Development of a novel chiral palladacycle and its application in asymmetric hydrophosphination reaction
作者:Jeanette See Leng Yap、Bin Bin Li、Jonathan Wong、Yongxin Li、Sumod A. Pullarkat、Pak-Hing Leung
DOI:10.1039/c4dt00062e
日期:——
Pd(OAc)2 gave the racemic dimeric complex in high yield. This racemic palladacycle was efficiently resolved through the formation of its (S)-prolinato derivatives. The resulting diastereomeric complexes were separated efficiently by column chromatography. In the solid state, the structure and absolute configuration of the two optically resolved palladium complexes were determined by single crystal X-ray crystallography
通过三步合成路线,由1-(2,5-二氯苯基)乙酮合成了一种新型的胺配体1-(2,5-二氯苯基)-N,N-二甲基乙胺。胺配体与Pd(OAc)2的直接邻位钯制得高产率的外消旋二聚体。通过形成其(S)-脯氨酸衍生物,有效地拆分了外消旋的palladacycle 。通过柱色谱法有效地分离得到的非对映异构体复合物。在固态下,两种光学拆分的钯配合物的结构和绝对构型是通过单晶X射线晶体学确定的。在解决方案中,他们的绝对构象也由2D进行了研究1 H– 1 H旋转框架核Overhauser增强(ROESY)NMR光谱。( R, R)和( S, S)-二-μ-氯二聚钯配合物都可以通过用稀盐酸处理相应的脯氨酰胺衍生物来化学选择性地获得。随后可以通过用浓盐酸处理将胺助剂从钯中心除去。对映体纯的palladacycle用于促进二苯基膦和乙炔二羧酸二甲酯之间的不对称氢磷酸化反应。的31 p 1个H} NMR谱表明,只有一个立体异构体的产物形成。