Synthesis of 2,6-diamino-5-[(2-substituted phenylamino)ethyl]pyrimidin- 4(3H)-one as inhibitors of folate metabolizing enzymes

Article abstract of DOI:10.1002/jhet.5570430615

A series of eleven novel 2,6-diamino-5-[(2-substituted phenylamino)ethyl] pyrimidin-4(3H)-one derivatives were synthesized as potential inhibitors of dihydrofolate reductase (DHFR) and thymidylate synthase (TS). The synthesis of analogues 2a-f, 3a and 3e

Full text of DOI:10.1002/jhet.5570430615

Nov-Dec 2006
1523
Synthesis of 2,6-Diamino-5-[(2-substituted phenylamino)ethyl]pyrimidin-
4(3H)-one as Inhibitors of Folate Metabolizing Enzymes [1a,b]
Aleem Gangjee* [a], Ying Wang [a], Sherry F. Queener [b], and Roy L. Kisliuk [c]
[a] Division of Medicinal Chemistry, Graduate School of Pharmaceutical Sciences, Duquesne University,
Pittsburgh, Pennsylvania 15282.
[b] Department of Pharmacology and Toxicology, Indiana University School of Medicine,
Indianapolis, Indiana, 46202.
[c] Department of Biochemistry, Tufts University School of Medicine, Boston, Massachusetts 02111
Received January 12, 2006
R'
N
NH2
steps
NH2
N
R
R
H2N
N
H
O
A
series of eleven novel 2,6-diamino-5-[(2-substituted phenylamino)ethyl]pyrimidin-4(3H)-one
derivatives were synthesized as potential inhibitors of dihydrofolate reductase (DHFR) and thymidylate
synthase (TS). The synthesis of analogues 2a-f, 3a and 3e was achieved via an improved method.
Commercially available anilines 12a-f were used as starting materials which on reaction with
chloroacetaldehyde followed by cyanoacetate and cyclocondensation with guanidine afforded 2,6-diamino-
5-[(2-substituted phenylamino)ethyl]pyrimidin-4(3H)-one 2a-f in three steps. The N-methyl analogues 3a-
3e were prepared by reductive methylation. These compounds were evaluated against dihydrofolate
reductase from Escherichia coli, Toxoplasma gondii, Pneumocystis carinii, human, and rat liver. Few
compounds were marginally active against dihydrofolate reductase. The most potent inhibitor, (2c) which
has a 1-naphthyl substituent on the side chain, has an IC50 = 150 μM and 9.1 μM against Escherichia coli
and Toxoplasma gondii DHFR, respectively.
J. Heterocyclic Chem., 43, 1523 (2006).
Introduction.
Several classical antifolates have been reported in the
literature as inhibitors of dihydrofolate reductase and
thymidylate synthase [5]. The disadvantage of classical
compounds is that they require active transport to enter
cells. Cells that lack these transport mechanisms, such as
bacterial and protozoa cells are not susceptible to the
action of classical antifolates. In an attempt to overcome
these problems, nonclassical, lipophilic antifolates were
developed [6]. The treatment of Pneumocystis carinii and
Toxoplasma gondii infections with nonclassical
antifolates takes advantages of the fact that these
organisms are permeable to lipophilic, nonclassical
antifolates and, unlike mammalian cells, lack a carrier-
mediated active transport mechanism for the uptake of
classical folates and antifolates with polar glutamate side
chains [7]. Thus, host tissues can be selectively rescued
from the toxic effects by a reduced folate, typically
leucovorin, which is taken up only by host cells [7,8].
The clinically used lipophilic agents trimethoprim and
pyrimethamine, used for Pneumocystis carinii and
Toxoplasma gondii infections, respectively, are selective
but weak inhibitors of dihydrofolate reductase from
Pneumocystis carinii and Toxoplasma gondii and must be
used with sulfonamides to provide synergistic effects
[7,9]. Trimetrexate and piritrexim, which are 100-10,000
times more potent than trimethoprim or pyrimethamine
against dihydrofolate reductase from Pneumocystis carinii
Inhibition of folate metabolism has long been an
attractive biochemical target [2,3]. Opportunistic
infections with Pneumocystis carinii and Toxoplasma
gondii associated with loss of cell-mediated immunity
remains among the principal causes of morbidity and
mortality in patients with acquired immunodeficiency
syndrome (AIDS) in the United States [4]. A therapeutic
approach is to treat these infections via dihydrofolate
reductase inhibitors.
OMe
OMe
OMe
NH2
NH2 CH3
OMe
OMe
N
N
N
H
H2N
N
H2N
N
OMe
trimethoprim (TMP)
trimetrexate (TMQ)
MeO
NH2
MeO
NH2 CH3
N
N
H
N
N
H
H2N
N
H2N
N
N
OMe
OMe
piritrexim (PTX)
1
Figure 1

1524
A. Gangjee, Y. Wang, S. F. Queener and R. L. Kisliuk
Vol 43
and Toxoplasma gondii, are also potent inhibitors of
dihydrofolate reductase from mammalian sources [10,11].
Gangjee et al. [12] simplified the structure of
trimetrexate and designed a series of monocyclic
nonclassical trimethoprim analogues bearing a C-C bridge
in the side chain, as potent and selective pathogen
dihydrofolate reductase inhibitors (Figure 1). Among
these, compound 1 was the most potent and had an
activity profile (potency and selectivity) against
Pneumocystis carinii dihydrofolate reductase similar to
trimethoprim. Molecular modeling using SYBYL 6.8 [13]
and superimposition of 1 onto trimetrexate indicated that
the distance between the pyrimidine ring and side chain
substituted phenyl ring in 1 was shorter than that in
trimetrexate. Increasing the length of the bridge by one
atom could afford optimal chain length for enzyme
interaction similar to 1. In this report we synthesized
compounds 2a-f and 3a-e with a C-C-N side chain in an
attempt to improve the potency and selectivity of 1
against Pneumocystis carinii dihydrofolate reductase and
Toxoplasma gondii dihydrofolate reductase (Figure 2).
In addition, it was also of interest to combine both
dihydrofolate reductase and thymidylate synthase inhibitory
activity in one nonclassical antifolate molecule. Gangjee et
al. [14] recently reported the successful design, synthesis
and evaluation of dual DHFR-TS inhibitors. Such dual
inhibitors could act at two different sites, i.e., dihydrofolate
reductase and thymidylate synthase, and could possess
“combination chemotherapy” potential in a single molecule
without the pharmacokinetic disadvantages of two separate
entities. Since the 2,4-diamino portion of the pyrimidine
NH2
CH3
N
NH2
H
N
N
N
R
R
H2N
N
H
O
H2N
N
H
O
3a: R = H
3b: R = 4-Cl
3c: R = 2,3-C4H4
3d: R = 3,4-C4H4
3e: R = 3,4,5-triOMe
2a: R = H
2b: R = 4-Cl
2c: R = 2,3-C4H4
2d: R = 3,4-C4H4
2e: R = 3,4,5-triOMe
2f: R = 2,5-diOMe
Figure 2
Due to a complete lack of selectivity, these drugs have
to be used along with leucovorin for host rescue.
However, leucovorin is expensive and the side effects due
to a lack of effective rescue sometimes require cessation
of therapy. Thus the development of selective and potent
nonclassical, lipophilic antifolates is a desirable goal.
NH2
O
180°
N
NH
H2N
H2N
N
H
O
N
NH2
2,4-diamino mode
(binding to DHFR)
2-amino-4-oxo mode
(binding to TS)
Figure 3
Scheme 1
NH2
NaOMe, EtOH,
NCCH2CO2C2H5
C2H5O
OC2H5
C2H5O
C2H5O
guanidine, EtOH
N2, reflux
Ac2O, pyridine
90 °C, N2
CO2C2H5
CN
N
OC2H5
C2H5O
Cl
H2N
N
H
O
5
4
6
N(COCH3)2
N
CHO
H3COCHN
N
H
O
N(COCH3)2
OC2H5
H2O, 100 °C
8
N
OC2H5
O
H3COCHN
N
H
O
NH
7
N
H3COCHN
N
COCH3
H2O, rt, 6 d
9
NH2
OMe
OMe
O
NHCOCH3
OMe
H
N
H
N
2,5-dimethoxyaniline
AcOH, BH3 ·NMe3
NaOH, 60 °C
N
NH
H3COCHN
N
OH
N
H2N
N
H
O
N
H3COCHN
N
H
O
COCH3
OMe
11
2f
10

Nov-Dec 2006
Synthesis of 2,6-Diamino-5-[(2-substituted phenylamino)ethyl]pyrimidin-4(3H)-one
1525
ring is the preferred binding mode for dihydrofolate
reductase (e.g. trimethoprim) [15] and 2-amino-4-oxo
portion of the pyrimidine ring is the preferred binding
mode for TS [e.g. 2-amino-4-oxo-N10-propargyl-5,8-
dideazafolate (PDDF)] [16], compounds 2a-f and 3a-e, as
potential nonclassical dual inhibitors of dihydrofolate
reductase and thymidylate synthase could adopt both "2,4-
diamino” mode as well as "2-amino-4-oxo" mode via
rotation of the C2-NH2 bond by 180 °C, using the 6-oxo to
mimic the 4-oxo group of PDDF (Figure 3).
pyrrole ring was formed in this process instead of the
desired aldehyde 8. H nmr of 9 indicated the absence
1
of the 5-formylmethyl protons as well as the presence
of two vinyl protons (doublet, J = 3.6 Hz) between
6.55-7.49 ppm, confirmed that cyclization and elim-
ination had occurred simultaneously to form the
pyrrolo[2,3-d]pyrimidine. However, treatment of 7 in
water at ambient temperature afforded hydrolysis of the
acetal, deacetylation, and cyclization to give 10 in 32%
yield. Reaction of 10 with 2,5-dimethoxyaniline in the
presence of acetic acid and borane-trimethylamine gave
the desired diacetylated analogue 11 in 9% yield.
Deprotection of 12 was readily accomplished with hot
1 N sodium hydroxide to give 2f in 36% yield.
Since the overall yield was low in the synthetic
sequence for 2f, a more efficient synthetic route was
developed for the target compounds (Scheme 2). Anilines
12a-f were condensed with 2-chloroacetaldehyde to afford
13a-f in 72-98% yields in the presence of borane-
trimethylamine and acetic acid at room temperature.
Intermediates 13a-f were then reacted with ethyl
cyanoacetate to afford 14a-f in 30-45% yields. Finally
14a-f were cyclocondensed with guanidine to give the
target compounds 2a-f in moderate yields. The N-methyl
analogues 3a and 3e were prepared from 2a and 2e via
reductive methylation using formaldehyde and sodium
Results and Discussion.
The initial synthetic strategy for 2a-f is shown in
Scheme 1. The synthesis commenced from the
commercially available 2-chloroacetaldehyde diethyl
acetal
4
and ethyl cyanoacetate using sodium
methoxide as base and a crystal of sodium iodide as
catalyst to afford ethyl 2-cyano-4,4-diethoxy-butyl-
anoate 5 using a modification of a literature procedure
[17]. Compound 5 condensed with guanidine in ethanol
to provide 2,6-diamino-5-(3,3-diethoxyethyl)pyrim-
idin-4(3H)-one 6 in 16% yield. The amino groups in 6
were protected by acetylation with acetic anhydride
and pyridine to give the triacetyl aminopyrimidine 7.
To deprotect the acetal, 7 was heated in water at 100
ºC. Interestingly, cyclized compound 9 with a stable
Scheme 2
NH
NH2
ClCH2CHO
Cl
CO2Et
CN
NH
NCCH2CO2Et, EtOH
R
R
R
NaOMe, NaI, DMF,
N2, 90-100 ºC
AcOH, BH3·NMe3
MeOH, rt, N2
12a-f
13a-f
14a-f
NH2
N
CH3
N
NH2
H
N
guanidine, EtOH
N2, 90-100 ºC
HCHO, NaCNBH3
CH3CN, rt
N
R
R
H2N
N
H
O
H2N
N
H
O
2a-f
3a, 3e
Scheme 3
CH3
NH
HCHO, NaBH(OAc)3
CH3CN, rt
NCCH2CO2Et, EtOH
Cl
N
R
Cl
NaOMe, NaI, DMF,
N2, 90-100 ºC
R
13b-d
15b-d
CH3
N
NH2
N
CH3
N
guanidine, EtOH
N2, 90-100 ºC
CO2Et
R
R
CN
H2N
N
H
O
3b-d
16b-d

1526
A. Gangjee, Y. Wang, S. F. Queener and R. L. Kisliuk
Vol 43
temperature for 20 minutes. The solvent was removed under
reduced pressure at 40 °C, and the residue was dissolved in
anhydrous DMF (10 ml). To this solution were added 2-
chloroacetaldehyde diethyl acetal (4, 4.10 g, 26.5 mmol) and a
crystal of NaI, and the mixture was protected with a drying tube
and stirred for 4 hours at 95 °C. The solution was cooled, poured
into ice water (15 ml), and extracted with ethyl ether (6 ꢁ 20
ml). The organic phase was washed with water (2 ꢁ 10 ml),
brine (10 ml), dried with Na2SO4, and filtered. The filtrate was
concentrated in vacuo to give 3.11 g (51%) of 5 as a pale brown
liquid and was used for next step without further purification.
cyanoborohydride in 44% and 47% yield, respectively.
Analogues 3b-d were synthesized via a slightly modified
sequence (Scheme 3). Methylation of 13b-d under
classical method provided 15a-f, which were converted to
the desired analogues 3b-d in two steps. The structures of
all target compounds 2a-f and 3a-e were confirmed by H
NMR and elemental analysis or high resolution mass
spectrum.
Compounds 2a-f and 3a-e were evaluated as inhibitors
of isolated dihydrofolate reductase against Escherichia
coli, Toxoplasma gondii, Pneumocystis carinii, human,
and rat liver along with trimetrexate (TMQ) and
trimethoprim (TMP). None of the target compounds
inhibited these enzymes at 24 μM except 2c for which the
IC50 values were 150 μM and 9.1 μM against Escherichia
coli and Toxoplasma gondii, respectively. This clearly
indicated that both C-C and C-C-N bridged 5-substituted
nonclassical monocyclic pyrimidine systems are not
conductive to dihydrofolate reductase inhibitory activity.
The inhibitory activity of these analogues against
thymidylate synthase will be reported in due course.
1
2,6-Diamino-5-(3,3-diethoxyethyl)pyrimidin-4(3H)-one (6).
To a solution of sodium methoxide (1.54 g, 27.16 mmol) in
anhydrous ethanol (20 ml) were added guanidine hydrochloride
(1.30 g, 13.58 mmol) and crude 5 (3.11 g, 13.58 mmol). The
mixture that resulted was refluxed at 95 °C for 2.5 hours, and
then further stirred at room temperature for 12 hours. To this
solution were added methanol (20 ml) and silica gel (10.0 g),
and the solvent evaporated. The silica gel plug obtained was
loaded on a silica gel column and eluted with CHCl3:MeOH (28-
30 % ammonia in methanol) (100:5). Fractions containing the
product (tlc) were pooled and the solvent evaporated to afford
0.55 g (17%) of 6 as a white solid, mp 185-187.5 °C (lit., [18]
1
187-189 °C); tlc Rf 0.44 (CHCl3:MeOH, 5:1); H nmr (DMSO-
EXPERIMENTAL
d6) ꢀ 1.07 (t, 6H, J = 7.1 Hz, CH3), 2.42 (d, 2H, J = 5.5 Hz,
CH2), 3.39 (m, 2H, OCH2), 3.59 (m, 2H, OCH2), 4.42 (t, 1H, J =
5.3 Hz, CH), 5.58 (s, 2H, NH2), 5.98 (s, 2H, NH2), 9.85 (s, 1H,
NH).
All evaporations were carried out in vacuo with a rotary
evaporator. Analytical samples were dried in vacuo (0.2 mmHg)
in an Abderhalden drying apparatus over P2O5 and ethanol at
reflux. Thin layer chromatography (tlc) was performed on silica
gel plates with fluorescent indicator. Spots were visualized by
UV light (254 and 365 nm). All analytical samples were
homogeneous on tlc in at least two different solvent systems.
Purification by column and flash chromatography was carried
out using Merck silica gel 60 (200-400 mesh). The amount
(weight) of silica gel for column chromatography was in the
range of 50-100 times the amount (weight) of the crude
compounds being separated. Columns were dry packed unless
specified otherwise. Solvent systems are reported as volume
percent mixture. Melting points were determined on a Mel-
Temp II melting point apparatus with a digital thermometer and
are uncorrected. 1H nmr spectra were recorded on a Bruker WH-
300 (300 MHz) nmr spectrometer. The chemical shift (ꢀ) values
are reported as parts per million (ppm) relative to tetramethyl-
silane as internal standard; s = singlet, d = doublet, t = triplet, q
= quartet, m = multiplet, bs = broad singlet. Elemental analyses
were performed by Atlantic Microlab, Inc., Norcross, GA.
Elemental compositions were within ± 0.4% of the calculated
values. Fractional moles of water or organic solvents frequently
found in some analytical samples of antifolates could not be
removed despite 24 h of drying in vacuum and were confirmed,
N-[4-Diacetylamino-5-(2,2-diethoxyethyl)-6-oxo-1,6-dihydro-
pyrimidin-2-yl)acetamide (7).
To a solution of 6 (0.30 g, 1.24 mmol) in anhydrous pyridine
(10 ml) was added acetic anhydride (1.32 ml, 13.97 mmol). The
reaction mixture was stirred at 90 °C under a nitrogen
atmosphere for 5 hours and then further stirred at room
temperature for 12 hours. The solution was evaporated in vacuo
to give an oil. To this residue were added methanol (20 ml) and
silica gel (5.0 g), and the solvent evaporated. The silica gel plug
obtained was loaded on a silica gel column and eluted with
CHCl3:MeOH (20:2). Fractions containing the product (tlc) were
pooled and the solvent evaporated to afford 0.27 g (59%) of 7 as
1
a pale yellow solid; tlc Rf 0.79 (CHCl3:MeOH, 5:1); H nmr
(DMSO-d6) ꢀ 1.07 (t, 6H, OCH2CH3), 2.14 (s, 3H, COCH3),
2.30 (s, 6H, COCH3), 2.64 (d, 2H, CH2), 3.43 (m, 2H, OCH2),
3.55 (m, 2H, OCH2), 4.77 (t, 1H, CH), 9.50 (bs, 1H, NHCO),
11.91 (bs, 1H, NH).
N-(7-Acetyl-4-oxo-4,5,6,7-tetrahydro-3H-pyrrolo[2,3-d]pyrim-
idin-2-yl)acetamide (9).
The triacetylated pyrimidinone 7 (0.18 g, 0.50 mmol) was
heated with water (5 ml) on a steam bath for 4 h. Water was
evaporated at 50 °C in vacuo to afford a residual oil. To this
residue were added methanol (8 ml) and silica gel (5.0 g), and
the solvent evaporated. The silica gel plug obtained was loaded
on a silica gel column and eluted with CHCl3:MeOH (a gradient
elution, 100:0.5 to 100:5). Fractions containing the product (tlc)
were pooled and the solvent evaporated to afford 0.057 g of 9
(23%) as a colorless oil; tlc Rf 0.72 (CHCl3:MeOH, 5:1); 1H nmr
(DMSO-d6) ꢀ 2.09 (s, 3H, NCOCH3), 2.26 (s, 3H, NCOCH3),
1
where possible, by their presence in the H nmr spectrum. All
solvents and chemicals were purchased from Aldrich Chemical
Co. and Fisher Scientific and were used as received.
2-Cyano-4,4-diethoxybutyric Acid Ethyl Ester (5).
To a solution of sodium methoxide (1.51 g, 26.5 mmol) in
anhydrous ethanol (10 ml) was added ethyl cyanoacetate (3.0 g,
26.5 mmol), and the reaction mixture was stirred at room

Nov-Dec 2006
Synthesis of 2,6-Diamino-5-[(2-substituted phenylamino)ethyl]pyrimidin-4(3H)-one
1527
6.55 (d, 1H, J = 3.6 Hz, CH), 7.49 (d, 1H, J = 3.6 Hz, CH),
11.80 (bs, 2H, NH and 2-NHCO).
Anal. Calcd for C14H19N5O3 • 0.4 H2O: C, 53.80, H, 6.39; N,
22.40. Found: C, 54.08; H, 6.14; N, 22.09.
(±)-N-(7-Acetyl-6-hydroxy-4-oxo-4,5,6,7-tetrahydro-3H-
pyrrolo[2,3-d]pyrimidin-2-yl]acetamide (10).
General Procedure for the Synthesis of Compounds 13a-f.
To a solution of the appropriate aniline (12a-f) in methanol
were added chloroacetaldehyde, acetic acid, and borane
trimethylamine. The mixture was stirred at room temperature
under nitrogen for 10-18 hours. If the reaction was not complete
(tlc) after 6 hours, an additional amount of acetic acid (0.5 eq),
chloroacetaldehyde (1.0 eq) and borane trimethylamine (1.0 eq)
were added, and the mixture was further stirred for 10-12 hours.
The pH of the solution was adjusted to 8 with conc. ammonium
hydroxide. To this solution was added silica gel and the solvent
evaporated. The silica gel plug obtained was loaded on a silica
gel column and eluted with ethyl acetate:hexanes (1:20).
Fractions containing the product (tlc) were pooled and
evaporated to afford the desired product.
A solution of the triacetylated pyrimidinone 7 (0.27 g, 0.73
mmol) in water (10 ml) was stirred at room temperature for 6
days. TLC showed that the starting material was still present
and there were two new spots. Water was evaporated at 50
°C in vacuo to afford a residual solid. To this residue were
added methanol (20 ml) and silica gel (10.0 g), and the
solvent evaporated. The silica gel plug obtained was loaded
on a silica gel column and eluted with CHCl3:MeOH (a
gradient elution, 100:0.5 to 100:5). Fractions containing the
product (tlc) were pooled and the solvent evaporated to
afford 0.07 g of 10 (32%) as a white solid; tlc Rf 0.52
(CHCl3:MeOH, 5:1); 1H nmr (DMSO-d6) ꢀ 2.15 (s, 3H,
NCOCH3), 2.49 (s, 3H, NCOCH3), 2.89-2.97 (q, 2H, CH2),
5.87 (t, 1H, CHOH), 6.55 (d, 1H, J = 5.9 Hz, OH), 11.61-
11.71 (bs, 2H, NH and 2-NHCO).
(2-Chloroethyl)phenylamine (13a).
Compound 13a was obtained from aniline 12a (3.0 g, 32.25
mmol), chloroacetaldehyde (4.89 ml, 38.50 mmol), borane
trimethylamine (4.71 g, 62.57 mmol) and acetic acid (0.27 ml,
4.70 mmol) by using the method described above to afford 4.91
N-{4-Acetylamino-5-[2-(2,5-dimethoxyphenylamino)ethyl]-6-
oxo-1,6-dihydro-pyrimidin-2-yl}acetamide (11).
g
(98%) of 13a as a yellow oil; tlc Rf 0.76 (ethyl
To a solution of 10 (69 mg, 0.27 mmol) in methanol (20 ml)
were added 2,5-dimethoxyaniline (45 mg, 0.30 mmol), borane
trimethylamine (41 mg, 0.54 mmol), and acetic acid (0.02 ml,
0.27 mmol). The resulting mixture was stirred at room
temperature for 12 hours. The pH of the solution was adjusted to
8 with conc. ammonium hydroxide in an ice bath. To this
solution was added silica gel (5.0 g) and the solvent evaporated.
The silica gel plug obtained was loaded on a silica gel column
and eluted with CHCl3:MeOH (a gradient elution, 100:0.5 to
100:3). Fractions containing the product (tlc) were pooled and
the solvent evaporated to afford 10 mg of 11 (9%) as a gray
acetate:hexanes, 1:2); 1H nmr (DMSO-d6) ꢀ 3.48 (t, 2H, NCH2),
3.80 (t, 2H, CH2Cl), 6.16 (t, 1H, NH), 6.52 (m, 3H, C6H5), 7.07
(m, 2H, C6H5).
(2-Chloroethyl)-(4-chlorophenyl)amine (13b).
Compound 13b was obtained from 4-chloroaniline 12b (4.0 g,
31.35 mmol), chloroacetaldehyde (4.75 ml, 36.62 mmol), borane
trimethylamine (6.87 g, 94.07 mmol) and acetic acid (0.30 ml,
5.22 mmol) by using the method described above to afford 5.06
g (85%) of 13b as a gray oil; tlc Rf 0.81 (ethyl acetate:hexanes,
1
1
1:2); H nmr (DMSO-d6): ꢀ 3.37 (t, 2H, NCH2), 3.68 (t, 2H,
solid, mp 215-217 °C; tlc Rf 0.79 (CHCl3:MeOH, 5:1); H nmr
CH2Cl), 6.05 (bs, 1H, NH), 6.60 (dd, 2H, C6H4), 7.09 (dd, 2H,
C6H4).
(DMSO-d6) ꢀ 2.05 (s, 3H, NCOCH3), 2.14 (s, 3H, NCOCH3),
2.57 (t, 2H, 7-CH2), 3.13 (t,, 2H, NCH2), 3.66 (s, 3H, OCH3),
3.69 (s, 3H, OCH3), 5.04 (t, 1H, 9-NH), 6.03 (dd, 1H, C6H3),
6.24 (d, 1H, J = 2.6 Hz, C6H3), 6.65 (d, 1H, J = 8.5 Hz, C6H3),
9.70 (s, 1H, NH), 11.54 (bs, 1H, NHCO), 11.85 (bs, 1H,
NHCO).
(2-Chloroethyl)naphthalen-1-yl-amine (13c).
Compound 13c was obtained from 1-aminonaphthalene 12c
(3.0 g, 20.98 mmol), chloroacetaldehyde (3.18 ml, 25.04 mmol),
borane trimethylamine (3.06 g, 40.66 mmol) and acetic acid
(0.36 ml, 6.27 mmol) by using the method described above to
afford 3.28 g (76%) of 13c as a red oil; tlc Rf 0.43 (ethyl
acetate:hexanes, 1:7); 1H nmr (DMSO-d6) ꢀ 3.61 (q, 2H, NCH2),
3.85 (t, 2H, J = 6.4 Hz, CH2Cl), 6.40 (t, 1H, J = 5.4 Hz, NH),
6.57 (d, 1H, J = 7.6 Hz, C10H7), 7.14 (d, 1H, J = 8.0 Hz, C10H7),
7.29 (t, 1H, C10H7), 7.43 (m, 2H, C10H7), 7.76 (d, 1H, C10H7),
8.13 (d, 1H, C10H7).
Anal. Calcd for C18H23N5O5: C, 55.52; H, 5.95; N, 17.98.
Found: C, 55.31; H, 5.78; N, 18.23.
2,6-Diamino-5-[2-(2,5-dimethoxyphenylamino)ethyl]pyrimidin-
4(3H)-one (2f).
A stirred solution of 11 (39 mg, 0.10 mmol) and 1 N aq.
NaOH (2 ml) was heated at 60 ºC for 10 hours and then stirred at
room temperature for 12 hours. The pH of the solution was
adjusted to 8 with 1 N HCl in an ice bath. To this solution was
added silica gel (2.0 g) and the solvent evaporated. The silica gel
plug obtained was loaded on a silica gel column and eluted with
CHCl3:MeOH:NH4OH (10:1:0.1). Fractions containing the
product (tlc) were pooled and the solvent evaporated to afford
11 mg of 2f (36%) as a white solid, mp 246-249 °C; tlc Rf 0.47
(2-Chloroethyl)naphthalen-2-yl-amine (13d).
Compound 13d was obtained from 2-aminonaphthalene 12d
(3.00 g, 20.97 mmol), chloroacetaldehyde (3.18 ml, 25.04
mmol), borane trimethylamine (3.06 g, 40.66 mmol) and acetic
acid (0.24 ml, 4.18 mmol) by using the method described above
to afford 3.89 g (90%) of 13d as a deep red oil; tlc Rf 0.63 (ethyl
acetate:hexanes, 1:2); 1H nmr (DMSO-d6) ꢀ 3.51 (q, 2H, NCH2),
3.80 (t, 2H, J = 6.4 Hz, CH2Cl), 6.19 (t, 1H, J = 5.7 Hz, NH),
6.79 (s, 1H, C10H7), 6.99 (t, 1H, C10H7), 7.11 (q, 1H, C10H7), 7.31
(t, 1H, C10H7), 7.61 (m, 3H, C10H7).
1
(CHCl3:MeOH, 5:1); H nmr (DMSO-d6) ꢀ 2.48 (m, 2H, CH2),
2.93 (m, 2H, NCH2), 3.64 (s, 3H, OMe), 3.67 (s, 3H, OMe), 5.02
(t, 1H, J = 5.1 Hz, NH), 5.84 (s, 2H, NH2), 5.97-6.02 (m, 3H,
C6H3 and NH2), 6.11 (d, 1H, J = 2.6 Hz, C6H3), 6.63 (d, 1H, J =
8.6 Hz, C6H3), 9.90 (s, 1H, NH).

1528
A. Gangjee, Y. Wang, S. F. Queener and R. L. Kisliuk
Vol 43
(2-Chloroethyl)-(3,4,5-trimethoxyphenyl)amine (13e).
cyanoacetate (1.76 ml, 16.09 mmol) and a crystal of NaI to
afford 0.89 g (35%) of 14c as a gray oil; tlc Rf 0.58 (ethyl
acetate:hexanes, 1:2); H nmr (DMSO-d6) ꢀ 1.16 (t, 3H, CH3),
2.27 (m, 2H, CH2), 3.16 (m, 2H, NCH2), 4.15 (m, 3H, CHCN
and COOCH2), 6.27 (t, 1H, J = 5.3 Hz, NH), 6.54 (d, 1H, J = 7.6
Hz, C10H7), 7.14 (d, 1H, J = 8.0 Hz, C10H7), 7.29 (t, 1H, C10H7),
7.43 (m, 2H, C10H7), 7.76 (d, 1H, J = 7.3 Hz, C10H7), 8.13 (d,
1H, J = 8.0 Hz, C10H7). HRMS (EI): Calculated for C17H18N2O2:
m/z = 282.3387. Found: m/z = 282.3374.
Compound 13e was obtained from 3,4,5-trimethoxyaniline
12e (4.11 g, 21.78 mmol), chloroacetaldehyde (3.30 ml, 25.98
mmol), borane trimethylamine (3.18 g, 42.24 mmol) and acetic
acid (0.24 ml, 4.18 mmol) by using the method described above
to afford 4.47 g (81%) of 13e as an oil; tlc Rf 0.42 (ethyl
1
1
acetate:hexanes, 1:2); H nmr (DMSO-d6): ꢀ 3.36 (m, 2H, N-
CH2), 3.45 (s, 2H, CH2Cl), 3.51 (s, 3H, 4-OMe), 3.69 (s, 6H,
3,5-diOMe), 5.6 (bs, 1H, NH), 5.89 (s, 2H, C6H2).
2-Cyano-3-(naphthalen-2-yl-amino)propionic Acid Ethyl Ester
(14d).
(2-Chloroethyl)-(2,5-dimethoxyphenyl)amine (13f).
Compound 13f was obtained from 2,5-dimethoxyaniline 12f
(2.75 g, 18.0 mmol), chloroacetaldehyde (3.43 ml, 27.0 mmol),
borane trimethylamine (2.71 g, 36.0 mmol) and acetic acid (0.24
ml, 4.18 mmol) by using method described above to afford 2.82
g (72%) of 13f as an oil; tlc Rf 0.68 (ethyl acetate:hexanes, 1:2);
1H nmr (DMSO-d6) ꢀ 3.44 (m, 2H, NCH2), 3.65 (s, 3H, OCH3),
3.79 (m, 5H, OCH3 and CH2Cl), 5.14 (t, 1H, J = 6.0 Hz, NH),
6.11 (d, 1H, C6H3), 6.23 (s, 1H, C6H3), 6.74 (dd, 1H, C6H3).
Compound 14d was obtained from intermediate 13d (0.80 g,
3.89 mmol), sodium methoxide (0.23 g, 4.28 mmol), ethyl
cyanoacetate (0.62 ml, 5.84 mmol) and a crystal of NaI to afford
0.35 g (32%) of 14d as a brown oil; tlc Rf 0.32 (ethyl
acetate:hexanes, 1:2); 1H nmr (DMSO-d6): ꢀ 1,23 (m, 3H, CH3),
2.22 (m, 2H, CH2), 3.28 (m, 2H, NCH2), 4.13-4.35 (m, 3H,
CHCN and COOCH2), 6.08 (t, 1H, NH), 6.75 (s, 1H, C10H7),
6.95 (dd, 1H, C10H7), 7.12 (t, 1H, C10H7), 7.31 (t, 1H, C10H7),
7.61 (q, 3H, C10H7).
General Procedure for Synthesis of Compounds 14a-f.
2-Cyano-3-(3,4,5-trimethoxyphenylamino)propionic Acid Ethyl
Ester (14e).
To a stirred solution of sodium methoxide in absolute ethanol
was added ethyl cyanoacetate. The resulting mixture was stirred
at room temperature for 5 minutes. The solvent was evaporated
in vacuo at 40 °C, and the residual white solid was dissolved in
dry DMF. To this solution were added the appropriate
intermediate 13a-f and a crystal of NaI, and the solution was
heated at 90 °C under nitrogen for 4 hours. The reaction mixture
was poured into water and extracted with methylene chloride.
The organic layer was washed with brine, dried over Na2SO4,
and concentrated in vacuo. The residue was purified by silica gel
column chromatography and eluted with ethyl acetate:hexanes
(1:10 to 1:5). Fractions containing the pure product (tlc) were
pooled, evaporated and immediately used for the next step.
Compound 14e was obtained from intermediate 13e (2.0 g,
8.15 mmol), sodium methoxide (0.48 g, 8.96 mmol), ethyl
cyanoacetate (1.13 ml, 10.60 mmol) and a crystal of NaI to
afford 2.13 g (45%) of 14e as a pale yellow oil; tlc Rf 0.64 (ethyl
1
acetate:hexanes, 2:1); H nmr (DMSO-d6) ꢀ 1.19 (t, 3H, CH3),
2.07 (m, 2H, CH2), 3.14 (m, 2H, N-CH2), 3.51 (s, 3H, 4'-OCH3),
3.70 (s, 6H, 3',5'-diOCH3), 4.02 (m, 2H, COOCH2), 4.20 (m, 1H,
CHCN), 5.58 (t, 1H, NH), 5.85 (s, 2H, C6H2).
2-Cyano-3-(2,5-dimethoxyphenylamino)propionic Acid Ethyl
Ester (14f).
Compound 14f was obtained from intermediate 13f (1.07 g,
4.96 mmol), sodium methoxide (0.27 g, 4.96 mmol), ethyl
cyanoacetate (0.80 ml, 7.44 mmol), and a crystal of NaI to
afford 0.58 g (40%) of 14f as a gray oil; tlc Rf 0.57 (ethyl
2-Cyano-3-phenylaminopropionic Acid Ethyl Ester (14a).
Compound 14a was obtained from intermediate 13a (1.0 g,
6.43 mmol), sodium methoxide (0.35 g, 6.43 mmol), ethyl
cyanoacetate (1.03 ml, 9.64 mmol) and a crystal of NaI to afford
0.44 g (30%) of 14a as a yellow oil; tlc Rf 0.57 (ethyl
1
acetate:hexanes, 1:2); H nmr (DMSO-d6) ꢀ 1.20 (t, 3H, CH3),
2.10 (m, 2H, CH2), 3.18 (m, 2H, NCH2), 3.65 (s, 3H, OMe), 3.68
(s, 3 H, OMe), 4.17 (m, 3H, COOCH2 and CHCN), 5.14 (t, 1H, J
= 6.1 Hz, NH), 6.06-6.12 (m, 2H, C6H3), 6.68 (d, 1H, J = 8.4 Hz,
C6H3).
1
acetate:hexanes, 1:2); H nmr (DMSO-d6) ꢀ 1.21 (t, 3H, CH3),
2.09 (m, 2H, CH2), 3.17 (q, 2H, N-CH2), 4.18 (m, 3H, CHCN
and COOCH2), 5.71 (t, 1H, NH), 6.57 (m, 3H, C6H5), 7.08 (t,
2H, C6H5).
General Procedure for the Synthesis of Compounds 2a-f.
3-(4-Chlorophenylamino)-2-cyanopropionic Acid Ethyl Ester
(14b).
To a solution of sodium methoxide in absolute ethanol was
added guanidine hydrochloride. The reaction mixture was stirred
at room temperature for 30 minutes, the appropriate intermediate
(14a-f) was added. The reaction mixture was stirred under
nitrogen at 95 °C for 2-4 hours and quenched by adding water.
To this solution was added silica gel and the solvent evaporated.
The silica gel plug obtained was loaded on a silica gel column
and eluted with CHCl3:MeOH:NH4OH (10:1:0.1). Fractions
containing the pure product (tlc) were pooled and evaporated to
afford the product.
Compound 14b was obtained from intermediate 13b (1.0 g,
5.26 mmol), sodium methoxide (0.31 g, 5.78 mmol), ethyl
cyanoacetate (0.84 ml, 7.89 mmol) and a crystal of NaI to afford
0.42 g (30%) of 14b as a pale brown oil; tlc Rf 0.45 (ethyl
1
acetate:hexanes, 1:2); H nmr (DMSO-d6) ꢀ 1.15 (t, 3H, CH3),
2.09 (m, 2H, CH2), 3.15 (m, 2H, NCH2), 4.12-4.29 (m, 3H,
CHCN and COOCH2), 5.95 (t, 1H, NH), 6.56 (d, 2H, C6H4),
7.10 (d, 2H, C6H4).
2-Cyano-3-(naphthalen-1-ylamino)propionic Acid Ethyl Ester
(14c).
2,6-Diamino-5-(2-phenylaminoethyl)pyrimidin-4(3H)-one (2a).
Compound 2a was synthesized from intermediate 14a (0.44 g,
1.90 mmol), sodium methoxide (0.64 g, 11.76 mmol) and
guanidine hydrochloride (1.09 g, 11.40 mmol) using the general
Compound 14c was obtained from intermediate 13c (1.84 g,
8.94 mmol), sodium methoxide (0.73 g, 13.41 mmol), ethyl

Nov-Dec 2006
Synthesis of 2,6-Diamino-5-[(2-substituted phenylamino)ethyl]pyrimidin-4(3H)-one
1529
procedure described above to afford 0.20 g (45%) of 2a as a
white solid, mp > 240 °C dec; tlc Rf 0.33 (CHCl3:MeOH, 5:1);
1H nmr (DMSO-d6) ꢀ 2.47 (t, 2H, CH2), 2.92 (m, 2H, NCH2),
5.47 (t, 1H, NH), 5.81 (s, 2H, NH2), 5.99 (s, 2H, NH2), 6.50 (m,
3H, C6H5), 7.04 (t, 2H, C6H5) 9.88 (s, 1H, NH).
Anal. Calcd for C15H21N5O4: C, 53.72; H, 6.31; N, 20.88.
Found: C, 53.84; H, 6.48; N, 20.67.
2,6-Diamino-5-[2-(2,5-dimethoxyphenylamino)ethyl]pyrimidin-
4(3H)-one (2f).
Compound 2f was synthesized from intermediate 14f (0.57 g,
1.95 mmol), sodium methoxide (1.14 g, 21.12 mmol) and
guanidine hydrochloride (1.89 g, 19.80 mmol) using the general
procedure described above to afford 0.16 g (28%) of 2f as a
white solid. The compound obtained was identical to that
synthesized using the alternative synthesis reported above.
Anal. Calcd for C12H15N5O: C, 58.76; H, 6.16; N, 28.30.
Found: C, 58.48; H, 6.06; N, 28.20.
2,6-Diamino-5-[2-(4-chlorophenylamino)ethyl]pyrimidin-4(3H)-
one (2b).
Compound 2b was synthesized from intermediate 14b (0.21
g, 0.77 mmol), sodium methoxide (0.27 g, 4.98 mmol) and
guanidine hydrochloride (0.52 g, 4.62 mmol) using the general
procedure described above to afford 0.10 g (48%) of 2b as a
white solid, mp > 250 °C dec; tlc Rf 0.35 (CHCl3:MeOH, 5:1);
1H nmr (DMSO-d6) ꢀ 2.45 (t, 2H, CH2), 2.89 (t, 2H, NCH2), 5.74
(s, 1H, NH), 5.82 (s, 2H, NH2), 5.99 (s, 2H, NH2), 6.52 (d, 2H,
C6H5), 7.04 (d, 2H, C6H5), 9.84 (s, 1H, NH).
General Procedure for Synthesis of Compounds 3a and 3e.
To a suspension of 2a or 2e in acetonitrile was added
formaldehyde, followed by sodium cyanoborohydride. The pH
of the resulting mixture was adjusted to 2-3 with conc. HCl.
Within 5 minutes, tlc (CHCl3:MeOH, 5:1, with a drop of
NH4OH) indicated the presence of a new spot and the starting
material was consumed in 30 minutes. This suspension, cooled
in an ice bath, was neutralized to pH 7-8 with conc. ammonium
hydroxide. Methanol was added to dissolve the precipitate
followed by silica gel and the solvent evaporated to afford a
silica gel plug. The silica gel plug obtained was loaded on a
silica gel column and eluted with CHCl3:MeOH:NH4OH
(100:10:0.1). Fractions containing the product (tlc) were pooled
and evaporated to afford the product.
Anal. Calcd for C12H14N5OCl•0.1 H2O: C, 51.20; H, 5.08; N,
24.88; Cl, 12.59. Found: C, 51.06; H, 5.00; N, 24.70; Cl, 12.61.
2,6-Diamino-5-[2-(naphthalen-1-yl-amino)ethyl]pyrimidin-
4(3H)-one (2c).
Compound 2c was synthesized from intermediate 14c (0.54 g,
1.92 mmol), sodium methoxide (0.15 g, 2.76 mmol) and
guanidine hydrochloride (0.22 g, 2.30 mmol) using the general
procedure described above to afford 0.35 g (10%) of 2c as a gray
solid, mp > 260 °C dec; tlc Rf 0.47 (CHCl3:MeOH, 5:1); 1H nmr
(DMSO-d6) ꢀ 2.67 (t, 2H, CH2), 3.11 (t, 2H, CH2-N), 6.00 (bs,
4H, 2-NH2 and 4-NH2 ), 6.35 (d, 1H, J = 7.5 Hz, C10H7), 6.61 (s,
1H, NH), 7.01 (d, 1H, J = 8.0 Hz, C10H7), 7.23 (t, 1H, C10H7),
7.36 (m, 2H, C10H7), 7.70 (d, 1H, J = 7.9 Hz, C10H7), 8.01 (d,
1H, J = 8.0 Hz, C10H7), 10.16 (s, 1H, NH).
2,6-Diamino-5-[2-(methylphenylamino)ethyl]pyrimidin-4(3H)-
one (3a).
Compound 3a was obtained from intermediate 2a (0.10 g,
0.43 mmol), formaldehyde (0.12 ml, 4.30 mmol) and sodium
cyanoborohydride (89 mg, 1.29 mmol) using the general
procedure described above to afford 0.047 g (44%) of 3a as a
pale yellow solid, mp 218-219 °C; tlc Rf 0.39 (CHCl3:MeOH,
5:1); 1H nmr (DMSO-d6) ꢀ 2.37 (t, 2H, CH2), 2.89 (s, 3 H, CH3),
3.16 (t, 2 H, NCH2), 5.75 (s, 2 H, NH2), 5.95 (s, 2 H, NH2), 6.53
(t, 1H, C6H5), 6.80 (d, 2H, C6H5), 7.10 (t, 2H, C6H5), 9.75 (s, 1H,
NH).
Anal. Calcd for C16H17N5O•0.6 CH3COOC2H5: C, 63.47; H,
6.31; N, 20.11. Found: C, 63.57; H, 6.26; N, 19.96.
2,6-Diamino-5-[2-(naphthalen-2-yl-amino)ethyl]pyrimidin-
4(3H)-one (2d).
Compound 2d was synthesized from intermediate 14d (0.45
g, 1.77 mmol), sodium methoxide (0.50 g, 9.22 mmol) and
guanidine hydrochloride (0.85 g, 8.85 mmol) using the general
procedure described above to afford 0.13 g (28%) of 2d as a
light brown solid, mp > 243 °C dec; tlc Rf 0.47 (CHCl3:MeOH,
Anal. Calcd for C13H17N5O: C, 60.21; H, 6.61; N, 27.01.
Found: C, 60.01; H, 6.60; N, 26.84.
2,6-Diamino-5-{2-[methyl-(3,4,5-trimethoxyphenyl)amino]ethyl}-
pyrimidin-4(3H)-one (3e).
1
Compound 3e was obtained from intermediate 2e (100 mg,
0.31 mmol), formaldehyde (0.09 ml, 3.10 mmol), and sodium
cyanoborohydride (64 mg, 0.93 mmol) using the general
procedure described above to afford 0.05 g (47%) of 3e as a pale
orange solid, mp 190-192 °C; tlc Rf 0.41 (CHCl3:MeOH, 5:1);
1H nmr (DMSO-d6): ꢀ 2.40 (t, 2H, CH2) , 2.92 (s, 1H, CH3), 3.15
(m, 2H, N-CH2), 3.53 (s, 3H, 4'-OMe), 3.77 (s, 6H, 3',5'-
diOMe), 5.80 (s, 2H, NH2), 5.93 (s, 2H, NH2), 6.13 (s, 2H,
C6H2), 9.91 (s, 1H, NH).
5:1); H nmr (DMSO-d6) ꢀ 2.55 (t, 2H, CH2) , 3.02 (m, 2H,
CH2), 5.86 (bs, 3H, 9-NH and NH2), 6.01 (s, 2H, NH2), 6.68 (s,
1H, C10H7), 6.90 (d, 1H, J = 8.3 Hz, C10H7), 7.06 (t, 1H, C10H7),
7.27 (t, 1H, C10H7), 7.52-7.62 (m, 3H, C10H7), 9.88 (s, 1H, NH).
Anal. Calcd for C16H17N5O•0.5 H2O: C, 63.14; H, 5.96; N,
23.01. Found: C, 63.19; H, 5.72; N, 22.84.
2,6-Diamino-5-[2-(3,4,5-trimethoxyphenylamino)ethyl]pyrimidin-
4(3H)-one (2e).
Compound 2e was synthesized from intermediate 14e (0.58 g,
1.95 mmol), sodium methoxide (1.14 g, 21.12 mmol) and
guanidine hydrochloride (1.89 g, 19.80 mmol) using the general
procedure described above to afford 0.27 g (45%) of 2e as a
light pink solid, mp 181-183 °C; tlc Rf 0.36 (CHCl3:MeOH,
Anal. Calcd for C16H23N5O4• 0.3 H2O: C, 54.17; H, 6.70; N,
19.74. Found: C, 53.81; H, 6.88; N, 20.10.
General Procedure for the Synthesis of Compounds 15b-d.
To a mixture of 13b-d and formaldehyde in 1,2-dichloro-
ethane were added sodium triacetoxyborohydride and acetic
acid. The resulting reaction mixture was stirred at room
temperature for 24 hours and then poured into water and
extracted with CH2Cl2. The organic layer was washed with
1
5:1); H nmr (DMSO-d6) ꢀ 2.45 (t, 2H, CH2) , 2.90 (m, 2H, N-
CH2), 3.51 (s, 3H, 4'-OMe), 3.70 (s, 6H, 3',5'-diOMe), 5.31 (t,
1H, 9-NH), 5.81 (s, 2H, NH2), 5.86 (s, 2H, C6H2), 5.98 (s, 2H,
NH2), 9.88 (s, 1H, NH).

1530
A. Gangjee, Y. Wang, S. F. Queener and R. L. Kisliuk
Vol 43
brine, dried over Na2SO4, and concentrated in vacuo. The
residue was purified by silica gel column chromatography and
eluted with ethyl acetate:hexanes (1:30) to afford the product.
Compound 3b was obtained from intermediate 15b (1.97 g,
9.64 mmol), sodium methoxide [(0.57 g, 10.61 mmol, first step)
and (1.02 g, 18.86 mmol, second step)], ethyl cyanoacetate (1.62
ml, 14.46 mmol), and guanidine hydrochloride (1.74 g, 18.24
mmol) using the general procedure described above to afford
0.34 g (12% over two steps) of 3b as a white solid, mp 252-253
(2-Chloroethyl)-(4-chlorophenyl)methylamine (15b).
Compound 15b was obtained from intermediate 13b (0.76 g,
3.99 mmol) and formaldehyde (0.57 ml, 19.95 mmol), sodium
triacetoxyborohydride (1.27 g, 7.98 mmol), and acetic acid (0.15
ml, 2.61 mmol) using the general procedure described above to
afford 0.28 g (34%) of 15b as a pale yellow oil; tlc Rf 0.47 (ethyl
1
°C; tlc Rf 0.35 (CHCl3:MeOH, 5:1); H nmr (DMSO-d6) ꢀ 2.37
(t, 2H, CH2), 2.90 (s, 3H, NCH3), 3.17 (t, 2H, NCH2), 5.81 (s,
2H, NH2), 5.99 (s, 2H, NH2), 6.81 (d, 2H, C6H4), 7.13 (d, 2H,
C6H4), 9.85 (s, 1H, NH).
Anal. Calcd for C13H16N5OCl: C, 53.15; H, 5.49; N, 23.84; Cl,
12.10. Found: C, 52.86; H, 5.37; N, 23.63; Cl, 12.37.
1
acetate:hexanes, 1:6); H nmr (DMSO-d6) ꢀ 2.93 (s, 3H, NCH3),
3.65-3.72 (m, 4H, NCH2 and CH2Cl), 6.72 (d, 2H, C6H4), 7.19
(d, 2H, C6H4). HRMS (EI): Calculated for C9H11NCl2, m/z =
204.0968). Found: m/z = 204.0969.
2,6-Diamino-5-[2-(methylnaphthalen-1-yl-amino)ethyl]pyrimidin-
4(3H)-one (3c).
(2-Chloroethyl)methylnaphthalen-1-yl-amine (15c).
Compound 3c was obtained from intermediate 15c (1.41 g,
6.42 mmol), sodium methoxide [(0.38 g, 7.07 mmol, first step)
and (0.68 g, 12.57 mmol, second step)], ethyl cyanoacetate (1.08
ml, 9.64 mmol), and guanidine hydrochloride (1.16 g, 12.16
mmol) using the general procedure described above to afford
0.10 g (5% over two steps) of 3c as a pale yellow solid, mp 113-
Compound 15c was obtained from intermediate 13c (1.98 g,
9.61 mmol), formaldehyde (1.37 ml, 48.05 mmol), sodium
triacetoxyborohydride (3.06 g, 19.23 mmol), and acetic acid
(0.15 ml, 2.61 mmol) using the general procedure described
above to afford 1.41 g (67%) of 15c as a red oil; tlc Rf 0.47
1
1
(ethyl acetate:hexanes, 1:6); H nmr (DMSO-d6) ꢀ 2.84 (s, 3H,
115 °C; tlc Rf 0.33 (CHCl3:MeOH, 5:1); H nmr (DMSO-d6) ꢀ
NCH3), 3.34 (m, 2H, CH2N), 3.82 (t, 2H, J = 6.3 Hz, CH2Cl),
7.21 (d, 1H, J = 7.4 Hz, C10H7), 7.40-7.53 (m, 3H, C10H7), 7.60
(d, 1H, J = 8.0 Hz, C10H7), 7.87 (t, 1H, C10H7), 8.23 (d, 1H,
C10H7).
2.57 (t, 2H, CH2), 2.87 (s, 3H, CH3), 2.95 (t, 2H, CH2N), 5.70 (s,
2H, NH2), 5.95 (s, 2H, NH2 ), 7.13 (d, 1H, J = 7.2 Hz, C10H7),
7.35-7.52 (m, 4H, C10H7), 7.83 (d, 1H, J = 7.2 Hz, C10H7), 8.20
(d, 1H, J = 7.7 Hz, C10H7), 9.77 (s, 1H, NH).
Anal. Calcd for C17H19N5O• 0.4 CH3OH: C, 64.87; H, 6.44; N,
21.74. Found: C, 65.22; H, 6.34; N, 21.45.
(2-Chloroethyl)methylnaphthalen-2-yl-amine (15d).
Compound 15d was obtained from intermediate 13d (0.20 g,
0.98 mmol), formaldehyde (3.60 ml, 4.89 mmol, 37% in water),
sodium triacetoxyborohydride (0.62 g, 2.93 mmol), and acetic
acid (0.15 ml, 2.61 mmol) using the general procedure described
above to afford 0.75 g (35%) of 15d as a yellow oil; tlc Rf 0.81
2,6-Diamino-5-[2-(methylnaphthalen-2-yl-amino)ethyl]pyrimidin-
4(3H)-one (3d).
Compound 3d was obtained from intermediate 15d (1.97 g, 9.64
mmol), sodium methoxide [(0.38 g, 7.07 mmol, first step) and
(0.35 g, 6.49 mmol, second step)], ethyl cyanoacetate (1.08 ml,
9.64 mmol), and guanidine hydrochloride (0.60 g, 6.28 mmol)
using the general procedure described above to afford 0.18 g (9%
over two steps) of 3d as a gray solid, mp 198-200 °C; tlc Rf 0.41
(CHCl3:MeOH, 5:1); 1H nmr (DMSO-d6) ꢀ 2.50 (s, 2H, CH2) , 3.03
(s, 3H, CH3), 3.34 (s, 2H, CH2N), 5.81 (s, 1H, NH2), 6.00 (s, 2H,
NH2), 6.98 (s, 1H, C10H7), 7.10 (t, 1H, C10H7), 7.29 (t, 1H, C10H7),
7.37 (d, 1H, C10H7), 7.57 (d, 1H, C10H7), 7.66 (d, 2H, C10H7), 9.81
(s, 1H, NH). HRMS (EI): Calculated for C17H19N5O: m/z =
309.1590. Found: m/z = 309.1601.
1
(ethyl acetate:hexanes, 1:2); H nmr (DMSO-d6) ꢀ 3.05 (s, 3H,
CH3), 3.35 (m, 2H, CH2N), 3.79 (t, 2H, CH2Cl), 6.96 (s, 1H,
C10H7), 7.14-7.37 (m, 3H, C10H7), 7.65-7.82 (m, 3H, C10H7).
General Procedure for the Synthesis of Compounds 3b-d.
To a stirred solution of sodium methoxide in absolute ethanol
was added ethyl cyanoacetate. The solution was stirred for 5
minutes at room temperature and then evaporated in vacuo at 40
°C, and the residue was dissolved in dry DMF. To the solution
were added 15b-d and a crystal of NaI, and the solution was
stirred at 95-100 °C under nitrogen for 2 hours. The mixture was
poured into water and extracted with CH2Cl2 (6 ꢁ 15 ml). The
organic layer was washed with brine (2 ꢁ 30 ml), dried with
Na2SO4, filtered and purified by flash column chromatography
on silica gel eluted with ethyl acetate:hexanes (1:30) to afford
16b-d. The freshly prepared 16b-d was immediately added to a
stirred mixture of sodium methoxide and guanidine hydro-
chloride that had been stirred for 30 minutes at room temper-
ature. This mixture was stirred under nitrogen at 90-100 °C for 1
hour and quenched by adding water (1.0 ml). Silica gel was
added to this mixture and the solvent evaporated to afford a dry
plug. This plug was chromatographed on a silica gel column
using a gradient of CHCl3:MeOH (28-30 % NH3 in MeOH) 20:1
and then 10:1 as the eluent. Fractions containing the pure
product (tlc) were pooled and evaporated to afford the product.
Acknowledgement.
This work was supported in part by Grants AI 41743 (A.G.)
and AI 44661 (A.G.), NIH Contracts N01-AI-87240 (S.F.Q.)
and N01-AI-3171 (S.F.Q.) from the National Institutes of
Allergy and Infectious Diseases, and CA10914 (R.L.K.) from
the National Cancer Institute.
REFERENCES AND NOTES
* Author to whom correspondence should be addressed at Duquesne
University: Tel: 412-396-6070. Fax: 412-396-5593.
[1a] Taken in part from the thesis submitted by Y. W. to the
Graduate School of Pharmaceutical Sciences, Duquesne University, in
partial fulfillment of the requirement for the degree of Master of Science,
June 2004; [b] Presented in part at the American Chemical Society
National Meeting, Anaheim, CA, March 21-25, 1999; MEDI 047.
2,6-Diamino-5-{2-[(4-chlorophenyl)methylamino]ethyl}-pyrimidin-
4(3H)-one (3b).

Nov-Dec 2006
Synthesis of 2,6-Diamino-5-[(2-substituted phenylamino)ethyl]pyrimidin-4(3H)-one
1531
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