Synthesis and Study of a Dialkylbiaryl Phosphine Ligand; Lessons for Rational Ligand Design
作者:Dillon J. Bryant、Lev N. Zakharov、David R. Tyler
DOI:10.1021/acs.organomet.9b00153
日期:2019.9.9
The rational design and synthesis of a novel dialkylbiarylphosphine ligand, 2′-(dimethylphosphine)-2,6-dimethoxy-1,1′-biphenyl (MeSPhos), for palladium-catalyzed C–N cross-coupling reactions is described. Based on previous results, it was hypothesized that a ligand with electronic properties similar to (2-biphenyl)dimethylphosphine (MeJPhos) but with greater steric bulk would allow the cross-coupling
描述了一种新颖的二烷基二芳基膦配体2'-(二甲基膦)-2,6-二甲氧基-1,1'-联苯(MeSPhos)的合理设计和合成,用于钯催化的C-N交叉偶联反应。基于先前的结果,假设具有与(2-联苯基)二甲基膦(MeJPhos)相似的电子性质但具有更大的空间体积的配体将允许先前难以接近的失活的芳基氯化物的交叉偶联。如所预测的,MeSPhos表现出与MeJPhos类似的电子特性。但是,令人惊讶的是,MeSPhos的空间分布比MeJPhos小得多。与广泛使用的CySPhos(2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl)相比,MeSPhos促进了CySPhos无效的高度失活的芳基氯化物的氧化加成,但大大降低了还原消除率。交叉偶联反应的动力学表明,改变的MeSPhos的空间和电子参数对交叉偶联的速率有重大影响,而减少的空间体积对催化剂的稳定性产生深远的有