Organocatalytic Asymmetric Synthesis of Dihydrobenzoxazinones Bearing Trifluoromethylated Quaternary Stereocenters
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- 作者：Hengqiao Lou ; Yongtao Wang ; Enze Jin ; Xufeng Lin
- 刊名：Journal of Organic Chemistry
- 出版年：2016
- 出版时间：March 4, 2016
- 年：2016
- 卷：81
- 期：5
- 页码：2019-2026
- 全文大小：588K
- ISSN：1520-6904
文摘
Chiral phosphoric acid-catalyzed enantioselective aza-Friedel–Crafts reaction of trifluoromethyl benzoxazinones with pyrroles is reported. Under mild conditions, a range of enantioenriched dihydrobenzoxazinones bearing trifluoromethylated quaternary stereocenters could be obtained in good to excellent yield and ee. A remarkable fluorine effect is observed, and preliminary mechanistic studies combined with theory calculations suggest that triple-hydrogen-bonding interactions hold the transition structure rigidly and allow the bulky substituents of the catalyst to influence the enantioselectivity.