Synthesis and in vitro anti-HIV evaluation of a new series of 6-arylmethyl-substituted S-DABOs as potential non-nucleoside HIV-1 reverse transcriptase inhibitors

Article abstract of DOI:10.1016/j.ejmech.2008.06.028

A series of new 5-alkyl-2-benzylsulfanylpyrimidin-4(3H)-ones (5a-y) bearing different substituted arylmethyl moieties at the C-6 position of the pyrimidine core have been synthesized and evaluated for their in vitro activities against HIV-1 and HIV-2 in MT-4 cell cultures. The majority of the title compounds showed moderate to good activities against HIV-1 with an IC₅₀ range from 6.67 μM to 0.12 μM. Among them, 6-(3,5-dimethylbenzyl) analogue 5q exhibited the most potent anti-HIV-1 activity (IC₅₀ = 0.12 μM, SI > 2642), which was about 40-fold more active than the reference compounds 1-[(2-hydroxyethoxy)methyl]-6-(phenylsulfanyl)thymine (HEPT) and 2′,3′-dideoxyinosine (DDI). The structure-activity relationships (SARs) of these new congeners were further discussed.

Full text of DOI:10.1016/j.ejmech.2008.06.028

European Journal of Medicinal Chemistry 44 (2009) 1016–1023
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Synthesis and in vitro anti-HIV evaluation of a new series of
6-arylmethyl-substituted S-DABOs as potential non-nucleoside
HIV-1 reverse transcriptase inhibitors
,
b
,
c
c
c
Yue-Ping Wang a, Fen-Er Chen a , Erik De Clercq , Jan Balzarini , Christophe Pannecouque
*
a Department of Chemistry, Fudan University, Shanghai 200433, PR China
b Institute of Biomedical Science, Fudan University, Shanghai 200031, PR China
c Rega Institute for Medical Research, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of new 5-alkyl-2-benzylsulfanylpyrimidin-4(3H)-ones (5a–y) bearing different substituted
arylmethyl moieties at the C-6 position of the pyrimidine core have been synthesized and evaluated for
their in vitro activities against HIV-1 and HIV-2 in MT-4 cell cultures. The majority of the title compounds
Received 1 February 2008
Received in revised form 20 June 2008
Accepted 30 June 2008
showed moderate to good activities against HIV-1 with an IC50 range from 6.67
m
M to 0.12
m
M. Among
M,
Available online 4 July 2008
them, 6-(3,5-dimethylbenzyl) analogue 5q exhibited the most potent anti-HIV-1 activity (IC50 ¼ 0.12
m
SI > 2642), which was about 40-fold more active than the reference compounds 1-[(2-hydroxyethox-
y)methyl]-6-(phenylsulfanyl)thymine (HEPT) and 20,30-dideoxyinosine (DDI). The structure–activity
relationships (SARs) of these new congeners were further discussed.
Keywords:
NNRTIs
S-DABOs
Antiviral activity
In vitro
Ó 2008 Elsevier Masson SAS. All rights reserved.
SAR
HIV-1
HIV-2
1. Introduction
of the pyrimidine nucleus were dependent on the nature of the C-2
side chain. For example, there seems to be a general trend of
In our continuing efforts to find novel effective and selective
anti-HIV-1 agents in 2-alkylsulfanyl-6-benzyl-3,4-dihydropyr-
imidin-4(3H)-ones (S-DABOs) type NNRTIs [1] (1, Fig. 1), we have
synthesized a series of 2-arylcarbonylmethysulfanyl-substituted S-
DABOs [2–4] (2, Fig. 1), many of which exhibited potent anti-HIV-1
activity and high selectivity index (SI) comparable to the well-
known 2-alkylsulfanyl-substituted S-DABOs [5] (F2-S-DABOs, 3,
Fig. 1). The follow-up structure–activity relationship (SAR) studies
on these analogues revealed that the C-2, C-5 and C-6 substituent
effects were tightly linked: the optimal moieties at positions 5 and 6
increasing anti-HIV-1 activity (i-Pr > Et > Me) in 2-arylcarbo-
nylmethylsulfanyl-substituted S-DABOs [2]; while in 2-alkylsul-
fanyl-substituted S-DABOs, the steric bulkiness of the C-5
substituent is detrimental to HIV-1 inhibitory activity (H ꢀ Me >
Et > i-Pr) [6]. Very recently, Botta et al. [7] disclosed a new series
of 2-arylalkylsulfanyl-substituted S-DABOs (4, Fig. 1) with a lead
compound 4a displaying potent anti-HIV-1 activity both in enzyme
and cell-based assays. Inspired by these promising results and
based on the above-mentioned SAR, a new series of 5-alkyl-6-
arylmethyl-2-benzylsulfanyl-substituted S-DABOs (5, Fig. 1) were
synthesized in hopes of further exploration of the structure–activity
relationships of S-DABOs and discovery of new more potent HIV-1
inhibitors. In this paper, we described the synthesis, anti-HIV-1
activity and preliminary SAR studies of these new congeners.
Abbreviations: CDI, 1,10-carbonyldiimidazole; DABO, 2-alkoxyl-6-benzyl-3,4-
dihydropyrimidin-4(3H)-ones; DDI, 20,30-dideoxyinosine; DMF, N,N-dime-
thylformamide; HEPT, 1-[(2-hydroxyethoxy)methyl]-6-(phenylsulfanyl)thymine;
NNRTIs, non-nucleoside reverse transcriptase inhibitors; HIV, human immunode-
ficiency virus; HIV-1, human immunodeficiency virus type-1; HIV-2, human
immunodeficiency virus type-2; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphe-
nyltetrazolium bromide; S-DABOs, 2-alkylsulfanyl-6-benzyl-3,4-dihydropyrimidin-
4(3H)-ones; SARs, structure–activity relationships.
2. Results and discussion
2.1. Chemistry
* Corresponding author. Department of Chemistry, Fudan University, Shanghai
200433, PR China. Tel./fax: þ86 21 65643811.
The synthetic route to the target compounds 5a–y is depicted in
Scheme 1. The key intermediate b-ketoesters 7a–n were easily
E-mail address: rfchen@fudan.edu.cn (F.-E. Chen).
0223-5234/$ – see front matter Ó 2008 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2008.06.028

Y.-P. Wang et al. / European Journal of Medicinal Chemistry 44 (2009) 1016–1023
1017
O
O
O
R2
R1
R2
X
R1
4
HN
HN
HN
3
5
6
2
1
R1
Alkyl
R2
S
N
S
N
S
N
F
O
F
R3
X = CH2, S, CHCN, C=O
2
F2-S-DABOs
S-DABOs
1
3
O
HN
O
R1
S
N
n
HN
R1
Cl
Cl
n = 0-3
S
N
Ar
R2
4a: n = 1, R1 = 4-MeO
4
5
Fig. 1. Chemical structures of S-DABOs.
prepared in 48–98% yield using the method of Clay et al. [8]
by exposure of substituted arylacetic acids 6a–g to 1,10-carbon-
yldiimidazole (CDI) followed by treatment with different ethyl
potassium malonates in the presence of anhydrous MgCl2 and Et3N.
f and 5k–p), a clear positional preference for substitution on the
phenyl ring portion of the benzyl group was observed by
direct comparison: the ortho-substituted analogues (5a, b, k and l)
were more active than the corresponding meta-substituted
ones (5c, d, m and n). Furthermore, the introduction of a bromine
atom (5e and o) or a phenyl group (5f and p) into the para-
position of the C-6 phenyl ring resulted in complete loss of
inhibitory activity against HIV-1. Interestingly, in the group of
disubstituted analogues (5g–j and 5q–w), the most potent
compounds turned out to be the 6-(3,5-dimethylbenzyl) deriva-
tives followed by the 6-(2,6-dichlorobenzyl) analogues (5q vs v
and 5r vs w); and the 6-(3,5-trifluoromethylbenzyl) congeners
were found to be less potent (5t) or devoid of any anti-HIV-1
activity (5i, j and u).
Moreover, it was found that the nature of the substituent at
the C-5 position of the pyrimidine ring also influenced the anti-
HIV-1 activity of these new congeners. When the C-5 substituents
were changed from Me to Et or Et to i-Pr, a marked increase
of anti-HIV-1 activity was observed for all the title compounds.
This conclusion is in agreement with the earlier SAR in related
S-DABO series (i.e., 2-arylcarbonylmethylsulfanyl-substituted S-
DABOs, 2) [2].
As for the substitution on the C-2 benzylsulfanyl group,
replacement of the para-hydrogen (5s) with a methoxy group (5q)
or a nitro group (5r) enhanced the HIV-1 inhibitory activity about
eight and sixfold, respectively. Furthermore, the data in Table 1
indicated that the 4-methoxylbenzylsulfanyl moiety was the
optimal substituent at the C-2 position of this new series of S-
DABOs (compare 5q vs r, 5v vs w and 5m vs n, etc.).
In addition, all the title compounds were also evaluated for their
capability to inhibit the HIV-2 replication in MT-4 cells, but none
was found effective (Table 1). These findings showed that this new
series of S-DABOs was specific for HIV-1 and belonged to typical
NNRTIs.
On the other hand, the rest of b-ketoesters 7o and p were prepared
from commercially available 1-naphthylacetonitrile and ethyl 2-
bromoalkanoate following the procedure described previously [9].
Then, condensation of 7a–p with thiourea in the presence of EtONa
in refluxing EtOH led to substituted uracil 8a–p in 50–88% yield.
Subsequent treatment of 8a–p with appropriate benzyl halides in
the presence of K2CO3 in anhydrous DMF afforded the corre-
sponding target compounds 5a–y in 14–77% yield.
All the target compounds 5a–y were characterized by NMR, MS,
IR and elemental analyses. Both analytical and spectral data of all
the compounds are in full agreement with the proposed structures.
Moreover, the X-ray crystallography of the compound 5v [10]
further confirmed the above structures.
2.2. Anti-HIV activity
The activity and cytotoxicity of these newly synthesized S-DABO
analogues were evaluated in MT-4 cells for their ability to inhibit
HIV-1- and HIV-2-induced cytopathogenicities. The results,
expressed as CC50, IC50 and SI, are illustrated in Table 1 together
with those of HEPT and DDI as reference standards. In general, most
of the tested compounds were noncytotoxic for MT-4 cells at doses
as high as 165
concentrations around 100
majority of these compounds exhibited moderate to good activities
against HIV-1 with an IC50 range from 6.67 M to 0.12 M. Among
m
M, and only two compounds showed CC50 values at
mM or lower (5f and y). Notably, the
m
m
them, 6-(3,5-dimethylbenzyl)-5-ethyl-2-(4-methoxybenzylsulfanyl)-
pyrimidin-4(3H)-one (5q) turned out to be the most promising
compound with an IC50 value of 0.12 mM being about 40-fold more
active than the reference compounds HEPT and DDI. Some other
compounds 5r, v, y, k and m, also showed high HIV-1 inhibitory
activities (IC50 ¼ 0.16
m
M, 0.16
m
M, 0.21
m
M, 0.23
m
M and 0.28
m
M,
3. Conclusion
respectively) and good selectivity indices (SI ¼ 1906, 1793, 178, 717
and 718, respectively).
In summary, we have described the synthesis and anti-HIV-1
activity of a new series of 5-alkyl-6-arylmethyl-2-benzylsulfanyl-
substituted S-DABOs. The bioassay results revealed that the
majority of the title compounds exhibited potent HIV-1 inhibitory
As shown in Table 1, the substitution pattern of the C-6 benzyl
moiety of S-DABOs played a determinant role for their HIV-1
inhibitory potency. In the case of monosubstituted anlaogues (5a–

1018
Y.-P. Wang et al. / European Journal of Medicinal Chemistry 44 (2009) 1016–1023
O
O
R1
Ar
NH
OH
Ar
a
N
H
S
c
6a-g
O
O
8a-p
Ar
O
d
R1
O
7a-p
R1
b
HN
CN
S
N
Ar
R2
5a-y
6,7,8
Ar
2-Br-Ph
3-Br-Ph
4-Br-Ph
R1
Me
Me
Me
Me
Me
Me
Me
Et
7,8
i
j
k
l
m
n
o
Ar
3-Br-Ph
4-Br-Ph
4-Ph-Ph
2,6-Cl2-Ph
3,5-Me2-Ph
3,5-(CF3)2-Ph
1-naphthyl
1-nahphtyl
R1
Et
Et
Et
Et
Et
Et
Et
i-Pr
a
b
c
d
e
f
g
h
4-Ph-Ph
2,6-Cl2-Ph
3,5-Me2-Ph
3,5-(CF3)2-Ph
2-Br-Ph
p
5
a
b
c
d
e
f
g
h
i
Ar
R1
R2
5
Ar
R1
Et
Et
Et
Et
Et
Et
R2
2-Br-Ph
2-Br-Ph
3-Br-Ph
3-Br-Ph
4-Br-Ph
4-Ph-Ph
3,5-Me2-Ph
3,5-Me2-Ph
3,5-(CF3)2-Ph Me
3,5-(CF3)2-Ph Me
Me
Me
Me
Me
Me
Me
Me
Me
MeO
NO2
MeO
NO2
MeO
MeO
MeO
NO2
MeO
NO2
MeO
NO2
MeO
n
o
p
q
r
3-Br-Ph
4-Br-Ph
4-Ph-Ph
3,5-Me2-Ph
3,5-Me2-Ph
3,5-Me2-Ph
3,5-(CF3)2-Ph Et
3,5-(CF3)2-Ph Et
2,6-Cl2-Ph
2,6-Cl2-Ph
1-naphthyl
1-naphthyl
NO2
MeO
MeO
MeO
NO2
H
MeO
NO2
MeO
NO2
MeO
MeO
s
t
u
v
w
x
y
Et
Et
Et
j
k
l
2-Br-Ph
2-Br-Ph
3-Br-Ph
Et
Et
Et
i-Pr
m
Scheme 1. Synthesis of compounds 5a–y. Reagents and conditions: (a) (i) CDI, CH3CN, rt, 30 min; (ii) R1CH(CO2Et)(CO2K), Et3N, anhydrous MgCl2, rt, overnight, then reflux, 2 h; (iii)
13% HCl; (b) (i) R1CHBrCOOEt, Zn, THF, reflux, 8–16 h; (ii) 50% K2CO3; (iii) 13% HCl; (c) thiourea, EtONa, EtOH, reflux, 16 h. (d) (4-R2)PhCH2X (X ¼ Br or Cl), K2CO3, DMF, rt, 18 h.
activity. In particular, the 6-(3,5-dimethylbenzyl) analogue 5q
turned out to be the most potent with an IC50 value of 0.12 M,
spectrometer were recorded in DMSO-d6 or CDCl3. Chemical
shifts are reported in (ppm) units relative to the internal
m
d
being about 40-fold more active than the reference compounds
HEPT and DDI. Based upon the preliminary SAR studies of these
new 2-benzylsulfanyl-substituted S-DABOs, some structural
requirements for high potency against HIV-1 were identified. These
results provided useful indicators for guiding the further rational
design of new S-DABO analogues as more active and selective HIV-1
inhibitors.
standard tetramethylsilane (TMS). Mass spectra were obtained on
an Agilent MS/5975 mass spectrometer. Elemental analyses were
performed on a CARLOERBA 1106 instrument and the results of
elemental analyses for C, H, N and S were within ꢁ0.4% of the
theoretical values. All chemicals and solvents used were of
reagent grade and were purified and dried by standard methods
before use. All air-sensitive reactions were run under a nitrogen
atmosphere. All the reactions were monitored by thin-layer
chromatography (TLC) on pre-coated silica gel G plates at 254 nm
under a UV lamp using ethyl acetate/hexane as eluents. Flash
chromatography separations were obtained on silica gel (300–
400 mesh). Compounds 6a–e and 6g were obtained commer-
cially; 3,5-dimethylpheny acetic acid (6f) was synthesized
4. Experimental protocols
4.1. Chemistry
Melting points were measured on a WRS-1 digital melting
point apparatus and are uncorrected. Infrared (IR) spectra (KBr)
according to the literature procedure [11,12]; and b-ketoesters 7o
and p were prepared following the procedure described previ-
ously [9].
were recorded on
a
Jasco FT/IR-4200 instrument. 1H NMR
(400 MHz) and 13C NMR (100 MHz) on a Brucker AV 400 MHz

Y.-P. Wang et al. / European Journal of Medicinal Chemistry 44 (2009) 1016–1023
1019
Table 1
Biological activities of compounds 5a–y against HIV-1 and HIV-2 in MT-4 cells
Compound
Ar
R1
R2
IC50
(m
M)a
CC50
(
m
M)b
SIc
HIV-1 IIIB
HIV-2
5a
5b
5c
5d
5e
5f
5g
5h
5i
5j
5k
5l
5m
5n
5o
5p
5q
5r
2-Br-Ph
2-Br-Ph
3-Br-Ph
3-Br-Ph
4-Br-Ph
4-Ph-Ph
3,5-Me2-Ph
3,5-Me2-Ph
3,5-(CF3)2-Ph
3,5-(CF3)2-Ph
2-Br-Ph
2-Br-Ph
3-Br-Ph
3-Br-Ph
4-Br-Ph
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Et
Et
Et
Et
Et
Et
Et
Et
Et
MeO
NO2
MeO
NO2
MeO
MeO
MeO
NO2
MeO
NO2
MeO
NO2
MeO
NO2
MeO
MeO
MeO
NO2
H
1.04 ꢁ 0.02
1.46 ꢁ 0.02
6.42 ꢁ 0.39
14.21 ꢁ 9.93
>290
>179
179 ꢁ 7.35
ꢀ246
172
>246
>290
>280
>290
>100
>329
>316
>256
>248
>165 ꢁ 26
>272
>201
>187
>281
>194
>317
>305
>343
>249
>242
>287
>278
>227
>37.39
>405.38
2.71 ꢁ 0.25
ꢀ168
>45
>20
X1
>290
>280
>290
>100
100 ꢁ 18
X1
1.10 ꢁ 0.24
5.46 ꢁ 2.48
>256
>329
>299
>58
X1
X1
717
>368
718
139.6
X1
>316
>256
>248
165
>248
0.23 ꢁ 0.02
0.74 ꢁ 0.20
0.28 ꢁ 0.02
1.34 ꢁ 0.44
>281
>272
201 ꢁ 21
187 ꢁ 34
>281
4-Ph-Ph
>194
194 ꢁ 18
X1
3,5-Me2-Ph
3,5-Me2-Ph
3,5-Me2-Ph
3,5-(CF3)2-Ph
3,5-(CF3)2-Ph
2,6-Cl2-Ph
2,6-Cl2-Ph
1-Naphthyl
1-Naphthyl
0.12 ꢁ 0.03
0.16 ꢁ 0.06
0.95 ꢁ 0.06
ꢀ9.47
>317
>2642
>1906
>361
ꢅ26
X1
>1793
>772
198
178
79
ꢀ98
>305
>343
>249
>242
>287
>278
5s
5t
Et
Et
Et
Et
Et
i-Pr
MeO
NO2
MeO
NO2
MeO
MeO
5u
5v
5w
5x
5y
HEPT
DDI
>242
0.16 ꢁ 0.08
0.36 ꢁ 0.17
1.32 ꢁ 0.07
0.21 ꢁ 0.004
5.06 ꢁ 0.19
5.37 ꢁ 0.1
261 ꢁ 25
37.39 ꢁ 4.08
ꢅ399
ꢀ529
a
IC50: Inhibitory concentration of compound achieving 50% inhibition of HIV-1 multiplication in MT-4 infected cells.
CC50: Cytotoxic concentration of compound that reduces the normal uninfected MT-4 cell viability by 50%.
SI: Selectivity index: ratio CC50/IC50
b
c
.
4.1.1. General procedure for the preparation of
b
-ketoesters 7a–n
with H2O, EtOH, and Et2O, then dried to give 8a–p to be used in the
To a well-stirred solution of substituted diethyl malonate
(517 mmol) in anhydrous EtOH (345 mL) was added dropwise
a solution of KOH (29 g, 517 mmol) in EtOH (345 mL) at room
temperature over 4 h. Then the resulting mixture was allowed to
stand at this temperature for 4–12 h until the pH of the final
mixture had a value between 7 and 8. After removing the solvent,
the residue was rinsed with Et2O and suspended in anhydrous
CH3CN (800 mL), TEA (100 mL, 717 mmol) and MgCl2 (54 g,
567 mmol) were added and the mixture was continued stirring at
room temperature for 2 h. Then a solution of arylacetyl imidazolide,
which was prepared from arylacetic acid (214 mmol) and 1,10-car-
bonyldiimidazole (CDI, 45 g, 259 mmol) in CH3CN (400 mL) 30 min
before, was added and the reaction mixture was stirred overnight
at room temperature. After refluxing for 2 h and then cooled to 0 ꢂC,
a solution of 13% HCl (800 mL) was added slowly and the resulting
clear mixture was stirred for further 15 min. The organic phase was
separated and concentrated, the aqueous phase was extracted with
EtOAc (3 ꢃ 300 mL). The combined organic layers were washed
with saturated NaHCO3 (3 ꢃ 350 mL) and brine (3 ꢃ 350 mL), dried
(Mg2SO4), filtered and concentrated in vacuo to afford the crude
products 7a–n to be used directly in the next step without further
purification.
next step without further purification.
4.1.3. General procedure for the preparation of
target compounds 5a–y
To a stirred solution of 8a–p (3 mmol) in anhydrous DMF
(18 mL) was added K2CO3 (0.46 g, 3.3 mmol) at room temperature.
After stirring for 20 min, appropriate benzyl halides (3.3 mmol)
was added, and stirring was continued at this temperature for
another 18 h. The reaction mixture was poured into cold H2O
(150 mL), the resulting precipitate was collected by filtration and
washed sequentially with small portions of H2O, MeOH and Et2O
and then dried in vacuo at 40 ꢂC to afford the corresponding crude
product, which was purified by flash chromatography or by crys-
tallization to give the pure target compounds 5a–y.
4.1.3.1. 6-(2-Bromobenzyl)-2-(4-methoxybenzylsulfanyl)-5-methyl-
pyrimidin-4(3H)-one (5a). Yield 38%; recrystallized from AcOEt as
a white solid; mp: 212.1–213.5 ꢂC; FT-IR (KBr):
n
3421 (NH), 2950,
2928, 2834 (CH3, CH2), 1650 (C]O), 1610, 1551, 1512, 1474 (aryl)
cmꢄ1; 1H NMR (CDCl3):
(ppm) 1.98 (s, 3H, CH3), 3.68 (s, 3H, OCH3),
d
4.02 (s, 2H, ArCH2), 4.07 (s, 2H, SCH2), 6.69 (d, 2H, J ¼ 8.4 Hz,
Ar0H3,5), 6.94 (d, 2H, J ¼ 8.4 Hz, Ar0H2,6), 7.16–7.64 (m, 4H, ArH),
12.53 (br s, 1H, CONH); 13C NMR (CDCl3):
d (ppm) 10.56 (CH3), 33.88
4.1.2. General procedure for the preparation of 5-alkyl-6-
arylmethyl-substituted thiouracil 8a–p
To a stirred solution of EtONa (250 mmol) in EtOH (30 mL) was
added thiourea (15.3 g, 200 mmol) at room temperature. After
(CH2), 40.85 (CH2), 55.15 (OCH3), 113.78 (2C), 116.89 (C-5), 124.99,
127.22, 128.06, 128.95, 130.11 (2C), 130.98, 132.56, 137.59, 156.31 (C-
6), 158.78 (Ar0-C4), 160.84 (C-2), 165.42 (C-4); MS (EI): m/z 430
(Mþ); Anal. Calcd for C20H19BrN2O2S (430.04): C, 55.69; H, 4.44; N,
6.49; S, 7.43. Found: C, 55.65; H, 4.47; N, 6.46; S, 7.45%.
stirring for 30 min, the corresponding
b-ketoesters 7a–p
(160 mmol) was added and the reaction mixture was refluxed for
16 h under a nitrogen atmosphere. The reaction mixture was cooled
to room temperature and concentrated under reduced pressure,
the remaining residue was dissolved in H2O and neutralized with
13% HCl to precipitate. The solid was collected, washed sequentially
4.1.3.2. 6-(2-Bromobenzyl)-5-methyl-2-(4-nitrobenzylsulfanyl)-
pyrimidin-4(3H)-one (5b). Yield 77%; recrystallized from MEK as
a yellow needle crystal; mp: 218.3–218.9 ꢂC; FT-IR (KBr):
n
3431
(NH), 2932, 2848 (CH2), 1661 (C]O), 1598, 1578, 1511, 1514 (aryl)

1020
Y.-P. Wang et al. / European Journal of Medicinal Chemistry 44 (2009) 1016–1023
cmꢄ1
;
1H NMR (DMSO-d6):
d
(ppm) 1.99 (s, 3H, CH3), 4.02 (s, 2H,
4.1.3.7. 6-(3,5-Dimethylbenzyl)-2-(4-methoxybenzylsulfanyl)-5-
methylpyrimidin-4(3H)-one (5g). Yield 44%; column chro-
ArCH2), 4.26 (s, 2H, SCH2), 7.14–7.61 (m, 6H, Ar0H2,6, ArH), 7.97 (d,
2H, Ar0H3,5), 12.66 (br s, 1H CONH); 13C NMR (DMSO-d6):
d
(ppm)
matography (eluent CH2Cl2/AcOEt 100/10), off-white solid; mp:
10.47 (CH3), 32.20 (CH2), 115.83 (C-5), 123.32 (2C), 124.63, 127.72,
128.60, 129.88 (2C), 131.78, 132.47, 137.84, 146.45, 146.62, 156.2 (C-
6), 159.53 (C-2), 163.50 (C-4); MS (EI): m/z 445 (Mþ); Anal. Calcd for
C19H16BrN3O3S (445.01): C, 51.13; H, 3.61; N, 9.41; S, 7.18. Found: C.
51.15; H, 3.62; N, 9.38; S, 7.16%.
167.0–167.4 ꢂC; FT-IR (KBr):
n
3422 (NH), 2942, 2920, 2832 (CH3,
CH2), 1653 (C]O), 1609, 1570, 1549, 1510, 1453 (aryl) cmꢄ1; 1H NMR
(CDCl3): (ppm) 1.96 (s, 3H, CH3), 2.22 (s, 6H, Ar(CH3)2), 3.71 (s, 3H,
d
OCH3), 3.82 (s, 2H, ArCH2), 4.27 (s, 2H, SCH2), 6.75 (d, 2H, J ¼ 8.8 Hz,
Ar0H3,5), 6.86 (s, 3H, ArH2,4,6), 7.17 (d, 2H, J ¼ 8.8 Hz, Ar0H2,6), 12.51
(br s, 1H, CONH); 13C NMR (CDCl3):
d (ppm) 10.75 (CH3), 21.29 (2C,
4.1.3.3. 6-(3-Bromobenzyl)-2-(4-methoxybenzylsulfanyl)-5-methyl-
Ar(CH3)2), 34.20 (CH2), 40.92 (CH2), 55.22 (OCH3), 113.92 (2C),
116.59 (C-5), 126.76 (2C), 128.11, 129.03, 130.25 (2C), 137.76, 137.96
(2C), 155.76 (C-6), 158.95 (Ar0-C4), 162.15 (C-2), 164.99 (C-4); MS
(EI): m/z 380 (Mþ); Anal. Calcd for C22H24N2O2S (380.16): C, 69.44;
H, 6.36; N, 7.36; S, 8.43. Found: C, 69.46; H, 6.33; N, 7.40; S, 8.42%.
pyrimidin-4(3H)-one (5c). Yield 53%; recrystallized from AcOEt as
a white needle crystal; mp: 176.2–176.3 ꢂC; FT-IR (KBr):
n
3408
(NH), 2946, 2927, 2832 (CH3, CH2), 1655 (C]O), 1610, 1553, 1510
(aryl) cmꢄ1 1H NMR (DMSO-d6)
(ppm) 1.96 (s, 3H, CH3), 3.71 (s,
;
d
3H, OCH3), 3.92 (s, 2H, ArCH2), 4.22 (s, 2H, CH2), 6.75 (d, 2H,
J ¼ 8.0 Hz, Ar0H3,5), 7.11 (d, 2H, J ¼ 8.0 Hz, Ar0H2,6), 7.26 (m, 2H,
ArH5,6), 7.43–7.45 (m, 1H, ArH4), 7.49 (s, 1H, ArH2), 12.58 (br s, 1H,
4.1.3.8. 6-(3,5-Dimethylbenzyl)-5-methyl-2-(4-nitrobenzylsulfanyl)-
pyrimidin-4(3H)-one (5h). Yield 47.41%; column chromatography
(eluent CH2Cl2/AcOEt 100/10), off-white solid; mp: 225.6–226.4 ꢂC;
CONH); 13C NMR (DMSO-d6):
d (ppm) 10.57 (CH3), 32.97 (CH2),
55.13 (OCH3), 113.85 (2C), 115.62 (C-5), 121.79, 128.25, 129.33,
129.72, 130.17 (2C), 130.57, 131.82, 141.19, 157.00 (C-6), 158.50 (Ar0-
C4), 160.00 (C-2), 163.47 (C-4); MS (EI): m/z 430 (Mþ); Anal. Calcd
for C20H19BrN2O2S (430.04): C, 55.69; H, 4.44; N, 6.49; S, 7.43.
Found: C, 55.72; H, 4.43; N, 6.46; S, 7.48%.
FT-IR (KBr):
n
3408 (NH), 2921, 2852 (CH2), 1655 (C]O), 1599, 1544,
(ppm) 1.95 (s, 3H, CH3), 2.18 (s,
1510 (aryl) cmꢄ1; 1H NMR (CDCl3):
d
6H, Ar(CH3)2), 3.81 (s, 2H, ArCH2), 4.42 (s, 2H, SCH2), 6.78 (s, 2H,
ArH2,6), 6.83 (s, 1H, ArH4), 7.49 (d, 2H, J ¼ 8.0 Hz, Ar0H2,6), 8.00 (d,
2H, J ¼ 8.0 Hz, Ar0H3,5), 12.58 (br s, 1H, CONH); 13C NMR (CDCl3):
d
(ppm) 10.78 (CH3), 21.25 (2C, Ar(CH3)2), 33.50 (CH2), 40.69 (CH2),
4.1.3.4. 6-(3-Bromobenzyl)-5-methyl-2-(4-nitrobenzylsulfanyl)-
117.24 (C-5), 123.56 (2C), 126.69 (2C), 128.31, 129.84 (2C), 137.54,
138.15 (2C), 145.03, 147.10, 154.32 (C-6), 161.97 (C-2), 164.55 (C-4);
MS (EI): m/z 395 (Mþ); Anal. Calcd for C21H21N3O3S (395.13): C,
63.78; H, 5.35; N, 10.63; S, 8.11. Found: C, 63.75; H, 5.38; N, 10.61; S,
8.15%.
pyrimidin-4(3H)-one (5d). Yield 54%; recrystallized from MEK as
a white solid; mp: 207.6–209.0 ꢂC; FT-IR (KBr):
n
3432 (NH),
2938, 2851 (CH2), 1656 (C]O), 1595, 1545, 1518, 1476 (aryl)
cmꢄ1 1H NMR (DMSO-d6):
(ppm) 1.95 (s, 3H, CH3), 3.91 (s, 2H,
;
d
ArCH2), 4.39 (s, 2H, SCH2), 7.19–7.42 (m, 4H, ArH), 7.46 (d, 2H,
J ¼ 8.4 Hz, Ar0H2,6), 8.03 (d, 2H, J ¼ 8.4 Hz, Ar0H3,5), 12.69 (br s,
4.1.3.9. 6-(3,5-Bis(trifluoromethyl)benzyl)-2-(4-methoxybenzylsulfanyl)-
1H, CONH); 13C NMR (DMSO-d6):
d
(ppm) 10.51 (CH3), 32.54
5-methylpyrimidin-4(3H)-one (5i). Yield 31%; recrystallized form
(CH2), 115.72 (C-5), 121.75, 123.40 (2C), 128.23, 129.30, 130.05
(2C), 130.53, 131.70, 141.13, 146.50, 146.58, 156.46 (C-6), 160.07
(C-2), 163.53 (C-4); MS (EI): m/z 445 (Mþ); Anal. Calcd for
C19H16BrN3O3S (445.01): C, 51.13; H, 3.61; N, 9.41; S, 7.18. Found:
C, 51.10; H, 3.63; N, 9.45; S, 7.21%.
AcOEt as a white solid; mp: 222.2–222.6 ꢂC; FT-IR (KBr):
n
3422
(NH), 2965, 2938, 2837 (CH3, CH2), 1656 (C]O), 1578, 1557, 1514,
1465 (aryl) cmꢄ1; 1H NMR (DMSO-d6):
(ppm) 2.0 (s, 3H, CH3), 3.67
d
(s, OCH3), 4.10 (s, 2H, ArCH2), 4.15 (s, 2H, SCH2), 6.68 (d, 2H,
J ¼ 8.4 Hz, Ar0H3,5), 6.95 (d, 2H, J ¼ 8.4 Hz, Ar0H2,6), 7.92 (s, 1H, ArH4),
8.02 (s, 2H, ArH2,6), 12.58 (br s, 1H, CONH); 13C NMR (DMSO-d6):
4.1.3.5. 6-(4-Bromobenzyl)-2-(4-methoxybenzylsulfanyl)-5-methyl-
d (ppm) 10.39 (CH3), 32.85 (CH2), 38.89 (CH2), 55.04 (OCH3), 113.74
pyrimidin-4(3H)-one (5e). Yield 66%; recrystallized from AcOEt as
(2C, Ar0-C3,5), 115.65 (C-5), 120.16 (sept, J ¼ 3.7 Hz, Ar-C4), 123.55 (q,
2C, J ¼ 271.1 Hz, CF3), 129.35, 129.84 (2C, Ar0-C2,6), 130.14 (q, 2C,
J ¼ 32.2 Hz, Ar-C3,5), 130.58 (2C, Ar-C2,6), 141.89, 157.18 (C-6), 158.51
(Ar0-C4), 158.82 (C-2), 163.27 (C-4); MS (EI): m/z 488 (Mþ); Anal.
Calcd for C22H18F6N2O2S (488.1): C, 54.10; H, 3.71; N, 5.74; S, 6.56.
Found: C, 54.15; H, 3.68; N, 5.77; S, 6.51%.
a white solid; mp: 204.1–205.6 ꢂC; FT-IR: (KBr)
n
3433 (NH), 2932,
2837 (CH2), 1653 (C]O), 1608, 1549, 1510, 1486 (aryl); 1H NMR
(DMSO-d6): (ppm) 1.97 (s, 3H, CH3), 3.72 (s, 3H, OCH3), 3.87 (s, 2H,
d
ArCH2), 4.24 (s, 2H, SCH2), 6.74 (d, 2H, J ¼ 8.4 Hz, Ar0H3,5), 7.10 (d,
2H, J ¼ 8.4 Hz, Ar0H2,6), 7.20 (d, 2H, J ¼ 8.0 Hz, ArH2,6), 7.47 (d, 2H,
J ¼ 8.0 Hz, ArH3,5), 12.55 (br s, 1H, CONH); 13C NMR (DMSO-d6):
d
(ppm) 10.57 (CH3), 32.86 (CH2), 55.15 (OCH3), 113.79 (2C), 115.50
4.1.3.10. 6-(3,5-Bis(trifluoromethyl)benzyl)-5-methyl-2-(4-nitro-
benzylsulfanyl)pyrimidin-4(3H)-one (5j). Yield 21%; recrystallized
from AcOEt as a white needle crystal; mp: 234.4–235.2 ꢂC; FT-IR
(C-5), 119.55, 129.77, 130.15 (2C), 131.30 (2C), 131.35 (2C), 137.92,
156.79 (C-6), 158.46 (Ar0-C4), 160.17 (C-2), 163.43 (C-4); MS (EI): m/z
430 (Mþ); Anal. Calcd for C20H19BrN2O2S (430.04): C, 55.69; H, 4.44;
N, 6.49; S, 7.43. Found: C, 55.67; H, 4.46; N, 6.49; S, 7.41%.
(KBr):
n
3421 (NH), 2985, 2928, 2850 (CH3, CH2), 1648 (C]O), 1597,
1549, 1517 (aryl) cmꢄ1
;
1H NMR (DMSO-d6):
d
(ppm) 2.00 (s, 3H,
CH3), 4.17 (s, 2H, ArCH2), 4.30 (s, 2H, SCH2), 7.31 (d, 2H, J ¼ 8.4 Hz,
4.1.3.6. 2-(4-Methoxybenzylsulfanyl)-5-methyl-6-(4-phenylbenzyl)-
Ar0H2,6), 7.87 (s,1H, ArH4), 7.94 (s, 2H, ArH2,6), 7.96 (d, 2H, J ¼ 8.4 Hz,
pyrimidin-4(3H)-one (5f). Yield 50%; recrystallized from CHCl3 as
Ar0H3,5), 12.75 (br s, 1H, CONH); 13C NMR (DMSO-d6):
d (ppm) 10.36
a white solid; mp: 215.2–216.9 ꢂC; FT-IR (KBr):
n
3421 (NH), 2954,
2928, 2834 (CH3, CH2), 1659 (C]O), 1582, 1542, 1509, 1486 (aryl)
cmꢄ1 1H NMR (DMSO-d6):
(ppm) 2.00 (s, 3H, CH3), 3.61 (s, 3H,
(CH3), 32.32 (CH2), 38.88 (CH2),115.93 (C-5),120.07 (sept, J ¼ 3.6 Hz,
Ar-C4), 123.21 (2C), 123.46 (q, 2C, J ¼ 271.1 Hz, CF3), 129.69 (2C),
130.08 (q, 2C, J ¼ 32.36 Hz, Ar-C3,5), 130.39 (2C, Ar-C2,6), 141.86,
146.27, 146.44, 156.75 (C-6), 159.07 (C-2), 163.43 (C-4); MS (EI): m/z
503 (Mþ); Anal. Calcd for C21H15F6N3O3S (503.07): C, 50.10; H, 3.00;
N, 8.35; S, 6.37. Found: C, 50.06; H, 3.03; N, 8.35; S, 6.33%.
;
d
OCH3), 3.94 (s, 2H, ArCH2), 4.27 (s, 2H, SCH2), 6.69 (d, 2H, J ¼ 8.0 Hz,
Ar0H3,5), 7.13 (d, 2H, J ¼ 8.0 Hz, Ar0H2,6), 7.36–7.65 (m, 9H, ArH),
12.56 (br s, 1H, CONH); 13C NMR (DMSO-d6):
d (ppm) 10.69 (CH3),
32.90 (CH2), 55.07 (OCH3), 113.84 (2C), 115.84 (C-5), 126.65 (2C),
126.85 (2C), 127.46, 129.08 (2C), 129.68 (2C), 129.89, 130.23 (2C),
137.78, 138.33, 140.09, 156.09 (C-6), 158.46 (Ar0-C4), 160.45 (C-2),
163.37 (C-4); MS (EI): m/z 428 (Mþ); Anal. Calcd for C26H24N2O2S
(428.16): C, 72.87; H, 5.64; N, 6.54; S, 7.48. Found: C, 72.91; H, 5.61;
N, 6.53; S, 7.45%.
4.1.3.11. 6-(2-Bromobenzyl)-5-ethyl-2-(4-methoxybenzylsulfanyl)-
pyrimidin-4(3H)-one (5k). Yield 73%; column chromatography
(eluent CH2Cl2/AcOEt 100/10), white solid; mp: 149.7–149.8 ꢂC; FT-
IR (KBr):
n
3397 (NH), 2965, 2933, 2870, 2836 (CH3, CH2), 1650
(ppm) 1.10
(C]O), 1612, 1567, 1512 (aryl) cmꢄ1; 1H NMR (CDCl3):
d

Y.-P. Wang et al. / European Journal of Medicinal Chemistry 44 (2009) 1016–1023
1021
(t, 3H, J ¼ 7.6 Hz, CH2CH3), 2.56 (q, 2H, J ¼ 7.6 Hz, CH2CH3), 3.76 (s,
3H, OCH3), 4.08 (s, 2H, ArCH2), 4.16 (s, 2H, SCH2), 6.71 (d, 2H,
J ¼ 8.4 Hz, Ar0H3,5), 7.02 (d, 2H, J ¼ 8.4 Hz, Ar0H2,6), 7.06–7.58 (m, 4H,
NMR (DMSO-d6): d (ppm) 13.40 (CH2CH3), 18.31 (CH2CH3), 32.81
(CH2), 38.94 (CH2), 55.15 (OCH3), 113.81(2C), 119.56, 121.54 (C-5),
129.78, 130.14 (2C), 131.34 (4C), 138.21, 157.02 (C-6), 158.47 (Ar0-C4),
159.96 (C-2), 163.03 (C-4); MS (EI): m/z 444 (Mþ); Anal. Calcd for
C21H21BrN2O2S (444.05): C, 56.63; H, 4.75; N, 6.29; S, 7.20. Found: C,
56.67; H, 4.73; N, 6.27; S, 7.21%.
ArH), 12.70 (br s, 1H, CONH); 13C NMR (CDCl3):
d (ppm) 12.98
(CH2CH3), 18.67 (CH2CH3), 33.85 (CH2), 40.25 (CH2), 55.18 (OCH3),
113.79 (2C), 122.84 (C-5), 125.07, 127.22, 128.04, 129.06, 130.13 (2C),
131.00, 132.58, 137.94, 156.45 (C-4), 158.78 (Ar0-C4), 160.41 (C-2),
165.02 (C-4); MS (EI): m/z 444 (Mþ); Anal. Calcd for C21H21BrN2O2S
(444.05): C, 56.63; H, 4.75; N, 6.29; S, 7.20. Found: C, 56.66; H, 4.74;
N, 6.27; S, 7.23%.
4.1.3.16. 5-Ethyl-2-(4-methoxybenzylsulfanyl)-6-(4-phenylbenzyl)-
pyrimidin-4(3H)-one (5p). Yield 18%; recrystallized from THF as
a white solid; mp: 222.0–223.2 ꢂC; FT-IR (KBr):
n
3398 (NH), 2973,
2932, 2867 (CH3, CH2), 1654 (C]O), 1609, 1583, 1542, 1509, 1486
(aryl) cmꢄ1 1H NMR (DMSO-d6):
4.1.3.12. 6-(2-Bromobenzyl)-5-ethyl-2-(4-nitrobenzylsulfanyl)pyrimidin-
4(3H)-one (5l). Yield 63%; recrystallized from AcOEt as white solid;
;
d
(ppm) 1.00 (t, 3H, J ¼ 7.4 Hz,
CH2CH3), 2.50 (q, 2H, J ¼ 7.4 Hz, CH2CH3), 3.60 (s, 3H, OCH3), 3.95 (s,
2H, ArCH2), 4.26 (s, 2H, SCH2), 6.68 (d, 2H, J ¼ 8.8 Hz, Ar0H3,5), 7.10
(d, 2H, J ¼ 8.8 Hz, Ar0H2,6), 7.34–7.66 (m, 9H, ArH), 12.53 (br s, 1H,
mp: 187.6–188.8 ꢂC; FT-IR (KBr):
n
3421 (NH), 2964, 2929, 2867
(CH2, CH2), 1638 (C]O), 1579, 1545, 1521, 1458 (aryl) cmꢄ1; 1H NMR
(CDCl3):
d
(ppm) 1.13 (t, 3H, J ¼ 7.4 Hz, CH2CH3), 2.59 (q, 2H,
CONH); 13C NMR (DMSO-d6):
d (ppm) 13.43 (CH2CH3), 18.34
J ¼ 7.4 Hz, CH2CH3), 4.08 (s, 2H, ArCH2), 4.23 (s, 2H, SCH2), 7.02–7.58
(CH2CH3), 32.78 (CH2), 55.00 (OCH3), 113.80 (2C), 122.11 (C-5),
126.59 (2C), 126.75 (2C), 127.40, 129.02 (2C), 129.68 (2C), 129.84,
130.16 (2C), 138.03, 138.23, 140.01, 156.14 (C-6), 158.40 (Ar0-C4),
159.53 (C-2), 162.82 (C-4); MS (EI): m/z 442 (Mþ); Anal. Calcd for
C27H26N2O2S (442.17): C, 73.27; H, 5.92; N, 6.33; S, 7.25. Found: C,
73.30; H, 5.91; N, 6.31; S, 7.25%.
(m, 6H, Ar0H2,6, ArH), 7.95 (d, 2H, J ¼ 8.8 Hz, Ar0H3,5), 12.44 (br s, 1H,
CONH). 13C NMR (CDCl3):
d (ppm) 12.97 (CH2CH3), 18.71 (CH2CH3),
33.21 (CH2), 40.16 (CH2), 123.34 (C-5), 123.51 (2C), 125.24, 127.30,
128.30, 129.64 (2C), 130.96, 132.75, 137.76, 145.14, 146.98, 155.13 (C-
6), 160.34 (C-2), 164.74 (C-4). MS (EI): m/z 459 (Mþ); Anal. Calcd for
C20H18BrN3O3S (459.03): C, 52.18; H, 3.94; N, 9.13; S, 6.97. Found: C,
52.16; H, 3.95; N, 9.15; S, 6.93%.
4.1.3.17. 6-(3,5-Dimethylbenzyl)-5-ethyl-2-(4-methoxybenzylsulfanyl)-
pyrimidin-4(3H)-one (5q). Yield 57%; column chromatography
(eluent CH2Cl2/AcOEt 100/10), white solid; mp: 146.3–147.4 ꢂC; FT-
4.1.3.13. 6-(3-Bromobenzyl)-5-ethyl-2-(4-methoxybenzylsulfanyl)-
pyrimidin-4(3H)-one (5m). Yield 68%; column chromatography
(eluent petroleum ether/acetone 100/10), white solid; mp: 151.5–
IR (KBr):
n
3422 (NH), 2969, 2932, 2874, 2832 (CH3, CH2), 1647
(C]O), 1613, 1578, 1542, 1511, 1458 (aryl) cmꢄ1
;
1H NMR (CDCl3):
152.5 ꢂC; FT-IR (KBr):
n
3412 (NH), 2959, 2933, 2867, 2836 (CH3,
CH2), 1650 (C]O), 1611, 1582, 1552, 1512, 1475 (aryl) cmꢄ1; 1H NMR
(DMSO-d6):
d
(ppm) 1.02 (t, 3H, J ¼ 7.6 Hz, CH2CH3), 2.27(s, 6H, Ar(CH3)2), 2.51(q,
2H, J ¼ 7.6 Hz, CH2CH3), 3.76 (s, 3H, OCH3), 3.88 (s, 2H, ArCH2), 4.32
(s, 2H, SCH2), 6.79 (d, 2H, J ¼ 8.4 Hz, Ar0H3,5), 6.93 (s, 3H, ArH2,4,6),
7.20 (d, 2H, J ¼ 8.4 Hz, Ar0H2,6), 12.60 (1H, br s, CONH); 13C NMR
d
(ppm) 1.08 (t, 3H, J ¼ 7.2 Hz, CH2CH3), 2.55 (q, 2H,
J ¼ 7.2 Hz, CH2CH3), 3.38 (s, 3H, OCH3), 3.90 (s, 2H, ArCH2), 4.28 (s,
2H, SCH2), 6.75 (d, 2H, J ¼ 8.4 Hz, Ar0H3,5), 7.11 (d, 2H, J ¼ 8.4 Hz,
Ar0H2,6), 7.16 (m, 2H, ArH5,6), 7.37 (m, 1H, ArH4), 7.43 (s, 1H, ArH2),
(CDCl3):
d (ppm) 13.18 (CH2CH3), 18.81 (CH2CH3), 21.28 (2C,
Ar(CH3)2), 34.09 (CH2), 40.31 (CH2), 55.20 (OCH3), 113.90 (2C),
122.51 (C-5), 126.87 (2C), 128.05, 129.14, 130.24 (2C), 137.89 (2C),
138.12, 155.92 (C-6), 158.91 (Ar0-C4), 161.62 (C-2), 164.70 (C-4); MS
(EI): m/z 394 (Mþ); Anal. Calcd for C23H26N2O2S (394.17): C, 70.02;
H, 6.64; N, 7.10; S, 8.13. Found: C, 70.08; H, 6.61; N, 7.13; S, 8.15%.
12.54 (br s, 1H, CONH); 13C NMR (DMSO-d6):
d (ppm) 13.32
(CH2CH3), 18.29 (CH2CH3), 32.91 (CH2), 55.14 (OCH3), 113.86 (2C),
121.58 (C-5), 121.74, 128.29, 129.31, 129.69, 130.16 (2C), 130.57,
131.88, 141.50, 157.16 (C-6), 158.49 (Ar0-C4), 159.48 (C-2), 163.01 (C-
4); MS (EI): m/z 444 (Mþ); Anal. Calcd for C21H21BrN2O2S (444.05):
C, 56.63; H, 4.75; N, 6.29; S, 7.20. Found: C, 56.65; H, 4.77; N, 6.25; S,
7.23%.
4.1.3.18. 6-(3,5-Dimethylbenzyl)-5-ethyl-2-(4-nitrobenzylsulfanyl)-
pyrimidin-4(3H)-one (5r). Yield 48%; column chromatography
(eluent CH2Cl2/AcOEt 100/10), off-white solid; mp: 193.7–194.1 ꢂC;
4.1.3.14. 6-(3-Bromobenzyl)-5-ethyl-2-(4-nitrobenzylsulfanyl)pyrimidin-
4(3H)-one (5n). Yield 57%; recrystallized from CH3CN as an off-
FT-IR (KBr):
n
3432 (NH), 2976, 2935, 2840 (CH3, CH2), 1653 (C]O),
1597, 1541, 1510 (aryl) cmꢄ1
;
1H NMR (CDCl3):
d
(ppm) 1.10 (t, 3H,
white needle crystal; mp: 162.6–163.8 ꢂC; FT-IR (KBr):
n
3417 (NH),
2964, 2933, 2850 (CH3, CH2), 1660 (C]O), 1597, 1551, 1517, 1472
(aryl) cmꢄ1 1H NMR (DMSO-d6):
J ¼ 7.4 Hz, CH2CH3), 2.25 (s, 6H, Ar(CH3)2), 2.58 (q, 2H, J ¼ 7.4 Hz,
CH2CH3), 3.86 (s, 2H, ArCH2), 4.34 (s, 2H, SCH2), 6.77 (s, 2H, ArH2,6),
6.89 (s, 1H, ArH4), 7.27 (d, 2H, J ¼ 8.8 Hz, Ar0H2,6), 7.95 (d, 2H,
J ¼ 8.8 Hz, Ar0H3,5), 12.42 (br s, 1H, CONH); 13C NMR (CDCl3):
;
d
(ppm) 0.94 (t, 3H, J ¼ 7.6 Hz,
CH2CH3), 2.44 (q, 2H, J ¼ 7.6 Hz, CH2CH3), 3.92 (s, 2H, ArCH2), 4.38
(s, 2H, SCH2), 7.19–7.41 (m, 4H, ArH), 7.44 (d, 2H, J ¼ 8.4 Hz, Ar0H2,6),
8.03 (d, 2H, J ¼ 8.4 Hz, Ar0H3,5), 12.65 (br s, 1H, CONH); 13C NMR
d
(ppm) 13.20 (CH2CH3), 18.79 (CH2CH3), 21.24 (2C, Ar(CH3)2), 33.33
(CH2), 40.11 (CH2), 122.99 (C-5), 123.51 (2C), 126.78 (2C), 128.24,
129.82 (2C), 137.90, 138.09 (2C), 145.21, 147.03, 154.78 (C-6), 161.69
(C-2), 164.90 (C-4); MS (EI): m/z 409 (Mþ); Anal. Calcd for
C22H23N3O3S (409.15): C, 64.53; H, 5.66; N, 10.26; S, 7.83. Found: C,
64.55; H, 5.69; N, 10.21; S, 7.85%.
(DMSO-d6):
d (ppm) 13.27 (CH2CH3), 18.26 (CH2CH3), 32.49 (CH2),
38.99 (CH2), 121.74, 122.17 (C-5), 123.45 (2C), 128.27, 129.30, 130.07
(2C), 130.57, 131.77, 141.51, 146.51, 146.60, 155.78 (C-6), 159.09 (C-2),
162.63 (C-4); MS (EI): m/z 459 (Mþ); Anal. Calcd for C20H18BrN3O3S
(459.03): C, 52.18; H, 3.94; N, 9.13; S, 6.97. Found: C, 52.15; H, 3.96;
N, 9.15; S, 6.95%.
4.1.3.19. 2-(Benzylsulfanyl)-6-(3,5-dimethylbenzyl)-5-ethylpyrimidin-
4(3H)-one (5s). Yield 31%; column chromatography (eluent CH2Cl2/
4.1.3.15. 6-(4-Bromobenzyl)-5-ethyl-2-(4-methoxybenzylsulfanyl)-
AcOEt 100/10), off-white solid; mp: 141.8–142.5 ꢂC; FT-IR (KBr):
n
pyrimidin-4(3H)-one (5o). Yield 52%; recrystallized from AcOEt as
3423 (NH), 2966, 2929, 2843 (CH3, CH2), 1632 (C]O), 1571, 1550,
a white solid; mp: 187.4–188.0 ꢂC; FT-IR (KBr):
n
3433 (NH), 2970,
2931, 2867, 2835 (CH3, CH2), 1660 (C]O), 1609, 1579, 1545, 1511,
1484 (aryl) cmꢄ1 1H NMR (DMSO-d6):
(ppm) 0.96 (t, 3H,
1493, 1454 (aryl) cmꢄ1 1H NMR (CDCl3):
;
d
(ppm) 1.12 (t, 3H,
J ¼ 7.2 Hz, CH2CH3), 2.31 (s, 6H, Ar(CH3)2), 2.62 (q, 2H, J ¼ 7.2 Hz,
;
d
CH2CH3), 3.91 (s, 2H, ArCH2), 4.40 (s, 2H, SCH2), 6.91 (s, 3H, ArH2,4,6),
J ¼ 7.4 Hz, CH2CH3), 2.46 (q, 2H, J ¼ 7.4 Hz, CH2CH3), 3.72 (s, 3H,
OCH3), 3.88 (s, 2H, ArCH2), 4.22 (s, 2H, SCH2), 6.74 (d, 2H, J ¼ 8.4 Hz,
Ar0H3,5), 7.07 (d, 2H, J ¼ 8.4 Hz, Ar0H2,6), 7.21 (d, 2H, J ¼ 8.4 Hz,
ArH2,6), 7.48 (d, 2H, J ¼ 8.4 Hz, ArH3,5), 12.53 (br s, 1H, CONH); 13C
7.27 (m, 5H, Ar0H), 12.92 (br s, 1H, CONH); 13C NMR (CDCl3):
d (ppm)
13.16 (CH2CH3), 18.75 (CH2CH3), 21.26 (2C, Ar(CH3)2), 34.33 (CH2),
40.30 (CH2), 122.36 (C-5), 126.80 (2C), 127.27, 128.02, 128.41 (2C),
129.05 (2C), 137.23, 137.84 (2C), 138.07, 155.99 (C-6), 161.80 (C-2),

1022
Y.-P. Wang et al. / European Journal of Medicinal Chemistry 44 (2009) 1016–1023
165.27 (C-4); MS (EI): m/z 364 (Mþ); Anal. Calcd for C22H24N2OS
(364.16): C, 72.49; H, 6.64; N, 7.69; S, 8.80. Found: C, 72.48; H, 6.67;
N, 7.63; S, 8.83%.
4.1.3.24. 5-Ethyl-2-(4-methoxybenzylsulfanyl)-6-(1-naphthylmethyl)-
pyrimidin-4(3H)-one (5x). Yield 28%; column chromatography
(eluent CH2Cl2/AcOEt, 100/5–100/25), white solid; mp: 166.6–
168.1 ꢂC; FT-IR (KBr):
n
3397 (NH), 2973, 2935, 2834 (CH3, CH2),
4.1.3.20. 6-(3,5-Bis(trifluoromethyl)benzyl)-5-ethyl-2-(4-methox-
ybenzylsulfanyl)pyramidin-4(3H)-one (5t). Yield 43%; column
chromatography (eluent petroleum ether/acetone 100/10); mp:
1646 (C]O), 1611, 1569, 1547, 1511 (aryl) cmꢄ1
;
1H NMR (CDCl3):
d
(ppm) 1.02 (t, 3H, J ¼ 7.6 Hz, CH2CH3), 2.62 (q, 2H, J ¼ 7.6 Hz,
CH2CH3), 3.71 (s, 3H, OCH3), 3.99 (s, 2H, ArCH2), 4.38 (s, 2H, SCH2),
6.57 (d, 2H, J ¼ 8.8 Hz, Ar0H3,5), 6.82 (d, 2H, J ¼ 8.8 Hz Ar0H2,6), 7.22–
199.7–201.4 ꢂC; FT-IR (KBr):
n
3418 (NH), 2981, 2938, 2837 (CH3,
CH2), 1654 (C]O), 1613, 1553, 1514, 1466 (aryl) cmꢄ1 1H NMR
(CDCl3):
;
8.07 (m, 7H, ArH), 12.74 (br s, 1H, CONH); 13C NMR (CDCl3):
d (ppm)
d
(ppm) 1.11 (t, 3H, J ¼ 7.2 Hz, CH2CH3), 2.59 (q, 2H,
13.03 (CH2CH3), 18.79 (CH2CH3), 33.74 (CH2), 37.46 (CH2), 55.13
(OCH3), 113.68 (2C), 122.67 (C-5), 124.07, 125.43, 125.54, 125.95,
126.92, 127.20, 128.65, 128.99, 130.02 (2C), 132.42, 133.80, 134.39,
156.38 (C-6), 158.68 (Ar0-C4), 161.42 (C-2), 165.05 (C-4); MS (EI): m/z
416 (Mþ); Anal. Calcd for C25H24N2O2S (416.16): C, 72.09; H, 5.81; N,
6.73; S, 7.70. Found: C, 72.11; H, 5.78; N, 6.76; S, 7.71%.
J ¼ 7.2 Hz, CH2CH3), 3.77 (s, 3H, OCH3), 4.04 (s, 2H, ArCH2), 4.22 (s,
2H, SCH2), 6.75 (d, 2H, J ¼ 8.8 Hz, Ar0H3,5), 7.07 (d, 2H, J ¼ 8.8 Hz,
Ar0H2,6), 7.76 (s, 3H, ArH2,4,6), 12.70 (br s, 1H, CONH); 13C NMR
(CDCl3): d (ppm) 13.23 (CH2CH3),18.76 (CH2CH3), 34.34 (CH2), 39.64
(CH2), 55.20 (OCH3), 114.00 (2C, Ar0-C3,5), 120.61 (sept, J ¼ 3.6 Hz,
Ar-C4), 122.87 (C-5), 123.32 (q, 2C, J ¼ 270.8 Hz, CF3), 127.94, 129.53
(2C, Ar-C2,6), 129.97 (2C, Ar0-C2,6), 131.63 (q, 2C, J ¼ 33.37 Hz, Ar-
C3,5), 140.61, 157.23 (C-6), 159.11 (Ar0-C4), 159.20 (C-2), 164.56 (C-4);
MS (EI): m/z 502 (Mþ); Anal. Calcd for C23H20F6N2O2S (502.11): C,
54.98; H, 4.01; N, 5.58; S, 6.38. Found: C, 54.95; H, 4.02; N, 5.55; S,
6.36%.
4.1.3.25. 2-(4-Methoxybenzylsulfanyl)-6-(1-naphthylmethyl)-5-(iso-
propyl)pyrimidin-4(3H)-one (5y). Yield 14%; column chromatog-
raphy (petroleum ether/acetone 100/20), yellow solid; mp:
151.2–151.6 ꢂC; FT-IR (KBr):
n
3420 (NH), 2962, 2930, 2867, 2836
(CH3, CH2), 1647 (C]O), 1560, 1541, 1510, 1459 (aryl) cmꢄ1; 1H NMR
(CDCl3):
d
(ppm) 1.31 (d, 6H, J ¼ 7.2 Hz, CH(CH3)2), 3.07 (sept, 1H,
4.1.3.21. 6-(3,5-Bis(trifluoromethyl)benzyl)-5-ethyl-2-(4-nitro-
benzylsulfanyl)pyrimidin-4(3H)-one (5u). Yield 32%; recrystallized
from AcOEt as an off-white solid; mp: 213–214.5 ꢂC; FT-IR (KBr):
J ¼ 7.2 Hz, CH(CH3)2), 3.73 (s, 3H, OCH3), 4.05 (s, 2H, ArCH2), 4.43 (s,
2H, SCH2), 6.61 (d, 2H, J ¼ 8.4 Hz, Ar0H3,5), 6.92 (d, 2H, J ¼ 8.4 Hz,
Ar0H2,6), 7.16–8.10 (m, 7H, ArH), 12.59 (br s, 1H, CONH); 13C NMR
n
3408 (NH), 2976, 2935, 2874, 2855 (CH3, CH2), 1647 (C]O),
(CDCl3):
d
(ppm) 19.76 (2C, 2 ꢃ CH3), 28.00 (CH), 33.76 (CH2), 38.03
1599, 1581, 1543, 1518, 1460 (aryl) cmꢄ1 1H NMR (DMSO-d6):
;
(CH2), 55.18 (OCH3),113.74 (2C),123.91 (C-5),125.46,125.59,125.70,
125.98, 126.46, 127.13, 128.71, 129.10, 130.10 (2C), 132.29, 133.81,
134.54, 156.46 (C-6), 158.74 (Ar0-C4), 160.81 (C-2), 164.37 (C-4); MS
(EI): m/z 430 (Mþ); Anal. Calcd for C26H26N2O2S (430.17): C, 72.53;
H, 6.09; N, 6.51; S, 7.45. Found: C, 72.51; H, 6.06; N, 6.55; S, 7.49%.
d
(ppm) 0.98 (t, 3H, CH2CH3), 2.50 (m, 2H, CH2CH3), 4.18 (s, 2H,
ArCH2), 4.30 (s, 2H, SCH2), 7.33 (d, 2H, J ¼ 8.8 Hz, Ar0H2,6), 7.87 (s,
1H, ArH4), 7.93 (s, 2H, ArH2,6), 7.96 (d, 2H, J ¼ 8.8 Hz, Ar0H3,5),
12.71 (br s, 1H, CONH); 13C NMR (DMSO-d6):
d (ppm) 13.11
(CH2CH3), 18.09 (CH2CH3), 32.34 (CH2), 38.34 (CH2), 120.08 (Ar-
C4), 122.38 (C-5), 123.23 (2C), 123.46 (q, 2C, J ¼ 271 Hz, CF3),
129.72 (2C), 130.05 (q, 2C, J ¼ 32.4 Hz, Ar-C3,5), 130.36 (2C, Ar-
C2,6), 142.10, 146.21, 146.44, 156.13 (C-6), 157.89 (C-2), 162.44 (C-
4); MS (EI): m/z 517 (Mþ); Anal. Calcd for C22H17F6N3O3S
(517.09): C, 51.07; H, 3.31; N, 8.12; S, 6.20. Found: C, 51.06; H,
3.32; N, 8.15; S, 6.22%.
4.2. Anti-HIV assays
The activity of the compounds against HIV-1 (HTLV-ZB strain)
and HIV-2 (ROD) was based on the inhibition of virus-induced
cytopathic effect in MT-4 cells using the 3-(4,5-dimethylthiazol-2-
yl)-2,5-diphenyltetrazolium bromide (MTT) method [13]. Briefly,
virus stocks were titrated in MT-4 cells and expressed as 50% cell
culture infective dose (CCID50). MT-4 cells were suspended in
culture medium at 1 ꢃ105 cells/mL and infected with HIV at
a multiplicity of infection of 0.02. Immediately after virus infection,
4.1.3.22. 6-(2,6-Dichlorobenzyl)-5-ethyl-2-(4-methoxybenzylsulfanyl)-
pyrimidin-4(3H)-one (5v). Yield 46%; recrystallized from MEK as
a colorless block crystal; mp: 231.2–231.5 ꢂC; FT-IR (KBr):
n
3407
(NH), 2968, 2934, 2867, 2933 (CH3, CH2), 1635 (C]O), 1572, 1548,
1511, 1455 (aryl) cmꢄ1 1H NMR (DMSO-d6):
(ppm) 1.10 (t, 3H,
100 mL of the cell suspension was brought into each well of a flat-
;
d
bottomed microtiter tray containing various concentrations of the
test compounds. The test compounds were dissolved in dimethyl
sulfoxide at 50 mM or higher. After a 4-day incubation at 37 ꢂC, the
number of viable cells was determined using the MTT method.
Compounds were tested in parallel for cytotoxic effect in uninfected
MT-4 cells.
J ¼ 7.6 Hz, CH2CH3), 2.55 (q, 2H, J ¼ 7.6 Hz, CH2CH3), 3.70 (s, 3H,
OCH3), 3.94 (s, 2H, ArCH2), 4.25 (s, 2H, SCH2), 6.70 (d, 2H, J ¼ 8.4,
Ar0H3,5), 6.79 (d, 2H, J ¼ 8.4, Ar0H2,6), 7.25 (t, 1H, J ¼ 8.0 Hz ArH4),
7.47 (d, 2H, J ¼ 8.0 Hz, ArH3,5), 12.53 (br s, 1H, CONH); 13C NMR
(DMSO-d6):
d (ppm) 12.67 (CH2CH3), 18.07 (CH2CH3), 32.27 (CH2),
34.96 (CH2), 55.17 (OCH3), 113.80 (2C), 121.04 (C-5), 128.23 (2C),
129.23, 129.79 (2C), 129.96, 134.75, 135.92 (2C), 157.20 (C-6), 157.53
(Ar0-C4), 158.46 (C-2), 162.82 (C-4); MS (EI): m/z 434 (Mþ); Anal.
Calcd for C21H20Cl2N2O2S (434.06): C, 57.93; H, 4.63; N, 6.43; S, 7.37.
Found: C, 57.95; H, 4.60; N, 6.43; S, 7.36%.
Acknowledgements
We are grateful to the National Natural Science Foundation of
China (No. 30672536) and the Geconcerteerde Onderzoeksacties
(GOA No 05/15) for the financial support of this research.
4.1.3.23. 6-(2,6-Dichlorobenzyl)-5-ethyl-2-(4-nitrobenzylsulfanyl)-
pyrimidin-4(3H)-one (5w). Yield 44%; column chromatography
(eluent CH2Cl2/AcOEt 100/10), white solid; mp: 212.0–212.6 ꢂC; FT-
References
IR (KBr):
n
3423 (NH), 2977, 2938, 2867 (CH3, CH2), 1655 (C]O),
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1561, 1519, 1434 (aryl) cmꢄ1
;
1H NMR (DMSO-d6):
d
(ppm) 1.10 (t,
3H, J ¼ 7.6 Hz, CH2CH3), 2.56 (q, 2H, J ¼ 7.6 Hz, CH2CH3), 4.14 (s, 2H,
ArCH2), 4.25(s, 2H, SCH2), 7.10 (d, 2H, J ¼ 8.4 Hz, Ar0H2,6), 7.22 (t, 1H,
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Ar0H3,5), 12.68 (br s, 1H, CONH); MS (EI) m/z 449 (Mþ); Anal. Calcd
for C20H17Cl2N3O3S (449.04): C, 53.34; H, 3.80; N, 9.33; S, 7.12.
Found: C, 53.34; H, 3.81; N, 9.35; S, 7.11%.
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