Flook Margaret M, Jiang Annie J, Schrock Richard R, Müller Peter, Hoveyda Amir H
Department of Chemistry 6-331, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
J Am Chem Soc. 2009 Jun 17;131(23):7962-3. doi: 10.1021/ja902738u.
The molybdenum-based monoaryloxide monopyrrolide (MAP) species, Mo(NAd)(CHCMe(2)Ph)(C(4)H(4)N)(HIPTO) (2a), which contains "small" imido (Ad = 1-adamantyl) and "large" aryloxide (HIPTO = O-2,6(2,4,6-i-Pr(3)C(6)H(2))C(6)H(3)) ligands, catalyzes Z-selective metathesis reactions as a consequence of intermediate metallacyclobutane species not being able to have an (anti) substituent pointing toward the HIPTO group. Ring-opening metathesis polymerization (ROMP) of dicarbomethoxynorbornadiene (DCMNBD) with 2% 2a in toluene leads to >99% cis and >99% syndiotactic poly(DCMNBD), while ROMP of cyclooctene and 1,5-cyclooctadiene (300 equiv) with initiator 2a leads to poly(cyclooctene) and poly(cyclooctadiene) that have cis contents of >99%; all are previously unknown microstructures. Z-Selectivity is also observed in the metathesis of cis-4-octene and cis-3-hexene by initiator 2a to give cis-3-heptene.
基于钼的单芳氧基单吡咯化物(MAP)物种Mo(NAd)(CHCMe(2)Ph)(C(4)H(4)N)(HIPTO)(2a),其含有“小”的亚氨基(Ad = 1-金刚烷基)和“大”的芳氧基(HIPTO = O-2,6(2,4,6-i-Pr(3)C(6)H(2))C(6)H(3))配体,由于中间的金属环丁烷物种不能有一个(反式)取代基指向HIPTO基团,从而催化Z选择性复分解反应。在甲苯中用2%的2a引发二碳甲氧基降冰片二烯(DCMNBD)的开环复分解聚合(ROMP),得到>99%的顺式和>99%的间同立构聚(DCMNBD),而用引发剂2a引发环辛烯和1,5-环辛二烯(300当量)的ROMP,得到顺式含量>99%的聚(环辛烯)和聚(环辛二烯);所有这些都是以前未知的微观结构。引发剂2a在顺-4-辛烯和顺-3-己烯的复分解反应中也观察到Z选择性,生成顺-3-庚烯。