Synthesis, β-hematin inhibition studies and antimalarial evaluation of dehydroxy isotebuquine derivatives against Plasmodium berghei

Article abstract of DOI:10.1016/j.bmc.2015.05.040

Diverse dehydroxy-isotebuquine derivatives were prepared by using a five step synthetic sequence in good yields. All these new 4-aminoquinolines were evaluated as inhibitors of haemozoin formation, where most of them showed a significant inhibition value

Full text of DOI:10.1016/j.bmc.2015.05.040

Bioorganic & Medicinal Chemistry 23 (2015) 4755–4762
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
Synthesis, b-hematin inhibition studies and antimalarial evaluation
of dehydroxy isotebuquine derivatives against Plasmodium berghei
Angel H. Romero a, María E. Acosta b, Neira Gamboa b, Jaime E. Charris c, José Salazar a, Simón E. López a,
⇑
a Laboratorio de Química Medicinal y Heterociclos, Departamento de Química, Universidad Simón Bolívar, Valle de Sartenejas, Baruta, Caracas 1080-A, Apartado 89000, Venezuela
b Unidad de Bioquímica, Facultad de Farmacia, Universidad Central de Venezuela, Los Chaguaramos, Caracas, Venezuela
c Laboratorio de Síntesis Orgánica, Facultad de Farmacia, Universidad Central de Venezuela, Los Chaguaramos, 1041-A Caracas, Venezuela
a r t i c l e i n f o
a b s t r a c t
Article history:
Diverse dehydroxy-isotebuquine derivatives were prepared by using a five step synthetic sequence in
good yields. All these new 4-aminoquinolines were evaluated as inhibitors of haemozoin formation,
where most of them showed a significant inhibition value (% IHF >97). The best inhibitors were tested
in vivo as potential antimalarials in mice infected with Plasmodium berghei ANKA chloroquine susceptible
strain, three of them (11b, 11d and 11h) displayed an antimalarial activity comparable to that of
chloroquine.
Received 29 March 2015
Revised 15 May 2015
Accepted 24 May 2015
Available online 31 May 2015
Keywords:
Malaria
Ó 2015 Elsevier Ltd. All rights reserved.
Isotebuquine
4-Aminoquinoline
Haemozoin formation
b-Hematin
Antimalarial activity
1. Introduction
has been severely restricted because of associations with hepato-
toxicity and agranulocytosis.7,8 Toxicity of amodiaquine has been
Malaria remains as one of the major causes of illness for humans,
with approximately 250 million of reported clinical cases around
the world annually, particularly in poor or developing countries.1
Plasmodium falciparum malaria causes most of severe cases and
deaths, where near 80% of all reported cases and 90% of malaria-at-
tributed deaths occur in Africa.1 Outside of Africa, Plasmodium vivax
is the predominant species, mainly in Asia, including the Middle
East and the Western Pacific, and in Central and South America.2
In Venezuela, P. vivax infections are very common, accounting for
70% of the total malaria confirmed cases reported to the World
Health Organization in 2013 (from 78.643 total cases of malaria,
30% were caused by P. falciparum infections).1
Chloroquine 1, a 4-amino-quinoline antimalarial, usually is
the first choice drug in the fight against P. falciparum and P. vivax,
but its efficacy has been eroded by the emergence of resistant
parasites. The spread of chloroquine resistance has prompted the
re-investigation of the chemistry and pharmacology of alternative
4-aminoquinoline antimalarials such as amodiaquine 2, which
proved to be effective against chloroquine-resistant strains.3–5
Amodiaquine is effective against many chloroquine resistant
strains of P. falciparum.6 However, clinical use of amodiaquine
related to the reactive metabolites formed by oxidation of its phe-
nolic ring, particularly to the formation of a quinone-imine inter-
mediate by cytochrome P-450-catalyzed biological oxidation.9 It
has been found that amodiaquine is excreted in bile exclusively
as the 50-thioether conjugates (glutathione and cysteinyl) in rats.10
This observation indicates that the parent drug undergoes
extensive biotransformation in vivo to form an amodiaquine qui-
none-imine or semiquinone-imine with subsequent conjugation
of glutathione.11 Structure activity relationship (SAR) studies on
amodiaquine had previously shown that wide variations in the side
chain are accommodated with retention of antimalarial activity.
Blocking of bioactivation pathways by removal of the phenolic
group or introduction of non reactive substituents has been the
main strategy.5,12–14 From SAR studies it has been found that in
the amodiaquine and tebuquine 3 series of 4-aminoquinoline ana-
logs, the presence of the 40-hydroxy group within the aromatic ring
imparts greater inherent antimalarial activity against chloroquine
resistant parasites than the corresponding dehydroxy analogs.5
Interchange of the hydroxy group and the Mannich side chain pro-
vides a means of preventing oxidation to toxic metabolites while
retaining possible important bonding interactions with the aro-
matic hydroxyl function generated an amodiaquine regioisomer
called isoquine 4 which cannot form toxic metabolites by simple
oxidation and is potent against chloroquine resistant parasites
⇑
Corresponding author.
E-mail address: slopez@usb.ve (S.E. López).
http://dx.doi.org/10.1016/j.bmc.2015.05.040
0968-0896/Ó 2015 Elsevier Ltd. All rights reserved.

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A. H. Romero et al. / Bioorg. Med. Chem. 23 (2015) 4755–4762
in vitro. Isoquine itself has been reported to possess potent in vitro
and oral in vivo antimalarial activity in experimental animal mod-
els and it does not
7a–b were obtained by the Suzuki–Miyaura cross coupling reac-
tion between different phenyl boronic acids with the starting
material, 2-bromo-4-nitrotoluene 6. Next, the benzylic bromina-
tion of those biphenyl intermediates followed by their correspond-
ing nucleophilic substitution with different secondary amines and
a subsequent reduction of the nitro group using tin in hydrochloric
acid, afforded the required anilines 10a–h in good yields. Finally,
the heteroaromatic substitution of 4,7-dichloroquinoline on posi-
tion 4 with the above mentioned anilines in refluxing ethanol
employing concd HCl, gave desired 4-aminoquinolines 11a–h as
their hydrochloride salts (Table 1), which were further biologically
tested (Tables 2 and 3).
Cl
OH
NH
OH
NH
N
N
N
HN
Cl
N
Cl
N
Cl
N
1
3
2
2.2. Biological
N
NH
Different quinoline antimalarials are thought to target ferripro-
toporphyrin IX (FP IX) heme within the digestive vacuole of the
OH
OH
Table 1
NH
N
NH
Yields of the last step for the synthesis of dehydroxy-isotebuquine derivatives 11 a–h
X
x 2HCl
Z
Cl
Cl
N
4
5
X
Z
NH
N
Cl
N
undergo in vivo biotransformation to quinone-imine metabolites.5
Apart from an excellent antiparasitic profile, isoquine and its differ-
ent side-chain analogs, like the recently developed N-tert-butyl iso-
quine 5 are rather inexpensive antimalarials to synthesize and were
expected to represent new leads for development of a safe, cheap,
affordable, and effective antimalarials for both prophylaxis and
treatment of malaria.15,16 Unfortunately, N-tert-butyl isoquine 5
development was terminated16 but recently, it was retaken for
phase II clinical trials in Mali to study its efficacy in uncomplicated
P. falciparum malaria.35 Intrigued by the importance of the 30-OH on
the side chain of isoquine for the antimalarial activity, we decided
to synthesize a group of 30-dehydroxy analogs of isotebuquine
11a–h and test them for both their b-hematin inhibition and pre-
liminary antimalarial activity.
EtOH, HCl (cat)
reflux, 2h
+
Cl
Cl
NH2
11a-h
10a-h
Compd No.
X
H
H
Z
Yield (%)
82a
NEt2
11a
11b
N
90
11c
11d
11e
11f
H
N
N
O
79
87
38
84
86
72
H
Cl
Cl
Cl
Cl
N
N
NMe
O
2. Results and discussion
2.1. Chemistry
11g
11h
N
N
The synthesis of title compounds 11a–h is depicted on
Scheme 1. First, the corresponding nitro-biphenyl compounds
a
Compound 11a was obtained as the monohydrochloride salt.
X
Z
X
X
Br
Br
d
c
b
a
NO2
NO2
NO2
NO2
8a-b
9a-h
6
7a-b
X
Z
X= H, Cl
Z=
X
Z
NEt2
N
O
e
NH
N
N
N
N
NMe
NH2
Cl
10a-h
11a-h
Scheme 1. Synthesis of novel dehydroxy-isotebuquine derivatives. Conditions: (a) phenylboronic acid (1.2 equiv)/toluene, Pd(PPh3)4 (5%), K2CO3 (2.5 equiv)/EtOH–H2O (1:1),
100 °C, 24 h; (b) NBS (1.2 equiv)/CCl4, (PhCO)2O2 (0.05 equiv), light, reflux/24 h; (c) dialkylamine (5 equiv)/toluene, reflux, 6 h; (d) Sn/HCl, 70 °C, 2 h; (e) 4,7-dichloroquinoline
(1.2 equiv)/EtOH, concd HCl (1 equiv), reflux, 6 h.

A. H. Romero et al. / Bioorg. Med. Chem. 23 (2015) 4755–4762
4757
Table 2
Table 3
Percentage of inhibition of haemozoin formation (% IHF) for compounds 11a–h
The effect of dehydroxy-isotebuquine derivatives 11a–d, 11f, 11h on P. berghei
infected mice (20 mg kgꢀ1
)
X
x 2HCl
Z
Compd No.
Post-infection days of survival ( SD)a
% P ( SD)b
11a
11b
11c
11d
11f
11h
25.20 (3.00)*
28.40 (1.60)*
23.20 (3.17)*
28.60 (1.40)*
26.00 (2.75)*
27.30 (1.40)**
29.40 (0.40)
6.80 (0.70)
3.20 (1.30)
1.80 (0.45)
6.50 (0.60)
2.10 (0.30)
7.30 (0.45)
2.00 (0.54)
0.60 (0.08)
65.20 (2.58)
NH
N
Cl
Control treatedc
Control untreated
11a-i
a
Results are expressed as the media standard deviation (SD). n = 6 (number of
Compd No.
11a
X
H
H
Z
% IHF ( SD)a,b
98.450 (0.008)d
97.080 (0.002)
treated mice).
NEt2
N
b
c
% P: percentage of parasitemia.
Positive control treated with chloroquine (25 mg kgꢀ1).
P <0.05 comparing to control treated group.
P <0.01 comparing to control treated group.
11b
*
**
N
N
O
11c
11d
11e
11f
11g
H
H
98.040 (0.015)
98.490 (0.014)
1.610 (0.061)
97.210 (0.054)
2.030 (0.040)
11a–d, 11f, 11h were all capable of increase significantly the sur-
vival time in more than 20 days post-infection (Table 3), but partic-
ularly three compounds 11b, 11d and 11h increased the survival
rates comparable to chloroquine, respectively. As can be seen,
there is a good correlation between inhibition of haemozoin forma-
tion, the reduction of the parasitemia and the survival time of
infected mice for these last three most active compounds.
Despite some derivatives (11a, 11c, 11f) were very effective as
inhibitors of the haemozoin formation, they were not able to
extent the survival rate of infected mice over 27 days, perhaps this
result is related to the pharmacokinetics and bioavailability of
these compounds in vivo. Both, the N-piperazino substituted
quinoline 11e and the N-morpholino analog 11g, respectively,
were the two least active compounds of the series as inhibitors
of the haemozoin formation. We believe this could be related, in
the case of compound 11e, to the pKa of the N-benzyl nitrogen
when interacting with the heme group affecting it (calculated
N
N
NMe
Cl
Cl
Cl
N
N
O
11h
Chloroquinec
Cl
—
97.250 (0.021)
98.570 (0.015)
—
a
b
c
SD: standard deviation.
% IHF: percentage of inhibition of haemozoin formation.
Control.
Monohydrochloride.
d
parasite, once it is released upon hemoglobin digestion.17,18 Free FP
IX is toxic and the malaria parasite sequesters FP IX as nontoxic
crystalline haemozoin.19,20 Heme detoxification in haemozoin is
believed to be the main target of quinoline containing antimalari-
als.21–23 It is not well known how quinoline drugs target heme to
inhibit haemozoin formation in vivo, and even nor is it understood
whether different quinoline antimalarials inhibit haemozoin
through similar or different pathways.21 Despite there is still some
controversy, it has been shown that the inhibition of haemozoin
growth will depend on drug accumulation inside the parasite
digestive vacuole, where it can target the soluble forms of hematin
monomer or dimer24–26 and/or the haemozoin crystal face
{0.01}.27,28 Recently, it has been shown for quinoline related drugs
(including chloroquine) that in vitro drug–heme interactions lead-
ing to the inhibition of b-hematin correlated with parasite growth
inhibition (cytostatic activity) and suggested they do not necessar-
ily affect the cytocidal potency.29–31
The antimalarial activity of synthesized 4-amino-quinolines
11a–h was evaluated through the test of the ability of the com-
pounds to inhibit b-hematin (synthetic haemozoin) formation,
considering that haemozoin can be formed spontaneously under
acid and low oxygen conditions found in the food vacuole of the
parasite.32 Results showing more than 50% of inhibition of haemo-
zoin formation were considered significant (compounds 11a–d,
11f, 11h; see Table 2).
pKa = 3.8, value obtained from the ChemBioDraw Ultra suite),33
a
hypothesis that should be still investigated. The reasons for the
strong difference encountered between compounds 11c and 11g
as inhibitors of haemozoin formation (Table 2) are unknown, the
calculated pKa for both is close (7.5 and 7.4, respectively) and
11g (ClogP = 7.2) seemed to be more lipophilic than 11c
(ClogP = 6.5).33 Based on recent suggestions,21 we consider
important to test further the comparison of % of b-hematin inhibi-
tion of most active compounds with their cytostatic (IC50) versus
the cytocidal (LD50) effects in order to better understand their
possible mechanism of action. Our results are still preliminary
and require also further evaluation to discard toxic compounds
(such as the selectivity index, SI),36 however from the in vivo test,
no apparently toxicity was seen on mice for most active
compounds The quinolines 11b, 11d and 11h should merely be
evaluated as antimalarial compounds over P. falciparum chloro-
quine susceptible and resistance strains, their high activity over
P. berghei chloroquine sensitive parasites showed that the 30-OH
substitution is not full necessary in this case for an effective
antimalarial potency, a remarkable difference when compared to
amodiaquine analogs which lacks the 40-OH group.5
Quinolines 11a–d, 11f, 11h were then selected and tested in
mice infected with Plasmodium berghei ANKA, a chloroquine-
susceptible strain of murine malaria (Table 3). Mice were given
the compound (chloroquine in 25 mg kgꢀ1 or 11a–d, 11f and 11h
in 20 mg kgꢀ1, ip once daily) for 4 consecutive days (days 0–4
post-infection). At day fourth post-infection, the parasitemia was
determined, the survival days were monitored and compared with
control mice receiving saline (untreated mice).34 Control mice
died between days 6 and 7 post-infection. In general, compounds
3. Conclusions
Eight dehydroxy-isotebuquine derivative 11a–h were prepared
by using a five step synthetic sequence in good yields. All these
new 4-aminoquinolines were evaluated as inhibitors of haemozoin
formation, but only six (11a–d, 11f and 11h) showed a significant
inhibition value (% IHF >97). Compounds 11a–d, 11f and 11h were
tested in vivo as potential antimalarials in mice infected with P.

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A. H. Romero et al. / Bioorg. Med. Chem. 23 (2015) 4755–4762
berghei ANKA chloroquine susceptible strain, three of them (11b,
11d and 11h) displayed an antimalarial activity comparable to that
of chloroquine, demonstrating that the 30-hydroxy group for these
dehydroxy-isotebuquine analogs is not necessary for a potent anti-
malarial effect.
4.1.2. General procedure for the preparation of 2-
(bromomethyl)-5-nitro-1,10-biphenyls 8a–b
To a solution of the corresponding 2-methyl-5-nitro-1,10-biphe-
nyl 7a–b (16 mmol) in carbon tetrachloride (90 mL) was added N-
bromosuccinimide (3.7 g, 20.8 mmol) and benzoyl-peroxide
(0.19 g, 0.8 mmol). The reaction was refluxed with stirring for
24 h under light irradiation. The mixture was then cooled at room
temperature, the solid succinimide filtered and the solvent evapo-
rated under vacuo to give a crude material which was purified by
column chromatography using hexanes.
4. Experimental
4.1. Chemistry
Melting points were determined in a Fischer-Johns micro hot-
stage apparatus and are uncorrected. NMR spectra were obtained
using a JEOL Eclipse Plus or JEOL Eclipse spectrometers in either
deuterated chloroform (CDCl3) or hexadeuterated dimethylsulfox-
ide (DMSO-d6). 1H NMR were recorded at 400 or 270 MHz, 13C
NMR at 100 or 67.9 MHz, respectively. Chemical shifts (d) are
given in ppm downfield from the residual CHCl3 or DMSO (1H
NMR, 13C NMR). Coupling constants are given in hertz. The IR
spectra were recorded as KBr disks (for solids) or liquid films in
NaCl cells (for oils) using a FT-IR Nicolet Magna Spectrometer.
GC–MS spectra were recorded using an Agilent Gas
Chromatograph model 7898A using an EI ionization (70 eV).
Elemental analyses of new synthesized compounds were per-
formed on a Perkin Elmer 2400 CHN analyzer; results fell in the
range of 0.4% of the required theoretical values. Silica gel plates
4.1.2.1. 2-(Bromomethyl)-5-nitro-1,10-biphenyl 8a. Yellow oil,
75%. FT-IR (m
, cmꢀ1): 1571 (st, NO2), 1477 (st, NO2). 1H NMR
(270 MHz, CDCl3, d, cmꢀ1): 8.18 (dd, 1H, J = 8.4 Hz, J = 2.5 Hz),
8.12 (d, 1H J = 2.5 Hz), 7.70 (d, 1H, J = 8.4 Hz), 7.47 (m, 5H), 4.44
(s, 2H CH2). 13C NMR (67.9 MHz, CDCl3, d, cmꢀ1): 147.5, 143.4,
142.4, 138.0, 132.1, 128.9, 128.6, 125.4, 122.8, 29.8. Anal. Calcd
for C13H10BrNO2: C, 53.45; H, 3.45; N, 4.79. Found: C, 53.54; H,
3.49; N, 4.84.
4.1.2.2.
8b. White solid, 70%, mp 114–116 °C. FT-IR (
2-(Bromomethyl)-40-chloro-5-nitro-1,10-biphenyl
, cmꢀ1): 1476
m
(st, NO2). 1H NMR (270 MHz, CDCl3, d, cmꢀ1): 8.20 (dd, 1H,
J = 8.4 Hz, J = 2.5 Hz), 8.10 (d, 1H, J = 2.5 Hz), 7.69 (d, 1H,
J = 8.4 Hz), 7.47 (d, 2H, J = 8.2 Hz), 7.38 (d, 2H, J = 8.2 Hz),
4.39 (s, 2H CH2). 13C NMR (67.9 MHz, CDCl3, d, cmꢀ1): 147.2,
142.2, 142.1, 136.3, 134.9, 132.2, 130.2, 129.1, 125.3, 123.1,
29.2. GC–MS (60 eV, m/z): 325 (M+, 100%). Anal. Calcd for
ALUGRAMÒ SIL G/UV254 (Macherey-Nagel GmbH
&
Co.,
Germany) were used for TLC testing. Column chromatography
was performed, when required, with Kieselsgel 60 silica (70–
230 mesh, Merck, Darmstadt, Germany) and hexanes–ethyl acet-
ate as eluent. Reagents were obtained from Aldrich (Milwaukee,
MI, USA) or Merck (Darmstadt, Germany) and used without fur-
ther purification.
C
13H9BrClNO2: C, 47.81; H, 2.78; N, 4.29. Found: C, 47.69; H,
2.82; N, 4.32.
4.1.3. General procedure for the preparation of 1-((5-nitro-[1,10-
biphenyl]-2-yl)methyl)amines 9a–h
4.1.1. General procedure for the preparation of 2-methyl-5-
nitro-1,10-biphenyls 7a–b
To a solution of the corresponding 2-(bromomethyl)-5-nitro-
1,10-biphenyl 8 (2 mmol) in toluene (30 mL) was added the
dialkylamine (10 mmol, 5 equiv) and the reaction stirred under
reflux for 6 h. The mixture was then cooled at room temperature,
the solvent evaporated under vacuo and the unreacted dialky-
lamine eliminated through vacuum distillation. The remaining
residue was treated with sodium hydroxide (aq 10%) and the
obtained solid filtrated and recrystallized (EtOH) to give yellow-
orange colored solids.
To a mixture of 2-bromo-4-nitrotoluene (14 mmol), substituted
phenylboronic acid (16.8 mmol, 1.2 equiv) and tetrakis(triph-
enylphosphine)palladium(0) (0.81 g, 0.7 mmol, 5%) in toluene
(50 mL) was added potassium carbonate (35 mmol, 2.5 equiv) dis-
solved in a water–ethanol (1:1) solution (30 mL). The mixture was
heated (100 °C) with stirring under argon for 24 h, cooled at room
temperature and filtered, washed with water (3 ꢁ 20 mL), the
organic phase treated with anhydrous magnesium sulfate, filtered
and evaporated under vacuo to give a brown crude solid which was
further purified by column chromatography using hexanes–ethyl
acetate (9:1).
4.1.3.1. N-Ethyl-N-((5-nitro-[1,10-biphenyl]-2-yl)methyl)ethana-
mine 9a. Yellow oil, 67%. FT-IR (m
, cmꢀ1): 1475 (st, NO2). 1H NMR
(270 MHz, CDCl3, d, cmꢀ1): 8.18 (dd, 1H, J = 8.5 Hz, J = 2.5 Hz), 8.07
(d, 1H, J = 2.5 Hz), 8.02 (br s, 1H), 7.27–7.47 (m, 5H), 3.59 (s, 2H,
CH2), 2.45 (q, 4H, CH2), 0.88 (t, 6H, CH3). 13C NMR (67.9 MHz,
CDCl3, d, cmꢀ1): 148.2, 144.9, 137.7, 137.6, 133.5, 129.4 (2C),
129.3 (2C), 129.2, 125.4, 123.5, 51.5 (CH2-N), 46.1 (2C, CH2), 8.2
(2C, CH3). GC–MS (60 eV, m/z): 284 (M+, 100%). Anal. Calcd for
4.1.1.1. 2-Methyl-5-nitro-1,10-biphenyl 7a. Yellow solid, 78%,
mp: 74–76 °C. FT-IR (m
, cmꢀ1): 1571 (st, NO2), 1478 (st, NO2). 1H
NMR (270 MHz, CDCl3, d, cmꢀ1): 8.08 (m, 2H), 7.39 (m, 6H), 2.35
(s, 3H, CH3). 13C NMR (67.9 MHz, CDCl3, d, cmꢀ1): 146.4, 143.2,
139.7, 131.2, 129.0 (2C), 128.6 (2C), 128.0, 124.7, 122.2, 20.9.
GC–MS (60 eV, m/z): 213 (M+, 100%). Anal. Calcd for C13H11NO2:
C, 73.23; H, 5.20; N, 6.57. Found: C, 73.30; H, 5.14; N, 6.52.
C17H20N2O2: C, 71.81; H, 7.09; N, 9.85. Found: C, 71.89; H, 7.03;
N, 9.79.
4.1.3.2. 1-((5-Nitro-[1,10-biphenyl]-2-yl)methyl)piperidine 9b.
Yellow solid, 87%, mp 60–62 °C. IR (KBr,
m
cmꢀ1): 1583, 1497 (st.
N@O, nitro). 1H NMR (270 MHz, d ppm, CDCl3): 8.17 (dd, 1H,
J = 8.1 Hz, J = 1.9 Hz), 8.10 (d, 1H), 7.90 (d, 1H), 7.41–7.51 (m,
3H), 7.27–7.29 (m, 2H), 3.85 (s, 2H, CH2-N), 2.49 (br s, 4H, CH2-
N), 1.69 (br s, 4H, CH2), 1.44 (br s, 2H, CH2). 13C NMR (100 MHz,
d ppm, CDCl3): 147.3, 144.4, 138.6, 132.0, 132.0, 129.3 (2C),
128.8 (2C), 128.4, 125.0, 12.6, 58.5 (CH2-N), 54.0 (2C, CH2-N),
24.5 (CH2), 23.3 (CH2). GC–MS (60 eV, m/z): 296 (M+, 100%). Anal.
Calcd for C18H20N2O2: C, 72.95; H, 6.80; N, 9.45. Found: C, 72.88;
H, 6.84; N, 9.50.
4.1.1.2. 40-Chloro-2-methyl-5-nitro-1,10-biphenyl 7b. White
solid, 81%, mp: 108–110 °C. FT-IR (m
, cmꢀ1): 1564 (st, NO2), 1477
(st, NO2). 1H NMR (270 MHz, CDCl3, d, cmꢀ1): 8.10 (dd, 1H,
J = 8.4 Hz; J = 2.5 Hz), 8.06 (d, 1H, J = 2.2 Hz), 7.42 (m, 2H), 7.24 (m,
2H, 2H), 2.34 (s, 3H, CH3). 13C NMR (60 MHz, CDCl3, d, cmꢀ1):
146.3, 143.5, 141.9, 138.0, 134.2, 131.4, 130.4 (2C), 128.9 (2C),
124.6, 122.5, 20.8 (CH3). GC–MS (60 eV, m/z): 247 (M+, 100%).
Anal. Calcd for C13H10NO2Cl: C, 63.04; H, 4.07; N, 5.66. Found: C,
63.10; H, 4.11; N, 5.60.

A. H. Romero et al. / Bioorg. Med. Chem. 23 (2015) 4755–4762
4759
4.1.3.3.
9c. Yellow solid, 91%, mp 118–120 °C. IR (KBr,
4-((5-Nitro-[1,10-biphenyl]-2-yl)methyl)morpholine
cmꢀ1): 1570,
4.1.4. General procedure for the preparation of anilines 10a–h
A mixture of the corresponding 1-((5-nitro-[1,10-biphenyl]-
2-yl)methyl)amine 9 (2 mmol), tin powder (4 mmol) and concen-
trated hydrochloric acid (20 mmol) was heated (70 °C) with
stirring for 2 h. The mixture was then cooled at room temperature
and neutralized carefully with a solution of NaOH (aq 10%),
extracted with dichloromethane (3 ꢁ 20 mL), the organic phase
washed with distilled water, dried (MgSO4), filtered and the
solvent evaporated under vacuo to give a solid aniline product
which was purified by column chromatography (Hex/EtOAc 7:3).
m
1495 (st. N@O, nitro). 1H NMR (270 MHz, d ppm, CDCl3): 8.22 (d,
1H, J = 6.7 Hz), 8.13 (br s, 1H), 7.41–7.52 (m, 3H), 7.30–7.28 (m,
2H), 3.80 (br s, 6H, CH2-O, CH2-N), 2.54 (br s, 4H, CH2-N). 13C
NMR (100 MHz, d ppm, CDCl3): 147.5, 144.5, 138.4, 132.1, 130.0,
129.2 (2C), 128.9 (2C), 128.6, 125.2, 122.6, 65.6 (2C, CH2-O), 58.4
(2C, CH2-N), 52.79 (CH2-N). GC–MS (60 eV, m/z): 298 (M+, 100%).
Anal. Calcd for C17H18N2O3: C, 68.44; H, 6.08; N, 9.39. Found: C,
68.51; H, 6.12; N, 9.32.
4.1.3.4. 1-((5-Nitro-[1,10-biphenyl]-2-yl)methyl)pyrrolidine 9d.
4.1.4.1. 6-((Diethylamino)methyl)-[1,10-biphenyl]-3-amine 10a.
Orange solid, 81%, mp 92–94 °C. IR (KBr,
m
cmꢀ1): 1570, 1465 (st.
Yellow solid, 74%, mp 61–63 °C. IR (KBr, m
cmꢀ1): 3352, 3162
N@O, nitro). 1H NMR (270 MHz, d ppm, CDCl3): 8.26 (s, 1H), 8.13
(m, 2H); 7.50–7.24 (m, 5H), 3.99 (s, 2H, CH2-N), 2.86 (br s, 4H,
CH2-N), 1.87 (br s, 4H, CH2). 13C NMR (100 MHz, d ppm, CDCl3):
148.2, 144.4, 137.7, 134.4, 133.0, 129.5 (2C), 129.2 (2C), 129.2,
125.3, 123.6, 54.1 (CH2-N), 53.8 (2C, CH2-N), 23.0 (CH2). GC–MS
(60 eV, m/z): 281 ((Mꢀ1)+, 100%). Anal. Calcd for C17H18N2O2: C,
72.32; H, 6.43; N, 9.92. Found: C, 72.39; H, 6.39.; N, 9.85.
(st. N–H). 1H NMR (270 MHz, d ppm, CDCl3): 8.18 (dd, 1H,
J = 8.5 Hz, J = 2.5 Hz), 8.07 (d, 1H, J = 2.5 Hz), 8.02 (d, 1H,
J = 2.5 Hz), 7.27–7.47 (m, 5H), 3.59 (s, 2H, CH2-N), 2.45 (c, 4H,
CH2-N), 0.88 (t, 6H, CH3). 13C NMR (100 MHz, d ppm, CDCl3):
144.8, 140.5, 133.6, 129.6, 129.4, 128.8, 127.8, 116.4, 115.2, 51.9
(CH2-N), 46.2 (CH2-N), 8.7 (CH3). GC–MS (60 eV, m/z): 284 (M+,
100%).
Anal. Calcd for C17H22N2: C, 80.27; H, 8.72; N, 11.01. Found: C,
80.34.50; H, 8.69; N, 11.05.
4.1.3.5.
methylpiperazine 9e. Yellow solid, 90%, mp 100–102 °C. IR (KBr,
cmꢀ1): 1582, 1497 (st. N@O, nitro). 1H NMR (270 MHz, d ppm,
CDCl3): 8.17 (dd, 1H, J = 8.5 Hz, J = 2.5 Hz), 8.08 (d, 1H, J = 2.5 Hz),
7.70 (d, 1H, J = 8.6 Hz), 7.41 (d, 2H, J = 8.4 Hz), 7.29 (d, 2H,
J = 8.4 Hz), 3.43 (s, 2H, CH2-N), 2.46 (br s, 8H, CH2-N), 2.33 (3H,
CH3). 13C NMR (100 MHz, d ppm, CDCl3): 146.9, 143.5, 142.7, 137.4,
134.3, 130.9, 130.6 (2C), 128.7 (2C), 125.0, 122.3, 59.4 (CH2-N), 55.0
(2C, CH2-N), 52.4 (2C, CH2-N), 45.71 (N-CH3). Anal. Calcd for
1-((40-Chloro-5-nitro-[1,10-biphenyl]-2-yl)methyl)-4-
m
4.1.4.2. 6-(Piperidin-1-ylmethyl)-[1,10-biphenyl]-3-amine 10b.
Yellow solid, 84%, mp 120–122 °C. IR (KBr, m
cmꢀ1): 3422, 3311
(st. N–H). 1H NMR (400 MHz, d ppm, CDCl3): 7.30–7.37 (m, 6H),
6.66 (dd, 1H, J = 9.5 Hz, J = 2.5 Hz), 6.58 (d, 1H, J = 2.5 Hz), 3.65 (s,
2H, CH2-N), 3.30 (s, 2H, NH2), 2.25 (br s, 4H, CH2-N), 1.51 (br s,
4H, CH2), 1.36 (2H, CH2). 13C NMR (100 MHz, d ppm, CDCl3):
145.0, 143.9, 141.8, 131.6, 129.6, 127.8, 126.8, 116.7, 114.1, 59.8
(CH2-N), 54.0 (CH2-N), 25.9 (CH2), 24.4 (CH2). Anal. Calcd for
C18H20ClN3O2: C, 62.52; H, 5.83; N, 12.15. Found: C, 62.46; H, 5.86;
N, 12.19.
C18H22N2: C, 81.16; H, 8.32; N, 10.52. Found: C, 81.10; H, 8.36; N,
10.47.
4.1.3.6. 1-((40-Chloro-5-nitro-[1,10-biphenyl]-2-yl)methyl)piper-
idine 9f. Orange solid, 84%, mp 106–108 °C. IR (KBr,
m
cmꢀ1):
4.1.4.3. 6-(Morpholinomethyl)-[1,10-biphenyl]-3-amine 10c.
1480 (st. N@O, nitro). 1H NMR (270 MHz, d ppm, J Hz, CDCl3):
8.21 (dd, 1H, H5, J = 8.64; 2.22); 8.08 (d, 1H, H3, J = 2.2); 7.94 (s,
1H, H6); 7.41 (d, 2H, 2H30, J = 8.40); 7.28 (d, 2H, 2H20, J = 8.40);
3.48 (s, 2H, CH2-N); 2.33 (s, 4H, CH2-N); 1.58 (sa, 4H, CH2); 1.43
(sa, 2H, CH2). 13C NMR (100 MHz, d ppm, CDCl3): 147.8, 142.9,
137.3, 134.6, 131.8, 130.7, 128.9, 124.9, 122.8, 59.3 (CH2-N), 54.2
(2C, CH2-N), 25.1 (2C, CH2), 23.5 (CH2). Anal. Calcd for
C18H19ClN2O2: C, 65.35; H, 5.79; N, 8.47. Found: C, 65.41; H,
5.83; N, 8.41.
Yellow solid, 85%, mp 128–130 °C. IR (KBr, m
cmꢀ1): 3428, 3314
(est. N–H). 1H NMR (270 MHz, d ppm, CDCl3): 7.31–7.38 (m, 6H),
6.67 (dd, 1H, J = 2.5 Hz, J = 8.1 Hz), 6.58 (d, 1H, J = 2.5 Hz), 3.97 (t,
4H, CH2-O), 3.50 (br s, 2H, CH2-N), 2.41 (br s, 4H, CH2-N). 13C
NMR (100 MHz, d ppm, CDCl3): 145.9, 144.4, 141.3, 132.2, 129.5,
128.2, 127.2, 116.7, 114.3, 66.2 (2C, CH2-O), 59.1 (2C, CH2-N),
52.5 (N-CH2). Anal. Calcd for C17H20N2O: C, 76.09; H, 7.51; N,
10.44. Found: C, 76.13; H, 7.54; N, 10.48.
4.1.4.4. 6-(Pyrrolidin-1-ylmethyl)-[1,10-biphenyl]-3-amine 10d.
Orange solid, 86%, mp 57–59 °C. IR (KBr,
4.1.3.7. 4-((40-Chloro-5-nitro-[1,10-biphenyl]-2-yl)methyl)mor-
pholine 9g. Beige solid, 89%, mp 95–96 °C. IR (KBr,
m
cmꢀ1): 3421, 3310 (st.
m
cmꢀ1): (st.
N–H). 1H NMR (270 MHz, d ppm, CDCl3): 7.45 (d, 1H, J = 8.1 Hz),
6.70 (dd, 1H, J = 8.1 Hz, J = 2.5 Hz); 6.57 (d, 1H, J = 2.5 Hz), 3.69 (s,
2H, CH2-N), 3.58 (s, 2H, NH2), 2.50 (br s, 4H, CH2-N), 1.87 (br s,
4H, CH2). 13C NMR (100 MHz, d ppm, CDCl3): 147.1, 144.5, 140.3,
133.3, 129.3, 129.1, 128.9, 116.6, 115.5, 54.0 (CH2-N), 52.3 (CH2-
N), 25.63 (CH2). Anal. Calcd for C17H20N2: C, 80.91; H, 7.99; N,
11.10. Found: C, 80.99; H, 8.04; N, 11.15.
N@O, nitro). 1H NMR (270 MHz, d ppm, CDCl3): 8.23 (dd, 1H,
J = 8.7 Hz), 8.11 (d, 1H, J = 2.2 Hz), 7.86 (br s, 1H), 7.47 (d, 2H,
J = 8.4 Hz), 7.38 (d, 2H, J = 8.4 Hz), 3.79 (br s, 4H, 2CH2-O), 3.71 (s,
2H, CH2-N), 2.75 (s, 4H, CH2-N). 13C NMR (100 MHz, d ppm,
CDCl3): 147.3, 143.0, 137.1, 134.7, 131.7 (2C), 130.6 (2C), 129.0,
125.1, 122.7, 66.2 (2C, CH2-O), 63.8 (CH2-N), 53.1 (2C, CH2-N).
Anal. Calcd for C17H17ClN2O3: C, 61.36; H, 5.15; N, 8.42. Found:
C, 61.43; H, 5.11; N, 8.47.
4.1.4.5.
biphenyl]-3-amine 10e.
(KBr,
cmꢀ1): 3361, 3208 (st. N–H). 1H NMR (270 MHz, d ppm,
40-Chloro-6-((4-methylpiperazin-1-yl)methyl)-[1,10-
Yellow solid, 71%, mp 131–133 °C. IR
4.1.3.8. 1-((40-Chloro-5-nitro-[1,10-biphenyl]-2-yl)methyl)pyrro-
lidine 9h. Orange solid, 87%, mp 102–104 °C. IR (KBr, m
cmꢀ1): 1479
m
(st. N@O, nitro). 1H NMR (270 MHz, d ppm, CDCl3): 8.24 (dd, 1H,
J = 8.4 Hz), 8.16 (br s, 1H), 8.09 (d, 1H, J = 1.8 Hz), 7.45 (d, 2H,
J = 8.2 Hz), 7.27 (d, 2H, J = 8.4 Hz), 3.88 (s, 2H, CH2-N), 2.71 (br s,
4H, CH2-N), 1.87 (br s, 4H, CH2). 13C NMR (400 MHz, d ppm,
CDCl3): 147.3, 142.4, 136.9, 134.9, 131.7, 130.6, 129.1, 125.0,
123.1, 55.9 (CH2-N), 53.9 (CH2-N), 23.4 (2C, CH2). Anal. Calcd for
CDCl3): 7.33 (m, 4H), 7.20 (d, 1H, J = 8.1 Hz), 6.64 (dd, 1H, H5,
J = 8.2 Hz, J = 2.2 Hz), 6.64 (d, 1H, J = 2.2 Hz), 3.68 (s, 2H, NH2),
3.28 (s, 2H, CH2-N), 2.45 (br s, 8H, CH2-N), 2.31 (3H, CH3). 13C
NMR (100 MHz, d ppm, CDCl3): 145.5, 142.9, 140.1, 133.0, 132.0,
130.9, 128.0, 116.7, 114.2, 59.2 (CH2-N), 54.9 (CH2-N), 51.6 (CH2-
N), 45.5 (CH3).
Anal. Calcd for C18H22ClN3: C, 68.45; H, 7.02; N, 13.30. Found: C,
68.51; H, 6.98; N, 13.27.
C17H17ClN2O2: C, 64.45; H, 5.41; N, 8.84. Found: C, 64.50; H,
5.37; N, 8.90.

4760
A. H. Romero et al. / Bioorg. Med. Chem. 23 (2015) 4755–4762
4.1.4.6.
40-Chloro-6-(piperidin-1-ylmethyl)-[1,10-biphenyl]-3-
1H, J = 9.1 Hz, J = 2.2 Hz), 7.65 (d, 1H, J = 8.4 Hz, J = 2.2 Hz), 7.40–
7.54 (m, 6H), 7.10 (d, 1H, J = 6.9 Hz), 4.31 (s, 2H, CH2-N), 2.51 (br
s, 4H, CH2-N), 1.66 (6H, CH2). 13C NMR (60 MHz, d ppm, DMSO-
d6): 155.0, 145.7, 144.6, 139.8, 139.2, 138.5, 133.7, 129.9, 129.5,
128.7, 128.2, 126.9, 126.5, 126.4, 124.5, 120.1, 116.8, 101.6, 56.2
(CH2-N), 52.7 (CH2-N), 22.6 (CH2), 21.45 (CH2). Anal. Calcd (dihy-
drochloride salt) for C27H28Cl3N3: C, 64.74; H, 5.63; N, 8.39.
Found: C, 64.85; H, 5.70; N, 8.29.
amine 10f. Light yellow solid, 70%, mp 145–147 °C. IR (KBr,
m
cmꢀ1): 3422, 3307 (st. N–H). 1H NMR (400 MHz, d ppm, CDCl3):
7.46 (d, 1H, J = 8.3 Hz), 7.34 (d, 2H, J = 8.2 Hz), 7.28 (d, 2H,
J = 8.4 Hz), 6.68 (dd, 1H, J = 8.3 Hz, J = 2.5), 6.52 (d, 1H, J = 2.5 Hz),
3.74 (s, NH2), 3.47 (s, 2H, CH2-N), 2.37 (br s, 4H, CH2), 1.61 (br s,
4H, CH2), 1.39 (2H, CH2). 13C NMR (100 MHz, d ppm, CDCl3):
145.9, 143.0, 139.9, 132.6, 130.9, 128.3, 116.5, 114.6, 59.1 (CH2-
N), 53.5 (CH2-N), 25.0 (CH2), 23.8 (CH2). Anal. Calcd for
C18H21ClN2: C, 71.87; H, 7.04; N, 9.31. Found: C, 71.94; H, 7.08;
4.1.5.3. 7-Chloro-N-(6-(morpholinomethyl)-[1,10-biphenyl]-3-
yl)quinolin-4-amine dihydrochloride 11c. Yellow solid, 79%,
N, 9.27.
mp 232–234 °C. IR (KBr,
m
cmꢀ1): 3528, 3446 (st. N–H). 1H NMR
4.1.4.7.
40-Chloro-6-(morpholinomethyl)-[1,10-biphenyl]-3-
cmꢀ1):
(400 MHz, d ppm, DMSO-d6): 8.79 (d, 1H, J = 9.2 Hz), 8.54 (d, 1H,
H2, J = 7.0 Hz), 8.07 (m, 2H), 7.86 (d, 1H, J = 9.2 Hz), 7.63 (d, 1H,
J = 7.3 Hz) 7.42–7.53 (m, 6H), 7.10 (d, 1H, J = 7.0 Hz), 4.34 (br s,
4H, CH2-O), 3.80 (br s, 2H, CH2-N), 2.49 (br s, 4H, CH2-N). 13C
NMR (100 MHz, d ppm, DMSO-d6): 155.2, 145.7, 144.2, 139.6,
139.3, 139.2, 138.5, 133.9, 129.9, 129.4, 128.7, 128.2, 127.0,
126.7, 126.3, 124.6, 119.9, 116.8, 101.5, 63.5 (CH2-O), 56.6 (CH2-
N), 51.7 (CH2-N). Anal. Calcd (dihydrochloride salt) for
amine 10g. Yellow solid, 79%, mp 105–107 °C. IR (KBr,
m
3314, 3212 (st. N–H). 1H NMR (270 MHz, d ppm, CDCl3): 7.31 (m,
5H), 6.68 (dd, 1H, J = 8.2 Hz, J = 2.5 Hz), 6.54 (d, 1H, J = 2.5 Hz),
3.71 (s, 2H, CH2-O), 3.64 (s, 2H, NH2), 3.45 (s, 2H, CH2-N), 2.42
(br s, 4H, CH2-N). 13C NMR (100 MHz, d ppm, CDCl3): 146.2,
143.2, 139.8, 133.3, 132.6, 130.8, 128.3, 116.5, 114.6, 66.2 (CH2-
O), 59.2 (CH2-N), 52.6 (CH2-N). Anal. Calcd for C17H19ClN2O: C,
67.43; H, 6.32; N, 9.25. Found: C, 67.49; H, 6.37; N, 9.28.
C26H26Cl3N3O: C, 62.10; H, 5.21; N, 8.36. Found: C, 62.18; H,
5.17; N, 8.42.
4.1.4.8. 40-Chloro-6-(pyrrolidin-1-ylmethyl)-[1,10-biphenyl]-3-
amine 10h. Yellow solid, 71%, mp 99–101 °C. IR (KBr,
m
cmꢀ1):
4.1.5.4. 7-Chloro-N-(6-(pyrrolidin-1-ylmethyl)-[1,10-biphenyl]-
3-yl)quinolin-4-amine dihydrochloride 11d. Yellow solid, 87%,
mp 228–230 °C. IR (KBr,
3430, 3280 (est. N–H). 1H NMR (270 MHz, d ppm, CDCl3): 7.29–
7.33 (m, 4H), 6.67 (d, 1H, J = 8.2 Hz, J = 2.5 Hz), 6.53 (d, 1H,
J = 3.0 Hz), 3.67 (s, 2H, CH2-N), 2.41 (br s, 4H, CH2-N), 1.70 (br s,
4H, CH2). 13C NMR (60 MHz, d ppm, CDCl3): 145.3, 142.0, 140.2,
132.9, 131.6, 130.9, 128.1, 116.4, 114.6, 56.5 (CH2-N), 53.6 (CH2-
N), 23.4 (CH2). Anal. Calcd for C17H19ClN2: C, 71.19; H, 6.68; N,
9.77. Found: C, 71.24; H, 6.64; N, 9.80.
m
cmꢀ1): 3525, 3400 (st. N–H). 1H NMR
(400 MHz, d ppm, DMSO-d6): 8.72 (d, 1H, J = 9.5 Hz), 8.52 (d, 1H,
J = 7.4 Hz), 8.05 (d, 1H, J = 2.2 Hz), 7.94 (d, 1H, J = 8.1 Hz), 7.85 (d,
1H, J = 9.5 Hz), 7.62 (dd, 1H, J = 7.0 Hz, J = 2.2 Hz), 7.40–7.55 (m,
6H), 7.07 (d, 1H, J = 7.0 Hz), 4.38 (s, 2H, CH2-N), 2.49 (br s, 4H,
CH2-N), 1.80 (br s, 4H, CH2). 13C NMR (60 MHz, d ppm, DMSO-
d6): 155.0, 145.0, 144.6, 139.9, 139.2, 139.0, 138.7, 132.9, 129.8,
129.5, 128.8, 128.2, 127.9, 126.9, 126.4, 124.6, 120.2, 116.8,
101.5, 54.1 (CH2-N), 53.8 (CH2-N), 22.6 (CH2). Anal. Calcd (dihy-
drochloride salt) for C26H26Cl3N3: C, 64.14; H, 5.38; N, 8.63.
Found: C, 64.23; H, 5.44; N, 8.57.
4.1.5. General procedure for the preparation of 4-amino-
quinolines 11a–h
To a solution of 4,7-dichloroquinoline (1 mmol) in ethanol
(20 mL) was added concentrated hydrochloric acid (1 equiv), fol-
lowed by the corresponding aniline (10a–h) (1 mmol) previously
dissolved in ethanol (10 mL). The reaction mixture was heated
under reflux with continuous stirring for 6 h. The mixture was then
cooled at room temperature and the precipitated solid was fil-
trated, washed with ethanol and dried under vacuo to yield the
desired quinolines 11a–h as their practically pure dihydrochloride
salts.
4.1.5.5.
methyl)-[1,10-biphenyl]-3-yl)quinolin-4-amine dihydrochloride
11e. Orange solid, 38%, mp 238–240 °C. IR (KBr,
cmꢀ1): 3448
7-Chloro-N-(40-chloro-6-((4-methylpiperazin-1-yl)
m
(est. N–H). 1H NMR (400 MHz, d ppm, DMSO-d6): 11.27 (s, 1H),
8.90 (d, 1H, J = 6.4 Hz), 8.56 (d, 1H, J = 8.6 Hz), 8.16 (d, 1H,
J = 1.8 Hz), 7.90 (dd, 1H, J = 1.8 Hz, J = 9.5 Hz), 7.51–760 (m, 6H),
7.42 (d, 1H, J = 1.5 Hz), 7.02 (d, 1H, J = 7.4 Hz), 3.51 (s, 2H, CH2-
N), 2.75 (m, 8H, CH2-N), 2.09 (s, 3H, N-CH3). 13C NMR (100 MHz,
d ppm, DMSO-d6): 155.3, 144.1, 143.5, 139.5, 139.2, 138.6, 137.3,
133.3, 132.9, 131.8, 129.2, 129.0, 128.2, 126.9, 126.6, 124.7,
119.8, 116.7, 101.3, 52.2 (CH2-N), 49.0 (CH2-N), 42.6 (CH2-N),
31.2 (N-CH3). Anal. Calcd (dihydrochloride salt) for C27H28Cl4N4:
C, 58.93; H, 5.13; N, 10.18. Found: C, 58.99; H, 5.09; N, 10.25.
4.1.5.1. 7-Chloro-N-(6-((diethylamino)methyl)-[1,10-biphenyl]-
3-yl)quinolin-4-amine monohydrochloride 11a. In this case,
concentrated HCl was added as a catalyst (1 drop). Beige solid,
82%, mp 198–200 °C. IR (KBr,
m
cmꢀ1): 3342 (st. N–H). 1H NMR
(400 MHz, d ppm, DMSO-d6): 9.11 (s, 1H, N–H), 8.44 (d, 1H, H2,
J = 5.5 Hz), 8.38 (d, 1H, H6, J = 9.2 Hz), 7.88 (d, 1H, H8, J = 2.2 Hz),
7.58 (d, 1H, H5, J = 8.4 Hz), 7.53 (dd, 1H, J = 8.8 Hz, J = 2.2 Hz),
7.34–7.43 (m, 6H), 7.15 (d, 1H, J = 2.2 Hz), 7.01 (d, 1H, J = 5.5 Hz),
3.43 (s, 2H, CH2-N), 2.34 (q, 4H, CH2-N), 0.82 (t, 6H, CH3). 13C
NMR (100 MHz, d ppm, DMSO-d6): 151.5, 149.8, 148.7, 143.4,
141.0, 138.7, 134.7, 133.5, 131.4, 129.7, 128.7, 127.8, 127.7,
125.7, 124.9, 124.0, 121.7, 118.8, 102.3, 54.2 (CH2-N), 46.6 (CH2-
N), 11.9 (CH3). Anal. Calcd (monohydrochloride salt) for
4.1.5.6.
biphenyl]-3-yl)quinolin-4-amine dihydrochloride 11f. Yellow
solid, 84%, mp 260 °C decomp. IR (KBr,
cmꢀ1): 3441 (st. N–H).
7-Chloro-N-(40-chloro-6-(piperidin-1-ylmethyl)-[1,10-
m
1H NMR (270 MHz, d ppm, DMSO-d6): 8.42 (d, 1H, J = 8.8 Hz),
8.30 (d, 1H, J = 7.0 Hz), 7.91 (s, 1H), 7.74 (d, 1H, J = 8.2 Hz), 7.70
(d, 1H, J = 9.2 Hz), 7.54 (dd, 1H, J = 1.8 Hz, J = 8.2 Hz), 7.48 (d, 2H,
J = 7.7 Hz), 7.33 (m, 3H), 7.03 (d, 1H, J = 7.0 Hz), 4.27 (s, 2H, CH2-
N), 2.66 (m, 4H, CH2-N), 1.82 (br s, 4H, CH2), 1.66 (br s, 2H, CH2).
13C NMR (100 MHz, d ppm, DMSO-d6): 155.2, 144.7, 143.7, 139.9,
139.2, 138.4, 137.5, 133.9, 133.6, 131.5, 129.4, 128.5, 126.8,
126.1, 125.4, 124.9, 119.8, 101.3, 55.4 (CH2-N), 52.9 (CH2-N), 22.5
(CH2), 21.2 (CH2). Anal. Calcd (dihydrochloride salt) for
C26H28Cl3N3: C, 69.03; H, 6.02; N, 9.29. Found: C, 69.12; H, 6.09;
N, 9.35.
4.1.5.2. 7-Chloro-N-(6-(piperidin-1-ylmethyl)-[1,10-biphenyl]-3-
yl)quinolin-4-amine dihydrochloride 11b. Yellow solid, 90%,
mp 252–254 °C. IR (KBr,
m
cmꢀ1): 3524, 3446 (st. N–H). 1H NMR
(400 MHz, d ppm, DMSO-d6): 8.77 (d, 1H, J = 8.8 Hz), 8.54 (d, 1H,
C27H27Cl4N3: C, 60.58; H, 5.08; N, 7.85. Found: C, 60.49; H, 5.03;
J = 6.8 Hz), 8.10 (d, 1H, J = 1.8 Hz), 8.06 (d, 1H, J = 8.4 Hz), 7.85 (d,
N, 7.91.

A. H. Romero et al. / Bioorg. Med. Chem. 23 (2015) 4755–4762
4761
4.1.5.7.
biphenyl]-3-yl)quinolin-4-amine dihydrochloride 11g. Yellow
solid, 86%, mp 224–226 °C. IR (KBr,
cmꢀ1): 3438 (st. N–H). 1H
7-Chloro-N-(40-chloro-6-(morpholinomethyl)-[1,10-
counted by examination of Giemsa stained smears. Chloroquine
(25 mgꢂkgꢀ1) was used as a positive control. The survival time
beyond the control group (saline treated) was recorded. The results
were expressed as percentage of parasitemia (% of parasitemia)
and survival days of each compound treated-group over the con-
trol (saline treated group).34
m
NMR (400 MHz, d ppm, DMSO-d6): 11.02 (br s, 1H), 8.72 (d, 1H,
J = 9.2 Hz), 8.51 (d, 1H, J = 6.6 Hz), 8.07 (d, 1H, J = 1.8 Hz), 7.98 (d,
1H, J = 8.4 Hz), 7.88 (d, 1H, J = 9.2 Hz), 7.63 (d, 1H, J = 9.2 Hz),
7.56 (d, 2H, J = 8.4 Hz), 7.47 (d, 2H, J = 8.1 Hz), 7.44 (d, 1H,
J = 6.9 Hz), 7.07 (d, 1H, J = 6.9 Hz), 4.20 (s, 2H, CH2-N), 3.79 (br s,
4H, CH2-O), 2.90 (br s, 4H, CH2-N). 13C NMR (100 MHz, d ppm,
DMSO-d6): 155.2, 144.6, 144.3, 139.5, 139.4, 138.6, 137.8, 133.9,
133.7, 131.8, 129.4, 128.3, 126.9, 126.3, 126.1, 124.9, 119.9,
116.7, 101.5, 63.6 (CH2-O), 51.6 (CH2-N), 40.0 (CH2-N). Anal.
Calcd (dihydrochloride) for C26H25Cl4N3O: C, 58.12; H, 4.69; N,
7.82. Found: C, 58.21; H, 4.62; N, 7.88.
4.2.4. Data analysis
Data were statistically analyzed using one-way ANOVA and t-
tests for specific group comparisons; assuming 95% of confidence
according to GraphPad Prism 3.02.
Acknowledgements
S.L. and J.S. thanks Decanato de Investigacion y Desarrollo (DID,
Universidad Simon Bolivar), for its financial support and Lic
Noelani Ciguela for her help in the NMR spectra. A.R. thanks
Decanato de Estudios de Postgrado, Departamento de Quimica
4.1.5.8. 7-Chloro-N-(40-chloro-6-(pyrrolidin-1-ylmethyl)-[1,10-
biphenyl]-3-yl)quinolin-4-amine dihydrochloride 11h. Yellow
solid, 72%, mp 250–251 °C. IR (KBr,
m
cmꢀ1): 3436 (st. N–H). 1H
NMR (270 MHz, d ppm, DMSO-d6): 8.91 (d, 1H, J = 8.8 Hz), 8.57
(d, 1H, J = 6.6 Hz), 8.20 (d, 1H, J = 8.1 Hz), 8.18 (d, 1H, J = 1.8 Hz),
7.84 (d, 1H, J = 9.2 Hz, J = 1.8 Hz), 7.64 (d, 1H, J = 8.2 Hz,
J = 1.8 Hz), 7.57 (d, 2H, J = 8.4 Hz), 7.48 (d, 2H, J = 8.4 Hz), 7.45 (d,
1H, J = 6.6 Hz), 7.07 (d, 1H, J = 6.6 Hz), 4.36 (s, 2H, CH2-N), 2.76
(br s, 4H, CH2-N), 1.84 (br s, 4H, CH2). 13C NMR (100 MHz, d ppm,
DMSO-d6): 154.9, 144.4, 143.3, 138.9, 138.3, 138.1, 133.6, 132.8,
132.3, 131.8, 129.3, 129.1, 128.3, 128.0, 126.9, 124.8, 120.1,
116.9, 101.5, 54.0 (CH2-N), 53.5 (CH2-N), 22.9 (CH2). Anal. Calcd
(dihydrochloride salt) for C26H25Cl4N3: C, 59.90; H, 4.83; N, 8.06.
Found: C, 59.97; H, 4.87; N, 8.12.
(Universidad Simon Bolivar) for
a Doctoral Fellowship and
Laboratorio de RMN (Facultad de Farmacia, UCV, Caracas) for its
help in collecting the NMR spectral data.
Supplementary data
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.bmc.2015.05.040.
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