;Chiral sulfoxide cis-2 and trans-2 were synthesized from commercially available 5-bromovalerate through a five-step synthetic route. We demonstrated the application of these chiral sulfoxide catalysts in asymmetric addition of diethylzinc to benzaldehyde and also investigated the promotion of the catalytic process by acid additives. Surprisingly, when we added 50 mol% of 4-methoxybenzoic acid, the yield and enantioselectivity were improved. In addition, the stereochemistry of product changed from S to R, Finally, We also investigated asymmetric addition of diethylzinc to different aromatic aldehydes.
