Efficient one-pot synthesis of polysubstituted 6-[(1H-1,2,3-Triazol-1-Yl) Methyl]uracils through the "click" protocol

Article abstract of DOI:10.1135/cccc2011074

The preparation of several triazolo acyclic nucleosides and triazolo acyclic nucleoside phosphonates is described. The synthetic methodology has been developed as an efficient one-pot Cu(I)-catalyzed azide alkyne Huisgen "click" cycloaddition. A novel Cu(I)-catalyzed decarboxylation reaction of 1-substituted 1H-1,2,3-triazole-4-carboxylic acids at room temperature was observed and used for the preparation of 1-substituted 1H-1,2,3-triazoles. As congeners of TPI (Taiho pharmaceutical inhibitor), the prepared compounds were screened as potential inhibitors of human thymidine phosphorylase, but no inhibitory activity was observed.

Full text of DOI:10.1135/cccc2011074

Polysubstituted 6-[(1H-1,2,3-Triazol-1-yl)methyl]uracils
1121
EFFICIENT ONE-POT SYNTHESIS OF POLYSUBSTITUTED
6-[(1H-1,2,3-TRIAZOL-1-YL)METHYL]URACILS THROUGH THE
“CLICK” PROTOCOL
1,
2
3
4
Petr JANSA *, Petr ŠPAČEK , Ivan VOTRUBA , Petra BŘEHOVÁ ,
5
6
7
Martin DRAČÍNSKÝ , Blanka KLEPETÁŘOVÁ and Zlatko JANEBA
Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i.,
1
Flemingovo nám. 2, 166 10 Prague 6, Czech Republic; e-mail: jansa@uochb.cas.cz,
2
5
3
4
spacek@uochb.cas.cz, votruba@uochb.cas.cz, brehova@uochb.cas.cz,
6
7
dracinsky@uochb.cas.cz, klepetarova@uochb.cas.cz, janeba@uochb.cas.cz
Received April 15, 2011
Accepted May 19, 2011
Published online August 29, 2011
Dedicated to the 75th anniversary of Professor Antonín Holý’s birthday and the 25th anniversary of
the discovery of antiviral nucleoside phosphonates.
The preparation of several triazolo acyclic nucleosides and triazolo acyclic nucleoside
phosphonates is described. The synthetic methodology has been developed as an efficient
one-pot Cu(I)-catalyzed azide alkyne Huisgen “click” cycloaddition. A novel Cu(I)-catalyzed
decarboxylation reaction of 1-substituted 1H-1,2,3-triazole-4-carboxylic acids at room tem-
perature was observed and used for the preparation of 1-substituted 1H-1,2,3-triazoles. As
congeners of TPI (Taiho pharmaceutical inhibitor), the prepared compounds were screened
as potential inhibitors of human thymidine phosphorylase, but no inhibitory activity was
observed.
Keywords: Nucleosides; Nucleotides; Biological activity; Heterocycles; Phosphorus; Click
chemistry.
The synthesis of nucleoside or nucleotide analogues with a biomimetically
modified ‘sugar’ moiety is an area of tremendous interest because of their
wide range of biological activities, especially antiviral1, antiparasitic2 and
cytostatic3. So-called acyclic nucleosides4, where the sugar part of the mol-
ecule is substituted by an acyclic alkyl or heteroalkyl chain, are very prom-
ising and very potent compounds. The biological activity of these
compounds with longer chains is negatively influenced by the entropic
contribution to the free energy during the interaction of such molecules
with the target enzymes or receptors. Long acyclic chains can rotate around
Collect. Czech. Chem. Commun. 2011, Vol. 76, No. 9, pp. 1121–1131
© 2011 Institute of Organic Chemistry and Biochemistry
doi:10.1135/cccc2011074

1122
Jansa, Špaček, Votruba, Břehová, Dračínský, Klepetářová, Janeba:
every single bond. All these free-rotation states are lost after incorporation
into the target enzyme, where usually only one rotamer forms a stable com-
plex with the investigated biomolecule. To suppress this negative entropic
contribution, the long alkyl chains could be modified by the insertion of
double bonds5 or small 5-membered cycles. The introduction of a 1,2,3-tri-
azole ring by a Cu(I)-catalyzed6 azide alkyne Huisgen7 “click” cycloaddition
(abbreviated also as “CuAAC”) is a very useful tool for freezing the rotation
flexibility of the acyclic part of the molecule. Some initial studies describ-
ing the possibility of freezing the side-chain flexibility of acyclic nucleo-
sides or acyclic nucleoside phosphonates with the triazole moiety have
already been reported8. The general impact of the Cu(I)-catalyzed 1,3-di-
polar cycloaddition reaction between alkynes and azides on the chemistry
of nucleosides and oligonucleotides has been also reviewed9.
In addition, nucleoside analogues with triazole rings can also act as
transition-state analogue inhibitors. This was demonstrated for example for
the analogues of the Taiho pharmaceutical inhibitor (TPI) (1), which is a
very potent thymidine phosphorylase inhibitor, where substituted 6-[(1H-
imidazol-1-yl)methyl]uracils (2) and 6-[(1H-1,2,4-triazol-1-yl)methyl]-
uracils (3) were identified as promising inhibitors of human thymidine
phosphorylase (Fig. 1)10. Surprisingly, no 6-[(1H-1,2,3-triazol-1-yl)methyl]-
uracils, which could be also promising inhibitors of human thymidine
phosphorylase and are easy to prepare by the Huisgen “click” protocol,
have been reported to the best of our knowledge, only base-modified
5-(1,2,3-triazol-1-yl)-2′-deoxyuridines were prepared and studied for their
antiviral activities11.
Due to the high regioselectivity of the CuAAC, only 4′-substituted
6-[(1H-1,2,3-triazol-1-yl]methyl)uracils could be selectively prepared. This
substituent in the position 4′ can interact with the highly polar phosphate
binding site in the molecule of human thymidine phosphorylase12. There-
fore, 6-[(1H-1,2,3-triazol-1-yl)methyl]uracils bearing polar substituent in
O
O
O
X
Cl
X
N
HN
HN
HN
N
N
N
N
N
O
N
H
O
N
H
O
N
H
NH.HCl
X = Cl, F
3
2
1 (TPI)
FIG. 1
Structures of the known potent inhibitors of thymidine phosphorylase
Collect. Czech. Chem. Commun. 2011, Vol. 76, No. 9, pp. 1121–1131

Polysubstituted 6-[(1H-1,2,3-Triazol-1-yl)methyl]uracils
1123
the position 4′ can act as transition-state analog inhibitors of human
thymidine phosphorylase.
RESULTS AND DISCUSSION
At first, the key intermediates 5a and 5b bearing an azidomethyl group
were prepared by the reaction of chloromethyl derivatives 4a and 4b
with sodium azide in DMF at room temperature (Scheme 1). The conver-
sion to the products of 5 is quantitative and sodium chloride is the only
by-product formed. Thus, the reaction mixture containing the compounds
of 5 can be used directly in the next step.
The crude intermediates of 5 in DMF were reacted with a wide range of
commercially available terminal alkynes under the Cu(I)-catalyzed azide
alkyne Huisgen “click” conditions at room temperature to obtain substi-
tuted 6-[(1H-1,2,3-triazol-1-yl)methyl]uracils (Scheme 1). This reaction was
surprisingly very slow when only the catalytic amount (5%) of Cu(I) was
used. It was rationalized that the product of the reaction because of its che-
late-like structure could form stable complexes with the copper catalyst.
This notion was afterwards confirmed during the isolation of the desired
product (see below). Therefore, one molar equivalent of Cu(I) was used
and the full conversion was obtained within a minute. As expected, the
Huisgen “click” reaction with terminal alkynes is fully regiospecific and
leads only to the formation of substituted 6-[(1H-1,2,3-triazol-1-yl)methyl]-
uracils. The acyclic nucleoside phosphonate analogues 10 and 11 were
also prepared using diisopropyl [(prop-2-yn-1-yloxy)methyl]phosphonate
(Scheme 1), which was prepared according to the literature7, except that
the diisopropyl bromomethylphosphonate13 reagent was used instead of
the tosyloxymethylphosphonate derivative.
Surprisingly, during the formation of 1-substituted 1H-1,2,3-triazole-
4-carboxylic acids by the reaction of intermediate 5a or 5b with acrylic
acid, a novel Cu(I)-catalyzed decarboxylation reaction at room temperature
was observed. Thus, the prolonged reaction time (5 days) yielded 1-substi-
tuted 1H-1,2,3-triazoles 9a and 9b. This decarboxylation reaction of 1,2,3-
triazole-4-carboxylic acids has been already described in the literature but
under more drastic conditions, e.g. reflux in concentrated hydrochloric
acid14, thermal decomposition at 160 °C 15, photochemical degradation16 or
in the presence of copper powder at 180 °C 17. Very recently, a single case of
such a decarboxylation reaction has been observed during a Cu(I) catalyzed
tandem decarboxylative coupling of alkynoic acids and 1,3-dipolar cyclo-
addition of azides, which was used for the synthesis of a variety of func-
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1124
Jansa, Špaček, Votruba, Břehová, Dračínský, Klepetářová, Janeba:
tionalized 1,2,3-triazoles18. The carboxyl function in the molecule of
1,2,3-triazole-4-carboxylic acids was found to be very reactive also in other,
different types of reactions. During isolation (see below) on silica gel col-
umn chromatography using an eluent containing ethanol, a full conversion
into ethyl esters 8a and 8b was observed.
O
COOCH3
COOCH3
d
N
HN
N
N
O
N
H
7
O
O
O
X
f (R=H)
X
e
c
N
X
N
OH
HN
N
N
N
HN
N
N
OR
HN
N
N
O
N
H
O
N
H
O
N
H
O
9a, X = H
9b, X = Cl
6a, X = H
6b, X = Cl
8a, X = H, R = Et
8b, X = Cl, R = Et
isolation
R = H
O
O
O
P
O
OR
OR
O
OR
OR
P
O
g
b
X
X
HN
N
HN
O
HN
N
N
N3
Cl
O
N
H
O
N
O
N
H
H
10, R = iPr
11, R = H
5a, X = H
5b, X = Cl
4a, X = H
4b, X = Cl
h
a
O
O
O
i
j
N
HN
O
OH
HN
N
N
N
HN
N
N
NH2
N
O
N
O
N
H
H
NH
H
O
O
HO
14
13
12
SCHEME 1
Conditions: (a) NCS, AcOH, (Ac)2O, 60 °C; (b) NaN3, DMF, r.t.; (c) prop-2-yn-1-ol, DMF, CuI,
r.t.; (d) dimethyl 2-(prop-2-yn-1-yl)malonate, DMF, CuI, r.t.; (e) acrylic acid, DMF, CuI, r.t.; (f)
DMF, CuI, r.t.; (g) DMF, CuI, r.t.; (h) BTMS, CH3CN, r.t.; (i) prop-2-yn-1-amine, DMF, CuI, r.t.;
(j) but-2-yne-1,4-diol, DMF, 120 °C
Another unexpected reaction was observed during the reaction of
propargylamine with intermediate 5a or 5b, where only an N-formyl deriv-
ative 12 of the desired product was isolated. It is well known that DMF is a
quite reactive solvent and that it can decompose into dimethylamine and
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Polysubstituted 6-[(1H-1,2,3-Triazol-1-yl)methyl]uracils
1125
carbon oxide19, but this formylation at room temperature was truly unan-
ticipated.
The Cu(I)-catalyzed azide alkyne Huisgen “click” cycloaddition could not
be used for the preparation of 4- and 5-disubstituted 1,2,3-triazoles. This
type of compounds can be prepared by azide alkyne cycloaddition at ele-
vated temperature. Such a reaction was used for the preparation of symmet-
rical dihydroxymethyl derivative 13, where a partial degradation of the
starting compound 5a was observed at 120 °C to produce compound 14.
Finally, the most challenging part of this work was the isolation of the
prepared compounds, where the copper catalyst could not be removed by
simple column chromatography. Such isolated products were green and ac-
cording to the X-ray fluorescence method they contained copper. For the
most liphophilic compound 7, a wide range of extraction techniques were
applied, such as extraction with aqueous EDTA disodium salt or sodium
thiosulfate, but without success. We can speculate that the target com-
pounds form stable complexes with copper owing to their chelate-like
structures (Fig. 2). After some optimization, efficient isolation conditions
were found. The procedure is based on the low solubility of CuS. Thus, after
the complete reaction, 1.5 molar eq. of sodium sulfide were added. The re-
action mixture was stirred at room temperature for 10 min while being
purged in a slow current of air. A solid dark precipitation was filtered off
and the final purification was done using flash chromatography. By this
method, all of the prepared 4′-substituted 6-[(1H-1,2,3-triazol-1-yl)methyl]-
uracils were isolated as pure compounds (copper < 5 ppm) in good to excel-
lent preparative yields of 71–93%. A copper-less process for the preparation
of 4′,5′-disubstituted 6-[(1H-1,2,3-triazol-1-yl)methyl]uracil 13 provided the
product in a 36% yield only.
O
X
HN
O
N
H
R
N
N
N
Cu+
N
N
N
R
H
N
O
NH
X
O
FIG. 2
The proposed structure of the complex of 6-[(1H-1,2,3-triazol-1-yl)methyl]uracils with copper
Collect. Czech. Chem. Commun. 2011, Vol. 76, No. 9, pp. 1121–1131

1126
Jansa, Špaček, Votruba, Břehová, Dračínský, Klepetářová, Janeba:
The chemical structure of the prepared compounds and the presence of
the 6-[(1H-1,2,3-triazol-1-yl)methyl]uracil motive was unambiguously con-
firmed by solving the X-ray structure of compound 6a (Fig. 3).
All of the prepared compounds were tested for their in vitro inhibition
of thymidine phosphorylase. In contrast to active 6-[(1H-imidazol-1-yl]-
methyl)uracils (2) and 6-[(1H-1,2,4-triazol-1-yl)methyl]uracils (3)6, none of
the prepared compound exhibited any significant inhibitory activity. The
inactivity of the tested compounds could be explained for compounds with
only a hydrogen atom at position 5 of the uracil ring. It was fully demon-
strated that the substituent in position 5 of the uracil ring has a key effect
on inhibitory activity where only 5-halo-, 5-alkyl- or 5-aryluracils could act
as thymidine phosphorylase inhibitors20. Nevertheless, the absence of the
biological activity of prepared 5-chlorouracils is really incomprehensible.
All of the prepared compounds (as analogs of nucleic acid components)
were also tested for their antiproliferative and antiviral activities. None of
the tested compounds exhibited any antiproliferative activity in mouse leu-
kemia L1210 cells, human T-lymphoblastoid CCRF-CEM cell line, human
promyelocytic leukemia HL-60 cells, human cervix carcinoma HeLa S3 cells
or any antiviral activity against HIV, HCV, RSV, VZV, CMV, HSV-1, HSV-2,
Vaccinia virus, Coxsackie B4 virus, Vesicular stomatitis virus, Feline corona
virus and Influenza A virus.
In conclusion, an efficient methodology for the preparation and isolation
of several triazolo acyclic nucleosides and one triazolo acyclic nucleoside
phosphonate was described. The synthetic method has been developed as
an efficient one-pot Cu(I)-catalyzed azide alkyne Huisgen “click” cyclo-
addition. A novel Cu(I)-catalyzed decarboxylation reaction of 1-substituted
1H-1,2,3-triazole-4-carboxylic acids at room temperature was observed and
used for the preparation of 1-substituted 1H-1,2,3-triazoles. As nucleoside
FIG. 3
An ORTEP drawing of 6a. Thermal ellipsoids are drawn at the 50% probability level
Collect. Czech. Chem. Commun. 2011, Vol. 76, No. 9, pp. 1121–1131

Polysubstituted 6-[(1H-1,2,3-Triazol-1-yl)methyl]uracils
1127
and nucleotide analogues, the prepared compounds were screened for their
probable biological activities, but no antiviral, antiproliferative and inhibi-
tory activities towards thymidine phosphorylase were observed.
EXPERIMENTAL
Unless otherwise stated, the solvents were evaporated at 40 °C/2 kPa and the compounds
were dried in vacuo over P2O5. The NMR spectra were recorded on a Bruker Avance 500 (1H
at 500 MHz, 13C at 125.8 MHz). Chemical shifts, given in ppm (δ-scale), were referenced to
the signal of DMSO (δ 2.50 and 39.7) or to dioxane (δ 3.75 and 67.19). Coupling constants
(J) are given in Hz. The assignment of the carbons was based on C,H-HSQC and C,H-HMBC
experiments. The melting points were determined on a Kofler block and are uncorrected.
The mass spectra were measured on a LCQ Fleet spectrometer (Thermo Fisher Scientific)
using ESI ionization. The high-resolution mass spectra were measured on a LTQ Orbitrap XL
spectrometer (Thermo Fisher Scientific) using ESI ionization. The 6-(Chloromethyl)-
pyrimidine-2,4(1H,3H)-dione (4a) was purchased from ABCR GmbH & Co.KG (Germany).
The X-ray diffraction data of a single crystal of 6a (colorless, 0.09 × 0.46 × 0.51 mm) were
collected on an Xcalibur X-ray diffractometer with CuKα (λ = 1.54180 Å) at 150 K. The
structure was solved by direct methods with SIR92 21 and refined by the full-matrix, least-
squares methods based on F with CRYSTALS 22. The hydrogen atoms were located in a differ-
ence map, but those attached to carbon atoms were repositioned geometrically and then re-
fined with riding constraints; the non-hydrogen atoms were refined with anisotropic
thermal displacement parameters.
5-Chloro-6-(chloromethyl)pyrimidine-2,4(1H,3H)-dione (4b) was prepared according to the lit-
erature23. ESI MS, m/z (%): 193.2 (100) [M–]. HR ESI MS: for C5H3Cl2N2O2 calculated
192.9577; found 192.9577.
One-Pot Synthesis of Monosubstituted 6-[(1H-1,2,3-Triazol-1-yl)methyl]uracils.
General Procedure
6-(Chloromethyl)pyrimidine-2,4(1H,3H)-dione (4a) or 5-chloro-6-(chloromethyl)pyrimidine-
2,4(1H,3H)-dione (4b) (1 mmol) was added to the suspension of sodium azide (1.05 mmol)
in 10 ml of DMF. Full conversion was achieved after stirring at ambient temperature for 2 h
according to the TLC (the control sample of the reaction mixture was evaporated in vacuo
and the MS spectra of 5a and 5b confirmed the presence of the desired product – see be-
low). This reaction mixture containing only sodium chloride, traces of sodium azide and
product 5a or 5b was pure enough for the next reaction. Therefore, this reaction mixture
was injected into the solution containing copper(I) iodide (1 mmol) and the selected alkyne
(2 mmol) in 20 ml of DMF under an inert atmosphere of argon. This mixture was stirred at
room temperature for 10 min. The reaction was always completed after 1 min according to
the TLC. For the synthesis of compounds 9a and 9b, the reaction time was prolonged for
additional 5 days. For the separation of the copper catalyst, sodium sulfide (1.5 mmol) was
added and the reaction mixture was stirred at room temperature for 10 min while being
purged in a slow current of air. A solid dark precipitation was filtered off and the final prod-
uct was isolated by flash chromatography (silica gel, ethyl acetate/acetone/ethanol/water
30:3:4:3).
Collect. Czech. Chem. Commun. 2011, Vol. 76, No. 9, pp. 1121–1131

1128
Jansa, Špaček, Votruba, Břehová, Dračínský, Klepetářová, Janeba:
6-(Azidomethyl)pyrimidine-2,4(1H,3H)-dione (5a): ESI MS, m/z (%): 166.0 (100) [M–]. HR ESI
MS: for C5H4N5O2 calculated 166.0365; found 166.0364.
6-(Azidomethyl)-5-chloropyrimidine-2,4(1H,3H)-dione (5b): ESI MS, m/z (%): 200.1 (100) [M–].
HR ESI MS: for C5H3ClN5O2 calculated 199.9981; found 199.9982.
6-{[4-(Hydroxymethyl)-1H-1,2,3-triazol-1-yl]methyl}pyrimidine-2,4(1H,3H)-dione (6a): Yield
207 mg (93%) of white crystals, m.p. >250 °C. 1H NMR (DMSO-d6): 11.13 bs, 1 H and
11.10 bs, 1 H (H-1, H-3); 8.20 s, 1H (H-5′); 5.39 s, 2 H (NCH2); 4.89 s, 1 H (H-5); 4.48 s, 2 H
(OCH2). 13C NMR (DMSO-d6): 163.65 (C-6); 151.40 (C-2); 151.03 (C-4); 145.70 (C-4′); 127.58
(C-5′); 98.51 (C-5); 55.02 (CH2OH); 48.86 (NCH2). ESI MS, m/z (%): 222.1 (100) [M–]. HR ESI
MS: for C8H8N5O3 calculated 222.0627; found 222.0625. For C8H9N5O3 (223.19) calculated:
43.05% C, 4.06% H, 31.38% N; found: 43.24% C, 4.31% H, 31.19% N.
Crystal data for 6a: C8H9N5O3, monoclinic, space group P21/c, a = 10.9584(5) Å, b =
10.8983(4) Å, c = 8.2735(4) Å, β = 108.409(5)°, V = 937.53(8) Å3, Z = 4, M = 223.19; 9216 re-
flections measured, 1976 independent reflections. Final R = 0.043, wR = 0.037, GOF = 1.268
for 1857 reflections with I > 2σ(I) and 146 parameters.
CCDC 821669 contains the supplementary crystallographic data for this paper. These
data can be obtained free of charge via www.ccdc.cam.ac.uk/conts/retrieving.html (or from
the Cambridge Crystallographic Data Centre, 12, Union Road, Cambridge, CB2 1EZ, UK;
fax: +44 1223 336033; or deposit@ccdc.cam.ac.uk).
5-Chloro-6-{[4-(hydroxymethyl)-1H-1,2,3-triazol-1-yl]methyl}pyrimidine-2,4(1H,3H)-dione (6b):
Yield 234 mg (91%) of white crystals, m.p. >250 °C. 1H NMR (DMSO-d6): 11.50 bs, 1 H
(NH); 8.08 s, 1 H (H-5′); 5.40 bs, 2 H (NCH2); 4.51 s, 2 H (OCH2). 13C NMR (DMSO-d6):
160.35 (C-6); 151.16 (C-2); 148.24 (C-4′); 146.73 (C-4); 123.81 (C-5′); 106.76 (C-5); 55.17
(CH2OH); 48.58 (NCH2). ESI MS, m/z (%): 256.1 (100) [M–]. HR ESI MS: for C8H7ClN5O3 cal-
culated 256.0243; found 256.0244. For C8H8ClN5O3 (257.63) calculated: 37.30% C, 3.13% H,
27.18% N; found: 37.15% C, 3.30% H, 27.22% N.
Dimethyl 2-({1-[(2,6-dioxo-1,2,3,6-tetrahydropyrimidin-4-yl)methyl]-1H-1,2,3-triazol-4-yl}-
methyl)malonate (7): Yield 278 mg (82%) of white crystals, m.p. >250 °C. 1H NMR
(DMSO-d6): 11.23 bs, 1 H (H-3); 11.14 bs, 1 H (H-1); 8.00 s, 1 H (H-5′); 5.31 d, 2 H,
J(CH2,5) = 1.2 (NCH2); 4.79 t, 1 H, J(5,CH2) = 1.2 (H-5); 3.93 t, 1 H, J(CH,CH2) = 7.8
(4′-CH2-CH); 3.64 s, 6 H (CH3); 3.18 d, 2 H, J(CH2,CH) = 7.8 (4′-CH2). 13C NMR (DMSO-d6):
168.96 (COO); 163.92 (C-6); 151.40 and 151.13 (C-2, C-4); 143.52 (C-4′); 124.24 (C-5′);
98.22 (C-5); 52.72 (COOCH3); 50.97 (4′-CH2-CH); 48.93 (NCH2); 24.76 (4′-CH2). ESI MS,
m/z (%): 338.1 (30) [MH+]; 360.2 (100) [MNa+]. ESI MS, m/z (%): 337.2 (100) [M–]. HR ESI
MS: for C13H14N5O6 calculated 336.0950; found 336.0940. For C13H15N5O6 (337.29) calcu-
lated: 46.29% C, 4.48% H, 20.76% N; found: 46.11% C, 4.67% H, 20.87% N.
Ethyl 1-[(2,6-dioxo-1,2,3,6-tetrahydropyrimidin-4-yl)methyl]-1H-1,2,3-triazole-4-carboxylate (8a):
Yield 214 mg (81%) of white crystals, m.p. >250 °C. 1H NMR (DMSO-d6): 11.23 bs, 1 H
(H-3); 11.17 bs, 1 H (H-1); 8.87 s, 1 H (H-5′); 5.41 s, 2 H (NCH2); 5.11 s, 1 H (H-5); 4.32 q,
2 H, J(CH2,CH3) = 7.1 (OCH2); 1.30 t, 3 H, J(CH3,CH2) = 7.1 (CH3). 13C NMR (DMSO-d6):
163.91 (C-6); 160.29 (COO); 151.46 (C-2); 149.82 (C-4); 139.16 (C-4′); 130.62 (C-5′); 99.45
(C-5); 60.90 (OCH2); 49.45 (NCH2); 14.38 (CH3). ESI MS, m/z (%): 264.2 (100) [M–]. ESI MS,
m/z (%): 288.2 (22) [MNa+]. HR ESI MS: for C10H10N5O4 calculated 264.0738; found
264.0735. For C10H11N5O4 (265.23) calculated: 45.28% C, 4.18% H, 26.41% N; found:
45.41% C, 4.35% H, 26.24% N.
Ethyl 1-[(5-chloro-2,6-dioxo-1,2,3,6-tetrahydropyrimidin-4-yl)methyl]-1H-1,2,3-triazole-
4-carboxylate (8b): Yield 250 mg (84%) of white crystals, m.p. >250 °C. 1H NMR (DMSO-d6):
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Polysubstituted 6-[(1H-1,2,3-Triazol-1-yl)methyl]uracils
1129
11.76 bs, 1 H (H-1); 11.61 bs, 1 H (H-3); 8.90 s, 1 H (H-5′); 5.50 s, 2 H (NCH2); 4.31 q, 2 H,
J(CH2,CH3) = 7.1 (OCH2); 1.30 t, 3 H, J(CH3,CH2) = 7.1 (CH3). 13C NMR (DMSO-d6): 160.29
and 160.06 (C-6, COO); 150.10 (C-2); 144.09 (C-4); 138.94 (C-4′); 130.31 (C-5′); 107.97
(C-5); 60.92 (OCH2); 48.47 (NCH2); 14.40 (CH3). ESI MS, m/z (%): 298.1 (100) [M–]. HR ESI
MS: for C10H9ClN5O4 calculated 298.0343; found 298.0346. For C10H10ClN5O4 (299.67)
calculated: 40.08% C, 3.36% H, 23.37% N; found: 40.31% C, 3.54% H, 23.51% N.
6-[(1H-1,2,3-Triazol-1-yl)methyl]pyrimidine-2,4(1H,3H)-dione (9a): Yield 137 mg (71%) of
white crystals, m.p. >250 °C. 1H NMR (DMSO-d6): 11.25 bs, 1 H and 11.15 bs, 1 H (H-1,
H-3); 8.25 s, 1 H (H-5′); 7.82 s, 1 H (H-4′); 5.37 s, 2 H (NCH2); 4.90 s, 1 H (H-5). 13C NMR
(DMSO-d6): 163.92 (C-6); 151.43 (C-2); 150.92 (C-4); 133.90 (C-4′); 126.41 (C-5′); 98.62
(C-5); 48.86 (NCH2). ESI MS, m/z (%): 192.2 (100) [M–]. HR ESI MS: for C7H6N5O2 calculated
192.0527; found 192.0527. For C7H7N5O2 (193.16) calculated: 43.53% C, 3.65% H, 36.26% N;
found: 43.24% C, 3.87% H, 36.09% N.
6-[(1H-1,2,3-Triazol-1-yl)methyl]-5-chloropyrimidine-2,4(1H,3H)-dione (9b): Yield 175 mg
(77%) of white crystals, m.p. >250 °C. 1H NMR (DMSO-d6): 11.76 bs, 1 H (H-1); 11.69 bs,
1 H (H-3); 8.26 s, 1 H (H-5′); 7.79 s, 1 H (H-4′); 5.44 s, 2 H (NCH2). 13C NMR (DMSO-d6):
160.10 (C-6); 150.10 (C-2); 144.88 (C-4); 133.68 (C-4′); 126.14 (C-5′); 107.75 (C-5); 48.00
(NCH2). ESI MS, m/z (%): 226.1 (100) [M–]. HR ESI MS: for C7H5ClN5O2 calculated 226.0137;
found 226.0139. For C7H6ClN5O2 (227.61) calculated: 36.94% C, 2.66% H, 30.77 N; found:
36.78% C, 2.85% H, 30.64% N.
Diisopropyl [({1-[(2,6-dioxo-1,2,3,6-tetrahydropyrimidin-4-yl)methyl]-1H-1,2,3-triazol-4-yl}-
methoxy)methyl]phosphonate (10): Yield 340 mg (85%) of colorless oil. ESI MS, m/z (%): 400.1
(100) [M–]. ESI MS, m/z (%): 402.0 (9) [MH+]; 424.1 (100) [MNa+]. HR ESI MS: for
C
15H23N5O6P calculated 400.1391; found 400.1390. For C15H24N5O6P (401.35) calculated:
44.89% C, 6.03% H, 17.45% N; found: 44.97% C, 6.28% H, 17.26% N.
[({1-[(2,6-Dioxo-1,2,3,6-tetrahydropyrimidin-4-yl)methyl]-1H-1,2,3-triazol-4-yl}methoxy)methyl]-
phosphonic acid (11): A mixture of diisopropyl ester 200 mg (0.5 mmol), acetonitrile (10 ml),
and BrSiMe3 (1 ml) was stirred overnight at room temperature. After evaporation in vacuo
and codistillation with acetonitrile, the residue was treated with water and concentrated
aqueous ammonia was added to the alkaline reaction. The mixture was evaporated to dry-
ness and the residue was applied on a column of Dowex 50 X 8 (H+-form, 20 ml) and
washed with water. Elution with 2.5% aqueous ammonia and evaporation in vacuo afforded
a crude product as ammonium salt. This residue in a minimum volume of water was applied
on a Dowex 1 X 2 (acetate) (25 ml) column, which was then washed with water followed
by a gradient of acetic acid (0–1 M). The main UV-absorbing fraction was evaporated, the
residue was codistilled three times with water and crystallized from water–ethanol to afford
110 mg (69%) of the desired product as white crystals, m.p. >250 °C. 1H NMR (D2O): 8.20 s,
1 H (H-5′); 5.53 d, 2 H, J(CH2,5) = 1.0 (NCH2); 5.44 t, 1 H, J(5,CH2) = 1.0 (H-5); 4.79 s, 2 H
(4′-CH2-O); 3.81 d, 2 H, J(H,C,P) = 9.1 (PCH2). 13C NMR (D2O): 167.13 (C-6); 153.27 (C-2);
151.38 (C-4); 144.67 (C-4′); 126.94 (C-5′); 100.66 (C-5); 65.62 d, J(C,P) = 159.6 (PCH2O);
65.48 d, J(C,O,C,P) = 13.1 (4′-CH2-O); 50.21 (4-CH2-N). ESI MS, m/z (%): 316.1 (100) [M–].
ESI MS, m/z (%): 318.1 (100) [MH+]. HR ESI MS: for C9H11N5O6P calculated 316.0452; found
316.0442. For C9H12N5O6P (317.20) calculated: 34.08% C, 3.81% H, 22.08% N; found
34.01% C, 4.02% H, 21.94% N.
N-({1-[(2,6-Dioxo-1,2,3,6-tetrahydropyrimidin-4-yl)methyl]-1H-1,2,3-triazol-4-yl}methyl)-
formamide (12): Yield 190 mg (76%) of white crystals, m.p. >250 °C. 1H NMR (DMSO-d6):
11.25 bs, 1 H and 11.15 bs, 1 H (H-1, H-3); 8.56 bt, 1 H, J(NH,CH2) = 5.7 (CH2NH); 8.07 s,
Collect. Czech. Chem. Commun. 2011, Vol. 76, No. 9, pp. 1121–1131

1130
Jansa, Špaček, Votruba, Břehová, Dračínský, Klepetářová, Janeba:
2 H (H-5′, CHO); 5.31 d, 2 H, J(CH2,5) = 1.0 (4-CH2-N); 4.95 bs, 1 H (H-5); 4.35 bd, 2 H,
J(CH2,NH) = 5.9 (4′-CH2-NH). 13C NMR (DMSO-d6): 164.04 (C-6); 161.39 (CHO); 151.51
(C-2); 150.93 (C-4); 145.08 (C-4′); 124.41 (C-5′); 98.74 (C-5); 49.09 (4-CH2-N); 33.00
(4′-CH2-NH). ESI MS, m/z (%): 249.2 (100) [M–]. HR ESI MS: for C9H11N6O3 calculated
251.0887; found 251.0886. For C9H10N6O3 (250.21) calculated: 43.20% C, 4.03% H,
33.59% N; found: 43.48% C, 4.17% H, 33.42% N.
Preparation of Disubstituted 6-[(1H-1,2,3-Triazol-1-yl)methyl]uracils
The reaction mixture containing intermediate 4a (1 mmol) was injected into the solution of
but-2-yn-1,4-diol (2 mmol) in 20 ml of DMF under an inert atmosphere of argon. This
mixture was stirred at 120 °C for 3 days to achieve full conversion. The two main products
were separated by column chromatography (silica gel, ethyl acetate/acetone/ethanol/water
30:3:4:3).
6-{[4,5-Bis(hydroxymethyl)-1H-1,2,3-triazol-1-yl]methyl}pyrimidine-2,4(1H,3H)-dione (13):
Yield 90 mg (36%) of white crystals, m.p. >250 °C. 1H NMR (DMSO-d6): 11.12 bs, 1 H (NH);
5.34 s, 2 H (NCH2); 5.15 bt, 1 H, J(OH,CH2) = 5.5 (OH); 4.76 s, 1 H (H-5); 4.62 s, 2 H and
4.53 d, 2 H, J(CH2,OH) = 5.3 (CH2OH). 13C NMR (DMSO-d6): 163.97 (C-6); 151.43 and
151.24 (C-2, C-4); 145.14 (C-4′); 135.17 (C-5′); 97.96 (C-5); 54.32 and 51.00 (CH2OH); 47.43
(CH2N). ESI MS, m/z (%): 252.2 (100) [M–]. HR ESI MS: for C9H10N5O4 calculated 252.0738;
found 252.0738. For C9H11N5O4 (253.21) calculated: 42.69% C, 4.38% H, 27.66% N; found:
42.57% C, 4.58% H, 27.40% N.
2,6-Dioxo-1,2,3,6-tetrahydropyrimidine-4-carboxamide (14): Yield 65 mg (42%) of white crys-
tals, m.p. >250 °C. 1H NMR (DMSO-d6): 11.27 bs, 1 H and 10.57 bs, 1 H (H-1 and H-3);
8.24 bs, 1 H and 8.00 bs, 1 H (NH2); 6.07 s, 1 H (H-5). 13C NMR (DMSO-d6): 164.55 (C-6);
161.82 (CONH2); 150.96 (C-2); 145.02 (C-4); 100.32 (C-5). ESI MS, m/z (%): 154.1 (100) [M–].
HR ESI MS: for C5H4N3O3 calculated 154.0253; found 154.0251. For C5H5N3O3 (155.11)
calculated: 38.72% C, 3.25% H, 27.09% N; found: 38.79% C, 4.36% H, 26.87% N.
This study was performed as a part of Research Project Z40550506 of the Institute of Organic
Chemistry and Biochemistry. It was supported by the Grant Agency of the Academy of Sciences of the
Czech Republic through Project KJB400550903, by the Centre of New Antivirals and Antineoplastics
1M0508, by the Ministry of Education, Youth and Sports of the Czech Republic and by the Gilead
Sciences and IOCB Research Centre.
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