Department of Chemistry 6-331, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
J Am Chem Soc. 2015 Feb 18;137(6):2239-42. doi: 10.1021/jacs.5b00221. Epub 2015 Feb 5.
Four alternating AB copolymers have been prepared through ring-opening metathesis polymerization (ROMP) with Mo(NR)(CHCMe2Ph)[OCMe(CF3)2]2 initiators (R = 2,6-Me2C6H3 (1) or 2,6-i-Pr2C6H3 (2)). The A:B monomer pairs copolymerized by 1 are cyclooctene (A):2,3-dicarbomethoxy-7-isopropylidenenorbornadiene (B), cycloheptene (A'):dimethylspiro[bicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylate-7,1'-cyclopropane] (B'), A:B', and A':B; A':B' and A:B' are also copolymerized by 2. The >90% poly(A-alt-B) copolymers are formed with heterodyads (AB) that have the trans configuration. Evidence suggests that one trans hetero C═C bond is formed when A (A or A') reacts with the syn form of the alkylidene made from B (syn-MB = syn-MB or syn-MB') to give anti-MA, while the other trans C═C bond is formed when B reacts with anti-MA to give syn-MB. Cis and trans AA dyads are proposed to arise when A reacts with anti-MA in competition with B reacting with anti-MA.
通过使用 Mo(NR)(CHCMe2Ph)[OCMe(CF3)2]2 引发剂（R = 2,6-Me2C6H3 (1) 或 2,6-i-Pr2C6H3 (2)）进行开环易位聚合（ROMP），已经制备了四种交替的 AB 共聚物。1 共聚的 A:B 单体对是环辛烯（A）：2,3-二羧甲氧基-7-异丙叉基降冰片二烯（B），环庚烯（A'）：二甲基螺[二环[2.2.1]庚-2,5-二烯-2,3-二羧酸酯-7,1'-环丙烷]（B'），A:B，A':B'和 A':B；2 也可以共聚 A':B'和 A:B'。形成了具有反式构型的 >90%的聚（A-alt-B）共聚物。有证据表明，当 A（A 或 A'）与 B（syn-MB = syn-MB 或 syn-MB'）形成的顺式亚烷基反应时，形成一个反式异 C═C 键，给出反式 MA，而另一个反式 C═C 键则当 B 与反式 MA 反应时形成顺式 MB。顺式和反式 AA 二聚体是在 A 与反式 MA 反应与 B 与反式 MA 反应竞争时产生的。
