Copper-catalyzed enantioselective alkynylation of pyrazole-4,5-diones with terminal alkynes.

A copper-catalyzed enantioselective alkynylation between terminal alkynes and pyrazole-4,5-diones has been developed. With 2.5 mol% CuI and 3 mol% chiral ligand L15, chiral propargylic alcohols bearing a pyrazolone motif were produced in 82-99% yield and up to 98% ee. Moreover, both enantiomers of the chiral propargylic alcohols were obtained with ligands L12 and L15, respectively.