Cu( <scp>i</scp> )-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 (<i>Z</i>)-isomer undergoing borylative cyclization much faster than the (<i>E</i>)-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.