Enantioselective protonation catalyzed by a chiral bicyclic guanidine derivative
Enantioselective protonation catalyzed by a chiral bicyclic guanidine derivative
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DOI：
10.1002/anie.200801378
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发表时间：
2008-01-01
影响因子：
16.6
通讯作者：
Tan, Choon-Hong
中科院分区：
文献类型：
--
作者：
Leow, Dasheng;Lin, Shishi;Tan, Choon-Hong
烯醇酸酯的对映选择性质子化是制备具有立体中心的手性羰基化合物的一种概念上简单而有效的方法电负性原子之间的质子交换速率往往很快，这使得区分非对映体过渡态变得困难。此外，E和Z烯醇化物将表现出不同的对映面选择性。大多数这样的反应是用预先形成的烯醇酸酯和化学计量量的手性质子源进行的。[1,2]几种策略被用于催化对映选择性质子化。[1,3]一种特别吸引人的方法是通过共轭加成反应生成瞬态烯酸酯[4]，[5]随后是原位对映选择性质子化（方案1）。质子化可以发生在催化剂-烯醇酸离子对中，也可以发生在酸性更强的非手性质子源中，网址：NuÀH。
The enantioselective protonation of enolates is a conceptually simple and efficient approach to the preparation of chiral carbonyl compounds with an a stereogenic center.[1] The rate of proton exchange between electronegative atoms is often rapid, which makes discrimination between diastereomeric transition states difficult. Furthermore, E and Z enolates will exhibit different enantiofacial selectivities. The majority of such reactions have been conducted with preformed enolates and a stoichiometric amount of a chiral proton source.[1, 2] Several strategies have been employed for catalytic enantioselective protonation.[1, 3] One particularly attractive method is the generation of a transient enolate [4] through a conjugate addition reaction,[5] followed by an in situ enantioselective protonation (Scheme 1). The protonation can occur within the catalyst–enolate ion pair or from a more acidic, achiral proton source, NuÀH.