Organometallic ruthenium and osmium compounds of pyridin-2- and -4-ones as potential anticancer agents

Article abstract of DOI:10.1002/cbdv.201200005

Organometallic Ru^II compounds are among the most widely studied anticancer agents. Functionalizing metal centers with biomolecule-derived ligands has been shown to be a promising strategy to improve the antiproliferative activity of metal-based chemotherapeutics. Herein, the synthesis of a series of novel 3-hydroxypyridin-2-one-derived ligands and their M^II(η⁶-p-cymene) half-sandwich complexes (M=Ru, Os) is described. The compounds were characterized by 1D- and 2D-NMR spectroscopy, and elemental analysis. Copyright

Full text of DOI:10.1002/cbdv.201200005

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CHEMISTRY & BIODIVERSITY – Vol. 9 (2012)
Organometallic Ruthenium and Osmium Compounds of Pyridin-2- and -4-
ones as Potential Anticancer Agents
by Helena Henkea)b), Wolfgang Kandiollera), Muhammad Hanifc), Bernhard K. Kepplera)b), and
Christian G. Hartinger*a)b)d)
a) University of Vienna, Institute of Inorganic Chemistry, Waehringer Str. 42, AT-1090 Vienna
b) University of Vienna, Research Platform ꢀTranslational Cancer Therapy Researchꢁ,
Waehringer Str. 42, AT-1090 Vienna
c) Department of Chemistry, COMSATS Institute of Information Technology Abbottabad Campus,
University Road, Abbottabad-22060, Pakistan
d) The University of Auckland, School of Chemical Sciences, Symonds Str. 23, 1010 Auckland,
New Zealand (e-mail: c.hartinger@auckland.ac.nz)
Organometallic RuII compounds are among the most widely studied anticancer agents. Function-
alizing metal centers with biomolecule-derived ligands has been shown to be a promising strategy to
improve the antiproliferative activity of metal-based chemotherapeutics. Herein, the synthesis of a series
of novel 3-hydroxypyridin-2-one-derived ligands and their MII(h6-p-cymene) half-sandwich complexes
(M¼Ru, Os) is described. The compounds were characterized by 1D- and 2D-NMR spectroscopy, and
elemental analysis.
Introduction. – Due to the severe side effects of chemotherapeutics and their use
limited to a few types of tumors, the search for new compounds with tumor-inhibiting
properties is crucial. New drugs need to have improved selectivity and activity, and
should exhibit less side-effects as compared to established chemotherapeutics [1–5]. In
the field of medicinal inorganic chemistry, non-platinum anticancer agents based on
ruthenium and gallium have demonstrated great promise in clinical trials and could be
an alternative fulfilling afore-mentioned criteria for novel chemotherapeutics [6].
With the emergence of organometallic Ru compounds, research has been redirected
to compounds designed to exhibit biological properties based on more selective
interaction with target molecules [7]. In an initial development stage, researchers
aimed to attach biologically active ligand systems to the metal center. This approach
resulted in the preparation of [Ru(h6-C6H6)Cl2(metronidazole)] with metronidazole,
being a well-known anti-infective agent [8], and a series of compounds with various
enzyme inhibitors as ligands or structural elements like ethacrynic acid, paullones, and
staurosporine [7].
In recent years, we have explored the use of (thio)pyridinone (including pyranone)
ligand systems derived from the biomolecule maltol in the development of anticancer
agents [4][9][10]. Hydroxypyridinones are of high interest in medicinal inorganic
chemistry [4][11]. Selected examples include their application as antidiabetic [12–15],
antibacterial [16–18], and antiviral agents [18], as Naþ- and Liþ-receptors [19–21], for
treatment of iron-overload disease [11] and, potentially, of neurodegenerative
ꢂ 2012 Verlag Helvetica Chimica Acta AG, Zꢃrich

CHEMISTRY & BIODIVERSITY – Vol. 9 (2012)
1719
disorders [22], as matrix metalloprotein [23–25] and anthrax lethal factor inhibitors
[17][18], magnetic resonance imaging (MRI) contrast agents [26][27], and as
anticancer drugs [28–30]. One of the most important examples is the presence in the
anticancer agent tris(maltolato)gallium(III) which has been undergoing clinical trials
in order to improve the bioavailability of GaIII and to prevent the hydrolysis of the drug
[28][29][31]. We have reported a series of mono- and polynuclear Ru and Os
complexes derived from maltol as the central building block to exhibit biological
activity based on varying chemical properties, such as cross-linking of DNA duplexes
and of DNA and proteins by dinuclear compounds [32], and potential to overcome
drug resistance [33]. In case of mononuclear compounds, the increased stability of
thiopyranones over pyranones is noteworthy, accompanied by a change in selectivity of
cytotoxicity in cancer cells [34][35].
Herein, we report on the preparation and characterization of an extended series of
maltol-based organometallic Ru and Os complexes aiming at compounds functional-
ized on the pyridinone moiety in order to alter their stability in aqueous solution and
their biological properties.
Results and Discussion. – RuIIꢀpyranone complexes have been shown to undergo
aquation of the chloride ligand upon dissolution in H2O, followed by the formation of
dimeric tris(hydroxido)-bridged Ru complexes [4][34–37]. Since pyridinones are
known to form more stable complexes than pyranones (the stability decreases in
the order 3-hydroxypyridin-4-one>3-hydroxypyridin-2-one>1-hydroxypyridin-2-one
[38]) and in order to functionalize RuII compounds at the ligand, a series of pyridinone
ligands were synthesized. The most general approach to convert hydroxypyranones
into hydroxypyridinones involves the protection of the OH group with a Bn moiety and
reaction with the primary amine at a pH value of ca. 12, followed by hydrogenation to
cleave the protecting group (Scheme 1) [38].
Scheme 1. Synthesis of 3-Hydroxypyridin-4(1H)-ones
a) BnBr. b) RꢀNH2, pH 12. c) H2, Pd/C.
A straightforward approach for the synthesis of pyridin-2(1H)-one ligands is the N-
alkylation of 2,3-dihydroxypyridine [39][40], and it was applied to prepare 4a–4c
(Scheme 2). Compound 1 was obtained by N-alkylation of 2,3-dihydroxypyridine with
BrCH2COOEt (77%), followed by protection of the OH group of 1 with BnCl under
alkaline conditions via an SN2 reaction, yielding ethyl [3-(benzyloxy)-2-oxopyridin-
1(2H)-yl]acetate (2) in high yield (83%) after aqueous workup [41]. In the next step of
the ligand synthesis, the ester moiety was converted with the appropriate amine into the
corresponding amides 3a–3c. Therefore, ester 2 was hydrolyzed under alkaline

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CHEMISTRY & BIODIVERSITY – Vol. 9 (2012)
Scheme 2. Preparation of the Pyridin-2(1H)-one Complexes (cym¼h6-cymene; M¼Ru, Os; X¼Cl, Br,
I; 4-MMP¼4-methylmorpholine)
conditions, and the obtained carboxylic acid was activated with 2-(1H-benzotriazol-1-
yl)-1,1,3,3-tetramethyluronium tetrafluoroborate (TBTU) to form the reactive O-acyl-
N,N,N’,N’-tetramethyluronium intermediate. This active ester was reacted with the
respective amines (a: propylamine; b: 4-(morpholin-4-yl)aniline; c: 4-phenylaniline) to
yield the desired amides after aqueous workup. To obtain ligands 4a and 4b, the
protecting group was removed by catalytic hydrogenation using H2 gas and Pd on
activated charcoal as catalyst. In case of 4c, the Bn group was removed under acidic
conditions. Both methods resulted in similar yields, however, the catalytic hydro-
genation was much faster than cleavage under acidic conditions.
1
The characterization of the compounds was carried out by H-,13C{1H}- and 2D-
NMR spectroscopy. The 1H-NMR spectra of 4a–4c displayed several features
confirming the nature of the compounds: the NH H-atom signals of the amides
appeared as a singlet at ca. 10 ppm, and the OH H-atoms were assigned to signals at ca.
9 ppm, indicating successful cleavage of the Bn group (Fig.). Furthermore, the lack of
signals assignable to the aromatic H-atoms and the CH2 group of the Bn moiety is a
clear indication of successful preparation of the desired ligands. 13C{1H}-NMR
1
Spectroscopy confirmed the observations mentioned above, and H,13C-HSQC and -
HMBC were used for unambiguous assignments of the peaks.

CHEMISTRY & BIODIVERSITY – Vol. 9 (2012)
1721
Figure. Reaction monitoring of the conversion of 3b to 4b by 1H-NMR spectroscopy
Complexes 5 were prepared by deprotonation of the ligands with MeONa and
subsequent addition of the dimeric precursor [Ru(h6-p-cymene)X(m-X)]2 (X¼Cl, Br,
I; Scheme 2). The mixture was stirred for a minimum of 3 h at room temperature, and
purification was achieved by precipitation from CH2Cl2 with Et2O to yield the chlorido
complexes in ca. 60% yield. Replacement of the Clꢀ ligand with either Brꢀ or Iꢀ led to
much lower yields of the complexes. For comparison purposes, also complexes of 3-
hydroxy-1,2-dimethylpyridin-4(1H)-ones were prepared to yield RuII- and OsII(h6-p-
cymene) complexes (6–8; Scheme 3) employing the same procedure as described for 5.
Scheme 3. Synthesis of the (h6-p-cymene)3-hydroxy-1,2-dimethylpyridin-4(1H)-oneꢀMII Complexes 6–8
The complexes were characterized by 1H- and 13C{1H}-NMR spectroscopy, melting
point, and elemental analysis. Most of the complexes decomposed at temperatures

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CHEMISTRY & BIODIVERSITY – Vol. 9 (2012)
>2008, and the elemental analysis data were in good agreement with the calculated
values.
NMR Experiments were carried out in (D4)MeOH or CDCl3 because of higher
stability of the complexes than in (D6)DMSO. The NMR spectra of 5bCl and 5bI
revealed that the H-atoms of the NꢀCH2ꢀCO group were not equivalent. The signals of
the aromatic H-atoms of the p-cymene appeared in the range of 5.3–5.6 ppm, which is
comparable to related O,O-chelated RuIIꢀpyridinone complexes [42]. The Me2CH
i
signal appeared as a multiplet at ca. 3 ppm, and those of the Me H-atoms of the Pr
group were detected in the lower ppm range. Chemical shifts of the coordinated ligands
are similar to those found in the spectra for the free ligands. The 13C-NMR signals of
5bCl, which are representative of the p-cymene signals, were observed as follows: those
of the CH groups were at ca. 80 (C(2)/C(6)), 78 (C(3)/C(5)), and 31 ppm (C(7)), of the
two quaternary C-atoms at 100 (C(1)) and 95 ppm (C(4)), and of the Me groups at 23
(C(8)/C(9)) and 19 ppm (C(10)). The same 2D methods were applied to unambigu-
ously assign the NMR signals of the ligands.
Conclusions and Outlook. – Developing new tumor-inhibiting drugs is very
important, due to the steady increase of the number of cancer patients and limitations
of currently applied chemotherapeutics. Compounds with new modes of action are
urgently needed hoping to find a successful way to cure cancer. A relatively new class of
compounds involves the use of hydroxypyridinone ligands coordinated to metal
centers. These ligands are of great interest for medicinal chemists, as pyridinones are
already applied in various areas of medicine.
Here, we reported on new derivatives of pyridinone Ru and Os complexes. A series
of novel ligands was prepared in order to extend the number of derivatives of this type
of compounds. By modifying not only the coordination sphere of the metal center but
also the ligand, the pharmacological properties of the anticancer agent can be
modulated. Therefore, pyridin-2-(1H)-one-based ligands were modified at the amide
functionality with Pr, 1,1’-biphenyl-4-yl, and 4-(morpholin-4-yl)phenyl residues. The
corresponding RuII(h6-p-cymene) complexes with different halido leaving groups
(chlorido, bromido, and iodido) were synthesized and characterized, as were pyridin-4-
(1H)-one complexes for comparison purposes. The preparation of these complexes
provides the basis to include them in further biological testing as well as to study their
drug-like properties, in order to pinpoint the influence of modification at various sites
of the complexes, and to gaining more insight on the biological properties of these
compounds.
We thank the Johanna Mahlke geb. Obermann-Stiftung, the Higher Education Commission of
Pakistan, the Austrian Exchange Service (ꢄAD), the Hochschuljubilꢀumsstiftung Vienna, COST D39,
and CM0902, and the Austrian Science Fund for financial support.
Experimental Part
General. The chemicals of anal. grade were purchased from commercial providers. Dry solvents were
produced following standard procedures. Bis[dichlorido(h6-p-cymene)ruthenium(II)] [43][44], bis[di-
bromido(h6-p-cymene)ruthenium(II)], bis[(h6-p-cymene)diiodidoruthenium(II)] [45], bis[dichlori-
do(h6-p-cymene)osmium(II)] [46], the precursors 1 and 2 [41], and 6 [47] were synthesized according

CHEMISTRY & BIODIVERSITY – Vol. 9 (2012)
1723
1
to literature procedures. M.p. Bꢁchi B-540 apparatus. H- (500.10 MHz) and 13C{1H}- (125.75 MHz) as
well as the 2D-NMR spectra (in gradient-enhanced mode): Bruker FT-NMR Avance IIITM 500 MHz
spectrometer; at 258; abbreviations for assignments: amide, R of the amide moity; Cym, p-cymene; Ph,
phenyl group (incl. substituents); Pyr, pyridin-2(1H)-one or pyridin-4(1H)-one moiety. Elemental
analyses: Microanalytical Laboratory, University of Vienna, on a PerkinꢀElmer 2400 CHN Elemental
Analyzer.
Syntheses. Amide Formation: General Procedure (GP). 4-Methylmorpholine (4-MMP; 2 equiv.) was
added to a soln. of ethyl [3-(benzyloxy)-2-oxopyridin-1(2H)-yl]acetate (2; (1 equiv.) and 2-(1H-
benzotriazol-1-yl)-1,1,3,3-tetramethyluronium tetrafluoroborate (TBTU; 1.05 equiv.) in dry DMF
(50 ml) under Ar, and the mixture was stirred at r.t. for 20 min. Subsequently, the appropriate amine
was added, and the mixture was stirred for another 18 h at r.t. The solvent was removed under vacuum,
and the residue was dissolved in CH2Cl2 and washed with 5% aq. HCl (2ꢁ ), 5% aq. NaOH (3ꢁ ), and
H2O (2ꢁ ). The solvent was removed on a rotary evaporator, and the crude product was recrystallized
from 96% EtOH [48].
Complexation. The ligand (1 equiv.) was deprotonated by MeONa (1.1 equiv.) in MeOH.
Subsequently, the corresponding dimer [M(h6-p-cymene)X(m-X)]2 (M¼Ru, Os, X¼Cl, Br, I; 0.9 equiv.)
was dissolved in CH2Cl2 and added in one portion. The mixture was stirred at r.t. for 3 h. Then, the solvent
was removed under reduced pressure, the residue was extracted with CH2Cl2 and filtered, and the soln.
was concentrated to a volume of ca. 2–3 ml. Et2O was added until precipitation occurred, and the pure
product was isolated by filtration.
2-[3-(Benzyloxy)-2-oxopyridin-1(2H)-yl]-N-propylacetamide; 3a). The reaction was performed
according to GP, using 2 (¼ [3-(benzyloxy)-2-oxopyridin-1(2H)-yl]acetic acid; 4.00 g, 15.4 mmol),
TBTU (¼O-(Benzotriazol-1-yl)-N,N,N’,N’-tetramethyluronium tetrafluoroborate; 5.28 g, 16.4 mmol),
4-MMP (3.12 g, 30.8 mmol), and PrNH2 (0.91 g, 15.1 mmol). Yield: 4.02 g (87%). 1H-NMR
(500.10 MHz, (D4)MeOH): 7.48 (d, J¼7.3, 2 H, Ph); 7.30–7.40 (m, 3 H, Ph); 7.18 (dd, J¼1.5, 6.5, 1 H,
Pyr); 6.99 (dd, J¼1.5, 6.5, 1 Hm, Pyr); 6.28 (t, J¼8.0, 1 H, Pyr); 5.12 (s, CH2O); 4.66 (s, CH2N); 3.19 (t, J¼
7.1, CH2, amide); 1.54–1.59 (m, CH2, amide); 0.96 (t, J¼7.4, Me).
2-[3-(Benzyloxy)-2-oxopyridin-1(2H)-yl]-N-[4-(morpholin-4-yl)phenyl]acetamide; 3b). The reac-
tion was performed according to the General Procedure, using 2 (1.94 g, 7.5 mmol), TBTU (2.60 g,
8.0 mmol), 4-MMP (1.52 g, 15.0 mmol), and 4-(morpholin-4-yl)aniline (1.34 g, 7.5 mmol). Yield: 2.10 g
(67%). M.p. 211–2128. 1H-NMR (500.10 MHz, (D6)DMSO): 10.11 (s, NH); 7.39–7.46 (m, 6 H, Ph); 7.27
(dd, J¼1.5, 7.0, 1 H, Pyr); 6.95 (dd, J¼1.5, 7.6, 1 H, Pyr); 6.91 (d, J¼7.0, 2 H, Ph); 6.15 (t, J¼7.1, 1 H,
Pyr); 5.03 (s, CH2O); 4.72 (s, NCH2CO), 3.73 (t, J¼5, 2 CH2O); 3.05 (t, J¼5.0, 2 CH2). 13C{1H}-NMR
(125.75 MHz, CDCl3): 165.4 (C¼O); 157.6 (C¼O); 148.3 (COꢀBn); 147.7 (CꢀN); 137.1 (C); 132.0 (arom.
CH); 131.6 (CꢀN); 128.9 (arom. CH); 128.4 (arom. CH); 128.39 (arom. CH); 120.5 (arom. CH); 116.3
(arom. CH); 115.9 (arom. CH); 103.9 (arom. CH); 70.3 (OCH2Ph); 66.6 (CH2ꢀO, Morph.); 52.3
(NCH2CO); 49.3 (CH2ꢀN, Morph.).
2-[3-(Benzyloxy)-2-oxopyridin-1(2H)-yl]-N-(1,1’-biphenyl-4-yl)acetamide; 3c). The reaction was
performed according to GP, using 2 (1.40 g, 5.4 mmol), TBTU (1.80 g, 5.6 mmol), 4-MMP (1.10 g,
10.9 mmol), and 4-phenylaniline (0.91 g, 5.4 mmol). Yield: 1.60 g (70%). M.p. 203–2048. 1H-NMR
(500.10 MHz, (D6)DMSO): 8.69 (t, J¼5.5, NH); 7.60–7.70 (m, 4 H, Ph); 7.30–7.50 (m, 10 H, Ph); 7.25 (d,
J¼6.6, 1 H, Pyr); 6.94 (d, J¼7.5, 1 H, Pyr); 6.14 (t, J¼7.0, 1 H, Pyr); 5.02 (s, CH2O); 4.63 (s, NCH2CO).
13C{1H}-NMR (125.75 MHz, CDCl3): 167.4 (C¼O); 157.6 (C¼O); 148.4 (COꢀBn); 140.4 (C); 139–3 (C);
138.9 (C); 137.1 (C); 132.0 (arom. CH); 129.4 (arom. CH); 128.9 (arom. CH); 128.45 (arom. CH); 128.36
(arom. CH); 127.8 (arom. CH); 127.1 (arom. CH); 116.2 (arom. CH); 103.9 (arom. CH); 70.3 (CH2O);
51.8 (NCH2CO).
2-(3-Hydroxy-2-oxopyridin-1(2H)-yl)-N-propylacetamide (4a). Compound 3a (1.1 g, 3.7 mmol) was
dissolved in MeOH, and 10% Pd/C (0.2 g) was added. The soln. was put into an autoclave, and the
apparatus was purged with Ar and evacuated (3ꢁ ). H2 at a pressure of 10–15 bar was applied, and the
soln. was stirred overnight at r.t. Then, the soln. was filtered through Celite to remove the catalyst, and the
solvent was removed under reduced pressure. Recrystallization from EtOH yielded the pure product.
Yield: 0.50 g (77%). M.p. 209–2118. 1H-NMR (500.10 MHz, (D6)DMSO): 8.93 (s, OH); 8.11 (t, J¼5.4,

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CHEMISTRY & BIODIVERSITY – Vol. 9 (2012)
NH); 7.06 (d, J¼6.5, 1 H, Pyr); 6.70 (d, J¼7.5, 1 H, Pyr); 6.07 (t, J¼7.0, 1 Hm, Pyr); 4.53 (s, NCH2CO),
3.04 (q, J¼7.0, CH2, amide); 1.37–1.43 (m, CH2, amide); 0.86 (t, J¼7.2, Me).
2-(3-Hydroxy-2-oxopyridin-1(2H)-yl)-N-[4-(morpholin-4-yl)phenyl]acetamide (4b). Compound 3b
(2.00 g, 4.8 mmol) was dissolved in AcOH, and 10% Pd/C (0.50 g) was added. The soln. was put into an
autoclave, and the apparatus was purged with Ar and evacuated (3ꢁ ). H2 at a pressure of 10–15 bar was
applied and the soln. was stirred overnight at r.t. Then, the soln. was filtered through Celite to remove the
catalyst, and the solvent was removed under reduced pressure. Recrystallization from EtOH yielded the
pure product. Yield: 1.10 g (70%). M.p. 246–2478. 1H-NMR (500.10 MHz, (D6)DMSO): 10.10 (s, NH);
8.99 (s, OH); 7.45 (d, J¼9.0, 2 H, Ph); 7.14 (dd, J¼1.4, 6.8, 1 H, Pyr); 6.91 (d, J¼9.0, 2 H, Ph); 6.74 (dd,
J¼1.5, J¼7.2, 1 H, Pyr); 6.11 (t, J¼7.0, 1 H, Pyr); 4.73 (s, NCH2CO); 3.73 (t, J¼5, CH2O); 3.05 (t, J¼5,
CH2N). 13C{1H}-NMR (125.75 MHz, CDCl3): 165.4 (C¼O); 158.4 (C¼O); 147.7 (CꢀOH); 147.1 (CꢀN);
131.5 (CꢀN); 130.1 (arom. CH); 120.5 (arom. CH); 120.5 (arom. CH); 115.9 (arom. CH); 115.6 (arom.
CH); 105.1 (arom. CH); 66.6 (CH2ꢀO, Morph.): 52.2 (NCH2CO); 49.3 (CH2ꢀN).
N-(1,1’-Biphenyl-4-yl)-2-(3-hydroxy-2-oxopyridin-1(2H)-yl)acetamide (4c). Compound 3c (1.60 g,
3.90 mmol) was dissolved in HCl/AcOH 1:1 (250 ml) and stirred at r.t. for 3–4 d. The mixture was
concentrated, the residue was suspended in MeOH, and the solvent was removed (3ꢁ ). Recrystalliza-
1
tion from EtOH gave the pure product. Yield: 0.90 g (72%). M.p. 236–2378. H-NMR (500.10 MHz,
(D6)DMSO): 9.00 (s, OH); 8.69 (t, J¼6.0, NH); 7.60–7.70 (m, 4 H, Ph); 7.45–7.50 (m, 2 H, Ph); 7.25–7.35
(m, 3 H, Ph); 7.12 (dd, J¼1.7, 6.9, 1 H, Pyr); 6.72 (dd, J¼1.7, 7.2, 1 H, Pyr); 6.10 (t, J¼7.0, 1 H, Pyr); 4.64
(s, NCH2CO). 13C{1H}-NMR (125.75 MHz, CDCl3): 167.3 (C¼O); 158.4 (C¼O); 147.1 (CꢀO); 140.4 (C);
139.3 (C); 138.9 (C); 130.0 (arom. CH); 129.4 (arom. CH); 128.4 (arom. CH); 127.8 (arom. CH); 127.1
(arom. CH); 115.4 (arom. CH); 105.2 (arom. CH); 51.8 (NCH2CO).
[Chlorido(h6-p-cymene)(N-{[(propylamino)carbonyl]methyl}-3-oxo-kO-pyridin-2(1H)-onato-
kO)ruthenium(II)] (5aCl). The reaction was performed according to GP1, using 4a (101 mg, 0.48 mmol),
MeONa (32 mg, 0.59 mmol), and [RuCl(m-Cl)(h6-p-cymene)]2 (123 mg, 0.20 mmol). Yield: 115 mg
(60%). M.p. 137–1428. 1H-NMR (500.10 MHz, (D4)MeOH): 8.18 (br. s, NH); 6.83 (br. s, 1 H, Pyr); 6.71
(br. s, 1 H, Pyr); 6.39 (br. s, 1 H, Pyr); 5.67 (br. s, 2 H, Cym); 5.45 (br. s, 2 H, Cym); 4.7–5.0 (1 H of
NCH2CO, overlapped with solvent signal); 4.66 (s, 1 H of NCH2CO); 3.20–3.30 (m, CH2, amide); 2.90–
2.98 (m, Me2CH); 2.27 (s, Me, Cym); 1.54–1.64 (m, Me2CH); 1.28–1.34 (m, CH2, amide); 0.97 (t, J¼8.0,
Me, amide). Anal. calc. for C20H27ClN2O3Ru·0.25 CH2Cl2 (501.20): C 48.53, H 5.53, N 5.59; found: C
48.31, H 5.22, N 5.94.
[(h6-p-Cymene)iodido(N-{[(propylamino)carbonyl]methyl}-3-oxo-kO-pyridin-2(1H)-onato-kO)r-
uthenium(II)] (5aI). The reaction was performed according to GP, using 4a (70 mg, 0.33 mmol), MeONa
(24 mg, 0.44 mmol), and [RuI(m-I)(h6-p-cymene)]2 (120 mg, 0.12 mmol). Yield: 15 mg (11%). 1H-NMR
(500.10 MHz, (D4)MeOH): 6.81 (br. s, 1 H, Pyr); 6.65 (br. s, 1 H, Pyr); 6.35 (br. s, 1 H, Pyr); 5.69 (br. s,
2 H, Cym); 5.47 (br. s, 2 H, Cym); 4.7–5.0 (1 H of NCH2CO, overlapped with solvent signal); 4.66 (s, 1 H
of NCH2CO); 3.10–3.20 (m, MeCH2); 2.90–2.98 (m, Me2CH); 2.27 (s, Me, Cym); 1.55–1.65 (m,
MeCH2CH2); 1.28–1.34 (m, Me2CH); 0.97 (t, J¼7.0, MeCH2CH2). Anal. calc. for C20H27IN2O3Ru·
0.25 CH2Cl2 (592.65): C 41.04, H 4.68, N 4.73; found: C 41.08, H 4.47, N 4.46.
[Chlorido(h6-p-cymene)(N-{[(4-(morpholin-4-yl)anilino)carbonyl]methyl}-3-oxo-kO)-pyridin-
2(1)-onato-kO)ruthenium(II)] (5bCl). The reaction was performed according to GP1, using 4b (145 mg,
0.44 mmol), MeONa (32 mg, 0.59 mmol), and [RuCl(m-Cl)(h6-p-cymene)]2 (123 mg, 0.20 mmol). Yield:
155 mg (64%). M.p. 241–2448 (dec.). 1H-NMR (500.10 MHz, CDCl3): 8.06 (s, NH); 7.60 (d, J¼8.9, 2 H,
Ph); 6.85 (d, J¼8.9, 2 H, Ph); 6.69 (d, J¼7.7, 1 H, Pyr); 6.52 (d, J¼6.1, 1 H, Pyr); 6.29–6.33 (m, 1 H,
Pyr); 5.55 (t, J¼5.2, 2 H, Cym); 5.25–5.30 (m, 2 H, Cym); 5.22 (d, J¼15.1, 1 H, of NCH2CO); 4.35 (d, J¼
15.1, 1 H, of NCH2CO); 3.86 (t, J¼7.0, 2 CH2O); 3.05 (t, J¼7.0, 2 CH2N); 2.90–2.98 (m, Me2CH); 2.32 (s,
Me); 1.28–1.34 (m, Me2CH). 13C{1H}-NMR (125.75 MHz, CDCl3): 166.1 (C¼O); 163.9 (C¼O); 161.2
(CꢀO); 148.4 (CꢀN); 130.3 (CꢀN); 122.1 (arom. CH); 120.8 (arom. CH); 118.0 (arom. CH); 115.9
(arom. CH); 113.8 (arom. CH); 99.5 (MeC, Cym); 95.0 (Me2CꢀC); 80.1 (CH, Cym); 80.0 (CH, Cym);
78.2 (CH, Cym); 77.7 (CH, Cym); 66.9 (CH2O), 54.4 (NCH2CO); 49.7 (CH2N); 31.2 (Me2CH, Cym);
22.5 (1 C, Me2CH); 22.3 (1 C, Me2CH); 18.5 (Me, Cym). Anal. calc. for C27H32ClN3O4Ru (599.08): C
54.13, H 5.38, N 7.01; found: C 54.18, H 5.24, N 7.04.

CHEMISTRY & BIODIVERSITY – Vol. 9 (2012)
1725
[Bromido(h6-p-cymene)(N-{[(4-(morpholin-4-yl)anilino)carbonyl]methyl}-3-oxo-kO-pyridin-
2(1H)-onato-kO)ruthenium(II)] (5bBr). The reaction was performed according to GP1, using 4b
(109 mg, 0.33 mmol), MeONa (24 mg, 0.44 mmol), and [RuBr(m-Br)(h6-p-cymene)]2 (106 mg,
0.15 mmol). Yield: 67 mg (39%). 1H-NMR (500.10 MHz, CDCl3): 7.99 (s, NH); 7.59 (d, J¼8.9, 2 H,
Ph); 6.85 (d, J¼8.9, 2 H, Ph); 6.69 (d, J¼7.7, 1 H, Pyr); 6.52 (d, J¼6.1, 1 H, Pyr); 6.28–6.32 (m, 1 H,
Pyr); 5.55 (t, J¼5.2, 2 H, Cym); 5.32 (dd, J¼3.6, 5.3, 2 H, Cym); 5.22 (d, J¼15.0, 1 H, NCH2CO); 4.32 (d,
J¼15.0, 1 H, NCH2CO); 2.92–2.95 (m, Me2CH); 2.32 (s, Me, Cym); 1.30–1.40 (m, Me2CH). Anal. calc.
for C27H32BrN3O4Ru·0.05 CH2Cl2 (647.78): C 50.15, H 4.99, N 6.49; found: C 49.86, H 4.78, N 6.81.
[(h6-p-Cymene)iodido(N-{[(4-(morpholin-4-yl)anilino)carbonyl]methyl}-3-oxo-kO-pyridin-2(1H)-
onato-kO)ruthenium(II)] (5bI). The reaction was performed according to GP, using 4b (109 mg,
0.33 mmol), MeONa (24 mg, 0.44 mmol), and [RuI(m-I)(h6-p-cymene)]2 (120 mg, 0.12 mmol). Yield:
86 mg (51%). 1H-NMR (500.10 MHz, CDCl3): 8.07 (s, NH); 7.55–7.65 (m, 2 H, Ph); 6.86 (d, J¼8.5, 2 H,
Ph); 6.70 (t, J¼7.7, 1 H, Pyr); 6.59 (d, J¼6.2, 1 H, Pyr); 6.29–6.36 (m, 1 H, Pyr); 5.55–5.70 (m, 2 H,
Cym); 5.33–5.40 (m, 2 H, Cym); 5.31–5.33 (m, 1 H, NCH2CO); 4.74 (s, 1 H, NCH2CO); 2.94–2.99 (m,
Me2CH); 2.36 (s, Me, Cym); 1.28–1.36 (m, Me2CH, Cym). Anal. calc. for C27H32IN3O4Ru·0.5 H2O
(699.54): C 46.32, H 4.82, N 6.00; found: C 46.33, H 4.38, N 6.24.
[Chlorido(h6-p-cymene)(N-{[(1,1’-biphenyl-4-ylamino)carbonyl]methyl}-3-oxo-kO-pyridin-2(1H)-
onato-kO)ruthenium(II)] (5cCl). The reaction was performed according to GP, using 4c (130 mg,
0.44 mmol), MeONa (32 mg, 0.60 mmol), and [RuCl(m-Cl)(h6-p-cymene)]2 (123 mg, 0.20 mmol). Yield:
153 mg (65%). M.p. 122–1268 (decomp.). 1H-NMR (500.10 MHz, CDCl3): 7.52–7.60 (m, 5 H, Ph); 7.41–
7.48 (m, 4 H, Ph); 6.69 (d, J¼7.4, 1 H, Pyr); 6.48 (d, J¼6.1, 1 H, Pyr); 6.29 (dd, J¼7.0, 14.4, 1 H, Pyr); 5.55
(t, J¼5.2, 2 H, Cym); 5.32 (dd, J¼3.6, 5.3, 2 H, Cym); 5.20 (d, J¼15.0, 1 H, NCH2CO); 4.76 (d, J¼15.0,
1 H, NCH2CO); 2.87–2.96 (m, Me2CH); 2.32 (s, Me, Cym); 1.28–1.34 (m, Me2CH). 13C{1H}-NMR
(125.75 MHz, CDCl3): 166.6 (C¼O); 165.8 (C¼O); 140.4 (CꢀO); 136.5 (C); 128.7 (arom. CH); 127.6
(arom. CH); 127.1 (arom. CH); 120.8 (arom. CH); 118.0 (arom. CH); 114.7 (arom. CH); 113.8 (arom.
CH); 107.7 (arom. CH); 101.3 (MeC, Cym); 95.1 (iPrC); 81.3 (C, Cym); 80.5 (C, Cym); 54.4 (NCH2CO);
30.5 (Me2CH); 22.5 (1 C, Me2CH); 22.3 (1 C, Me2CH); 18.5 (Me, Cym). Anal. calc. for C29H29ClN2O3Ru
(590.08): C 59.03, H 4.95, N 4.75; found: C 58.63, H 5.04, N 4.55.
[Bromido(h6-p-cymene)(1,2-dimethyl-3-oxo-kO-pyridin-4(1H)-onato-kO)ruthenium(II)} (7). The
reaction was performed according to GP, using 3-hydroxy-1,2-dimethylpyridin-4(1H)-one (92 mg,
0.66 mmol), MeONa (39 mg, 0.72 mmol), and [RuBr(m-Br)(h6-p-cymene)]2 (237 mg, 0.30 mmol). Yield:
20 mg (7%). 1H-NMR (500.10 MHz, CDCl3): 6.92 (d, J¼6.8, 1 H, Pyr); 6.41 (d, J¼6.8, 1 H, Pyr); 5.39–
5.52 (m, 4 H, Cym); 3.62 (s, MeN); 2.92–3.02 (m, Me2CH); 2.44 (s, Me); 2.35 (s, Me); 1.28–1.33 (m,
Me2CH, Cym). 13C{1H}-NMR (125.75 MHz, CDCl3): 173.7 (C¼O); 159.0 (CꢀO); 134.7 (MeC, Pyr);
133.8 (CH, Pyr); 108.7 (CH, Pyr); 98.8 (C, Cym); 95.4 (C, Cym); 79.1 (CH, Cym); 77.7 (CH, Cym); 41.6
(MeN); 31.0 (Me2CH, Cym); 21.2 (Me2CH); 17.3 (Me, Cym); 10.6 (Me, Pyr). Anal. calc. for
C17H22BrNO2Ru (453.34): C 45.04, H 4.89, N 3.09; found: C 44.80, H 4.67, N 3.07.
{Chlorido(h6-p-cymene)[1,2-dimethyl-3-oxo-kO-pyridin-4(1H)-onato-kO]osmium(II)} (8). The re-
action was performed according to GP, using 3-hydroxy-1,2-dimethylpyridin-4(1H)-one (61 mg,
0.40 mmol), MeONa (27 mg, 0.50 mmol), and [OsCl(m-Cl)(h6-p-cymene)]2 (158 mg, 0.20 mmol). Yield:
21 mg (11%). 1H-NMR (500.10 MHz, CDCl3): 6.99 (d, J¼6.5, 1 H, Pyr); 6.51 (d, J¼6.5, 1 H, Pyr); 6.00
(d, J¼5.5, 1 H, Cym); 5.93 (d, J¼5.5, 1 H, Cym); 5.78 (d, J¼5.5, 1 H, Cym); 5.73 (d, J¼5.5, 1 H, Cym);
3.67 (s, MeN); 2.70–2.78 (m, Me2CH); 2.45 (s, Me), 2.37 (s, Me), 1.24–1.27 (m, Me2CH). Anal. calc. for
C17H22ClNO2Os (498.05): C 41.00, H 4.45, N: 2.81; found: C 40.64, H 4.18, N 2.94.
REFERENCES
[1] P. J. Dyson, G. Sava, Dalton Trans. 2006, 1929.
[2] A. F. A. Peacock, P. J. Sadler, Chem.–Asian J. 2008, 3, 1890.
[3] G. Sꢃss-Fink, Dalton Trans. 2010, 39, 1673.
[4] W. Kandioller, A. Kurzwernhart, M. Hanif, S. M. Meier, H. Henke, B. K. Keppler, C. G. Hartinger,
J. Organomet. Chem. 2011, 696, 999.

1726
CHEMISTRY & BIODIVERSITY – Vol. 9 (2012)
[5] W. H. Ang, A. Casini, G. Sava, P. J. Dyson, J. Organomet. Chem. 2011, 696, 989.
[6] M. A. Jakupec, M. Galanski, V. B. Arion, C. G. Hartinger, B. K. Keppler, Dalton Trans. 2008, 183.
[7] C. G. Hartinger, P. J. Dyson, Chem. Soc. Rev. 2009, 38, 391.
[8] L. D. Dale, T. M. Dyson, D. A. Tocher, J. H. Tocher, D. I. Edwards, Anti-Cancer Drug Des. 1989, 4,
295.
[9] M. G. Mendoza-Ferri, C. G. Hartinger, R. E. Eichinger, N. Stolyarova, K. Severin, M. A. Jakupec,
A. A. Nazarov, B. K. Keppler, Organometallics 2008, 27, 2405.
[10] M. Hanif, P. Schaaf, W. Kandioller, M. Hejl, M. A. Jakupec, A. Roller, B. K. Keppler, C. G.
Hartinger, Aust. J. Chem. 2010, 63, 1521.
[11] K. H. Thompson, C. A. Barta, C. Orvig, Chem. Soc. Rev. 2006, 35, 545.
´
[12] T. Jakusch, K. Gajda-Schrantz, Y. Adachi, H. Sakurai, T. Kiss, L. Horvath, J. Inorg. Biochem. 2006,
100, 1521.
´
´
[13] E. A. Enyedy, A. Lakatos, L. Horvath, T. Kiss, J. Inorg. Biochem. 2008, 102, 1473.
´
´
´
[14] T. Jakusch, D. Hollender, E. A. Enyedy, C. S. Gonzalez, M. Montes-Bayon, A. Sanz-Medel, J. C.
Pessoa, I. Tomaz, T. Kiss, Dalton Trans. 2009, 2428.
[15] A. Katoh, Y. Matsumura, Y. Yoshikawa, H. Yasui, H. Sakurai, J. Inorg. Biochem. 2009, 103, 567.
[16] M. H. Feng, L. van der Does, A. Bantjes, J. Med. Chem. 1993, 36, 2822.
[17] J. A. Lewis, J. Mongan, J. A. McCammon, S. M. Cohen, ChemMedChem 2006, 1, 694.
[18] A. Agrawal, C. A. F. de Oliveira, Y. Cheng, J. A. Jacobsen, J. A. McCammon, S. M. Cohen, J. Med.
Chem. 2009, 52, 1063.
[19] H. Piotrowski, K. Polborn, G. Hilt, K. Severin, J. Am. Chem. Soc. 2001, 123, 2699.
[20] Z. Grote, M.-L. Lehaire, R. Scopelliti, K. Severin, J. Am. Chem. Soc. 2003, 125, 13638.
[21] Z. Grote, R. Scopelliti, K. Severin, J. Am. Chem. Soc. 2004, 126, 16959.
[22] M. A. Santos, Coord. Chem. Rev. 2008, 252, 1213.
[23] F. E. Jacobsen, J. A. Lewis, S. M. Cohen, ChemMedChem 2007, 2, 152.
[24] Y.-M. Zhang, X. Fan, S.-M. Yang, R. H. Scannevin, S. L. Burke, K. J. Rhodes, P. F. Jackson, Bioorg.
Med. Chem. Lett. 2008, 18, 405.
[25] Y.-L. Yan, M. T. Miller, Y. Cao, S. M. Cohen, Bioorg. Med. Chem. Lett. 2009, 19, 1970.
[26] E. J. Werner, A. Datta, C. J. Jocher, K. N. Raymond, Angew. Chem., Int. Ed. 2008, 47, 8568.
[27] A. Datta, K. N. Raymond, Acc. Chem. Res. 2009, 42, 938.
[28] M. A. Jakupec, B. K. Keppler, Curr. Top. Med. Chem. 2004, 4, 1575.
[29] L. R. Bernstein, T. Tanner, C. Godfrey, B. Noll, Metal-Based Drugs 2000, 7, 33.
[30] M. A. Santos, S. M. Marques, S. Chaves, Coord. Chem. Rev. 2012, 256, 240.
[31] M. A. Jakupec, B. K. Keppler, in ꢀMetal Ions in Biological Systemsꢁ, Eds. A. Sigel, H. Sigel, Marcel
Dekker, New York, 2004, p. 425.
´
´
[32] O. Novakova, A. A. Nazarov, C. G. Hartinger, B. K. Keppler, V. Brabec, Biochem. Pharmacol. 2009,
77, 364.
[33] M. G. Mendoza-Ferri, C. G. Hartinger, M. A. Mendoza, M. Groessl, A. E. Egger, R. E. Eichinger,
J. B. Mangrum, N. P. Farrell, M. Maruszak, P. J. Bednarski, F. Klein, M. A. Jakupec, A. A. Nazarov,
K. Severin, B. K. Keppler, J. Med. Chem. 2009, 52, 916.
[34] W. Kandioller, C. G. Hartinger, A. A. Nazarov, C. Bartel, M. Skocic, M. A. Jakupec, V. B. Arion,
B. K. Keppler, Chem.–Eur. J. 2009, 15, 12283.
[35] W. Kandioller, C. G. Hartinger, A. A. Nazarov, M. L. Kuznetsov, R. O. John, C. Bartel, M. A.
Jakupec, V. B. Arion, B. K. Keppler, Organometallics 2009, 28, 4249.
[36] A. F. A. Peacock, M. Melchart, R. J. Deeth, A. Habtemariam, S. Parsons, P. J. Sadler, Chem.–Eur. J.
2007, 13, 2601.
[37] W. Kandioller, C. G. Hartinger, A. A. Nazarov, J. Kasser, R. John, M. A. Jakupec, V. B. Arion, P. J.
Dyson, B. K. Keppler, J. Organomet. Chem. 2009, 694, 922.
[38] P. S. Dobbin, R. C. Hider, A. D. Hall, P. D. Taylor, P. Sarpong, J. B. Porter, G. Xiao, D. van der Helm,
J. Med. Chem. 1993, 36, 2448.
[39] R. C. Fox, P. D. Taylor, Synth. Commun. 1998, 28, 1563.
[40] M. Hanif, H. Henke, S. M. Meier, S. Martic, M. Labib, W. Kandioller, M. A. Jakupec, V. B. Arion,
H.-B. Kraatz, B. K. Keppler, C. G. Hartinger, Inorg. Chem. 2010, 49, 7953.

CHEMISTRY & BIODIVERSITY – Vol. 9 (2012)
1727
[41] M. Streater, P. D. Taylor, R. C. Hider, J. Porter, J. Med. Chem. 1990, 33, 1749.
[42] M. G. Mendoza-Ferri, C. G. Hartinger, A. A. Nazarov, W. Kandioller, K. Severin, B. K. Keppler,
Appl. Organomet. Chem. 2008, 22, 326.
[43] M. A. Bennett, A. K. Smith, J. Chem. Soc., Dalton Trans. 1974, 233.
[44] M. A. Bennett, T.-N. Huang, T. W. Matheson, A. K. Smith, S. Ittel, W. Nickerson, Inorg. Synth. 1982,
21, 74.
[45] M. G. Mendoza-Ferri, C. G. Hartinger, A. A. Nazarov, R. E. Eichinger, M. A. Jakupec, K. Severin,
B. K. Keppler, Organometallics 2009, 28, 6260.
[46] W. A. Kiel, R. G. Ball, W. A. G. Graham, J. Organomet. Chem. 1990, 383, 481.
[47] R. Lang, K. Polborn, T. Severin, K. Severin, Inorg. Chim. Acta 1999, 294, 62.
[48] B. L. Rai, H. Khodr, R. C. Hider, Tetrahedron 1999, 55, 1129.
Received January 12, 2012