Copper-Phosphido Catalysis: Enantioselective Addition of Phosphines to Cyclopropenes

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. A combined experimental and theoretical mechanistic study supports insertion of a Cu(I)-phosphido intermediate into the strained olefin. Density functional theory calculations reveal migratory insertion as the stereodetermining step of the pathway, with final product formation occurring via a syn-protodemetalation. Enrichment of phosphorus stereocenters is demonstrated via a DyKAT process.