W-Phos Ligand Enables Copper-Catalyzed Enantioselective Alkylation of N-Sulfonyl Ketimines with Grignard Reagents

Catalytic asymmetric addition of reactive Grignard reagents to ketimines poses a considerable challenge. Herein, a PNP-type W-Phos ligand developed recently by our group showed a unique effect toward this end, paving the way to a Cu(I)-catalyzed asymmetric alkylation reaction of N-sulfonyl ketimines, delivering optically active α-tertiary amines in high enantioselectivities. This catalytic protocol shows an unprecedented substrate scope with more than 80 examples, not only compatible with benzo five- and six-membered cyclic N-sulfonyl ketimines but also suitable for geometrically unstable (E or Z) acyclic N-sulfonyl ketimines. The application potential of the protocol is featured by the extensive presence of α-tertiary amines in natural products and pharmaceutical compounds and also demonstrated by downstream transformations with maintenance of the enantioselectivity.