Copper-Catalyzed Diastereoselective and Enantioselective Addition of 1,1-Diborylalkanes to Cyclic Ketimines and α‑Imino Esters

We report broadly applicable copper catalytic conditions for the diastereoselective and enantioselective 1,2-addition of 1,1-diborylalkanes to cyclic ketimines and α-imino esters. The developed method provides various β-aminoboronate esters bearing adjacent stereocenters with high diastereo- and enantioselectivity. Synthetic applications for converting the obtained β-aminoboronate esters to a diverse array of synthetically useful chiral compounds are demonstrated.