A Simple Iridium Catalyst with a Single Resolved Stereocenter for Enantioselective Allylic Amination. Catalyst Selection from Mechanistic Analysis
作者:Andreas Leitner、Shashank Shekhar、Mark J. Pouy、John F. Hartwig
DOI:10.1021/ja054331t
日期:2005.11.1
A study of the relationship between the stereochemical elements of a phosphoramidite ligand and the stereoselectivity of iridium-catalyzed amination of allylic carbonates is reported. During catalyst activation, a complex of a phosphoramidite ligand possessing one axial chiral binaphtholate group and two resolved phenethyl substituents converts to a more reactive cyclometalated complex containing one
报道了亚磷酰胺配体的立体化学元素与铱催化烯丙基碳酸酯胺化的立体选择性之间关系的研究。在催化剂活化过程中,具有一个轴向手性联萘基团和两个拆分的苯乙基取代基的亚磷酰胺配体的络合物转化为反应性更强的环金属化络合物,该络合物在氮处含有一个远端手性取代基,一个取代基成为金属环的一部分,以及一个未受干扰的联萘基团. 对不同的立体化学元素进行了系统的改变。用大的非手性环烷基取代远端手性苯乙基取代基导致催化剂的反应速率和对映选择性类似于具有苯乙基的原始催化剂的反应速率和对映选择性。含 (R) 或 (S) 联萘基团在磷上的非对映配体以及氮上的一个 (R)-苯乙基和一个非手性环十二烷基的反应研究表明,这两种非对映配体的配合物在非常不同的情况下进行环金属化率。为了获得两种非对映体催化剂并确定反应是否可以与更简单的配体选择性地发生,该配体在氮处含有苯乙基取代基作为唯一解析的立体化学元素,研究了衍生自含有联苯酚基团
Palladium-Catalyzed, Asymmetric Mizoroki–Heck Reaction of Benzylic Electrophiles Using Phosphoramidites as Chiral Ligands
作者:Zhigang Yang、Jianrong (Steve) Zhou
DOI:10.1021/ja304099j
日期:2012.7.25
We report herein the first examples of asymmetric Mizoroki-Heck reactions using benzyl electrophiles. A new phosphoramidite was identified to be an effective chiral ligand in the palladium-catalyzed reaction. The reaction is compatible with polar functional groups and can be readily scaled up. Several cyclic olefins worked well as olefin components. Thirty-one examples are included.