Enantioselective [4+1] Annulation Reactions of alpha-Substituted Ammonium Ylides To Construct Spirocyclic Oxindoles
Enantioselective [4+1] Annulation Reactions of alpha-Substituted Ammonium Ylides To Construct Spirocyclic Oxindoles
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α-取代铵叶立德的对映选择性 [4 1] 成环反应构建螺环羟吲哚
DOI：
10.1021/jacs.5b04792
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发表时间：
2015
影响因子：
15
通讯作者：
Chen Ying-Chun
中科院分区：
文献类型：
--
作者：
Zheng Peng-Fei;Ouyang Qin;Niu Sheng-Li;Shuai Li;Yuan Yi;Jiang Kun;Liu Tian-Yu;Chen Ying-Chun
铵叶立德在有机合成中有着悠久的历史，但与磷叶立德和硫叶立德相比，铵叶立德在不对称催化中的应用无论是底物范围还是反应途径都还不成熟。本文报道了3-溴羟吲哚与缺电子1-氮二烯的不对称[4 + 1]成环反应，该反应是通过一种新设计的2′-甲基α-异铜灵（α-MeIC）的叶立德铵催化，以良好的对映选择性（高达99%ee）有效地合成了含二氢吡咯基序的螺环羟吲哚化合物.据我们所知，该工作代表了含α-取代的铵叶立德的不对称催化的第一个例子，并且铵叶立德的催化[4 + 1]成环途径也是前所未有的。此外，1H NMR，质谱，和计算计算研究进行，催化循环和对映选择性机制的初步解释已成功阐明。
Ammonium ylides have a long history in organic synthesis, but their application in asymmetric catalysis is still underdeveloped in regard to both substrate scope and reaction pathways compared with phosphorus and sulfur ylides. Here a previously unreported asymmetric [4 + 1] annulation reaction of 3-bromooxindoles and electron-deficient 1-azadienes has been developed through ammonium ylide catalysis of a newly designed 2′-methyl α-isocupreine (α-MeIC), efficiently delivering spirocyclic oxindole compounds incorporating a dihydropyrrole motif in excellent enantioselectivity (up to 99% ee). To the best of our knowledge, this work represents the first example of asymmetric catalysis of ammonium ylides bearing α-substitutions, and the catalytic [4 + 1] annulation pathway of ammonium ylides is also unprecedented. Moreover,1H NMR, mass spectroscopy, and computational calculation studies were conducted, and the catalytic cycle and a tentative explanation of the enantioselective mechanism have been successfully elucidated.