Synthesis and cytotoxic evaluation for some new 2,5-disubstituted pyrimidine derivatives for anticancer activity

Article abstract of DOI:10.1007/s00044-014-1276-6

Abstract An efficient synthetic approach for 2,5-disubstituted pyrimidines has been reported. The desired 2,5-substituted pyrimidines were obtained by Suzuki coupling of 2-substituted benzyloxy-5-bromopyrimidines with various aryl boronic acids in the presence catalytic amount of PdCl₂(PPh₃)₂ with 0.5 M aqueous Na₂CO₃ in water at 80 °C. 2-Benzyloxy-5-bromopyrimidines were synthesized, in turn by the reaction of 2-chloro-5-bromopyrimidine with substituted benzyl alcohols in the presence of Cs₂CO₃ in CH₃CN:DMF (1:1). Some of the 2,5-disubstituted pyrimidines have shown moderate in vitro cytotoxic activity against HeLa cell line.

Full text of DOI:10.1007/s00044-014-1276-6

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res
DOI 10.1007/s00044-014-1276-6
REVIEW ARTICLE
Synthesis and cytotoxic evaluation for some new 2,5-disubstituted
pyrimidine derivatives for anticancer activity
Onteddu Surendranatha Reddy
K. J. P. Narayana V. Anuradha
•
Ch. Venkata Suryanarayana
B. Hari Babu
•
•
•
Received: 11 June 2014 / Accepted: 28 September 2014
Ó Springer Science+Business Media New York 2014
Abstract An efficient synthetic approach for 2,5-disub-
stituted pyrimidines has been reported. The desired 2,5-
substituted pyrimidines were obtained by Suzuki coupling
of 2-substituted benzyloxy-5-bromopyrimidines with vari-
ous aryl boronic acids in the presence catalytic amount of
PdCl (PPh ) with 0.5 M aqueous Na CO in water at
Introduction
Nitrogen-containing heterocycles are widely found in nat-
ure and are integral part of several biologically active
compounds (Garc ´ı a-Valverde and Torroba, 2005) (Fig. 1).
Many biologically active compounds including nucleic
acids, nucleotides, and corresponding nucleosides have
pyrimidine as a core unit (Lagoja, 2005). It was reported
that pyrimidines and their derivatives exhibited significant
in vitro activity against DNA and RNA (Kappe, 1993). In
addition, pyrimidine derivatives were found to possess
inhibition properties against polio herpes viruses and as
diuretics, antitumor agents, anti HIV agents, and for car-
diovascular diseases (Kappe, 1993). Further, pyrimidines
substituted with nitro group acted as novel allosteric
enhancer of c-amino butyric acid receptor function (Ur-
wyler et al., 2003). Moreover, heterocyclic compounds
2
3 2
2
3
8
0 °C. 2-Benzyloxy-5-bromopyrimidines were synthe-
sized, in turn by the reaction of 2-chloro-5-bromopyrimi-
dine with substituted benzyl alcohols in the presence of
Cs CO in CH CN:DMF (1:1). Some of the 2,5-disubsti-
2
3
3
tuted pyrimidines have shown moderate in vitro cytotoxic
activity against HeLa cell line.
Keywords 2-Chloro-5-bromopyrimidine ꢀ
Cesium carbonate ꢀ Green synthesis ꢀ HeLa cell line ꢀ
PdCl (PPh )
2
3 2
containing a CF group exhibit wide range of biological
3
activities (Berber et al., 2002; Jain et al., 2006). Boyd et al.
(2001) utilized 2-methoxy bromopyrimidine for the syn-
theses of 5-substituted pyrimidones as inhibitors for lipo-
protein-associated phospholipase A. Recently, Xie et al.
(2011) reported that 2,4,5-trisubstituted pyrimidines as a
new class of tubulin polymerization inhibitors and
Electronic supplementary material The online version of this
article (doi:10.1007/s00044-014-1276-6) contains supplementary
material, which is available to authorized users.
5-substituted-6-chloro uracils have been reported (Nencka
et al., 2007) as efficient inhibitors of human thymidine
phosphorylase which plays an important role in angiogen-
esis. Conventional syntheses of pyrimidines are well doc-
umented in the literature, those methods involve double
condensation with elimination of water, alcohol, or hydro-
gen halide between amino and carboxylic acid, acid chlo-
ride or condensation of amino to CN groups or to polarized
double bonds without elimination (Lagoja, 2005; Herrera
et al., 2002). In view of aryl-substituted pyrimidines having
great potential for anticancer activity, we have designed
O. S. Reddy ꢀ B. H. Babu (&)
Department of Chemistry, Acharya Nagarjuna University,
Nagarjuna Nagar, Guntur, Andhra Pradesh, India
e-mail: dr.b.haribabu@gmail.com
Ch. V. Suryanarayana ꢀ V. Anuradha
Department of Chemistry, Vignan School of P.G. Studies,
Guntur, Andhra Pradesh, India
K. J. P. Narayana
Department of Microbiology, Acharya Nagarjuna University,
Nagarjuna Nagar, Guntur, Andhra Pradesh, India
123

Med Chem Res
Fig. 1 Representative
examples of pyrimidine
containing biologically active
compounds
AcHN
S
Cl
CF3
NH2
N
O
N
N
N
C H
N
NH2
2
5
AMG 517
Pyrimethamine
OMe
MeO
MeO
S
NH2
N
N
N
N
N
N
H
H
NO2
NH
2
Trimethoprim
GS39783
2
,5-disubstituted pyrimidines that are not reported so far.
2-(benzyloxy)-5-bromopyrimidine (3a) in quantitative
yield. Similarly, compound 1 was reacted with differently
substituted benzyl alcohols (2b–i; e.g., OMe, F, Cl, OCF3)
and thiophenylmethanol to give the corresponding 2-ben-
zyloxy-5-bromopyrimidines (i.e., 3b–i) in good yields. The
new compounds (i.e., 3a–i) thus obtained were character-
The palladium-catalyzed Suzuki coupling (Miyaura and
Suzuki, 1995) is an important and versatile method for
carbon–carbon bond formation. It has been extensively
explored for synthesis of unsymmetrical biaryls, as well as
aryl pyrimidines (Schomaker and Delia, 2001; Leadbeater
and Marco, 2002; Liu et al., 2005; Li et al., 2007; Bardhan
et al., 2009). Herein, we report palladium-catalyzed Suzuki
coupling for the synthesis of some new 2,5-disubstituted
pyrimidines from 2-benzyloxy-5-bromopyrimidines, aryl-
boronic acids, and water, utilizing the approaches described
earlier (Saygili et al., 2004; Parry et al., 2002; Isley et al.,
1
13
ized well by H NMR, C NMR, and mass spectral data
(See experimental section).
With these intermediates (i.e., 3a–i) in hand, our next aim
was to use these bromopyrimidines for the syntheses of 2,5-
disubstituted pyrimidines through Suzuki coupling. As such,
we have planned to develop a general synthetic route for
synthesis of various 2,5-disubstituted pyrimidines using
Suzuki coupling in water as a key step as shown in Scheme 2.
The optimization of suitable coupling conditions for the
formation of carbon–carbon bond between 2-(substituted
benzyloxy)-5-bromopyrimidine (3a) and 3-(methylsulfo-
nyl) phenylboronic acid by evaluation of various Pd cata-
lysts, solvents, and bases was undertaken (See Table 1).
Then, coupling of compound 3a with PdCl (PPh ) with
2
013; Lipshutz and Abela, 2008).
Results and discussion
The present synthesis begins with commercially available
2
-chloro-5-bromopyrimidine 1 as a starting material. We
selected 1 as starting material on the basis of the following
reasons: 1.The chloro group of compound 1 can easily be
displaced with appropriately substituted benzyl alcohols in
the presence of a base. This is possible because of the
electronegative nitrogen atoms induced polarization in the
sigma bond frame work of pyrimidine ring (Joule and
Mills, 2010; Brown, 1962). The enhanced electron defi-
ciency at the 2, 4, and 6 positions makes these positions
more susceptible for the nucleophilic attack. This nucleo-
philic attack is especially feasible when the substituent is a
chloro or bromo (Joule and Mills, 2010; Brown, 1962). 2.
The bromopyrimidines (3) could serve as suitable candi-
dates for palladium-catalyzed Suzuki coupling.
2
3 2
tetrahydrofuran as solvent at 80 °C afforded the coupling
product 4a with only 50 % yield. Performance of this
reaction at [80 °C caused decomposition of the methane-
sulfonyl group in the target molecule. On the other hand,
when the solvent was replaced with water under the same
conditions produced the desired product 4a with 67 %
yield and[90 % purity. Therefore, replacement of organic
solvent with water allowed us to improve the yields of
Suzuki coupling. Similar conditions have been adopted for
the synthesis of various 2,5-disubstituted pyrimidines (i.e.,
4b–i) as shown in Scheme 2.
In order to establish the generality of reaction conditions
developed with other boronic acids of interest, coupling of
bromopyrimidines (i.e., 3a–i) using similar conditions with
the appropriately substituted phenylboronic acids containing
OMe, CF , and NO groups on aromatic system was carried
As shown in Scheme 1, treatment of 2-chloro-5-bro-
mopyrimidine (1) with 2,4-diflouro benzyl alcohol (2a) in
the presence of cesium carbonate in CH CN and DMF at
3
room temperature for 12 h afforded the desired
3
2
1
23

Med Chem Res
Cl
Br
O
R
Cs CO
2
3
N
N
CH CN:DMF
N
N
3
HO
R
RT, 12h
2
Br
a-i
1
3
OMe
F
O
O
O
O
O
N
N
N
N
OMe
N
N
F
N
N
N
N
OMe
OMe
Br
a, 97%
Br
3b, 71%
Br
3d, 94%
Br
3e, 97%
Br
3c, 61%
3
F
O
O
O
O
S
N
N
Cl
N
N
OCF3
N
N
N
N
F
Br
Br
3h, 94%
Br
3i, 90%
Br
3g, 99%
3
f, 98%
Scheme 1 Synthesis of 2-benzyloxy-5-bromopyrimidines (3)
out and the reactions yielded the desired titled compounds in
good yields (Scheme 3). On the other hand, the substituted
Cytotoxic evaluation of 2,5-disubstituted pyrimidines
compounds (4a–7h)
2
-(benzyloxy) group in 2,5-disubstituted pyrimidines (i.e.,
4
a–i, 5a–g, i, 6b, d–g, and 7b, f–h) was found to be cleaved
The compounds (4a–7h) were tested on Human cervical
cancer cell line (HeLa) using MTT cell proliferation assay.
The compounds were screened for anticancer activity at
100 lg/mL and compounds which showed more than 50 %
cell growth inhibition were selected for dose response study
using different concentrations (0–100 lg/mL). IC50 values
were calculated and are presented in Table 2. The compound
4i showed more potent anticancer activity among the com-
pounds 4a–7h and followed by 5g, 5i, 5e, and 5b.
under standard hydrogenolysis (Morgentin et al., 2009)
conditions to yield 2-hydroxy-5-substituted pyrimidines.
These hydroxy intermediates are useful scaffolds for the
synthesis of diverse functionalized pyrimidines.
Conclusions
In conclusion, we have found that 2-(benzyloxy)-5-
bromopyrimidines as suitable coupling partners for the
green aqueous Suzuki coupling. The desired 2-(benzyl-
oxy)-5-bromopyrimidines were prepared by the treatment
of 2-chloro-5-bromopyrimidine with substituted benzyl
alcohols in the presence of CS CO in CH CN: DMF. As
Experimental
General
2
3
3
such, we have developed an efficient methodology for the
synthesis of various 2,5-disubstituted pyrimidines by cou-
pling of 2-benzyloxy-5-bromopyrimidines with arylboronic
acids in the presence 10 mol% of PdCl (PPh ) in water at
All reactions were carried out in oven-dried glassware
(120 °C) under an atmosphere of nitrogen unless as indi-
cated otherwise. Ethyl acetate and hexanes from Mal-
linckrodt Chemical Co. were dried and distilled from
2
3 2
8
0 °C. In addition, this catalytic system tolerated broad
CaH . Tetrahydrofuran from Chemlabs Chemicals were
2
range of functional groups under mild reaction conditions.
The synthetic methodology developed is general and total
of 26 new 2,5-substituted pyrimidines could be prepared in
high yields and under mild reaction conditions.
dried by distillation from sodium and benzophenone under
an atmosphere of nitrogen. Acetonitrile was purchased
from Qualigens Chemical Co, and dimethylformamide was
purchased from Merck.
123

Med Chem Res
1
Thin layer chromatography (TLC) was performed on
percolated plates (silica gel 60 F254), which were purchased
from Merck Inc. Purification by gravity column chroma-
tography was carried out by use of Silicycle ultra-pure
silica gel (particle size 40–63 lm, 100–200 mesh). Purity
of products was checked by High-resolution mass spectra
hexanes as the eluent); H NMR (DMSO, 300 MHz) d 8.75
(s, 2H, pyrimidine H), 7.39 (d, J = 8.4 Hz, 2H, ArH), 6.94
(d, J = 6.3 Hz, 2H, ArH), 5.29 (s, 2H, ArCH ), 3.75 (s,
2
1
3
3H, OMe); C NMR (DMSO, 100 MHz) d 163.19,
159.75, 159.15, 129.94, 127.97, 113.74, 111.75, 68.83,
55.05; IR (KBr) 1242 (C–O), 1210 (C–N),530 (C–Br)
-
1
?
?
(
HRMS) obtained by means of Q-TOF micro mass spec-
cm ; HRMS (ES ) exact mass calculated for [M?H]
(C H BrN O ) requires m/z 295.000, found m/z 295.101,
trometer and HPLC (Waters 2695). Proton NMR spectra
were obtained on a MR (400 MHz) and Vnmrs (300 MHz)
1
2
11
2 2
297.100.
spectrometer by use of dimethylsulfoxide-d (DMSO) as
6
solvent and TMS as internal standard. Proton NMR
chemical shifts were referenced to residual protonated
solvents (d 2.5 ppm for dimethylsulfoxide), and carbon-13
NMR spectra were obtained on a MR (100 MHz) and
Vnmrs (75 MHz) spectrometer by use of dimethylsulfoxide
as the solvent and TMS as internal standard. Carbon-13
chemical shifts are referenced to the center of the DMSO
septet (d 39.5 ppm). Multiplicities are recorded by the
following abbreviations: s, singlet; d, doublet; t, triplet; q,
quartet; m, multiplet; bs broad singlet; bd, broad doublet;
and J, coupling constant (hertz). Melting points were
obtained with a Buchi MP-B540 melting point apparatus.
5-Bromo-2-(2, 3, 4-trimethoxybenzyloxy) pyrimidine
(3c)
61 % yield as brown solid, mp (recrystallized from ben-
zene) 105.4–107 °C, TLC R
as the eluent); H NMR (DMSO, 300 MHz) d 8.77 (s, 2H,
pyrimidine H), 7.13 (d, J = 8.45 Hz, 1H, ArH), 6.81 (d,
0.18 (10 % EtOAc in hexanes
f
1
J = 8.4 Hz, 1H, ArH), 5.28 (s, 2H, ArCH ), 3.76–3.80 (d,
2
1
3
J = 12.9 Hz, 9H, OMe). C NMR (DMSO, 75 MHz) d
163.23, 159.89, 153.94, 151.98, 141.71, 124.88, 121.62,
111.83, 107.63, 64.88, 61.16, 60.37, 55.87; IR (KBr) 1276
-
1
?
(
C–O), 1263 (C–N), 528 (C–Br) cm ; HRMS (ES ) exact
?
mass calculated for [M?H] (C H BrN O ) requires m/z
1
4
15
2 4
General procedure for the synthesis of substituted
benzyloxy halo pyrimidines (3a–3i, Scheme 1)
355.021, found m/z 355.015, 357.030.
2
-(Benzyloxy)-5-bromopyrimidine (3a)
5-Bromo-2-(4-fluorobenzyloxy) pyrimidine (3d)
In portion wise, Cesium carbonate (6.78 g, 20.6 mmol) was
added to a stirred solution of benzyl alcohol (2.25 g,
94 % yield as white solid, mp (recrystallized from ben-
zene) 103.2–106.1 °C; TLC R
0.38 (10 % EtOAc in
f
1
20.6 mmol) in acetonitrile and dimethylformamide (1:1,
40 mL) under nitrogen atmosphere at room temperature. After
10 min, 5-bromo-2-chloropyrimidine (2.0 g, 10.3 mmol) was
hexanes as the eluent); H NMR (DMSO, 300 MHz) d 8.78
(s, 2H, pyrimidine H), 7.51 (m, 2H, ArH), 7.22 (m, 2H,
1
3
ArH), 5.36 (s, 2H, ArCH ). C NMR (DMSO, 100 MHz)
2
added and the mixture was stirred at the same temperature for
overnight. The reaction was monitored by TLC; after com-
pletion of the reaction, reaction mixture was poured into ice-
cold water; the resultant solid was filtered; solid was washed
with water (3 9 10 mL) followed by n-pentane (2 9 10 mL)
and air dried and recrystallized from benzene gave 3a (2.675 g)
d 163.08, 160.65, 159.84, 132.42, 130.38, 115.32, 111.95,
68.26; IR (KBr) 1270 (C–O), 1270 (C–N), 1338 (C–F), 533
-
(C–Br) cm ; HRMS (ES ) exact mass calculated for
1
?
?
[M?H] (C11
H BrFN O) requires m/z 282.980, found m/z
8 2
283.100, 285.130.
as white solid in 97 % yield, mp 102.9–105.6 °C, TLC R 0.34
5-Bromo-2-(3-fluorobenzyloxy) pyrimidine (3e)
f
1
10 % EtOAc in hexanes as the eluent); H NMR (DMSO,
(
3
00 MHz); d 8.78 (s, 2H, Pyrimidine H), 7.34–7.47 (m, 5H,
97 % yield as white solid, mp (recrystallized from ben-
13
ArH), 5.38 (s, 2H, ArCH2); CNMR (DMSO, 100 MHz) d
63.16,159.83, 136.15, 128.39,128.02,127.95, 111.91, 68.95;
zene) 92–94 °C, TLC R
0.38 (10 % EtOAc in hexanes as
f
1
1
the eluent); H NMR (DMSO, 400 MHz) d 8.79 (s, 2 H,
pyrimidine H), 7.44 (m, 1 H, ArH), 7.28 (m, 2 H, ArH),
13
-1
IR (KBr) 1271(C–O), 1179 (C–N), 525 (C–Br) cm ; HRMS
?
?
ES ) exact mass calculated for [M?H] (C H BrN O)
(
7.17 (td, J = 2.4 Hz, 1 H, ArH), 5.40 (s, 2 H, ArCH
2
);
C
11
9
2
requires m/z 264.989, found m/z 265.091, 267.301.
NMR (DMSO, 100 MHz) d 163.02, 162.02, 159.89,
1
39.08, 130.46, 123.74, 114.65, 112.09, 68.08; IR (KBr)
1
-
5
-Bromo-2-(4-methoxybenzyloxy) pyrimidine (3b)
1 % yield as brown solid, mp (recrystallized from ben-
1282 (C–O), 1240 (C–N),1338 (C–F), 525 (C–Br) cm
?
HRMS (ES ) exact mass calculated for [M?H]
;
?
7
(C11
H
8
BrFN
O) requires m/z 282.980, found m/z 283.050,
2
zene)119.5–124.3 °C, TLC Rf 0.27 (10 % EtOAc in
285.023.
1
23

Med Chem Res
5
-Bromo-2-(4-Chlorobenzyloxy) pyrimidine (3f)
5-Bromo-2-((5-methylthiophen-2-yl) methoxy)
pyrimidine (3i)
9
1
8 % yield as white solid, mp (recrystallized from benzene)
15.7–116.9 °C, TLC R 0.37 (10 % EtOAcin hexanesas the
90 % yield as brown solid, mp (recrystallized from ben-
f
1
eluent); H NMR (DMSO, 300 MHz) d 8.78 (s, 2H, pyrim-
zene) 86–86.8 °C, TLC R 0.4 (10 % EtOAc in hexanes as
f
1
3
1
idine H), 7.46 (m, 4H, ArH), 5.37 (s, 2H, ArCH2); C NMR
DMSO, 100 MHz) d 163.02, 159.83, 135.24, 132.61,
29.74, 128.37, 112.02, 68.09; IR (KBr) 1247 (C–O), 1207
the eluent); H NMR(DMSO, 400 MHz) d 8.79 (s, 2H,
pyrimidine H), 7.03(d, J = 3.6 Hz, 1H, thiophene H),6.70
(
1
(d, J = 2.8 Hz, 1H, thiophene H) 6.46 (s, 2H, thiophene
13
-
1
?
(
C–N), 790 (C–Cl), 525 (C–Br) cm ; HRMS (ES ) exact
CH ),2.41(s, 3H, Me); C NMR (DMSO, 100 MHz) d
2
?
mass calculated for [M?H] (C H BrClN O) requires m/z
162.81, 159.81, 140.99, 135.33, 128.84, 124.91, 111.96,
1
1
8
2
2
5
9
98.950, found m/z 299.120, 301.200.
63.66, 14.94; IR (KBr) 1282 (C–O), 1210 (C–N), 609 (C–
-
1
S), 516 (C–Br) cm ; HRMS (ES ) exact mass calculated
?
?
for [M ? H] (C H BrN OS) requires m/z 284.961, found
-Bromo-2-(2,4-difluorobenzyloxy) pyrimidine (3g)
1
0
9
2
m/z 285.130, 287.090.
9 % yield as pale white solid, mp (recrystallized from
benzene) 85.3–87.6 °C, TLC R 0.36 (10 % EtOAc in
hexanes as the eluent); H NMR (DMSO, 300 MHz) d 8.79
f
1
General procedure for the preparation (benzyloxy)-5-
(
s, 2H, pyrimidine H), 7.62 (q, J = 9 Hz, 1H, ArH), 7.31
(3-(methylsulfonyl) phenyl) pyrimidine (4a)
(
td, J = 8.1 Hz, 1H, ArH), 7.13 (td, J = 2.1 Hz, 1H, ArH),
1
3
5
1
1
1
.39 (s, 2H, ArCH2); C NMR (DMSO, 100 MHz) d
63.70, 162.89, 160.40, 159.91, 132.37, 119.59, 112.15,
11.64, 104.04, 62.70; IR(KBr) 1279 (C–O), 1268 (C–N),
To a oven dried 25 mL round bottom flask were added
2-(benzyloxy)-5-bromopyrimidine (0.15 g, 0.568 mmol),
3-(methylsulfonyl)
phenylboronic
acid
(0.125 g,
-
1
?
324 (C–F), 520 (C–Br) cm ; HRMS (ES ) exact mass
?
0.625 mmol), and 0.5 N aqueous sodium carbonate
(0.240 g, 2.27 mmol in 4.52 mL water) followed by 5 mL
water and were degassed by bubbling with nitrogen gas for
calculated for [M?H] (C H BrF N O) requires m/z
1
1
8
2 2
3
00.97, found m/z 301.09, 303.20.
15 min. PdCl (PPh ) (0.039 g, 0.0056 mmol) was added
2 3 2
5
-Bromo-2-(4(trifluoromethoxy) benzyloxy)
to the above reaction mixture and then heated to 80 °C for
30 min. The reaction mixture was cooled to room temper-
ature, the resultant solid was filtered and solid was washed
with water and air dried. The crude product was recrystal-
lized from dichloromethane in petroleum ether to give 4a
(131 mg) in 67 % yield as off-white solid, mp (recrystal-
lized from dichloromethane in petroleum ether)
pyrimidine (3h)
4 %, yield as white solid, mp (recrystallized from ben-
9
zene) 91.7–93.6 °C, TLC R 0.27 (10 % EtOAc in hexanes
as the eluent); H NMR (DMSO, 300 MHz) d 8.79 (s, 2H,
pyrimidine H), 7.59 (d, J = 8.4 Hz, 2H, ArH), 7.39 (d,
f
1
1
3
J = 8.4 Hz, 2H, ArH),5.41(s, 2H, ArCH2);
NMR(DMSO, 100 MHz) d 163.04, 159.89, 147.96, 135.72,
29.83, 120.99, 112.07, 68.00; IR (KBr) 1271 (C–O), 1216
C
180.1–184.4 °C; TLC R 0.25 (40 % EtOAc in hexanes as
f
1
the eluent); H NMR (DMSO, 300 MHz) d 9.06 (s, 2H,
1
pyrimidine H), 8.26 (s, 1H, ArH), 8.10 (d, J = 7.8 Hz, 1H,
ArH), 7.95 (d, J = 7.8 Hz, 1H, ArH), 7.78 (t, J = 7.5 Hz,
1H, ArH), 7.49 (d, J = 6.9 Hz, 2H, ArH), 7.44–7.34 (m, 3
-
1
?
(
C–N), 1340 (C–F), 534 (C–Br) cm ; HRMS (ES ) exact
?
mass calculated for [M?H] (C H BrF N O) requires m/z
1
2
8
3 2
1
3
3
48.972, found m/z 349.102, 351.081.
H, ArH), 5.48 (s, 2H, ArCH ), 3.30 (s, 3H, SO Me);
2
C
2
Table 1 Exploration of various Pd catalysts, solvents, and bases for the Suzuki coupling
Pd catalyst
Ligand
Bases
CO
Solvent
Cosolvent
–
Temp (°C)
Time(h)
Yield (%)
Pd(PPh
Pd(dppf)Cl
Pd(OAc)
Pd(PPh
3
)
4
–
K
2
3
Benzene
DME
70
80
110
80
80
80
60
80
80
12
6
8
2
–
Na CO
2
3
3
H
–
2
O
22
0
2
TBAB
–
2
K CO
3
PEG-400
DME
8
3
)
4
Na CO
2
H
–
2
O
–
30
15
20
5
Pd
2
(dba)
(dba)
3
PPh
3
Cs
Cs
2
CO
3
Dioxane
Dioxane
DMF
5
Pd
2
3
P(t-Bu)
3
2
CO
3
–
5
PdCl
PdCl
PdCl
2
2
2
(dppf)
–
–
–
3
K PO
4
–
(PPh
(PPh
3
)
)
2
2
Na
2
CO
CO
3
3
H
2
O
–
0.5
2
67
50
3
Na
2
THF
H
2
O
123

Med Chem Res
O
R
O
R
PdCl
2
(PPh
3
)
2
N
N
N
N
0.5M Na CO
2
3
o
H O, 80 C, 30min
2
Br
a-i
(43-80%)
3
SO Me
2
4a-i
F
O
O
O
OMe
OMe
O
O
N
N
N
N
N
N
OMe
N
N
F
N
N
OMe
SO Me
SO Me
SO Me
SO
d, 79%
Me
O
2
2
2
2
SO Me
4c, 43%
2
4
a, 67%
4b, 48%
4e, 76%
4
F
O
O
O
N
N
OCF3
S
N
N
Cl
N
N
N
N
F
SO Me
2
SO Me
2
SO Me
2
SO Me
2
4f, 77%
4i, 75%
4g, 65%
4h, 80%
Scheme 2 Green aqueous Suzuki coupling of 2-(substituted benzyloxy)-5-bromopyrimidines with 3-(methylsulfonyl) phenylboronic acid
NMR (DMSO, 100 MHz) d 164.32, 157.85, 141.84, 136.49,
126.069, 124.69, 113.78, 68.47, 55.08, 43.31; IR (KBr)
-
1
?
1
1
1
35.20, 131.40, 130.19, 128.41, 127.95, 126.20, 126.13,
1250 (C–O), 1294 (SO ), 1176 (C–N) cm ; HRMS (ES )
2
?
24.72, 68.62, 43.31; IR (KBr) 1149 (C–O),1298 (SO ),
2
exact mass calculated for [M?H]
requires m/z 371.098, found m/z 371.067.
(C H N O S)
19 18 2 4
-
186 (C–N) cm ; HRMS (ES ) exact mass calculated for
1
?
?
[
M?H] (C H N O S) requires m/z 341.088, found m/z
18 16 2 3
3
41.080.
5-(3-(Methylsulfonyl) phenyl)-2-(3,4,5-
trimethoxybenzyloxy) pyrimidine (4c)
2
-(4-Methoxybenzyloxy)-5-(3-(methylsulfonyl)
phenyl) pyrimidine (4b)
43 % yield as pale yellow solids, mp (recrystallized from
dichloromethane in petroleum ether) 97.9–102.1 °C; TLC
f
1
R 0.14 (40 % EtOAc in hexanes as the eluent); H NMR
4
8 % yield as pale yellow solids, mp (recrystallized from
dichloromethane in petroleum ether) 155.5–157.0 °C; TLC
f
(DMSO, 400 MHz) d 9.02 (s, 2H, pyrimidine H),8.24 (s,
1H, ArH), 8.06 (bd, J = 6.4 Hz, 1H, ArH), 7.93 (bd,
J = 6.8 Hz, 1H, ArH), 7.75 (bd, J = 6.4 Hz, 1H, ArH),
7.14 (d, J = 8 Hz, 1H, ArH), 6.79 (d, J = 8 Hz, 1H, ArH),
1
R 0.25 (40 % EtOAc in hexanes as the eluent); H NMR
(
DMSO, 300 MHz) d 9.05 (s, 2 H, pyrimidine H), 8.25 (s,
H, ArH), 8.10 (d, J = 7.8 Hz, 1H, ArH), 7.95 (d,
J = 8.1 Hz, 1H, ArH), 7.79 (t, J = 7.8 Hz, 1H, ArH), 7.43
d, J = 8.7 Hz, 2H, ArH), 6.96 (d, J = 8.7 Hz, 2H, ArH),
.39 (s, 2H, ArCH ), 3.76 (s, 3H, OMe), 3.30 (s, 3H,
1
5.34 (s, 2 H, ArCH ), 3.81–3.74 (t, J = 14.8 Hz, 9H,
2
1
OMe), 3.28 (s, 3H, SO Me); C NMR (DMSO, 100 MHz)
3
(
2
5
d 164.36, 157.80, 153.83, 151.94, 141.84, 135.27, 131.37,
130.18, 126.11, 124.74, 121.91, 107.64, 64.45, 61.11,
60.32, 55.84, 43.32; IR (KBr) 1201 (C–O), 1289 (SO2),
2
1
3
SO Me); C NMR (DMSO, 100 MHz) d 164.36, 159.13,
2
1
57.78, 141.04, 135.23, 131.37, 130.18, 129.94, 128.31,
1
23

Med Chem Res
O
R
O
PdCl (PPh )
R
2
3 2
3
N
N
0
.5M Na CO
N
N
2
o
H O, 80 C, 30min
2
1
R = OMe, CF , NO
3
2
(
50-98%)
R1
Br
3a-i
5
a-g,i; 6b,d-g;
and 7b,f-h.
F
OMe
OMe
O
O
O
O
O
O
N
N
N
N
N
OMe
N
N
N
F
N
N
N
N
N
N
Cl
N
N
N
OMe
N
OMe
OMe
b, 60%
OMe
5d, 98%
OMe
OMe
OMe
5
5e, 90%
5f, 97%
5
a, 66%
5
c, 54%
F
O
N
F
O
O
O
O
N
O
N
S
N
N
N
OMe
N
N
F
N
N
Cl
N
N
F
N
CF3
CF3
CF3
CF3
N
OMe
6
b, 87%
6
d, 81%
OMe
6e, 86%
6f, 87%
5i, 60%
5
g, 92%
F
F
O
O
O
N
O
O
N
N
N
OMe
N
N
Cl
N
OCF3
N
N
F
N
F
CF3
NO2
NO2
f, 73%
NO2
h, 62%
6g, 82%
NO2
7
7
7
b, 50%
7
g, 68%
Scheme 3 Syntheses of diversely substituted 2,5-disubstituted pyrimidines use of green aqueous Suzuki coupling
2
-(4-Fluorobenzyloxy)-5-(3-(methylsulfonyl) phenyl)
Table 2 Selected compounds studied for IC50 by using different
concentrations (0–100 lg/mL)
pyrimidine (4d)
Compounds
4d
4i
5b
5e
79 % yield as off white solids, mp (recrystallized from
IC50 (lg/mL)
Compounds
96.1
5g
82.7
5i
89.2
6b
86.2
–
dichloromethane in petroleum ether) 174.3–179.2 °C; TLC
f
1
R 0.27 (40 % EtOAc in hexanes as the eluent); H NMR
IC50 (lg/mL)
83.1
84.3
95.9
–
(DMSO, 400 MHz) d 9.06 (s, 2H, pyrimidine H), 8.25 (S,
1
H, ArH), 8.10 (d, J = 7.6 Hz, 1H, ArH), 7.95 (d,
-
184 (C–N) cm ; HRMS (ES )exact mass calculated for
1
?
1
J = 8.0 Hz, 1H, ArH), 7.78 (t, J = 8.0 Hz, 1H, ArH), 7.56
(q, J = 5.2 Hz, 2H, ArH), 7.23 (t, J = 8.8 Hz, 2H, ArH),
?
[
M?H] (C H N O S) requires m/z 431.119, found m/z
21 22 2 6
1
3
4
31.089.
5.45 (s, 2H, ArCH ), 3.30 (s, 3H, SO Me); C NMR
2 2
123

Med Chem Res
(
DMSO, 75 MHz) d 164.22, 163.46, 157.85, 141.84,
35.18, 132.71, 131.41, 130.27, 126.24, 126.15, 124.72,
7.15 (td, J = 1.5 Hz, 1H, ArH), 5.48 (s, 2H, ArCH , 3.30
2
)
1
3
1
1
1
(s, 3H, SO Me); C NMR (DMSO, 100 MHz) d 164.03,
2
15.37, 67.93, 43.31; IR (KBr) 1218 (C–O), 1295 (C–F),
163.66, 161.08, 157.90, 141.84, 135.12, 132.32, 131.43,
-
309 (SO ), 1186 (C–N) cm ; HRMS (ES ) exact mass
1
?
130.19, 126.40, 126.18, 124.76, 119.89, 111.68, 104.04,
?
62.37, 43.31; HRMS (ES ) exact mass calculated for
2
?
calculated for [M?H] (C H FN O S) requires m/z
1
8
15
2 3
?
[M?H] (C H F N O S) requires m/z 377.069, found
3
59.078, found m/z 359.090.
1
8 14 2 2 3
m/z 396.989.
2
-(3-Fluorobenzyloxy)-5-(3-(methylsulfonyl) phenyl)
pyrimidine (4e)
6 % yield as brown solids, mp (recrystallized from
5-(3-(Methylsulfonyl) phenyl)-2-(4-(trifluoromethoxy)
benzyloxy) pyrimidine (4h)
7
dichloromethane in petroleum ether)132.4–135.2 °C; TLC
f
80 % yield as brown solids, (recrystallized from dichloro-
1
R 0.4 (50 % EtOAc in hexanes as the eluent); H NMR
methane in petroleum ether)149.0–151.1 °C; TLC R 0.31
f
1
(40 % EtOAc in hexanes as the eluent); H NMR (DMSO,
(
DMSO, 300 MHz) d 9.09 (s, 2H, pyrimidine H), 8.33 (d,
J = 8.7 Hz, 2H, ArH), 8.06 (d, J = 8.7 Hz, 2H, ArH),
.43 (d, J = 8.7 Hz, 2H, ArH), 6.96 (d, J = 8.4 Hz, 2H,
300 MHz) d 9.07 (s, 2H, pyrimidine H), 8.26 (s, 1H, ArH),
8.10(d, J = 8.1 Hz, 1H, ArH), 7.95 (d, J = 8.1 Hz, 1H,
ArH), 7.78 (t, J = 7.8 Hz, 1H, ArH), 7.63 (d, J = 8.7 Hz,
2H, ArH), 7.40 (d, J = 8.4 Hz, 2H, ArH), 5.51 (s, 2H,
7
1
3
ArH), 5.40 (s, 2H, ArCH ), 3.76 (s, 3H, SO Me); C NMR
2
2
(
DMSO, 100 MHz) d 164.16, 163,32, 157.89, 141.84,
1
3
1
39.46, 135.15, 131.42, 130.507, 130.19, 126.35, 124.76,
ArCH ), 3.31 (s, 3H, SO Me);
2
C NMR (DMSO,
2
1
23.76, 123.73, 114.59, 67.76, 43.31; IR (KBr) 1254 (C–
100 MHz) d 164.17, 157.88, 147.92, 141.84, 136.05,
135.14, 131.42, 130.19, 129.81, 126.34, 126.17, 124.74,
121.02, 118.76, 67.68, 43.31; IR (KBr) 1217 (C–O), 1342
-
O), 1339 (C–F), 1291 (SO ), 1183 (C–N) cm ; HRMS
1
2
?
?
(
ES ) exact mass calculated for [M?H] (C H FN O S)
18 15 2 3
-
1
?
requires m/z 359.078, found m/z 358.898.
(C–F), 1291 (SO ), 1217 (C–N) cm ; HRMS (ES ) exact
2
?
mass calculated for [M?H] (C H F N O S) requires
1
9 15 3 2 4
2
-(4-Chlorobenzyloxy)-5-(-3(methylsulfonyl) phenyl)
m/z 425.070, found m/z 425.063.
pyrimidine (4f)
2-((5-methylthiophen-2-yl) methoxy)-5-(3-
7
7 % yield as off white solids, mp (recrystallized from
(methylsulfonyl) phenyl) pyrimidine (4i)
dichloromethane in petroleum ether) 159.9–162.2 °C; TLC
f
1
R 0.26 (40 % EtOAc in hexanes as the eluent); H NMR
75 % yield as pale yellow solids, mp (recrystallized from
(
DMSO, 400 MHz) d 9.06 (s, 2 H,pyrimidine H), 8.25 (t,
J = 1.6 Hz, 1H, ArH), 8.10 (d, J = 8.4 Hz, 1H, ArH),
.95 (d, J = 8.4 Hz, 1H, ArH), 7.78 (t, J = 7.6 Hz, 1H,
dichloromethane in petroleum ether)72.0–76.0 °C; TLC Rf
0.4 (40 % EtOAc in hexanes as the eluent); H NMR
1
7
(DMSO, 300 MHz) d 9.07 (s, 2H, pyrimidine H), 8.26 (s,
1H, ArH), 8.11 (d, J = 2.81 Hz, 1H, ArH), 7.95 (d,
J = 8.1 Hz, 1H, ArH), 7.78 (t, J = 7.8 Hz, 1H, ArH), 7.06
(bd, J = 3.6 Hz, 1H, thiophene H), 6.72 (bd, J = 2.4 Hz,
ArH), 7.52 (d, J = 8.4 Hz, 2H, ArH), 7.47 (dd,
J = 2.0 Hz, 2H, ArH), 5.47 (s, 2H, ArCH ), 3.30 (s, 3H,
2
1
3
SO Me); C NMR (DMSO, 75 MHz) d 164.18, 157.86,
2
1
1
1
41.84, 135.58, 135.15, 132.54, 131.41, 130.19, 129.78,
1H, thiophene H), 5.55 s, 2H, ArCH ), 3.31 (s, 3H, OMe),
2
1
3
28.406, 126.30, 126.16, 124.74, 67.78, 43.31; IR (KBr)
1
2.42 (s, 3H, Me); C NMR (DMSO,100 MHz) d 163.97,
157.80, 141.84, 140.89, 135.71,135.16, 131.40, 130.19,
128.73, 126.15, 124.90, 63.35, 43.31, 14.96; IR (KBr) 1294
-
146 (C–O), 1299 (SO ), 1181 (C–N), 800 (C–Cl) cm
2
;
?
?
HRMS (ES ) exact mass calculated for [M?H]
-
1
(
C H ClN O S) requires m/z 375.049, found m/z
3
(C–O), 694 (C–S), 1149 (SO ), 1211 (C–N) cm ; HRMS
2
18
15
2
?
?
3
74.975.
(ES ) exact mass calculated for [M?H] (C H N O S )
17 16 2 3 2
requires m/z 361.060, found m/z 361.083.
2
-(2,4-Difluorobenzyloxy)-5-(3-(methylsulfonyl)
phenyl) pyrimidine (4g)
2-(Benzyloxy)-5-(6-methoxypyridin-3-yl) pyrimidine
5a)
(
6
5 % yield as pale yellow solid, mp(recrystallized from
dichloromethane in petroleum ether) 97.9–102.1 °C; TLC
f
66 % yield as brown solids, mp (recrystallized from
1
R 0.27 (40 % EtOAc in hexanes as the eluent); H NMR
dichloromethane in petroleum ether) 140–142 °C; TLC Rf
0.28 (20 % EtOAc in hexanes as the eluent); H NMR
1
(
DMSO, 300 MHz) d 9.07 (s, 2 H, pyrimidine H), 8.26 (s,
H, ArH), 8.10 (d, J = 7.8 Hz, 1H, ArH), 7.95 (d,
J = 8.1 Hz, 1H, ArH), 7.78 (t, J = 7.8 Hz, 1H, ArH), 7.65
q, J = 8.4 Hz, 1H, ArH), 7.33 (td, J = 2.4 Hz, 1H, ArH),
1
(DMSO, 400 MHz) d 8.94 (s, 2H, pyrimidine H), 8.54 (d,
J = 2.4 Hz, 1H, PyH), 8.08 (dd, J = 2.4 Hz, 1H, PyH),
7.48 (d, J = 7.2 Hz, 2H, ArH), 7.42–7.32 (m, 3H, ArH),
(
1
23

Med Chem Res
6
.94 (d, J = 8.8 Hz, 1H, PyH), 5.45 (s, 2H, ArCH ), 3.90
2
(d, J = 9.2 Hz, 1H, PyH), 5.42 (s, 2H, ArCH ), 3.90 (s,
2
13
1
3
(
s, 3H, OMe); C NMR (DMSO, 100 MHz) d 163.88,
3H, OMe); C NMR (DMSO, 100 MHz) d 163.79,
163.41, 163.03, 157.00, 144.554, 137.23, 132.83, 130.27,
1
1
63.40, 156.99, 144.53, 137.21, 136.60, 128.40, 127.86,
24.84, 123.22, 110.77, 68.44, 53.29; IR (KBr) 1291 (C–
?
124.89, 123.21, 115.32, 110.78, 67.75, 53.30; IR (KBr)
-
1
-1
?
1222 (C–O), 1316 (C–F), 1247 (C–N) cm ; HRMS (ES )
O), 1251 (C–N) cm ; HRMS (ES ) exact mass calculated
?
for [M?H] (C H N O ) requires m/z 294.116, found
?
exact mass calculated for [M?H]
requires m/z 312.107, found m/z 312.069.
(C H FN O )
17 14 3 2
1
7
15
3
2
m/z 294.069.
2
-(4-Methoxybenzyloxy)-5-(6-methoxypyridin-3-yl)
2-(3-Fluorobenzyloxy)-5-(6-methoxypyridin-3-yl)
pyrimidine (5b)
pyrimidine (5e)
6
0 % yield as off white solids, mp (recrystallized from
90 % yield as pale yellow solid, mp (recrystallized from
dichloromethane in petroleum ether) 140.1–141.3 °C; TLC
f
dichloromethane in petroleum ether) 152–154 °C; TLC Rf
0.20 (20 % EtOAc in hexanes as the eluent); H NMR
1
R 0.4 (30 % EtOAc in hexanes as the eluent); H NMR
1
(
DMSO, 400 MHz) d 8.94 (s, 2H, pyrimidine H), 8.54 (d,
J = 2.4 Hz,1H, PyH), 8.08 (dd, J = 2.4 Hz, 1H, PyH),
.42 (d, J = 8.8 Hz, 2H, ArH), 6.96-6.93 (m, 3H, ArH&-
PyH), 5.36 (s, 2H, ArCH ), 3.90 (s, 3H, OMe), 3.76 (s, 3H,
(DMSO, 400 MHz) d 8.95 (s, 2 H, pyrimidine H), 8.55 (d,
J = 2.4 Hz, 1H, PyH), 8.09 (dd, J = 2.4 Hz, 1H, PyH),
7.44 (q, J = 5.6 Hz, 1H, ArH), 7.31 (t, J = 8.8 Hz, 2 H,
7
ArH), 7.17 (t, J = 2.4 Hz, 1 H, ArH), 6.95 (d, J = 8.4 Hz,
13
2
1
3
OMe), C NMR (DMSO, 100 MHz) d 163.92, 163.38,
1H, PyH), 5.47 (s, 2H, ArCH ), 3.90 (s, 3H, OMe);
C
2
1
59.097, 156.95, 144.51, 137.21, 129.85, 128.43, 124.71,
NMR (DMSO, 75 MHz) d 163.53, 163.41, 156.94, 148.59,
144.54, 140.80, 137.22, 135.87, 128.57, 124.89, 123.17,
110.79, 63.21, 53.29; IR (KBr) 1295 (C–O), 1352 (C–F),
1
23.26, 113.77, 110.78, 68.30, 55.06, 53.28; IR (KBr) 1293
-
C–O), 1245 (C–N) cm ; HRMS (ES ) exact mass cal-
1
?
(
?
culated for [M?H] (C H N O ) requires m/z 324.126,
-1
?
1259 (C–N) cm ; HRMS (ES ) exact mass calculated for
?
[M?H] (C H FN O ) requires m/z 312.107, found m/z
1
8 17 3 3
found m/z 324.095.
1
7
14
3 2
312.086.
5
-(6-Methoxypyridin-3-yl)-2-(3,4,5-
trimethoxybenzyloxy) pyrimidine (5c)
2-(4-Chlorobenzyloxy)-5-(6-methoxypyridin-3-yl)
pyrimidine (5f)
5
4.87 % yield as yellow solids, mp (recrystallized from
dichloromethane in petroleum ether) 139.3–144.4 °C; TLC
f
97 % yield as pale yellow solids, mp (recrystallized from
1
R 0.35 (30 % EtOAc in hexanes as the eluent); H NMR
dichloromethane in petroleum ether) 155.9–158.5 °C; TLC
1
R 0.45 (30 % EtOAc in hexanes as the eluent); H NMR
(DMSO, 400 MHz) d 8.94 (s, 2H, pyrimidine H), 8.54 (d,
J = 2.4 Hz, 1H, PyH), 8.08 (dd, J = 2.4 Hz, 1H, PyH),
f
(DMSO, 400 MHz) d 8.95 (s, 2H, pyrimidine H), 8.54 (d,
J = 2.8 Hz, 1H, PyH), 8.09 (dd, J = 2.4 Hz, 1H, PyH),
7.48 (q, J = 8.4 Hz, 4H, ArH), 6.95 (d, J = 9.2 Hz, 1H,
7
.16 (d, J = 8.8 Hz, J = 1H, ArH), 6.95 (d, J = 8.8 Hz,
H, ArH), 6.82 (d, J = 8.0 Hz, 1H, PyH), 5.34 (s, 2H,
1
1
3
ArCH ), 3.89 (s, 3H, OMe), 3.83 (s, 3H, OMe), 3.80 (s, 3H,
2
PyH), 5.44 (s, 2H, ArCH ), 3.89 (s, 3H, OMe); C NMR
2
1
3
OMe), 3.77 (s, 3H, OMe. C NMR (DMSO, 75 MHz) d
(DMSO, 75 MHz) d 163.73,163.43, 157.04, 144.57,
137.25, 135.70, 132.28, 129.69, 128.40, 124.97, 123.17,
110.79, 67.62, 53.31; IR (KBr) 1282 (C–O), 1246 (C–N)
1
1
6
1
63.93, 163.38, 156.97, 153.79, 151.90, 144.53, 141.74,
37.22, 124.65, 123.30, 122.02, 110.77, 109.53, 107.65,
4.28, 61.09, 60.31, 55.84, 53.29; IR (KBr) 1282 (C–O),
-
1
?
807 (C–Cl) cm ; HRMS(ES ) exact mass calculated for
?
[M?H] (C H ClN O ) requires m/z 328.077, found m/z
-
1
?
261(C–N) cm ; HRMS (ES ) exact mass calculated for
1
7
14
3 2
?
M?H] (C H N O ) requires m/z 384.148, found m/z
[
327.965.
2
0 21 3 5
3
84.115.
2-(2,4-Difluorobenzyloxy)-5-(6-methoxypyridin-3-yl)
2
-(4-Fluorobenzyloxy)-5-(6-methoxypyridin-3-yl)
pyrimidine (5g)
pyrimidine (5d)
92 % yield as off white solids, mp (recrystallized from
9
8 % yield as Pale yellow solids, mp (recrystallized from
dichloromethane in petroleum ether) 142.6–144.2 °C; TLC
f
1
R 0.29 (20 % EtOAc in hexanes as the eluent); H NMR
dichloromethane in petroleum ether) 159.6–163.3 °C; TLC
1
R 0.44 (30 % EtOAc in hexanes as the eluent); H NMR
(DMSO, 400 MHz) d 8.96 (s, 2H, pyrimidine H), 8.53 (d,
J = 1.6 Hz, 1H, PyH), 8.09 (dd, J = 2.4 Hz, 1H, PyH),
7.64 (q, J = 8.0 Hz, 1H, ArH), 7.33 (td, J = 2.4 Hz, 1H,
ArH), 7.15 (td, J = 4.0 Hz, 1H, ArH), 6.95 (d, J = 8.8 Hz,
f
(
DMSO, 400 MHz) d 8.95 (s, 2H, pyrimidine H), 8.54 (s,
H, PyH), 8.08 (dd, J = 2.4 Hz, 1H, PyH), 7.53 (t,
J = 7.6 Hz, 2H, ArH), 7.23 (t, J = 8.8 Hz, 2H, ArH), 6.95
1
123

Med Chem Res
1
3
1
H, PyH), 5.45 (s, 2H, ArCH ), 3.90 (s, 3H OMe);
2
C
(DMSO, 75 MHz) d 163.95, 160.27, 158.588, 133.44,
132.77, 130.49, 129.08, 127.77, 126.98, 126.26, 122.15,
115.37, 67.98; IR (KBr) 1224 (C–O), 1317 (C–F), 1264
NMR (DMSO, 100 MHz) d 163.44, 162.75, 160.301,
57.06, 144.60, 137.25, 132.23, 125.06, 123.16, 119.94,
1
1
1
-
1
?
11.56, 110.79, 110.41, 104.04, 62.22, 53.30; IR (KBr)
-
277 (C–O), 1337 (C–F), 1183 (C–N) cm ; HRMS (ES )
(C–N) cm ; HRMS (ES ) exact mass calculated for
?
[M?H] (C H F N O) requires m/z 349.088, found m/z
1
?
1
8 12 4 2
?
exact mass calculated for [M?H] (C H F N O )
17 13 2 3 2
349.057.
requires m/z 330.097, found m/z 330.079.
2-(3-Fluorobenzyloxy)-5-(2-(trifluoromethyl) phenyl)
5
-(6-Methoxypyridin-3-yl)-2-((5-methylthiophen-2-yl)
pyrimidine (6e)
methoxy) pyrimidine (5i)
8
6 % yield as pale yellow liquid, TLC R 0.23 (20 %
f
1
6
0 % yield as brown solid, mp (recrystallized from
EtOAc in hexanes as the eluent); H NMR (DMSO,
300 MHz) d 8.38 (s, 2H, pyrimidine H), 7.90 (d,
J = 7.5 Hz, 1H, ArH), 7.79 (t, J = 7.5 Hz, 1H, ArH), 7.72
(t, J = 7.5 Hz, 1H, ArH), 7.54 (d, J = 7.2 Hz, 1 H, ArH),
7.45 (m, 1H, ArH), 7.34 (m, 2H, ArH), 7.19 (m, 1H, ArH),
dichloromethane in petroleum ether) 109–111.5 °C; TLC
1
R 0.24 (20 % EtOAc in hexanes as the eluent); H NMR
f
(DMSO, 400 MHz) d 9.01 (s, 2H, pyrimidine H), 8.61 (d,
J = 2.0 Hz, 1H, PyH), 8.15 (dd, J = 2.4 Hz, 1H, PyH),
1
3
7
1
2
.10 (d, J = 3.2 Hz, thiophene H), 7.00 (bd, J = 8.4 Hz,
5.40 (s, 2H, ArCH2); C NMR (DMSO, 75 MHz) d
164.35, 160.98, 159.11, 139.86, 133.89, 133.26, 131.00,
129.59, 128.25, 127.56, 126.73, 124.34, 122.63, 115.21,
68.30; IR (KBr) 1259 (C–O), 1328 (C–F), 1220 (C–N)
H, thiophene H), 6.77 (bd, J = 2.4 Hz, 1H, PyH), 5.58 (s,
1
H, ArCH ), 3.95 (s, 3H, OMe), 2.47 (s, 3H, Me);
2
3
C
NMR (DMSO, 75 MHz) d 163.53, 163.41, 156.94, 144.54,
-
1
?
?
1
6
1
40.80, 137.22, 135.87, 128.57, 124.89, 123.17, 110.79,
cm ; HRMS (ES ) exact mass calculated for [M?H]
(C H F N O) requires m/z 349.088, found m/z 349.038.
3.21, 53.29, 14.95; IR (KBr) 1295 (C–O), 656 (C–S),
1
8 12 4 2
-
261(C–N) cm ; HRMS (ES ) exact mass calculated for
1
?
?
M?H] (C H N O S) requires m/z 314.088, found m/z
[
2-(4-Chlorobenzyloxy)-5-(2-(trifluoromethyl) phenyl)
1
6 15 3 2
3
14.047.
pyrimidine (6f)
2
-(4-Methoxybenzyloxy)-5-(2-(trifluoromethyl)
87 % yield as pale yellow solid, mp (recrystallized from
phenyl) pyrimidine (6b)
dichloromethane in petroleum ether) 76–79 °C; TLC R 0.28
f
1
20 % EtOAc in hexanes as the eluent); H NMR (DMSO,
(
8
7 % yield as pale yellow solid, mp (recrystallized from
300 MHz) d 8.62 (s, 2H, pyrimidine H), 7.90 (d, J = 8.1 Hz,
1H, ArH), 7.79 (t, J = 7.5 Hz, 1H, ArH), 7.69 (t,
J = 7.5 Hz, 1H, ArH), 7.49 (m, 5H, ArH), 5.46 (s, 2H,
dichloromethane in petroleum ether) 67–70 °C; TLC Rf
1
0
.25 (20 % EtOAc in hexanes as the eluent); H NMR
DMSO, 300 MHz) d 8.61 (s, 2H, pyrimidine H), 7.90 (d,
J = 7.8 Hz, 1H, ArH), 7.79 (t, J = 7.5 Hz, 1H, ArH), 7.69
t, J = 7.8 Hz, 1 H, ArH), 7.53 (d, J = 7.8 Hz, 1H, ArH),
.45 (d, J = 9.0 Hz, 2H, ArH), 6.97 (d, J = 8.4 Hz, 2H,
1
3
(
ArCH2); C NMR (DMSO, 75 MHz) d 163.89, 158.63,
135.48, 133.41, 132.77, 132.65, 129.87, 129.09, 128.42,
127.76, 127.04, 126.18, 122.15, 67.82; IR (KBr) 1261 (C–
(
-
1
7
O), 1317 (C–F), 805 (C–Cl), 1171 (C–N) cm ; HRMS
?
1
3
?
ArH), 5.38 (s, 2H, ArCH2), 3.77 (s, 3H, OMe); C NMR
(ES ) exact mass calculated for [M?H] (C H ClF N O)
18 12 3 2
(
DMSO, 75 MHz) d 164.07, 159.18, 158.54, 133.52,
requires m/z 365.059, found m/z 364.969.
1
1
32.79, 130.03, 129.06, 128.23, 127.77, 126.81, 126.18,
25.80, 113.79, 68.53, 55.07; IR (KBr) 1254 (C–O), 1323
2-(2,4-Difluorobenzyloxy)-5-(2-(trifluoromethyl)
-
C–F), 1267(C–N) cm ; HRMS (ES ) exact mass calcu-
1
?
(
phenyl) pyrimidine (6g)
?
lated for [M?H] (C H F N O ) requires m/z 361.108,
1
9 15 3 2 2
found m/z 361.110.
82 % yield as pale yellow liquid, TLC R 0.27 (20 %
f
1
EtOAc in hexanes as the eluent); H NMR (DMSO,
2
-(4-Fluorobenzyloxy)-5-(2-(trifluoromethyl) phenyl)
300 MHz) d 8.64 (s, 2H, pyrimidine H), 7.90 (d,
J = 7.8 Hz, 1H, ArH), 7.80 (t, J = 7.2 Hz, 1H, ArH), 7.68
pyrimidine (6d)
(q, J = 8.4 Hz, J = 2H, 2H, ArH), 7.54 (d, J = 7.2 Hz,
8
1 % yield as pale yellow liquid, TLC R 0.23 (20 %
f
1H, ArH), 7.33 (td, J = 2.4 Hz, 1H, ArH), 7.15 (td,
13
J = 1.5 Hz, 1H, ArH), 5.47 (s, 2H, ArCH2); C NMR
1
EtOAc in hexanes as the eluent); H NMR (DMSO,
00 MHz) d 8.63 (s, 2H, pyrimidine H), 7.906 (d,
J = 7.5 Hz, 1H, ArH), 7.80 (t, J = 7.2 Hz, 1H, ArH), 7.70
t, J = 7.5 Hz, 1H, ArH), 7.56 (m, 3H, ArH), 7.24 (t,
3
(DMSO, 75 MHz) d 163.75, 163.35, 160.70, 158.64,
133.38, 132.65, 129.11, 127.76, 127.13, 126.18, 122.15,
119.82, 111.69, 104.06,62.41; IR (KBr) 1286 (C–O), 1286
(
1
3
-1
?
J = 6.3 Hz, 2H, ArH), 5.44 (s, 2H, ArCH2). C NMR
(C–F), 1175 (C–N) cm ; HRMS (ES ) exact mass
1
23

Med Chem Res
?
calculated for [M?H] (C H F N O) requires m/z
5-(4-Nitrophenyl)-2-(4-(trifluoromethoxy) benzyloxy)
1
8 11 5 2
3
67.079, found m/z 367.044.
pyrimidine (7h)
2
-(4-Methoxybenzyloxy)-5-(4-nitrophenyl) pyrimidine
62 % yield as pale yellow solid, mp (recrystalised from
(
7b)
0 % yield as pale yellow solid, mp (recrystallized from
DCM in hexane) 164.8–166.2 °C; TLC R
0.31 (20 %
f
1
EtOAc in hexanes as the eluent); H NMR (DMSO,
400 MHz) d 9.10 (s, 2H, pyrimidineH), 8.33 (d,
J = 8.8 Hz, 2H, ArH), 8.06 (d, J = 8.8 Hz, 2H, ArH),
7.63 (d, J = 8.4 Hz, 2H, ArH), 7.40 (d, J = 8.8 Hz, 2H,
5
dichloromethane in petroleum ether) 168.5–173.1 °C; TLC
1
R 0.17 (20 % EtOAc in hexanes as the eluent); H NMR
f
1
3
(
DMSO, 300 MHz) d 9.07(s, 2H, pyrimidine H), 8.26 (bt,
J = 8.8 Hz, 1H, ArH), 8.11 (d, J = 8.1 Hz, 1H, ArH),
.95 (d, J = 9.6 Hz, 1H, ArH), 7.78 (t, J = 7.8 Hz, 1H,
ArH), 5.51(s, 2H, ArCH ); 3.30 (s, 3H, OMe); C NMR
2
(DMSO, 100 MHz) d 164.45, 158.14, 147.96, 147.03,
140.44, 135.96, 129.93, 127.45, 125.68, 124.14, 121.02,
7
ArH), 7.46 (m, 1H, ArH), 7.32 (m, 2H, ArH), 7.183 (td,
118.76, 67.78; IR (KBr) 1223 (C–O), 1345 (NO
2
), 1199
-
(C–N), 1251 (C–F) cm ; HRMS (ES ) exact mass cal-
1
?
J = 2.1 Hz, 1H, ArH), 5.50 (s, 2H, ArCH ), 3.30 (s, 3H,
2
1
3
?
OMe); C NMR (DMSO, 100 MHz) d 164.63, 159.15,
culated for [M?H]
(C18H F N O ) requires m/z
12 3 3 4
1
58.04, 146.97, 140.53, 129.94, 128.21, 127.37, 125.39,
392.077, found m/z 392.120.
1
24.14, 113.78, 68.60, 55.08; IR (KBr) 1174 (C–O), 1343
-
NO ), 1249 (C–N) cm ; HRMS (ES ) exact mass Cal-
1
?
(
Cytotoxic evaluation of 2,5-disubstituted pyrimidines
2
?
culate for [M?H] (C H N O ) requires m/z 338.106,
compounds (4a–7h)
1
8 15 3 4
found m/z 337.953.
The compounds were tested on HeLa cells using MTT cell
proliferation assay (Plumb et al., 1989). HeLa cell line was
obtained from National Centre for Cell Science (NCCS),
Pune (India) and cultivated in Dulbecco’s modified Eagle’s
medium (DMEM) (Sigma Life Science, USA) containing
10 % fetal bovine serum (FBS). The cells (2,000 cells per
well) were seeded in a 96-well microplate containing
100 lL of DMEM complete medium per well and incu-
2
-(4-Chlorobenzyloxy)-5-(4-nitrophenyl) pyrimidine
(
7f)
7
3 % yield as brown solid, mp (recrystallized from dichlo-
romethane in petroleum ether) 213.6–219.6 °C; TLC R 0.2
f
1
20 % EtOAc in hexanes as the eluent); H NMR (DMSO,
(
4
00 MHz) d 9.10 (s, 2H, pyrimidine H), 8.33 (d, J = 8.8 Hz,
H, ArH), 8.06 (d, J = 8.0 Hz, 2H, ArH), 7.53–7.46 (m, 4H,
2
bated at 37 °C with 5 % CO
.
2
1
3
ArH), 5.50 (s, 2H, ArCH2); C NMR (DMSO, 100 MHz) d
1
The cells were treated different concentrations of com-
pounds up to 72 h for every 24 h interval. Controls were
maintained with 0.5 % DMSO. After 72 h treatment, 5 lL
of MTT (3-(4,5-dimethyl- thiazol-2-yl)-2,5-diphenyltet-
razolium bromide) reagent (R&D Systems, USA) along
with 45 lL of phenol red free DMEM (Sigma Life Science,
USA) without FBS was added to each well and plates were
64.46, 158.13, 147.03, 140.45, 135.49, 132.59, 129.77,
1
28.43, 127.46, 125.65, 124.15, 67.88; IR (KBr) 1103 (C–
-
1
O), 1309 (NO ), 1274 (C–N), 802 (C–Cl) cm ; HRMS
2
?
?
(
ES ) exact mass calculated for [M?H] (C H ClN O )
17 12 3 3
requires m/z 342.056, found m/z 342.110.
2
-(2,4-Difluorobenzyloxy)-5-(4-nitrophenyl)
incubated at 37 °C with 5 % CO
for 4 h. Thereafter,
2
pyrimidine (7g)
50 lL of solubilization buffer (R&D Systems, USA) was
added to each well to dissolve the colored formazan crys-
tals produced by the reduction of MTT. After 24 h, the
optical density was measured at 550 nm using microplate
reader (Bio-Rad, USA).
6
8 % yield as brown solid, mp (recrystallized from
dichloromethane in petroleum ether) 140.1–144.5 °C; TLC
1
R 0.22 (20 % EtOAc in hexanes as the eluent); H NMR
f
(
DMSO, 400 MHz) d 9.10 (s, 2H, pyrimidine H), 8.32 (d,
J = 8.0 Hz, 2H, ArH), 8.06 (d, J = 8.8 Hz, 2H, ArH),
.66 (q, J = 8.0 Hz, 1H, ArH), 7.33 (t, J = 1.6 Hz, 1H,
ArH), 7.14 (td, J = 1.6 Hz, 1H, ArH), 5.50 (s, 2H,
Acknowledgments The authors are highly thankful to Department
of Chemistry, Acharya Nagarjuna University, Nagarjunanagar, Gun-
tur, and Andhra Pradesh, India for constant encouragement.
7
1
3
ArCH2); C NMR (DMSO, 100 MHz) d 164.30, 163.86,
1
1
6
1
62.81, 160.34, 158.13, 147.02, 140.41, 132.31, 127.46,
References
26.13, 125.73, 124.13, 119.74, 115.73, 111.57, 104.04,
2.48; IR (KBr) 1280 (C–O), 1303 (C–F), 1343 (NO ),
2
-
225 (C–N) cm ; HRMS (ES ) exact mass calculated for
1
?
Bardhan S, Wacharasindhu S, Wan Z-K, Mansour TS (2009)
Heteroaryl ethers by oxidative palladium catalysis of pyr-
idotriazol-1-yloxy pyrimidines with arylboronic acids. Org Lett
11:2511–2514
?
[
M?H] (C H F N O ) requires m/z 344.076, found m/z
17 11 2 3 3
3
43.948.
123

Med Chem Res
Berber H, Soufyane M, Santillana-Hayat M, Mirand C (2002)
Unexpected synthesis of (trifluroethyl)pyrimidines from the
heterocyclisation of a-trifluoroacetylpropanenitriles. Tetrahe-
dron Lett 43:9233–9235
Boyd HF, Hammond B, Hickey DMB, Ife RJ, Leach CA, Lewis VA,
Macphee CH, Milliner KJ, Pinto IL, Smith SA, Stansfield IG,
Theobald CJ, Whittaker CM (2001) The identification of a potent
water soluble inhibitor of lipoprotein-associated phosphopase
Liu L, Zhang Y, Wang Y (2005) Phosphine-free palladium acetate
catalyzed Suzuki reaction in water. J Org Chem 70:6122–6125
Miyaura N, Suzuki A (1995) Palladium-catalyzed cross-coupling
reactions of organoboron compounds. Chem Rev 95:2457–2483
Morgentin R, Jung F, Lamorlette M, Maudet M, Menard M, Ple P,
Pasquet G, Renaud F (2009) An efficient large-scale synthesis of
alkyl 5-hydroxy-pyridine- and pyrimidin-2-yl- acetate. Tetrahe-
dron 65(4):757–764
A
2
. Bioorg Med Chem Lett 11:701–704
Nencka R, Votruba I, H rˇ ebabeck y´ H, Jansa P, Tlou sˇ t’ov a´ E, Horsk a´
K, Masoj ´ı dkov a´ M, Hol y´ A (2007) Discovery of 5-substituted-6-
chlorouracils as efficient inhibitors of human thymidine phos-
phorylase. J Med Chem 50:6016–6023
Brown DJ (1962) The chemistry of heterocyclic compounds. In: The
pyrimidines, vol 16. Wiley-Inter science
Garc ´ı a-Valverde M, Torroba T (2005) Special issue: sulfur-nitrogen
heterocycles. Molecules 10:318–320
´
Parry PR, Wang C, Batsanov AS, Bryce MR, Tarbit B (2002)
Functionalized pyridylboronic acids and their Suzuki cross-
coupling reactions to yield novel heteroarylpyridines. J Org
Chem 67:7541–7543
Plumb JA, Milroy R, Kaye SB (1989) Effects of the pH dependence
of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bro-
mide-formazan absorption on chemosensitivity determined by
a novel tetrazolium-based assay. Cancer Res 49(16):4435–4440
Saygili N, Batsanov AS, Bryce MR (2004) 5-Pyrimidylboronic acid
and 2-methoxy-5-pyrimidyl boronic acid: new heteroarylpyrim-
idine derivatives via Suzuki cross-coupling reactions. Org
Biomol Chem 2(6):852–857
´
Herrera A, Mart ´ı ez-Alvarez R, Chioua M, Chioua R, S a´ nchez A
2002) On the regioselectivity in the reaction of aliphatic ketones
(
and Aromatic nitriles. Regiospecific synthesis of alkylarylpyr-
imidines. Tetrahedron 58:10053–10058
Isley NA, Gallou F, Lipshutz BH (2013) Transforming Suzuki-
Miyaura cross-couplings of MIDA boronates into a green
technology: no organic solvents.
35(47):17707–17710
J
Am Chem Soc
1
Jain KS, Chitre TS, Miniyar PB, Kathiravan MK, Bendre VS, Veer
VS, Shahane SR, Shishoo CJ (2006) Biological and medicinal
significance of pyrimidines. Curr Sci 90:793–803
Joule JA, Mills K (2010) Heterocyclic chemistry, 5th edn. Wiley-
Blackwell
Kappe CO (1993) 100 years of the biginelli dihydropyrimidine
synthesis. Tetrahedron 49:6937–6963
Lagoja IM (2005) Pyrimidine as constituent of natural biologically
active compounds. Chem Biodivers 2:1–50
Leadbeater NE, Marco M (2002) Ligand-free palladium catalysis of
the Suzuki reaction in water using microwave heating. Org Lett
Schomaker JM, Delia TJ (2001) Arylation of halogenated pyrimidines
via a Suzuki coupling reaction. J Org Chem 66:7125–7128
Urwyler S, Pozza MF, Lingenhoehl K, Mosbacher J, Lampert C,
0
Froestl W, Koller M, Kaupmann K (2003) N, N -Dicyclopentyl-
2-methylsulfanyl-5-nitro-pyrimidine-4,6-diamine
(GS39783)
and structurally related compounds: novel allosteric enhancers
of gamma-aminobutyric acidB receptor. J Pharmacol Exp Ther
307(1):322–330
4
Li S, Lin Y, Cao J, Zhang S (2007) Guanidine/Pd(OAc)
room temperature Suzuki cross-coupling reaction in aqueous
media under aerobic conditions. J Org Chem 72(11):4067–4072
Lipshutz BH, Abela AR (2008) Micellar catalysis of Suzuki-Miyaura
cross-couplings with heteroaromatics in water. Org Lett
:2973–2976
Xie F, Zhao H, Li D, Chen H, Quan H, Shi X, Lou L, Hu Y (2011)
Syntheisis and Biological Evalution of 2,4,5-Substituted Pyrim-
idines as a New Class of Tubulin Polymerization Inhibitors.
J Med Chem 54:3200–3205
2
- catalyzed
1
0(23):5329–5332
1
23