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Development of Organometallic Catalyst Base on the Control of Organometallic Cluster

基于有机金属簇调控的有机金属催化剂的开发

基本信息

批准号：
12440175
负责人：
NAKAMURA Masaharu
金额：
$ 4.99万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

This research has been conducted in order to develop synthetically useful new carbon-carbon bond forming reactions based on theoretical design of organometallic reagent, which often exists as a cluster in solution. As an example of the c-C bond forming reaction with an organometallic cluster, we examined the addition of allylzinc chloride to vinyl Grignard reagent, which was first reported by Gaudemar in 1971 and has been developed by Normant and co-workers to be a synthetically useful reaction. We revealed, for the first time, that the formation of a Zn/Mg organometallic aggregate functions as a key intermediate to facilitate the addition reaction, and the formation of organozinc aggregate resulted in the stabilization of product to make the whole process thermodynamically favored one. In the course of our continuing study on the organometallic cluster reaction, we found that the vinyl boron substrate can be exploited as a reactive carbometalation acceptor. The mechanistic detail of the addition of allylzine reagent to vinylboronate was studied by using the DFT calculations. The reaction starts with the formation of σ-complex, in which zinc atom is bound to one of the two oxygens of boronic and ester. Two distinct reaction pathways, "bora-Claisen" pathway and "zincio-ene" pathway, were obtained as in the addition of allylzine reagent to vinyl boronate. In contrast to the allyizincation reaction, the addition of zincioenamine to vinylboronate proceeds via concerted six-membered chair and boat transitiion states. Low activation energy was required to effect the addition via the boat transition state, indicating high reactivity of the zincioenamine toward an olefinic double bond. Thus, the addition of zincioenamine to a simple alkene, such as 1-octene and allylbenzene, was examined and was proved to be a facile reaction under certain conditiions.

有机金属试剂在溶液中通常以簇状形式存在，本研究的目的是基于有机金属试剂的理论设计，开发具有综合实用价值的新型碳-碳键形成反应。作为与有机金属簇形成C-C键反应的一个例子，我们研究了烯丙基氯化锌与乙烯基格氏试剂的加成反应，该反应由Gaudemar于1971年首次报道，并已由Normant及其同事开发为一种合成有用的反应。我们首次揭示了锌/镁金属有机聚集体的形成是促进加成反应的关键中间体，而有机锌聚集体的形成导致了产物的稳定，从而使整个过程在热力学上是有利的。在我们对有机金属簇合物反应的继续研究过程中，我们发现乙烯基硼底物可以被用作反应性碳金属化的受体。通过密度泛函理论计算，研究了烯丙基锌试剂与乙烯基硼酸根反应的机理。该反应始于σ络合物的形成，在该络合物中，锌原子与硼和酯两个氧原子中的一个结合。与加入烯丙基锌试剂相比，得到了两条不同的反应途径，即“Bora-Claisen”途径和“zinco-ene”途径。与烯丙化反应不同的是，乙烯基硼酸锌胺与乙烯基硼酸酯的加成反应是通过协调的六元椅子和船型过渡态进行的。需要较低的活化能才能通过BOAT过渡态进行加成，这表明锌胺对烯烃双键的反应活性很高。因此，我们考察了锌胺与1-辛烯和烯丙基苯等简单烯烃的加成反应，并证明在一定条件下该反应是一种简单的反应。