The significance of degenerate processes to enantioselective olefin metathesis reactions promoted by stereogenic-at-Mo complexes.
The significance of degenerate processes to enantioselective olefin metathesis reactions promoted by stereogenic-at-Mo complexes.
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DOI：
10.1021/ja907805f
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发表时间：
2009-11-18
影响因子：
15
通讯作者：
Hoveyda, Amir H.
中科院分区：
文献类型：
--
作者：
Meek, Simon J.;Malcolmson, Steven J.;Li, Bo;Schrock, Richard R.;Hoveyda, Amir H.
本研究提供的光谱和实验证据表明，简并复分解是这类新兴的手性催化剂的有效性的关键。公开了两种非对映体络合物的分离和表征（X-射线），以及由这种引发新叶烯在促进RCM过程中表现出的反应性和对映体选择性模式的检查。只有当产生足够量的乙烯并且通过简并过程以足够快的速率发生在Mo处的转化时，才能实现高的对映选择性，而不管起始亚烷基的立体化学身份（Curtin-Hammett动力学）。对于经历快速相互转化的非对映体金属络合物，金属中心处的立体突变变得无关紧要，并且不需要手性催化剂的立体选择性合成。
The present study provides spectroscopic and experimental evidence demonstrating that degenerate metathesis is critical to the effectiveness of this emerging class of chiral catalysts. Isolation and characterization (X-ray) of both diastereomeric complexes, as well as examination of the reactivity and enantioselectivity patterns exhibited by such initiating neophylidenes in promoting RCM processes, are disclosed. Only when sufficient amounts of ethylene are generated and inversion at Mo through degenerate processes occurs at a sufficiently rapid rate, is high enantioselectivity achieved, irrespective of the stereochemical identity of the initiating alkylidene (Curtin-Hammett kinetics). With diastereomeric metal complexes that undergo rapid interconversion, stereomutation at the metal center becomes inconsequential and stereoselective synthesis of a chiral catalyst is not required.
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影响因子：
15
作者：
Jiang, Annie J.;Simpson, Jeffrey H.;Schrock, Richard R.
通讯作者：
Schrock, Richard R.
影响因子：
15
作者：
Marinescu, Smaranda C.;Schrock, Richard R.;Hoveyda, Amir H.
通讯作者：
Hoveyda, Amir H.
影响因子：
15
作者：
Van Veldhuizen, JJ;Gillingham, DG;Hoveyda, AH
通讯作者：
Hoveyda, AH
影响因子：
15
作者：
Marinescu, Smaranda C.;Schrock, Richard R.;Hoveyda, Amir H.
通讯作者：
Hoveyda, Amir H.
影响因子：
56.9
作者：
HALPERN, J
通讯作者：
HALPERN, J