Highly enantioselective addition of aliphatic aldehydes to 2-hydroxychalcone enabled by cooperative organocatalysts
Jiadong Hu1, Yu-Qi Gao, Dongyang Xu
1Shaanxi Key Laboratory of Natural Products & Chemical Biology, College of Chemistry & Pharmacy, Northwest A&F University, 22 Xinong Road, Yangling 712100, Shaanxi, China. xiewq@nwafu.edu.cn.
Abstract:
Herein, we developed an enantioselective addition of aliphatic aldehydes to 2-hydroxychalcone promoted by cooperative organocatalysts, giving access to hybrid flavonoids in excellent enantioselectivities. This reaction took advantage of cycloisomerization of 2-hydroxychalcone to form a transient flavylium under the irradiation of 24 W CFL, which was trapped by the in situ generated chiral enamine intermediate. The synergistic action of chiral phosphoric acid secured the excellent outcome of this reaction by ion-pairing with the transient flavylium.
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