Cu(i)-catalyzed enantioselective and stereospecific borylative annulation of cyclic 1,3-dione-tethered 1,3-enynes.

A copper(i)-catalyzed, highly enantioselective, and diastereoselective borylative cyclization of prochiral cyclic 1,3-dione-tethered 1,3-enynes is reported. This stereospecific transformation exhibits a broad substrate scope, enabling access to bicyclic organoboron products containing four contiguous stereocenters with excellent enantioselectivity. Notably, the reaction rate is significantly influenced by the substrate's stereochemistry, with the ()-isomer undergoing borylative cyclization much faster than the ()-isomer due to reduced steric interactions during C-C bond formation. Furthermore, treatment of the resulting products with sodium perborate yields the corresponding alcohols without compromising enantiomeric excess.