POLYMERIZATION OF ENANTIOMERICALLY PURE 2,3-DICARBOALKOXYNORBORNADIENES AND 5,6-DISUBSTITUTED NORBORNENES BY WELL-CHARACTERIZED MOLYBDENUM RING-OPENING METATHESIS POLYMERIZATION INITIATORS - DIRECT DETERMINATION OF TACTICITY IN CIS, HIGHLY TACTIC AND TRANS, HIGHLY TACTIC POLYMERS
POLYMERIZATION OF ENANTIOMERICALLY PURE 2,3-DICARBOALKOXYNORBORNADIENES AND 5,6-DISUBSTITUTED NORBORNENES BY WELL-CHARACTERIZED MOLYBDENUM RING-OPENING METATHESIS POLYMERIZATION INITIATORS - DIRECT DETERMINATION OF TACTICITY IN CIS, HIGHLY TACTIC AND TRANS, HIGHLY TACTIC POLYMERS
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DOI：
10.1021/ja00087a028
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发表时间：
1994-04-20
影响因子：
15
通讯作者：
SCHROCK, RR
中科院分区：
文献类型：
--
作者：
ODELL, R;MCCONVILLE, DH;SCHROCK, RR
对映体纯的二烷氧基降冰片二烯（2，3-（CO（2）R*）（2）-降冰片二烯，其中R* =（1 R，2S，5 R）-（-）-薄荷基（2a）或（R）-（-）-泛内酯基（2b））与Mo（CHCMe（2）Ph）（NAr）（O-t-BU）（2）（1a）（Ar = 2，6-i-Pr 2C 6 H3）的开环易位聚合（ROMP）产生高反式、高立构聚合物。手性单体2a、B与Mo（CHCMe（2）Ph）（NAr）[OC（CF 3）（3）]（2）（1 B）、Mo（CHCMe（2）Ph）（NAr '）[BIPH（t-Bu）（4）]（1c）和Mo（CHCMe（2）Ph）（NAr'）[（+/-）-BINO（SiMe（2）Ph）（2）]（THF）（1d）（Ar' = 2，6-Me（2）C（6）H（3））的ROMP产生高顺式、高立构聚合物。触觉可以直接确定的homomerase（质子/质子）相关光谱和去耦实验。发现顺式聚合物是全同立构的，反式聚合物是间同立构的。使用对映体纯的二取代降冰片烯（2，3-二甲氧甲基降冰片烯-5-烯、2，3-二甲氧基甲基降冰片烯-5-烯和5，6-二甲基降冰片烯-2-烯）的相关实验表明，用1a作为引发剂制备的高反式聚合物是无规的，而用1d作为引发剂制备的高顺式聚合物是全同立构的。双峰分子量分布，观察在某些情况下，当采用1D，符合略有不同的速率聚合的对映体纯基板的两种不同的对映体的外消旋引发剂。
The ring-opening metathesis polymerization (ROMP) of enantiomerically pure dicarboalkoxynorbornadienes (2,3-(CO(2)R*)(2)-norbornadiene where R* = (1R,2S,5R)-(-)-menthyl (2a) or (R)-(-)-pantalactonyl (2b)) with Mo(CHCMe(2)Ph)(NAr)(O-t-BU)(2) (1a) (Ar = 2,6-i-Pr2C6H3) yields high trans, highly tactic polymers. The ROMP of chiral monomers 2a,b with Mo(CHCMe(2)Ph)(NAr)[OC(CF3)(3)](2) (1b), Mo(CHCMe(2)Ph)(NAr')[BIPH(t-Bu)(4)] (1c), and Mo(CHCMe(2)Ph)(NAr') [(+/-)-BINO(SiMe(2)Ph)(2)](THF) (1d) (Ar' = 2,6-Me(2)C(6)H(3)) yields high cis, highly tactic polymers. Tacticities can be determined directly by homonuclear (proton/proton) correlation spectroscopy and decoupling experiments. The cis polymers were found to be isotactic, the trans polymers syndiotactic. Related experiments employing enantiomerically pure disubstituted norbornenes (2,3-dicarbomethoxynorborn-5-ene, 2,3-dimethoxymethylnorborn-5-ene, and 5,6-dimethylnorborn-2-ene) showed that high trans polymers prepared with 1a as the initiator are atactic while high cis polymers prepared with 1d as the initiator are isotactic. Bimodal molecular weight distributions were observed in some cases when 1d was employed, consistent with slightly different rates of polymerization of enantiomerically pure substrate by the two different enantiomers of the racemic initiator.