Amine‐Catalyzed Asymmetric Epoxidation of α,β‐Unsaturated Aldehydes
Amine‐Catalyzed Asymmetric Epoxidation of α,β‐Unsaturated Aldehydes
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DOI：
10.1002/adsc.200600529
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发表时间：
2007-05
影响因子：
5.4
通讯作者：
Gui‐Ling Zhao;I. Ibrahem;Henrik Sundén;A. Córdova
中科院分区：
文献类型：
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作者：
Gui‐Ling Zhao;I. Ibrahem;Henrik Sundén;A. Córdova
研究了不同过氧化物催化的α，β-不饱和醛的直接不对称环氧化反应。脯氨酸、手性吡咯烷衍生物和氨基酸衍生的咪唑烷酮催化α，β-不饱和醛的不对称环氧化。特别地，保护的市售α，α-二苯基-和α，α-二（β-萘基）-2-脯氨醇催化α，β-不饱和醛的不对称环氧化反应，具有高的非对映选择性和对映选择性，以高达97：3 dr和98%ee的高产率提供相应的2-环氧醛。使用无毒催化剂、水和过氧化氢、过氧化脲或过碳酸钠作为氧源可以使该反应对环境友好。此外，一锅直接有机催化的不对称串联环氧化-Wittig反应进行了描述。该反应具有高度的非对映选择性和对映选择性，并提供了一个快速获得2，4-二环氧醛。此外，一个高度立体选择性的一锅有机催化的不对称级联环氧化-曼尼希反应，通过亚胺和烯胺活化的组合进行，提出。对氨基酸和手性吡咯烷催化的α，β-不饱和醛直接不对称环氧化反应的机理和立体化学进行了讨论。
The direct organocatalytic enantioselective epoxidation of α,β-unsaturated aldehydes with different peroxides is presented. Proline, chiral pyrrolidine derivatives, and amino acid-derived imidazolidinones catalyze the asymmetric epoxidation of α,β-unsaturated aldehydes. In particular, protected commercially available α,α-diphenyl- and α,α-di(β-naphthyl)-2-prolinols catalyze the asymmetric epoxidation reactions of α,β-unsaturated aldehydes with high diastereo- and enantioselectivities to furnish the corresponding 2-epoxy aldehydes in high yield with up to 97:3 dr and 98 % ee. The use of non-toxic catalysts, water and hydrogen peroxide, urea hydroperoxide or sodium percarbonate as the oxygen sources could make this reaction environmentally benign. In addition, one-pot direct organocatalytic asymmetric tandem epoxidation-Wittig reactions are described. The reactions were highly diastereo- and enantioselective and provide a rapid access to 2,4-diepoxy aldehydes. Moreover, a highly stereoselective one-pot organocatalytic asymmetric cascade epoxidation-Mannich reaction, which proceeds via the combination of iminium and enamine activation, is presented. The mechanism and stereochemistry of the amino acid- and chiral pyrrolidine-catalyzed direct asymmetric epoxidation of α,β-unsaturated aldehydes are also discussed.