Chiral 1,2-Cyclohexane-Bridged Bis-NHC Palladium Catalysts for Asymmetric Suzuki–Miyaura Coupling: Synthesis, Characterization, and Steric Effects on Enantiocontrol
作者:Yinle Li、Junkai Tang、Jun Gu、Quanrui Wang、Peipei Sun、Dao Zhang
DOI:10.1021/om400825e
日期:2014.2.24
catalyze the asymmetric Suzuki–Miyaura couplings of aryl halides with arylboronic acids in good yields (up to 96%) and moderate enantioselectivities (up to 64% ee). The coligand and steric effects were studied carefully. The coligands, including Br–, Cl–, AcO–, CF3COO–, and water molecules, have little influence on the catalytic results. However, a strong steric effect of the two aromatic substituents
该系列的手性1,2-环己烷桥接的二N-杂环卡宾配体前体为h 2 [(1 - [R,2 - [R )- (1A -我)]溴用不同的取代基和它们的中性和阳离子二水钯络合物,即PD [(1 - [R,2 - [R )- (1A -我)]溴2 }(2A -我),PD [(1 - [R,2 - [R )- (1A)]× 2 }(X = Cl(上3),OAC(4- OAC),OC(O)CF 3(4-OCH(O)CF 3)),和PD [(1 - [R,2 - [R )- (大号OME)](OH 2)2 } X 2(X =光学传递函数(5-光学传递函数),的SbF 6(5-的SbF 6))已经制备在中度至良好的收益。这些手性钯复合物完全表征通过元素分析,高分辨率质谱,1个H和13 C NMR,和旋光测定。手性复合物的晶体结构2A和5-光学传递函数进一步证实了采用绕钯中心扭曲的正方形平面协调几何。获得