Exchange Processes in Shibasaki’s Rare Earth Alkali Metal BINOLate Frameworks and Their Relevance in Multifunctional Asymmetric Catalysis
作者:Jerome R. Robinson、Jun Gu、Patrick J. Carroll、Eric J. Schelter、Patrick J. Walsh
DOI:10.1021/jacs.5b02201
日期:2015.6.10
utility of this technique for probing solution dynamics of REMB catalysts. Isolation of the first crystallographically characterized REMB complex with substrate bound enabled stoichiometric and catalytic reactivity studies, wherein we observed that substrate deprotonation by the catalyst framework was necessary to achieve selectivity. Our spectroscopic observations in LA/BB catalysis are inconsistent with
Shibasaki 的稀土碱金属 BINOLate (REMB) 催化剂 (REMB; RE = Sc, Y, La - Lu; M = Li, Na, K; B = 1,1-bi-2-naphtholate; RE/M/B = 1 /3/3) 是最成功的对映选择性催化剂之一,并已用于广泛的机械反应。尽管这些催化剂取得了惊人的成功,但对其反应性至关重要的几个基本问题仍未解决。进行了组合反应性和光谱研究,以探测路易斯酸 (LA) 和路易斯酸/布朗斯台德碱 (LA/BB) 催化反应中活性催化剂的身份。交换光谱提供了一种获得 RE/Li 框架中配体和碱金属自交换速率的方法,证明了该技术在探测 REMB 催化剂溶液动力学方面的实用性。分离出第一个具有底物结合的晶体学表征的 REMB 复合物可以进行化学计量和催化反应研究,其中我们观察到催化剂框架的底物去质子化是实现选择性所必需的。我们在 LA/BB