Syntheses of novel heterocycles as anticancer agents

Article abstract of DOI:10.1016/j.bmc.2005.02.055

Several pteridine analogues 4-13, 23-26 have been synthesized and tested in vitro against three cancer cell lines, MCF7 (breast), NCI-H460 (lung) and SF-268 (CNS). All tested pteridines can serve as novel templates for the anticancer chemotherapy and can serve as new leads in cancer chemotherapy.

Full text of DOI:10.1016/j.bmc.2005.02.055

Bioorganic & Medicinal Chemistry 13 (2005) 3513–3518
Syntheses of novel heterocycles as anticancer agents
ꢀ
Prem M. S. Chauhan, Cristina J. A. Martins and David C. Horwell
*
School of Chemical Sciences and Pharmacy, University of East Anglia Norwich NR4 7TJ, UK
Received 12 November 2004; revised 22 February 2005; accepted 25 February 2005
Available online 6 April 2005
Abstract—Several pteridine analogues 4–13, 23–26 have been synthesized and tested in vitro against three cancer cell lines, MCF7
(breast), NCI-H460 (lung) and SF-268 (CNS). All tested pteridines can serve as novel templates for the anticancer chemotherapy
and can serve as new leads in cancer chemotherapy.
Ó 2005 Elsevier Ltd. All rights reserved.
1
. Introduction
lyzes reduction of folate to 7,8-dihydofolate by
NADPH. Without the function of DHFR, cells are de-
prived of key metabolic intermediates needed to form
nucleotides and ultimately nucleic acids required for
The pharmacological approach to neoplastic disease has
made some impressive gains since 1940 when the antileu-
kemic activity of nitrogen mustard was discovered dur-
ing World War II. Cancer has been recognized as a
disease of aberrant cellular proliferation, with tradi-
tional cancer therapies aiming to exploit the prolifera-
tion machinery. As such, they demonstrate only partial
selectivity for tumour cells over normal cells in prolifer-
ation tissue in the gut and bone marrow.
3
–7
proliferation of cells.
Bearing in mind the importance of folate metabolism in
the proliferation of cells, we have synthesized several
pteridines analogues (4–13, 23–26) as anticancer agents.
Many heterocycles such as quinoline, benzimidazole,
isoxazole and uracil have showed interesting cytotoxic
1
activity and different mode of action in cancer therapy
2
when compared with pteridines. Keeping in view all of
It is now generally accepted that a neoplastic transform-
ation is related to genes alteration or oncogene activa-
tion, allowing progress in the development of new
treatments for malignant diseases, both by revealing
the pathobiology of the disease and the discovery of
new drugs. Moreover, the role of many proteins has
the above facts, we have synthesized hybrid compounds
having pteridine along with different heterocyclic rings
in key positions, 2 and 4. Moreover, in aqueous solution
pteridine adds one or two molecules of water reversibly
across the 3,4-double bond or 5,6- and 7,8-double
bonds, respectively. The equilibrium ratio in favour of
the hydrated or anhydrous adducts varies in acidic or
1
been identified as novel targets in cancer therapy allow-
ing the design of more selective agents.
8
basic environment. This property is of great importance
since it has the potential to increase bioavailability of
these molecules.
The classical anticancer agent methotrexate (MTX)
2
which is a pteridine analog owes its cytotoxicity by
inhibiting the enzyme dihydrofolate reductase (DHFR).
DHFR catalyzes NADPH dependent reduction of 7,8-
dihydrofolate to 5,6,7,8-tetrahydrofolate. It also cata-
We have synthesized several 2- and 4-substituted pter-
idine having different heterocycles in position 2 linked
through a thio ether group (4–13, 26) and an alkylamino
group on position 4 (23–25) in order to establish struc-
ture activity relationship. All synthesized compounds
were tested in vitro against three cancer cell lines,
MCF7 (breast), NCI-H460 (lung) and SF-268 (CNS).
All tested pteridines are potential novel templates for
anticancer chemotherapy and can serve as new clinical
leads in cancer chemotherapy.
Keywords: Heterocycles; Pteridine; Pyrimidine; Uracil; Anticancer.
*
Corresponding author. Tel.: +44 1603593133; fax: +44 1603592003;
e-mail addresses: prem_chauhan_2000@yahoo.com; d.horwell@
uea.ac.uk
ꢀ
Present address: Medicinal Chemistry Division, Central Drug
Research Institute, 226001 Lucknow, India. Tel.: +91 522 2612 411
to 18x4332 (O); fax: +91 522 2623405.
0
968-0896/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2005.02.055

3514
P. M. S. Chauhan et al. / Bioorg. Med. Chem. 13 (2005) 3513–3518
2. Chemistry
3. Anticancer screening
The reaction of 1 with glyoxal and 2,3-butanedione in
methanol gave 4-hydroxy-2-mercaptopteridine 2 and 4-
hydroxy-2-mercapto-6,7-dimethylpteridine 3. Both
mercapto-pteridines were reacted with 2-(chloromethyl)-
quinoline in methanolic sodium hydroxide to give
compounds 4 and 5. Similarly, both mercapto-pteridines
were also reacted with 2-(chloromethyl)benzimidazole
in methanolic sodium hydroxide to afford compounds
3.1. Methodology of the in vitro cancer screening
Experimental compounds were solubilized in dimethyl
sulfoxide (DMSO) at 400-times the desired maximum
tests concentration (maximum final DMSO concentra-
tion of 0.25%) and stored frozen. Compounds were then
diluted with complete media with 0.1% gentamicin sul-
fate (5 lL of test sample in 100% DMSO was added to
565 lL of complete medium). 20 lL of this solution
was then dispensed into test wells containing 50 lL of
cell suspension to yield a test concentration of
6
and 7 and with 4-bromo-phenacylbromide yielded
compounds 8 and 9. Further reaction of 3,5-dimethyl-
-(chloromethyl)isoxazole in methanolic sodium
4
9
–11
hydroxide with 2 and 3 afforded compounds 10
and 11. Refluxing 1,2-dibromoethane, compound 2
and K CO in DMF yielded compound 12 which
1.00EÀ04 M.
Two standard drugs were used as a
standard and tested against each cell line: NSC 19893
(5-FU) and NSC 123127 (Adriamycin). All compounds
were tested for primary anticancer assay against three
cell lines, MCF7 (breast), NCI-H460 (lung) and SF-
2
3
was treated further with pyrrolidine to yield 13
Scheme 1).
(
2
68 (CNS). Results of each test agents is reported as per-
The synthesis of 2-hydroxy-4-mercapto-5,6-diaminopyr-
imidine 15 was achieved through the reaction of 2,4-
dihydroxy-5,6-diaminopyrimidine 14 and phosphorus
pentasulfide in refluxing pyridine. Further cyclization
of 15 with 2,3-butanedione in methanol afforded 19.
Compounds 20–22 were obtained by reacting commer-
cially available 2,4,5,6-tetraaminopyrimidine 16, 2,4-
dimercapto-5,6-diaminopyrimidine 17 and 2-mercapto-
centage growth of the treated cells when compared with
untreated control cells. Compounds which reduce the
growth of any of the cell line by 32% or less (negative
number indicate kills) is considered in vitro active.
4. Results and discussion
4
2
-hydroxy-5,6-diaminopyrimidine 18, respectively, with
,3-butanedione in methanol. Further reactions
Compound 4 has shown 67% growth inhibition against
MCF7 (breast) cell line, 62% against NCI-H460 (lung)
cell lines and 61% against SF-268 (CNS) cell line. Simi-
larly compound 5 has exhibited 53% growth inhibition
against NCI-H460 (lung) cell lines. Similarly, compound
11 has shown 57% growth against MCF7 (breast) cell
line, 66% growth against NCI-H460 (lung) cell lines
of 19–21 with ethanolamine in refluxing DMF
yielded 23–25. Reaction of 4-hydroxy-2-mercapto-6,7-
dimethylpteridine 22 and 2-(chloromethyl)uracil in
methanolic sodium hydroxide gave compound 26
(
Scheme 2).
Br
N
N
N
R
R
S
S
N
N
N
R
R
O
N
N
N
O
8 R = H
OH
9 R = Me
1
1
0 R = H
OH
1 R = Me
iii
iv
ii
N
N
R
HS
N
N
R
R
HS
N
NH2
S
i
N
N
N
N
N
N
R
N
NH2
OH
4
OH 2 R = H
3 R = Me
OH
R = H
R = Me
vii
1
5
v
S
N
N
N
R
R
S
N
N
N
R
R
N
N
N
R
vi
S
N
H
N
N
N
N
R Br
OH
3 R = H
OH
2 R = H
OH
6
7
R = H
R = Me
1
1
Scheme 1. Reagents: (i) glyoxal, 2,3-butanedione, methanol; (ii) 2-(chloromethyl)quinoline, NaOH, methanol; (iii) 4-bromophenacylbromide,
NaOH, methanol; (iv) 3,5-dimethyl-4-(chloromethyl)isoxazole, NaOH, methanol; (v) 1,2-dibromoethane, K
DMF; (vii) 2-(chloromethyl)benzimidazoles, NaOH, methanol.
2 3 2 3
CO , DMF; (vi) pyrrolidine, K CO ,

P. M. S. Chauhan et al. / Bioorg. Med. Chem. 13 (2005) 3513–3518
3515
O
S
Y
NH2
NH2
NH2
NH2
NH2
NH2
HN
i
HN
HN
O
N
H
O
N
H
X
N
H
14
15
16 X=NH, Y=NH
1
7
X=S, Y=S
18 X=S, Y=O
ii
ii
OH
O
Y
HN
N
N
N
N
N
N
N
HN
HN
iv
iii
S
N
X
N
H
X
N
H
26
19 X=O, Y=S
20 X= NH, Y=NH
21 X=S, Y=S
22 X=S, Y=O
23 X=O
NH
24 X=NH
25 X=S
O
N
H
O
2 5
Scheme 2. Reagents: (i) P S , pyridine; (ii) 2,3-butadione, methanol, reflux; (iii) ethanolamine, DMF, 140 °C; (iv) 6-(chloromethyl)uracil, NaOH,
methanol.
Table 1. Percentage growth of the treated cells
duct. Such property will allow pteridine analogues to
form covalent hydration adducts in biological fluid
(water) and increase bioavailability of such molecules.
Compound Breast (MCF7) Lung (NCI-H460) CNS (SF-268)
growth %
growth %
growth %
4
5
6
7
8
9
1
1
1
2
2
2
2
67
87
62
53
61
84
6
. Experimental
68
93
71
79
114
73
100
103
145
101
66
89
91
6.1. Instrumentations and general materials
124
106
57
0
1
3
3
4
5
6
93
62
All reactions were carried out under a nitrogen atmo-
sphere unless otherwise stated. Solvents were of reagent
92
96
103
110
62
99
1
grade and used as supplied commercially. H and
13
C
112
97
NMR spectra were recorded on a Varian 300 MHz spec-
trometer. Melting points were recorded on a Reichert
Thermovar apparatus (350 °C). IR spectra were re-
corded as a thin film on an AVATAR 360 FT-IR spec-
trometer. Microanalyses were performed by A.W.R.
Saunders at the University East Anglia. Electron spray
mass spectrometry spectra were recorded by Richard
Evans at the University East Anglia. Compounds
80
69
103
122
96
115
93
Concentration used in testing (molar units): 1.000EÀ4.
and 62% growth against SF-268 (CNS) cell line. Com-
pound 24 has shown 62% growth against NCI-H460
lung) cell lines. These results suggest that quinoline het-
1, 16, 17, 18 and 20 are commercially available interme-
diates and compounds 2, 3, 15, 19, 21 and 22 were syn-
thesized following the literature procedures.
(
erocycles and isooxazoles play an important role in
inhibiting growth of cancer cell lines. Similarly, com-
pound 24 having an amino group on position 2 and eth-
anolamine on position 4 has shown some inhibiting
effect on the growth of lung cancer cell line. These pter-
idine analogues can serve as novel templates for antican-
cer chemotherapy and can be new leads in cancer
chemotherapy. Further optimization of these identified
chemical leads can possibly lead to more active mole-
cules against cancer (Table 1).
1
2,13
6.2. 2-Mercapto-pteridine-4-ol and 2-mercapto-6,7-di-
methylpteridine-4-ol (2,3)
4,5-Diamino-6-hydroxyl-2-mercapto-pyrimidine (1) (1.50 g,
0.01 mmol) and glyoxal or 2,3-butadione (0.86 g,
2.0 mL, 0.01 mmol) were refluxed in methanol (100
mL) for 3.5 h. The solution was cooled and a
brown solid filtered and dried under vacuum to yield 2-
mercapto-pteridine-4-ol (2) and 2-mercapto-6,7-di-
1
2,13
5
. Conclusion
methyl-pteridin-4-ol (3), respectively.
In this paper, we have described pteridine compounds as
potential anticancer agents and identified analogues in
particular 4, 5, 11 and 24 that can be novel templates
for lead optimization purpose in cancer chemotherapy.
Furthermore, pteridines form covalent hydrate adducts
with water and in equilibrium with the unsolvated ad-
6.3. 2-(Quinolin-2-ylmethylsulfanyl)-pteridin-4-ol (4)
A solution of 2-mercapto-pteridine-4-ol (2, 0.9 g,
5.0 mmol), 2-(chloromethyl)quinoline (1.07 g, 5.0 mmol)
3
and NaOH (0.08 g, 2.0 mmol) in methanol (50 cm )
were stirred for 12 h at room temperature. The

3516
P. M. S. Chauhan et al. / Bioorg. Med. Chem. 13 (2005) 3513–3518
separated solid was recrystallized from methanol to give
the title compound (0.55 g, 37%) as a light yellow solid
(0.8 g, 5.0 mmol) and NaOH (0.08 g, 2.0 mmol) in
methanol (50 cm ) was stirred for 16 h at room tempera-
3
(
Found: C, 54.79; H, 2.91; N, 20.32. C H N OSÆ
ture. The precipitated solid was recrystallized from
methanol to give the title compound (1.2 g, 71%) as a
yellow solid (Found: C, 50.51; H, 3.87; N, 22.23.
C H N OSÆ2H O requires: C, 51.33; H, 3.76; N,
1
6
11
5
1
2
1
.5H O requires C, 55.18; H, 3.18; N, 20.10%); mp
08–210 °C; mmax (Nujol)/cm 1250, 1380, 1460, 1590,
2
À1
680 (C@N); d (300 MHz, DMSO-d ) 4.65 (2H, s,
H
6
16 14
6
2
À1
C(10)H ), 7.45 (1H, d, C(12)H), 7.60–7.85 (2H, m,
C(15)H, C(16)H), 7.85 (1H, d, C(17)H), 8.00 (1H, d,
C(14)H), 8.25 (1H, d, C(13)H), 8.40 (1H, d, C(7)H),
22.44%); mp > 320 °C; m
(Nujol)/cm
3100–3300
2
max
(OH, NH), 2900 (CH), 1680 (C@N); dH (300 MHz,
DMSO-d ) 2.45 (6H, br s, C(9)H , C(10)H ), 4.45 (2H,
s, C(12)H ), 7.15 (2H, m, C(16)H, C(17)H), 7.45 (2H,
6
3
3
8
.75 (1H, d, C(6)H); dC (75 MHz, DMSO-d ) 37.97
6
2
(
1
(
1
C-10), 122.88 (C-4a), 127.44 (C-12), 127.96 (C-15),
29.01 (C-13a), 129.55 (C-14), 130.87 (C-17), 133.10
C-16), 137.92 (C-13), 141.37 (C-6), 148.21 (C-7),
49.54 (C-17a), 157.59 (C-11), 161.06 (C-8a), 171.57
m, C(15)H, C(18)H); dC (75 MHz, DMSO-d ) 22.62
6
(C-9), 23.53 (C-10), 29.03 (C-12), 116.0 (C-4a), 119.0
(C-18), 122.68 (C-15), 129.8 (C-16) (C-17), 138.0 (C-
18a), 140 (C-14a), 149.139 (C-13), 153.83 (C-7), 155.90
(C-6), 157.54 (C-8a), 170.84 (C-4), 171.48 (C-2);
+
(
C-4), 173.106 (C-2); m/z (ES) M (322.3).
+
2+
m/z (ES) M (339.4), M (340.3).
6.4. 6,7-Dimethyl-2-(quinolin-2-ylmethylsulfanyl)-
pteridin-4-ol (5)
6.7. 1-(4-Bromo-phenyl)-2-(4-hydroxy-6,7-dimethyl-
pteridin-2-ylsulfanyl)-ethanone (8)
Compound 5 was prepared as described before to give
the title compound (3, 0.8 g, 57.2%) as a light yellow
solid (Found: C, 56.12; H, 3.72; N, 18.48. C H N OSÆ
A solution of 2-mercapto-pteridine 4-ol (2, 0.9 g,
5.0 mmol), 4-bromophenacylbromide (1.38 g, 5.0 mmol)
1
8
15
5
3
and NaOH (0.08 g, 2.0 mmol) in methanol (50 cm ) was
2
2
1
H OC requires C, 56.05; H, 3.92; N, 18.16%); mp 215–
(Nujol)/cm , 1174, 1296, 1376, 1489, 1495,
521, 1549, 1652, 2338, 2361, 3648; dH (300 MHz,
2
À1
17 °C; m
stirred for 12 h at room temperature. The solid thus sep-
arated was recrystallized from methanol, to give the title
compound (0.7 g, 37%) as a yellow solid (Found: C,
40.96; H, 2.19; N, 13.93. C H BrN O SÆ2H O requires
max
DMSO-d ) 2.60 (6H, s, C(9)H , C(10)H ), 4.60 (2H, s,
C(12)H ), 7.45 (1H, d, C(14)H), 7.60–7.80 (2H, m,
6
3
3
2
14
9
4
2
2
C(17)H, C(18)H), 7.85 (1H, d, C(19)H), 8.00 (1H, d,
C(16)H), 8.25 (1H, d, C(15)H); dC (75 MHz, DMSO-
d6) 22.59 (C-9), 23.56 (C-10), 37.89 (C-12), 122.82 (C-
C, 40.69; H, 2.19; N, 13.65%); mp 180–183 °C; m
(Nu-
max
À1
jol)/cm 1652 (C@N), 1700 (CO); dH (300 MHz,
DMSO-d ) 5.21 (2H, s, C(10)H ), 8.25 (2H, d, C(13)H,
6
2
4
1
1
a), 127.35 (C-14), 127.95 (C-17), 128.98 (C-15a),
29.61 (C-16), 129.74 (C-19), 130.78 (C-18), 137.83 (C-
5), 148.23 (C-7), 149.07 (C-6), 155.90 (C-19a), 157.66
C(17)H), 8.45 (2H, d, C(14)H, C(16)H); dC (75 MHz,
DMSO-d ) 38.93 (C-10), 128.51 (C-4a), 131.69 (C-13),
6
(C-17), 132.97 (C-14), (C-16), 133.42 (C-12), 136.54
(C-15), 141.07 (C-7), 149.09 (C-6), 157.63 (C-8a),
170.85 (C-4), 172.11 (C-2), 195.87 (C-11); m/z (ES)
(C-13), 166.28 (C-8a), 171.11 (C-4), 171.58 (C-2); m/z
(ES) M (350.3), M (351.4).
+
2+
+
2+
+3
M (377.2), M (379.1), M (381.3).
6.5. 2-(1H-Benzimidazol-2-ylmethylsulfanyl)-pteridin-
4-ol (6)
6.8. 2-(4-Bromo-1-benzoyl-methylsulfanyl)-6,7-dimethyl-
pteridine-4-ol (9)
A solution of 2-mercapto-pteridine-4-ol (2, 0.9 g,
5
5
.0 mmol),
2-(chloromethyl)benzimidazole
(0.8 g,
.0 mmol) and NaOH (0.08 g, 2.0 mmol) in methanol
Compound 9 was prepared as described before from 3 to
give the title compound (61.6%) as a yellow solid
(Found: C, 42.87; H, 2.90; N, 12.74. C H BrN O SÆ
3
(
50 cm ) was stirred for 16 h at room temperature. The
1
6
13
4
2
solvent was removed under reduced pressure and the
crude product was recrystallized from methanol to give
the title compound (0.8 g, 51.6%) as a yellow solid
2.5H O requires C, 42.68; H, 2.90; N, 12.44%); mp
2
À1
228–231 °C (dec); m
(Nujol)/cm 1170 (CO), 1652
max
À1
(CN) cm ; d (300 MHz, DMSO-d ) 2.45 (6H, d s,
H
6
(
Found: C, 49.51; H, 4.02; N, 25.19. C H N OSÆ
C(10)H , C(9)H ), 4.85 (2H, s, C(12)H ), 7.8 (2H, d,
C(15) H, C(19) H), 8.5 (2H, d, C(16) H, C(18) H); m/z
(ES) M (405.2), M (407.2), M (409.2).
1
4
10
6
3 3 2
1
2
1
.5H O requires C, 49.84; H, 4.18; N, 24.91%); mp
10–214 °C; m
2
À1
+
2+
+3
(Nujol)/cm 3200–3400 (OH, NH),
680 (C@N), d (300 MHz, DMSO-d ) 4.81 (2H, s,
max
H
6
C(10)H ), 7.0–7.25 (2H, m, C(14)H, C(15)H), 7.45
2
(
(
6.9. 2-(3,5-Dimethyl-isoxazol-4-ylmethylsulfanyl)-
pteridin-4-ol (10)
2H, m, C(13)H, C(16)H), 8.65 (1H, d, C(7)H), 8.85
1H, d, C(6)H); dC (75 MHz, DMSO-d ) 29.09 (C-10),
6
1
1
1
8
16.02 (C-4a), 122.8 (C-16), 133.50 (C-13), 139.98 (C-
4), 142.14 (C-15), 142.27 (C-12a), 149.73 (C-16a),
51.21 (C-7), 152.97 (C-11), 157.20 (C-6), 168.82 (C-
A solution of 2-mercapto-pteridine-4-ol (2, 0.9 g,
5.0 mmol),
(0.72 g, 5.0 mmol) and NaOH (0.08 g, 2.0 mmol) in
3,5-dimethyl-4-(chlomethyl)
isoxazol
+
3
methanol (50 cm ) was stirred for 16 h at room temper-
a), 169.78 (C-4), 177.45 (C-2); m/z (ES) M (311.2).
ature. The solid thus separated was recrystallized from
methanol to give the title compound (0.8 g, 55.5%) as
a light yellow solid (Found: C, 46.65; H, 3.71; N,
6.6. 2-(1H-Benzimidazol-2-ylmethylsulfanyl)-6,7-dimeth-
yl-pteridin- 4-ol (7)
2
2.64. C H N O SÆH O requires C, 46.89; H, 3.60;
12 11 5 2 2
À1
(Nujol)/cm 1457,
max
A solution of 2-mercapto-6,7-dimethyl-pteridin-4-ol (3,
5.0 mmol),
N, 22.78%); mp 249–253 °C; m
1377, 1680 (C@N), 2724; dH (300 MHz; DMSO-d6)
1
.04 g,
2-(chloromethyl)benzimidazole

P. M. S. Chauhan et al. / Bioorg. Med. Chem. 13 (2005) 3513–3518
3517
2
.45 (3H, s, C(17)H ), 2.8 (3H, s, C(16)H ), 4.42 (2H, s,
3
6.13. 2-Hydroxy-4-mercapto-5,6-diaminopyrimidine (15)
3
C(10)H ), 8.85 (1H, d, C(7)H), 9.12 (1H, d, C(6)H), dC
2
(
(
75 MHz; DMSO-d ) 10.93 (C-17), 12.23 (C-16), 23.28
C-10), 112.22 (C-4a), 133.43 (C-11), 142.26 (C-15),
2,4-Dihydroxy-5,6-diaminopyrimidine (14) (2.0 g, 14.0
mmol) and phosphorus pentasulfide (7.0 g, mmol) were
6
3
refluxed in pyridine (100 cm ) for 3 h. The solvent was
1
1
M
50.12 (C-7), 156.52 (C-6), 160.74 (C-8a), 166.84 (C-
2), 167.62 (C-4), 167.80 (C-2); m/z (ES) M (289.2),
+
removed under reduced pressure and the residue dis-
solved in the minimum amount of dilute sulfuric acid.
Upon standing in the refrigerator crystals precipitated
and were filtered and dried under vacuum to give com-
1
+
(290.2).
6
6
.10. 2-(3,5-Dimethyl-isoxazol-4-ylmethylsulfanyl)-
,7-dimethyl-pteridin-4-ol (11)
1
2
pound (15) (1.54 g, 70%) as beige solid, d (75 MHz,
C
DMSO); 102.5 (C ), 146.4 (C-6), 147.1 (C-2), 174.6 (C-
4).
5
Compound 11 was prepared as described before from 3
to give the title compound (1.1 g, 56%) as a yellow solid
(
Found: C, 46.57; H, 4.20; N, 19.37. C H N O SÆ
6.14. 2-Hydroxy-4-mercapto-6,7-dimethylpteridine (19)
1
4
15
5
2
2
2
1
.5H O requires C, 46.40; H, 4.17; N, 19.32%); mp
20–224 °C; mmax (Nujol)/cm 1298, 1400, 1489, 1520,
2
À1
2-Hydroxy-4-mercapto-5,6-diaminopyrimidine
(15)
3
539, 1554, 1635, 1652, 2849, 2975; d (300 MHz;
(3.0 g, 19.0 mmol) and 2,3-butadione (2.0 cm ,
1.2 equiv, 22.8 mmol) were refluxed in methanol
(50 cm ) for 4.0 h. The solution was cooled and part of
H
DMSO-d ), 2.24 (3H, s, C(19)H ), 2.45 (9H, m,
C(18)H ), C(9)H , C(10)H , 4.11 (2H, s, C(12)H ); d
6
3
3
3
3
3
2
C
1
1
(
(
(
75 MHz; DMSO-d ) 10.90 (C-19), 12.12 (C-18), 22.56
6
C-9), 23.05 (C-10), 23.62 (C-12), 112.75 (C-4a), 129.53
C-13), 149.20 (C-17), 155.75 (C-7), 157.79 (C-6),
the solvent removed to give compound (19) (2.18 g,
56%) as a beige/brown solid, dH (300 MHz, DMSO)
3.39 (6H, br s, C(9)H , C(10)H ); d (75 MHz, DMSO)
3
3
C
1
2
60.76 (C-8a), 167.76 (C-14), 170.95 (C-4), 171.46 (C-
); m/z (ES) M (317.3).
21.32 (C-10), 22.33 (C-9), 127.91 (C-4a), 144.12 (C-6),
147.91 (C-2), 149.62 (C-8a), 158.82 (C-7), 190.83 (C-4).
+
6
.11. 2-(2-Bromo-ethylsulfanyl)-pteridin-4-ol (12)
6.15. 2,4-Diamino-6,7-dimethylpteridine (20)
A solution of 2-mercapto-pteridine-4-ol (2, 0.9 g,
.0 mmol), 1,2-dibromoethane (1.4 g, 5.0 mmol) and
NaOH (0.08 g, 2.0 mmol) in methanol (50 cm ) was
stirred for 12 h at room temperature. The precipitated
solid was recrystallized from DMF, to give the title
compound (0.7 g, 48.2%) as a light yellow solid, mp
Commercially available 2,4,5,6-tetraaminopyrimidine
(16) (5.0 g, 21.0 mmol) and 2,3-butadione (2.76 cm ,
3
5
3
1.5 equiv, 31 mmol) were refluxed in methanol
(100 cm ). After 3.5 h the solution was cooled and a
brown solid filtered and dried under vacuum to give
3
1
1
compound (20) (3.17 g, 79%); dH (300 MHz, DMSO)
3.10 (3H, s, C(10)H ), 2.51 (3H, s, C(9)H ); d
C
2
C H BrN OS requires C, 33.46; H, 2.46; N, 10.51%);
95 °C (Found: C, 33.52; H, 2.50; N, 10.44.
3
3
(75 MHz, DMSO) 21.62 (C-9), 22.64 (C-10), 119.32
(C-4a), 144.61 (C-6), 150.92 (C-4), 155.74 (C-8a),
160.82 (C-7),163.05 (C-2).
8
7
4
À1
mmax (Nujol)/cm , 1041, 1377, 1461, 1540, 1578,
696, 2900; dH (300 MHz; DMSO-d ) 3.85 (2H, t,
1
C(10)H , J = 9.2 Hz), 4.45 (2H, t, C(11)H , J =
6
2
2
9
(
.2 Hz), 8.65 (1H, d, C(7)H), 8.85 (1H, d, C(6)H); dC
75 MHz; DMSO-d6) 27.85 (C-10), 49.98 (C-11),
6.16. 2,4-Dimercapto-6,7-dimethylpteridine (21)
1
8
M
32.51 (C-4a), 138.54 (C-7), 144.17 (C-6), 151.08 (C-
a), 158.67 (C-4), 166.79 (C-2); m/z (ES) M (287),
2,4-Dimercapto-5,6-diaminopyrimidine (17) (5.0 g,
28.7 mmol) and 2,3-butadione (3.77 cm , 1.5 equiv,
+
3
2
+
4+
(289), M (291).
3
43.1 mmol) were refluxed in methanol (100 cm ) for
3
.5 h. The solution was cooled and a brown solid filtered
1
1
6
.12. 2-(Pyrrolidin-1-yl-ethylsulfanyl)-pteridin-4-ol (13)
and dried under vacuum to yield compound (21)
4.32 g, 68%); dH (300 MHz, DMSO) 2.51 (3H, s,
C(9)H ), 3.34 (3H, s, C(10)H ); d (75 MHz, DMSO)
(
A reaction mixture of 12 (0.287 g, 1.0 mmol), pyrrol-
idine (0.142 g, 2.0 mmol) and K CO (0.20 g) in DMF
(
3
3
C
21.62 (C-9), 22.43 (C-10), 130.61 (C-4a), 142.54 (C-6),
151.42 (C-8a), 159.71 (C-7), 172.32 (C-4), 187.51 (C-2).
2
3
3
15 cm ) were heated for 12 h. The reaction mixture
was filtered and concentrated and the crude product
recrystallized from methanol to give the title compound
6.17. 4-(2-Hydroxy-ethylamino)-6,7-dimethyl-1H-pteri-
din-2-one (23)
(
C, 51.85; H, 5.48; N, 25.38. C H N OS requires C,
0.20 g, 72%) as a yellow solid, mp 150–152 °C (Found:
1
2
15
5
À1
5
1
2
1.97; H, 5.45; N, 25.25%); mmax (Nujol)/cm 1398,
436, 1506, 1528, 1554, 1635, 1652, 1684, 1699, 2361,
2-Hydroxy-4-mercapto-6,7-dimethylpteridine (19, 0.5 g,
2.4 mmol) was dissolved in hot dimethylformamide
3
3
361, 3628; dH (300 MHz; DMSO-d ) 1.25–1.45 (4 H,
(DMF) (20 cm ) and ethanolamine (0.2 cm , 1.5 equiv,
3.6 mmol) was added and the mixture refluxed for 5 h.
The solution was cooled and left in the refrigerator to
give the title compound (0.33 g, 60%) as a brown solid,
mp 273–275 °C (Found: C, 51.14; H, 5.48; N, 29.68.
C H N O requires C, 51.06; H, 5.57; N, 29.77%);
6
m, C(14)H , C(15)H ), 2.85–3.25 (8H, m, C(10)H
C(11)H , C(13)H , C(16)H ), 7.88 (1H, d, C(7)H), 8.88
2
2
2
2
2
2
(
1H, d, C(6)H); dC (75 MHz; DMSO-d ) 25.14 (C-14),
6
2
6.02 (C-15), 46.04 (C-10), 47.80 (C-11), (C-13)
C-16),130.75 (C-4a), 138.54 (C-7),149.83 (C-6), 156.8
(
(
(
1
0
13
5
2
+
À1
C-8a), 158.67 (C-4), 167.51 (C-2); m/z (ES) M
278.4).
mmax (Nujol)/cm 1552, 1595, 1650 (C@N), 3383 (O–
H); dH (300 MHz, DMSO) 3.33 (6H, s, C(9)H3,

3518
P. M. S. Chauhan et al. / Bioorg. Med. Chem. 13 (2005) 3513–3518
C(10)H ), 3.49 (2H, br s, C(12)H ), 3.54 (2H, br s,
3
solid, mp 307 °C (dec) (Found: C, 46.91; H, 3.56; N,
2
C(13)H ); d (75 MHz, DMSO) 21.1 (C-9), 22.24 (C-
25.36. C H N O S requires C, 46.98; H, 3.64; N,
1584, 1675 (C@N); dH
2
C
13 12
6
3
À1
1
0), 42.81 (C-12), 59.13 (C-13), 118.64 (C-4a), 146.78
C-6), 156.05 (C-7), 158.24 (C-4),160.34 (C-2); m/z
25.29%); mmax (Nujol)/cm
(300 MHz, DMSO) 2.60 (6H, s, C(10)H , C(9)H ) 3.9
(
(
3
3
1
+
ES) M (236).
(2H, s, C(12)H ); dC (75 MHz, DMSO) 21.64 (C-9),
2
2
2.52 (C-10), 30.54 (C-12), 98.56 (C-18), 129.02 (C-
6.18. 2-(2-Amino-6,7-dimethyl-pteridin-4-ylamino)-
ethanol (24)
14a), 148.44 (C-13), 151.62 (C-15), 154.64 (C-4),
155.33 (C-7), 156.51 (C-6), 164.46 (C-8a), 169.38 (C-2),
1
1
+
69.67 (C-17); m/z (ES) M (333).
Commercially available 2,4-diamino-6,7-dimethylpter-
idine (20, 0.5 g, 2.6 mmol) was dissolved in hot dimeth-
3
ylformamide (DMF) (30 cm ) and ethanolamine
(
Acknowledgements
3
0.25 cm , 1.2 equiv, 3.4 mmol) was added and the mix-
ture refluxed for 5 h. The solution was cooled and left in
the refrigerator to give the title compound (0.38 g, 77%)
as a beige solid, mp 258–260 °C (Found: C, 51.17; H,
Both of us (P.M.S.C. and C.J.A.M.) are highly thankful
to Pfizer for their financial support and to the NIH,
USA for anticancer screening. We are also thankful to
Ms. Anu Agarwal for her help in the preparation of
the manuscript.
6
.16; N, 35.76. C H N O requires C, 51.28; H, 6.08;
10 14 6
À1
N, 35.84%); mmax (Nujol)/cm
225 (O–H), 3348 (N–H); dH (300 MHz, DMSO) 3.42
6H, s, C(10)H , C(10)H ), 3.54 (2H, br s, C(13)H ),
1593, 1658 (C@N),
3
(
3
3
2
3
.59 (2H, br s, C(12)H ); dC (75 MHz, DMSO) 21.44
References and notes
2
(
(
1
C-9), 22.82 (C-10), 42.74 (C-12), 59.52 (C-13), 119.71
C-4a), 145.36 (C-8a), 154.42 (C-6), 158.91 (C-7),
1. (a) Kidwai, M.; Venkataramanan, R.; Mohan, R.; Sapra,
P. Curr. Med. Chem. 2002, 9, 1209–1228; (b) Beattie, J. F.;
Breault, G. A.; Ellston, R. P. A.; Green, S.; Jewsbury, P.
J.; Midgley, C. J.; Naven, R. T.; Minshull, C. A.; Pauptit,
R. A.; Tucker, J. A.; Pease, J. E. Bioorg. Med. Chem. Lett.
1
60.62 (C-4), 162.64 (C-2); m/z (ES) M (235).
+
6.19. 2-(2-Mercapto-6,7-dimethyl-pteridin-4-ylamino)-
ethanol (25)
2003, 14, 2955–2960.
. (a) Khaled, M. A.; Morin, R. D.; Benington, F.; Daugh-
ery, J. P. Cancer Chemother. Pharmacol. 1984, 13, 73–74;
2
2,4-Dimercapto-6,7-dimethylpteridine (21, 0.5 g, 2.2
mmol) was dissolved in hot dimethylformamide
(b) Suster, D. C.; Tarnauceanu, E.; Ionescu, D.; Dobre,
V.; Niculescu-Duvaz, I. J. Med. Chem. 1978, 21, 1162–
1165.
3. Berridge, M. J. Nature 1993, 361, 315–325.
3
3
(
2
DMF) (30 cm ) and ethanolamine (0.2 cm , 1.3 equiv,
.8 mmol) was added and the mixture refluxed for 5 h.
The solution was cooled and left in the refrigerator to
give the title compound (0.24 g, 43%) as an orange/
brown solid, mp 175–177 °C (Found: C, 47.71; H,
4. Bertino, J. R. O. J. Clin. Oncol. 1993, 11, 5–14.
. Schaweitzer, B. I.; Dicker, A. P.; Bertino, J. R. FASEB J.
990, 4, 2441–2452.
5
1
5
5
.16; N, 27.78. C H N OS requires C, 47.79; H,
10 13 5
.21; N, 27.87%); mmax (Nujol)/cm 1560 (C@N), 3175
À1
6. Piper, J. R.; Johnson, C. A.; Maddry, J. A.; Malik, N. D.;
McGuire, J. J.; Otter, G. M.; Sirotnak, F. M. J. Med.
Chem. 1993, 36, 4161.
(O–H), 3350 (N–H); dH (300 MHz, DMSO) 2.60 (6H,
s, C(10)H3, C(9)H ), 3.50 (2H, br s, C(13)H ), 3.62
3
2
7
. Gibson, W.; Boyle, F. T.; Bisset, G. M. F. J. Med. Chem.
1996, 39, 73–85.
(
2H, br s, C(12)H ); d (75 MHz, DMSO) 21.42 (C-9),
2 C
2
1
2
2.81 (C-10), 44.22 (C-12), 61.02 (C-13), 145.25 (C-4a),
51.03 (C-8a), 157.28 (C-6), 161.01 (C-4), 183.04 (C-7),
00.01 (C-2); m/z (ES) M (252), MÀSH (218).
8
. Boulton, A. J.; Mckillop, A. Compr. Heterocyclic Chem.
1984, 3, 232–263.
1
+
9. Alley, M. C.; Scudiero, D. A.; Monks, P. A.; Hursey,
M. L.; Czerwinski, M. J.; Fine, D. L.; Abbott, B. J.;
Mayo, J. G.; Shoemaker, R. H.; Boyd, M. R. Cancer Res.
988, 48, 589–601.
0. Grever, M. R.; Schepartz, S. A.; Chabner, B. A. Semin.
Oncol. 1992, 19, 622–638.
1. Boyd, M. R.; Paull, K. D. Drug Dev. Res. 1995, 34, 91–
09.
2. Albert, A.; Brown, D. J.; Cheeseman, G. J. Chem. Soc.
952, 4219–4232.
6.20. 6-(6,7-Dimethyl-4-oxo-3,4dihydro-pteridin-2-yl-
sulfanylmethyl)-1H-pyrimidine-2,4-dione (26)
1
1
1
1
2
-Mercapto-4-hydroxy-6,7-dimethylpteridine (22, 1.0 g,
4
oxide (20 cm ) and 2-(chloromethyl)uracil (0.92 g,
1
.8 mmol) was dissolved in methanolic sodium hydr-
1
3
.2 equiv, 5.7 mmol) was added and the mixture stirred
1
for 16 h. The solid was filtered and recrystallized from
DMF to give the title compound (0.93 g, 60%) as a beige
13. Levin, G.; Kalmus, A.; Bergmann, F. J. Org. Chem. 1960,
25, 1752–1754.