Design, synthesis, and biological evaluation of sulfonic acid ester and benzenesulfonamide derivatives as potential CETP inhibitors

Article abstract of DOI:10.1007/s00044-011-9917-5

Epidemiological studies have established an inverse relationship between plasma high-density lipoprotein (HDL) cholesterol concentration, and incidence of coronary artery disease (CAD); thus, the development of novel therapies that attempt to exploit the atheroprotective functions of HDL is a major goal. Inhibition of cholesteryl ester transfer protein (CETP) is one of the approaches targeted to increase HDL cholesterol concentration. CETP is a glycoprotein involved in transporting lipoprotein particles and neutral lipids between HDL and low-density lipoproteins (LDL), and therefore CETP inhibitors could be useful agents in the future for treating dyslipidemia and related disorders. Guided by our previously reported pharmacophore and QSAR models for CETP inhibition, we synthesized and bioassayed a series of sulfonic acid ester and benzenesulfonamide derivatives that can serve as a promising lead compounds for the development of potential and selective CETP inhibitors. The most potent compound 6k illustrated an IC50 of 3.4 lM. Springer Science+Business Media, LLC 2011.

Full text of DOI:10.1007/s00044-011-9917-5

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res (2012) 21:3669–3680
DOI 10.1007/s00044-011-9917-5
ORIGINAL RESEARCH
Design, synthesis, and biological evaluation of sulfonic acid ester
and benzenesulfonamide derivatives as potential CETP inhibitors
•
Reema Abu Khalaf Ghassan Abu Sheikha
•
•
Mahmoud Al-Sha’er Ghadeer Albadawi
•
Mutasem Taha
Received: 1 September 2011 / Accepted: 16 November 2011 / Published online: 30 November 2011
Ó Springer Science+Business Media, LLC 2011
Abstract Epidemiological studies have established an
inverse relationship between plasma high-density lipopro-
tein (HDL) cholesterol concentration, and incidence of
coronary artery disease (CAD); thus, the development of
novel therapies that attempt to exploit the atheroprotective
functions of HDL is a major goal. Inhibition of cholesteryl
ester transfer protein (CETP) is one of the approaches
targeted to increase HDL cholesterol concentration. CETP
is a glycoprotein involved in transporting lipoprotein par-
ticles and neutral lipids between HDL and low-density
lipoproteins (LDL), and therefore CETP inhibitors could be
useful agents in the future for treating dyslipidemia and
related disorders. Guided by our previously reported
pharmacophore and QSAR models for CETP inhibition, we
synthesized and bioassayed a series of sulfonic acid ester
and benzenesulfonamide derivatives that can serve as a
promising lead compounds for the development of poten-
tial and selective CETP inhibitors. The most potent com-
pound 6k illustrated an IC50 of 3.4 lM.
Introduction
Cardiovascular disease continues to be a leading cause of
death worldwide. Dyslipidemia, a major risk factor for
cardiovascular disease, represents a multifactorial disease
and current antidyslipidemic medicines focus on either
lowering low-density lipoproteins (LDL) cholesterol or
raising high-density lipoprotein (HDL) cholesterol (Grass
et al., 1995; Paigen et al., 1990; Hansson, 2005).
A number of epidemiological studies have established an
inverse relationship between serum HDL cholesterol levels
and the incidence of ischemic heart disease (Julve et al.,
2011; Lamarche et al., 1996). HDL removes excess choles-
terol from peripheral tissues to the liver for biliary elimina-
tion (Cuchel et al., 2010; Lewis, 2006; Tall et al., 2001).
CETP, a 476-residue glycoprotein, is engaged in inter-
changing lipoprotein particles and neutral lipids, including
cholesteryl esters, phospholipids, and triglycerides between
HDL and LDL (Chapman et al., 2010). CETP, as revealed by
˚
X-ray crystallography (PDB code: 2OBD, resolution 2.2 A),
Keywords CETP inhibitors Á High-density lipoprotein Á
Pharmacophore modeling Á Benzenesulfonamide Á
Sulfonic acid ester
has a lipophilic binding site capable of binding up to four
lipid molecules (Qiu et al., 2007). In human plasma, CETP
plays a proatherogenic task by moving cholesteryl esters
from HDL to very low-density lipoprotein (VLDL) and LDL
particles, thereby lowering atheroprotective HDL choles-
terol and raising proatherogenic VLDL and LDL cholester-
ols. Obviously, the risk of coronary artery disease (CAD) is
proportional to the plasma levels of CETP (Vasan et al.,
2009; Boekholdt et al., 2004). Actually, It is rather frequent
within the CAD population to have elevated CETP plasma
protein levels that are 2- to 3-fold higher than concentrations
typically found in the plasma of normal subjects (1–3 lg/ml)
(McPherson et al., 1991).
R. Abu Khalaf (&) Á G. Abu Sheikha Á G. Albadawi
Department of Pharmacy, Faculty of Pharmacy,
Al-Zaytoonah University of Jordan, Amman,
Jordan
e-mail: reema.abukhalaf@zuj.edu.jo;
rima_abu_khalaf@yahoo.com
M. Al-Sha’er
Faculty of Pharmacy, Zarqa University, Zarqa, Jordan
M. Taha
Drug Discovery Unit, Department of Pharmaceutical Sciences,
Faculty of Pharmacy, University of Jordan, Amman, Jordan
Indication exists that the outcomes of CETP activity
may depend on the metabolic setting, particularly on
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Med Chem Res (2012) 21:3669–3680
triglyceride levels. Therefore, pharmacological CETP
inhibition may reduce the risk of CAD in humans, but only
in those with high triglyceride levels (Vasan et al., 2009;
Boekholdt et al., 2004).
synthesized compounds, we explore the electronic effect of
different substituents such as CF3, Br, NO2, Cl, OCH3, and
CH3 together with the compound lipophilicity effect on the
CETP inhibitory activity.
The inaccessibility of a reasonable high-resolution
crystallographic structures for CETP combined with its
large binding pocket locked up most modeling-related
discovery projects to ligand-based approaches particularly
quantitative structure–activity relationship analysis
(QSAR) (Castilho et al., 2007; Hanumantharao et al., 2005;
Kelkar et al., 2004; Cronin and Schultz, 2003; Akamatsu,
2002).
Materials and methods
General methods
The proposed structures for compounds 6a–6l and 8a–8l
were confirmed via elemental analyses, IR spectroscopy,
1
Earlier, we have developed ligand-based three-dimen-
sional (3D) pharmacophores integrated within self-consis-
tent QSAR model for CETP inhibitors. The pharmacophore
models were used as 3D search queries to mine 3D libraries
for new CETP inhibitors, while the QSAR model predicted
their biological activities and therefore prioritize them for
in vitro evaluation (Abu Khalaf et al., 2010; Abu Sheikha
et al., 2010). Our shape-constrained Hypo4/8 captured the
most potent hit (1) with IC50 value of 1.9 lM (see Fig. 1)
(Abu Khalaf et al., 2010).
mass spectroscopy, H- and 13C-NMR spectra.
Melting points were measured using Gallenkampf
1
melting point apparatus and are uncorrected. H- and 13C-
NMR spectra were collected on a Varian Oxford NMR300
spectrometer. The samples were dissolved in CDCl3.
Mass spectrometry was performed using LC Mass Bruker
Apex-IV mass spectrometer utilizing an electrospray
interface.
Infrared spectra were recorded using Shimadzu IRAf-
finity-1 spectrophotometer. The samples were dissolved in
CHCl3 and analyzed as thin solid films using NaCl plates.
Analytical thin layer chromatography (TLC) was carried
out using pre-coated aluminum plates and visualized by
UV light (at 254 and/or 360 nm). Elemental analysis was
performed using EuroVector elemental analyzer.
Chemicals and solvents were purchased from corre-
sponding companies (Sigma-Aldrich, Riedel-de Haen,
Fluka, BDH Laboratory Supplies and Promega Corpora-
tion) and were used in the experimentation without further
purification.
However, optimization based upon the pharmacophoric
features of hit 1 and the lipophilic binding site of CETP
target guided us to design and synhesize a novel series of
derivatives of N-(4-benzyloxyphenyl)-4-methyl-benzene-
sulfonamide (6a–6g, Scheme 1), N-(4-benzyloxyphenyl)-N-
(4-methylbenzenesulfonyl)-4-methylbenzenesulfonamide
(6h–6l, Scheme 1), N-(4-benzylaminophenyl)-toluene-4-
sulfonic acid ester (8a–8c, Scheme 2), and 4-(N,N)-[bis-
(benzylaminophenyl)]-toluene-4-sulfonic acid ester (8d–8l,
Scheme 2) that have CETP inhibitory activities. In the newly
Fig. 1 The mapping of shape-
complemented Hypo4/8
pharmacophore hypotheses
against hit 1 ((HBA) Hydrogen
bond acceptor, (Hph)
hydrophobic features, (RA) ring
aromatic): a Inhibitor 1,
b Hypo4/8 fitted against 1
O
S
O
NH
S
Cl
(a)
(b)
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Med Chem Res (2012) 21:3669–3680
3671
Scheme 1 Synthesis of N-(4-
benzyloxyphenyl)-4-methyl-
benzenesulfonamide (6a–6g)
and N-(4-benzyloxyphenyl)-N-
(4-methylbenzenesulfonyl)-4-
methylbenzenesulfonamide
(6h–6l) derivatives. Reagents
and conditions: (a) DCM, TEA,
RT, 2 h; (b) DMF, NaOH, RT,
3 h
NH2
H3C
a
O
R
O
S
S
N
H3C
Cl +
O
O
4a,b
3
2
OH
4a R= H
4b R= Sulfonyl-4-CH3-benzene
OH
H3C
b
X
O
R
S
6a-6l
5a-5i
N
O
6a X= 4-CF3, R= H
6b X= 4-Br, R= H
6c X= 4-CH3, R= H
6d X= 4-NO2, R= H
6e X= 3-Cl, R= H
6f X= 4-Cl, R= H
O
5a X= 4-CF3
5b X= 4-Br
5c X= 4-CH3
5d X= 4-NO2
5e X= 3-CF3
5f X= 3-Cl
5g X= 4-Cl
5h X= 3-CH3
5i X= 3-OCH3
Br
6g X= 3-OCH3, R= H
6h X= 3-CF3, R= Sulfonyl-4-CH3-benzene
6i X= 3-Cl, R= Sulfonyl-4-CH3-benzene
6j X= 4-Cl, R= Sulfonyl-4-CH3-benzene
6k X= 3-CH3, R= Sulfonyl-4-CH3-benzene
6l X= 3-OCH3, R= Sulfonyl-4-CH3-benzene
X
General procedure for the synthesis of N-(4-
benzyloxyphenyl)-4-methyl-benzenesulfonamide
and N-(4-benzyloxyphenyl)-N-(4-
stirred at room temperature for 3 h and then DMF was
evaporated. The residue was dissolved in CH2Cl2 (10 ml)
and extracted with water (10 ml). The organic extract was
dried on anhydrous Na2SO4 and filtered. The residue, after
evaporation of the solvent, was purified by column chro-
matography eluting with CH2Cl2/cyclohexane (85:15)
to give N-(4-benzyloxyphenyl)-4-methyl-benzenesulfona-
mide derivatives 6a–6g.
methylbenzenesulfonyl)-4-methylbenzenesulfonamide
derivatives (6a–6l)
Tosyl chloride 2 (0.953 g, 5 mmol) was dissolved in
CH2Cl2 (10 ml) in an ice bath and p-aminophenol 3
(0.655 g, 6 mmol) was added. Then, triethylamine
(0.83 ml, 6 mmol) was added. The mixture was stirred at
room temperature for 2 h and then extracted with water
(10 ml). The organic extract was dried on anhydrous
Na2SO4 and filtered. The residue, after evaporation of the
solvent, was purified by column chromatography eluting
with CH2Cl2/MeOH (95:5) to give N-(4-hydroxy-phenyl)-
4-methyl-benzenesulfonamide 4a (0.397 g, 30%) and 4b
(0.167 g, 16%).
In addition, N-(4-hydroxyphenyl)-N-(4-methylbenzene-
sulfonyl)-4-methylbenzenesulfonamide 4b (1.169 g, 2.8
mmol) was dissolved in DMF (5 ml) in an ice bath and one
of the substituted benzyl bromides 5a–5i (3.6 mmol) was
added. Then, NaOH (0.24 g, 6 mmol) was added. The
mixture was stirred at room temperature for 3 h and then
DMF was evaporated. The residue was dissolved in
CH2Cl2 (10 ml) and extracted with water (10 ml). The
organic extract was dried on anhydrous Na2SO4 and fil-
tered. The residue, after evaporation of the solvent, was
purified by column chromatography eluting with CH2Cl2/
cyclohexane (85:15) to give N-(4-benzyloxyphenyl)-N-
(4-methylbenzenesulfonyl)-4-methylbenzenesulfonamide
derivatives 6h–6l.
Subsequently, N-(4-hydroxy-phenyl)-4-methyl-benze-
nesulfonamide 4a (0.741 g, 2.8 mmol) was dissolved in
DMF (5 ml) in an ice bath and one of the substituted
benzyl bromides 5a–5i (3.6 mmol) was added. Then,
NaOH (0.24 g, 6 mmol) was added. The mixture was
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Med Chem Res (2012) 21:3669–3680
Scheme 2 Synthesis of
NH2
H3C
4-benzylaminophenyl-toluene-
4-sulfonic acid ester (8a–8c)
and 4-(N,N)-[bis-
(benzylaminophenyl)]-toluene-
4-sulfonic acid ester (8d–8l)
derivatives. Reagents and
conditions: (a) DCM, TEA, RT,
2 h; (b) DMF, RT, 3 h
O
O
S
S
O
a
H3C
Cl
+
O
O
7
3
2
OH
NH2
b
H3C
X
O
S
5b-5h, 5j and 5k
Br
O
O
8a-8l
5b X= 4-Br
5c X= 4-CH3
5d X= 4-NO2
5e X= 3-CF3
5f X= 3-Cl
5g X= 4-Cl
5h X= 3-CH3
5j X= 3-Br
8a X= 3-CH3, R= H
8b X= 3-Br, R= H
8c X= 3-NO2, R= H
8d X= 4-Br, R= 4-Br-Benzyl
N
8e X= 4-CH3, R= 4-CH3-Benzyl
8f X= 4-NO2, R= 4-NO2-Benzyl
8g X= 3-CF3, R= 3-CF3-Benzyl
8h X= 3-Cl, R= 3-Cl-Benzyl
8i X= 4-Cl, R= 4-Cl-Benzyl
8j X= 3-CH3, 3-CH3-Benzyl
8k X= 3-Br, R= 3-Br-Benzyl
8l X= 3-NO2, 3-NO2-Benzyl
R
X
5k X= 3-NO2
N-(4-Hydroxy-phenyl)-4-methyl-benzenesulfonamide (4a)
Offwhite powder (30%): Rf = 0.77 (CHCl3–MeOH, 95:5);
4-Methyl-N-[4-(4-trifluoromethyl-benzyloxy)-phenyl]-
benzenesulfonamide (6a)
1
mp. 162–163°C; H-NMR (300 MHz, CDCl3) d 10.3 (s,
White powder (33%): Rf = 0.85 (CHCl3–MeOH, 98:2);
1
mp. 115–116°C; H-NMR (300 MHz, CDCl3) d 7.58 (d,
1H, OH), 7.62 (d, J = 8.25 Hz, 2H), 7.40 (d, J = 8.33 Hz,
2H), 6.95 (dd, J = 8.94, 3.0 Hz, 2H), 6.85 (dd, J = 8.96,
2.98 Hz, 2H), 2.35 ppm (s, 3H); 13C-NMR (300 MHz,
CDCl3) d 146.25 (1C), 145.53 (1C), 137.32 (1C), 131.68
(1C), 130.21 (2C), 127.16 (2C), 123.41 (2C), 121.51 (2C),
21.66 ppm (1C); IR (thin film) cm-1 3465, 3021, 2963,
1721, 1603, 1501, 1377, 1215.
J = 7.82 Hz, 2H), 7.48 (dd, J = 12.09, 6.96 Hz, 2H), 7.25
(m, 4H), 7.85 (m, 2H), 6.72 (d, J = 8.75 Hz, 1H), 6.42
(d, J = 8.76 Hz, 1H), 4.70 (s, 2H), 2.42 ppm (s, 3H); 13C-
NMR (300 MHz, CDCl3) d 148.76 (1C), 145.71 (1C),
144.18 (1C), 140.03 (1C), 137.53 (1C), 135.13 (1C),
129.94 (2C), 129.76 (2C), 127.47 (2C), 125.43(2C),
123.08 (2C), 113.06 (2C), 54.21 (1C), 26.96 (1C),
21.74 ppm (1C); IR (thin film) cm-1 3399, 3032, 2963,
1597, 1497, 1454; MS (ESI, positive mode) m/z
[M ? Na]? 444.08517 (C21H18F3NNaO3S requires
444.43377); Anal. Calcd for C21H18F3NO3S: C 59.85, H
4.31, F 13.52, N 3.32, S 7.61, found: C 59.57, H 4.93, F
13.52, N 3.25, S 7.81.
N-(4-Hydroxyphenyl)-N-(4-methylbenzenesulfonyl)-4-
methylbenzenesulfonamide (4b)
White powder (16%): Rf = 0.85 (CHCl3–MeOH, 95:5);
1
mp. 150–151°C; H-NMR (300 MHz, CDCl3) d 10.4 (s,
1H, OH), 7.59 (d, J = 8.34 Hz, 2H), 7.44 (d, J = 8.28 Hz,
2H), 6.95–7.10 (m, 4H), 6.75–6.89 (m, 4H), 2.43 ppm (s,
6H); 13C-NMR (300 MHz, CDCl3) d 148.68 (1C), 145.65
(1C), 134.50 (1C), 134.31 (1C), 131.91 (2C), 131.30 (2C),
129.80 (2C), 129.72 (2C), 128.54 (2C), 128.19 (2C),
123.03 (2C), 21.78 (1C), 21.65 ppm (1C); IR (thin film)
cm-1 3512, 3027, 2959, 1725, 1601, 1500, 1368, 1221.
N-[4-(4-Bromo-benzyloxy)-phenyl]-4-methyl-
benzenesulfonamide (6b)
Off-white powder (63%): Rf = 0.75 (CHCl3); mp. 129–
130°C; 1H-NMR (300 MHz, CDCl3) d 7.66 (d, J =
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Med Chem Res (2012) 21:3669–3680
3673
N-[4-(3-Chloro-benzyloxy)-phenyl]-4-methyl-
benzenesulfonamide (6e)
8.27 Hz, 2H), 7.42 (d, J = 8.32 Hz, 2H), 7.28 (d,
J = 8.25 Hz, 2H), 7.18 (d, J = 8.28 Hz, 2H), 6.73 (dd,
J = 6.89, 1.94 Hz, 2H), 6.43 (dd, J = 6.95, 1.86 Hz, 2H),
4.23 (s, 2H), 2.45 ppm (s, 3H); 13C-NMR (300 MHz,
CDCl3) d 146.46 (1C), 145.13 (1C), 141.20 (1C), 137.80
(1C), 132.52 (1C), 131.82 (2C), 129.68 (2C), 129.11
(2C), 128.62 (2C), 123.32 (2C), 121.20 (1C), 113.19
(2C), 47.86 (1C), 21.79 ppm (1C); IR (thin film) cm-1
3399, 3030, 2967, 1605, 1520, 1489, 1474; MS (ESI,
positive mode) m/z [M ? Na]? 455.00830 (C20H18BrN-
NaO3S requires 455.33186); Anal. Calcd for C20H18
BrNO3S: C 55.56, H 4.20, Br 18.48, N 3.24, S 7.42, found:
C 55.86, H 4.37, Br 18.48, N 3.06, S 7.31.
1
White oil (13.6%): Rf = 0.82 (CHCl3–MeOH, 98:2); H-
NMR (300 MHz, CDCl3) d 7.7 (d, J = 8.31 Hz, 2H),
7.15–7.40 (m, 6H), 6.7 (dd, J = 6.83, 2.19 Hz, 2H), 6.4
(dd, J = 6.86, 2.2 Hz, 2H), 4.15 (s, 2H), 2.4 ppm (s, 3H);
13C-NMR (300 MHz, CDCl3) d 146.60 (1C), 145.09 (1C),
141.15 (1C), 141.13 (1C), 134.62 (1C), 132.56 (2C),
130.01 (2C), 129.67 (2C), 128.62 (2C), 127.56 (1C),
127.39 (1C), 125.42 (1C), 123.30 (2C), 113.05 (2C), 47.85
(1C), 21.75 ppm (1C); IR (thin film) cm-1 3426, 3063,
2924, 1601, 1512, 1431, 1177; MS (ESI, positive mode)
m/z [M ? Na]? 410.05881 (C20H18ClNNaO3S requires
410.06959).
4-Methyl-N-[4-(4-methyl-benzyloxy)-phenyl]-
benzenesulfonamide (6c)
N-[4-(4-Chloro-benzyloxy)-phenyl]-4-methyl-
benzenesulfonamide (6f)
Off-white powder (15%): Rf = 0.82 (CHCl3–MeOH,
98:2); mp. 119–120°C; 1H-NMR (300 MHz, CDCl3) d
7.68 (d, J = 8.27 Hz, 2H), 7.28 (d, J = 8.30 Hz, 2H), 7.15
(dd, J = 13.19, 8.01 Hz, 4H), 6.72 (dd, J = 8.92, 3.34 Hz,
2H), 6.45 (dd, J = 8.93, 1.99 Hz, 2H), 4.20 (s, 2H), 2.45
(s, 3H), 2.30 ppm (s, 3H); 13C-NMR (300 MHz, CDCl3) d
146.92 (1C), 145.01 (1C), 140.99 (1C), 137.17 (1C),
135.86 (1C), 132.64 (1C), 129.64 (2C), 129.42 (2C),
128.64 (2C), 127.56 (2C), 123.24 (2C), 113.02 (2C), 48.28
(1C), 21.75 (1C), 21.14 ppm (1C); IR (thin film) cm-1
3422, 3041, 2924, 1605, 1508, 1447; MS (ESI, positive
mode) m/z [M ? Na]? 390.11344 (C21H21NNaO3S
requires 390.46238); Anal. Calcd for C21H21NO3S: C
68.64, H 5.76, N 3.81, S 8.73, found: C 68.64, H 5.70, N
3.67, S 8.64.
White powder (30.4%): Rf = 0.82 (CHCl3–MeOH, 98:2);
1
mp. 120–121°C; H-NMR (300 MHz, CDCl3) d 7.68 (d,
J = 8.82 Hz, 2H), 7.20-7.32 (m, 6H), 6.72 (dd, J = 8.93,
2.08 Hz, 2H), 6.43 (dd, J = 8.95, 2.08 Hz, 2H), 4.25 (s,
2H), 2.42 ppm (s, 3H); 13C-NMR (300 MHz, CDCl3) d
146.61 (1C), 145.11 (1C), 141.12 (1C), 137.35 (1C),
133.12 (1C), 132.53 (1C), 129.68 (2C), 128.86 (1C),
128.80 (1C), 128.78 (2C), 128.62 (2C), 123.30 (2C),
113.08 (2C), 47.76 (1C), 21.79 ppm (1C); IR (thin film)
cm-1 3399, 3032, 2963, 1605, 1512, 1493, 1447, 1173; MS
(ESI, positive mode) m/z [M ? H]? 388.07687 (C20H19
ClNO3S requires 388.06959); Anal. Calcd for
C20H18ClNO3S: C 61.93, H 4.68, Cl 9.14, N 3.61, S 8.27,
found: C 60.14, H 4.84, Cl 9.14, N 3.32, S 8.91.
N-[4-(3-Methoxy-benzyloxy)-phenyl]-4-methyl-
benzenesulfonamide (6g)
4-Methyl-N-[4-(4-nitro-benzyloxy)-phenyl]-
benzenesulfonamide (6d)
Off-white powder (17.6%): Rf = 076 (CHCl3–MeOH,
1
Yellow powder (12%): Rf = 0.63 (CHCl3); mp.
118–119°C; 1H-NMR (300 MHz, CDCl3) d 8.25 (d,
J = 7.95 Hz, 2H), 7.78 (d, J = 7.47 Hz, 2H), 7.55 (d,
J = 8.02 Hz, 2H), 7.30 (d, J = 7.5 Hz, 2H), 6.78 (d,
J = 8.27 Hz, 2H), 6.45 (d, J = 7.97 Hz, 2H), 4.48 (s, 2H),
2.43 ppm (s, 3H); 13C-NMR (300 MHz, CDCl3) d 147.32
(1C), 146.66 (1C), 146.03 (1C), 145.20 (1C), 141.46 (1C),
132.53 (1C), 129.70 (2C), 129.31 (2C), 127.81 (2C),
124.00 (2C), 123.43 (2C), 113.27 (2C), 47.83 (1C),
21.78 ppm (1C); IR (thin film) cm-1 3395, 3063, 2843,
1605, 1516, 1474; MS (ESI, positive mode) m/z [M ?
Na]? 421.08286 (C20H18N2NaO5S requires 421.43340);
Anal. Calcd for C20H18N2O5S: C 60.29, H 4.55, N 7.03, S
8.05, found: C 60.40, H 4.25, N 6.94, S 8.54.
98:2); mp. 97–98°C; H-NMR (300 MHz, CDCl3) d 7.68
(d, J = 8.32 Hz, 2H), 7.18–7.31 (m, 4H), 6.78–6.92 (m,
2H), 6.72 (dd, J = 8.93, 2.13 Hz, 2H), 6.44 (dd, J = 8.96,
2.19 Hz, 2H), 4.26 (s, 2H), 3.80 (s, 3H), 2.42 ppm (s, 3H);
13C-NMR (300 MHz, CDCl3) d 159.98 (1C), 146.90 (1C),
145.03 (1C), 141.02 (1C), 140.53 (1C), 132.62 (1C),
129.78 (1C), 129.65 (2C), 128.64 (2 C), 123.25 (2C),
119.71 (1C), 113.12 (1C), 113.02 (2C), 112.73 (1C), 55.27
(1C), 48.44 (1C), 21.75 ppm (1C); IR (thin film) cm-1
3422, 3027, 2963, 1601, 1512, 1454, 1173; MS (ESI,
positive mode) m/z [M ? H]? 384.12641 (C21H22NO4S
requires 384.11913); Anal. Calcd for C21H21NO4S: C
65.78, H 5.52, N 3.65, S 8.36, found: C 65.36, H 5.62, N
3.27, S 8.15.
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Med Chem Res (2012) 21:3669–3680
4-Methyl-N-[4-(3-trifluoromethyl-benzyloxy)-phenyl]-N-
(toluene-4-sulfonyl)-benzenesulfonamide (6h)
4-Methyl-N-[4-(3-methyl-benzyloxy)-phenyl]-N-(toluene-4-
sulfonyl)-benzenesulfonamide (6k)
Off-white oil (29.5%): Rf = 0.85 (CHCl3–MeOH, 98:2);
1H-NMR (300 MHz, CDCl3) d 7.58 (d, J = 8.32 Hz, 2H),
7.46 (d, J = 8.27 Hz, 3H), 7.35 (m, 3H), 7.25 (m, 4H),
6.85 (m, 4H), 4.75 (s, 2H), 2.43 ppm (s, 6H); 13C-NMR
(300 MHz, CDCl3) d 148.88 (1C), 145.55 (1C), 144.07
(1C), 137.59 (1C), 136.90 (1C), 135.18 (1C), 132.28 (1C),
131.81 (1C), 129.97 (2C), 129.69 (2C), 129.02 (1C),
128.44 (2C), 127.72 (2C), 125.17 (2C), 125.12 (2C),
124.65 (1C), 124.60 (1C), 122.98 (2C), 54.28 (1C), 21.60
(1C), 21.52 ppm (1C); IR (thin film) cm-1 3032, 2963,
1597, 1497, 1451, 1161; MS (ESI, positive mode) m/z
[M ? Na]? 598.09609 (C28H24F3NNaO5S2 requires
598.10480).
White powder (32.1%): Rf = 0.82 (CHCl3–MeOH, 98:2);
1
mp. 125.5–126.5°C; H-NMR (300 MHz, CDCl3) d 7.58
(d, J = 8.36 Hz, 2H), 7.33–7.43 (m, 6H), 6.82–7.12 (m,
8H), 4.65 (s, 2H), 2.35 (s, 6H), 2.15 ppm (s, 3H); 13C-
NMR (300 MHz, CDCl3) d 148.12 (1C), 146.37 (1C),
144.27 (1C),137.98 (1C), 137.95 (1C), 136.24 (1C), 134.86
(1C), 131.42 (2C), 130.62 (2C), 130.31(1C), 130.29 (1C),
129.13 (2C), 128.70 (1C), 128.64 (3C), 127.83 (2C),
125.71 (1C), 122.89 (2C), 53.54 (1C), 21.68 (1C), 21.56
(1C), 21.41 ppm (1C); IR (thin film) cm-1 3028, 2955,
1597, 1497, 1451, 1165; MS (ESI, positive mode) m/z
[M ? Na]?
544.12091
(C28H27NNaO5S2
requires
544.13306); Anal. Calcd for C28H27NO5S2: C 64.47, H
5.22, N 2.69, S 12.29, found: C 64.70, H 5.28, N 3.49, S
11.64.
4-Methyl-N-[4-(3-chloro-benzyloxy)-phenyl]-N-(toluene-4-
sulfonyl)-benzenesulfonamide (6i)
4-Methyl-N-[4-(3-methoxy-benzyloxy)-phenyl]-N-(toluene-
4-sulfonyl)-benzenesulfonamide (6l)
1
White oil (48.8%): Rf = 0.79 (CHCl3–MeOH, 98:2); H-
NMR (300 MHz, CDCl3) d 7.58 (d, J = 8.35 Hz, 2H),
7.46 (d, J = 8.29 Hz, 2H), 7.22–7.30 (m, 4H), 7.05–7.18
(m, 4H), 6.78–6.90 (m, 4H), 4.60 (s, 2H), 2.40 ppm (s, 6H);
13C-NMR (300 MHz, CDCl3) d 148.73 (1C), 145.64 (1C),
144.08 (1C), 137.69 (1C), 134.90 (1C), 134.31 (1C),
131.91 (2C), 130.0 (2C), 129.80 (2C), 129.78 (2C), 129.72
(2C), 128.54 (2C), 128.50 (2C), 128.01 (1C), 126.69 (1C),
123.03 (2C), 54.12 (1C), 21.78 (1C), 21.65 ppm (1C); IR
(thin film) cm-1 3032, 2924, 1597, 1497, 1449, 1157; MS
(ESI, positive mode) m/z [M ? Na]? 564.06795 (C27H24
ClNNaO5S2 requires 564.07844).
White powder (18.0%): Rf = 0.88 (CHCl3–MeOH, 98:2);
1
mp. 148–149°C; H-NMR (300 MHz, CDCl3) d 7.55 (d,
J = 8.28 Hz, 2H), 7.47 (d, J = 8.22 Hz, 2H), 7.08–7.28
(m, 6H), 6.68–6.89 (m, 6H), 4.60 (s, 2H), 3.74 (s, 3H),
2.43 ppm (s, 6H); 13C-NMR (300 MHz, CDCl3) d 159.66
(1C), 148.57 (1C), 145.57 (1C), 143.90 (1C), 137.00 (1C),
135.04 (1C), 131.89 (1C), 130.04 (2C), 129.75 (2C),
129.67 (2C), 129.44 (2C), 128.53 (2C), 127.73 (2C),
122.88 (2C), 120.91 (1C), 113.88 (1C), 113.45 (1C), 55.22
(1C), 54.56 (1C), 21.79 (1C), 21.66 ppm (1C); IR (thin
film) cm-1 3029, 2924, 1597, 1497, 1458, 1165; MS (ESI,
positive mode) m/z [M ? Na]? 560.10835 (C28H27NNa
O6S2 requires 560.12798); Anal. Calcd for C28H27NO6S2:
C 62.55, H 5.06, N 2.61, S 11.93, found: C 61.85, H 5.03,
N 2.39, S 12.04.
4-Methyl-N-[4-(4-chloro-benzyloxy)-phenyl]-N-(toluene-4-
sulfonyl)-benzenesulfonamide (6j)
White powder (51.5%): Rf = 0.85 (CHCl3-MeOH, 98:2);
1
General procedure for synthesis of N-(4-
benzylaminophenyl)-toluene-4-sulfonic acid ester
and 4-(N,N)-[bis-(benzylaminophenyl)]-toluene-4-
sulfonic acid ester derivatives (8a–8l)
mp. 119.5-120.5°C; H-NMR (300 MHz, CDCl3) d 7.56
(d, J = 8.32 Hz, 2H), 7.45 (d, J = 8.26 Hz, 2H),
7.22–7.30 (m, 4H), 7.05–7.18 (m, 4H), 6.78–6.84 (m, 4H),
4.60 (s, 2H), 2.44 ppm (s, 6H); 13C-NMR (300 MHz,
CDCl3) d 148.70 (1C), 145.67 (1C), 144.04 (1C), 137.47
(1C), 134.90 (1C), 134.31 (1C), 130.07 (2C), 130.0 (2C),
129.76 (2C), 129.72 (2C), 129.65 (2C), 128.72 (2C),
128.66 (2C), 128.01 (1C), 127.71 (1C), 122.99 (2C), 54.03
(1C), 21.79 (1C), 21.67 ppm (1C); IR (thin film) cm-1
3028, 2963, 1597, 1497, 1447, 1262; MS (ESI, positive
mode) m/z [M ? Na]? 564.05881 (C27H24ClNNaO5S2
requires 564.07844); Anal. Calcd for C27H24ClNO5S2: C
59.82, H 4.46, Cl 6.54, N 2.58, S 11.83, found: C 59.07, H
5.05, Cl 6.14, N 2.19, S 11.37.
Tosyl chloride 2 (0.953 g, 5 mmol) was dissolved in
CH2Cl2 (10 ml) in an ice bath and p-aminophenol 3
(0.655 g, 6 mmol) was added. Then, triethylamine
(0.83 ml, 6 mmol) was added. The mixture was stirred at
room temperature for 2 h and then extracted with water
(10 ml). The organic extract was dried on anhydrous
Na2SO4 and filtered. The residue, after evaporation of the
solvent, was purified by column chromatography eluting
with CH2Cl2/MeOH (95:5) to give toluene-4-sulfonic acid
4-amino-phenyl ester 7 (0.503 g, 38%).
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3675
Subsequently, 4-aminophenyl-4-toluene-sulfonic acid
ester 7 (0.741 g, 2.8 mmol) was dissolved in DMF (5 ml)
in an ice bath and one of the substituted benzyl bromides
5b–5h, 5j, and 5k (3.6 mmol) was added. Then, NaOH
(0.24 g, 6 mmol) was added. The mixture was stirred at
room temperature for 3 h and then DMF was evaporated.
The residue was dissolved in CH2Cl2 (10 ml) and extracted
with water (10 ml). The organic extract was dried on
anhydrous Na2SO4 and filtered. The residue, after evapo-
ration of the solvent, was purified by column chromatog-
raphy eluting with CH2Cl2/cyclohexane (85:15) to give
N-(4-benzylaminophenyl)-toluene-4-sulfonic acid ester and
4-(N,N)-[bis-(benzylaminophenyl)]-toluene-4-sulfonic acid
ester derivatives 8a–8l.
145.08 (1C), 141.37 (1C), 141.17 (1C), 132.54 (1C),
130.52 (1C), 130.32 (2C), 129.67 (2C), 128.64 (2C),
125.90 (1C), 123.33 (2C), 122.86 (1C), 113.04 (2C),
47.81 (1C), 21.77 ppm (1C); IR (thin film) cm-1 3422,
3059, 2924, 1605, 1508, 1483; MS (ESI, positive mode)
m/z [M ? Na]? 455.00830 (C20H18BrNNaO3S requires
455.33186).
Toluene-4-sulfonic acid 4-(3-nitro-benzylamino)-phenyl
ester (8c)
Pale green oil (18.2%): Rf = 0.76 (CHCl3); 1H-NMR
(300 MHz, CDCl3) d 7.67 (d, J = 8.26 Hz, 2H), 7.25–7.53
(m, 6H), 6.82 (d, J = 9.07 Hz, 2H), 6.64 (d, J = 9.03 Hz,
2H), 4.95 (br s, 1H, NH), 4.50 (s, 2H), 2.44 ppm (s, 3H);
13C-NMR (300 MHz, CDCl3) d 148.24 (1C), 145.42 (1C),
140.64 (1C), 139.23 (1C), 138.78 (1C), 132.18 (1C), 129.88
(2C), 129.74 (2C), 128.60 (1C), 127.49 (1C), 122.66 (2C),
121.95 (2C), 110.93 (2C), 47.46 (1C), 21.77 ppm (1C); IR
(thin film) cm-1 3449, 3071, 2924, 1601, 1528, 1508, 1346;
MS (ESI, positive mode) m/z [M ? H]? 399.16944
(C20H19N2O5S requires 399.09364).
4-Aminophenyl-4-toluene-sulfonic acid ester (7)
White powder (38%): Rf = 0.80 (CHCl3–MeOH, 95:5);
1
mp. 140–141°C; H-NMR (300 MHz, CDCl3) d 7.64 (d,
J = 8.33 Hz, 2H), 7.41 (d, J = 8.01 Hz, 2H), 6.57 (dd,
J = 8.90, 2.19 Hz, 2H), 6.38 (dd, J = 8.94, 2.19 Hz, 2H),
5.18 (br s, 2H, NH2), 2.38 ppm (s, 3H); 13C-NMR
(300 MHz, CDCl3) d 148.37 (1C), 145.80 (1C), 139.47
(1C), 132.22 (1C), 130.50 (2C), 128.73 (2C), 122.96 (2C),
114.39 (2C), 21.64 ppm (1C); IR (thin film) cm-1 3378,
3021, 2967, 1721, 1610, 1505, 1424, 1215.
Toluene-4-sulfonic acid 4-[bis-(4-bromo-benzyl)-amino]-
phenyl ester (8d)
White powder (50%): Rf = 0.82 (CHCl3); mp. 129–130°C;
1H-NMR (300 MHz, CDCl3) d 7.68 (d, J = 8.27 Hz, 2H),
7.42 (d, J = 8.36 Hz, 4H), 7.25 (d, J = 8.04 Hz, 2H), 7.05
(d, J = 8.31 Hz, 4H), 6.73 (d, J = 9.14 Hz, 2H), 4.52 (s,
4H), 2.45 ppm (s, 3H); 13C-NMR (300 MHz, CDCl3) d
147.43 (1C), 145.16 (1C), 140.93 (2C), 136.75 (2C),
132.68 (1C), 131.90 (4C), 129.69 (2C), 128.57 (4C),
128.43 (1C), 123.26 (2C), 121.01 (2C), 113.19 (2C), 54.22
(2C), 21.79 ppm (1C); IR (thin film) cm-1 3051, 2963,
1601, 1508, 1455; MS (ESI, positive mode) m/z [M ? H]?
602.97937 (C27H24Br2NO3S requires 602.35046); Anal.
Calcd for C27H23Br2NO3S: C 53.93, H 3.86, Br 26.57, N
2.33, S 5.33, found: C 53.15, H 3.48, Br 26.48, N 2.62, S
5.64.
Toluene-4-sulfonic acid 4-(3-methyl-benzylamino)-phenyl
ester (8a)
Off-white oil (14.9%): Rf = 0.85 (CHCl3–MeOH, 98:2);
1H-NMR (300 MHz, CDCl3) d 7.68 (d, J = 8.31 Hz, 2H),
7.05–7.32 (m, 6H), 6.75 (dd, J = 8.91, 2.12 Hz, 2H), 6.44
(dd, J = 8.94, 2.14 Hz, 2H), 4.27 (s, 2H), 3.96 (br s, 1H,
NH), 2.44 (s, 3H), 2.30 ppm (s, 3H); 13C-NMR (300 MHz,
CDCl3) d 147.04 (1C), 145.03 (1C), 140.93 (1C), 138.77
(1C), 138.46 (1C), 132.61 (1C), 129.65 (2C), 128.65 (3C),
128.31 (1C), 128.22 (1C), 124.59 (1C), 123.25 (2C),
112.93 (2C), 48.47 (1C), 21.76 (1C), 21.47 ppm (1C); IR
(thin film) cm-1 3426, 3028, 2924, 1605, 1512, 1470,
1451; MS (ESI, positive mode) m/z [M ? H]? 368.13149
(C21H22NO3S requires 368.12421).
Toluene-4-sulfonic acid 4-[bis-(4-methyl-benzyl)-amino]-
phenyl ester (8e)
Toluene-4-sulfonic acid 4-(3-bromo-benzylamino)-phenyl
ester (8b)
Off-white powder (19%): Rf = 0.82 (CHCl3–MeOH,
98:2); mp. 149–150°C; 1H-NMR (300 MHz, CDCl3) d
7.68 (d, J = 8.06 Hz, 2H), 7.26 (d, J = 9.74 Hz, 2H), 7.08
(dd, J = 8.79, 7.94 Hz, 8H), 6.70 (d, J = 8.98 Hz, 2H),
6.53 (d, J = 9.04 Hz, 2H), 4.55 (s, 4H), 2.45 (s, 3H),
2.30 ppm (s, 6H); 13C-NMR (300 MHz, CDCl3) d 148.13
(1C), 144.98 (1C), 140.82 (1C), 136.70 (2C), 134.95 (2C),
132.97 (1C), 129.64 (2C), 129.64 (4C), 128.60 (2C),
126.56 (4C), 123.01 (2C), 112.69 (2C), 54.19 (2C), 21.76
Off-white oil (26%): Rf = 0.82 (CHCl3–MeOH, 98:2); 1H-
NMR (300 MHz, CDCl3) d 7.66 (d, J = 8.31 Hz, 2H),
7.48 (s, 1H), 7.38 (d, J = 7.49 Hz, 1H), 7.28 (d,
J = 8.05 Hz, 2H), 7.24 (d, J = 6.24 Hz, 1H), 7.19 (m,
1H), 6.74 (dd, J = 8.98, 2.18 Hz, 2H), 6.43 (dd, J = 8.98,
2.15 Hz, 2H), 4.10 (br s, 1H, NH), 4.30 (s, 2H), 2.42 ppm
(s, 3H); 13C-NMR (300 MHz, CDCl3) d 146.57 (1C),
123

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Med Chem Res (2012) 21:3669–3680
(1C), 21.13 ppm (2C); IR (thin film) cm-1 3062, 2974,
1601, 1501, 1462; MS (ESI, positive mode) m/z [M ? Na]?
494.17604 (C29H29NNaO3S requires 494.61150); Anal.
Calcd for C29H29NO3S: C 73.86, H 6.20, N 2.97, S 6.80,
found: C 73.94, H 6.36, N 2.63, S 6.23.
(ESI, positive mode) m/z [M ? Na]? 534.06679
(C27H23Cl2NNaO3S requires 534.07757).
Toluene-4-sulfonic acid 4-[bis-(4-chloro-benzyl)-amino]-
phenyl ester (8i)
White powder (10.4%): Rf = 0.70 (CHCl3); mp.
151–152°C; 1H-NMR (300 MHz, CDCl3) d 7.67 (d,
J = 8.26 Hz, 2H), 7.25-7.32 (m, 6H), 7.10 (d,
J = 8.31 Hz, 4H), 6.75 (dd, J = 9.07, 1.99 Hz, 2H), 6.51
(dd, J = 9.13, 2.19 Hz, 2H), 4.50 (s, 4H), 2.40 ppm (s,
3H); 13C-NMR (300 MHz, CDCl3) d 147.56 (1C), 145.08
(1C), 140.93 (1C), 136.29 (1C), 132.98 (2C), 132.83 (2C),
129.64 (2C), 128.93 (4C), 128.55 (2C), 128.06 (4C),
123.21 (2C), 113.22 (2C), 54.15 (2C), 21.72 ppm (1C); IR
(thin film) cm-1 3048, 2963, 1601, 1508, 1489, 1443;
MS (ESI, positive mode) m/z [M ? H]? 512.08485
(C27H24Cl2NO3S requires 512.07757); Anal. Calcd for
C27H23Cl2NO3S: C 63.28, H 4.52, Cl 13.84, N 2.73, S 6.26,
found: C 62.19, H 4.92, Cl 13.56, N 2.51, S 6.88.
Toluene-4-sulfonic acid 4-[bis-(4-nitro-benzyl)-amino]-
phenyl ester (8f)
Pale-green oil (61%): Rf = 0.61 (CHCl3); 1H-NMR
(300 MHz, CDCl3) d 8.18 (d, J = 8.7 Hz, 4H), 7.68 (d,
J = 8.3 Hz, 2H), 7.38 (d, J = 8.62 Hz, 4H), 7.28 (d,
J = 8.05 Hz, 2H), 6.76 (dd, J = 9.15, 2.17 Hz, 2H), 6.53
(dd, J = 9.18, 2.13 Hz, 2H), 4.68 (s, 4H), 2.42 ppm (s,
3H); 13C-NMR (300 MHz, CDCl3) d 147.42 (1C), 146.73
(1C), 145.30 (2C), 141.50 (2C), 132.62 (2C), 129.74 (2C),
128.51 (2C), 127.38 (4C), 124.21 (4C), 123.57 (2C),
113.32 (2C), 54.68 (2C), 21.79 ppm (1C); IR (thin film)
cm-1 3055, 2963, 1597, 1512, 1478; MS (ESI, positive
mode) m/z [M ? Na]? 556.11513 (C27H23N3NaO7S
requires 556.55354).
Toluene-4-sulfonic acid 4-[bis-(3-methyl-benzyl)-amino]-
phenyl ester (8j)
Toluene-4-sulfonic acid 4-[bis-(3-trifluoromethyl-benzyl)-
amino]-phenyl ester (8g)
Off-white powder (6.4%): Rf = 0.68 (CHCl3); mp.
90–91°C; 1H-NMR (300 MHz, CDCl3) d 7.68 (d, J =
8.28 Hz, 2H), 7.18–7.32 (m, 6H), 7.08 (d, J = 7.52 Hz,
2H), 6.95 (d, J = 6.29 Hz, 4H), 6.70 (dd, J = 9.17,
2.11 Hz, 2H), 6.52 (dd, J = 9.2, 2.16 Hz, 2H), 4.52 (s,
4H), 2.42 (s, 3H), 2.3 ppm (s, 6H); 13C-NMR (300 MHz,
CDCl3) d 148.12 (1C), 145.01 (1C), 140.27 (1C), 138.46
(2C), 138.07(2C), 132.77 (1C), 129.64 (1C), 128.66 (3C),
128.60 (2C), 127.84 (2C), 127.20 (2C), 123.59 (2C),
123.03 (2C), 112.59 (2C), 54.44 (2C), 21.77 (1C),
21.59 ppm (2C); IR (thin film) cm-1 3047, 2963, 1605,
1512, 1447; MS (ESI, positive mode) m/z [M ? H]?
472.19409 (C29H30NO3S requires 472.18681); Anal. Calcd
for C29H29NO3S: C 73.86, H 6.20, N 2.97, S 6.80, found: C
73.73, H 6.60, N 2.04, S 6.88.
Off-white oil (45.6%): Rf = 0.74 (CHCl3); 1H-NMR
(300 MHz, CDCl3) d 7.65 (d, J = 8.03 Hz, 2H), 7.5 (d,
J = 7.61 Hz, 2H), 7.32-7.45 (m, 7H), 7.25 (d, J =
8.09 Hz, 2H), 6.75 (dd, J = 9.13, 2.15 Hz, 2H), 6.53 (dd,
J = 9.18, 2.16 Hz, 2H), 4.65 (s, 4H), 2.42 ppm (s, 3H);
13C-NMR (300 MHz, CDCl3) d 147.36 (1C), 145.22 (1C),
141.17 (1C), 138.85 (2C), 132.40 (1C), 131.42 (1C),
130.00 (2C), 129.66 (2C), 129.37 (2C), 128.61 (2C),
124.32 (1C), 124.27 (2C), 124.22 (2C), 124.17 (1C),
123.36 (1C), 123.23 (1C), 122.23 (1C), 113.20 (2C), 54.50
(2C), 21.74 ppm (1C); IR (thin film) cm-1 3051, 2963,
1601, 1512, 1451; MS (ESI, positive mode) m/z [M ? H]?
580.13669 (C29H24F6NO3S requires 580.13028).
Toluene-4-sulfonic acid 4-[bis-(3-chloro-benzyl)-amino]-
phenyl ester (8h)
Toluene-4-sulfonic acid 4-[bis-(3-bromo-benzyl)-amino]-
phenyl ester (8k)
White oil (14.6%): Rf = 0.68 (CHCl3); 1H-NMR
(300 MHz, CDCl3) d 7.68 (d, J = 8.33 Hz, 2H), 7.2-7.32
(m, 6H), 7.15 (s, 2H), 7.05 (m, 2H), 6.75 (dd, J = 9.21,
2.28 Hz, 2H), 6.51 (dd, J = 9.23, 2.29 Hz, 2H), 4.55 (s,
4H), 2.43 ppm (s, 3 H); 13C-NMR (300 MHz, CDCl3) d
147.37 (1C), 145.13 (1C), 140.98 (1C), 140.05 (2C),
134.79 (2C), 132.60 (1C), 130.15 (2C), 129.67 (2C),
128.60 (2C), 127.49 (2C), 126.65 (2C), 124.78 (2C),
123.29 (2C), 113.04 (2C), 54.28 (2C), 21.75 ppm (1C); IR
(thin film) cm-1 3055, 2963, 1597, 1574, 1508, 1431; MS
Off-white oil (11%): Rf = 0.69 (CHCl3); 1H-NMR
(300 MHz, CDCl3) d 7.68 (d, J = 8.3 Hz, 2H), 7.38 (d,
J = 7.9 Hz, 2H), 7.38 (dd, J = 14.44, 8.76 Hz, 4H), 7.18
(d, J = 7.77 Hz, 2H), 7.08 (d, J = 7.83 Hz, 2H), 6.74 (d,
J = 9.16 Hz, 2H), 6.50 (d, J = 9.20 Hz, 2H), 4.54 (s, 4H),
2.42 ppm (s, 3H); 13C-NMR (300 MHz, CDCl3) d 147.02
(1C), 146.53 (1C), 145.42 (2C), 140.30 (2C), 130.43 (2C),
129.68 (2C), 129.56 (2C), 128.61 (4C), 125.22 (4C),
123.32 (2C), 113.00 (2C), 54.19 (2C), 29.75 ppm (1C); IR
(thin film) cm-1 3048, 2963, 1597, 1508, 1465; MS (ESI,
123

Med Chem Res (2012) 21:3669–3680
3677
positive mode) m/z [M ? Na]? 624.96507 (C27H23Br2
NNaO3S requires 624.35046).
CETP inhibition by 0.1% DMSO. CETP was not affected
by DMSO. The increase in fluorescence intensity with
CETP (rabitt serum) is usually 1.5- to 2-fold over 0.1%
DMSO. Negative controls lacking rabbit serum were used
as background. All measurements were conducted in
duplicates.
Toluene-4-sulfonic acid 4-[bis-(3-nitro-benzyl)-amino]-
phenyl ester (8l)
Yellow powder (17.6%): Rf = 0.64 (CHCl3); mp.
1
133–134°C; H-NMR (300 MHz, CDCl3) d 8.13 (m, 2H),
8.02 (s, 2H), 7.65 (d, J = 8.3 Hz, 2H), 7.5 (m, 4H), 7.25 (d,
J = 8.14 Hz, 2H), 6.78 (dd, J = 9.23, 2.12 Hz, 2H), 6.5A3
(dd, J = 9.2, 2.13 Hz, 2H), 4.75 (s, 4H), 2.42 ppm (s, 3H);
13C-NMR (300 MHz, CDCl3) d 148.77 (1C), 146.77 (1C),
145.28 (1C), 145.20 (1C), 141.60 (1C), 141.58 (1C),
140.02 (2C), 132.75 (2C), 132.41 (1C), 129.99 (2C),
129.72 (2C), 128.57 (2C), 123.59 (2C), 122.60 (2C),
121.58 (2C), 113.50 (2C), 54.57 (2C), 21.75 ppm (1C); IR
(thin film) cm-1 3074, 2928, 1603, 1530, 1506, 1350; MS
(ESI, positive mode) m/z [M ? H]? 534.13044 (C27H24
N3O7S requires 534.12567); Anal. Calcd for C27H23N3O7S:
C 60.78, H 4.34, N 7.88, S 6.01, found: C 60.33, H 4.56, N
7.76, S 6.39.
Table 1 The synthesized N-(4-benzyloxyphenyl)-4-methyl-benzene-
sulfonamide and N-(4-benzyloxyphenyl)-N-(4-methylbenzenesulfo-
nyl)-4-methylbenzenesulfonamide derivatives with their fit values
against Hypo4/8 and in vitro CETP bioactivities
Compound Fit values against In vitro % inhibition In vitro
of CETP at 10 lM
Hypo4/8
IC50 (lM)
6a
6b
6c
6d
6e
6f
6g
6h
6i
9.1
8.9
8.6
0.0
9.2
8.7
9.4
9.0
9.2
8.8
9.1
9.5
9.9 1.3
10.2 0.7
0.0 0.2
–
–
–
15.5 1.1
29.6 0.2
23.0 1.4
22.8 2.7
39.0 2.6
42.6 0.2
37.5 2.8
66.9 1.5
65.3 2.8
–
–
–
CETP inhibition assay
–
11.1 (0.99)a
10.5 (0.99)a
13.2 (0.99)a
3.4 (0.99)a
3.9 (0.99)a
CETP inhibitory bioactivities were assayed by fluorescent-
CE transfer employing commercially available kit (Bio-
Vision, Linda Vista Avenue, USA). The assay kit is based
on donor molecule containing fluorescent self-quenched
neutral lipid that is transferred to an acceptor molecule in
the presence of CETP (from rabbit serum). CETP-mediated
transfer of the fluorescent neutral lipid to the acceptor
molecule results in increase in fluorescence. Inhibition of
CETP will prevent lipid transfer and therefore decrease
fluorescence intensity.
6j
6k
6l
a
This value represents the correlation coefficient of the corre-
sponding dose–response line at three concentrations
Table 2 The synthesized 4-benzylaminophenyl toluene-4-sulfonic
acid ester and 4-(N,N)-[bis-(benzylaminophenyl)]-toluene-4-sulfonic
acid ester derivatives with their fit values against Hypo4/8 and in vitro
CETP bioactivities
The assay procedure can be described briefly as follows.
An aliquot of 1.5 ll of rabbit serum (CETP) was added to
160 ll of testing sample (12.8 lM). Then, 20 ll of the
master mix, provided in the assay kit (5 ll donor molecule,
5 ll acceptor molecule and 10 ll assay buffer), was added,
mixed well, and the volume was made up to 203 ll with
the provided assay buffer. The assay is carried out using a
black 96-well plate with led. After incubation at 37°C for
1 h, fluorescence intensity (Excitation k: 465 nm; Emission
k: 535 nm) was read in a FLX800TBI Microplate Fluo-
rimeter (BioTek Instruments, Winooski, USA).
Compound Fit values against In vitro % inhibition In vitro
Hypo4/8
of CETP at 10 lM
IC50 (lM)
8a
8b
8c
8d
8e
8f
8g
8h
8i
7.9
8.3
4.3
8.9
8.5
0.0
8.7
8.3
8.9
8.1
8.4
4.6
31.3 0.4
16.1 1.3
29.9 2.9
17.5 1.1
22.3 0.6
9.3 0.5
30.1 (0.99)a
–
–
–
–
–
24.7 1.0
31.9 1.4
24.9 2.9
29.0 2.5
23.1 1.2
31.4 0.5
–
The tested compounds were initially dissolved in DMSO
to yield 10 mM stock solutions and subsequently diluted to
the required concentrations using distilled deionized water
(12.8 lM). The final concentration of DMSO was adjusted
to 0.1%. The percentage of residual activity of CETP was
determined for each compound by comparing the activity
of CETP in the presence and absence of the tested com-
pound. Positive controls were tested to assess the degree of
28.5 (0.99)a
–
8j
8k
8l
–
–
29.7 (0.99)a
a
This value represents the correlation coefficient of the corre-
sponding dose–response line at three concentrations
123

3678
Med Chem Res (2012) 21:3669–3680
Results and discussion
Chemistry
sodium hydroxide to prepare the final N-(4-benzyloxy-
phenyl)-4-methyl-benzenesulfonamides (6a–6g) and N-(4-
benzyloxyphenyl)-N-(4-methylbenzenesulfonyl)-4-methyl-
benzenesulfonamides (6h–6l). On the other hand, these
intermediates were reacted with substituted benzyl bro-
mides in DMF at room temperature to prepare N-(4-ben-
zylaminophenyl)-toluene-4-sulfonic acid esters (8a–8c)
and 4-(N,N)-[bis-(benzylaminophenyl)]-toluene-4-sulfonic
acid esters (8d–8l). The highest yield was obtained upon
reacting N-(4-hydroxy-phenyl)-4-methyl-benzenesulfona-
mide with 4-bromo-benzylbromide to give 6b in 63%
yield.
In the current work, the intermediates N-(4-hydroxyphenyl)-
4-methylbenzenesulfonamide 4a, N-(4-hydroxyphenyl)-N-
(4-methylbenzenesulfonyl)-4-methylbenzenesulfonamide
4b, and 4-aminophenyl-4-toluene-sulfonic acid ester 7 were
prepared from the reaction of tosyl chloride 2 with p-ami-
nophenol 3 in dichloromethane at room temperature and in
the presence of triethylamine, as illustrated in Schemes 1
and 2.
Afterward, the resulting intermediates (4a, 4b, or 7)
were reacted with different substituted benzyl bromides
5a–5k in DMF at room temperature and in the presence of
Scheme 1 shows the new benzenesulfonamide deriva-
tives (6a–6l), while Scheme 2 shows sulfonic acid ester
derivatives (8a–8l).
O
O
S
O
N
S
O
O
Cl
(f)
(g)
(a)
O
O
O
S
O
N
S
O
O
S
N
O
O
S
O
O
F3C
(b)
(c)
(h)
(i)
Cl
O
O
N
O
S
O
O
S
S
N
O
O
S
O
O
O
(k)
OCH3
(d)
(e)
(j)
Fig. 2 The mapping of Hypo4/8 against the synthesized compounds
6h (IC50 = 11.1 lM), 6i (IC50 = 10.5 lM), 6j (IC50 = 13.2 lM), 6k
(IC50 = 3.4 lM), and 6l (IC50 = 3.9 lM): a Hypo4/8, b structure of
6h, c Hypo4/8 mapped against 6h, d structure of 6i, e Hypo4/8
mapped against 6i, f structure of 6j, g Hypo4/8 mapped against 6j,
h structure of 6k, i Hypo4/8 mapped against 6k, j structure of 6l and
k Hypo4/8 mapped against 6l
123

Med Chem Res (2012) 21:3669–3680
Biological evaluation
3679
(4-methylbenzenesulfonyl)-4-methylbenzenesulfonamides,
N-(4-benzylaminophenyl)-toluene-4-sulfonic acid esters,
and 4-(N,N)-[bis-(benzylaminophenyl)]-toluene-4-sulfonic
acid esters as potential CETP inhibitors. Future optimization
of the hydrophobic characters together with the substituent’s
electronic properties can lead to the discovery of more potent
derivatives.
The results of CETP inhibition assay, presented in Tables 1
and 2, demonstrate that compound 6k exhibit appreciable
activity against CETP with an IC50 value of 3.4 lM.
Although our newly synthesized compounds are of lower
potency than some published CETP inhibitors, these
derivatives are characterized by their novel scaffold that
can serve as a promising leads for further optimization.
Tables 1 and 2 show the fit values of the synthesized
compounds against Hypo4/8.
Acknowledgments The authors are grateful to the Scientific
Research and Postgraduate Deanship at Al-Zaytoonah University of
Jordan for sponsoring this project.
Figure 2 shows how Hypo4/8 maps the most active
synthesized compounds 6h–6l. The hydrogen bond accep-
tor feature of Hypo4/8 fits either the sulfonamide moiety or
the benzyloxy oxygen, while ring aromatic feature maps
one of the aromatic rings in the structure. Furthermore, the
three hydrophobic features of Hypo4/8 fit different
substituted aromatic rings, i.e., substituted with methyl,
trifluoromethyl, chloro, or methoxy.
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