Copper-Catalyzed Asymmetric Protoboration of β-Amidoacrylonitriles and β-Amidoacrylate Esters: An Efficient Approach to Functionalized Chiral α-Amino Boronate Esters.

A copper-catalyzed asymmetric protoboration of both Z-β-amidoacrylonitriles and ethyl E-β-amidoacrylates using bis(pinacolato)diboron has been developed for the first time. The process tolerates a vast array of substrates, delivering a series of stable functionalized chiral α-amino boronate esters in good yields and enantioselectivities under mild reaction conditions. The current method is also applicable for gram-scale synthesis without erosion of enantioselectivity. This work provides an attractive and complementary approach to synthesizing enantioriched chiral α-amino boronate esters.