Chiral-Boron Complex-Catalyzed Asymmetric [3 + 2] Cycloaddition of 2'-Hydroxychalcones with
Guo-Li Chai1, Xiao Wang1, Wei-Yu Huang1
1State Key Laboratory of Antiviral Drugs, Pingyuan Laboratory, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007, China.
Abstract:
A highly efficient asymmetric [3 + 2] cycloaddition reaction of 2'-hydroxychalcones with N-2,2,2-trifluoroethylisatin ketimines catalyzed by a (R)-3,3'-I2-BINOL-boron complex was developed. A broad range of 3,2'-pyrrolidinyl spirooxindole derivatives bearing a CF3-substituted pyrrolidine moiety with four contiguous stereocenters was prepared in high yields with excellent diastereo- and enantioselectivities (up to >20:1 dr and >99% ee). This protocol had the characteristics of mild reaction conditions, high efficiency, and excellent stereocontrol.
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