Design, synthesis and antiplasmodial activity of novel imidazole derivatives based on 7-chloro-4-aminoquinoline

Article abstract of DOI:10.1016/j.bioorg.2018.06.012

A series of short chain 4-aminoquinoline-imidazole derivatives have been synthesized in one pot two step multicomponent reaction using van leusen standard protocol. The diethylamine function of chloroquine is replaced by substituted imidazole derivatives containing tertiary terminal nitrogen. All the synthesized compounds were screened against the chloroquine sensitive (3D7) and chloroquine resistant (K1) strains of Plasmodium falciparum. Some of the compounds (6, 8, 9 and 17) in the series exhibited comparable activity to CQ against K1 strain of P. falciparum. All the compounds displayed resistance factor between 0.09 and 4.57 as against 51 for CQ. Further, these analogues were found to form a strong complex with hematin and inhibit the β-hematin formation, therefore these compounds act via heme polymerization target.

Full text of DOI:10.1016/j.bioorg.2018.06.012

Accepted Manuscript
Design, Synthesis and Antiplasmodial activity of novel imidazole derivatives
based on 7-chloro-4-aminoquinoline
Srinivasarao Kondaparla, Ashan Manhas, Vasantha Rao Dola, Kumkum
Srivastava, Sunil K. Puri, S.B. Katti
PII:
S0045-2068(18)30239-6
DOI:
https://doi.org/10.1016/j.bioorg.2018.06.012
YBIOO 2392
Reference:
To appear in:
Bioorganic Chemistry
Received Date:
Revised Date:
Accepted Date:
9 March 2018
3 June 2018
4 June 2018
Please cite this article as: S. Kondaparla, A. Manhas, V. Rao Dola, K. Srivastava, S.K. Puri, S.B. Katti, Design,
Synthesis and Antiplasmodial activity of novel imidazole derivatives based on 7-chloro-4-aminoquinoline,
Bioorganic Chemistry (2018), doi: https://doi.org/10.1016/j.bioorg.2018.06.012
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Design, Synthesis and Antiplasmodial activity of novel imidazole
derivatives based on 7-chloro-4-aminoquinoline.
a
b
a
b
Srinivasarao Kondaparla *, Ashan Manhas , Vasantha Rao Dola ,Kumkum Srivastava ,
b
a
Sunil K. Puri , S. B. Katti
a
Medicinal & Process Chemistry Division, CSIR-Central Drug Research Institute Sector-10, Jankipuram
Extension, Sitapur Road, Lucknow -226031.
b
Parasitology Division, CSIR-Central Drug Research Institute, Sector-10, Jankipuram Extension, Sitapur Road,
Lucknow-226031, India.
Keywords: 4-Aminoquinoline; Antiplasmodial activity; Heme binding; Chloroquine;
Plasmodium falciparum; β-hematin; in vitro; Chloroquine sensitive strain; Chloroquine
resistant strain.
Abbreviations:
CQ,
chloroquine;
DMF,
dimethylformamide;
TOSMIC,
Toluenesulfonylmethyl isocyanide
Corresponding author; Tel: +91-08674-259287, Fax; +91-522-2771941
Email address; srinu086@gmail.com (Srinivasarao Kondaparla*)

Abstract:
A series of short chain 4-aminoquinoline-imidazole derivatives have been synthesized
in one pot two step multicomponent reaction using van leusen standard protocol. The
diethylamine function of chloroquine is replaced by substituted imidazole derivatives
containing tertiary terminal nitrogen. All the synthesized compounds were screened against
the chloroquine sensitive (3D7) and chloroquine resistant (K1) strains of Plasmodium
falciparum. Some of the compounds (6, 8, 9 and 17) in the series exhibited comparable
activity to CQ against K1 strain of P. falciparum. All the compounds displayed resistance
factor between 0.09 and 4.57 as against 51 for CQ. Further, these analogues were found to
form a strong complex with hematin and inhibit the β-hematin formation, therefore these
compounds act via heme polymerization target.

1
. Introduction
Malaria still remains a serious health problem to human beings around the world,
mostly sub-Saharan African countries are at much higher risk [1]. As per WHO report 3.2
billion people remain at risk of malaria. In 2015 alone, there were an estimated 212 million
new cases of malaria and 429, 000 deaths. Most among them are children younger than 5
years [2]. Among the protozoan parasites (P. falciparum, vivax, ovale, malariae and
knowlesi) of the genus Plasmodium, P. falciparum is the most prevalent and virulent in
human, and contributes maximum number of deaths compared to other Plasmodium species
[
3]. Over the last 60 years the use of quinine has declined owing to the development of
synthetic 4-aminoquinolines such as chloroquine (CQ) (Figure 1). Among several quinoline
based antimalarials, CQ is the most effective and widely used drug in malaria chemotherapy
because of its rapid onset of action, good tolerability and low cost [4]. However, emergence
and wide-spread of drug resistance to CQ and many other drugs, including primaquine,
pyrimethamine and mefloquine (Figure 1) has increased the burden of mortality rate quite
abnormally in the last few years [5]. So, there is an urgent need of new chemical entities
active against drug resistant parasites. However, despite emergence of drug resistance CQ
scaffold still could be a good choice for further chemical modifications, owing to its excellent
efficacy, limited host toxicity and affordability [6]. Subsequently, literature survey on 4-
aminoquinolines clearly suggested that antimalarial activity, particularly inhibition of β-
hematin formation and accumulation of the drug at the target site, resides in 4-
aminoquinoline core [7]. Accordingly, a number of new 4-aminoquinoline analogues with
enhanced activity against CQ-R strain have been developed by conducting synthetic
modification of the CQ side chain [8-9]. However, in recent years various strategies have
been employed to circumvent the drug resistant. The 4-aminoquinoline hybridization is one
quite attractive strategy which has been recently introduced in the medicinal chemistry and

drug discovery process [10-11]. Moreover, chemotherapeutic agents derived from Schiff’s
base have occupied a unique place in the field of medicinal chemistry [12]. Further,
incorporation of bioactive functionalities in the side chain of 4-aminoquinoline emerged as
promising strategies to construct the molecules with enhanced activity against drug-resistant
P. falciparum and also with improved metabolic stability [13]. Recently, Campiani et al.
synthesized Clotrimazole (CLT) analogues [14] and subsequently prepared hybrid of the 4-
aminoquinoline with the clotrimazole-like pharmacophore [15] in which imidazole ring of
CLT behaves as a Fe(III) axial ligand and inhibit β-hematin formation and reported
promising in vitro (against both sensitive and resistant strain) and in vivo antimalarial
activities. On the other hand, various imidazole-based compounds have shown good
coordination properties and are able to form stable complexes with several metal ions
inhibitors [13].
Previously from our laboratory we introduced biologically privileged thiazolidine-4-
one ring system in the side chain in order to enhance the lipophilicity (Fig. 2, a). These
analogues showed remarkable activity against CQ-sensitive strain (NF-54) of P. falciparum
in vitro and CQ-resistant strain (N-67) of P. yoelii in vivo [16]. Later, we reported the
synthesis of chiral chloroquine and its analogues by incorporating different acyclic/cyclic
amines in the side chain of CQ (Fig. 2, a). These chiral chloroquine analouges exhibited
superior activity against both in vitro (3D7 & K1 strains) and in vivo (N-67 strain) studies
[
17]. Encouraged by these results, we envisaged that incorporation of biological privileged
motif such as imidazole (with ability to coordinate with the heme) in the side chain of 4-
aminoquinoline pharmacophore would lead to develop the new antimalarial agents active
against CQ-R strain of P. falciparum. Based on the above fact and in the continuation of our
ongoing antimalarial programme, herein we report the one-pot two step efficient synthesis of
4
-aminoquinoline analogues (Fig. 2, b) containing imidazole nucleus at lateral part of the

side chain and there evaluation as potentially active compounds against Plasmodium malaria
parasite. Results are discussed in the present communication.
2
2
. Results and Discussion
.1 Chemistry
The designed compounds (5-22) were synthesized via a two step simple and efficient
synthetic protocol. The detailed synthetic route for the synthesis of intermediate 4 and target
compounds (5-22) is outlined in Scheme-1. Initially, treatment of 4, 7-dichloroquinoline with
1
excess of ethylenediamine under solvent free conditions furnished the corresponding N -(7-
chloroquinolin-4-yl)ethane-1,2-diamine (4) in quantitative yield. Further, intermediate 4 was
utilized as amine input in TOSMIC (Toulene sulfonyl methyl isocyanide) based multi-
1
component cyclisation reaction. Further, condensation of aldehyde with N -(7-
chloroquinolin-4-yl)ethane-1,2-diamine give aldimine followed by TOSMIC induced base
°
(
K
2
CO
3
) catalysed cyclisation in DMF at 90 C afforded the target compounds (5-22) in good
1
13
yield. All final compounds (5-22) were characterized by H NMR, C NMR, Mass and
HRMS respectively.
2
.2 Antiplasmodial (P. falciparum) Activity
A novel series of 4-aminoquinoline-imidazole derivatives (5-22) were synthesized
and examined for in vitro antiplasmodial activity against both CQ-sensitive (3D7) and CQ-
resistant (K1) strains of Plasmodium falciparum. The results are shown in Table-1. All the
compounds exhibited moderate to higher activity with IC50 values ranging from 0.079±0.015
-
5±0.048 µM against CQ-S strain and 0.291±0.018- 5±0.047 µM against CQ-R strain of P.
falciparum.
The structure activity relationship (SAR) studies on these compounds clearly suggest
that the activity of these compounds is greatly influenced by the type of substitution present
on the imidazole ring. The activity data of our compounds suggest that the type of

substitution present on the phenyl ring attached to imidazole markedly influenced the activity
of 4-aminoquinoline imidazole derivatives (Figure 3). According to our results, compounds
(
5, 6, 7, 11 and 14) with heterocyclic core attached to imidazole had very mild effect on the
inhibition of parasite growth against CQ-R strain with IC50 values 1.15±0.028, 0.46±0.048,
1
0
.70±0.024, 1.33±0.029 and 0.97±0.025 µM respectively, among them compound 6 (IC50
=
.46±0.048 µM) exhibited comparable activity to CQ (IC50 = 0.255±0.049 µM) against CQ-R
strain of P. falciparum. Moreover, compounds 12 and 20 (IC50 values 2.62±0.025 and
.92±0.031 µM) with phenoxyl and naphthalene substituents on imidazole moiety were found
0
to be inactive against both the strains (3D7 & K1) of P. falciparum. This result clearly
suggests that bulky aromatic substituents are not suitable on imidazole moiety. However, the
activity of compounds was greatly influenced by the type of substitution present on the
phenyl
ring
attached
to
N-(2-(1H-imidazol-1-yl)ethyl)-7-chloroquinolin-4-amine
pharmacophore. Compounds containing electron withdrawing groups had much better
activity against CQ-R strain as compared to those containing electron donating groups. On
that account, among the synthesized compounds in the series, compounds 8 and 15 with
electron withdrawing group showed better inhibition effect against CQ-R strain compared to
compounds 10, 16, 19 and 22 which were bearing electron donating group as on phenyl ring.
Interestingly, cyclopentyl and cyclohexyl substitutions on N-(2-(1H-imidazol-1-yl)ethyl)-7-
chloroquinolin-4-amine moiety markedly affected the activity profile against both the strains
(
3D7 & K1) of P. falciparum. Consequently, compound 17 with cyclopentyl substitution
exhibited much better activity against K1 strain with IC50 value 0.34±0.011 µM, than
compound 21(IC50 = 0.52±0.029 µM) which is having cyclohexyl substitution. Moreover,
compound 17 also showed comparable activity to CQ (IC50 = 0.255±0.049 µM) against K1
strain. This activity may be due to presence of planar hydrophobic motif in the side chain.
Furthermore, despite various substitutions on phenyl ring (Table-1) isopropyl group bearing

compound 9 was found to be most active in the series against K1 strain with IC50 0.29±0.018
µM, which was shown all most equal potency with CQ (IC50 = 0.255 ±0.049 µM).
Furthermore, Compound 13 having tert-butyl group substitution on N-(2-(1H-imidazol-1-
yl)ethyl)-7-chloroquinolin-4-amine pharmacophore showed significant activity with IC50
.50±0.023 µM against K1 strain of P. falciparum. From the overall results, it is clear that
alkyl groups and alkyl substituted phenyl rings are most favourable for the substitution on N-
2-(1H-imidazol-1-yl)ethyl)-7-chloroquinolin-4-amine pharmacophore, which would lead to
=
0
(
compounds having better antimalarial activity against both strains and ultimately opens up a
novel strategy to circumvent the drug resistance parasites of P. falciparum.
2
.3 In vitro cytotoxicity
The cytotoxicity of all the synthesized compounds 5-22 was determined against
VERO cell line using MTT assay (Table-1). 14 compounds in the series showed considerable
selectivity index (SI) ranging between 26.12 and 203.82, rest of molecules namely 6, 7, 11,
1
2, 16 and 21 showed selectivity index values as >431.03, >117.64, >150.37, >76.33,
112.29 and >383.14 respectively. Compounds 8 and 17 which were exhibited comparable
>
potency against K1 strain also showed good selectivity index 79.54 and 203.82 respectively.
Compound 9 which was most potent against resistant strain K1, also showed good selectivity
index of >687.2. In the series few compounds exhibited reasonably promising activity against
K1 strain, less cytotoxic effect with fairly high selectivity index, and consequently these 4-
aminoquinoline imidazole derivatives are promising candidate for further lead optimization.
2
.4 In vitro Inhibition of β-hematin Polymerization
The mode of action of new series of 4-aminoquinoline-imidazole derivatives 5-22 was
investigated by the reported method [18] and the results are shown in (Table 1). Heme
binding assay results confirm that all the synthesized compounds interact with the heme.
However, compounds 8 and 14 formed strong complex with hematin and log K was found to

be 5.93 and 5.71 respectively. Remaining compounds in the series exhibited the association
constants values in the range 5.71-8.73. These results are concurrent with the previous results
from our laboratory [19-20] as well as reported literature evidences [21]. These results
indicate that, there might be a π-π stacking interaction between quinoline ring and porphyrin
ring system.
All the synthesized side chain modified 4-aminoquinoline-imidazole derivatives 5-22
inhibited the β-hematin formation in a concentration dependent manner (Table 1). However
most of the new series of 4-aminoquinoline-imidazole derivatives were good inhibitors of β-
hematin formation. It is reported that there was no linear correlation between inhibition of β-
hematin formation and antiplasmodial activity [16]. As reported, some of our compounds
showed moderate antiplasmodial activity against CQ-S and CQ-R strains of P. falciparum,
but showed better affect on inhibition of hemozoin formation (Table 1). In this present study
most potent inhibitor was compound 9 with an IC50 of 0.42 µM in the hemozoin inhibition
assay, and also showed comparable activity to CQ against CQ-R strain. These results
highlighted the importance of hydrophobic substitution. So, we conclude that this class of
compounds act on heme polymerization target.
3
. Conclusion
In conclusion, we have synthesized novel imidazole derivatives of 4-aminoquinoline
by utilizing highly efficient van leusen multicomponent synthetic protocol. A few compounds
in the series exhibited moderate antiplasmodial activity against CQ-R strain of P. falciparum,
and also most of the compounds show fairly high selectivity index. In the present study,
substitutions on N-(2-(1H-imidazol-1-yl)ethyl)-7-chloroquinolin-4-amine moiety has greatly
influenced the antiplasmodial activity. Overall results clearly highlight the importance of
alkyl substituents on phenyl ring as well as hydrophobic substitutions on N-(2-(1H-imidazol-
1
-yl)ethyl)-7-chloroquinolin-4-amine pharmacophore.

4
4
. Materials and Methods
.1 General Information
Melting points (mp) were taken in open capillaries on Complab melting point
1
13
apparatus and are uncorrected. The H NMR (400 MHz) and C NMR (100 MHz) spectra
were recorded in CDCl , CD OD and DMSO-d solvents on DPX-400 Bruker FT-NMR
3
3
6
spectrometer. All chemical shifts (δ) are reported in parts per million (ppm) downfield from
tetramethylsilane. The splitting pattern abbreviations are as follows: s (singlet), d (doublet),
dd (doublet of doublet), t (triplet), and m (multiplet). Coupling constants are given in hertz.
Mass Spectra (ESI-MS), high resolution mass spectra HRMS (ESI-HRMS) were recorded on
Jeol (Japan)/SX-102, Agilent 6520 Q-Tof (ESI-HRMS) spectrometers respectively.
Analytical thin-layer chromatography (TLC) was carried out on Merck’s pre-coated silica-gel
plates 60 F254 and spots were visualized by irradiation with UV light (254 nm). Iodine was
used as developing agent and/or by spraying with Dragendorff’s reagent. Column
chromatographic purification was performed over neutral alumina and (silica gel 60-120,
1
00-200 and 230-400 mesh) using a gradient solvent system (n-hexane/EtoAc, DCM/Hexane
or chloroform/methanol as the eluent unless otherwise specified). All chemicals and reagents
were obtained from Aldrich (USA), Lancaster (UK) and Spectrochem Pvt. Ltd (India) and
were used without further purification.
1
4
.2.
diamine (4)
A mixture of 4,7-dichloroquinoline (1 equiv.) and 1,2-diaminoethane (5 equiv.) was
General procedure for the synthesis of N -(7-Chloroquinolin-4-yl)ethane-1,2-
heated slowly from room temperature to 80°C over 1 h with stirring and subsequently at 120–
30°C for 6-8 h with continued stirring to drive the reaction to completion. The reaction
mixture was cooled to room temperature and taken up in dichloromethane. The organic layer
was successively washed with 5% aq NaHCO followed by water wash and then finally with
brine. The organic layer was dried over anhydrous Na SO and solvent was removed under
1
3
2
4

reduced pressure and the residue was precipitated by the addition of 80:20 hexane–
chloroform.
1
Compound 4 was obtained as yellow solid in 85% yield; m.p. 131-132°C; H NMR (400
MHz, CDCl
3
): δ 3.10-3.16 (m, 2H, NHCH
2
CH
2
NH
2
), 3.30-3.45 (m, 2H, NHCH
2
CH
2
NH ),
2
4
.73 (br s, 2H, NHCH
2
CH NH ), 5.87 (br s, 1H, NHCH
2
2
2
CH NH ), 6.40 (d, J = 5.4 Hz, 1H,
2
2
Ar-H quinoline), 7.67 (d, J = 9.0 Hz, 1H, Ar-H quinoline), 7.70 (d, J = 2.1 Hz, 1H, Ar-H
quinoline), 7.95-7.99 (dd, J = 2.1, 8.1 Hz, 1H, Ar-H quinoline), 8.50 (d, J = 5.1 Hz, 1H, Ar-H
+
quinoline); ESI-MS: (m/z) 222.3 (M+H) .
4
.3 General procedure for the synthesis of (5-22)
Aldehyde (1 equiv. 0.48 mmol) and amine (1 equiv. 0.48 mmol) were dissolved in
DMF (10 mL) and heat the reaction mixture at 90°C for 6-8h. Then Potassium carbonate (2
equiv. 0.96 mmol) and TOSMIC (1 equiv. 0.48 mmol) were added to the reaction mixture,
continue stirring at 90°C for 12h. The Completion of the reaction was monitored by TLC,
then cool the reaction mixture to room temperature, then add 20 mL water and extract with
EtOAc (3 X 20 mL). The organic phase was dried over Na
2
SO and concentrated under
4
reduced pressure. Then obtained crude was purified by column chromatography using 60-120
mesh in Methanol/Chloroform as eluent, afforded the title compounds.
4
.3.1 N-(2-(5-(1H-Pyrrol-2-yl)-1H-imidazol-1-yl)ethyl)-7-chloroquinolin-4-amine (5)
1
Compound 5 was obtained as pale yellow solid in 76% yield; m.p. 168-170°C; H NMR (400
MHz, CD
3
OD): δ 3.62-3.66 (m, 2H, NHCH
2
CH
2
N), 4.41 (t, J = 6.2 Hz, 2H, NHCH
2
CH N),
2
6
1
7
.20-6.21 (m, 1H, Ar-H pyrrole), 6.28 (d, J = 1.4 Hz, 1H, Ar-H pyrrole), 6.29 (d, J = 1.4 Hz,
H, Ar-H quinoline), 6.83-6.84 (m, 1H, Ar-H pyrrole), 7.00 (d, J = 1.0 Hz, 1H, Ar-H Imd),
.37-7.40 (dd, J = 2.1, 9.0 Hz, 1H, Ar-H quinoline), 7.63 (d, J = 0.8 Hz, 1H, Ar-H Imd), 7.77
(
d, J = 2.0 Hz, 1H, Ar-H quinoline), 7.91 (d, J = 9.0 Hz, 1H, Ar-H quinoline), 8.27 (d, J = 5.6
1
3
Hz, 1H, Ar-H quinoline); C NMR (100 MHz, CD OD): δ 42.5, 43.5, 98.0, 108.2, 108.5,
3

1
17.2, 118.9, 119.0, 122.7, 124.8, 126.0, 126.1, 126.6, 135.0, 137.9, 148.0, 150.8; ESI-MS:
+
+
(
m/z): 338.2 (M+H) ; HRMS calcd for [C18
H
16ClN +H] 338.1167, found 338.1177.
5
4
.3.2
7-Chloro-N-(2-(5-(3-methylthiophen-2-yl)-1H-imidazol-1-yl)ethyl)quinolin-4-
amine (6)
1
Compound 6 was obtained as yellow solid in 78% yield; m.p. 172-174°C; H NMR (400
MHz, CDCl
3
): δ 2.08 (s, 3H, CH
3
-thiophene), 3.56 (d, J = 5.4 Hz, 2H, NHCH
2
CH
2
N), 4.21
(
t, J = 6.1 Hz, 2H, NHCH
2
CH N), 6.07 (d, J = 5.4 Hz, 1H, Ar-H quinoline), 6.93 (d, J = 5.2
2
Hz, 1H, Ar-H thiophene), 7.07 (s, 1H, Ar-H Imd), 7.27-7.30 (dd, J = 2.1, 8.9 Hz, 1H, Ar-H
quinoline), 7.32 (d, J = 5.1 Hz, 1H, Ar-H thiophene), 7.52 (s, 1H, Ar-H Imd), 7.66 (d, J = 9.0
Hz, 1H, Ar-H quinoline), 7.92 (d, J = 2.0 Hz, 1H, Ar-H quinoline), 8.40 (d, J = 5.3 Hz, 1H,
1
3
Ar-H quinoline); C NMR (100 MHz, CDCl
3
): δ 14.5, 43.0, 43.4, 98.3, 117.4, 122.1, 123.0,
1
24.6, 125.4, 126.5, 128.1, 130.1, 130.6, 135.1, 138.4, 138.7, 148.9, 149.5, 151.5; ESI-MS:
+
+
(
m/z): 369.2 (M+H) ; HRMS calcd for [C19
H
17ClN S+H] 369.0935, found 369.0933.
4
4
.3.3 N-(2-(5-(1H-Indol-3-yl)-1H-imidazol-1-yl)ethyl)-7-chloroquinolin-4-amine (7)
1
Compound 7 was obtained as Pale yellow solid in 76% yield; m.p. 210-212°C; H NMR (400
MHz, CD
NHCH CH
.14 (m, 1H, Ar-H Ind), 7.21 (s, 1H, Ar-H Imd), 7.23-7.26 (dd, J = 2.1, 9.0 Hz, 1H, Ar-H
quinoline), 7.34 (d, J = 1.0 Hz, 1H, Ar-H quinoline); 7.36 (d, J = 0.9 Hz, 1H, Ar-H Ind), 7.67
d, J = 2.0 Hz, 1H, Ar-H quinoline); 7.72 (d, J = 9.0 Hz, 1H, Ar-H Ind), 7.79 (s, 1H, Ar-H
3
OD): δ 3.52 (t, J = 6.2 Hz, 2H, NHCH
2
CH
2
N), 4.34 (t, J = 6.3 Hz, 2H,
2
2
N), 6.97-6.98 (m, 1H, Ar-H Ind), 6.99 (d, J = 8.0 Hz, 1H, Ar-H quinoline), 7.11-
7
(
1
3
Imd), 7.88 (s, 1H, Ar-H Ind), 7.98 (d, J = 5.6 Hz, 1H, Ar-H quinoline); C NMR (100 MHz,
CD OD): δ 36.3, 43.0, 97.6, 103.1, 111.3, 117.0, 118.2, 119.7, 121.8, 122.5, 124.4, 124.6,
25.9, 126.8, 126.9, 127.1, 134.9, 136.3, 137.7, 147.7, 150.3, 150.5; ESI-MS: (m/z): 388.2
3
1
+
+
(
M+H) ; HRMS calcd for [C22
H
19ClN +H] 388.1323, found 388.1325.
5

4
.3.4 7-Chloro-N-(2-(5-(4-(trifluoromethyl)phenyl)-1H-imidazol-1-yl)ethyl)quinolin-4-
amine (8)
Compound 8 was obtained as Pale yellow solid in 71% yield; m.p. 187-189°C; H NMR (400
MHz, CD OD): δ 3.57 (t, J = 6.2 Hz, 2H, NHCH CH N), 4.80 (t, J = 6.3 Hz, 2H,
NHCH CH N), 6.58 (d, J = 5.1 Hz, 1H, Ar-H quinoline), 7.38 (s, 1H, Ar-H Imd), 7.39-7.41
dd, J = 2.1, 8.9 Hz, 1H, Ar-H quinoline), 7.44-7.54 (m, 4H, Ar-H Ph), 7.61 (d, J = 7.8 Hz,
H, Ar-H quinoline), 7.64 (s, 1H, Ar-H Imd), 7.79 (d, J = 4.7 Hz, 1H, Ar-H quinoline), 7.92
1
3
2
2
2
2
(
1
1
3
(
d, J = 8.5 Hz, 1H, Ar-H quinoline); C NMR (100 MHz, CD OD): δ 43.1, 43.2, 98.2, 117.1,
3
1
19 13
3
19 13
1
21.2, 121.9, 124.9, J( F, C) (q, JC-F = 272.9 Hz, CF ), 125.6, 125.9, J( F, C) (q, J = 7.8
3
4
19 13
2
19 13
Hz,), 128.0, J( F, C) (q, J = 3.5 Hz,), 128.6, 129.4, 130.7, J( F, C) (q, J = 33.1Hz, ipso),
+
1
35.4, 137.4, 137.7, 148.7, 149.6, 150.2, 151.1, 151.5; ESI-MS: (m/z): 417.2 (M+H) ;
+
HRMS calcd for [C21
H17ClF
3
N
4
+H] 417.1088, found 417.1087.
4
.3.5 7-Chloro-N-(2-(5-(4-isopropylphenyl)-1H-imidazol-1-yl)ethyl)quinolin-4-amine (9)
1
Compound 9 was obtained as yellow solid in 81% yield; m.p. 175-177°C; H NMR (400
MHz, CDCl ): δ 1.23 (d, J = 6.8 Hz, 6H, CH(CH ), 2.84-2.91 (sep, 1H, CH(CH ), 3.47 (t,
J = 9.5 Hz, 2H, NHCH CH N), 4.26 (t, J = 5.3 Hz, 2H, NHCH CH N), 5.95 (d, J = 4.9 Hz,
H, Ar-H quinoline), 6.96 (s, 1H, Ar-H Imd), 7.13-7.18 (m, 4H, Ar-H Ph), 7.24-7.30 (dd, J =
.1, 9.0 Hz, 1H, Ar-H quinoline), 7.44 (s, 1H, Ar-H Imd), 7.77 (d, J = 8.6 Hz, 1H, Ar-H
3
3
)
2
)
3 2
2
2
2
2
1
2
quinoline), 7.87 (d, J = 7.5 Hz, 1H, Ar-H quinoline), 8.26 (d, J = 5.0 Hz, 1H, Ar-H
1
3
quinoline); C NMR (100 MHz, CDCl
3
): δ 23.8, 33.7, 43.0, 43.6, 98.2, 117.3, 125.3, 126.2,
1
26.4, 126.9, 127.6, 129.0, 129.7, 133.4, 135.1, 137.9, 148.4, 149.3, 149.8, 151.0; ESI-MS:
+
+
(
m/z): 391.2 (M+H) ; HRMS calcd for [C23
H
24ClN +H] 391.1684, found 391.1669.
4

4
.3.6
amine (10)
Compound 10 was obtained as yellowish white solid in 70% yield; m.p. 192-194°C; H NMR
400 MHz, CDCl ): δ 2.99 (s, 6H, N(CH ), 3.53-3.57 (m, 2H, NHCH CH N), 4.33 (t, J =
.8 Hz, 2H, NHCH CH N), 6.05 (d, J = 5.4 Hz, 1H, Ar-H quinoline), 6.61-6.64 (m, 2H, Ar-H
Ph), 7.00 (s, 1H, Ar-H Imd), 7.14-7.16 (dd, J = 2.1, 6.7 Hz, 1H, Ar-H quinoline), 7.29-7.32
m, 2H, Ar-H Ph), 7.47 (d, J = 8.9 Hz, 1H, Ar-H quinoline), 7.51 (s, 1H, Ar-H Imd), 7.93 (d,
7-Chloro-N-(2-(5-(4-(dimethylamino)phenyl)-1H-imidazol-1-yl)ethyl)quinolin-4-
1
(
3
3
)
2
2
2
5
2
2
(
1
3
J = 2.1 Hz, 1H, Ar-H quinoline), 8.39 (d, J = 5.3 Hz, 1H, Ar-H quinoline); C NMR (100
MHz, CDCl
3
): δ 40.2, 42.8, 43.8, 98.5, 112.1, 116.2, 117.4, 122.0, 125.2, 127.2, 128.3, 130.0,
+
1
33.8, 134.9, 137.4, 149.0, 149.2, 150.2, 151.5; ESI-MS: (m/z): 392.2 (M+H) ; HRMS calcd
+
for [C22
H
23ClN +H] 392.1636, found 392.1638.
5
4
.3.7 7-Chloro-N-(2-(5-(quinolin-2-yl)-1H-imidazol-1-yl)ethyl)quinolin-4-amine (11)
1
Compound 11 was obtained as Pale yellow solid in 75% yield; m.p. 203-205°C; H NMR
(
400 MHz, CDCl
NHCH CH N), 6.31 (d, J = 5.0 Hz, 1H, Ar-H quinoline), 6.69 (d, J = 8.3 Hz, 1H, Ar-H
quinoline), 7.11 (s, 1H, Ar-H Imd), 7.19-9.21 (dd, J = 2.4, 8.3 Hz, 1H, Ar-H quinoline), 7.30
d, J = 8.9 Hz, 1H, Ar-H quinoline), 7.55 (d, J = 7.0 Hz, 1H, Ar-H quinoline), 7.60 (d, J = 7.7
Hz, 1H, Ar-H quinoline), 7.79 (s, 1H, Ar-H Imd), 7.84 (d, J = 7.8 Hz, 1H, Ar-H quinoline),
3
): δ 3.43-3.51 (m, 2H, NHCH
2
CH
2
N), 4.34 (t, J = 6.2 Hz, 2H,
2
2
(
7
.91 (d, J = 8.2 Hz, 1H, Ar-H quinoline), 7.98 (d, J = 2.4 Hz, 1H, Ar-H quinoline), 8.28 (d, J
1
3
=
6.4 Hz, 1H, Ar-H quinoline), 8.43 (d, J = 5.0 Hz, 1H, Ar-H quinoline); C NMR (100
): δ 44.7, 45.5, 98.2, 102.9, 116.7, 120.8, 122.3, 123.6, 124.9, 125.0, 126.1,
26.6, 127.2, 128.3, 128.7, 130.2, 135.5, 137.6, 144.8, 146.4, 147.8, 147.9, 149.1; ESI-MS:
MHz, CDCl
3
1
+
+
(
m/z): 400.2 (M+H) ; HRMS calcd for [C23
H
19ClN +H] 400.1323, found 400.1322.
5

4
.3.8 7-Chloro-N-(2-(5-(3-phenoxyphenyl)-1H-imidazol-1-yl)ethyl)quinolin-4-amine (12)
1
Compound 12 was obtained as Pale yellow solid in 66% yield; m.p. 182-184°C; H NMR
(
400 MHz, CDCl
NHCH CH N), 6.04 (d, J = 5.4 Hz, 1H, Ar-H quinoline), 6.87-6.94 (m, 5H, Ar-H Ph), 6.95-
.98 (dd, J = 2.0, 8.9 Hz, 1H, Ar-H quinoline), 6.98 (s, 1H, Ar-H Imd), 7.05-7.08 (m, 3H, Ar-
3
): δ 3.50-3.61 (m, 2H, NHCH
2
CH
2
N), 4.28 (t, J = 5.8 Hz, 2H,
2
2
6
H Ph), 7.19 (s, 1H, Ar-H Ph), 7.50 (s, 1H, Ar-H Imd), 7.69 (d, J = 8.8 Hz, 1H, Ar-H
quinoline), 7.87 (d, J = 2.0 Hz, 1H, Ar-H quinoline), 8.35 (d, J = 5.3 Hz, 1H, Ar-H
1
3
quinoline); C NMR (100 MHz, CDCl
3
): δ 43.2, 43.6, 98.3, 117.3, 118.0, 118.6, 119.2,
1
1
22.0, 123.3, 123.8, 125.3, 128.1, 128.4, 129.6, 129.9, 130.2, 130.7, 131.0, 135.0, 137.6,
+
38.5, 148.8, 149.4, 151.4, 156.3, 157.8; ESI-MS: (m/z): 441.2 (M+H) ; HRMS calcd for
+
[
C
26
H22ClN
4
O+H] 441.1477, found 441.1474.
4
.3.9 N-(2-(5-Tert-butyl-1H-imidazol-1-yl)ethyl)-7-chloroquinolin-4-amine (13)
1
Compound 13 was obtained as white solid in 73% yield; m.p. 166-168°C; H NMR (400
MHz, CDCl
3
): δ 1.38 (s, 9H, C(CH
3
)
3
), 3.77 (t, J = 6.1 Hz, 2H, NHCH
2
CH N), 4.39 (t, J =
2
6
7
7
.2 Hz, 2H, NHCH CH N), 6.41 (d, J = 5.5 Hz, 1H, Ar-H quinoline), 6.72 (s, 1H, Ar-H Imd),
2
2
.34-7.36 (dd, J = 2.0, 8.7 Hz, 1H, Ar-H quinoline), 7.41 (d, J = 6.7 Hz, 1H, Ar-H quinoline),
.44 (s, 1H, Ar-H Imd), 7.93 (d, J = 2.1 Hz, 1H, Ar-H quinoline), 8.41 (d, J = 8.2 Hz, 1H, Ar-
1
3
H quinoline); C NMR (100 MHz, CDCl
3
): δ 29.4, 30.3, 30.8, 43.7, 43.8, 44.8, 99.3, 117.8,
1
24.3, 124.8, 127.3, 127.8, 134.0, 139.3, 139.6, 149.3, 150.2, 152.3; ESI-MS: (m/z): 329.1
+
+
(
M+H) ; HRMS calcd for [C18
H
22ClN +H] 329.1528, found 329.1529.
4
4
.3.10 7-Chloro-N-(2-(5-(furan-2-yl)-1H-imidazol-1-yl)ethyl)quinolin-4-amine (14)
1
Compound 14 was obtained as white off solid in 65% yield; m.p. 173-175°C; H NMR (400
MHz, DMSO-d
NHCH CH N), 6.40 (d, J = 5.4 Hz, 1H, Ar-H quinoline), 6.51-6.52 (m, 1H, Ar-H furan),
.60-6.61 (m, 1H, Ar-H furan), 7.14 (d, J = 0.9 Hz, 1H, Ar-H Imd), 7.41-7.44 (dd, J = 2.2,
6
): δ 3.56-3.61 (m, 2H, NHCH
2
CH
2
N), 4.36 (t, J = 6.2 Hz, 2H,
2
2
6

9
.0 Hz, 1H, Ar-H quinoline), 7.66-7.67 (m, 1H, Ar-H furan), 7.75 (d, J = 2.2 Hz, 1H, Ar-H
quinoline), 8.11 (d, J = 9.0 Hz, 1H, Ar-H quinoline), 8.27 (s, 1H, Ar-H Imd), 8.34 (d, J = 5.4
1
3
Hz, 1H, Ar-H quinoline); C NMR (100 MHz, DMSO-d
6
): δ 43.1, 44.1, 99.1, 107.8, 111.9,
1
17.9, 123.7, 124.3, 124.7, 127.8, 128.6, 133.9, 140.0, 143.3, 144.4, 149.3, 150.2, 152.2;
+
+
ESI-MS: (m/z): 339.1 (M+H) ; HRMS calcd for [C18
H
16ClN O+H] 339.1007, found
4
3
39.1021.
4
.3.11. 4-(1-(2-(7-Chloroquinolin-4-ylamino)ethyl)-1H-imidazol-5-yl)benzonitrile (15)
1
Compound 15 was obtained as white solid in 77% yield; m.p. 159-161°C; H NMR (400
MHz, CDCl
.46 (d, J = 5.3 Hz, 1H, Ar-H quinoline), 7.28 (s, 1H, Ar-H Imd), 7.45-7.39 (m, 2H, Ar-H
Ph), 7.53-7.57 (dd, J = 2.0, 9.0 Hz, 1H, Ar-H quinoline), 7.61-7.63 (m, 2H, Ar-H Ph), 7.80 (s,
H, Ar-H Imd), 7.87 (d, J = 2.0 Hz, 1H, Ar-H quinoline), 7.92 (d, J = 8.5 Hz, 1H, Ar-H
3
): δ 3.91-3.96 (m, 2H, NHCH
2
CH
2
N), 4.32 (t, J = 5.6 Hz, 2H, NHCH
2
CH N),
2
6
1
1
3
quinoline), 7.99 (d, J = 2.0 Hz, 1H, Ar-H quinoline); C NMR (100 MHz, CDCl
3
): δ 43.7,
4
1
3
4
5.5, 98.9, 116.6, 120.7, 121.6, 123.1, 124.3, 124.6, 124.8, 125.0, 126.1, 127.5 128.9, 132.5,
+
+
38.1, 149.5, 151.2, 151.7; ESI-MS: (m/z): 374.2 (M+H) ; HRMS calcd for [C21
H
17ClN +H]
5
74.1167, found 374.1169.
.3.12
7-Chloro-N-(2-(5-(4-methoxyphenyl)-1H-imidazol-1-yl)ethyl)quinolin-4-
amine(16)
1
Compound 16 was obtained as Pale yellow solid in 68% yield; m.p. 160-162°C; H NMR
(
400 MHz, DMSO-d
J = 6.1 Hz, 2H, NHCH
Ar-H Ph), 7.22 (s, 1H, Ar-H Imd), 7.23 (d, J = 5.1 Hz, 1H, Ar-H quinoline), 7.32-7.33 (m,
6
): δ 3.45 (t, J = 6.4 Hz, 2H, NHCH
2
CH
2
N), 3.74 (s, 3H, OCH ), 4.23 (t,
3
2
CH N), 6.08 (d, J = 5.0 Hz, 1H, Ar-H quinoline), 6.82-6.84 (m, 2H,
2
2
8
H, Ar-H Ph), 7.36-7.39 (dd, J = 2.1, 9.2 Hz, 1H, Ar-H quinoline), 7.74 (s, 1H, Ar-H Imd),
1
3
.04 (d, J = 9.0 Hz, 1H, Ar-H quinoline), 8.23 (d, J = 5.2 Hz, 1H, Ar-H quinoline); C NMR
(
100 MHz, DMSO-d
6
): δ 42.9, 43.4, 55.4, 98.7, 114.3, 117.8, 122.1, 124.1, 124.5, 127.3,

+
1
27.8, 130.4, 132.7, 134.0, 138.7, 149.3, 150.0, 151.8, 159.3; ESI-MS: (m/z): 379.2 (M+H) ;
+
HRMS calcd for [C21
H20ClN
4
O+H] 379.1320, found 379.1320.
4
.3.13 7-Chloro-N-(2-(5-cyclopentyl-1H-imidazol-1-yl)ethyl)quinolin-4-amine (17)
1
Compound 17 was obtained as off white solid in 79% yield; m.p. 187-189°C; H NMR (400
MHz, CDCl ): δ 1.51-1.57 (m, 4H, cyclopentane), 1.72-1.76 (m, 2H, cyclopentane), 1.90-
.96 (m, 2H, cyclopentane), 2.77-2.85 (m, 1H, CH(CH ), 3.70-3.74 (m, 2H, NHCH CH N),
.20 (t, J = 5.3 Hz, 2H, NHCH CH N), 6.41 (d, J = 5.3 Hz, 1H, Ar-H quinoline), 6.77 (s, 1H,
3
1
4
2
)
4
2
2
2
2
Ar-H Imd), 7.26 (s, 1H, Ar-H Imd), 7.29-7.32 (dd, J = 2.1, 8.8 Hz, 1H, Ar-H quinoline), 7.72
d, J = 9.0 Hz, 1H, Ar-H quinoline), 7.95 (d, J = 2.1 Hz, 1H, Ar-H quinoline), 8.54 (d, J = 5.3
(
1
3
Hz, 1H, Ar-H quinoline); C NMR (100 MHz, CDCl
3
): δ 25.0, 32.9, 34.8, 42.6, 43.4, 98.4,
1
3
4
17.5, 122.2, 124.0, 125.4, 128.3, 135.1, 136.7, 136.8, 149.2, 149.6, 151.7; ESI-MS: (m/z):
+
+
41.2 (M+H) ; HRMS calcd for [C19
H22ClN
4
+H] 341.1528, found 341.1534.
.3.14 7-Chloro-N-(2-(5-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-1H-imidazol-1-
yl)ethyl)quinolin-4-amine (18)
Compound 18 was obtained as Pale yellow solid in 63% yield; m.p. 201-203°C; H NMR
400 MHz, CDCl ): δ 3.55 (t, J = 5.4 Hz, 2H, NHCH CH N), 4.22 (t, J = 4.7 Hz, 2H,
dioxane), 4.29 (t, J = 4.5 Hz, 2H, dioxane), 4.34 (t, J = 5.4 Hz, 2H, NHCH CH N), 6.09 (d, J
5.3 Hz, 1H, Ar-H quinoline), 6.68-6.72 (m, 3H, Ar-H Ph), 6.96 (s, 1H, Ar-H Imd), 7.29-
1
(
3
2
2
2
2
=
7
1
.32 (dd, J = 2.0, 8.8 Hz, 1H, Ar-H quinoline), 7.47 (s, 1H, Ar-H Imd), 7.53 (d, J = 8.9 Hz,
H, Ar-H quinoline), 7.92 (d, J = 1.7 Hz, 1H, Ar-H quinoline), 8.39 (d, J = 5.2 Hz, 1H, Ar-H
1
3
quinoline); C NMR (100 MHz, CDCl
3
): δ 42.3, 43.0, 63.8, 98.0, 116.9, 117.2, 121.5, 122.3,
1
23.3, 123.9, 126.8, 127.2, 132.1, 133.6, 133.7, 138.0, 143.0, 148.6, 148.7, 149.4, 151.2;
+
+
ESI-MS: (m/z): 407.2 (M+H) ; HRMS calcd for [C22
H20ClN
4
O +H] 407.1269, found
2
4
07.1270.

4
.3.15 7-Chloro-N-(2-(5-(4-fluorophenyl)-1H-imidazol-1-yl)ethyl)quinolin-4-amine (19)
1
Compound 19 was obtained as yellowish white solid in 78% yield; m.p. 161-163°C; H NMR
(
400 MHz, CDCl
NHCH CH N), 6.08 (d, J = 5.3 Hz, 1H, Ar-H quinoline), 6.97 (d, J = 8.6 Hz, 2H, Ar-H Ph),
.00 (s, 1H, Ar-H Imd), 7.18-7.20 (m, 1H, Ar-H Ph), 7.21 (d, J = 2.0 Hz, 1H, Ar-H
quinoline), 7.30-7.33 (dd, J = 2.0, 8.9 Hz, 1H, Ar-H quinoline), 7.49 (s, 1H, Ar-H Imd), 7.51-
.53 (m, 1H, Ar-H Ph), 7.94 (d, J = 2.0 Hz, 1H, Ar-H quinoline), 8.41 (d, J = 7.4 Hz, 1H, Ar-
3
): δ 3.52-3.56 (m, 2H, NHCH
2
CH
2
N), 4.29 (t, J = 5.8 Hz, 2H,
2
2
7
7
1
3
2
19 13
H quinoline); C NMR (100 MHz, CDCl ): δ 42.9, 43.4, 98.2, 114.0, 115.6, J( F, C) (d, J
3
4
19 13
=
22.2 Hz), 117.4, 122.3, 125.1, 128.0, 128.7, 130.8, J( F, C) (d, J = 3.0 Hz), 132.1
3
19 13
1
19 13
J( F, C) (d, J = 8.3Hz), 138.2, 139.1, 141.2, 148.9, 149.5, 151.4, 153.4, 167.6, J( F, C)
+
+
(
d, J = 247.6 Hz); ESI-MS: (m/z): 367.2 (M+H) ; HRMS calcd for [C20
H
17ClFN +H]
4
3
67.1120, found 367.1124.
4
.3.16 7-Chloro-N-(2-(5-(naphthalen-1-yl)-1H-imidazol-1-yl)ethyl)quinolin-4-amine (20)
1
Compound 20 was obtained as white solid in 64% yield; m.p. 206-208°C; H NMR (400
MHz, CDCl
NHCH CH N), 6.58 (d, J = 5.3 Hz, 1H, Ar-H quinoline), 7.15 (s, 1H, Ar-H Imd), 7.23 (d, J =
.8 Hz, 1H, Ar-H quinoline), 7.31 (d, J = 4.7 Hz, 1H, Ar-H quinoline), 7.37-7.40 (m, 2H, Ar-
3
): δ 3.36 (d, J = 5.0 Hz, 2H, NHCH
2
CH
2
N), 3.84 (t, J = 5.4 Hz, 2H,
2
2
1
H naphthalene), 7.47-7.50 (m, 2H, Ar-H naphthalene), 7.57 (d, J = 8.2 Hz, 1H, Ar-H
quinoline), 7.62 (s, 1H, Ar-H Imd), 7.87-789 (m, 3H, Ar-H naphthalene), 8.13 (d, J = 5.3 Hz,
1
3
1
1
1
H, Ar-H quinoline); C NMR (100 MHz, CDCl ): δ 43.1, 43.6, 98.1, 117.1, 121.6, 124.8,
3
25.1, 125.4, 126.4, 126.5, 127.1, 128.1, 128.5, 129.3, 129.6, 130.9, 132.6, 133.6, 135.0,
+
36.9, 137.7, 148.6, 149.1, 151.2; ESI-MS: (m/z): 399.2 (M+H) ; HRMS calcd for
+
[
C
24
H20ClN
4
+H] 399.1371, found 399.1372.

4
.3.17 7-Chloro-N-(2-(5-cyclohexyl-1H-imidazol-1-yl)ethyl)quinolin-4-amine (21)
1
Compound 21 was obtained as Pale yellow solid in 73% yield; m.p. 174-176°C; H NMR
(
400 MHz, CDCl
3
): δ 1.60-1.94 (m, 10H, cyclohexane), 2.17-2.24 (m, 1H, cyclohexane),
.24 (d, J = 5.3 Hz, 2H, NHCH CH N), 3.87 (t, J = 5.1 Hz, 2H, NHCH CH N), 6.45 (d, J =
.3 Hz, 1H, Ar-H quinoline), 6.74 (s, 1H, Ar-H Imd), 7.28 (s, 1H, Ar-H Imd), 7.33-7.35 (dd,
3
5
2
2
2
2
J = 2.1, 8.9 Hz, 1H, Ar-H quinoline), 7.75 (d, J = 8.9 Hz, 1H, Ar-H quinoline), 7.98 (d, J =
1
3
2
.0 Hz, 1H, Ar-H quinoline), 8.59 (d, J = 5.3 Hz, 1H, Ar-H quinoline); C NMR (100 MHz,
CDCl
3
): δ 25.6, 26.1, 26.4, 33.5, 33.6, 33.7, 42.0, 43.8, 98.3, 117.5, 122.2, 123.9, 125.4,
+
1
28.3, 135.1, 136.1, 138.1, 149.3, 149.6, 151.7; ESI-MS: (m/z): 355.6 (M+H) ; HRMS calcd
+
for [C20
H
24ClN +H] 355.1684, found 355.1684.
4
4
.3.18 4-(1-(2-(7-Chloroquinolin-4-ylamino)ethyl)-1H-imidazol-5-yl)phenol (22)
1
Compound 22 was obtained as off white solid in 65% yield; m.p. 167-169°C; H NMR (400
MHz, DMSO-d
NHCH CH N), 5.75 (s, 1H, Ar-H PhOH), 6.18 (d, J = 5.4 Hz, 1H, Ar-H quinoline), 6.77-
.79 (dd, J = 1.9, 6.6 Hz, 2H, Ar-H Ph), 6.85 (s, 1H, Ar-H Imd), 7.18-7.20 (dd, J = 1.9, 6.6
6
): δ 3.44-3.49 (m, 2H, NHCH
2
CH
2
N), 4.20 (t, J = 6.5 Hz, 2H,
2
2
6
Hz, 2H, Ar-H Ph ), 7.44-7.47 (dd, J = 2.2, 9.0 Hz, 1H, Ar-H quinoline), 7.75 (s, 1H, Ar-H
Imd), 7.78 (d, J = 2.2 Hz, 1H, Ar-H quinoline), 8.13 (d, J = 9.0 Hz, 1H, Ar-H quinoline), 8.30
1
3
(
d, J = 5.4 Hz, 1H, Ar-H quinoline); C NMR (100 MHz, DMSO-d
6
): δ 43.0, 43.2, 99.0,
1
1
16.0, 117.8, 120.6, 124.3, 124.7, 127.1, 127.9, 130.6, 132.9, 133.9, 138.7, 149.4, 150.0,
+
+
52.1, 157.8; ESI-MS: (m/z): 365.2 (M+H) ; HRMS calcd for [C20
H
18ClN O+H] 365.1164,
4
found 365.1164.
4
4
.4. Biological assay
.4.1 In vitro antimalarial assay
The compounds were evaluated for antimalarial activity against 3D7 (CQ- sensitive)
and K1 (CQ-resistant) strains of Plasmodium falciparum using Malaria SYBR Green I
nucleic acid staining dye based fluorescence (MSF) assay as mentioned by Kondaparla et al

[
22]. The stock (10 mM) solution was prepared in DMSO and test dilutions were prepared in
culture medium (RPMI-1640-FBS). The final concentration of DMSO in Plasmodium
cultures was < 1%. Chloroquine-diphosphate (SIGMA) was used as reference drug. For
assessment of antimalarial activity 50μl of culture medium was dispensed in 96 well plate
followed by addition of 50μl of highest concentration (containing less than 0.5% of DMSO)
of test compounds (in duplicate wells) in row B. Subsequent two-fold serial dilutions were
prepared in culture medium and finally 50 µl of 2.0% parasitized cell suspension containing
0
.8% parasitaemia (Asynchronous culture containing more than 80% ring stages) was added
to each well except 4 wells in row ‘A’ received non parasitized erythrocyte suspension. The
plates were incubated at 37 °C in CO incubator in an atmosphere of 5% CO and air mixture
and 72 hours later 100 µl of lysis buffer containing 2 x concentration of SYBR Green-I
Invitrogen) was added to each well and incubated for one hour at 37°C [23]. The plates were
2
2
(
examined at 485±20nm of excitation and 530±20nm of emission for relative fluorescence
units (RFUs) per well using the fluorescence plate reader (FLX800, BIOTEK). Data was
transferred into a graphic programme (EXCEL) and IC50 values were obtained by Logit
regression analysis of dose response curves using pre-programmed Excel spreadsheet.
4
.4.2 In vitro assay for evaluation of cytotoxic activity
Cytotoxicity of the compounds was carried out using Vero cell line (C1008; Monkey
kidney fibroblast) following the method as mentioned in Mosmann [24]. The cells were
incubated with compound-dilutions for 72 h and MTT was used as reagent for detection of
cytotoxicity, 50% cytotoxic concentration (CC50) was determined using nonlinear regression
analysis of dose response curves using pre-programmed Excel spreadsheet. Selectivity Index
(
SI) was calculated as SI = CC50 / IC50

4
.4.3 Determination of hematin 4-aminoquinoline derivatives association constant
Association constant for hematin 4-aminoquinoline derivatives complex formation
were determined by spectrometric titration procedure in aqueous DMSO at pH-7.5 [25]. In
this assay condition, hematin is strictly in monomeric state and interpretation of results is not
complicated by the need to consider hematin disaggregation process. Association constant
calculated in this technique is a good reflection of the interaction that would occur in the
acidic food vacuole of the parasite and pH-7.5 improves the stability of hematin solutions and
quality of the data.
4
.4.4 In vitro inhibition of β-hematin formation assay
The ability of the 4-aminoquinoline derivatives to inhibit β-hematin formation was induced
by 1-oleoyl-rac-glycerol. Spectroscopic measurements were done using UV
spectrophotometer wave length 405 nm and at pH 5 [26]. The IC50 values obtained from the
assay are expressed as percent inhibition relative to β-hematin formation in a drug free
control. The 50% inhibitory concentration values for the compounds were obtained from the
sigmoidal dose-response curves using non-linear regression curve fitting analyses with
GraphPad Prism v.3.00 software [27].
Acknowledgment
Author (K.S.R) thanks the CSIR, New Delhi, for Senior Research Fellowship. Authors thank
the Director, CDRI, for the support, and the SAIF division for the spectral data. The CDRI
manuscript No is 223/2017/SBK
Conflicts of Interest
The authors have no conflict of interest to declare.
Supporting Information available (Appendix S1): Electronic supplementary information
1
13
(
ESI) available: H NMR, C NMR data of selected compounds.

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Figure Legends
Table 1 Biological and Biophysical data of the synthesized compounds 5-22
Figure 1 Structures of some molecules having antimalarial activity.
Figure-2 a) Previously reported 4-aminoquinolines from this laboratory b) Designed 4-
aminoquinoline imidazole Prototype.
Figure 3 SAR of the synthesized potent 4-aminoquinoline
Scheme 1 Synthesis of 4-aminoquinoline-imidazole derivatives

Table 1 Biological and Biophysical data of the synthesized compounds 5-22
b
c
f
g
Cmpd In vitro antiplasmodial
pKa
SI
Log Resi LogK
IC50
a
d
.
no
activity IC50(µM)
P
stan
ce
facto
r
3
D7
K1
e
5
5.00±0.038
1.15±0.028
pKa(A)-15.95
pKa(B)- 6.01
pKa(C)-7.32
88.29
1.77 0.23 6.72±0.03 0.72±0.02
6
7
5.00±0.043
5.00±0.046
0.46±0.048
1.70±0.024
pKa(A)-5.72
pKa(B)-7.31
>431.03 3.70 0.09 6.32±0.05 0.63±0.04
>117.64 2.77 0.34 7.20±0.02 0.83±0.03
pKa(A)-15.45
pKa(B)-5.97
pKa(C)-7.32
8
9
1
0.21±0.021
2.83 ±0.028
5.00±0.047
0.45±0.019
0.29±0.018
1.09±0.016
pKa(A)-6.16
pKa(B)-7.33
79.54
>687.2
35.56
4.15 2.14 5.93±0.04 0.62±0.05
4.46 0.10 6.12±0.03 0.42±0.02
3.51 0.21 7.43±0.02 0.52±0.03
pKa(A)-6.18
pKa(B)-7.33
0
1
2
pKa(A)-4.45
pKa(B)-6.26
pKa(C)-7.36
1
1
5.00±0.039
5.00±0.044
1.33±0.029
2.62±0.025
pKa(A)-2.26
pKa(B)-5.56
pKa(C)-7.30
>150.37 3.74 0.26 6.86±0.05 0.68±0.04
pKa(A)-6.12
pKa(B)-7.33
>76.33
4.77 0.52 7.01±0.02 0.73±0.03
1
1
3
4
0.14±0.018
0.29±0.018
0.50±0.023
0.97±0.025
pKa(A)-6.69
pKa(B)-7.42
190.95
102.76
3.26 3.37 6.59±0.03 0.64±0.02
1.85 3.29 5.71±0.05 0.69±0.04
pKa(A)-5.35
pKa(B)-7.30
1
1
5
6
5.00±0.048
5.00±0.043
0.73±0.027
1.78±0.021
pKa(A)-6.14
pKa(B)-7.33
160.80
3.26 0.14 7.71±0.04 0.71±0.03
pKa(A)-6.20
pKa(B)-7.33
>112.29 3.10 0.35 7.83±0.02 0.73±0.04

1
1
1
2
2
2
7
8
9
0
1
2
0.079±0.015
0.52±0.028
5.00±0.045
5.00±0.045
0.19±0.017
3.73±0.038
0.34±0.011
2.40±0.031
3.04±0.039
0.92±0.031
0.52±0.029
5.00±0.047
pKa(A)-6.72
pKa(B)-7.43
203.82
3.06 4.30 6.54±0.05 0.63±0.03
2.73 4.57 7.88±0.02 0.69±0.02
3.39 0.60 8.12±0.03 0.79±0.04
4.23 0.18 7.62±0.03 0.75±0.03
pKa(A)-6.16 39.21
pKa(B)-7.33
pKa(A)-6.18
pKa(B)-7.33
26.12
pKa(A)-6.15 6.43
pKa(B)-7.33
pKa(A)-6.72 >383.14 3.47 2.67 6.70±0.04 0.67±0.03
pKa(B)-7.43
pKa(A)-9.80 15.13
pKa(B)-6.32
2.84 1.34 8.73±0.05 0.81±0.04
pKa(C)-7.23
CQ
0.005±0.002
0.255±0.049
pKa(A)- 9.8 8983
pKa(B)- 7.32
3.73 51
5.52±0.02 0.17±0.02
a
b
IC50 (µM±SD) : Concentration corresponding to 50% growth inhibition of the parasite; Pka value of different
compounds was calculated using chemaxon software. Selectivity index (SI): (CC50 for cytotoxicity to vero cells
IC50(3D7) for antiplasmodial activity); log P values calculated using ChemBioDraw ultra software; Resistance
factor (RI): IC50(K1)/IC50(3D7); 1:1 (compound : Hematin) complex formation in 40% aqueous DMSO, 20 mM
HEPES buffer, pH 7.5 at 25 °C (data are expressed as means ± SD from at least three different experiments in
c
d
e
/
f
g
duplicate); The IC50 represents the millimolar equivalents of test compounds, relative to hemin, required to
inhibit β-hematin formation by 50% (data are expressed as means ± SD from at least three different experiments
in duplicate).

Figure 1 Structures of some molecules having antimalarial activity.

Figure-2 a) Previously reported 4-aminoquinolines from this laboratory. b) Designed 4-
aminoquinoline imidazole Prototype.