| 高分子 Vol.63 No.3 |
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特集 触媒が先導する高分子科学
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| 展望 COVER STORY: Highlight Reviews |
| らせん高分子の次世代キラル触媒としての利用 Next-Genetation Chiral Catalysts on Basis of Helical Polymers |
杉野目 道紀 Michinori SUGINOME |
| ＜要旨＞ 低分子キラル触媒よりも高い不斉収率を与え、回収・再利用が容易で、しかも不斉反応場のキラリティーを完全に反転させることで両エナンチオマーを高い光学純度で作り分けることのできる新しいキラル高分子触媒の開発が進みつつある。キラルらせん高分子ポリ（キノキサリン-2,3-ジイル）をベースとするキラル高分子配位子PQXphosについて紹介する。 Keywords: Helical Polymer / Catalytic Asymmetric Synthesis / Transition-Metal-Catalyzed Reactions / Helix Inversion / Invresion of Catalyst Chirality / Palladium Catalyst / Hydrosilylation / Suzuki-Miyaura Cross-Coupling |
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| 高分子保護剤を用いるナノ金属粒子触媒 Metal Nanoparticles Stabilized by Functionalized Hyperbranched Polymers for Catalysis |
永島 英夫 Hideo NAGASHIMA |
| ＜要旨＞ ナノ金属粒子触媒は、ナノサイズの金属粒子の特異的な活性から次世代触媒として期待されている。錯体触媒に匹敵する機能をもつには、配位子に相当する高分子保護剤の開発が有用である。ハイパーブランチポリスチレン誘導体を用いた、ナノ金属粒子触媒の開発と、二相系触媒、自己触媒メッキへの応用研究を例に、高分子保護剤への期待を紹介する。 Keywords: Metal Nanoparticles / Polymer Support / Hyperbranched Polymers / Ammonium Salts / Biphasic Catalysis / Electroless Plating |
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| 希土類触媒による精密共重合の新展開 Recent Developments in Rare Earth-Catalyzed Precision Copolymerization |
西浦 正芳・侯 召民 Masayoshi NISHIURA, Zhaomin HOU |
| ＜要旨＞ 希土類元素は独特の電子状態やイオン半径を有しており、従来の遷移金属錯体とは異なる特異な反応性を示す有機希土類錯体が数多く報告されている。本稿では、近年急速に発展しているカチオン性の希土類アルキル重合触媒の開発とそれを用いたさまざまなオレフィン類の精密共重合について、最近の研究例を中心に概説する。 Keywords: Rare Earth / Polymerization / Styrene / Isoprene / Copolymerization / Lanthanide / Hexadiene / Chain Shuttling Copolymerization |
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| トピックス COVER STORY: Topics and Products |
| 高分子組込み型不斉触媒 Polymer-Immobilized Asymmetric Catalyst |
伊津野 真一 Shinichi ITSUNO |
| ＜要旨＞Quaternary ammonium salts of cinchona alkaloid show excellent catalytic activity in various asymmetric organic reactions. In order to immobilize these chiral catalysts in the main-chain of polymers, cinchona alkaloid dimers were polymerized with achiral comonomers. The cinchona alkaloid dimers were prepared by using the quinuclidine nitrogen atom (quaternization), the OH group (ether formation), and the vinyl group (thiol-ene reaction). These dimers were readily polymeried by the following methods. (1) Quaternization polymerization: the cinchona alkaloid dimer prepared through ether linkage was allowed to react with dihalide to result in the chiral polymer containing cinchona alkaloid ammonium salt. (2) Etherification polymerization: the quaternized dimer was allowed to react with dihalide under basic condition to yield the chiral polymer. (3) Ino-exchange polymerization: the polymerization reaction between the quaternized dimer and disodium disulfonate occurred to produce the chiral polymers. This polymerization was applied to the synthesis of another chiral polymeric catalyst containing MacMillan catalyst in the main-chain. These chiral polymers were successfully used as catalysts in asymmetric reactions including alkylation and Diels-Alder reactions. Keywords: Cinchona Alkaloid / Polymer-Immobilized Catalyst / Chiral Polymer / Asymmetric Catalyst / Quaternization Polymerization / Etherification Polymerization / Ion-Exchange Polymerization |
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| 人工金属酵素 Artificial Metalloenzymes |
上野 隆史 Takafumi UENO |
| ＜要旨＞ Design of artificial metalloenzymes has become an important topic in the fields of biopolymers, biological chemistry, and inorganic chemistry due to the potential applications of artificial metalloenzymes in nanoscience and biotechnology. One of the general methods used to produce artificial metalloenzymes involves non-natural metal cofactors within protein scaffolds. This method has been used in the construction of small artificial metalloproteins with high activity and selectivity. In recent years, the above-mentioned general strategy has been applied to functionalize protein assemblies. The development of artificial metalloenzymes with hierarchically-assembled proteins would enable us to provide powerful tools for industrial and biological applications. In this review, we discuss the most significant recent research in this field as well as future directions. Keywords: Artificial Metalloenzyme / Protein / Ferritin / Virus / Protein Crystal / Organometallic / Supramolecular Protein / Catalysis |
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| シクロデキストリンを触媒とする高分子合成 Preparation of Polymers by Using Cyclodextrins as Catalysts |
原田 明・高島 義徳 Akira HARADA, Yoshinori TAKASHIMA |
| ＜要旨＞ Cyclodextrins（CDs）were found to initiate ring-opening polymerization of lactones selectively to produce polyesters in high yields, although lactones did not give any polymers under the same conditions without CDs. The lactones were activated in CD rings by inclusion. The products were found to be a polymer chain attached to the C2 hydroxyl group of a single glucopyranose unit of CD via an ester bond. The other free CDs include a growing polymer chain to support the polymerization. CD dimers were found to be much better catalysts for the polymerization of lactones, because one of the CD ring functions as a clamp as shown in DNA polymerases in the biological systems. This procedure provides a new environmentally benign approach to produce polyesters without using organic solvents and/or metal catalysts. The process might be used for the production of many kinds of polymers. Keywords: Cyclodextrin / Polymerization / Lactone Molecular Clamp / Cyclodextrin Dimer |
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| Z 選択的オレフィンメタセシス触媒とその応用 Z -Selective Olefin Metathesis Catalysts and Their Applications |
遠藤 浩司・Robert H. Grubbs Koji ENDO, Robert H. Grubbs |
| ＜要旨＞Olefin metathesis is a convenient and powerful method for the construction of carbon–carbon double bonds. This useful methodology has developed at a fast pace due to the discovery of well-defined transition metal catalysts in the 1980s. Now various highly efficient catalysts are available and widely used in both academic laboratories and industrial processes. However, stereo-control of the product olefin has been an earnest wish of the chemists working on this field. Because of the thermodynamic nature of metathesis, most catalysts produce a higher proportion of the thermodynamically favored E olefin isomer. This fundamental aspect of olefin metathesis has limited its applications in some areas of chemistry. Herein we report a new class of ruthenium-based metathesis catalysts in which an N-heterocyclic carbene ligand is chelated to the metal center. These catalysts show remarkable selectivity for the formation of Z olefins during a wide variety of metathesis reactions. In addition, applications of these catalysts to organic synthesis and polymer synthesis are also presented. Keywords: Olefin Metathesis / Catalyst / Z -selective / Organic Synthesis / Polymer Synthesis |
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| グローイングポリマー Polymer Science and I: A Personal Account |
| メリチンを選んだ理由 Reason for Melittin |
星野 友 Yu HOSHINO |
| ＜要旨＞ The reason I chose Melittin as a model target peptide for plastic antibodies was not only a scientific one. I was looking for the most inexpensive target that would be captured by polymer nanoparticles via strong “non-specific” interactions. |
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| 高分子科学最近の進歩 Front-Line Polymer Science |
| ゲル化剤に関する最近の動向 Recent Trends of Gelators |
英 謙二 Kenji HANABUSA |
＜要旨＞ Recent trends in studies on gelators are described. Gelators are low molecular weight compounds that can form physical gels in liquids. The formed gels show thermally reversible sol-to-gel phase transition. Driving forces of gelation are co-operating noncovalent interactions; for example hydrogen bonding, van der Waals interaction, π-π interaction, and electrostatic interaction. The hydrogelators containing Olsalazine and Taxol are reported as drug delivery agents. Hydrogelators consisting of D-amino acids are stable in vivo and show sustained release behavior. Hydrogelators as cell culture scaffold materials are mentioned. The cast films derived from gels are useful for sensing applications. Gelators that can detect TNT, TATP, and amines are introduced. Gelators that can form thixotropic gels are synthesized. Gelators prepared from oligothiophene and crown ether segments form thixotropic gels in the presence of bis-ammonium salts. Cyclic(dipeptide) derivatives are reported as hydrogelator forming thixotropic gels. New triggers that induce physical gelation are mentioned. |
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