We recently introduced a family of 6-NHC-Cu(I) catalysts that exhibit highest selectivities (regio- and enantio-) exclusively when aryl ethers are used as the leaving group. Understanding the match between a catalyst and leaving group remains elusive. We sought to increase our understanding of this system by comparing our catalyst’s activity with other catalysts using substrates that contain different leaving groups. Our objective is to better understand the regioselectivity–leaving group combinations. We also observed that our catalyst functioned best when methanol was used as an additive. We examined the selectivities as a function of other protic additives. Finally, we wanted to understand the regioselectivity–enantioselectivity relationship with regards to internal versus terminal leaving groups. Overall, we demonstrate that matching leaving group and catalyst is important and that for our extended aromatic ligand the use of aromatic leaving groups is a unique pairing. We also demonstrate that the leaving group is also critical for controlling both types of selectivity.
我们最近推出了一系列6-NHC-Cu(I)催化剂,当芳基醚作为离去基团时,这些催化剂表现出最高的选择性(区域性和对映选择性)。催化剂和离去基团之间的匹配关系仍然不清楚。我们试图通过使用含有不同离去基团的底物来比较我们催化剂的活性与其他催化剂的活性,以增加对该系统的理解。我们的目标是更好地理解区域选择性和离去基团的组合。我们还观察到,当甲醇被用作添加剂时,我们的催化剂的功能最佳。我们检查了其他质子性添加剂的选择性。最后,我们想了解内部和末端离去基团与区域选择性-对映选择性关系之间的关系。总的来说,我们证明了匹配离去基团和催化剂的重要性,并且对于我们的扩展芳香配体,使用芳香离去基团是一种独特的配对。我们还证明,离去基团对于控制两种类型的选择性也是至关重要的。