Inversion of Configuration at the Metal in Diastereomeric Imido Alkylidene Monoaryloxide Monopyrrolide Complexes of Molybdenum
Inversion of Configuration at the Metal in Diastereomeric Imido Alkylidene Monoaryloxide Monopyrrolide Complexes of Molybdenum
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DOI：
10.1021/ja808308e
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发表时间：
2009-01-14
影响因子：
15
通讯作者：
Hoveyda, Amir H.
中科院分区：
文献类型：
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作者：
Marinescu, Smaranda C.;Schrock, Richard R.;Hoveyda, Amir H.
Mo（NAr）（CHCMe 2 Ph）（2，5-二甲基吡咯烷）（1）的两种非对映异构体（SMR 1）-2和RMR 1）-2（其中1是对映异构纯的（R）苯酚盐，Ar = 2，6-二异丙基苯基）分别与PMe 3形成加合物。其中之一（（RMR 1）-2（PMe 3））已被分离。X射线结构显示，PMe 3在吡咯烷中加入了反式，这是一个烯烃攻击金属的模型。三甲基膦将通过形成弱PMe 3加合物催化（SMR 1）-2和（RMR 1）-2的缓慢相互转化。（SMR 1）-2或（RMR 1）-2与乙烯之间的反应产生Mo（NAr）（CH 2）（Me（2）Pyr）（1）物种，其中Mo处的构型在22 ℃下以NMR时标的速率通过在轴向位置上具有亚氨基和芳氧基配体的金属环丁烷中间体的形成而被乙烯反转。提出了一种反应物烯烃接近钼和产品otefin离开钼反式的吡咯烷。
The two diastereomers of Mo(NAr)(CHCMe2Ph)(2,5-dimethylpyrrolide)(1), (SMR1)-2 and (RMR1)-2, respectively, where 1 is an enantiomericatly pure (R) phenoxide and Ar = 2,6-diisopropylphenyl, form adducts with PMe3. One of these ((RMR1)-2(PMe3)) has been isolated. An X-ray structure reveals that PMe3 has added trans to the pyrrolide; it is a model for where an olefin would attack the metal. Trimethylphosphine will catalyze slow interconversion of (SMR1)-2 and (RMR1)-2 via formation of weak PMe3 adducts. Reactions between (SMR1)-2 or (RMR1)-2 and ethylene yield Mo(NAr)(CH2)(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 otefin to leave Mo trans to the pyrrolide.