A study on chemical behaviors of some 4-pyrones synthesized by one-step reactions towards various amines

Article abstract of DOI:10.1002/jhet.5570440209

(Chemical Equation Presented) Cycloaddition of acetylbenzoyl ketene generated in situ as an intermediate during one-step reaction between excess benzoylacetone and oxalylchloride to C=C double bond of cyclic enol form of benzoylacetone gave 3-acetyl-5-benzoyl-6-methyl-2-phenyl-4(47Y)-pyrone 1a. Condensation reactions of 1a together with 3,5-dibenzoyl-2,6-diphenyl-4(4H)- pyrone 1b and 3-benzoyl-5-ethoxycarbonyl-2,6-diphenyl-4(4H)-pyrone 1c with two-fold excess primary amines provided a series of 3-benzoyl-1-alkyl-5-(1- alkylimino-ethyl)-6-phenyl-2-methyl-4(1H)-pyridinone 2, 3,5-dibenzoyl-1-alkyl-2, 6-diphenyl-4(1H)-pyridinone 3a-c and 3-benzoyl-1-alkyl-5-ethoxycarbonyl-2,6- diphenyl-4(1H)-pyridinone 3d,e derivatives, respectively. In addition, while prolonged reaction of n-pentylamine with unsymmetrical pyrone derivative la gives a symmetrical pyridinone derivative namely 3,5-dibenzoyl-2,6-dimethyl-1- pentyl-4(1H)-pyridinone 5, much prolonged action n-pentylamine and then aqueous n-pentylamine on 1b resulted in degradation of the 4-pyrone ring to give dibenzoylmethane.

Full text of DOI:10.1002/jhet.5570440209

Mar-Apr 2007
337
A Study on Chemical Behaviors of Some 4-Pyrones Synthesized
By One-Step Reactions towards Various Amines
Ahmet Şener,a* Sıddık Eskinoba,a İshak Bildirici,a
Hasan Genç a and Rahmi Kasımoğulları b
a- Yüzüncü Yıl University, Art and Science Faculty, Chemistry Department, 65080 VAN-TURKEY
b- Dumlupınar University, Art and Science Faculty, Chemistry Department, KÜTAHYA-TURKEY
asener2001@yahoo.com
Received May 12, 2006
R
O
O
N
O
N
O
O
O
O
H3C
H3C
Ph
RNH2
- H2O
Ph
(COCl)2
CH3
Ph
Ph
Ph
O
CH3
Ph
CH3
H2
N
R
2
1a
H 11
C 5
.
n
O
O
O
O
O
O
O
O
O
R1
Ph
Ph
Ph
R1
Ph
Ph
RNH2
- H2O
H3C
N
CH3
Ph
N
O
Ph
1b,c
R
3
C5H11(n)
5
R1: Ph, OEt
Cycloaddition of acetylbenzoyl ketene generated in situ as an intermediate during one-step reaction
between excess benzoylacetone and oxalylchloride to C=C double bond of cyclic enol form of
benzoylacetone gave 3-acetyl-5-benzoyl-6-methyl-2-phenyl-4(4H)-pyrone 1a. Condensation reactions of
1a together with 3,5-dibenzoyl-2,6-diphenyl-4(4H)-pyrone 1b and 3-benzoyl-5-ethoxycarbonyl-2,6-
diphenyl-4(4H)-pyrone 1c with two-fold excess primary amines provided a series of 3-benzoyl-1-alkyl-5-
(1-alkylimino-ethyl)-6-phenyl-2-methyl-4(1H)-pyridinone 2, 3,5-dibenzoyl-1-alkyl-2,6-diphenyl-4(1H)-
pyridinone 3a-c and 3-benzoyl-1-alkyl-5-ethoxycarbonyl-2,6-diphenyl-4(1H)-pyridinone 3d,e derivatives,
respectively. In addition, while prolonged reaction of n-pentylamine with unsymmetrical pyrone derivative
1a gives a symmetrical pyridinone derivative namely 3,5-dibenzoyl-2,6-dimethyl-1-pentyl-4(1H)-
pyridinone 5, much prolonged action n-pentylamine and then aqueous n-pentylamine on 1b resulted in
degradation of the 4-pyrone ring to give dibenzoylmethane.
J. Heterocyclic Chem., 44, 337 (2007).
5-ethoxycarbonyl-2,6-diphenyl-4-pyrone 1c in a good
yield [13]. α-Oxoketenes (acylketenes) are highly reactive
molecules that usually can not be observed and isolated
under ordinary reaction conditions, although several
examples have been detected by low temperature ir
spectroscopy technique [14], and some sterically or
electronically hindered α-oxoketenes have been stabilized
by preparative flash vacuum pyrolysis method in recent
years [15]. A simple useful procedure of the generation of
α-oxoketenes is the thermal decarbonylation of 2,3-
dihydrofuran-2,3-diones at approximately 80-140°C in
solution [17].
INTRODUCTION
Six-membered nitrogen heterocycles are key units in
medicinal chemistry and versatile intermediates in organic
synthesis [1]. 4(1H)-Pyridinones have shown various
pharmacological effects such as antibacterial [2],
antifungal [3], anti-malarial [4], cardiotonic agents [5],
antihypertensive [6], anti-neoplastic [7], anti-inflam-
matory [8], analgesic [9], and treatment of Parkinson’s
disease [10]. On the other hand, the reaction of primary
amines with 4(1H)-pyrones to form 4(1H)-pyridinones
has been known for more than 90 years [11]. It has been
utilized for the preparation of a variety of these
pyridinones; despite the fact that this reaction has
somewhat limited scope, being reliable only for small
alkyl and aryl amines [11,12].
These ketenes are currently of considerable interest, not
only because of mechanistic and theoretical consider-
ations [18], but also because of their use as synthetic
building blocks in organic synthesis [15, 16].
Recently, one step synthesis of 3,5-dibenzoyl-2,6-
dipheyl-4-pyrone derivative 1b from the reaction of
dibenzoylmethane with oxalyl chloride has been reported
by our group [13]. Also, we demonstrated that α-oxo-
ketene generated in situ from 4-ethoxycarbonyl-5-phenyl-
2,3-dihydrofuran-2,3-dione in refluxing xylene has
reacted easily with dibenzoylmethane to give 3-benzoyl-
Here, we envisioned that we could generate acetyl
benzoylketene as a reactive intermediate via one-step
reaction of benzoylacetone with oxalylchloride similar to
the formation of dibenzoyl ketene [13] and trapped it in
[4+2] cycloaddition reaction with excess benzoylacetone
to give the titled compound 1a, namely 3-acetyl-5-
benzoyl-2-phenyl-6-methyl-4-pyrone. In addition, we also

338
A. Şener, S. Eskinoba, İ. Bildirici, H. Genç and R. Kasımoğullari
Vol 44
planned to investigate chemical behaviors of 1a together
with 1b and 1c towards a series of amine derivatives in
comparison with each-other.
only one product, the structure of which was identified
as 3-acetyl-5-benzoyl-2-phenyl-6-methyl-4-pyrone 1a,
mainly based upon 13C nmr spectroscopic data of 1a
(see experimental). This is an indication of regio-
specifically proceeding of cycloaddition reaction
between acetylbenzoyl ketene and benzoylacetone
(Scheme 2).
RESULTS AND DISCUSSION
Our attempt to synthesize some new six membered aza-
heterocycles via reactions of 1b and 1c together with 1a,
which we synthesized in this work, with a series of alkyl
or aryl amines, led to the formation of various
heterocyclic compounds having pyridine and pyridinone
ring systems (Scheme 3 and 4).
While 1b and 1c from 4-pyrone derivatives which were
investigated in terms of their chemical behaviors towards
amines were obtained according to procedure given in the
literature [14], 1a was prepared by refluxing of a mixture
of benzoylacetone (2 mmole) and oxalylchloride (1
mmole) in xylene (Scheme 1).
Scheme 2
O
Cl
Cl
O
O
H3C
Ph
+
OH
Ref. 19
O
O
H3C
Ph
O
O
Scheme 1
- CO
O
O
C
O
H3C
Ph
O
O
O
EtO
Ph
O
+
Ph
Ph
O
O
CH3
Ph
O
1c
Ref. 13
O
O
H
H
O
O
O
Ph
O
H3C
O
O
(COCl)2
Ph
R2
2 Ph
Ph
Ref. 13
1b
R1
O
Ph
O
O
O
1
O
O
O
O
O
O
O
H3C
Ph
H3C
Ph
CH3
Ph
CH3
Ph
H3C
Ph
CH3
(COCl)2
1
R1
R2
1a
O
Ph
O
a
b
c
CH3
Ph
Ph
CH3
Ph
OC2H5
1a
O
O
So far, studies reported on reactivity of α-oxoketenes
show that these reactive intermediates are capable of
undergoing [4+2] cycloaddition reactions with hetero-
dienophiles such as Schiff-bases, nitriles, isocyanates,
carbonyls and vinyl ethers to give various oxazinone,
oxazindione, dioxinone and 4-pyrone derivatives [20],
respectively. Our previous [13] and present studies related
to the synthesis of 4-pyrones are of importance because of
showing that α-oxoketenes are also capable of undergoing
Diels-Alder reactions with enol forms of some dicarbonyl
compounds.
2 Ph
CH3
In the preparation of 1a, both 4-acetyl-5-phenyl-2,3-
furandione [19] and acetylbenzoyl ketene used for the
reaction were generated in situ from a mixture of
benzoylacetone and oxalylchloride in boiling xylene.
Thus, [4+2] cycloaddition of acetylbenzoyl ketene,
generated by thermolysis of 4-acetyl-5-phenyl-2,3-
furandione formed during one-step reaction, to C=C
double bond of cyclic enol form of excess
benzoylacetone having
a
strong intramolecular
The structure of 1a was confirmed by analytical and
spectral data (see experimental). In addition, compound
1a could be easily converted via its reactions with a series
of primary amine derivatives in ethanol into the
corresponding pyridinone derivatives 2, structures of
which were also elucidated by elemental analysis and
spectroscopic data (see experimental) (Scheme 3).
hydrogen bond led to the formation of a new 4-pyrone
derivative 1a, which provide a versatile synthetic
method for 3,5-diacyl-4H-pyron-4-ones. Since both
benzoylacetone and acetylbenzoyl ketene posses
unsymmetrical structures, this reaction may produce
three isomeric 4-pyrone derivatives. However, the result
of TLC study for reaction illustrates the presence of

Mar-Apr 2007
A Study on Chemical Behaviors of Some 4-Pyrones
339
Scheme 3
The reactions of 1a with two-fold excess primary
amines were found to be significantly different. Upon
treatment with excess amines in ethanol at boiling
temperature for 20 hours, the resulting acetyl-4-(1H)-
pyridinones underwent a second condensation reactions
between acetyl groups and amines to yield the
corresponding alkylimino-4-(1H)-pyridinones (Scheme
3). In these reactions performed in polar solvents using
excess amine, while benzoyl groups in 4-pyrones 1b and
1c did not react with primary amines, the undergoing
condensation reactions of acetyl groups in 1a with amines
is interesting. In similar manner, symmetrical derivative 5
formed during the reaction of 1a with n-pentylamine also
did not react via its benzoyl group with n-pentylamine.
This shows that the formation of alkylimino-4-(1H)-
pyridinones is a process consisting of reactions having
two steps following each-other (Scheme 3 and 6).
O
O
O
O
O
O
H3C
Ph
H3C
Ph
Ph
+ RNH2
Ph
CH3
- H2O
O
CH3
N
R
1a
RNH2
- H2O
R
N
O
O
2
R
H3C
Ph
Ph
CH3
a
b
c
Et
Pr (n.)
Bu (n.)
N
R
2
Condensation reactions of all 4-pyrone derivatives with
two-fold excess primary amines were performed in
butanol or ethanol at boiling temperature for a time
between 20 or 40 hours. Compounds 1b and 1c having
phenyl groups at both C-2 and C-6 positions exhibits
similar behaviors towards primary amines. While the
reactions between ethylamine and 1b or 1c proceeded
smoothly affording the corresponding substituted 4-
pyridinones, the reactions with amines bearing bulky
groups afforded the corresponding substituted 4-
pyridinones in lower yields, even with prolonged reaction
times (Scheme 4).
Scheme 6
O
O
O
O
O
O
Ph
CH3
Ph
Ph
H3C
CH3
n.C H11NH2
+
5
H3C
O
Ph
N O
H
H
1a
C5H11(n)
O
O
O
O
O
N
O
Ph
Ph
Ph
H3C
Ph
- H2O
H3C
CH3
CH3
N O
Scheme 4
H
H
C5H11(n)
C5H11(n)
O
O
O
5
3
R1
R2
Ph
Ph
R2
Ph
a
b
c
d
e
Ph
Et
Bu
Ph
Et
Ph
Ph
Ph
EtO
EtO
1b, c
+ R1NH2
Our experiments show that the appearance of steric
hindrance depended on the size of both alkyl groups in
primary amines and functionalities at C-2 and C-6
positions on pyrane ring of 4-pyrones. Indeed, while 2,6-
diphenylpyrones 1b and 1c could not react with n-
pentylamine, 1a could react with the same reagent, even
when it is accompanying with a rearrangement.
While reactions of other all primary amines with 1a
derived the products having unsymmetrical structures, in
the case that starting materials are n-pentylamine and 1a,
due to this steric effect, only a pyridinone derivative with
symmetrical structure could be obtained.
Consequently, in the present work, novel 4-pyridinone
derivatives have been synthesized from three different
pyrones. One of the 4(1H)-pyrones is obtained regio-
specifically. The new compounds have been characterized
by elemental analyses, FT-IR, 1H nmr and 13C nmr
spectral data (see experimental).
- H2O
N
R1
3
H
O
O
O
O
O
O
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
1b
+ NH3
- H2O
N
4
N
H
Much prolonged action of n-pentylamine and then
aqueous n-pentylamine on 1b resulted in degradation of
the 4-pyrone ring, and ultimately gave dibenzoylmethane
(Scheme 5).
Scheme 5
n.C5H11NH3
+
OH
O
n.C5H11NH2 + H2O
O
O
O
O
EXPERIMENTAL
Ph
Ph
Ph
O
O
H
O
Ph
- CO2
( OH )
+ 2H2O
Ph
- (PhCO)2CH2
Ph
Ph
O
O
Ph
IR spectra were recorded on a Bio-Rad Win-1000 FT-IR
1
spectrometer in KBr pellets. The H nmr and 13C nmr spectra
1b

340
A. Şener, S. Eskinoba, İ. Bildirici, H. Genç and R. Kasımoğullari
Vol 44
were recorded on a Varian (200 MHz) and Varian (50 MHz)
spectrometers using SiMe4 as the reference. Elemental analyses
were performed on a Carlo Erba EAGER 200. Melting points
were determined on an Electrothermal Gallenkamp apparatus.
3,5-dibenzoyl-2,6-diphenyl-4-pyrone 1b, 3-benzoyl-5-ethoxy-
carbonyl-2,6-diphenyl-4-pyrone 1c were synthesized according
to the published procedures [13].
All reagents and solvents were of reagent grade quality and
were obtained from commercial suppliers. All solvents were
dried by refluxing with appropriate drying agents and distilled
before use. The homogeneity of the products was tested in each
step by TLC (SiO2).
3-Benzoyl-1-butyl-5-(1-butyliminoethyl)-6-phenyl-2-meth-
yl-4(1H)-pyridinone (2c). Yield 41%, mp 193°C; ir (KBr): (CH,
aromatic) 3060, (CH, aliphatic) 2975, (C=O and C=N-) 1693,
1
1666, 1620 cm-1; H nmr (CDCl3): δ 7.98-7.26 (m, 10H, CH,
aromatic), 3.94-3.68 (t, 2H, N-CH2-CH2-), 3.64-3.60 (t, 2H, =N-
CH2-CH2-), 2.30 (s, 3H, CH3), 2.24 (s, 3H, CH3), 1.81-1.65 (m,
4H, N-CH2-CH2-CH2-CH3), 1.56-1.37 (m, 4H, =N-CH2-CH2-CH2-
CH3), 1.03-0.96 (t, 3H, N-CH2-CH2-CH2-CH3), 0.72-0.64 ppm (t,
3H, =N-CH2-CH2-CH2-CH3); 13C nmr (CDCl3): δ 198.48 (C=O,
benzoyl), 175.67 (C=O, C-4), 175.49 (C, imino), 151.98 (C-6),
148.61 (C-2), 139.09, 135.71, 135.44, 132.39, 131.88, 131.40,
131.32, 131.02, 130.76, 130.58, 51.19 (N-CH2-), 49.97 (=N-CH2-),
34.28 (CH3), 34.13 (CH3), 21.89 (N-CH2-CH2-CH2CH3), 21.52
(=N-CH2-CH2-CH2CH3), 19.46 (N-CH2-CH2-CH2-CH3 and =N-
CH2-CH2-CH2-CH3), 15.57 (-N-CH2-CH2-CH2-CH3), 15.08 ppm
(=N-CH2-CH2-CH2-CH3). Anal. Calcd. for C29H34N2O2: C, 78.70;
H, 7.74; N, 6.33. Found: C, 78.65; H, 7.73; N, 6.34.
General Procedures for Pyridinone Derivatives (3a-c).
3,5-dibenzoyl-2,6-diphenyl-4-pyrone 1b (1 mmol) and amine
derivative (2 mmol) were refluxed in 1-butanol for a time
between 20 and 40 hours (24 h for 3a, 20 h for 3b and 40 h for
3c). The solvent was evaporated under reduced pressure to give
an oily residue which was treated with ether and finally
crystallized from ethanol.
3-Acetyl-5-benzoyl-2-phenyl-6-methyl-4-pyrone (1a).
Benzoylacetone of (0.32 g, 2 mmole) and oxalylchloride (0.086 ml,
1 mmole) in xylene were heated for 4 hours at reflux temperature.
After the solvent were removed by evaporation, the oily residue was
dissolved in ether. After 10 hours, the formed crystals were
collected by filtration and recrystallized from ethanol to give 0.066 g
(20%) of 1a, mp 184°C; ir (KBr): (CH, aromatic) 3050, (CH,
1
aliphatic) 2950, C=O 1704, 1672, 1643 cm-1; H nmr (CDCl3): δ
7.93-7.43 (m, 10H, CH, aromatic), 2.39 (s, 3H, CH3), 2.30 ppm (s,
3H, CH3-C=O); 13C nmr (CDCl3): δ 201.47 (C=O, acetyl), 194.71
(C=O, benzoyl), 176.86 (C=O, C-4), 166.54 (C-6), 163.98 (C-2),
138.45, 136.14, 133.66, 132.75, 131.37, 131.29, 130.91, 130.85,
130.33, 128.81, 34.01 (CH3), 20.36 ppm (CH3-C=O). Anal. Calcd.
for C21H16O4: C, 75.89; H, 4.85. Found: C, 75.62; H, 4.85.
3,5-Dibenzoyl-1,2,6-triphenyl-4(1H)-pyridinone (3a). Yield
35%, mp 272°C (24 hours); ir (KBr): (CH, aromatic) 3061,
1
(C=O) 1664, 1615 cm-1; H nmr (CDCl3): δ 7.91-6.91 ppm (CH,
General Procedures for Pyridinone Derivatives (2a-c).
3-Acetyl-5-benzoyl-2-phenyl-6-methyl-4-pyrone 1a (1 mmol)
and amine derivative (2 mmol) were refluxed in ethanol for 24
hours. The solvent was evaporated under reduced pressure to
give an oily residue which was treated with ether and finally
crystallized from indicated solvent and solvent for each
compound: 2a, ethanol; 2b, ethanol:water; 2c, ethanol:water.
3-Benzoyl-1-ethyl-5-(1-ethyliminoethyl)-6-phenyl-2-meth-
yl-4(1H)-pyridinone (2a). Yield 60%, mp 193°C; ir (KBr):
(CH, aromatic) 3050, (CH, aliphatic) 2950, (C=O and C=N-)
aromatic); 13C nmr (CDCl3): δ 196.45 (C=O, benzoyl), 175.93
(C=O), 152.29 (C-2), 140.82, 139.32, 135.13, 133.97, 133.07,
132.06, 131.88, 131.33, 130.90, 130.36, 129.73 ppm. Anal.
Calcd. for C37H25NO3: C, 83.59; H, 4.74; N, 2.63. Found: C,
83.53; H, 4.75; N, 2.63.
3,5-Dibenzoyl-1-ethyl-2,6-diphenyl-4(1H)-pyridinone (3b).
Yield 65%, mp 257°C (20 hours); ir (KBr): (CH, aromatic)
1
3060, (CH, aliphatic) 2950, (C=O) 1677, 1615 cm-1; H nmr
(CDCl3): δ 7.81-7.27 (m, 20H, CH, aromatic), 3,67-3.63 (q, 2H,
CH2), 0.92-0.85 ppm (t, 3H, CH3); 13C nmr (CDCl3): δ 196.64
(C=O, benzoyl), 175.27 (C=O), 151.97 (C-2), 139.29, 135.03,
134.21, 133.63, 131.84, 131.33, 131.17, 130.57, 130.33, 47.44
(CH2), 17.89 ppm (CH3). Anal. Calcd. for C33H25NO3: C, 81.97;
H, 5.21; N, 2.90. Found: C, 81.88; H, 5.22; N, 2.90.
1
1685, 1670, 1619 cm-1; H nmr (CDCl3): δ 7.96-7.26 (m, 10H,
CH, aromatic), 4.02-3.91 (q, 2H, N-CH2-), 3.74-3.68 (q, 2H,
=N-CH2-), 2.25 (s, 3H, CH3), 2.22 (s, 3H, CH3), 1.36-1.28 (t,
3H, N-CH2-CH3), 1.13-1.09 ppm (t, 3H, =N-CH2-CH3); 13C nmr
(CDCl3): δ 198.51 (C=O, benzoyl), 175.69 (C=O, C-4), 158.29
(C, imino), 148.63 (C-6), 147.25 (C-2), 139.05, 135.48, 132.27,
131.39, 131.29, 130.93, 130.77, 130.71, 130.60, 46.15 (N-CH2-),
45.10 (=N-CH2-), 19.30 (CH3), 19.25 (CH3), 17.15 (N-CH2-
CH3), 17.11 (=N-CH2-CH3). Anal. Calcd. for C25H26N2O2: C,
77.69; H, 6.78; N, 7.25. Found: C, 77.61; H, 6.77; N, 7.24.
3-Benzoyl-1-propyl-5-(1-propyliminoethyl)-6-phenyl-2-
methyl-4(1H)-pyridinone (2b). Yield 55%, mp 168°C; ir
(KBr): (CH, aromatic) 3075, (CH, aliphatic) 2960, (C=O and
C=N-) 1704, 1667, 1619 cm-1; 1H nmr (CDCl3): δ 7.98-7.26 (m,
10H, CH, aromatic), 3.92-3.85 (t, 2H, N-CH2-CH2-), 3.85-3.55
(t, 2H, =N-CH2-CH2-), 2.31 (s, 3H, CH3), 2.24 (s, 3H, CH3),
1.85-1.77 (m, 2H, N-CH2-CH2-), 1.65-1.50 (m, 2H, =N-CH2-
CH2-), 1.07-1.00 (t, 3H, N-CH2-CH2-CH3), 0.70-0.62 ppm (t,
3H, =N-CH2-CH2-CH3); 13C nmr (CDCl3): δ 198.48 (C=O,
benzoyl), 175.69 (C=O, C-4), 162.79 (C, imino), 151.98 (C-6),
148.60 (C-2), 139.06, 135.48, 132.39, 131.90, 131.42, 131.34,
130.95, 130.77, 130.68, 130.60, 51.89 (N-CH2-), 51.50 (=N-
CH2-), 33.71 (CH3), 33.65 (CH3), 25.89 (N-CH2-CH2-CH3),
25.55 (=N-CH2-CH2-CH3), 19.48 (N-CH2-CH2-CH3), 12.92 ppm
(=N-CH2-CH2-CH3). Anal. Calcd. for C27H30N2O2: C, 78.23; H,
7.29; N, 6.76. Found: C, 78.32; H, 7.28; N, 6.75.
3,5-Dibenzoyl-1-n-butyl-2,6-diphenyl-4(1H)-pyridinone (3c).
Yield 27%, mp 228°C (40 hours); ir (KBr): (CH, aromatic) 3050,
1
(CH, aliphatic) 2932, (C=O) 1677, 1615 cm-1; H nmr (CDCl3): δ
7.82-7.26 (m, 20H, CH, aromatic), 3,56-3.48 (t, 2H, CH2), 1.39-
1.31 (m, 2H, CH2), 0.73-0.62 (m, 2H, CH2), 0.43-0.35 ppm (t, 3H,
CH3); 13C nmr (CDCl3): δ 196.62 (C=O, benzoyl), 175.27 (C=O),
152.07 (C-2), 139.35, 135.01, 134.08, 133.73, 131.81, 131.39,
131.18, 130.50, 130.30, 52.06 (CH2), 34.44 (CH2), 21.22 (CH2),
14.70 ppm (CH3). Anal. Calcd. for C35H29NO3: C, 77.83; H, 7.10;
N, 3.40. Found: C, 77.86; H, 7.09; N, 3.39.
General Procedures for Pyridinone Derivatives (3d, 3e).
3-benzoyl-5-ethoxycarbonyl-2,6-diphenyl-4-pyrone 1c (1 mmol)
and amine derivative (2 mmol) were refluxed in 1-butanol for 24
hours. The solvent was evaporated under reduced pressure to
give an oily residue which was treated with ether and finally
crystallized from ethanol.
3-Benzoyl-5-ethoxycarbonyl-1,2,6-triphenyl-4(1H)-pyrid-
inone (3d). Yield 35%, mp 246°C (10 hours); ir (KBr): (CH,
aromatic) 3061, (CH, aliphatic) 2981, (C=O) 1730, 1669, 1618
1
cm-1; H nmr (CDCl3): δ 8.00-6.80 (m, 20 H, CH, aromatic),
4.07-3.96 (q, 2H, CH2), 0.97-0.88 (t, 3H, CH3); 13C nmr

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A Study on Chemical Behaviors of Some 4-Pyrones
341
(CDCl3): δ 196.09 (C=O, benzoyl), 174.00 (C=O, C-4), 167.21
(C=O, ester), 152.08 (C-2), 151.86 (C-6), 140.82, 139.28,
138.41, 135.02, 134.35, 134.01, 133.95, 133.50, 132.05, 132.00,
131.50, 131.05, 131.35, 131.05, 130.49, 130.33, 130.25, 129.91,
63.25 (CH2), 15.70 ppm (CH3). Anal. Calcd. for C33H25NO3: C,
81.97; H, 5.21; N, 2.90. Found: C, 81.92; H, 5.22; N, 2.90.
3-Benzoyl-1-ethyl-5-ethoxycarbonyl-2,6-diphenyl-4(1H)-
pyridinone (3e). Yield 55%, mp 209°C (24 hours); ir (KBr): (CH,
aromatic) 3064, (CH, aliphatic) 2976, (C=O) 1734, 1673, 1620
cm-1; 1H nmr (CDCl3): δ 7.75-7.23 (m, 15H, CH, aromatic), 3.97-
3.87 (q, 2H, O-CH2), 3.64-3.53 (q, 2H, N-CH2), 1.17-1.10 (t, 3H,
O-CH2-CH3), 0.92-0.81 ppm (t, 3H, N-CH2-CH3); 13C nmr
(CDCl3): δ 196.33 (C=O, benzoyl), 173.96 (C=O, C-4), 167.29
(C=O, ester), 152.87 (C-2), 151.59 (C-6), 139.25, 135.00, 134.21,
134.09, 133.47, 132.05, 131.77, 131.29, 131.13, 130.64, 130.48,
130.27, 129.54, 63.09 (O-CH2), 60.07 (N-CH2), 17.75 (O-CH2-
CH3), 15.70 ppm (N-CH2-CH3). Anal. Calcd. for C29H25NO3: C,
79.98; H, 5.79; N, 3.22. Found: C, 79.95; H, 5.80; N, 3.21.
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benzoyl-2,6-diphenyl-4-pyrone 1a (0,46 g, 1 mmol) and excess
ammonia were refluxed in ethanol for 72 hours. The solvent was
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was treated with ether and finally crystallized from ethanol.
Yield 35%, mp 294°C; ir (KBr): (NH) 3375, (b, OH) 3370-2500,
1
(CH, aromatic) 3050, (C=O) 1671, 1617 cm-1; H nmr (CDCl3):
δ 11.08 (b, OH), 7.93-7.33 ppm (CH, aromatic). Anal. Calcd. for
C31H21NO3: C, 81.74; H, 4.65; N, 3.08. Found: C, 81.70; H,
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The Reaction of 1b with Aqueous n-Pentylamine. The 4-
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was evaporated under reduced pressure to give an oily residue
which dissolved in aqueous ether. After evaporation of ether, the
same residue was dissolved in ethanol (%96), and the solution was
allowed to crystallize. After three or four months, red colored big
crystals (0.34 g, 76%) consisting of dibenzoylmethane was
isolated by filtration; it was identified by comparison of its mp
78°C and TLC with an authentic sample [21].
3,5-Dibenzoyl-2,6-dimethyl-1-pentyl-4(1H)-pyridinone (5).
3-Acetyl-5-benzoyl-2-phenyl-6-methyl-4-pyrone 1a (0.33 g, 1
mmol) and n-pentylamine derivative (0.23 ml, 2 mmol) were
refluxed in ethanol for 36 hours. The solvent was evaporated
under reduced pressure to give an oily residue which was treated
with ether and finally crystallized from ethanol. Yield 35%, mp
210°C; ir (KBr): (CH, aromatic) 3100, (CH, aliphatic) 2956-
2928, (C=O) 1670, 1621 cm-1; 1H nmr (CDCl3): δ 7.90-7.26 (m,
10H, CH, aromatic), 3.98-3.85 (t, 2H, N-CH2-), 2.30 (s, 6H,
CH3), 1.75-1.71 (m, 2H, N-CH2-CH2-CH2CH2CH3), 1.41-1.34
(m, 4H, N-CH2-CH2-CH2-CH2-CH3), 0.96-0.90 ppm (t, 3H, N-
CH2-CH2-CH2-CH2-CH3); 13C nmr (CDCl3): δ 198.47 (C=O,
benzoyl), 175.68 (C=O, C-4), 148.58 (C-2 and C-6), 139.09,
135.44, 132.42, 131.33, 130.58, 50.20 (N-CH2-), 31.87 (CH3),
30.70 (N-CH2-CH2-CH2CH2CH3), 24.19 (N-CH2CH2-CH2-
CH2CH3), 19.46 (N-CH2CH2CH2-CH2-CH3), 15.85 ppm (N-
CH2CH2CH2CH2-CH3). Anal. Calcd. for C26H21NO3: C, 78.97;
H, 5.35; N, 3.54. Found: C, 78.91; H, 5.34; N, 3.55.
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Acknowledgement. The authors wish to express their
appreciation and gratitude to the Scientifically Research Projects
Chairman-ship of Yüzüncü Yıl University for its financial
support of this study. Project Number: 2003-FED-038.
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