Enantioselective Hydrogenation with Self-Assembling Rhodium Phosphane Catalysts: Influence of Ligand Structure and Solvent
作者:Mandy-Nicole Birkholz、Natalia V. Dubrovina、Haijun Jiao、Dirk Michalik、Jens Holz、Rocco Paciello、Bernhard Breit、Armin Börner
DOI:10.1002/chem.200601607
日期:2007.7.6
assemble by hydrogen bonding and form chelates. In contrast, synthetic precursors bearing alkoxypyridine appendages are not able to aggregate via intramolecular hydrogen bonds. The nature of self-assembly is dependent on the nature of the P ligand and the solvent used for the hydrogenation (CH2Cl2 vs. MeOH). These features affect the rate of the reaction as well as the enantioselectivity, which varied
已经制备了三组新的和相关的手性磷杂环戊烯和磷脂碱配体用于Rh催化的对映选择性氢化。环状单膦的大小和取代方式是变化的。更重要的是,配体在与三价磷原子连接的杂环基团的性质上有所不同:2-吡啶酮或2-烷氧基吡啶。在相应的Rh络合物中,两个单齿P配体的吡啶酮单元可通过氢键组装并形成螯合物。相反,带有烷氧基吡啶附属物的合成前体不能通过分子内氢键聚集。自组装的性质取决于P配体的性质和用于氢化的溶剂(CH2Cl2对MeOH)。这些特征会影响反应速度以及对映选择性,