A Highly Efficient Organocatalyst for Direct Aldol Reactions of Ketones with Aldedydes
A Highly Efficient Organocatalyst for Direct Aldol Reactions of Ketones with Aldedydes
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DOI：
10.1021/ja0510156
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发表时间：
2005-06
影响因子：
15
通讯作者：
Zhuo Tang;†. Z. Yang;Xiao‐Hua Chen;L. Cun;A. Mi;Yaozhong Jiang;L. Gong
中科院分区：
文献类型：
--
作者：
Zhuo Tang;†. Z. Yang;Xiao‐Hua Chen;L. Cun;A. Mi;Yaozhong Jiang;L. Gong
制备了衍生自各种手性 β-氨基醇的 L-脯氨酸酰胺，这些手性 β-氨基醇在其立构中心带有各种电子性质的取代基，并评估其催化 4-硝基苯甲醛与丙酮的直接羟醛反应的性能。发现具有强吸电子基团的催化剂比具有给电子基团的类似物表现出更高的催化活性和对映选择性。 2 mol% 催化剂 4g 的存在可显着催化多种醛与丙酮和丁酮的直接羟醛反应，得到具有非常高对映选择性（96% 至 >99% ee）的 β-羟基酮。对于来自环己酮反应的反羟醛产物观察到95/5的高非对映选择性，并且对于来自环戊酮反应的反羟醛产物提供93%ee的优异对映选择性。
L-proline amides derived from various chiral beta-amino alcohols that bear substituents with various electron natures at their stereogenic centers are prepared and evaluated for catalyzing the direct Aldol reaction of 4-nitrobenzaldehyde with acetone. Catalysts with strong electron-withdrawing groups are found to exhibit higher catalytic activity and enantioselectivity than their analogues with electron-donating groups. The presence of 2 mol % catalyst 4g significantly catalyzes the direct Aldol reactions of a wide range of aldehydes with acetone and butanone, to give the beta-hydroxy ketones with very high enantioselectivities ranging from 96% to >99% ee. High diastereoselectivity of 95/5 was observed for the anti Aldol product from the reaction of cyclohexanone, and excellent enantioselectivity of 93% ee was provided for anti Aldol product from the reaction of cyclopentanone.