Asymmetric hydrosiliylation of ketones, catalyzed by rhodium complexes containing chiral chelate ligands. Crystal and molecular structure of (bicyclo[2.2.1]hepta-2,5-diene)[(S)-N,N-dimethyl-1-[o-(diphenylarsino)phenyl]ethylamine]rhodium(I) perchlorate
Asymmetric hydrosiliylation of ketones, catalyzed by rhodium complexes containing chiral chelate ligands. Crystal and molecular structure of (bicyclo[2.2.1]hepta-2,5-diene)[(S)-N,N-dimethyl-1-[o-(diphenylarsino)phenyl]ethylamine]rhodium(I) perchlorate
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由含有手性螯合配体的铑络合物催化的酮的不对称氢化硅烷化。
DOI：
10.1021/ic00131a034
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发表时间：
1982
影响因子：
4.6
通讯作者：
D. Stephan
中科院分区：
文献类型：
--
作者：
N. C. Payne;D. Stephan
式o-(X(C6H5)2)C6H4CH(CH3)N(CH3)2的两个手性二齿配体，amphos(X＝磷)和amors(X＝砷)，已经由(7′)-和(5)-1-苯乙胺以良好产率制备。这些配体的铑配合物已用于一系列前手性酮的不对称硅氢化。为了进行比较，使用含有手性二膦物质 (S, S)-chiraphos 和 (+)-diop 的 Rh 催化剂重复反应。使用 amphos 催化剂实现了 72% 的最大对映体过量，而相反，amars 催化剂没有产生诱导。基于 [Rh (S-amars)(C7H8)] C104 的三维单晶 X 射线研究结果，提出了对此行为的解释。盐在空间群 PI 中结晶，每个晶胞有两个分子式单位，晶胞尺寸为 a= 10.154 (6) A、b= 15.082 (9) A、c= 9.538 (6) A、a= 97.64 (1)、ß= 96.05 (1) 和 y= 74.43 (1)。该结构已通过 F 上的全矩阵最小二乘技术进行了细化，并使用了 I> 3 (/) 的 3834 次反射，最终一致性因子为 R¡= 0.059。两个独立的手性阳离子在Rh原子上具有基本上方形平面的配位几何形状（如果二烯被视为双齿螯合配体），平均Rh-As和Rh-N距离分别为2.398 (3)和2.177 (18) A。每个六元环均采用a-扭船构象。尽管如此，在晶胞中观察到苯环的伪轴赤道排列的对映体配置，这种构象灵活性可能是观察到的光学产率的原因。
Two chiral, bidentate ligands of formula o-(X (C6H5) 2) C6H4CH (CH3) N (CH3) 2, amphos (X= phosphorus) and amars (X= arsenic), have been prepared in good yield from (7?)-and (5)-1-phenylethylamine. Rhodium complexes of these ligands have been used for the asymmetric hydrosilation of a series of prochiral ketones. For comparison purposes, the reactions were repeated with Rh catalysts containing the chiral, diphosphine species (S, S)-chiraphos and (+)-diop. The maximum enantiomeric excess of 72% was achieved with the amphos catalyst, while, in contrast, the amars catalyst gave no induction. An explanation for this behavior is proposed, on the basis of the results of a three-dimensional single-crystal X-ray study of [Rh (S-amars)(C7H8)] C104. The salt crystallizes in space group PI with two formula units per cell and unit cell dimensions a= 10.154 (6) A, b= 15.082 (9) A, c= 9.538 (6) A, a= 97.64 (1), ß= 96.05 (1), and y= 74.43 (1). Thestructure has been refined by full-matrix least-squares techniques on F, with the use of 3834 reflections with I> 3 (/), to a final agreement factor of R¡= 0.059. The two independent chiral cations have essentially square-planar coordination geometries at the Rh atoms (if the diene is viewed as a bidentate chelating ligand), with average Rh-As and Rh-N distances of 2.398 (3) and 2.177 (18) A, respectively. Each six-membered ring adopts a-twist boat conformation. In spite of this, enantiotopic dispositions of the pseudo axial-equatorial arrangements of the phenyl rings are observed in the unit cell, a conformational flexibility which is presumably responsible for the observed optical yields.