Mechanistic Study on Asymmetric Oxidations with Metallosalen Complexes as Catalysts and Exploitation of New Metallosalen Complexes

金属Salen配合物催化剂不对称氧化机理研究及新型金属Salen配合物的开发

基本信息

批准号：
09440220
负责人：
KATSUKI Tsutomu
金额：
$ 8.83万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

Metallosalen Complexes are excellent catalysts for asymmetric oxene and carbene transfer reactions but our understanding of the mechanism of asymmetric induction is still immature. However, knowledge on the mechanism is indispensable for understanding the stereochemistries of the asymmetric reactions and developing new type of highly efficient asymmetric reactions.Although salen ligand had been recognized to have a planar structure, the analysis of stereochemistry in the ylide formation of sulfide using chiral (salen)cobalt complex suggested that the salen ligand had not a planar but stepped structure. This finding on the ligand-conformation was strongly supported by realizing as asymmetric epoxidation with achiral (salen)manganese complexes as catalysts in the presence of chiral axial ligands. Furthermore, X-ray analysis of chiral (salen)manganese complexes proved that the salen ligands adopt stepped conformation. Basing on these findings, we succeeded in an efficient kinetic resolution of allene compounds and asymmetric hydroxylation of benzylic C-H bonds.In addition to these results, unique asymmetric cyclopropanation was also developed by employing nitroso (salen) ruthenium complexes. Though the ruthenium complexes are catalytically inactive, photo-irradiation makes them active. Furthermore, the complexes are expected to have highly pliable structure basing on the X-ray analysis of the complex. Taking advantage of high pliability of the ruthenium complex, we could controlled the ligand conformation by choosing solvent and achieve for the first time highly cis- and enantio-selective cyclopropanation.

金属素络合物是非对称氧烯和卡宾转移反应的极好的催化剂，但是我们对不对称诱导机理的理解仍然不成熟。 However, knowledge on the mechanism is indispensable for understanding the stereochemistries of the asymmetric reactions and developing new type of highly efficient asymmetric reactions.Although salen ligand had been recognized to have a planar structure, the analysis of stereochemistry in the ylide formation of sulfide using chiral (salen)cobalt complex suggested that the salen ligand had not a planar but stepped structure.在有手性轴向配体的情况下，用Achiral（salen）锰配合物作为催化剂的不对称环氧化，可以强烈支持配体构造的这一发现。此外，手性（Salen）锰配合物的X射线分析证明了SALEN配体采用垫层构象。在这些发现的基础上，我们成功地对苯烯化合物的有效动力学分辨率和苄基C-H键的不对称羟基化。在这些结果之外，还通过采用硝基氮（salen）ruthenium复合物来开发独特的不对称环丙烷化。尽管钌络合物是催化性的，但光辐照使它们活跃。此外，在复合物的X射线分析上，这些复合物有望具有高柔韧的结构。利用芳族复合物的高柔韧性，我们可以通过选择溶剂并首次实现高度顺式和对映选择性环丙烷化来控制配体构象。