Synthesis and some reactions of 4-(ethoxycarbonyl)-1,5-diphenyl- 1H-pyrazole-3-carboxylic acid

Article abstract of DOI:10.1002/jhet.5570440516

(Chemical Equation Presented) 1,5-Diphenyl-1H-pyrazole-3,4-dicarboxylic acid-4-ethyl ester 2, obtained from the 4-ethoxycarbonyl-5-phenyl-2,3-furandione 1 and N-benzylidene-N¹-phenyl hydrazine, was converted via reactions of its acid chloride 3 with various alcohols or N-nucleophiles into the corresponding ester 5 or amide derivatives 6, respectively. In addition, 2 was decarboxylated to give ethyl 1,5-diphenylpyrazole-4-carboxylate 4. Nitrile 7 derivative of 2 was also obtained by dehydration of 6a in a mixture of SOCl ₂ and DMF. While cyclocondensation reaction of 2 with hydrazine hydrate leads to the formation of pyrazolo[3,4-d]pyridazine-4,7-dione 8, the reaction of 3 with anhydrous hydrazine provided a new bis pyrazole derivative 9.

Full text of DOI:10.1002/jhet.5570440516

Sep-Oct 2007
1077
Synthesis and Some Reactions of
4-(Ethoxycarbonyl)-1,5-Diphenyl-1H-pyrazole-3-carboxylic Acid
Ahmet ꢀener,a* ꢁsrafil Tozlu,b Hasan Genç,b ꢁshak Bildiricia and Kadir Arısoyc
a- Yüzüncü Yıl University, Art and Science Faculty, Chemistry Department, 65080 VAN-TURKEY
b- Yüzüncü Yıl University, Faculty of Education, Department of Sciences, 65080 VAN-TURKEY
c- Celal Bayar University, Faculty of Arts and Sciences, Chemistry Department, Manisa-TURKEY
asener2001@yahoo.com
Received November 7, 2006
O
O
O
O
O
O
EtO
OH
EtO
Cl
PCl5
HN(Ph)N=CHPh
EtO
N
N
Ph
Ph
N
N
O
Ph
O
2O
Ph
2
Ph
3
NuH -HCl
H
NH2
NH2
1
Anhyd.
NH2
NH2
-co2
HN NH
O
O
O
O
O
O
O
Nu
EtO
Ph
EtO
N
H
RO
N
N
N
Ph
N
N
Ph
Ph
N
N
N
2
Ph
Ph
8
Ph
4
SOCl2
DMF
Ph
9
PhNCO
5,6
7
6a
6c
1,5-Diphenyl-1H-pyrazole-3,4-dicarboxylic acid-4-ethyl ester 2, obtained from the 4-ethoxycarbonyl-5-
phenyl-2,3-furandione 1 and N-benzylidene-N'-phenyl hydrazine, was converted via reactions of its acid
chloride 3 with various alcohols or N-nucleophiles into the corresponding ester 5 or amide derivatives 6,
respectively. In addition, 2 was decarboxylated to give ethyl 1,5-diphenylpyrazole-4-carboxylate 4. Nitrile
7 derivative of 2 was also obtained by dehydration of 6a in a mixture of SOCl2 and DMF. While
cyclocondensation reaction of 2 with hydrazine hydrate leads to the formation of pyrazolo[3,4-
d]pyridazine-4,7-dione 8, the reaction of 3 with anhydrous hydrazine provided a new bis pyrazole
derivative 9.
J. Heterocyclic Chem., 44, 1077 (2007).
hydrazones. Our approach was achieved by synthesis of a
new 1H-pyrazole derivative 2 with ortho functional
groups capable of forming the pyridazine ring.
INTRODUCTION
Furandiones are extremely versatile synthons in
heterocyclic chemistry [1]. Thermal decarbonylation of
these compounds yields ꢀ-oxoketenes as an intermediate
which are capable of undergoing cyclo- and nucleophilic
RESULTS AND DISCUSSION
addition
reactions
with
heterodienophiles
and
Without any solvent, heating of furandione 1 and
phenyl hydrazone of benzaldehyde (1/1 mole) for about 1
h. led to the formation of pyrazole-3,4-dicarboxylic acid
derivative 2, which was also recently synthesized by a
different method [7], in approximately 30 % yield. The
moderate yield of the reaction can be explained by the
chemical behavior of furandione 1 towards H-active
nucleophiles. Carbon atoms C-2, C-3 and C-5 in
furandiones are electrophilic sites having different
reactivity and could be used for the construction reactions
with nucleophiles [8]. Simultaneous attacks of H-active
nucleophiles to both C-2 and C-3 positions of the furan
ring could convert furandiones into starting materials;
these materials are dibenzoylmethane and oxalic acid
derivatives [9]. The by-products formed in this way are
removed when the raw product is treated with diethyl
ether. A reasonable proposal similar to that discussed with
4-benzoyl-5-phenyl-2,3-furandione [3d] for reaction
nucleophiles, respectively [2]. In addition, these
compounds also show typical carbonyl, lacton and ꢀ,ꢁ-
unsaturated carbonyl reactions depending on the
structures of the nucleophiles [3]. On the other hand,
furandiones, depending on functionalities at particularly
C-4 position, can exhibit different behaviors towards
nucleophiles as well as cycloaddition processes [4]. A
literature survey revealed that, so far, only 4-aroyl-
furandiones have been reacted with hydrazines or
hydrazones affording the corresponding 1H-pyrazole-3-
carboxylic acids [3b,3d,3e,3g,3h,4e], various analogues of
which proved to be interesting in a chemical and
biological context due to showing pharmacological action
with a wide spectrum [5]. In an attempt to help remedy
this situation we decided to extend our previous studies
[3a,3b,3d,3e,4e,6] on the reactions of
furandione 1, bearing ester group at C-4 position, with
a different

1078
A. ꢀener, ꢁ. Tozlu, H. Genç, ꢁ. Bildirici and K. Arısoy
Vol 44
pathway from furandione 1 to pyrazole acid 2 is outlined
briefly in Scheme 1.
[10], ester 5, amide 6 and nitrile 7 derivatives by the usual
chemical procedures (Scheme 2). While 4-benzoyl
pyrazole-3-carboxylic acids could be easily converted by
SOCl2 into the corresponding acid chloride [3b,3d,3e,6],
conversion of 2 with only PCl5, and with difficulty, into
the corresponding acid chloride 3 may be referred to a
steric effect (ortho-effect) originated from ethyl carbox-
ylate side chain at C-4 position of 2. On the otherhand,
while esterification reaction between chlorocarbonyl
group of 3 and methanol did not lead to any simultaneous
different reaction with the ester group of 3, the occurring
of trans-esterification on the ethyl carboxylate side chain
at C-4 position of 3 during the esterification reaction
between chlorocarbonyl group of 3 and propanol is
interesting. This may be due to the volatility differences
between methanol, ethanol and propanol (Scheme 2).
The correct structure of the unsymmetrically substituted
urea derivative was established by another chemical
procedure consisting of the reaction of primary amide 6a
with phenylisocyanate which resulted in formation of
phenylurea derivative 6c, originally prepared from the
acid chloride 3 in the usual way.
Scheme 1
–
COO
O
O
H
O
O
EtO
Ph
N(Ph)N=CHPh
EtO
H
+
Ph
N
Ph
O
N
O
H
–
Ph
1
COO
O
O
+
H
EtO
N
Ph
Ph
N
H
Ph
O
O
–
COOH
COO
EtO
Ph
EtO
H
N
N
O
–PhCHO
Ph
N
Ph
2
N
H
Ph
Ph
Reaction of pyrazole derivatives having functionalities
such as carbonyls, esters, carboxylic acids and nitriles in
the ortho-positions according to each other with
hydrazines may be a convenient method to build the
pyrazolo[3,4-d]pyridazine system [11]. Thus, the pyrazole
acid 2 was cyclized with hydrazine hydrate to a
pyrazolo[3,4-d]pyridazinedione derivative 8, both itself
and its tautomeric structures of which are previously
known [12], in approximately 38% yield (Scheme 3).
As mentioned above, while cyclocondensation reaction
of pyrazole acid 2 with excess hydrazine hydrate gives
pyrazolo-pyridazine derivative 8, the reaction of its acid
chloride 3 with anhydrous hydrazine at room temperature
led to the formation of a novel bis pyrazole compound 9
(Scheme 4).
Structure of compound 2 was confirmed by analytical
and spectral data (see Experimental). In addition, the acid
2 could be converted into the corresponding acid chloride
3, decarboxylation product 4 that is previously known
Scheme 2
O
O
O
O
O
COOR'
EtO
Ph
OH
EtO
RO
Cl
PCl5
R'OH
(Pyr)
N
N
N
Ph
Ph
N
N
N
Ph
Ph
Ph
3
2
5
R
Et
R'
Me
5
a
b
c
-CO2
NuH -HCl
n.Pr n.Pr
Et
Ph
O
O
O
O
Both undergoing ring closure reaction of 2 with only
excess hydrazine hydrate for giving pyrazolo[3,4-d]-
CN
SOCl2
DMF
EtO
Ph
Nu
EtO
EtO
Ph
N
N
N
pyridazine system
8 and forming of bis-pyrazole
Ph
(6a)
N
N
N
derivative 9 during the equimolar reaction of 3 with
anhydrous hydrazine may be an indication of pronounced
tendency to form open chain poly-condensation products
of 1H-pyrazole-3,4-dicarboxylic acid derivatives with
hydrazines.
Ph
Ph
Ph
7
4
6
Nu
NH2
6
a
b
c
PhNCO
6a
6c
NHPh
NHCONHPh
Scheme 3
H
H
H
H
O
O
N
N
N
N
N
N
N N
HO
O
O
OH
O
OH
HO
Ph
O
EtO
OH
NH2NH2.H2O
N
Ph
N
Ph
2
N
N
N
N
Ph
Ph
Ph
N
N
N
N
Ph
Ph
Ph
Ph
8

Sep-Oct 2007
Some Reactions of 4-(Ethoxycarbonyl)-1,5-Diphenyl-1H-pyrazole-3-carboxylic Acid
1079
1,5-Diphenyl-1H-pyrazole-4-carboxylic acid ethyl ester (4).
Compound 2 (0.336 g, 1 mmol) was heated to 235-240°C on an
oil bath for about 30 min, without any solvent. After cooling to
room temperature, the residue was treated with ether to give crude
product, which was then recrystallized from ethyl alcohol to yield
0.146 g (50 %) of 4, identical in ir spectrum with literature
compound mp 120°C (Reference [10a], mp 113°C; reference
[10b], mp 112.5-114°C; reference [10c], mp 116°C; reference
Scheme 4
Ph
N
Ph
OEt
O
O
H
N
N
NH2NH2
EtO
Ph
N
3
N
H
O
O
N
Ph
9
1
[10d], mp 116-118°C). H nmr (CDCl3): ꢀ = 8.19 (s, 1H, H-3),
7.38-7.17 (m, 10H, Ar-H), 4.20 (q, J = 7.1 Hz, 2H, OCH2), 1.22
ppm (t, J = 7.2 Hz, 3H, CH3); 13C nmr (CDCl3): ꢀ = 164.94 (C=O),
147.40 (N-Ph), 144.42 (C-3), 141.28 (C-5), 132.51, 131.06,
130.95, 130.80, 129.96, 129.86, 127.30, 115.93 (C-4), 62.05
(OCH2), 16.15 ppm (CH3). Anal. Calcd. for C18H16N2O2: C, 73.95;
H, 5.52; N. 9.58. Found: C, 73.90; H, 5.51; N, 9.59.
The structures of all these pyrazole derivatives,
1
obtained from 3, were confirmed by analytical, IR, H-
nmr and 13C nmr spectroscopic data, based on the
structural analogy of similar compounds [3a-e, 4e,6,10,
12,13] (see Experimental).
1,5-Diphenyl-1H-pyrazole-3,4-dicarboxylic acid-4-ethyl-3-
methyl ester (5a).
EXPERIMENTAL
General Procedure. The acid chloride 3 (0.355 g, 1 mmol)
and a moderate excess of methanol were refluxed together with
a catalytic amount of pyridine for 3 h. After cooling, the solution
was acidified by adding diluted hydrochloric acid (12 %) to give
a crude solid that was crystallized from the same alcohol. The
yield 0.263 g, (75 %), mp 95 °C ; IR: 3018 cm–1 (Ar-H), 2990
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.
Microanalyses were performed on a Carlo Erba Elemental
Analyzer Model 1108.The ir spectra were obtained as potassium
bromide pellets using a Mattson 1000 FTIR spectrometer. The
1H and 13C nmr spectra were recorded on Varian XL-200 (200
MHz) and Varian XL-200 (50 MHz) spectrometers,
respectively, using TMS as an internal standard. All experiments
were followed by using DC Alufolien Kieselgel 60 F 254 Merck
and Camag tlc lamp (254/366 nm)
1
cm–1 (R-H), 1736 cm–1 (C=O); H nmr (CDCl3): ꢀ = 7.33-7.27
(m, 10H, Ar-H), 4.21 (q, J = 7.1 Hz, 2H, OCH2), 3.97 (s, 3H,
OCH3), 1.17 ppm (t, J = 7.1 Hz, 3H, CH3); 13C nmr (CDCl3): ꢀ =
164.81 (C=O), 164.38 (C=O), 146.82 (N-Ph), 145.36 (C-3),
140.68 (C-5), 132.12, 131.41, 130.92, 130.53, 130.26, 130.01,
127.59, 117.78 (C-4), 63.10 (OCH2), 54.49 (OCH3), 15.87 ppm
(CH3). Anal.Calcd. for C20H18N2O4: C, 68.56; H, 5.18; N. 7.99.
Found: C, 68.52; H, 5.19; N, 7.98.
4-(Ethoxycarbonyl)-1,5-Diphenyl-1H-pyrazole-3-carboxylic
acid (2). An equimolar mixture of 1 (0.246 g, 1 mmol) and N-
benzylidene-N'-phenyl hydrazine (0.196 g, 1 mmol) was heated
to 90-100°C for approximately 40 min, without any solvent.
After cooling to room temperature, the residue was treated with
ether and the formed crude product was crystallized from a
mixture of toluene and cyclohexane (volume ratio:1:1) to give
0.101 g (30 %) of 2, mp 173°C; IR: 3250-2400 cm–1 (b, OH,
COOH), 3065 cm–1 (Ar-H), 2977 cm–1 (R-H), 1738 cm–1 (C=O),
1,5-Diphenyl-1H-pyrazole-3,4-dicarboxylic acid di-n-
propyl ester (5b). Compound 5b was prepared according to the
general procedure with a reflux time 2.5 h. using 1-propanol as
solvent, resulting in a 45 % yield (0.176 g), mp 130°C; IR: 3080
cm–1 (Ar-H), 2978 cm–1 (R-H), 1753 cm–1 (C=O); 1H nmr (CDCl3):
ꢀ = 7.36-7.19 (m, 10H, Ar-H), 4.35 (t, J = 6.8 Hz, 2H, OCH2), 4.11
(t, J = 6.6 Hz, 2H, OCH2), 1.81 (m, J = 7.1 Hz, 2H, CH2), 1.55 (m,
J = 7.0 Hz, 2H, CH2), 1.01 (t, J = 7.4 Hz, 3H, CH3), 0.79 ppm (t, J
= 7.4 Hz, 3H, CH3); 13C nmr (CDCl3): ꢀ = 164.98 (C=O), 164.30
(C=O), 146.66 (N-Ph), 145.97 (C-3), 140.75 (C-5), 132.11, 131.36,
130.87 (2 C), 130.43, 130.26, 127.59, 117.49 (C-4), 69.24 (OCH2),
68.74 (OCH2), 23.99 (CH2), 23.75 (CH2), 12.36 (CH3), 12.26 ppm
(CH3). Anal.Calcd. for C23H24N2O4: C, 70.39; H, 6.16; N. 7.14.
Found: C, 70.36; H, 6.17; N, 7.15.
1
1642 cm–1 (C=O); H nmr (CDCl3): ꢀ = 13.6 (br, H, COOH),
7.35-7.15 (m, 10H, Ar-H), 4.12 (q, J = 7.1 Hz, 2H, OCH2), 0.88
ppm (t, J = 7.1 Hz, 3H, CH3); 13C nmr (CDCl3): ꢀ= 168.95
(C=O, COOH or ester), 162.05 (C=O, COOH or ester), 150.38
(N-Ph), 146,26 (C-3), 140.25 (C-5), 132.20, 131.61, 130.88,
130.76, 130.66, 130.13, 127.73, 113.86 (C-4), 64.66 (OCH2),
15.16 ppm (CH3). Anal. Calcd. for C19H16N2O4: C, 67.85; H,
4.79; N, 8.33. Found: C, 67.74; H, 4.78; N, 8.34.
1,5-Diphenyl-1H-pyrazole-3,4-dicarboxylic acid-4-ethyl-3-
phenylester (5c). The acid chloride 3 (0.355 g, 1 mmol) and
phenol (0.094 g, 1 mmol) were refluxed together with a catalytic
amount of pyridine in toluene for 7 h. After evaporation of the
solvent, the oily residue was dissolved in ethyl alcohol then the
solution was acidified by adding diluted hydrochloric acid (12
%) to give a crude solid, which was crystallized from ethanol.
The yield 0.185 g (45 %), mp 120°C; IR; 3050 cm–1 (Ar-H),
3-Cholorocarbonyl-1,5-diphenyl-1H-pyrazole-4-carboxylic
acid ethyl ester (3). 2 (0.336 g, 1mmol) and PCl5 (0.208 g, 1
mmol) in CCl4 were refluxed for 3 h. After the solvent was
removed by evaporation, the oily residue was treated with dry
ether and the formed crude product was crystallized
cyclohexane. The yield 0.142 g (40 %) mp 97 °C; IR: 3090 cm–1
1
(Ar-H), 2984 cm–1 (R-H), 1726 cm–1 (C=O); H nmr (CDCl3): ꢀ
1
2927 cm–1 (R-H), 1778 cm–1 (C=O), 1727 cm–1 (C=O); H nmr
= 7.37-7.23 (m, 10H, Ar-H), 4.22 (q, J = 7.2 Hz, 2H, OCH2),
1.19 ppm (t, J = 7.1 Hz, 3H, CH3); 13C nmr (CDCl3): ꢀ =
164.07 (C=O), 163.48 (C=O), 148.11 (N-Ph), 146.65 (C-3),
140.35 (C-5), 132.08, 131.86, 131.19, 131.10, 130.47, 129.29,
127.50, 118.32 (C-4), 63.63 (OCH2), 15.77 ppm (CH3).
Anal.Calcd. for C19H15CIN2O3: C, 64.32; H, 4.26; CI, 9.99; N,
7.90. Found: C, 64.30; H, 4.26; CI, 10.00; N, 7.89.
(CDCl3): ꢀ = 7.47-7.23 (m, 15H, Ar-H), 4.25 (q, J = 7.1 Hz, 2H,
OCH2), 1.17 ppm (t, J = 7.1 Hz, 3H, CH3); 13C nmr (CDCl3): ꢀ =
164.49 (C=O), 162.39 (C=O), 152.68 (O-Ph), 146.98 (N-Ph),
144.94 (C-3), 140.70 (C-5), 132.17, 131.53, 131.46, 131.01,
130.67, 130.34, 129.97, 128.06, 127.63, 123.64, 118.30 (C-4),
63.28 (OCH2), 15.93 ppm (CH3). Anal.Calcd. for C25H20N2O4: C,
72.80; H, 4.89; N. 6.79. Found: C, 72.77; H, 4.89; N, 6.80.

1080
A. ꢀener, ꢁ. Tozlu, H. Genç, ꢁ. Bildirici and K. Arısoy
Vol 44
3-Carbamoyl-1,5-diphenyl-1H-pyrazole-4-carboxylic acid
ethyl ester (6a).
cm-1 (CN), 1753 cm–1 (C=O); 1H nmr (CDCl3): ꢀ = 7.43-7.17 (m,
10H, Ar-H), 4.29 (q, J = 7.1 Hz, 2H, OCH2), 1.29 ppm (t, J = 7.1
Hz, 3H, CH3); 13C nmr (CDCl3): ꢀ = 162.41 (C=O), 148.64 (N-
Ph), 143.88 (C-3), 140.21 (C-5), 132.44, 131.94, 131.10, 130.27,
129.45, 129.16, 127.34, 118.67 (C-4), 114.63 (CN), 63.21 (O
CH2), 15.86 ppm ( CH3). Anal. Calcd. for C19H15N3O2: C, 71.91;
H, 4.76; N. 13.24. Found: C, 71.87; H, 4.76; N, 13.25.
General Procedure. To the cold solution of acid chloride 3
(0.355 g, 1 mmol) in chloroform was added aqueous ammonia
(0.15 mL, 2 mmol) at 0-5°C, with stirring and the stirring
continued for 30 min. The formed white precipitate was isolated
by filtration and recrystallized from methanol to give 0.257 g (59
%) of 6a, mp 167°C; IR: 3464, 3336 cm–1 (NH2), 3055 cm–1 (Ar-
H), 2944 cm–1 (R-H), 1702 cm–1 (C=O), 1625 cm–1 (C=O, amide);
1H nmr (CDCl3): ꢀ = 8.52 (br, 1H, NH), 7.37-7.19 (m, 10H, Ar-
H), 6.20 (br, 1H, NH), 4.14 (q, J = 7.1 Hz, 2H, OCH2), 0.98 ppm
(t, J = 7.1 Hz, 3H, CH3); 13C nmr (CDCl3): ꢀ = 166.44 (C=O),
164.47 (C=O), 148.53 (N-Ph), 147.62 (C-3), 140.67 (C-5), 132.10,
131.24, 131.10, 130.80, 130.50, 130.15, 127.68, 115.50 (C-4),
63.28 (OCH2), 15.48 ppm (CH3). Anal. Calcd. for C19H17N3O3: C,
68.05; H, 5.11; N. 12.53. Found: C, 68.09; H, 5.10; N, 12.52.
1,5-Diphenyl-3-phenylcarbamoyl-1H-pyrazole-4-carboxyl-
ic acid ethyl ester (6b). Compound 6b was prepared according
to the general procedure using aniline as reagent, resulting in
57 % yield (0.234 g ) mp 200 °C; IR: 3285 cm–1 (N-H), 3080
cm–1 (Ar-H), 2945 cm–1 (R-H), 1705 cm–1 (C=O), 1628 cm-1
(C=O); 1H nmr (CDCl3): ꢀ = 10.60 (br, 1H, N-H), 7.82-7.12 (m,
15H, Ar-H), 4.18 (q, J = 7.1 Hz, 2H, OCH2), 1.01 ppm (t, J =
7.1 Hz, 3H, CH2); 13C nmr (CDCl3): ꢀ = 166.87 (C=O), 160.28
(C=O), 148.60 (N-Ph), 148.47 (N-Ph), 140.68 (C-3), 140.30 (C-
5), 132.08, 131.31, 131.04, 130.94, 130.86, 130.57, 130.21
127.68, 126.14, 122.09, 116.47 (C-4), 63.51 (OCH2), 15.54 ppm
(CH3). Anal.Calcd. for C25H21N3O3: C, 72.98; H, 5.14; N. 10.21.
Found: C, 72.94; H, 5.15; N, 10.22.
2,3-Diphenyl-5,6-dihydro-2H-pyrazolo[3,4-d]pyridazine-4,7-
dione (8). The compound 2 (0.336 g, 1 mmol) in hydrazine
hydrate used as solvent was refluxed for approximately 6 h.
After cooling, the formed white precipitates were collected by
filtration and recrystallized from acetic acid to give 0.116 g (38
%) of 8a, identical ir spectrum with literature compound, mp
315°C (Reference [12], mp 310°C). 13C nmr (DMSO-d6): ꢀ =
156.01 (b, C=O), 150.55 (b, C=O), 142.81, 142.04, 139.27,
131.21, 129.80, 129.63 (2 C), 128.40, 127.57, 126.75, 113.81
ppm. Anal.Calcd. for C17H12N4O2: C, 67.10; H, 3.97; N. 18.41.
Found: C, 67.05; H, 3.97; N, 18.42.
1,2-Bis-(4-ethoxycarbonyl-1,5-diphenyl-3-pyrazoloyl)-
hydrazine (9). To the solution of acid chloride 3 (0.354 g 1
mmol) in CCl4 was added anhydrous hydrazine (0.05 mI, 1
mmol) at room temperature, with stirring and the stirring
continued for 30 min. at room temperature. The formed
precipitate was isolated by filtration and recrystallized from
ethanol to give 0.205 g (30 %) of 9, mp 240°C; IR: 3500-2500
cm–1 (b, O=C-NHꢀHO-C=N-), 1684 cm-1 (C=O), 1630 cm-1
1
(C=O); H nmr (CDCl3): ꢀ = 11.98 (br, 1H, NH), 7.36-7.20 (m,
10H, Ar-H), 4.18 (q, J = 7.1 Hz, 2H, OCH2), 0.94 ppm (t, J =
7.1 Hz, 3H, CH3); 13C-nmr ( CDCl3): ꢀ = 166.15 (C=O), 157.95
(C=O), 148.89 (N-Ph), 146.26 (C-3), 140.62 (C-5), 132.22,
131.29, 131.04, 130.77, 130.51, 130.13, 127.66, 115.14 (C-4),
63.52 (OCH2), 15.55 ppm (CH3). Anal.Calcd. for C38H32N6O6: C,
68.25; H, 4.82; N. 12.57. Found: C, 68.30; H, 4.83; N, 12.56.
1,5-Diphenyl-3-(3-phenylüreidocarbonyl)-1H-pyrazole-4-
carboxylic acid ethyl ester (6c).
Method A: From Acid Chloride 3. An equimolar mixture of
the acid chloride 3 (0.355 g, 1 mmol) and phenyl-urea (0.136 g,
1 mmol) was refluxed in xylene for 4 h. After evaporation of the
solvent, the oily residue was treated with ether and the formed
crude product was recrystallized from methanol. The yield 0.182
g (40 %), mp 165°C ; IR: 3387 cm–1 (NH), 3080 cm–1 (Ar-H),
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.
1
2953 cm–1 (R-H), 1753 cm–1 (C=O), 1651 cm–1 (C=O); H nmr
REFERENCES
(CDCl3): ꢀ = 7.93 (br, NH), 7.44-6.90 (m, 15H, Ar-H), 4.18 (q, J
= 7.2 Hz, 2H, OCH2), 0.95 ppm (t, J = 7.2 Hz, 3H, CH3); 13C
nmr (CDCl3), ꢀ = 169.07 (C=O), 162.41 (C=O), 150.43 (C=O),
146.32 (N-Ph), 143.89 (C-3), 141.24 (C-5), 140.14 (N-Ph),
132.21, 131.70, 130.99, 130.86, 130.70, 130.64, 130.20, 127.71,
124.54, 121.64, 113.83 (C-4), 64.79 (OCH2), 15.22 ppm (CH3).
Anal.Calcd. for C26H22N4O4: C, 68.71; H, 4.88; N. 12.33. Found:
C, 68.68; H, 4.89; N, 12.34
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