Axially chiral styrene-based organocatalysts and their application in asymmetric cascade Michael/cyclization reaction
Hao Yu, Zi-Hao Li, Zhi‐Gang Ma, Ruxin Liu, Rui-Tian Ge, Quan‐Zhe Li, Tong‐Mei Ding, Shu‐Yu Zhang
Abstract
An axially chiral styrene-based organocatalyst, featuring a combination of axially chiral styrene-based structure and a pyrrole ring, has been designed and synthesized. This catalyst demonstrates remarkable capabilities in producing a wide range of densely substituted spirooxindoles that feature an alkyne-substituted quaternary stereogenic center. These spirooxindoles are generated through mild cascade Michael/cyclization reactions, resulting in high conversion rates and exceptional enantioselectivity. Our catalytic model, based on experiments, X-ray structure analysis and DFT calculations suggests that chiral matched π-π interactions and multiple H-bonds between the organocatalyst and substrates play significant roles in controlling the stereoselectivity of the reaction.