On the Stereoselectivity of Ring-Opening Metathesis Polymerization (ROMP) of N-Arylpyrrolidine-Fused Cyclobutenes with Molybdenum鈥?and Ruthenium鈥揂lkylidene Catalyst

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• 作者：Nai-Ti Lin ; Yuan-Zhen Ke ; Kamani Satyanarayana ; Shou-Ling Huang ; Yi-Kang Lan ; Hsiao-Ching Yang ; Tien-Yau Luh
• 刊名：Macromolecules
• 出版年：2013
• 出版时间：September 24, 2013
• 年：2013
• 卷：46
• 期：18
• 页码：7173-7179
• 全文大小：373K
• 年卷期：v.46,no.18(September 24, 2013)
• ISSN：1520-5835

文摘

Ring-opening metathesis polymerization (ROMP) of cyclobutenes fused with N-arylpyrrolidene with Schrock鈥揌oveyda catalyst containing a racemic biphenolate ligand [Mo(N-2,6-i-Pr₂C₆H₃)(CHCMe₂Ph)(biphenolate)] gives polycyclobutenes with homogeneous tacticity and predominantly double bonds in Z-configuration. Reactions of the same substrates with the first-generation Grubbs catalyst [(Cy₃P)₂Cl₂Ru鈺怌HPh] or Schrock molybdenum carbene with monodendate alkoxy ligands [Mo(N-2,6-i-Pr₂C₆H₃)(CHCMe₂Ph)(OCMe(CF₃)₂] yield the corresponding polycyclobutene containing a mixture of Z- and E-double bonds. Upon diimide reduction, all these polycyclobutenes give the same tactic hydrogenated polymers, indicating that the stereochemistry at the asymmetric carbons remains the same in all these reactions. The stereoselectivities of ROMP with cyclobutenes and with norbornenes are compared, and the plausible mechanisms are proposed.