β-amino-alcohol tethered 4-aminoquinoline-isatin conjugates: Synthesis and antimalarial evaluation

Article abstract of DOI:10.1016/j.ejmech.2014.07.064

A series of β-amino alcohol tethered 4-aminoquinoline-isatin conjugates were synthesized with the aim of probing their antimalarial structure activity relationship. Two of the most active conjugates (11 b and 11 f) exhibited antimalarial efficacy comparable to that of chloroquine, with IC₅₀ values of 11.8 and 13.5 nM, respectively against chloroquine resistant W2 strain of Plasmodium falciparum and are devoid of any cytotoxicity.

Full text of DOI:10.1016/j.ejmech.2014.07.064

European Journal of Medicinal Chemistry 84 (2014) 566e573
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Short communication
b-amino-alcohol tethered 4-aminoquinoline-isatin conjugates:
Synthesis and antimalarial evaluation
,
*
Nisha a, Jiri Gut b, Philip J. Rosenthal b, Vipan Kumar a
a Department of Chemistry, Guru Nanak Dev University, Amritsar 143005, India
b Department of Medicine, University of California, San Francisco, CA, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of b-amino alcohol tethered 4-aminoquinoline-isatin conjugates were synthesized with the aim
Received 23 June 2014
Received in revised form
16 July 2014
Accepted 19 July 2014
Available online 21 July 2014
of probing their antimalarial structure activity relationship. Two of the most active conjugates (11b and
11f) exhibited antimalarial efficacy comparable to that of chloroquine, with IC50 values of 11.8 and
13.5 nM, respectively against chloroquine resistant W2 strain of Plasmodium falciparum and are devoid of
any cytotoxicity.
© 2014 Elsevier Masson SAS. All rights reserved.
Keywords:
b-amino alcohol
4-Aminoquinoline-isatin conjugates
Antimalarial activity
Cytotoxicity
1. Introduction
antimalarials and potentially delaying the emergence of drug
resistance [12e16]. The hybrid drug approach involves the rational
With 207 million cases and 627 thousand deaths in 2012, ma-
laria is one of the world's deadliest diseases, affecting 64% of the
global population [1]. Plasmodium falciparum is the most virulent
human malaria parasite, and is responsible for most of the malaria-
related deaths [2,3]. Since the discovery of the natural product
quinine, many compounds with a quinoline scaffold have displayed
good antimalarial activity, leading to the development of effective
antimalarial agents, including chloroquine, amodiaquine, piper-
aquine and mefloquine [4e6]. Chloroquine has been extensively
utilized for decades because of its efficacy, safety and low cost.
However, the widespread resistance of P. falciparum to chloroquine
[2,7] has hampered efforts to combat malaria and led to the
development of the natural endoperoxide artemisinin and its
semisynthetic derivatives (artemether, artesunate, and dihy-
droartemisinin) as potent and fast acting antimalarials [8]. How-
ever, the worldwide deployment of artemisinin based combination
therapy is limited by relatively high cost of treatment, safety in
pregnancy and [9,10] early signs of resistance to artemisinin de-
rivatives in southeast Asia [11].
design of new chemical entities by covalent fusion of two phar-
macophores with complimentary activities and different pharma-
cological targets. The potential of a quinoline-hybridisation strategy
was demonstrated by several active antimalarials that include tri-
oxaferroquines [13], trioxaquines [17], an artemisinin-quinine
hybrid [18], 4-aminoquinoline based tetraoxanes [19], clotrima-
zole-based-4-aminoquinolines [20] and isatin-4-aminoquinoline
hybrids [21].
Isatin is one of the most promising heterocyclic scaffolds, with
anti-HIV [22], antiviral [23], anti-tumour [24e26], antifungal
[27,28], anti-angiogenic [29], anticonvulsant [30], and anti-Par-
kinson’s [31] activity. It is an effective SARS coronavirus 3CL pro-
tease inhibitor [32] and is well-tolerated in human subjects [33,34].
Isatin has major importance in organic synthesis due to a highly
reactive C-3 carbonyl group which allows easy transformation into
2-oxoindole compounds upon nucleophilic addition or spi-
roannulation [35]. 2-oxoindole derivatives such as SU-5416 (sem-
axanib) and SU-11248 (Sunitinib),
a 5-fluoro-3-substituted-2-
oxoindole, were reported to have tyrosine kinase inhibitory and
anti-angiogenic properties [36,37]. The encouraging applications of
isatin in organic synthesis and its biological potential have
prompted efforts towards the synthesis and evaluation of novel
isatin-derivatives.
4-Aminoquinoline hybridization is now considered as an
attractive and viable strategy for developing new efficacious
Recently the antimalarial potential of isatins via synthesis of
isatin-chalcone and isatin-thiolactone conjugates has been
* Corresponding author.
E-mail address: vipan_org@yahoo.com (V. Kumar).
http://dx.doi.org/10.1016/j.ejmech.2014.07.064
0223-5234/© 2014 Elsevier Masson SAS. All rights reserved.

Nisha et al. / European Journal of Medicinal Chemistry 84 (2014) 566e573
567
explored [38,39]. The synthesized thiolactone-isatin conjugates
showed superior antimalarial activity; the most active scaffold
exhibited an IC50 of 6.92 mM against W2 strain of P. falciparum [39].
as C23H23ClN4O3, showed a molecular ion peak at m/z 438.1451 in
its high resolution mass spectrum. The salient features of its 1H
NMR spectrum included the appearance of a pair of doublet of a
In particular, isatin-quinoline hybrids were shown to possess good
antiplasmodial profiles as evidenced by isatin-4-aminoquinolines
tethered via ethyl linker which exhibited IC50 values in the range
of 51e54 nM [21]. These examples suggested that the isatin-
quinoline core has an inherent potential as a lead antimalarial
agent and the introduction of substituents at appropriate positions
and the nature of linker in this structural framework could improve
its antimalarial efficacy.
doublet at
a multiplet at
appearance of characteristic quinoline ring protons. The 13C NMR
d
5.23 (J ¼ 1.4 and 10.3 Hz) corresponding to the eNCH2,
d
5.95 corresponding to the methine proton, and the
spectrum showed characteristic absorptions at
ing to a methine carbon, while absorptions at
d
98.1 correspond-
152.1 and 171.0
d
corresponded to the presence of isatin carbonyls. The appearance of
methylene carbon at
d
115.1, as confirmed by the 13C NMR (DEPT)
spectrum along with the requisite number of carbons, further
substantiated the assigned structures.
A previous report from our group revealed the synthesis and
antimalarial
evaluation
of
1H-1,2,3-triazole-tethered-7-
chloroquinoline-isatin [40,41] and piperazine-tethered isatin-7-
chloroquinoline conjugates [42]. The observed activity profiles
among these conjugates were found to depend on the substituent
at the C-5 position of isatin and the length of the alkyl chain.
Building on our interest in molecular hybridization to develop new
antimalarials [43], we report herein the synthesis and biological
evaluation of hybrids containing a 4-aminoquinoline tethered to
2.2. In vitro antiplasmodial activity
The synthesized compounds were evaluated for their anti-
malarial profiles against the CQ resistant W2 strain of P. falcipa-
rum (Table 1). The antimalarial activities depended upon the
nature of the substituent at the C-5 position of the isatin ring and
upon the alkyl chain length. Activities decreased as the chain
length was increased, from ethyl to propyl linker, except in the
case of 11b and 11f, which had essentially the same activity. A
further increase in chain length via introducing butyl and hexyl
linkers did not alter the observed antimalarial efficacy. The nature
of the substituent at the C-5 position of the isatin ring also seems
to play a crucial role in influencing antimalarial activity. The
presence of an inductively electron withdrawing chloro-
substituent at C-5 improved activity irrespective of the chain
length, with effects more pronounced with shorter (n ¼ 2,3) alkyl
chain lengths. The replacement of the chloro substituent with an
H, -CH3 or F group decreased activity, although few of these hy-
brids showed activity comparable with that of chloroquine, while
compound 11a (R ¼ H) showed better activity than chloroquine.
The replacement of the alkyl chain with a piperazine ring resulted
in a complete loss of activity, as evident with compounds 12bed.
Compounds 11b and 11f, with an optimum combination of
shorter alkyl chain lengths (n ¼ 2 and 3) and the presence of a
chloro-substituent at the C-5 position of th isatin ring, were the
most potent of the tested compounds, exhibiting IC50 of 11.8 and
13.5 nM, respectively. The most potent of the tested compounds
were then evaluated for their cytotoxic profiles against HCT116
isatin derivatives through an
rationale behind the introduction of a
b
-amino alcohol functionality. The
-amino alcohol linker is its
b
presence in a number of potent antimalarials, as exemplified by
mefloquine [44]. The length of the alkyl chain at the C-4 position of
the quinoline ring was varied because of its established impact on
antimalarial efficacy [45e48].
2. Results and discussion: synthetic chemistry and
pharmacology
2.1. Synthetic chemistry
The synthesis of the target
b-amino alcohol tethered isatin-
quinoline hybrids involved an initial synthesis of the required
precursors viz. 1-oxiranylmethyl isatin 3 and 4-aminoquinolines 9
and 10. The procedure for the synthesis of 1-oxiranylmethyl indole-
2,3-dione 3 was based on our recent report involving an initial base
promoted allylation of C-5 substituted isatins with its subsequent
epoxidation using m-chloroperbenzoic acid (mCPBA) in dry chlo-
roform at 60 ꢀC (Scheme 1) [49].
The preparation of 4 aminoquinoline-based precursors was
realized by heating 4,7-dichloroquinoline with an excess of
aliphatic chain/cyclic diaminoalkanes initially at 80 ꢀC and then at
135 ꢀC for 3 h, as shown in Scheme 2, [43a].
The target hybrids 11 were synthesized by refluxing precursors
3 and 9 in dry toluene at 110 ꢀC in the presence of a catalytic
amount of p-toluene sulphonic acid for 4e6 h. The conjugates 12
were prepared under similar conditions, however with longer
duration of refluxing (Scheme 3).
The purification of the reaction mixture via column chroma-
tography resulted in the isolation of desired structural chimeras 11
and 12. The structures were assigned on the basis of spectral data
and analytical evidence. The compound 11e, for example, analyzed
(colon cancer cell line) cells at 0.2, 2.0 and 20
mM (Table 2). As
evident, the active conjugates were devoid of any cytotoxic ac-
tivity at low concentration and thus can act as therapeutic tem-
plates for the synthesis of new antimalarials.
In conclusion, the present manuscript describes the synthesis of
b-amino alcohol tethered isatin-4-aminoquinoline hybrids and
evaluation of their activities against P. falciparum. Our results reveal
a clear preference for shorter alkyl chain length (n ¼ 2,3) and the
presence of a chloro-substituent at the C-5 position of the isatin
ring for optimal antimalarial activity. The most potent and non-
cytotoxic conjugates exhibited antimalarial activity comparable to
that of chloroquine and artemisinin.
O
O
O
Br
R
R
R
m-CPBA
O
O
O
NaH, DMF,
60 oC, 6 hrs
Dry CHCl3,
60 oC, 2 hrs
N
N
N
H
2
O
3
1
R= H, Cl, F, CH3
Scheme 1. Synthesis of 1-oxiranylmethyl indole-2,3diones 3.

568
Nisha et al. / European Journal of Medicinal Chemistry 84 (2014) 566e573
NH2CH2(CH2)nNH2
5, n = 1; 6, n = 2
7, n = 3; 8, n = 5
NHCH2(CH2)nNH2
Cl
N
80-135 oC,
4 hrs
+
Cl
N
Cl
NEt3,
9
4
H
N
80-135 oC,
8 hrs
N
H
H
N
N
N
Cl
10
Scheme 2. Synthesis of 4-aminoquinolines.
3. Experimental section
br: broad peak. 13C NMR spectra were recorded on Jeol 300
(75 MHz) spectrometers in deuterochloroform and DMSO-d6 using
TMS as internal standard. High resolution mass spectra were
recorded on a Bruker-micrOTOF-Q II spectrometer. Column chro-
matography was performed on a silica gel (60e120 mesh).
Melting points were determined by open capillary using a Veego
Precision Digital Melting Point apparatus (MP-D) and are uncor-
rected. 1H NMR spectra were recorded in deuterochloroform and
DMSO-d6 with Jeol 300 (300 MHz) spectrometers using TMS as
internal standard. Chemical shift values are expressed as parts per
million downfield from TMS, and J values are in hertz. Splitting
patterns are indicated as s: singlet, d: doublet, t: triplet, m: multi-
plet, dd: double doublet, ddd: doublet of a doublet of a doublet, and
3.1. Procedure for the synthesis of substituted N-allyl isatins 2
Isatin (1 mmol) was added to a stirred suspension of sodium
hydride (1.5 mmol) in dry DMF (10 mL) resulting in the formation of
Scheme 3. Synthesis of isatin-4-aminoquinoline conjugates.

Nisha et al. / European Journal of Medicinal Chemistry 84 (2014) 566e573
Table 1 (continued )
569
Table 1
Antimalarial activities of tested compounds against CQ resistant W2 strains of
P. falciparum.
Compound
Structure
IC50 (nM)
49.7
clogP
Compound
Structure
IC50 (nM)
24.9
clogP
11n
5.0
4.6
11a
3.6
11o
55.8
11b
11c
11.7
ND
4.5
4.1
11p
12a
59.6
4.4
3.0
216.0
11d
488.1
3.9
12b
1960.0
3.8
11e
11f
75.5
13.5
302.0
72.3
3.9
4.8
4.4
4.2
12c
12d
1225.0
1853.5
3.4
3.3
11g
11h
CQ
ART
36.37
04.37
purple coloured anionic solution. The solution was allowed to stir at
room temperature till the evolution of hydrogen ceases. To this
reaction mixture was added drop wise a solution of allyl bromide
(1.1 mmol) in dry DMF. The reaction mixture was heated to 60 ꢀC
with constant stirring for about 6 h. After the completion of the
reaction, as evident from TLC, quenching was done by drop wise
addition of water (20 mL) with subsequent extraction with ethyl
acetate (3 ꢁ 30 mL). The combined organic layers were washed
with brine solution, dried over anhydrous Na2SO4 and concentrated
11i
11j
48.7
3.1
4.0
101.0
Table 2
11k
58.0
3.6
Cytotoxicity of some active compounds against HCT116 (colon cancer cell line) cells.
Compound
R
n
Cytotoxicity % inhibition
0.2
mM
2.0
m
M
20 mM
11a
11b
11e
11f
11h
11i
11l
H
Cl
H
Cl
F
1
1
2
2
2
3
3
0
0
2
2
91
88
85
46
66
37
83
79
90
11l
45.3
62.9
3.3
4.1
ꢂ11
ꢂ12
2
12
ꢂ5
0
0
ꢂ2
H
F
0
ꢂ1
84
16
11m
Doxorubicin
Staurosporine
79
80

570
Nisha et al. / European Journal of Medicinal Chemistry 84 (2014) 566e573
under reduced pressure. Purification of the reaction mixture via
column chromatography using hexane: ethyl acetate (4:1) mixture
furnished the desired N-allyl isatin derivatives in good yields.
eCH2e); 4.98e5.15 (m, 2H, eCH2e); 5.63e5.71 (m, 1H, eCHe);
6.25 (d, J ¼ 5.1 Hz, 1H, H2); 6.35e6.39 (m, 1H, AreH); 7.19 (dd,
J ¼ 2.4 Hz, 9.0 Hz, 1H, H4); 7.29e7.30 (m, 1H, AreH); 7.53 (s, 1H,
AreH); 7.67e7.77 (m, 2H, H5þ eNH exchangeable with D2O); 7.93
(d, J ¼ 9.0 Hz, 1H, H3); 8.18e8.21 (m, 2H, H1þ eOH exchangeable
with D2O); 13C NMR (75 MHz, CDCl3): dC 20.1, 37.6, 42.5, 44.9, 99.2,
111.9, 114.3, 114.6, 115.2, 123.9, 124.7, 125.6, 128.1, 132.4, 133.9, 134.6,
135.1, 147.5, 148.8, 150.7, 151.6, 169.8. HRMS calculated for
3.2. Procedure for the synthesis of 1-oxiranylmethyl isatin 3
N-allyl isatin 2 was added to a stirred suspension of m-chlor-
operbenzoic acid (m-CPBA) (1.2 mmol) in dry CHCl3 at 0 ꢀC. The
reaction mixture was allowed to attain room temperature and
subsequently refluxed at 60 ꢀC for 2 h. After the completion of the
reaction as evident from TLC, the excess of m-CPBA was quenched
by treatment with a saturated solution of K2CO3 and the organic
layer was subsequently extracted with chloroform (3 ꢁ 30 mL). The
combined organic layers were dried over anhydrous Na2SO4 and
concentrated under reduced pressure resulting in the isolation of a
crude solid which was recrystallized using (9:1) hexane:chloroform
mixture.
C
23H23ClN4O3 438.1459 [Mþ] found 438.1451; Anal. Calcd (%) for: C,
62.94; H, 5.28; N, 12.77; found C, 62.85; H, 5.16; N, 12.85.
3.3.4. 1-{2-[2-(7-Chloro-quinolin-4-ylamino)-ethylamino]-3-
hydroxy-propyl}-5-fluoro-1H-indole-2,3-dione (11d)
White solid, yield 87%, m.p. 180e181 ꢀC; 1H NMR (300 MHz,
CDCl3): dH 3.31 (s, 2H, eCH2e); 3.61 (s, 4H, 2ꢁ eCH2e); 4.95e5.15
(m, 2H, eCH2e); 5.61e5.72 (m, 1H, eCHe); 6.27 (d, J ¼ 5.1 Hz, 1H,
H2); 6.35 (d, J ¼ 8.2 Hz, 1H, AreH); 7.18 (dd, J ¼ 2.4, 8.7 Hz, 1H, H4);
7.27 (d, J ¼ 8.2,1H, AreH); 7.54 (s,1H, AreH); 7.65e7.73 (m, 2H, H5þ
eNH exchangeable with D2O); 7.92 (d, J ¼ 9.0 Hz, 1H, H4); 8.32 (d,
J ¼ 5.1 Hz, 1H, H1); 13C NMR (75 MHz, CDCl3): dC 38.1, 42.0, 45.2,
98.7, 113.3, 115.5, 115.6, 117.0, 117.9, 123.9, 124.3, 126.3, 127.6, 131.6,
134.2, 134.9, 147.3, 147.7, 150.4, 151.2, 168.7. HRMS calculated for
3.3. General method for the preparation of isatin-4aminoquinoline
conjugates 11aep
To the stirred solution of 1-oxiranylmethyl isatin 3 (1 mmol) and
4-aminoquinoline 9 (1 mmol) in dry toluene was added catalytic
amount of p-toluene sulphonic acid. The reaction mixture was
refluxed at 110 ꢀC for 6 h and the progress was monitored by TLC.
On completion, water (15 mL) was added to the reaction mixture
and subsequently extraction was done using chloroform
(2 ꢁ 50 mL). Combined organic layers were dried over anhydrous
sodium sulphate and concentrated under reduce pressure. Purifi-
cation of reaction mixture via column chromatography using hex-
ane:ethylacetate (3:2) mixture as eluent resulted in the isolation of
desired hybrids 11aep.
C
22H20ClFN4O3 442.1208 [Mþ] found 442.1215; Anal. Calcd (%) for:
C, 59.66; H, 4.55; N, 12.65; found C, 59.74; H, 4.46; N, 12.57.
3.3.5. 1-{2-[3-(7-Chloro-quinolin-4-ylamino)-propylamino]-3-
hydroxy-propyl}-1H-indole-2,3-dione (11e)
White solid, yield 83%, m.p. 158e159 ꢀC; 1H NMR (300 MHz,
CDCl3): dH 1.94e2.01 (m, 2H, eCH2e); 3.48e3.49 (m, 2H, eCH2e);
3.55e3.60 (m, 2H, eCH2e); 3.81 (s, 2H, eCH2e); 5.17 (dd, J ¼ 1.4,
10.3 Hz, 1H, eCH2e); 5.30 (dd, J ¼ 1.4, 10.3 Hz, 1H, eCH2e);
5.91e5.98 (m, 1H, eCHe); 6.38 (d, J ¼ 6.0 Hz, 1H, H2); 6.56 (t,
J ¼ 7.2 Hz, 1H, AreH); 6.65 (d, J ¼ 8.3 Hz, 1H, AreH); 6.96 (t,
J ¼ 6.1 Hz, 1H, NH exchangeable with D2O); 7.26e7.32 (m, 2H,
H4 þ AreH); 7.44 (dd, J ¼ 0.9, 7.8 Hz, 1H, AreH); 7.58 (s, 1H, NH
exchangeable with D2O); 7.72 (s, 1H, OH exchangeable with D2O);
7.90 (d, J ¼ 1.7 Hz, 1H, H5); 8.10 (d, J ¼ 9.0 Hz, 1H, H3); 8.32 (d,
J ¼ 6.0 Hz, 1H, H1); 13C NMR (75 MHz, CDCl3): dC 28.2, 36.6, 39.9,
45.4, 98.1, 112.1, 114.5, 115.1, 116.0, 116.7, 122.9, 124.9, 126.1, 127.6,
133.1, 134.7, 136.6, 148.0, 149.5, 152.1, 171.0. HRMS calculated for
3.3.1. 1-{2-[2-(7-Chloro-quinolin-4-ylamino)-ethylamino]-3-
hydroxy-propyl}-1H-indole-2,3-dione (11a)
White solid, yield 85%, m.p. 183e184 ꢀC; 1H NMR (300 MHz,
CDCl3): dH 3.48 (s, 2H, -CH2-); 3.80 (s, 4H, 2ꢁ eCH2e); 5.16e5.31
(m, 2H, eCH2e); 5.83e5.98 (m, 1H, eCHe); 6.34 (d, J ¼ 5.1 Hz, 1H,
H2); 6.56 (d, J ¼ 9.0 Hz, 1H, AreH); 7.16e7.31 (m, 3H, H4 þ 2AreH);
7.53 (s, 1H, AreH); 7.89 (s, 1H, H5); 7.96 (d, J ¼ 9.0 Hz, 1H, H3); 8.40
(d, J ¼ 5.1 Hz, 1H, H1); 13C NMR (75 MHz, CDCl3): dC 37.2, 42.5, 44.1,
99.7, 111.3, 114.3, 114.6, 115.2, 117.5, 123.3, 124.8, 125.7, 127.3, 128.2,
132.3, 134.6, 135.1, 148.9, 151.5, 169.9. HRMS calculated for
C
23H23ClN4O3 438.1459 [Mþ] found 438.1451; Anal. Calcd (%) for: C,
62.94; H, 5.28; N, 12.77; found C, 62.83; H, 5.41; N, 12.68.
C
22H21ClN4O3 424.1302 [Mþ] found 424.1309; Anal. Calcd (%) for: C,
3.3.6. 5-Chloro-1-{2-[3-(7-Chloro-quinolin-4-ylamino)-
62.19; H, 4.98; N, 13.19; found C, 62.26; H, 4.84; N, 13.27.
propylamino]-3-hydroxy-propyl}-1H-indole-2,3-dione (11f)
White solid, yield 85%, m.p. 151e152 ꢀC; 1H NMR (300 MHz,
CDCl3): dH 1.93e2.01 (m, 2H, eCH2e); 3.45e3.47 (m, 2H, eCH2e);
3.56e3.60 (m, 2H, eCH2e); 3.79 (s, 2H, eCH2e); 5.19 (dd, J ¼ 1.4,
10.3 Hz, 1H, eCH2e); 5.31 (dd, J ¼ 1.4, 10.3 Hz, 1H, eCH2e);
5.91e5.98 (m, 1H, eCHe); 6.39 (d, J ¼ 6.0 Hz, 1H, H2); 6.71 (d,
J ¼ 8.3 Hz, 1H, AreH); 6.93 (t, J ¼ 6.1 Hz, 1H, NH exchangeable with
D2O); 7.16e7.23 (m, 2H, AreH); 7.39 (d, J ¼ 9.0 Hz, 1H, H4); 7.58 (s,
1H, NH exchangeable with D2O); 7.75 (s, 1H, NH exchangeable with
D2O); 7.88 (d, J ¼ 9.0 Hz, 1H, H3); 7.99 (s, 1H, H5); 8.66 (d, J ¼ 6.0 Hz,
1H, H1); 13C NMR (75 MHz, CDCl3): dC 28.9, 35.9, 40.2, 46.1, 99.1,
111.2, 112.8, 115.3, 116.5, 122.4, 123.7, 124.6, 125.7, 127.1, 133.4, 134.1,
135.9, 147.8, 148.9, 150.2, 152.5, 169.3. HRMS calculated for
3.3.2. 5-Chloro-1-{2-[2-(7-Chloro-quinolin-4-ylamino)-
ethylamino]-3-hydroxy-propyl}-1H-indole-2,3-dione (11b)
White solid, yield 86%, m.p. 175e176 ꢀC; 1H NMR (300 MHz,
CDCl3): dH 3.29 (s, 2H, eCH2e); 3.58 (s, 4H, 2xeCH2e); 4.94e5.10
(m, 2H, -CH2-); 5.65e5.76 (m, 1H, -CH-); 6.22 (d, J ¼ 5.1 Hz, 1H, H2);
6.34e6.39 (m, 1H, AreH); 6.95e7.15 (m, 3H, H4þ 2AreH); 7.24 (s,
1H, eNH exchangeable with D2O); 7.33e7.35 (m, 1H, AreH);
7.64e7.70 (m, 2H, H5þ eNH exchangeable with D2O); 7.83 (d,
J ¼ 8.8 Hz, 1H, H3); 8.20e8.24 (m, 2H, H1þ eOH exchangeable with
D2O); 13C NMR (75 MHz, CDCl3): dC 37.5, 42.0, 44.7, 98.5,113.1, 115.4,
115.8, 117.0, 117.8, 123.9, 124.5, 126.0, 127.6, 131.8, 134.2, 134.8, 147.2,
147.7, 150.3, 151.0, 168.5. HRMS calculated for C22H20Cl2N4O3
458.0912 [Mþ] found 458.0921; Anal. Calcd (%) for: C, 57.53; H,
4.39; N, 12.20; found C, 57.45; H, 4.47; N, 12.28.
C
23H22Cl2N4O3 472.1069 [Mþ] found 472.1075; Anal. Calcd (%) for: C,
58.36; H, 4.68; N, 11.84; found C, 58.27; H, 4.76; N, 11.93.
3.3.7. 1-{2-[3-(7-Chloro-quinolin-4-ylamino)-propylamino]-3-
hydroxy-propyl}-5-methyl-1H-indole-2,3-dione (11g)
3.3.3. 1-{2-[2-(7-Chloro-quinolin-4-ylamino)-ethylamino]-3-
hydroxy-propyl}-5methyl-1H-indole-2,3-dione (11c)
White solid, yield 81%, m.p. 157e158 ꢀC; 1H NMR (300 MHz,
CDCl3): dH 1.92e2.00 (m, 2H, eCH2e); 2.29 (s, 3H, eCH3);
3.45e3.46 (m, 2H, eCH2e); 3.56e3.60 (m, 2H, eCH2e); 3.81 (s, 2H,
White solid, yield 85%, m.p. 169e170 ꢀC; 1H NMR (300 MHz,
CDCl3): dH 2.29 (s, 3H, eCH3); 3.35 (s, 2H, eCH2e); 3.62 (s, 4H,

Nisha et al. / European Journal of Medicinal Chemistry 84 (2014) 566e573
571
eCH2e); 5.19 (dd, J ¼ 1.4, 10.3 Hz, 1H, eCH2e); 5.30 (dd, J ¼ 1.4,
10.3 Hz, 1H, eCH2e); 5.91e5.97 (m, 1H, eCHe); 6.41 (d, J ¼ 6.0 Hz,
1H, H2); 6.71 (d, J ¼ 8.3 Hz, 1H, AreH); 7.16e7.27 (m, 2H, AreH);
7.39 (d, J ¼ 9.0 Hz, 1H, H4); 7.56 (s, 1H, NH exchangeable with D2O);
7.73 (s, 1H, NH exchangeable with D2O); 7.89 (d, J ¼ 9.0 Hz, 1H, H3);
7.97 (s, 1H, H5); 8.58 (d, J ¼ 6.0 Hz, 1H, H1); 13C NMR (75 MHz,
CDCl3): dC 20.9, 27.9, 36.3, 39.5, 45.9, 99.7, 111.7, 113.9, 115.7, 116.1,
117.2, 123.2, 123.9, 126.5, 127.1, 133.7, 134.2, 147.5, 147.9, 149.3, 150.9,
151.7, 168.9. HRMS calculated for C24H25ClN4O3 452.1615 [Mþ]
found 452.1608; Anal. Calcd (%) for: C, 63.64; H, 5.56; N, 12.37;
found C, 63.75; H, 5.43; N, 12.45.
2.51e2.56 (m, 2H, eCH2e); 3.33 (d, J ¼ 5.7 Hz, 2H, eCH2e); 3.34 (d,
J ¼ 5.7 Hz, 2H, eCH2e); 3.76 (s, 2H, eCH2e); 5.15 (dd, J ¼ 1.4,
10.3 Hz, 1H, eCH2e); 5.27 (dd, J ¼ 1.4, 10.3 Hz, 1H, eCH2e);
5.84e5.93 (m, 1H, eCHe); 6.51 (d, J ¼ 6.0 Hz, 1H, H2); 6.59 (d,
J ¼ 8.3 Hz, 1H, AreH); 7.13e7.24 (m, 2H, AreH); 7.39 (d, J ¼ 9.0 Hz,
1H, H4); 7.63 (s, 1H, NH exchangeable with D2O); 7.81 (d, J ¼ 9.0 Hz,
1H, H3); 7.91 (s, 1H, H5); 8.67 (d, J ¼ 6.0 Hz, 1H, H1); 13C NMR
(75 MHz, CDCl3): dC 20.9, 25.9, 27.1, 38.8, 42.4, 45.1, 98.9,111.9,114.5,
115.2,115.8,116.5,123.8,124.9,125.5,127.6,132.5,134.1,135.4, 146.7,
148.8, 149.7, 151.1, 169.7. HRMS calculated for
C25H27ClN4O3
466.1772 [Mþ] found 466.1766; Anal. Calcd (%) for: C, 64.30; H, 5.83;
N, 12.00; found C, 64.43; H, 5.91; N, 12.11.
3.3.8. 1-{2-[3-(7-Chloro-quinolin-4-ylamino)-propylamino]-3-
hydroxy-propyl}-5-fluoro-1H-indole-2,3-dione (11h)
3.3.12. 1-{2-[4-(7-Chloro-quinolin-4-ylamino)-butylamino]-3-
hydroxy-propyl}-5-fluoro-1H-indole-2,3-dione (11l)
White solid, yield 88%, m.p. 148e149 ꢀC; 1H NMR (300 MHz,
CDCl3): dH 1.94e2.00 (m, 2H, eCH2e); 3.45e3.47 (m, 2H, eCH2e);
3.56e3.60 (m, 2H, eCH2e); 3.83 (s, 2H, eCH2e); 5.17 (dd, J ¼ 1.4,
10.3 Hz, 1H, eCH2e); 5.30 (dd, J ¼ 1.4, 10.3 Hz, 1H, eCH2e);
5.92e5.98 (m, 1H, eCHe); 6.37 (d, J ¼ 6.0 Hz, 1H, H2); 6.67 (d,
J ¼ 8.3 Hz, 1H, AreH); 7.16e7.21 (m, 2H, AreH); 7.39 (d, J ¼ 9.0 Hz,
1H, H4); 7.56 (s, 1H, NH exchangeable with D2O); 7.73 (s, 1H, NH
exchangeable with D2O); 7.92 (d, J ¼ 9.0 Hz, 1H, H3); 8.12 (s, 1H, H5);
8.58 (d, J ¼ 6.0 Hz, 1H, H1); 13C NMR (75 MHz, CDCl3): dC 28.5, 36.9,
40.1, 45.7, 98.9, 113.1, 114.6, 115.8, 116.7, 122.1, 123.5, 124.9, 126.4,
127.6, 132.5, 135.1, 136.1, 147.5, 148.5, 150.5, 152.5, 171.3. HRMS
calculated for C23H22ClFN4O3 456.1364 [Mþ] found 456.1373; Anal.
Calcd (%) for: C, 60.46; H, 4.85; N, 12.26; found C, 60.59; H, 4.99; N,
12.17.s.
White solid, yield 82%, m.p. 148e149 ꢀC; 1H NMR (300 MHz,
CDCl3): dH 1.67e1.75 (m, 4H, 2x eCH2e); 2.53e2.57 (m, 2H,
eCH2e); 3.32 (d, J ¼ 5.7 Hz, 2H, eCH2e); 3.34 (d, J ¼ 5.7 Hz, 2H,
eCH2e); 3.75 (s, 2H, eCH2e); 5.14 (dd, J ¼ 1.4, 10.3 Hz, 1H, eCH2e);
5.23 (dd, J ¼ 1.5, 17.2 Hz, 1H, eCH2e); 5.82e5.93 (m, 1H, eCHe);
6.51e6.60 (m, 3H, H2þ 2AreH); 7.33 (d, J ¼ 9.0 Hz, 1H, H4); 7.49 (dd,
J ¼ 0.9, 7.8 Hz, 1H, AreH); 7.88 (d, J ¼ 1.8 Hz, 1H, H5); 7.95 (s, 2H,
H3þ NH exchangeable with D2O); 8.65 (d, J ¼ 6.0 Hz, 1H, H1); 13C
NMR (75 MHz, CDCl3): dC 25.2, 26.7, 38.5, 41.9, 44.2, 98.4, 113.1,
114.5,115.1,115.3, 116.7, 124.5, 124.6,125.3,128.3,132.5,134.6,135.5,
146.1, 148.8, 149.2, 151.3, 169.1. HRMS calculated for C24H24ClFN4O3
470.1521 [Mþ] found 470.1529; Anal. Calcd (%) for: C, 61.21; H, 5.14;
N, 11.90; found C, 61.36; H, 5.29; N, 11.81.
3.3.9. 1-{2-[4-(7-Chloro-quinolin-4-ylamino)-butylamino]-3-
hydroxy-propyl}-1H-indole-2,3-dione (11i)
3.3.13. 1-{2-[6-(7-Chloro-quinolin-4-ylamino)-hexylamino]-3-
hydroxy-propyl}-1H-indole-2,3-dione (11m)
White solid, yield 82%, m.p. 155e156 ꢀC; 1H NMR (300 MHz,
CDCl3): dH 1.63e1.76 (m, 4H, 2ꢁ eCH2e); 3.34 (dd, J ¼ 6.04, 12.0 Hz,
4H, 2ꢁ eCH2e); 3.77 (s, 2H, eCH2e); 5.11 (dd, J ¼ 1.4, 10.3 Hz, 1H,
eCH2e); 5.30 (dd, J ¼ 1.5, 17.2 Hz, 1H, eCH2e); 5.87e5.96 (m, 1H,
eCHe); 6.53e6.64 (m, 3H, H2þ 2AreH); 7.24 (t, J ¼ 8.2 Hz, 1H,
AreH); 7.49e7.54 (m, 2H, H4þ1AreH); 7.83 (d, J ¼ 1.8 Hz, 1H, H5);
7.94 (s, 2H, 2ꢁ NH exchangeable with D2O); 8.36e8.42 (m, 3H,
H3þH1þOH exchangeable with D2O); 13C NMR (75 MHz, CDCl3): dC
25.2, 26.6, 38.4, 42.3, 44.6, 98.5, 111.2, 114.2, 115.2, 115.3, 116.9,
124.5, 124.7, 125.1, 128.2, 132.1, 134.6, 135.5, 146.2, 148.9, 149.4,
151.4, 169.1. HRMS calculated for C24H25ClN4O3 452.1615 [Mþ]
found 452.1607; Anal. Calcd (%) for: C, 63.64; H, 5.56; N, 12.37;
found C, 63.78; H, 5.69; N, 12.48.
White solid, yield 79%, m.p. 165e166 ꢀC; 1H NMR (300 MHz,
CDCl3): dH 1.27e1.31 (m, 4H, eCH2e); 1.91e1.97 (m, 2H, eCH2e);
2.52e2.55 (m, 2H, eCH2e); 3.31 (dd, J ¼ 6.1, 12.1 Hz, 2H, eCH2e);
3.35 (dd, J ¼ 6.3, 12.1 Hz, 2H, eCH2e); 3.75 (s, 2H, eCH2e); 5.12 (dd,
J ¼ 1.4, 10.3 Hz, 1H, eCH2e); 5.31 (dd, J ¼ 1.5, 17.2 Hz, 1H, eCH2e);
5.85e5.94 (m, 1H, eCHe); 6.36 (d, J ¼ 6.0 Hz, 1H, H2); 6.63 (d,
J ¼ 8.3 Hz, 1H, AreH); 6.96 (t, J ¼ 8.1 Hz, 1H, AreH); 7.23e7.29 (m,
2H, H4 þ AreH); 7.48 (dd, J ¼ 0.9, 7.8 Hz, 1H, AreH); 7.55 (s, 1H, NH
exchangeable with D2O); 7.74 (s, 1H, NH exchangeable with D2O);
7.91 (d, J ¼ 1.7 Hz, 1H, H5); 8.10 (d, J ¼ 9.0 Hz, 1H, H3); 8.31 (d,
J ¼ 6.0 Hz, 1H, H1); 13C NMR (75 MHz, CDCl3): dC 28.2, 28.5, 31.9,
32.7, 36.6, 39.9, 45.5, 98.7, 112.5, 114.1, 115.8, 116.1, 116.3, 122.9,
123.4,126.2,127.5,133.2,134.7,136.6,148.1,149.5,152.1,171.1. HRMS
calculated for C26H29ClN4O3 480.1928 [Mþ] found 480.1935; Anal.
Calcd (%) for: C, 64.92; H, 6.08; N, 11.65; found C, 64.86; H, 6.19; N,
11.53.
3.3.10. 5-Chloro-1-{2-[4-(7-Chloro-quinolin-4-ylamino)-
butylamino]-3-hydroxy-propyl}-1H-indole-2,3-dione (11j)
Pale yellow solid, yield 82%, m.p. 160e161 ꢀC; 1H NMR
(300 MHz, CDCl3): dH 1.65e1.77 (m, 4H, 2x eCH2e); 3.32 (d,
J ¼ 5.76 Hz, 2H, eCH2e); 3.35 (d, J ¼ 5.7 Hz, 2H, eCH2e); 3.78 (s, 2H,
eCH2e); 5.13 (dd, J ¼ 1.4, 10.3 Hz, 1H, eCH2e); 5.29 (dd, J ¼ 1.5,
17.2 Hz, 1H, eCH2e); 5.84e5.95 (m, 1H, eCHe); 6.51 (d, J ¼ 6.0 Hz,
1H, H2); 6.64 (d, J ¼ 8.3 Hz, 1H, AreH); 7.15e7.27 (m, 2H, ArH); 7.35
(d, J ¼ 9.0 Hz, 1H, H4); 7.69 (s, 1H, NH exchangeable with D2O); 7.85
3.3.14. 5-Chloro-1-{2-[6-(7-Chloro-quinolin-4-ylamino)-
hexylamino]-3-hydroxy-propyl}-1H-indole-2,3-dione (11n)
White solid, yield 80%, m.p. 153e154 ꢀC; 1H NMR (300 MHz,
CDCl3): dH 1.28e1.32 (m, 4H, eCH2e); 1.93e1.97 (m, 2H, eCH2e);
2.52e2.56 (m, 2H, eCH2e); 3.34 (dd, J ¼ 5.7 Hz, 12.0 Hz, 2H,
eCH2e); 3.36 (dd, J ¼ 5.7, 12.1 Hz, 2H, eCH2e); 3.75 (s, 2H, eCH2e);
5.13 (dd, J ¼ 1.4, 10.3 Hz, 1H, eCH2e); 5.31 (dd, J ¼ 1.5, 17.2 Hz, 1H,
eCH2e); 5.83e5.95 (m, 1H, eCHe); 6.35 (d, J ¼ 6.0 Hz, 1H, H2); 6.63
(d, J ¼ 8.3 Hz, 1H, AreH); 7.37 (d, J ¼ 9.0 Hz, 1H, H4); 7.43e7.49 (m,
2H, 2AreH); 7.53 (s, 1H, NH exchangeable with D2O); 7.74 (s, 1H, NH
exchangeable with D2O); 7.92 (d, J ¼ 1.76 Hz, 1H, H5); 8.10 (d,
J ¼ 9.04 Hz, 1H, H3); 8.32 (d, J ¼ 6.0 Hz, 1H, H1); 13C NMR (75 MHz,
CDCl3): dC 28.4, 29.1, 31.5, 33.1, 36.8, 39.4, 45.7, 99.1, 111.5, 113.7,
115.3, 116.5, 117.2, 117.8, 122.5, 123.7, 126.7, 127.8, 133.5, 134.1, 147.3,
148.2, 150.3, 152.5, 169.3. HRMS calculated for C26H28Cl2N4O3
514.1538 [Mþ] found 514.1545; Anal. Calcd (%) for: C, 60.59; H, 5.48;
N, 10.87; found C, 60.43; H, 5.59; N, 10.74.
(d, J ¼ 9.0 Hz,1H, H3); 7.91 (s,1H, H5); 8.62 (d, J ¼ 6.0 Hz,1H, H1); 13
C
NMR (75 MHz, CDCl3): dC 25.6, 26.9, 37.9, 42.7, 44.1, 99.1, 112.8,
113.7, 114.9, 115.7, 116.1, 124.6, 126.3, 127.3, 128.6, 133.3, 133.9, 135.1,
147.4, 148.5, 150.1, 151.9, 170.1. HRMS calculated for C24H24Cl2N4O3
486.1225 [Mþ] found 486.1232; Anal. Calcd (%) for: C, 59.14; H, 4.96;
N, 11.50; found C, 59.27; H, 4.83; N, 11.43.
3.3.11. 1-{2-[4-(7-Chloro-quinolin-4-ylamino)-butylamino]-3-
hydroxy-propyl}-5-methyl-1H-indole-2,3-dione (11k)
White solid, yield 83%, m.p. 145e146 ꢀC; 1H NMR (300 MHz,
CDCl3): dH 1.62e1.73 (m, 4H, 2x eCH2e); 2.29 (s, 3H, eCH3);

572
Nisha et al. / European Journal of Medicinal Chemistry 84 (2014) 566e573
3.3.15. 1-{2-[6-(7-Chloro-quinolin-4-ylamino)-hexylamino]-3-
hydroxy-propyl}-5-methyl-1H-indole-2,3-dione (11o)
3.4.2. 5-Chloro-1-{2-[4-(7-Chloro-quinolin-4-yl)-piperazin-1-yl]-
3-hydroxy-propyl}-1H-indole-2,3-dione (12b)
White solid, yield 85%, m.p. 155e156 ꢀC; 1H NMR (300 MHz,
CDCl3): dH 1.25e1.30 (m, 4H, 2ꢁ eCH2); 1.87e1.95 (m, 2H, eCH2e);
2.28 (s, 3H, eCH3); 2.58e2.63 (m, 2H, eCH2e); 3.31 (dd, J ¼ 5.8,
12.1 Hz, 2H, eCH2e); 3.35 (dd, J ¼ 5.7, 12.1 Hz, 2H, eCH2e); 3.87 (s,
2H, eCH2e); 5.07 (dd, J ¼ 1.4, 10.3 Hz, 1H, eCH2e); 5.28 (dd,
J ¼ 1.5, 17.2 Hz, 1H, eCH2e); 5.65e5.76 (m, 1H, eCHe); 6.25 (d,
J ¼ 6.0 Hz, 1H, H2); 6.54 (d, J ¼ 8.3 Hz, 1H, AreH); 6.98 (d,
J ¼ 9.0 Hz, 1H, H4); 7.37e7.41 (m, 2H, 2AreH); 7.40 (s, 1H, NH
exchangeable with D2O); 7.81 (s, 1H, NH exchangeable with D2O);
7.89 (d, J ¼ 1.7 Hz, 1H, H5); 8.13 (d, J ¼ 9.0 Hz, 1H, H3); 8.32 (d,
J ¼ 6.0 Hz, 1H, H1); 13C NMR (75 MHz, CDCl3): dC 21.5, 27.9, 28.6,
31.1, 33.3, 36.2, 40.0, 46.0, 98.9, 112.3, 114.9, 115.7, 116.4, 117.3, 122.1,
124.5, 125.8, 127.1, 133.9, 135.2, 136.9, 147.2, 148.7, 151.3, 152.1,
170.0. HRMS calculated for C27H31ClN4O3 494.2085 [Mþ] found
494.2077; Anal. Calcd (%) for: C, 65.51; H, 6.31; N, 11.32; found C,
65.67; H, 6.42; N, 11.43.
Pale yellow solid, yield 82%, m.p. 117e118 ꢀC; 1H NMR (300 MHz,
CDCl3): dH 2.76 (s, 4H, 2x eCH2e); 3.15 (s, 4H, 2x eCH2e); 3.30 (s,
2H, eCH2e); 4.96e5.15 (m, 2H, eCH2e); 5.87e5.99 (m, 1H, eCHe);
6.25 (d, J ¼ 5.1 Hz, 1H, H2); 6.32e6.37 (m, 1H, AreH); 7.13e7.24 (m,
2H, 2AreH); 7.34 (d, J ¼ 9.0 Hz, 1H, H4); 7.64e7.73 (m, 2H, H5þ eOH
exchangeable with D2O); 7.82 (d, J ¼ 8.8 Hz, 1H, H3); 8.17e8.25 (m,
2H, H1þ eOH exchangeable with D2O); 13C NMR (75 MHz, CDCl3):
dC 45.5, 54.1, 58.2, 99.1, 111.7, 113.2, 114.8, 115.1, 116.5, 117.7, 123.6,
124.3, 125.4, 127.3, 133.7, 136.1, 147.5, 148.7, 150.1, 152.5,169.1. HRMS
calculated for C24H22Cl2N4O3 484.1069 [Mþ] found 484.1060; Anal.
Calcd (%) for: C, 59.39; H, 4.57; N, 11.54; found C, 59.47; H, 4.69; N,
11.42.
3.4.3. 1-{2-[4-(7-Chloro-quinolin-4-yl)-piperazin-1-yl]-3-hydroxy-
propyl}-5-methyl-1H-indole-2,3-dione (12c)
Pale yellow solid, yield 82%, m.p.119e120 ꢀC; 1H NMR (300 MHz,
CDCl3): dH 2.29 (s, 3H, eCH3); 2.76 (s, 4H, 2x eCH2e); 3.18 (s, 4H, 2x
eCH2e); 3.29 (s, 2H, eCH2e); 4.95e5.15 (m, 2H, eCH2e);
5.85e5.96 (m,1H, eCHe); 6.22 (d, J ¼ 5.1 Hz,1H, H2); 6.34e6.37 (m,
1H, AreH); 7.11e7.16 (m, 1H, AreH); 7.25 (s, 1H, AreH); 7.39 (d,
J ¼ 9.0 Hz, 1H, H4); 7.98 (s, 1H, H5); 7.82 (d, J ¼ 9.0 Hz, 1H, H3);
8.19e8.22 (m, 2H, H1þ eOH exchangeable with D2O); 13C NMR
(75 MHz, CDCl3): dC 19.8, 46.1, 53.8, 57.4, 98.7, 112.8, 114.3, 116.5,
122.8, 124.9, 125.2, 125.9, 127.7, 132.8, 134.1, 135.8, 147.9, 148.2,
3.3.16. 1-{2-[6-(7-Chloro-quinolin-4-ylamino)-hexylamino]-3-
hydroxy-propyl}-5-fluoro-1H-indole-2,3-dione (11p)
White solid, yield 87%, m.p. 152e153 ꢀC; 1H NMR (300 MHz,
CDCl3): dH 1.28e1.34 (m, 4H, 2ꢁ eCH2e); 1.91e1.95 (m, 2H,
eCH2e); 2.48e2.52 (m, 2H, eCH2e); 3.41 (dd, J ¼ 5.8, 12.1 Hz, 2H,
eCH2e); 3.47 (dd, J ¼ 5.8, 12.1 Hz, 2H, eCH2e); 3.78 (s, 2H,
eCH2e); 5.11e5.32 (m, 2H, eCH2e); 5.91e5.98 (m, 1H, eCHe);
6.41 (d, J ¼ 6.0 Hz, 1H, H2); 6.69 (d, J ¼ 8.3 Hz, 1H, AreH); 7.31 (d,
J ¼ 9.0 Hz, 1H, H4); 7.38e7.43 (m, 2H, 2AreH); 7.52 (s, 1H, -NH
exchangeable with D2O); 7.67 (s, 1H, -NH exchangeable with D2O);
7.98 (d, J ¼ 1.8 Hz, 1H, H5); 8.17 (d, J ¼ 9.0 Hz, 1H, H3); 8.33 (d,
J ¼ 6.0 Hz, 1H, H1); 13C NMR (75 MHz, CDCl3): dC 28.3, 28.5, 31.7,
32.6, 36.9, 40.1, 45.1, 98.1, 112.1, 114.3, 115.7, 116.1, 116.9, 122.4,
124.3, 126.8, 127.9, 133.2, 134.5, 136.6, 148.4, 149.6, 150.6, 152.2,
171.2. HRMS calculated for C26H28ClFN4O3 498.1834 [Mþ] found
498.1829; Anal. Calcd (%) for: C, 62.58; H, 5.66; N, 11.23; found C,
62.67; H, 5.75; N, 11.34.
149.2, 151.7, 152.1, 171.2. HRMS calculated for
C25H25ClN4O3
464.1615 [Mþ] found 464.1608; Anal. Calcd (%) for: C, 64.58; H, 5.42;
N, 12.05; found C, 64.65; H, 5.59; N, 12.18.
3.4.4. 1-{2-[4-(7-Chloro-quinolin-4-yl)-piperazin-1-yl]-3-hydroxy-
propyl}-5-fluoro-1H-indole-2,3-dione (12d)
Pale yellow solid, yield 79%, m.p.131e132 ꢀC; 1H NMR (300 MHz,
CDCl3): dH 2.75 (s, 4H, 2x eCH2e); 3.17 (s, 4H, 2xeCH2e); 3.29 (s,
2H, eCH2e); 4.96e5.14 (m, 2H, eCH2e); 5.87e5.97 (m, 1H, eCHe);
6.29 (d, J ¼ 5.1 Hz, 1H, H2); 6.43e6.50 (m, 1H, AreH); 7.19e7.21 (m,
1H, AreH); 7.24e7.31 (m, 1H, AreH); 7.41 (d, J ¼ 9.0 Hz, 1H, H4);
7.64 (s, 1H, H5); 7.93 (d, J ¼ 8.8 Hz, 1H, H3); 8.35e8.40 (m, 2H, H1þ
eOH exchangeable with D2O); 13C NMR (75 MHz, CDCl3): dC 45.2,
53.8, 58.3, 99.3, 113.1, 114.2, 115.9, 116.5, 117.1, 123.8, 124.7, 126.9,
127.1, 133.6, 134.9, 136.1, 147.3, 148.4, 150.6, 152.8, 169.3. HRMS
calculated for C24H22ClFN4O3 468.1364 [Mþ] found 468.1372; Anal.
Calcd (%) for: C, 61.47; H, 4.73; N, 11.95; found C, 61.58; H, 4.65; N,
11.83.
3.4. General method for the preparation of isatin-4-piperazin-1-yl-
quinoline conjugates 12aed
The stirred solution of 1-Oxiranylmethyl isatin 3 (1 mmol), 4-
piperazin-1-yl-quinoline 10 (1 mmol) and catalytic amount of p-
toluene sulphonic acid in dry toluene was refluxed at 110 ꢀC for
12 h. On completion of the reaction, as monitored by TLC, water
(15 mL) was added to the reaction mixture and extracted with
chloroform (2 ꢁ 30 mL). Combined organic layers were dried over
anhydrous sodium sulphate and concentrated under reduce pres-
sure. Purification of reaction mixture thus obtained via column
chromatography using hexane:ethylacetate (3:2) mixture as eluent
resulted in the isolation of desired chimeras 12aed.
3.5. Methods for assessment of antimalarial activity of test
compounds
The W2 strain of P. falciparum was cultured in RPMI-1640 me-
dium with 10% human serum, following standard methods, and
parasites were synchronized with 5% D-sorbitol [50]. Beginning at
the ring stage, microwell cultures were incubated with different
concentrations of compounds for 48 h. The compounds were added
from DMSO stocks; the maximum concentration of DMSO used was
0.1%. Controls without inhibitors included 0.1% DMSO. After 48 h,
when control cultures had progressed to new rings, the culture
medium was removed, and cultures were incubated for 48 h with
1% formaldehyde in PBS, pH 7.4, at room temperature. Fixed para-
sites were then transferred to 0.1% Triton X-100 in PBS containing
1 nM YOYO-1 dye (Molecular Probes). Parasitaemia was deter-
mined from dot plots (forward scatter vs. fluorescence) acquired on
a FACSort flow cytometer using Cell Quest software (Beckton
Dickinson). IC50 values for growth inhibition were determined from
plots of percent control parasitaemia over inhibitor concentration
3.4.1. 1-{2-[4-(7-Chloro-quinolin-4-yl)-piperazin-1-yl]-3-hydroxy-
propyl}-1H-indole-2,3-dione (12a)
White solid, yield 87%, m.p. 121e122 ꢀC; 1H NMR (300 MHz,
CDCl3): dH 2.75 (s, 4H, 2x eCH2e); 3.18 (s, 4H, 2x eCH2e); 3.28 (s,
2H, eCH2e); 4.95e5.13 (m, 2H, eCH2e); 5.85e5.97 (m, 1H, eCHe);
6.35 (d, J ¼ 5.1 Hz, 1H, H2); 6.53e6.59 (m, 1H, AreH); 7.17 (dd,
J ¼ 2.4 Hz, 8.7 Hz, 1H, H4); 7.28e7.30 (m, 1H, AreH); 7.47e7.53 (m,
1H, AreH); 7.89 (d, J ¼ 2.4 Hz, 1H, H5); 7.96 (d, J ¼ 9.0 Hz, 1H, H3);
8.41 (d, J ¼ 5.1 Hz, 1H, H1); 13C NMR (75 MHz, CDCl3): dC 45.7, 53.1,
58.9, 98.1, 112.5, 114.4, 115.6, 116.2, 116.9, 122.8, 124.9, 126.2, 127.6,
133.2, 134.6, 136.5, 148.2, 149.6, 152.2, 171.1. HRMS calculated for
C
24H23ClN4O3 450.1459 [Mþ] found 450.1465; Anal. Calcd (%) for: C,
63.93; H, 5.14; N, 12.43; found C, 63.87; H, 5.27; N, 12.51.

Nisha et al. / European Journal of Medicinal Chemistry 84 (2014) 566e573
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Financial assistance from the University Grants Comission (UGC)
under a Rajiv Gandhi fellowship for SC/ST students (Nisha) is
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