Synthesis and spectral studies of pyranone derivative and its Cu(II), Co(II), Ni(II) and Zn(II) complexes

Article abstract of DOI:10.1134/S1070363208060315

Under the thermolysis condition, 5-phenyl-2,3-dihydro-2,3-furandione (IV) in inert aprotic solvents as p-xylene at 130-140°C yields 3-benzoyl-4-hydroxy-6-phenyl-2H-pyran-2-one (VI) via phenyl ketene (V). The compound (VI) was converted into the correspond

Full text of DOI:10.1134/S1070363208060315

ISSN 1070-3632, Russian Journal of General Chemistry, 2008, Vol. 78, No. 6, pp. 1277–1282. © Pleiades Publishing, Ltd., 2008.
Synthesis and Spectral Studies of Pyranone Derivative
and Its Cu(II), Co(II), Ni(II) and Zn(II) Complexes1
E. Akbasa, M. Sonmeza, B. Anılb and F. Aslanoglua
,
aDepartment of Chemistry, Faculty of Science and Arts, Yuzuncu Yil University
65080, Van, Turkey
bDepartment of Chemistry, Faculty of Science and Arts, Ataturk University
25240, Erzurum, Turkey
e-mail: esvakbas@hotmail.com
Received April 12, 2007
Abstract—Under the thermolysis condition, 5-phenyl-2,3-dihydro-2,3-furandione (IV) in inert aprotic sol-
vents as p-xylene at 130–140°C yields 3-benzoyl-4-hydroxy-6-phenyl-2H-pyran-2-one (VI) via phenyl ketene
(V). The compound (VI) was converted into the corresponding 3-benzoyl-4-hydroxy-6-phenylpyridin-2(1H)-
one (VII), and 3-benzoyl-2-oxo-6-phenyl-2H-pyran-4-yl acetate (VIII), by its reactions with ammonium
hydroxyde, and acetic anhydride, respectively. On the other hand, a series of new various metal complexes (IX-
XIa, XIb) of VI was synthesized. The results suggest that the compound VI as bidentate ligand indicate a
binuclear structure for the Cu(II) complex with square-planar geometry. The Ni(II) and Zn(II) complexes are of
tetrahedral and the Co(II) complex is also octahedral geometry with water molecules at the axial positions. The
1
structures of compounds and complexes were characterized on the basis of elemental analysis, Mass, IR, H,
and 13C NMR spectra.
DOI: 10.1134/S1070363208060315
4H-pyrimidin-4-ones [12]. The ketenes towards carbon-
nucleophiles converted into 4-pyrone derivative [10].
α-Oxoketenes are often used as structure particles
in chemical design. Usually they can not be stabilized
under reaction conditions. The most common method
for the synthesis of these highly reactive molecules is
the thermolysis of 2,3-dihydrofuran-2,3-diones and
1,3-dioxan-4-ones [1–7].
Besides, the compounds containing pyranone ring
are known as good complexing agents and therefore are
of interest in coordination and bioinorganic chemistry
[17–18]. The interests in these complex derivatives are
due to the possibility of their enzyme inhibitory
properties [19].
The ketenes usually were added to multiple bond
systems via a [2+2] process across their C=C as well
as C=O double bonds, while α-oxoketenes show a
pronounced behavior to form [4π+2π] hetero-Diels
Alder adducts when trapped with dienophiles. When
the reaction is carried out in an inert medium, the
–COC=C part of ketene molecule acts as heterodiene
while the C=C bond of ketene acts as heterodienophile
[7–11].
Herein we have reported synthesis of 3-benzoyl-4-
hydroxy-6-phenyl-2H-pyran-2-one [11] in inert aprotic
solvent. Thereafter, 3-benzoyl-4-hydroxy-6-phenyl-2H-
pyran-2-one was converted into the corresponding 3-
benzoyl-4-hydroxy-6-phenylpyridin-2(1H)-one, and 3-
benzoyl-2-oxo-6-phenyl-2H-pyran-4-yl acetate, by its
reactions with ammonium hydroxyde, and acetic an-
hydride, respectively. In addition the new Cu(II), Co(II),
Ni(II) and Zn(II) metal complexes of the 3-benzoyl-4-
hydroxy-6-phenyl-2H-pyran-2-one (VI) were synthe-
sized and characterized.
The nucleophilic addition is one of the most
characteristic reactions of the ketenes [10–13, 15]. N-
acrylamides of aroylacetic acids were obtained by the
reaction of the arylketenes with aromatic and
heterocyclic amines [16]. The reactions of ketene with
1,1-diamines form the substituted 6-aryl-2-methylene-
The reactions of oxalyl chloride with a solution of
alkenyloxysilanes in dry ether at room temperature
gives 2,3-furandiones (I). They undergo decom-
position, by heating to a temperature near the melting
1
The text was submitted by the authors in English.
1277

1278
AKBAS et al.
point (120–140°C), without solvents and give
2,4-diones (III) [11] as a result of [4+2] cyclo-
aroylketenes (II). They were converted into 3H-pyran-
dimerization (Scheme 1).
Scheme 1.
R2
R1
O
R1
O O
C C
-(CH3)3SiCl
-HCl
+
CHR2
O
C
(CH3)3SiO
Cl
O
Cl
O
I
OH
O
O
O
O
R2
R1
R2
R1
R2
R1
C
heat
R1
R1
R2
O
I
–CO
O
O
O
II
III
We have synthesized the same pyranone (VI) (LH)
compound in a good yield in refluxing p-xylene at
130–140°C (Scheme 2), instead of that described
above.
Scheme 2.
p-xylene/heat
–CO
O
O
O
O
O
without solvent
120oC/30 torr
H
H
C
O
[11]
Ph
H
O
[11]
O
Ph
O O
C C
O
IV
Ph
Ph
Ph
CH2
+
Cl
C
V
(CH3)3SiO
Cl
p-xylene/heat
–CO
OH
O
O
O
H
Ph
Ph
VI (LH)
We also prepared the same pyranone (VI) (LH)
compound in one step reaction between 1-phenyl–1-
trimethylsiloxyethylene and oxalylchloride in refluxing
p-xylene (Scheme 2). However, this reaction resulted
in a very low yield.
phenolic protons are generally downfield (7.5–4). If a
carbonyl group in the ortho position to the phenolic
protons is available, the absorption is downfield in the
range of about (12–10) because of intramolecular
hydrogen bonding [20]. Also, the signals from
aromatic protons were presented. The 13C NMR
spectrum of VI revealed the signals at δ 202.2, 182.9
(C=O). The mass spectrum of VI showed the
following ion peaks, m/e: 293.0, 292.0 (for further
details of spectroscopic investigations see Experi-
mental).
The IR spectroscopic data of VI are in agreement
1
with published data [11]. In the H NMR spectra of
VI, the 1-H (C5) signal appeared as a singlet at δ
6.7 ppm. A singlet signal at δ 15.9 ppm was also
exhibited due to OH proton. The behavior of a
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 6 2008

SYNTHESIS AND SPECTRAL STUDIES OF PYRANONE DERIVATIVE
1279
→
When the compound VI was allowed to react in 1-
butanol with ammonium hydroxyde, the corresponding
pyridine derivative VII was produced (Scheme 3). The
IR spectrum of compound VII showed the bands at
3287 cm–1 (NH OH), 1691, 1642 cm–1 (C=O). The
←
1H NMR spectrum of compound VII (in DMSO-d6)
revealed the signals at 9.9 (1H, br. s, NH), 12.2 (1H,
br. s, OH).
Scheme 3.
OH
O
O
OH
N
O
NH4OH
Ph
Ph
OH
Ph
N
Ph
OH
O
O
O
H
Ph
VII
Ph
OAc
O
O
VI (LH)
Ac2O
Ph
Ph
O
VIII
Treatment of the compound VI with acetic
anhydride afforded a single product that was identified
as 3-benzoyl-2-oxo-6-phenyl-2H-pyran-4-yl acetate
(VIII), the chemical transformation of which was
outlined in Scheme 3. The signals of hydroxyl function
changed in the spectra of complexes, indicating
coordination through phenolic oxygen and carbonyl
oxygen of ligand LH. By comparing the spectra of the
ligand and their complexes, the stretching vibrational
band of OH disappeared in the complexes and the
frequency shifts of some relevant bands of the ligand
were observed, particularly for the stretching vibration
of C=O [21] Co(II) and Ni(II) complexes showed a
broad band around 3300 cm–1 indicating the presence
of coordinated or lattice water in the complex. The bis
(acetato) bridged Cu(II) complex shows strong bands
at 1632 and 1468 cm–1. New bands in all the
complexes at 442–523 cm–1 are attributed to the M–O.
1
group disappeared in the IR and H NMR spectra of
1
compound VIII. The H NMR spectrum of compound
VIII revealed a singlet signal at δ 2.1 due to methyl
protons. Its IR spectrum showed absorption bands at
1782, 1731, 1658 cm–1 due to three carbonyl functions,
respectively (for details see Experimental).
On the other hand, bidentate mononuclear
complexes were obtained from 1/2 molar ratio
reactions with metal ions and LH (VI) except for 1/1
molar ratio binuclear Cu(II) complex. The LH(VI), in
reaction with Co(CH3COO)2 · 4H2O, Cu(CH3COO)2·
H2O, Zn(CH3COO)2 · 2H2O, and NiCl2 · 6H2O salts
yields complexes corresponding to the general formula
[Cu2(L)2(AcO)2] (IX), [Co(L)2] · 3H2O (X), [Ni(L)2]·
H2O (XIa) and [Zn(L)2] · H2O (XIb) (Scheme 4). The
analytical data are in a good agreement with the
proposed stoichiometry of the complexes. All the
complexes were of nonelectrolyte type, as measured
their conductivities in the range 2.8–9.5 Scm2 mole–1.
The 1H-NMR spectra of diamagnetic Zn(II)
complex showed approximately the same peaks
identical to those of the free ligand with exception of
the absent peak of OH group. This is considered as an
additional evidence for the deprotonation of OH.
The electronic spectra values and the magnetic
moment data of the complexes were given in the
experimental section. The spectrum of the Cu(II)
complex showed an absorption band at 724 nm
2
2
attributed to the B1g → A1g transition, which is com-
patible with this complex having a square-planar struc-
ture [22]. The Co(II) complex showed two bands at
698 and 510 nm attributed to 4T1g → 4A2g and 4T1g(F) →
4T1g(P) transitions respectively, in an octahedral
Strong bands observed at 3400, l750, and 1626 cm–1
and 1544 cm–1 in the IR spectra of the free ligand
assigned respectively to OH, C=O and C–Opyran was
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 6 2008

1280
AKBAS et al.
Scheme 4.
CH3
Ph
H
Ph
O
H
C
O
Ph
OH2
Co
Ph
O
O
O
O
O
O
O
O
O
.H2O
O
O
O
O
O
O
Cu
Cu
O
O
O
C
OH2
Ph
Ph
Ph
H
Ph
H
CH3
X
IX
Ph
H
Ph
O
O
O
O
O
O
.H2O
M
O
O
Ph
Ph
H
XI M
a
b
Ni
Zn
geometry around the Co(II) ion [21]. The spectrum of
the Ni(II) complex is consistent with tetrahedral
geometry showing to d–d transition band at 670 nm
assignable to transition T1 → T1(P), which suggests
tetrahedral geometry [22]. On the other hand, the
spectra of the Zn(II) complex has bands in the 276–
386 nm and these bands may be due to the n → π* and
π → π* transition of the benzene and heterocyclic
rings.
spectrometer. All experiments were followed by TLC
using DC Alufolien Kieselgel 60 F 254 Merck and
Camag TLC lamp (254/366 nm). The electronic
spectra in the 200–900 nm range were obtained in
DMSO on a Unicam UV2–100 UV/VIS spectro-
photometer. Molar conductance of the ligand and their
metal complexes were determined in DMSO at room
3
3
temperature by using
a
Jenway model 4070
conductivitymeter.
3-Benzoyl-4-hydroxy-6-phenyl-2H-pyran-2-one
(VI). The compound IV (1.74 g, 10 mmol) in 20 ml of
anhydrous p-xylene was refluxed 3 h at 130–140°C.
After the solvent was evaporated, then the oily residue
was treated with ether and the formed crude product
was crystallized from 2-propyl alcohol to give VI.
Yield 2 g (70%); mp 169–170°C; or to a stirred
solution of 1-phenyl–1-trimethylsiloxyethylene (4.8 g,
25 mmol) in 20 ml of anhydrous p-xylene was added
oxalylchloride (1.6 g, 12.5 mmol) over a period of one
hour at 25°C. After 2 h the mixture was heated for 3 h.
The solvent was evaporated, then the oily residue was
treated with ether and the formed crude product was
EXPERIMENTAL
Solvents were dried by refluxing with the
appropriate drying agents and distilled before use.
Melting points were determined on an Electrothermal
Gallenkamp apparatus and are uncorrected. Micro-
analyses were performed on LECO CHNS 932
Elemental Analyzer. The IR spectra were obtained in
potassium bromide pellets using a Mattson 1000 FTIR
1
spectrometer. The H and 13C NMR spectra were
recorded on Bruker Avance DPX-400 spectrometers,
using TMS as an internal standard. The mass spectra
(100 eV) were run on an AGILENT 1100 MSD mass
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 6 2008

SYNTHESIS AND SPECTRAL STUDIES OF PYRANONE DERIVATIVE
crystallized from 2-propyl alcohol to give VI. Yield
1281
in a vacuum dessicator.
0.8 g (10.9%); mp 169–170°C; IR spectrum (KBr):
1750, 1626, 1544 cm–1. 1H NMR (CDCl3): 6.68 s (1H,
C5), 7.5–7.9 m (10H, Ar), 15.9 s (1H, OH). 13C NMR
(CDCl3) δ, ppm: 200.3 (C=O, benzoyl), 180.9 (C=O,
C4), 166.1, 160.2, 138.0, 132.7, 132.3, 130.1, 129.2,
128.3, 127.9, 126.6, 99.5, 98.1. The mass spectrum
(100 eV), m/e: 294.1, 293.0, 292.0, 291.0, 288.6,
264.0, 262.9, 236.0, 214.9, 188.0, 186.9, 148.0, 146.9,
145.9, 131.0, 105.9, 104.8, 101.9, 79.8, 76.9, 68.9, and
63.9.
μ-Diacetato-bis(3-benzoyl-6-phenyl-2H-pyran-
2,4(3H)-dionato)dicopper(II) (IX). Yield 0.160 g
(65%); mp < 320°C. Found, %: C 57.60; H 3.13.
C40H28O12Cu2. Calculated, %: C 58.03; H 3.38. IR
(KBr), ν, cm–1: 1707, 1632 (C=O), 1293 (C–Ophenolic),
1581, 1422 (OCOCH3), 463, 520(M–O). ΛM (in
DMSO 1×10–3 M) 4.1 Scm2 mol–1; μeff. 1.69μB; λmax
(DMSO-d6), nm: 396, 520, 724.
Bis(3-benzoyl-6-phenyl-2H-pyran-2,4(3H)-dio-
nato)diaquacobalt(II)monohidrate (X). Yield 0.160 g
(62%); mp < 320 °C. Found, %: C 62.56; H 3.97.
C36H28O11Co. Calculated, %: C 62.16; H 4.02. IR
(KBr), ν, cm–1: 3300 (OH/H2O), 1697, 1640 (C=O),
1285 (C–Ophenolic), 442, 520 (M–O). ΛM (in DMSO-d6
1 × 10–3 M) 5.6 Scm2 mol–1; μeff. 3.10 μB; λmax
(DMSO), nm: 394, 510, 698.
3-Benzoyl-4-hydroxy-6-phenylpyridin-2(1H)-one
(VII). To the solution of VI (0.292 g, 1 mmol) in
20 ml 1-butanol was added excess of saturated
aqueous solution of ammoniumhydroxyde with stir-
ring. Then the reaction mixture was refluxed for 5 h.
The resulting mixture was kept at room temperature
for 24 h. The precipitate was filtered off and
recrystallized from 1-butanol to give VII. Yield 0.160 g
Bis(3-benzoyl-6-phenyl-2H-pyran-2,4(3H)-dio-
nato)nickel(II)monohidrate (XIa). Yield 0.160 g
(54%); mp < 320°C. Found, %: C 66.03; H 3.98.
C36H26O9Ni. Calculated, %: C 65.58; H 3.64. IR
(KBr), ν, cm–1: 3216 (OH/H2O), 1672, 1632 (C=O),
1280 (C–Ophenolic), 450, 517 (M–O). ΛM (in DMSO-d6
1 × 10–3 M) 9.5 Scm2 mol–1; μeff 2.85μB; λmax (DMSO),
nm: 358, 392, 540, 670.
(55%); mp. 284–285°C; IR spectrum, (KBr), ν, cm–1:
→
3287 (NH
OH), 1691, 1642 (C=O). 1H NMR
←
(CDCl3): 6.6 s (1H, C5), 7.5–7.9 m (10H, Ar), 9.9 br.s
(1H, NH), 12.2 br.s (1H, OH). Found, %: C 74.14; H
4.45; N 4.80. C18H13NO3. Calculated, %: C 74.22; H
4.50; N 4.81.
3-Benzoyl-2-oxo-6-phenyl-2H-pyran-4-yl acetate
(VIII). Compound VI (0.292 g, 1 mmol) was treated
with 5 ml of acetic anhydride and H2SO4 (2 drops),
and then mixture was stirred at cautious heating (no
gas evolution) for 30 more min. The reaction mixture
was cooled, and then the solution was treated with 100
ml water. The precipitate was filtered off and
recrystallized from ethyl alcohol. The compound VIII
was obtained in yield 0.20 g (60%). mp 144–145ºC.
IR: 1782, 1731, 1658 cm–1 (C=O). 1H NMR (CDCl3):
6.8 s (1H, C5), 7.2–7.9 m (10H, Ar), 2.1 (3H, s, CH3).
13C NMR (CDCl3), δ, ppm: 191.4, 168.7, 164.5, 164.1,
162.2, 138.5, 135.7, 134.1, 132.3, 131.2, 131.1, 130.7,
128.2, 115.3, 101.5, 22.7. Found, %: C 71.82; H 4.20.
C20H14O5. Calculated, % : C 71.85; H 4.22.
Bis(3-benzoyl-6-phenyl-2H-pyran-2,4(3H)-dio-
nato)zinc(II)monohidrat (XIb). Yield 0.160 g (70%);
mp < 320°C. Found. %: C 66.97; H 3.68. C36H22O8Zn.
Calculated, %: C 66.72; H 3.40. IR (KBr), ν, cm–1:
1672, 1630 (C=O), 1283 (C–Ophenolic), 442, 522 (M–
1
O). H NMR (DMSO): 6.62 s (1H, C5), 7.3–7.9 m
(10H, Ar). ΛM (in DMSO 1 × 10–3 M) 2.8 Scm2 mol–1;
μeff Dia; λmax (in DMSO-d6 1 × 10–3 M), nm: 276, 308,
356, 386.
ACKNOWLEDGMENTS
This work was supported by the Scientific and
Technical Research Council of Turkey (TBAG 2392
103T136). The authors would like to thank Department
of Chemistry, Faculty of Arts and Sciences, Ataturk
University for providing spectroanalytical facilities
and Dr. Musa Turker from Department of Biology,
Faculty of Arts and Sciences, Yuzuncu Yil University
for his linguistic support.
Synthesis of the complexes. 0.292 g (1 mmol) of
the ligand (VI) was dissolved in 30 ml of chloroform,
and a solution of 0.5 mmol of the metal salt [Cu(AcO)2·
H2O (0.099 g), Co(AcO)2·4H2O (0.124 g), NiCl2·6H2O
(0.120 g) and Zn(AcO)2·2H2O (0.109 g)] in 15 ml
methanol was added dropwise with continuous stirring.
The mixture was stirred further for 1.5–2.5 h at 80°C.
The precipitated solid was then filtered off, washed
with diethyl ether, followed by cold ethanol and dried
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