Unraveling and Manipulating the Stereospecific Retro-Aldol Reaction in the Organocatalytic Asymmetric Aldol Reaction of Isatin and Cyclohexanone
Unraveling and Manipulating the Stereospecific Retro-Aldol Reaction in the Organocatalytic Asymmetric Aldol Reaction of Isatin and Cyclohexanone
复制标题
靛红和环己酮有机催化不对称羟醛反应中立体特异性逆羟醛反应的揭示和操控
DOI：
10.1021/acs.orglett.8b03292
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发表时间：
2018
期刊：
影响因子：
5.2
通讯作者：
Yang Hua
中科院分区：
文献类型：
--
作者：
Wang Jing;Deng Zhi Xiong;Wang Chao Ming;Xia Peng Ju;Xiao Jun An;Xiang Hao Yue;Chen Xiao Qing;Yang Hua
设计了一种基于焦谷氨酸的双功能有机催化剂，并将其应用于靛红与环己酮的不对称直接羟醛缩合反应中，发现了对映体过量的羟醛加成物的侵蚀现象.通过密切监测反应和进行广泛的对照实验，确定ee的侵蚀归因于罕见的立体定向逆羟醛过程。此外，通过调整起始原料的使用，最终实现了对逆向醛醇缩合过程的有效操纵，从而明显提高了对映体选择性和官能团耐受性。研究了不对称转化反应中隐藏的反应途径对不对称转化反应对映体选择性的影响。
Anl-pyroglutamic acid-derived bifunctional organocatalyst was designed and applied in an organocatalytic asymmetric direct aldol reaction between isatins and cyclohexanone, in which an erosion of enantiomeric excess of aldol adduct was unexpectedly observed. Through closely monitoring the reaction and performing extensive control experiments, it was determined that the erosion of ee was attributed to a rare stereospecific retro-aldol process. Moreover, effective manipulation of the retro-aldol process by tuning the use of starting materials was ultimately accomplished, leading to evidently upgraded enantioselectivity and functional group tolerance. This study demonstrates the impact of the hidden reaction pathway on the enantioselectivity in asymmetric transformation.