Copper-Catalyzed Hydroamination: Enantioselective Addition of Pyrazoles to Cyclopropenes

摘要

Chiral N-cyclopropyl pyrazoles and structurallyrelated heterocycles are prepared using an earth-abundant copper catalystunder mild reaction conditions with high regio-, diastereo-, and enantiocontrol.The observed N-2:N-1 regioselectivity favors themore hindered nitrogen of the pyrazole. Experimental and DFT studiessupport a unique mechanism that features a five-centered aminocupration.