Enantioselective Copper-Catalyzed Alkynylation of Quinolones Using Chiral P,N Ligands.

Herein we report a catalytic enantioselective alkynylation of quinolones. In this reaction, quinolones are silylated to form a quinolinium ion which then undergoes an enantioselective attack by a copper acetylide, templated by (S,S,Ra)-UCD-Phim. This gives alkynylated products (24 examples) in yields of up to 92% and enantioselectivities of up to 97%. This methodology has been applied to the synthesis of two natural products, (+)-cuspareine and (+)-galipinine.