Synthesis, characterization, and antimicrobial evaluation of sulfonamides containing N-acyl moieties catalyzed by bismuth(III) salts under both solvent and solvent-free conditions

Article abstract of DOI:10.1080/00397910903318732

Efficient N-acylation of sulfonamides with both readily available carboxylic acid chlorides and anhydrides has been carried out with catalysis by bismuth(III) salts including BiCl3 and Bi (OTf)3. The reactions proceed rapidly in both heterogeneous and solvent-free conditions and afforded the corresponding N-acylsulfonamides in good to excellent yields. The mild reaction conditions and low toxicity of bismuth salts make this procedure attractive and in close agreement with the goals of green chemistry. Some of the synthesized compounds were evaluated in vitro as antimicrobial agents against representative strains of Gram-positive (Staphylococcus aureus ATCC 25922, clinical strains of Staphylococcus aureus VISA and Enterococcus spp.) and Gram-negative bacteria (Pseudomonas aeruginosa ATCC 27853, clinical strains of Klebsiella pneumonia and Escherichia coli) and as antifungal agents against Candida albicans (clinically isolated) by both disc diffusion and minimal inhibition concentration (MIC) methods. All these bacteria and fungi studied were screened against some antibiotics to compare with our chemicals' zone diameters.

Full text of DOI:10.1080/00397910903318732

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Synthesis, Characterization, and
Antimicrobial Evaluation of Sulfonamides
Containing N-Acyl Moieties Catalyzed by
Bismuth(III) Salts Under Both Solvent and
Solvent-Free Conditions
a
b
Hadi Adibi , Ahmad Reza Massah , Mohammad Bagher Majnooni
a
b
b
c
,
Sherita Shahidi , Maryam Afshar , Ramin Abiri & Hamid
b
Javaherian Naghash
a
Department of Medicinal Chemistry , Faculty of Pharmacy,
Kermanshah University of Medical Sciences , Kermanshah, Islamic
Republic of Iran
b
Department of Chemistry , Islamic Azad University , Shahreza
Branch, Shahreza, Islamic Republic of Iran
c
Department of Microbiology , Faculty of Medicine, Kermanshah
University of Medical Sciences , Kermanshah, Islamic Republic of
Iran
Published online: 09 Aug 2010.
To cite this article: Hadi Adibi , Ahmad Reza Massah , Mohammad Bagher Majnooni , Sherita Shahidi ,
Maryam Afshar , Ramin Abiri & Hamid Javaherian Naghash (2010) Synthesis, Characterization, and
Antimicrobial Evaluation of Sulfonamides Containing N-Acyl Moieties Catalyzed by Bismuth(III)
Salts Under Both Solvent and Solvent-Free Conditions, Synthetic Communications: An International
Journal for Rapid Communication of Synthetic Organic Chemistry, 40:18, 2753-2766, DOI:
10.1080/00397910903318732
To link to this article: http://dx.doi.org/10.1080/00397910903318732
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1
Synthetic Communications , 40: 2753–2766, 2010
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397910903318732
SYNTHESIS, CHARACTERIZATION, AND
ANTIMICROBIAL EVALUATION OF SULFONAMIDES
CONTAINING N-ACYL MOIETIES CATALYZED BY
BISMUTH(III) SALTS UNDER BOTH SOLVENT AND
SOLVENT-FREE CONDITIONS
1
Hadi Adibi, Ahmad Reza Massah, Mohammad Bagher
2
1
2
2
Majnooni, Sherita Shahidi, Maryam Afshar, Ramin Abiri,
3
2
and Hamid Javaherian Naghash
1
Department of Medicinal Chemistry, Faculty of Pharmacy, Kermanshah
University of Medical Sciences, Kermanshah, Islamic Republic of Iran
2
Department of Chemistry, Islamic Azad University, Shahreza Branch,
Shahreza, Islamic Republic of Iran
3
Department of Microbiology, Faculty of Medicine, Kermanshah University
of Medical Sciences, Kermanshah, Islamic Republic of Iran
Efficient N-acylation of sulfonamides with both readily available carboxylic acid chlorides
and anhydrides has been carried out with catalysis by bismuth(III) salts including BiCl
and Bi (OTf) . The reactions proceed rapidly in both heterogeneous and solvent-free
3
3
conditions and afforded the corresponding N-acylsulfonamides in good to excellent yields.
The mild reaction conditions and low toxicity of bismuth salts make this procedure attract-
ive and in close agreement with the goals of green chemistry. Some of the synthesized
compounds were evaluated in vitro as antimicrobial agents against representative strains
of Gram-positive (Staphylococcus aureus ATCC 25922, clinical strains of Staphylococcus
aureus VISA and Enterococcus spp.) and Gram-negative bacteria (Pseudomonas aerugi-
nosa ATCC 27853, clinical strains of Klebsiella pneumonia and Escherichia coli) and as
antifungal agents against Candida albicans (clinically isolated) by both disc diffusion
and minimal inhibition concentration (MIC) methods. All these bacteria and fungi studied
were screened against some antibiotics to compare with our chemicals’ zone diameters.
Keywords: Antimicrobial activity; bismuth(iii) salts; N-acylation; N-acylsulfonamide; solvent-free
INTRODUCTION
Sulfonamides are among the most widely used antibacterial agents in the world,
chiefly because of their low cost, low toxicity, and excellent activity against common
[1]
bacterial diseases. The synergetic action of sulfonamides with trimethoprim has
Received August 8, 2009.
Address correspondence to Hadi Adibi, Department of Medicinal Chemistry, Faculty of
Pharmacy, Kermanshah University of Medical Sciences, Kermanshah 67145-1673, Islamic Republic of
Iran, and Ahmad Reza Massah, Department of Chemistry, Islamic Azad University, Shahreza Branch,
Shahreza 86145-311, Islamic Republic of Iran. E-mail: hadibi@kums.ac.ir; massah@iaush.ac.ir
2
753

2754
H. ADIBI ET AL.
brought about enormous resurgence of sulfonamide usage everywhere over the past
decade. N-Acylsulfonamides have received considerable attention because of their
diverse biological activities as precursors of therapeutic agents for Alzheimer’s
[
2]
[3]
disease, antibacterial inhibitors of tRNA synthetases, prostaglandin F1a sulfona-
[
4]
mides for the potential treatments of osteoporosis, antagonists for angiotensin
II, and leukotriene D4-receptors.
The most common methods for N-acylation of sulfonamides with different
acylating agents have utilized suitable bases such as pyridine,
[
pyridine,
[
5]
[6]
[
7,8]
4-N,N-dimethyl
Formation of bis-acylated by-products is
9,10]
[11–13]
and alkali hydroxides.
the most important restriction of these methods. Recently, the first solvent-free pro-
cedure for the N-acylation of sulfonamides in the presence of potassium carbonates
[
14]
has been performed that overcomes the restriction of the other methods. On the
other hand, there are a few reports mentioning this transformation under acidic
conditions. Some of the methods reported include acylation of sulfonamides with
[
15]
concentrated H SO in the carboxylic acid anhydride as solvent
16]
or in acetoni-
trile and also using Fe-exchanged montmorillonite K10. Very recently, we have
2
4
[
[17]
[
18]
demonstrated the applicability of protic solid acids such as silica chloride and
silica phosphoric acid for N-acylation of sulfonamides. Unfortunately, many of
[19]
these methods have drawbacks such as long reaction times, vigorous reaction
conditions, use of expensive or unavailable reagents, poor yields of products, and
tedious workups. Furthermore, most of these methods occur in solvent media,
contrary to green chemistry. Clearly, there is a need for development of a new,
inexpensive, benchtop acid that can promote this reaction in a catalytic way.
Bismuth compounds have recently received a lot of attention because of their
[
20–23]
low toxicity, low cost, and good stability.
Bismuth(III) salts have been reported
[24]
[25]
as catalyst for epoxide opening, Mannich-type reactions, Mukaiyama-aldol reac-
[
26]
[27]
[28]
tions, Claisen rearrangement, deprotection of 1,1-diacetates, and acetylation
[
29]
and benzoylation of alcohols and phenols.
attractive because they are commercially available or can be easily prepared from com-
mercially available starting materials. In continuation of our studies in this regard,
we decided to apply these reagents to the N-acylation of sulfonamides and evaluate
their antimicrobial activity.
Bi(OTf) and BiCl are particularly
3 3
[
30]
RESULTS AND DISCUSSION
Chemistry
An efficient method is reported here using Bi(OTf) and BiCl as catalysts for
3
3
N-acylation of different sulfonamides with some carboxylic acid anhydride and
chloride in solvent-free and heterogeneous conditions (Scheme 1). In a simple pro-
cedure, a mixture of reactants was vigorously stirred at room temperature in
solvent-free condition or refluxed in suitable solvents for the appropriate times.
The progress of the reactions was monitored by thin-layer chromatography
(
TLC), and the products were isolated in good to excellent yields (82–98%) in an easy
workup procedure.
At first, the reaction was optimized with respect to the solvent, amount of
catalyst, temperature, and reaction time. To find the best solvent, the reaction of

SULFONAMIDES CONTAINING N-ACYL MOIETIES
2755
3 3
Scheme 1. BiCl - and Bi(OTf) -catalyzed N-acylation of sulfonamides.
benzenesulfonamide with acetic anhydride was carried out in different solvents. Even
though the reactions in CHCl and CH Cl led to a small amount of side products,
3
2
2
an excellent yield was obtained, and these were selected as solvents for further stu-
dies. Also, the N-acylation of benzenesulfonamide was tried with varying amounts
of catalyst in solvent and solvent-free conditions. We attempted the reaction of
benzenesulfonamide with 2 equivalents acetic anhydride or acetyl chloride in the
presence of 5 mol% of Bi(OTf) at room temperature or in refluxed CH Cl . The
3
2
2
reactions were completed within 1–5 min, and the pure N-acetylsulfonamide was
obtained in 91–94% yield by just passing through a small silica-gel column. In a simi-
lar manner, benzenesulfonamide was also converted to N-acetylsulfonamide using
1
0 mol% of BiCl within 13–17 min. By reducing the amount of acylating agents
3
or catalysts, there were a considerable change in reaction time and yield in both
solvent and solvent-free conditions. To evaluate the role of catalysts, we tried the
N-acylation of benzenesulfonamide with acetic anhydride and acetyl chloride in
the absence of Bi(OTf) or BiCl . The reaction did not occur after 48 h. The best
3
3
conditions for the N-acylation of benzenesulfonamide are summarized in Table 1.
The BiCl - and Bi(OTf) -catalyzed N-acylation reactions were applied to a
3
3
range of sulfonamides, carboxylic acid anhydrides, and carboxylic acid chlorides
Tables 2 and 3). The reaction proceeded very efficiently in all cases. As shown in
(
Table 2, benzenesulfonamide, 4-methyl benzenesulfonamide, and methanesulfona-
mide underwent clean and remarkably fast N-acylation reaction with several
aliphatic and aromatic carboxylic acid anhydrides. The aliphatic carboxylic acid
anhydrides with long chains, like pentanoic anhydride (Table 2, entries 4, 10, and
1
1
6) and also the relatively bulky isobutanoic anhydride (Table 2, entries 5, 11, and
7), were converted to the corresponding N-acylsulfonamides in excellent yields in
Table 1. Best reaction conditions in the N-acylation of benzenesulfonamide
Entry
Conditions
Yield (%)
ꢀ
ꢀ
1
2
3
4
5
6
7
8
Bi(OTf)
Bi(OTf)
Bi(OTf)
Bi(OTf)
3
3
3
3
5%=Solvent-free=25 C=Acetyl chloride=3 min
5%=Solvent-free=25 C=Acetic anhydride=1 min
92
92
91
94
88
91
87
90
5%=CH
5%=CH
2
Cl
Cl
2
=Reflux=Acetyl chloride=5 min
=Reflux=Acetic anhydride=2 min
2
2
ꢀ
BiCl
BiCl
BiCl
BiCl
3
3
3
3
10%=Solvent-free=25 C=Acetyl chloride=16 min
10%=Solvent-free=25 C=Acetic anhydride=13 min
ꢀ
10%=CHCl
10%=CHCl
3
=Reflux=Acetyl chloride=17 min
=Reflux=Acetic anhydride=15 min
3

2756
H. ADIBI ET AL.
Table 2. N-Acylation of sulfonamides with carboxylic acid anhydride in solvent or solvent-free conditions
Catalyst: Bi(OTf)
3
(5%)
Catalyst: BiCl
3
(10%)
Solvent-free
CH
2
Cl
2
Solvent-free
CHCl
3
0
a
b
a
b
a
b
a
b
Entry
R
R
Time
Yield
Time
Yield
Time
Yield
Time
Yield
1
2
3
4
5
6
7
8
9
CH
3
3
3
3
3
3
3
3
3
3
3
3
CH
3
1
1
90
90
90
91
90
90
90
91
91
92
92
90
92
93
90
94
94
90
15
2
2
90
91
91
90
91
91
94
93
90
96
91
88
94
92
95
92
96
90
10
10
10
8
88
85
85
88
90
82
89
90
88
90
88
80
91
90
85
86
88
88
10
10
12
10
13
13
60
20
20
20
20
20
80
15
17
17
20
20
70
90
88
88
90
91
87
90
92
90
88
89
82
90
89
90
90
92
85
10
CH
CH
CH
CH
CH
CH
CH
CH
CH
CH
CH
Ph
C
C
C
2
H
3
H
4
H
5
7
9
1
1
1
5
10
10
60
15
17
20
22
17
70
13
17
12
16
15
70
CH(CH
Ph
3
3
3
)
2
)
2
)
2
1
2
15
2
30
2
-Ph CH
3
-Ph
-Ph
-Ph
C
C
C
2
3
4
H
5
7
9
3
2
H
H
3
3
1
1
1
1
1
1
1
1
1
1
0
1
2
3
4
5
6
7
8
9
3
3
-Ph CH(CH
-Ph Ph
CH
1
1
50
1
30
2
3
Ph
Ph
C
C
C
2
H
3
H
4
H
5
7
9
2
2
3
2
Ph
Ph
3
3
CH(CH
Ph
NO -Ph
1
30
1
Ph
Ph
35
10
c
c
c
c
2
10
12
12
a
b
c
Minutes.
Isolated yield (%).
In hours.
both solvent and solvent-free conditions. These results show that there was no steric
effect from the substituents at anhydride moiety. Comparisons between the results of
Tables 2 and 3 show that carboxylic acid anhydrides were found to be more reactive
than carboxylic acid chlorides. Also, N-acylation of sulfonamides with electron-
withdrawing groups containing carboxylic acid anhydrides needed a longer reaction
time to form N-acylsulfonamides. For example, the reaction of benzenesulfonamide
with 4-nitrobenzoic anhydride did not proceed well, and only 10–15% of product was
obtained after 10–12 h (Table 2, entry 19). These results show that the acylinium ion
was formed and then reacted with sulfonamide. This fact was further supported by
N-acylation of benzenesulfonamide with benzoic-4-nitrobenzoic anhydride. After
completion of the reaction, we observed that the only product is N-benzoyl benzen-
sulfonamide. In fact, sulfonamide reacted with a carbonyl group to form more stable
acylinium ions (Scheme 2). On the other hand, comparison between the results
obtained in solution and those under solvent-free conditions show that reaction
proceeded faster in solvent-free conditions, which is in agreement with the goals of

SULFONAMIDES CONTAINING N-ACYL MOIETIES
2757
Table 3. N-Acylation of sulfonamides with carboxylic acid chloride in solvent or solvent-free conditions
Catalyst: Bi(OTf)
Solvent-free
3
(5%)
Cl
Catalyst: BiCl
3
(10%)
CHCl
CH
2
2
Solvent-free
3
00
a
b
a
b
a
b
a
b
Entry
R
R
Time
Yield
Time
Yield
Time
Yield
Time
Yield
1
2
3
4
5
6
7
8
9
Ph
Ph
Ph
CH
3
3
5
92
95
91
90
95
90
94
95
98
5
5
91
96
95
86
92
85
95
94
93
16
14
45
10
10
50
10
10
30
88
88
90
89
89
80
90
92
85
17
15
45
12
10
55
12
10
35
87
90
85
90
89
83
88
90
88
C
Ph
2
H
5
5
5
15
3
40
5
CH
CH
CH
CH
CH
CH
3
3
3
3
3
3
-Ph
-Ph
-Ph
CH
3
C
Ph
2
H
7
5
20
1
45
5
CH
3
C
Ph
2
H
1
10
1
25
a
Minutes.
b
Isolated yield (%).
green chemistry. Furthermore, the experimental results show that Bi(OTf) is more
3
reactive and works better than BiCl in terms of amount of catalyst, temperature,
3
reaction times, and the yields of products (Tables 1–3).
Antimicrobial Activity
The test compounds were evaluated for their antibacterial activity against three
Gram-positive cocci [Staphylococcus aureus ATCC 25922, clinical strains of
Staphylococcus aureus VISA (vancomycin intermediate Staphylococcus aureus),
and Enterococcus faesium), three Gram-negative bacilli (Pseudomonas aeruginosa
ATCC 27853, clinical strains of Klebsiella pneumonia, and Escherichia coli), and
the yeast (clinical strains of Candida albicans) using the microbroth-dilution
Scheme 2. N-Acylation of benzenesulfonamide with benzenoic-4-nitrobenzoic anhydride.

2
758

2
759

2760
H. ADIBI ET AL.
[
31]
method.
The obtained MIC (minimum inhibitory concentration) values were
compared to gentamicin, ciprofloxacin, sulfamethoxazole, ceftriaxone, and flucona-
zole as the reference drugs and are presented in Table 4. Inhibition zones were
[
32]
determined by the disc diffusion method
25 mg), gentamicin (10 mg), co-trimoxazole (1.25:23.75 mg), cefoxitin (30 mg), imipe-
nem (10 mg), tetracycline (30 mg), and azithromycin (15 mg) as the reference drugs
Table 5).
Microbiological results showed that the tested compounds possessed a broad
and compared with fluconazole
(
(
spectrum of antibacterial activity against the screened microorganisms; however,
they exhibited less antibacterial potency than the control drugs. The results reported
in Table 4 indicate that the tested compounds are able to inhibit growth of the
screened pathogens, showing MIC values between 32 and 1024 mg=mL. Among
the synthesized compounds, N-ethanoyl methansulfonamide and N-isobutanoyl-4-
methyl benzenesulfonamide were also potent against clinical VISA strains, showing
an MIC value of 512 mg=mL. All the other compounds exhibited no antibacterial
activity against the pathogens.
Moreover, the tested compounds also possessed antimycotic activity against
the yeast Candida albicans, showing MIC values between 64 and 1024 mg=mL,
whereas the antifungal potency of the compared control drug fluconazole was
observed to be better than the corresponding compounds, showing an MIC value
of 4 mg=mL. As seen in Table 5, N-butanoyl-4-methyl benzenesulfonamide shows
the best antifungal activity against C. albicans, and its potency compares to that
of the reference antibiotic (fluconazole).
CONCLUSION
In summary, we found that Bi(OTf) and BiCl are efficient catalysts for the N-
3
3
acylation of different sulfonamides. This method offers several advantages, including
mild reaction conditions, use of green catalysts, and no formation of bis-acylated by-
products. Furthermore, this solvent-free protocol is a simple, inexpensive, safe, and
ecofriendly alternative to the other methods for the N-acylation of sulfonamides.
Also, antimicrobial activity of some of the synthesized sulfonamides demonstrated
moderate to good inhibition against all the strains tested. Finally, these preliminary
results are promising and are beneficial for further study in developing new
compounds.
EXPERIMENTAL
General
All chemicals were purchased from Merck and Fluka chemical companies. The
products were characterized by comparing the physical data with those of known
samples or by their spectral data. Infrared (IR) spectra were recorded on Nicollet
1
(impact 400D model) Fourier transform (FT)-IR spectrophotometer. H NMR
and C NMR spectra were recorded on a Bruker DRX 300 Avance spectrophot-
1
3
ometer in dimethylsulfoxide (DMSO-d ) as the solvent and tetramethylsilane
6

SULFONAMIDES CONTAINING N-ACYL MOIETIES
2761
(
6
TMS) as internal standard. Column chromatography was performed using silica gel
0 (230–400 mesh). All yields refer to isolated yield.
General Procedure for N-Acylation of Sulfonamides Under
Solvent-Free Conditions
Carboxylic acid chloride (2 mmol) or carboxylic acid anhydride (2 mmol) were
added to a vigorously stirred mixture of sulfonamide (1 mmol) and BiCl (0.1 mmol)
3
or Bi(OTf) (0.05 mmol) at room temperature. The progress of the reaction was
3
monitored by thin-layer chromatography (TLC). After completion of the reaction,
ethyl acetate (20 mL) was added, and the solid catalyst was removed by filtration.
The filtrate was washed with water and dried over MgSO . After evaporation of
4
the solvent, the crude product was purified by column chromatography on silica
gel (mixed EtOAc–petroleum ether as eluent) or recrystallized (toluene or ethyl
acetate=n-hexane mixed solvent) to afforded the corresponding N-acyl sulfonamide
in good to excellent yields.
General Procedure for N-Acylation of Sulfonamides in Solvent
A mixture of sulfonamide (1 mmol), carboxylic acid chloride (2 mmol), or car-
boxylic acid anhydride (2 mmol) was refluxed in CHCl or CH Cl (5 mL) in the
3
2
2
presence of BiCl3 (0.1 mmol) or Bi(OTf)3 (0.05 mmol) for an appropriate time
Table 1). The progress of the reaction was monitored by TLC. After completion
of the reaction, CHCl or CH Cl (20 mL) was added, and the solid catalyst was
(
3
2
2
removed by filtration. The filtrate was washed with water and dried over MgSO4.
After evaporation of the solvent, the crude product was purified as described for
the solvent-free method.
1
13
Structural assignments of the products are based on their IR, H NMR,
C
NMR, and CHN analysis and also by comparison of their melting points with those
of known compounds.
Spectral Data of Isolated N-Acylsulfonamides
ꢀ
N-Ethanoyl benzenesulfonamide (Table 2, entry 1). Mp 120–122 C; IR t
ꢁ
1
1
(
(
(
(
cm ): 3125, 2901, 1699, 1468, 1356, 1243, 1169, 867, 689; H NMR (DMSO-d ) d
6
ppm) 1.92 (s, 3H), 7.59–7.73 (m, 3H), 7.91 (2H, dd, J ¼ 7.2 Hz, J ¼ 1.5 Hz) 12.10
1
2
1
3
s, 1H); C NMR (DMSO-d ) d (ppm) 23.68, 127.90, 129.58, 134.08, 139.81, 169.23.
6
Found: C, 48.61; H, 4.77; N, 6.88. C H NO S requires C, 48.23; H, 4.55; N, 7.03%.)
8
9
3
ꢀ
N-Propanoyl benzenesulfonamide (Table 2, entry 2). Mp 75–76 C; IR n
ꢁ
cm ): 3246, 2986, 1710, 1461, 1341, 1156, 845, 766, 595 cm ; H NMR (DMSO-d )
6
1
1 1
(
d (ppm) 0.88 (t, 3H, J ¼ 7.5 Hz), 2.22 (q, 2H, J ¼ 7.5 Hz), 7.59–7.70 (m, 3H),
1
3
7
.91–7.94 (m, 2H), 12.06 (s, 1H); C NMR (DMSO-d ) d (ppm) 8.68, 29.15,
6
126.04, 127.87, 129.37, 129.56, 172.72. (Found: C, 50.88; H, 5.29; N, 6.68.
C H NO S requires C, 50.69; H, 5.20; N, 6.57%.)
9
11
3

2762
H. ADIBI ET AL.
ꢀ
N-Butanoyl benzenesulfonamide (Table 2, entry 3). Mp 99–101 C; IR n
ꢁ
1
1
(
cm ) 3216, 1687, 1608, 1330, 1171; H NMR (DMSO-d ) d (ppm) 0.73 (t, 3H,
6
J ¼ 7.3 Hz), 1.41 (sext, 2H, J ¼ 7.3 Hz), 2.16 (t, 2H, J ¼ 7.3 Hz), 7.59–7.92 (m, 5H),
1
3
1
2.05 (s, 1H); C NMR (DMSO-d ) d (ppm) 13.59, 17.94, 37.59, 127.86, 129.56,
6
134.05, 139.90, 171.96. (Found: C, 52.65; H, 5.59; N, 6.36. C H NO S requires
C, 52.85; H, 5.77; N, 6.16%.)
1
0
13
3
ꢀ
N-Pentanoyl benzenesulfonamide (Table 2, entry 4). Mp 82–84 C; IR n
ꢁ
1
1
(
cm ) 3101, 1688, 1608, 1350, 1164; H NMR (DMSO-d ) d (ppm) 0.77 (t, 3H,
6
J ¼ 7.2 Hz), 1.13 (sext, 2H, J ¼ 7.4 Hz), 1.37 (quin, 2H, J ¼ 7.4 Hz), 2.19 (t, 2H,
1
3
J ¼ 7.3 Hz), 7.59–7.91 (m, 5H), 12.03 (s, 1H); C NMR (DMSO-d ) d (ppm)
6
1
5
3.47, 21.31, 26.02, 34.97, 127.36, 129.04, 133.55, 139.38, 171.57. (Found: C,
4.92; H, 6.07; N, 5.68. C H NO S requires C, 54.75; H, 6.27; N, 5.80%.)
1
1
15
3
ꢀ
N-Isobutanoyl benzenesulfonamide (Table 2, entry 5). Mp 120–122 C;
1
ꢁ1
IR n (cm ) 3257, 2979, 2880, 1719, 1434, 1335, 1176, 1090, 891, 758; H NMR
(
DMSO-d ) d (ppm) 0.92 (d, 6H, J ¼ 6.8 Hz), 2.45 (sept, 1H, J ¼ 6.8 Hz), 7.59–7.91
6
1
3
(m, 5H), 12.07 (s, 1H); C NMR (DMSO-d ) d (ppm) 18.83, 34.71, 127.81,
6
129.56, 134.04, 139.79, 175.75. (Found: C, 52.71; H, 5.89; N, 6.28. C H NO S
10 13 3
requires C, 52.85; H, 5.77; N, 6.16%.)
ꢀ
N-Benzoyl benzenesulfonamide (Table 2, entry 6). Mp 137–139 C; IR n
cm ): 3277, 3059, 1699, 1580, 1455, 1342, 1177, 1072, 900, 834, 575; H NMR
ꢁ
1
1
(
(
8
1
DMSO-d ) d (ppm) 7.36–7.53 (m, 3H), 7.56–7.58 (m, 2H), 7.83–7.87 (m, 3H),
6
1
3
.01–8.03 (m, 2H), 12.56 (s,1H); C NMR (DMSO-d ) d (ppm) 126.03, 128.12,
6
28.87, 129.07, 129.38, 129.60, 133.77, 134.12, 165.91. (Found: C, 59.95; H, 4.38;
N, 5.21. C H NO S requires C, 59.76; H, 4.24; N, 5.36%.)
1
3
11
3
N-Ethanoyl-4-methyl benzenesulfonamide (Table 2, entry 7). Mp
ꢁ1
ꢀ
1
1
36–138 C; IR n (cm ) 3290, 1725, 1607, 1441, 1336, 1217, 1171, 867, 669 cm ;
1
H NMR (DMSO-d ) d (ppm) 1.90 (s, 3H), 2.38 (s, 3H), 7.40 (d, 2H, J ¼ 8 Hz),
6
1
7
.79 (d, 2H, J ¼ 8.0 Hz), 12.01 (s, 1H); H NMR (DMSO-d ) d (ppm) 21.50, 23.64,
6
128.00, 129.96, 136.96, 144.62, 169.13. (Found: C, 51.01; H, 5.37; N, 6.57.
C H NO S requires C, 50.69; H, 5.20; N, 6.57%.)
9
11
3
N-Propanoyl-4-methyl benzenesulfonamide (Table 2, entry 8). Mp
1
ꢀ
ꢁ1
1
04–106 C; IR n (cm ) 3143, 1715, 1596, 1344, 1191; H NMR (DMSO-d ) d
6
(
ppm) 0.87 (t, 3H, J ¼ 7.5 Hz), 2.20 (q, 2H, J ¼ 7.5 Hz), 2.38 (s, 3H), 7.41 (d, 2H,
1
3
J ¼ 8.1 Hz), 7.79 (d, 2H, J ¼ 8.1 Hz), 11.96 (s, 1H); C NMR (DMSO-d ) d (ppm)
6
8
5
.70, 21.50, 29.10, 127.97, 129.93, 137.09, 144.56, 172.61. (Found: C, 52.61; H,
.87; N, 6.36. C H NO S requires C, 52.85; H, 5.77; N, 6.16%.)
1
0
13
3
N-Butanoyl-4-methyl benzenesulfonamide (Table 2, entry 9). Mp
ꢁ1
ꢀ
1
7
9–81 C; IR n (cm ) 3090, 1680, 1601, 1349, 1158; H NMR (DMSO-d ) d
6
(
2
ppm) 0.74 (t, 3H, J ¼ 7.3 Hz), 1.40 (sext, 2H, J ¼ 7.3 Hz), 2.15 (t, 2H, J ¼ 7.3 Hz),
1
3
.38 (s, 3H), 7.4 (d, 2H, J ¼ 8.1 Hz), 7.79 (d, 2H, J ¼ 8.1 Hz), 11.97 (s, 1H);
C
NMR (DMSO-d ) d (ppm) 13.60, 17.96, 21.49, 37.59, 127.95, 129.93, 137.08,
6
144.55, 171.85. (Found: C, 54.63; H, 6.21; N, 5.97. C H NO S requires C, 54.75;
11 15 3
H, 6.27; N, 5.80%.)

SULFONAMIDES CONTAINING N-ACYL MOIETIES
2763
N-Pentanoyl-4-methyl benzenesulfonamide (Table 2, entry 10). Mp
ꢁ1
ꢀ
1
8
8–89 C; IR n (cm ) 3271, 2960, 2868, 1719, 1593, 1428, 1342, 1151, 854; H
NMR (DMSO-d ) d (ppm) 0.76 (t, 3H, J ¼ 7.3 Hz), 1.15 (sext, 2H, J ¼ 7.5 Hz),
6
1
.36 (quint, 2H, J ¼ 7.5 Hz), 2.17 (t, 2H, J ¼ 7.3 Hz), 2.37 (s, 3H), 7.4 (d, 2H,
6
1
3
J ¼ 8 Hz), 7.79 (d, 2H, J ¼ 8 Hz), 11.96 (s, 1H); C NMR (DMSO-d ) d (ppm);
1
3
C NMR (DMSO-d ) d (ppm) 13.94, 21.47, 21.83, 26.52, 35.46, 127.95, 129.90,
6
137.07, 144.51, 171.95. (Found: C, 56.78; H, 6.89; N, 5.33. C H NO S requires
C, 56.45; H, 6.71; N, 5.49%.)
1
2
17
3
N-Isobutanoyl-4-methyl benzenesulfonamide (Table 2, entry 11). Mp
ꢁ1
ꢀ
1
1
0
7
1
5
10–112 C; IR n (cm ) 3259, 1731, 1329, 1171; H NMR (DMSO-d ) d (ppm)
6
.92 (d, 6H, J ¼ 6.8 Hz), 2.38 (s, 3H), 2.41–2.46 (m, 1H,), 7.40 (d, 2H, J ¼ 7.8 Hz),
1
3
.78 (d, 2H, J ¼ 7.8 Hz), 11.99 (s, 1H); C NMR (DMSO-d ) d (ppm) 16.92,
6
9.57, 32.75, 125.97, 128.03, 135.03, 142.61, 173.72. (Found: C, 54.60; H, 6.41; N,
.62. C H NO S requires C, 54.75; H, 6.27; N, 5.80%.)
1
1
15
3
N-Benzoyl-4-methyl benzenesulfonamide (Table 2, entry 12). Mp 145 ꢁ
ꢀ
ꢁ1
1
1
47 C; IR n (cm ) 3292, 3065, 1699, 1605, 1500, 1421, 1342, 1176, 897, 712, H
NMR (DMSO-d ) d (ppm) 2.38 (s, 3H), 7.42–7.63(m, 5H), 7.84–7.91 (m, 4H),
6
1
3
1
2.48 (s, 1H); C NMR (DMSO-d ) d (ppm) 21.53, 128.22, 128.84, 129.06,
6
129.99, 131.94, 133.71, 137.02, 144.72, 165.83. (Found: C, 59.98; H, 4.61; N, 5.35.
C H NO S requires C, 61.07; H, 4.76; N, 5.09%.)
1
4
13
3
ꢀ
N-Ethanoyl methanesulfonamide (Table 2, entry 13). Mp 97–98 C; IR n
cm ) 3138, 2907, 1706, 1468, 1341, 1243, 1158, 874, 755, 590, 509; H NMR
ꢁ
1
1
(
(
1
3
DMSO-d ) d (ppm) 1.99 (s, 3H), 3.21 (s, 3H), 11.67 (s, 1H); C NMR (DMSO-
6
d ) d (ppm) 23.70, 41.38, 170.25. (Found: C, 26.22; H, 5.21; N, 10.01. C H NO S
6
3
7
3
requires C, 26.27; H, 5.14; N, 10.21%.)
ꢀ
N-Propanoyl methanesulfonamide (Table 2, entry 14). Mp 68–70 C; IR n
ꢁ
1
1
(
cm ) 3143, 1687, 1343, 1158; H NMR (DMSO-d ) d (ppm) 0.99 (t, 3H,
6
1
3
J ¼ 7.5 Hz), 2.27 (q, 2H, J ¼ 7.5 Hz), 3.21 (s, 3H), 11.63 (s, 1H); C NMR
(
DMSO-d ) d (ppm) 8.84, 29.16, 43.58, 173.72. (Found: C, 31.54; H, 6.21; N, 9.08.
6
C H NO S requires C, 31.78; H, 6.00; N, 9.26%.)
4
9
3
ꢀ
N-Butanoyl methanesulfonamide (Table 2, entry 15). Mp 68–70 C; IR n
ꢁ
1
1
(
cm ) 3203, 1700, 1330, 1151; H NMR (DMSO-d ) d (ppm) 0.86 (t, 3H,
6
J ¼ 7.3 Hz), 1.53 (sext, 2H, J ¼ 7.3 Hz), 2.23 (t, 2H, J ¼ 7.3 Hz), 3.22 (s, 3H), 11.64
1
3
(
s, 1H); C NMR (DMSO-d ) d (ppm) 13.22, 17.50, 37.14, 40.88, 172.46. (Found:
6
C, 36.61; H, 6.51; N, 8.78. C H NO S requires C, 36.35; H, 6.71; N, 8.84%.)
5
11
3
ꢀ
N-Pentanoyl methanesulfonamide (Table 2, entry 16). Mp 69–71 C; IR n
ꢁ
1
1
(
cm ) 3269, 1720, 1330, 1158; H NMR (300 MHz, DMSO-d ) d (ppm) 0.86 (t, 3H,
6
J ¼ 7.3 Hz), 1.26 (sext, 2H, J ¼ 7.4 Hz), 1.48 (quin, 2H, J ¼ 7.4 Hz), 2.25 (t, 2H,
1
3
J ¼ 7.3 Hz), 3.2 (s, 3H), 11.62 (s, 1H); C NMR (75 MHz, DMSO-d ) d (ppm)
6
14.06, 21.96, 26.62, 35.52, 43.55, 173.09. (Found: C, 39.98; H, 7.22; N, 7.97.
C H NO S requires C, 40.21; H, 7.31; N, 7.81%.)
6
13
3
ꢀ
N-Isobutanoyl methanesulfonamide (Table 2, entry 17). Mp 97–99 C;
1
ꢁ1
IR n (cm ) 3213, 1717, 1329, 1158; H NMR (DMSO-d ) d (ppm) 1.03 (d, 6H,
6

2764
H. ADIBI ET AL.
1
3
J ¼ 6.8 Hz), 2.49 (sept, 1H, J ¼ 6.9 Hz), 3.22 (s, 3H), 11.64 (s, 1H); C NMR
(
DMSO-d ) d (ppm) 19.05, 34.73, 41.32, 176.85. (Found: C, 36.32; H, 6.83; N,
6
8
.67. C H NO S requires C, 36.35; H, 6.71; N, 8.84%.)
5 11 3
ꢀ
N-Benzoyl methanesulfonamide (Table 2, entry 18). Mp 153–155 C; IR n
ꢁ
1
1
(
(
cm ) 3244, 1692, 1335, 1177; H NMR (DMSO-d ) d (ppm) 3.38 (s, 3H), 7.49–7.95
m, 5H), 12.14 (s, 1H); C NMR (DMSO-d ) d (ppm) 41.78, 128.90, 129.00, 132.11,
6
1
3
6
1
33.70, 166.92. (Found: C, 48.58; H, 4.67; N, 6.86. C H NO S requires C, 48.23; H,
8 9 3
4
.55; N, 7.03%.)
Biological Assays
Turbidity of all the bacterial cultures was adjusted to 0.5 McFarland stan-
dard by preparing a bacterial suspension of three to five well-isolated colonies
of the same morphological type selected from an agar plate culture. The cul-
5
tures were further diluted 1000-fold to get an inoculum size of 1.5 ꢂ 10
CFU=mL. The test compounds (50 mg) were dissolved in DMSO (0.5 mL),
and the solution was diluted with distilled water (4.5 mL) to get a stock solution
of 10000 mg=mL of each compound. Further progressive double dilution with
Muller–Hinton broth was performed to obtain the required concentrations of
[
31]
1
024, 512, 256, 128, 64, 32, 16, 8, 4, and 2 mg=mL.
To ensure that the solvent
had no effect on bacterial growth, a control test was performed with test
medium supplemented with DMSO at the same dilutions as used in the experi-
ment. Our results indicated that all the compounds tested in this study demon-
strated less activity against both Gram-positive and Gram-negative
microorganisms than the reference drug.
Standard antibiotics were also diluted in the same manner. Each microwell in a
series of 12 microwells was inoculated with 75 mL of the serial dilutions, and then 75
ꢀ
mL of the bacterial suspention was added. After overnight incubation in 37 C,
growth was surveyed. Data of MICs of the test compounds and control drugs are
shown in Table 4.
Inhibition zones of compounds were determined by the disc diffusion
[
method. The antimicrobial screening was surveyed using the sterilized (autoclaved
32]
ꢀ
at 120 C for 30 min) Mueller–Hinton Agar and YEPD agar for the yeast. The cul-
ture suspensions were prepared and adjusted by comparing against 0.5 McFarland
turbidity tubes. Mueller–Hinton and YEPD agar were poured into each sterile Petri
dish. After the media were solidified, the bacteria were cultured using sterile swabs.
All of the compounds were dissolved in DMSO of 10 mg=mL. Empty sterilized discs
of 6.4 mm (Padtan Teb, Iran) were impregnated with 100 mL of compounds. Discs
ꢀ
were placed on agar plates, and the cultures were incubated at 37 C for 24 h for bac-
teria and 48 h for C. albicans. Inhibition zones formed on the medium were evaluated
in millimeters. The solvent control (DMSO) did not show any antimicrobial activity.
Inhibition zones were compared with those of reference discs. Reference discs used
for control are as follows: fluconazole (25 mg), gentamicin (10 mg), co-trimoxazole
(1.25:23.75 mg), cefoxitin (30 mg), imipenem (10 mg), tetracycline (30 mg), and azithro-
mycin (15 mg).

SULFONAMIDES CONTAINING N-ACYL MOIETIES
2765
ACKNOWLEDGMENTS
We thank Dr. Taki for his kind help and the Islamic Azad University of
Shahreza Research Council for their partial support. We gratefully acknowledge the
Kermanshah University of Medical Sciences Research Council for financial support.
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