Synthesis, characterization and antimicrobial screening of hybrid molecules containing quinoline, pyrimidine and morpholine analogues

Article abstract of DOI:10.1007/s12039-013-0371-4

In an attempt to find new bio-active molecules, a series of compounds N-(4-(2-chloroquinolin-3-yl)-6-(aryl)pyrimidin-2-yl)-2-morpholinoacetamides (5a-l) were synthesized by multistep reactions. Compounds were characterized by IR, NMR and mass spectra. Ant

Full text of DOI:10.1007/s12039-013-0371-4

c
J. Chem. Sci. Vol. 125, No. 2, March 2013, pp. 321–333. ꢀ Indian Academy of Sciences.
Synthesis, characterization and antimicrobial screening of hybrid
molecules containing quinoline, pyrimidine and morpholine analogues
N C DESAI∗, K M RAJPARA, V V JOSHI, H V VAGHANI and H M SATODIYA
Division of Medicinal Chemistry, Department of Chemistry (DST-FIST Sponsored Department),
Mahatma Gandhi Campus, Maharaja Krishnakumarsinhji Bhavnagar University, Bhavnagar 364 002, India
e-mail: dnisheeth@rediffmail.com
MS received 14 April 2012; revised 1 October 2012; accepted 6 November 2012
Abstract. In an attempt to find new bio-active molecules, a series of compounds N-(4-(2-chloroquinolin-
3-yl)-6-(aryl)pyrimidin-2-yl)-2-morpholinoacetamides (5a–l) were synthesized by multistep reactions. Com-
pounds were characterized by IR, NMR and mass spectra. Antimicrobial screening of title compounds
(5a–l) was carried out against Gram-positive bacteria (Staphylococcus aureus, Streptococcus pyogenes), Gram-
negative bacteria (Escherichia coli, Pseudomonas aeruginosa) and fungi (Candida albicans, Aspergillus niger,
Aspergillus clavatus) using serial broth dilution method. On the basis of statistical analysis, it is observed that
these compounds gave significant co-relation. Newly synthesized compounds 5e, 5f, 5g, 5i and 5l showed
significant potency against different microbial strains.
Keywords. Quinoline; pyrimidine; morpholine; antibacterial activity; antifungal activity; MIC.
1. Introduction
two new series of quinoline derivatives with possibly
a new mode of action. The structural similarity con-
cepts have been drawn in figure 1, which explains the
structural similarity of our new target compounds with
renowned drug chloroquine. Substituted aminopyrimi-
dine nuclei are common in marketed drugs such as anti-
atherosclerotic aronixil, anti-histaminic thonzylamine,
antianxielytic buspirone, antihypertensive minoxidil
and prazosin, anti-psoriatic enazadrem, and other
medicinally relevant compounds. Some notable bio-
logical activity of pyrimidine derivatives includes
adenosine receptor antagonists,10 kinase inhibitors,11
analgesic,12 anti-inflammatory,12 inhibitors of cyclin-
dependent kinases 1 and 2,13 calcium channel anta-
gonist,14 anti-histaminic15 and antitubercular16 activi-
ties. Promising diverse pharmacological activities are
shown by various N-functionalized morpholines. They
are reported to exert a number of important physiologi-
cal activities such as antibacterial, antifungal,17 platelet
aggregation inhibitors,18 antiemetic19 and antidepres-
sants.20 Comparative structure of drugs and reported
bio-active quinoline derivatives shown in figure 1.
As a result of remarkable pharmacological efficiency
of quinoline, pyrimidine and morpholine derivatives,
our studies have been focused towards the synthesis and
bio-evaluation of these derivatives by hybrid approach
for the search of new antimicrobials. Earlier, our
research group has synthesized quinoline derivatives
as potential antimicrobial agents.21,22 In continuation
A wide array of microorganisms including bacteria,
viruses, protozoa and fungi are becoming resistant to
drugs that are used to treat infections. This resistance
is a major obstacle to the treatment of infectious di-
seases worldwide. Faced with the extent of antimicro-
bial drug resistance and the dwindling number of effec-
tive antimicrobial drugs, the World Health Organization
(WHO) has considered this situation to be one of the
greatest threats to human health. Moreover, problems
of multi-drug resistant microorganisms have reached
an alarming level in many countries around the world.
Therefore, it is necessary to have antimicrobial agents
with improved potency. In the present research work,
we have incorporated design of new compounds and
development of hybrid molecules through the com-
bination of different pharmacophores in one hetero-
cyclic congerners, which may lead to compounds with
potential antimicrobial activity.
The quinoline skeleton is often used for the design of
many synthetic compounds with diverse pharmaceuti-
cal properties. The quinoline ring is endowed with va-
rious activities, such as antituberculosis,1 antimalarial,2
anti-inflammatory,3 anticancer,4 antibiotic,5 antihyper-
tensive,6 tyrokinase PDGF-RTK inhibiting agents,7 and
anti-HIV.8,9 Keeping this in view, we have designed
∗For correspondence
321

322
N C Desai et al.
O-
H2N
N+
NH2
O
N
HN
O
N
O
N
N
H
N
N
F
Cl
N
O
Linezolid
Chloroquine
Minoxidil
Cl
N
R
N
N
HN
O
N
O
(5a-l)
Present work
Figure 1. Comparative structure of drugs and reported bio-active quinoline derivatives.
to this, we have synthesized N-(4-(2-chloroquinolin- 2.3 General procedure for the preparation of 4-(aryl)-
3-yl)-6-(aryl)pyrimidin-2-yl)-2-morpholinoacetamides
(5a–l) derivatives and screened for their antimicro-
bial activity. The synthesized compounds (5a–l) were
characterized by IR, NMR and mass spectra.
6-(2-chloroquinolin-3-yl)pyrimidin-2-amine (3a–l)
A mixture of compounds (2a–l) (0.01 mol) and guani-
dine nitrate (0.01 mol) in ethanol (99.9%) was refluxed,
while a solution of sodium hydroxide (0.05 mol) in
water was added portion-wise for 2 h. Refluxing was
continued for a further 10 h and the mixture was poured
into ice-cold water. The formed solid was separated by
filtration. The crude product was dried and crystallized
from ethanol (95%).
2. Experimental
2.1 Preparation of 2-chloroquinoline-3-carbaldehyde
(1)
2.3a 4-(2-Chloroquinolin-3-yl)-6-phenylpyrimidin-2-
amine (3a): Light brown crystals, yield: 70%; m.p.:
177–179◦C; IR (KBr) νmax/cm−1: 3450, 3344 (NH2),
3070 (C-H, aromatic), 1577 (C=N), 1515 (C=C), 725
To a solution of acetanilide (5 mmol) in dry DMF
(15 mmol) at 0–5◦C with stirring POCl3 (60 mmol)
was added drop-wise and the mixture stirred at 100◦C
for time ranging between 4 and 16 h. The mixture was
poured into crushed ice, stirred for 5 min and the result-
ing solid filtered, washed well with water and dried. The
yellow crystals formed were filtered off, washed with
water and crystallized from ethyl acetate.23
1
(C-Cl); H NMR (300 MHz, DMSO-d6, δ, ppm): 5.65
(s, 2H, NH2, D2O exch.), 6.56 (s, 1H, pyrimidine-
H), 7.39–8.54 (m, 10H, Ar-H); 13C NMR (100 MHz,
DMSO-d6, δ, ppm): 103.5 (C5), 126.8–143.5 (C-
arom), 152.3 (C-Cl, quinoline), 163.1 (C2), 164.8 (C6),
165.2 (C4); LCMS (m/z): 332 (M+); Anal. Calcd.
For C19H13ClN4: C-68.57, H-3.94, N-16.84; Found:
C-68.64, H-3.88, N-16.76%.
2.2 General procedure for the preparation of 3-(2-
chloroquinolin-3-yl)-1-(aryl)prop-2-en-1-ones (2a–l)
2.3b 2-(2-Amino-6-(2-chloroquinolin-3-yl)pyrimidin-
4-yl)phenol (3b): Light yellow crystals, yield: 78%;
m.p.: 193–195◦C; IR (KBr) νmax/cm−1:3417 (OH),
3452, 3361 (NH2), 3063 (C-H, aromatic), 1570 (C=N),
1511 (C=C), 730 (C-Cl); 1H NMR (300 MHz, DMSO-
d6, δ, ppm): 5.60 (s, 2H, NH2, D2O exch.), 6.59 (s,
1H, pyrimidine-H), 6.98–8.50 (m, 9H, Ar-H), 9.11
A mixture of 2-chloroquinoline-3-carbaldehyde (1)
(0.01 mol) and substituted acetophenones (0.01 mol)
was stirred in ethanolic sodium hydroxide for 24 h at
room temperature. The yellow crystals formed were
filtered off, washed with water and crystallized from
ethanol (95%).24

Synthesis and antimicrobial screening of quinoline analogues
323
(s, 1H, OH, D2O exch.); 13C NMR (100 MHz, DMSO- (NH2), 3074 (C-H, aromatic), 1558 (C=N), 1514
d6, δ, ppm): 103.8 (C-5), 121.5–149.5 (C-arom), (C=C), 751 (C-Cl); 1H NMR (300 MHz, DMSO-
152.7 (C-Cl, quinoline), 163.4 (C-2), 164.6 (C-6), d6, δ, ppm): 5.70 (s, 2H, NH2, D2O exch.), 6.66 (s,
165.2 (C-4); LCMS (m/z): 348 (M+); Anal. Calcd. 1H, pyrimidine-H), 7.52–8.49 (m, 9H, Ar-H); 13C
For C19H13ClN4O: C-65.43, H-3.76, N-16.06; Found: NMR (100 MHz, DMSO-d6, δ, ppm): 103.6 (C-5),
C-65.51, H-3.82, N-16.00%.
127.0–144.3 (C-arom), 152.5 (C-Cl, quinoline), 163.4
(C-2), 164.1 (C-6), 165.7 (C-4); LCMS (m/z): 366
(M+); Anal. Calcd. For C19H12Cl2N4: C-62.14, H-3.29,
N-15.26; Found: C-62.06, H-3.22, N-15.32%.
2.3c 4-(2-Amino-6-(2-chloroquinolin-3-yl)pyrimidin-
4-yl)phenol (3c): Light orange crystals, yield: 74%;
m.p.: 167–169◦C; IR (KBr) νmax/cm−1:3411 (OH),
3440, 3352 (NH2), 3072 (C-H, aromatic), 1575 (C=N),
1516 (C=C), 724 (C-Cl); 1H NMR (300 MHz, DMSO-
d6, δ, ppm): 5.62 (s, 2H, NH2, D2O exch.), 6.62 (s,
1H, pyrimidine-H), 6.84–8.48 (m, 9H, Ar-H), 9.11 (s,
1H, OH, D2O exch.); 13C NMR (100 MHz, DMSO-d6,
δ, ppm): 104.1 (C-5), 116.7–156.3 (C-arom), 152.4
(C-Cl, quinoline), 163.1 (C-2), 164.5 (C-6), 165.7
(C-4); LCMS (m/z): 348 (M+); Anal. Calcd. For
C19H13ClN4O: C-65.43, H-3.76, N-16.06; Found:
C-65.35, H-3.72, N-16.15%.
2.3g 4-(2-Chloroquinolin-3-yl)-6-(2-fluorophenyl)
pyrimidin-2-amine (3g): Light grey crystals, yield:
80%; m.p.: 190–191◦C; IR (KBr) νmax/cm−1: 3433,
3320 (NH2), 3056 (C-H, aromatic), 1567 (C=N), 1523
1
(C=C), 1145 (C-F), 743 (C-Cl); H NMR (300 MHz,
DMSO-d6, δ, ppm): 5.77 (s, 2H, NH2, D2O exch.),
6.75 (s, 1H, pyrimidine-H), 7.25–8.50 (m, 9H, Ar-H);
13C NMR (100 MHz, DMSO-d6, δ, ppm): 104.2 (C-5),
113.9–157.5 (C-arom), 153.1 (C-Cl, quinoline), 163.8
(C-2), 164.4 (C-6), 165.2 (C-4); LCMS (m/z): 350
(M+); Anal. Calcd. For C19H12ClFN4: C-65.06, H-3.45,
N-15.97; Found: C-65.10, H-3.51, N-15.90%.
2.3d 4-(2-Chloroquinolin-3-yl)-6-(4-methoxyphenyl)
pyrimidin-2-amine (3d): Light reddish brown crys-
tals, yield: 72%; m.p.: 179–181◦C; IR (KBr) νmax/cm−1:
3439, 3362 (NH2), 3067 (C-H, aromatic), 2925 (C-H,
2.3h 4-(2-Chloroquinolin-3-yl)-6-(3-fluorophenyl)
pyrimidin-2-amine (3h): Light brown crystals, yield:
77%; m.p.: 175–176◦C; IR (KBr) νmax/cm−1: 3443,
3361 (NH2), 3073 (C-H, aromatic), 1573 (C=N), 1528
1
OCH3), 1571 (C=N), 1520 (C=C), 740 (C-Cl); H
NMR (300 MHz, DMSO-d6, δ, ppm): 3.68 (s, 3H,
OCH3), 5.68 (s, 2H, NH2, D2O exch.), 6.71 (s, 1H,
pyrimidine-H), 7.08–8.45 (m, 9H, Ar-H); 13C NMR
(100 MHz, DMSO-d6, δ, ppm): 56.4 (-OCH3), 104.1
(C-5), 114.5–160.7 (C-arom), 152.5 (C-Cl, quinoline),
163.7 (C-2), 164.3 (C-6), 165.8 (C-4); LCMS (m/z):
362 (M+); Anal. Calcd. For C20H15ClN4O: C-66.21,
H-4.17, N-15.44; Found: C-66.14, H-4.25, N-15.52%.
1
(C=C), 1137 (C-F), 733 (C-Cl); H NMR (300 MHz,
DMSO-d6, δ, ppm): 5.68 (s, 2H, NH2, D2O exch.),
6.79 (s, 1H, pyrimidine-H), 7.15–8.53 (m, 9H, Ar-H);
13C NMR (100 MHz, DMSO-d6, δ, ppm): 103.9 (C-5),
116.4–161.7 (C-arom), 152.8 (C-Cl, quinoline), 163.6
(C-2), 164.8 (C-6), 165.2 (C-4); LCMS (m/z): 350
(M+); Anal. Calcd. For C19H12ClFN4: C-65.06, H-3.45,
N-15.97; Found: C-65.00, H-3.53, N-16.03%.
2.3e 4-(2-Chlorophenyl)-6-(2-chloroquinolin-3-yl)
pyrimidin-2-amine (3e): Light yellow crystals, yield:
70%; m.p.: 187–189◦C; IR (KBr) νmax/cm−1: 3443,
3354 (NH2), 3061 (C-H, aromatic), 1566 (C=N), 1513
(C=C), 748 (C-Cl); 1H NMR (300 MHz, DMSO-
d6, δ, ppm): 5.72 (s, 2H, NH2, D2O exch.), 6.69 (s,
1H, pyrimidine-H), 7.40–8.48 (m, 9H, Ar-H); 13C
NMR (100 MHz, DMSO-d6, δ, ppm): 103.6 (C-5),
127.0–144.3 (C-arom), 152.7 (C-Cl, quinoline), 163.3
(C-2), 164.7 (C-6), 165.2 (C-4); LCMS (m/z): 366
(M+); Anal. Calcd. For C19H12Cl2N4: C-62.14, H-3.29,
N-15.26; Found: C-62.22, H-3.37, N-15.34%.
2.3i 4-(2-Chloroquinolin-3-yl)-6-(4-fluorophenyl)
pyrimidin-2-amine (3i): Light reddish crystals, yield:
78%; m.p.: 178–180◦C; IR (KBr) νmax/cm−1: 3452,
3345 (NH2), 3071 (C-H, aromatic), 1555 (C=N), 1510
1
(C=C), 1145 (C-F), 743 (C-Cl); H NMR (300 MHz,
DMSO-d6, δ, ppm): 5.72 (s, 2H, NH2, D2O exch.),
6.69 (s, 1H, pyrimidine-H), 7.40–8.48 (m, 9H, Ar-H);
13C NMR (100 MHz, DMSO-d6, δ, ppm): 104.4 (C-5),
115.6–163.1 (C-arom), 152.8 (C-Cl, quinoline), 163.2
(C-2), 164.8 (C-6), 165.4 (C-4); LCMS (m/z): 350
(M+); Anal. Calcd. For C19H12ClFN4: C-65.06, H-3.45,
N-15.97; Found: C-65.14, H-3.51, N-15.88%.
2.3f 4-(4-Chlorophenyl)-6-(2-chloroquinolin-3-yl)
pyrimidin-2-amine (3f): Yellow crystals, yield: 77%; 2.3j 4-(2-Chloroquinolin-3-yl)-6-(2-nitrophenyl)
m.p.: 201–203◦C; IR (KBr) νmax/cm−1: 3450, 3322 pyrimidin-2-amine (3j): Dark yellow crystals, yield:

324
N C Desai et al.
73%; m.p.: 186–188◦C; IR (KBr) νmax/cm−1: 3461, crystals, yield: 70%; m.p.: 197–199◦C; IR (KBr)
3331 (NH2), 3056 (C-H, aromatic), 1567 (C=N), νmax/cm−1: 3350, 3237 (NH), 3059 (C-H, aromatic),
1521 (C=C), 1451, 1357 (NO2), 751 (C-Cl); 1H NMR 2860 (C-H, CH2), 1684 (C=O), 1612 (C=N), 1578
1
(300 MHz, DMSO-d6, δ, ppm): 5.72 (s, 2H, NH2, D2O (C=C), 767 (C-Cl); H NMR (300 MHz, DMSO-d6,
exch.), 6.69 (s, 1H, pyrimidine-H), 7.58–8.57 (m, 9H, δ, ppm): 4.11 (s, 2H, CH2), 6.92 (s, 1H, pyrimidine-
Ar-H); 13C NMR (100 MHz, DMSO-d6, δ, ppm): 104.4 H), 7.43–8.50 (m, 10H, Ar-H), 9.76 (s, 1H, NH, D2O
(C-5), 123.6–149.4 (C-arom), 153.1 (C-Cl, quinoline), exch.); 13C NMR (100 MHz, DMSO-d6, δ, ppm): 60.4
163.6 (C-2), 164.4 (C-6), 165.9 (C-4); LCMS (m/z): (CH2), 101.2 (C-5), 126.2–145.6 (C-arom), 153.6 (C-
377 (M+); Anal. Calcd. For C19H12ClN5O2: C-60.41, Cl, quinoline), 162.3 (C-2), 164.1 (C-6), 165.4 (C-4),
H-3.20, N-18.54; Found: C-60.33, H-3.26, N-18.62%.
171.2 (C=O); LCMS (m/z): 408 (M+); Anal. Calcd.
For C21H14Cl2N4O: C-61.63, H-3.45, N-13.69; Found:
C-61.69, H-3.52, N-13.62%.
2.3k 4-(2-Chloroquinolin-3-yl)-6-(3-nitrophenyl)
pyrimidin-2-amine (3k): Orange yellow crystals,
yield: 75%; m.p.: 211–213◦C; IR (KBr) νmax/cm−1:
3456, 3321 (NH2), 3067 (C-H, aromatic), 1574 (C=N),
1518 (C=C), 1452, 1360 (NO2), 743 (C-Cl); 1H NMR
(300 MHz, DMSO-d6, δ, ppm): 5.77 (s, 2H, NH2, D2O
exch.), 6.63 (s, 1H, pyrimidine-H), 7.61–8.67 (m, 9H,
Ar-H); 13C NMR (100 MHz, DMSO-d6, δ, ppm): 103.8
(C-5), 122.7–148.7 (C-arom), 152.6 (C-Cl, quinoline),
163.4 (C-2), 164.7 (C-6), 165.6 (C-4); LCMS (m/z):
377 (M+); Anal. Calcd. For C19H12ClN5O2: C-60.41,
H-3.20, N-18.54; Found: C-60.46, H-3.16, N-18.48%.
2.4b 2-Chloro-N-(4-(2-chloroquinolin-3-yl)-6-(2-
hydroxyphenyl)pyrimidin-2-yl)acetamide (4b): Light
brown crystals, yield: 70%; m.p.: 226–228◦C; IR (KBr)
νmax/cm−1: 3418 (OH), 3340, 3230 (NH), 3078 (C-
H, aromatic), 2869 (C-H, CH2), 1686 (C=O), 1614
(C=N), 1567 (C=C), 773 (C-Cl); 1H NMR (300 MHz,
DMSO-d6, δ, ppm): 4.16 (s, 2H, CH2), 6.89 (s, 1H,
pyrimidine-H), 7.00–8.46 (m, 9H, Ar-H), 9.14 (s, 1H,
OH, D2O exch.), 9.76 (s, 1H, NH, D2O exch.); 13C
NMR (100 MHz, DMSO-d6, δ, ppm): 60.3 (CH2),
101.2 (C-5), 117.5–154.3 (C-arom), 153.4 (C-Cl,
quinoline), 162.0 (C-2), 164.4 (C-6), 165.1 (C-4),
171.5 (C=O); LCMS (m/z): 424 (M+); Anal. Calcd.
For C21H14Cl2N4O2: C-59.31, H-3.32, N-13.17; Found:
C-59.37, H-3.41, N-13.12%.
2.3l 4-(2-Chloroquinolin-3-yl)-6-(4-nitrophenyl)
pyrimidin-2-amine (3l): Yellow crystals, yield: 82%;
m.p.: 192–194◦C; IR (KBr) νmax/cm−1: 3441, 3334
(NH2), 3076 (C-H, aromatic), 1568 (C=N), 1518
(C=C), 1459, 1348 (NO2), 740 (C-Cl); 1H NMR
(300 MHz, DMSO-d6, δ, ppm): 5.74 (s, 2H, NH2, D2O
exch.), 6.67 (s, 1H, pyrimidine-H), 7.60–8.53 (m, 9H,
Ar-H); 13C NMR (100 MHz, DMSO-d6, δ, ppm): 104.4
(C-5), 124.2–147.6 (C-arom), 153.4 (C-Cl, quinoline),
163.6 (C-2), 164.3 (C-6), 165.7 (C-4); LCMS (m/z):
377 (M+); Anal. Calcd. For C19H12ClN5O2: C-60.41,
H-3.20, N-18.54; Found: C-60.47, H-3.11, N-18.61%.
2.4c 2-Chloro-N-(4-(2-chloroquinolin-3-yl)-6-(4-
hydroxyphenyl)pyrimidin-2-yl)acetamide (4c): Light
brown crystals, yield: 71%; m.p.: 168–170◦C; IR (KBr)
νmax/cm−1: 3424 (OH), 3347, 3219 (NH), 3070 (C-
H, aromatic), 2874 (C-H, CH2), 1680 (C=O), 1610
(C=N), 1514 (C=C), 768 (C-Cl); 1H NMR (300 MHz,
DMSO-d6, δ, ppm): 4.09 (s, 2H, CH2), 6.93 (s, 1H,
pyrimidine-H), 6.78–8.50 (m, 9H, Ar-H), 9.11 (s, 1H,
OH, D2O exch.), 9.73 (s, 1H, NH, D2O exch.); 13C
NMR (100 MHz, DMSO-d6, δ, ppm): 60.6 (CH2),
101.1 (C-5), 115.8–157.4 (C-arom), 153.2 (C-Cl,
quinoline), 162.4 (C-2), 164.1 (C-6), 165.6 (C-4),
171.7 (C=O); LCMS (m/z): 424 (M+); Anal. Calcd.
For C21H14Cl2N4O2: C-59.31, H-3.32, N-13.17; Found:
C-59.39, H-3.28, N-13.25%.
2.4 General procedure for the preparation of 2-chloro-
N-(4-(2-chloroquinolin-3-yl)-6-(aryl)pyrimidin-2-yl)
acetamides (4a–l)
Equimolar amount of compounds (3a–l) (0.01 mol)
and chloroacetyl chloride (0.01 mol) in chloroform was
refluxed in the presence of catalytic amount of triethyl-
amine for about 12 h. Excess of solvent was removed
under reduced pressure and the residue was stirred with
water. The crude product was dried and crystallized
from ethanol (95%).
2.4d 2-Chloro-N-(4-(2-chloroquinolin-3-yl)-6-(4-
methoxyphenyl)pyrimidin-2-yl)acetamide (4d): Light
brown crystals, yield: 68%; m.p.: 177–179◦C; IR (KBr)
νmax/cm−1: 3360, 3238 (NH), 3062 (C-H, aromatic),
2876, 2927 (C-H, CH2, CH3), 1685 (C=O), 1613
(C=N), 1515 (C=C), 775 (C-Cl); 1H NMR (300 MHz,
2.4a 2-Chloro-N-(4-(2-chloroquinolin-3-yl)-6-
phenylpyrimidin-2-yl)acetamide (4a): Light yellow

Synthesis and antimicrobial screening of quinoline analogues
325
DMSO-d6, δ, ppm): 3.56 (s, 3H, OCH3), 4.13 (s, 165.2 (C-4), 171.4 (C=O); LCMS (m/z): 426 (M+);
2H, CH2), 6.84 (s, 1H, pyrimidine-H), 7.09–8.50 (m, Anal. Calcd. For C21H13Cl2FN4O: C-59.03, H-3.07,
9H, Ar-H), 9.69 (s, 1H, NH, D2O exch.); 13C NMR N-13.11; Found: C-59.11, H-3.02, N-13.15%.
(100 MHz, DMSO-d6, δ, ppm): 55.3 (OCH3), 60.1
(CH2), 101.3 (C-5), 113.8–160.4 (C-arom), 154.1 (C-
2.4h 2-Chloro-N-(4-(2-chloroquinolin-3-yl)-6-(3-
Cl, quinoline), 162.5 (C-2), 164.0 (C-6), 165.1 (C-4),
fluorophenyl)pyrimidin-2-yl)acetamide (4h): Light
171.4 (C=O); LCMS (m/z): 438 (M+); Anal. Calcd.
reddish brown crystals, yield: 68%; m.p.: 156–157◦C;
For C22H16Cl2N4O2: C-60.15, H-3.67, N-12.75; Found:
IR (KBr) νmax/cm−1: 3355, 3256 (NH), 3070 (C-H,
C-60.21, H-3.71, N-12.80%.
aromatic), 2869 (C-H, CH2), 1683 (C=O), 1581
(C=N), 1516 (C=C), 1149 (C-F), 765 (C-Cl); 1H NMR
(300 MHz, DMSO-d6, δ, ppm): 4.26 (s, 2H, CH2),
6.91 (s, 1H, pyrimidine-H), 7.17–8.52 (m, 9H, Ar-H),
9.73 (s, 1H, NH, D2O exch.); 13C NMR (100 MHz,
DMSO-d6, δ, ppm): 60.7 (CH2), 101.5 (C-5), 114.6–
161.7 (C-arom), 153.4 (C-Cl, quinoline), 162.3 (C-2),
164.1 (C-6), 165.4 (C-4), 171.5 (C=O); LCMS (m/z):
426 (M+); Anal. Calcd. For C21H13Cl2FN4O: C-59.03,
H-3.07, N-13.11; Found: C-59.08, H-3.13, N-13.07%.
2.4e 2-Chloro-N-(4-(2-chlorophenyl)-6-(2-chloroquinolin-
3-yl)pyrimidin-2-yl)acetamide (4e): Light yellow
crystals, yield: 72%; m.p.: 199–201◦C; IR (KBr)
νmax/cm−1: 3361, 3237 (NH), 3074 (C-H, aromatic),
2869 (C-H, CH2), 1683 (C=O), 1610 (C=N), 1534
1
(C=C), 756 (C-Cl); H NMR (300 MHz, DMSO-d6,
δ, ppm): 4.20 (s, 2H, CH2), 6.88 (s, 1H, pyrimidine-
H), 7.30–8.55 (m, 9H, Ar-H), 9.74 (s, 1H, NH, D2O
exch.); 13C NMR (100 MHz, DMSO-d6, δ, ppm): 60.6
(CH2), 101.1 (C-5), 127.3–146.1 (C-arom), 153.6 (C-
Cl, quinoline), 162.2 (C-2), 164.5 (C-6), 165.7 (C-4),
171.4 (C=O); LCMS (m/z): 442 (M+); Anal. Calcd.
For C21H13Cl3N4O: C-56.84, H-2.95, N-12.63; Found:
C-56.78, H-2.88, N-12.71%.
2.4i 2-Chloro-N-(4-(2-chloroquinolin-3-yl)-6-(4-
fluorophenyl)pyrimidin-2-yl)acetamide
(4i): Light
brown crystals, yield: 69%; m.p.: 188–190◦C; IR (KBr)
νmax/cm−1: 3345, 3254 (NH), 3072 (C-H, aromatic),
2872 (C-H, CH2), 1690 (C=O), 1575 (C=N), 1516
1
(C=C), 1154 (C-F), 776 (C-Cl); H NMR (300 MHz,
DMSO-d6, δ, ppm): 4.29 (s, 2H, CH2), 6.94 (s, 1H,
pyrimidine-H), 7.34–8.51 (m, 9H, Ar–H), 9.77 (s, 1H,
NH, D2O exch.); 13C NMR (100 MHz, DMSO-d6, δ,
ppm): 60.4 (CH2), 101.5 (C-5), 115.7–162.6 (C-arom),
152.7 (C–Cl, quinoline), 162.1 (C-2), 164.5 (C-6),
165.7 (C-4), 171.4 (C=O); LCMS (m/z): 426 (M+);
Anal. Calcd. For C21H13Cl2FN4O: C-59.03, H-3.07,
N-13.11; Found: C-58.97, H-3.13, N-13.18%.
2.4f 2-Chloro-N-(4-(4-chlorophenyl)-6-(2-chloroquinolin-
3-yl)pyrimidin-2-yl)acetamide (4f): Light yellow
crystals, yield: 67%; m.p.: 164–166◦C; IR (KBr)
νmax/cm−1: 3371, 3235 (NH), 3079 (C-H, aromatic),
2866 (C-H, CH2), 1684 (C=O), 1600 (C=N), 1519
1
(C=C), 762 (C-Cl); H NMR (300 MHz, DMSO-d6,
δ, ppm): 4.29 (s, 2H, CH2), 6.92 (s, 1H, pyrimidine-
H), 7.45–8.53 (m, 9H, Ar-H), 9.64 (s, 1H, NH, D2O
exch.); 13C NMR (100 MHz, DMSO-d6, δ, ppm): 60.7
(CH2), 101.5 (C-5), 127.7–145.7 (C-arom), 153.0 (C-
Cl, quinoline), 162.7 (C-2), 164.3 (C-6), 165.5 (C-4),
171.9 (C=O); LCMS (m/z): 442 (M+); Anal. Calcd.
For C21H13Cl3N4O: C-56.84, H-2.95, N-12.63; Found:
C-56.89, H-2.99, N-12.70%.
2.4j 2-Chloro-N-(4-(2-chloroquinolin-3-yl)-6-(2-
nitrophenyl)pyrimidin-2-yl)acetamide (4j): Orange
yellow crystals, yield: 66%; m.p.: 167–169◦C; IR
(KBr) νmax/cm−1: 3365, 3283 (NH), 3058 (C-H, aro-
matic), 2853 (C-H, CH2), 1688 (C=O), 1580 (C=N),
1522 (C=C), 1488, 1360 (NO2), 770 (C-Cl); 1H NMR
(300 MHz, DMSO-d6, δ, ppm): 4.24 (s, 2H, CH2),
6.86 (s, 1H, pyrimidine-H), 7.53–8.57 (m, 9H, Ar-H),
9.73 (s, 1H, NH, D2O exch.); 13C NMR (100 MHz,
DMSO-d6, δ, ppm): 60.5 (CH2), 101.6 (C-5), 124.2–
147.4 (C-arom), 152.2 (C-Cl, quinoline), 162.4 (C-2),
164.2 (C-6), 165.8 (C-4), 171.6 (C=O); LCMS (m/z):
453 (M+); Anal. Calcd. For C21H13Cl2N5O3: C-55.52,
H-2.88, N-15.42; Found: C-55.57, H-2.93, N-15.36%.
2.4g 2-Chloro-N-(4-(2-chloroquinolin-3-yl)-6-(2-
fluorophenyl)pyrimidin-2-yl)acetamide (4g): Light
brown crystals, yield: 71%; m.p.: 182–184◦C; IR (KBr)
νmax/cm−1: 3351, 3242 (NH), 3065 (C-H, aromatic),
2865 (C-H, CH2), 1690 (C=O), 1589 (C=N), 1523
1
(C=C), 1150 (C-F), 771 (C–Cl); H NMR (300 MHz,
DMSO-d6, δ, ppm): 4.28 (s, 2H, CH2), 6.94 (s, 1H,
pyrimidine-H), 7.25–8.58 (m, 9H, Ar-H), 9.67 (s, 1H,
NH, D2O exch.); 13C NMR (100 MHz, DMSO-d6, δ,
ppm): 60.2 (CH2), 101.4 (C-5), 114.7–157.4 (C-arom), 2.4k 2-Chloro-N-(4-(2-chloroquinolin-3-yl)-6-(3-
152.6 (C–Cl, quinoline), 162.2 (C-2), 164.5 (C-6), nitrophenyl)pyrimidin-2-yl)acetamide (4k): Yellow

326
N C Desai et al.
crystals, yield: 70%; m.p.: 180–182◦C; IR (KBr) NMR (100 MHz, DMSO-d6, δ, ppm): 45.3 (N(CH2)2),
νmax/cm−1: 3358, 3262 (NH), 3076 (C-H, aromatic), 63.2 (CH2), 67.3 (O(CH2)2), 101.1 (C-5), 126.4–145.2
2863 (C-H, CH2), 1692 (C=O), 1576 (C=N), 1510 (C-arom), 151.8 (C-Cl, quinoline), 163.4 (C-2), 164.5
(C=C), 1485, 1358 (NO2), 785 (C-Cl); 1H NMR (C-6), 165.3 (C-4), 173.1 (C=O); LCMS (m/z):
(300 MHz, DMSO-d6, δ, ppm): 4.25 (s, 2H, CH2), 459 (M+); Anal. Calcd. For C25H22ClN5O2: C-65.29,
6.92 (s, 1H, pyrimidine-H), 7.52–8.57 (m, 9H, Ar-H), H-4.82, N-15.23; Found: C-65.34, H-4.87, N-15.16%.
9.69 (s, 1H, NH, D2O exch.); 13C NMR (100 MHz,
DMSO-d6, δ, ppm): 60.7 (CH2), 101.5 (C-5), 103.2–
2.5b N-(4-(2-chloroquinolin-3-yl)-6-(2-hydroxyphenyl)
148.3 (C-arom), 152.8 (C–Cl, quinoline), 162.0 (C-2),
pyrimidin-2-yl)-2-morpholinoacetamide (5b): Light
164.4 (C-6), 165.9 (C-4), 171.7 (C=O); LCMS (m/z):
yellow crystal, yield: 53%; m.p.: 164–166◦C; IR (KBr)
νmax/cm−1: 3412 (OH), 3310, 3236 (NH), 3068 (C-H,
aromatic), 2964, 2929, 2854 (C-H, CH2), 1682 (C=O),
1589 (C=N), 1575 (C=C), 1357 (C-N), 1230 (C-O),
453 (M+); Anal. Calcd. For C21H13Cl2N5O3: C-55.52,
H-2.88, N-15.42; Found: C-55.44, H-2.80, N-15.47%.
1
726 (C-Cl); H NMR (300 MHz, DMSO-d6, δ, ppm):
2.4l 2-Chloro-N-(4-(2-chloroquinolin-3-yl)-6-(4-
nitrophenyl)pyrimidin-2-yl)acetamide (4l): Dark yel-
low crystal, yield: 73%; m.p.: 224–226◦C; IR (KBr)
νmax/cm−1: 3369, 3283 (NH), 3088 (C-H, aromatic),
2862 (C-H, CH2), 1686 (C=O), 1582 (C=N), 1522
(C=C), 1478, 1350 (NO2), 790 (C-Cl); 1H NMR
(300 MHz, DMSO-d6, δ, ppm): 4.29 (s, 2H, CH2),
6.95 (s, 1H, pyrimidine-H), 7.56–8.58 (m, 9H, Ar-H),
9.79 (s, 1H, NH, D2O exch.); 13C NMR (100 MHz,
DMSO-d6, δ, ppm): 60.5 (CH2), 101.3 (C-5), 124.1–
147.4 (C-arom), 152.4 (C-Cl, quinoline), 162.2 (C-2),
164.5 (C-6), 165.8 (C-4), 171.4 (C=O); LCMS (m/z):
453 (M+); Anal. Calcd. For C21H13Cl2N5O3: C-55.52,
H-2.88, N-15.42; Found: C-55.48, H-2.82, N-15.37%.
2.65 (t, 4H, J = 4.9 Hz, N(CH2)2), 3.45 (t, 4H, J =
4.7 Hz, O(CH2)2), 3.94 (s, 2H, CH2), 6.78 (s, 1H,
pyrimidine-H), 7.01–8.42 (m, 9H, Ar-H), 9.21 (s, 1H,
OH, D2O exch.), 10.18 (s, 1H, NH, D2O exch.); 13C
NMR (100 MHz, DMSO-d6, δ, ppm): 45.5 (N(CH2)2),
63.8 (CH2), 67.3 (O(CH2)2), 101.7 (C-5), 117.6–154.4
(C-arom), 151.6 (C-Cl, quinoline), 163.2 (C-2), 164.3
(C-6), 165.5 (C-4), 173.3 (C=O); LCMS (m/z):
475 (M+); Anal. Calcd. For C25H22ClN5O3: C-63.09,
H-4.66, N-14.72; Found: C-63.14, H-4.73, N-14.65%.
2.5c N-(4-(2-chloroquinolin-3-yl)-6-(4-hydroxyphenyl)
pyrimidin-2-yl)-2-morpholinoacetamide (5c): Light
reddish brown crystal, yield: 51%; m.p.: 205–206◦C;
IR (KBr) νmax/cm−1: 3419 (OH), 3316, 3226 (NH),
3062 (C-H, aromatic), 2960, 2931, 2850 (C-H, CH2),
1690 (C=O), 1583 (C=N), 1579 (C=C), 1357 (C-N),
2.5 General procedure for the preparation of N-(4-
(2-chloroquinolin-3-yl)-6-(aryl)pyrimidin-2-yl)-2-
morpholinoacetamides (5a–l)
1
1222 (C-O), 731 (C-Cl); H NMR (300 MHz, DMSO-
A mixture of compounds (4a–l) (0.01 mol), anhy-
drous potassium carbonate (0.02 mol) and morpholine
(0.01 mol) in dry toluene was refluxed for about 8–
10 h. After completion of the reaction, potassium car-
bonate was removed by filtration and excess of sol-
vent was removed under reduced pressure. The obtained
residues were filtered, dried and crystallized from
ethanol (95%).
d6, δ, ppm): 2.68 (t, 4H, J = 4.4 Hz, N(CH2)2), 3.42 (t,
4H, J = 4.6 Hz, O(CH2)2), 3.90 (s, 2H, CH2), 6.71 (s,
1H, pyrimidine-H), 6.88–8.44 (m, 9H, Ar-H), 9.17 (s,
1H, OH, D2O exch.), 10.25 (s, 1H, NH, D2O exch.); 13C
NMR (100 MHz, DMSO-d6, δ, ppm): 45.7 (N(CH2)2),
63.5 (CH2), 67.7 (O(CH2)2), 101.5 (C-5), 115.7–156.8
(C-arom), 151.6 (C–Cl, quinoline), 163.2 (C-2), 164.4
(C-6), 165.3 (C-4), 173.8 (C=O); LCMS (m/z):
475 (M+); Anal. Calcd. For C25H22ClN5O3: C-63.09,
H-4.66, N-14.72; Found: C-63.17, H-4.60, N-14.74%.
2.5a N-(4-(2-chloroquinolin-3-yl)-6-phenylpyrimidin-
2-yl)-2-morpholinoacetamide (5a): Light brown crys-
tal, yield: 57%; m.p.: 204–206◦C; IR (KBr) νmax/cm−1:
3314, 3230 (NH), 3071 (C-H, aromatic), 2962, 2920,
2850 (C-H, CH2), 1686 (C=O), 1605 (C=N), 1570
(C=C), 1360 (C-N), 1236 (C-O), 720 (C-Cl); 1H NMR
(300 MHz, DMSO-d6, δ, ppm): 2.61 (t, 4H, J = 4.5 Hz,
N(CH2)2), 3.47 (t, 4H, J = 4.8 Hz, O(CH2)2), 3.91
(s, 2H, CH2), 6.73 (s, 1H, pyrimidine-H), 7.34–8.47
(m, 10H, Ar-H), 10.21 (s, 1H, NH, D2O exch.); 13C
2.5d N-(4-(2-chloroquinolin-3-yl)-6-(4-methoxyphenyl)
pyrimidin-2-yl)-2-morpholinoacetamide (5d): Light
pink crystal, yield: 55%; m.p.: 171–173◦C; IR (KBr)
νmax/cm−1: 3320, 3215 (NH), 3074 (C-H, aromatic),
2966, 2938, 2857 (C-H, CH2), 1688 (C=O), 1590
(C=N), 1574 (C=C), 1351 (C-N), 1231, 1134 (C-
1
O), 729 (C-Cl); H NMR (300 MHz, DMSO-d6, δ,
ppm): 2.63 (t, 4H, J = 4.7 Hz, N(CH2)2), 3.49 (t, 4H,

Synthesis and antimicrobial screening of quinoline analogues
327
J = 4.5 Hz, O(CH2)2), 3.64 (s, 3H, OCH3), 3.96 (s, 2958, 2920, 2854 (C-H, CH2), 1688 (C=O), 1588
2H, CH2), 6.82 (s, 1H, pyrimidine-H), 7.09–8.44 (m, (C=N), 1562 (C=C), 1355 (C-N), 1230 (C-O), 1117
1
9H, Ar-H), 10.10 (s, 1H, NH, D2O exch.); 13C NMR (C-F), 741 (C-Cl); H NMR (300 MHz, DMSO-d6,
(100 MHz, DMSO-d6, δ, ppm): 45.5 (N(CH2)2), 55.4 δ, ppm): 2.71 (t, 4H, J = 4.7 Hz, N(CH2)2), 3.52
(OCH3), 63.6 (CH2), 67.2 (O(CH2)2), 101.5 (C-5), (t, 4H, J = 4.1 Hz, O(CH2)2), 3.93 (s, 2H, CH2),
113.8–159.3 (C-arom), 152.3 (C-Cl, quinoline), 163.7 6.84 (s, 1H, pyrimidine-H), 7.17–8.58 (m, 9H, Ar-H),
(C-2), 164.4 (C-6), 165.7 (C-4), 173.4 (C=O); LCMS 10.27 (s, 1H, NH, D2O exch.); 13C NMR (100 MHz,
(m/z): 489 (M+); Anal. Calcd. For C26H24ClN5O3: DMSO-d6, δ, ppm): 45.5 (N(CH2)2), 63.7 (CH2), 67.2
C-63.74, H-4.94, N-14.29; Found: C-63.81, H-4.91, (O(CH2)2), 101.5 (C-5), 114.3–158.2 (C-arom), 153.1
N-22%.
(C-Cl, quinoline), 163.2 (C-2), 164.5 (C-6), 165.6
(C-4), 173.2 (C=O); LCMS (m/z): 477 (M+); Anal.
Calcd. For C25H21ClFN5O2: C-62.83, H-4.43, N-14.65;
Found: C-62.88, H-4.38, N-14.61%.
2.5e N-(4-(2-chlorophenyl)-6-(2-chloroquinolin-3-yl)
pyrimidin-2-yl)-2-morpholinoacetamide (5e): Light
yellow crystal, yield: 58%; m.p.: 182–184◦C; IR (KBr)
νmax/cm−1: 3320, 3214 (NH), 3062 (C-H, aromatic),
2968, 2933, 2858 (C-H, CH2), 1698 (C=O), 1601
(C=N), 1565 (C=C), 1352 (C-N), 1238 (C-O), 739
2.5h N-(4-(2-chloroquinolin-3-yl)-6-(3-fluorophenyl)
pyrimidin-2-yl)-2-morpholinoacetamide (5h): Light
pink crystal, yield: 54%; m.p.: 177–179◦C; IR (KBr)
νmax/cm−1: 3339, 3241 (NH), 3078 (C-H, aromatic),
2961, 2914, 2844 (C-H, CH2), 1687 (C=O), 1580
(C=N), 1559 (C=C), 1348 (C-N), 1239 (C-O), 1120
1
(C-Cl); H NMR (300 MHz, DMSO-d6, δ, ppm): 2.69
(t, 4H, J = 4.3 Hz, N(CH2)2), 3.49 (t, 4H, J = 4.9 Hz,
O(CH2)2), 3.92 (s, 2H, CH2), 6.79 (s, 1H, pyrimidine-
H), 7.33–8.49 (m, 9H, Ar-H), 10.27 (s, 1H, NH, D2O
exch.); 13C NMR (100 MHz, DMSO-d6, δ, ppm): 45.1
(N(CH2)2), 63.3 (CH2), 67.7 (O(CH2)2), 101.3 (C-5),
126.2–146.4 (C-arom), 152.5 (C-Cl, quinoline), 163.4
(C-2), 164.8 (C-6), 165.1 (C-4), 173.5 (C=O); LCMS
(m/z): 493 (M+); Anal. Calcd. For C25H21Cl2N5O2:
C-60.74, H-4.28, N-14.17; Found: C-60.69, H-4.32,
N-14.10%.
1
(C-F), 749 (C-Cl); H NMR (300 MHz, DMSO-d6,
δ, ppm): 2.75 (t, 4H, J = 4.8 Hz, N(CH2)2), 3.58
(t, 4H, J = 4.6 Hz, O(CH2)2), 3.96 (s, 2H, CH2),
6.80 (s, 1H, pyrimidine-H), 7.25–8.55 (m, 9H, Ar-H),
10.31 (s, 1H, NH, D2O exch.); 13C NMR (100 MHz,
DMSO-d6, δ, ppm): 45.7 (N(CH2)2), 63.8 (CH2), 67.1
(O(CH2)2), 101.0 (C-5), 115.1–161.7 (C-arom), 153.3
(C-Cl, quinoline), 163.1 (C-2), 164.4 (C-6), 165.3
(C-4), 173.0 (C=O); LCMS (m/z): 477 (M+); Anal.
Calcd. For C25H21ClFN5O2: C-62.83, H-4.43, N-14.65;
Found: C-62.77, H-4.47, N-14.72%.
2.5f N-(4-(4-chlorophenyl)-6-(2-chloroquinolin-3-yl)
pyrimidin-2-yl)-2-morpholinoacetamide (5f): Light
reddish brown crystal, yield: 50%; m.p.: 167–169◦C;
IR (KBr) νmax/cm−1: 3332, 3219 (NH), 3067 (C-H,
aromatic), 2961, 2928, 2858 (C-H, CH2), 1690 (C=O),
1594 (C=N), 1560 (C=C), 1361 (C-N), 1238 (C-O),
1
2.5i N-(4-(2-chloroquinolin-3-yl)-6-(4-fluorophenyl)
pyrimidin-2-yl)-2-morpholinoacetamide (5i): Light
brown crystal, yield: 59%; m.p.: 211–213◦C; IR (KBr)
νmax/cm−1: 3359, 3240 (NH), 3064 (C-H, aromatic),
2973, 2951, 2840 (C-H, CH2), 1691 (C=O), 1576
(C=N), 1532 (C=C), 1359 (C-N), 1231 (C-O), 1138
732 (C-Cl); H NMR (300 MHz, DMSO-d6, δ, ppm):
2.66 (t, 4H, J = 4.5 Hz, N(CH2)2), 3.44 (t, 4H, J =
4.3 Hz, O(CH2)2), 3.94 (s, 2H, CH2), 6.74 (s, 1H,
pyrimidine-H), 7.50–8.54 (m, 9H, Ar-H), 10.24 (s, 1H,
NH, D2O exch.); 13C NMR (100 MHz, DMSO-d6, δ,
ppm): 45.3 (N(CH2)2), 63.1 (CH2), 67.5 (O(CH2)2),
101.6 (C-5), 127.5–145.3 (C-arom), 152.2 (C-Cl,
quinoline), 163.1 (C-2), 164.4 (C-6), 165.2 (C-4),
173.4 (C=O); LCMS (m/z): 493 (M+); Anal. Calcd.
For C25H21Cl2N5O2: C-60.74, H-4.28, N-14.17; Found:
C-60.82, H-4.35, N-14.26%.
1
(C-F), 737 (C-Cl); H NMR (300 MHz, DMSO-d6,
δ, ppm): 2.73 (t, 4H, J = 4.7 Hz, N(CH2)2), 3.55
(t, 4H, J = 4.4 Hz, O(CH2)2), 3.91 (s, 2H, CH2),
6.77 (s, 1H, pyrimidine-H), 7.30–8.52 (m, 9H, Ar-H),
10.29 (s, 1H, NH, D2O exch.); 13C NMR (100 MHz,
DMSO-d6, δ, ppm): 45.2 (N(CH2)2), 63.6 (CH2), 67.7
(O(CH2)2), 101.3 (C-5), 115.7–162.3 (C-arom), 152.8
(C-Cl, quinoline), 163.5 (C-2), 164.2 (C-6), 165.7
(C-4), 173.3 (C=O); LCMS (m/z): 477 (M+); Anal.
Calcd. For C25H21ClFN5O2: C-62.83, H-4.43, N-14.65;
Found: C-62.87, H-4.38, N-14.70%.
2.5g N-(4-(2-chloroquinolin-3-yl)-6-(2-fluorophenyl)
pyrimidin-2-yl)-2-morpholinoacetamide (5g): Light
yellow crystal, yield: 56%; m.p.: 188–190◦C; IR (KBr)
νmax/cm−1: 3326, 3228 (NH), 3071 (C-H, aromatic),

328
N C Desai et al.
2.5j N-(4-(2-chloroquinolin-3-yl)-6-(2-nitrophenyl) 504 (M+); Anal. Calcd. For C25H21ClN6O4: C-59.47,
pyrimidin-2-yl)-2-morpholinoacetamide (5j): Yellow H-4.19, N-16.64; Found: C-59.55, H-4.25, N-16.72%.
orange crystal, yield: 73%; m.p.: 224–226◦C; IR (KBr)
νmax/cm−1: 3350, 3234 (NH), 3071 (C-H, aromatic),
3. Materials and methods
2983, 2956, 2831 (C-H, CH2), 1697 (C=O), 1593
(C=N), 1538 (C=C), 1485, 1347 (NO2 group), 1363
3.1 General
1
(C-N), 1233 (C-O), 730 (C-Cl); H NMR (300 MHz,
DMSO-d6, δ, ppm): 2.76 (t, 4H, J = 4.9 Hz, N(CH2)2),
All reactions except those in aqueous media were car-
3.51 (t, 4H, J = 4.7 Hz, O(CH2)2), 3.95 (s, 2H, CH2),
ried out by standard techniques for the exclusion of
6.82 (s, 1H, pyrimidine-H), 7.62–8.56 (m, 9H, Ar-H),
moisture. Melting points were determined on an elec-
10.34 (s, 1H, NH, D2O exch.); 13C NMR (100 MHz,
tro thermal melting point apparatus and were reported
DMSO-d6, δ, ppm): 45.4 (N(CH2)2), 63.7 (CH2), 67.9
uncorrected. TLC on silica gel plates (Merck, 60, F254
)
(O(CH2)2), 101.3 (C-5), 124.2–148.4 (C-arom), 152.6
(C-Cl, quinoline), 163.7 (C-2), 164.2 (C-6), 165.3
(C-4), 173.7 (C=O); LCMS (m/z): 504 (M+); Anal.
Calcd. For C25H21ClN6O4: C-59.47, H-4.19, N-16.64;
Found: C-59.41, H-4.14, N-16.70%.
was used for purity check and reaction monitoring.
Column chromatography on silica gel (Merck, 70–230
mesh and 230–400 mesh ASTH for flash chromatogra-
phy) was applied when necessary to isolate and purify
the reactions products. Elemental analysis (% C, H, N)
was carried out by a Perkin-Elmer 2400 CHN anal-
yser. IR spectra of all compounds have been recorded
on a Perkin-Elmer FT-IR spectrometer in KBr. 1H NMR
spectra were recorded on Varian Gemini 300 MHz and
13C NMR spectra on Varian Mercury-400, 100 MHz
in DMSO-d6 as a solvent and tetramethylsilane (TMS)
as an internal standard. Chemical shifts were reported
in ppm units with use of δ scale. Mass spectra were
scanned on a Shimadzu LCMS 2010 spectrometer.
Anhydrous reactions were carried out in oven-dried
glassware in nitrogen atmosphere.
2.5k N-(4-(2-chloroquinolin-3-yl)-6-(3-nitrophenyl)
pyrimidin-2-yl)-2-morpholinoacetamide (5k): Dark
yellow crystal, yield: 52%; m.p.: 155–157◦C; IR (KBr)
νmax/cm−1: 3369, 3258 (NH), 3065 (C-H, aromatic),
2980, 2947, 2835 (C-H, CH2), 1690 (C=O), 1584
(C=N), 1522 (C=C), 1482, 1348 (NO2 group), 1360
1
(C-N), 1235 (C-O), 725 (C-Cl); H NMR (300 MHz,
DMSO-d6, δ, ppm): 2.74 (t, 4H, J = 4.6 Hz, N(CH2)2),
3.56 (t, 4H, J = 4.3 Hz, O(CH2)2), 3.92 (s, 2H, CH2),
6.80 (s, 1H, pyrimidine-H), 7.70–8.67 (m, 9H, Ar-H),
10.30 (s, 1H, NH, D2O exch.); 13C NMR (100 MHz,
DMSO-d6, δ, ppm): 45.1 (N(CH2)2), 63.4 (CH2), 67.7
(O(CH2)2), 101.5 (C-5), 122.7–147.8 (C-arom), 152.7
(C-Cl, quinoline), 163.2 (C-2), 164.6 (C-6), 165.8
(C-4), 173.6 (C=O); LCMS (m/z): 504 (M+); Anal.
Calcd. For C25H21ClN6O4: C-59.47, H-4.19, N-16.64;
Found: C-59.52, H-4.25, N-16.59%.
3.2 Antibacterial assay
The newly synthesized compounds (5a–l) were
screened for their antibacterial activity against Gram-
positive bacteria (Staphylococcus aureus (MTCC-96),
Streptococcus pyogenes (MTCC-442)) and Gram-
negative bacteria (Escherichia coli (MTCC-443),
Pseudomonas aeruginosa (MTCC-1688). All MTCC
cultures were collected from Institute of Microbial
Technology, Chandigarh. The activity of compounds
was determined as per National Committee for Clini-
cal Laboratory Standards (NCCLS) protocol using
2.5l N-(4-(2-chloroquinolin-3-yl)-6-(4-nitrophenyl)
pyrimidin-2-yl)-2-morpholinoacetamide (5l): Dark
orange yellow crystal, yield: 55%; m.p.: 188–190◦C;
IR (KBr) νmax/cm−1: 3353, 3244 (NH), 3079 (C-H,
aromatic), 2973, 2940, 2828 (C-H, CH2), 1698 (C=O), Mueller Hinton Broth (Becton Dickinson, USA).25–28
Compounds were screened for their antibacterial acti-
1594 (C=N), 1515 (C=C), 1475, 1355 (NO2 group),
1363 (C–N), 1241 (C-O), 732 (C–Cl); 1H NMR
(300 MHz, DMSO-d6, δ, ppm): 2.70 (t, 4H, J = 4.5 Hz,
N(CH2)2), 3.54 (t, 4H, J = 4.8 Hz, O(CH2)2), 3.95
(s, 2H, CH2), 6.75 (s, 1H, pyrimidine-H), 7.63–8.58
(m, 9H, Ar-H), 10.36 (s, 1H, NH, D2O exch.); 13C
NMR (100 MHz, DMSO-d6, δ, ppm): 45.5 (N(CH2)2),
63.2 (CH2), 67.5 (O(CH2)2), 101.2 (C-5), 124.3–146.8
(C-arom), 151.8 (C-Cl, quinoline), 163.8 (C-2), 164.5
(C-6), 165.2 (C-4), 173.7 (C=O); LCMS (m/z):
vity as primary screening in six sets against Escherichia
coli, Staphylococcus aureus, Pseudomonas aeruginosa
and Streptococcus pyogenes at different concentrations
of 1000, 500, 250 μg/mL. The compounds found to be
active in primary screening were similarly diluted to
obtain 200, 125, 100, 62.5, 50, 25 and 12.5 μg/mL con-
centrations for secondary screening to test in a sec-
ond set of dilution against all microorganisms. Inocu-
lum size for test strain was adjusted to 106 CFU/mL

Synthesis and antimicrobial screening of quinoline analogues
329
(Colony Forming Unit per milliliter) by comparing the ANOVA method followed by independent two sample t
turbidity (turbidimetric method). Mueller Hinton Broth test, it was observed that differences below 0.001 level
was used as nutrient medium to grow and dilute the were considered as statistically significant. Compounds
compound suspension for test bacteria. 2% DMSO was 5a–l were screened for their antibacterial and antifungal
used as a diluent/vehicle to obtain the desired concen- activities in six sets (n) against bacteria and fungi used
tration of synthesized compounds and standard drugs to in the present protocol.
test upon standard microbial strains. Synthesized com-
pounds were diluted to 1000 μg/mL concentration, as a
stock solution. The control tube containing no antibio-
tic was immediately subcultured [before inoculation]
4. Results and discussion
by spreading a loopful evenly over a quarter of plate
4.1 Chemistry
of medium suitable for the growth of test organisms.
The tubes were then put for incubation at 37◦C for 24 h
The Vilsmeier–Haack reaction on acetanilide pro-
for bacteria. 10 μg/mL suspensions were further inocu-
lated on an appropriate media and growth was noted
after 24 h and 48 h. The highest dilution (lowest con-
centration) preventing appearance of turbidity was con-
sidered as minimum inhibitory concentration (MIC,
μg/mL) i.e., the amount of growth from the control
tube before incubation (which represents the original
inoculum) was compared. A set of tubes containing
only seeded broth and solvent controls were maintained
under identical conditions so as to make sure that the
solvent had no influence on strain growth. The result
of this is greatly affected by the size of inoculum.
The test mixture should contain 106 CFU/mL orga-
nisms. Standard drug used in the present study was ampi-
cillin for evaluating antibacterial activity which showed
100, 100, 250 and 100 μg/mL MIC against E. coli,
P. aeruginosa, S. aureus and S. pyogenes, respectively.
vided a vital and efficient intermediate for the syn-
thesis of several newer substituted heterocyclic com-
pounds. The reaction was performed at 100◦C for
4–16 h, using the typical Vilsmeiere–Haack reagent
derived from phosphorus oxychloride and dimethylfor-
mamide.23 Although, the reaction proceeded unevent-
fully, the products formed were isolated using silica
gel column chromatography. The reaction sequences
employed for synthesis of the target compounds (5a–
l) are illustrated in scheme 1. The key chalcone inter-
mediates (2a–l) were synthesized through the Claisen–
Schmidt condensation of equimolar amounts of ace-
tophenone derivatives and chloroquinoline aldehyde (1)
through stirring the reactants in aqueous ethanolic solu-
tion containing 20% sodium hydroxide at room temper-
ature for 24 h in accordance with the method described
in the literature.24
When 3-(2-chloroquinolin-3-yl)-1-(aryl)prop-2-en-
1-ones (2a–l) were refluxed with guanidine nitrate
in the presence of sodium hydroxide, 4-(aryl)-6-(2-
chloroquinolin-3-yl)pyrimidin-2-amines (3a–l) were
formed. 1H NMR spectrum of compound (3a) revealed
a singlet characteristic peak for primary amine protons
at δ = 5.65 ppm which was confirmed by disappearence
of peak when exchange with D2O. The IR spectra for
(3a) showed the specific band for the primary amine
at 3344 and 3450 cm−1. The 13C NMR spectrum of
the same compound revealed seventeen unequivalent
carbons. Pyrimidine carbons displayed characteristic
peaks at δ = 103.5 (C-5), 163.1 (C-2), 164.8 (C-6),
165.2 (C-4) ppm. Moreover, the mass spectrum of
(5a) showed a molecular ion peak at m/z = 332 (M+)
corresponding to a molecular formula C19H13ClN4.
Various substituted 2-chloro-N-(4-(2-chloroquinolin-
3-yl)-6-(aryl)pyrimidin-2-yl)acetamides (4a–l) were
synthesized by electrophilic substitution reaction of
chloroacetyl chloride with the corresponding parent
4-(aryl)-6-(2-chloroquinolin-3-yl)pyrimidin-2-amines
(3a–l) in the presence of triethylamine as base and
3.3 Antifungal assay
The same compounds (5a–l) were tested for antifungal
activity as primary screening in six sets against Can-
dida albicans, Aspergillus niger and Aspergillus clava-
tus at various concentrations of 1000, 500, 250 μg/mL.
The compounds found to be active in primary screening
were similarly diluted to obtain 200, 125, 100, 62.5, 50
and 25 μg/mL concentrations for secondary screening
to test in a second set of dilution against all microorga-
nisms. Griseofulvin was used as a standard drug for anti-
fungal activity, which showed 500, 100 and 100 μg/mL
MIC against C. albicans, A. niger and A. clavatus. For
fungal growth, in the present protocol, we have used
Sabourauds dextrose broth at 28◦C in aerobic condition
for 48 h.
3.4 Statistical analysis
Standard deviation value was expressed in terms of
SD. On the basis of calculated value by using one-way toluene as solvent. The structures of compounds

330
N C Desai et al.
Scheme 1. Synthetic route for the preparation of title compounds (5a–l).
(4a–l) were determined by spectral data and ele- of secondary amine in amide linkage showed as a
mental analysis, which gave the molecular formula singlet at δ = 10.21 ppm. Aromatic protons showed
(see Experimental). Then, condensation of 2- a multiplet centred on δ = 7.34–8.47 ppm. The 13C
chloro-N-(4-(2-chloroquinolin-3-yl)-6-(aryl)pyrimidin- NMR spectrum of compound (5a) revealed twenty one
2-yl)acetamides (4a–l) with morpholine in the pres- unequivalent carbons. The carbonyl carbon was dis-
ence of anhydrous potassium carbonate furnished played at δ = 173.1 ppm. Other important signals were
N-(4-(2-chloroquinolin-3-yl)-6-(aryl)pyrimidin-2-yl)-
displayed at δ = 45.3 and 67.3 ppm for N(CH2)2 and
2-morpholinoacetamides (5a–l). Structures of the O(CH2)2, respectively, while methylene carbon was
isolated products (5a–l) were confirmed on the basis appeared downfield at δ = 63.2 ppm. Moreover, the
of their spectral data. For example, the IR spectrum of mass spectrum of (5a) showed a molecular ion peak at
compound (5a) revealed an absorption bands at 3314, m/z = 459 (M+) corresponding to a molecular formula
3230 and 1686 cm−1 characteristic to secondary amine C25H22ClN5O2.
and carbonyl groups, respectively. Absorption bands
at 2962, 2920 and 2850 cm−1 were due to stretching
1
vibration corresponding to methylene group. Its H
NMR spectrum revealed two triplet signals at δ =
2.61 and 3.47 ppm with coupling constants of nearly
4.5 and 4.8 Hz assignable to N(CH2)2 and O(CH2)2 of
morpholine ring, respectively. Protons of methylene
group dispalyed as a singlet at δ = 3.91 ppm. Proton
4.2 Biology
4.2a Antimicrobial activity: Compounds (5a–l)
were evaluated against Gram-positive, Gram-negative
bacteria and fungi strains. The individual minimum
inhibitory concentration (MIC, μg/mL) obtained for

Synthesis and antimicrobial screening of quinoline analogues
331

332
N C Desai et al.
compounds (5a–l) are presented in table 1. It was ampicillin and griseofulvin. Antimicrobial activity of
observed that compounds 5e (2-Cl), 5f (4-Cl), 5g (2-F), compounds 5e, 5f, 5g, 5h, 5i, 5j, 5k and 5l tested against
5i (4-F) and 5l (4-NO2) were most active compounds. microbial strains by micro broth dilution assay is shown
From antibacterial screening results, it was observed in figure 2.
that compounds 5f (4-Cl) and 5i (4-F) possessed good
activity, whereas compounds 5g (2-F) and 5l (4-NO2)
possessed excellent activity against E. coli. Compounds
5e (2-Cl) and 5l (4-NO2) possessed very good activity
against P. aeruginosa. When we replaced hydrogen
in 5a by nitro and chloro group at fourth position
of benzene ring, we got compound 5f which under-
went enhancement in activity and possessed excellent
activity against P. aeruginosa. Compound 5k (3-NO2)
shown good activity, while compounds 5i (4-F) and 5l
(4-NO2) exhibited excellent activity against S. aureus.
It was our observation that when we replaced hydrogen
in 5a by 4-NO2 led to compound 5l and they displayed
excellent activity against S. pyogenes.
Antifungal activity showed that, compounds 5f (4-
Cl) and 5l (4-NO2) possessed excellent activity against
C. albicans. Compounds 5f (4-Cl), 5j (2-NO2) and
5l (4-NO2) possessed very good activity against A.
niger. Compound 5g (2-F) possessed very good activity
against A. clavatus. When nitro group was introduced
at fourth position of benzene ring in 5a activity was
enhanced and displayed excellent activity, while intro-
duction of chloro group at second position of benzene
ring in 5a displayed excellent activity against A. clava-
tus. Thus, we have discussed and compared antibacte-
rial and antifungal activities based on standard drugs
4.2b Structure–activity relationship: The results
revealed that the activity was considerably affected by
various substituents on the aromatic ring of pyrimidine
nucleus. For antibacterial activity, it was observed
that introduction of electron withdrawing group on
benzene ring of pyrimidine nucleus showed consider-
able increase in antibacterial potency of compounds.
It was observed from a result that compounds 5g and
5l containing fluoro and nitro substituents showed
significant potency against Gram-negative bacteria
E. coli. Amongst them, compound containing nitro
group at fourth position on substituted benzene ring
showed maximum inhibition against E. coli at MIC
12.5 μg/mL. Compounds 5i and 5l containing flouro
and nitro group showed good potency against S.
aureus. Again compounds 5l containing nitro group
at fourth position of benzene ring showed maximum
inhibition against Gram-positive bacteria S. pyogenes.
From the above results it was clear to note that elec-
tron withdrawing groups at fourth position of benzene
ring showed maximum potency than electron releasing
groups. All other compounds showed good to moderate
potency. For antifungal activity, it has been observed
that compounds containing chloro and nitro 5f and 5l
Figure 2. Antimicrobial activity of compounds 5e, 5f, 5g, 5h, 5i, 5j, 5k and 5l tested
against microbial strains by micro broth dilution assay.

Synthesis and antimicrobial screening of quinoline analogues
333
showed excellent activity against C. albicans. Com-
pounds 5e and 5l containing chloro and nitro group
exhibited maximum potency against A. clavatus. It
has been observed very strong correlation between
antibacterial and antifungal activities.
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5. Conclusion
The new compounds (5a–l) presented here clearly differ
in their corresponding antimicrobial activity depending
on the type of substituent in hybrid molecules. In the
course of this study, particularly derivatives possessing
electron withdrawing groups such as nitro and halo-
gen are identified as exhibiting potential antibacterial
activity against bacterial strains and antifungal acti-
vity against fungal strains. These results, combined with
potential benefits or at least differences in pharmacoki-
netics make the titled quinoline, pyrimidine and mor-
pholine congeners not only interesting simplified leads
for the further chemical optimization of this class, but
also potentially interesting for future scope to study
their mechanism of action and would be worthy of
additional structure–activity relationship investigation.
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The electronic supporting information can be seen in
www.ias.ac.in/chemsci.
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Acknowledgement
We thank the Department of Chemistry, Mahatma Gandhi
Campus, Maharaja Krishnakumarsinhji Bhavnagar Uni-
versity, Bhavnagar for providing research and library
facilities.
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