A Highly Enantioselective Route to Either Enantiomer of Both α- and β-Amino Acid Derivatives
作者:Armando Córdova、Shin-ichi Watanabe、Fujie Tanaka、Wolfgang Notz、Carlos F. Barbas
DOI:10.1021/ja017833p
日期:2002.3.1
α-amino acids and derivatives in high yield and stereoselectivity. Six of the seven aldehydes studied yielded products with ee values of 99% or greater. The diastereoselectivity of the reaction increased with the bulkiness of the substituents of the aldehyde donor in the order R = Me < Et < i-Pr < n-Pent. In five of the cases studied, excellent syn stereoselectivities were achieved. In addition, the corresponding
这份报告描述了在催化不对称曼尼希型反应中前所未有地使用未改性的醛作为供体。N-PMP 保护的 α-亚氨基乙醛酸乙酯与未修饰的脂肪醛的脯氨酸催化反应提供了一种通用且非常温和的进入 β-氨基和 α-氨基酸的对映异构体及其衍生物的高产率和立体选择性。研究的七种醛中的六种产生的产品 ee 值为 99% 或更高。反应的非对映选择性随着醛供体取代基的体积增加而增加,顺序为 R = Me < Et < i-Pr < n-Pent。在研究的五个案例中,实现了出色的顺式立体选择性。此外,相应的手性 β-氨基醛加合物可以很容易地转化为相应的氨基酸衍生物。最重要的是,
A Solid-Supported Organocatalyst for Highly Stereoselective, Batch, and Continuous-Flow Mannich Reactions
作者:Esther Alza、Carles Rodríguez-Escrich、Sonia Sayalero、Amaia Bastero、Miquel A. Pericàs
DOI:10.1002/chem.200901310
日期:2009.10.5
fast reactions leading to complete conversion in 1–3 h are recorded in DMF. With ketone donors, the reactions tend to be slower, but can be efficiently accelerated (six‐membered ring cycloalkanones) by low‐power microwave irradiation. This approach, which greatly facilitates product isolation since the catalyst is removed by simple filtration, has allowed the implementation of the reactions of aldehyde
据报道,在(2 S,4 R)-羟基脯氨酸官能化的聚苯乙烯树脂的催化下,醛和酮与N-(对-甲氧基苯基)乙醛酸乙酯亚胺的快速,高度立体选择性曼尼希反应。已经研究了脯氨酸与聚合物主链连接的接头性质的影响,并且由叠氮基甲基聚苯乙烯和O构成了1,2,3-三唑接头事实证明,炔丙基羟基脯氨酸是催化活性和对映选择性的最佳选择。对于醛供体,在DMF中记录了可在1-3小时内完成完全转化的快速反应。使用酮供体,反应往往较慢,但可以通过低功率微波辐射有效地加速(六元环环烷酮)。这种方法极大地促进了产物的分离,因为通过简单的过滤就可以除去催化剂,从而可以在连续流,单程系统中实施醛底物的反应。以这种方式,连续合成对映体和非对映体纯加合物(syn / anti > 97:3; ee在室温下,停留时间为6.0分钟,已达到> 99%)。该方法通过大大简化的实验规程避免了纯化步骤,从而通过使用0.46 mmol的催化树脂(5