L. Casella, E. Monzani, M. Gullotti
Dec 18, 1996
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Inorganic Chemistry
Abstract
The copper-mediated oxygenation of methyl 4-hydroxybenzoate (1) in acetonitrile has been investigated by employing a series of dinuclear copper(I) complexes with polybenzimidazole ligands. The reaction mimics the activity of the copper enzyme tyrosinase, since the initial product of the reaction is the o-catechol, methyl 3,4-dihydroxybenzoate (2). The ligand systems investigated include α,α‘-bis{bis[2-(1-methyl-2-benzimidazolyl)ethyl]amino}-m-xylene (L-66) α,α‘-bis{bis[2-(1-methyl-2-benzimidazolyl)methyl]amino}-m-xylene (L-55), α,α‘-bis{[(1-methyl-2-benzimidazolyl)methyl][2-(1-methyl-2-benzimidazolyl)ethyl]amino}-m-xylene (L-56), and α,α‘-bis{[(2-pyridyl)methyl][2-(1-methyl-2-benzimidazolyl)ethyl]amino}-m-xylene (L-5p6). The most effective among the dicopper(I) complexes is that derived from L-66, while its mononuclear Cu(I) analogue, with the ligand N,N-bis[2-(1-methyl-2-benzimidazolyl)ethyl]amine is inactive in the monooxygenase reaction. The catechol 2 is the only product of phenol hydroxylation when t...