A BIOMIMETIC OXIDIZING SYSTEM CU2-ASCORB IC ACID-O-2 - ITS DISTINCTIVE HYDROXYLATION ACTIVITY OF AROMATIC-COMPOUNDS, REACTION-MECHANISM, AND APPLICATION TO THE SYNTHESIS OF NEW BIOACTIVE MOLECULES()

A biomimetic oxidizing system ''Cu2+-ascorbic acid-O-2'' was effective for selective conversion of o-alkoxyphenols into oxido-labile catecho ls. First direct preparation of 3-hydroxycoumarins from coumarins was achieved by using this system. The oxidizing system hydroxylated pheno ls to afford catechols and hydroquinones. An unusual substituent effec t was observed on this hydroxylation of phenols. Some of the derived c atechols and 3-hydroxycoumarins exhibited much greater bio-activities than those of the mother compounds. Mechanistic investigation has reve aled that catechols were formed via ipso-substitution of alkoxy groups of o-alkoxyphenols for hydroxy group.