Reactions of Co(III)-coordinated Ornithine: Towards Inhibitors of the Polyamine Biosynthetic Pathway

Andrea J. Clarkson; Allan G. Blackman; Charles R. Clark; Alan M. Sargeson

doi:10.1071/CH09315

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Reactions of Co(III)-coordinated Ornithine: Towards Inhibitors of the Polyamine Biosynthetic Pathway

Andrea J. Clarkson ^A , Allan G. Blackman ^A ^D , Charles R. Clark ^A and Alan M. Sargeson ^B ^C

+ Author Affiliations

- Author Affiliations

^A Department of Chemistry, University of Otago, PO Box 56, Dunedin, New Zealand.

^B Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia.

^C Deceased.

^D Corresponding author. Email: blackman@chemistry.otago.ac.nz

Australian Journal of Chemistry 62(10) 1221-1225 https://doi.org/10.1071/CH09315
Submitted: 2 June 2009 Accepted: 28 July 2009 Published: 13 October 2009

Abstract

Treatment of the complex Δ,Λ-[Co(en)₂(S-ornithineH-κ²N,O)](CF₃SO₃)₃ with SOCl₂ in DMF gives a mixture of the expected imino complex [Co(en)₂(2-iminoornithineH-κ²N,O)]³⁺ and the amidine complex [Co(en)₂(5-{[(1E)-(dimethylamino)methylene]amino}-2-iminopentanoate-κ²N,O)]³⁺, which is proposed to result from the reaction of the Vilsmeier reagent [ClCH=N(CH₃)₂]⁺ with the terminal amine of coordinated ornithine. Treatment of the imino complex with nitromethane in alkaline solution gives the complex [Co(en)₂(2-nitromethylornithineH-κ²N,O)]³⁺, which contains the potential suicide inhibitor 2-nitromethylornithine. X-ray crystal structures of Δ-[Co(en)₂(S-ornithineH-κ²N,O)]Br₃ and Δ,Λ-[Co(en)₂(5-{[(1E)-(dimethylamino)methylene]amino}-2-iminopentanoate-κ²N,O)](ClO₄)₃ are reported.

Acknowledgements

We thank Professor Ward Robinson and Dr Jan Wikaira (University of Canterbury) for X-ray data collection. C.R.C. thanks the University of Otago for granting a period of study leave at the Australian National University and the Sargeson family for their warm hospitality during his stay.

References

Reactions of Co(III)-coordinated Ornithine: Towards Inhibitors of the Polyamine Biosynthetic Pathway

Abstract

Acknowledgements

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