已经开发了一系列含有基于核苷的手性钳式配体的Mn I配合物,这些配合物具有模块化和可调的结构。该配合物在各种酮的氢化反应中显示出前所未有的高活性(高达9800 TON; TON =周转数),广泛的底物范围(81个实例),良好的官能团耐受性和出色的对映选择性(85-98%ee)。这些方面在稀土金属催化的氢化反应中很少见。该协议的实用性已在手性药物的多种关键中间体的不对称合成中得到证明。初步的机理研究表明,底物与催化剂相互作用的外层模式可能主导了催化作用。
Efficient Access to Chiral Benzhydrols via Asymmetric Transfer Hydrogenation of Unsymmetrical Benzophenones with Bifunctional Oxo-Tethered Ruthenium Catalysts
A concise asymmetric transfer hydrogenation of diaryl ketones, promoted by bifunctional Ru complexes with an etherial linkage between 1,2-diphenylethylenediamine (DPEN) and η(6)-arene ligands, was successfully developed. Because of the effective discrimination of substituents at the ortho position on the aryl group, unsymmetrical benzophenones were smoothly reduced in a 5:2 mixture of formic acid and
The use of a chiral (NCP)Ir complex as the precatalyst allowed for the discovery of asymmetrictransferhydrogenation of diaryl ketones with ethanol as the hydrogen source and solvent. This reaction was applicable to various ortho-substituted diaryl keontes, affording benzhydrols in good yields and enantioselectivities. This protocol could be carried out in a gram scale under mild reaction conditions
使用手性 (NCP)Ir 配合物作为预催化剂,可以发现以乙醇为氢源和溶剂的二芳基酮的不对称转移氢化。该反应适用于各种邻位取代的二芳基酮,以良好的收率和对映选择性提供苯甲醇。该方案可以在温和的反应条件下以克级进行。通过合成 ( S )-新苯诺定的关键前体突出了催化体系的实用性。
Novel Axially Chiral Phosphine Ligand with a Fluoro Alcohol Moiety for Rh-Catalyzed Asymmetric Arylation of Aromatic Aldehydes
作者:Satoshi Morikawa、Kyosuke Michigami、Hideki Amii
DOI:10.1021/ol100697a
日期:2010.6.4
A new chiral phosphine ligand (R)-1 possessing a fluoroalcohol moiety was prepared. The (R)-1-coordinated Rh(I) complex showed an excellent catalytic activity for asymmetric 1,2-addition of arylboronic acids to aldehydes to afford highly enantioenriched diarylmethanols. The fluoroalcohol moiety in ligand (R)-1 plays a pivotal role for the high enantioselectivity of the present Rh(I)-catalyzed transformation.