Microwave-accelerated and Catalyst-free Synthesis of Novel tris-(Pyrazolyl)methanes

Full text of DOI:10.1080/00304948.2016.1206426

Organic Preparations and Procedures International
The New Journal for Organic Synthesis
ISSN: 0030-4948 (Print) 1945-5453 (Online) Journal homepage: http://www.tandfonline.com/loi/uopp20
Microwave-accelerated and Catalyst-free Synthesis
of Novel tris-(Pyrazolyl)methanes
Maryam Beyrati & Alireza Hasaninejad
To cite this article: Maryam Beyrati & Alireza Hasaninejad (2016) Microwave-accelerated and
Catalyst-free Synthesis of Novel tris-(Pyrazolyl)methanes, Organic Preparations and Procedures
International, 48:5, 393-400, DOI: 10.1080/00304948.2016.1206426
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Date: 22 September 2016, At: 00:10

Organic Preparations and Procedures International, 48:393–400, 2016
Copyright Ó Taylor & Francis Group, LLC
ISSN: 0030-4948 print / 1945-5453 online
DOI: 10.1080/00304948.2016.1206426
Microwave-accelerated and Catalyst-free Synthesis
of Novel tris-(Pyrazolyl)methanes
Maryam Beyrati and Alireza Hasaninejad
Department of Chemistry, Faculty of Sciences, Persian Gulf University, Bushehr
75169, Iran
Pyrazole derivatives constitute an important family of compounds due to their applica-
tions as pharmaceuticals, agrochemicals and dyestuffs.1–3 For example, 2,4-dihydro-3H-
pyrazol-3-one derivatives have a broad spectrum of approved biological activity, being
used as anti-bacterial,4 anti-inflammatory,5 anti-depressant,6 gastric secretion stimula-
tory,7 and anti-filarial agents.8 Moreover, applications of pyrazole containing compounds
as ligands in coordination chemistry are well-documented in the literature.9–11
tris-(Pyrazolyl)methane (Tm) and tris-(pyrazolyl)borate (Tp) have been extensively
investigated in inorganic, bio-inorganic and organometallic chemistry, partly due to their
close analogy to cyclopentadienyl ligands.12–14 tris-(Pyrazolyl)methane is a versatile
ligand that complexes with groups 1–14 metals such as Li, Na, Ce, Ti, V, Cr, Mo, W,
Mn, Fe, Os, Ru, CO, Rh, Cu, Ag, Al, Sn.14–15 Several of these complexes are potent cata-
lysts for reactions such as olefin polymerization,16 carbene transfer,17 and oxidation of
alkanes.18 An important feature of the tris-(pyrazolyl)methane ligand is the possibility to
modify the steric and/or electronic properties by judicious selection of the substituents.19
Some tris-(pyrazolyl)methane complexes show interesting physico-chemical proper-
ties with significance in areas which span catalysis to magnetic materials,15 thus constitut-
ing an emerging field of research. In recent years, microwave-assisted synthesis has
evolved into a popular branch of synthetic organic chemistry,20, 21 as it helps in minimiz-
ing the energy consumption needed for heating as well as time required for the reaction to
be complete.22, 23 In particular, microwave heating when coupled with catalyst-free strat-
egy,24 presents a powerful and green alternative to conventional synthesis. Moreover,
multi-component reactions are effective methods in the sustainable and diversity-oriented
synthesis of a wide variety of useful heterocycles.25 In continuation of our interest on cat-
alyst-free and multi-component organic reactions,26–38 we now report a simple and effi-
cient method for the synthesis of novel tris-(pyrazolyl)methane derivatives via a pseudo
five-component condensation (Scheme 2) of hydrazine derivatives (2 eq.) and b-ketoest-
ers (2 eq.) with highly substituted 1H-pyrazole-4-carbaldehydes (1 eq.) under catalyst-
free conditions and microwave irradiation. The pyrazolones 1a-1d were obtained from
the reaction of 1,3-dicaronyl compounds with arylhydrazines under microwave irradiation
and regioselectively formylated at the C-4 position using the Vilsmeier-Haack reaction to
afford the corresponding 1-aryl-5-chloro-3-methyl-1H-pyrazole-4-carbaldehyde 2a-d
Received February 22, 2016; in final form June 6, 2016.
Address correspondence to Alireza Hasaninejad, Department of Chemistry, Faculty of Scien-
ces, Persian Gulf University, Bushehr 75169, Iran. E-mail: a_hasaninejad@yahoo.com
393

394
Beyrati and Hasaninejad
R3
R3
CHO
Cl
DMF/POCl3
90 °C- 4 h
MW
N
R3COCH2CO2Et + ArNHNH2
N
O
N
Ar
N
Ar
400 W, 110 °C
5 min
2 (a-d)
1 (a-d)
a) R3= Me, Ar = C6H5 . b) R3= Me, Ar = 4-OMe-C6H4 .
c) R3= C6H5, Ar = C6H5 . d) R3= Me, Ar = 4-Br-C6H4 .
Scheme 1
(Scheme 1).39 In order to determine the best conditions for the reaction of the pyrazole-
carbaldehydes (2) to 3, the condensation of 5-chloro-3-methyl-1-phenyl-1H-pyrazole-4-
carbaldehyde (2a, 1 mmol) with phenylhydrazine (2 mmol) and ethyl acetoacetate
(2 mmol) was conducted as a model under microwave irradiation under different micro-
wave powers (300, 400 and 500 W) and the reaction temperature (80, 100, 110 and
120ꢀC) under catalyst-free conditions. The results are summarized in Table 1. Table 1
indicates that the best results were obtained at 400 W of microwave power and 110ꢀC of
temperature (Entry 4). Increasing the temperature did not improve the yield and the reac-
tion time whereas the yield of product decreased when the temperature was less than
110ꢀC (Entries 2, 4–6). To compare thermal heating with microwave irradiation, the reac-
tion model was also examined at 110ꢀC under thermal conditions. As is evident in
Table 1, Entry 7, the yield of product is less than 45% even after 3 hours of heating.
R1COCH2CO2Et
R1
R1
N
N
+
R2NHNH2
+
R2
R2
N
N
catalyst-free
DMSO (one drop)
HO
Cl
OH
R3
R3
MW, 400 W
110 °C
CHO
N
N
Ar
N
Cl
N
3 (a-k)
Ar
2
a)R1 = Me, R2 = C6H5, R3 = Me, Ar = C6H5.
b) R1 = Me, R2 = 4-Br-C6H4, R3 = Me, Ar = C6H5.
d) R1 = Me, R2 = H, R3 = Me, Ar = 4-OMe-C6H4.
f) R1 = C6H5, R2 = H, R3 = Me, Ar = C6H5.
h) R1 = Me, R2 = H, R3 = Me, Ar = C6H5.
c) R1 = n-Pr, R2 = H, R3 = Me, Ar = C6H5.
e) R1 = Me, R2 = H, R3
= Me, Ar = 4-Br-C6H4.
g)R1 = Me, R2 = 4-OMe-C6H4, R3 = C6H5, Ar = C6H5.
i) R1 = Me, R2 = 4-OMe-C6H4, R3 = Me, Ar = C6H5.
k)R1 = Me, R2 = 4-OMe-C6H4, R3 = Me, Ar = 4-Br-C6H4.
j) R1 = C6H5, R2 = H, R3 = Me, Ar = 4-OMe-C6H4.
Scheme 2

Catalyst-free Synthesis of Novel tris-(Pyrazolyl)methanes
395
Table 1
Effect of Microwave and Temperature on the Condensation of 5-Chloro-3-methyl-1-phe-
nyl-1H-pyrazole-4-carbaldehyde with Phenylhydrazine and Ethyl Acetoacetate
Entry
MW Power (W)
Temp. (ꢀC)
Time (min)
Yield (%)
1
2
3
4
5
6
7
500
400
300
400
400
400
–
110
100
110
110
120
80
5
5
92
94
5
80
97
5
5
97
85
5
180
110
<45
To assess the efficiency and the scope of our method, hydrazine derivatives (2 mmol)
were treated with b-ketoesters (2 mmol) and various 1H-pyrazole-4-carbaldehydes
(1 mmol) under the optimized reaction conditions (Scheme 2). The results displayed in
Table 2 show that a variety of 1H-pyrazole-4-carbaldehydes, b-ketoesters and hydrazine
derivatives were successfully applied in this process to afford the corresponding novel
tris(pyrazolyl)methane derivatives 3 in high yields and short reaction times.
Table 2
Microwave-assisted Catalyst-free Synthesis of tris(Pyrazolyl)methanes from the Reaction
of 1H-Pyrazole-4-carbaldehydes with Arylhydrazines and b-Ketoesters
Time Yield
Product mp (ꢀC). (min) (%)
Entry R1
R2
R3
Me
Ar
1
2
Me
Me
C6H5
4-BrC6H4
C6H5
C6H5
C6H5
3a
3b
3c
3d
3e
3f
201–204
197–199
214–216
199–201
195–197
183–185
181–183
209–211
221–223
226–228
173–175
5
6
5
5
4
7
6
4
4
9
4
97
92
94
95
96
91
94
92
96
94
97
Me
Me
Me
Me
Me
3
4
n-Pr
Me
H
H
H
H
4-MeO-C6H4
4-Br-C6H4
C6H5
5
Me
6
7
8
C6H5
Me
Me
4-OMe-C6H4 C6H5 C6H5
3g
3h
3i
3j
3k
H
Me
4-OMe-C6H4 Me
Me
4-OMe-C6H4 Me
C6H5
C6H5
9
10
11
Me
C6H5
Me
H
4-MeO-C6H4
4-Br-C6H4
Our proposed mechanism for the synthesis of novel tris(pyrazolyl)methane deriva-
tives under microwave irradiation is shown in Scheme 3. On the basis of this mechanism,
firstly a condensation of hydrazine derivative with b-ketoester is proposed to give the
intermediate A. Then, the intermediate C is likely formed via the condensation of 1H-Pyr-
azole-4-carbaldehyde with B, which is the tautomer of A. The next step is a Michael addi-
tion of another intermediate of B to C to yield adduct D. Finally, after the tautomeric
proton shift, the desired product 3 is formed.

396
Beyrati and Hasaninejad
R1
O
O
R1
N
O
R1
MW
MW
EtO
R2NHNH2
NHR2
N
O
(A)
-EtOH
N
-H2O
R2
EtO
Ar
N
R3
Cl
R1
Cl
N
R1
O
HO
N
N
R3
N
R1
H
R3
R1
+
Ar
N
N
HO
MW
MW
N
N
N
R2
+
-H2O
O
R2
N
N
O
Cl
OH
N
R2
N
Ar
R2
(C)
(B)
R1
R1
R1
N
R1
N
N
N
O
N
N
R2
R2
R2
R2
N
N
N
N
OH
R3
HO
Cl
OH
Cl
R3
N
N
Ar
Ar
(3)
(D)
Scheme 3
Experimental Section
Chemicals were purchased from Merck or Fluka Chemical Co. All reactions were carried in
laboratory microwave oven (MicroSYNTH, Milestone Company, Italy). The 1H NMR
(400 MHz) and 13C NMR (100 MHz) were carried out on a Bruker Avance 400. Melting
€
points were recorded on a Buchi B-545 apparatus in open capillary tubes and are uncorrected.
3-Methyl-1-phenyl-1H-pyrazol-5(4H)-one (1a). Typical Procedure. A thoroughly
ground mixture of phenylhydrazine (0.098 mL,1 mmol) and ethyl acetoacetate
(0.128 mL, 1 mmol), was subjected to 400 W microwave irradiation. The microwave
was programmed to give a maximum internal temperature of 110ꢀC for 5 min. After,
cooling, the product was washed with ethyl acetate and then dried to provide 0.155 gr
(89%) of 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one (1a) as an off-white solid.
5-Chloro-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde (2a). Typical Procedure.
Phosphorus oxychloride (18.4 mL, 0.2 mol) was added dropwise to cold dimethylforma-
mide (15.5 mL, 0.2 mol) over a period of 30 min; stirring (stir bar) was continued for
further 45 min with the temperature of the reaction mixture maintained at 0ꢀC Then
3-methyl-1-phenyl-1H-pyrazol-5(4H)-one (1a, 6.968 g, 0.04 mol) was added and the
reaction mixture was allowed to rise room temperature. The mixture was then heated at
90ꢀC for 4 h, allowed to cool and poured onto mixture of crushed ice and water. The
precipitates obtained were collected, dried and the crude solid was purified by column
chromatography (n-hexane/ethyl acetate 10:4) to afford 0.166 g. (75%) of 5-chloro-
3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde (2a).
4-[(5-Chloro-3-methyl-1-phenyl-1H-pyrazol-4-yl)(5-hydroxy-3-methyl-1-phenyl-1H-
pyrazol-4-yl)methyl]-3-methyl-1-phenyl-1H-pyrazol-5-ol (3a). Typical Procedure. To a

Catalyst-free Synthesis of Novel tris-(Pyrazolyl)methanes
397
mixture of phenylhydrazine (0.197 mL, 2 mmol) and ethyl acetoacetate (0.255 mL,
2 mmol) was added 5-chloro-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde (2a, 0.220 g,
1 mmol) in a 5 mL microwave vessel. The resulting mixture was irradiated in a microwave
oven at 400 W power. The microwave was programmed to give a maximum internal tem-
perature of 110ꢀC. The reaction mixture was irradiated for 5 min. After the completion of
the reaction, the mixture was cooled to room temperature, 3 mL of water was added, and
the resulting solid was collected and recrystallized from hot ethanol to afford 0.534 gr
(97%) of 4-[(5-chloro-3-methyl-1-phenyl-1H-pyrazol-4-yl)(5-hydroxy-3-methyl-1-phenyl-
1H-pyrazol-4-yl)methyl]-3-methyl-1-phenyl-1H-pyrazol-5-ol (3a).
5-Chloro-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde (2a), white crystalline
1
solid, mp. 114–116ꢀC (115–117ꢀC)40, H NMR (DMSO-d6, 400 MHz): d 2.57 (s, 3H),
7.48–7.59 (m, 5H), 10.00 (s, 1H). 13C NMR (DMSO-d6, 100 MHz): d 13.85,117.43,
125.22, 125.59, 129.18, 129.22, 129.30, 133.50, 136.97, 151.81, 183.92. MS: m/e (%):
219 (100), 155 (16), 77 (60), 51 (48).
4-[(5-Chloro-3-methyl-1-phenyl-1H-pyrazol-4-yl)(5-hydroxy-3-methyl-1-phenyl-
1H-pyrazol-4-yl)methyl)]-3-methyl-1-phenyl-1H-pyrazol-5-ol (3a), white powder,
1
mp. 202–204ꢀC, H NMR (DMSO-d6, 400 MHz): d 2.05 (s, 3H), 2.30 (s, 6H), 4.96 (s,
1H), 7.24–7.28 (m, 2H), 7.44–7.52 (m, 9H), 7.72 (d, J D 8.0 Hz, 4H), 12.55 (s, 1H),
13.68 (s, 1H). 13C NMR (DMSO-d6, 100 MHz): d 14.12, 25.38, 117.24, 121.07, 124.48,
125.39, 126.11, 128.47, 129.44, 129.57, 138.39, 146.54, 148.44.
Anal. Calcd for C31H27ClN6O2: C, 67.57; H, 4.94; N, 15.25. Found: C, 67.77; H,
5.02; N, 15.18.
1-(4-Bromophenyl)-4-((1-(4-bromophenyl)-5-hydroxy-3-methyl-1H-pyrazol-4-
yl)(5-chloro-3-methyl-1-phenyl-1H-pyrazol-4-yl)methyl)-3-methyl-1H-pyrazol-5-ol
1
(3b), cream powder, mp. 197–199ꢀC, H NMR (DMSO-d6, 400 MHz): d 1.93 (s, 3H),
2.04 (s, 6H), 4.78 (s, 2H), 5.19 (s, 1H), 7.38 (t, J D 7.4 Hz, 1H), 7.57–7.63 (m, 4H),
7.73–7.77 (m, 8H). 13C NMR (DMSO-d6, 100 MHz): d 13.08, 22.85, 100.15, 119.30,
121.05, 121.50, 122.68, 127.04, 129.98, 132.21, 132.76, 137.17, 137.82, 146.53, 146.62,
147.15, 148.20.
Anal. Calcd for C31H25Br2ClN6O2: C, 52.53; H, 3.55; N, 11.86. Found: C, 52.73; H,
3.28; N, 11.66.
4-((5-Chloro-3-methyl-1-phenyl-1H-pyrazol-4-yl)(5-hydroxy-3-propyl-1H-pyra-
zol-4-yl)methyl)-3-propyl-1H-pyrazol-5-ol (3c), cream powder, mp. 214–216ꢀC, 1H
NMR (DMSO-d6, 400 MHz): d 0.53–0.59 (m, 2H), 0.71 (s, 3H), 0.82–0.85 (m, 2H),
1.31–1.49 (m, 3H), 1.88–1.91 (m, 4H), 2.27–2.30 (m, 3H), 3.38 (s, 2H), 3.99 (s, 1H),
7.28–7.31 (m, 1H), 7.49–7.52 (m, 2H), 7.69–7.71 (m, 2H), 12.14 (s, 2H). 13C NMR
(DMSO-d6, 100 MHz): d 13.99, 21.73, 26.72, 26.94, 99.57, 100.26, 103.11, 120.73,
125.29, 126.45, 129.80, 138.40, 141.10, 146.74, 147.38, 157.00, 159.00.
Anal. Calcd for C23H27ClN6O2: C, 60.72; H, 5.98; N, 18.47%. Found: C, 60.38; H,
5.91; N, 18.99%.
4-((5-Chloro-1-(4-methoxyphenyl)-3-methyl-1H-pyrazol-4-yl)(5-hydroxy-3-methyl-
1H-pyrazol-4-yl)methyl)-3-methyl-1H-pyrazol-5-ol (3d), cream-colored powder, mp.
199–201ꢀC, 1H NMR (DMSO-d6, 400 MHz): d 1.72 (s, 3H), 1.92 (s, 6H), 3.38 (s, 2H), 3.78
(s, 3H), 4.88 (s,1H), 7.48–7.50 (m, 1H), 7.56–7.58 (m, 3H), 8.54 (s, 2H). 13C NMR (DMSO-
d6, 100 MHz): d 25.75, 57.13, 60.01, 100.28, 101.26, 101.84, 106.42, 107.52, 124.21,
128.02, 128.45, 143.51, 150.27, 156.45.
Anal. Calcd for C20H21ClN6O3: C, 56.01; H, 4.94; N, 19.60. Found: C, 56.23; H,
5.03; N, 19.41.

398
Beyrati and Hasaninejad
4-((1-(4-Bromophenyl)-5-chloro-3-methyl-1H-pyrazol-4-yl)(5-hydroxy-3-methyl-
1H-pyrazol-4-yl)methyl)-3-methyl-1H-pyrazol-5-ol (3e), cream powder, mp. 195–
197ꢀC, 1H NMR (DMSO-d6, 400 MHz): d 1.92 (s, 6H), 2.01 (s, 3H), 3.35 (s, 2H), 4.88 (s,
1H), 7.43–7.47 (m, 1H), 7.69–7.71 (m, 3H), 12.13 (s, 2H).13C NMR (DMSO-d6,
100 MHz): d 25.75, 57.13, 101.64, 107.43, 113.25, 124.46, 126.09, 126.87, 128.32, 144.26,
150.23, 158.49.
Anal. Calcd for C19H18BrClN6O2: C, 47.77; H, 3.80; N, 17.59%. Found: C, 47.90; H,
3.86; N, 17.28%.
4-((5-Chloro-3-methyl-1-phenyl-1H-pyrazol-4-yl)(5-hydroxy-3-phenyl-1H-pyra-
zol-4-yl)methyl)-3-phenyl-1H-pyrazol-5-ol (3f), yellow powder, mp.183–185ꢀC, 1H
NMR (DMSO-d6, 400 MHz): d 1.98 (s, 3H), 3.93 (s, 2H), 5.50 (s, 1H), 7.19–7.29 (m,
7H), 7.43–7.52 (m, 6H), 7.63–7.65 (m, 2H), 12.68 (s, 2H).
Anal. Calcd for C29H23ClN6O2: C, 66.60; H, 4.43; N, 16.07%. Found: C, 66.72; H,
4.31; N, 16.21%.
4-((5-Chloro-1,3-diphenyl-1H-pyrazol-4-yl)(5-hydroxy-1-(4-methoxyphenyl)-
3-methyl-1H-pyrazol-4-yl)methyl)-1-(4-methoxyphenyl)-3-methyl-1H-pyrazol-5-ol
1
(3g), cream powder, mp.181–183ꢀC, H NMR (DMSO-d6, 400 MHz): d 2.05 (s, 3H),
2.48 (s, 3H), 3.72–3.88 (m, 8H), 5.5 (s, 1H), 6.91–6.94 (m, 2H), 7.06–7.11 (m, 2H),
7.38–7.44 (m, 6H), 7.60–7.66 (m, 4H), 7.76–7.86 (m, 4H).
Anal. Calcd for C38H33ClN6O4: C, 67.80; H, 4.94; N, 12.48%. Found: C, 67.56; H,
4.86; N, 12.69%.
4-((5-Chloro-3-methyl-1-phenyl-1H-pyrazol-4-yl)(5-hydroxy-3-methyl-1H-pyra-
1
zol-4-yl)methyl)-3-methyl-1H-pyrazol-5-ol (3h), cream powder, mp. 209–211ꢀC, H
NMR (DMSO-d6, 400 MHz): d 1.91 (s, 6H), 2.35 (s, 3H), 3.99 (s, 2H), 5.11 (s, 1H),
7.29–7.32 (m, 1H), 7.50–7.52 (m, 2H), 7.70–7.72 (m, 2H), 12.25 (s, 2H).
Anal. Calcd for C19H19ClN6O2: C, 57.22; H, 4.80; N, 21.07%. Found: C, 57.43; H,
4.54; N, 20.89%.
4-((5-Chloro-3-methyl-1-phenyl-1H-pyrazol-4-yl)(5-hydroxy-1-(4-methoxyphenyl)-
3-methyl-1H-pyrazol-4-yl)methyl)-1-(4-methoxyphenyl)-3-methyl-1H-pyrazol-5-ol (3i),
1
brown powder, mp. 221–223ꢀC, H NMR (DMSO-d6, 400 MHz): d 2.00 (s, 3H), 2.16 (s,
6H), 3.79 (s, 6H), 5.20 (s, 1H), 6.06 (s, 2H), 7.04–7.09 (m, 5H), 7.23–7.61 (m, 4H), 7.70–
7.72 (m, 4H).
Anal. Calcd for C33H31ClN6O4: C, 64.86; H, 5.11; N, 13.75%. Found: C, 64.67; H,
5.18; N, 13.62%.
4-((5-Chloro-1-(4-methoxyphenyl)-3-methyl-1H-pyrazol-4-yl)(5-hydroxy-3-phe-
nyl-1H-pyrazol-4-yl)methyl)-3-phenyl-1H-pyrazol-5-ol (3j), white powder, mp. 226–
228ꢀC, 1H NMR (DMSO-d6, 400 MHz): d 1.78 (s, 3H), 1.97 (s, 3H), 3.62 (s, 2H), 5.00 (s,
1H), 6.92–7.04 (m, 2H), 7.07–7.11 (m, 2H), 7.15–7.17 (m, 2H), 7.24–7.28 (m, 4H), 7.29–
7.33 (m, 2H), 7.37–7.42 (m, 2H), 12.60 (s, 2H). 13C NMR (DMSO-d6, 100 MHz): d
13.54, 55.87, 103.10, 114.54, 117.48, 126.92, 128.14, 128.98, 130.76, 131.48, 147.86,
148.02, 149.07, 159.10.
Anal. Calcd for C30H25ClN6O3: C, 65.16; H, 4.56; N, 15.20%. Found: C, 65.38; H,
4.29; N, 15.01%.
4-((1-(4-Bromophenyl)-5-chloro-3-methyl-1H-pyrazol-4-yl)(5-hydroxy-1-(4-methox-
yphenyl)-3-methyl-1H-pyrazol-4-yl)methyl)-1-(4-methoxyphenyl)-3-methyl-1H-pyrazol-
5-ol (3k), cream powder, mp. 173–175ꢀC, 1H NMR (DMSO-d6, 400 MHz): d 1.99 (s, 3H),
2.49 (s, 6H), 3.82 (s, 6H), 4.39 (s, 1H), 5.12 (s, 2H), 6.96–7.03 (m, 2H), 7.11–7.21 (m, 4H),
7.58–7.73 (m, 6H). 13C NMR (DMSO-d6, 100 MHz): d 13.03, 55.77, 55.95, 100.12, 109.68,
114.47, 115.03, 122.37, 122.81, 132.74, 137.23, 146.36, 147.85, 158.52.

Catalyst-free Synthesis of Novel tris-(Pyrazolyl)methanes
399
Anal. Calcd for C33H30BrClN6O4: C, 57.44; H, 4.38; N, 12.18%. Found: C, 57.08; H,
4.31; N, 12.67%.
Acknowledgements
The authors thank Persian Gulf University Research Councils for financial support of this
work.
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