Enantioselective Copper‐Catalyzed Decarboxylative Propargylic Alkylation of Propargyl β‐Ketoesters with a Chiral Ketimine P,N,N‐Ligand

The first enantioselective copper-catalyzed decarboxylative propargylic alkylation has been developed. Treatment of propargyl β-ketoesters with a catalyst, prepared in situ from [Cu(CH3 CN)4 BF4 ] and a newly developed chiral tridentate ketimine P,N,N-ligand under mild reaction conditions, generates β-ethynyl ketones in good yields and with high enantioselectivities without requiring the pregeneration of ketone enolates. This new process provides facile access to a range of chiral β-ethynyl ketones in a highly enantioenriched form.