Synthesis, in-vitroreverse transcriptase inhibitory activity and docking study of some new imidazol-5-one analogs

Article abstract of DOI:10.1007/s00044-014-0954-8

Non-nucleoside reverse transcriptase inhibitors have a definitive role and most commonly used in treatment of HIV-1 infection. A new series of 4-ethylidene/substituted-benzylidene-1-(4-hydroxy/chloro-6-methylpyrimidin-2-yl) -2-ethyl/phenyl-1H-imidazol-5(4H)-one were designed, synthesized, and evaluated for HIV-1 reverse transcriptase (RT) inhibitory activity. The results of in-vitro HIV-1 RT assay showed that some of the new compounds, such as 4c, 4d, 4e, 5a, and 5e effectively inhibit HIV-1 RT activity. 1-(4-Chloro-6- methylpyrimidin-2-yl)-4-(furan-2-ylmethylene)-2-methyl-1H-imidazol-5(4H)-one (5e) exerted most potent in-vitro HIV-1 RT inhibitory activity, among the group of compounds. Molecular docking studies were carried out to explore the binding affinity of imidazole-5-one analogs in active site of HIV-1 RT enzyme. Springer Science+Business Media 2014.

Full text of DOI:10.1007/s00044-014-0954-8

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res
DOI 10.1007/s00044-014-0954-8
ORIGINAL RESEARCH
Synthesis, in-vitro reverse transcriptase inhibitory activity
and docking study of some new imidazol-5-one analogs
•
Santosh N. Mokale Deepak K. Lokwani
•
Devanand B. Shinde
Received: 30 September 2013 / Accepted: 11 February 2014
Ó Springer Science+Business Media New York 2014
Abstract Non-nucleoside reverse transcriptase inhibitors
have a definitive role and most commonly used in treatment
of HIV-1 infection. A new series of 4-ethylidene/substituted-
benzylidene-1-(4-hydroxy/chloro-6-methylpyrimidin-2-yl)-
2-ethyl/phenyl-1H-imidazol-5(4H)-one were designed, syn-
thesized, and evaluated for HIV-1 reverse transcriptase (RT)
inhibitory activity. The results of in-vitro HIV-1 RT assay
showed that some of the new compounds, such as 4c, 4d, 4e,
5a, and 5e effectively inhibit HIV-1 RT activity. 1-(4-
Chloro-6-methylpyrimidin-2-yl)-4-(furan-2-ylmethylene)-2-
methyl-1H-imidazol-5(4H)-one (5e) exerted most potent in-
vitro HIV-1 RT inhibitory activity, among the group of
compounds. Molecular docking studies were carried out to
explore the binding affinity of imidazole-5-one analogs in
active site of HIV-1 RT enzyme.
one of the most urgent world health threats. The successful
replication of HIV-1 requires viral genome reverse tran-
scription to generate proviral DNA which then subsequently
integrated into the human genome as a provirus. Two types of
drugs that inhibit HIV-1 reverse transcriptase (RT) activity are
nucleoside and non-nucleoside inhibitors. The non-nucleo-
side reverse transcriptase inhibitors (NNRTIs) are allosteric
inhibitors which bind to the viral enzyme RT by interacting
with specific allosteric non-substrate binding pocketsite (non-
nucleoside binding pocket-NNBP), blocking its mechanism,
and making it unable to produce viral DNA (Balzarini, 2004).
NNRTIs are highly specific inhibitors of HIV-1, they are not
active against other retroviruses (Balzarini and De Clercq,
1998). This specificity results in highselectivity indexes (ratio
of in-vitro cytotoxicity over antiviral activity) for this class of
compounds.
Keywords Imidazol-5-one ꢀ HIV-1 RT ꢀ Docking ꢀ
NNRTI ꢀ Glide
Several NNRTIs have been approved for clinical use bythe
Food and Drug Administration as anti-AIDS drugs, which
include nevirapine, delavirdine, efavirenz, and etravirine
(Pauwels, 2004). However, in view of the increasing inci-
denceofresistancetothecurrentdrugregimensandfrequency
of adverse events, there is the need of development of new,
selective, and potent NNRTIs. This makes HIV-1 RT as a
good target to test the drug lead exploration strategies.
The NNRTIs appear very diverse in structure and they
have some common features, such as a central heterocyclic
moiety (body) surrounded by two bulky hydrophobic
groups (wings). The overall structure may be seen as a
butterfly with hydrophilic center and two hydrophobic
outskirts. It was suggested from literature that a heteroaryl
system would be preferred as one of the wings for better
HIV-1 RT inhibitory activity (Rao et al., 2004a, b; Rawal
et al., 2007). By considering above idea, we reported in our
previous study, the new RT inhibitors having imidazole
ring as central moiety with methylpyridine and substituted
Introduction
Human immunodeficiency virus type-1 (HIV-1) is responsi-
ble for human acquired immunodeficiency syndrome (AIDS),
S. N. Mokale
Y.B. Chavan College of Pharmacy, Dr. Rafiq Zakaria Campus,
Aurangabad, Maharashtra, India
e-mail: santoshmokale@rediffmail.com
D. K. Lokwani ꢀ D. B. Shinde (&)
Department of Chemical Technology, Dr. Babasaheb Ambedkar
Marathwada University, Aurangabad, Maharashtra, India
e-mail: dbsdeepak10@rediffmail.com
D. K. Lokwani
e-mail: dklokwani@gmail.com
123

Med Chem Res
O
Fig. 1 Chemical structure of
compounds
H
N
N
H
3C
H
3C
HN
O
N
O
O
N
O
F
H
3C
N
N
H
C
3
N
l
O
C
N
H
3C
N
N
H
C
3
O
N
F
N
O
O
H
3C
F
Cl
OH
Efavirenz
5e
4e
Nevirapine
ethylidene/benzylidene as two hydrophobic groups (Mok-
ale et al., 2012). In present work, we designed and syn-
thesized new compounds by replacing methylpyridine ring
with 4-substituted-6-methylpyrimidine as one of new
hydrophobic wings for NNRTI (Fig. 1). The most effective
HIV-1 RT inhibitors were further subjected to docking
studies to investigate their possible binding interactions
with HIV-1 RT enzyme.
became acidic. The crystalline precipitate of benzoyl gly-
cine was filtered and washed with carbon tetrachloride and
cold water. The solid product was collected, dried and re-
crystallized from boiling water.
Yield: 94.51 %; M.P: 86 °C.
General procedure for synthesis of 4-(substituted
ethylidene/benzylidene)-2-methyloxazol-5-ones
(3a–j) from acetyl glycine
Experimental
A mixture of aldehyde (1 mol), acetyl glycine (1, 1 mol),
acetic anhydride (3 mol) and anhydrous potassium acetate
(1 mol) was placed in a 500 ml RBF. The mixture was
heated on an electric hot plate with constant shaking till the
mixture liquefied. Then the content of RBF was further
heated on water bath for 2 h. To this, 100 ml of ethanol
was added slowly and mixture was allowed to stand
overnight. The residue was separated by filtration, and then
it was washed with 25 ml of ice-cold alcohol and 25 ml of
boiling water. The crude product was collected, dried and
recrystallized using suitable solvent.
All reactions were carried out with dry, freshly distilled
solvents under anhydrous conditions, unless otherwise
noted. Melting points were determined on SRS OPTI-
MELT and uncorrected. H NMR and 13C NMR spectra
1
were recorded on a BRUKER AVANCE III 400 spec-
trometer (400 MHz) with TMS as internal standard and
DMSO as a solvent. Mass spectra were recorded on Time
of flight mass spectrometer. FT-IR spectra were recorded
on JASCO FT-IR 4000 using KBr powder.
Synthesis of acetyl glycine (1) from glycine
General procedure for synthesis of 4-(substituted
ethylidene/benzylidene)-2-phenyloxazole-5-ones
(3k–t) from benzoyl glycine
Glycine (0.5 mol) and water (150 ml) were taken in
500 ml conical flask. The mixture was stirred vigorously
until solid dissolved completely. To this solution, acetic
anhydride (1 mol) was added in one portion and again
stirred vigorously for 15–20 min. The resultant mixture
was cooled in a refrigerator overnight. The precipitate was
collected by filtration, washed with ice-cold water and dry
at 100 °C. The crude product was recrystallized from
40 ml of boiling water.
A mixture of aldehyde (1 mol), benzoyl glycine (2, 1 mol),
acetic anhydride (3 mol), and anhydrous potassium acetate
(1 mol) was placed in a 500 ml RBF. The mixture was
heated on an electric hot plate with constant shaking till it
liquefied. Then the content of RBF was further heated on
water bath for 2 h. To this 100 ml of ethanol was added
slowly and the mixture was allowed to stand overnight. The
crystalline product was separated by filtration, washed with
25 ml of ice-cold alcohol, then with 25 ml of boiling water
and recrystallized using suitable solvent.
Yield: 65.21 %; M.P: 206 °C.
Synthesis of benzoyl glycine (2) from glycine
Glycine (1 mol) was taken in a conical flask and it was
dissolved in 750 ml of 10 % sodium hydroxide solution.
To this solution, benzoyl chloride (1.15 mol) was added in
five portions with stirring until benzoyl chloride reacted
completely. The solution was transferred to beaker con-
taining crushed ice and conical flask was rinsed with little
water. The concentrated hydrochloric acid was added to
above mixture slowly with stirring until the mixture
General procedure for synthesis of 4-ethylidene/
substituted benzylidene-2-methyl/phenyl-1-(4-chloro-
6-methylpyrimidin-2-yl)-1H-imidazol-5-one (4a–5t)
A mixture of 4-substituted ethylidene/benzylidene-2-methyl/
phenyl-1,3-oxazol-5-one (1 mol), 2-amino-6-methylpyr-
imidin-4-ol or 4-chloro-6-methylpyrimidin-2-amine (1 mol),
25 ml glacial acetic acid or 25 ml pyridine, and potassium
123

Med Chem Res
4-(Furan-2-ylmethylene)-1-(4-hydroxy-6-
methylpyrimidin-2-yl)-2-methyl-1H-imidazol-5(4H)-
one (4d)
acetate (1 mol) was placed in a 250 ml RBF equipped with a
reflux condenser and it was heated on heating mantel. The
completion of reaction was monitor on TLC plate. After the
completion of reaction, the reaction mixture was poured into
ice. The precipitate was collected and recrystallized from
suitable solvent.
% Yield: 49; MW: 284.27; MF: C14H12N4O3; MP:
170–172; IR (KBr): 3487, 3057, 2877, 1730, 1638, 1575,
1
1454, 878 cm-1; H NMR (DMSO, 400 MHz): d 11.2 (s,
The spectral characterizations of synthesized derivatives
are given below.
1H, OH), 8.4–7.6 (m, 4H, Ar–OH), 6.8 (s, 1H, –C=CH–),
2.6–2.3 (m, 6H, CH3); 13C NMR (DMSO, 400 MHz):
d = 168.9 (C, C=O), 161.3 (C, CN3), 160.5 (C, CN2),
157.2 (C, C–OH), 155.3 (C, C-5), 150.1 (C, C-10), 142.3
(CH, C-20), 131.1 (C, CN), 116.2 (CH, C-8), 113.2 (CH,
C-30), 109.2 (CH, C-40), 103.4 (CH, C-4), 24.6 (CH3), 23.8
(CH3); MS: m/z 285 (M?1).
4-(4-Chlorobenzylidene)-1-(4-hydroxy-6-
methylpyrimidin-2-yl)-2-methyl-1H-imidazol-5(4H)-
one (4a)
% Yield: 67; MW: 328.75; MF: C16H13ClN4O2; MP: 180;
IR (KBr): 3389, 3056, 2878, 1730, 1638, 1575, 1454, 876,
1
658 cm-1; H NMR (DMSO, 400 MHz): d 10.9 (s, 1H,
1-(4-Hydroxy-6-methylpyrimidin-2-yl)-2-methyl-4-
(3,4,5-trimethoxybenzylidene)-1H-imidazol-5(4H)-one
(4e)
OH), 8.2–7.3 (m, 5H, Ar–H), 5.8 (s, 1H, –C=CH–), 2.5–2.2
(m, 6H, CH3); 13C NMR (DMSO, 400 MHz): d = 173.1
(C, C=O), 164.2 (C, CN3), 161.2 (C, CN2), 160.5 (C, C–
OH), 159.3 (C, C-5), 133.1 (C, C–Cl), 132.5 (C, C-10)
130.3 (C, CN), 129.3 (CH, C-20, C-60), 128.1 (CH, C-30,
C-50), 116.2 (CH, C-8), 103.5 (CH, C-4), 24.2 (CH3), 23.5
(CH3); MS: m/z 329 (M?1).
% Yield: 65; MW: 384.38; MF: C19H20N4O5; MP:
290–292; IR (KBr): 3390, 3050, 2959, 1744, 1658, 1612,
1
1447, 1386, 875 cm-1; H NMR (DMSO, 400 MHz): d
11.1 (s, 1H, OH), 8.1–7.4 (m, 3H, Ar–H), 6.4 (s, 1H,
–C=CH–), 3.8 (s, 9H, OCH3), 2.3–2.1 (m, 6H, CH3); 13C
NMR (DMSO, 400 MHz): d = 172.2 (C, C=O), 163.3 (C,
CN3), 160.1 (C, CN2), 156.8 (C, C–OH), 155.8 (C, C-5),
154.1 (C, C-30, C-50), 140.1 (C, C-40), 132.1 (C, CN), 130.4
(C, C-10), 120.2 (CH, C-20, C-60), 117.0 (CH, C-8), 103.5
(CH, C-4), 60.3 (OCH3), 56.2 (OCH3), 24.5 (CH3), 23.3
(CH3); MS: m/z 385 (M?1).
4-Benzylidene-1-(4-hydroxy-6-methylpyrimidin-2-yl)-
2-methyl-1H-imidazol-5(4H)-one (4b)
% Yield: 45; MW: 294.30; MF: C16H14N4O2; MP:
210–212; IR (KBr): 3401, 3057, 2877, 1730, 1638, 1575,
1
1454, 878 cm-1; H NMR (DMSO, 400 MHz): d 11.1 (s,
1H, OH), 8.0–7.1 (m, 6H, Ar–H), 5.7 (s, 1H, –C=CH–),
2.5–2.2 (m, 6H, CH3); 13C NMR (DMSO, 400 MHz):
d = 169.1 (C, C=O), 164.6 (C, CN3), 161.6 (C, CN2),
160.1 (C, C–OH), 159.8 (C, C-5), 131.9 (C, C-10) 130.1 (C,
CN), 128.9 (CH, C-20, C-60), 127.5 (CH, C-30, C-50), 126.8
(CH, C-40), 115.7 (CH, C-8), 103.1 (CH, C-4), 23.1 (CH3),
22.8 (CH3); MS: m/z 295 (M?1).
4-(2,4-Dichlorobenzylidene)-1-(4-hydroxy-6-
methylpyrimidin-2-yl)-2-methyl-1H-imidazol-5(4H)-
one (4f)
% Yield: 66; MW: 363.19; MF: C16H12N4O2; MP:
236–238; IR (KBr): 3391, 3042, 2897, 1735, 1638, 1575,
1
1454, 864, 762, 658 cm-1; H NMR (DMSO, 400 MHz):
d 10.9 (s, 1H, OH), 7.8–7.2 (m, 4H, Ar–H), 5.8 (s, 1H,
–C=CH–), 2.7–2.3 (m, 6H, CH3); 13C NMR (DMSO,
400 MHz): d = 171.8 (C, C=O), 164.1 (C, CN3), 162.3 (C,
CN2), 155.1 (C, C–OH), 154.3 (C, C-5), 136.3 (C, C–Cl),
133.5 (C, C-10), 129.6 (C, C–Cl), 128.6 (CH, C-60), 127.9
(CH, C-30), 127.0 (C, CN), 125.9 (CH, C-50), 116.2 (CH,
C-8), 102.4 (CH, C-4), 23.9 (CH3), 22.5 (CH3); MS: m/
z 363 (M?1).
1-(4-Hydroxy-6-methylpyrimidin-2-yl)-4-(2-
hydroxybenzylidene)-2-methyl-1H-imidazol-5(4H)-
one (4c)
% Yield: 51; MW: 310.30; MF: C16H14N4O3; MP:
190–192; IR (KBr): 3563, 3052, 2959, 1734, 1650, 1602,
1
1443, 888 cm-1; H NMR (DMSO, 400 MHz): d 11.9 (s,
1H, OH), 7.9–7.2 (m, 6H, Ar–H), 5.8 (s, 1H, –C=CH–), 5.1
(s, 1H, OH), 2.5–2.2 (m, 6H, CH3); 13C NMR (DMSO,
400 MHz): d = 171.3 (C, C=O), 162.9 (C, CN3), 160.8 (C,
CN2),159.8 (C, C–OH), 157.7 (C, C-5), 151.1 (C, C–OH),
130.5 (C, CN), 129.1 (C, C-10), 128.3 (CH, C-40), 127.6
(CH, C-20), 126.2 (CH, C-30), 121.3 (CH, C-50), 114.9 (CH,
C-8), 102.9 (CH, C-4), 24.1 (CH3), 23.2 (CH3); MS: m/
z 311 (M?1).
4-(4-(Dimethyl amino) benzylidene)-1-(4-hydroxy-6-
methylpyrimidin-2-yl)-2-methyl-1H-imidazol-5(4H)-
one (4g)
% Yield: 67; MW: 337.37; MF: C18H19N5O2; MP:
310–312; IR (KBr): 3410, 3052, 2959, 1734, 1650, 1602,
123

Med Chem Res
1
1443, 888 cm-1; H NMR (DMSO, 400 MHz): d 11.8 (s,
4-Benzylidene-1-(4-hydroxy-6-methylpyrimidin-2-yl)-2-
phenyl-1H-imidazol-5(4H)-one (4k)
1H, OH), 8.0–7.2 (m, 5H, Ar–H), 6.1 (s, 1H, –C=CH–), 3.2
(s, 6H, CH3), 2.1–2.2 (m, 6H); 13C NMR (DMSO,
400 MHz): d = 170.1 (C, C=O), 166.3 (C, CN3), 160.5 (C,
CN2), 156.5 (C, C–OH), 153.2 (C, C-5), 151.2 (C, C-40),
134.2 (C, CN), 130.3 (C, C-10), 126.8 (CH, C-20 C-60),
125.6 (CH, C-30, C-50), 114.1 (CH, C-8), 102.3 (CH, C-4),
41.2 (CH3, N(CH3)2), 24.9 (CH3), 23.1 (CH3); MS: m/z 338
(M?1).
% Yield: 56; MW: 356.37; MF: C21H16N4O2; MP:
180–182; IR (KBr): 3381, 3050, 1790, 1651, 1596, 1489,
1
886 cm-1; H NMR (DMSO, 400 MHz): d 11.3 (s, 1H),
7.8–7.2 (m, 11H), 5.6 (s, 1H), 2.2 (s, 3H); 13C NMR
(DMSO, 400 MHz): d = 169.6 (C, C=O), 161.3 (C, CN3),
160.2 (C, CN2), 151.3 (C, C–OH), 150.3 (C, C-5), 134.0
(C, C-10), 133.1 (C, CN), 132.3 (C, C100), 128.4 (CH, C-300,
C-500), 128.2 (CH, C-30, C-50), 128.0 (CH, C-20, C-60),
127.8 (CH, C-200, C-600), 127.3 (CH, C-40), 126.9 (CH,
C-400), 113.2 (CH, C-8), 102.1 (CH, C-4), 23.3 (CH3); MS:
m/z 357 (M?1).
4-((1H-Indol-3-yl)methylene)-1-(4-hydroxy-6-
methylpyrimidin-2-yl)-2-methyl-1H-imidazol-5(4H)-
one (4h)
% Yield: 56; MW: 333.34; MF: C18H15N5O2; MP:
190–192; IR (KBr): 3425, 3353, 3053, 2972, 1750, 1662,
4-(4-Chlorobenzylidene)-1-(4-hydroxy-6-
methylpyrimidin-2-yl)-2-phenyl-1H-imidazol-5(4H)-
one (4l)
1618, 1444, 1380, 868 cm-1
;
1H NMR (DMSO,
400 MHz): d 11.1 (s, 1H, OH), 10.1 (s, 1H, OH), 7.8–7.0
(m, 5H, Ar–H), 5.6 (s, 1H, –C=CH–), 2.4–2.2 (m, 6H,
CH3); 13C NMR (DMSO, 400 MHz): d = 167.1 (C, C=O),
165.2 (C, CN3), 162.6 (C, CN2), 154.5 (C, C–OH), 151.3
(C, C-5), 133.2 (C, CN), 132.1 (C, C-30), 131.5 (CH, C-20),
128.3 (C, C-80), 125.0 (C, C-10), 124.2 (CH, C-40), 123.9
(CH, C-70), 121.2 (CH, C-50, C-60), 113.4 (CH, C-8), 102.1
(CH, C-4), 25.1 (CH3), 23.5 (CH3); MS: m/z 334 (M?1).
% Yield: 69; MW: 390.82; MF: C21H15ClN4O2; MP:
202–204; IR (KBr): 3426, 3063, 2986, 1754, 1582, 1651,
1
1446, 865 cm-1; H NMR (DMSO, 400 MHz): d 11.2 (s,
1H), 7.8–7.3 (m, 10H), 5.4 (s, 1H), 2.3 (s, 3H); 13C NMR
(DMSO, 400 MHz): d = 168.9 (C, C=O), 161.5 (C, CN3),
160.6 (C, CN2), 150.9 (C, C–OH), 149.8 (C, C-5), 134.2
(C, C-10), 133.9 (C, CN), 133.5 (C, C–Cl), 132.1 (C, C-100),
129.1 (CH, C-300, C-500), 128.9 (CH, C-30, C-50), 127.5 (CH,
C-20, C-60), 126.8 (CH, C-200, C-600), 126.1 (CH, C-400),
112.5 (CH, C-8), 101.8 (CH, C-4), 23.5 (CH3); MS: m/
z 391 (M?1).
4-Ethylidene-1-(4-hydroxy-6-methylpyrimidin-2-yl)-2-
methyl-1H-imidazol-5(4H)-one (4i)
% Yield: 45; MW: 232.23; MF: C11H12N4O2; MP:
194–198; IR (KBr): 3389, 2984, 2877, 1735, 1632, 1585,
1
1441, 884 cm-1; H NMR (DMSO, 400 MHz): d 11.3 (s,
4-(2,4-Dichlorobenzylidene)-1-(4-hydroxy-6-
methylpyrimidin-2-yl)-2-phenyl-1H-imidazol-5(4H)-
one (4m)
1H, OH), 6.8 (s, 1H, Ar–H), 5.8 (s, 1H, –C=CH–), 2.5–2.2
(m, 9H, CH3); 13C NMR (DMSO, 400 MHz): d = 169.1
(C, C=O), 164.3 (C, CN3), 162.9 (C, CN2), 153.5 (C, C–
OH), 150.2 (C, C-5), 131.5 (C, CN), 112.1 (CH, C-8),
101.3 (CH, C-4), 23.9 (CH3), 22.5 (CH3), 10.2 (CH3); MS:
m/z 333 (M?1).
% Yield: 68; MW: 425.26; MF: C21H14Cl2N4O2; MP:
178–180; IR (KBr):3391, 3063, 2986, 1754, 1582, 1651,
1
1446, 865 cm-1; H NMR (DMSO, 400 MHz): d 11.5 (s,
1H), 7.9–7.1 (m, 9H), 5.3 (s, 1H), 2.4 (s, 3H); 13C NMR
(DMSO, 400 MHz): d = 169.3 (C, C=O), 164.1 (C, CN3),
162.1 (C, CN2), 155.1 (C, C–OH), 152.3 (C, C-5), 136 (C,
C–Cl), 134.8 (C, C-10), 134.1 (C, CN), 133.1 (C, C–Cl),
132.6 (C, C-100), 128.6 (CH, C-300, C-500), 127.9 (CH, C-30,
C-50), 127.1 (CH, C-60), 126.5 (CH, C-200, C-600), 125.8
(CH, C-400), 113.1 (CH, C-8), 102.2 (CH, C-4), 24.1 (CH3);
MS: m/z 426 (M?1).
1-(4-Hydroxy-6-methylpyrimidin-2-yl)-4-(4-
methoxybenzylidene)-2-methyl-1H-imidazol-5(4H)-
one (4j)
% Yield: 68; MW: 324.33; MF: C17H16ClN4O3, IR (KBr):
3405, 3052, 2959, 1734, 1650, 1602, 1443, 1381,
1
888 cm-1; H NMR (DMSO, 400 MHz): d 11.3 (s, 1H,
OH), 8.1–7.3 (m, 5H, Ar–H), 5.9 (s, 1H, –C=CH–), 3.5 (s,
3H, OCH3), 2.5–2.2 (m, 6H, CH3); 13C NMR (DMSO,
400 MHz): d = 171.3 (C, C=O), 163.3 (C, CN3), 162.2 (C,
CN2), 158.2 (C, C-40), 152.2 (C, C–OH), 149.9 (C, C-5),
133.1 (C, CN), 126.8 (C, C-10), 125.3 (CH, C-20, C-60),
113.2 (C, C-30, C-50), 111.5 (CH, C-8), 101.6 (CH, C-4),
56.3 (OCH3), 24.2 (CH3), 23.3 (CH3); MS: m/z 325 (M?1).
4-(4-(Dimethyl amino) benzylidene)-1-(4-hydroxy-6-
methylpyrimidin-2-yl)-2-phenyl-1H-imidazol-5(4H)-
one (4n)
% Yield: 61; MW: 399.44; MF: C23H21N5O2; MP: 250; IR
(KBr): 3385, 3052, 2920, 1725,1606,1648,1449,891 cm-1
;
123

Med Chem Res
1H NMR (DMSO, 400 MHz): d 11.3 (s, 1H), 8.1–7.5 (m,
10H), 5.4 (s, 1H), 3.2 (s, 6H), 2.1 (s, 3H); 13C NMR
(DMSO, 400 MHz): d = 169.1 (C, C=O), 163.9 (C, CN3),
160.5 (C, CN2), 154.6 (C, C–OH), 151.4 (C, C-5), 150.1
(C, C–C40), 134.2 (C, C-10), 131.3 (C, CN), 130.6 (C,
C-100), 128.1 (CH, C-300, C-500), 127.7 (CH, C-30, C-50),
126.3 (CH, C-20, C-60), 125.5 (CH, C-200, C-600), 124.7 (CH,
C-400), 114.2 (CH, C-8), 101.6 (CH, C-4), 41.1 (-N(CH3)2),
25.1 (CH3); MS: m/z 400 (M?1).
152.5 (C, C-5), 147.1 (C, C-30), 144.2 (C, C–C40), 134.3
(C, C-100), 133.2 (C, C-10), 131.8 (C, CN), 130.3 (CH,
C-400), 128.5 (CH, C-300, C-500), 127.2 (CH, C-200, C-600),
123.2 (CH, C-60), 122.1 (C, C-20), 119.9 (C, C-50), 113.2
(CH, C-8), 101.3 (CH, C-4), 60.3 (OCH3), 24.2 (CH3); MS:
m/z 403 (M?1).
4-Ethylidene-1-(4-hydroxy-6-methylpyrimidin-2-yl)-2-
phenyl-1H-imidazol-5(4H)-one (4r)
1-(4-Hydroxy-6-methylpyrimidin-2-yl)-4-(2-
hydroxybenzylidene)-2-phenyl-1H-imidazol-5(4H)-one
(4o)
% Yield: 53; MW: 294.30; MF: C16H14N4O2; MP: 140; IR
(KBr): 3405, 2984, 2877, 1735, 1632, 1585, 1441,
1
884 cm-1; H NMR (DMSO, 400 MHz): d 11.4 (s, 1H),
7.8–7.3 (m, 6H), 5.6 (s, 1H), 2.4–2.2 (s, 6H); 13C NMR
(DMSO, 400 MHz): d = 169.1 (C, C=O), 163.2 (C, CN3),
162.1 (C, CN2), 159.2 (C, C–OH), 152.9 (C, C-5), 134.8
(C, C-100), 130.3 (C, CN), 129.7 (CH, C-400), 128.1 (CH,
C-300, C-500), 126.9 (CH, C-200, C-600), 111.8 (CH, C-8),
100.1 (CH, C-4), 25.1 (CH3), 9.7 (CH3); MS: m/z 294
(M?1).
% Yield: 56; MW: 327.37; MF: C21H16N4O3; MP:
204–206; IR (KBr): 3563, 3055, 2962, 1746, 1650, 1604,
1
1443, 878 cm-1; H NMR (DMSO, 400 MHz): d11.5 (s,
1H), 7.6–6.9 (m, 10H), 5.8 (s, 1H), 5.3 (s, 1H), 2.1 (s, 3H);
13C NMR (DMSO, 400 MHz): d = 170.3 (C, C=O), 164.3
(C, CN3), 160.1 (C, CN2), 157.8 (C, C–OH), 157.1 (C,
C-20), 152.3 (C, C-5), 132.8 (C, C-10), 130.2 (C, CN), 129.5
(C, C-100), 128.5 (CH, C-300, C-500), 128.0 (CH, C-40), 127.2
(CH, C-60), 126.1 (CH, C-200, C-600), 123.9 (CH, C-400),
122.3 (CH, C-50), 121.9 (CH C-30), 112.5 (CH, C-8), 101.1
(CH, C-4), 24.1 (CH3); MS: m/z 373 (M?1).
1-(4-Hydroxy-6-methylpyrimidin-2-yl)-2-phenyl-4-
(3,4,5-trimethoxybenzylidene)-1H-imidazol-5(4H)-
one (4s)
% Yield: 68; MW: 446.45; MF: C24H22N3O5; MP:
118–120; IR (KBr): 3394, 3004, 2959, 1715, 1603, 1650,
4-(Furan-2-ylmethylene)-1-(4-hydroxy-6-
methylpyrimidin-2-yl)-2-phenyl-1H-imidazol-5(4H)-
one (4p)
1
1443, 888 cm-1; H NMR (DMSO, 400 MHz): d 11.5 (s,
1H), 7.9–7.2 (m, 8H), 5.4 (s, 1H), 3.9 (s, 9H), 2.2 (s, 3H);
13C NMR (DMSO, 400 MHz): d = 170.1 (C, C=O), 162.9
(C, CN3), 160.2 (C, CN2), 158.6 (C, C–OH), 153.6 (C,
C-5), 152.1 (C, C-30, C-50), 139.2 (C, C-40), 134.1 (C,
C-100), 130.8 (C, CN), 130.1 (C, C-10), 129.6 (CH, C-400),
127.8 (CH, C-300, C-500), 126.8 (CH, C-200, C-600), 103.2
(CH, C-20, C-60), 112.1 (CH, C-8), 103.1 (CH, C-4), 60.1
(OCH3), 56.3 (OCH3), 23.5 (CH3); MS: m/z 447 (M?1).
% Yield: 51; MW: 346.33; MF: C19H14N4O3; MP:
200–202; IR (KBr): 3399, 3055, 2962, 1746, 1650, 1604,
1
1443, 878 cm-1; H NMR (DMSO, 400 MHz): d 11.1 (s,
1H), 8.2–7.3 (m, 9H), 5.4 (s, 1H), 2.3 (s, 3H); 13C NMR
(DMSO, 400 MHz): d = 169.3 (C, C=O), 164.1 (C, CN3),
160.6 (C, CN2), 157.2 (C, C–OH), 151.2 (C, C-5), 150.9
(C, C-10), 143.2 (CH, C-20), 132.2 (C, CN), 130.2 (C,
C-100), 128.3 (CH, C-300, C-500), 127.6 (CH, C-200, C-600),
124.9 (CH, C-400), 112.1 (CH, C-30), 111.1 (CH, C-8),
108.2 (CH, C-40), 100.2 (CH, C-4), 23.5 (CH3); MS: m/
z 347 (M?1).
1-(4-Hydroxy-6-methylpyrimidin-2-yl)-4-(4-
methoxybenzylidene)-2-phenyl-1H-imidazol-5(4H)-
one (4t)
% Yield: 65; MW: 386.40; MF: C22H18N4O3; MP:
138–140; IR (KBr): 3417, 3023, 2917, 1730, 1575, 1646,
4-(4-Hydroxy-3-methoxybenzylidene)-1-(4-hydroxy-6-
methylpyrimidin-2-yl)-2-phenyl-1H-imidazol-5(4H)-
one (4q)
1
1447, 863 cm-1; H NMR (DMSO, 400 MHz): d 11.3 (s,
1H), 7.7–7.1 (m, 10H), 5.3 (s, 1H), 3.8 (s, 3H), 2.3 (s, 3H);
13C NMR (DMSO, 400 MHz): d = 171.3 (C, C=O), 163.3
(C, CN3), 162.3 (C, CN2), 158.1 (C, C–OH), 157.3 (C,
C-40), 152.8 (C, C-5), 134.8 (C, C-100), 130.2 (CH, C-20,
C-60), 129.3 (CH, C-200, C-600), 129.0 (CH, C-400), 128.6
(CH, C-300, C-500), 128.1 (C, C-10), 115.2 (CH, C-30, C-50),
113.0 (CH, C-8), 101.3 (CH, C-4), 56.3 (OCH3), 24.2
(CH3); MS: m/z 387 (M?1).
% Yield: 54; MW: 402.40; MF: C22H18N4O4; MP:
196–198; IR (KBr): 3563, 3052, 1734, 1650, 1602, 1443,
1
1381, 884 cm-1; H NMR (DMSO, 400 MHz): d 11.5 (s,
1H), 7.8–7.4 (m, 9H), 5.9 (s, 1H), 5.2 (s, 1H), 3.4 (s 3H),
2.2 (s, 3H); 13C NMR (DMSO, 400 MHz): d = 170.2 (C,
C=O), 162.3 (C, CN3), 160.1 (C, CN2), 158.6 (C, C–OH),
123

Med Chem Res
1-(4-Chloro-6-methylpyrimidin-2-yl)-4-(4-
chlorobenzylidene)-2-methyl-1H-imidazol-5(4H)-
one (5a)
116.1 (CH, C-8), 104.0 (CH, C-4), 24.3 (CH3), 22.9 (CH3);
MS: m/z 330 (M?1).
1-(4-Chloro-6-methylpyrimidin-2-yl)-4-(furan-2-
% Yield: 61; MW: 347.19; MF: C16H12Cl2N4O; MP:
210–212; IR (KBr): 3053, 2878, 1730, 1638, 1575, 1454,
ylmethylene)-2-methyl-1H-imidazol-5(4H)-one (5e)
1
876, 658 cm-1; H NMR (DMSO, 400 MHz): d 8.5–7.7
% Yield: 59; MW: 328.75; MF: C14H11ClN4O2; MP: 280;
IR (KBr): 3057, 2877, 1730, 1638, 1575, 1454, 878 cm-1
(m, 6H), 2.8 (s, 3H), 2.3 (s, 3H); 13C NMR (DMSO,
400 MHz): d = 172.6 (C, C=O), 165.1 (C, CN3), 162.1 (C,
CN2), 161.3 (C, C–Cl), 159.8 (C, C-5), 134.2 (C, C–Cl),
133.5 (C, C-10) 131.3 (C, CN), 129.2 (CH, C-20, C-60),
128.6 (CH, C-30, C-50), 115.2 (CH, C-8), 103.2 (CH, C-4),
24.2 (CH3), 22.5 (CH3); MS: m/z 348 (M?1).
;
1H NMR (DMSO, 400 MHz): d 7.8–6.3 (m, 5H), 2.8 (s,
3H), 2.3 (s, 3H); 13C NMR (DMSO, 400 MHz): d = 170.8
(C, C=O), 163.1 (C, CN3), 161.2 (C, CN2), 160.2 (C, C–
Cl), 154.2 (C, C-5), 151.2 (C, C-10), 141.5 (CH, C-20),
131.6 (C, CN), 116.1 (CH, C-8), 114.5 (CH, C-30), 112.1
(CH, C-40), 103.6 (CH, C-4), 23.9 (CH3), 23.1 (CH3); MS:
m/z 303 (M?1).
4-Benzylidene-1-(4-chloro-6-methylpyrimidin-2-yl)-2-
methyl-1H-imidazol-5(4H)-one (5b)
1-(4-Chloro-6-methylpyrimidin-2-yl)-2-methyl-4-(3,4,5-
% Yield: 64; MW: 312.75; MF: C16H13ClN4O; MP:
204–208; IR (KBr): 3057, 2877, 1730, 1638, 1575, 1454,
trimethoxybenzylidene)-1H-imidazol-5(4H)-one (5f)
1
878 cm-1; H NMR (DMSO, 400 MHz): d 8.4–7.5 (m,
% Yield: 68; MW: 402.83; MF: C19H19ClN4O4; MP: 165;
IR (KBr): 3050, 2959, 1744, 1658, 1612, 1447, 1386,
7H), 2.8 (s, 3H), 2.2 (s, 3H); MS: m/z 314 (M?1); 13C
NMR (DMSO, 400 MHz): d = 170.2 (C, C=O), 165.6 (C,
CN3), 162.3 (C, CN2), 161.5 (C, Cl), 160.1 (C, C-5), 132.9
(C, C-10) 131.0 (C, CN), 127.9 (CH, C-20, C-60), 127.0
(CH, C-30, C-50), 126.1 (CH, C-40), 115.1 (CH, C-8), 103.5
(CH, C-4), 23.5 (CH3), 22.6 (CH3); MS: m/z 348 (M?1).
1
875 cm-1; H NMR (DMSO, 400 MHz): d 7.8 (m, 1H),
6.9–6.3 (m, 3H), 3.8 (s, 9H), 2.9 (s, 3H), 2.1 (s, 3H); 13C
NMR (DMSO, 400 MHz): d = 171.9 (C, C=O), 162.9 (C,
CN3), 161.0 (C, CN2), 160.5 (C, Cl), 154.9 (C, C-5), 153.5
(C, C-30, C-50), 139.5 (C, C-40), 131.8 (C, CN), 130.2 (C,
C-10), 119.5 (CH, C-20, C-60), 117.5 (CH, C-8), 102.1 (CH,
C-4), 60.6 (OCH3), 55.8 (OCH3), 23.9 (CH3), 22.5 (CH3);
MS: m/z 403 (M?1).
1-(4-Chloro-6-methylpyrimidin-2-yl)-4-(4-
methoxybenzylidene)-2-methyl-1H-imidazol-5(4H)-
one (5c)
1-(4-Chloro-6-methylpyrimidin-2-yl)-4-(2,4-
dichlorobenzylidene)-2-methyl-1H-imidazol-5(4H)-one
(5g)
% Yield: 67; MW: 342.78; MF: C17H15ClN4O2; MP:
178–180; IR (KBr): 3052, 2959, 1734, 1650, 1602, 1443,
1
1381, 888 cm-1; H NMR (DMSO, 400 MHz): d 8.1–7.3
(m, 6H), 3.5 (s, 3H), 2.7 (s, 3H), 2.3 (s, 3H); 13C NMR
(DMSO, 400 MHz): d = 172.5 (C, C=O), 164.1 (C, CN3),
163.1 (C, CN2), 160.2 (C, Cl), 159.1 (C, C-40), 150.1 (C,
C-5), 134.2 (C, CN), 127.3 (C, C-10), 125.2 (CH, C-20, C-60),
114.5 (C, C-30, C-50), 112.6 (CH, C-8), 102.8 (CH, C-4),
57.1 (OCH3), 24.9 (CH3), 23.1 (CH3); MS: m/z 344 (M?1).
% Yield: 62; MW: 381.64; MF: C16H11Cl3N4O; MP:
220–223; IR (KBr): 3042, 2897, 1735, 1638, 1575, 1454,
1
864, 762, 658 cm-1; H NMR (DMSO, 400 MHz): d 7.6
(m, 1H), 7.0–6.5 (m, 4H), 2.6 (s, 3H), 2.1 (s, 3H); 13C NMR
(DMSO, 400 MHz): d = 172.1 (C, C=O), 164.5 (C, CN3),
161.0 (C, CN2), 160.1 (C, Cl), 153.2 (C, C-5), 137.1 (C, C–
Cl), 134.1 (C, C-10), 128.9 (C, C–Cl), 128.0 (CH, C-60),
127.2 (CH, C-30), 126.1 (C, CN), 125.5 (CH, C-50), 115.9
(CH, C-8), 103.1 (CH, C-4), 23.2 (CH3), 22.1 (CH3); MS:
m/z 382 (M?1).
1-(4-Chloro-6-methylpyrimidin-2-yl)-4-(2-
hydroxybenzylidene)-2-methyl-1H-imidazol-5(4H)-one
(5d)
% Yield: 58; MW: 328.75; MF: C16H13ClN4O2; MP:
210-212; IR (KBr): 3563, 3052, 2959, 1734, 1650, 1602,
1-(4-Chloro-6-methylpyrimidin-2-yl)-4-(4-
(dimethylamino)benzylidene)-2-methyl-1H-imidazol-
5(4H)-one (5h)
1
1443, 888 cm-1; H NMR (DMSO, 400 MHz): d 8.4–7.3
(m, 6H), 5.8 (s, 1H), 2.9 (s, 3H), 2.3 (s, 3H); 13C NMR
(DMSO, 400 MHz): d = 173.1 (C, C=O), 163.1 (C, CN3),
162.1 (C, CN2),160.8 (C, Cl), 157.9 (C, C-5), 152.3 (C, C–
OH), 129.9 (C, CN), 129.0 (C, C-10), 128.8 (CH, C-40),
128.0 (CH, C-20), 127.1 (CH, C-30), 120.5 (CH, C-50),
% Yield: 71; MW: 355.82; MF: C18H18ClN5O; MP:
148–150; IR (KBr): 3052, 2959, 1734, 1650, 1602, 1443,
888 cm-1; 1H NMR (DMSO, 400 MHz): d 8.2–7.3 (m, 6H),
3.1 (s, 6H), 2.7 (s, 3H), 2.2 (s, 3H); 13C NMR (DMSO,
123

Med Chem Res
1
400 MHz): d = 171.9 (C, C=O), 165.1 (C, CN3), 162.1 (C,
CN2), 161.5 (C, Cl), 154.1 (C, C-5), 152.1 (C, C-40), 135.6
(C, CN), 131.2 (C, C-10), 127.1 (CH, C-20 C-60), 126.6 (CH,
C-30, C-50), 115.5 (CH, C-8), 102.8 (CH, C-4), 40.9 (CH3,
N(CH3)2), 23.6 (CH3), 22.4 (CH3); MS: m/z 356 (M?1).
865 cm-1; H NMR (DMSO, 400 MHz): d 7.10–7.45 (m,
10H), 6.7 (s, 1H), 2.2 (s, 3H); 13C NMR (DMSO,
400 MHz): d = 171.0 (C, C=O), 163.5 (C, CN3), 162.6 (C,
CN2), 160.9 (C, Cl), 148.4 (C, C-5), 132.1 (C, C-10), 131.2
(C, CN), 130.4 (C, C–Cl), 129.6 (C, C-100), 128.4 (CH,
C-300, C-500), 128.0 (CH, C-30, C-50), 127.1 (CH, C-20, C-60),
126.2 (CH, C-200, C-600), 125.1 (CH, C-400), 113.1 (CH,
C-8), 102.5 (CH, C-4), 22.5 (CH3); MS: m/z 410 (M?1).
4-((1H-indol-3-yl)methylene)-1-(4-chloro-6-
methylpyrimidin-2-yl)-2-methyl-1H-imidazol-5(4H)-
one (5i)
1-(4-Chloro-6-methylpyrimidin-2-yl)-4-(2,4-
dichlorobenzylidene)-2-phenyl-1H-imidazol-5(4H)-one
(5m)
% Yield: 60; MW: 351.79; MF: C18H14ClN5O; MP:
186–190; IR (KBr): 3353, 3053, 2972, 1750, 1662, 1618,
1
1444, 1380, 868 cm-1; H NMR (DMSO, 400 MHz): d
10.2 (s, 1H), 8.3–7.4 (m, 7H), 2.6 (s, 3H), 2.1 (s, 3H); 13C
NMR (DMSO, 400 MHz): d = 170.2 (C, C=O), 165.0 (C,
CN3), 162.2 (C, CN2), 160.1 (C, Cl), 152.3 (C, C-5), 134.1
(C, CN), 131.9 (C, C-30), 130.6 (CH, C-20), 128.8 (C, C-80),
126.1 (C, C-10), 125.1 (CH, C-40), 123.1 (CH, C-70), 122.1
(CH, C-50, C-60), 115.1 (CH, C-8), 101.8 (CH, C-4), 24.7
(CH3), 23.6 (CH3); MS: m/z 352 (M?1).
% Yield: 76; MW: 443.71; MF: C21H13Cl3N4O; MP:
218–220; IR (KBr): 3063, 2986, 1754, 1582, 1651, 1446,
1
865 cm-1; H NMR (DMSO, 400 MHz): d 8.5–7.6 (m,
9H), 6.7 (s, 1H), 2.1 (s, 3H); 13C NMR (DMSO, 400 MHz):
d = 170.8 (C, C=O), 163.8 (C, CN3), 162.4 (C, CN2),
161.1 (C, Cl), 154.1 (C, C-5), 135.8 (C, C–Cl), 134.4 (C,
C-10), 133.2 (C, CN), 132.8 (C, C–Cl), 132.0 (C, C-100),
128.1 (CH, C-300, C-500), 127.1 (CH, C-30, C-50), 126.3 (CH,
C-60), 125.8 (CH, C-200, C-600), 124.6 (CH, C-400), 114.6
(CH, C-8), 102.8 (CH, C-4), 24.5 (CH3); MS: m/z 444
(M?1).
1-(4-Chloro-6-methylpyrimidin-2-yl)-4-ethylidene-2-
methyl-1H-imidazol-5(4H)-one (5j)
% Yield: 55; MW: 250.68; MF: C11H11ClN4O; MP:
255–257; IR (KBr): 2984, 2877, 1735, 1632, 1585, 1441,
1-(4-Chloro-6-methylpyrimidin-2-yl)-4-(4-
(dimethylamino)benzylidene)-2-phenyl-1H-imidazol-
5(4H)-one (5n)
1
884 cm-1; H NMR (DMSO, 400 MHz): d 6.96–6.15 (m,
2H), 2.52 (d, 3H), 2.5 (s, 3H), 2.1 (s, 3H); 13C NMR
(DMSO, 400 MHz): d = 171.5 (C, C=O), 164.1 (C, CN3),
162.0 (C, CN2), 161.1 (C, Cl), 151.1 (C, C-5), 130.1 (C,
CN), 111.5 (CH, C-8), 100.9 (CH, C-4), 23.4 (CH3), 22.1
(CH3), 9.6 (CH3); MS: m/z 251 (M?1).
% Yield: 67; MW: 417.89; MF: C23H20ClN5O2; MP:
265–267; IR (KBr): 3052, 2920, 1725,1606,1648,1449,
1
891 cm-1; H NMR (DMSO, 400 MHz): d 8.5–7.65 (m,
8H), 6.8–6.65 (m, 3H), 3. 1 (s, 6H), 2.4 (s, 3H); 13C NMR
(DMSO, 400 MHz): d = 172.1 (C, C=O), 163.2 (C, CN3),
162.1 (C, CN2), 161.2 (C, Cl), 152.1 (C, C-5), 151.2 (C, C–
C40), 133.1 (C, C-10), 131.6 (C, CN), 130.9 (C, C-100),
128.6 (CH, C-300, C-500), 128.0 (CH, C-30, C-500), 127.1
(CH, C-20, C-60), 126.1 (CH, C-200, C-600), 124.9 (CH,
C-400), 114.1 (CH, C-8), 101.2 (CH, C-4), 42.0 (-N(CH3)2),
24.2 (CH3); MS: m/z 418 (M?1).
4-Benzylidene-1-(4-chloro-6-methylpyrimidin-2-yl)-2-
phenyl-1H-imidazol-5(4H)-one (5k)
% Yield: 70; MW: 374.82; MF: C21H15ClN4O; MP:
202–204; IR (KBr): 3050, 1790, 1651, 1596, 1489,
1
886 cm-1; H NMR (DMSO, 400 MHz): d 7.25–7.65 (m,
11H), 6.8 (s, 1H), 2.5 (s, 3H); 13C NMR (DMSO,
400 MHz): d = 172.1 (C, C=O), 162.1 (C, CN3), 161.9 (C,
CN2), 159.9 (C, Cl), 149.8 (C, C-5), 134.5 (C, C-10), 132.6
(C, CN), 131.8 (C, C100), 128.1 (CH, C-300, C-500), 127.5
(CH, C-30, C-50), 126.8 (CH, C-20, C-60), 126.1 (CH, C-200,
C-600), 125.5 (CH, C-40), 124.3 (CH, C-400), 114.5 (CH,
C-8), 103.4 (CH, C-4), 23.4 (CH3); MS: m/z 375 (M?1).
1-(4-Chloro-6-methylpyrimidin-2-yl)-4-(2-
hydroxybenzylidene)-2-phenyl-1H-imidazol-5(4H)-one
(5o)
% Yield: 69; MW: 390.82; MF: C21H15ClN4O2; MP: 240;
IR (KBr): 3563, 3055, 2962, 1746, 1650, 1604, 1443,
1
1-(4-Chloro-6-methylpyrimidin-2-yl)-4-(4-
chlorobenzylidene)-2-phenyl-1H-imidazol-5(4H)-one
(5l)
878 cm-1; H NMR (DMSO, 400 MHz): d 8.1–7.5 (m,
8H), 6.8–6.65 (m, 3H), 5. 8 (s, 1H), 2.3 (s, 3H); 13C NMR
(DMSO, 400 MHz): d = 171.2 (C, C=O), 164.5 (C, CN3),
162.3 (C, CN2), 160.8 (C, Cl), 157.5 (C, C-20), 151.9 (C,
C-5), 133.1 (C, C-10), 131.5 (C, CN), 130.5 (C, C-100),
128.9 (CH, C-300, C-500), 127.5 (CH, C-40), 126.2 (CH,
% Yield: 72; MW: 409.26; MF: C21H14Cl2N4O; MP:
222–224; IR (KBr): 3063, 2986, 1754, 1582, 1651, 1446,
123

Med Chem Res
1
C-60), 125.6 (CH, C-200, C-600), 124.2 (CH, C-400), 121.5
(CH, C-50), 120.6 (CH C-30), 113.3 (CH, C-8), 102.4 (CH,
C-4), 23.5 (CH3); M.S: m/z 391 (M?1).
888 cm-1; H NMR (DMSO, 400 MHz): d 8.4–7.65 (m,
6H), 6.7–6.5 (m, 3H), 3. 6 (s, 9H) 2.4 (s, 3H); 13C NMR
(DMSO, 400 MHz): d = 171.2 (C, C=O), 163.5 (C, CN3),
161.5 (C, CN2), 159.8 (C, Cl), 152.8 (C, C-5), 152.0 (C,
C-30, C-50), 140.1 (C, C-40), 135.1 (C, C-100), 132.4 (C,
CN), 131.1 (C, C-10), 130.1 (CH, C-400), 127.5 (CH, C-300,
C-500), 126.4 (CH, C-200, C-600), 103.1 (CH, C-20, C-60),
112.8 (CH, C-8), 102.4 (CH, C-4), 61.5 (OCH3), 55.8
(OCH3), 23.6 (CH3); MS: m/z 465 (M?1).
1-(4-Chloro-6-methylpyrimidin-2-yl)-4-(furan-2-
ylmethylene)-2-phenyl-1H-imidazol-5(4H)-one (5p)
% Yield: 62; MW: 364.78; MF: C19H13ClN4O2; MP:
240–242; IR (KBr): 3055, 2962, 1746, 1650, 1604, 1443,
1
878 cm-1; H NMR (DMSO, 400 MHz): d 8.2–7.5 (m,
7H), 7.1–6.7 (m, 3H), 2.1 (s, 3H); 13C NMR (DMSO,
400 MHz): d = 171.2 (C, C=O), 164.5 (C, CN3), 161.6 (C,
CN2), 160.1 (C, Cl), 152.6 (C, C-5), 151.0 (C, C-10), 145.1
(CH, C-20), 133.8 (C, CN), 131.6 (C, C-100), 129.1 (CH,
C-300, C-500), 128.1 (CH, C-200, C-600), 125.0 (CH, C-400),
114.5 (CH, C-30), 110.6 (CH, C-8), 109.1 (CH, C-40), 99.5
(CH, C-4), 22.9 (CH3);M.S: m/z 365 (M?1).
1-(4-Chloro-6-methylpyrimidin-2-yl)-4-(4-
methoxybenzylidene)-2-phenyl-1H-imidazol-5(4H)-
one (5t)
% Yield: 70; MW: 404.84; MF: C22H17ClN4O2; MP:
158–160; IR (KBr): 3023, 2917, 1730, 1575, 1646, 1447,
863 cm-1; 1H NMR (DMSO, 400 MHz): d 8.3–7.3 (m, 8H),
6.9–6.5 (m, 3H), 3. 7 (s, 3H) 2.2 (s, 3H); 13C NMR (DMSO,
400 MHz): d = 173.1 (C, C=O), 164.1 (C, CN3), 162.5 (C,
CN2), 160.5 (C, Cl), 157.9 (C, C-400), 151.4 (C, C-5), 135.3
(C, C-100), 131.3 (CH, C-20, C-60), 130.2 (CH, C-200, C-600),
129.8 (CH, C-400), 129.1 (CH, C-300, C-500), 128.0 (C, C-10),
114.9 (CH, C-30, C-50), 113.3 (CH, C-8), 101.4 (CH, C-4),
57.3 (OCH3), 24.5 (CH3); MS: m/z 405 (M?1).
1-(4-Chloro-6-methylpyrimidin-2-yl)-4-(3-hydroxy-4-
methoxybenzylidene)-2-phenyl-1H-imidazol-5(4H)-
one (5q)
% Yield: 70; MW: 402.40; MF: C22H17ClN4O3; MP:
260–262; IR (KBr): 3563, 3052, 1734, 1650, 1602, 1443,
1
1381, 884 cm-1; H NMR (DMSO, 400 MHz): d 8.6–7.5
(m, 10H), 5. 6 (s, 1H), 3.6 (s, 3H) 2.3 (s, 3H); 13C NMR
(DMSO, 400 MHz): d = 171.2 (C, C=O), 162.8 (C, CN3),
162.1 (C, CN2), 161.1 (C, C–OH), 153.1 (C, C-5), 148.0
(C, 0C-30), 146.1 (C, C–C40), 133.1 (C, C-100), 132.7 (C,
C-1 ), 131.9 (C, CN), 131.2 (CH, C-400), 129.1 (CH, C-300,
C-500), 128.1 (CH, C-200, C-600), 122.4 (CH, C-60), 120.1 (C,
C-20), 119.2 (C, C-50), 113.8 (CH, C-8), 101.4 (CH, C-4),
60.5 (OCH3), 23.1 (CH3); MS: m/z 421 (M?1).
In vitro anti-HIV activity
The 20 lg/ml of finely powdered test compounds (4a–
t) in DMSO was used for in-vitro assay. The HIV-1 RT
inhibition assay was performed by using RT assay kit
(Roche) and carried out as described in kit protocol.
Briefly, the reaction mixture was set with template primer
complex, dNTPs and RT enzyme in the lysis buffer with
or without inhibitors. After 1 h incubation at 37 °C, the
reaction mixture was transferred to streptavidine-coated
microtitre plate (MTP). The biotin-labeled dNTPs that are
incorporated in the template due to activity of RT were
bound to streptavidine. The unbound dNTPs were washed
using wash buffer and anti-DIG-POD was added to the
MTP. The DIG-labeled dNTPs incorporated in the tem-
plate were bound to anti-DIG-POD antibody. The
unbound anti-DIG-POD was washed and the peroxide
substrate (ABST) was added to the MTP. A colored
reaction product was produced during the cleavage of the
substrate catalyzed by a peroxide enzyme. The absorbance
of the sample was determined at optical density (OD),
405 nm using micro titer plate ELISA reader. The %
inhibition was calculated using following formula.
1-(4-Chloro-6-methylpyrimidin-2-yl)-4-ethylidene-2-
phenyl-1H-imidazol-5(4H)-one (5r)
% Yield: 60; MW: 312.75; MF: C16H13ClN4O; MP:
248–250; IR (KBr): 2984, 2877, 1735, 1632, 1585, 1441,
1
884 cm-1; H NMR (DMSO, 400 MHz): d 8.2–7.5 (m,
5H), 6.86.65 (m, 2H), 2.6 (s, 3H), 2.3 (s, 3H); 13C NMR
(DMSO, 400 MHz): d = 171.8 (C, C=O), 162.1 (C, CN3),
161.0 (C, CN2), 159.1 (C, Cl), 156.1 (C, C-5), 133.5 (C,
C-100), 129.3 (C, CN), 128.7 (CH, C-400), 127.0 (CH, C-300,
C-500), 125.9 (CH, C-200, C-600), 112.6 (CH, C-8), 100.5
(CH, C-4), 24.6 (CH3), 10.1 (CH3); MS: m/z 313 (M?1).
1-(4-Chloro-6-methylpyrimidin-2-yl)-2-phenyl-4-
(3,4,5-trimethoxybenzylidene)-1H-imidazol-5(4H)-
one (5s)
% inhibition
ꢀ
ꢁ
OD at 405 nm with inhibitor
% Yield: 71; MW: 464.90; MF: C24H22ClN4O4; MP:
284-286; IR (KBr): 3004, 2959, 1715, 1603, 1650, 1443,
¼ 100 ꢁ
ꢂ 100
OD at 405 nm without inhibitor
123

Med Chem Res
acetate to give 4-(substituted ethylidene/benzylidene)-2-
methyloxazol-5-ones (3a–j). Benzoyl glycine was used to
synthesize the intermediates 3k–t. Benzoyl glycine (2) was
first synthesized from glycine by reacting with benzoyl
chloride in alkaline condition and further subjected to cy-
clocondensation with aliphatic or aromatic aldehydes in the
presence of acetic anhydride and anhydrous potassium
acetate to get 4-(substituted ethylidene/benzylidene)-2-
phenyloxazole-5-ones (Furnis et al., 2005) (3k–t).
The target compounds 4-substituted ethylidene/benzyli-
dene-1-(4-hydroxy/chloro-6-methylpyrimidin-2-yl)-2-methyl/
phenyl-1H-imidazol-5(4H)-ones (4a–t and 5a–t) were
obtained by reacting 4-substituted ethylidene/benzylidene-
2-methyl/phenyl oxazol-5-ones (3a–t) with 2-amino-6-
methylpyrimidin-4-ol or 4-chloro-6-methylpyrimidin-2-
amine.
Docking methodology
Molecular docking studies were performed using Glide
¨
v5.6 (Schrodinger, LLC). The coordinate for RT enzyme
was taken from RCSB Protein Data Bank (PDB Id. 1FKP)
and prepared for docking using protein preparation wizard.
Water molecules in the enzyme structure were removed
and termini were capped by adding ACE and NMA resi-
due. The bond orders and formal charges were added for
heterogroups and the hydrogens were added to all atoms.
The side chains that were not close to the binding cavity
and not participate in salt bridges, were neutralized. After
preparation, the structure was refined to optimize the
hydrogen bond network using OPLS_2005 force field. This
helps in reorientation of side chain hydroxyl group. The
minimization was terminated when the energy converged
˚
or the RMSD reached a maximum cutoff of 0.30 A. Grid
was then defined around active site of enzyme by centering
on ligand using default box size. The extra precision (XP)
docking mode of Glide was used for docking of com-
pounds, optimized by Ligprep, on generated grid of protein
structure (Friesner et al., 2006).
Biological screening
A group of imidazole-5-one derivatives along with methyl-
pyrimidine ring was prepared to investigate the effect of
substitution at R and R1 position of imidazole ring on HIV-1
RT activity. All title compounds (4a–5t) were tested for
antiviral activity against HIV-1 RT using in-vitro RT assay. It
was observed that most of the newly synthesized compounds
such as 4c, 4d, 4e, 4h, 5a, 5e, 5f and 5j possess notable HIV-1
RT inhibitory activity (Table 1). Among them, the com-
pounds 4c, 4d, 4e, 5a and 5e in which 2-hydroxyphenyl,
furan-2-yl, 3,4,5-trimethoxyphenyl, 4-chlorophenyl, and
furan-2-yl groups substituted at R1 position, respectively,
showed significantly more HIV-1 RT inhibitory activity. The
compounds bearing bulky substituents along with electron
withdrawing groups at R1 position of imidazole-5-one ring
showed higher HIV-1 RT inhibitory activity (compounds 4c,
Result and discussion
Chemistry
The synthesis of target compounds 4a–t and 5a–t is out-
lined in Scheme 1. Acetyl glycine was used to synthesize
intermediates 3a–j. Glycine on reaction with acetic anhy-
dride gave acetyl glycine (1) which further subjected to
cyclocondensation with aliphatic or aromatic aldehydes in
the presence of acetic anhydride and anhydrous potassium
R1
N
R1
O
O
O
a
c
N
d
H
O
H
3C
N
N
H
H
3C
N
N
O
O
X
H
3C
O
1
H2N
3a-3j
H
O
4a-4j & 5a-5j
R1
R1
O
O
N
d
H
b
c
N
N
O
H
O
O
N
O
N
N
2
3k-3t
X
4k-4t & 5a-5t
Scheme 1 The scheme for synthesis of final compounds (4a–5t) reagents and condition: a water, b 10 % NaOH, c substituted aldehyde
(R1CHO), potassium acetate, acetic anhydride, d AcOH, 2-amino-6-methylpyrimidin-4-ol or 4-chloro-6-methylpyrimidin-2-amine
123

Med Chem Res
4d, 4e, 5a and 5e). However as bulkiness at R1 position of
imidazole-5-one ring decreased, the HIV-1 RT inhibitory
activity was also decreased (compounds 4i, 4r and 5r). Thus,
it can be said that RT inhibitory activity of compounds is
sensitive to the size and nature of substituent at their R1
position. The compounds 4a–4j and 5a–5j in which methyl
group is substituted at R position of imidazole-5-one ring
showed higher HIV-1 RT inhibitory activity than the com-
pounds 4k–4t and 5k–5t possessing phenyl group at R posi-
tion. Thus, it is suggested that compounds with less
hydrophobic group at R position on the imidazole-5-one ring
would be better for the HIV-1 RT inhibitory activity.
procedure was first evaluated by comparing binding con-
formation of co-crystalized inhibitor predicted by extra
precision (XP) Glide docking mode and experimental
binding mode as determined by X-ray crystallography. The
˚
root mean square deviations of 1.28 and 0.26 A were found
for flexible and rigid docking, respectively, which suggests
the reliability of docking procedure.
Docking score (G-score) of all compounds against HIV-
1 RT enzyme is shown in Table 1. The most of compounds
showed good correlation of virtual docking score with their
experimental activity. All docked compounds adopted a
similar conformation and position in the active binding site
of HIV-1 RT structure. For most of compounds, the ligand–
enzyme complex was primarily stabilized by hydrophobic
interactions and specific polar hydrogen bonds. The side
chain, 4-hydroxy/chloro-6-methylpyrimidine ring (One of
the wing of butterfly shape) of imidazole-5-ones analogs
pointed toward hydrophobic pocket was formed by Leu
100, Val 106, Leu 234, and Tyr 318 amino acid residues.
Docking studies
To rationalize most relevant SAR and to predict the bind-
ing affinity of synthesized compounds, the docking studies
were carried out on X-ray coordinates of HIV-1 RT
enzyme (PDB Id 1FKP). The accuracy of a docking
Table 1 In vitro HIV-RT inhibition data of compounds 4a–t and 5a–t
R
N
N
N
N
X
R1
O
4a–t X = OH; 5a–5t X = Cl; 4a–j and 5a–j R = CH3; 4k–t and 5k–t R = C6H5
Comp.
R1
% Inhibitiona
G-score
Comp.
R1
% Inhibitiona
G-score
4a
–4-ClC6H4
60.77
65.86
71.15
83.03
71.33
56.24
65.86
67.94
53.60
51.60
47.75
60.58
48.69
49.45
51.26
49.12
54.54
50.58
57
-7.50
-6.94
-9.15
-9.88
-9.10
-7.12
-8.32
-8.50
-6.42
-6.75
-5.80
-6.80
-6.01
-6.15
-5.80
-7.49
-6.81
-7.15
-6.20
-5.40
-11.50
5a
5b
5c
5d
5e
5f
–4-ClC6H4
72.84
61.71
56.05
65.67
86.24
67.56
60.77
66.81
58.88
67.56
52.28
52.09
54.16
52.47
46.43
53.03
42.47
43.22
30.96
33.41
-8.15
-6.45
-8.01
-6.94
-9.56
-7.65
-6.68
-7.21
-5.95
-6.51
5.24
4b
–C6H5
–C6H5
4c
–2-OHC6H4
–2-furon
–4-OCH3C6H4
–2-OHC6H4
–2-Furon
4d
4e
–3,4, 5-tri-OCH3C6H2
–2,4-di-ClC6H3
–4-N(CH3)2–C6H4
–3-Indole
4f
–3,4,5-tri-OCH3C6H2
–2,4-di-ClC6H3
4-N(CH3)2–C6H4
–3-Indole
4g
5g
5h
5i
4h
4i
–CH3
4j
–4-OCH3C6H4
–C6H5
5j
–CH3
4k
5k
5l
–C6H5
4l
–4-ClC6H4
–4-ClC6H4
-6.02
-5.29
-5.65
-6.13
-6.78
-5.18
-6.95
-5.80
-5.65
4m
–2,4-di-ClC6H3
–4-N(CH3)2–C6H4
–2-OHC6H4
–2-Furon
5m
5n
5o
5p
5q
5r
5s
–2,4-di-ClC6H3
–4-N(CH3)2–C6H4
–2-OHC6H4
–2-Furon
4n
4o
4p
4q
–3-OCH3, 4-OH–C6H3
–CH3
–3-OCH3, 4-OH–C6H3
–CH3
4r
4s
–3,4,5-tri-OCH3C6H2
–4-OCH3C6H4
–
–3,4,5-tri-OCH3C6H2
–4-OCH3C6H4
4t
56.24
99.97
5t
Nevirapine
a
Data are indicated as percentage of inhibition at 20 lg/ml
123

Med Chem Res
Fig. 2 Docking poses of compounds at active binding site of RT enzyme. a Efavirenz, b compound 5e and c compound 4e. Hydrogen bond with
amino acid residues is shown in pink dotted lines. Hydrophobic interaction with amino acid residues is shown in green dotted lines
Whereas another side chain at position R1 (furan-2-yl and
3,4,5-trimethoxyphenyl for 5e and 4e, respectively)
showed hydrophobic interaction with Tyr 181, Pro95, and
Val 179 amino acid residues (Fig. 2). The methyl group is
substituted at R position on the imidazole-5-one ring also
showed some hydrophobic interactions with Tyr 181 and
Tyr 188. Thus, this may be reason that the replacement of
this methyl group by bulky phenyl ring in compounds 4k–
t and 5k–t showed the less activity as compared to com-
pounds 4a–j and 5a–j. This may be due to phenyl ring that
occupies the larger space and reduces the possibility of
hydrophobic interaction with Tyr 181 and Tyr 188. The
compound 5e and 4e showed strong hydrogen bond with
Lys 101, similar to reference compounds Efavirenz
(Fig. 2a). It was observed that –C=O group of imidazole
ring in all docked compound formed the hydrogen bond
with –NH Lys 101. Moreover, this hydrogen bond between
–C=O group of imidazole and –NH of Lys 101 was found
in hydrophobic space of enzyme which increases the
affinity of the compounds toward the enzyme. This indi-
cates the importance of –C=O group of central imidazole
ring for anti-HIV-1 RT activity (Fig. 3). Although there is
very little difference in HIV-1 RT inhibitory activity of
compounds bearing hydroxyl or chloro groups at X posi-
tion on pyrimidine ring, but docking study revealed that
both groups play a different important role for stabilization
of imidiazole-5-ones-RT complex. The –OH group of
pyrimidine ring formed hydrogen bond with –C=O groups
of Lys 101, whereas substitution of –Cl group at -X posi-
tion of pyrimidine ring supports the stabilization of com-
plex by forming hydrophobic interaction with surrounding
amino acid residues.
123

Med Chem Res
Fig. 3 Docking pose of
a compounds 5e and
b compound 4e at active
binding site of RT enzyme
showing the hydrogen bond in
hydrophobic space. Hydrogen
bond with amino acid is shown
in pink dotted lines. The gray
color balls indicate the
hydrophobic amino acid resides
Conclusion
in-vitro screening that the most of compounds exhibit RT
inhibitory activity. Among the compounds, 4c, 4d, 4e, 5a
and 5e showed more significant RT inhibitory activity. The
substitution pattern around imidazole ring showed the
requirement of small hydrophobic groups at R position and
bulky groups at R1 position on imidazole-5-one ring. The
We have designed and synthesized the new series of
4-substituted ethylidene/benzylidene-1-(4-hydroxy/chloro-6-
methylpyrimidin-2-yl)-2-methyl/phenyl-1H-imidazol-5(4H)-
ones as HIV-1 RT inhibitors. It has been observed from
123

Med Chem Res
(eds) Textbook of AIDS medicine, 2nd edn. Williams &
Wilkins, Baltimore
molecular docking studies showed the potential binding
mode of synthesized imidazole-5-one analogs in the allo-
steric binding site of HIV-1 RT. The imidazole-5-one ring
formed important hydrogen bond with Lys 101, and thus
crucial for HIV-1 RT inhibition. The 4-hydroxy/chloro-6-
methylpyrimidin-2-yl and bulky substitution at R1 position
of imidazole-5-one ring stabilize the ligand–enzyme by
forming the hydrophobic interactions with HIV-1 RT
enzyme. The overall SAR exploration helped us for the
new rational design, and thus further structure modifica-
tions on the R and R1 position of imidazole-5-one ring and
pyrimidine ring are underway.
FriesnerRA, MurphyRB,RepaskyMP,FryeLL,GreenwoodJR, Halgren
TA, Sanschagrin PC, Mainz DT (2006) Extra precision glide:
docking and scoring incorporating a model of hydrophobic enclo-
sure for protein–ligand complexes. J Med Chem 49:6177–6196
Furnis BS, Hannaford AJ, Smith PWG (2005) Vogel’s textbook of
practical organic chemistry, 5th edn. Pearson Publication,
London, p 1156
Mokale SN, Lokwani D, Shinde DB (2012) Synthesis, biological
activity and docking study of imidazol-5-one as novel non-
nucleoside HIV-1 reverse transcriptase inhibitors. Bioorg Med
Chem 20:3119–3127
Pauwels R (2004) New non-nucleoside reverse transcriptase inhibi-
tors (NNRTIs) in development for the treatment of HIV
infections. Curr Opin Pharmacol 4:437–446
Rao A, Balzarini J, Carbone A, Chimmirri A, De Clercq E, Monforte
`
Acknowledgments The authors are thankful to the Head, Depart-
ment of Chemical Technology, Dr. Babasaheb Ambedkar Marathw-
ada University, Aurangabad 431004 (MS), India for providing the
laboratory facility.
AM, Monforte P, Pannecouque C, Zappala M (2004a) 2-(2,6-
Dihalophenyl)-3-(pyrimidin-2-yl)-1,3-thiazolidin-4-ones as non-
nucleoside HIV-1 reverse transcriptase inhibitors. Antiviral Res
63:79–84
Rao A, Balzarini J, Carbone A, Chimmirri A, De Clercq E, Monforte
AM, Monforte A, Pannecouque C, Zappala M (2004b) Synthesis
of new 2,3-diaryl-1,3-thiazolidin-4-ones as anti-HIV agents.
Farmaco 59:33–39
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