Katarzyna Grubel - Influence of water on the formation of O2-reactive divalent metal enolate complexes of relevance to acireductone dioxygenases

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      Publication Details (including relevant citation   information):

      Katarzyna Grubel, Gajendrasingh K. Ingle, Amy L. Fuller, Atta M.   Arif and Lisa M. Berreau Dalton Transactions  2011, Advance Article; DOI: 10.1039/C1DT10587F

      Abstract:

      Reaction conditions were evaluated for the preparation of   [(6-PhTPA)Ni(PhC(O)C(OH)C(O)Ph)]ClO4  (3) and   [(6-Ph2TPA)Co(PhC(O)C(OH)C(O)Ph)]ClO4  (7), two complexes of structural relevance to the   enzyme/substrate (ES) adduct in Ni(II)- and   Co(II)-containing forms of acireductone   dioxygenase. The presence of water in reactions directed at the   preparation of 3 and 7 was found to result in isomerization of   the enolate precursor 2-hydroxy-1,3-diphenylpropane-1,3-dione to   give the ester 2-oxo-2-phenylethylbenzoate. Performing synthetic   procedures under dryer conditions reduced the amount of ester   production and enabled the isolation of 3 in high yield. This   complex was comprehensively characterized, including by X-ray   crystallography. Using similar conditions for the   6-Ph2TPACo-containing system, the   amount of ester generated was only modestly affected, but the   formation of a benzoate complex   ([(6-Ph2TPA)Co(O2CPh)]ClO4,   10) resulting from ester hydrolysis was prevented. The best   preparation of 7 was found to involve dry conditions and short   reaction times. The approach outlined herein toward determining   appropriate reaction conditions for the preparation of 3 and 7   involved the preparation and characterization of several   air-stable (6-PhTPA)Ni- and   (6-Ph2TPA)Co-containing analog   complexes having enolate, solvent, and benzoate ligands. These   complexes were used as paramagnetic 1H   NMR standards for evaluation of reaction mixtures containing 3   and 7.

     
     
     
        Graphical abstract: Influence of water on the formation of O2-reactive divalent metal enolate complexes of relevance to acireductone dioxygenases 

      Address (URL): http://pubs.rsc.org/en/content/articlelanding/2011/dt/c1dt10587f