Diastereo- and Enantioselective Synthesis of Spiro-Pyrrolidine-Pyrazolones by Squaramide-Catalyzed Cascade Aza-Michael/Michael Reactions
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- 作者：Jun-Hua Li ; Hongliang Wen ; Lei Liu and Da-Ming Du
- 刊名：European Journal of Organic Chemistry
- 出版年：2016
- 出版时间：May 2016
- 年：2016
- 卷：2016
- 期：14
- 页码：2492-2499
- 全文大小：1229K
- ISSN：1099-0690
文摘
A new method was developed to rapidly generate a series of spiro-pyrrolidine-pyrazolones by using a squaramide-catalyzed cascade aza-Michael/Michael addition of either tosylaminomethyl enones or enoates to unsaturated pyrazolones. This tandem reaction sequence proceeded well by using 5 mol-% of a chiral bifunctional tertiary amine squaramide catalyst to afford the desired products in good to excellent yields (up to 98 %) with excellent diastereoselectivities [up to >20:1 diastereomeric ratio (dr)] and high to excellent enantioselectivities (up to 98 % ee).