Synthesis and antimicrobial activity of some novel dicationic sulphonophanes

Article abstract of DOI:10.1016/j.ejmech.2011.03.063

The synthesis of some novel imidazole-based dicationic sulfonophanes incorporating various spacer units is described. All the sulphonophanes exhibit good antibacterial and antifungal activity against five bacterial strains Bacillus subtilis, Staphylococcu

Full text of DOI:10.1016/j.ejmech.2011.03.063

European Journal of Medicinal Chemistry 46 (2011) 3093e3098
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Short communication
Synthesis and antimicrobial activity of some novel dicationic sulphonophanes
,
a
b
Perumal Rajakumar a , Chinnadurai Satheeshkumar , Gunasekaran Mohanraj ,
*
Narayanasamy Mathivanan b
a Department of Organic Chemistry, University of Madras, Guindy Campus, Chennai 600 025, India
b Center for Advanced Studies in Botany, University of Madras, Guindy Campus, Chennai 600 055, India
a r t i c l e i n f o
a b s t r a c t
Article history:
The synthesis of some novel imidazole-based dicationic sulfonophanes incorporating various spacer
units is described. All the sulphonophanes exhibit good antibacterial and antifungal activity against five
bacterial strains Bacillus subtilis, Staphylococcus aureus, Vibrio cholera, Escherichia coli, Proteus vulgaris and
human pathogenic fungus Candida albicans.
Received 22 November 2010
Received in revised form
22 March 2011
Accepted 30 March 2011
Available online 12 April 2011
Ó 2011 Elsevier Masson SAS. All rights reserved.
Keywords:
Dicationic sulphonophanes
Imidazole
Antibacterial activity
Antifungal activity
1. Introduction
proteins [12]. The synthesis of sulfones from sulfonyl chlorides has
shown extensive use in organic synthesis [13]. Sulfone derivatives
The revolutionary breakthrough by Cram and Steinberg [1] in
the field of supramolecular chemistry through the synthesis of
different types of cyclophanes of varied application is remark-
able. Cyclophanes have received much attention in the areas of
material science [2e4], as well as biological properties [5,6].
Synthesis of cationic cyclophanes in the area of supramolecular
chemistry is interestingly due to their simple reaction procedure,
mild reaction conditions, inexpensive and environmently as well
as eco-friendly reagents. Imidazole-based dicationic cyclophanes
have been used for the synthesis of carbenoid [7] and silver
complexes [8], and for selective anion recognition [9] and they
also exhibit interesting conformational behavior [10]. Imidazole
nucleus is well known and important pharmacophore in drug
discovery [11].
Quaternary ammonium compounds (QACs) are widely used as
disinfectants, antiseptics, and alternative disinfectant for fruits and
vegetables. QACs penetrate into the bacteria cell wall, reacting with
the cytoplasmic membrane inducing wall lysis caused by autolytic
enzymes. Another major resistance mechanism in both gram-
positive and gram-negative bacteria is efflux; where by molecules
taken up by the cells are pumped out by specific membrane
are well known for their biological activities such as antimicrobial
[14,15], anti-inflammatory [16] and inhibition of HIV-1 reverse
transcription [17].
Recently, the dicationic acridinophanes [18], quinolinophanes
[19], carbazolophanes [20] and imidazolophanes [21] using various
spacers like pyridine, m-terphenyl and chiral binaphthol have been
reported from our laboratory. Sulphonophanes could show better
antimicrobial activity due to the combined effect of imidazole and
sulphone functionality. Hence it is of interest to incorporate of the
two important bioactive moieties within one structure, hoping to
improve their antimicrobial activity. However, to the best of
knowledge, sulfone based imidazolaphanes called sulphonophanes
have not been reported sofar. We report herein the synthesis of
sulphonophanes 1e6 along with their antimicrobial activities
against human pathogens.
2. Chemistry
Synthesis of some novel dicationic sulfonophanes 1e6 has been
achieved via an N-alkylation route using imidazole as building unit.
One equivalent precyclophanes 8 react with 1.0 equiv. of various
spacer units 7, 9, 10aec, 11, 12 and 13 under reflux conditions for
4 days to give the sulphonophanes 1e6 in excellent yields (Fig. 1).
1H, 13C NMR, mass spectral and elemental analysis gave satisfactory
evidence for all new diaryl sulfone based cyclophanes.
* Corresponding author. Tel.: þ91 44 2220 2810.
E-mail address: perumalrajakumar@gmail.com (P. Rajakumar).
0223-5234/$ e see front matter Ó 2011 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2011.03.063

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P. Rajakumar et al. / European Journal of Medicinal Chemistry 46 (2011) 3093e3098
Table 1
3. Biological
Antimicrobial activity (minimum inhibitory concentration in
phanes (1e6) against human pathogens.
m
g/mL) of sulphono-
Antimicrobial activities of sulphonophanes were tested by agar
well diffusion method. Activity against gram positive human
pathogenic bacteria viz Bacillus subtilis and Staphylococcus aureus,
and gram negative bacteria viz Vibrio cholera, Escherichia coli,
Proteus vulgaris and human fungal pathogen Candida albicans
(obtained from the culture collections of Biocontrol and Mictrobial
metabolites Lab, Centre for advanced studies in Bontany, University
of Madras, Chennai, India) were tested under in vitro conditions.
The observed data on the antimicrobial activity of the sulphono-
phanes and control drugs are given in Table 1 in the form of
minimum inhibitory concentration (MIC).
Dicationic
B.
S.
V.
E.
P.
C.
Sulfonophanes
subtilis
aureus
cholerae
coli
vulgaris
albicans
1
2
3a
3b
3c
4
5
6
10
15
40
30
20
15
15
35
5
5
10
40
25
30
30
15
40
5
10
40
35
70
35
25
5
30
10
NA
NI
15
30
30
60
55
25
25
30
5
15
30
60
40
40
20
30
25
10
NA
NI
5
10
20
25
40
5
5
15
NA
5
Ciprofloxacin
Clotrimazole
Control
NA
NI
NA
NI
NA
NI
NI
4. Result and discussion
NA e not applicable; NI e no inhibition.
The synthesis of dicationic sulphonophanes 1e6 can be ach-
ieved by capping the precyclophane 8 with a suitable dibromide as
depicted in Scheme 1. Reaction of 1-(4-(bromomethyl)phenyl-
sulfonyl)-4-(bromomethyl)benzene 7 [22] with 2.1 equiv. of imid-
azole in the presence of 25% aqueous NaOH in CH3CN at room
temperature for 2 days gave the precyclophane 8 in 71% yield. The
1H NMR spectrum of precyclophane 8 showed a sharp singlet at
carbons at
d 49.8 in addition to aromatic carbons. Further, the
structure of precyclophane 8 was confirmed from mass spectral and
analytical data.
The dicationic sulphonophane 1 was synthesized in 67% yield by
the reaction of precyclophane 8 with one equiv. of dibromide 7
in CH3CN. The 1H NMR spectrum of cyclophane 1 displayed eight
N-methylene protons as a singlet at
of imidazole appeared as a singlet
protons. In the 13C NMR spectrum of sulphonophane 1, N-methy-
lene carbons appeared at 51.8 in addition to seven aromatic
carbons. The structure of the cyclophane 1 was further confirmed
from mass spectral and analytical data.
d
5.54 and the methine protons
d
5.26 for the N-methylene protons in addition 14 aromatic protons.
In the 13C NMR spectrum, compound 8 displayed N-methylene
d
9.48 in addition to the aromatic
d
O
O
O
O
S
S
Similarly, the precyclophane 8 was reacted with 1.0 equiv of the
dibromide 9 in CH3CN under refluxing condition for 4 days to give
sulphonophane 2 in 65% yield. The 1H NMR spectrum of 2 displayed
N
N
N
N
N
N
N
N
OCH3
-
-
2Br
2Br
two sharp singlets at
d 5.36 and d 5.61 for N-methylene protons. In
the 13C NMR spectrum, sulphonophane 2 showed two peaks at
S
d
d
51.1 and
d 55.8 for N-methylene carbons and methoxy carbon at
O
O
O
O
H3CO
47.7 in addition to the signals for ten aromatic carbons. Similarly,
1
2
precyclophane 8 with -o, -m and -p xylenyl dibromides 10aeb and
dibromides 11, 12 and 13 in CH3CN at reflux for 4 days afforded the
dicationic sulphonophanes 3aec and sulphonophanes 4, 5 and 6 in
70%, 76%, 71%, 74%, 70% and 72% yields, respectively Scheme 1.
All the sulphonophanes were identified and characterized thor-
oughlyfromspectral andanalyticaldata. Theketosulphonophanes5
and 6 displayed carbonyl absorbance at 1657 and 1658 cmꢀ1 in IR
O
O
S
S
N
N
N
N
N
N
N
N
and in 13C NMR, carbonyl carbon appeared at
195.5 respectively.
d 195.8 and
-
-
2Br
2Br
d
5. Antimicrobial studies
3a ortho
3b para
3c meta
4
Table 1 shows the antimicrobial activity of sulphonophanes 1-6
against gram positive and gram negative bacteria and human
fungal pathogen. The results revealed that majority of the synthe-
sized compounds showed varying degrees of inhibition against the
tested human pathogenic microorganisms [23].
O
O
S
O
O
S
The antimicrobial activity of the sulfonophanes were determined
by agar well diffusion assay against the gram positive human path-
ogenic bacteria viz., B. subtilis and S. aureus, gram negative bacteria
viz., V. cholera, E. coli, P. vulgaris and human fungal pathogen
C. albicans. Ciprofloxacin and clotrimazole were used as standard for
antibacterial and antifungal activity respectively. Among all the
compounds sulfonophanes 1, 2, 4 and 5 showed significant antimi-
crobial activity against the test pathogens. The sulphonophanes
3aec displayed least activity. The MIC of the compounds 1, 2, 4, 5 and
N
N
N
N
N
N
N
N
-
2Br
-
2Br
O
O
O
6 against the pathogens was between the effective range 5e40 mg.
The compound 5 with sulphone and keto moiety exhibited signifi-
cant activity against S. aureus, B. subtilis and V. cholerae, where as its
6
5
Fig. 1. Structures of Sulphonophanes 1e6.

P. Rajakumar et al. / European Journal of Medicinal Chemistry 46 (2011) 3093e3098
3095
2
1
Br
O
O
OCH3
S
ii
H3CO
Br
Br
ii
Br
9
7
3a-c
ii
Br
O
O
S
10a-c
Br
O
O
S
i
N
N
N
11
Br
Br
8
N
Br
Br
7
ii
Br
Br
Br
Br
ii
4
ii
O
O
O
12
13
6
5
Scheme 1. i. Imidazole (2.1 equiv), aq. NaOH 25%, MeCN, r.t., 48 h (71%); ii. MeCN, reflux, 96 h 1 (67%), 2 (65%), 3a (70%), 3b (76%), 3c (71%), 4 (74%), 5 (70%), 6 (72%).
activityagainstE. coli and P. vulgaris is only moderate. The compound
1 was more effective than other sulphonophanes and exhibit similar
activity to that of the commercial antibiotic ciprofloxacin.
revealed that the sulphonophanes 1 and 5 show good inhibition of
DNA gyrase B enzyme in our studies. Both the sulphonophanes
show strong hydrophobic and hydrogen bond interactions with the
side chain A of the enzyme dimer DNA gyrase B. In general, the
binding of ligand (compounds or drugs) to the enzyme DNA gyrase
B affects its catalytic activity. Prior to unwinding, the DNA binds to
the side chain A of DNA gyrase B. As the DNA gyrase B is necessary
for the DNA unwinding, the binding of the cyclophanes inhibits the
enzyme action and thus inhibits the interaction of DNA enzyme
complex. Sulphonophanes 1 showed hydrobic interaction with
Lys189 (A), Glu193 (A), Phe225 (A), Leu229 (A), Asn265 (A), Ile266
(A), Tyr267 (A), Gln275 (A), Arg276 (A) and hydrogen bond inter-
action with Lys233 (A) and Gln264 (A) with the binding free energy
of ꢀ7.01 kcal molꢀ1. Sulphonophane 5 showed hydrobic interaction
with lys189 (A), Arg190 (A), Leu229 (A), Asn265 (A), Ile266 (A),
Tyr267 (A), Pro274 (A) and hydrogen bonding with Glu193 (A) and
Cys268 (A) with the binding free energy of -9.52 kcal molꢀ1. Sul-
phonophane 1 has crucial binding interaction with DNA gyrase B
when compared to compound 5. The molecular interaction of sul-
phonophanes 1 and 5 with DNA gyrase B using Ligplot [25] is
showed in Fig. 2. Eventhough the energy difference between 1 and
5 is about 2 kcal molꢀ1, the sulphonophane 1 is considered as good
lead based on its crucial interaction with the receptor.
The MIC values were determined at lowest concentration that
completely inhibited visible growth of the microorganisms. The
relationship between the structure of the sulphonophanes and
antimicrobial activity revealed that the compounds having imid-
azole moiety exhibited least activity when compared with
compounds having sulphone moieties. Among the substituents on
the sulphonyl group, the compounds having more number of sul-
phone group were the most active. The maximum activity was
attained with sulphonophane 1, with two sulphone moieties.
All the synthesized sulphonophanes were evaluated for their
antifungal activity against C. albicans and their minimum inhibitory
concentration (MIC) was determined. All the tested compounds
showed moderate 3aec to high 1, 2 and 4e6 inhibitory effect
towards tested fungus in Table 1. Except compound 3c, all the other
sulfonophanes showed significant activity. The compounds 1, 4 and
5 showed excellent activity against S. aureus, V. cholerae and C.
albicans 5
mg level comparable to that of the corresponding stan-
dard drugs.
In order to ensure that the solvent had no effect on bacterial and
fungal growth a control test was performed with DMSO (dimethyl
sulfoxide) which revealed no inhibiting activity.
To study the mechanism of antimicrobial activity of the sul-
phonophanes 1 and 5, docking studies were carried out using the
software autodock version 4 [24]. Sulphonophanes 1 and 5 were
tested against the enzyme DNA gyrase B (PDB ID: 1EI1). The studies
6. Conclusion
In conclusion, the sulphonophanes 1, 2, 4, 5, and 6 exhibit
good antibacterial activities against all the five human bacterial

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P. Rajakumar et al. / European Journal of Medicinal Chemistry 46 (2011) 3093e3098
pathogens and also 1, 4 and 5 exhibit excellent antifungal activity
against C. albicans. Molecular docking studies also revealed that
sulphonophanes 1and 5 have good free energy of binding and
may be considered as a good inhibitor of DNA gyrase B. Thus the
sulphonophanes may be further developed as an antimicrobial
drug against the fungal and bacterial infections. Further,
synthesis and biological applications of other related sulphono-
phanes with benzimidazole and benzotriazole unit are
underway.
was removed under vacuum and the residue was purified by
column chromatography on silica gel (CHCl3eMeOH, 99:1). Yield
71%; mp 192 ꢂC; 1H NMR (300 MHz, DMSO-d6):
d 5.26 (s, 4H); 7.00
(d, 4H, J ¼ 12.6 Hz); 7.31 (d, 4H, J ¼ 6.6 Hz); 7.67 (s, 2H); 7.87 (d, 4H,
J ¼ 6.3 Hz). 13C NMR (75 MHz, DMSO-d6):
d 49.8, 119.4, 127.9, 128.1,
129.7, 137.4, 140.9, 142.5 (EI-MS) m/z 378 (Mþ). Elemental Anal.
Calcd for C20H18N4O2S: C, 63.47; H, 4.79; N, 14.80. Found: C, 63.55;
H, 4.81; N, 14.78.
7.3. Synthesis of sulphonophanes 1e6; general procedure
7. Experimental protocols
To a solution of 8 (1.0 equiv) in anhydrous MeCN (250 mL),
dibromide 7, 9, 10aec, 11, 12 and 13 (1.0 equiv.) was added in one
portionand themixturewasrefluxedfor4days until thebromidewas
consumed (reaction monitored by TLC). When the reaction was
complete, the mixture was concentrated, cooled and the cationic
cyclophanes 1, 2, 3aec, 4, 5 and 6 were isolated (as the bromide salt)
by filtration.
7.1. Chemistry
All melting points were determined using a Toshniwal melting
point apparatus by open capillary tube method and are uncor-
rected. 1H NMR and 13CNMR spectra were recorded on a Bruker
300 MHz and Jeol 400 MHz instruments. Mass spectra were
recorded on a Jeol DX303 HF mass spectrophotometer. Elemental
analyses were carried out using a Perkin-Elmer CHNS 2400 instru-
ment. Column chromatography was performed on silica gel (ACME,
100e200 mesh). Routine monitoring of the reaction was made
using thin layer chromatography developed on glass plates coated
with silica gel-G (ACME) of 25 mm thickness and visualized with
iodine.
7.3.1. Sulphonophane 1
Yield 67%; mp 215 ꢂC; 1H NMR (300 MHz, DMSO-d6):
d
5.54 (s,
8H); 7.58e7.64 (m, 8H); 7.84e7.88 (m, 4H); 7.99e8.06 (m, 8H); 9.48
(s, 2H). 13C NMR (125 MHz, DMSO-d6):
d 51.8, 128.5, 128.6, 128.7,
129.2, 129.9, 130.1, 141.0. (EI-MS) m/z 782 (Mþ). Elemental Anal.
Calcd for C34H30 Br2N4O4S2: C, 52.18; H, 3.86; N, 7.16. Found: C,
52.21; H, 3.89; N, 7.14.
7.2. Synthesis of precyclophane 8
7.3.2. Sulphonophane 2
To a solution of imidazole (2.1 equiv) in MeCN (50 mL), aq NaOH
(25%, 5 mL) was added and the mixture was stirred for 10 min. The
dibromide 7 (1.0 equiv) in MeCN (20 mL) was added in one portion
and the reaction was stirred at room temperature for 48 h. After
completion of the reaction, the solvent was evaporated in vacuum
and the residue was extracted with CHCl3 (3 ꢁ 100 mL), washed
with brine (150 mL) and dried over anhydrous Na2SO4. The solvent
Yield 65%; mp 254 ꢂC; 1H NMR (300 MHz, DMSO-d6):
d 3.48 (s,
6H); 5.36 (s, 4H); 5.61 (s, 4H); 6.78 (s, 2H); 7.79 (s, 2H); 7.92 (d, 4H,
J ¼ 7.5 Hz); 8.07e8.12 (m, 6H); 9.66 (s, 2H). 13C NMR (75 MHz,
DMSO-d6):
d 47.7, 51.1, 55.8, 112.2, 122.8, 122.9, 123.9, 128.2, 130.2,
136.7, 141.3, 141.5, 150.3; (EI-MS) m/z 702 (Mþ). Elemental Anal.
Calcd for C30H30 Br2N4O4S: C, 51.29; H 4.30; N, 7.98. Found: C, 51.32;
H 4.29; N, 7.94.
Fig. 2. Ligplot results: a. Binding of ligand 793 (A)-sulphonophane 1 on A-Chain amino acids of DNA gyrase B (PDBID:1EI1) with 3 hydrogen bonds and 9 hydrophobic interactions.
b. Binding of ligand 793 (A)-sulphonophane 5 on A-Chain amino acids of DNA gyrase B with 2 hydrogen bonds and 7 hydrophobic interactions.

P. Rajakumar et al. / European Journal of Medicinal Chemistry 46 (2011) 3093e3098
3097
7.3.3. Sulphonophane 3a
prepared with the help of sterilized cork borer (9 mm diameter). All
the sulphonopahnes 1e6 were dissolved in 10% DMSO which did
not affect microorganisms growth, according to our control
Yield 70%; mp 174 ꢂC; 1H NMR (300 MHz, DMSO-d6):
d 5.37 (s,
4H); 5.56 (s, 4H); 7.69e7.83 (m, 8H); 7.99 (d, 4H, J ¼ 8.4 Hz)
8.05e8.09 (m, 4H); 9.51 (s, 2H). 13C NMR (75 MHz, DMSO-d6):
experiments. Using a micropippete, 50
mL of different concentra-
d
54.4, 57.2, 127.9, 129.3, 133.4, 133.5, 134.5, 136.4, 137.3, 141.2, 144.3,
tions of sulphonophanes (5, 10, 15 to 100 m
g) were added to the
146.8. (EI-MS) m/z 642 (Mþ). Elemental Anal. Calcd for C28H26
Br2N4O2S: C, 52.34; H, 4.08; N, 8.72. Found: C, 52.35; H, 3.99; N,
8.69.
wells in the plate. Commercial antibiotics were used as positive
reference standard to compare the efficiency of the test
compounds. The plates were incubated at 37 ꢂC for 24 h. The
antibacterial and minimum inhibitory concentrations were deter-
mined by the zone of inhibitions.
7.3.4. Sulphonophane 3b
Yield 76%; mp 181 ꢂC; 1H NMR (300 MHz, DMSO-d6):
d
5.41
(s, 4H); 5.54 (s, 4H); 7.44e7.57 (m, 6H); 7.67e7.89 (m, 8H); 8.12 (s,
2H); 9.64 (s, 2H). 13C NMR (125 MHz, DMSO-d6):
51.8, 52.0, 123.5,
123.7, 128.7, 129.2, 130.7, 136.2, 136.3, 141.6, 141.7. (EI-MS) m/z 642
(Mþ). Elemental Anal. Calcd for C28H26 Br2N4O2S: C, 52.34; H, 4.08;
N, 8.72. Found: C, 52.36; H, 4.04; N, 8.71.
7.4.2. Antifungal activity
d
The test human fungal pathogen C. albicans was maintained in
Sabouraud’s dextrose agar (SDA). The C. albicans was inoculated in
Sabouraud’s dextrose broth and incubated at 37 ꢂC for 8 h. The
pathogen was swabbed on the sterile SDA plates using a sterile
swab and wells were made using sterile cork borer (9 mm diam-
eter). The sulphonophanes 1e6 were tested for their antifungal
activity and their MIC was determined. The sulphonophanes at the
7.3.5. Sulphonophane 3c
Yield 71%; mp 186 ꢂC; 1H NMR (300 MHz, DMSO-d6):
d 5.32
(s, 4H); 5.46 (s, 4H); 7.56 (d, 2H, J ¼ 7.6 Hz); 7.68 (d, 4H, J ¼ 6.9 Hz);
concentrations of 5 mg/mL of 10% DMSO was used for this study
7.90 (d, 8H, J ¼ 8.4 Hz); 8.03 (s, 2H); 9.17 (s, 2H). 13C NMR (125 MHz,
with Clotrimazole as a positive control. The minimum inhibitory
concentration was taken as the lowest concentration of the test
compound that showed promonent inhibition of fungal pathogen
growth after 48 h of incubation at 37 ꢂC.
DMSO-d6):
d 51.9, 52.3, 123.3, 123.9, 128.7, 129.0, 129.2, 130.7, 131.1,
135.4, 136.1, 140.9, 141.8. (EI-MS) m/z 642 (Mþ). Elemental Anal.
Calcd for C28H26 Br2N4O2S: C, 52.34; H, 4.08; N, 8.72. Found: C,
52.36; H, 4.10; N, 8.69.
7.4.3. Molecular docking studies
7.3.6. Sulphonophane 4
The synthesized sulphonophanes were subjected for molecular
docking using Autodock (version 4) with Lamarckian genetic
algorithm. Sulphonophanes 1 and 5 were analysed for their
mechanism of antimicrobial action using the above method. The
estimated binding energy for each molecule were compared along
with the crucial hydrogen and hydrophobic bonds between the
protein and ligand to substantiate the experimental results. The
interactions were graphically represented in 2D using Ligplot
software.
Yield 74%; mp >300 ꢂC; 1H NMR (300 MHz, DMSO-d6):
d 5.57
(s, 4H); 5.73 (s, 4H); 7.49 (d, 4H, J ¼ 8.4 Hz); 7.55e7.64 (m, 8H); 7.68
(s, 4H); 7.73 (s, 4H); 7.91 (d, 4H, J ¼ 8.1 Hz); 10.10 (s, 2H). 13C NMR
(75 MHz, DMSO-d6):
d 51.0, 52.2, 123.0, 123.6, 126.7, 127.9, 128.1,
128.3, 128.4, 128.5, 128.6, 128.9, 129.6, 133.5, 136.6, 140.5, 141.1. (EI-
MS) m/z 794 (Mþ). Elemental Anal. Calcd for C40H34 Br2N4O2S: C,
60.46; H, 4.31; N, 7.05. Found: C, 60.48; H, 4.29; N, 7.08.
7.3.7. Sulphonophane 5
Yield 70%; mp 169 ꢂC; 1H NMR (300 MHz, DMSO-d6):
d 5.58
Acknowledgement
(s, 4H); 5.62 (s, 4H); 7.61 (s, 4H); 7.69e7.71 (m, 6H); 7.91 (s, 4H);
7.95e8.03 (m, 6H); 9.64 (s, 2H). 13C NMR (125 MHz, DMSO-d6):
The authors thank DST-FIST, New Delhi, for NMR spectral facility
to the Department of organic chemistry, University of Madras and
CS thanks University Grant Commission (UGC) for the financial
assistance.
d
51.6, 52.1, 123.7, 123.9, 127.4, 128.4, 128.8, 130.0, 130.6, 137.4, 137.6,
139.7, 141.2, 195.8. IR
Elemental Anal. Calcd for C35H30 Br2N4O3S: C, 56.31; H, 4.05; N, 7.51.
Found: C, 56.29; H, 4.08; N, 7.55.
n
co ¼ 1657 (C]O). (EI-MS) m/z 746 (Mþ).
References
7.3.8. Sulphonophane 6
Yield 72%; mp 175 ꢂC; 1H NMR (300 MHz, DMSO-d6):
d 5.59
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(s, 4H); 5.69 (s, 4H); 7.56e7.64 (m, 4H); 7.85e7.88 (m, 16H); 8.02
(d, 4H, J ¼ 7.5 Hz); 9.62 (s, 2H). 13C NMR (125 MHz, DMSO-d6):
d
51.8, 52.2, 123.7, 127.5, 128.4, 128.6, 128.7. 129.1, 130.1, 130.2, 130.4,
130.9, 137.6, 139.8, 140.3, 140.9, 141.1, 195.5. IR
n
co ¼ 1658 (C]O).
(EI-MS) m/z 850 (Mþ). Elemental Anal. Calcd for C42H34 Br2N4O4S:
C, 59.30; H, 4.03; N, 6.59. Found: C, 59.31; H, 4.01; N, 6.54.
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