Copper-catalyzed asymmetric [4 + 1] annulation of yne-allylic esters with pyrazolones

An enantioselective catalytic method for the direct [4 + 1] annulation of yne-allylic acetates with pyrazolones has been realized by a copper-catalyzed remote strategy. A variety of enantioenriched spiropyrazolones are rapidly accessed in high yields with moderate to good enantiocontrol. The facile follow-up transformations highlight its potential utility in the synthesis of diverse spiropyrazolones building blocks.