Synthesis, characterization, and antimicrobial screening of some Mannich base sydnone derivatives

Article abstract of DOI:10.1007/s00044-013-0568-6

The title compounds (5a-j), (6a-j), and (7a-j) were prepared via a four-step procedure using starting material 4-methoxyaniline (1). The structure of all synthesized compounds was confirmed by FT-IR, ¹H NMR, ¹³C NMR, and CHN analysis. The synthesized compounds were tested for their antibacterial and antifungal activity (MIC) in vitro against organisms viz. B. subtilis, S. aureus, E. coli, P. aeruginosa, and C. albicans taking ciprofloxacin, ampicillin, streptomycin, penicillin-G, fluconazole, and nystatin as the standard drugs. Some of the compounds have shown significant activities.

Full text of DOI:10.1007/s00044-013-0568-6

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res
DOI 10.1007/s00044-013-0568-6
ORIGINAL RESEARCH
Synthesis, characterization, and antimicrobial screening
of some Mannich base sydnone derivatives
•
Piyush P. Savaliya Vikunjana K. Akbari
•
•
Jigisha A. Modi Keshav C. Patel
Received: 17 October 2012 / Accepted: 2 March 2013
Ó Springer Science+Business Media New York 2013
Abstract The title compounds (5a–j), (6a–j), and (7a–j)
were prepared via a four-step procedure using starting
material 4-methoxyaniline (1). The structure of all syn-
niak and Jazwinski, 1995; Papageorgiou et al., 1983),
chemical properties (Satoshi et al., 2004), and synthetic
utility (Jogul and Badami, 2006). A hydrogen atom at the
4th position of the sydnone ring allows substitution with a
wide variety of electrophiles, such as bromination, nitra-
tion, acylation, and sulfonation. It seems to be possible to
substitute the 4th position by electron-releasing groups
such as the methylene group by Mannich reaction (Tien
et al., 1981). A large number of sydnone derivatives have
been synthesized as they serve as vital biologic agents viz,
antibacterial, antifungal (Bansode and Kamble, 2012; Patel
and Asundaria, 2012), antitumor (Marija et al., 2011), anti-
oxidant (Shih and Ke, 2004), anticancer (Satyanarayana
et al., 2004), anti-inflammatory, analgesic, and antiviral
(Kamble et al., 2009; Deshpande and Pai, 2012; Pandey
and Mukesh, 2006) activities.
1
thesized compounds was confirmed by FT-IR, H NMR,
13C NMR, and CHN analysis. The synthesized compounds
were tested for their antibacterial and antifungal activity
(MIC) in vitro against organisms viz. B. subtilis, S. aureus,
E. coli, P. aeruginosa, and C. albicans taking ciprofloxa-
cin, ampicillin, streptomycin, penicillin-G, fluconazole,
and nystatin as the standard drugs. Some of the compounds
have shown significant activities.
Keywords Sydnone ꢀ Benzothiazole ꢀ Benzimidazole ꢀ
Mannich ꢀ Antimicrobial activity
Introduction
Benzothiazoles have drawn attention as promising
structural units in the field of medicinal chemistry. They
were reported to exhibit a variety of biologic activities such
as anti-HIV (Hadizadeh and Mehrparvar, 2004), anti-
inflammatory, analgesic (Venkatesh and Pandeya, 2009a;
Hosni and Abdulla, 2008), antifungal (Pattan and Narendra
babu, 2002), antibacterial (Vibhute, 2001), antitumor
(Yuichi, 2005), antitubercular (Amini et al., 2008), anti-
cancer (Devmurari et al., 2010), etc.
Mesoionic compounds are heterocyclic betaines that are
very useful in medicinal chemistry because of their well-
known range of pharmacological activities and low toxic-
ity. Sydnones are the most important class of mesoionic
compounds because they possess different physiologic
activities depending on the substituent in the heterocyclic
ring (Greco et al.,1962; Yeh et al.,1989). Sydnones have
attained importance due to their unusual structure (Stefa-
Benzimidazole nucleus is an important heterocyclic ring
because of its synthetic utility and broad range of phar-
macological activities like antibacterial, antifungal (Sanja
et al., 2007; Lal et al., 2011), antitubercular (Joshi et al.,
2001), anticonvulsant (Srivastava et al., 2000), antide-
pressant (Sharma et al., 1999), etc.
Therefore, we focused our attention on the synthesis of
some sydnones and their Mannich derivatives containing
benzothiazole and benzimidazole moieties with a view to
evaluate their antibacterial and antifungal activity.
P. P. Savaliya ꢀ V. K. Akbari ꢀ J. A. Modi ꢀ K. C. Patel (&)
Department of Chemistry, Veer Narmad South Gujarat
University, Surat, Gujarat, India
e-mail: savaliyapiyush25@gmail.com
123

Med Chem Res
Results and discussion
The structures of all the synthesized compounds were
confirmed by elemental analysis and spectral studies. The
IR spectra of compound 4 showed two characteristic bands
at 3,112 and 1,749 cm-1 due to the C–H and [C=O
stretching of the sydnone, and 1H NMR (DMSO d6) spectra
of compound 4 showed a singlet at d 3.89 ppm due to the
methoxy and d 7.21 ppm, characteristic of the proton at C4
of the sydnone. The absence of a sharp band at around
3,112 cm-1 is due to the formation of Mannich bases in
title compounds.
Chemistry
The synthesis of methylene-based sydnones containing ben-
zothiazoles (5a–j), benzimidazoles (6a–j), and 18 amines
(7a–j) derivatives is shown in the Scheme 1. Synthesis of
3-(4-methoxyphenyl)sydnone(4) was accomplished by a three-
step procedure. Compound (4) was reacted with paraformal-
dehyde, benzothiazoles, benzimidazoles, and 18 amines to give
(5a–j), (6a–j), and (7a–j) as shown in Scheme 1.
The IR spectrum of compounds (5a–j), (6a–j), and (7a–
j) displayed absorption bands between 1,760 and 1,718 cm-1
,
Substituted benzothiazoles (Venkatesh and Pandeya,
2009b) and benzimidazoles (Messmary et al., 2010) were
synthesized by the reported process.
which is characteristic of the carbonyl group of sydnones and
also showed 1,250–1,210, 1,050–1,010, and 2,940–2,850 cm-1
Scheme 1 Synthetic route of
compound 5a–j, 6a–j, and 7a–j
O
ClCH2COOH
NH2
NH
H3CO
H3CO
OH
2N NaOH, reflux
1
2
O
NaNO2
Ac2O
N
H3CO
OH
0-5 oC
R.T.
O
N
3
H
O
N
H3CO
O
N
4
ethanol
paraformaldehyde
H
N
S
N
NH2
NH2
R
R
R
N
OCH3
N
N
R
R
O
H2
C
NH
H2C
N
N
O
O
N
CH2
HN
S
N
N
O
R
H3CO
N
O
H3CO
N
O
(5a-j)
(6a-j)
(7a-j)
123

Med Chem Res
characteristic of C–O–Casy, C–O–Csym, and CH2 groups,
respectively. Some additional peaks appear due to the sub-
stitution in the aromatic ring showing an absorption band
at 2,238 cm-1 (C:N), 1,650–1,490 cm-1 (NO2 asy), 1,360–
1,310 cm-1 (NO2 sym), 1,350–1,120 cm-1 (C–F), 850–800
cm-1 (C–Cl), and 690–510 cm-1 (C–Br). Furthermore, in
1H NMR spectra, common signals are in the range of d
5.0–4.72 ppm for (NH) group, d 3.82–3.98 ppm for (OCH3)
group, and d 3.26–3.6 ppm for (–CH2–) group. 13C NMR
spectra exhibited confirmatory signals for the carbonyl carbon
around d 169.00 ppm, methoxy carbon around d 56.75 ppm,
and methylene carbon around d 51 ppm.
Benzothiazole and 18 amine containing sydnones showed
good activity as compared to benzimidazole containing
sydnone derivatives.
It should be noted that 4-nitro benzothiazole containing
sydnone showed good activity against all bacterial and
fungal strains.
Most of the compounds were found to have good
activity against Gram-positive bacterial strains and fungal
strains as compared to Gram-negative bacterial strains.
Experimental
Antimicrobial activity
All the melting points reported are uncorrected and were
recorded using an electro-thermal melting point apparatus.
Elemental analysis (C, H, N) was performed on Thermo
Scientific FLASH 2000 at G.N.F.C. (Gujarat Narmada
Valley Fertilizer Company Ltd., Bharuch). Infrared spectra
was recorded with a Thermo Scientific Nicolet iS10 FT-IR
Spectrophotometer at the Department of Chemistry, Veer
Narmad South Gujarat University, in the frequency range
4,000–400 cm-1 with samples embedded in KBr disks.
Proton nuclear magnetic resonance (1H NMR) spectra of
the compound were recorded with a Bruker Avance II 400
NMR and carbon (13C) NMR spectra of the compounds
were recorded with a Bruker Avance II 400 NMR spec-
trometer using DMSO-d6 as a solvent and tetramethylsilane
(TMS) as an internal reference at sophisticated analytical
instrument facilities (SAIF), Chandigarh. Thin-layer chro-
matography analyses were performed using aluminum-
backed silica-gel plates (Merck 60 F524) and examined
under short wave ultraviolet (UV) light.
All of the synthesized compounds were tested for their
antibacterial and antifungal activity on four important
bacterial stains (Gram-positive bacteria Bacillus subtilis
and Staphylococcus aureus and Gram-negative bacteria
Escherichia coli and Pseudomonas aeruginosa) and one
fungal strain (Candida albicans), taking ciprofloxacin,
ampicillin, streptomycin, penicillin-G, fluconazole, and
nystatin as the standard drugs. Most of the compounds have
shown antibacterial and antifungal activity.
Compound 5d (R = 4-NO2) is most active against all
bacterial and fungal strains, whereas compound 5f (R = 6-
NO2), 5j (R = CN), and 7g (R = 4-OC2H5) displayed
excellent activity against Gram-positive bacteria B. subtilis
and S. aureus. Compound 5 g (R = 6-CH3) is most active
only against Gram-positive bacteria B. subtilis and com-
pound 6j (R = 2-NO2) is most active only against Gram-
positive bacteria S. aureus. Compound 6i (R = 4-NO2) is
most active against Gram-negative bacteria E. coli compared
with the standard drugs ciprofloxacin and ampicillin. Com-
pound 5c, 5h, 7a, and 7g showed moderate to good activity
and the rest of compounds were moderate to less active
against these species as compared to the standard drugs.
Antifungal screening data showed that compound 5d
(R = 4-NO2) exhibited high activity and compound 5c and
7d (R = 6-Br and 4-Cl) showed excellent activity against
C. albicans. Compound 5b, 5f–h, and 5i (R = 6-Cl,
6-NO2, 6-CH3, 6-OCH3, and 6-OC2H5) showed good
activity and the rest of the compounds were moderate to
less active against C. albicans compared to the standard
drugs fluconazole and nystatin.
The general procedure for synthesis of the compounds
(5a–j, 6a–j, and 7a–j)
Synthesis of 2-((4-methoxyphenyl)amino)acetic acid (2)
This step, a condensation, involved neutralizing an aqueous
solution of chloroacetic acid (0.94 g, 0.01 mol) with an
equimolar equivalent of 2 N NaOH and adding this solu-
tion to an aqueous solution of 4-methoxy aniline (1.23 g,
0.01 mol) over a period of 4 h. This reaction mixture was
heated for 12 h and the clear liquor was then vacuum fil-
tered while hot to remove any decomposition product and
refrigerated overnight. The resulting crystals were again
filtered to obtain compound 2. Yield 82 %, m.p.
130–135 °C. IR: (KBr) m (cm-1): 3,470 (O–H of acid),
1,770 ([C=O of acid), 1,600, 1,509 (C=C of aromatic),
1,242, 1,047 (C–O–C of methoxy); 1H NMR (DMSO-d6): d
(ppm): 3.82 (s, 3H, OCH3), 4.11 (s, 2H, CH2), 9.3 (s, 1H,
COOH), 6.56 (s, 1H, NH), 6.88–7.23 (m, 4H, Ar–H); 13C
Conclusions
Various benzothiazole, benzimidazole, and 18 amine
substituted Mannich base sydnones were synthesized,
characterized by spectral data, elemental analysis, and
evaluated for their antimicrobial activity.
123

Med Chem Res
4-(((substitutedbenzo[d]thiazol-2-yl)amino)methyl)-3-(4-
methoxyphenyl)-sydnone (5a–j)
NMR (DMSO-d6): d (ppm): 45.92, 55.73, 114.32, 118.26,
139.10, 150.07, 172.08.
(5a) IR: (KBr) m (cm-1): 3,260 (NH), 2,917, 2,850 (–CH2–),
1,746 ([C=O of sydnone), 1,237, 1,040 (C–O–C of meth-
Synthesis of 2-((4-methoxyphenyl)(nitroso)amino)acetic
acid (3)
1
oxy), 1,173 (C–F); H NMR (DMSO-d6): d (ppm): 3.32
(s, 2H, CH2), 3.89 (s, 3H, OCH3), 4.90 (s, 1H, NH),
6.92–7.86 (m, 7H, Ar–H); 13C NMR (DMSO-d6): d (ppm):
51.10, 56.75, 108.32, 113.61, 116.20, 117.54, 124.92,
130.75, 132.10, 138.95, 148.61, 157.60, 159.95, 170.14,
175.40; Anal. Calcd. for C17H13FN4O3S: C, 54.83; H, 3.52;
N, 15.05. Found: C, 54.71; H, 3.49; N, 15.01.
To an ice-cooled solution of 2 (1.81 g, 0.01 mol) in 40 ml
of water, a solution of (0.69 g, 0.01 mol) sodium nitrite in
5 ml of water was added drop by drop with stirring. After
stirring for another 2 h and leaving the solution to stand
overnight, the reaction mixture was filtered through a
Buckner funnel, and the nitroso compound was precipitated
by adding concentrated hydrochloric acid to the filtrate.
Yellowish needles were obtained as product, yield 78 %,
m.p. 101–105 °C. IR: (KBr) m (cm-1): 3,450 (O–H of
acid), 1,763 ([C=O of acid), 1,614, 1,513 (C=C of aro-
matic), 1,570, 1,328 (N=O), 1,242, 1,047 (C–O–C of
(5b) IR: (KBr) m (cm-1): 3,265 (NH), 2,924, 2,864
(–CH2–), 1,753 ([C=O of sydnone), 1,240, 1,047 (C–O–C
1
of methoxy), 757 (C–Cl); H NMR (DMSO-d6): d (ppm):
3.38 (s, 2H, CH2), 3.87 (s, 3H, OCH3), 4.95 (s, 1H, NH),
7.10–8.20 (m, 7H, Ar–H); 13C NMR (DMSO-d6): d (ppm):
52.20, 55.89, 115.95, 118.32, 120.95, 125.90, 128.95,
130.24, 132.33, 137.65, 150.92, 162.88, 169.25, 174.90;
Anal. Calcd. for C17H13N4O3ClS: C, 52.51; H, 3.37; N,
14.41. Found: C, 52.45; H, 3.32; N, 14.38.
1
methoxy); H NMR (DMSO-d6): d (ppm): 3.82 (s, 3H,
OCH3), 3.95 (s, 2H, CH2), 9.0 (s, 1H, COOH), 6.91–7.47
(m, 4H, Ar–H); 13C NMR (DMSO-d6): d (ppm): 55.62,
62.42, 115.29, 121.19, 134.66, 159.9, 172.92.
(5c) IR: (KBr) m (cm-1): 3,274 (NH), 2,933, 2,887
(–CH2–), 1,757 ([C=O of sydnone), 1,228, 1,046 (C–O–C
of methoxy), 596 (C–Br); H NMR (DMSO-d6): d (ppm):
Synthesis of 3-(4-methoxyphenyl)sydnone (4)
1
3.29 (s, 2H, CH2), 3.94 (s, 3H, OCH3), 4.86 (s, 1H, NH),
6.82–7.89 (m, 7H, Ar–H); 13C NMR (DMSO-d6): d (ppm):
51.75, 56.20, 116.20, 117.32, 118.45, 123.92, 124.95,
127.85, 130.87, 132.81, 138.98, 151.90, 163.24, 168.70,
175.22; Anal. Calcd. for C17H13N4O3BrS: C, 47.12; H,
3.02; N, 12.93. Found: C, 47.15; H, 2.99; N, 12.89.
A mixture of 3 (2.65 g, 0.0126 mol) and acetic anhydride
(15 ml) was stirred at room temperature for 12 h in the
dark. The solution was poured slowly into cold water
which was very well stirred. The pH of the content was
adjusted to 7.0 with 10 % sodium bicarbonate solution.
The crude sydnone obtained was washed well with water
and dried. Recrystallization from 95 % ethanol afforded a
yield of 98 % of light yellow needles, m.p. 120–124 °C.
IR: (KBr) m (cm-1): 3,112 (C–H of sydnone), 1,749 ([C=O
(5d) IR: (KBr) m (cm-1): 3,257 (NH), 2,917, 2,847
(–CH2–), 1,752 ([C=O of sydnone), 1,550, 1,356 (–NO2),
1,254, 1,048 (C–O–C of methoxy); 1H NMR (DMSO-d6): d
(ppm): 3.35 (s, 2H, CH2), 3.83 (s, 3H, OCH3), 4.98 (s, 1H,
NH), 6.92–8.05 (m, 7H, Ar–H); 13C NMR (DMSO-d6): d
(ppm): 52.32, 57.30, 115.91, 122.33, 125.10, 125.60,
126.82, 128.20, 130.74, 137.82, 142.92, 144.90, 163.22,
168.92, 174.88; Anal. Calcd. for C17H13N5O5S: C, 51.12;
H, 3.28; N, 17.54. Found: C, 51.05; H, 3.22; N, 17.47.
(5e) IR: (KBr) m (cm-1): 3,267 (NH), 2,930, 2,851
(–CH2–), 1,747 ([C=O of sydnone), 1,533, 1,365 (–NO2),
1,237, 1,056 (C–O–C of methoxy); 1H NMR (DMSO-d6): d
(ppm): 3.28 (s, 2H, CH2), 3.84 (s, 3H, OCH3), 4.93 (s, 1H,
NH), 7.10–8.34 (m, 7H, Ar–H); 13C NMR (DMSO-d6): d
(ppm): 52.30, 56.72, 116.24, 117.42, 119.34, 122.74,
124.92, 130.92, 136.80, 139.21, 146.82, 149.84, 163.54,
169.34, 174.62; Anal. Calcd. for C17H13N5O5S: C, 51.12;
H, 3.28; N, 17.54. Found: C, 51.07; H, 3.21; N, 17.49.
(5f) IR: (KBr) m (cm-1): 3,283 (NH), 2,937, 2,865
(–CH2–), 1,754 ([C=O of sydnone), 1,521, 1,327 (–NO2),
1,212, 1,048 (C–O–C of methoxy); 1H NMR (DMSO-d6): d
(ppm): 3.32 (s, 2H, CH2), 3.89 (s, 3H, OCH3), 4.89 (s, 1H,
NH), 7.09–8.54 (m, 7H, Ar–H); 13C NMR (DMSO-d6): d
1
of sydnone), 1,249, 1,040 (C–O–C of methoxy); H NMR
(DMSO-d6): d (ppm): 3.89 (s, 3H, OCH3), 7.21 (s, 1H,
sydnone), 7.48–8.25 (m, 4H, Ar–H); 13C NMR (DMSO-
d6): d (ppm): 55.8, 121.19, 123.4, 134.66, 159.9, 172.92.
General synthesis of compounds 5a–j, 6a–j and 7a–j
A mixture of compound 4 (1.29 g, 0.00679 mol), 0.25 gm
paraformaldehyde, substituted benzothiazoles, substituted
benzimidazoles, and substituted 18 amines (0.084 mol) was
added to 10 ml of acetic acid and 10 ml ethanol and the
whole mixture was heated at (70 °C) for 3 h. After cooling,
ethanol was distilled and 20 ml of water was added and
neutralized with aqueous sodium bicarbonate to afford the
crude product. Recrystallization from 95 % ethanol yielded
55–60 % of compounds 5a–j, 6a–j, and 7a–j as crystalline
solid.
All the sydnone derivatives were prepared by the same
method. Their physical constants and antimicrobial activity
are given in Tables 1 and 2, respectively.
123

Med Chem Res
Table 1 Physical constant of the synthesized compounds
Compound
R
Yield (%)
MP (°C)
Molecular formula
C17H13N4O3FS
Molecular weight
5a
5b
5c
5d
5e
5f
6-F
61
64
70
72
80
68
82
75
85
82
74
69
65
69
55
59
61
65
54
62
58
63
62
69
65
72
68
74
62
70
125–128
105–108
120–123
100–103
205–208
215–218
95–98
372.37
388.83
433.28
399.38
399.38
399.38
368.41
384.41
398.44
379.39
322.32
467.30
467.30
428.44
477.31
477.31
432.86
473.44
443.41
443.41
327.33
342.31
342.31
331.75
376.20
311.34
341.36
331.75
366.20
315.30
6-Cl
C
17H13N4O3ClS
17H13N4O3BrS
6-Br
C
4-NO2
C17H13N5O5S
C17H13N5O5S
C17H13N5O5S
C18H16N4O3S
C18H16N4O4S
C19H18N4O4S
5-NO2
6-NO2
5g
5h
5i
6-CH3
6-OCH3
6-OC2H5
6-CN
162–165
122–125
111–114
136–139
188–191
125–128
155–158
138–141
112–115
185–188
152–155
181–184
178–181
105–108
156–159
138–141
122–125
108–111
118–121
121–124
131–134
115–118
128–131
5j
C
C
C
C
18H13N5O3S
6a
6b
6c
6d
6e
6f
H
17H14N4O3
3,4-di Cl Ph
2,4-di Cl Ph
4-OCH3 Ph
2-Br Ph
3-Br Ph
4-Cl Ph
3-NO2, 4-OCH3 Ph
4-NO2
23H16N4O3Cl2
23H16N4O3Cl2
C24H20N4O4
C23H17N4O3Br
C23H17N4O3Br
C23H17N4O3Cl
6g
6h
6i
C24H19N5O6
C23H17N5O5
C23H17N5O5
C17H17N3O4
C16H14N4O5
C16H14N4O5
6j
2-NO2
7a
7b
7c
7d
7e
7f
4-OCH3
4-NO2 Ph
2-NO2 Ph
4-Cl
C
16H14N3O3Cl
16H14N3O3Br
4-Br
C
4-CH3
C17H17N3O3
C18H19N3O4
7g
7h
7i
4-OC2H5
2-Cl
C16H14N3O3Cl
C16H13N3O3Cl2
C16H14N3O3F
2,5-di Cl
4-F
7j
(ppm): 51.92, 57.20, 116.44, 117.34, 119.12, 121.32,
125.34, 130.89, 131.22, 138.74, 144.24, 160.22, 162.81,
168.21, 175.24; Anal. Calcd. for C17H13N5O5S: C, 51.12;
H, 3.28; N, 17.54. Found: C, 51.10; H, 3.24; N, 17.50.
(5g) IR: (KBr) m (cm-1): 3,281 (NH), 2,986 (–CH3),
2,940, 2,853 (–CH2–), 1,743 ([C=O of sydnone), 1,241,
1,037 (C–O–C of methoxy); 1H NMR (DMSO-d6): d
(ppm): 2.42 (s, 3H, CH3), 3.34 (s, 2H, CH2), 3.81 (s, 3H,
OCH3), 4.95 (s, 1H, NH), 6.80–8.00 (m, 7H, Ar–H); 13C
NMR (DMSO-d6): d (ppm): 51.44, 56.82, 116.22, 117.22,
121.34, 125.24, 126.72, 131.10, 131.82, 134.20, 138.70,
149.82, 162.89, 169.71, 174.24; Anal. Calcd. for
C18H16N4O3S: C, 58.68; H, 4.38; N, 15.21. Found: C,
58.72; H, 4.34; N, 15.18.
6.89–8.12 (m, 7H, Ar–H); 13C NMR (DMSO-d6): d (ppm):
51.44, 56.82, 116.22, 117.22, 121.34, 125.24, 126.72,
131.10, 131.82, 134.20, 138.70, 149.82, 162.89, 169.71,
174.24; Anal. Calcd. for C18H16N4O4S: C, 56.24; H, 4.20;
N, 14.57. Found: C, 56.20; H, 4.18; N, 14.51.
(5i) IR: (KBr) m (cm-1): 3,257 (NH), 2,976 (–CH3),
2,937, 2,848 (–CH2–), 1,742 ([C=O of sydnone), 1,253,
1,054 (C–O–C of methoxy); 1H NMR (DMSO-d6): d
(ppm): 1.40 (t, 3H, CH3), 3.35 (s, 2H, CH2), 3.83 (q, 2H,
OCH2), 3.90 (s, 3H, OCH3), 4.92 (s, 1H, NH), 7.05–8.48
(m, 7H, Ar–H); 13C NMR (DMSO-d6): d (ppm): 14.80,
51.90, 56.82, 64.60, 105.12, 114.22, 116.23, 117.82,
125.22, 130.21, 131.45, 139.22, 144.72, 152.84, 163.62,
168.40, 175.23; Anal. Calcd. for C19H18N4O4S: C, 57.27;
H, 4.55; N, 14.06. Found: C, 57.21; H, 4.50; N, 14.01.
(5j) IR: (KBr) m (cm-1): 3,270 (NH), 2,937, 2,851
(–CH2–), 2,238 (C:N), 1,754 ([C=O of sydnone), 1,253,
1,034 (C–O–C of methoxy); 1H NMR (DMSO-d6): d
(5h) IR: (KBr) m (cm-1): 3,272 (NH), 2,921, 2,857
(–CH2–), 1,737 ([C=O of sydnone), 1,249, 1,063 (C–O–C
1
of methoxy); H NMR (DMSO-d6): d (ppm): 3.26 (s, 2H,
CH2), 3.83, 3.98 (s, 6H, OCH3), 4.80 (s, 1H, NH),
123

Med Chem Res
Table 2 Antibacterial and antifungal activity of synthesized compounds
Compound
Minimum inhibition concentration (l/ml) and inhibition of zone at 300 (l/ml)
Gram-positive
Gram-negative
Fungal species
B. subtilis
S. aureus
E. coli
P. aeruginosa
C. albicans
IZ
MIC
IZ
MIC
IZ
MIC
IZ
MIC
IZ
MIC
5a
12
15
15
30
10
18
18
12
13
17
11
12
10
12
12
10
12
10
12
12
18
12
13
13
13
14
16
12
12
16
31
26
40
35
–
200
200
100
20
12
14
18
27
10
16
15
14
14
16
11
11
10
11
10
10
12
10
10
21
16
10
11
12
10
13
17
12
11
14
30
30
40
45
–
300
200
100
20
12
13
11
23
12
12
12
13
13
12
10
13
12
15
14
12
15
14
18
14
12
14
14
13
12
13
13
12
10
17
26
31
28
30
–
300
200
300
40
10
13
12
18
10
16
10
14
13
10
10
14
12
12
13
10
10
16
12
10
14
14
13
13
13
13
15
10
10
11
23
29
34
38
–
500
200
200
100
500
200
500
200
200
500
500
300
300
300
200
500
500
200
300
500
100
200
200
300
200
200
100
500
500
300
25
13
16
21
32
14
17
17
15
14
17
12
15
16
14
13
14
14
16
12
14
20
14
14
18
15
16
16
12
13
17
–
200
100
80
5b
5c
5d
20
5e
500
40
500
80
300
300
300
200
300
300
500
300
300
300
200
300
200
200
60
200
100
100
100
200
100
300
200
200
200
200
200
200
200
200
200
200
200
200
80
5f
5g
60
200
100
200
80
5h
200
200
60
5i
5j
6a
300
200
500
200
300
500
300
500
300
300
100
200
200
200
200
200
80
300
300
500
300
500
500
300
500
500
40
6b
6c
6d
6e
6f
6g
6h
6i
6j
200
200
200
200
300
300
200
200
300
500
100
25
7a
80
7b
500
300
200
300
200
40
7c
7d
7e
200
200
200
300
300
100
–
7f
7g
7h
300
300
200
50
300
300
200
50
7i
7j
Ciprofloxacin
Ampicillin
Streptomycin
Penicillin-G
Fluconazole
Nystatin
100
250
100
100
–
–
0.25
0.125
1.0
0.5
–
–
0.25
–
0.125
0.5
–
0.25
–
–
–
–
–
25
28
100
100
–
–
–
–
–
–
–
3-(4-methoxyphenyl)-4-((2-substituted-1H-
benzo[d]imidazol-1-yl)methyl)-sydnone (6a–j)
(ppm): 3.29 (s, 2H, CH2), 3.89 (s, 3H, OCH3), 4.87 (s, 1H,
NH), 7.10–7.96 (m, 7H, Ar–H); 13C NMR (DMSO-d6): d
(ppm): 51.94, 57.20, 104.40, 115.98, 117.22, 118.60,
125.43, 126.20, 129.23, 130.80, 131.41, 138.74, 156.82,
162.72, 168.24, 175.25; Anal. Calcd. for C18H13N5O3S: C,
56.98; H, 3.45; N, 18.46. Found: C, 57.03; H, 3.39; N,
18.40.
(6a) IR: (KBr) m (cm-1): 2,935, 2,867 (–CH2–), 1,734
([C=O of sydnone), 1,247, 1,050 (C–O–C of methoxy); 1H
NMR (DMSO-d6): d (ppm): 2.13 (s, 2H, CH2), 3.86 (s, 3H,
OCH3), 7.02–7.85 (m, 8H, Ar–H); 13C NMR (DMSO-d6):
123

Med Chem Res
d (ppm): 52.10, 57.10, 109.92, 115.84, 119.71, 123.00,
125.12, 130.87, 134.24, 138.98, 143.80, 144.24, 163.89,
168.74; Anal. Calcd. for C17H14N4O3: C, 63.35; H, 4.38;
N, 17.38. Found: C, 63.29; H, 4.36; N, 17.35.
NMR (DMSO-d6): d (ppm): 52.05, 57.12, 116.32, 119.20,
119.80, 122.91, 125.10, 128.64, 128.98, 129.40, 130.82,
134.40, 137.71, 138.82, 142.89, 152.91, 163.84, 169.12;
Anal. Calcd. for C23H17N4O3Cl: C, 63.82; H, 3.96; N,
12.94. Found: C, 63.86; H, 3.90; N, 12.91.
(6b) IR: (KBr) m (cm-1): 2,937, 2,860 (–CH2–), 1741
([C=O of sydnone), 1,236, 1,049 (C–O–C of methoxy),
(6h) IR: (KBr) m (cm-1): 2,922, 2,860 (–CH2–), 1,746
1
848 (C–Cl); H NMR (DMSO-d6): d (ppm): 2.16 (s, 2H,
([C=O of sydnone), 1,555, 1,346 (–NO2), 1,235, 1,022 (C–
CH2), 3.83 (s, 3H, OCH3), 6.98–7.93 (m, 11H, Ar–H); 13
C
O–C of methoxy); H NMR (DMSO-d6): d (ppm): 2.14 (s,
1
NMR (DMSO-d6): d (ppm): 52.78, 57.34, 116.34, 118.81,
119.44, 122.98, 125.33, 126.98, 128.95, 129.98, 130.78,
131.05, 132.71, 133.44, 137.83, 139.54, 141.91, 152.94,
163.84, 169.20; Anal. Calcd. for C23H16N4O3Cl2: C, 59.11;
H, 3.45; N, 11.99. Found: C, 59.06; H, 3.41; N, 12.03.
(6c) IR: (KBr) m (cm-1): 2,925, 2,857 (–CH2–), 1,753
([C=O of sydnone), 1,245, 1,039 (C–O–C of methoxy),
2H, CH2), 3.84, 3.87 (s, 6H, OCH3), 6.89–7.98 (m, 11H,
Ar–H); 13C NMR (DMSO-d6): d (ppm): 52.11, 56.44,
57.34, 114.82, 115.94, 119.11, 119.86, 123.34, 123.92,
124.22, 125.50, 130.72, 135.81, 136.42, 137.80, 139.24,
142.41, 153.24, 154.41, 162.80, 169.21; Anal. Calcd. for
C24H19N5O6: C, 60.89; H, 4.05; N, 14.79. Found: C, 60.80;
H, 3.99; N, 14.72.
1
834 (C–Cl); H NMR (DMSO-d6): d (ppm): 2.13 (s, 2H,
(6i) IR: (KBr) m (cm-1): 2,936, 2,857 (–CH2–), 1,741
CH2), 3.89 (s, 3H, OCH3), 7.11–7.95 (m, 11H, Ar–H); 13
C
([C=O of sydnone), 1,531, 1,342 (–NO2), 1,232, 1,034 (C–
1
NMR (DMSO-d6): d (ppm): 51.90, 56.94, 116.21, 119.41,
120.00, 122.91, 124.91, 127.34, 130.11, 130.89, 131.80,
133.71, 136.11, 136.80, 137.90, 139.24, 142.34, 152.94,
162.94, 170.12; Anal. Calcd. for C23H16N4O3Cl2: C, 59.11;
H, 3.45; N, 11.99. Found: C, 59.07; H, 3.42; N, 12.02.
(6d) IR: (KBr) m (cm-1): 2,937, 2,854 (–CH2–), 1760
([C=O of sydnone), 1,237, 1,021 (C–O-C of methoxy); 1H
NMR (DMSO-d6): d (ppm): 2.11 (s, 2H, CH2), 3.84, 3.88
(s, 6H, OCH3), 6.93–8.09 (m, 11H, Ar–H); 13C NMR
(DMSO-d6): d (ppm): 51.88, 56.97, 113.92, 116.24,
119.22, 119.78, 122.81, 123.34, 125.32, 130.81, 131.23,
137.82, 138.74, 142.34, 153.45, 160.62, 163.64, 170.12;
Anal. Calcd. for C24H20N4O4: C, 67.28; H, 4.71; N, 13.08.
Found: C, 67.22; H, 4.67; N, 13.04.
O–C of methoxy); H NMR (DMSO-d6): d (ppm): 2.18 (s,
2H, CH2), 3.87 (s, 3H, OCH3), 6.95–8.05 (m, 12H, Ar–H);
13C NMR (DMSO-d6): d (ppm): 52.34, 57.11, 115.81,
118.10, 119.50, 122.24, 124.34, 125.92, 127.82, 130.94,
136.60, 137.22, 139.89, 141.81, 147.22, 153.22, 162.81,
169.22; Anal. Calcd. for C23H17N5O5: C, 62.30; H, 3.86;
N, 15.79. Found: C, 62.22; H, 3.80; N, 15.72.
(6j) IR: (KBr) m (cm-1): 2,917, 2,867 (–CH2–), 1,759
([C=O of sydnone), 1,545, 1,324 (–NO2), 1,226, 1,022 (C–
1
O–C of methoxy); H NMR (DMSO-d6): d (ppm): 2.14 (s,
2H, CH2), 3.84 (s, 3H, OCH3), 7.04–8.21 (m, 12H, Ar–H);
13C NMR (DMSO-d6): d (ppm): 51.85, 56.89, 114.30,
119.10, 119.74, 120.62, 122.42, 123.24, 124.44, 126.22,
129.72, 132.89, 135.26, 137.72, 138.98, 142.34, 149.51,
153.30, 161.00, 170.10; Anal. Calcd. for C23H17N5O5: C,
62.30; H, 3.86; N, 15.79. Found: C, 62.21; H, 3.84; N,
15.71.
(6e) IR: (KBr) m (cm-1): 2,928, 2,862 (–CH2–), 1,752
([C=O of sydnone), 1,220, 1,045 (C–O–C of methoxy),
1
588 (C–Br); H NMR (DMSO-d6): d (ppm): 2.15 (s, 2H,
CH2), 3.87 (s, 3H, OCH3), 6.85–7.94 (m, 12H, Ar–H); 13
C
NMR (DMSO-d6): d (ppm): 52.12, 57.21, 115.92, 119.12,
119.81, 120.22, 122.89, 125.23, 128.21, 129.54, 130.72,
131.11, 132.48, 136.89, 139.21, 140.10, 142.54, 153.34,
162.94, 169.78; Anal. Calcd. for C23H17N4O3Br: C, 57.88;
H, 3.59; N, 11.74. Found: C, 57.81; H, 3.55; N, 11.70.
(6f) IR: (KBr) m (cm-1): 2,918, 2,840 (–CH2–), 1,749
([C=O of sydnone), 1,241, 1,019 (C–O–C of methoxy),
3-(4-methoxyphenyl)-4-
(((substitutedphenyl)amino)methyl)-sydnone (7a–j)
(7a) IR: (KBr) m (cm-1): 3,264 (NH), 2,936, 2,847 (–CH2–),
1,754 ([C=O of sydnone), 1,244, 1,033 (C–O–C of
1
methoxy); H NMR (DMSO-d6): d (ppm): 3.30 (s, 2H,
CH2), 3.84, 3.88 (s, 6H, OCH3), 4.79 (s, 1H, NH),
6.85–7.92 (m, 8H, Ar–H); 13C NMR (DMSO-d6): d
(ppm): 51.10, 56.24, 113.32, 115.22, 116.44, 125.25,
130.64, 139.10, 140.89, 151.62, 162.82, 169.30; Anal.
Calcd. for C17H17N3O4: C, 62.38; H, 5.23; N, 12.84.
Found: C, 62.28; H, 5.19; N, 12.80.
(7b) IR: (KBr) m (cm-1): 3,257 (NH), 2,952, 2,841
(–CH2–), 1,744 ([C=O of sydnone), 1,507, 1,357 (–NO2),
1,231, 1,025 (C–O–C of methoxy); 1H NMR (DMSO-d6): d
(ppm): 3.28 (s, 2H, CH2), 3.87 (s, 3H, OCH3), 4.84 (s, 1H,
NH), 6.92-8.05 (m, 8H, Ar–H); 13C NMR (DMSO-d6): d
(ppm): 52.24, 57.20, 114.40, 116.32, 125.20, 127.41,
1
592 (C–Br); H NMR (DMSO-d6): d (ppm): 2.17 (s, 2H,
CH2), 3.87 (s, 3H, OCH3), 7.05–8.14 (m, 12H, Ar–H); 13
C
NMR (DMSO-d6): d (ppm): 51.92, 56.80, 116.21, 118.91,
119.50, 121.95, 123.21, 125.10, 128.22, 126.64, 130.52,
131.62, 131.92, 132.80, 136.94, 139.11, 141.85, 152.92,
162.34, 168.94; Anal. Calcd. for C23H17N4O3Br: C, 57.88;
H, 3.59; N, 11.74. Found: C, 57.84; H, 3.58; N, 11.71.
(6g) IR: (KBr) m (cm-1): 2,937, 2,852 (–CH2–), 1,761
([C=O of sydnone), 1,246, 1,037 (C–O–C of methoxy),
1
757 (C–Cl); H NMR (DMSO-d6): d (ppm): 2.13 (s, 2H,
CH2), 3.88 (s, 3H, OCH3), 6.97–8.05 (m, 12H, Ar–H); 13
C
123

Med Chem Res
130.72, 136.31, 138.84, 154.49, 162.90, 168.82; Anal.
Calcd. for C16H14N4O5: C, 56.14; H, 4.12; N, 16.37.
Found: C, 56.06; H, 4.09; N, 16.32.
7.04–8.16 (m, 8H, Ar–H); 13C NMR (DMSO-d6): d (ppm):
52.41, 56.40, 114.54, 115.90, 122.61, 123.95, 125.50,
138.85, 143.80, 162.95, 169.55; Anal. Calcd. for C16H14
N3O3Cl: C, 57.93; H, 4.25; N, 12.67. Found: 57.88; H,
4.21; N, 12.60.
(7c) IR: (KBr) m (cm-1): 3,282 (NH), 2,945, 2,832
(–CH2–), 1,761 ([C=O of sydnone), 1,532, 1,341 (–NO2),
1,244, 1,060 (C–O–C of methoxy); 1H NMR (DMSO-d6): d
(ppm): 3.30 (s, 2H, CH2), 3.86 (s, 3H, OCH3), 4.60 (s, 1H,
NH), 6.82–7.92 (m, 8H, Ar–H); 13C NMR (DMSO-d6): d
(ppm): 51.82, 56.44, 114.20, 115.92, 118.00, 124.82,
126.00, 130.92, 131.94, 135.61, 138.95, 146.10, 163.92;
Anal. Calcd. for C16H14N4O5: C, 56.14; H, 4.12; N, 16.37.
Found: C, 56.08; H, 4.09; N, 16.32.
(7i) IR: (KBr) m (cm-1): 3,275 (NH), 2,937, 2,856
(–CH2–), 1,760 ([C=O of sydnone), 1,234, 1,060 (C–O–C
1
of methoxy), 832 (C–Cl); H NMR (DMSO-d6): d (ppm):
3.26 (s, 2H, CH2), 3.83 (s, 3H, OCH3), 4.80 (s, 1H, NH),
6.97–8.03 (m, 8H, Ar–H); 13C NMR (DMSO-d6): d (ppm):
52.32, 57.25, 114.85, 116.50, 118.65, 120.12, 125.20,
129.34, 131.00, 133.25, 139.22, 145.22, 164.10, 168.91;
Anal. Calcd. for C16H13N3O3Cl2: C, 52.48; H, 3.58; N,
11.47. Found: C, 52.39; H, 3.51; N, 11.42.
(7j) IR: (KBr) m (cm-1): 3,264 (NH), 2,924, 2,867
(–CH2–), 1,752 ([C=O of sydnone), 1,245, 1,037 (C–O–C
of methoxy), 1,154 (C–F); 1H NMR (DMSO-d6): d (ppm):
3.33 (s, 2H, CH2), 3.86 (s, 3H, OCH3), 4.77 (s, 1H, NH),
7.01–8.21 (m, 8H, Ar–H); 13C NMR (DMSO-d6): d (ppm):
51.92, 569.94, 102.95, 114.32, 116.75, 124.86, 130.70,
137.50, 139.15, 144.85, 147.54, 163.56, 169.10; Anal.
Calcd. for C16H14N3O3F: C, 60.95; H, 4.48; N, 13.33.
Found: C, 60.88; H, 4.44; N, 13.29.
(7d) IR: (KBr) m (cm-1): 3,275 (NH), 2,937, 2,841
(–CH2–), 1,752 ([C=O of sydnone), 1,234, 1,056 (C–O–C
1
of methoxy), 769 (C–Cl); H NMR (DMSO-d6): d (ppm):
3.27 (s, 2H, CH2), 3.83 (s, 3H, OCH3), 4.72 (s, 1H, NH),
7.05–8.14 (m, 8H, Ar–H); 13C NMR (DMSO-d6): d (ppm):
52.30, 57.20, 114.90, 116.32, 125.60, 126.23, 129.54,
130.92, 138.82, 147.54, 163.84, 168.72; Anal. Calcd. for
C16H14N3O3Cl: C, 57.93; H, 4.25; N, 12.67. Found: 57.82;
H, 4.20; N, 12.64.
(7e) IR: (KBr) m (cm-1): 3,265 (NH), 2,922, 2,862
(–CH2–), 1,743 ([C=O of sydnone), 1,221, 1,065 (C–O–C
1
of methoxy), 584 (C–Br); H NMR (DMSO-d6): d (ppm):
3.31 (s, 2H, CH2), 3.85 (s, 3H, OCH3), 4.81 (s, 1H, NH),
6.85–7.94 (m, 8H, Ar–H); 13C NMR (DMSO-d6): d (ppm):
51.89, 56.82, 114.50, 115.24, 116.62, 125.10, 130.80,
132.82, 139.22, 148.35, 163.85, 168.92; Anal. Calcd. for
C16H14N3O3Br: C, 51.08; H, 3.75; N, 11.17. Found: C,
51.00; H, 3.71; N, 11.13.
References
Amini M, Navidpour L, Shafiee A (2008) Synthesis and antituber-
cular activity of new N,N-diaryl-4-(4,5dichloroimidazole-2-yl)-
1,4-dihydro-2,6-dimethyl-3,5pyridinedicarboxamides.
16(1):9–12
DARU
(7f) IR: (KBr) m (cm-1): 3,286 (NH), 2,987 (–CH3),
2,942, 2,850 (–CH2–), 1,752 ([C=O of sydnone), 1,236,
1,054 (C–O–C of methoxy); 1H NMR (DMSO-d6): d
(ppm): 2.22 (s, 3H, CH3), 3.33 (s, 2H, CH2), 3.89 (s, 3H,
OCH3), 4.74 (s, 1H, NH), 6.94–8.05 (m, 8H, Ar–H); 13C
NMR (DMSO-d6): d (ppm): 20.61, 52.34, 56.75, 112.85,
116.24, 125.45, 129.85, 130.10, 131.22, 138.95, 146.35,
162.98, 169.71; Anal. Calcd. for C17H17N3O3: C, 65.58; H,
5.50; N, 13.50. Found: C, 65.51; H, 5.45; N, 13.44.
(7g) IR: (KBr) m (cm-1): 3,282 (NH), 2,989 (–CH3),
2,936, 2,857 (–CH2–), 1,744 ([C=O of sydnone), 1,236,
1,051 (C–O–C of methoxy); 1H NMR (DMSO-d6): d
(ppm): 1.37 (t, 3H, CH3), 3.26 (s, 2H, CH2), 3.60 (q, 2H,
OCH2), 3.83 (s, 3H, OCH3), 4.76 (s, 1H, NH), 6.94–8.14
(m, 8H, Ar–H); 13C NMR (DMSO-d6): d (ppm): 14.70,
51.72, 57.34, 63.20, 112.81, 115.25, 116.35, 125.15,
130.56, 139.10, 140.54, 149.95, 163.60, 169.15; Anal.
Calcd. for C18H19N3O4: C, 63.33; H, 5.61; N, 12.31.
Found: C, 63.40; H, 5.66; N, 12.26.
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1
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