Synthesis of 5-methylsulfonylpyrimidines and their fused derivatives

Article abstract of DOI:10.1134/S1070363217030082

The interaction of available 2-methylsulfonyl-3-ethoxyacrylonitrile with amidine, their analogs, and aminoazoles containing amidine fragment, yielding earlier unknown 4-amino-5-methylsulfonylpyrimidines and their fused derivatives has been studied.

Full text of DOI:10.1134/S1070363217030082

ISSN 1070-3632, Russian Journal of General Chemistry, 2017, Vol. 87, No. 3, pp. 407–413. © Pleiades Publishing, Ltd., 2017.
Original Russian Text © R.N. Solomyannii, S.G. Pil’o, S.R. Slivchuk, V.M. Prokopenko, E.B. Rusanov, V.S. Brovarets, 2017, published in Zhurnal Obshchei
Khimii, 2017, Vol. 87, No. 3, pp. 398–404.
Synthesis of 5-Methylsulfonylpyrimidines
and Their Fused Derivatives
R. N. Solomyanniia, S. G. Pil’oa, S. R. Slivchuka,
V. M. Prokopenkoa, E. B. Rusanovb, and V. S. Brovaretsa*
a Institute of Bioorganic Chemistry and Petrochemistry, National Academy of Sciences of Ukraine,
ul. Murmanskaya 1, Kiev, 02660 Ukraine
*e-mail: brovarets@bpci.kiev.ua
b Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Kiev, Ukraine
Received September 29, 2016
Abstract—The interaction of available 2-methylsulfonyl-3-ethoxyacrylonitrile with amidine, their analogs, and
aminoazoles containing amidine fragment, yielding earlier unknown 4-amino-5-methylsulfonylpyrimidines and
their fused derivatives has been studied.
Keywords: 2-methylsulfonyl-3-ethoxyacrylonitrile, aminoazole, 4-amino-5-methylsulfonylpyrimidine, imidazo-
[1,2-a]pyrimidine, pyrazolo[1,5-a]pyrimidine, heterocyclization
DOI: 10.1134/S1070363217030082
Pyrimidine derivatives play important part in bio-
chemical processes in living organisms [1–4] and
exhibit a wide range of biological activity [5–9].
Methylsulfonyl group is found in certain natural com-
pounds [10–15]; therefore, its introduction in pyri-
midine molecule leads to various biological activity of
the resulting derivatives [16–20].
reacts with amidines 2 on reflux in ethanol in the
presence of triethylamine to form 4-amino-2-aryl(aryl-
thio)-5-methylsulfonylpyrimidines 3a–3f (Scheme 1).
Most probably, the transformation scheme includes
initial substitution of ethoxy group yielding inter-
mediate A (cf. [22, 23]), followed by intramolecular
heterocyclization A→B and isomerization into the
target products 3.
This work aimed to study the interaction of
available 2-methylsulfonyl-3-ethoxyacrylonitrile 1 [21]
with amidines, their analogs, and aminoazoles in order
to prepare novel 5-methylsulfonylpyrimidines and
their fused derivatives. We observed that substrate 1
Composition and structure of pyrimidines 3a–3f
were confirmed by elemental analysis (Table 1), IR, 1Н
NMR, and 13С NMR spectroscopy, and chromato–
mass spectrometry (Table 2) data. IR spectra of the
Scheme 1.
MeSO2
CN
HN
+
R1
H2N HCl
OEt
1
2
NH
NH2
N
MeSO2
MeSO2
MeSO2
:
NH2
R1
Δ
NH
R1
N
Et3N
_
.
Et3N HCl
N
N
N
3a_3f
R1
A
B
R1 = Ph (a), 4-FC6H4 (b), 4-MeOC6H4 (c), PhS (d), 4-MeC6H4S (e), 4-MeOC6H4S (f).
407

408
SYNTHESIS OF 5-METHYLSULFONYLPYRIMIDINES
Table 1. Yields, melting points, and elemental analysis data of compounds 3, 5, 7, 9
Found, %
Calculated, %
Comp. Yield,
mp, °С
Formula
no.
%
С
Н
N
S
С
Н
N
S
3аа
3b
3c
3d
3e
3f
65
53
55
57
69
79
73
60
70
90
185–187 (EtOH)
185–186 (EtOH)
187–188 (EtOH)
209–210 (EtOH)
53.08 4.40 16.69 12.96 C11H11N3O2S
49.60 3.71 15.91 12.14 C11H10FN3O2S
51.55 4.66 15.18 11.35 C12H13N3O3S
46.94 3.90 15.05 22.63 C11H11N3O2S2
53.01 4.42 16.86 12.86
49.62 3.76 15.72 12.00
51.61 4.66 15.04 11.48
46.98 3.91 14.93 22.79
48.81 4.41 14.23 21.71
48.48 4.38 13.49 20.59
39.62 3.77 26.40 15.11
42.48 4.42 24.76 14.17
39.62 3.77 26.40 15.11
50.38 3.82 21.36 12.22
213 (decomp.) (EtOH) 48.80 4.45 14.39 21.51 C12H13N3O2S2
215 (decomp.) (EtOH) 48.40 4.37 13.57 20.43 C12H13N2O3S2
5а
5b
7
202–203 (dioxane)
205–206 (dioxane)
>250 (dioxane)
39.60 3.70 26.55 15.02 C7H8N4O2S
42.53 4.35 24.85 14.05 C8H10N4O2S
39.52 3.70 26.29 15.23 C7H8N4O2S
50.33 3.90 21.50 12.11 C11H10N4O2S
9
>250 (dioxane)
a mp 188–189°С [16].
Table 2. Spectral parameters of compounds 3, 5, 7, 9
Comp.
ν, cm–1
no.
m/z,
δ, ppm
[M + 1]+
3аа,b 1142, 1277 (SO2); 1418, 1440, 1470, 3.25 s (3H, CH3), 7.10 br.s (1H, NH), 7.47–7.64 m (3Н, С6Н5),
1569, 1625, 3123, 3269, 3456 8.22 br.s (1Н, NН), 8.32–8.40 m (2Н, С6Н5), 8.68 s (1Н, CH)
3b 1140, 1282 (SO2); 1226, 1418, 1571, 3.30 s (3H, CH3), 7.14 br.s (1H, NH), 7.30–7.39 m (2Н, С6Н4),
1601, 1631, 3080, 3418, 3446 8.24 br.s (1Н, NН), 8.45–8.46 m (2Н, C6H4), 8.67 s (1Н, CH)
1145, 1247 (SO2); 1403, 1535, 1562, 3.27 s (3H, CH3), 3.86 s (3Н, СН3O), 7.00 br.s (1H, NH), 7.08 d
250
268
280
3c
1634, 3358, 3460
(2Н, С6Н4, J = 8.5 Hz), 8.10 br.s (1Н, NН), 8.34 d (2Н, С6Н4, J =
8.5 Hz), 8.63 m (1Н, CH)
3d 1126, 1282 (SO2); 1357, 1458, 1529, 3.23 s (3H, CH3), 7.06 br.s (1H, NH), 7.48–7.62 m (5H, C6H5),
1562, 1629, 3344, 3453 8.19 br.s (1H, NH), 8.31 s (1Н, CH)
3ec 1128, 1283 (SO2); 1528, 1562, 1634, 2.37 s (3H, CH3), 3.23 s (3H, CH3), 7.03 br.s (1H, NH), 7.27 d
282
296
3344, 3442
(2Н, С6Н4, J 8.5 Hz), 7.46 d (2Н, С6Н4, J = 8.5 Hz), 8.17 br.s
(1H, NH), 8.29 s (1Н, CH)
3f
1127, 1285 (SO2); 1249, 1528, 1564, 3.23 s (3H, CH3), 3.82 s (3Н, СН3O), 7.02 d (2H, C6H4, J =
312
1632, 3340, 3445
8.5 Hz), 7.19 br.s (1Н, NH), 7.50 d (2Н, C6H4, J = 8.5 Hz), 8.15
br.s (1Н, NH), 8.29 s (1Н, CH)
5аd 1130, 1290 (SO2); 1199, 1311, 1458, 3.32 s (3H, CH3), 6.61 s (1H, CH), 8.28 s (1H, CH), 8.40 br.s
1495, 1586, 1637, 1680, 3129, 3333, 3456 (2Н, NH2), 8.41 s (1H, CH)
213
227
213
263
5be 1118, 1293 (SO2); 1223, 1563, 1603, 2.45 s (3H, CH3), 3.37 s (3H, CH3), 6.43 s (1H, CH), 8.35 s (1H,
1641, 3006, 3413
1127, 1292 (SO2); 1560, 1578, 1662, 3.28 s (3H, CH3), 7.63 s (1H, CH), 8.17 s (1H, CH), 8.40 br.s
3128, 3393 (2Н, NH2), 8.41 s (1H, CH)
CH), 8.40 br.s (2Н, NH2)
7f
9
1124, 1288 (SO2); 1212, 1420, 1452, 3.33 s (3H, CH3), 7.39–7.58 m (7H, CH, C6H4, NH2)
1569, 1606, 1637, 3173, 3420
a
1
IR spectrum, ν, cm–1: 1410, 1530, 1560, 1620, 3100, 3440 [16]. Н NMR spectrum, δ, ppm: 3.23 s (3H, CH3), 7.52–8.18 m (7Н, С6Н5,
NН2), 8.68 s (1Н) [16]. b 13С NMR spectrum, δС, ppm: 43.4 (SO2СН3), 113.9 (С5), 128.8 (СНAr), 129.1 (СНAr), 132.1 (СНAr), 136.9 (СAr),
158.4 (С6Н), 159.7 (С4), 166.7 (С2). c 13С NMR spectrum, δC, ppm: 21.2 (СН3), 43.5 (SO2СН3), 112.7 (С5), 125.5 (СAr), 130.4 (СНAr),
135.6 (СНAr), 139.7 (СAr), 157.9 (С6Н), 158.9 (С4), 175.9 (С2). d 13С NMR spectrum, δC, ppm: 44.9 (SO2СН3), 97.7 (С3Н), 100.3 (С6),
146.7 (С5Н), 147.0 (С3а), 149.1 (С2Н), 149.5 (С7). 13С NMR spectrum, δC, ppm: 14.9 (СН3), 44.9 (SO2СН3), 97.7 (С3Н), 100.0 (С6),
e
146.4 (С3а), 149.0 (С5Н), 150.1 (С7), 156.4 (С2). f 13С NMR spectrum, δC, ppm: 44.6 (SO2СН3), 100.5 (С6), 109.3 (С3Н), 134.6 (С2Н),
147.7 (С5), 149.8 (С8а), 150.1 (С7Н).
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 87 No. 3 2017

SOLOMYANNII et al.
409
Fig. 1. General view of molecule of compound 3e (thermal ellipsoids with 30% probability, hydrogen atoms omitted).
products contained the absorption bands at 1126–1145
and 1247–1285 cm–1 assigned to symmetric and asym-
metric stretching of SO2 group and the bands at 3269–
3460 cm–1 corresponding to NH2 stretching. The
absence of the nitrile band evidenced the participation
of that group in cyclization.
1Н NMR spectra of compounds 3a–3f did not
contain the signal of the EtO fragment but contained
two broadened singlets at δ 7.02–7.14 and 8.15–
8.27 ppm assigned to amino group. 13С NMR spectra
contained the expected signals of carbon atoms. On top
of that, product 3a has been earlier prepared via a
different route [24], and its constants were identical to
those of the 1→3a transformation product.
the following parameters were formed in the crystal:
N3–H1 0.85(3), N3···O2 2.978(3) Å, N3H1O2 128(3)°;
N3–H2 0.82(2), N3···O1#1 3.038(3) Å, N3H2O1#1 167(2)°
and N3–H1 0.85(3)°, N3···O2#2 2.958(3) Å, N3H1O2#2
147(3)° (the #1 and #2 symbols denote the atoms
related to the basic ones via the symmetry operations x,
–y – 0.5, z – 0.5 and –x + 1, –y – 1, –z, respectively).
Aiming to prepare fused derivatives of 5-methyl-
sulfonylpyrimidines annulated via the bond a, we
studied the interaction of 2-methylsulfonyl-3-ethoxy-
acrylonitrile 1 with aminoazoles: 5-amino-3-R-1H-
pyrazoles 4, 2-amino-1Н-imidazole 6, and 2-amino-1H-
benzimidazole 8, containing three labile hydrogen
atoms (Scheme 2). The reactions occurred on refluxing
the equimolar amounts of the reagents and triethyl-
amine in dioxane. In contrast to the expected cyclocon-
To unambiguously elucidate the structure of
compounds 3, we performed X-ray diffraction analysis
of one of them (3e). General view of its molecule is
shown in Fig. 1, and the basic geometry parameters are
collected in Table 3. The bond lengths and angles in
the central pyrimidine cycle fell within the expected
ranges and coincided with the suggested structure of
the compound. In detain, the transannular bonds were
delocalized, and their lengths were typical of the delo-
calized structures. The pyrimidine cycle was planar,
the mean square deviation of the atoms off the plane
being as low as 0.0113 Å, the S1, S2, and N3 atoms
deviated from the plane by 0.1594(30), 0.0680(29),
and –0.0652(34) Å, respectively, and the phenyl cycle
С6–С11 was rotated with respect to the plane by 84.76(7)°.
The C2–N3 bond, 1.334(3) Å, was strongly shortened
as compared to the length typical of the ordinary С–N
bonds (1.45 Å), whereas the sum of bond angles at the
amino group nitrogen atom equaled 359(3)°, evi-
dencing the efficient conjugation of the lone-electron
pair of the N3 atom with the heterocycle π-system.
Intramolecular (N3–H1···O2) as well as intermolecular
(N3–H2···O1#1 and N3–H1···O2#2) hydrogen bonds with
Table 3. Major bond lengths and bond angles in molecule of
compound 3e
Bond length
C1–N1
C1–N2
C2–N2
C2–C3
C3–C4
C4–N1
C2–N3
C1–S2
d, Å
Bond angle
N2C1N1
C1N2C2
N2C2C3
C4C3C2
N1C4C3
C4N1C1
C3S1C5
ω, deg
1.334(3)
1.332(3)
1.345(3)
1.419(3)
1.373(3)
1.328(3)
1.334(3)
1.754(2)
1.771(2)
1.742(2)
1.743(3)
128.0(2)
117.31(19)
119.23(19)
116.9(2)
124.6(2)
113.92(19)
104.17(12)
103.25(11)
C1S2C6
C6–S2
C3–S1
C5–S1
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410
SYNTHESIS OF 5-METHYLSULFONYLPYRIMIDINES
Scheme 2.
NH2
N
MeSO2
MeSO2
CN
MeSO2
MeSO2
HN
N
H
C
N
HN
D
NH2
1 + H2N
CN
N
N
NH2
N
E
F
Scheme 3.
NH2
N
H
MeSO2
MeSO2
HN N
N
Et3N
N
Δ
N
:
N
1
+
R
R2
R
H2N
N
H
N
4
5a, 5b
NH2
G
N
MeSO2
MeSO2
HN
H
2Et3N
Δ
N
:
N
1
HCl
+
_
H2N
.
Et3N HCl
N
N
N
H
N
N
6
7
H
NH2
N
H
MeSO2
MeSO2
N
Et3N
Δ
N
H
1
+ H2N
:
N
N
N
N
H
I
N
N
8
9
R = H (a), Me (b).
densation 1→3, the initial pathway of the interaction
between compound 1 and the aminoazoles could
involve the primary amino group as well as the cyclic
nitrogen atom, resulting in the formation of
intermediates C and E that would afford linear (D) or
angular (F) products.
Composition and structure of compounds 5, 7, and
9 were confirmed by the data of elemental analysis,
spectroscopy, and X-ray diffraction. The IR spectro-
scopy data confirmed the disappearance of the CN
group during the heterocyclization and the presence of
1
SO2 and NH2 groups in the reaction products. The Н
NMR spectra contained the signal of the NH2 group at
8.40–8.75 ppm, coinciding the reference data for
similar systems [26, 27].
According to the data in [25–27], the 1→C→D
path involving the formation of intermediates G, H,
and I (Scheme 3) should be preferred. The latter
intermediates, rapidly cyclizing in the fused systems 5,
7, and 9, were not isolated.
Structure of compound 5a was unambiguously
elucidated by means of X-ray diffraction. General view
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 87 No. 3 2017

SOLOMYANNII et al.
of the molecule is shown in Fig. 2, and the basic geo-
411
metry parameters are collected in Table 4. The central bi-
cyclic fragment N1N2N4C1–6 was planar within 0.006 Å.
The distribution of bond lengths and angles evidenced
delocalization of electronic density in the heterocyclic
scaffold. The С6–N3 bond (1.315 Å) was strongly
shortened as compared to the length typical of the C–N
ordinary bond (1.45 Å), and the sum of bond angles at
the nitrogen atom was 360(3)°, pointing at conjugation
of the lone-electron pair of the N3 atom of the amino
group with π-system of the heterocycle. It is interesting
that the S–C bond lengths were identical within the
experimental accuracy (1.740 Å). Intermolecular
(N3–H32···O1А) as well as strong intramolecular
(N3–H31···O2) bonds with the following parameters
were observed in the crystal: N3–H32 0.90(3), N3···O1А
2.925(3) Å, N3H32O1А 147(3)°; N3–H31 0.82(3),
N3···O2 2.794(3) Å, N3H31O2 132(3)°. The “A” sign
denotes the atom related with the basic ones via the
following symmetry operation: x + 1, y, z.
Fig. 2. General view of molecule of compound 5a (thermal
ellipsoids with 30% probability, hydrogen atoms omitted).
Ukraine. Contents of carbon and hydrogen were
determined using gravimetric Pregl method, content of
nitrogen was determined using gasometric Dumas
micromethod, and sulfur content was determined using
titrimetric Schoeniger method [28]. Melting points
were determined using a Fisher–Johns instrument.
In summary, the interaction of 2-methylsulfonyl-3-
ethoxyacrylonitrile with amidines and their analogs
yielded 4-amino-5-methylsulfonylpyrimidines. The
reactions of the same substrate with aminoazoles (5-
amino-3-R-1H-pyrazoles, 2-amino-1Н-imidazole, and
2-amino-1H-benzimidazole) occurred regioselectively
to afford 7-amino-6-(methylsulfonyl)pyrazolo[1,5-a]-
pyrimidines, 5-amino-6-(methylsulfonyl)imidazo[1,2-
a]pyrimidine, and 4-amino-3-(methylsulfonyl)pyri-
mido[1,2-a]benzimidazole. These products are inte-
resting in view of further modification and screening
for biologically active compounds.
Table 4. Major bond lengths and bond angles in molecule of
compound 5a
Bond length
N2–N1
d, Å
Bond angle
C1C2C3
ω, deg
1.364(3)
105.3(3)
N2–C1
C2–C1
C3–C2
C3–N1
C3–N4
C4–N4
C4–C5
C6–N3
C6–N1
C6–C5
1.329(4)
1.376(5)
1.379(4)
1.387(3)
1.350(3)
1.314(3)
1.414(3)
1.314(3)
1.369(3)
1.387(3)
C1N2N1
C2C3N1
N2C1C2
N4C3N1
N2N1C3
N2N1C6
C6N1C3
N4C3C2
C4N4C3
C6C5C4
N3C6N1
N3C6C5
N1C6C5
N4C4C5
101.9(2)
104.6(2)
114.8(3)
121.6(2)
113.4(2)
122.5(2)
124.0(2)
133.7(3)
115.5(2)
119.7(2)
116.9(2)
129.1(2)
113.9(2)
125.1(3)
EXPERIMENTAL
1Н and 13C NMR spectra were recorded using a
Varian Mercury instrument (400 and 100 MHz) in
DMSO-d6 with TMS as internal reference. IR spectra
were recorded using a Vertex-70 spectrometer (KBr
pellets). Chromato–mass spectra were recorded using
an Agilent 1100 Series chromatograph equipped with a
diode matrix and an Agilent LC\MSD SL mass-
selective detector. Parameters of the analysis: column
Zorbax SB-C18, 1.8 µm, 4.6×15 mm; solvents: MeCN–
H2O, 95 : 5, 0.1% CF3COOH (A); 0.1% aqueous
CF3COOH (B); eluent flow rate 3 mL/min, injected
volume 1 µL, UV detectors 215, 254, and 285 nm,
chemical ionization at atmospheric pressure. Elemental
analysis was performed at Laboratory of Analytical
Chemistry, Institute of Bioorganic Chemistry and
Petrochemistry, National Academy of Sciences of
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 87 No. 3 2017

412
SYNTHESIS OF 5-METHYLSULFONYLPYRIMIDINES
X-ray diffraction study of a monocrystal of
[0.0041(9)]. The structure was solved via direct method
and refined using least squares method implemented in
Bruker SHELXTL software package [29]. Hydrogen
atoms were localized and refined under isotropic
approximation. 1516 reflections with I > 2σ(I) were
used in the refinement (159 fitted parameters, 9.5
reflections per a parameter); the weighing scheme ω =
1/[σ2(Fo2) + (0.0446P)2 + 0.870Р] with Р = (Fo2 +
2Fc2)/3 was applied. The ratio of the highest (average)
shift to the inaccuracy at the last cycle 0.014(0.001).
Final values of the divergence factors: R1(F) 0.0566,
wR2(F2) 0.1227 over reflections with I > 2σ(I) and
R1(F) 0.0973, wR2(F2) 0.1458, GOF 1.082 over all
reflections. Residual electronic density from the differ-
rential Fourier series after the last cycle of refinement
0.66 and –0.35 е/Å3. Complete crystallographic data
were deposited at the Cambridge Crystallographic
Data Centre (CCDC 1502977).
compound 3e (0.10×0.15×0.26 mm) was performed at
room temperature using a Bruker Smart Apex II
diffractometer (MoKα-radiation, graphitic monochro-
mator, θmax 28.89°, –14 ≤ h ≤ 16, –11 ≤ k ≤ 11, –19 ≤
l ≤ 19). Total reflections collected: 15100, 3582 of
them being independent (R-factor of averaging
0.0512). Crystals of compound 3e were monoclinic,
C12H13N3O2S2, M 295.37, space group С2/с, а.8777(4),
b 8.3561(3), c 14.4812(5) Å, β106.937(2)°, V 1374.94
(8) Å3, Z 4, dcalc 1.427, μ 0.388 mm–1, F(000) 616. The
absorption was corrected for by means of multi-
scanning using SADABS software (Тmin/Tmax
=
0.804262/0.9697). The structure was solved via direct
method and refined using least squares method
implemented in Bruker SHELXTL software package
[29]. The non-hydrogen atoms were refined under
anisotropic approximation. Positions and thermal
parameters of the СН hydrogen atoms were refined
using a rider model along with the respective
parameters of the adjacent carbon atoms; the hydrogen
atoms adjacent to nitrogen were localized via
differential Fourier synthesis, and their positions were
refined under isotropic approximation. 2306 reflections
with I > 2σ(I) were used in the refinement (180 fitted
parameters, 12.8 reflections per a parameter); the
weighing scheme ω = 1/[σ2(Fo2) + (0.0537Р)2 +
0.5368P] with Р = (Fo2 + 2Fc2)/3 was applied. Final
values of the divergence factors: R1(F) 0.0503, wR2(F2)
0.1105 over reflections with I > 2σ(I) and R1(F)
0.0922, wR2(F2) 0.1303, GOF 1.018 over all reflec-
tions. Residual electronic density from the differential
Fourier series after the last cycle of refinement 0.34
and –0.41 е/Å3. Complete crystallographic data were
deposited at the Cambridge Crystallographic Data
Centre (CCDC 1502961).
Commercial chemicals and solvents were used.
4-Amino-2-aryl(arylthio)-5-methylsulfonylpyri-
midines (3a–3f). A mixture of 0.52 g (3 mmol) of 2-
methylsulfonyl-3-ethoxyacrylonitrile 1, 3 mmol of the
corresponding amidine hydrochloride, and 0.84 mL
(6 mmol) of triethylamine were refluxed during 6 h in
10 mL of ethanol and then kept at room temperature
during 12 h. The solvent was removed in vacuum, the
residue was treated with water, the precipitate was
filtered off, dried, and recrystallized.
7-Amino-6-(methylsulfonyl)pyrazolo[1,5-a]pyri-
midine (5a). A mixture of 0.52 g (3 mmol) of 2-methyl-
sulfonyl-3-ethoxyacrylonitrile 1, 0.25 g (3 mmol) of
5-amino-1Н-pyrazole, and 0.42 mL (3 mmol) of
triethylamine was refluxed during 3 h in 5 mL of
dioxane. The solvent was removed in vacuum, the residue
was treated with water, the precipitate was filtered off,
dried, and recrystallized.
X-ray diffraction study of a monocrystal of
compound 5a (0.39×0.35×0.15 mm) was performed at
room temperature using a Bruker Smart Apex II diffrac-
tometer (MoKα-radiation, graphitic monochromator,
θmax 29.57°, –9 ≤ h ≤ 9, –11 ≤ k ≤ 11, –11 ≤ l ≤ 11).
Total reflections collected: 5370, 2290 of them being
independent (R-factor of averaging 0.0429). Crystals
of compound 5a were triclinic, C7H8N4O2S, M 212.23,
space group Р-1, а 7.2727(12), b 8.2714(13), c
8.3057(14) Å, α 96.932(11), β 114.398(9), γ 100.789(9)°,
V 435.88(12) Å3, Z 2, dcalc 1.617, μ 0.349 mm–1,
F(000) 220. The absorption was corrected for by
means of multiscanning using SADABS software
(Тmin/Tmax = 0.652028) and isotropic extinction factor
7-Amino-2-methyl-6-(methylsulfonyl)pyrazolo-
[1,5-a]pyrimidine (5b) was prepared similarly from 2-
methylsulfonyl-3-ethoxyacrylonitrile 1 and 5-amino-3-
methyl-1H-pyrazole.
5-Amino-6-(methylsulfonyl)imidazo[1,2-a]pyri-
midine (7). A mixture of 0.52 g (3 mmol) of 2-methyl-
sulfonyl-3-ethoxyacrylonitrile 1, 0.36 g (3 mmol) of 2-
amino-1H-imidazole hydrochloride, and 0.84 mL
(6 mmol) of triethylamine was refluxed during 3 h in
10 mL of dioxane. The solvent was removed in
vacuum, the residue was treated with water, the
precipitate was filtered off, dried, and recrystallized.
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SOLOMYANNII et al.
413
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washed with ethanol, and recrystallized.
ACKNOWLEDGMENTS
This work was financially supported by National
Research Foundation of Ukraine (project no. 16DF037-
02).
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