Novel vanadium catalyst system with tartaric acid salts for highly selective asymmetric oxidative coupling polymerization

The asymmetric oxidative coupling polymerization (AOCP) of 2,3-dihydroxynaphthalene (DHN) with a novel catalyst system, oxovanadium(IV) stearate in the presence of the sodium or lithium salt of tartaric acid, under an O2 atmosphere was carried out. For example, the polymerization with a catalytic amount of the d-(−)-tartaric acid disodium salt in THF at room temperature for 48 h followed by acetylation of the hydroxyl groups gave a methanol-insoluble polymer in a 40% yield, which showed the highest specific rotation value ([α]D) of −223 among the polymers so far obtained by the AOCP of DHN. The enantioselectivity during the polymerization was estimated to be an 88% enantiomeric exess (S).