Synthesis, antibacterial, anthelmintic and anti-inflammatory studies of novel methylpyrimidine sulfonylpiperazine derivatives

Article abstract of DOI:10.5935/0103-5053.20140073

A strategic synthesis of novel methylpyrimidine sulfonyl piperazines involving Suzuki coupling was designed and pharmacological activities of the compounds were evaluated. Reactions were carried out under conventional method and show good functional group transformations and high yields. Structures of the newly synthesized compounds were established by infrared spectroscopy (IR), 1H and 13C nuclear magnetic resonance (NMR) and liquid chromatography-mass spectrometry (LC-MS) and elemental analysis. The compounds were tested for in vitro antibacterial activity against Escherichia coli and Staphylococcus aureus bacterial strains, anthelmintic activity using Pheretima posthuma and anti-inflammatory activity involving carrageenan induced rat paw edema model. Some compounds were proven to be potent pharmacophores.

Full text of DOI:10.5935/0103-5053.20140073

http://dx.doi.org/10.5935/0103-5053.20140073
J. Braz. Chem. Soc., Vol. 25, No. 6, 1012-1020, 2014.
Printed in Brazil - ©2014 Sociedade Brasileira de Química
0103 - 5053 $6.00+0.00
Article
A
Synthesis, Antibacterial, Anthelmintic and Anti-Inflammatory Studies of
Novel Methylpyrimidine Sulfonyl Piperazine Derivatives
Nadigar R. Mohan,a Swamy Sreenivasa,*,a Karikere E. Manojkumar,a Tadimety M. C. Rao,b
Boreddy S. Thippeswamyc and Parameshwar A. Suchetana
aDepartment of Studies and Research in Chemistry, Tumkur University, Tumkur 572 103, Karnataka, India
bTadimety Aromatics Pvt. Ltd, Hirehalli Industrial Area, Tumkur 572 168, Karnataka, India
cDepartment of Pharmacology, Sree Siddaganga College of Pharmacy, Tumkur 572 102, Karnataka, India
Uma síntese estratégica de novas piperazinas sulfonil metilpirimidina envolvendo acoplamento
Suzuki foi desenvolvida e as atividades farmacológicas dos compostos foram avaliadas. As
reações foram realizadas pelo método convencional e apresentaram boas transformações dos
grupos funcionais e elevados rendimentos. As estruturas dos novos compostos sintetizados foram
estabelecidas por espectroscopia no infravermelho (IR), ressonância magnética nuclear (NMR) de
1H e de 13C, e cromatografia líquida-espectrometria de massas (LC-MS) e análise elementar. Os
compostos foram testados quanto à atividade antibacteriana in vitro contra as cepas bacterianas
Escherichia coli e Staphylococcus aureus, à atividade antihelmíntica utilizando Pheretima
posthuma e à atividade anti-inflamatória envolvendo o modelo de edema de pata de rato induzido
pela carragena. Provou-se que alguns compostos são farmacóforos potentes.
A strategic synthesis of novel methylpyrimidine sulfonyl piperazines involving Suzuki coupling
was designed and pharmacological activities of the compounds were evaluated. Reactions were
carried out under conventional method and show good functional group transformations and high
yields. Structures of the newly synthesized compounds were established by infrared spectroscopy
(IR), 1H and 13C nuclear magnetic resonance (NMR) and liquid chromatography-mass spectrometry
(LC-MS) and elemental analysis. The compounds were tested for in vitro antibacterial activity
against Escherichia coli and Staphylococcus aureus bacterial strains, anthelmintic activity using
Pheretima posthuma and anti-inflammatory activity involving carrageenan induced rat paw edema
model. Some compounds were proven to be potent pharmacophores.
Keywords: carbon-carbon bond formation, pharmacology, propylphosphonic anhydride,
sulfonyl chlorides, antimicrobial, anti-inflammatory
Introduction
natural products and also in the majority of pharmaceutically
fascinating compounds containing amide bond.2,3 Pyrimidine,
piperazine and sulfonamide derivatives represent a category
of pharmacologically interesting compounds having diverse
biological activities. Intensive research has been carried
out on the synthesis and analysis of pharmacological
activities of these derivatives. Substituted sulfonamide
derivatives are important category of pharmacophores that
have a wide spectrum of pharmaceutical accomplishments:
as antimalarial,4 anti-microbial,5 anti-bacterial,6,7
anti-cancer,8 anti-fungal,9 anti-helmintic,9 anti-oxidant,10
anti-HIV,11 anti-tumor,11 antiplasmodial,12 anti-neoplastic,13
anti-proliferative,14 activities and additionally known to act
as 5-HT6, 5-HT7 receptor antagonists,15,16 A2B and CXCR3
Suzuki-Miyaura coupling involves the cross coupling
of organic halides and organic boron compounds, it is a
strong synthetic tool for carbon-carbon bond formation via
borylation.1 This coupling procedure is used to synthesize
different varieties of biologically necessary intermediates.
Delicate and effective amidation of carboxyl acids with
amines is the most elementary and necessary reaction in
organic synthesis. In nature, amide bond is one of the most
important functional group that constitutes the backbone of
the biologically important peptides and is found in several
*e-mail: drsreenivasa@yahoo.co.in

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Mohan et al.
1013
antagonists,17,18 11β-HSD,19 histone deacetylase (HDAC)
inhibitors,20 β-secretase (BACE1) inhibitors21 and dual
PI3K/mTOR inhibitors.22
Owingtoourinterestindevelopingnewbiologicallyactive
pyrimidine sulfonyl piperazines, our group has previously
reported the new series of substituted methylpyrimidine
piperazine methanones and their biological activities.23
In this article, we are intended to report the synthesis of
methylpyrimidine sulfonyl piperazines. Literature survey
revealed the paucity of information on these functionalities
incorporated in one molecule and their collective biological
significance. Prompted by these facts, it was designed and
synthesized a new series of molecules having all the three
nuclei in a single molecule as shown in Scheme 1 and
studied their communal pharmacological impact as potent
antibacterial, anthelmintic and anti-inflammatory agents.
Experimental
Melting points (mp) reported were determined in open
capillary and are uncorrected. Purification of the newly
synthesized sulfonyl piperazine methanone derivatives
was made by column chromatography using silica gel
60-120 mesh size and petroleum ether/ethyl acetate (7:3)
as solvent system. Reactions were monitored by thin layer
chromatography (TLC), visualization was done using UV
light (254 nm) chamber. Characterization was done by Fourier
transform infrared (FTIR) spectra recorded on a Jasco FT-IR
spectrometer. 1H and 13C nuclear magnetic resonance (NMR)
spectra were recorded at 400 and 100 MHz, respectively, on
a JEOL ECX NMR spectrometer using CDCl3 as solvent and
tetramethylsilane (TMS), respectively, as internal standard.
Liquid chromatogram with mass spectrometry detection
(LC-MS) was obtained on aWatersAlliance 2795 separation
module and Waters Micromass LCT mass detector and
elemental analysis (C, H, N and S) was performed on an
Elementarvario Micro cube analyzer.
Scheme 1. Reagents and conditions: (a) PdCl2(dppf), KOAc/
1,4-dioxane and H2O, 80 °C, 18 h; (b) K2CO3, dikis, dioxane/H2O, ∆, 6 h;
(c) NaOH/THF: H2O, rt, stirred, 7 h; (d) T3P, Et3N/EDC, stirred, ∆, 3 h;
(e) TFA/EDC, stirred, ∆, 6 h; and (f) different substituted sulfonyl chloride,
Et3N/EDC, ∆, 3 h.
under reduced pressure to get crude compound (3) which was
further purified by column chromatography using petroleum
ether: ethyl acetate (7:3) as eluent to get pure ethyl-2-methyl-
6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyrimidine-4-
carboxylate (3) as white crystalline solid; mp 177-178 oC; IR
Synthesis of methyl 2-methyl-6-(4,4,5,5-tetramethyl-
1,3,2-dioxaborolan-2-yl)pyrimidine-4-carboxylate (3)
A mixture of bis(pinacolato)diboron (98 mmol) (2),
dioxane and water (2:1) (183 mL) was stirred at room
temperature under nitrogen atmosphere. To this reaction
mixture, potassium acetate (245 mmol), Pd(dppf)Cl2 in CH2Cl2
(49 mmol) and methyl-6-chloro-2-methylpyrimidine-4-
carboxylate (1) (9.8 mmol) were added and stirred at 80 oC for
18 h. Reaction mixture was then cooled to room temperature,
diluted with ethyl acetate, filtered over celite, washed with
ethyl acetate followed by one water wash. Resulting organic
layer was separated, dried over sodium sulfate concentrated
ν
max/cm-1 1589.2 (CO); 1H NMR (399.6 MHz, CDCl3) d 8.60
(s, 1H,Ar-H), 3.97 (s, 3H, O–CH3), 2.89 (s, 3H,Ar-CH3), 1.37
(s, 12H, (–CH3)4); yield 65%.
Synthesis of methyl 6-(4-chloro-2-(trifluoromethyl) phenyl)-
2-methylpyrimidine-4-carboxylate (5)
A solution of methyl 2-methyl-6-(4,4,5,5-tetramethyl-
1,3,2-dioxa borolan-2-yl)pyrimidine-4-carboxylate (3)

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J. Braz. Chem. Soc.
(89 mmol), dioxane and water (2:1) (183 mL) was
stirred at room temperature under nitrogen atmosphere.
To this reaction mixture, potassium acetate (252 mmol),
bis(triphenylphosphine)palladium(II) dichloride (dikis)
(35 mmol) and 1-bromo-4-chloro-2-(trifluoro methyl)
benzene (4) (89.9 mmol) were added and stirred under
heating for 6 h. Reaction mixture was then cooled to room
temperature, diluted with ethyl acetate, filtered over celite,
washed with ethyl acetate followed with water. Resulting
organic layer was separated, dried over sodium sulfate
concentrated under reduced pressure to get crude compound
(5) which was further purified by column chromatography
using petroleum ether: ethyl acetate (7:3) as eluent to
get pure methyl-6-(4-chloro-2-(trifluoro methyl)phenyl)-
2-methyl pyrimidine-4-carboxylate (5) as white crystalline
solid; mp 199-200 oC; IR νmax/cm-1 1673.2 (CO); 1H NMR
(399.6 MHz, CDCl3) d 8.06 (s, 1H, Ar-H), 7.83 (d, 1H,
J 1.5, Ar-H), 7.69 (dd, 1H, J 8.3, 1.5, Ar-H), 7.50 (d, 1H,
J 8.3, Ar-H), 3.79 (s, 3H, –O–CH3), 2.81(s, 3H, Ar-CH3);
yield 60%.
as eluent to obtain pure 4-(6-(4-chloro-2-(trifluoromethyl)
phenyl)-2-methylpyrimidine-4-carbonyl)piperazine-
1-carboxylate (8) as colorless solid; mp 241-243 oC; 1H NMR
(399.6 MHz, CDCl3) d 7.79 (d, 1H, J 1.9, Ar-H), 7.66 (dd,
1H, J 7.9, 1.9, Ar-H), 7.50 (d, 2H, J 8.7, Ar-H), 3.79 (t,
2H, J 4.3, NCH2), 3.58-3.52 (m, 6H, NCH2, H2C–N–CH2 ),
2.81 (s, 3H, Ar-CH3), 1.48 (s, 9H, –CH3); LC-MS (M + 1)
485.12; yield 88%.
Synthesis of (6-(4-chloro-2-(trifluoromethyl)phenyl)-
2-methylpyrimidin-4-yl)(piperazin-1-yl)methanone (9)
A mixture of 4-(6-(4-chloro-2-(trifluoromethyl)phenyl)-
2-methylpyrimidine-4-carbonyl) piperazine-1-carboxylate
(8) (12 mmol) along with trifluroacetic acid (6 mL) in
ethylene dichloride (60 mL) was refluxed for about 6 h.
Reaction mixture was cooled to room temperature and
concentrated to get deprotected crude 6-(4-chloro-
2-(trifluoromethyl)phenyl)-2-methyl pyrimidin-4-yl)
(piperazin-1-yl)methanone (9) as pale yellow solid which
was taken for next step directly without purification; mp
221-222 oC; 1H NMR (399.6 MHz, CDCl3) d 9.75 (s, 1H,
NH), 7.80 (d, 1H, J 1.9, Ar-H), 7.67 (dd, 1H, J 7.9, 1.9,
Ar-H), 7.61 (s, 1H,Ar-H), 7.50 (d, 1H, J 8.3,Ar-H), 4.11 (t,
4H, J 21.9, H2C–N–CH2 ), 3.34 (t, 4H, J 7.9, H2C–N–CH2),
2.81 (s, 3H, Ar-CH3); LC-MS (M + 1) 385.12; yield 80%.
Synthesis of 6-(4-chloro-2-(trifluoromethyl)phenyl)-
2-methylpyrimidine-4-carboxylic acid (6)
A mixture of methyl 6-(4-chloro-2-(trifluoromethyl)
phenyl)-2-methyl pyrimidine-4-carboxylate (5) (45 mmol)
in aqueous tetrahydrofuran was stirred at room temperature
for 7 h resulting in base hydrolysis. Reaction mixture was
then acidified with 1.5 mol L-1 HCl to precipitate compound
(6). Compound 6-(4-chloro-2-(trifluoromethyl)phenyl)-
2-methyl pyrimidine-4-carboxylic acid (6) was filtered and
dried to get pure colorless solid; mp 221-222 oC; 1H NMR
(399.6 MHz, CDCl3) d 8.06 (s, 1H, Ar-H), 7.83 (d, 1H,
J 1.5, Ar-H), 7.69 (dd, 1H, J 8.3, 1.5, Ar-H), 7.50 (d, 1H,
J 8.3,Ar-H), 2.81(s, 3H,Ar-CH3); LC-MS (M + 1) 317.12;
yield 90%.
General procedure for the synthesis of {6-[4-chloro-
2-(trifluoromethyl)phenyl]-2-methylpyrimidin-4-yl}
[4-(substitutedsulfonyl) piperazin-1-yl]methanone (11a-j)
Equimolar mixture of 6-(4-chloro-2-(trifluoromethyl)
phenyl)-2-methylpyrimidin-4-yl)(piperazin-1-yl)
methanone (9) (1 mmol) and substituted sulfonyl
chlorides (10a-j) (1 mmol) along with triethylamine
(Et3N) (0.003 mmol) in ethylene dichloride (5 mL) was
refluxed for 3 h. Reaction mixture was then cooled to
room temperature, washed with water; organic layer was
separated and dried using sodium sulfate, organic layer
on further concentration yielded pale yellow solid (11a-j).
Crude compound obtained was further purified by column
chromatography using petroleum ether: ethyl acetate (7:3)
as eluent to get the pure {6-[4-chloro-2-(trifluoromethyl)
phenyl]-2-methylpyrimidin-4-yl}[4-(substitutedsulfonyl)
piperazine-1-yl]methanone (11a-j) in good yield.
Synthesis of tert-butyl 4-(6-(4-chloro-2-(trifluoromethyl)
phenyl)-2-methylpyrimidine-4-carbonyl)piperazine-
1-carboxylate (8)
A equimolar mixture of 6-(4-chloro-2-(trifluoromethyl)
phenyl)-2-methylpyrimidine-4-carboxylic acid (6)
(59 mmol) and tert-butyl piperazine-1-carboxylate (7)
(59 mmol) along with propylphosphonic anhydride (T3P®)
(240 mmol), triethylamine (Et3N) (180 mmol) in ethylene
dichloride (200 mL) was refluxed under nitrogen atmosphere
for3h. Reactionmixturewaswashedwithwater, organiclayer
separated, dried and concentrated under vacuum to obtain
crude compound (8) which was further purified by column
chromatography using petroleum ether:ethyl acetate (7:3)
(6-(4-Chloro-2-(trifluoromethyl)phenyl)-2-methyl-
pyrimidin-4-yl)(4(methylsulfonyl) piperazin-1-yl) methanone
(11a): IR νmax/cm-1 C=O 1651.8, S=O 1320.6 (asymmetric),
1
1168.7 (symmetric); H NMR (399.6 MHz, CDCl3) d
7.80 (d, 1H, J 1.9, Ar-H), 7.67 (dd, 1H, J 8.3, 1.9, Ar-H),

Vol. 25, No. 6, 2014
Mohan et al.
1015
7.52 (d, 1H, J 3.9, Ar-H), 7.49 (s, 1H, Ar-H), 3.93 (t, 2H,
J 9.9, N-CH2), 3.73 (t, 2H, J 4.7, N-CH2), 3.46 (t, 2H,
J 5.1, N‑CH2), 3.41 (t, 2H, J 5.1 Hz, N–CH2), 3.91 (s, 3H,
‑SO2–CH3), 2.82 (s, 3H, –CH3); CHNS (calculated, found)
C% 46.71 (46.62), H% 3.92 (3.90), N% 12.10 (12.11), S%
6.93 (6.92); LC-MS (M + 1) 463.8.
(399.6 MHz, CDCl3) d 7.78 (d, 1H, J 1.9, Ar-H), 7.65 (dd,
1H, J 8.3, 1.9 Hz, Ar-H), 7.58-7.56 (m, 2H, Ar-H), 7.49-
7.45 (m, 2H, Ar-H), 7.38-7.33 (m, 1H, Ar-H), 3.92 (t, 2H,
J 5.1, N–CH2), 3.75 (t, 2H, J 4.7, N–CH2), 3.21 (t, J 5.1,
2H, N–CH2), 3.15 (t, 2H, J 5.1, N–CH2), 2.80 (s, 3H, –CH3),
2.41 (s, 3H,Ar-CH3); CHNS (calculated, found) C% 51.76
(51.75), H% 3.80 (3.85), N% 10.06 (10.37), S% 5.76 (5.75);
LC-MS (M + 1) 557.9.
(6-(4-Chloro-2-(trifluoromethyl)phenyl)-2-methyl-
pyrimidin-4-yl)(4-((2,4-dichlorophenyl) sulfonyl) piperazin-1-
yl)methanone (11b): IR νmax/cm-1 C=O 1650.8, S=O 1300.6
(asymmetric), 1164.7 (symmetric); 1H NMR (399.6 MHz,
CDCl3) d 8.04 (dd, 1H, J 5.5, 1.5, Ar-H); 7.79 (d, 1H, J 1.5,
Ar-H); 7.72 (dd, 1H, J 7.9, 1.5, Ar-H); 7.66 (dd, 1H, J 8.3,
1.9, Ar-H); 7.49 (d, 2H, J 9.1, Ar-H); 7.40 (d, 1H, J 7.9,
Ar-H); 3.89 (t, 2H, J 4.7, N–CH2); 3.71 (t, 2H, J 4.3, N‑CH2),
3.49 (t, J 4.7, 4H, N–CH2), 2.80 (s, 3H, –CH3); CHNS
(calculated, found) C% 46.52 (46.54), H% 3.06 (3.07), N%
9.43 (9.42), S% 5.40 (5.39); LC-MS (M + 1) 594.8.
(6-(4-Chloro-2-(trifluoromethyl)phenyl)-2-methyl-
pyrimidin-4-yl)(4-((4-fluorophenyl) sulfonyl)piperazin-1-yl)
methanone (11f): IR νmax/cm-1 C=O 1639.2, S=O 1302.68
1
(asymmetric), 1166.72 cm-1(symmetric); H NMR
(399.6 MHz, CDCl3) d 7.78 (d, 1H, J 1.9, Ar-H), 7.65
(dd, 1H, J 8.3, 1.9, Ar-H), 7.58-7.56 (m, 2H, Ar-H), 7.49-
7.45 (m, 3H, Ar-H), 7.38-7.33 (m, 1H, Ar-H), 3.92 (t, 2H,
J 5.1, N–CH2), 3.75 (t, 2H, J 4.7, N–CH2), 3.21 (t, 2H,
J 5.1, N–CH2), 3.15 (t, 2H, J 5.1, N-CH2), 2.80 (s, 3H,
–CH3); 13C NMR (100 MHz, CDCl3) d 167.74, 165.83,
165.29, 163.77, 161.25, 160.29, 137.50, 136.13, 132.50,
132.14, 131.19, 127.12, 123.35, 120.64, 120.42, 116.70,
115.08, 114.84, 46.37, 46.12, 45.60, 41.65, 26.06; CHNS
(calculated, found) C% 50.88 (50.90), H% 3.53 (3.55),
N% 10.32 (10.36), S% 5.91 (5.98); LC-MS (M + 1) 543.9.
(6-(4-Chloro-2-(trifluoromethyl)phenyl)-2-methyl-
pyrimidin-4-yl)(4-((2,3-dichlorophenyl)sulfonyl) piperazin-1-
yl)methanone (11c): IR νmax/cm-1 C=O 1649.8, S=O 1304.6
(asymmetric), 1166.7 (symmetric); 1H NMR (399.6 MHz,
CDCl3) d 8.04 (dd, 1H, J 5.5, 1.5, Ar-H), 7.79 (d, 1H,
J 1.5, Ar-H), 7.72 (dd, 1H, J 7.9, 1.5, Ar-H), 7.66 (dd, 1H,
J 8.3, 1.9, Ar-H), 7.49 (d, 2H, J 9.1, Ar-H), 7.40 (t, 1H,
J 7.9, Ar-H), 3.89 (t, 2H, J 4.7, N–CH2), 3.71 (t, 2H, J 4.3,
N–CH2), 3.49 (t, 4H, J 4.7, N-CH2), 2.80 (s, 3H, –CH3);
13C NMR (100 MHz, CDCl3) d 167.70, 165.80, 165.37,
160.40, 138.10, 136.07, 135.34, 134.75, 132.48, 132.11,
130.58, 130.58, 130.33, 129.80, 127.30, 127.08, 124.25,
121.52, 116.75, 46.98, 45.89, 45.37, 42.20, 26.04; CHNS
(calculated, found) C% 46.52 (46.57), H% 3.06 (3.09),
N% 9.43(9.46), S% 5.40 (5.45); LC-MS (M + 1) 594.8.
(6-(4-Chloro-2-(trifluoromethyl)phenyl)-2-methyl-
pyrimidin-4-yl)(4-((2,5-dimethoxyphenyl) sulfonyl) piperazin-
1-yl)methanone (11g): IR νmax/cm-1 C=O 1632.45, S=O
1
1303.64 (asymmetric), 1154.19 (symmetric); H NMR
(399.6 MHz, CDCl3) d 7.78 (d, 1H, J 1.9, Ar-H), 7.66 (dd,
1H, J 8.3, 1.9,Ar-H), 7.49-7.43 (m, 3H,Ar-H), 7.10 (dd, 1H,
J9.1, 3.1,Ar-H), 6.9 (d, 1H, J8.7,Ar-H), 3.89 (s, 3H, O–CH3),
3.80 (s, 3H, O–CH3), 3.65 (t, 4H, J 4.7, CH2–N–CH2), 3.42
(t, 4H, J 4.7 Hz, CH2–N–CH2), 2.79 (s, 3H, –CH3); 13C NMR
(100 MHz, CDCl3) d167.79, 165.68, 165.40, 160.62, 153.07,
150.88, 136.07, 135.36, 132.51, 132.14, 127.01, 126.46,
124.28, 121.54, 120.55, 116.59, 116.02, 114.01, 56.59,
55.96, 47.04, 46.08, 45.60, 42.29, 26.06; CHNS (calculated,
found) C% 51.33 (51.35), H% 4.14 (4.17), N% 9.58 (9.60),
S% 5.48 (5.50); LC-MS (M + 1) 585.9.
(6-(4-Chloro-2-(trifluoromethyl)phenyl)-2-methyl-
pyrimidin-4-yl)(4-((2,6-dichlorophenyl) sulfonyl) piperazin-1-
yl)methanone (11d): IR νmax/cm-1 C=O 1633.8, S=O 1310.6
(asymmetric), 1162.7 (symmetric), 1H NMR (399.6 MHz,
CDCl3) d 8.04 (dd, 1H, J 5.5, 1.5,Ar-H), 7.79 (d, 1H, J 1.59,
Ar-H), 7.72 (dd, 1H, J 7.9, 1.5, Ar-H), 7.66 (dd, 1H, J 8.3,
1.9,Ar-H), 7.49 (d, 2H, J9.1,Ar-H), 7.40 (t, 1H, J7.9,Ar-H),
3.89 (t, J 4.7, 2H, N–CH2), 3.71 (t, 2H, J 4.3, N–CH2),
3.49 (t, 4H, J 4.7, N–CH2), 2.80 (s, 3H, –CH3); CHNS
(calculated, found) C% 46.52 (46.54), H% 3.06 (3.04),
N% 9.43 (9.40), S% 5.40 (5.43); LC-MS (M + 1) 594.8.
(6-(4-Cloro-2-(trifluoromethyl)phenyl)-2-methyl-
pyrimidin-4-yl)(4-((5-methylisoxazol-4-yl)sulfonyl) piperazin-
1-yl)methanone (11h): IR νmax/cm-1 C=O 1635.85, S=O
1
1308.94 (asymmetric), 1164.49 (symmetric); H NMR
(399.6 MHz, CDCl3) d 8.30 (s, 1H, isoxazole proton), 8.06
(s, 1H,Ar-H), 7.83 (d, 1H, J 1.5,Ar-H), 7.69 (dd, 1H, J 8.3,
1.5,Ar-H), 7.50 (d, 1H, J 8.3,Ar-H), 2.88 (s, 3H, isoxazole
–CH3), 2.81(s, 3H,Ar-CH3); CHNS (calculated, found) C%
47.60 (47.65), H% 3.61 (3.63), N% 13.22 (13.24), S% 6.05
(6.09); LC-MS (M + 1) 530.9.
(6-(4-Chloro-2-(trifluoromethyl)phenyl)-2-methyl-
pyrimidin-4-yl)(4-((3-fluoro-4-methyl phenyl)sulfonyl)
piperazin-1-yl)methanone (11e): IR νmax/cm-1 C=O 1623.7,
S=O 1308.4 (asymmetric), 1165.6 (symmetric); 1H NMR

1016
Synthesis, Antibacterial, Anthelmintic and Anti-Inflammatory Studies of Novel Methylpyrimidine
J. Braz. Chem. Soc.
(6-(4-Chloro-2-(trifluoromethyl)phenyl)-2-methyl-
appropriate amount of sample, control and standard. Then,
the plates were incubated at 37 °C for 36 h. After the
incubation period, the diameter of the zone of inhibition
of each well was measured in mm; the experiment was
performed in triplicates.
pyrimidin-4-yl)(4-(cyclopropylsulfonyl) piperazin-1-yl)
methanone (11i): IR νmax/cm-1 C=O 1653.66, S=O 1306.54
(asymmetric), 1165.76 (symmetric); 1H NMR (399.6 MHz,
CDCl3) d 7.80 (d, 1H, J 1.9, Ar-H), 7.67 (dd, 1H, J 8.3,
1.9, Ar-H), 7.52 (d, 1H, J 3.9, Ar-H), 7.49 (s, 1H, Ar-H),
3.93 (t, 2H, J 9.9, N–CH2), 3.73 (t, 2H, J 4.7, N–CH2), 3.46
(t, 2H, J 5.1, N–CH2), 3.41 (t, 2H, J 5.1, N–CH2), 2.82 (s,
3H, –CH3), 2.32-2.26 (m, 1H, junction proton), 1.21-1.01
(m, 4H, (–CH2–)2); 13C NMR (100 MHz, CDCl3) d 167.77,
165.81, 165.41, 160.49, 136.11, 135.36, 132.51, 132.15,
127.16, 124.28, 121.55, 116.76, 46.80, 46.25, 45.75, 42.04,
26.08, 25.71, 4.40, 4.40; CHNS (calculated, found) C%
49.13 (49.16), H% 4.12 (4.16), N% 11.46 (11.50), S% 6.56
(6.60); LC-MS (M + 1) 489.8.
Anthelmintic activity
Anthelmintic activity of compounds (11a-j) was done
using P. posthuma (Indian Earthworm), worms were
maintained under normal vermicomposting medium
with adequate supply of nourishment and water for
about 3 weeks. Adult earthworms of approximately
4 cm in length and 0.2-0.3 cm in width were chosen for
experiment. Different concentrations 50 and 100 mg
of samples were evaluated as per the standard method
reported.25 Five groups, each with six earth worms,
were taken. Each P. posthuma was washed separately
with normal saline before the initiation of experimental
procedure and was placed into a 20 mL of normal saline.
Group I earthworms were placed in 20 mL saline in a
clean petri plate and group II earthworms were placed in
20 mL saline containing standard drug piperazine citrate
(50 mg mL-1). Similarly, group III to XXII earthworms
were placed in a 20 mL saline containing 50 and
100 mg mL-1 of test samples, respectively. Observation
was done keeping time taken for paralysis and the time
taken for death as objective and was documented in
minutes. Paralysis time was analyzed based on behavior
of the worms with no revival body state in normal saline
medium. Death was concluded based on total loss of
motility with faded body color.26
(6-(4-Chloro-2-(trifluoromethyl)phenyl)-2-methyl-
pyrimidin-4-yl)(4-(isopropylsulfonyl) piperazin-1-yl)
methanone (11j): IR νmax/cm-1 C=O 1655.67, S=O 1305.56
(asymmetric), 1166.78 (symmetric); 1H NMR (399.6 MHz,
CDCl3) d 7.80 (d, 1H, J 1.9, Ar-H); 7.67 (dd, 1H, J 8.3,
1.9, Ar-H), 7.52 (d, 1H, J 3.9, Ar-H), 7.49 (s, 1H, Ar-H),
3.93 (t, 2H, J 9.9, N–CH2), 3.73 (t, 2H, J 4.7, N–CH2), 3.46
(t, 2H, J 5.1, N–CH2), 3.41 (t, 2H, J 5.1, N–CH2), 2.82 (s,
3H, –CH3), 2.32-2.26 (m, 1H, junction proton), 1.4 (d,
J 1.9, 4H, (–CH3)2); CHNS (calculated, found) C% 48.93
(48.92), H% 4.52 (4.53), N% 11.41 (11.43), S% 6.53 (6.53);
LC-MS (M + 1) 491.9.
Biological evaluation
Antibacterial activity
In vitro antibacterial activity of the sulfonyl piperazine
methanone derivatives (11a-j) was studied against Gram
positive Staphylococcus aureus (NCIM-5022) and Gram
negative Escherichia coli (NCIM-5051) bacterial strains.
All the bacterial strains were procured form CSIR-National
Chemical Laboratory (NCL) (Pune, India). Agar well
diffusion method was incorporated for the study,24 broth
cultures of bacterial strains were incubated for 24 h and
were uniformly smeared on sterile nutrient agar medium
in each petri plates using sterile L-shaped glass rod. Five
uniform wells with 6 mm diameter were bored using cork
borer to accommodate 50 µL of solution in each well.
Samples were dissolved in dimethylsulfoxide (DMSO), a
negative control which showed no zone of inhibition and
ciprofloxacin (10 µg 50 µL-1) was taken as standard drug,
a positive control was purchased from Himedia (Mumbai,
India). Concentrations of 2.5, 5, 10 and 20 µg 50 µL-1 were
used to assess the dose dependent activity of test samples.
Sterile micropipette tips were used to load the wells with
Anti-inflammatory activity
Effect of compounds (11a-e) on carrageenan induced
paw edema was studied on albino Wistar rats of either
sex which were obtained from Sree Venkateshwara
Enterprises Bangalore. The animals were acclimatized,
maintained under standard laboratory condition for a
week. Given free access to UV purified and filtered
water and standard pelleted feed procured from M/S
Pranava Agro Industries Sangli, Maharastra, ad libitum.
All the studies conducted were approved by the
Institutional Animal Ethics Committee (IAEC) of Sree
Siddaganga College of Pharmacy, Tumkur (Ref No.
SSCPT/IAEC.Clear/141/2012-13). The standard was
indomethacin from Research Lab Fine Chem Industries,
(B. No. 99550509, Mfg date: May 2009, exp. date: May
2014). Test compounds (100 mg kg-1 body weight) and
indomethacin (10 mg kg-1 body weight). The dose selected
in the present study is done on the previously published
literature which dealt with pyrimidine, piperazine and

Vol. 25, No. 6, 2014
Mohan et al.
1017
sulfonamide as moieties in molecules exhibiting
anti-inflammatory activity.27,28 Test compounds were made
it into suspension by using 1% carboxy methyl cellulose
(vehicle) and administered through oral route.
a pre-final product. Compound (9) revealed to be the
important intermediate which was reacted with appropriate
substituted aryl/alkyl/hetro-substituted sulfonyl chlorides
to get pyrimidine sulfonyl piperazine derivatives (11a-j) in
good yield as reported in Table 1.
Carrageenan induced rat paw edema29 experiment was
carried out on test system (albino Wistar rats) weighing
between 150-180 g randomly divided into seven groups
of six animals each and was fasted overnight. Group I
served as carrageenan inducer (control) and received
vehicle, group II standard indomethacin (10 mg kg-1 body
weight) through oral route. Group III to group VII were
administrated with test compounds (11a-e) in the dose of
(100 mg kg-1 body weight) and after administering samples/
indomethacin/vehicle, test systems were kept under clinical
sign observation for 30 min and suspension of carrageenan
(0.1 mL of 1% kg m-3) was injected into the sub-plantar
region of right hind paw of each test system. The paw
volume was measured by using digital plethysmometer
(IITc Life science, USA), immediately after injection, again
at 30, 60, 120 and 180 min intervals.
Table 1. Physical and analytical data of methylpyrimidine sulfonyl
piperazine derivatives 11a-j
Molecular
formula
Molecular
weight
R
mp / oC Yield / %
C18H18ClF3N4O3S
462
187-189
219-221
92
91
C23H18Cl3F3N4O3S
593
C23H18Cl3F3N4O3S
C23H18Cl3F3N4O3S
593
593
220-222
218-220
90
92
Statistical analysis
C24H21ClF4N4O3S
556
237-239
95
The data of antibacterial and anthelmintic were
expressed as mean standard error (SE) of triplicates and
six Pheretima posthuma in each group. The difference in
values at p ≤ 0.01 was considered as statistically significant.
The analysis of variance (ANOVA) was performed using
ezANOVA (version 0.98) software to determine the
mean and standard error of the inhibition zone in antibacterial
activity and standard error of paralysis and death time of
earthworms. Anti-inflammatory data were expressed as
mean standard error of the mean (SEM) of seven groups
of six albino Wistar rats in each group, the difference in
values at p < 0.05, p < 0.01 and p < 0.001 when compared
with carrageenan control usingANOVA followed by Dunnett
multiple comparison test on Graph Pad Prism 5.
C23H19ClF4N4O3S
C25H24ClF3N4O5S
542
584
244-246
249-251
96
93
C21H19ClF3N5O4S
C20H20ClF3N4O3S
529
488
248-250
224-226
91
94
C20H22ClF3N4O3S
490
217-219
92
Initial investigation of the antibacterial screening data
Results and Discussion
revealed that all tested compounds (11a-j) showed activity
against E. coli and P. aeruginosa, data given in Table 2. Test
samples upon detailed investigation for activity at different
concentrations of 2.5, 5, 10 and 20 µg 50 µL-1 against
E. coli and P. aeruginosa, respectively, given in Table 3.
Minimum inhibitory concentrations (MIC) obtained by
micro dilution method were observed to be 10 µg 50 µL-1.
Data reveal that the tested samples are active at and
above the concentration level 10 µg 50 µL-1 which is the
minimum inhibitory concentration. Further the compounds
were screened at 10 and 20 µg 50 µL-1 against E. coli and
P. aeruginosa, respectively and it is evident that all the
tested compounds showed activity against tested strains.
The synthetic pathway for the synthesis of compounds
(11a-j) is illustrated in Scheme 1. Initial borylation of (1)
with (2), in presence of Pd(dppf)Cl2, methylene chloride,
potassium acetate and 1,4-dioxane and water afforded
(3). Treatment of (3) with (4) in 1,4-dioxane:water using
potassium carbonate and catalytic quantity of dikis,
underwent Suzuki coupling to give (5). Upon hydrolysis
of (5), it gave (6) and it was further condensed with (7) in
presence of triethylamine and dehydrating agent T3P® to
get (8) a key intermediate. Deprotection of N-boc group
from (8) was done by using trifluroacetic acid to get (9)

1018
Synthesis, Antibacterial, Anthelmintic and Anti-Inflammatory Studies of Novel Methylpyrimidine
J. Braz. Chem. Soc.
study at different concentrations 15, 25, 35 and 50 mg mL-1,
shown in Table 5, it was observed activity at concentration
of 50 mg mL-1 and above. Further testing of samples at
50 mg mL-1 and 100 mg mL-1 concentrations showed the time
(in min) of paralysis and death as reported. Investigation of
anthelmintic activity revealed that methylpyrimidine sulfonyl
piperazines were potent anthelmintic agents.
Table 2. Antibacterial activity of methylpyrimidine sulfonyl piperazine
derivatives 11a-j
Zone of inhibition / mm
Concentration /
Code
E. coli
P. aeruginosa
(µg 50 µL-1)
(mean SE)
(mean SE)
CIPRO
10
10
20
10
20
10
20
10
20
10
20
10
20
10
20
10
20
10
20
10
20
13.00 0.58
4.67 0.33b
5.67 0.33b
6.50 0.29b
7.17 0.17b
6.17 0.22b
7.17 0.38b
4.50 0.29b
5.50 0.29b
3.50 0.29b
4.50 0.29b
5.50 0.29b
6.57 0.30b
5.83 0.44b
6.97 0.03b
3.83 0.17b
4.83 0.70b
5.50 0.29b
4.17 0.44b
6.67 0.33b
4.17 0.44b
14.17 0.17
2.17 0.17b
2.83 0.44b
2.50 0.29b
2.83 0.60b
2.33 0.33b
3.50 0.29b
2.83 0.44b
3.50 0.29b
3.33 0.44b
4.33 0.33b
3.67 0.33b
4.50 0.29b
2.67 0.17b
3.17 0.44b
4.50 0.29b
5.67 0.33b
3.67 0.17b
4.67 0.33b
3.50 0.58b
4.17 0.33b
11a
Table 4. Anthelmintic activity of methylpyrimidine sulfonyl piperazine
derivatives 11a-j
11b
11c
11d
11e
11f
11g
11h
11i
Code
Concentration /
(mg mL-1)
Time taken for
paralysis / min
Time taken for
death / min
Control
PC
–
142.33 0.49
39.17 0.48b
74.33 0.42b
37.50 0.62a
72.67 0.71b
40.83 0.48b
69.00 0.73b
41.17 0.70b
70.83 0.60b
38.67 0.56b
61.33 0.71b
41.33 0.49b
64.17 0.48b
42.67 0.71b
59.17 0.48b
33.17 0.48b
72.00 0.97b
41.50 0.43b
68.17 0.60b
41.50 0.43b
71.83 0.65b
38.67 0.56b
165.33 1.58
57.67 0.88b
102.67 0.56b
53.83 0.79b
96.00 1.12b
53.00 0.58b
97.33 1.12b
53.00 1.29b
98.67 0.76b
54.17 0.75b
104.33 0.71b
55.50 1.09
102.83 1.19b
57.00 0.86
110.50 0.67b
59.67 0.42a
103.00 0.89b
54.67 0.49b
105.33 0.61b
54.67 0.49b
107.23 0.51b
53.83 0.79b
50
11a
50
100
50
11b
11c
11d
11e
11f
11g
11h
11i
100
50
100
50
100
50
100
50
11j
100
50
CIPRO: standard drug ciprofloxacin; ap < 0.05, bp < 0.01 and cp < 0.001;
SE: standard error.
100
50
100
50
Table 3. Antibacterial activity minimum inhibitory concentration (MIC)
values of methylpyrimidine sulfonyl piperazine derivatives 11a-j
100
50
Concentration /
(µg 50 µL-1)
11j
Bacterial stain
Code
Growth
100
2.5
5.0
10
+
+
–
–
PC: standard drug piperazine citrate; ap < 0.05, bp < 0.01 and cp < 0.001.
E. coli
11a-j
Table 5. Anthelmintic activity values of methylpyrimidine sulfonyl
piperazine derivatives 11a-j
20
2.5
5.0
10
+
+
–
–
P. aeruginosa
11a-j
Concentration /
(mg mL-1)
Test model
Code
Activity
20
15
25
35
50
IA
IA
IA
+: presence of growth; –: absence of growth.
P. posthuma
11a-j
AC
Evaluation of anthelmintic activity using P. posthuma
showed comparably moderate results with that of standard
drug piperazine citrate, given in Table 4. Earthworms
belonging to control group showed paralysis time at
142.67 1.45 min and death time at 168.00 1.53 min. For
the sample tests (11a-j) upon detailed anthelmintic activity
AC: active; IA: inactive.
Increase in paw volume was observed in all time
intervals after the administration of carrageenan (1%,
0.1 mL). Samples (11a-e) were administered orally to test

Vol. 25, No. 6, 2014
Mohan et al.
1019
systems at dose of 100 mg kg-1 body weight, significantly
(p < 0.05, p < 0.01 and p < 0.001) inhibited the carrageenan
(control) induced paw edema. Treatment with standard
drug indomethacin also significantly (p < 0.001) inhibited
the carrageenan induced paw edema. At 30 min interval,
no significance was observed for all the tested compounds
against carrageenan induced paw edema.At 60 min interval,
for compounds 11a, 11b, 11d and 11e, it was moderately
significance (p < 0.01), in addition at 120 min interval for
compounds 11a and 11c, it was also showed moderate
significance (p < 0.01). Finally, results obtained at 180 min
interval were comparably significance (p < 0.001) to
standard drug indomethacin (Figure 1).
Supplementary Information
Supplementary data are available free of charge at
http://jbcs.sbq.org.br as PDF file.
Acknowledgments
The authors are thankful to Tumkur University for
providing laboratory facilities.Authors are also thankful to
Sapala Organics Private Limited for spectral data.
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Submitted: January 20, 2014
Published online: April 11, 2014