Chiral N,N′-dioxide-iron(II) complexes catalyzed enantioselective oxa-Michael addition of α,β-unsaturated aldehydes

The enantioselective oxa-Michael addition reaction of 1-(4-methoxyphenyl) ethanone oxime to various α,β-unsaturated aldehydes was accomplished by using chiral N,N′-dioxide-FeSO4·7H2O (1:1) complex. Aromatic acid was employed as additive to increase the yield of the reaction. The corresponding adducts were obtained in moderate yields with up to 76% ee under mild conditions.