Marinescu Smaranda C, Schrock Richard R, Li Bo, Hoveyda Amir H
Department of Chemistry 6-331, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
J Am Chem Soc. 2009 Jan 14;131(1):58-9. doi: 10.1021/ja808308e.
The two diastereomers of Mo(NAr)(CHCMe(2)Ph)(2,5-dimethylpyrrolide)(1), (S(M)R(1))-2 and (R(M)R(1))-2, respectively, where 1 is an enantiomerically pure (R) phenoxide and Ar = 2,6-diisopropylphenyl, form adducts with PMe(3). One of these ((R(M)R(1))-2(PMe(3))) has been isolated. An X-ray structure reveals that PMe(3) has added trans to the pyrrolide; it is a model for where an olefin would attack the metal. Trimethylphosphine will catalyze slow interconversion of (S(M)R(1))-2 and (R(M)R(1))-2 via formation of weak PMe(3) adducts. Reactions between (S(M)R(1))-2 or (R(M)R(1))-2 and ethylene yield Mo(NAr)(CH(2))(Me(2)Pyr)(1) species in which the configuration at Mo is inverted by ethylene at a rate of the order of the NMR time scale at 22 degrees C via formation of metallacyclobutane intermediates with imido and aryloxide ligands in axial positions. A reactant olefin is proposed to approach Mo and the product olefin to leave Mo trans to the pyrrolide.
钼（NAr）（CHCMe(2)Ph）（2,5 - 二甲基吡咯化物）（1）的两种非对映异构体，分别为（S(M)R(1)）-2和（R(M)R(1)）-2，其中1是对映体纯的（R）苯氧化物且Ar = 2,6 - 二异丙基苯基，它们与PMe(3)形成加合物。其中一种（（R(M)R(1)）-2（PMe(3)））已被分离出来。X射线结构表明PMe(3)是反式加成到吡咯化物上；它是烯烃进攻金属的一个模型。三甲基膦将通过形成弱的PMe(3)加合物催化（S(M)R(1)）-2和（R(M)R(1)）-2的缓慢相互转化。（S(M)R(1)）-2或（R(M)R(1)）-2与乙烯之间的反应生成Mo（NAr）（CH(2)）（Me(2)Pyr）（1）物种，其中在22℃下，通过形成在轴向位置带有亚氨基和芳氧基配体的金属环丁烷中间体，Mo的构型被乙烯以NMR时间尺度量级的速率反转。提出反应物烯烃接近Mo，产物烯烃以反式于吡咯化物的方式离开Mo。
