Copper-catalyzed enantioselective conjugate addition of dialkylzinc reagents to (2-pyridyl)sulfonyl imines of chalcones.
[reaction: see text] The enantioselective catalytic 1,4-addition to alpha,beta-unsaturated ketimines is an unprecedented process. Herein, we document the copper-catalyzed addition of dialkylzinc reagents to (2-pyridylsulfonyl)imines of chalcones. This process occurs rapidly in the presence of a chiral phosphoramidite ligand to afford exclusively the 1,4-addition product. In the case of addition of dimethylzinc, enantioselectivities in the range 70-80% ee are obtained. The presence of the metal-coordinating 2-pyridylsulfonyl group proved to be essential for this reaction to proceed.
Esquivias
Jorge
J
Departamento de Química Orgánica, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.
Arrayás
Ramon Gómez
RG
Carretero
Juan C
JC