Copper-Catalyzed Remote Enantioselective [4 + 1] Cyclization of Yne-Vinyl Allylic Esters with Cyclic 1,3-Dicarbonyl Compounds Enables Access to Spirocyclic Ketones.

Efficient approaches for asymmetric propargylic substitution via copper-allenylidene intermediates have been elegantly developed; however, the asymmetric transformations of metal vinyl-allenylidenes remain relatively underexplored. Here, we describe an efficient, copper-catalyzed, remote enantioselective [4 + 1] annulation of yne-vinyl allylic esters with cyclic 1,3-dicarbonyl compounds. This reaction proceeds via a copper divinyl-allenylidene complex, affording a series of chiral spirocyclic compounds in high yields with excellent enantioselectivity.