2-(pyrazol-4-yl)-1,3-oxaselenolanes from pyrazole carbaldehydes and 2-selanyl-1-ethanol

Article abstract of DOI:10.1002/hc.21200

Pyrazole carbaldehydes react with 2-selanyl-1-ethanol at room temperature in the presence of trimethylchlorosilane followed by treatment C with triethyl amine to afford the corresponding 2-(pyrazol-4-yl)-1,3-oxaselenolanes. The structure of the novel compounds was confirmed by IR, ¹³ C, ¹ H, ¹⁵N, and ⁷⁷ Se NMR spectroscopy.this article online at wileyonlinelibrary.com.

Full text of DOI:10.1002/hc.21200

Heteroatom Chemistry
Volume 00, Number 00, 2014
2-(Pyrazol-4-yl)-1,3-oxaselenolanes from
Pyrazole Сarbaldehydes and
2-Selanyl-1-ethanol
Lyubov K. Papernaya, Alexandra A. Shatrova,
Ekaterina P. Levanova, Alexandr I. Albanov, Lyudmila V. Klyba,
Elena V. Rudyakova, and Galina G. Levkovskaya
A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences,
664033 Irkutsk, Russia
Received 18 December 2013; revised 1 April 2014
Urgency of such research is due to the pyrazole
ABSTRACT: Pyrazole carbaldehydes react with 2-
carbaldehydes (unlike aromatic aldehydes) react
selanyl-1-ethanol at room temperature in the pres-
with selenoethanol analog, mercaptoethanol, in the
ence of trimethylchlorosilane followed by treatment
presence of trimethylchlorosilane (Me3SiCl) in quite
with triethyl amine to afford the corresponding 2-
different fashion delivering, even with an equimolar
(pyrazol-4-yl)-1,3-oxaselenolanes. The structure of the
amount of mercaptoethanol, mainly open-chained
novel compounds was confirmed by IR, 13C, 1H, 15N,
S,S-acetals of pyrazole carbaldehydes [12] or
and 77Se NMR spectroscopy.
2014 Wiley Period-
ꢀC
pyrazolyloxadithiocanes [13]. Only under specially
found conditions, individual 2-(pyrazol-4-yl)-1,3-
oxathiolanes are formed in quantitative yields [12].
While the reaction of nitrobenzaldehydes with
an equimolar amount of 2-mercaptoethanol with-
out heating in the presence of Me3SiCl furnishes
aryl-1,3-oxathiolanes with good selectivity, the
formylpyrazoles react with 2-mercaptoethanol un-
der similar conditions to give mainly open-chained
bis(2-hydroxyethyl)dithioacetals. Noteworthy, when
twofold molar excess of 2-mercaptoethanol is em-
ployed, bis(2-hydroxyethyl)dithioacetals are formed
almost quantitatively.
icals, Inc. Heteroatom Chem. 00:1–7, 2014; View
this article online at wileyonlinelibrary.com. DOI
10.1002/hc.21200
INTRODUCTION
Currently, an extremely limited number of 1,3-
oxaselenolane derivatives is known. This is explained
by the fact that their syntheses are laborious and
multistage, the initial selenols being inaccessible and
unstable compounds [1]. At the same time, similar
to sulfur analogs, the five-membered oxaselenolane
ring is present in nucleoside structures possessing
antiviral activity against hepatitis B and HIV infec-
tion, thus representing considerable interest for syn-
thesis [2–11].
In continuation of the systematic investigations
of the thio- and a selenoacetalyzation of hetaryl-
carbaldehydes in the presence of alkylchlorosilanes,
we have studied the reactions of pyrazole aldehydes
with 2-selanyl-1-ethanol.
Correspondence to: Lyubov K. Papernaya, e-mail: papern@
irioch.irk.ru.
RESULTS AND DISCUSSION
Supporting Information is available in the online issue at
www.wileyonlinelibrary.com.
2014 Wiley Periodicals, Inc.
In the present work, we have found that unlike
2-mercaptoethanol, 2-selenoetanol reacts with
ꢀC
1

2
Papernaya et al.
Se
Se
O
O
O
Me
Me
Me
TMSCl
Et3N
+
.N
HCl
HSe(CH2)2OH
N
N
N
R
CHCl3
r.t., CH2Cl2
N
R
N
R
R1
R1
R1
2a-f
3a-f, 68-94%
1a-f
R = Me, R1= Bn (a), Me (b), Pr(c), i-Pr (d), Allyl (e); R = Cl, R1= Ph (f)
SCHEME 1 Synthesis of 2-(pyrazol-4-yl)-1,3-oxaselenanes 3a–f.
pyrazole aldehydes in a different manner. The
reaction is implemented with equimolar amounts of
reagents in four- to sixfold excess trimethylchlorosi-
lane in the CH2Cl2 solution at room temperature for
1 h (under the conditions of predominant formation
of open-chained bis(2-hydroxyethyl) dithioac-
etals [12]) to exclusively deliver 2-(pirazol-4-yl)-1,
3-oxaselenolane hydrochlorides 2a–f in high yields
(Scheme 1).
The synthesized hydrochlorides 2a–f are unsta-
ble and upon storage in air or during the treat-
ment with solvents and admixtures of water undergo
hydrolysis to give the initial aldehydes and other
unidentified compounds, probably, products of 2-
selanyl-1-ethanol oxidation.
mercaptoethanol with formylpyrazoles is also owing
to the formation of thermodynamically more steady
structure, i.e., pyrazolyloxaselenolane.
The synthesized pyrazolyloxaselenolanes 3a–f
are white fine-crystalline substances, well soluble
in the majority of organic solvents. The structure
1
of compounds 3a–f has been proved using Н, 13С,
77Se, and 15N NMR technique. The composition of
the products is confirmed by the data of element
analysis.
In the 1H NMR spectra, 1,3-oxaselenolanes
fragment of compounds 2a, 3a–f is present
as a five-membered cycle with nonequivalent di-
astereotopic protons of SeCH2 (2J = 9.1–10.8 Hz and
vicinal 3J = 5.3–6.2 Hz and 3J = 0.9–1.7 Hz) and
ОCH2 groups with heminal 2J = 9.2–10.2 Hz
and vicinal 3J = 5.3–11.0 Hz and 3J = 0.9–1.7 Hz
spin–spin coupling constants. The structure of the
compounds synthesized is also supported by the
presence of satellite signals of protons and carbons
adjacent to selenium atom, which are caused by
the spin–spin interaction with magnetically active
selenium isotope 77Se. For instance, a proton
signal of the OСHSe moiety in oxaselenolanes 2a,
3a–f appears as a singlet at 6.17–6.37 ppm with
The treatment of compounds 2a–f with a triethy-
lamine solution in chloroform leads to hardly acces-
sible 1,3-oxaselenolanes in 68–94% yields.
In contrast to the initially formed hydrochlo-
rides, 1,3-oxaselenolanes 3a–f are stable and do not
undergo the ring opening with the formation of the
starting aldehydes under the action of water.
The application of 2 molar excess of the selenoal-
cohol in the reaction do not lead to the formation of
open-chained bis(2-hydroxyethyl)diselenoacetals of
pyrazole carbaldehydes, unlike similar interaction
of formylpyrazoles with 2-mercaptoethanol un-
2
a characteristic constant JH–Se = 14.4–14.9 Hz,
1JС–Se = 53.4–57.9 Hz.
der similar conditions [12]. As
a
result,
a
In the 77Se NMR spectra of compounds 2a, 3a–f,
the signal of selenium atom is present in the region
of 305.4–337.2 ppm.
hard-to-separate mixture containing pyrazolylox-
aselenolanes 3a–f, selenoethanol (thin-layer chro-
matography (TLC)) and unidentified products has
been obtained.
In the 15N NMR spectra, signals of the pyridine
and pyrrole nitrogen atoms are detected.
Such difference in behavior of selenoethanol and
mercaptoethanol in the reaction with formylpyra-
zoles is likely due to the steric effect originated ow-
ing to the presence of bulkier selenium atom in the
selenoalcohol in comparison with mercaptoethanol
sulfur atom. Despite the complementarity of the car-
baldehyde group in 4-formylpyrazoles to the mer-
captoalcohol, the chalcogenol fragment mentioned
by us earlier, in this case, the steric hindrance is,
apparently, a decisive factor ensuring the formation
of only Se,O-cycle of 1,3-oxaselenolanes. Obviously,
the difference in the reactions of selenoethanol and
We have studied the mass spectra of com-
pounds 3a–f (Table 1). Upon electron ionization, 1,3-
oxaselenolanes 3a–f generate unstable molecular
ions, unlike the corresponding pyrazole-substituted
1,3-oxathiolanes, which under the close conditions
give a stable molecular ions (Irel., 18–60%) [14]. At
the same time, the main direction of decomposi-
tion of the molecular ions is similar both for sulfur-
and selenium-containing pyrazoles and involves the
cleavage of saturated heterocycle to produce the
radical cation of the corresponding carbaldehyde
(Scheme 2, ion A). Further decomposition of the
Heteroatom Chemistry DOI 10.1002/hc

2-(Pyrazol-4-yl)-1,3-oxaselenolanes from Pyrazole Сarbaldehydes and 2-Selanyl-1-ethanol
3
TABLE 1 Full Mass Spectrums of Electronic Ionization 2-(Pyrazol-4-yl)-1,3-oxaselenolanes 3a–f m/z (Intensity, Rated Rather
Maximum Peak)
Compound
Structure
m/z (Irel.,%), 80Se, 35Cl
3a
322(<1) [M]+·, 215 (11), 214 (80), 213 (45), 200 (4), 199 (37), 186 (3),
185 (15), 171 (6), 158 (3), 144 (3), 137 (6), 123 (6), 122 (3), 108
(2), 106 (1), 104 (4), 92 (8), 91 (100), 82 (2), 77 (2), 65 (20), 51 (3).
O
Se
Me
N
Me
N
Ph
3b
3c
246 (<1) [M]+·, 218 (2), 216 (1), 139 (5), 138 (52), 137 (100), 110 (2),
109 (3), 108 (9), 107 (3), 106 (7), 105 (2), 104 (2), 82 (2), 80 (2), 66
(3), 65 (3), 56 (6).
O
Se
Me
N
Me
N
Me
274 (<1) [M]+·, 246 (4), 244 (2), 167 (8), 166 (58), 165 (10), 151 (15),
138 (18), 137 (100), 125 (5), 124 (48), 123 (98), 110 (4), 109 (3),
108 (16), 107 (3), 106 (7), 105 (3), 104 (5), 82 (19), 80 (6), 69 (2),
68 (3), 67 (6), 66 (4), 65 (5), 56 (8).
O
O
Se
Me
N
Me
N
3d
3e
3f
274 (<1) [M]+·, 246 (3), 244 (1), 167 (5), 166 (51), 165 (5), 151 (41),
125 (5), 124 (36), 123 (100), 110 (1), 108 (11), 107 (2), 106 (3),
104 (2), 86 (3), 84 (4), 80 (1), 67 (5).
Se
Me
N
Me
N
Me
Me
272 (<1) [M]+·, 244 (3), 242 (1), 165 (11), 164 (84), 163 (100), 149
(11), 137 (17), 135 (12), 123 (31), 122 (6), 121 (8), 120 (3), 110 (3),
109 (4), 108 (16), 107 (5), 106 (10), 105 (4), 104 (3), 95 (4), 94 (9),
93 (3), 86 (5), 84 (9), 82 (10), 81 (5), 80 (7), 79 (2), 68 (4), 67 (6),
66 (5), 65 (7), 56 (4), 55 (4), 54 (2).
O
Se
Me
N
Me
N
328(<1) [M]+·, 302 (1), 300 (5), 298 (2), 222 (30), 221 (43), 220 (85),
219 (100), 155 (9), 153 (3), 143 (3), 110 (3), 108 (10), 106 (5), 105
(3), 104 (7), 77 (34), 65 (4), 51 (18).
O
Se
Cl
Me
N
N
Ph
SCHEME 2 Pyrazolyl-substituted 1,3-oxaselenolanes 3а–f under the electron ionization (EI).
Heteroatom Chemistry DOI 10.1002/hc

4
Papernaya et al.
radical cation A has been discussed previously [14].
As expected, in the mass spectrum of compound 3а,
the most intensive peak is assigned to the benzyl
moiety with m/z 91 [15,16].
It should be noted that the elimination of
oxygen-containing fragments from the molecular
ion of 1,3-oxaselenolane does not occur. Instead, the
mass spectra of compounds 3a–f show a weak in-
tensity peak of the [M – C2H4]+· ion. All mass spec-
tral characteristics of compounds 3a–f are given in
Table 1.
A method for the preparation of 2-selanyl-
1-ethanol was proposed and successfully real-
ized by researchers of laboratory of sulfur chem-
istry at the A.E. Favorsky Institute of Chemistry,
Siberian Branch, Russian Academy of Sciences,
Irkutsk, Russia [17]. Pyrazole carbaldehyde 1f was
used as commercial product (Sigma-Aldrich Cor-
porate, St. Louis, MO). 1,3,5-Trialkylsubstituted 4-
formylpyrazoles 1a–e were synthesized by the mod-
ified protocol of Vilsmeir–Haack formylation of the
corresponding 1,3,5-trialkylpyrazoles. The compari-
son with literature data [13, 18, 19] showed that the
increase in the reaction time to 8 h at 130–137°С al-
lowed increasing the conversion of trialkylpyrazoles
up to 100% and synthesizing the target products with
98% purity.
Thus, the nature of chalcogene in a five-
membered saturated heterocycle essentially affects
stability of the molecular ion but does not influence
the character of fragmentation.
CONCLUSIONS
1-Allyl-3,5-dimethylpyrazole carbaldehyde (1e).
To DMF (10.96 g, 150 mmol), POCl3 (22.99 g,
150 mmol) was added. Then, the mixture obtained
was added to 1-allyl-3,5-dimethylpyrazole (13.62 g,
100 mmol). The reaction mixture was heated to 130–
137°С and stirred for 8 h. After the reaction com-
pletion, the mixture was poured into water, pH of
the solution reached neutral values with Na2CO3,
the reaction product was extracted with ethyl ac-
etate, dried over MgSO4, the solution was evapo-
rated, and the residue was distilled in a vacuum.
Yield 10.18 g (62%), boiling point (bp) 136–145°С
(10 mm Hg). 1Н NMR δ (ppm): 2.32 (s, 3H, CH3), 2.41
(s, 3H, CH3), 4.57 (d, 2H, CH2), 4.99 (d, J = 17.15,
1H, =CH2), 5.17 (d, J = 10.24, 1H, =CH2), 5.87 (m,
1H, =CH), 9.78 (s, 1H, C(O)H). 13С NMR δ (ppm):
9.03 (CH3), 11.57 (CH3), 50.39 (CH2), 116.33 (C2),
116.89 (CH2=), 131.33 (CH=), 142.92 (C3), 149.50
(C1), 182.97 (C(O)H). Anal. calcd for С9H12N2O: C,
65.83; H, 7.37; N, 17.06. Found: C, 65.88; H, 7.36; N,
17.03.
Pyrazole carbaldehydes 1a–d were obtained
analogously.
1-Benzyl-3,5-dimethylpyrazole carbaldehyde (1a).
Yield 64%, melting point (mp) 66–68°С, (lit [18]:
yield 60.7%, mp 73–74°С).
1,3,5-Trimethylpyrazole carbaldehyde (1b). Yield
61%, bp 114–116°С (5 mm Hg), (lit [18]: yield 62%,
mp 84°С; lit [19]: yield 59%, bp 130°С, (5 mm Hg),
mp 80–83°С).
1-Propyl-3,5-dimethylpyrazole carbaldehyde (1c).
Yield 62%, bp 110–112°С (2 mm Hg) (lit [19]: yield
86%, bp 125°С (5 mm Hg)).
In conclusion, the reaction of a series of 4-
formylpyrazoles, bearing diverse substituents at the
N-1 atom, with selenoethanol has been studied for
the first time. It is revealed that in the presence of
Me3SiCl, the reaction is carried out without heating
to chemoselectively afford hitherto unknown hetero-
cyclic derivatives, 2-(pyrazol-4-yl)-1,3-oxaselenolane
hydrochlorides, which are readily transformed into
the corresponding stable free bases.
EXPERIMENTAL
General
1H, 13C, 77Se, and 15N NMR spectra were recorded
on a Bruker DRX-400 instrument (Bruker BioSpin,
Rheinstetten, Germany) (1H, 400.13; 13C, 100.62;
77Se, 76.31; and 15N, 40.56 MHz, respectively) in the
СDCl3 solution using TMS (1H, 13C), Me2Se (77Se),
and СН3NO2 (15N) as internal standards. The cou-
plings are given in hertz. IR spectra were measured
on a Bruker Vertex 70 spectrometer (Eftlinger, Ger-
many) in KВr pellets or in thin layer. Mass spectra of
electron ionization were obtained on a Agilent 5975С
instrument (Agilent Technologies, Santa Clara, CA).
The samples were introduced via an Agilent
6890N chromatograph and separated on a chro-
matographic column HP-5MS (30 m × 0.25 mm ×
0.25 μm, mode linear programming column temper-
ature from 60°С to 190°С at 5°С/min). Helium was
used as a gas carrier.
The reaction course and purity of the com-
pounds obtained were monitored using a TLC tech-
nique on Silica gel 60 F254 Merk, and diethyl
ether:methanol = 98:2 was used as eluent. Commer-
cial solvents were removed by distillation.
1-i-Propyl-3,5-dimethylpyrazole
carbaldehyde
(1d). Yield 64%, mp 115–116°С (in litera-
ture [12,14,20–22] the yields and physical–chemical
constants of carbaldehydes 1a–e were not given).
Heteroatom Chemistry DOI 10.1002/hc

2-(Pyrazol-4-yl)-1,3-oxaselenolanes from Pyrazole Сarbaldehydes and 2-Selanyl-1-ethanol
5
3
2
3J = 5.3, J = 11.2, 1Н, OCH2), 4.70 (dd, J = 9.8,
3J = 6.2, 1Н, OCH2), 5.65 (s, 2Н, NСН2), 6.17 (s,
1Н, SeCHO), 7.31–7.43 (m, 5Н, Ph). 13C NMR δ
(ppm): 10.03 (Me-5), 10.10 (Me-3), 30.15 (1JC–Se
Pyrazoles involved in formylation were synthe-
sized by the protocol used for the preparation of lin-
early bonded pyrazoles [13].
= 62.7 Hz, SeCH2), 51.77 (NСН2), 71.48 (1JC–Se
=
1-Allyl-3,5-dimethylpyrazole. A mixture of KOH
(11.20 g, 200 mmol) and DMSO (10 mL) was stirred
for 10 min, and then 3,5-dimethylpyrazole (9.61 g,
100 mmol) was added and the mixture was stirred
for 20 min at 20–22°С. Next, allyl bromide (14.52 g,
120 mmol) was added slowly keeping the tempera-
ture not above 30°С, and the mixture was stirred at
20–22°С for 3 h. The reaction mixture was poured
into water (100 mL). 1-Allyl-3,5-dimethylpyrazole
was extracted with diethyl ether, dried over MgSO4,
the solution was evaporated, and the residue was dis-
tilled in vacuum. Yield 11.45 g (84%), bp 86–92°С (15
mm Hg) (lit [23]: yield 48%, bp 187–190°С (746 mm
57.9 Hz, SeCHO), 73.34 (ОСН2), 117.08 (C-4), 127.85
(Cm), 128.82 (Cp), 129.03 (Co), 132.39 (Ci), 142.24
(C-5), 143.05 (C-3). 15N NMR δ (ppm): –183.5 (N-1),
–168.6 (N-2). 77Se NMR δ (ppm): 337.2. Anal. calcd
for C15H18N2OSe·HCl: С, 50.36; H, 5.35; Cl, 9.91; N,
7.83; Se, 22.07. Found: С, 50.65; H, 5.31; Cl, 9.96; N,
7.88; Se, 21.95. By taking into account instability,
the synthesized hydrochlorides 2b–f were converted
to free bases 3b–f without isolating.
General Method for the Synthesis of
2-(Pyrazol-4-yl)-1,3-oxaselenolanes (3a–f)
1
Hg)). Н NMR δ (ppm): 2.10 (s, 3H, CH3), 2.14 (s,
3H, CH3), 4.50 (d, 2H, CH2), 4.92 (d, J = 17.15, 1H,
=CH2), 5.10 (d, J = 10.24, 1H, =CH2), 5.62 (s, 1H,
H-4), 5.87 (m, 1H, =CH). Anal calcd for С8H12N2: C,
70.55; H, 8.88; N, 20.57. Found: C, 70.49; H, 8.89; N,
20.54 (in the work [23], it was reported on synthe-
sis of 1-allyl-3,5-dimethylpyrazole, but the yield and
constants were not given).
To hydrochlorides 2a–f, obtained by the above pro-
tocol from pyrazole carbaldehydes 1a–f (1 mmol),
a solution of Et3N (1 mmol, 0.101 g) in CHCl3
(2 mL) was added. The product formed was pu-
rified by column chromatography using silica gel
(diethyl ether:methanol = 98:2). The target 1,3-
oxaselenolanes 3a–f were isolated as white crystals.
1,3,5-Trimethylpyrazole was prepared in 89%
yield, bp 60–66°С (10 mm Hg) (lit [24]: yield 79%,
bp 165–167°С (741 mm Hg)).
1-Benzyl-3,5-dimethylpyrazole was prepared in
88% yield, bp 191–193°С (20 mm Hg) (lit [24]: yield
33–67%, bp 154–156°С (18 mm Hg)).
1-Propyl-3,5-dimethylpyrazole was prepared in
85% yield, bp 151–156°С (20 mm Hg) (lit [25]: yield
80%, bp 62°С (3 mm Hg)).
1-i-Propyl-3,5-dimethylpyrazole was prepared in
83% yield, bp 95–98°С (8 mm Hg) (in the work
[25], it was reported on synthesis of 1-i-propyl-3,5-
dimethylpyrazole, but the yield and constants were
not given).
1-Benzyl-3,5-dimethyl-4-(1,3-oxaselenolan-2-yl)-
1H-pyrazole (3a). Yield 0.267 g (83%), mp 63–65°С.
IR (KBr, ν, cm−1): 2923, 2858, 1568, 1495, 1434,
1261, 1190, 1177, 1057, 964, 852, 794, 758, 699, 650,
632, 597, 575.1Н NMR δ (ppm): 2.15 (s, 3Н, Ме-5),
2
3
3
2.27 (s 3Н, Ме-3), 3.33 (ddd, J = 9.1, J = 5.9, J =
2
3
3
10.4, 1H, SeCH2), 3.36 (ddd, J = 9.1, J = 5.6, J
2
3
= 1.6, 1Н, SeCH2), 3.67 (ddd, J = 10.2, J = 10.4,
3J = 5.6 Hz, 1Н, OCH2), 4.65 (ddd, J = 10.2, J =
2
3
5.9, 3J = 1.6 Hz, 1Н, OCH2), 5.18 (s, 2Н, NСН2),
2
6.27 (s, JH,Se = 14.4, 1Н, SeCHO), 7.06 (m, 2Н,
Но), 7.23 (m, 1Н, Нр), 7.28 (m, 2Н, Нm).13C NMR
δ (ppm): 10.26 (Me-5), 12.55 (Me-3), 29.94 (1JC–Se
= 63.5, SeCH2) 52.72 (NСН2), 73.03 (ОСН2), 75.30
(SeCHO), 113.84 (C-4), 126.69 (Cm), 127.53 (Cp),
128.73 (Co), 136.91 (Ci), 137.85 (C-5), 146.50 (C-3).
15N NMR δ (ppm): –192.1 (N-1), –98.2 (N-2). 77Se
NMR δ (ppm): 310.1. Anal. calcd for C15H18N2OSe:
С, 56.08; H, 5.65; N, 8.72; Se, 24.58. Found: C, 55.88;
H, 5.64; N, 8.68; Se, 24.90.
1-Benzyl-3,5-dimethyl-4-(1,3-oxaselenolan-2-yl)-
1H-pyrazole hydrochloride (2a). To a solution of
formylpyrazole 1a (0.214 g, 1 mmol) in CH2Cl2
(2 mL), a solution of 2-selanyl-1-ethanol (0.125
g, 1 mmol) in CH2Cl2 (1 mL) was added upon
stirring and bubbling of argon at room temperature.
The reaction proceeded with self-heating for 2 h.
Then, the solvent, excess Me3SiCl, and the formed
hexamethyldisiloxane were removed under reduced
pressure to give hydrochloride 2a as light-yellowish
flakes spreading in air, yield 0.346 g (98%). IR (neat,
ν, cm−1): 2746–2140 br (NH+). 1Н NMR δ (ppm):
2.35 (s, 3Н, Ме-5), 2.50 (s, 3Н, Ме-3), 3.33 (ddd, 2J =
1,3,5-Ttrimethyl-4-(1,3-oxaselenolan-2-yl)-1Н-
pyrazole (3b). Yield 0.191 g (78%), mp 70–72°С. IR
(KBr, ν, cm−1): 2920, 2857, 1567, 1435, 1380, 1264,
1180, 1055, 993, 965, 860, 838, 794, 710, 659, 632,
1
514. Н NMR δ (ppm): 2.23 (s, 3Н, Ме-3), 2.24 (s,
2
3
(3Н, Ме-5), 3.36 (dd, J = 9.2, J = 6.0, 1Н, SeCH2),
3
3
2
2
3
3
9.1, J = 6.2, J = 11.2, 1Н, SeCH2), 3.41 (dd, J =
9.1, 3J = 5.3, 1Н, SeCH2), 3.69 (ddd, 2J = 9.8,
3.38 (ddd, J = 9.2, J = 5.6, J = 1.5, 1Н, SeCH2),
2 3
3.67 (s, 3Н, NMe), 3.70 (dd, J = 9.7, J = 5.6, 1Н,
Heteroatom Chemistry DOI 10.1002/hc

6
Papernaya et al.
2
3
3
1475, 1432, 1265, 1190, 1175, 1052, 993, 963, 906,
858, 794, 723, 650. Н NMR δ (ppm): 2.23 (s, 3H,
OCH2), 4.67 (ddd, J = 9.7, J = 6.0, J = 1.5, 1Н,
OCH2), 6.27 (s, 2JH,Se = 14.4, 1Н, SeCHO). 13C NMR
1
2
3
δ (ppm): 10.15 (Me-5), 12.25 (Me-3), 29.84 (1JC–Se
=
Me-5), 2.25 (s, 3H, Me-3), 3.37 (ddd, J = 10.8, J =
3
2
3
5.5, J = 11.0, 1Н, SeCH2), 3.40 (ddd, J = 10.8, J
= 5.5, 3J = 1.7, 1Н, SeCH2), 3.70 (ddd, 2J = 9.2,
3J = 11.0, 3J = 5.5, 1Н, ОCH2), 4.60 (d, 3J = 5.3,
64.0, SeCH2), 35.64 (MeN), 72.96 (ОСН2), 75.35
(1JC–Se = 53.5, SeCHO), 113.26 (C-4), 137.73 (C-5),
145.85 (C-3). 15N NMR δ (ppm): –202.0 (N-1), –99.6
(N-2). 77Se NMR δ (ppm): 305.4. Anal. calcd for
C9H14N2OSe: C, 44.09; H, 5.76; N, 11.43; Se, 32.20.
Found: C, 43.87; H, 5.72; N, 11.37; Se, 32.36.
2
3
3
(2Н, СН2N), 4.68 (ddd, J = 9.2, J = 5.5, J = 1.7,
4
2
1Н, OCH2), 5.00 (ddt, Jtrans = 17.1, J = 1.5, J =
1.2, 1Н, СН2=), 5.18 (ddt, Jcis = 10.3, 2J = 1.2, 4J
= 1.2, 1Н, СН2= ), 5.91 (ddt, Jtrans = 17.1, Jcis
=
3
2
10.3, J = 5.3, 1Н, СН=). 6.28 (s, JH,Se = 14.6, 1Н,
SeCHO). 13C NMR δ (ppm): 10.02 (Me-5), 12.40
(Me-3), 29.85 (SeCH2), 51.49 (NСН2), 72.99 (ОСН2),
75.35 (SeCHO), 113.54 (C-4), 117.07 (=CH2), 132.97
(=CH), 137.70 (C-5), 145.93 (C-3). 15N NMR δ
(ppm): –193.6 (N-1), –99.8 (N-2). 77Se NMR δ (ppm):
311.3. Anal. calcd for C11H16N2OSe: С, 48.71; H,
5.25; N, 10.33; Se, 29.11. Found: С, 48.95; H, 5.28; N
10.38; Se 29.25.
3,5-Dimethyl-4-(1,3-oxaselenolan-2-yl)-1-propyl-
1Н-pyrazole (3c). Yield 0.153 g (56%), mp 55–56°С.
IR (KBr, ν, cm−1): 2960, 2862, 1565, 1458, 1430,
1379, 1267, 1205, 1175, 1052, 995, 963, 924, 859,
832, 795, 707, 648. Н NMR δ (ppm): 0.91 (t, J =
7.5, 3Н, MeСН2СН2), 1.78 (sextet, 3J = 7.5, 2Н,
MeСН2СН2), 2.23 (s, 3Н, Ме-3), 2.24 (s (3Н, Ме-5),
1
3
2
3
3
3.37 (ddd, J = 9.2, J = 6.0, J = 5.8, 1Н, SeCH2),
2
3
3
3.39 (ddd, J = 9.2, J = 11.0, J = 1.5, 1Н, SeCH),
2
3
3
3.69 (ddd, J = 10.0, J = 11.0, J = 5.8, 1Н, ОCH2),
3.89 (m (2Н, СН2N), 4.67 (ddd, 2J = 10.0, 3J =
5-Chloro-3-methyl-4-(1,3-оxaselenolan-2-yl)-1-
phenyl-1Н-pyrazole (3f). Yield 0.306 g (94%), mp
82–83°С. IR (KBr, ν, cm−1): 2964, 2864, 1597, 1560,
1501, 1415, 1381, 1332, 1264, 1180, 1055, 1003, 989,
966, 809, 770, 763. 1Н NMR δ (ppm): 2.40 (s, 3Н,
5.8, 3J = 1.5, 1Н, OCH2), 6.28 (s, JH,Se = 14.8,
2
1Н, SeCHO).13C NMR δ (ppm): 10.18 (Me-5), 12.46
(Me-3), 11.23 (MeСН2СН2), 23.64 (MeСН2СН2),
29.94 (1JC–Se = 63.5 Hz, SeCH2), 50.33 (СН2N), 73.00
(ОСН2), 75.49 (1JC–Se = 53.4 Hz, SeCHO), 112.86
(C-4); 137.26 (C-5), 145.98 (C-3).15N NMR δ (ppm):
–189.9 (N-1), –100.8 (N-2). 77Se NMR δ (ppm): 308.4.
Anal. calcd for C11H18N2OSe: С, 48.35; H, 6.64; N,
10.25; Se, 28.90. Found: C, 48.60; H, 6.61; N, 10.30;
Se, 28.77.
2
3
3
Me-3), 3.40 (ddd, J = 9.3, J = 5.8, J = 10.8, 1Н,
2
3
3
SeCH2), 3.43 (ddd, J = 9.3, J = 5.6, J = 1.0, 1Н,
SeCH2), 3.77 (ddd, 2J = 9.4, 3J = 10.8, 3J = 5.6,
2
3
3
1Н, OCH2), 4.75 (ddd, J = 9.4, J = 5.8, J = 1.0
2
Hz, 1Н, OCH), 6.37 (s, JH,Se = 14.9, 1Н, SeCHO),
7.39 (m, 1Н, Нр), 7.47 (m, 2Н, Нm), 7.51 (m, 2Н,
Но). 13C NMR δ (ppm): 13.64 (Me-3), 30.11 (1JC–Se
=
61.9 Hz, SeCH2), 73.62 (ОСН2), 73.57 (1JC–Se
=
1-Isopropyl-3,5-dimethyl-4-(1,3-oxaselenolan-
2-yl)-1H-pyrazole (3d). Yield 0.239 g (88%), mp
75–77°С. IR (KBr, ν, cm−1): 2977, 2856, 1569, 1491,
1437, 1261, 1177, 1056, 988, 963, 921, 850, 795,
652, 602. 1Н NMR δ (ppm): 1.43 (d, 3J = 6.6, 6Н,
Ме2СН), 2.25 (s, 3H, Me-5), 2,26 (s, 3H, Me-3), 3.36
55.5 Hz, SeCHO), 104.28 (C-5), 115.18 (C-4),
125.12 (Co), 128.26 (Cp), 129.09 (Cm), 138.22 (Ci),
149.43(C-3). 15N NMR δ (ppm): –187.6 (N-1), –92.2
(N-2). 77Se NMR δ (ppm): 317.5. Anal. calcd for
C13H13ClN2OSe: С, 47.65; H, 4.00; Cl, 10.82; N, 8.55;
Se, 24.10. Found: С, 47.89; H, 4.04; Cl, 10.85; N,
8.59; Se, 24.23.
2
3
3
(ddd, J = 9.2, J = 5.9, J = 9.9, 1Н, SeCH2), 3.40
(ddd, 2J = 9.2 Hz, 3J = 5.6 Hz, 3J = 0.9 Hz, 1Н,
2
3
3
SeCH2). 3.70 (ddd, J = 10.2, J = 9.9, J = 5.6, 1Н,
3
ОCH2), 4.34 (m, J = 6.6, 1Н, Ме2СН-N), 4.67 (ddd,
2J = 10.2, 3J = 5.9, 3J = 0.9, 1Н, OCH2), 6.29 (s,
2JH,Se = 14.4, 1Н, SeCHO). 13C NMR δ (ppm): 10.09
ACKNOWLEDGMENT
The study of the structures of the compounds ob-
tained was conducted with equipment of Baykal An-
alytical Center for Collective Use, Siberian Branch
of the Russian Academy of Sciences.
(Me-5), 12.67 (Me-3), 22.47 (Me2СН), 29.94 (1JC–Se
=
62.7, SeCH2), 73.01 (ОСН2), 75.69 (SeCHO), 49.32
(Me2СН-N), 115.18 (C-4), 136.43 (C-3), 145.93 (C-5).
15N NMR δ (ppm): –178.9 (N-1), –107.5 (N-2). 77Se
NMR δ (ppm): 305.7. Anal. calcd for C11H18N2OSe:
С, 48.35; H, 6.64; N, 10.25; Se, 28.90. Found: С,
48.58; H, 6.62; N, 10.31; Se, 28.74.
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Heteroatom Chemistry DOI 10.1002/hc

2-(Pyrazol-4-yl)-1,3-oxaselenolanes from Pyrazole Сarbaldehydes and 2-Selanyl-1-ethanol
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