Kinetic Resolution of N-Allylic Pyrazoles via Photoexcited Chiral Copper Complex-Catalyzed Alkene E → Z Isomerization

Herein, we present an efficient and practical kinetic resolution (KR) of racemic allylic pyrazoles utilizing photoexcited chiral-copper-complex-mediated alkene E → Z isomerization. This method enables the synthesis of both enantioenriched E- and Z-allylic pyrazoles, achieving enantiomeric excesses (e.e.) of up to 97% and selectivity factors (S factors) as high as 217. Remarkably, the method's ability to furnish allylic pyrazoles with the Z-configuration, which is notably arduous to obtain under thermodynamic control, underscores the transformative potential of this synthetic protocol.