syntheses of two opticallyactive (buta-1,3-dien-2-yl)(salen)Co complexes are reported. These dienyl complexes undergo Diels−Alder reactions with high enantioselectivity with a variety of dienophiles. One of the (salen)Co-substituted Diels−Alder cycloadducts was characterized by X-ray crystallography. A highlight of this chemistry is that the Diels−Alder cycloadduct containingcobaltcomplexes were cleanly