Aspects of Heterogeneous Enantioselective Catalysis by Metals
Aspects of Heterogeneous Enantioselective Catalysis by Metals
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DOI：
10.1021/la200009w
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发表时间：
2011-08-16
期刊：
影响因子：
3.9
通讯作者：
Lambert, Richard M.
中科院分区：
文献类型：
--
作者：
Kyriakou, Georgios;Beaumont, Simon K.;Lambert, Richard M.
金属催化的非均相对映选择性反应的一些方面进行了审查，具体参考四个不同的系统中，控制对映选择性的现象似乎是非常不同的。在葡萄糖电氧化的情况下，很明显，存在于金属表面的任何固有手性起着至关重要的作用。与α-酮氢化，非手性表面改性的手性剂的吸附成为有效的对映选择性催化剂和手性物种的扩展阵列的形成似乎是不重要的：相反，1：1对接相互作用控制的氢键之间的吸附的手性改性剂和前手性反应物决定的结果。氢键在β-酮酯氢化中也起着核心作用，但这里的基础研究表明，涉及反应物和手性配体的有序阵列的形成是重要的。不对称C=C氢化，虽然研究相对较少，但在实验室规模的合成有机化学和精细化学品和药物的制造中具有重大影响的潜力。决定给定手性配体是否有效的结构属性已经确定;与金属表面形成强共价键的能力，同时在反应条件下抵抗强吸附反应物的氢化和置换是一个必不可少的必要条件。除此之外，在手性中心附近的配体刚性加上对SAM形成的抗性是一个至关重要的因素，其缺乏导致外消旋化学。
Some aspects of metal-catalyzed heterogeneous enantioselective reactions are reviewed with specific reference to four different systems where the phenomena that control enantioselection appear to be very different. In the case of glucose electro-oxidation, it is clear that any intrinsic chirality present at the metal surface plays a vital role. With alpha-keto hydrogenation, achiral surfaces modified by the adsorption of chiral agents become effective enantioselective catalysts and the formation of extended arrays of chiral species appears not to be of importance: instead a 1:1 docking interaction controlled by hydrogen bonding between the adsorbed chiral modifier and the prochiral reactant determines the outcome. Hydrogen bonding also plays a central role in beta-ketoester hydrogenation, but here fundamental studies indicate that the formation of ordered arrays involving the reactant and chiral ligand is of importance. Asymmetric C=C hydrogenation, though relatively little studied, has the potential for major impact in synthetic organic chemistry both on the laboratory scale and in the manufacture of fine chemicals and pharmaceuticals. The structural attributes that determine whether a given chiral ligand is effective have been identified; the ability to form strong covalent bonds with the metal surface while also resisting hydrogenation and displacement by the strongly adsorbing reactant under reaction conditions is an essential necessary condition. Beyond this, ligand rigidity in the vicinity of the chirality center coupled with resistance to SAM formation is a critically important factor whose absence results in racemic chemistry.