Design of an axially chiral amino acid with a binaphthyl backbone as an organocatalyst for a direct asymmetric aldol reaction
Design of an axially chiral amino acid with a binaphthyl backbone as an organocatalyst for a direct asymmetric aldol reaction
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DOI：
10.1002/anie.200500408
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发表时间：
2005-01-01
影响因子：
16.6
通讯作者：
Maruoka, K
中科院分区：
文献类型：
--
作者：
Kano, T;Takai, J;Maruoka, K
直接催化的不对称Aldol反应是有机合成中最基本的反应之一，近年来发展了几种利用手性金属催化剂[1]和有机催化剂[2-4]进行该反应的有效不对称方法，其中脯氨酸[2，3]及其衍生物[4]的催化作用已被广泛探索。然而，这些脯氨酸催化的羟醛缩合反应的反应性和选择性有严重的限制，因为在结构上修饰脯氨酸的困难。此外，在醛与丙酮的直接羟醛缩合反应中，亚化学计量量的脯氨酸通常是实现合理产率所必需的。此外，已知脯氨酸与缺电子芳族醛反应形成亚胺鎓盐，其甚至在室温下进行脱羧。[5]这种降解可能会导致脯氨酸催化的羟醛缩合反应的显着延迟。在这种情况下，我们感兴趣的是设计一种人工氨基酸催化剂1，其不会通过脱羧而发生不期望的降解。
The direct catalytic asymmetric aldol reaction is one of the most fundamental transformations in organic synthesis, and several efficient asymmetric methodologies for this reaction using chiral metal catalysts [1] and organocatalysts [2–4] have recently been developed, of which catalysis by proline [2, 3] and its derivatives [4] have been extensively explored. However, the reactivity and selectivity of some of these prolinecatalyzed aldol reactions have serious limitations because of the difficulty in structurally modifying proline. Furthermore, a substoichiometric amount of proline is often necessary to achieve reasonable yields in the direct aldol reaction of aldehydes with acetone. Also, proline is known to react with electron-deficient aromatic aldehydes to form iminium salts, which undergo decarboxylation, even at room temperature.[5] Such degradation may induce the significant retardation of the proline-catalyzed aldol reactions. In this context, we were interested in designing an artificial amino acid catalyst 1 that would not undergo undesirable degradation through decar-