Synthesis of 2-amino-4-oxo-5-substitutedbenzylthiopyrrolo[2,3-d]- pyrimidines as potential inhibitors of thymidylate synthase [1]

Article abstract of DOI:10.1002/jhet.5570420127

A series of ten novel 2-amino-4-oxo-5-[(substitutedbenzyl)thio]pyrrolo[2,3- d]pyrimidines 2-11 were synthesized as potential inhibitors of thymidylate synthase and as antitumor agents. The analogues contain various electron withdrawing and electron donati

Full text of DOI:10.1002/jhet.5570420127

Jan-Feb 2005
Synthesis of 2-Amino-4-oxo-5-substitutedbenzylthiopyrrolo[2,3-d]-
165
pyrimidines as Potential Inhibitors of Thymidylate Synthase [1]
*
Aleem Gangjee [a], Hiteshkumar D. Jain [a], Jaclyn Phan [a] and Roy L. Kisliuk [b]
[
a] Division of Medicinal Chemistry, Graduate School of Pharmaceutical Sciences, Duquesne University,
Pittsburgh, Pennsylvania 15282 [b] Department of Biochemistry, Tufts University School of Medicine,
Boston, Massachusetts 02111
Received August 13, 2004
A series of ten novel 2-amino-4-oxo-5-[(substitutedbenzyl)thio]pyrrolo[2,3-d]pyrimidines 2-11 were syn-
thesized as potential inhibitors of thymidylate synthase and as antitumor agents. The analogues contain var-
ious electron withdrawing and electron donating substituents on the benzylsulfanyl ring of the side chains
and were synthesized from the key intermediate 2-amino-4-oxo-6-methylpyrrolo[2,3-d]pyrimidine, 14.
Appropriately substituted benzyl mercaptans were appended to the 5-position of 14 via an oxidative addition
reaction using iodine, ethanol and water. The compounds were evaluated against human, Escherichia coli
and Toxoplasma gondii thymidylate synthase and against human, Escherichia coli and Toxoplasma gondii
dihydrofolate reductase. The most potent inhibitor, (6) which has a 4'-methoxy substituent on the side chain,
has an IC50=25 µM against human thymidylate synthase. Contrary to analogues of general structure 1, elec-
tron donating or electron withdrawing substituents on the side chain of 2-11 had little or no influence on the
human thymidylate synthase inhibitory activity.
J. Heterocyclic Chem., 42, 165 (2005).
Introduction.
thymidylate synthase is an attractive goal for the develop-
ment of antitumor agents [3,4].
Thymidylate synthase catalyzes the reductive methyla-
tion of 2'-deoxyuridine-5'-monophosphate to 2'-deoxy-
thymidine-5'-monophosphate utilizing 5,10-methylenete-
trahydrofolate as the source of the methyl group as well as
the reductant [2]. This step represents the sole de novo
source of 2'-deoxythymidine-5'-monophosphate and hence
inhibition of thymidylate synthase, in the absence of sal-
vage, leads to "thymineless death". Thus inhibition of
Several thymidylate synthase inhibitors are currently
undergoing clinical trials and some of them are clinically
used as antitumor agents (Figure 1). Notable among these
are ZD1694 [5] and LY231514 [6]. ZD1694 has been
approved in Europe as an antitumor agent. LY231514 in
combination with cisplatin has recently been approved for
the treatment of malignant pleural mesothelioma. Classical
antifolates such as PDDF [7], ZD1694 and LY231514 have

1
66
A. Gangjee, H. D. Jain, J. Phan and R. L. Kisliuk
Vol. 42
a benzoyl-L-glutamic acid side chain which often makes
them substrates for the enzyme folylpoly-γ-glutamate syn-
thetase (FPGS). Folylpoly-γ-glutamate synthetase cat-
alyzes the formation of poly-γ-glutamates which lead to
high intracellular concentrations of these antitumor agents
and increases thymidylate synthase inhibitory activity for
certain antifolates (ZD1694 and LY231514). Although
polyglutamation of some antifolates is necessary for cyto-
toxicity, it is also responsible for toxicity to host cells.
Additionally, to gain access into the cell, classical antifo-
lates depend on a reduced folate carrier system, the impair-
ment of which can lead to drug resistance [8]. These prob-
lems, associated with classical antifolates can be overcome
by nonclassical lipophilic analogues which lack the γ-glu-
tamate moiety. Such analogues would passively diffuse
into cells and would not depend on folylpoly-γ-glutamate
synthetase for their potency [8].
sterically restrict the rotation of the 5-position side-chain
so that it adopts the most favorable conformation for bind-
ing to thymidylate synthase. Molecular modeling using
Sybyl 6.8 [13] and superimposition of compounds 2-11
onto the ternary complex of Escherichia coli TS-FdUMP-
AG337 [14] indicates that the pyrrolo[2,3-d]pyrimidine
with a 6-methyl moiety mimics the 6-methyl of the quina-
zoline of AG337 and, as reported previously by Gangjee et
al. [11,12] for compounds 1a-c, provides potent thymidy-
late synthase inhibition. Thus we elected to retain the 6-
methyl group in the design of compounds 2-11 as
inhibitors of thymidylate synthase.
The key intermediate in the synthesis of analogues 2-11
was the 2-amino-4-oxo-6-methylpyrrolo[2,3-d]pyrimi-
dine, 14 (Scheme 1), to which various side chains could be
conveniently appended. Compound 14 was obtained in a
one step reaction by the addition of chloroacetone, 13, to a
solution of 2,6-diamino-4-hydroxypyrimidine, 12, in
sodium acetate and water as reported previously [12].
Analogues 2-11 were obtained by oxidative addition of
appropriately substituted benzyl mercaptans to the 5-posi-
tion of 14 (Scheme 1). Thus heating a mixture of 14 with
the substituted benzyl mercaptans in a mixture of
ethanol/water (2:1) with two equivalents of iodine at
reflux for a period of 4-6 hours afforded the desired target
compounds 2-11 in reasonably good yields without the
necessity of protecting the 2-amino group of 14, as
reported previously [12]. This method had the advantages
Based on the structure of AG337 (thymitaq), the first
nonclassical thymidylate synthase inhibitor to reach clini-
cal trials [10], we have previously reported compounds 1a-
c as potent inhibitors of human thymidylate synthase
[
11,12]. Compounds 1b-c, which have electron withdraw-
ing nitro- and chloro- substituents in either the 3'- and/or
'- position of the phenyl ring were much more potent than
4
the unsubstituted phenyl or analogues containing methoxy
substituents. Compounds 1b-c are more potent than the
classical, clinically used analogs ZD1694 and LY231514
against human thymidylate synthase.
Molecular modeling using SYBYL 6.8 [13] and super-
imposition of the 6-5 pyrrolo[2,3-d]pyrimidine onto the 6-
-quinazoline (AG337) indicated that the smaller 6-5 sys-
over our previously reported method [12] of shorter reac-
tion times (4-6 hours vs 16 hours) and not requiring pro-
tecting and deprotecting the 2-amino group, which occurs
in poor yields (20-30%) over two steps. Another signifi-
cant modification of the reported method [12] was the use
of sodium thiosulfate to remove the excess iodine. Further,
evaporation of the solvent under reduced pressure afforded
a residue which was purified by column chromatography
to afford the target compounds 2-11 in 25-46% yields. The
6
tem has its 5- and 6-atoms closer to the pyrimidine ring
than the 5- and 6-atoms of the quinazoline in AG337. In
compounds 1a-c the sulfur bridge is directly attached to
the 5-position of the pyrrolo[2,3-d]pyrimidine, thus short-
ening the distance between the pyrimidine ring and the
side chain substituent as compared to the quinazolines. We
reasoned that increasing the length of the bridge, as in
compounds 2-11, by one atom may compensate for the
contraction of the B-ring in 6-5 systems. Webber et al. [9]
suggested that the 6-methyl moiety of AG337 serves two
important functions, one being its ability to make
hydrophobic contact with a Trptophan (Trp80) of
Escherichia coli thymidylate synthase and the other was to
1
H nmr of 2-11 indicated the absence of the 5-aromatic
proton as well as the presence of methylene protons
between 3.90-3.99 ppm and the appropriate aromatic pro-
tons of the side-chain phenyl ring, confirmed that substitu-
tion had occurred.
Compounds 2-11 were evaluated [15,16] as inhibitors of
Escherichia coli and human thymidylate synthase along

Jan-Feb 2005
Synthesis of 2-Amino-4-oxo-5-substitutedbenzylthiopyrrolo[2,3-d]pyrimidines
167
with PDDF, ZD1694, and LY231514 and as inhibitors of
Escherichia coli and human dihydrofolate reductase along
with methotrexate. The IC50 values were all >20 µM, and
within 10 minutes. The reaction mixture was heated with stirring
at 100 °C for an additional 4 hours, cooled to 0 °C, and filtered to
afford 1.15 g (70%) of 14 as a slight pink colored solid: mp >260
1
°
C (dec) tlc; R 0.37 (chloroform/methanol 4:1, silica gel);
H
f
2
-11 were 10-1000 times less potent than PDDF, ZD1694
nmr (Me SO-d ): δ 2.14(s, 3 H, 6-CH ), 5.83(s, 1 H, 5-CH),
2
6
3
or LY231514 against the TS enzymes and 1000 times less
potent than methotrexate against the DHFR enzymes.
Surprisingly, the most potent compound in this series has
an electron donating 4'-methoxy (IC50 = 25 µM) substitu-
tion in the side chain. Additionally, the presence of elec-
tron donating or electron withdrawing substituents in the
side chain had little or no influence on human thymidylate
synthase inhibition. On the basis of the analogues reported
in this study, along with the previous reports of Gangjee et
al. [11,12], it appears that for 5-substituted pyrrolo[2,3-
d]pyrimidines the 6-methyl moiety is conducive for activ-
ity when the bridge at the 5-position is a single sulfur
atom. However, if the bridge is homologated to a two-atom
S8-C9 chain with a 6-methyl substituent, the analogue
loses activity as compared with the single-atom sulfur
bridge (compare 1a-c [11,12] with 2-11).
5
.98(bs, 2 H, 2-NH ), 10.15(bs, 1 H, 7-NH), 10.78 (bs, 1 H, 3-
2
NH).
2
-Amino-6-methyl-5-benzylthio-3,4-dihydro-4-oxo-7H-pyrrolo-
[2,3-d]pyrimidine (2).
To a solution of 14 (1.0 g, 6.0 mmol) in a mixture of
ethanol/water (2:1, 90 ml) was added benzyl mercaptan (1.5 g,
2.0 mmol) and the reaction mixture was heated to 100-110 °C.
1
Iodine (3.0 g, 12.0 mmol) was added and the heating continued
with stirring for a total of 4 hours. To this mixture was added an
excess of sodium thiosulfate and the solvent was removed under
reduced pressure. To the residue was added 10 g of silica gel and
50 ml of methanol, and the mixture was evaporated to dryness to
afford a plug which was loaded on top of a silica gel column. The
column was eluted with a gradient of 1-5% methanol in chloro-
form and fractions containing the desired spot (tlc) were pooled
and evaporated to dryness. The resulting residue was recrystal-
lized from methanol, filtered and dried to yield 0.7 g (40%) of 2:
mp 278-282 °C; tlc R 0.50 (chloroform/methanol 5:1, with 2
f
1
EXPERIMENTAL
drops of ammonium hydroxide); H nmr (DMSO-d ): δ 1.82 (s,
6
3
4
1
H, 6-CH ), 2.23 (s, 3H, 6-CH ), 3.95 (s, 2H, -CH ), 6.07 (s, 2H,
3 3 2
-NH ), 7.04-7.25 (m, 5H, C H ), 10.23 (s, 1H, 7-NH), 10.95 (s,
All evaporations were carried out in vacuo with a rotary evap-
orator. Analytical samples were dried in vacuo (0.2 Torr) in an
Abderhalden drying apparatus over phosphorous pentoxide.
Melting points were determined on a Fisher-Johns melting point
apparatus and are uncorrected. Nuclear magnetic resonance spec-
2
6 5
H, 3-NH).
Anal. Calcd. for C14H14N4OS•1.0H2O: C, 58.72; H, 4.93; N,
19.57; S, 11.20. Found C, 55.25; H, 5.30; N, 18.41; S, 10.53.
2
7
-Amino-6-methyl-5-(2'-methylbenzyl)thio-3,4-dihydro-4-oxo-
1
tra for proton ( H nmr) were recorded on a Bruker WH-300 (300
MHz) spectrometer. Data was accumulated by 16K size with a
H-pyrrolo[2,3-d]pyrimidine (3).
Compound 3 was synthesized as described for 2: Yield 41%;
0
.5 s delay time and 70° tip angle. The chemical shift values are
expressed in ppm (parts per million) relative to tetramethylsilane
as internal standard; s = singlet, d = doublet, dd = doublet of dou-
blet, t = triplet, q = quartet, m = multiplet, bs = broad singlet. The
relative integrals of peak areas agreed with those expected for the
assigned structures. High resolution mass spectra (HRMS) were
recorded on a VG-7070E-HF instrument. Thin layer chromatog-
raphy (tlc) was performed on POLYGRAM Sil G/UV254 silica
gel plates with fluorescent indicator, and the spots were visual-
ized under 254 and 366 nm illumination. Proportions of solvents
used for thin layer chromatography are by volume. Elemental
analyses were performed by Atlantic Microlabs Inc., Norcoss,
GA. Analytical results indicated by element symbols are within
mp 268-270 °C; tlc Rf 0.49 (chloroform/methanol 5:1, with 2
drops of ammonium hydroxide); H nmr (DMSO-d6): δ 1.80 (s,
1
3H, 6-CH3), 2.33 (s, 3H, 2'-CH3), 3.94 (s, 2H, -CH2), 6.07 (s, 2H,
4-NH2), 6.81-6.83 (d, 1H, C6H4), 6.97 (m, 1H, C6H4), 7.07 (d,
2H, C6H4), 10.22 (s, 1H, 7-NH), 10.94 (s, 1H, 3-NH).
Anal. Calcd. for C15H16N4OS: C, 59.98; H, 5.37; N, 18.65; S,
10.67. Found C, 59.80; H, 5.37; N, 18.58; S, 10.70.
2
7
-Amino-6-methyl-5-(2'-chlorobenzyl)thio-3,4-dihydro-4-oxo-
H-pyrrolo[2,3-d]pyrimidine (4).
Compound 4 was synthesized as described for 2: Yield 43%;
mp 269-270.5 °C; tlc Rf 0.45 (chloroform/methanol 5:1, with 2
drops of ammonium hydroxide); H nmr (DMSO-d6): δ 1.72 (s,
1
±
0.4% of the calculated values. Fractional moles of water or
organic solvents frequently found in some analytical samples of
antifolates were not removed in spite of 24-48 hours of drying in
vacuo and were confirmed where possible by their presence in
3H, 6-CH3), 3.99 (s, 2H, -CH2), 6.08 (s, 2H, 4-NH2), 6.81-6.84
(d, 1H, C6H4), 7.09 (t, 1H, C6H4), 7.17-7.19 (t, 1H, C6H4), 7.35-
7.38 (d, 1H, C6H4), 10.25 (s, 1H, 7-NH), 10.95 (s, 1H, 3-NH).
1
the H nmr spectrum. All solvents and chemicals were purchased
Anal. Calcd. for C14H13N OSCl: C, 52.42; H, 4.08; N, 17.46;
4
from Aldrich Chemical Co. and Fisher Scientific and were used
as received.
S, 9.99; Cl, 11.05. Found C, 52.28; H, 4.14; N, 17.58; S, 10.09;
Cl, 11.00.
2
-Amino-6-methyl-3,4-dihydro-4-oxo-7H-pyrrolo[2,3-d]pyrimi-
2-Amino-6-methyl-5-(4'-methylbenzyl)thio-3,4-dihydro-4-oxo-
dine (14).
7H-pyrrolo[2,3-d]pyrimidine (5).
A suspension of 2,6-diamino-4-hydroxypyrimidine (12) (1.26
g, 10 mmol) in 25 ml of water containing sodium acetate (0.82 g,
0 mmol) was heated to 100 °C until it formed a clear solution.
Compound 5 was synthesized as described for 2: Yield 46%; mp
244-245 °C; tlc R 0.49 (chloroform/methanol 5:1, with 2 drops of
f
1
1
ammonium hydroxide); H nmr (DMSO-d ): δ 1.85 (s, 3H, 6-CH ),
6
3
Chloroacetone (13) (0.79 ml, 10 mmol) was added to this solu-
2.22 (s, 3H, 4'-CH ), 3.92 (s, 2H, -CH ), 6.06 (s, 2H, 4-NH ), 6.93-
3 2 2
tion in one lot, following which a precipitate began to form
7.00 (m, 4H, C H ), 10.22 (s, 1H, 7-NH), 10.94 (s, 1H, 3-NH).
6 4

168
A. Gangjee, H. D. Jain, J. Phan and R. L. Kisliuk
Vol. 42
Anal. Calcd. for C15H16N OS•0.8H O: C, 59.98; H, 5.37; N,
Compound 11 was synthesized as described for 2: Yield 30%;
4
2
1
2
8.65; S, 10.67. Found C, 57.23; H, 5.64; N, 17.80; S, 10.19.
mp 274-276.5 °C; tlc R 0.50 (chloroform/methanol 5:1, with 2
f
1
drops of ammonium hydroxide); H nmr (DMSO-d ): δ 1.84 (s,
6
-Amino-6-methyl-5-(4'-methoxybenzyl)thio-3,4-dihydro-4-
3
H, 6-CH ), 3.95 (s, 2H, -CH ), 6.10 (s, 2H, 4-NH ), 6.97-7.00
3 2 2
oxo-7H-pyrrolo[2,3-d]pyrimidine (6).
(
d, 1H, C H ), 7.25 (s, 1H, C H ), 7.42-7.45 (d, 1H, C H ),
6 3 6 3 6 3
Compound 6 was synthesized as described for 2: Yield 33%;
10.27 (s, 1H, 7-NH), 11.02 (s, 1H, 3-NH).
Anal. Calcd. for C14H12N OSCl •1.0H O: C, 47.33; H, 3.40;
mp 243-245 °C; tlc R 0.50 (chloroform/methanol 5:1, with 2
drops of ammonium hydroxide); H nmr (DMSO-d ): δ 1.86 (s,
3
2
1
f
4
2
2
1
6
N, 15.77; S, 9.03; Cl, 19.96. Found C, 45.05; H, 3.78; N, 15.01;
S, 8.59; Cl, 19.00.
H, 6-CH ), 3.68 (s, 3H, 4'-OCH ), 3.90 (s, 2H, -CH ), 6.07 (s,
3 3 2
H, 4-NH ), 6.74-6.76 (d, 2H, C H ), 6.97-6.99 (d, 2H, C H ),
2
6
4
6 4
Acknowledgment.
0.22 (s, 1H, 7-NH), 10.95 (s, 1H, 3-NH). HRMS (EI): m/e cal-
+
culated for (M ) C 5H N O S 316.0994; found m/z = 316.0990.
1
16
4
2
This work was supported, in part, by NIH Grants from the
National Cancer Institute CA98850 (A.G.) and CA10914
2
7
-Amino-6-methyl-5-(4'-chlorobenzyl)thio-3,4-dihydro-4-oxo-
H-pyrrolo[2,3-d]pyrimidine (7).
(
R.L.K.). JP was Sponsored by the American Association of
Colleges of Pharmacy and funded by a grant from the Merck
Company Foundation through the Merck Research Scholar
Program.
Compound 7 was synthesized as described for 2: Yield 28%;
mp 274-275.5 °C; tlc R 0.49 (chloroform/methanol 5:1, with 2
f
1
drops of ammonium hydroxide); H nmr (DMSO-d ): δ 1.82 (s,
6
3
H, 6-CH ), 3.94 (s, 2H, -CH ), 6.08 (s, 2H, 4-NH ), 7.03-7.05
3 2 2
REFERENCES AND NOTES
(d, 2H, C H ), 7.22-7.25 (d, 2H, C H ), 10.24 (s, 1H, 7-NH),
6 4 6 4
1
0.96 (s, 1H, 3-NH).
Anal. Calcd. for C14H13N OSCl•0.6H O: C, 52.42; H, 4.08;
*
To whom correspondence should be addressed. E-mail:
gangjee@duq.edu; Phone: 412-396-6070; Fax: 412-396-5593.
1] Presented in part at the 2004 American Association of
4
2
N, 17.46; S, 9.99; Cl, 11.05. Found C, 50.71; H, 4.32; N, 16.90;
S, 9.67; Cl, 10.69.
[
Colleges of Pharmacy Annual Meeting, Salt Lake City, Utah, July
12-14, 2004.
2
7
-Amino-6-methyl-5-(4'-fluorobenzyl)thio-3,4-dihydro-4-oxo-
H-pyrrolo[2,3-d]pyrimidine (8).
[2] C. W. Carreras and D. V. Santi, Annu. Rev. Biochem., 64,
7
21 (1995).
Compound 8 was synthesized as described for 2: Yield 30%;
[3] K. T. Douglas, Med. Res. Rev., 7, 441 (1987).
4] E. M. Berman and L. M. Werbel, J. Med. Chem., 34, 479
mp 264-266 °C; tlc R 0.50 (chloroform/methanol 5:1, with 2
f
[
1
drops of ammonium hydroxide); H nmr (DMSO-d ): δ 1.83 (s,
6
(1991).
[5] A. L. Jackman, G. A. Taylor, W. Gibson, R. Kimbell, M.
Brown, A. H. Calvert, I. R. Judson and L. R. Hughes, Cancer Res.,
51, 5579 (1991).
3
(
H, 6-CH ), 3.94 (s, 2H, -CH ), 6.08 (s, 2H, 4-NH ), 7.00-7.06
3 2 2
m, 4H, C H ), 10.24 (s, 1H, 7-NH), 10.96 (s, 1H, 3-NH).
6 4
Anal. Calcd. for C14H13N OSF•1.0H O: C, 55.25; H, 4.31; N,
4
2
1
9
8.41; S, 10.54; F, 6.24. Found C, 52.16; H, 4.69; N, 17.38; S,
.95; F, 5.89.
[6] E. C. Taylor, D. Kuhnt, C. Shih, S. M. Rinzel, G. B.
Grindey, J. Barredo, M. Jannatipour and R. A. Moran, J. Med. Chem.,
3
5, 4450 (1992).
7] T. R. Jones, A. H. Calvert, A. L. Jackman, S. J. Brown, M.
Jones and K. R. Harrap, Eur. J. Cancer, 17, 11 (1981).
8] G. Jansen, in Antifolate Drugs in Cancer Therapy, A. L.
2
7
-Amino-6-methyl-5-(4'-bromobenzyl)thio-3,4-dihydro-4-oxo-
[
H-pyrrolo[2,3-d]pyrimidine (9).
[
Compound 9 was synthesized as described for 2: Yield 36%;
Jackman, ed, Humana Press, Totowa, New Jersey, 1999, pp. 293-321.
[9] S. E. Webber, T. M. Bleckman, J. Attard, J. G. Deal, V.
Katherdekar, K. M. Welsh, S. Webber, C. A. Janson, D. A. Matthews,
W. W. Smith, S. T. Freer, S. R. Jordan, R. J. Bacquet, E. F. Howland,
C. J. L. Booth, R. W. Ward, S. M. Hermann, J. White, C. A. Morse, J.
A. Hilliard and C. A. Bartlett, J. Med. Chem., 36, 733 (1993).
mp 254-256 °C; tlc R 0.48 (chloroform/methanol 5:1, with 2
f
1
drops of ammonium hydroxide); H nmr (DMSO-d ): δ 1.81 (s,
6
3
H, 6-CH ), 3.92 (s, 2H, -CH ), 6.09 (s, 2H, 4-NH ), 6.96-6.99
3 2 2
(
1
d, 2H, C H ), 7.36-7.38 (d, 2H, C H ), 10.25 (s, 1H, 7-NH),
0.97 (s, 1H, 3-NH). HRMS (EI): m/e calculated for (M )
6 4 6 4
+
C14H13N OSBr 363.9993; found m/z = 363.9980
4
[10] P. J. Creaven, L. Pendyala, N. J. Meropol, N. J.
Clendeninn, E. Y. Wu, G. M. Loewen, A. Proefrock, A. Johnston and
M. Dixon, Cancer Chemother. Pharmacol., 41, 167 (1998).
2
-Amino-6-methyl-5-(2',4'-dichlorobenzyl)thio-3,4-dihydro-4-
oxo-7H-pyrrolo[2,3-d]pyrimidine (10).
[11] A. Gangjee, R. Devraj, J. J. McGuire and R. L. Kisliuk, J.
Compound 10 was synthesized as described for 2: Yield 25%;
Med. Chem., 38, 4495 (1995).
mp 274-275.5 °C; tlc R 0.50 (chloroform/methanol 5:1, with 2
drops of NH OH); H nmr (DMSO-d ): δ 1.74 (s, 3H, 6-CH ),
3
7
[12] A. Gangjee, F. Mavandadi, R. L. Kisliuk, J. J. McGuire
and S. F. Queener, J. Med. Chem., 39, 4563 (1996).
[13] Tripos Associates, Inc., 1699 S. Hanely Road, Suite 303,
St. Louis, MO 63144.
f
1
4
6
3
.98 (s, 2H, -CH ), 6.09 (s, 2H, 4-NH ), 6.79-6.81 (d, 1H, C H ),
2 2 6 3
.18-7.21 (d, 1H, C H ), 7.52 (s, 1H, C H ), 10.27 (s, 1H, 7-
6
3
6 3
NH), 10.98 (s, 1H, 3-NH).
Anal. Calcd. for C14H12N OSCl : C, 47.33; H, 3.40; N, 15.77;
S, 9.03; Cl, 19.96. Found C, 47.27; H, 3.49; N, 15.75; S, 9.01; Cl,
[14] Protein Data Bank, Brookhaven National Laboratory, for
ecTS-5-FdUMP-CB3717 and SYBYL 6.4 for superimposing
AG337. See also ref 8.
4
2
[15] R. L. Kisliuk, D. Strumpf, Y. Gaumont, R. P. Leary and L.
1
9.85.
Plante, J. Med. Chem., 20, 1531 (1977).
[16] A. J., Wahba and M. Friedkin, J. Biol. Chem., 237, 3794
(1962).
2
-Amino-6-methyl-5-(3',4'-dichlorobenzyl)thio-3,4-dihydro-4-
oxo-7H-pyrrolo[2,3-d]pyrimidine(11).