Diverse and unexpected outcomes from oxidation of the platinum(II) anticancer agent [Pt{(p-BrC<inf>6</inf>F<inf>4</inf>)NCH<inf>2</inf>CH<inf>2</inf>NEt<inf>2</inf>}Cl(py)] by hydrogen peroxide

Ojha, Ruchika, Mason, Dayna, Forsyth, Craig M., Deacon, Glen B., Junk, Peter, and Bond, Alan M. (2021) Diverse and unexpected outcomes from oxidation of the platinum(II) anticancer agent [Pt{(p-BrC<inf>6</inf>F<inf>4</inf>)NCH<inf>2</inf>CH<inf>2</inf>NEt<inf>2</inf>}Cl(py)] by hydrogen peroxide. Journal of Inorganic Biochemistry, 218. 111360.

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Abstract

Oxidation of the anti-tumour agent [Pt{(p-BrC6F4)NCH2CH2NEt2}Cl(py)], 1 (py = pyridine) with hydrogen peroxide under a variety of conditions yields a range of organoenamineamidoplatinum(II) compounds [Pt{(p-BrC6F4)NCH=C(X)NEt2}Cl(py)] (X = H, Cl, Br) as well as species with shared occupancy involving H, Cl and Br. Thus, oxidation of the –CH2–CH2– backbone (dehydrogenation) occurs, often accompanied by substitution. Oxidation of 1 with H2O2 in acetone yielded 1:1 co-crystallized [Pt{(p-BrC6F4)NCH=CHNEt2}Cl(py)], 1H and [Pt{(p-BrC6F4)NCH=C(Cl)NEt2}Cl(py)], 1Cl. The former was obtained pure in low yield from the oxidation of 1 with (NH4)2[Ce(NO3)6] in acetone, and the latter was obtained from 1 and H2O2 in CH2Cl2 at near reflux. From the latter reaction under vigorous refluxing [Pt{(p-BrC6F4)NCH=C(Br)NEt2}Cl(py)], 1Br was isolated. In refluxing acetonitrile, oxidation of 1 with H2O2 yielded [Pt{(p-BrC6F4)NCH=C(H0.25Br0.75)NEt2}Cl(py)], 1H0.25Br0.75, in which the alkene is mainly substituted by Br in a dual occupancy. Treatment of 1 with H2O2 and tetrabutylammonium hydroxide in acetone at room temperature formed [Pt{(p-HC6F4)NCH2CH2NEt2}Cl(py)], 2. Oxidation of [Pt{(p-HC6F4)NCH2CH2NEt2}Br(py)], 3 with H2O2 in boiling acetonitrile gave the ligand oxidation product [Pt{(p-HC6F4)NCH=C(Br)NEt2}Br(py)], 3Br. All major products were identified by X-ray crystallography as well as by 1H and 19F NMR spectra. In cases of mixed crystals or dual occupancy compounds, the 19F and 1H NMR spectra showed dissociation into the components in the solution in the same proportions as in isolated crystalline material.

Item ID: 69906
Item Type: Article (Research - C1)
ISSN: 1873-3344
Keywords: Br liberation, Hydrogen peroxide, Olefinic substitution, Oxidation, Oxidation of the ligand, Platinum anti-tumour agents
Copyright Information: © 2021 Elsevier Inc. All rights reserved.
Funders: Australian Research Council (ARC), Australian Government (AG)
Projects and Grants: ARC grant DP120101470, AG Postgraduate award
Date Deposited: 01 Dec 2021 21:54
FoR Codes: 34 CHEMICAL SCIENCES > 3402 Inorganic chemistry > 340211 Transition metal chemistry @ 100%
SEO Codes: 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280105 Expanding knowledge in the chemical sciences @ 100%
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