Catecholamine-protein conjugates: Isolation of 4-phenylphenoxazin-2-ones from oxidative coupling of N-acetyldopamine with aliphatic amino acids

Article abstract of DOI:10.1016/S0040-4020(01)81991-8

4-Phenylphenoxazinones 4 were isolated after biomimetic oxidation, using diphenoloxidases of insect cuticle, mushroom tyrosinase, or after autoxidation of N-acetyldopamine (1) in the presence of β-alanine, β-alanine methyl ester or N-acetyl-L-lysine. They are formed presumably by addition of 2-aminoalkyl-5-alkylphenols 2 to the o-quinone of biphenyltetrol 3 which, in turn, arises from oxidative coupling of 1. The structures of 4 present the first examples for the assembly of reasonably stable intermediates in the rather complex process of chemical modifications of aliphatic amino acid residues by o-quinones.