The Experts below are selected from a list of 1035 Experts worldwide ranked by ideXlab platform
Jun-ichi Anzai - One of the best experts on this subject based on the ideXlab platform.
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[3+3]Cycloalkyne dimers linked by an azo group: a stable cis-azo compound forms polymeric aggregates by nonplanar pi-pi interactions.
Journal of the American Chemical Society, 2003Co-Authors: Yuto Saiki, Tomonori Hoshi, Hiroki Sugiura, Keiichi Nakamura, Masahiko Yamaguchi, Jun-ichi AnzaiAbstract:We previously reported that the structure of the linker moiety controlled intramolecular and bimolecular aggregation of [3+3]cycloalkyne oligomers, which are cyclic acetylene derivatives containing helicenes. Here, novel [3+3]cycloalkyne dimers linked by the azo group are synthesized, and aggregation behaviors are studied, which turned out to be considerably different. The trans- and cis-azo compounds were synthesized by the oxidative coupling of a [3+3]cycloalkyne amine derivative, and the stereochemistry was determined by UV-vis spectroscopy. 1H NMR, CD, gel permeation chromatography analysis, and vapor pressure osmometry in chloroform revealed that the trans-isomer forms a strong and selective bimolecular aggregate. The cis-isomer forms a trimolecular aggregate at a concentration below 1 mM and a polymeric aggregate at above 1 mM. Unlike known diaryl azo compounds, these azo isomers do not interconvert when subjected to heating or irradiation. In contrast, a model compound lacking the cyclic helicene structure isomerizes readily.
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3 3 cycloalkyne dimers linked by an azo group a stable cis azo compound forms polymeric aggregates by nonplanar π π interactions
Journal of the American Chemical Society, 2003Co-Authors: Yuto Saiki, Tomonori Hoshi, Hiroki Sugiura, Keiichi Nakamura, Masahiko Yamaguchi, Jun-ichi AnzaiAbstract:We previously reported that the structure of the linker moiety controlled intramolecular and bimolecular aggregation of [3+3]cycloalkyne oligomers, which are cyclic acetylene derivatives containing helicenes. Here, novel [3+3]cycloalkyne dimers linked by the azo group are synthesized, and aggregation behaviors are studied, which turned out to be considerably different. The trans- and cis-azo compounds were synthesized by the oxidative coupling of a [3+3]cycloalkyne amine derivative, and the stereochemistry was determined by UV−vis spectroscopy. 1H NMR, CD, gel permeation chromatography analysis, and vapor pressure osmometry in chloroform revealed that the trans-isomer forms a strong and selective bimolecular aggregate. The cis-isomer forms a trimolecular aggregate at a concentration below 1 mM and a polymeric aggregate at above 1 mM. Unlike known diaryl azo compounds, these azo isomers do not interconvert when subjected to heating or irradiation. In contrast, a model compound lacking the cyclic helicene s...
Masahiko Yamaguchi - One of the best experts on this subject based on the ideXlab platform.
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equatorial preference in the c h activation of Cycloalkanes gacl3 catalyzed aromatic alkylation reaction
Journal of Organic Chemistry, 2003Co-Authors: Fumi Yonehara, Yoshiyuki Kido, Hiraku Sugimoto, Satoshi Morita, Masahiko YamaguchiAbstract:GaCl(3) catalyzes the aromatic alkylation of naphthalene or phenanthrene using Cycloalkanes. The C[bond]C formation predominantly takes place at the least hindered positions of the substrates, and equatorial isomers regarding the Cycloalkane moiety are generally obtained. The reaction of bicyclo[4.4.0]decane and naphthalene occurs at the 2-position of naphthalene and at the 2- or 3-carbons of the Cycloalkane, and the products possess a trans configuration at the junctures and an equatorial configuration at the naphthyl groups. Notably, cis-bicyclo[4.4.0]decane turns out to be much more reactive than the trans isomer, and a turnover number "TON" up to 20 based on GaCl(3) is attained. 1,2-Dimethylcyclohexane reacts similarly, and the cis isomer is more reactive than the trans isomer. MonoalkylCycloalkanes react at the secondary carbons provided that the alkyl group is smaller than tert-butyl. Adamantanes react at the tertiary 1-position. The alkylation reaction is considered to involve the C[bond]H activation of Cycloalkanes with GaCl(3) at the tertiary center followed by the migration of carbocations and electrophilic aromatic substitution yielding thermodynamically stable products. The stereochemistry of the reaction reveals that GaCl(3) activates the equatorial tertiary C[bond]H rather than the axial tertiary C[bond]H.
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[3+3]Cycloalkyne dimers linked by an azo group: a stable cis-azo compound forms polymeric aggregates by nonplanar pi-pi interactions.
Journal of the American Chemical Society, 2003Co-Authors: Yuto Saiki, Tomonori Hoshi, Hiroki Sugiura, Keiichi Nakamura, Masahiko Yamaguchi, Jun-ichi AnzaiAbstract:We previously reported that the structure of the linker moiety controlled intramolecular and bimolecular aggregation of [3+3]cycloalkyne oligomers, which are cyclic acetylene derivatives containing helicenes. Here, novel [3+3]cycloalkyne dimers linked by the azo group are synthesized, and aggregation behaviors are studied, which turned out to be considerably different. The trans- and cis-azo compounds were synthesized by the oxidative coupling of a [3+3]cycloalkyne amine derivative, and the stereochemistry was determined by UV-vis spectroscopy. 1H NMR, CD, gel permeation chromatography analysis, and vapor pressure osmometry in chloroform revealed that the trans-isomer forms a strong and selective bimolecular aggregate. The cis-isomer forms a trimolecular aggregate at a concentration below 1 mM and a polymeric aggregate at above 1 mM. Unlike known diaryl azo compounds, these azo isomers do not interconvert when subjected to heating or irradiation. In contrast, a model compound lacking the cyclic helicene structure isomerizes readily.
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3 3 cycloalkyne dimers linked by an azo group a stable cis azo compound forms polymeric aggregates by nonplanar π π interactions
Journal of the American Chemical Society, 2003Co-Authors: Yuto Saiki, Tomonori Hoshi, Hiroki Sugiura, Keiichi Nakamura, Masahiko Yamaguchi, Jun-ichi AnzaiAbstract:We previously reported that the structure of the linker moiety controlled intramolecular and bimolecular aggregation of [3+3]cycloalkyne oligomers, which are cyclic acetylene derivatives containing helicenes. Here, novel [3+3]cycloalkyne dimers linked by the azo group are synthesized, and aggregation behaviors are studied, which turned out to be considerably different. The trans- and cis-azo compounds were synthesized by the oxidative coupling of a [3+3]cycloalkyne amine derivative, and the stereochemistry was determined by UV−vis spectroscopy. 1H NMR, CD, gel permeation chromatography analysis, and vapor pressure osmometry in chloroform revealed that the trans-isomer forms a strong and selective bimolecular aggregate. The cis-isomer forms a trimolecular aggregate at a concentration below 1 mM and a polymeric aggregate at above 1 mM. Unlike known diaryl azo compounds, these azo isomers do not interconvert when subjected to heating or irradiation. In contrast, a model compound lacking the cyclic helicene s...
Yuto Saiki - One of the best experts on this subject based on the ideXlab platform.
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[3+3]Cycloalkyne dimers linked by an azo group: a stable cis-azo compound forms polymeric aggregates by nonplanar pi-pi interactions.
Journal of the American Chemical Society, 2003Co-Authors: Yuto Saiki, Tomonori Hoshi, Hiroki Sugiura, Keiichi Nakamura, Masahiko Yamaguchi, Jun-ichi AnzaiAbstract:We previously reported that the structure of the linker moiety controlled intramolecular and bimolecular aggregation of [3+3]cycloalkyne oligomers, which are cyclic acetylene derivatives containing helicenes. Here, novel [3+3]cycloalkyne dimers linked by the azo group are synthesized, and aggregation behaviors are studied, which turned out to be considerably different. The trans- and cis-azo compounds were synthesized by the oxidative coupling of a [3+3]cycloalkyne amine derivative, and the stereochemistry was determined by UV-vis spectroscopy. 1H NMR, CD, gel permeation chromatography analysis, and vapor pressure osmometry in chloroform revealed that the trans-isomer forms a strong and selective bimolecular aggregate. The cis-isomer forms a trimolecular aggregate at a concentration below 1 mM and a polymeric aggregate at above 1 mM. Unlike known diaryl azo compounds, these azo isomers do not interconvert when subjected to heating or irradiation. In contrast, a model compound lacking the cyclic helicene structure isomerizes readily.
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3 3 cycloalkyne dimers linked by an azo group a stable cis azo compound forms polymeric aggregates by nonplanar π π interactions
Journal of the American Chemical Society, 2003Co-Authors: Yuto Saiki, Tomonori Hoshi, Hiroki Sugiura, Keiichi Nakamura, Masahiko Yamaguchi, Jun-ichi AnzaiAbstract:We previously reported that the structure of the linker moiety controlled intramolecular and bimolecular aggregation of [3+3]cycloalkyne oligomers, which are cyclic acetylene derivatives containing helicenes. Here, novel [3+3]cycloalkyne dimers linked by the azo group are synthesized, and aggregation behaviors are studied, which turned out to be considerably different. The trans- and cis-azo compounds were synthesized by the oxidative coupling of a [3+3]cycloalkyne amine derivative, and the stereochemistry was determined by UV−vis spectroscopy. 1H NMR, CD, gel permeation chromatography analysis, and vapor pressure osmometry in chloroform revealed that the trans-isomer forms a strong and selective bimolecular aggregate. The cis-isomer forms a trimolecular aggregate at a concentration below 1 mM and a polymeric aggregate at above 1 mM. Unlike known diaryl azo compounds, these azo isomers do not interconvert when subjected to heating or irradiation. In contrast, a model compound lacking the cyclic helicene s...
Igor V Komarov - One of the best experts on this subject based on the ideXlab platform.
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following ramachandran 2 exit vector plot evp analysis of disubstituted saturated rings
New Journal of Chemistry, 2018Co-Authors: Oleksandr O Grygorenko, Daryna Demenko, Dmitry M Volochnyuk, Igor V KomarovAbstract:Analysis of disubstituted heteroaliphatic, as well as all common saturated rings using the exit vector plots (EVPs) tool is described, which is based on the Cambridge Structural Database (CSD) data. It is shown that the combined EVPs for saturated rings are similar to those observed for Cycloalkanes (i.e. α, β, γ, and δ regions are found). In addition to that, a new region (e) is found which is not accessible by simple Cycloalkane derivatives. It is shown that while introducing saturated rings into the molecules is widely considered as an approach to increase their non-planarity, not many of them are truly three-dimensional; some recommendations are given to address this issue.
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Following Ramachandran: exit vector plots (EVP) as a tool to navigate chemical space covered by 3D bifunctional scaffolds. The case of Cycloalkanes
RSC Advances, 2016Co-Authors: Oleksandr O Grygorenko, Dmitry M Volochnyuk, Pavlo Babenko, Oleksii Raievskyi, Igor V KomarovAbstract:An approach to the analysis and visualization of chemical space covered by disubstituted scaffolds, which is based on exit vector plots (EVPs), is used for analysis of the simplest disubstituted cyclic cores – Cycloalkanes – deposited in the Cambridge Structural Database (CSD). It is shown that four clearly defined regions are found in EVPs of the Cycloalkanes, similar to those observed in Ramachandran plots for peptides. These results can be used for directed design of more complex scaffolds, classification of conformational space for the disubstituted scaffolds, rational scaffold replacement, or SAR studies.
Keiichi Nakamura - One of the best experts on this subject based on the ideXlab platform.
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[3+3]Cycloalkyne dimers linked by an azo group: a stable cis-azo compound forms polymeric aggregates by nonplanar pi-pi interactions.
Journal of the American Chemical Society, 2003Co-Authors: Yuto Saiki, Tomonori Hoshi, Hiroki Sugiura, Keiichi Nakamura, Masahiko Yamaguchi, Jun-ichi AnzaiAbstract:We previously reported that the structure of the linker moiety controlled intramolecular and bimolecular aggregation of [3+3]cycloalkyne oligomers, which are cyclic acetylene derivatives containing helicenes. Here, novel [3+3]cycloalkyne dimers linked by the azo group are synthesized, and aggregation behaviors are studied, which turned out to be considerably different. The trans- and cis-azo compounds were synthesized by the oxidative coupling of a [3+3]cycloalkyne amine derivative, and the stereochemistry was determined by UV-vis spectroscopy. 1H NMR, CD, gel permeation chromatography analysis, and vapor pressure osmometry in chloroform revealed that the trans-isomer forms a strong and selective bimolecular aggregate. The cis-isomer forms a trimolecular aggregate at a concentration below 1 mM and a polymeric aggregate at above 1 mM. Unlike known diaryl azo compounds, these azo isomers do not interconvert when subjected to heating or irradiation. In contrast, a model compound lacking the cyclic helicene structure isomerizes readily.
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3 3 cycloalkyne dimers linked by an azo group a stable cis azo compound forms polymeric aggregates by nonplanar π π interactions
Journal of the American Chemical Society, 2003Co-Authors: Yuto Saiki, Tomonori Hoshi, Hiroki Sugiura, Keiichi Nakamura, Masahiko Yamaguchi, Jun-ichi AnzaiAbstract:We previously reported that the structure of the linker moiety controlled intramolecular and bimolecular aggregation of [3+3]cycloalkyne oligomers, which are cyclic acetylene derivatives containing helicenes. Here, novel [3+3]cycloalkyne dimers linked by the azo group are synthesized, and aggregation behaviors are studied, which turned out to be considerably different. The trans- and cis-azo compounds were synthesized by the oxidative coupling of a [3+3]cycloalkyne amine derivative, and the stereochemistry was determined by UV−vis spectroscopy. 1H NMR, CD, gel permeation chromatography analysis, and vapor pressure osmometry in chloroform revealed that the trans-isomer forms a strong and selective bimolecular aggregate. The cis-isomer forms a trimolecular aggregate at a concentration below 1 mM and a polymeric aggregate at above 1 mM. Unlike known diaryl azo compounds, these azo isomers do not interconvert when subjected to heating or irradiation. In contrast, a model compound lacking the cyclic helicene s...
