Well-defined ruthenium olefin metathesis catalysts: Mechanism and activity
Well-defined ruthenium olefin metathesis catalysts: Mechanism and activity
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DOI：
10.1021/ja963136z
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发表时间：
1997-04-30
影响因子：
15
通讯作者：
Grubbs, RH
中科院分区：
文献类型：
--
作者：
Dias, EL;Nguyen, ST;Grubbs, RH
已经合成了几种式(PR3)(2)X2Ru=CHCHCPh2的钌基烯烃复分解催化剂，并通过监测闭环复分解或无环二烯二烯丙二酸二乙酯来测定相对催化剂活性。确定了以下活性增加顺序：X = I < Br < Cl 且 PR3 = PPh3 远小于 (PPr2Ph)-Pr-i < PCy2Ph < (PPr3)-Pr-i < PCy3。使用催化剂(PCy3)(2)-Cl2Ru=CH2进行了额外的研究，以探讨此类催化剂的烯烃复分解机理。这些数据支持一种方案，其中存在两种竞争途径：一种是膦从钌中心解离的主导途径，另一种是两种膦保持结合的次要途径。通过在反应中添加 CuCl 可以实现更高的催化剂活性。
Several ruthenium-based olefin metathesis catalysts of the formula (PR3)(2)X2Ru=CHCHCPh2 have been synthesized, and relative catalyst activities were determined by monitoring the ring-closing metathesis or the acyclic diene diethyl diallylmalonate. The following order of increasing activity was determined: X = I < Br < Cl and PR3 = PPh3 much less than (PPr2Ph)-Pr-i < PCy2Ph < (PPr3)-Pr-i < PCy3. Additional studies were conducted with the catalyst (PCy3)(2)-Cl2Ru=CH2 to probe the mechanism of olefin metathesis by this class of catalysts. The data support a scheme in which there are two competing pathways: the dominant one in which a phosphine dissociates from the ruthenium center and a minor one in which both phosphines remain bound. Higher catalyst activites could be achieved by the addition of CuCl to the reaction.