Development of Organometallic Catalyst Base on the Control of Organometallic Cluster

本研究的目的是基于有机金属试剂的理论设计，开发综合有用的新的碳-碳键形成反应，有机金属试剂在溶液中通常以簇合物的形式存在。作为与有机金属簇合物的c-C键形成反应的一个例子，我们研究了烯丙基氯化锌与乙烯基格氏试剂的加成，这是Gaudemar在1971年首次报道的，并已由Normant及其同事开发为合成有用的反应。我们首次发现，Zn/Mg有机金属聚集体的形成是促进加成反应的关键中间体，并且有机锌聚集体的形成导致产物的稳定化，使整个过程成为化学上有利的过程。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作为反应性碳化受体。用密度泛函理论研究了烯丙基锌试剂与乙烯基硼酸酯加成反应的机理细节。反应开始时，锌原子与硼酸和酯的两个氧原子中的一个键合形成σ-络合物。在烯丙基锌试剂与硼酸乙烯酯的加成反应中，得到了两种不同的反应途径，即“硼-克莱森”途径和“锌-烯”途径。与烯丙基化反应相反，锌烯胺与乙烯基硼酸酯的加成通过协调的六元椅和船过渡态进行。需要低活化能来实现经由船式过渡态的加成，表明锌烯胺对烯属双键的高反应性。因此，考察了锌烯胺与简单烯烃（如1-辛烯和烯丙基苯）的加成反应，并证明在一定条件下是一个容易的反应。

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.