this subject based on the ideXlab platform.
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Mechanism and reactivity of catalytic propargylic Substitution Reactions via metal–allenylidene intermediates: a theoretical perspective
Catalysis Science & Technology, 2018Co-Authors: Ken Sakata, Yoshiaki NishibayashiAbstract:Development of transition metal-catalyzed propargylic Substitution Reactions is still in progress as a novel synthetic tool, while a variety of allylic Substitution Reactions have been well established and widely used in organic synthesis. In this review, we summarize the mechanism and reactivity of transition metal-catalyzed propargylic Substitution Reactions from a theoretical point of view. We classify the reaction mechanisms for transition metal-catalyzed propargylic Substitution Reactions which have been reported to date, and then discuss, in particular, the Reactions via metal–allenylidene intermediates.
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transition metal catalyzedenantioselective propargylic Substitution Reactions ofpropargylic alcohol derivatives with nucleophiles
Synthesis, 2012Co-Authors: Yoshiaki NishibayashiAbstract:Recent advances in the transition-metal-catalyzed enantioselectivepropargylic Substitution Reactions of propargylic alcohol derivativeswith nucleophiles are reviewed in this article. After the disclosureof the first example of a ruthenium-catalyzed propargylic alkylation,various types of enantioselective propargylic Substitution Reactions,including enantioselective propargylation of aromatic compounds,have been reported in the last eight years. In addition, a varietyof enantioselective propargylic alkylations use two distinct catalysts,where the two catalysts work cooperatively to promote the asymmetricReactions. 1 Introduction 2 Ruthenium-Catalyzed Enantioselective Propargylic SubstitutionReactions 2.1 Propargylic Alkylation 2.2 Propargylation of Aromatic Compounds with Propargylic Alcohols 2.3 Propargylic Substitution Reactions of Propargylic Alcohols withAlkenes 2.4 Cycloadditions between Propargylic Alcohols and 2-Naphthols 3 Copper-Catalyzed Enantioselective Propargylic SubstitutionReactions 3.1 Propargylic Amination 3.2 Ring-Opening Reactions of Ethynyl Epoxides 3.3 Propargylic Alkylation 3.4 Propargylation of Indoles 4 Cooperative Enantioselective Propargylic Alkylations -UsingTransition-Metal Catalysts and Organocatalysts 4.1 With Ruthenium Catalysts 4.2 With Copper Catalysts 4.3 With Lewis Acid Catalysts 5 Cooperative Reactions Using Distinct Transition-Metal Catalysts 6 Miscellaneous Reactions 7 Conclusion
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Catalytic Propargylic Substitution Reactions
ChemCatChem, 2009Co-Authors: Yoshihiro Miyake, Sakae Uemura, Yoshiaki NishibayashiAbstract:In sharp contrast to the well-established transition metal- catalyzed allylic Substitution Reactions, the study of the corresponding propargylic Substitution Reactions has been quite limited for constructing carbon–carbon and carbon–heteroatom bonds at the propargylic position. However, during the last decade, general and useful catalytic Reactions have been developed extensively. In this Review, we summarize recent advances in catalytic propargylic Substitution Reactions of propargylic alcohols and their derivatives with heteroatom- and carbon-centered nucleophiles. In addition to a variety of transition metals, such as Ru, Re, Rh, Ir, Ni, Pd, Pt, and Cu, which form organometallic species as intermediates, several Lewis acids and Bronsted acids are also applicable as catalysts in these Reactions. The reaction mechanism and the scope of nucleophiles that can be used depend on the nature of the catalysts. Some examples of enantioselective Substitution Reactions at the propargylic position are also described.
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Ruthenium-catalyzed vinylic Substitution Reactions with nucleophiles via butatrienylidene intermediates.
Journal of the American Chemical Society, 2008Co-Authors: Yoshihiro Yamauchi, Yoshihiro Miyake, Sakae Uemura, Masahiro Yuki, Yoshiaki Tanabe, Youichi Inada, Yoshiaki NishibayashiAbstract:Novel ruthenium-catalyzed vinylic Substitution Reactions of vinylic trifluoromethanesulfonates with nucleophiles such as cyclic 1,3-diketones and alcohols have been found to give the corresponding vinylic-substituted products in good to high yields. This catalytic reaction is considered to be a new type of vinylic Substitution reaction. Reactions of α-ketoacetylenes with alcohols have also been found to afford the corresponding vinylic ethers in good yields. These catalytic Reactions can be explained to proceed by proposing ruthenium−butatrienylidene complexes as key intermediates. We believe that this finding will open up a further aspect of the chemistry of metal−cumulenylidene complexes.
Carmen Claver - One of the best experts on this subject based on the ideXlab platform.
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new phosphite oxazoline ligands for efficient pd catalyzed Substitution Reactions
Journal of the American Chemical Society, 2005Co-Authors: Oscar Pamies, And Montserrat Dieguez, Carmen ClaverAbstract:We have designed and synthesized a new family of readily available highly modular phosphite−oxazoline ligands for the Pd-catalyzed asymmetric allylic Substitution Reactions. The introduction of a π...
Wolfgang Weigand - One of the best experts on this subject based on the ideXlab platform.
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Substitution Reactions of fefe hydrogenase model complexes containing diselenolate bridges
Polyhedron, 2013Co-Authors: Mohammad Elkhateeb, Mohammad K Harb, Qutaiba Abusalem, Helmar Gorls, Wolfgang WeigandAbstract:Abstract Substitution Reactions of the carbonyl ligands of the hydrogenase model complexes [Fe2(μ-SeC3H5RSe-μ)(CO)6] (R = H, Me) by bis(diphenylphosphino)methane (dppm) has been investigated. These Reactions produced either the mono-substituted complexes, [Fe2(μ-SeC3H5RSe-μ)(CO)5](κ-dppm) (R = H (1), Me (2)), or the chelated disubstituted ones, [Fe2(μ-SeC3H5RSe-μ)(CO)4](μ-dppm) (R = H (3), Me (4)). The new complexes have been characterized by elemental analysis, mass spectrometry, IR, 1H, 13C{H}, 31P{H} and 77Se{H} NMR spectroscopy. The solid state structures of complexes 1–4 were determined by X-ray crystal structure analysis.
Zhuoan Zhao - One of the best experts on this subject based on the ideXlab platform.
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highly regioselective allylic Substitution Reactions catalyzed by an air stable π allyl iridium complex derived from dinaphthocyclooctatetraene and a phosphoramidite ligand
Synthesis, 2013Co-Authors: Keyin Ye, Zhuoan ZhaoAbstract:An air-stable (pi-allyl)iridium complex derived from naphthocyclooctatetraene and a phosphoramidite ligand has been synthesized and found to be highly efficient in iridium-catalyzed allylic Substitution Reactions. This catalyst features excellent regiosel
John F Hartwig - One of the best experts on this subject based on the ideXlab platform.
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origins of enantioselectivity during allylic Substitution Reactions catalyzed by metallacyclic iridium complexes
Journal of the American Chemical Society, 2012Co-Authors: Sherzod T Madrahimov, John F HartwigAbstract:In depth mechanistic studies of iridium catalyzed regioselective and enantioselective allylic Substitution Reactions are presented. A series of cyclometalated allyliridium complexes that are kinetically and chemically competent to be intermediates in the allylic Substitution Reactions was prepared and characterized by 1D and 2D NMR spectroscopies and single-crystal X-ray difraction. The rates of epimerization of the less thermodynamically stable diastereomeric allyliridium complexes to the thermodynamically more stable allyliridium stereoisomers were measured. The rates of nucleophilic attack by aniline and by N-methylaniline on the isolated allyliridium complexes were also measured. Attack on the thermodynamically less stable allyliridium complex was found to be orders of magnitude faster than attack on the thermodynamically more stable complex, yet the major enantiomer of the catalytic reaction is formed from the more stable diastereomer. Comparison of the rates of nucleophilic attack to the rates of ep...
