MnI2-catalyzed Dimerization of 2-Hydroxyanthracene

Dimerization of 2-hydroxyanthracene was investigated with 5mol% of various catalysts that are efficient catalysts for the dimerization of 2-naphthol. Catalysts such as Cu(OH)Cl¢ TMEDA, [Mn(acac)3], and [Mn(acac)2] did not give satisfactory results. However, MnI2, which gave only trace amounts of dimerization product of 2-naphthol under the same conditions, afforded 2,2¤-dihydroxy-1,1¤-bianthracene in 74% yield.