An Organocatalytic Asymmetric Friedel鈥揅rafts Addition/Fluorination Sequence: Construction of Oxindole鈥揚yrazolone Conjugates Bearing Vicinal Tetrasubstituted Stereocenters
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- 作者：Xiaoze Bao ; Baomin Wang ; Longchen Cui ; Guodong Zhu ; Yuli He ; Jingping Qu ; Yuming Song
- 刊名：Organic Letters
- 出版年：2015
- 出版时间：November 6, 2015
- 年：2015
- 卷：17
- 期：21
- 页码：5168-5171
- 全文大小：396K
- ISSN：1523-7052
文摘
A highly efficient and practical one-pot sequential process, consisting of an organocatalytic enantioselective Friedel鈥揅rafts-type addition of 4-nonsubstituted pyrazolones to isatin-derived N-Boc ketimines and a subsequent diastereoselective fluorination of the pyrazolone moiety, is developed. This reaction sequence delivers novel oxindole鈥損yrazolone adducts featuring vicinal tetrasubstituted stereocenters with a 0.5 mol % catalyst loading in high yield with excellent enantio- and diastereocontrol. Notably, chloro, bromo, and thioether functionalities can be readily incorporated, rendering a broad diversity of the product.