Showing papers by "Masahiro Murakami published in 2005"
TL;DR: This reaction achieves a formal alkyne insertion between the carbonyl carbon and the alpha-carbon, providing a six-membered carbocyclic skeleton.
Abstract: Cyclobutanones reacted with alkynes in the presence of nickel(0) catalysts to produce cyclohexenones. Oxidative cyclization of the carbonyl group of the cyclobutanone and the alkyne with the nickel(0) was followed by beta-carbon elimination from the resulting oxanickelacyclopentene and subsequent reductive elimination. This reaction achieves a formal alkyne insertion between the carbonyl carbon and the alpha-carbon, providing a six-membered carbocyclic skeleton.
156 citations
138 citations
TL;DR: A new [3 + 2] annulation reaction was developed in which 2-cyanophenylboronic acid reacted as a three-carbon component with alkynes or alkenes to afford substituted indenones or indanones.
127 citations
TL;DR: New cyclization reactions forming cyclic ketones were developed wherein an intermediate organorhodium(I) species underwent intramolecular acylation with an ester group to promote the next catalytic cycle.
Abstract: New cyclization reactions forming cyclic ketones were developed wherein an intermediate organorhodium(I) species underwent intramolecular acylation with an ester group. A 2-norbornanone skeleton is constructed in a single operation through successive multiple carbon−carbon bond formation. The reactions ended up with generation of an alkoxyrhodium(I) species to promote the next catalytic cycle.
111 citations
TL;DR: Intramolecular carborhodation onto the pendent alkene in a 5-exo mode furnished a five-membered ring and the rhodium(I) methoxide generated by beta-methoxy elimination reacted with the arylboronic acid to promote the next catalytic cycle.
Abstract: 1,6-Enynes reacted with arylboronic acids in the presence of a catalytic amount of a rhodium(I) complex under mild conditions to give (Z)-1-(1-arylethylidene)-2-vinylcyclopentanes. The regioselective addition of an arylrhodium(I) species across the carbon−carbon triple bond triggered the cyclization process. Intramolecular carborhodation onto the pendent alkene in a 5-exo mode furnished a five-membered ring. Finally, the rhodium(I) methoxide generated by β-methoxy elimination reacted with the arylboronic acid to promote the next catalytic cycle.
98 citations
82 citations
TL;DR: A rhodium-catalyzed annulation reaction of o-formylphenylboronic acid with alkynes occurred regioselectively at room temperature to give substituted 1H-inden-1-ol derivatives as mentioned in this paper.
Abstract: A rhodium-catalyzed annulation reaction of o-formylphenylboronic acid with alkynes occurred regioselectively at room temperature to give substituted 1H-inden-1-ol derivatives. o-Acetylphenylboronic...
53 citations
TL;DR: Nucleophilic addition of an organorhodium(I) to a cyano group has been observed for the first time in the rhodium-catalysed reaction of cyano-substituted alkynes with arylboronic acids.
53 citations
51 citations
TL;DR: Asymmetric decarboxylative rearrangement of allyl α-acetamido-β-ketocar boxylates was catalysed by a palladium complex modified with a chiral phosphine ligand, giving optically active γ,δ-unsaturated α-aminoketones with up to 90% ee.
45 citations
TL;DR: Cyclobutene, having a pinacolatoboryl group at the 3-position, was prepared by the reaction of trimethyl borate with a cyclobutenyl anion, which was generated by reductive lithiation of 3-(phenylselenyl)cyclobutenes.
Abstract: Cyclobutene, having a pinacolatoboryl group at the 3-position, was prepared by the reaction of trimethyl borate with a cyclobutenyl anion, which was generated by reductive lithiation of 3-(phenylselenyl)cyclobutene. Its thermal ring-opening reaction provided (Z)-1-borylbuta-1,3-diene selectively despite the arising steric congestion. The contrasteric behavior was accounted for by assuming an electron-accepting interaction of the vacant boron p orbital with the distorted breaking σ orbital in the inward transition state.
TL;DR: A ring-closing metathesis reaction of allenynes occurred at room temperature in the presence of a molybdenum alkylidene complex to give ring-closed vinylallenes.
TL;DR: An addition/ring-opening reaction of aryl- and alkenylboronic acids to cyclobutanones took place in 1,4-dioxane at 100 °C in the presence of a rhodium(I) catalyst bearing tri-t-butylphosphine.
Abstract: An addition/ring-opening reaction of aryl- and alkenylboronic acids to cyclobutanones took place in 1,4-dioxane at 100 °C in the presence of a rhodium(I) catalyst bearing tri-t-butylphosphine, affo...
TL;DR: Cyano(dialkylamino)boryl ethers of homopropargylic alcohols undergo intramolecular addition of a B-CN bond across their carbon-carbon triple bonds (cyanoboration) in the presence of palladium and nickel catalysts as discussed by the authors.
TL;DR: In this article, five-membered cyclic silylboranes were synthesized via intramolecular reductive B-Si bond formation with 3-[chloro(diisopropylamino)bo...
Abstract: Five-membered cyclic silylboranes, 2-(diisopropylamino)-1,1-diorgano-1-sila-2-boracyclopentanes, were synthesized via intramolecular reductive B–Si bond formation with 3-[chloro(diisopropylamino)bo...
TL;DR: In this article, diarylindium(III) hydroxides react with α,β-unsaturated carbonyl compounds in the presence of a rhodium catalyst to afford the 1,4-addition products in high yield.
TL;DR: Two structurally distinct carbocycles were selectively obtained by the reactions of 2-(o-styryl)cyclobutanones promoted by ytterbium salts.
TL;DR: In this article, an NMR analysis together with an X-ray diffraction study supports the conjecture that the helical secondary structure is a common feature of the assemblies in which naphthalene-like aromatic units are linked together between the β-positions in series.
Abstract: Oligo(naphthalene-2,3-diyl)s are synthesized by the palladium-catalyzed cross-coupling reactions of 2-naphthyl-zinc compounds with 2-bromonaphthalene derivatives. An NMR analysis together with an X-ray diffraction study supports the conjecture that the helical secondary structure is a common feature of the assemblies in which naphthalene-like aromatic units are linked together between the β-positions in series.
TL;DR: In this article, a diolefin ligand was used to afford 2-alkylidenecyclopentanols through the regioselective addition of an arylrhodium(I) species across the carbon-carbon triple bond, followed by intramolecular nucleophilic addition of the resulting vinyl-rhodium-I species to the carbonyl group.
Abstract: 5-Yn-1-ones react with arylboronic acids in the presence of a catalytic amount of rhodium(I) complex having a diolefin ligand to afford 2-alkylidenecyclopentanols through the regioselective addition of an arylrhodium(I) species across the carbon-carbon triple bond, followed by intramolecular nucleophilic addition of the resulting vinylrhodium(I) species to the carbonyl group.
TL;DR: In this article, cyclobutanones reacted with alkynes in the presence of nickel(0) catalysts to produce cyclohexenones, which achieved a formal alkyne insertion between the carbonyl carbon and the alpha-carbon, providing a six-membered carbocyclic skeleton.
Abstract: Cyclobutanones reacted with alkynes in the presence of nickel(0) catalysts to produce cyclohexenones. Oxidative cyclization of the carbonyl group of the cyclobutanone and the alkyne with the nickel(0) was followed by beta-carbon elimination from the resulting oxanickelacyclopentene and subsequent reductive elimination. This reaction achieves a formal alkyne insertion between the carbonyl carbon and the alpha-carbon, providing a six-membered carbocyclic skeleton.
TL;DR: In this paper, the authors developed hyperspectral remote sensing algorithms for chlorophyll and accessory pigments retrieval in the Ishizuchi Reservoir in Japan, where the laboratory reflectance data of 207 field samples with manipulated pigment and suspended sediment concentrations were measured between 400 and 700 nm with a hypersensorral spectroradiometer, and integrated into 60 contiguous narrow bands.
Abstract: Remote sensing technology is being conceived as a cost-effective tool to monitor the eutrophication problem in shallow inland lakes and reservoirs. The objective of this study is to develop hyperspectral remote sensing algorithms for chlorophyll and accessory pigments retrieval in the Ishizuchi Reservoir in Japan. The laboratory reflectance data of 207 field samples with manipulated pigment and suspended sediment concentrations were measured between 400 and 700 nm with a hyperspectral spectroradiometer, and integrated into 60 contiguous narrow bands. Band ratio and spectral absorption algorithms were developed by regression analysis with the observed chlorophyll measurements, and their estimation accuracies were evaluated using the RMSE of the estimates. Algorithms developed from spectral absorption ratios a(675 nm)/a*(675 nm) for five different classes of total pigment concentrations were more accurate than the algorithms based on band ratios Rrs (538 nm)/Rrs (488 nm), Rrs (581 nm)/Rrs (463 nm) ...
TL;DR: In this article, the nucleophilic addition of an organorhodium(I) to a cyano group has been observed for the first time in the rhodium-catalysed reaction of cyano-substituted alkynes with arylboronic acids.
Abstract: Nucleophilic addition of an organorhodium(I) to a cyano group has been observed for the first time in the rhodium-catalysed reaction of cyano-substituted alkynes with arylboronic acids. The higher reactivity of a cyano group relative to an alkoxycarbonyl group toward an organorhodium(I) species is demonstrated by an intramolecular example.
TL;DR: Aminoboranes have been shown to be highly efficient and mild iminium ion generators in the Mannich-type aminative coupling of aldehydes with silyl ketene acetals.
Abstract: Aminoboranes have been shown to be highly efficient and mild iminium ion generators in the Mannich-type aminative coupling of aldehydes with silyl ketene acetals. By using aminoboranes bearing bulky amino groups, such as a diisopropylamino group, free secondary amines can be successfully used as the amino component in a three-component Mannich reaction with aldehydes and silyl ketene acetals.
TL;DR: In this article, a cyclic skeleton was constructed by intramolecular nucleophilic addition of an intermediate organorhodium(I) species to a cyano group.
Abstract: [reaction: see text]. A new [3 + 2] annulation reaction was developed in which 2-cyanophenylboronic acid reacted as a three-carbon component with alkynes or alkenes to afford substituted indenones or indanones. The use of an alkynoate even produced benzotropone, a formal [3 + 2 + 2] adduct. The cyclic skeletons were constructed by intramolecular nucleophilic addition of an intermediate organorhodium(I) species to a cyano group.
TL;DR: In this paper, five-membered cyclic silylboranes were synthesized via intramolecular reductive B-Si bond formation with 3-[chloro(diisopropylamino)bo...
Abstract: Five-membered cyclic silylboranes, 2-(diisopropylamino)-1,1-diorgano-1-sila-2-boracyclopentanes, were synthesized via intramolecular reductive B–Si bond formation with 3-[chloro(diisopropylamino)bo...
TL;DR: An addition/ring-opening reaction of aryl-and alkenylboronic acids to cyclobutanones in 1,4-dioxane at 100 °C in the presence of a rhodium(I) catalyst bearing tri-t-butylphosphine, affo...
Abstract: An addition/ring-opening reaction of aryl- and alkenylboronic acids to cyclobutanones took place in 1,4-dioxane at 100 °C in the presence of a rhodium(I) catalyst bearing tri-t-butylphosphine, affo...
TL;DR: In this paper, a ring-closing metathesis reaction of allenynes occurred at room temperature in the presence of a molybdenum alkylidene complex to give ring-closed vinylallenes.
Abstract: A ring-closing metathesis reaction of allenynes occurred at room temperature in the presence of a molybdenum alkylidene complex to give ring-closed vinylallenes. The vinylallene skeletons were constructed by a metathesis-type reaction between the alkyne moiety and the proximal carbon-carbon double bond of the allene moiety. [reaction: see text]
TL;DR: In this article, two structurally distinct carbocycles were selectively obtained by the reactions of 2-(o-styryl)cyclobutanones promoted by ytterbium salts.
Abstract: Two structurally distinct carbocycles were selectively obtained by the reactions of 2-(o-styryl)cyclobutanones promoted by ytterbium salts. Treatment of the cyclobutanones with YbCl3 in 1,4-dioxane at 100 °C afforded 2-(2-chloroethyl)naphthalenes. On the other hand, the reaction with Yb(OTf)3 in chlorobenzene at 130 °C gave 9,10-dihydrobenzocycloocten-7(8H)-ones.