Chiral cyclopalladated complex promoted asymmetric synthesis of diester-substituted P,N-ligands via stepwise hydrophosphination and hydroamination reactions
作者:Ke Chen、Sumod A. Pullarkat、Mengtao Ma、Yongxin Li、Pak-Hing Leung
DOI:10.1039/c2dt12379g
日期:——
A series of enantiomerically pure 1,2-diester substituted P,N-ligands incorporating two chiral carbons in the backbone were generated in high yields and high stereoselectivity from acetylenedicarboxylate via initial hydrophosphination using diphenylphosphine followed by hydroamination with various primary and secondary amines. The reactions were activated and stereochemically controlled by the organopalladium complex containing ortho-palladated (S)-(1-(dimethylamino)ethyl)naphthalene under mild conditions. The absolute stereochemistry and the coordination chemistry of P,N-products were determined by the single crystal X-ray diffraction analysis. All the chiral P,N-ligands could be liberated from the palladium template without loss of optical purity. Subsequent recomplexation to selected chiral palladium centers confirmed the optical purity of the new functionalized chiral P,N-ligands.
通过使用二苯基膦进行初始氢化膦反应,然后使用各种伯胺和仲胺进行氢化反应,从乙炔二甲酸酯中生成了一系列对映体纯度极高的 1,2 二酯取代的 P,N 配体,这些配体的骨架中含有两个手性碳,并具有极高的产率和立体选择性。在温和的条件下,含有正交钯化 (S)-(1-(二甲基氨基)乙基)萘的有机钯络合物对反应进行了激活和立体化学控制。通过单晶 X 射线衍射分析确定了 P,N 产物的绝对立体化学性质和配位化学性质。所有手性 P,N-配体都能从钯模板中释放出来,而不会损失光学纯度。随后与选定的手性钯中心的再络合证实了新的功能化手性 P,N 配体的光学纯度。