Enantioselective Palladium/Copper-Catalyzed C-C Bond Activation Synergized with Sonogashira-Type C(sp3)-C(sp) Cross-Coupling Alkynylation

The Sonogashira-type cross-coupling reaction is one of the most significant alkynylation transformations in organic chemistry. However, highly enantioselective alkynylation via Sonogashira-type cross-coupling reaction is rather limited, mainly due to the difficulties in matching the stereoselective induction of chiral ligand with the combinational behavior of Pd/Cu-based bimetallic catalysis. We report here a novel enantioselective palladium/copper-catalyzed alkyl alkynylation of cyclobutanones with terminal alkynes via tandem C-C bond activation/Sonogashira-type cross coupling reaction, in which a novel chiral TADDOL-derived phosphoramidite ligand bearing fluorine and silicon-based bulky groups that simplified as FSi-Phos is found to be an efficient ligand for both C(sp2)-C(sp3) bond cleavage and new C(sp3)-C(sp) bond formation. A wide range of chiral alkynylated indanones bearing an all-carbon quaternary stereocenter are provided efficiently with up to 97.5:2.5 er.