Stereospecific Ring-Opening Metathesis Polymerization of Norbornadienes Employing Tungsten Oxo Alkylidene Initiators

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• 作者：William P. Forrest ; Jonathan G. Weis ; Jeremy M. John ; Jonathan C. Axtell ; Jeffrey H. Simpson ; Timothy M. Swager ; Richard R. Schrock
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：August 6, 2014
• 年：2014
• 卷：136
• 期：31
• 页码：10910-10913
• 全文大小：260K
• ISSN：1520-5126

文摘

We report here the polymerization of several 7-isopropylidene-2,3-disubstituted norbornadienes, 7-oxa-2,3-dicarboalkoxynorbornadienes, and 11-oxa-benzonorbornadienes with a single tungsten oxo alkylidene catalyst, W(O)(CH-t-Bu)(OHMT)(Me₂Pyr) (OHMT = 2,6-dimesitylphenoxide; Me₂Pyr = 2,5-dimethylpyrrolide) to give cis, stereoregular polymers. The tacticities of the menthyl ester derivatives of two polymers were determined for two types. For poly(7-isopropylidene-2,3-dicarbomenthoxynorbornadiene) the structure was shown to be cis,isotactic, while for poly(7-oxa-2,3-dicarbomenthoxynorbornadiene) the structure was shown to be cis,syndiotactic. A bis-trifluoromethyl-7-isopropylidene norbornadiene was not polymerized stereoregularly with W(O)(CHCMe₂Ph)(Me₂Pyr)(OHMT) alone, but a cis, stereoregular polymer was formed in the presence of 1 equiv of B(C₆F₅)₃.