Development of Dynamic Multi-Functional Chiral Molecular Catalysts for Asymmetric Reduction and C-C Bond Formation

具有M/NH双官能团的Ru(Tsdpen)η^6-芳烃或C_p^*M(Tsdpen) （M = Rh, Ir）的手性过渡金属酰胺配合物具有足够的Bronsted碱度，可使2-丙醇或甲酸及酸性有机化合物去质子化，分别生成氢胺配合物和带有金属键C-亲核试剂的胺配合物。由于酰胺配合物和胺配合物之间快速有效的相互转化，手性酰胺配合物已被证明能以高度立体选择性的方式影响α-取代芳酮的不对称转移氢化和环烯酮的不对称迈克尔加成。以Ru_3(CO)_<12>和手性二亚氨基二膦四齿配体原位合成的手性Ru簇基催化剂体系可应用动态M/NH双官能团效应。该手性团簇影响了2-丙醇中芳酮的不对称转移加氢反应，生成了具有高ee的旋光性醇。酰胺和胺配合物的动态多官能团效应是催化剂具有高反应活性、选择性和实用性的重要原因。超临界流体是一种很有前途的分子催化反应介质，利用scCO_2可以显著提高分子催化剂的反应活性和选择性。为了更深入地了解分子催化在这一独特介质中的反应机理，利用商用核磁共振波谱仪和高压氧化锆电池，开发了一种超临界流体核磁共振（scNMR）波谱方法。我们发现三烷基亚磷酸酯配体对提高二氯钯（II）和二氯钌（II）配合物在scCO_2中的溶解度非常有效，Ru配合物促进了苯乙炔、二乙胺和scCO_2快速生成氨基甲酸乙烯酯。对二乙胺在scCO_2中的动力学行为进行了核磁共振研究，结果表明N， N-二乙基氨基甲酸的生成是可逆的，且氨基甲酸的浓度受压力和温度的影响较大。少

A well-defined chiral transition metal amide complex with a M/NH bifunctional unit, Ru(Tsdpen)η^6-arene) or C_p^*M(Tsdpen), (M = Rh, Ir), has sufficient Bronsted basicity to deprotonate 2-propanol or formic acid and acidic organic compounds, leading to a hydrido amine complex and amine complexes bearing a metal bonded C- nucleophile, respectively. Thanks to a rapid and effective interconversion between the amide complex and the amine complex, the chiral amide complex has proven to effect asymmetric transfer hydrogenation of α-substituted aromatic ketones and asymmetric Michael addition to cyclic eneones in a highly stereoselctive manner. The dynamic M/NH bifunctional effect can be applied to the chiral Ru cluster-based catalyst systems generated in situ from Ru_3(CO)_<12> and chiral diiminodiphosphine tetradentate ligands. This chiral cluster effected asymmetric transfer hydrogenation of aromatic ketones in 2-propanol, leading to optically active alcohols with high ee. The dynamic mult … More i-functional effect of both the amide and the amine complexes is responsible for the excellent catalyst performance in terms of high reactivity, selectivity, and practicability.We have demonstrated that supercritical fluids are promising reaction media for molecular catalysis and the utilization of a particular fluid, scCO_2 caused a remarkable enhancement of reactivities and selectivities of molecular catalysts. In order to gain deeper understanding of the reaction mechanism of the molecular catalysis in this unique media, a supercritical fluid nuclear magnetic resonance (scNMR) spectroscopic method has been developed using a commercially available NMR spectrometer equipped with a high-pressure zirconia cell. We found that trialkylphosphite ligands are highly effective for increasing the solubility of dichloropalladium(II) and dichlororuthenium(II) complexes in scCO_2 and the Ru complex promoted rapid vinyl carbamate formation from phenylacetylene, diethylamine, and scCO_2. The scNMR investigation on a dynamic behavior of diethylamine in scCO_2 revealed that formation of N, N-diethylcarbamic acid was reversible and the concentration of the carbamic acid was highly influenced by the pressure and temperature. Less