Journal of the American Chemical Society, Vol.141, No.13, 5135-5138, 2019
Enantioselective Copper Catalyzed Alkyne - Azide Cycloaddition by Dynamic Kinetic Resolution
The copper(I) catalyzed alkyne-azide cycloaddition (CuAAC), a click reaction, is one of the most powerful catalytic reactions developed during the last two decades. Conducting CuAAC enantioselectively would add a third dimension to this reaction and would enable the direct synthesis of alpha-chiral triazoles. Doing so is demanding because the two precursors have linear geometries, and the triazole product is a flat heterocycle. Designing a chiral catalyst is further complicated by the complex mechanism of CuAAC. We report an enantioselective CuAAC (E-CuAAC), enabled by dynamic kinetic resolution (DKR). The E-CuAAC is high yielding and affords up to 99:1 er. The E-CuAAC can directly generate alpha-chiral triazoles in a complex molecular environment.