Development of Chiral Ligand Based on Double Asymmetric Induction and Application to Catalytic Reaction.

设想的配体是用于钯催化剂的单齿膦配体。基于双不对称诱导法设计了一个新的手性配体。因此，轴向手性和手性助剂的组合构成了手性配体的骨架。最初，轴向手性片段是联萘骨架，因为该骨架已被证明具有最有效的诱导能力。作为另一种手性助剂，选择恶唑烷和缩醛结构。在联萘骨架的2位和2'位上引入二苯基膦基和手性助剂。尽管进行了大量的试验，但仍不能合成最期望的配体，但制备了另一种配体并在几种钯催化的反应中进行了测试。不幸的是，在典型的反应条件下，在每个催化反应中，迄今为止没有观察到高的不对称诱导。然而，这一概念被认为是获得更有效的手性配体的新方向。

The envisioned ligand is monodentate phosphine ligand for palladium catalyst. The new chiral ligand was designed based on the double asymmetric induction methodology which is well known in a usual asymmetric reaction. Thus, the combination of axial chirality and chiral auxiliary constitutes the backbone of the chiral ligand. Initially, the axially chiral fragment was binaphthalene framework, because the skeleton has been proved to exhibit most efficient induction ability. As an another chiral auxiliary, oxazohdine and acetal structures were selected. Diphenylphosphino group and chiral auxiliary were planned to be put on 2 and 2' positions on the binaphthalene framework. Although the most desired ligand could not be synthesized in spite of intensive trials, another ligand was prepared and tested in several palladium catalyzed reactions. Unfortunately, the high asymmetric induction was not observed so far under the typical reaction conditions in each catalyzed reaction. However, this concept is believed to be anew direction to obtain more efficient chiral ligand.