Copper(I)-Catalyzed Enantioselective 1,6-Borylation of α,β,γ,δ-Unsaturated Phosphonates

Copper­(I)-catalyzed asymmetric 1,6-borylation of 1,3-dienylphosphonates was achieved using (S,S)-Ph-BPE as a chiral ligand. Regio-, stereo-, and enantioselective borylation successfully proceeded to afford phosphonate-containing allylboronates, with high enantioselectivity up to 97% ee. Further applications of the resulting products generated a valuable phosphonate analogue of γ-butyrolactone