Copper-catalyzed Hydroamination: Enantioselective Addition of Pyrazoles to Cyclopropenes

Abstract

Hydroamination of cyclopropenes presents an appealing approach to increase molecular complexity. In this study we explore an earth-abundant copper-catalyzed hydroamination of cyclopropenes with pyrazoles and structurally related heterocycles under mild conditions with high regio-, diastereo-, and enantiocontrol. The observed regioselectivity favors the more hindered nitrogen of the pyrazole. Experimental and DFT studies support a unique mechanism featuring a five-centered aminocupration.