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Chiral Dicopper Complexes with a Doubly Asymmetric Ligand as Models for the Tyrosinase Active Site: Synthesis, Structure, O 2 ‐Reactivity and Comparison with Their Symmetric Analogs
Author(s) -
Sander Ole,
Näther Christian,
Tuczek Felix
Publication year - 2009
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.200900095
Subject(s) - chemistry , reactivity (psychology) , tyrosinase , ligand (biochemistry) , stereochemistry , active site , benzene , medicinal chemistry , dichloromethane , copper , enzyme , receptor , organic chemistry , biochemistry , medicine , alternative medicine , pathology , solvent
Abstract In order to model the asymmetric active site of the type‐3 copper enzyme tyrosinase the “doubly asymmetric” binucleating ligand 1‐[bis‐ N , N ‐(pyrid‐2‐ylmethyl)aminomethyl]‐3‐[ N ‐(pyrid‐2‐ylmethyl)‐ N ‐(2‐pyrid‐2‐ylethyl)aminomethyl]benzene (“unsDMPA”) is synthesized and coordinated to copper(I). The O 2 ‐reactivity of the Cu I (unsDMPA) complex and its analog derived from the symmetric counterpiece of unsDMPA, DMPA, is investigated. Oxygenation in methanol leads to dicopper(II) bis(μ‐hydroxo) and bis(μ‐methanolato) complexes; the dicopper(II) bis(μ‐hydroxo) complex of the unsDMPA ligand is chiral. Oxygenation in dichloromethane leads to oxidative N ‐dealkylation. This is attributed to a tendency of DMPA and unsDMPA complexes to form dicopper bis(μ‐oxo) intermediates, as evidenced by DFT. The implications of these results with respect to the design of tyrosinase model systems are discussed.