Synthesis, spectral characterization and biological screening of n-substituted derivatives of n-(1-Hydroxy-2-methylpropan-2-yl)benzenesulfonamide

Article abstract of DOI:10.14233/ajchem.2013.13642

In the present study, a series of N-substituted derivative of N-(1-hydroxy-2-methylpropan-2-yl)benzenesulfonamide was synthesized. Firstly, the reaction of 2-amino-2-methyl propan-1-ol (1) with benzenesulfonyl chloride (2) yielded N-(1-hydroxy-2-methylpro

Full text of DOI:10.14233/ajchem.2013.13642

Asian Journal of Chemistry; Vol. 25, No. 6 (2013), 3289-3293
http://dx.doi.org/10.14233/ajchem.2013.13642
Synthesis, Spectral Characterization and Biological Screening of
N-Substituted Derivatives of N-(1-Hydroxy-2-methylpropan-2-yl)benzenesulfonamide
1,*
1
1
1
AZIZ-UR-REHMAN , NADIA ABBAS , MUHAMMAD ATHAR ABBASI , HIRA KHALID ,
2
3
4
4
KHALID MOHAMMED KHAN , MUHAMMAD ASHRAF , IRSHAD AHMAD and SYEDA ABIDA EJAZ
1Department of Chemistry, Government College University, Lahore-54000, Pakistan
2HEJ Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi-75270, Pakistan
3Department of Biochemistry and Biotechnology, The Islamia University of Bahawalpur, Bahawalpur-63100, Pakistan
4Department of Pharmacy, The Islamia University of Bahawalpur, Bahawalpur-63100, Pakistan
*Corresponding author: Tel: +92 42 111000010; Ext. 449; E-mail: azizryk@yahoo.com
(Received: 22 February 2012;
Accepted: 17 December 2012)
AJC-12569
In the present study, a series of N-substituted derivative of N-(1-hydroxy-2-methylpropan-2-yl)benzenesulfonamide was synthesized.
Firstly, the reaction of 2-amino-2-methyl propan-1-ol (1) with benzenesulfonyl chloride (2) yielded N-(1-hydroxy-2-methylpropan-2-
yl)benzene sulfonamide (3) and secondly on treatment with different electrophiles (4a-i) in the presence of N,N-dimethyl formamide and
sodium hydride which act as a base furnished into N-substituted derivatives of N-(1-hydroxy-2-methylpropan-2-yl)benzenesulfonamide
(5a-i). All these derivatives along with their parent compounds were characterized by IR, EI-MS and 1H NMR spectra. These compounds
were assayed for their antioxidant activities by using 2,2-diphenyl-1-picrylhydrazil (DPPH) scavenging and other biological activities via
screening them against acetylcholinesterase, butyrylcholinesterase and lipoxygenase enzymes, however, these showed prominent activity
against butyrylcholinesterase enzyme. It is clearly evident from the results that compounds, N-(butan-2-yl)-N-(1-hydroxy-2-methylpropan-
2-yl)benzene sulfonamide (5e) and N-(allyl)-N-(1-hydroxy-2-methylpropan-2-yl)benzenesulfonamide (5f) were found to be potent inhibitor
having IC50 value of 65.47 0.69 and 79.36 0.92 µmol, respectively, relative to eserine, a reference standard with IC50 value of 0.85
0.001 µmol. These two compounds 5e and 5f were also showed good scavenging activity against DPPH.
Key Words: 2-Amino-2-methyl propan-1-ol, Benzenesulfonyl chloride, Sulfonamides, Butyrylcholinesterase enzyme, DPPH.
enzymes which comprise serine hydrolases. The different
substrates specificities and inhibitors for these enzymes are
due to the differences in amino acid residues of the active sites
ofAChE and BChE. The enzyme system is responsible for the
termination of acetylcholine at cholinergic synapses. These
are key components of cholinergic brain synapses and neuro-
muscular junctions. The main function of AChE and BChE is
to catalyze the hydrolysis of the neurotransmitter acetylcholine
and termination of the nerve impulse in cholinergic synapses7.
It has been found that BChE is present in extensively higher
quantities inAlzheimer's plaques than in the normal age related
non-dementia of brains. H1 and H2 receptor antagonists possess
AChE inhibitory activities. Cholinesterase inhibitors raise the
amount of acetylcholine accessible for neuronal and neuro-
muscular transmission through their capacity to reversibly or
irreversibly8. Hence, the search for new cholinesterase inhibitors
is considered a significant and ongoing strategy to introduce
new drug candidates for the treatment of Alzheimer's disease
and other associated diseases9.
INTRODUCTION
Sulfonamides are a very important class of compounds
in the pharmaceutical industry, being widely used as anticancer,
antiinflammatory and antiviral agents1. They are well known
for their antimicrobial activity because of their being less-
expensive, less toxic and having superb inhibitory effect against
bacterial infections2. Nucleophilic substitution reactions occur
during sulfonamide synthesis. Amine acts as nucleophile,
attacks on sulfonyl chloride3. Sulfonamides are effective
inhibitors of carbonic anhydrase4 and are wide spectrum anti-
biotics. More than 30 drugs bearing this functionality have
been reported to apparent clinical applications5. These comp-
ounds are most effective inhibitor against HIV protease. These
also take account of anticonvulsants, diuretics, hypoglycemic
functionality. Sulfonamides also find their wide use in case of
animal husbandry and food additives6.
Acetylcholinesterase (AChE, EC 3.1.1.7) and buty-
rylcholinesterase (BChE, EC 3.1.1.8) consist of a family of

3290 Aziz-Ur-Rehman et al.
Asian J. Chem.
Literature review showed that minor modification in the
structure of sulfonamides can lead to quantitative as well as
qualitative changes in the biological activity. It encouraged us
to synthesize various N-substituted derivatives of sulfonamides
with an objective to search new contenders of drug having
significant enhanced activity and can be helpful in controlling
many degenerative diseases.
Acetylcholinesterase assay: TheAChE inhibition activity
was performed according to the reported method10 with slight
modifications. Total volume of the reaction mixture was 100
µL. It contained 60 µL Na2HPO4 buffer with concentration of
50 mM and pH 7.7. 10 µL test compound (0.5 mM well-1) was
added, followed by the addition of 10 µL (0.005 unit well-1)
enzyme. The contents were mixed and pre-read at 405 nm.
Then contents were pre-incubated for 10 min at 37 ºC. The
reaction was initiated by the addition of 10 µL of 0.5 mM
well-1 substrate (acetylthiocholine iodide), followed by the
addition of 10 µL DTNB (0.5 mM well-1). After 15 min of
incubation at 37 ºC the absorbance was measured at 405 nm
using 96-well plate reader Synergy HT, Biotek, USA.All experi-
ments were carried out with their respective controls in triplicate.
Eserine (0.5 mM well-1) was used as a positive control. The per
cent inhibition was calculated by the help of following equation
In this work, we report various N-substituted derivatives
of N-(1-hydroxy-2-methylpropan-2-yl)benzenesulfonamide.
First, a parent sulfonamide was prepared by reacting benzene-
sulfonyl chloride with 2-amino-2-methyl propan-1-ol at room
temperature. Simple stirring in basic aqueous media gave the
desired compound in excellent yield that was further reacted
with different electrophiles to acquire N-alkyl substituted
sulfonamides.
EXPERIMENTAL
Control − Test
TLC was performed on pre-coated silica gel G-25-UV254
plates. Detection was carried out at 254 nm and by ceric
sulphate reagent. Purity was checked on TLC with different
solvent systems using ethyl acetate and n-hexane giving single
spot. The IR spectra were recorded in KBr on a Jasco-320-A
spectrophotometer. 1H NMR spectra were recorded in CDCl3
on a Bruker spectrometers operating at 400 MHz. Chemical
shifts are given in ppm. Mass spectra (EIMS) were measured
on Finnigan MAT-112 instrument. EI-MS were recorded in
were recorded on a JMS-HX-110 spectrometer, with a data
system. The melting points were recorded on a Griffin &
George melting point apparatus by open capillary tube and
were uncorrected.
Inhibition (%) =
×100
Control
IC50 values were calculated using EZ-Fit enzyme kinetics soft-
ware (Perrella Scientific Inc. Amherst, USA).
Butyrylcholinesterase assay: The BChE inhibition
activity was performed according to the reported method10 with
slight modifications. Total volume of the reaction mixture was
100 µL containing 60 µL, Na2HPO4 buffer, 50 mM and pH
7.7. 10 µL test compound 0.5 mM well-1 was added followed
by the addition of 10 µL (0.5 unit well-1) BChE (Sigma Inc.).
The contents were mixed and pre-read at 405 nm and then
pre-incubated for 10 min at 37 ºC. The reaction was initiated
by the addition of 10 µL of 0.5 mM well-1 substrate (butyryl-
thiocholine chloride). Followed by the addition of 10 µL
DTNB, 0.5 mM well-1. After 15 min of incubation at 37 ºC,
absorbance was measured at 405 nm using 96-well plate reader
Synergy HT, Biotek, USA. All experiments were carried out
with their respective controls in triplicate. Eserine (0.5 mM
well-1) was used as positive control. The percent inhibition
was calculated by the help of following equation.
Procedure for the synthesis of sulfonamide in aqueous
media: The nucleophilic substitution reaction of amine with
benzene sulfonyl chloride was carried out as follows: a mixture
of benzene sulfonyl chloride (10.0 mmol; 1.27 mL) and
2-amino-2-methyl propan-1-ol (10.0 mmol; 0.95 mL) was
suspended in 50 mL water. The pH of the suspension was
adjusted and maintained at 9-10 by adding aqueous solution
of a base (Na2CO3) at room temperature. The reaction mixture
was stirred and progress of completion was monitored by thin
layer chromatography.After the completion of reaction, concen-
trated HCl was added gradually to adjust the pH to 2. The
precipitates were quenched by filtration, washed with distilled
water and dried to afford the title compound 3. The product
was dissolved in methanol and re-crystallized by slow evapo-
ration of the solvent, to generate colourless bead like crystals
of N-(1-hydroxy-2-methylpropan-2-yl)benzenesulfonamide.
Yield 91 %; m.p. 124 ºC.
Control − Test
Inhibition (%) =
×100
Control
IC50 values were calculated using EZ-Fit Enzyme kinetics
software (Perrella Scientific Inc. Amherst, USA).
Lipoxygenase assay: Lipoxygenase (LOX) activity was
assayed according to the method11,12 with slight modifications.
A total volume of 200 µL lipoxygenase assay mixture
contained 150 µL sodium phosphate buffer (100 mM, pH 8.0),
10 µL test compound and 15 µL purified lipoxygenase enzyme
(600 units well-1,Sigma Inc.). The contents were mixed and
pre-read at 234 nm and preincubated for 10 min at 25 ºC. The
reaction was initiated by addition of 25 µL substrate solution.
The change in absorbance was observed after 6 min at 234
nm using 96-well plate reader Synergy HT, Biotek, USA. All
reactions were performed in triplicates. The positive and nega-
tive controls were included in the assay. Baicalin (0.5 mM
well-1) was used as a positive control. The percentage inhibition
(%) was calculated by formula given below.
General procedure for the synthesis of N-alkyl substi-
tuted sulfonamides in DMF: The calculated amount of N-
(1-hydroxy-2-methylpropan-2-yl)benzenesulfonamide (0.1
mmol) was taken in a round bottomed flask (50 mL), then
N,N-dimethyl formamide (DMF) (10 mL) was added to dissolve
it followed by the addition of sodium hydride (0.1 mmol) to
the mixture. The reaction mixture was stirred for 0.5 h at room
temperature and then slowly added the alkyl halide to the
mixture and the solution was further stirred for 2 h. The progress
of reaction was monitored via TLC till single spot. Distilled
water was added in the flask and the product was received by
solvent extraction.
Control − Test
Inhibition (%) =
×100
Control

Vol. 25, No. 6 (2013)
Synthesis of N-Substituted Derivatives of N-(1-Hydroxy-2-methylpropan-2-yl)benzenesulfonamide 3291
where, Control = total enzyme activity without inhibitor. Test
= Activity in the presence of test compound. IC50 values was
calculated using EZ-Fit Enzyme Kinetics software (Perrella
Scientific Inc. Amherst, USA).
(s, 2H, CH2-1), 3.46 (t, J = 7.0, 2H, CH2-1''), 1.75 (m, 2H,
CH2-2''), 1.31 (m, 2H, CH2-3'') 1.30 (s, 6H, CH3-3, CH3-4)
and 0.91 (t, J = 7.5, 3H, CH3-4''); EIMS: m/z 285 [M]+, 221
[M-SO2]+, 144 [M-C6H5SO2]+, 141 [C6H5SO2]+.
DPPH assay: The stable 1,1-diphenyl-2-picrylhydrazyl
radical (DPPH) was used for the determination of antioxidant
activity. Different concentrations of compounds in respective
solvents were added at an equal volume (10 µL) to 90 µL of
100 µM methanolic DPPH in a total volume of 100 µL in 96-
well plates. The contents were mixed and incubated at 37 ºC
for 0.5 h. The absorbance was measured at 517 nm using
Synergy HT BioTek® USA microplate reader. Quercetin and
L-ascorbic acid were used as standard antioxidants. The
experiments were carried out in triplicates. IC50 values were
calculated using EZ-Fit5 Perrella Scientific Inc.Amherst USA
software. The decrease in absorbance indicates increased
radical scavenging activity which was determined by the
following formula13.
N-(1-Hydroxy-2-methylpropan-2-yl)-N-pentylbenzene
sulfonamide (5d): Light brown greasy liquid,Yield 63 %. IR
(KBr, νmax, cm-1): 3053 (C-H, stretching of aromatic ring), 1625,
1523 (C=C, aromatic stretching), 1343 (-SO2-NH-, stretching);
1H NMR (500 MHz, CDCl3): δ 7.90 (dd, J = 8.5, 2.1 Hz, 2H,
H-2', H-6'), 7.57 (m, 1H, H-4'), 7.49 (m, 2H, H-3', H-5'), 3.65
(s, 2H, CH2-1), 3.36 (t, 2H, J = 7.0 Hz, CH2-1''), 1.73 (m, 2H,
CH2-2''), 1.34 (m, 4H, CH2-3'' CH2-4'') 1.23 (s, 6H, CH3-3,
CH3-4) and 0.90 (t, J = 7.5, 3H, CH3-5''); EIMS: m/z 299 [M]+,
235 [M-SO2]+, 158 [M-C6H5SO2]+, 141 [C6H5SO2]+.
N-(Butan-2-yl)-N-(1-hydroxy-2-methylpropan-2-
yl)benzenesulfonamide (5e): Light brown greasy liquid, yield
68 %. IR (KBr, νmax, cm-1): 3053 (C-H, stretching of aromatic
ring), 1625, 1523 (C=C, aromatic stretching), 1343 (-SO2-NH-
, stretching); 1H NMR (500 MHz, CDCl3): δ 7.92 (dd, J = 8.5,
2.1 Hz, 2H, H-2', H-6'), 7.55 (m, 1H, H-4'), 7.48 (m, 2H, H-3',
H-5'), 3.66 (s, 2H, CH2-1), 2.98 (d, J = 7.5 Hz, 2H, CH2-1''),
1.74 (m, 1H, H-2''), 1.13 (s, 6H, CH3-3, CH3-4) and 0.91 (d,
6H, J = 7.5 Hz, CH3-3'', CH3-4''); EIMS: m/z 285 [M]+, 221
[M-SO2]+, 144 [M-C6H5SO2]+, 141 [C6H5SO2]+.
Control − Test
Antiradical activity[Inhibition (%)] =
×100
Control
Statistical analysis: All the measurements were done in
triplicate and statistical analysis was performed by Microsoft
Excel 2003. Results are presented as mean sem.
N-Allyl-N-(1-hydroxy-2-methylpropan-2-yl)benzene
sulfonamide (5f): Brown greasy liquid, yield 75 %. IR (KBr,
νmax, cm-1): 3052 (C-H, stretching of aromatic ring), 1628, 1523
(C=C, aromatic stretching), 1344 (-SO2-NH-, stretching); 1H
NMR (500 MHz, CDCl3): δ 7.85 (dd, J = 8.5, 2.1 Hz, 2H,
H-2', H-6'), 7.56 (m, 1H, H-4'), 7.49 (m, 2H, H-3', H-5' ), 5.17
(dd, J = 1.6, 17.3 Hz, Hb-3''), 5.13 (dd, J =1.2, 10 Hz, Ha-3''),
5.61 (m, 1H, H-2''), 3.79 (m, 2H, CH2-1''), 3.72 (s, 2H, CH2-1)
and 1.21 (s, 6H, CH3-3, CH3-4); EIMS: m/z 269 [M]+, 205
[M-SO2]+, 128 [M-C6H5SO2]+, 141 [C6H5SO2]+.
Spectral characterization of the synthesized compounds
N-(1-Hydroxy-2-methylpropan-2-yl)benzenesulfon
amide (3): White amorphous powder, Yield 89 %, m.p. 124
ºC. IR (KBr, νmax, cm-1): 3432 (N-H, stretching), 3058 (C-H,
stretching of aromatic ring), 1623, 1517 (C=C, aromatic
stretching), 1341 (-SO2-NH-, stretching); 1H NMR (500 MHz,
CDCl3): δ 7.90 (dd, J = 8.5, 2.1 Hz, 2H, H-2', H-6'), 7.56 (m,
1H, H-4'), 7.49 (m, 2H, H-3', H-5'), 2.27 (s, 2H, CH2-1) and
1.14 (s, 6H, CH3-3, CH3-4); EIMS: m/z 229 [M]+, 165 [M-
SO2]+, 141 [C6H5SO2]+, 73 [M-C6H5CH2NH]+.
N-Benzyl-N-(1-hydroxy-2-methylpropan-2-yl)-
benzenesulfonamide (5g): Gammy liquid, yield 71 %. IR
(KBr, νmax, cm-1): 3042 (C-H, stretching of aromatic ring),
1620, 1524 (C=C, aromatic stretching), 1340 (-SO2-NH-,
stretching); 1H NMR (500 MHz, CDCl3): δ 7.90 (dd, J = 8.5,
2.1 Hz, 2H, H-2', H-6'), 7.61 (m, 1H, H-4'), 7.50 (m, 2H, H-3',
H-5'), 7.36-7.42 (m, 5H, H-2'' to H-6''), 3.62 (s, 2H, CH2-1),
3.56 (s, 2H, CH2-7'') and 1.32 (s, 6H, CH3-3, CH3-4); EIMS:
m/z 319 [M]+, 255 [M-SO2]+, 178 [M-C6H5SO2]+, 141
[C6H5SO2]+, 91 [C7H7]+.
N-(1-Hydroxy-2-methylpropan-2-yl)-N-methyl
benzenesulfonamide (5a): Brown greasy liquid,Yield 75 %.
IR (KBr, νmax, cm-1): 3052 (C-H, stretching of aromatic ring),
1628, 1523 (C=C, aromatic stretching), 1344 (-SO2-NH-,
stretching); 1H NMR (500 MHz, CDCl3): δ 7.85 (dd, J = 8.5,
2.1 Hz, 2H, H-2', H-6'), 7.56 (m, 1H, H-4'), 7.49 (m, 2H, H-3',
H-5' ), 3.72 (s, 2H, CH2-1), 2.98 (s, 3H, CH3-1'') and 1.21 (s,
6H, CH3-3, CH3-4); EIMS: m/z 243 [M]+, 179 [M-SO2]+, 102
[M-C6H5SO2]+, 141 [C6H5SO2]+.
N-Ethyl-N-(1-hydroxy-2-methylpropan-2-yl)benzene
sulfonamide (5b): Transparent gammy liquid,Yield 70 %. IR
(KBr, νmax, cm-1): 3054 (C-H, stretching of aromatic ring), 1621,
1522 (C=C, aromatic stretching), 1342 (-SO2-NH-, stretching);
1H NMR (500 MHz, CDCl3): δ 7.87 (dd, J = 8.5, 2.1 Hz, 2H,
H-2', H-6'), 7.54 (m, 1H, H-4'), 7.48 (m, 2H, H-3', H-5'), 3.66
(s, 2H, CH2-1), 3.44 (q, 2H, CH2-1''), 1.31 (s, 6H, CH3-3, CH3-
4) and 1.18 (t, J = 7.0, 3H, CH3-2''); EIMS: m/z 257 [M]+, 193
[M-SO2]+, 116 [M-C6H5SO2]+, 141 [C6H5SO2]+.
N-(2-Phenylethyl)-N-(1-hydroxy-2-methylpropan-2-
yl)benzenesulfonamide (5h): Gammy liquid,Yield 71 %. IR
(KBr, νmax, cm-1): 3038 (C-H, stretching of aromatic ring), 1624,
1521 (C=C, aromatic stretching), 1349 (-SO2-NH-, stretch-
ing); 1H NMR (500 MHz, CDCl3): δ 7.98 (dd, J = 8.5, 2.1 Hz,
2H, H-2', H-6'), 7.67 (m, 1H, H-4'), 7.55 (m, 2H, H-3', H-5'),
7.27-7.14 (m, 5H, H-2" to H-6"), 3.58 (t, J = 8.0 Hz, 2H,
H-8"), 3.15 (t, J = 7.0 Hz, 2H, H-7"), 3.70 (s, 2H, CH2-1) and
1.32 (s, 6H, CH3-3, CH3-4); EIMS: m/z 333 [M]+, 269 [M-
SO2]+, 192 [M-C6H5SO2]+, 141 [C6H5SO2]+, 91 [C7H7]+.
N-(3-Phenylpropyl)-N-(1-hydroxy-2-methylpropan-2-
yl)benzenesulfonamide (5i): Yellow liquid, Yield 71 %. IR
(KBr, νmax, cm-1): 3028 (C-H, stretching of aromatic ring), 1619,
1528 (C=C, aromatic stretching), 1351 (-SO2-NH-, stretching);
N-Butyl-N-(1-hydroxy-2-methylpropan-2-yl)benzene
sulfonamide (5c): Transparent greasy liquid, Yield 78 %. IR
(KBr, νmax, cm-1): 3046 (C-H, stretching of aromatic ring), 1623,
1525 (C=C, aromatic stretching), 1346 (-SO2-NH-, stretching);
1H NMR (500 MHz, CDCl3): δ 7.91 (dd, J = 8.5, 2.1 Hz, 2H,
H-2', H-6'), 7.63 (m, 1H, H-4'), 7.55 (m, 2H, H-3', H-5'), 3.65

3292 Aziz-Ur-Rehman et al.
Asian J. Chem.
1H NMR (500 MHz, CDCl3): δ 7.97 (dd, J = 8.5, 2.1 Hz, 2H,
H-2', H-6'), 7.65 (m, 1H, H-4'), 7.50 (m, 2H, H-3', H-5'), 7.28-
7.15 (m, 5H, H-2" to H-6"), 3.33 (t, J = 7.0 Hz, 2H, H-9"),
2.80 (t, J = 7.5 Hz, 2H, H-7"), 2.15 (t, J = 7.5 Hz, 2H, H-8"),
3.78 (s, 2H, CH2-1) and 1.35 (s, 6H, CH3-3, CH3-4); EIMS:
m/z 347 [M]+, 283 [M-SO2]+, 206 [M-C6H5SO2]+, 141
[C6H5SO2]+, 91 [C7H7]+.
with cold water and recrystallized by using methanol. The
parent compound 3 was synthesized as white amorphous
powder. The molecular formula C10H15NO3S was established
by HR-MS showing molecular ion peak at m/z 229.343 (calcd.
(%) for C14H15NO2S, 229.340). The IR spectrum revealed the
presence of a sulfonyl group (1338, 1447 cm-1) and -NH- (3100
cm-1) group in the molecule. The EI-MS gave a distinct peak
at m/z 165 after the removal -SO2 group and further a peak
was observed at m/z 141 which showed the presence of
benzenesulfonyl group in the molecule. In the aromatic
RESULTS AND DISCUSSION
The objective of our research work was to synthesize N-
substituted derivatives of N-(1-hydroxy-2-methyl propan-2-
yl)benzenesulfonamide and to screen out their enzymatic
activities. Parent compound 3 was synthesized by the reaction
of 2-amino-2-methyl propan-1-ol (1) with benzene sulfonyl
chloride (2) in aqueous media14. Further, a series of N-substi-
tuted derivatives (Scheme-I) were brought about by treating
compound 3 with different electrophiles, 4a-i, in the presence
of N,N-dimethyl formamide and NaH which acts as a base.
Reactants completely converted into products by simple
stirring after 1-3 h. Precipitates were quenched by treating
1
region of the H NMR spectrum signals appeared at δ 7.90
(dd, J = 8.5, 2.1 Hz, 2H, H-2', H-6'), 7.56 (m, 1H, H-4') and
7.49 (m, 2H, H-3', H-5'), due to downfield shift, protons were
assigned to the mono substituted sulfonyl ring. In the aliphatic
region of the 1H NMR spectrum, signals appeared at δ 2.27 (s,
2H, CH2-1) and 1.14 (s, 6H, CH3-3, CH3-4); indicated the
presence of one methylene and two methyl groups in the mole-
cule. On the basis of above evidences the structure of compound
3 was assigned as N-(1-hydroxy-2-methylpropan-2-yl)benzene
sulfonamide. The structure was also confirmed from its crystal
O
CH
C
O
3
O
CH
C
O
3
OH
S
Na CO
2
S
3
OH
CH
N
H
2
Cl
CH
H N
2
2
CH
3
H O, Stir.
2
3
CH
3
1
2
Stirr at rt.
DMF
R
X
4a-i
3
O
O
CH
2
C
3
OH
S
1
3'
CH
N
R
1'
2
5'
4CH
3
5a-i
Compound
5a
R
Compound
5f
R
H
Ha
C
C
CH3
1''
2'' 3'' Hb
CH2
1''
7"
CH
2
2''
CH2 CH3
2''
5b
5c
5g
5h
1''
6''
4''
7''
CH
2
8''
CH
2''
CH2 CH2 CH2 CH3
3''
2
4''
2''
1''
6''
4''
2''
7''
CH
9''
CH
2
8''
CH
2
CH2 CH2 CH2 CH2 CH3
3''
2
5d
5e
5i
4''
5''
2''
1''
6''
4''
3''
CH3
–
–
CH2 CH
2''
4''
CH3
1''
Scheme-I: Outline for the synthesis of N-substituted derivatives of N-(1-hydroxy-2-methyl propan-2-yl)benzenesulfonamide

Vol. 25, No. 6 (2013)
Synthesis of N-Substituted Derivatives of N-(1-Hydroxy-2-methylpropan-2-yl)benzenesulfonamide 3293
TABLE-1
EVALUATION OF BIOLOGICAL ACTIVITIES OF N-SUBSTITUTED DERIVATIVES OF
N-(1-HYDROXY-2-METHYL PROPAN-2-YL)BENZENESULFONAMIDE
DPPH
Inhibition (%) at
0.5 mM
AChE
BChE
LOX
Sample
No.
IC50
(µmol)
Inhibition (%)
IC50
(µmol)
Inhibition (%)
IC50
(µmol)
Inhibition (%)
IC50
(µmol)
at 0.5 mM
35.29 0.47
20.41 0.95
50.02 0.83
23.13 1.01
23.45 0.93
37.02 0.89
20.85 0.77
32.41 0.95
29.34 0.91
36.41 0.85
Eserine
at 0.5 mM
60.23 0.58
69.23 0.87
71.60 0.45
71.03 1.02
79.87 1.11
87.92 0.98
65.23 0.82
62.22 0.83
71.23 0.87
69.85 1.13
Eserine
at 0.5 mM
13.41 0.66
38.20 0.45
44.91 1.06
36.41 0.92
41.44 0.72
38.08 0.76
26.59 0.84
48.21 0.44
48.20 0.45
31.41 0.70
Baicalein
92.67 0.59
91.63 0.78
74.42 0.75
84.58 0.91
83.83 0.84
63.23 0.73
71.57 1.02
83.61 0.78
61.60 0.72
73.80 0.74
Quercetin
89.21 0.89
97.43 0.98
103.12 0.91
75.57 0.79
81.78 0.87
59.19 0.95
61.88 0.97
111.41 0.92
154.43 0.91
101.73 0.77
16.96 0.14
Nil
Nil
165.36 0.85
159.36 0.91
139.71 0.85
149.99 0.89
111.54 0.92
65.47 0.69
79.36 0.92
179.33 0.97
185.36 0.98
131.51 0.91
0.85 0.001
Nil
Nil
3
5a
<500
Nil
Nil
5b
Nil
5c
Nil
<500
Nil
5d
Nil
5e
Nil
Nil
5f
Nil
<500
<500
Nil
5g
Nil
5h
Nil
5i
Control
0.04 0.001
22.4 1.3
Note: IC50 values (concentration at which there is 50 % enzyme inhibition) of compounds were calculated using EZ-Fit Enzyme kinetics software
(Perella Scientific Inc. Amherst, USA). AChE = Acetyl cholinesterase. BChE = Butyrylcholinesterase. LOX = Lipoxygenase. DPPH = 1,1-
diphenyl-2-picrylhydrazyl radical.
data15. During the course of this study we obtained some N-
substituted derivatives of sulfonamides in good yield and others
moderate to low. On the basis of data from IR, EIMS and 1H
NMR, the structures of N-substituted derivatives of N-(1-hy-
droxy-2-methyl propan-2-yl)benzenesulfonamides were elu-
cidated as described in experimental section.
Conclusion
The proposed structure of the synthesized compound is
well supported by spectroscopic data. From the enzyme
inhibition data (Table-1), it may be concluded that the two
compounds 5e and 5f have talented activity against butyryl-
cholinesterase enzyme with IC50 value 65.47 0.69 and 79.36
0.92 µmol, respectively but all other compounds showed
moderate activity.All the synthesized compounds also showed
good scavenging activity against DPPH but all were remained
inactive against acetylcholinesterase and lipoxygenase
enzymes. Hence on the basis of aforesaid results, these synthe-
sized derivatives provide an overall indispensable basis to
introduce new drug candidates for the treatment ofAlzheimer's
disease and other associated diseases. Due to having anti-
oxidant properties, these can be helpful in controlling many
degenerative diseases.
Enzyme inhibition activity: The screening of these
synthesized compounds against acetylcholinesterase (AchE),
butyrylcholinesterase (BChE) and lipoxygenase enzymes
(LOX) revealed that they were exhibited good inhibitory
potential against butyrylcholinesterase as it was evident from
their IC50 values but remained inactive against acetylcholines-
terase and lipoxygenase enzymes. The results are depicted in
Table-1. It is clearly evident from results that compounds
N-(butan-2-yl)-N-(1-hydroxy-2-methylpropan-2-yl)benzene
sulfonamide (5e) and N-(allyl)-N-(1-hydroxy-2-methylpropan-
2-yl)benzenesulfonamide (5f) was found to be potent inhibitor
having IC50 value of 65.47 0.69 and 79.36 0.92 µmol,
relative to eserine, a reference standard with IC50 value of 0.85
0.001 µmol, probably due to the N-substitution of isobutyl
and allyl groups in the molecules, respectively. DPPH is a stable
free radical at room temperature. DPPH radical is scavenged
by antioxidants through the donation of a proton and form
reduced DPPH. The colour changes from violet to yellow after
reduction of DPPH and it can be quantified by decrease of
absorbance at wavelength 517 nm. Radical scavenging activity
increased with increasing percentage of the free radical inhi-
bition. The colour change from violet to yellow and fall in
absorbance of the stable radical DPPH was measured for three
different concentrations of samples and the results are shown
in Table-1. These results showed that the compounds 5e and
5f also showed good scavenging activity against DPPH. The
IC50 value for these compounds 59.19 0.95 and 61.88
0.97 µmol, relative to quercetin, a reference standard with IC50
value of 16.96 0.14 µmol, was calculated from the curves
plotted. IC50 is the concentration of fraction causing 50 %
inhibition of absorbance and lower its value means greater
antioxidant activity of the fraction.
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