Stereoselective Divergent Synthesis of Chiral Pyrazolone Derivatives via Multicomponent Cascade Reactions by
Xin Liu1, Siyi Chen1, Jun Huang1
1Strait Institute of Flexible Electronics (SIFE, Future Technologies), Fujian Key Laboratory of Flexible Electronics, Fujian Normal University and Strait Laboratory of Flexible Electronics (SLoFE), Fuzhou 350117, China.
Abstract:
Isothiourea-catalyzed multicomponent cascade reactions are challenging due to the existence of competitive side reactions between multiple reaction partners and intermediates. Herein, we report a practical and efficient protocol for the stereoselective divergent synthesis of pyrazolone-derived β-amino acid esters and β-lactams by isothiourea catalysis. Two distinct reaction pathways are identified, which are controlled by esterification or lactamization of the zwitterionic intermediate. The strategy is attractive because of the convenient one-step procedure, mild conditions, high stereoselectivity, and good functional-group tolerance.
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