Persistent <i>N</i>-Chirality as the Only Source of Asymmetry in Nonracemic N<sub>2</sub>PdCl<sub>2</sub> Complexes
作者:Kathryn A. Pelz、Peter S. White、Michel R. Gagné
DOI:10.1021/om0498495
日期:2004.6.1
and diastereopure N2Pd(3,3‘-Me2BINOL) complexes. HCl removes the Me2BINOL resolving ligand and provides a family of enantiopure N2PdCl2 complexes whose only stereochemistry resides on the stereogenic nitrogen centers. In effect, nitrogen inversion (>105 s-1) is halted by metal coordination and utilized to generate enantiopure complexes. When the diamine substituents are relatively small, the N-chirality
前手性1,2-二胺,Pd(OAc)2和(R)-K 2 -3,3'-Me 2 BINOL的组合导致对映体和非对映体N 2 Pd(3,3'-Me 2 BINOL )复合体。HCl除去Me 2 BINOL解析配体,并提供一系对映纯N 2 PdCl 2配合物,其立体化学仅存在于立体氮中心。实际上,氮的反转(> 10 5 s - 1)通过金属配位而停止,并用于生成对映纯配合物。当二胺取代基相对较小时,N-手性稳定;然而,大的取代基加速了N-解离过程和伴随的外消旋化。可以为Diels-Alder反应生成对映纯N 2 Pd 2 +-路易斯酸催化剂,尽管对映选择性低(<25%ee),但这是由于立体化学转移效率低,而不是降低了催化剂的手性。