화학공학소재연구정보센터
Macromolecules, Vol.48, No.7, 2006-2012, 2015
Stereoselective Ring-Opening Metathesis Polymerization (ROMP) of Methyl-N-(1-phenylethyl)-2-azabicyclo[2.2.1]hept-5-ene-3-carboxylate by Molybdenum and Tungsten Initiators
Ring-opening metathesis polymerization (ROMP) of methyl-N-(1-phenylethyl)-2-azabicyclo[2.2.1]hept-5-ene-3-carboxylate (PhEtNNBE; (S) and racemic) was investigated employing six molybdenum and tungsten imido alkylidene initiators and two tungsten oxo alkylidene initiators. Of the six initiators that we proposed should yield cis,syndiotactic-poly[(S)-PhEtNNBE], two molybdenum OHMT alkylidene initiators, Mo(NR)(CHMe2Ph)(pyr)(OHMT) (R = 1-adamantyl (Ad) or 2,6-Me2C6H3 (Ar'); OHMT = O-2,6-mesityl(2)C(6)H(3); pyr = pyrrolide), and two tungsten oxo alkylidene initiators, W(O)(CHMe2Ph)(2,5-dimethylpyrrolide)(PMe2Ph)(OR) (OR = OHMT or (R)-OBr(2)Bitet where (R)-Br(2)BitetOH = (R)-3,3'-dibromo-2'-(tert-butyldimethylsilyloxy)-5,5',6,6',7,7',8,8'-octahydro-1,1'-binaphthyl-2-ol), produced essentially pure cis,syndiotactic-poly[(S)-PhEtNNBE]. Essentially pure cis,isotactic-poly[(S)-PhEtNNBE] was formed when (S)-PhEtNNBE was polymerized by Mo(NAr')(CHCMe2Ph)(OBiphenCF(3))(thf) or W(NAr')(CHCMe2Ph)((S)-OBiphenMe) (OBiphenCF(3) = 3,3'-di-tert-butyl-5,5'-bistrifluoromethyl-6,6'-dimethyl-1,1'-biphenyl-2,2'-diolate; (S)-OBiphenMe = 3,3'-di-tert-butyl-5,5',6,6'-tetramethyl-1,1'-biphenyl-2,2'-diolate). The best initiator for ROMP of rac-PhEtNNBE was Mo(NAd)(CHMe2Ph)(pyr)(OHMT) at 0 degrees C, which led to a polymer that is biased (similar to 80%) toward a cis,syndiotactic structure and that contains alternating enantiomers in the chain (cis,syndio,alt-poly[(rac)-PhEtNNBE]).