Chiral N-cyclopropyl pyrazoles and structurally related heterocycles are prepared using an earth-abundant copper catalyst under mild reaction conditions with high regio-, diastereo-, and enantiocontrol. The observed N2:N1 regioselectivity favors the more hindered nitrogen of the pyrazole. Experimental and DFT studies support a unique mechanism that features a five-centered aminocupration.

We describe a copper catalyst that promotes the addition of phosphines to cyclopropenes at ambient temperature. A range of cyclopropylphosphines bearing different steric and electronic properties can now be accessed in high yields and enantioselectivities. Enrichment of phosphorus stereocenters is also demonstrated via a Dynamic Kinetic Asymmetric Transformation (DyKAT) process. A combined experimental and theoretical mechanistic study supports an elementary step featuring insertion of a CuI -phosphido into a carbon-carbon double bond. Density functional theory calculations reveal migratory insertion as the rate- and stereo-determining step, followed by a syn-protodemetalation.