Synthesis and antineoplastic properties of (1H-1,2,3-triazol-1-yl)furazans

Article abstract of DOI:10.1007/s11172-013-0113-2

A method of 3-amino-4-[5-aryl(heteroaryl)-1H-1,2,3-triazol-1-yl)]furazan synthesis was optimized. Condensation of these compounds with 2,5-dimethoxytetrahydrofuran resulted in a series of previously unknown 4-[5-aryl(heteroaryl)-1H-1,2,3-triazol-1-yl)]-3-(pyrrol-1-yl)furazans. All target compounds were evaluated for both antimitotic microtubule destabilizing effect in a phenotypic sea urchin embryo assay and cytotoxicity in a panel of 60 human cancer cell lines. Pyrrolyl derivatives of triazolylfurazans were determined as antiproliferative compounds. The most potent microtubule targeting compounds 7a and 7e are of interest for further trials as antineoplastic agents.

Full text of DOI:10.1007/s11172-013-0113-2

Russian Chemical Bulletin, International Edition, Vol. 62, No. 3, pp. 836—843, March, 2013
836
Synthesis and antineoplastic properties of (1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl)furazans*
A. S. Kulikov,a M. A. Epishina,a L. V. Batog,a V. Yu. Rozhkov,a N. N. Makhova,a
L. D. Konyushkin,a M. N. Semenova,b and V. V. Semenova
a
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences,
47 Leninsky prosp., 119991 Moscow, Russian Federation.
Fax: +7 (499) 135 5328. Eꢀmail: mnn@ioc.ac.ru
bN. K. Kol´tsov Institute of Developmental Biology, Russian Academy of Sciences,
26 ul. Vavilova, 119334 Moscow, Russian Federation.
Fax: +7 (499) 135 8012
A method of 3ꢀaminoꢀ4ꢀ[5ꢀaryl(heteroaryl)ꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl)]furazan synthesis was
optimized. Condensation of these compounds with 2,5ꢀdimethoxytetrahydrofuran resulted in
a series of previously unknown 4ꢀ[5ꢀaryl(heteroaryl)ꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl)]ꢀ3ꢀ(pyrrolꢀ1ꢀ
yl)furazans. All target compounds were evaluated for both antimitotic microtubule destabilizing
effect in a phenotypic sea urchin embryo assay and cytotoxicity in a panel of 60 human cancer
cell lines. Pyrrolyl derivatives of triazolylfurazans were determined as antiproliferative comꢀ
pounds. The most potent microtubule targeting compounds 7a and 7e are of interest for further
trials as antineoplastic agents.
Key words: azidofurazans, 1,3ꢀdicarbonyl compounds, 1,3ꢀdipolar cycloaddition, 2,5ꢀdiꢀ
methoxytetrahydrofuran, 3ꢀamino(pyrrolꢀ1ꢀyl)ꢀ4ꢀ[5ꢀaryl(hetaryl)ꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl]ꢀ
furazans, antineoplastic activity, sea urchin embryos.
Fiveꢀmembered heterocycles are frequently used in the
synthesis of antimitotics that was studied in detail1 for the
analogs of natural compound combretastatin Aꢀ4 (CAꢀ4).
A waterꢀsoluble phosphorylated prodrug of CAꢀ4 is curꢀ
rently undergoes clinical trials in the USA as antitumor
agent.2,3 An introduction of 1,2,3ꢀtriazole (1,2,3ꢀtriꢀ
azolocombretastatin)4,5 and furazan (combretafurazan)6
rings into combretastatin framework was regarded as
a nonꢀisomerizable and metabolically stable bioisosteric
replacement of the double bond in cisꢀstilbenes allowing
the synthesis of new promising anticancer compounds.
Compared to combretastatin, combretafurazan is
a more potent cytotoxic compound in vitro against neuroꢀ
blastoma cells, yet maintaining similar pharmacokinetic
properties.6 1,2,3ꢀTriazoleꢀbridged combretastatin anaꢀ
log4,5 exhibits both strong cytotoxicity against ovarian canꢀ
cer cells and vascular disrupting activity in tumors.6 Moreꢀ
over, this compound is more waterꢀsoluble than combreꢀ
tafurazan.
Waterꢀsoluble biologically active compounds containꢀ
ing both cycles, e.g., (1,2,3ꢀtriazolꢀ1ꢀyl)furazans 1, exꢀ
hibiting other mechanisms of action were synthesized.
Thus, compounds with the (1,2,3ꢀtriazolꢀ1ꢀyl)furazan
moieties inhibit glycogen synthase kinase (GSKꢀ3), a tarꢀ
get in the treatment of Alzheimer’s disease and type 2
diabetes.7 Other analogs of (1,2,3ꢀtriazolꢀ1ꢀyl)furazans
inhibit the SARS CoV Mpro cysteine protease, an imporꢀ
tant enzyme responsible for the intracellular replication of
severe acute respiratory syndrome coronavirus.8a Several
(1,2,3ꢀtriazolꢀ1ꢀyl)furazan derivatives selectively stimuꢀ
* Dedicated to Academician of the Russian Academy of Sciences I. P. Beletskaya on the occasion of her anniversary.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 0835—0842, March, 2013.
1066ꢀ5285/13/6203ꢀ836 © 2013 Springer Science+Business Media, Inc.

Antineoplastic properties of triazolylfurazans
Russ.Chem.Bull., Int.Ed., Vol. 62, No. 3, March, 2013
837
late NOꢀdependent activation of soluble guanylate cyꢀ
clase (sGC).8b
acetates are known. To provide feasible antineoplastic
properties, it is necessary to introduce into the triazolꢀ
ylfurazan structure either alkoxybenzene moieties or
heterocyclic pharmacophores and to remove the esꢀ
ter group.
In the present work we aimed to study a series of (1,2,3ꢀ
triazolꢀ1ꢀyl)furazans 1 as potential antineoplastic agents,
since these compounds can be synthesized by well elaboꢀ
rated methods.9—15 Synthesis of these compounds involved
1,3ꢀdipolar cycloaddition of azidofurazans 2 to various
dipolarophiles, e.g., acetylenes, morpholinonitroethylene,
or compounds with the activated methylene group, e.g.,
activated nitriles and 1,3ꢀdicarbonyl compounds. The disꢀ
advantage of majority of these methods is the formation of
1,2,3ꢀtriazole regioisomers. Depending on the type of
the substituents, dipolarophiles add differently to the
azidofurazans yielding isomeric 4,5ꢀ or 5,4ꢀderivatives
(Scheme 1).
Thereby, the aim of the present work was the optimiꢀ
zation of the synthetic procedure for [5ꢀaryl(hetaryl)ꢀ1Hꢀ
1,2,3ꢀtriazolꢀ1ꢀyl]furazan derivatives and biological
evaluation of the target compounds for antiproliferaꢀ
tive properties. It was also necessary to clarify whether
the regioselectivity of cycloaddition of azidofurazan to
aroyl(hetaroyl)acetates 3 with other aromatic or heteroꢀ
aromatic substituents will be retained. In addition, to
extend the scope of triazolylfurazan derivatives with
potential antineoplastic activity, we used the Clauson—
Kaas pyrrole synthesis involving the reaction of primary
amino group of the furazan ring with dimethoxytetraꢀ
hydrofuran.
Scheme 1
For these purposes, aroylacetic esters 3a—g were inꢀ
volved in the cyclocondensations with aminoazidofurꢀ
azan 2a under conditions developed earlier.10 The 1H and
13C NMR spectra of synthesized triazolylfurazans 4a—g
indicated formation of single regioisomer in high yield; no
signals for the second possible regioisomer were detected.
The spectral characteristics also indicated high purity of
the crude products. Therefore, unpurified esters 4a—g were
hydrolyzed to the corresponding acids 5a—g, which also
without further purification were subsequently thermally
decarboxylated to target 3ꢀaminoꢀ4ꢀ[5ꢀaryl(hetaryl)ꢀ1Hꢀ
1,2,3ꢀtriazolꢀ1ꢀyl]furazans 6a—g in high yields. Thus, we
developed a preparative procedure for the synthesis of triꢀ
azolylfurazans 6a—g without purification of the intermeꢀ
diates (Scheme 2).
2: NH2 (a), Me (b), OMe (c), Ph (d),
(e)
To transform the amino group of triazolylfurazans 6
into the pyrrole ring, compounds 6a—f and 6h15 were
involved in the Clauson—Kaas pyrrole synthesis with
2,5ꢀdimethyltetrahydrofuran. The reaction was carried
out in refluxing acetic acid.14 Pyrroleꢀcontaining triꢀ
azolylfurazans 7a—f,h were obtained in 64—98% yields
(Scheme 3).
The regioselective cycloaddition of aroylacetic esters
to azidofurazans was described; in the cycloaddition prodꢀ
ucts, the aryl substituent and the ester group were located,
respectively, at the positions 5 and 4 of the triazole ring.10
However, only two compounds of this type with Ar = Ph
and 4ꢀClC6H4 synthesized from the corresponding aroylꢀ
Scheme 2
3—6: R = 4ꢀMeOC6H4 (a), 3,4ꢀ(MeO)2C6H3 (b), 3,4,5ꢀ(MeO)3C6H2 (c), 3,4ꢀ(OCH2O)C6H3 (d), 4ꢀEtOC6H4 (e), 4ꢀFC6H4 (f), 2ꢀthienyl (g)
Reagents and conditions: i. MgCO3, EtOH, reflux, 8—10 h; ii. NaOH, H2O, reflux, 1 h; iii. AcOH, reflux, 45 min.

838
Russ.Chem.Bull., Int.Ed., Vol. 62, No. 3, March, 2013
Kulikov et al.
Scheme 3
Table 1. Antiproliferative activity of compounds 4c, 6a—d,g,i
and 7a—f,h
Comꢀ
pound
Sea urchin embryo,
Inhibition of human
EC/mol L–1
cancer cell growth (%)
(GI50/mol L–1
)
Cleavage Cleavage Embryo
alteration
arrest
spinning
4c
6a
6b
6c
6d
6g
6ia
7a
7b
7c
7d
7e
7f
>4
4
>4
>4
>4
>4
>4
>4
>4
0.5
>5
>5
>5
0.5
>4
>4
>4
>4
>4
>4
>4
>4
>4
>5
>5
>5
>4
5
105.15
103.97
95.88
101.33
100.34
102.88
103.66
(0.389)
50.83
>4
>4
>4
>4
>4
0.05
0.5
1
6, 7: R = 4ꢀMeOC6H4 (a), 3,4ꢀ(MeO)2C6H3 (b),
3,4,5ꢀ(MeO)3C6H2 (c), 3,4ꢀ(OCH2O)C6H3 (d),
4ꢀEtOC6H4 (e), 4ꢀFC6H4 (f), 4ꢀClC6H4 (h)
98.26
b
5
0.05
4
—
(0.295)
89.97
99.63
Reagents and conditions: AcOH, reflux, 1 h.
>4
>4
7h
>4
Biological trials
Note. The effect of compounds on the sea urchin embryos was
studied according to the described method.18 Repeated measureꢀ
ments showed no differences in effective threshold concentraꢀ
tion. Inhibition of human cancer cell growth (percentage to
control) was determined for the concentration of the tested comꢀ
pound of 10 mol L–1. GI50 is compound concentration required
for 50% cell growth inhibition. The average GI50 values and
percent of inhibition of cancer cell growth for 60 human cancer
cell lines (NCI60 screen, http://dtp.cancer.gov) are given.
a Compound 6i was kindly provided for the studies by Chemical
Block Ltd (www.chemblock.com).
The biological activity of seven triazolylfurazan derivꢀ
atives bearing amino groups 6a—d,g,i, ester 4c (a precurꢀ
sor of compound 6c), and seven pyrrole derivatives 7a—f,h
was studied. The initial trials were carried out on the
sea urchin embryos widely used as
a model in screening for compounds
with antiproliferative effect.16,17 Reꢀ
cently a simple and efficient phenoꢀ
typic sea urchin embryo assay has
b Not determined.
been developed. The assay allows
identification of compounds with
ester 4c, did not affect cell division in both test systems.
Their analogs 7a—f,h bearing the pyrrole ring instead of
the amino group exhibited moderate activity. The most
potent compounds 7a and 7e altered cleavage of the sea
urchin eggs at concentration of 50 nmol L–1. Compound 7e
caused the sea urchin embryo spinning suggesting the
antitubulin mechanism of action, namely, the ability to
destabilize microtubules. Apparently, compound 7a exꢀ
hibited similar mechanism of action. Although, compound
7a failed to affect the sea urchin embryo swimming, the
arrested eggs acquired tuberculate shape typical of microꢀ
tubule destabilizers.18 The pyrrole ring was shown to be
essential for antiproliferative effect, since the related strucꢀ
tures 6 containing the amino group instead of the pyrrole
ring were inactive. It is worth noting that the increase in
the number of methoxy groups in the benzene ring (comꢀ
pounds 7a—d) resulted in reduction of the antimitotic
properties. In this respect, triazolylfurazans 7 is distinꢀ
guished from the known analogs of plant antimitotics comꢀ
bretastatin and podophyllotoxin interacting with the colꢀ
chicine site of tubulin. Specifically, trimethoxybenzene
antiproliferative properties and proꢀ
vides information about the mechꢀ
anism of antimitotic activity.18 Specific changes of sea
urchin embryo swimming pattern, namely, settlement to
the bottom of the culture vessel and rapid spinning around
the animal—vegetal axis, suggest a microtubule destabiꢀ
lizing activity of a tested compound.* Typical developꢀ
mental abnormalities caused by triazolylfurazan 7 are
shown in Fig. 1.
Note that the compounds at effective concentrations
leading to the alteration of sea urchin egg cleavage were
comparable with the IC50 for the cultured mammalian
and human tumor cells.18,19 Target compounds were further
selected for cytotoxicity test in 60 human tumor cell lines
(Developmental Therapeutics Program at the National
Cancer Institute of USA). The results are given in Table 1.
Triazolylfurazans 6a—d,g,i bearing alkoxybenzene
moieties and the unsubstituted amino group, as well as
* Video illustrations of sea urchin embryo swimming are preꢀ
sented at http://www.chemblock.com.

Antineoplastic properties of triazolylfurazans
Russ.Chem.Bull., Int.Ed., Vol. 62, No. 3, March, 2013
b
839
a
c
Fig. 1. Effect of triazolylfurazans on the sea urchin Paracentrotus lividus embryo development with compound 7e as an example.
(a) Intact blastula. (b) and (c) Typical developmental alterations caused by compound 7e at concentration of 0.1 mol L–1 (b, abnormal
cleavage) and 0.5 mol L–1 (c, arrested tuberculate egg). The observations were carried out 6 h after fertilization. The average embryo
diameter was 115 m.
derivatives of combretastatin and podophyllotoxin exhibit
the strongest antimitotic activity.19,20
dimethoxytetrahydrofuran yielded a series of 4ꢀ[5ꢀarylꢀ
(hetaryl)ꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl]ꢀ(3ꢀpyrrolꢀ1ꢀyl)furazans 7.
The antiproliferative properties of both types of compounds
were evaluated using the sea urchin embryo assay. It was
found that the amino derivatives of triazolylfurazans 6
failed to affect cell division. However, their analogs 7 bearꢀ
ing the pyrrole ring exhibited moderate antimitotic activiꢀ
ty. Two compounds, 7a and 7c, were referred to the NCI
biological expert committee as promising compounds for
further trials.
According to the data of the National Cancer Institute
(NCI) of USA, compounds 7a and 7e inhibited cancer
cell growth at relatively low concentrations (GI50 = 389
and 295 nmol L–1, respectively). These compounds were
referred to the biological expert committee of NCI as
promising for further studies. Leukemia SR cells (7a),
melanoma MDAꢀMBꢀ435 cells (7a and 7e), and the coꢀ
lon cancer cells (7e) were the most sensitive to triazolylꢀ
furazans 7a and 7e. The "doze—effect" curves for seven
colon cancer cell lines exposed to compound 7e are given
in Fig. 2.
Experimental
NMR spectra were recorded on Bruker WMꢀ250 (1H,
250 MHz) and Bruker AMꢀ300 (13C, 75.5 MHz) spectrometers.
Chemical shifts are given in the  scale relative to Me4Si (interꢀ
nal standard). Mass spectra were obtained on a Varian MAT CH 6
instrument (EI, 70 eV). Thinꢀlayer chromatography was perꢀ
formed on Silufol UVꢀ254 plate (elution with CHCl3), spots
were visualized under UV light. Elemental analyses were carried
out on a Perkin—Elmer 2400 CHN analyzer.
In summary, the preparative synthesis of furazans 6 by
1,3ꢀdipolar cycloaddition of azidoaminofurazan 2a to
aroyl(hetaroyl)acetates 3a—g followed by further modifiꢀ
cation was developed. The procedure does not require puꢀ
rification of the intermediates. Subsequent Clauson—Kaas
condensation of synthesized triazolylfurazans 6 with
Ethyl aroylacetates with 4ꢀmethoxyphenylꢀ (3a), 3,4ꢀdiꢀ
methoxyphenylꢀ (3b), 3,4,5ꢀtrimethoxyphenylꢀ (3c), 4ꢀfluoroꢀ
phenyl substituents (3f) were commercially available (Aldrich).
4ꢀAzidofurazanꢀ3ꢀamine (2a), ethyl aroylacetates with 3,4ꢀmeꢀ
thylenedioxyphenylꢀ (3d),21 4ꢀethoxyphenylꢀ (3e),22 and 2ꢀthiꢀ
enyl substituents (3g)23 and 4ꢀ[5ꢀ(4ꢀchlorophenyl)ꢀ1Hꢀ1,2,3ꢀtriꢀ
azolꢀ1ꢀyl]furazaneꢀ3ꢀamine (6h)15 were synthesized by the
known procedures.
Synthesis of ethyl 1ꢀ(4ꢀaminofurazanꢀ3ꢀyl)ꢀ5ꢀRꢀ1Hꢀ1,2,3ꢀ
triazoleꢀ4ꢀcarboxylates 4a—g (general procedure). A mixture of
4ꢀazidofurazanꢀ3ꢀamine 2a (0.88 g, 7 mol), aroylacetate 3a—g
(7 mmol), and MgCO3 (0.34 g, 4 mmol) in ethanol (20 mL) was
refluxed for 8—10 h (until complete consumption of 2a, TLC
monitoring). The reaction mixture was filtered hot, the solvent
was evaporated in vacuo. The precipitate was filtered off, washed
with cold EtOH, and dried in air.
Cell growth (%)
100
GOLO205
50
HCTꢀ15
SWꢀ620
0
HCCꢀ2998
HT29
–50
HCTꢀ116
KM12
–8
–7
–6
–5
C/mol L–1
Fig. 2. Inhibition of colon cancer cell growth (COLO205, HCCꢀ
2998, HCTꢀ116, HCTꢀ15, HT29, KM12, and SWꢀ620 cell lines)
caused by triazolylfurazan 7e. C is concentration of 7e.
Ethyl 1ꢀ(4ꢀaminofurazanꢀ3ꢀyl)ꢀ5ꢀ(4ꢀmethoxyphenyl)ꢀ1Hꢀ
1,2,3ꢀtriazoleꢀ4ꢀcarboxylate (4a). The yield was 96%, m.p.

840
Russ.Chem.Bull., Int.Ed., Vol. 62, No. 3, March, 2013
Kulikov et al.
184—185 C, Rf 0.57. Found (%): C, 50.76; H, 4.40; N, 25.33.
C14H14N6O4. Calculated (%): C, 50.91; H, 4.27; N, 25.44. MS,
m/z (Irel (%)): 330 [M]+ (83); 285 [M – EtO]+ (13); 272 (18);
256 [M – HCO2Et]+ (12); 247 [M – aminofurazanyl + 1]+ (27);
245 (42); 227 (20); 217 (20); 202 (17); 175 [ArCCCO2H – 1]+
(100); 157 (37); 147 (48); 135 (52). 1H NMR (DMSOꢀd6), :
1.30 (t, 3 H, Me, 3J = 4.2 Hz); 3.85 (s, 3 H, OMe); 4.30 (q, 2 H,
Ethyl 1ꢀ(4ꢀaminofurazanꢀ3ꢀyl)ꢀ5ꢀ(4ꢀfluorophenyl)ꢀ1Hꢀ1,2,3ꢀ
triazoleꢀ4ꢀcarboxylate (4f). The yield was 88%, m.p. 150—151 C,
Rf 0.49. Found (%): C, 49.30; H, 3.35; N, 26.36. C13H11FN6O3.
Calculated (%): C, 49.06; H, 3.48; N, 26.41. MS, m/z (Irel (%)):
318 [M]+ (19); 233 [M – CO2 – N3 + 1]+ (44); 214 (15); 205
(32); 163 [ArCCCO2H – 1]+ 100); 135 (18); 133 (23). 1H NMR
(DMSOꢀd6), : 1.28 (t, 3 H, Me, 3J = 4.0 Hz); 4.29 (q, 2 H,
CH2, 3J = 4.0 Hz); 6.41 (s, 2 H, NH2); 7.19, 7.48 (both d,
2 H each, Ar, 3J = 8.2 Hz). 13C NMR (DMSOꢀd6), : 14.31
(Me); 61.19 (CH2); 117.84; 120.66; 134.22; 138.04; 145.18;
146.43; 158.80 (CNH2); 161.22 (CO); 164.52.
3
CH2, J = 4.2 Hz); 6.31 (s, 2 H, NH2); 6.94, 7.34 (both d,
2 H each, Ar, 3J = 8.4 Hz). 13C NMR (DMSOꢀd6), : 13.90
(Me); 55.28 (OMe); 60.79 (CH2); 113.82; 115.41; 131.51; 135.99;
142.32; 143.40; 153.30; 159.83 (CNH2); 160.87 (CO).
Ethyl 1ꢀ(4ꢀaminofurazanꢀ3ꢀyl)ꢀ5ꢀ(3,4ꢀdimethoxyphenyl)ꢀ1Hꢀ
1,2,3ꢀtriazoleꢀ4ꢀcarboxylate (4b). The yield was 82%, m.p.
192—194 C, Rf 0.62. Found (%): C, 50.19; H, 4.34; N, 23.22.
C15H16N6O5. Calculated (%): C, 50.00; H, 4.48; N, 23.32. MS, m/z
(Irel (%)): 360 [M]+ (89); 315 [M – EtO]+ (3); 275 [M – aminoꢀ
furazanyl – 1]+ (25); 256 (26); 247 (71); 205 [ArCCCO2H – 1]+
(71); 177 (100); 149 (18). 1H NMR (DMSOꢀd6), : 1.28 (t, 3 H,
Me, 3J = 4.2 Hz); 3.73, 3.83 (both s, 3 H each, 2 OMe); 4.31
(q, 2 H, CH2, 3J = 4.2 Hz); 6.51 (s, 2 H, NH2); 6.96, 7.02
(both d, 2 H, Ar, 3J = 8.0 Hz); 7.03 (s, 1 H, Ar). 13C NMR
(DMSOꢀd6), : 14.06 (Me); 55.33 (OMe); 55.43 (OMe); 60.58
(CH2); 111.35; 112.44; 127.70; 130.01; 141.88; 142.93; 147.17;
153.22; 158.64 (CNH2); 161.12 (CO).
Ethyl 1ꢀ(4ꢀaminofurazanꢀ3ꢀyl)ꢀ5ꢀ(2ꢀthienyl)ꢀ1Hꢀ1,2,3ꢀtriaꢀ
zoleꢀ4ꢀcarboxylate (4g). The yield was 85%, m.p. 130—131 C,
Rf 0.63. Found (%): C, 43.03; H, 3.20; N, 27.31. C11H10N6O3S.
Calculated (%): C, 43.13; H, 3.29; N, 27.44. MS, m/z (Irel (%)):
306 [M]+ (21); 221 [M – CO2 – N3 + 1]+ (14); 202 (15);
151 [ArCCCO2H – 1]+ (79); 135 (16); 133 (18). 1H NMR
(DMSOꢀd6), : 1.34 (t, 3 H, Me, 3J = 4.2 Hz); 4.36 (q, 2 H,
CH2, 3J = 4.2 Hz); 6.50 (s, 2 H, NH2); 7.15 (m, 1 H, C(4)
thiophene ring); 7.44 (d, 1 H, C(3) thiophene ring, 3J = 5.0 Hz);
7.77 (d, 1 H, C(5) thiophene ring, 3J = 5.0 Hz). 13C NMR
(DMSOꢀd6), : 13.42 (Me); 60.81 (CH2); 115.17; 123.89; 132.31;
134.17; 135.68; 142.71; 43.52; 158.16 (CNH2); 160.69 (CO).
Synthesis of 1ꢀ(4ꢀaminofurazanꢀ3ꢀyl)ꢀ5ꢀRꢀ1Hꢀ1,2,3ꢀtriꢀ
azoleꢀ4ꢀcarboxylic acids 5a—g (general procedure). A solution of
NaOH (0.5 g, 12.5 mol) in water (50 mL) was added to ethyl
1ꢀ(4ꢀaminofurazanꢀ3ꢀyl)ꢀ5ꢀRꢀ1Hꢀ1,2,3ꢀtriazoleꢀ4ꢀcarboxylate
4a—g (7 mmol). The reaction mixture was refluxed for 1 h, the
undissolved residue was filtered off, and the filtrate was acidified
with dilute HCl to pH 2. A precipitate was filtered off, washed
with water, and dried in air.
When crude carboxylic acids 4a—g (unwashed with EtOH)
were used, the yields of products 5a—g were virtually the same.
1ꢀ(4ꢀAminofurazanꢀ3ꢀyl)ꢀ5ꢀ(4ꢀmethoxyphenyl)ꢀ1Hꢀ1,2,3ꢀtriꢀ
azoleꢀ4ꢀcarboxylic acid (5a). The yield was 83%, m.p. 143—145 C.
Found (%): C, 47.47; H, 3.41; N, 27.74. C12H10N6O4. Calculatꢀ
ed (%): C, 47.69; H, 3.33; N, 27.81. MS, m/z (Irel (%)): 302 [M]+
(1); 259 [M – HN3]+ (23); 258 [M – CO2]+ (95); 231 (32); 230
[M – CO2 – N2]+ (70); 175 [ArCCCO2H – 1] (69); 158 (100).
1H NMR (DMSOꢀd6), : 3.76 (s, 3 H, OMe); 6.64 (s, 2 H,
NH2); 6.98, 7.32 (both d, 2 H each, Ar, 3J = 8.0 Hz); 13.40 (br.s,
1 H, OH). 13C NMR (DMSOꢀd6), : 55.27 (OMe); 113.84;
115.81; 131.53; 136.85; 142.45; 143.10; 153.33; 160.76 (CNH2);
161.36 (CO).
Ethyl 1ꢀ(4ꢀaminofurazanꢀ3ꢀyl)ꢀ5ꢀ(3,4,5ꢀtrimethoxyphenyl)ꢀ
1Hꢀ1,2,3ꢀtriazoleꢀ4ꢀcarboxylate (4c). The yield was 94%, m.p.
186—187 C, Rf 0.47. Found (%): C, 49.12; H, 4.62; N, 21.58.
C16H18N6O6. Calculated (%): C, 49.28; H, 4.65; N, 21.53. MS,
m/z (Irel (%)): 390 [M]+ (90); 305 [M – aminofurazanyl – 1]+
(29); 286 (15); 235 [ArCCCO2H – 1]+ (39); 207 (100); 177
1
3
(15). H NMR (DMSOꢀd6), : 1.28 (t, 3 H, Me, J = 4.0 Hz);
3.74 (s, 6 H, 2 OMe, C(3) and C(5) in Ar); 3.76 (s, 3 H, OMe,
C(4) in Ar); 4.31 (q, 2 H, CH2, 3J = 4.0 Hz); 6.62 (s, 2 H, NH2);
6.76 (s, 2 H, Ar). 13C NMR (DMSOꢀd6), : 13.67 (Me); 56.04
(OMe); 60.15 (OMe); 60.89 (CH2); 108.18; 119.85; 136.15;
139.12; 141.98; 145.13; 153.30; 157.72 (CNH2); 160.79 (CO).
Ethyl 1ꢀ(4ꢀaminofurazanꢀ3ꢀyl)ꢀ5ꢀ(3,4ꢀmethylenedioxypheꢀ
nyl)ꢀ1Hꢀ1,2,3ꢀtriazoleꢀ4ꢀcarboxylate (4d). The yield was 95%,
m.p. 178—179 C, Rf 0.56. Found (%): C, 49.01; H, 3.61;
N, 24.27. C14H12N6O5. Calculated (%): C, 48.84; H, 3.51;
N, 24.41. MS, m/z (Irel (%)): 344 [M]+ (21); 259 (18); 231 (19);
189 [ArCCCO2H – 1]+ (100); 170 (22); 161 (74). 1H NMR
(DMSOꢀd6), : 1.25 (t, 3 H, Me, 3J = 4.3 Hz); 4.30 (q, 2 H,
3
CH2, J = 4.3 Hz); 6.09 (s, 2 H, OCH2O); 6.56 (s, 2 H, NH2);
6.86—6.99 (m, 3 H, Ar). 13C NMR (DMSOꢀd6), : 13.91 (Me);
60.36 (OCH2); 101.70 (OCH2O); 108.95; 113.36; 115.55;
124.33; 125.23; 137.49; 143.15; 149.11; 149.46; 156.80 (CNH2);
161.12 (CO).
1ꢀ(4ꢀAminofurazanꢀ3ꢀyl)ꢀ5ꢀ(3,4ꢀdimethoxyphenyl)ꢀ1Hꢀ
1,2,3ꢀtriazoleꢀ4ꢀcarboxylic acid (5b). The yield was 54%, m.p.
162—163 C. Found (%): C, 47.14; H, 3.50; N, 25.40. C13H12N6O5.
Calculated (%): C, 46.99; H, 3.64; N, 25.29. MS, m/z (Irel (%)):
332 [M]+ (2); 288 [M – CO2]+ (71); 260 [M – CO2 – N2]+ (38);
245 [M – aminofurazanyl – 1]+ (34); 182 (74); 176 (100).
1H NMR (DMSOꢀd6), : 3.70, 3.82 (both s, 3 H each, 2 OMe);
6.67 (s, 2 H, NH2); 6.91—7.12 (m, 3 H, Ar); 13.15 (br.s, 1 H,
OH). 13C NMR (DMSOꢀd6), : 55.48 (OMe); 55.62 (OMe);
110.97; 111.29; 113.48; 123.01; 136.66; 142.51; 143.21; 148.29;
150.35; 153.45; 161.31 (CO).
1ꢀ(4ꢀAminofurazanꢀ3ꢀyl)ꢀ5ꢀ(3,4,5ꢀtrimethoxyphenyl)ꢀ1Hꢀ
1,2,3ꢀtriazoleꢀ4ꢀcarboxylic acid (5c). The yield was 82%, m.p.
153—155 C. Found (%): C, 46.56; H, 3.75; N, 23.38. C14H14N6O6.
Calculated (%): C, 46.41; H, 3.89; N, 23.20. MS, m/z (Irel (%)): 362
[M]+ (1); 318 [M – CO2]+ (43); 275 [M – aminofurazanyl – 1]+
(100); 206 (30). 1H NMR (DMSOꢀd6), : 3.50—3.70 (br.s, 9 H,
Ethyl 1ꢀ(4ꢀaminofurazanꢀ3ꢀyl)ꢀ5ꢀ(4ꢀethoxyphenyl)ꢀ1Hꢀ1,2,3ꢀ
triazoleꢀ4ꢀcarboxylate (4e). The yield was 94%, m.p. 140—141 C,
Rf 0.60. Found (%): C, 52.03; H, 4.57; N, 24.21. C15H16N6O4.
Calculated (%): C, 52.32; H, 4.68; N, 24.41. MS, m/z (Irel (%)):
344 [M]+ (28); 286 (11); 259 (35); 240 (17); 231 (35); 189
[ArCCCO2H – 1]+ (100); 161 (94). 1H NMR (DMSOꢀd6),
: 1.29 (t, 3 H, MeCH2OCO, 3J = 4.0 Hz); 1.42 (t, 3 H, MeCH2O,
3J = 4.1 Hz); 4.08 (q, 2 H, MeCH2O, 3J = 4.1 Hz); 4.30 (q, 2 H,
MeCH2OCO, 3J = 4.0 Hz); 6.37 (s, 2 H, NH2); 6.92, 7.32
(both d, 2 H each, Ar, 3J = 8.2 Hz). 13C NMR (DMSOꢀd6),
: 13.34 (Me); 13.78 (Me); 60.36 (CO2CH2); 62.15 (ArOCH2);
110.62; 114.11; 132.37; 137.98; 142.56; 146.60; 155.24; 158.12
(CNH2); 161.00 (CO).

Antineoplastic properties of triazolylfurazans
Russ.Chem.Bull., Int.Ed., Vol. 62, No. 3, March, 2013
841
3 OMe and 1 H, OH); 6.82 (br.s, 4 H, 2 H in Ar and 2 H,
NH2). 13C NMR (DMSOꢀd6), : 56.03 (OMe); 60.12 (OMe);
107.78; 119.13; 136.91; 138.92; 142.48; 143.13; 152.50; 153.63;
161.22 (CO).
Found (%): C, 50.26; H, 3.99; N, 29.19. C12H12N6O3. Calculatꢀ
ed (%): C, 50.00; H, 4.20; N, 29.15. MS, m/z (Irel (%)): 288 [M]+
(94); 260 [M – N2]+ (42); 245 [M – HN3]+ (92); 203 (28); 188
(48); 176 (100); 162 [ArCCH]+ (42). 1H NMR (DMSOꢀd6),
: 3.72 (s, 3 H, OMe); 3.82 (s, 3 H, OMe); 6.68 (s, 2 H, NH2);
1ꢀ(4ꢀAminofurazanꢀ3ꢀyl)ꢀ5ꢀ(3,4ꢀmethylenedioxyphenyl)ꢀ1Hꢀ
1,2,3ꢀtriazoleꢀ4ꢀcarboxylic acid (5d). The yield was 90%,
m.p. 176—177 C. Found (%): C, 45.33; H, 2.42; N, 26.50.
C12H8N6O5. Calculated (%): C, 45.58; H, 2.55; N, 26.58. MS, m/z
(Irel (%)): 316 [M]+ (2); 273 [M – HN3]+ (18); 272 [M – CO2]+
(60); 244 [M – CO2 – N2]+ (55); 229 [M – aminofurazanyl – 1]+
(100). 1H NMR (DMSOꢀd6), : 3.0—4.0 (br.s, OH); 6.10 (s, 2 H,
CH2); 6.68 (s, 2 H, NH2); 6.82—7.07 (m, 3 H in Ar). 13C NMR
(DMSOꢀd6), : 101.77 (CH2); 108.78; 110.29; 117.24; 122.95;
124.94; 137.27; 142.68; 147.45; 148.99; 153.28; 161.44 (CO).
1ꢀ(4ꢀAminofurazanꢀ3ꢀyl)ꢀ5ꢀ(4ꢀethoxyphenyl)ꢀ1Hꢀ1,2,3ꢀtriꢀ
azoleꢀ4ꢀcarboxylic acid (5e). The yield was 89%, m.p. 133—134 C.
Found (%): C, 49.22; H, 3.88; N, 26.61. C13H12N6O4. Calculatꢀ
ed (%): C, 49.37; H, 3.82; N, 26.51. MS, m/z (Irel (%)): 316 [M]+
(4); 273 [M – HN3]+ (18); 272 [M – CO2]+ (80); 245 (15); 244
[M – CO2 – N2]+ (62); 175 [ArCCCO2H – 1]+ (51); 172
(100). 1H NMR (DMSOꢀd6), : 1.44 (t, 3 H, MeCH2O,
3J = 4.7 Hz); 4.08 (q, 2 H, MeCH2O, 3J = 4.7 Hz); 6.62 (s, 2 H,
NH2); 6.93, 7.28 (both d, 2 H each, Ar, 3J = 8.2 Hz); 13.15 (br.s,
1 H, OH). 13C NMR (DMSOꢀd6), : 13.72 (Me); 60.40 (CH2);
111.95; 114.90; 131.17; 137.27; 142.04; 143.52; 153.88; 160.46
(CNH2); 161.55 (CO).
1ꢀ(4ꢀAminofurazanꢀ3ꢀyl)ꢀ5ꢀ(4ꢀfluorophenyl)ꢀ1Hꢀ1,2,3ꢀtriꢀ
azoleꢀ4ꢀcarboxylic acid (5f). The yield was 79%, m.p. 170—171 C.
Found (%): C, 45.45; H, 2.38; N, 28.80. C11H7FN6O3. Calcuꢀ
lated (%): C, 45.52; H, 2.43; N, 28.96. MS, m/z (Irel (%)): 290
[M]+ (11); 246 [M – HN3 – 1]+ (16); 218 [M – CO2 – N2]+
(24); 163 (26); 146 (27); 134 (100). 1H NMR (DMSOꢀd6), : 6.40
(s, 2 H, NH2); 7.20, 7.48 (both d, 2 H each, Ar, 3J = 8.0 Hz);
12.96 (br.s, 1 H, OH). 13C NMR (DMSOꢀd6), : 118.20;
121.06; 134.83; 139.26; 147.33; 147.53; 159.00 (CNH2); 160.65
(CO); 164.26.
1ꢀ(4ꢀAminofurazanꢀ3ꢀyl)ꢀ5ꢀ(2ꢀthienyl)ꢀ1Hꢀ1,2,3ꢀtriazoleꢀ4ꢀ
carboxylic acid (5g). The yield was 66%, m.p. 174—175 C.
Found (%): C, 39.05; H, 2.28; N, 30.12. C9H6N6O3S. Calculatꢀ
ed (%): C, 38.85; H, 2.17; N, 30.20. MS, m/z (Irel (%)): 278 [M]+
(22); 234 [M – CO2]+ (24); 206 (14); 202 (14); 151 (25); 134
(31); 122 (100). 1H NMR (DMSOꢀd6), : 6.43 (s, 2 H, NH2);
7.13 (m, 1 H, C(4) thiophene ring); 7.44 (d, 1 H, C(3) thiophene
ring, 3J = 5.2 Hz); 7.73 (d, 1 H, C(5) thiophene ring, 3J = 5.2 Hz).
Synthesis of 3ꢀaminoꢀ4ꢀ(5ꢀRꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl)furazans
6 (general procedure). A solution of carboxylic acid 5a—g
(10 mmol) in AcOH (20 mL) was refluxed for 45 min. The reacꢀ
tion mixture was cooled, concentrated in vacuo, and water
(50 mL) was added to the residue. A precipitate was filtered off,
washed with water, and dried in air.
4ꢀ[5ꢀ(4ꢀMethoxyphenyl)ꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl]furazanꢀ3ꢀ
amine (6a). The yield was 71%, m.p. 166—167 C, Rf 0.10.
Found (%): C, 51.22; H, 3.81; N, 32.43. C11H10N6O2. Calculatꢀ
ed (%): C, 51.16; H, 3.90; N, 32.54. MS, m/z (Irel (%)): 258 [M]+
(7); 230 [M – N2]+ (12); 158 (10); 146 (100). 1H NMR (DMSOꢀd6),
: 3.79 (s, 3 H, OMe); 6.65 (s, 2 H, NH2); 7.05, 7.35 (both d, 4 H
in Ar, 3J = 8.0 Hz); 8.23 (s, 1 H, triazole ring). 13C NMR
(DMSOꢀd6), : 55.30 (OMe); 114.55; 116.78; 129.68; 132.60;
139.85; 143.13; 153.19; 160.49.
3
6.91, 7.08 (both d, 2 H in Ar, J = 7.5 Hz); 7.04 (s, 1 H, in Ar);
8.28 (s, 1 H, triazole ring). 13C NMR (DMSOꢀd6), : 55.48
(OMe); 55.53 (OMe); 111.68; 111.95; 116.80; 120.91; 132.56;
140.08; 148.73; 150.14; 153.34.
4ꢀ[5ꢀ(3,4,5ꢀTrimethoxyphenyl)ꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl]furꢀ
azanꢀ3ꢀamine (6c). The yield was 69%, m.p. 213—214 C, Rf 0.11.
Found (%): C, 48.88; H, 4.61; N, 22.69. C13H14N6O4. Calculatꢀ
ed (%): C, 49.06; H, 4.43; N, 22.82. MS, m/z (Irel (%)): 318 [M]+
(77); 290 [M – N2]+ (8); 275 [M – HN3]+ (100); 235 (14); 217
(18); 206 (44); 192 (29); 206 (43); 192 [ArCCH]+ (29). 1H NMR
(DMSOꢀd6), : 3.70 (s, 3 H, OMe); 3.73 (s, 6 H, 2 OMe); 6.74
(s, 2 H in Ar); 6.75 (s, 2 H, NH2); 8.32 (s, 1 H, triazole ring).
13C NMR (DMSOꢀd6), : 56.04 (OMe); 60.13 (OMe); 105.93;
119.91; 132.95; 140.14; 143.21; 153.10; 153.47.
4ꢀ[5ꢀ(3,4ꢀMethylenedioxyphenyl)ꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl]ꢀ
furazanꢀ3ꢀamine (6d). The yield was 53%, m.p. 192—193 C,
Rf 0.13. Found (%): C, 48.51; H, 2.83; N, 31.11. C11H8N6O3.
Calculated (%): C, 48.53; H, 2.96; N, 30.87. MS, m/z (Irel (%)):
272 [M]+ (67); 244 [M – N2]+ (62); 186 (14); 172 (19); 160
(100). 1H NMR (DMSOꢀd6), : 6.08 (s, 2 H, CH2); 6.67 (s, 2 H,
NH2); 6.74, 7.02 (both d, 2 H, in Ar, J = 7.5 Hz); 7.00 (s, 1 H,
CH in Ar); 8.22 (s, 1 H, triazole ring). 13C NMR (DMSOꢀd6),
: 101.83 (CH2); 108.46; 108.87; 118.16; 122.62; 132.99; 139.78;
143.07; 147.76; 148.81; 153.20.
4ꢀ[5ꢀ(4ꢀEthoxyphenyl)ꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl]furazanꢀ3ꢀ
amine (6e). The yield was 63%, m.p. 158—159 C, Rf 0.10.
Found (%): C, 52.41; H, 4.59; N, 31.02. C12H12N6O2. Calculatꢀ
ed (%): C, 52.94; H, 4.44; N, 30.87. MS, m/z (Irel (%)): 272 [M]+
(5); 244 [M – N2]+ (16); 214 (30); 172 (21); 160 (100); 146
[ArCCH]+ (37). 1H NMR (DMSOꢀd6), : 1.42 (t, 3 H, MeCH2O,
J = 6.4); 4.07 (q, 2 H, MeCH2O, J = 6.4); 6.58 (s, 2 H, NH2);
6.97, 7.30 (both d, 2 H each, Ar, J = 8.3 Hz); 8.18 (s, 1 H,
triazole ring). 13C NMR (DMSOꢀd6), : 13.50 (Me); 62.07
(OCH2); 112.15; 114.92; 131.08; 136.44; 142.07; 147.26;
153.61; 158.48.
4ꢀ[5ꢀ(4ꢀFluorophenyl)ꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl]furazanꢀ3ꢀamine
(6f). The yield was 68%, m.p. 191—192 C, Rf 0.11. Found (%):
C, 48.23; H, 3.01; N, 34.36. C10H7FN6O. Calculated (%): C,
48.48; H, 2.87; N, 34.13. MS, m/z (Irel (%)): 246 [M]+ (45); 218
[M – N2]+ (13); 188 (23); 176 (20); 134 (100%); 120 [ArCCH]+
(66). 1H NMR (DMSOꢀd6), : 6.63 (s, 2 H, NH2); 7.22, 7.49
(both d, 2 H each, Ar, J = 8.3 Hz); 8.33 (s, 1 H, triazole ring).
13C NMR (DMSOꢀd6), : 118.90; 121.56; 135.79; 114.92; 141.21;
145.38; 148.54; 158.60; 164.92.
4ꢀ[5ꢀ(2ꢀThienyl)ꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl]furazanꢀ3ꢀamine
(6g). The yield was 73%, m.p. 81—82 C, Rf 0.13. Found (%):
C, 41.21; H, 2.47; N, 36.02. C8H6N6OS. Calculated (%):
C, 41.02; H, 2.58; N, 35.88. 1H NMR (DMSOꢀd6), : 6.63 (s, 2 H,
NH2); 7.20 (m, 1 H, C(4) thiophene ring); 7.40 (d, 1 H, C(3)
thiophene ring, 3J = 5.0 Hz); 7.77 (d, 1 H, C(2) thiophene ring,
3J = 5.0 Hz); 8,36 (s, 1 H, triazole ring). 13C NMR (DMSOꢀd6),
: 118.15; 123.92; 133.26; 135.21; 138.62; 145.05; 146.37; 158.93.
3ꢀ[5ꢀ(5ꢀChloroꢀ2ꢀthienyl)ꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl]furazanꢀ3ꢀ
amine (6i). M.p. 127—128 C, Rf 0.08. Found (%): C, 48.66;
H, 2.75; N, 34.00. C8H5ClN6OS. Calculated (%): C, 35.76;
H, 1.88; N, 31.28. MS, m/z (Irel (%)): 270 [M(Cl37)]+ (6); 268
4ꢀ[5ꢀ(3,4ꢀDimethoxyphenyl)ꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl]furazanꢀ
3ꢀamine (6b). The yield was 85%, m.p. 181—182 C, Rf 0.12.

842
Russ.Chem.Bull., Int.Ed., Vol. 62, No. 3, March, 2013
Kulikov et al.
[M(Cl35)]+ (18); 268; 242 [M(Cl37) – N2]+ (4); 240 [M(Cl35) –
– N2]+ (11); 198 (12); 170 (8); 168 (23); 158 (41); 156 (100).
1H NMR (DMSOꢀd6), : 6.76 (s, 2 H, NH2); 7.27, 7.85 (both m,
2 H, thiophene ring); 8.44 (s, 1 H, triazole ring). 13C NMR
(DMSOꢀd6), : 120.31; 125.18; 134.16; 137.72; 140.33; 146.21;
147.57; 160.13.
Found (%): C, 59.80; H, 4.29; N, 26.19. C16H14N6O2. Calculatꢀ
ed (%): C, 59.62; H, 4.38; N, 26.07. MS, m/z (Irel (%)): 322 [M]+
(32); 294 [M – N2]+ (53); 264 (21); 236 (38); 209 (52); 144
[ArCCH]+ (28); 132 (100). 1H NMR (DMSOꢀd6), : 1.31
(t, 3 H, Me, 3J = 7.0 Hz); 4.05 (q, 2 H, CH2, 3J = 7.0 Hz); 6.35
(s, 2 H, C(3) and C(4) of pyrrole ring); 6.83 (s, 2 H, C(2) and
C(5) of pyrrole ring); 6.98, 7.32 (both d, 2 H each, Ar, J = 8.4 Hz);
8.37 (s, 1 H, triazole ring). 13C NMR (CDCl3), : 13.90 (Me);
62.26 (OCH2); 113.25; 114.72; 117.33; 130.11; 133.18; 142.52;
143.92; 148.70; 161.08.
Synthesis of 4ꢀ(5ꢀRꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl)ꢀ3ꢀ(pyrrolꢀ1ꢀ
yl)furazans 7 (general procedure). A solution of 3ꢀaminoꢀ4ꢀ(5ꢀ
Rꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl)furazan 6 (2.0 mmol) and 2,5ꢀdiꢀ
methoxytetrahydrofuran (2.64 g, 2.0 mmol) in AcOH (10 mL)
was refluxed for 1 h, the reaction mixture was concentrated. The
residue was diluted with water (10 mL), extracted with CH2Cl2
(4×20 mL), dried with MgSO4. The filtered solution was passed
through a layer of SiO2 and the solvent was removed to dryness.
4ꢀ[5ꢀ(4ꢀMethoxyphenyl)ꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl]ꢀ3ꢀ(pyrrolꢀ
1ꢀyl)furazan (7a). The yield was 83%, m.p. 71—72 C, Rf 0.51.
Found (%): C, 58.80; H, 3.79; N, 27.39. C15H12N6O2. Calculatꢀ
ed (%): C, 58.44; H, 3.92; N, 27.26. MS, m/z (Irel (%)): 308 [M]+
(19); 281 [M – N2 + 1]+ (89); 250 (29); 224 (33); 208 (36); 158
4ꢀ[5ꢀ(4ꢀFluorophenyl)ꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl]ꢀ3ꢀ(pyrrolꢀ1ꢀ
yl)furazan (7f). The yield was 80%, m.p. 122—123 C, Rf 0.52.
Found (%): C, 56.59; H, 2.98; N, 28.19. C14H9FN6O. Calculatꢀ
ed (%): C, 56.76; H, 3.06; N, 28.37. MS, m/z (Irel (%)): 296 [M]+
(17); 268 [M – N2]+ (80); 267 (24); 238 (51); 211 (100); 185
(58); 146 (28); 134 (74); 126 (76); 120 [ArCCH]+ (64); 107
1
(79). H NMR (DMSOꢀd6), : 6.35 (s, 2 H, C(3) and C(4) of
pyrrole ring); 6.83 (s, 2 H, C(2) and C(5) of pyrrole ring); 7.28,
7.49 (both d, 2 H each, Ar, J = 8.2 Hz); 8.40 (s, 1 H, triazole
ring). 13C NMR (CDCl3), : 115.39; 117.16; 132.40; 137.73;
144.18; 145.62; 148.95; 162.29; 164.80.
1
(62); 146 (85); 135 (100); 115 (45). H NMR (CDCl3), : 3.82
(s, 3 H, OMe); 6.31 (br.s, 2 H, C(3) and C(4) of pyrrole ring);
6.68 (br.s, 2 H, C(2) and C(5) of pyrrole ring); 6.88, 7.16 (both d,
4ꢀ[5ꢀ(4ꢀChlorophenyl)ꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl]ꢀ3ꢀ(pyrrolꢀ1ꢀ
yl)furazan (7h). The yield was 76%, m.p. 97—98 C, Rf 0.44.
Found (%): C, 53.44; H, 3.01; N, 27.03. C14H9ClN6O. Calcuꢀ
lated (%): C, 53.77; H, 2.90; N, 26.87. MS, m/z (Irel (%)): 314
[M(Cl37)]+ (3); 312 [M(Cl35)]+ (13); 286 [M(Cl37) – N2]+ (18);
284 [M(Cl35) – N2]+ (53); 256 (11); 254 (40); 229 (11); 227 (36);
219 (46); 192 (96); 167 (37); 150 (53); 138 (13); 136 (33). 1H NMR
(DMSOꢀd6), : 6.33 (s, 2 H, C(3) and C(4) of pyrrole ring); 6.84
(s, 2 H, C(2) and C(5) of pyrrole ring); 7.45, 7.51 (both d,
2 H each, Ar, 3J = 8.6 Hz); 8.44 (s, 1 H, triazole ring).
Study of antiproliferative activity of compounds using a sea
urchin embryo assay.18 The trials were carried out in the biologiꢀ
cal laboratory of N. K. Kol´tsov Institute of Developmental Biꢀ
ology of RAS in Cyprus. Adult sea urchins, Paracentrotus lividus L.
(Echinidae), were collected from the Mediterranean Sea on the
Cyprus coast and kept in an aerated seawater tank. Gametes
were obtained by intracoelomic injection of 0.5 M KCl (1—2 mL).
Eggs were washed with filtered seawater and fertilized by adding
drops of diluted sperm. Embryos (600—2000 mL–1) were culꢀ
tured in filtered seawater at room temperature (18—23 C) in
sixꢀwell culture plates.
3
4 H in Ar, J = 8.0 Hz); 7.94 (s, 1 H, triazole ring). 13C NMR
(CDCl3), : 55.50 (OMe); 113.71; 114.93; 116.12; 129.88; 132.82;
141.44; 143.61; 149.11; 161.38.
4ꢀ[5ꢀ(3,4ꢀDimethoxyphenyl)ꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl]ꢀ3ꢀ(pyrꢀ
rolꢀ1ꢀyl)furazan (7b). The yield was 98%, m.p. 80—81 C, Rf 0.50.
Found (%): C, 56.66; H, 4.05; N, 24.77. C16H14N6O3. Calculatꢀ
ed (%): C, 56.80; H, 4.17; N, 24.84. MS, m/z (Irel (%)): 338 [M]+
(90); 310 [M – N2]+ (24); 295 [M – HN3]+ (13); 288 (100); 280
(27); 264 (38); 245 (48); 176 (60). 1H NMR (CDCl3), : 3.75
(s, 3 H, OMe); 3.88 (s, 3 H, OMe); 6.32 (s, 2 H, C(3) and C(4) of
pyrrole ring); 6.68 (s, 2 H, C(2) and C(5) of pyrrole ring); 6.70,
6.82 (both d, 4 H in Ar, 3J = 8.2 Hz); 7.95 (s, 1 H, triazole ring).
13C NMR (CDCl3), : 55.92 (OMe); 55.98 (OMe); 111.15;
111.57; 113.64; 116.15; 119.61; 121.48; 132.73; 141.43; 143.60;
149.08; 149.44; 150.91.
4ꢀ[5ꢀ(3,4,5ꢀTrimethoxyphenyl)ꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl]ꢀ3ꢀ
(pyrrolꢀ1ꢀyl)furazan (7c). The yield was 83%, m.p. 118—119 C,
Rf 0.44. Found (%): C, 55.47; H, 4.45; N, 22.70. C17H16N6O4.
Calculated (%): C, 55.43; H, 4.38; N, 22.82. MS, m/z (Irel (%)):
368 [M]+ (100); 340 [M – N2]+ (19); 325 [M – HN3]+ (13); 309
(13); 280 (21); 206 (41). 1H NMR (CDCl3), : 3.72 (s, 6 H,
2 OMe); 3.86 (s, 3 H, OMe); 6.31 (s, 2 H, C(3) and C(4) of
pyrrole ring); 6.40 (s, 2 H, C(2) and C(5) of pyrrole ring); 6.65
(s, 2 H in Ar); 7.97 (s, 1 H, triazole ring). 13C NMR (CDCl3),
: 56.09 (OMe); 60.80 (OMe); 106.73; 113.63; 118.82; 119.52;
132.83; 139.85; 141.37; 143.47; 149.04; 153.63.
4ꢀ[5ꢀ(3,4ꢀMethylenedioxyphenyl)ꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl]ꢀ3ꢀ
(pyrrolꢀ1ꢀyl)furazan (7d). The yield was 64%, m.p. 102—103 C,
Rf 0.44. Found (%): C, 56.07; H, 3.05; N, 26.17. C15H10N6O3.
Calculated (%): C, 55.90; H, 3.13; N, 26.08. MS, m/z (Irel (%)):
322 [M]+ (42); 294 [M – N2]+ (100); 264 (57); 237 (14); 207
(32); 179 (40). 1H NMR (CDCl3), : 5.99 (s, 2 H, CH2); 6.32 (s,
2 H, C(3) and C(4) of pyrrole ring); 6.64—6.80 (m, 2 H, C(2)
and C(5) of pyrrole ring, 3 H, Ar); 7.92 (s, 1 H, triazole ring).
13C NMR (CDCl3), : 101.92 (CH2); 108.50; 109.12; 113.70;
117.32; 119.68; 122.94; 132.99; 141.25; 143.44; 148.49; 149.02;
149.68.
Stock solutions of compounds were prepared in DMSO or
95% aqueous ethanol, the maximal studied concentrations of the
compounds depended on their solubility. The solubility of comꢀ
pounds in the solvents and seawater was controlled under microꢀ
scope.
Compound treatment was carried out at the following develꢀ
opmental steps: (1) fertilized eggs, 8—15 min after fertilization;
(2) hatched swimming blastulae, 8.5—10 h after fertilization.
Aliquots of embryo suspension (5 mL) were transferred into each
well followed by addition of the corresponding amount of comꢀ
pound solution to obtain the required final concentration. The
concentration of the solvent did not exceed the maximal toleratꢀ
ed value (1% for ethanol and 0.05% for DMSO). In the series of
trials, the concentration of compounds was sequentially deꢀ
creased twofold until the effect disappeared. The activity of the
compound was estimated as an effective threshold concentraꢀ
tion, EC, resulting in cleavage alteration or developmental abꢀ
normalities. The embryo development was monitored using
a Biolam LOMO light microscope (SaintꢀPetersburg).
4ꢀ[5ꢀ(4ꢀEthoxyphenyl)ꢀ1Hꢀ1,2,3ꢀtriazolꢀ1ꢀyl]ꢀ3ꢀ(pyrrolꢀ1ꢀ
yl)furazan (7e). The yield was 78%, m.p. 120—121 C, Rf 0.47.

Antineoplastic properties of triazolylfurazans
Russ.Chem.Bull., Int.Ed., Vol. 62, No. 3, March, 2013
843
Cytotoxicity in 60 human cancer cell lines was studied at the
National Cancer Institute of USA according to the procedure
described at http://dtp.nci.nih.gov/branches/btb/ivclsp.html.
11. V. Yu. Rozhkov, L. V. Batog, E. K. Shevtsova, M. I. Struchꢀ
kova, Mendeleev Commun., 2004, 14, 76.
12. V. Yu. Rozhkov, L. V. Batog, M. I. Struchkova, Russ. Chem.
Bull. (Int. Ed.), 2005, 54, 1866 [Izv. Akad. Nauk, Ser. Khim.,
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The authors are grateful to the National Cancer Instiꢀ
tute (Bethesda, Maryland, USA) for the screening of comꢀ
pounds in the framework of the Developmental Theraꢀ
peutics Program for the search of antineoplastic mediciꢀ
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15. V. Yu. Rozhkov, L. V. Batog, M. I. Struchkova, Russ. Chem.
Bull. (Int. Ed.), 2011, 60, 1712 [Izv. Akad. Nauk, Ser. Khim.,
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Received December 19, 2012;
in revised form February 12, 2013