Enantio- and diastereoselective boron conjugate addition to α-alkyl α,β-unsaturated esters

We developed a copper-catalyzed enantio- and diastereoselective boron conjugate addition to alpha-alkyl alpha,beta-unsaturated esters under base-free conditions. The approach showed excellent enantioselectivities (87-99% ee) and moderate to good conversions (51-99%), albeit with moderate diastereoselectivities (1 : 1-17 : 1 dr). The synthetic utility of this protocol was demonstrated.

Automated summary

We developed a copper-catalyzed enantio- and diastereoselective boron conjugate addition method for α-alkyl α,beta-unsaturated esters under base-free conditions. The approach exhibited excellent enantioselectivities and moderate to good conversions, although with moderate diastereoselectivities. The synthetic utility of this protocol was demonstrated.