Chiral (–)‐DIOP Ruthenium Complexes for Asymmetric Radical Addition and Living Radical Polymerization Reactions

Iizuka, Yasuhiro; Li, Zhaoming; Satoh, Kotaro; Kamigaito, Masami; Okamoto, Yoshio; Ito, Junichi; Nishiyama, Hisao

doi:10.1002/ejoc.200600862

Cited by 45 publications

(27 citation statements)

References 84 publications

(34 reference statements)

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“…More recently, a series of the ruthenium catalysts (Ru-1-3) with the same ligand were employed for the metal-catalyzed radical addition as well as the polymerization of various vinyl compounds, such as styrene, MMA, and MA. 104 Almost all of the radical additions between CCl 3 Br and the vinyl compounds resulted in an adduct with an enantiomeric excess up to 32%, while almost no effects on the tacticity of the polymer main chain were observed. These results also showed that the oxidized metal species diffused away from the growing radical species and could not control the stereochemistry during its addition to the monomer.…”

Section: Living Radical Polymerizationmentioning

confidence: 97%

Stereospecific Living Radical Polymerization: Dual Control of Chain Length and Tacticity for Precision Polymer Synthesis

2009

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Section: Living Radical Polymerizationmentioning

confidence: 97%

Stereospecific Living Radical Polymerization: Dual Control of Chain Length and Tacticity for Precision Polymer Synthesis

2009

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“…This result demonstrates that the chirality of the ligand has little influence on the tacticity of the polymer. This indicates that the chiral centers of the metal complex might also be far from the propagating chain radical as previously observed 14 . conditions.…”

Section: Stereocontrolled Atrp Of Nipam and Other Acrylamide Derived supporting

confidence: 79%

“…As a result, they are good initiators for this kind of monomers. For example, ATRP of styrene was successfully achieved in the presence of benzylic chloride and lithium molybdate complex 14 . α-Haloesters and α-haloketones are also widely used initiator in ATRP system.…”

Section: Initiatorsmentioning

confidence: 99%

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New Catalysts for Stereoselective Living Radical Polymerization of Functional α-Olefins

Nian

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New Catalysts for Stereoselective Living Radical Polymerization of Functional α-OlefinThe stereostructure of polymeric chains can greatly influence their physical and chemical properties. Therefore, controlling the stereostructures (tacticity) of polymers is very important in materials chemistry. There have been numerous studies on how to control the tacticity of polymer during a radical polymerization process. However, only a few monomers can be applied to stereospecific living radical polymerization.A Lewis acid-mediated stereocontrolled atom transfer radical polymerization (ATRP) of various acrylamide monomers was successfully achieved by using the newly had an isotacticity as high as 89% and a PDI of 1.12. It is the first time that the coppermediated stereocontrolled ATRP of N-isopropylacrylamide was successfully achieved.ii Acknowledgement I would like to give my deepest appreciation to my graduate advisor, Prof. Lin Pu, for his continuous guidance and help during my studies.

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“…We thus synthesized a series of chiral ruthenium complexes with the (À)-DIOP ligand and employed them as catalysts for the Kharasch addition between CCl 3 Br and the common vinyl monomers, such as St, MMA and MA, and living radical polymerizations of these monomers (Figure 14). 110 Although Ru 2 Cl 4 [(À)-DIOP] 3 and Ru(Ind)Cl(À)-DIOP induced asymmetry in the chiral addition reactions with a high chemical yield and relatively high optical yield (10-32% ee) between CCl 3 Br and the vinyl monomers, no tacticity control was achieved in the polymerizations. This is probably due to the fact that the ruthenium catalyst diffuses away from the growing radical species after the abstraction of the halogen and cannot control the stereochemistry of the addition reaction between the radical species and monomer, although the stereochemistry of the capping reaction with the abstracted halogen on the ruthenium(III) species can be controlled.…”

Section: Stereospecific Living Radical Polymerizationmentioning

confidence: 99%

Recent developments in metal-catalyzed living radical polymerization

Kamigaito

2010

Polym J

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This review presents a short overview of recent developments in metal-catalyzed living radical polymerization, mainly focusing on our recent research studies related to the subject. Metal-catalyzed living radical polymerization or atom transfer radical polymerization, which was originally developed via evolution of the metal-catalyzed Kharasch or atom transfer radical addition to chain-growth polymerization via reversible activation, has now been widely developed in many aspects. The effective metal catalysts include various transition metals, such as ruthenium, copper, iron and nickel, and highly active and versatile catalytic systems have been developed by designing ligands, applying lower oxidation metal species and using additives to widen the scope of controllable monomers and to minimize the amount of metal catalysts and the residual metals in the products. The development of the initiating systems has enabled the synthesis of a wide variety of novel, well-defined polymers, including end-functionalized, block, graft and star polymers, but also more complicated polymers possessing multiple controlled structures. Furthermore, metal-catalyzed living radical polymerization has been judiciously combined with stereospecific radical polymerization based on the use of polar solvents or Lewis acid additives, resulting in the dual control of the molecular weight and the tacticity of the resulting polymers and enabling the preparation of stereoblock and stereogradient polymers. Keywords: block polymer; living radical polymerization; precision polymer synthesis; transition metal catalyst; star polymer; stereospecific polymerization INTRODUCTIONSince the discovery of metal-catalyzed living radical polymerization or atom transfer radical polymerization (ATRP), there have been many developments in this research area, including active and versatile metal catalytic systems; the scope of controllable monomers; well-defined polymers with various controlled architectures; hybridization of the controlled polymers with inorganic, metal and biomolecular compounds; and attempts or real applications to a variety of industrial materials. 1-17 Besides these metal catalytic systems, there have also been substantial developments in various living radical polymerizations, such as nitroxide-mediated polymerizations, reversible addition fragmentation chain-transfer polymerizations and others, and in all of these, there are characteristic features of the mechanisms and components. [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] The metal-catalyzed living radical polymerization was originally discovered via evolution of the metal-catalyzed Kharasch or atom transfer radical addition reaction 35 to the chain-growth polymerization of vinyl monomers (Figure 1). 1 The initiating system generally consists of a transition metal complex in a lower oxidation state and an organic halide, in which the carbon-halogen bond of the halogen compound is activated by the metal catalyst to generate the carbon radical species upon a one-e...

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Chiral (–)‐DIOP Ruthenium Complexes for Asymmetric Radical Addition and Living Radical Polymerization Reactions

Cited by 45 publications

References 84 publications

Stereospecific Living Radical Polymerization: Dual Control of Chain Length and Tacticity for Precision Polymer Synthesis

Stereospecific Living Radical Polymerization: Dual Control of Chain Length and Tacticity for Precision Polymer Synthesis

New Catalysts for Stereoselective Living Radical Polymerization of Functional α-Olefins

Recent developments in metal-catalyzed living radical polymerization

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