The Experts below are selected from a list of 87 Experts worldwide ranked by ideXlab platform
Akira Hirao - One of the best experts on this subject based on the ideXlab platform.
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Precise Synthesis of Regular and Asymmetric Star Polymers and Densely Branched Polymers with Starlike Structures by Means of Living Anionic Polymerization
Polymer Journal, 2002Co-Authors: Akira Hirao, Mayumi Hayashi, Yui Tokuda, Naoki Haraguchi, Tomoya HigashiharaAbstract:The subject of this review is to present new synthetic methodologies recently developed by us, which are applicable to both regular and asymmetric star polymers with well-defined architectures. The first methodology involves the coupling reaction of a variety of living anionic polymers of styrene, α-methylstyrene, isoprene, tert -butyl methacrylate, and ethylene oxide with novel chain-end- and in-chain-functionalized polymers with a definite number of Benzyl Halide moieties intentionally designed as polymeric coupling agents. In the second methodology, we propose a new concept based on iterative approach, with which star polymers can be successively and, in principle, unlimitedly synthesized by repeating the iterative reaction sequence. Finally, a convenient synthesis of densely branched polymers with starlike structures is presented by the quantitative coupling reaction of living anionic polymers with reactive Benzyl Halide-functionalized backbone polymers based on a grafting-onto method.
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synthesis of branched polymers by means of living anionic polymerization 10 synthesis of well defined heteroarm star branched polymers by coupling reaction of chain functionalized polystyrenes with Benzyl Halide moieties with living anionic polymers
Polymer, 2002Co-Authors: Akira Hirao, Mayumi Hayashi, Akira MatsuoAbstract:Abstract The synthesis of well-defined heteroarm star-branched polymers having poly( t BMA) arms by the coupling reactions of living anionic polymers of tert -butyl methacrylate ( t BMA) with chain-functionalized polymers with a definite number of Benzyl Halide moieties was described. The reaction of living anionic poly( t BMA) bearing potassium countercation with Benzyl bromide-functionalized polystyrenes proceeded readily and quantitatively in THF at −40 °C for 1 h and −78 °C for 5 h, respectively. Similarly heteroarm star-branched polymers of AB 2 , AB 3 , AB 4 , A 2 B 4 , and ABC 4 types with well-defined architectures were successfully synthesized. On the other hand, the same living poly( t BMA) was sluggish to react with Benzyl chloride-functionalized polystyrenes, requiring 168 h to achieve quantitative formation of AB 4 star polymer. Moreover, no reaction occurred between living poly( t BMA) bearing lithium countercation in the presence of LiCl and Benzyl chloride-functionalized polystyrene in THF at −78 °C for 168 h.
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synthesis of well defined chain end and in chain functionalized polystyrenes with a definite number of α methylstyrene d glucose phenol and Benzyl Halide functionalities by reactions of chloro or bromo methylphenyl functionalized polystyrenes with su
Macromolecular Chemistry and Physics, 2001Co-Authors: Mayumi Hayashi, Akira HiraoAbstract:Chain-end and in-chain functionalized polystyrenes with four α-methylstyrene, eight D-glucose, eight phenol, eight Benzyl chloride, four Benzyl bromide functionalities with well-defined structures were successfully synthesized by the reactions of well-defined chain-end and in-chain functionalized polystyrenes with four chloro (or bromo)methylphenyl groups and substituted 1,1-diphenylalkyllithiums. They were prepared from sec-butyllithium (sec-BuLi) and the following substituted 1,1-diphenylethylene derivatives: 1,1-bis{3-[(1,2:5,6-di-O-isopropylidene-a-D-glucofuranose-O-3-yl)methyl]phenyl)ethylene (1), 1,1-bis(3-methoxymethylphenyl)ethylene (2), 1-{4-[3-(4-isopropenyl-phenyl)propyl]phenyl]-1-phenylethylene (3), 1,1-bis(4-tert-butyldimethylsilyloxyphenyl)ethylene (4), and 1,1-bis(3-tert-butyldimethylsilyloxymethylphenyl) ethylene (5). In 20 h at -78°C all reactions proceeded cleanly and efficiently in THF to afford quantitatively the expected well-defined functionalized polystyrenes. Advantages of these reactions are described in this paper.
Nagatoshi Nishiwaki - One of the best experts on this subject based on the ideXlab platform.
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Substrate switchable Suzuki–Miyaura coupling for Benzyl ester vs. Benzyl Halide
RSC Advances, 2018Co-Authors: Masato Ohsumi, Nagatoshi NishiwakiAbstract:Two reaction conditions were developed to accomplish the substrate switchable Suzuki–Miyaura coupling of Benzyl derivatives and arylboronic acid derivatives. Under conditions for esters, Benzyl esters such as carbonates and acetates reacted with arylboronic acids to afford the corresponding diarylmethanes. However, the Benzyl Halides did not react under the same conditions. On the other hand, Benzyl Halides such as bromides and chlorides furnished diarylmethanes under conditions for Halides, under which Benzyl ester substrates did not react, in which water was found to play an important role. This switching system was tested using the intermolecular/intramolecular competitive reactions, during which the desired products could be synthesized by selecting the appropriate reaction conditions.
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substrate switchable suzuki miyaura coupling for Benzyl ester vs Benzyl Halide
RSC Advances, 2018Co-Authors: Masato Ohsumi, Nagatoshi NishiwakiAbstract:Two reaction conditions were developed to accomplish the substrate switchable Suzuki–Miyaura coupling of Benzyl derivatives and arylboronic acid derivatives. Under conditions for esters, Benzyl esters such as carbonates and acetates reacted with arylboronic acids to afford the corresponding diarylmethanes. However, the Benzyl Halides did not react under the same conditions. On the other hand, Benzyl Halides such as bromides and chlorides furnished diarylmethanes under conditions for Halides, under which Benzyl ester substrates did not react, in which water was found to play an important role. This switching system was tested using the intermolecular/intramolecular competitive reactions, during which the desired products could be synthesized by selecting the appropriate reaction conditions.
Mayumi Hayashi - One of the best experts on this subject based on the ideXlab platform.
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Precise Synthesis of Regular and Asymmetric Star Polymers and Densely Branched Polymers with Starlike Structures by Means of Living Anionic Polymerization
Polymer Journal, 2002Co-Authors: Akira Hirao, Mayumi Hayashi, Yui Tokuda, Naoki Haraguchi, Tomoya HigashiharaAbstract:The subject of this review is to present new synthetic methodologies recently developed by us, which are applicable to both regular and asymmetric star polymers with well-defined architectures. The first methodology involves the coupling reaction of a variety of living anionic polymers of styrene, α-methylstyrene, isoprene, tert -butyl methacrylate, and ethylene oxide with novel chain-end- and in-chain-functionalized polymers with a definite number of Benzyl Halide moieties intentionally designed as polymeric coupling agents. In the second methodology, we propose a new concept based on iterative approach, with which star polymers can be successively and, in principle, unlimitedly synthesized by repeating the iterative reaction sequence. Finally, a convenient synthesis of densely branched polymers with starlike structures is presented by the quantitative coupling reaction of living anionic polymers with reactive Benzyl Halide-functionalized backbone polymers based on a grafting-onto method.
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synthesis of branched polymers by means of living anionic polymerization 10 synthesis of well defined heteroarm star branched polymers by coupling reaction of chain functionalized polystyrenes with Benzyl Halide moieties with living anionic polymers
Polymer, 2002Co-Authors: Akira Hirao, Mayumi Hayashi, Akira MatsuoAbstract:Abstract The synthesis of well-defined heteroarm star-branched polymers having poly( t BMA) arms by the coupling reactions of living anionic polymers of tert -butyl methacrylate ( t BMA) with chain-functionalized polymers with a definite number of Benzyl Halide moieties was described. The reaction of living anionic poly( t BMA) bearing potassium countercation with Benzyl bromide-functionalized polystyrenes proceeded readily and quantitatively in THF at −40 °C for 1 h and −78 °C for 5 h, respectively. Similarly heteroarm star-branched polymers of AB 2 , AB 3 , AB 4 , A 2 B 4 , and ABC 4 types with well-defined architectures were successfully synthesized. On the other hand, the same living poly( t BMA) was sluggish to react with Benzyl chloride-functionalized polystyrenes, requiring 168 h to achieve quantitative formation of AB 4 star polymer. Moreover, no reaction occurred between living poly( t BMA) bearing lithium countercation in the presence of LiCl and Benzyl chloride-functionalized polystyrene in THF at −78 °C for 168 h.
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synthesis of well defined chain end and in chain functionalized polystyrenes with a definite number of α methylstyrene d glucose phenol and Benzyl Halide functionalities by reactions of chloro or bromo methylphenyl functionalized polystyrenes with su
Macromolecular Chemistry and Physics, 2001Co-Authors: Mayumi Hayashi, Akira HiraoAbstract:Chain-end and in-chain functionalized polystyrenes with four α-methylstyrene, eight D-glucose, eight phenol, eight Benzyl chloride, four Benzyl bromide functionalities with well-defined structures were successfully synthesized by the reactions of well-defined chain-end and in-chain functionalized polystyrenes with four chloro (or bromo)methylphenyl groups and substituted 1,1-diphenylalkyllithiums. They were prepared from sec-butyllithium (sec-BuLi) and the following substituted 1,1-diphenylethylene derivatives: 1,1-bis{3-[(1,2:5,6-di-O-isopropylidene-a-D-glucofuranose-O-3-yl)methyl]phenyl)ethylene (1), 1,1-bis(3-methoxymethylphenyl)ethylene (2), 1-{4-[3-(4-isopropenyl-phenyl)propyl]phenyl]-1-phenylethylene (3), 1,1-bis(4-tert-butyldimethylsilyloxyphenyl)ethylene (4), and 1,1-bis(3-tert-butyldimethylsilyloxymethylphenyl) ethylene (5). In 20 h at -78°C all reactions proceeded cleanly and efficiently in THF to afford quantitatively the expected well-defined functionalized polystyrenes. Advantages of these reactions are described in this paper.
Akira Matsuo - One of the best experts on this subject based on the ideXlab platform.
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synthesis of branched polymers by means of living anionic polymerization 10 synthesis of well defined heteroarm star branched polymers by coupling reaction of chain functionalized polystyrenes with Benzyl Halide moieties with living anionic polymers
Polymer, 2002Co-Authors: Akira Hirao, Mayumi Hayashi, Akira MatsuoAbstract:Abstract The synthesis of well-defined heteroarm star-branched polymers having poly( t BMA) arms by the coupling reactions of living anionic polymers of tert -butyl methacrylate ( t BMA) with chain-functionalized polymers with a definite number of Benzyl Halide moieties was described. The reaction of living anionic poly( t BMA) bearing potassium countercation with Benzyl bromide-functionalized polystyrenes proceeded readily and quantitatively in THF at −40 °C for 1 h and −78 °C for 5 h, respectively. Similarly heteroarm star-branched polymers of AB 2 , AB 3 , AB 4 , A 2 B 4 , and ABC 4 types with well-defined architectures were successfully synthesized. On the other hand, the same living poly( t BMA) was sluggish to react with Benzyl chloride-functionalized polystyrenes, requiring 168 h to achieve quantitative formation of AB 4 star polymer. Moreover, no reaction occurred between living poly( t BMA) bearing lithium countercation in the presence of LiCl and Benzyl chloride-functionalized polystyrene in THF at −78 °C for 168 h.
Masato Ohsumi - One of the best experts on this subject based on the ideXlab platform.
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Substrate switchable Suzuki–Miyaura coupling for Benzyl ester vs. Benzyl Halide
RSC Advances, 2018Co-Authors: Masato Ohsumi, Nagatoshi NishiwakiAbstract:Two reaction conditions were developed to accomplish the substrate switchable Suzuki–Miyaura coupling of Benzyl derivatives and arylboronic acid derivatives. Under conditions for esters, Benzyl esters such as carbonates and acetates reacted with arylboronic acids to afford the corresponding diarylmethanes. However, the Benzyl Halides did not react under the same conditions. On the other hand, Benzyl Halides such as bromides and chlorides furnished diarylmethanes under conditions for Halides, under which Benzyl ester substrates did not react, in which water was found to play an important role. This switching system was tested using the intermolecular/intramolecular competitive reactions, during which the desired products could be synthesized by selecting the appropriate reaction conditions.
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substrate switchable suzuki miyaura coupling for Benzyl ester vs Benzyl Halide
RSC Advances, 2018Co-Authors: Masato Ohsumi, Nagatoshi NishiwakiAbstract:Two reaction conditions were developed to accomplish the substrate switchable Suzuki–Miyaura coupling of Benzyl derivatives and arylboronic acid derivatives. Under conditions for esters, Benzyl esters such as carbonates and acetates reacted with arylboronic acids to afford the corresponding diarylmethanes. However, the Benzyl Halides did not react under the same conditions. On the other hand, Benzyl Halides such as bromides and chlorides furnished diarylmethanes under conditions for Halides, under which Benzyl ester substrates did not react, in which water was found to play an important role. This switching system was tested using the intermolecular/intramolecular competitive reactions, during which the desired products could be synthesized by selecting the appropriate reaction conditions.
