Synthesis and helicity of optically active poly(N‐propargylphosphonamidates) having chiral phosphorus center |
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| Authors: | Dongmei Yue Toru Fujii Kayo Terada Junichi Tabei Masashi Shiotsuki Fumio Sanda Toshio Masuda |
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| Institution: | 1. Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura Campus, Kyoto 615‐8510, Japan;2. Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura Campus, Kyoto 615‐8510, JapanDepartment of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura Campus, Kyoto 615‐8510, Japan |
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| Abstract: | Novel chiral N‐propargylphosphonamidate monomers (HC?CCH2NHP(?O)R? O? menthyl, 1 : R = CH3, 2 : R = C2H5, 3 : R = n‐C3H7, 4 : R = Ph) were synthesized by the reaction of the corresponding phosphonic dichlorides with menthol and propargylamine. Pairs of diastereomeric monomers 1 – 4 with different ratios were obtained due to the chiral P‐center and menthyl group. One diastereomer could be separated from another one in the cases of monomers 1 and 2 . Polymerization of 1 – 4 with (nbd)Rh+η6‐C6H5B?(C6H5)3] as a catalyst in CHCl3 gave the polymers with number‐average molecular weights ranging from 5000 to 12,000 in 65–85%. Poly( 1 )–poly( 4 ) exhibited quantitative cis contents, and much larger specific rotations than 1 – 4 did in CHCl3. The polymers showed an intense Cotton effect around 325 nm based on the conjugated polyacetylene backbone. It was indicated that the polymers took a helical structure with predominantly one‐handed screw sense, and intramolecular hydrogen bonding between P?O and N? H of the polymers contributed to the stability of the helical structure. Poly( 1a ) and poly( 2a ) decreased the CD intensity upon raising CH3OH content in CHCl3/CH3OH. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1515–1524, 2007 |
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| Keywords: | chiral helical conformation polyacetylenes N‐propargylphosphonamidate synthesis |
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