A Reactive Helix: Synthesis, Chemical Modification, and Polymerization of an Optically Active Polymethacrylate

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• 作者：Takeshi Sakamoto ; Toshio Nishikawa ; Yasuyuki Fukuda ; Shin-ichiro Sato ; Tamaki Nakano
• 刊名：Macromolecules
• 出版年：2010
• 出版时间：July 27, 2010
• 年：2010
• 卷：43
• 期：14
• 页码：5956-5963
• 全文大小：935K
• 年卷期：v.43,no.14(July 27, 2010)
• ISSN：1520-5835

文摘

1-(p-Vinylphenyl)dibenzosuberyl methacrylate (VDBSMA) having two reactive vinyl groups in a molecule was synthesized and polymerized using α,α′-azobis(isobutyronitrile) as a radical initiator and using the complexes of 9-fluorenyllithium with (S)-(+)-1-(2-pyrrolidinylmethyl)pyrrolidine, (−)-sparteine, and (S,S)-(+)-2,3-dimethoxy-1,4-bis(dimethylamino)butane as optically active anionic initiators. The free radical polymerization led to an insoluble material, indicating that both methacrylic and styrenic moieties participated in the polymerization and a cross-linked gel was produced. In contrast, the anionic polymerization proceeded exclusively through the addition reaction of methacrylic moiety leaving the styrenic vinyl group intact leading to soluble polymers. The resulting poly(VDBSMA)s having a polymethacrylate-type main-chain structure were highly isotactic and showed high optical activity and intense circular dichroism (CD) spectra, indicating that the polymers have a single-handed helical conformation. Thus, a single-handed helical polymer having side-chain vinyl groups, which can be chemically modified, was successfully synthesized. The side-chain vinyl group was converted to 2-hydroxyethyl group, 1,2-dihydroxyethyl group, and carboxylic acid group by polymer reaction without seriously deteriorating the single-handed helical conformation of the polymer. In this way, single-handed helical polymers with side-chain protonic groups which would be difficult to be prepared by direct asymmetric anionic polymerization of the corresponding monomers were conveniently synthesized. In addition, radical polymerization of poly(VDBSMA) as a macromonomer afforded an optically active adduct consisting of single-handed helical chains.