Design, synthesis, and biological evaluation of benzylamino-methanone based cholesteryl ester transfer protein inhibitors

Article abstract of DOI:10.3390/molecules15085721

Cholesteryl ester transfer protein (CETP) is a glycoprotein involved in transporting lipoprotein particles and neutral lipids between high-density lipoprotein (HDL) and low density lipoproteins (LDL) and therefore its a proper target for treating dyslipidemia and related disorders. Guided by our previosuly-reported pharmacophore and QSAR models for CETP inhibition, we synthesized and bioassayed a series of benzylamino-methanones. The most potent illustrated 30% CETP inhibition at 10 μM.

Full text of DOI:10.3390/molecules15085721

Molecules 2010, 15, 5721-5733; doi:10.3390/molecules15085721
OPEN ACCESS
molecules
ISSN 1420-3049
www.mdpi.com/journal/molecules
Article
Design, Synthesis, and Biological Evaluation of Benzylamino-
Methanone Based Cholesteryl Ester Transfer Protein Inhibitors
Ghassan Abu Sheikha, Reema Abu Khalaf *, Areej Melhem and Ghadeer Albadawi
Department of Pharmaceutical Sciences, Faculty of Pharmacy, Al-Zaytoonah Private University of
Jordan, Amman, Jordan; E-mail: pharmacy@alzaytoonah.edu.jo
* Author to whom correspondence should be addressed; E-Mail:
reema.abukhalaf@alzaytoonah.edu.jo or rima_abu_khalaf@yahoo.com; Tel.: +962 6 4291511 ext.
239; Fax: +962 6 4291511.
Received: 18 June 2010; in revised form: 10 August 2010 / Accepted: 13 August 2010 /
Published: 19 August 2010
Abstract: Cholesteryl ester transfer protein (CETP) is a glycoprotein involved in
transporting lipoprotein particles and neutral lipids between high-density lipoprotein
(HDL) and low density lipoproteins (LDL) and therefore its a proper target for treating
dyslipidemia and related disorders. Guided by our previosuly-reported pharmacophore and
QSAR models for CETP inhibition, we synthesized and bioassayed a series of
benzylamino-methanones. The most potent illustrated 30% CETP inhibition at 10 μM.
Keywords: CETP inhibitors; high-density lipoprotein; pharmacophore modeling;
quantitative structure-activity relationship; benzylamino-methanones
Introduction
Atherosclerosis is the main cause for arterial dysfunction that limits blood flow to vessels in the
peripheral vasculature and is finally marked as coronary artery disease (CAD) [1]. A number of
epidemiological studies have established an inverse relationship between serum high-density
lipoprotein (HDL) cholesterol levels and the incidence of ischemic heart disease [2]. HDL removes
excess cholesterol from peripheral tissues to the liver for biliary elimination [3]. CETP, a 476-residue
glycoprotein, is engaged in interchanging lipoprotein particles and neutral lipids, including cholesteryl
esters, phospholipids and triglycerides between HDL and low density lipoproteins (LDL). CETP, as

Molecules 2010, 15
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revealed by X-ray crystallography (PDB code: 2OBD, resolution 2.2 Å), has a huge highly lipophilic
binding site capable of binding up to four lipid molecules [4]. In human plasma, CETP plays a
probably proatherogenic task by moving cholesteryl esters from HDL to very-low density lipoprotein
(VLDL) and LDL particles, thereby lowering atheroprotective HDL cholesterol and raising
proatherogenic VLDL and LDL cholesterols. Obviously, the risk of CAD is proportional to the plasma
levels of CETP [5]. 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 µg/mL) [6].
Indication exists that the outcomes of CETP activity may depend on the metabolic setting, particularly
on triglyceride levels. Therefore, pharmacological CETP inhibition may reduce the risk of CAD in
humans, but only in those with high triglyceride levels [5].
The inaccessibility of a reasonable high resolution crystallographic structure 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) [7-11]. Earlier, we
have developed ligand-based three-dimensional (3D) pharmacophores integrated within a self-
consistent 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 [12]. Additionally, we recently
described the synthesis of several benzylidene-amino methanones, (including 1, Figure 1), as
representatives of a new series of simple CETP inhibitors [12]. Herein we describe our efforts to
optimize the activity of this series of compounds through reduction of the imine double bond to the
corresponding amine analogues (compounds 19–30, Scheme 2).
Figure 1. The structure of benzylidene-amino methanone derivative 1.
OCH O
3
CF
3
H CO
3
N
The new compounds are expected to have better anti-CETP bioactivities compared to the previously
synthesized rigid benzylidene-amino methanones due to the enhanced flexibility of the amino
analogues, which should allow better fit values against the pharmacophores i.e. to fit both QSAR-
emerged pharmacophores instead of mapping just one of them. Furthermore, amino-derivatives are
more stable than imines in aqueous conditions [13]. On the other hand, reduction of imines into amines
can alter their physicochemical properties such as lipophilicity and basicity of the nitrogen, whereby
the amines are more water soluble and more basic than their imine analogues. This property
modification can influence the anti-CETP activity of the synthesized compounds. The synthesis
commenced by preparing different substituted imine intermediates 8–11 (Scheme 1). Imines are

Molecules 2010, 15
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typically formed by reversible acid-catalyzed condensation of amines and aldehydes with extrusion of
water through either azeotropic distillation or by employing chemical drying agents [14].
Scheme 1. Synthesis of 4-aminobenzoic acid derivatives 12–15.
COOMe
COOMe
+
COOH
R
b
a
N
8 R = 3-OCH3
9 R = 4-t-Bu
10 R = 3-CF3
11 R = 4-CF3
NH
3
NH
2
H
O
2
2
4 R = 3-OCH3
5 R = 4-t-Bu
6 R = 3-CF3
7 R = 4-CF3
R
c, d
COOH
NH
12 R = 3-OCH3
13 R = 4-t-Bu
14 R = 3-CF3
15 R = 4-CF3
R
Reagents and conditions: (a) Methanol, SOCl2; (b) DMF, 90–100 °C, overnight; (c) NaBH4,
methanol, overnight; (d) NaOH, 100 °C, overnight.
Subsequently, the imine intermediates were reduced to their corresponding amines 12–15 (Scheme
1) which were then used to prepare the final benzylamino-methanones, in modest to reasonable yields,
via Friedel–Crafts acylation of the substituted benzene derivatives 16–18 in the presence of
polyphosphoric acid (PPA), as reported in Scheme 2 [15]. The structures proposed for compounds 19–
1
30 were confirmed via elemental analyses, IR and H- and 13C-NMR spectroscopy (see the
Experimental section).

Molecules 2010, 15
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Scheme 2. Synthesis of benzylamino-methanones 19–30.
Y
COOH
O
X
X
a, b
NH
+
NH
Y
16 X = CH3, Y = H
17 X = OCH3, Y = H
18 X, Y = OCH3
R
12 R = 3-OCH3
13 R = 4-t-Bu
14 R = 3-CF3
15 R = 4-CF3
R
19 X = CH3, Y = H, R = 3-OCH3
20 X = CH3, Y = H, R = 4-t-Bu
21 X = CH3, Y = H, R = 3-CF3
22 X = CH3, Y = H, R = 4-CF3
23 X = OCH3, Y = H, R = 3-OCH3
24 X = OCH3, Y = H, R = 4-t-Bu
25 X = OCH3, Y = H, R = 3-CF3
26 X = OCH3, Y = H, R = 4-CF3
27 X = OCH3, Y = OCH3, R = 3-OCH3
28 X = OCH3, Y = OCH3, R = 4-t-Bu
29 X = OCH3, Y = OCH3, R = 3-CF3
30 X = OCH3, Y = OCH3, R = 4-CF3
Reagents and conditions: (a) PPA, cyclohexane, 90–100 °C, overnight; (b) NH3, 0 °C.
Results and Discussion
In the current work, the imine intermediates were prepared from reaction of trifluoro-m-
tolualdehyde, trifluoro-p-tolualdehyde, 3-methoxybenzaldehyde and 4-tert-butylbenzaldehyde with the
methyl ester of 4- aminobenzoic acid (3) as illustrated in Scheme 1 [16]. The best yield was obtained
when 3, dissolved in DMF, reacted with trifluoro-p-tolualdehyde to yield 15 (92.2%). Afterward, the
imine intermediates were reduced to their corresponding amines, which were then used to prepare the
final benzylamino-methanones. The best yield was obtained upon reacting 4-aminobenzoic acid
derivative 15 with toluene to yield 22 (96%). Scheme 2 shows the new benzylamino-methanone
derivatives 19–30, while Figure 2 shows how Hypo4/8 and Hypo12/4 map compounds 26 and 27.

Molecules 2010, 15
Figure 2. The binding pharmacophore hypotheses emerged in the optimal QSAR model
5725
(Hydrogen bond acceptor as green vectored spheres, hydrophobic features as blue spheres,
ring aromatic as orange vectored spheres, Hydrogen bond donor as violet vectored
spheres): (A) Hypo4/8 mapping 26, (B) Hypo4/8 mapping 27, (C) Hypo12/4 mapping 26,
(D) Hypo12/4 mapping 27, (E) and (F) The chemical structures of 26 and 27, respectively.
(A)
(B)
(C)
(E)
(D)
O
OCH3
O
OCH3
H3CO
N
H
H3CO
N
H
CF3
(F)
As can be noticed from Table 1, the benzylamino-methanone compounds have enhanced flexibility
reflected by their fit values against Hypo12/4 in comparison to their benzylidene-amino methanones
which do not fit Hypo12/4.
In this work, we intended to make the compounds more flexible in order to enhance their
pharmacophore mapping in an attempt to increase their anti-CETP bioactivities, but it seems that the
entropic cost contribution overcomes the enhanced flexibility contribution to the bioactivity.
Therefore, pharmacophore fitness is just one of many factors that can influence the activity.
The results of anti-CETP activity tests, presented in Table 1, demonstrate that compound 26
exhibited appreciable activity against CETP. Although our newly synthesized benzylamino-

Molecules 2010, 15
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methanones are of lower potency than some published CETP inhibitors, these derivatives are
characterized by their novel scaffold that could be a promising lead for further optimization.
The new compounds 19–30 were synthesized to explore how the CETP inhibitory activity is
affected by the expansion of the structure, i.e. meta or para substitution, and the electronic properties
of the substituent, i.e. electron donating or with-drawing group.
Table 1. The synthesized benzylamino-methanones with their fit values, corresponding
QSAR estimates and in vitro bioactivities.
QSAR-based
estimates
Fit values against
In vitro %
inhibition of
CETP at 10 μM
In vitro
IC50 (μM)
Compound
Hypo4/8 Hypo12/4
IC50
(μM)
Log(1/IC50)
19
20
7.9
8.3
2.2
0.8
-0.936
8.6
16.4 ± 3.0
21.6 ± 0.8
—
60.3
(0.99)a
—
-1.25
-1.282
-0.86
17.8
19.1
7.2
21
22
23
6.5
7.6
8.6
1
1.3
2
16.7 ± 0.6
12.6 ± 2.6
20.0 ± 3.2
—
66.1
(0.99)a
51.3
(1.00)a
—
25.1
(0.99)a
36.3
(0.99)a
61.7
(0.99)a
—
-1.111
12.9
24
8.3
1.8
23.3 ± 2.3
-1.289
-1.051
19.5
11.2
25
26
8.2
7.8
0.3
2.3
9.8 ± 0.4
29.9 ± 2.8
-0.754
-0.954
5.7
9
27
28
29
9.4
9.4
3.1
2.8
24.3 ± 2.7
21.3 ± 2.5
-0.823
-1.314
-1.089
6.7
20.6
12.3
8.5
8.8
1.4
2.1
19.5 ± 0.6
19.8 ± 2.9
30
—
a
This value represents the correlation coefficient of the corresponding dose-response line at three
concentrations.
As a general trend, the inhibitory activity of compound 26, that is para-substituted (R) with a
trifluoromethyl electron withdrawing group and fully extended, decreases with the trifluoromethyl
group on the meta position as in compound 25. Furthermore, meta and para substitution (R) with
electron donating groups such as t-Bu in compounds 20 and 24, and methoxy in compound 23 seems
to conserve the anti-CETP activity. Moreover, mono- (X) or di-substitution (X and Y) of the aromatic
ring, as in compounds 24 and 28, respectively, appears not to have a considerable effect on the
inhibitory activity.
Compounds 19–30 were tested against CETP at 10 μM concentrations and exhibited anti-CETP
activity ranging from 9.8 to 29.9 %. Compound 26 displayed the best activity as reported in Table 1.
Furthermore, in vitro IC50 values were determined for the most active compounds and approximately 3
to 9 fold differences were observed between QSAR-based IC50 estimates and the experimental
IC50 values.

Molecules 2010, 15
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Conclusions
In conclusion, we have successfully achieved synthetic exploration of a new series of aromatic
amines as CETP inhibitors. They showed comparable activities to their benzylidene-amino
methanones analogues [12] which reveals that flexibility of these amines was not enough to influence
their antiCETP activity. We are currently in the process of preparing new compounds of better
bioactivity profiles.
Experimental
General methods
Melting points were measured using Gallenkampf melting point apparatus and are uncorrected.
1H- NMR 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
IRAffinity-1 spectrophotometer. The samples were dissolved in CHCl3 and analysed 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 the
corresponding companies (Sigma-Aldrich, Riedel-de Haen, Fluka, BDH Laboratory Supplies and
Promega Corporation) and were used in the experimentation without further purification.
General procedure for the synthesis of 4-aminobenzoic acid derivatives 12–15
4-Aminobenzoic acid (2, 1.37 g, 10 mmol) was dissolved in methanol (100 mL), and then thionyl
chloride (200 mmol) was added at 0 °C. The mixture was stirred at room temperature for 20–30
minutes, followed by refluxing at 65–70 °C overnight. Evaporation of the solvent was carried out,
followed by neutralization using K2CO3 and extraction with CH2Cl2 (3 × 20 mL). The combined
extracts were dried on anhydrous Na2SO4 and filtrated to give 4-amino-benzoic acid methyl ester (3,
96%). Subsequently, 3 (1.52 g, 10 mmol) was disolved in DMF (10 mL), then an aldehyde (4–7, 25
mmol) was added. The mixture was heated between 100–150 °C overnight. After removing DMF,
methanol (15 mL) was added to the reaction mixture, followed by gradual addition of NaBH4 (4
equivalents) and stirring at room temperature overnight. The residue, after evaporation of the solvent,
was purified by column chromatography eluting with cyclohexane/EtOAc (90:10). Next,
desterification was carried out by refluxing with 1M NaOH (2.6 equivalents) at 100 °C overnight.
Then, the reaction mixture was neutralized with HCl and extracted with CHCl3 (3 × 20 mL). The
combined extracts were dried on anhydrous Na2SO4 and filtered.
4-(3-Methoxybenzylamino)-benzoic acid (12). Evaporation of the solvent gave 12 as an off-white
powder (88%); mp. 160–161 °C; 1H-NMR (300 MHz, CDCl3) δ 3.68 (s, 3H), 4.26 (s, 2H), 4.72 (br s,
1H), 6.55 (d, J = 8.8 Hz, 2H), 6.77 (dd, J = 8.1, 1.4 Hz, 1H), 6.86–6.89 (m, 2H), 7.21 (t, J = 8.1 Hz,
13
1H), 7.61 (d, J = 8.8 Hz, 2H), 12.03 (br s, 1H); C-NMR (300 MHz, CDCl3) δ 46.3 (1C), 55.4 (1C),
111.7 (1C), 112.5 (1C), 113.3 (1C), 117.6 (1C), 119.8 (1C), 130.0 (2C), 131.6 (2C), 141.7 (1C), 152.9

Molecules 2010, 15
5728
(1C), 159.9 (1C), 168.0 (1C); IR (thin film) cm-1 3437, 3059, 2940, 1655, 1597, 1489, 1427,
1285, 1177.
4-(4-tert-Butylbenzylamino)-benzoic acid (13). Evaporation of the solvent gave 13 as an off-white
powder (83%); mp. 210–211 °C; 1H-NMR (300 MHz, CDCl3) δ 1.27 (s, 9H), 4.36 (s, 2H), 4.80 (br s,
1H), 6.60 (d, J = 8.7 Hz, 2H), 7.26–7.36 (m, 4H), 7.94 (d, J = 8.7 Hz, 2H), 11.87 (br s, 1H); 13C-NMR
(300 MHz, CDCl3) δ 31.4 (3C), 34.6 (1C), 47.4 (1C), 111.6 (2C), 117.6 (1C), 125.8 (2C), 127.4 (2C),
132.4 (2C), 135.2 (1C), 150.7 (1C), 152.5 (1C), 172.4 (1C); IR (thin film) cm-1 3426, 3017, 2963,
1670, 1605, 1524, 1478, 1420, 1292.
4-(3-Trifluoromethylbenzylamino)-benzoic acid (14). Evaporation of the solvent gave 14 as an off-
1
white powder (77%); mp. 168–169 °C; H-NMR (300 MHz, CDCl3) δ 4.41 (s, 2H), 4.77 (br s, 1H),
13
6.57 (d, J = 8.6 Hz, 2H), 7.53–7.66 (m, 6H), 11.93 (br s, 1H); C-NMR (300 MHz, CDCl3) δ 45.7
(1C), 111.7 (2C), 118.0 (1C), 124.0 (1C), 124.1 (1C), 127.6 (1C), 129.9 (1C), 131.6 (2C), 131.8 (2C),
141.7 (1C), 152.6 (1C), 167.9 (1C); IR (thin film) cm-1 3456, 3062, 2920, 1674, 1605, 1516, 1481,
1424, 1316, 1107.
4-(4-Trifluoromethylbenzylamino)-benzoic acid (15). Evaporation of the solvent gave 15 as a pale
1
yellow powder (93%); mp. 189–190 °C; H-NMR (300 MHz, CDCl3) δ 4.41 (s, 2H), 4.79 (br s, 1H),
6.54 (d, J = 8.8 Hz, 2H), 7.51 (d, J = 8.1 Hz, 2H), 7.59–7.67 (m, 4H), 12.02 (br s, 1H); 13C-NMR (300
MHz, CDCl3) δ 45.8 (1C), 111.7 (2C), 118.0 (1C), 123.1 (1C), 125.8 (2C), 127.8 (1C), 128.2 (2C),
131.6 (2C), 145.2 (1C), 152.6 (1C), 167.9 (1C); IR (thin film) cm-1 3414, 3042, 2920, 1659, 1605,
1520, 1462, 1424, 1323, 1122.
General procedure for the synthesis of benzylamino-methanones 19–30
4-Aminobenzoic acid derivative 12–15 (2 mmol) was dissolved in cyclohexane (10 mL), and
polyphosphoric acid (6.5 g) was added. Then a benzene derivative 16–18 (20 mmol) was added. The
mixture was stirred carefully at 90–110 °C overnight and then poured on crushed ice. The solution was
carefully made alkaline with 25% ammonia and then extracted with CHCl3 (3 × 20 mL). The
combined extracts were dried on anhydrous Na2SO4 and filtered.
[4-(3-Methoxybenzylamino)phenyl]-p-tolyl-methanone (19). The residue, after evaporation of the
solvent, was purified by column chromatography eluting with cyclohexane/EtOAc (80:20) to give pure
19 as a yellow powder (22%); Rf = 0.52 (CHCl3-MeOH, 98:2); mp. 123–124 °C; 1H-NMR (300 MHz,
CDCl3) δ 2.32 (s, 3H), 3.78 (s, 3H), 4.37 (s, 2H), 4.65 (br s, 1H), 6.60 (d, J = 7.7 Hz, 2H), 6.80–6.94
13
(m, 2H), 7.22–7.28 (m, 4H), 7.62 (d, J = 7.2 Hz, 2H), 7.71 (d, J = 7.7 Hz, 2H); C-NMR (300 MHz,
CDCl3) δ 21.6 (1C), 47.7 (1C), 55.3 (1C), 111.6 (2C), 112.8 (1C), 113.1 (1C), 119.6 (1C), 126.9 (1C),
127.7 (2C), 129.9 (2C), 130.6 (1C), 132.9 (2C), 136.2 (1C), 140.0 (1C), 141.9 (1C), 151.7 (1C), 160.0
(1C), 195.1 (1C); IR (thin film) cm-1 3356, 3017, 2963, 1636, 1593, 1528, 1468, 1262, 1150; MS (ESI,
positive mode) m/z [M+H]+ 332.16451 (C22H22NO2 requires 332.15723); Anal. Calcd for C22H21NO2:
C 79.73, H 6.39, N 4.23, found: C 79.68, H 6.41, N 4.21.

Molecules 2010, 15
5729
[4-(4-tert-Butylbenzylamino)phenyl]-p-tolyl-methanone (20). The residue, after evaporation of the
solvent, was purified by column chromatography eluting with cyclohexane/EtOAc (85:15) to give pure
20 as a yellow powder (23%); Rf = 0.57 (CHCl3-MeOH, 98:2); mp. 140–141 °C; 1H-NMR (300 MHz,
CDCl3) δ 1.23 (s, 9H), 2.32 (s, 3H), 3.83 (s, 2H), 4.12 (br s, 1H), 6.65 (d, J = 8.6 Hz, 2H), 7.10 (d,
13
J = 7.8 Hz, 2H), 7.16–7.30 (m, 4H), 7.62–7.75 (m, 4H); C-NMR (300 MHz, CDCl3) δ 22.8 (1C),
29.5 (3C), 32.0 (1C), 39.1 (1C), 121.1 (1C), 123.7 (1C), 126.8 (1C), 128.3 (2C), 128.9 (2C), 129.0
(2C), 129.4 (2C), 130.2 (2C), 130.8 (1C), 132.9 (2C), 143.0 (1C), 150.7 (1C), 194.2 (1C); IR (thin
film) cm-1 3422, 3337, 3024, 2963, 1636, 1586, 1501, 1439, 1319; MS (ESI, positive mode) m/z
[M+H]+ 358.21016 (C25H28NO requires 358.20926); Anal. Calcd for C25H27NO: C 83.99, H 7.61, N
3.92, found: C 83.87, H 7.58, N 3.97.
p-Tolyl-[4-(3-trifluoromethylbenzylamino)phenyl]-methanone (21). The residue, after evaporation of
the solvent, was purified by column chromatography eluting with cyclohexane/EtOAc (80:20) to give
pure 21 as a reddish-orange oil (39%); Rf = 0.70 (CHCl3-MeOH, 98:2); 1H-NMR (300 MHz, CDCl3) δ
2.38 (s, 3H), 4.46 (s, 2H), 4.78 (br s, 1H), 6.58 (d, J = 5.2 Hz, 2H), 7.23 (d, J = 9.2 Hz, 2H), 7.43–7.74
13
(m, 8H); C-NMR (300 MHz, CDCl3) δ 21.5 (1C), 47.3 (1C), 111.6 (2C), 111.8 (1C), 113.7 (1C),
125.1 (1C), 127.6 (1C), 128.6 (2C), 129.2 (2C), 129.8 (1C), 132.9 (2C), 134.3 (1C), 136.2 (1C), 138.8
(1C), 141.9 (1C), 143.5 (1C), 151.4 (1C), 195.1 (1C); IR (thin film) cm-1 3356, 3024, 2924, 1651,
1593, 1527, 1439; MS (ESI, positive mode) m/z [M+H]+ 370.14133 (C22H19F3NO requires 370.13405).
p-Tolyl-[4-(4-trifluoromethylbenzylamino)phenyl]-methanone (22). The residue, after evaporation of
the solvent, was purified by column chromatography eluting with cyclohexane/EtOAc (80:20) to give
pure 22 as a dark-yellow powder (96%); Rf =0.49 (CHCl3-MeOH, 98:2); mp. 115–116 °C; 1H-NMR
(300 MHz, CDCl3) δ 2.35 (s, 3H), 4.49 (s, 2H), 4.82 (br s, 1H), 6.60 (dd, J = 9.0, 1.9 Hz, 2H), 7.27 (t,
J = 8.7 Hz, 2H), 7.42 (d, J = 6.2 Hz, 2H), 7.60 (dd, J = 9.0, 1.9 Hz, 2H), 7.66–7.78 (m, 4H); 13C-NMR
(300 MHz, CDCl3) δ 21.6 (1C), 47.3 (1C), 111.7 (2C), 127.0 (1C), 127.7 (1C), 128.8 (2C), 129.4 (2C),
130.2 (2C), 130.5 (2C), 130.6 (1C), 130.7 (2C), 131.1 (1C), 132.9 (1C), 142.0 (1C), 152.0 (1C), 195.1
(1C); IR (thin film) cm-1 3356, 3021, 2920, 1647, 1597, 1528, 1451; MS (ESI, positive mode) m/z
[M+H]+ 370.14133 (C22H19F3NO requires 370.13405); Anal. Calcd for C22H18F3NO: C 71.53, H 4.91,
N 3.79, found: C 71.48, H 4.95, N 3.67.
[4-(3-Methoxybenzylamino)phenyl]-(4-methoxyphenyl)-methanone (23). The residue, after evaporation
of the solvent, was purified by column chromatography eluting with CHCl3/MeOH (99:1) to give pure
23 as an orange oil (28%); Rf = 0.44 (CHCl3-MeOH, 98:2); 1H-NMR (300 MHz, CDCl3) δ 3.73 (s,
3H), 3.85 (s, 3H), 4.37 (s, 2H), 4.63 (br s, 1H), 6.59 (d, J = 8.7 Hz, 2H), 6.78–6.95 (m, 6H), 7.65–7.74
(m, 4H); 13C-NMR (300 MHz, CDCl3) δ 47.6 (1C), 55.3 (1C), 55.7 (1C), 111.3 (2C), 113.3 (2C),
120.3 (1C), 127.0 (1C), 129.0 (1C), 129.9 (1C), 130.8 (1C), 131.5 (1C), 132.0 (2C), 132.8 (2C), 140.1
(1C), 151.6 (1C), 160.0 (1C), 162.4 (1C), 194.3 (1C); IR (thin film) cm-1 3352, 3005, 2925, 1636,
1597, 1528, 1458, 1316, 1258, 1169; MS (ESI, positive mode) m/z [M+H]+ 348.14725 (C22H22NO3
requires 348.15214).

Molecules 2010, 15
5730
[4-(4-tert-Butylbenzylamino)phenyl]-(4-methoxyphenyl)-methanone (24). The residue, after
evaporation of the solvent, was purified by column chromatography eluting with cyclohexane/EtOAc
(80:20) to give pure 24 as a red oil (60%); Rf = 0.52 (CHCl3-MeOH, 98:2); 1H-NMR (300 MHz,
CDCl3) δ 1.26 (s, 9H), 3.84 (s, 3H), 3.89 (s, 2H), 4.10 (br s, 1H), 6.65 (d, J = 8.2 Hz, 1H), 6.93 (d,
J = 8.6 Hz, 2H), 7.11 (d, J = 8.2 Hz, 1H), 7.20 (d, J = 7.6 Hz, 2H), 7.29 (t, J = 7.6 Hz, 2H), 7.58–7.66
(m, 2H), 7.78 (d, J = 8.6 Hz, 2H); 13C-NMR (300 MHz, CDCl3) δ 31.4 (3C), 37.7 (1C), 38.2 (1C), 55.5
(1C), 123.7 (2C), 125.7 (1C), 126.7 (1C), 128.1 (1C), 128.4 (2C), 128.9 (2C), 131.1 (1C), 131.4 (2C),
133.9 (1C), 135.4 (1C), 138.6 (1C), 149.2 (1C), 149.6 (1C), 162.5 (1C), 194.5 (1C); IR (thin film) cm-1
3476, 3364, 3005, 2963, 1620, 1601, 1508, 1458, 1420, 1254; MS (ESI, positive mode) m/z [M+H]+
374.19873 (C25H28NO2 requires 374.20418).
(4-Methoxy-phenyl)-[4-(3-trifluoromethyl-benzylamino)-phenyl]-methanone (25). The residue, after
evaporation of the solvent, was purified by column chromatography eluting with cyclohexane/EtOAc
(80:20) to give pure 25 as a red oil (33%); Rf = 0.60 (CHCl3-MeOH, 98:2); 1H-NMR (300 MHz,
CDCl3) δ 3.82 (s, 3H), 4.46 (s, 2H), 4.73 (br s, 1H), 6.60 (dd, J = 6.9, 1.8 Hz, 2H), 6.93 (dd, J = 6.9,
13
1.8 Hz, 2H), 7.45–7.61 (m, 4H), 7.64–7.74 (m, 4H); C-NMR (300 MHz, CDCl3) δ 47.2 (1C), 55.5
(1C), 111.7 (2C), 113.4 (2C), 120.4 (1C), 123.9 (1C), 124.4 (1C), 127.5 (1C), 129.0 (1C), 129.3 (1C),
130.6 (1C), 130.9 (1C), 131.4 (2C), 132.0 (2C), 139.7 (1C), 151.2 (1C), 162.5 (1C), 194.3 (1C); IR
(thin film) cm-1 3348, 3032, 2932, 1636, 1601, 1528, 1455, 1327, 1169; MS (ESI, positive mode) m/z
[M+H]+ 386.13624 (C22H19F3NO2 requires 386.12896).
(4-Methoxyphenyl)-[4-(4-trifluoromethylbenzylamino)phenyl]-methanone (26). The residue, after
evaporation of the solvent, was purified by column chromatography eluting with CH2Cl2/EtOH (98:2)
to give pure 26 as a yellow oil (22%); Rf = 0.56 (CHCl3-MeOH, 98:2); 1H-NMR (300 MHz, CDCl3) δ
3.71 (s, 3H), 4.41 (s, 2H), 4.70 (br s, 1H), 6.50 (dd, J = 9.5, 4.0 Hz, 2H), 6.89 (dd, J = 9.3, 3.2 Hz, 2H),
7.20 (t, J = 5.0 Hz, 2H), 7.38 (dd, J = 9.3, 3.2 Hz, 2H), 7.52 (t, J = 5.0 Hz, 2H), 7.64 (dd, J = 9.5, 4.0
13
Hz, 2H); C-NMR (300 MHz, CDCl3) δ 47.4 (1C), 55.9 (1C), 111.6 (1C), 111.9 (2C), 113.6 (2C),
122.5 (1C), 126.0 (2C), 127.7 (2C), 129.2 (1C), 131.5 (2C), 132.9 (2C), 142.8 (1C), 151.3 (1C), 157.1
(1C), 162.7 (1C), 194.4 (1C); IR (thin film) cm-1 3345, 3035, 2963, 1636, 1597, 1531, 1462, 1323,
1165; MS (ESI, positive mode) m/z [M+H]+ 386.13624 (C22H19F3NO2 requires 386.12896).
(2,4-Dimethoxyphenyl)-[4-(3-methoxybenzylamino)phenyl]-methanone (27). The residue, after
evaporation of the solvent, was purified by column chromatography eluting with cyclohexane/EtOAc
(75:25) to give 27 pure as a pink powder (53%); Rf = 0.33 (CHCl3-MeOH, 98:2); mp. 126–127 °C; 1H-
NMR (300 MHz, CDCl3) δ 3.68 (s, 3H), 3.77 (s, 3H), 3.83 (s, 3H), 4.34 (s, 2H), 4.66 (br s, 1H), 6.48–
13
6.55 (m, 4H), 6.78–6.91 (m, 4H), 7.25 (t, J = 7.7 Hz, 1H), 7.99 (d, J = 8.7 Hz, 2H); C-NMR (300
MHz, CDCl3) δ 47.6 (1C), 55.3 (1C), 55.5 (1C), 55.7 (1C), 98.6 (1C), 104.2 (1C), 111.5 (2C), 112.8
(1C), 113.1 (1C), 119.6 (1C), 122.6 (1C), 127.7 (1C), 129.9 (1C), 131.1 (1C), 132.7 (2C), 140.1 (1C),
151.9 (1C), 158.8 (1C), 160.0 (1C), 162.3 (1C), 194.0 (1C); IR (thin film) cm-1 3348, 3005, 2936,
1636, 1597, 1489, 1458, 1316, 1262, 1161; MS (ESI, positive mode) m/z [M+H]+ 378.15691
(C23H24NO4 requires 378.16271); Anal. Calcd for C23H23NO4: C 73.19, H 6.14, N 3.71, found: C
73.25, H 6.21, N 3.68.

Molecules 2010, 15
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[4-(4-tert-Butylbenzylamino)phenyl]-(2,4-dimethoxyphenyl)-methanone (28). The residue, after
evaporation of the solvent, was purified by column chromatography eluting with cyclohexane/EtOAc
(80:20) to give pure 28 as a brown powder (82%); Rf = 0.45 (CHCl3-MeOH, 98:2); mp. 138–139 °C;
1H-NMR (300 MHz, CDCl3) δ 1.27 (s, 9H), 3.70 (s, 3H), 3.77 (s, 3H), 3.89 (s, 2H), 4.08 (br s, 1H),
6.50 (d, J = 8.6 Hz, 2H), 6.58 (d, J = 8.3 Hz, 2H), 7.08 (d, J = 8.6 Hz, 2H), 7.24–7.31 (m, 3H), 7.57 (d,
13
J = 8.3 Hz, 1H), 7.64 (d, J = 5.5 Hz, 1H); C-NMR (300 MHz, CDCl3) δ 31.4 (3C), 34.5 (1C), 37.6
(1C), 55.5 (1C), 55.6 (1C), 98.8 (1C), 104.5 (1C), 114.5 (1C), 122.5 (1C), 125.7 (2C), 128.0 (2C),
128.8 (1C), 131.1 (1C), 131.3 (2C), 133.8 (2C), 135.5 (1C), 149.6 (1C), 158.9 (1C), 162.5 (1C), 194.4
(1C); IR (thin film) cm-1 3480, 3364, 3005, 2963, 1623, 1602, 1505, 1462, 1410, 1312, 1277, 1211;
MS (ESI, positive mode) m/z [M+H]+ 404.22034 (C26H30NO3 requires 404.21474); Anal. Calcd for
C26H29NO3: C 77.39, H 7.24, N 3.47, found: C 77.42, H 7.30, N 3.51.
(2,4-Dimethoxyphenyl)-[4-(3-trifluoromethylbenzylamino)phenyl]-methanone (29). The residue, after
evaporation of the solvent, was purified by column chromatography eluting with cyclohexane/EtOAc
1
(75:25) to give pure 29 as an olive-green oil (32%); Rf = 0.58 (CHCl3-MeOH, 98:2); H-NMR (300
MHz, CDCl3) δ 3.71 (s, 3H), 3.82 (s, 3H), 4.43 (s, 2H), 4.83 (br s, 1H), 6.46–6.55 (m, 4H), 7.25 (dd,
J = 7.1, 2.0 Hz, 1H), 7.42–7.58 (m, 4H), 7.67 (d, J = 8.8 Hz, 2H); 13C-NMR (300 MHz, CDCl3) δ 47.2
(1C), 55.5 (1C), 55.7 (1C), 98.9 (1C), 104.2 (1C), 111.6 (2C), 122.5 (1C), 123.9 (1C), 124.0 (1C),
124.3 (1C), 124.4 (1C), 128.1 (1C), 129.3 (1C), 130.6 (1C), 131.1 (1C), 132.6 (2C), 139.7 (1C), 151.6
(1C), 158.9 (1C), 162.4 (1C), 194.1 (1C); IR (thin film) cm-1 3337, 3009, 2936, 1636, 1597, 1528,
1505, 1458, 1327, 1161; MS (ESI, positive mode) m/z [M+H]+ 416.14680 (C23H21F3NO3 requires
416.13953).
(2,4-Dimethoxyphenyl)-[4-(4-trifluoromethylbenzylamino)phenyl]-methanone (30). The residue, after
evaporation of the solvent, was purified by column chromatography eluting with cyclohexane/EtOAc
1
(75:25) to give pure 30 as a dark-brown oil (50%); Rf = 0.44 (CHCl3-MeOH, 98:2); H-NMR (300
MHz, CDCl3) δ 3.72 (s, 3H), 3.82 (s, 3H), 4.45 (s, 2H), 4.76 (br s, 1H), 6.48 (dd, J = 7.9, 1.9 Hz, 2H),
6.53 (d, J = 8.0 Hz, 2H), 7.26 (d, J = 2.9 Hz, 1H), 7.45 (d, J = 8.1 Hz, 2H), 7.57 (d, J = 8.1 Hz, 2H),
13
7.66 (dd, J = 7.9, 1.9 Hz, 2H); C-NMR (300 MHz, CDCl3) δ 47.1 (1C), 55.5 (1C), 55.7 (1C), 98.5
(1C), 98.9 (1C), 104.4 (1C), 111.6 (2C), 122.5 (1C), 125.6 (1C), 125.8 (2C), 127.4 (2C), 128.2 (1C),
129.6 (1C), 132.6 (2C), 142.7 (1C), 151.5 (1C), 158.9 (1C), 162.4 (1C), 194.0 (1C); IR (thin film) cm-1
3345, 3009, 2940, 1636, 1597, 1528, 1505, 1462, 1323, 1161; MS (ESI, positive mode) m/z [M+H]+
416.14680 (C23H21F3NO3 requires 416.13953).
CETP inhibition assay
CETP inhibitory bioactivities were assayed by fluorescent-CE transfer employing commercially
available kit (BioVision, Mountain View, CA, 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.

Molecules 2010, 15
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The assay procedure can be described briefly as follows: an aliquot of rabbit serum (1.5 µL) was
added to testing sample (160 µL). Then the master mix, provided in the assay kit (donor molecule,
acceptor molecule and assay buffer, 20 µL) was added, mixed well, and the volume was completed to
203 µL with the provided assay buffer. After incubation at 37 °C for 1 hour, fluorescence intensity
(Excitation λ: 465 nm; Emission λ: 535 nm) was read in a FLX800TBI Microplate Fluorimeter
(BioTek Instruments, Winooski, VT, USA).
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. 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 compound. Positive controls were tested to assess the degree of CETP inhibition by 0.1%
DMSO. CETP was not affected by DMSO. Negative controls lacking rabbit serum were used as
background. All measurements were conducted in duplicates.
Acknowledgments
We are grateful to the Scientific Research and Postgraduate Deanship at Al-Zaytoonah Private
University of Jordan for sponsoring this project.
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Sample Availability: Not available.
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