权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Construction of P-Chiral Reaction Field by Y-P-Y type Chiral Ligands and Application to Multi-site Controlled Asymmetric Reactions

Y-P-Y型手性配体构建P-手性反应场及其在多位点控制不对称反应中的应用

基本信息

批准号：
12650856
负责人：
YAMAGISHI Takamichi
金额：
$ 0.83万
依托单位：
Tokyo Metropolitan University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
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

Symmetrical Y-P-Y ligands having two coordinating units would be expected to form a P-chiral center if selective ligation of one of Y-units to metals occurs and to construct an effective chiral filed near the reaction site for asymmetric reactions. Residual Y unit would serve to interact with substrate or reaction reagent to realize the multi-site recognition to cause higher chiral induction. As N-P-N type ligand, various chiral bisoxazolylphosphine ligands having two chiral oxazoline units ((S,S)-R-P(Ox-R')_2) (R=Ph, ^iPr ; R'=Me, ^iPr, ^tBu) were prepared and their coordination mode to Pd, Pt, Rh, Ni, or Ru were examined by NMR technique. In the square planar complexes, large deviation in equilibrium to one of diastereomeric complexes was observed by the selective ligation of one of two oxazoline units to metal. This selective ligation to afford P-chiral center was also clarified by the X-ray analysis of a single crystal of [Pd(C_3H_5)-((S,S)-PhP(Ox-i^Pr)_2]PF_6.Bisoxazolylphosphine Pd complexes were applied to the asymmetric allylic alkylation and animation; In the enantiotopos differentiating allylic alkylation, high enantioselectivity more than 90 %ee were obtained, especially in the nucleophilic reaction of 1,3-dimethyl-π-allyl intermediate with a small steric factor 94% ee was obtained, which is the highest value reported so far. These results indicate the effectiveness of the P-chiral center formed by the selective ligation. In the reaction of alkyl zinc compound with π-allyl intermediate by Pd catalyst, the contribution of the free oxazolyl unit was observed to cause multi-site controlled reaction.

具有两个配位单元的对称Y-P-Y配体有望在其中一个Y单元与金属发生选择性连接时形成一个P-手性中心，并在反应中心附近为不对称反应构建一个有效的手性场。残留的Y单元将与底物或反应试剂相互作用，实现多位点识别，从而产生较高的手性诱导。作为N-P-N型配体，合成了两个手性恶唑啉单元((S，S)-R-P(Ox-R‘)2)(R=Ph，^IPr；R’=Me，^IPr，^Tbu)的手性双恶唑基膦配体，并用核磁共振技术研究了它们与Pd、Pt、Rh、Ni、Ru的配位方式。在方形平面配合物中，通过两个恶唑啉单元中的一个与金属的选择性配位，观察到与一个非对映异构体的平衡发生了很大的偏差。[Pd(C3H5)-((S，S)-Pp(Ox-i^Pr)2]Pf6]Pf_6单晶的X-射线分析也证实了这种选择性配位作用。双恶唑基膦钯配合物应用于不对称烯丙基烷基化反应和反应中，得到了90%以上的高对映体选择性ee，特别是在1，3-二甲基-π-烯丙基中间体的亲核反应中，得到了迄今报道的最高值94%ee。这些结果表明选择性连接形成的P-手性中心是有效的。在Pd催化下烷基锌化合物与π-烯丙基中间体的反应中，观察到游离恶唑单元的贡献导致了多中心控制反应。