Anti-HSV-1 activity and mechanism of action of some new synthesized substituted pyrimidine, thiopyrimidine and thiazolopyrimidine derivatives

Article abstract of DOI:10.1016/j.ejmech.2009.12.057

A series of heterocyclic derivatives 2-16 conjugated with tetrahydronaphthalene moiety were synthesized as antiviral agents by using 1-(5,6,7,8-tetrahydronaphthalen-2-yl)ethanone as starting material. The antiviral screening showed that many of these obtained compounds have good antiviral activities comparable to Acyclovir as reference control. Two compounds 13 and 15 gave over 90% inhibition and considered to be highly promising and on confirming their activity and comparing them to antiviral activity of Acyclovir. The detailed synthesis, spectroscopic data, and antiviral screening for synthesized compounds were reported.

Full text of DOI:10.1016/j.ejmech.2009.12.057

European Journal of Medicinal Chemistry 45 (2010) 1494–1501
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Anti-HSV-1 activity and mechanism of action of some new synthesized
substituted pyrimidine, thiopyrimidine and thiazolopyrimidine derivatives
,
c
Salwa F. Mohamed a, Eman M. Flefel b, Abd El-Galil E. Amr a , Dina N. Abd El-Shafy
*
a Applied Organic Chemistry Dept., National Research Center, Dokki, Cairo, Egypt
b Photochemistry Dept., National Research Center, Dokki, Cairo, Egypt
c Water Pollution Dept., National Research Center, Dokki, Cairo, Egypt
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of heterocyclic derivatives 2–16 conjugated with tetrahydronaphthalene moiety were synthe-
sized as antiviral agents by using 1-(5,6,7,8-tetrahydronaphthalen-2-yl)ethanone as starting material.
The antiviral screening showed that many of these obtained compounds have good antiviral activities
comparable to Acyclovir as reference control. Two compounds 13 and 15 gave over 90% inhibition and
considered to be highly promising and on confirming their activity and comparing them to antiviral
activity of Acyclovir. The detailed synthesis, spectroscopic data, and antiviral screening for synthesized
compounds were reported.
Received 3 February 2009
Received in revised form
12 December 2009
Accepted 23 December 2009
Available online 13 January 2010
Keywords:
Ó 2010 Elsevier Masson SAS. All rights reserved.
Oxarino derivatives
Pyrimidine derivatives
Thiazolo- and thiazinopyrimidine
Antiviral agents
1. Introduction
pyrimidine and thiazolopyrimidine derivatives and tested their
anti-HSV-1 activities.
HSV disease is distributed worldwide, it ranges from mild illness
in majority of patients to a few cases of sporadic, severe and life
threatening disease [1]. Acyclovir is used for its treatment but its
widespread and frequent use lead to appearance of resistant cases
[2], resistance also occurred to 5–10% of immunocompromised
patients [3]. From here it comes clear that it is important to test
new agents that can be used as antiviral compounds and also can
overcome resistant strains [4]. In previous work we have found that
certain substituted pyrimidine and their heterocyclic derivatives
show antimicrobial and anti-inflammatory [5–8] and antitumor
activities [9–11]. On the other hand, thioxopyrimidine and thiazo-
lopyrimidine derivatives have promising biological and anticancer
activities [12–14]. In addition, we have reported that certain of our
newly substituted heterocyclic compounds exhibited anti-
androgenic [15], anti-inflammatory [16], anticancer [17], anticon-
vulsant [18] and antiarrhythmic [19] activities. Recently, some new
thienopyrimidinone derivatives have been synthesized and tested
as analgesic, antiparkinsonian and anti-inflammatory activities
[20,21]. In view of these observations and in continuation of our
previous work in heterocyclic chemistry, we synthesized some new
2. Results and discussion
2.1. Chemistry
In the present work we report the synthesis and a preliminary
pharmacological activity screening of several pyrimidine deriva-
tives based on 3-(substituted phenyl)-1-(5,6,7,8-tetrahydro-
naphthalen-2-yl)prop-2-en-1-one derivatives 2a–c, which were
prepared from 1-(5,6,7,8-tetrahydronaphthalen-2-yl)ethanone 1
as starting material according to Ref. [22].
a,b-Unsaturated ketones
2a–c required for the synthesis of the corresponding oxirano
derivatives (3a–c) were obtained by treatment with hydrogen
peroxide (30%) in the presence of sodium hydroxide. The reaction
of
3 with phenyl hydrazine in refluxing ethanol produced
N-phenyl-pyrazol-4-ol derivative 4, which was refluxed in glacial
acetic acid to yield the corresponding N-phenyl pyrazolo deriva-
tive 5. However, the latter was also prepared directly from 3 by
refluxing with phenyl hydrazine in glacial acetic acid. Condensa-
tion of 3a–c with thiourea in refluxing ethanolic potassium
hydroxide afforded 2-thioxopyrimidinones 6a–c. Compound 6b
was condensed with chloroacetic acid in a mixture of acetic acid/
acetic anhydride in the presence of anhydrous sodium acetate to
yield the corresponding thiazolopyrimidines 7. Compound 7
* Corresponding author. Fax: þ20 2 33370 931.
E-mail address: aamr1963@yahoo.com (A.E-G.E. Amr).
0223-5234/$ – see front matter Ó 2010 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2009.12.057

S.F. Mohamed et al. / European Journal of Medicinal Chemistry 45 (2010) 1494–1501
1495
contains an active methylene group and it condensed with
p-chlorobenzaldehyde in the presence of anhydrous sodium
acetate and glacial acetic acid/acetic anhydride mixture to yield
the arylmethylene 8. However, the latter was also prepared
directly from 6b by the action of chloroacetic acid, p-chlor-
obenzaldehyde, and anhydrous sodium acetate in the presence of
acetic acid/acetic anhydride mixture (Scheme 1).
The oxirano derivative 3c was fused in an oil bath at 180 ꢀC and
the obtained residue was triturated with water, then methanol to
give bis(bromophenyl)dioxane derivative 9, while compound 3b was
condensed with urea or 3a with guanidine hydrochloride in reflux-
ing ethanolic potassium hydroxide to afford the corresponding
pyrimidinone derivatives 10 and 11, respectively (Scheme 2).
Compound 6b was reacted with ethyl chloroformate in refluxing
alcoholic potassium hydroxide to afford ethyl carbonothioate 12.
Compound 6b was alkylated with 3-chloroacetylacetone in the
presence of potassium hydroxide to give dimethoxyphenylpyr-
imidin-5(4H)-one derivative 13, which was cyclized to 2-acetylth-
iazolopyrimidine 14 by refluxing with acetic anhydride. Compound
14 was prepared directly from 6b by the action of 3-chloroacetyl-
acetone in refluxing pyridine in the presence of potassium
hydroxide. Compound 6b was condensed with 2-bromopropionic
acid or 3-bromopropionic acid in a mixture of acetic acid/acetic
anhydride in the presence of anhydrous sodium acetate to yield the
corresponding methylthiazolo- and thiazinopyrimidines 15 and 16,
respectively (Scheme 3).
Ar
Ar
N
N
N
N
HO
AcOH
O
4
5
Ar
1
CH3
CH3
PhNHNH2
CH3
CHO
AcOH
3a
3a
PhNHNH2
EtOH/TEA
EtOH/
NaOH
R
O
O
R
R
Ar
H2O2
Ar
O
NaOH
2a-c
a, R = 4-CH3
3a-c
b, R = 3,4-(OCH3)2
c, R = 4-Br
EtOH/
KOH
H2NCSNH2
H
Ar
O
N
S
Ar
N
S
N
6b
O
ClCH2COOH
N
AcOH/Ac2O
CH3ONa
O
H
OCH
3 Ar
N
S
R
Ar`
OCH3
7
N
6a-c
6b
O
Method A
Ar`CHO
O
Method B
ClCH2COOH
AcOH/Ac2O
AcOH/Ac2O
CH3ONa
Ar`CHO
OCH3
OCH3
8
Ar =
Cl
Ar` =
Scheme 1.

1496
S.F. Mohamed et al. / European Journal of Medicinal Chemistry 45 (2010) 1494–1501
H
N
at the expense of cellular molecules. The inhibition in replication
showed by our molecule might be due to inhibition of one or more
of important enzymes needed by the virus to complete its repli-
cating cycle. There is often sufficient specificity in virus poly-
merases to provide a target for a specific antiviral agent, and this
method has produced the majority of the specific antiviral drugs
currently in use.
Ar
O
H
O
C
N
O
H2N
NH2
EtOH/KOH
Nucleoside analogues are in fact pro-drugs, since they need to
be phosphorylated before becoming effective.
Br
3b
OCH3
3. Conclusion
OCH3
10
O
A series of heterocyclic derivatives conjugated with tetrahy-
dronaphthalene moiety were synthesized as antiviral agents by
using 1-(5,6,7,8-tetrahydronaphthalen-2-yl)ethanone as starting
material. The antiviral screening showed that many of these
obtained compounds have good antiviral activities comparable to
Acyclovir as reference control. Two compounds 13 and 15 gave over
90% inhibition and considered to be highly promising and on
confirming their activity and comparing them to antiviral activity of
Acyclovir.
Ar
O
2 mole of 3c
3a-c
O
Ar
Fusion/180°C
O
H
N
3a
Ar
NH
H
NH
C
Br
9
N
H2N
NH2
O
4. Experimental
EtOH/KOH
4.1. Chemistry
Ar =
Melting points were determined on open glass capillaries using
a
Electrothermal IA 9000 digital melting point apparatus.
CH3
11
Elemental analyses were performed on Elementar, Vario EL,
Microanalytical Unit, National Research Center, Cairo Egypt and
were found within ꢁ0.4% of the theoretical values. Infrared spectra
were recorded on Carl Zeiss Spectrophotometer model UR 10 using
the KBr disc technique. 1H NMR spectra were recorded on Varian
Gemini 270 MHz spectrometer (DMSO-d6) and the chemical shifts
Scheme 2.
The formation of the linear cyclized products 14–16 are tenta-
are given in d (ppm) downfield from tetramethylsilane (TMS) as an
tively favored over the isomeric structures, due to the chemical
shift (d) of the pyrimidine proton of compounds 14–16, which are
deshielded by about 0.6 ppm [23], relative to the thiopyrimidinone
derivative 6b.
internal standard. The mass spectra were measured using a Fin-
nigan SSQ 7000 mass spectrometer. Follow up of the reactions and
checking the purity of the compounds was made by TLC on silica
gel-precoated aluminum sheets (Type 60 F254, Merck, Darmstadt,
Germany).
2.2. Anti-HSV-1 activity
4.1.1. Synthesis of 3-(substituted phenyl)-1-(5,6,7,8-
2.2.1. Antiviral activity of acyclovir as our control
tetrahydronaphthalen-2-yl)prop-2-en-1-ones 2a–c
The Fig. 1 shows antiviral activity of Acyclovir at different
A mixture of 1 (1.74 g, 10 mmol) and aromatic aldehydes,
namely, 4-methylbenzaldehyde, 3,4-dimethoxybenzaldehyde and
4-bromobenzaldehyde (10 mmol) in alcoholic sodium hydroxide
(50 mL, 10%) was stirred for 12 h at room temperature. The reaction
mixture was poured onto ice-water, the solid formed was collected
by filtration, dried and crystallized to give 2a [22], 2b and 2c,
respectively.
concentrations from 10 to 100
mg/ml showing that our two
compounds 13 and 15 have higher activity.
2.2.2. Antiviral activity
Plaque reduction assay was used to test antiviral activity of 17
chemical compounds under test, a concentration of 2 and 5
were used in initial screening (Table 1).
mg/mL
Two compounds 13 and 15 gave over 90% inhibition and
considered to be highly promising and on confirming their activity
and comparing them to antiviral activity of Acyclovir (Fig. 1), results
confirmed the activity of those two compounds and that they gave
high % inhibition at low concentration.
On studying the mechanism of action of those two compounds
both showed virucidal activity against HSV-1. The chemical
configuration of these compounds contains heterocyclic moities
which may alter virus epitopes that inhibit virus attachment. That
decrease in activity in compound 13 might be due to beta-diketone
moiety (Table 2).
4.1.1.1. 3-(3,4-Dimethoxyphenyl)-1-(5,6,7,8-tetrahydronaphthalen-
2-yl)prop-2-en-1-one (2b). Yield 95%, mp. 85 ꢀC (EtOH); IR (KBr,
cmꢂ1): 3145 (Ar-CH), 2932 (aliph-CH), 1670 (C]O); 1H NMR
(DMSO-d6):
d 1.68–1.70 (m, 4H, 2 CH2-tetraline), 2.80–2.82 (m, 4H,
2 CH2-tetraline), 3.75, 3.80 (2s, 6H, 2OCH3), 6.90–7.90 (m, 8H, Ar-
H þ CH]CH); Mass: m/z (%): 322 (Mþ, base peak, 100). Analysis
calculated for C21H22O3 (322.40): C, 78.23; H, 6.88; O, 14.89. Found:
C, 78.18; H, 6.82.
4.1.1.2. 3-(4-Bromophenyl)-1-(5,6,7,8-tetrahydronaphthalen-2-
yl)prop-2-en-1-one (2c). Yield 98%, mp. 115 ꢀC (EtOH); IR (KBr,
cmꢂ1): 3138 (Ar-CH), 2918 (aliph-CH), 1674 (C]O); 1H NMR
Compound 15 also was found to inhibit viral replication this can
be discussed as follows (Table 3). Many viruses have evolved their
own specific enzymatic mechanisms to replicate virus nucleic acids
(DMSO-d6):
d 1.66–1.68 (m, 4H, 2 CH2-tetraline), 2.78–2.80 (m, 4H,
2 CH2-tetraline), 6.96–7.95 (m, 9H, Ar-H þ CH]CH); MS (EI, 70 eV):

S.F. Mohamed et al. / European Journal of Medicinal Chemistry 45 (2010) 1494–1501
1497
Ar
N
S
COCH3
Ar
N
S
COCH3
CH3
NH
COCH3
N
O
O
Ac2O
Pyridine
OCH3
OCH3
OCH3
13
OCH3
14
COCH3
COCH3
Cl C COCH3
H
Cl C COCH3
H
EtOH/KOH
Pyridine/KOH
Ar
N
S
H
COOC2H5
N
O
Cl
COOC2H5
6b
EtOH/KOH
OCH3
OCH3
12
Br
Br
H3C C COOH
H
H2C CH2COOH
AcOH/Ac2O
AcONa
AcOH/Ac2O
AcONa
Ar
N
S
CH3
Ar
O
N
S
N
N
O
O
O
OCH3
OCH3
OCH3
15
OCH3
16
Ar =
Scheme 3.
m/z ¼ 341 (Mþ, 32), 210 (base peak, 100). Analysis calculated for
onto ice-water. The solid formed was collected by filtration, dried
and crystallized to give 3a, 3b and 3c, respectively.
C19H17BrO (341.24): C, 66.87; H, 5.02. Found: C, 66.81; H, 5.00.
4.1.2. Synthesis of (3-(substituted phenyl)oxiren-2-yl)(5,6,7,8-
tetrahydronaphthalen-2-yl)methanones 3a–c
4.1.2.1. (3-(4-Methylphenyl)oxiren-2-yl)(5,6,7,8-tetrahydronaph-
thalen-2-yl)methanone (3a). Yield 93%, mp. 67 ꢀC (EtOH); IR (KBr,
To a solution of 2a–c (10 mmol) in a mixture of acetone/meth-
anol (50 mL, 3:2 ratio) and sodium hydroxide (2 g) in few drops of
water, hydrogen peroxide (6 mL, 30%) was added drop wise with
stirring for 15 min at 0 ꢀC. The reaction mixture was stirred for 3 h
at room temperature, then left overnight at ꢂ5 ꢀC, then poured
cmꢂ1): 1688 (C]O); 1H NMR (DMSO-d6):
d 1.65–1.68 (m, 4H, 2 CH2-
tetraline), 2.18 (s, 3H, CH3), 2.79–2.80 (m, 4H, 2 CH2-tetraline), 4.05,
4.82 (2s, 2H, 2CH-epoxy), 6.85–7.85 (m, 7H, Ar-H); MS (EI, 70 eV):
m/z ¼ 292 (Mþ, 46), 159 (base peak, 100). Analysis calculated for
C20H20O2 (292.37): C, 82.16; H, 6.89. Found: C, 82.12; H, 6.84.

1498
S.F. Mohamed et al. / European Journal of Medicinal Chemistry 45 (2010) 1494–1501
Table 2
100
90
80
70
60
50
40
30
20
10
0
Mechanism of action of compound 13.
Activity
Concentration
g/ml
Viral count
(control)
Viral count
(Extract)
% inhibition
28
m
Virucidal
30
40
0.84 ꢃ 107
0.4 ꢃ 107
0.1 ꢃ 107
0.6 ꢃ 107
CPE
Adsorbtion
Replication
30
40
0.4 ꢃ 107
0
0
0.4 ꢃ 107
30
40
0.1 ꢃ 107
0.1 ꢃ 107
0
0
10
20
30
40
50
60
70
80
90 100
Concentration µg/ml
Analysis calculated for C21H22O4 (338.4): C, 74.54; H, 6.55. Found: C,
74.50; H, 6.51.
Acyclovir
Compound 13
compound15
4.1.2.3. (3-(4-Bromophenyl)oxiran-2-yl)(5,6,7,8-tetrahydronaph-
thalen-2-yl)methanone (3c). Yield 96%, mp. 65 ꢀC (EtOH); IR (KBr,
Fig. 1. Comparison between Acyclovir and active compounds.
cmꢂ1): 1685 (C]O); 1H NMR (DMSO-d6):
d 1.69–1.72 (m, 4H, 2 CH2-
tetraline), 2.79–2.80 (m, 4H, 2 CH2-tetraline), 4.08, 4.80 (2s, 2H,
2CH-epoxy), 6.80–7.80 (m, 7H, Ar-H); MS (EI, 70 eV): m/z ¼ 357
(Mþ, 36), 159 (base peak, 100). Analysis calculated for C19H17BrO2
(357.24): C, 63.88; H, 4.80. Found: C, 63.82; H, 4.876.
4.1.2.2. (3-(3,4-Dimethoxyphenyl)oxiren-2-yl)(5,6,7,8-tetrahy-
dronaphthalen-2-yl)methanone (3b). Yield 92%, mp. 122 ꢀC (EtOH),
IR (KBr, cmꢂ1): 1690 (C]O); 1H NMR (DMSO-d6):
d 1.66–1.70 (m,
4H, 2 CH2-tetraline), 2.78–2.82 (m, 4H, 2 CH2-tetraline), 3.81, 3.85
(2s, 6H, 2OCH3), 4.10, 4.80 (2s, 2H, 2CH-epoxy), 6.90–7.80 (m, 6H,
Ar-H); MS (EI, 70 eV): m/z ¼ 338 (Mþ, 77), 159 (base peak, 100).
4.1.3. Synthesis of 1-phenyl-3-(5,6,7,8-tetrahydronaphthalen-2-yl)-
5-p-tolyl-4,5-dihydro-1H-pyrazol-4-ol (4)
A mixture of 3a (2.9 g,10 mmol) and phenyl hydrazine (10 mL) in
absolute ethanol (30 mL) in the presence of triethylamine (0.5 mL)
was refluxed for 3 h. The solvent was concentrated under reduced
pressure, poured onto cold water, acidified with dilute hydrochloric
acid, the formed precipitate was filtered off, dried and crystallized to
give 4. Yield 74%, mp. 76 ꢀC (EtOH/pet. ether); IR (KBr, cmꢂ1): 3440
Table 1
Anti-HSV-1 activity of selected newly synthesized compounds.
Code
Concentration
Viral count
(control)
Viral count
(Extract)
% inhibition
m
g/ml
3a
2
5
0.84 ꢃ 107
0.66 ꢃ 107
0.66 ꢃ 107
0.84 ꢃ 107
0.66 ꢃ 107
0.84 ꢃ 107
0.66 ꢃ 107
0.66 ꢃ 107
0.84 ꢃ 107
0.66 ꢃ 107
0.66 ꢃ 107
0.84 ꢃ 107
0.84 ꢃ 107
0.84 ꢃ 107
0.84 ꢃ 107
0.84 ꢃ 107
0.66 ꢃ 107
0.84 ꢃ 107
0
0
0.84 ꢃ 107
(OH), 1600 (C]N); 1H NMR (DMSO-d6):
d 1.70–1.72 (m, 4H, 2 CH2-
3b
3c
4
2
5
0.50 ꢃ 107
0.28 ꢃ 107
24
57
tetraline), 2.30 (s, 3H, CH3), 2.77–2.80 (m, 4H, 2 CH2-tetraline), 6.30
(d,1H, CH-pyrazole), 6.70 (t,1H, CH-pyrazole), 7.00–7.70 (m, 8H, Ar-
H þ OH); MS (EI, 70 eV): m/z ¼ 382 (Mþ, base peak, 100). Analysis
calculated for C26H26N2O (382.50): C, 81.64; H, 6.85; N, 7.32. Found:
C, 81.60; H, 6.80; N, 7.28.
2
5
0.46 ꢃ 107
30
18
0.54 ꢃ 107
2
5
0.20 ꢃ107
0.20 ꢃ 107
76
76
5
2
5
0.64 ꢃ 107
3
26
4.1.4. Synthesis of 1-phenyl-3-(5,6,7,8-tetrahydronaphthalen-2-yl)-
5-p-tolyl-1H-pyrazole (5)
0.54 ꢃ 107
4.1.4.1. Method A. A mixture of 3a (2.9 g, 10 mmol) and phenyl
hydrazine (10 mL) in glacial acetic acid (30 mL) was refluxed for 3 h.
The reaction mixture was poured onto ice-water, the formed
precipitate was filtered off, dried and crystallized to give 5. Yield 92%,
mp.102 ꢀC (MeOH); IR (KBr, cmꢂ1): 1600 (C]N); 1H NMR (DMSO-d6):
6a
6b
7
2
5
0.84 ꢃ 107
0.28 ꢃ 107
0
66
2
5
0.48 ꢃ 107
27
54
0.30 ꢃ 107
2
5
0.66 ꢃ 107
0.66 ꢃ 107
0
0
d
1.65–1.69 (m, 4H, 2 CH2-tetraline), 2.28 (s, 3H, CH3), 2.76–2.82 (m,
4H, 2CH2-tetraline), 7.00 (s,1H, CH-pyrazole), 7.10–7.70(m, 7H, Ar-H);
MS (EI, 70 eV): m/z ¼ 364 (Mþ, base peak,100). Analysis calculated for
C26H24N2 (364.48): C, 85.68; H, 6.64; N, 7.69. Found: C, 85.62; H, 6.60;
N, 7.63.
8
2
5
0.84 ꢃ 107
0
0
0.84 ꢃ 107
9
2
5
0.66 ꢃ 107
0.66 ꢃ 107
0
0
10
11
12
13
14
15
16
2
5
0.44 ꢃ 107
33
21
4.1.4.2. Method B. A solution of 4 (3.8 g, 10 mmol) in glacial acetic
acid (20 mL) was refluxed for 2 h. The reaction mixture was
concentrated under reduced pressure, then poured onto ice-water,
0.52 ꢃ 107
2
5
0.80 ꢃ 107
0.84 ꢃ 107
4
0
2
5
0.32 ꢃ 107
61
19
Table 3
0.68 ꢃ 107
Mechanism of action of compound 15.
2
5
0.08 ꢃ 107
0.04 ꢃ 107
90
95
Activity
Concentration
g/ml
Viral count
(control)
Viral count
(Extract)
% inhibition
m
0.84 ꢃ 107
0.4 ꢃ 107
0.1 ꢃ 107
0.06 ꢃ 107
92
95
2
5
0.84 ꢃ 107
0
14
Virucidal
20
30
0.72 ꢃ 107
0.04 ꢃ 107
0.4 ꢃ 107
0
0
2
5
0.08 ꢃ 107
90
100
Adsorbtion
Replication
20
30
0.4 x107
0
0.04 ꢃ 107
0.02 ꢃ 107
60
80
2
5
0.64 ꢃ 107
0.46 ꢃ 107
3
30
20
30

S.F. Mohamed et al. / European Journal of Medicinal Chemistry 45 (2010) 1494–1501
1499
the formed precipitate was filtered off, dried and crystallized to give
5 in 88% yield. The crystallized product was identified by m. p., mixed
m. p. and TLC in comparison with authentic sample from Method A.
anhydride (40 mL, 3:1) was refluxed for 3 h, allowed to cool, then
poured onto water. The solid formed was collected by filtration and
crystallized to give 8. Yield 82%, mp. 195 ꢀC (EtOH); IR (KBr, cmꢂ1):
1730 (C]O),1710 (C]O); 1H NMR (DMSO-d6):
d 1.70–1.72 (m, 4H, 2
4.1.5. Synthesis of 4-(4-substituted phenyl)-6-(5,6,7,8-
tetrahydronaphthalen-2-yl)-2-thioxo-tetrahydropyrimidin-5(6H)-
ones 6a–c
A mixture of 3a–c (10 mmol) and thiourea (0.8 g, 10 mmol) in
ethanolic potassium hydroxide (30 mL, 4%) was refluxed for 2 h. The
reaction mixture was concentrated under reduced pressure, the
residue was triturated with diluted hydrochloric acid. The solid
formed was collected by filtration, and crystallized to give 6a, 6b and
6c, respectively.
CH2-tetraline), 2.74–2.78 (m, 4H, 2 CH2-tetraline), 3.70, 3.75 (2s, 6H,
OCH3), 3.72, 3.90 (2d, 2H, 2 CH-pyrimidinone), 6.85–7.40 (m, 11H,
Ar-H þ CH-arylidine); MS (EI, 70 eV): m/z ¼ 559 (Mþ, 0.3), 151 (base
peak, 100). Analysis calculated for C31H27ClN2O4S (559.08): C,
66.60; H, 4.87; Cl, 6.34; N, 5.01; S, 5.74. Found: C, 66.55; H, 4.82; Cl,
6.28; N, 4.95; S, 5.68.
4.1.7.2. Method B. To a mixture of 6b (4.4 g, 10 mmol), chloroacetic
acid (1.0 g, 10 mmol) and anhydrous sodium acetate (1.60 g,
20 mmol) in glacial acetic acid/acetic anhydride (40 mL, 3:1, ratio),
4-chlorobenzaldehyde (10 mmol) was added. The reaction mixture
was heated under reflux for 2 h, then cooled and poured into water.
The solid formed was collected by filtration and crystallized to yield
8 in 84% yield. The crystallized product was identified by m. p., mixed
m. p. and TLC in comparison with authentic sample from Method A.
4.1.5.1. 4-(4-Methylphenyl)-6-(5,6,7,8-tetrahydronaphthalen-2-yl)-
2-thioxo-tetrahydropyrimidin-5(6H)-one (6a). Yield 95%, mp.
220 ꢀC (dioxane); IR (KBr, cmꢂ1): 3300, 3200 (2NH), 1710 (C]O),
1252 (C]S); 1H NMR (DMSO-d6):
d 1.70–1.72 (m, 4H, 2 CH2-tetra-
line), 2.30 (s, 3H, CH3), 2.78–2.80 (m, 4H, 2 CH2-tetraline), 3.00, 3.40
(2d, 2H, 2 CH-pyrimidinone) [23], 6.89–7.40 (m, 7H, Ar-H), 10.65,
11.40 (2s, 2H, 2 NH exchangeable with D2O); MS (EI, 70 eV): m/
z ¼ 350 (Mþ, 70), 245 (base peak, 100). Analysis calculated for
C21H22N2OS (350.48): C, 71.97; H, 6.33; N, 7.99; S, 9.15. Found: C,
71.92; H, 6.28; N, 7.95; S, 9.10.
4.1.8. (3,6-Bis(4-bromophenyl)-1,4-dioxane-2,5-diyl)bis((5,6,7,8-
tetrahydronaphthalen-2-yl)methanone) (9)
Compound 3c (3.6 g, 1 mmol) was fused in an oil bath at 180 ꢀC
for 4 h. The obtained residue was triturated with water, the formed
precipitate was filtered off, washed with water, dried and crystal-
lized to give 9. Yield 82%, mp. 135 ꢀC (MeOH); IR (KBr, cmꢂ1): 1685
4.1.5.2. 4-(3,4-Dimethoxyphenyl)-6-(5,6,7,8-tetrahydronaphthalen-
2-yl)-2-thioxo-tetrahydro-pyrimidin-5(6H)-one (6b). Yield 97%, mp.
231 ꢀC (dioxane); IR (KBr, cmꢂ1): 3350, 3220 (2NH), 1715 (C]O), 1245
(2C]O); 1H NMR (DMSO-d6):
d 1.65–1.69 (m, 4H, 2 CH2-tetraline),
2.78–2.80 (m, 4H, 2 CH2-tetraline), 5.35–5.55 (m, 4H, 4CH-
dioxane), 6.90–7.80 (m, 14H, Ar-H); MS (EI, 70 eV): m/z ¼ 714 (Mþ,
10), 159 (base peak, 100). Analysis calculated for C38H34Br2O4
(714.48): C, 63.88; H, 4.80. Found: C, 63.80; H, 4.75.
(C]S); 1H NMR (DMSO-d6):
d 1.68–1.70 (m, 4H, 2 CH2-tetraline), 2.78–
2.80 (m, 4H, 2 CH2-tetraline), 3.10, 3.40 (2d, 2H, 2 CH-pyrimidinone),
3.70, 3.80 (2s, 6H, 2OCH3), 6.95–7.50 (m, 6H, Ar-H),10.70,11.60 (2s, 2H,
2 NH exchangeable with D2O); MS (EI, 70 eV): m/z ¼ 396 (Mþ, 62), 292
(base peak, 100). Analysis calculated for C22H24N2O3S (396.50): C,
66.64; H, 6.10; N, 7.07; S, 8.09. Found: C, 66.58; H, 6.02; N, 7.00; S, 8.00.
4.1.9. Synthesis of Tetrahydropyrimidinone 10 and 11
A mixture of 3b (10 mmol) and urea (10 mmol) or 3a (10 mmol)
and guanidine (10 mmol) in ethanolic potassium hydroxide (50 mL,
4%) was refluxed for 2 h. The solvent was concentrated under
reduced pressure, the reaction mixture was poured onto acidified
water. The solid formed was collected by filtration, dried and
crystallized to give 10 and 11, respectively.
4.1.5.3. 4-(4-Bromophenyl)-6-(5,6,7,8-tetrahydronaphthalen-2-yl)-
2-thioxo-tetrahydropyrimidin-5(6H)-one (6c). Yield 92%, mp. 242 ꢀC
(MeOH); IR (KBr, cmꢂ1): 3360, 3225 (2NH),1718 (C]O), 1250 (C]S);
1H NMR (DMSO-d6):
d 1.70–1.72 (m, 4H, 2 CH2-tetraline), 2.80–2.84
(m, 4H, 2 CH2-tetraline), 3.08, 3.42 (2d, 2H, 2 CH-pyrimidinone),
6.95–7.48 (m, 7H, Ar-H),10.60,11.38 (2s, 2H, 2 NH exchangeable with
D2O); MS (EI, 70 eV): m/z ¼ 415 (Mþ, 35), 231 (base peak, 100).
Analysis calculated for C20H19BrN2OS (415.35): C, 57.83; H, 4.61; N,
6.74; S, 7.72. Found: C, 57.76; H, 4.54; N, 6.70; S, 7.68.
4.1.9.1. 4-(3,4-Dimethoxyphenyl)-6-(5,6,7,8-tetrahydronaphthalen-
2-yl)-tetrahydropyrimidine-2,5-dione (10). Yield 78%, mp. 230 ꢀC
(EtOH); IR (KBr, cmꢂ1): 3250, 3400 (2NH), 1720, 1700 (2C]O); 1H
NMR (DMSO-d6):
d 1.66–1.70 (m, 4H, 2 CH2-tetraline), 2.76–2.79
(m, 4H, 2 CH2-tetraline), 3.78, 3.85 (2d, 6H, 2OCH3), 5.50, 5.70 (2s,
2H, 2 CH-pyrimidinone), 6.70–7.30 (m, 6H, Ar-H), 10.60, 11.40 (2s,
2H, 2 NH exchangeable with D2O); MS (EI, 70 eV): m/z ¼ 380 (Mþ,
56), 158 (base peak, 100). Analysis calculated for C22H24N2O4
(380.44): C, 69.46; H, 6.36; N, 7.36. Found: C, 69.40; H, 6.30; N, 7.30.
4.1.6. Synthesis of 5-(3,4-dimethoxyphenyl)-7-(5,6,7,8-
tetrahydronaphthalen-2-yl)-2H-thiazolo[3,2-a]pyrimidine-
3,6(5H,7H)-dione (7)
Amixtureof6b(4.0g,10mmol),chlororaceticacid(1.0g,10mmol)
and anhydrous sodium acetate (1.6 g, 20 mmol) in glacial acetic acid
(30 mL) and acetic anhydride (10 mL) was refluxed for 3 h. The
reaction mixture was poured into water, the formed solid was filtered
off and crystallized to give 7. Yield 66%, mp. 153 ꢀC (EtOH); IR (KBr,
4.1.9.2. 4-(3,4-Dimethoxyphenyl)-2-imino-6-(5,6,7,8-tetrahy-
dronaphthalen-2-yl)-tetrahydro-pyrimidin-5(6H)-one (11). Yield
72%, mp. > 300 ꢀC (dioxane); IR (KBr, cmꢂ1): 3180, 3320, 3348 (3NH),
cmꢂ1): 1710 (C]O),1700 (C]O); 1H NMR (DMSO-d6):
d
1.65–1.68 (m,
1710 (C]O), (C]N); 1H NMR (DMSO-d6):
d 1.70–1.72 (m, 4H, 2 CH2-
4H, 2 CH2-tetraline), 2.75–2.80 (m, 4H, 2 CH2-tetraline), 3.60 (s, 2H,
CH2), 3.70, 3.85 (2d, 2H, 2 CH-pyrimidinone), 3.80, 3.88 (2s, 6H,
2OCH3), 6.90–7.40 (m, 6H, Ar-H); MS (EI, 70 eV): m/z ¼ 436 (Mþ, 10),
288 (base peak,100). Analysis calculated for C24H24N2O4S (436.52): C,
66.03; H, 5.54; N, 6.42; S, 7.35. Found: C, 65.95; H, 5.50; N, 6.36; S, 7.30.
tetraline), 2.30 (s, 3H, CH3),2.80–2.82 (m, 4H, 2 CH2-tetraline), 3.11,
3.30 (2s, 2H, 2 CH-pyrimidinone), 7.00–7.30 (m, 7H, Ar-H), 7.50, 7.70,
8.80 (3s, 3H, 3 NH exchangeable with D2O); MS (EI, 70 eV): m/z ¼ 379
(Mþ, base peak, 100). Analysis calculated for C22H25N3O3 (379.45): C,
69.64; H, 6.64; N, 11.07. Found: C, 69.58; H, 6.60; N, 11.00.
4.1.7. 2-(4-Chlorobenzylidene)-5-(3,4-dimethoxyphenyl)-7-
(5,6,7,8-tetrahydronaphthalen-2-yl)-2H-thiazolo[3,2-a]pyrimidine-
3,6(5H,7H)-dione (8)
4.1.10. Synthesis of S-6-(3,4-dimethoxyphenyl)-5-oxo-4-(5,6,7,8-
tetrahydronaphthalen-2-yl)-1,4,5,6-tetrahydro-pyrimidin-2-yl O-
ethyl carbonothioate (12)
4.1.7.1. Method A. A mixture of 7 (4.4 g, 10 mmol) and 4-chlor-
obenzaldehyde (1.4 g, 10 mmol) in glacial acetic acid/acetic
A mixture of 6b (4.0 g, 10 mmol) and ethyl chloroformate (1.3 g,
10 mmol) in alcoholic potassium hydroxide (30 mL, 2%) was

1500
S.F. Mohamed et al. / European Journal of Medicinal Chemistry 45 (2010) 1494–1501
refluxed for 2 h. The reaction mixture was poured onto acidified
ice-water, the solid formed was filtered off, dried and crystallized to
give 12. Yield 88%, mp. 202 ꢀC (EtOH), IR (KBr, cmꢂ1): 3300 (NH),
1740 (C]O, ester), 1720 (C]O, thiopyrimidone); 1H NMR (DMSO-
1.70 (m, 4H, 2 CH2-tetraline), 2.78–2.82 (m, 4H, 2 CH2-tetraline),
3.60, 3.85 (2d, 2H, 2 CH-pyrimidinone), 3.70, 3.75 (2s, 6H, 2OCH3),
3.90 (q, 1H, CH), 6.60–7.30 (m, 6H, Ar-H); MS (EI, 70 eV): m/z ¼ 450
(Mþ, 12), 269 (base peak, 100). Analysis calculated for C25H26N2O4S
(450.55): C, 66.64; H, 5.82; N, 6.22; S, 7.12. Found: C, 66.59; H, 5.75;
N, 6.12; S, 7.05.
d6): d 1.35 (t, 3H, CH3), 1.66–1.70 (m, 4H, 2 CH2-tetraline), 2.78–2.82
(m, 4H, 2 CH2-tetraline), 3.00, 3.40 (2d, 2H, 2 CH-pyrimidinone),
3.60, 3.65 (2s, 6H, 2OCH3), 4.15 (q, 2H, CH2), 6.85–7.40 (m, 6H, Ar-
H), 8.95 (s, 1H, NH exchangeable with D2O); MS (EI, 70 eV): m/
z ¼ 468 (Mþ, 2), 396 (base peak, 100). Analysis calculated for
C25H28N2O5S (468.57): C, 64.08; H, 6.02; N, 5.98; S, 6.84. Found: C,
65.96; H, 5.95; N, 5.92; S, 6.80.
4.1.13.2. 6-(3,4-Dimethoxyphenyl)-8-(5,6,7,8-tetrahydronaphthalen-
2-yl)-2,3-dihydropyrimido[2,1-b][1,3]thiazine-4,7(6H,8H)-dione
(16). Yield 62%, mp. 182 ꢀC (MeOH); IR (KBr, cmꢂ1): 1725 (C]O),
1710 (C]O); 1H NMR (DMSO-d6):
d 1.68–1.70 (m, 4H, 2 CH2-tet-
raline), 2.60–2.75 (m, 4H, 2CH2-thiazine), 2.78–2.79 (m, 4H, 2 CH2-
tetraline), 3.60, 3.90 (2d, 2H, 2 CH-pyrimidinone), 3.68, 3.70 (2s, 6H,
2OCH3), 6.70–7.80 (m, 6H, Ar-H); MS (EI, 70 eV): m/z ¼ 450 (Mþ, 6),
151 (base peak, 100). Analysis calculated for C25H26N2O4S (450.55):
C, 66.64; H, 5.82; N, 6.22; S, 7.12. Found: C, 66.60; H, 5.76; N, 6.14; S,
7.05.
4.1.11. Synthesis of 2-(2,4-dioxopentan-3-ylthio)-1,6-dihydro-4-
(1,2,3,4-tetrahydronaphthalen-6-yl)-6-(3,4-
dimethoxyphenyl)pyrimidin-5(4H)-one (13)
To a solution of 6b (4.0 g, 10 mmol) in alcoholic potassium
hydroxide (50 mL, 2%), 3-chloroacetylacetone (1.40 g,10 mmol) was
added drop wise with stirring. The reaction mixture was stirred at
room temperature for 1 h, then poured onto water, the formed solid
was filtered off, dried and crystallized to give 13. Yield 72%, mp.
226 ꢀC (dioxane); IR (KBr, cmꢂ1): 3220 (NH), 1715 (C]O), 1685
4.2. Antiviral assay
4.2.1. Material and methods
(2C]O); 1H NMR (DMSO-d6):
d 1.67–1.70 (m, 4H, 2 CH2-tetraline),
Compounds (1 mg) were dissolved in 1 mL (10% DMSO and 90%
deionized water) and sterilized by 1% antibiotic–antimycotic
mixture.
2.77–2.80 (m, 4H, 2 CH2-tetraline), 2.55, 2.65 (2s, 6H, 2 COCH3),
3.70, 3.72 (2s, 6H, 2OCH3), 4.45, 4.65 (2d, 2H, 2 CH-pyrimidinone),
4.55 (s, 1H, CH), 6.90–7.40 (m, 6H, Ar-H), 8.20 (s, 1H, NH
exchangeable with D2O); MS (EI, 70 eV): m/z ¼ 494 (Mþ, 15), 269
(base peak, 100). Analysis calculated for C27H30N2O5S (494.60): C,
65.57; H, 6.11; N, 5.66; S, 6.48. Found: C, 65.50; H, 5.98; N, 5.60; S,
6.44.
4.2.1.1. Cells. Vero cell line was used. The cells were propagated in
DMEM medium (Applichem,Germany) supplemented with 10%
fetal bovine serum (Sigma), 1% antibiotic–antimycotic mixture
(PAA Laboratories GmbH, Austria). The pH was adjusted to 7.2–7.4
using 7.5% sodium bicarbonate solution. The mixture was
4.1.12. Synthesis of 2-acetyl-5-(3,4-dimethoxyphenyl)-3-methyl-7-
(5,6,7,8-tetrahydronaphthalen-2-yl)-5H-thiazolo[3,2-a]pyrimidin-
6(7H)-one (14)
sterilized by filtration through 0.2
membrane.
mm pore size nitrocellulose
4.1.12.1. Method A. A mixture of 6b (4.0 g, 10 mmol) and 3-chlor-
oacetylacetone (1.4 g, 10 mmol) in pyridine (20 mL) in the presence
of potassium hydroxide (10 mmol) was heated under reflux for 4 h.
The reaction mixture was poured onto acidified cold water, the
formed solid was filtered off, dried and crystallized to give 14. Yield
70%, mp. 165 ꢀC (DMF/H2O); IR (KBr, cmꢂ1): 1710 (C]O), 1690
4.2.1.2. Plaque reduction assay. Assay was carried out according to
the method of Tebas et al., [24] in a six well plate where vero cells
(105 cell/ml) were cultivated for 2 days at 37 ꢀC. HSV-1 was diluted
to give 104 PFU/well and mixed with the safe concentration of the
compound or different concentrations of acyclovir (used as positive
control) and incubated for 1 h at 37 ꢀC before being added to the
cells. Growth medium was removed from the cell culture plates and
(C]O); 1H NMR (DMSO-d6):
d 1.60 (s, 3H, CH3), 1.65–1.68 (m, 4H, 2
CH2-tetraline), 2.30 (s, 3H, CH3), 2.78–2.80 (m, 4H, 2 CH2-tetraline),
3.50, 3.65 (2d, 2H, 2 CH-pyrimidinone), 3.65, 3.68 (2s, 6H, 2OCH3),
7.10–8.00 (m, 7H, Ar-H); MS (EI, 70 eV): m/z ¼ 476 (Mþ, base peak,
100). Analysis calculated for C27H28N2O4S (476.59): C, 68.04; H,
5.92; N, 5.88; S, 6.73. Found: C, 67.96; H, 5.88; N, 5.82; S, 6.66.
virus-extract or virus- acyclovir mixtures were inoculated (100 mL/
well), After 1 h contact time for virus adsorption, 3 mL of Dulbecco’s
Modified Eagles Media (DMEM) supplemented with 2% agarose
was added onto the cell monolayer, plates were left to solidify and
incubated at 37 ꢀC till formation of viral plaques. Formalin (10%)
was added for 2 h then plates were stained with crystal violet.
Control wells were included where untreated virus was incubated
with Vero cells and finally plaques were counted and percentage
reduction in plaques formation in comparison to control wells was
recorded as following:
4.1.12.2. Method B. A mixture of 13 (4.0 g, 10 mmol) and acetic
anhydride (20 mL) in dry pyridine (30 mL) was heated on a water
bath for 6 h. The reaction mixture was poured onto cold water, the
formed solid was filtered off, dried and crystallized to give 14 in 65%
yield. The crystallized product was identified by m. p., mixed m. p.
and TLC in comparison with authentic sample from Method A.
% inhibition ¼ viral countðuntreatedÞ
ꢂ viral countðtreatedÞ=viral countðuntreatedÞ
ꢃ 100
4.1.13. Synthesis of thiazolo- and thiazinopyrimidines 15 and 16
A mixture of 6b (4.0 g, 10 mmol), 2-bromopropanoic acid or 3-
bromopropanoic acid (10 mmol) and anhydrous sodium acetate
(2 g) in glacial acetic acid (30 mL) and acetic anhydride (10 mL) was
refluxed for 4 h. The reaction mixture was poured into cold water,
the formed solid was filtered off, dried and crystallized to give 15
and 16, respectively.
4.2.1.3. Mechanism of virus inhibition. Possible mechanism of HSV-
1 inhibition by the compound was studied at three different levels:
4.2.1.3.1. Viral replication [25]. Assay was carried out in a 6 well
plate where Vero cells were cultivated (105 cell/ml) for 2 days at
37 ꢀC. Virus was diluted to give 104 PFU/well and applied directly
to the cells and incubated for 1 h at 37 ꢀC, unadsorbed viral
particles were removed by washing cells three successive times by
supplements free-medium. Compound was applied at different
concentration, after 1 h contact time, 3 mL of DMEM medium
4.1.13.1. 5-(3,4-Dimethoxyphenyl)-2-methyl-7-(5,6,7,8-tetrahy-
dronaphthalen-2-yl)-2H-thiazolo-[3,2-a]pyrimidine-3,6(5H,7H)-
dione (15). Yield 56%, mp. 162 ꢀC (MeOH); IR (KBr, cmꢂ1): 1710
(C]O), 1690 (C]O); 1H NMR (DMSO-d6):
d 1.45 (d, 3H, CH3), 1.68–

S.F. Mohamed et al. / European Journal of Medicinal Chemistry 45 (2010) 1494–1501
1501
supplemented with 2% agarose was added to the cell monolayer.
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finally plaques were counted and percentage reduction in plaques
formation in comparison to control wells was recorded as above
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