Chiral Pd aqua complex-catalyzed asymmetric C-C bond-forming reactions: a Brønsted acid-base cooperative system.
Chiral Pd aqua complex-catalyzed asymmetric C-C bond-forming reactions: a Brønsted acid-base cooperative system.
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DOI：
10.1039/b911015a
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发表时间：
2009-09
影响因子：
4.9
通讯作者：
M. Sodeoka;Y. Hamashima
中科院分区：
文献类型：
--
作者：
M. Sodeoka;Y. Hamashima
手性阳离子钯水配合物可以作为酸碱催化剂，有效地活化活性亚甲基和次甲基化合物，得到手性钯烯醇化物。值得注意的是，这种烯醇化物的形成伴随着强质子酸的形成而发生。虽然Pd烯醇化物本身的反应性不足以与碳基亲电试剂反应，但其与质子酸活化亲电试剂的协同作用允许所需的C-C键形成反应以高度对映选择性的方式顺利进行。基于这种机理特征，已经开发了与缩醛的反应;这些是使用常规碱性烯醇化物化学难以实现的。
Chiral cationic Pd aqua complexes can function as acid-base catalysts, effectively activating active methylene and methine compounds to give chiral Pd enolates. It is noteworthy that such enolate formation occurs with concomitant formation of a strong protic acid. Although the reactivity of the Pd enolate itself is not sufficient for reactions with carbon-based electrophiles, its cooperative action with the protic acid to activate the electrophiles allows the desired C-C bond-forming reactions to proceed smoothly in a highly enantioselective manner. Based on this mechanistic feature, reactions with acetals have been developed; these are difficult to achieve using conventional basic enolate chemistry.