Monooxygenation of aromatic compounds by dioxygen with bioinspired systems using non-heme iron catalysts and tetrahydropterins: comparison with other reducing agents and interesting regioselectivity favouring meta-hydroxylation

Monooxygenation of aromatic compounds by dioxygen in the presence of catalytic amounts of an iron(II) salt and tetrahydropterins as reducing agents occurs with a regioselectivity favouring meta-hydroxylation of arenes bearing an electron-donating substituent, such as anisole, phenetole, toluene, and ethylbenzene. Comparison of similar systems using various reducing agents showed that only tetrahydropterins and ascorbate led to such a major meta-hydroxylation. The tetrahydropterin- and ascorbate-dependent systems should be useful for the preparation of meta-hydroxylated metabolites of aromatic drugs, as shown here in the case of diclofenac.