Reactions of copper(II)-phenol systems with O2: models for TPQ biosynthesis in copper amine oxidases.

Copper(II) complexes supported by a series of phenol-containing bis(pyridin-2-ylmethyl)amine N(3) ligands (denoted as L(o)H, L(m)H, and L(p)H) have been synthesized, and their O(2) reactivity has been examined in detail to gain mechanistic insights into the biosynthesis of the TPQ cofactor (2,4,5-trihydroxyphenylalaninequinone, TOPA quinone) in copper-containing amine oxidases. The copper(II) complex of L(o)H (ortho-phenol derivative) involves a direct phenolate to copper(II) coordination and exhibits almost no reactivity toward O(2) at 60 °C in CH(3)OH. On the other hand, the copper(II) complex of L(m)H (meta-phenol derivative), which does not involve direct coordinative interaction between the phenol moiety and the copper(II) ion, reacts with O(2) in the presence of triethylamine as a base to give a methoxy-substituted para-quinone derivative under the same conditions.

Oxygenation chemistry at a mononuclear copper(II) hydroquinone system with O2.

Aerobic treatment of a copper(II) complex supported by a bis(pyridin-2-ylmethyl)amine ligand containing a p-hydroquinone moiety on one of the pyridine donor groups in CH(3)OH induces oxygenation reaction of the ligand to give a hydroxylated p-quinone derivative.