Synthesis of 2,3,5-Substituted 1H-Pyrroles by a Cp2TiCl2-catalyzed Multicomponent Reaction of Terminal Alkynes with Nitriles and EtAlCl2

Article abstract of DOI:10.1134/S1070428020020074

Abstract: A one-pot synthesis of 2,3,5-substituted 1H-pyrroles with yields of 37–77% by the reaction of terminal alkynes with aromatic and heteroaromatic nitriles in the presence of EtAlCl₂ and the Cp₂TiCl₂ catalyst has been developed. Spectral-luminescent properties were studied and intense photoluminescence of 2,3,5-triphenyl-1H-pyrrole, 3-(2-phenylethyl)-2,5-diphenyl-1H-pyrrole, and 2,5-diphenyl-3-(pyridin-2-yl)-1H-pyrrole had been detected.

Full text of DOI:10.1134/S1070428020020074

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2020, Vol. 56, No. 2, pp. 218–224. © Pleiades Publishing, Ltd., 2020.
Russian Text © The Author(s), 2020, published in Zhurnal Organicheskoi Khimii, 2020, Vol. 56, No. 2, pp. 210–217.
Synthesis of 2,3,5-Substituted 1H-Pyrroles
by a Cp2TiCl2-catalyzed Multicomponent Reaction
of Terminal Alkynes with Nitriles and EtAlCl2
L. O. Khafizovaa,*, M. G. Shaibakovaa, N. A. Richtera, and U. M. Dzhemileva
a Institute of Petrochemistry and Catalysis, Russian Academy of Sciences, Ufa, 4500075 Russia
*e-mail: leilakh@mail.ru
Received July 31, 2019; revised November 10, 2019; accepted November 27, 2019
Abstract—A one-pot synthesis of 2,3,5-substituted 1H-pyrroles with yields of 37–77% by the reaction of termi-
nal alkynes with aromatic and heteroaromatic nitriles in the presence of EtAlCl2 and the Cp2TiCl2 catalyst has
been developed. Spectral-luminescent properties were studied and intense photoluminescence of 2,3,5-triphe-
nyl-1H-pyrrole, 3-(2-phenylethyl)-2,5-diphenyl-1H-pyrrole, and 2,5-diphenyl-3-(pyridin-2-yl)-1H-pyrrole hab
been detected.
Keywords: 1H-pyrroles, terminal alkynes, nitriles, EtAlCl2, Cp2TiCl2 catalyst
DOI: 10.1134/S1070428020020074
We recently reported [1] that terminal alkynes react
with aromatic nitriles and EtAlCl2 (alkyne : [Al] : RCN :
Mg : [Ti] = 1 : 4 : 2 : 4 : 0.1, THF–hexane (3 : 1), 0°C,
8 h) to form 2,3,5-substituted 1H-pyrroles 1 in yields of
58–77% (Scheme 1).
selectivity of the multicomponent reaction leading to
pyrrole formation [1], we have investigated this reaction
in detail using a number of functionally substituted
alkynes, as well as aromatic and heteroaromatic nitriles
as an example.
However, the number of alkynes and aromatic
nitriles involved in this reaction was quite small [1]. It
should be noted that the pyrrole ring is a component of
many important biologically active natural compounds,
such as hemoglobin, chlorophyll, bilirubin, and B
vitamins, which are involved in the vital functions of
humans, animals, and plants [2–6]. Moreover, most of
both known and developed drugs are pyrrole derivatives
[7–12]. In view of the aforesaid, as well as the relevance
of the development of a universal and technologically
simple synthesis of substituted pyrroles, we decided
to proceed with our previously initiated research into
pyrrole synthesis.
As the objects of study, we have selected oct-1-yne,
phenylacetylene, (trimethylsilyl)acetylene, 2-ethynyl-
pyridine, 2-ethynylthiophene, 2-ethynylfuran, 3-chloro-
prop-1-yne, 3-bromoprop-1-yne, 4-bromobut-1-yne, аs
well as such aromatic and heteroaromatic nitriles such
as benzonitrile, furan-2-carbonitrile, and thiophene-2-
carbonitrile (Scheme 2).
The reactions of oct-1-yne or phenylacetylene with
furan-2-carbonitrile or thiphene-2-carbonitrile under the
above conditions gave the corresponding trisubstituted
pyrroles 2a, 2b and 3a, 3b in yields of 37–46%
(Scheme 3).
As seen, the yields of the target pyrroles in our present
experiments were slightly lower than in the experiments
To find out how the structure of the starting terminal
alkynes and nitriles affect the direction and structural
Scheme 1.
R1
1. Mg, Cp2TiCl2 (10 mol %)
THF–hexane (3 : 1), 0oC, 8 h
2R2CN + EtAlCl2
R1
+
R2
R2
2. H2O
N
H
1, 58–77%
218

SYNTHESIS OF 2,3,5-SUBSTITUTED 1H-PYRROLES
219
Scheme 2.
SiMe3
Ph
Hex
O
S
N
C
N
C
N
Br
C
N
Cl
O
Br
S
with benzonitrile [1] because of the competing
homocyclotrimerization of the starting alkynes to give
trisubstituted benzenes.
molecules of the starting nitrile then insert into the
active Ti–C bonds of titanacyclopropene 12, yielding
diaminotitanacycloheptatriene 13. The transmetalation
of the latter with EtAlCl2 resulted in diаminо-alumina-
cycloheptatriene 14 with the simultaneous regeneration
of the Cp2TiCl2 catalyst. Hydrolysis and subsequent
transformations of intermediate 14 give rise to pyrroles
8a and 9a. Correspondingly, deuterolysis leads to
deuterated pyrroles 8b and 9b.
Ourattemptstoperformthereactionbetweenterminal
alkynes and benzonitriles containing electron-acceptor
substituents (Cl, Br, F, CN, NO2, NH2, OH) under the
above conditions were unsuccessful. Similar results
were also obtained with aliphatic nitriles (acetonitrile,
n-butyronitrile, iso-valeronitrile).
π-Conjugated systems containing pyrrole and
benzene rings hold promise as the key components
for organic semiconductors, LEDs, solar panels,
and nanocomposites [13–18]. Such compounds
actively absorb the UV light and exhibit their specific
fluorescence (FL) [19].
At the same time, benzonitrile fairly readily reacts
with both alkyl(cycloalkyl, phenyl)-substituted alkynes
[1] and functionally substituted alkynes to form the
corresponding 2,3,5-substituted 1H-pyrroles 4–9 in
yields of 34–77% (Scheme 4).
Thestructureofpyrroles4–9wasconfirmedbymodern
physicochemical methods of analysis [one-dimen-
sional (1H, 13C, Dept 135) and two-dimensional (HSQC,
HMBC, and HH COSY) NMR spectroscopy, and gas
chromatography–mass spectrometry]. It should be
noted that pyrroles, which derived from halo-substi-
tuted alkynes and benzonitrile, contain no halogen atom.
Obviously, the starting halo-substituted alkyne reacts
with excess Mg to give Grignard reagent 10, and the
subsequent reaction of the latter with titanacene 11
leads to titanacyclopropene 12 (Scheme 5). Two
We have performed a comparative spectral lumine-
scent study of the synthesized aromatically substituted
pyrroles: 2,5-diphenyl-3-(pyridin-2-yl)-1H-pyrrole (5),
2,3,5-triphenyl-1H-pyrrole (15) [1], and 2,5-diphenyl-
3-(2-phenylethyl)-1H-pyrrole (16) [1] (Table 1).
Figure 1 shows the absorption and FL spectra of
compounds 5, 15, and 16 in THF. The absorption
spectrum displays maxima at 305 (5), 320 (15), and
315 nm (16) (ε 12500, 98000, and 12100 L·mol–1·cm–1,
respectively). The separation of one of the aryl subs-
Scheme 3.
R
CN
CN
O
N
O
O
H
2a, 2b
37–40%
Mg, Cp2TiCl2
+
R
EtAlCl2
THF–hexane
R
S
N
H
S
S
3a, 3b
42–46%
R = C6H13 (a), Ph (b).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 56 No. 2 2020

220
KHAFIZOVA et al.
Scheme 4.
Me3Si
Ph
SiMe3
38%
N
N
52%
Ph
Ph
N
Ph
Ph
N
H
4
H
5
S
S
O
O
i
i
Ph
PhCN
N
H
54%
34%
Ph
Ph
N
H
7
6
(D)H
(D)H
Ph
Br
Cl(Br)
75%
Ph
Ph
Ph
N
N
77%
H(D)
8a, 8b
H(D)
9a, 9b
(i) – 1. EtAlCl2, Mg, Cp2TiCl2 (10 mol %), THF–hexane (3 : 1), 0°C, 8 h;
2. H2O (D2O).
tituentsfromthepyrroleringsbytwocarbonatoms(com-
pound 16) or the appearance of a heteroatom in the aryl
substituent (compound 5) induce a blue shift of the lumi-
nescentmaximumcomparedtocompound15(396nm)to
383(for5)and380(for16)nm.Thequantumyieldsofthe
studied compounds were ~ 35% (for 5 and 15) and 61%
(for 16).
stationary phase 5% SE-30 on Chromaton N-AW-
HMDS (0.125–0.160 mm), carrier gas He (30 mL/min),
temperature programming from 50 to 300°С at a
rate of 8 deg/min. The 1D (1H, 13C) and 2D homo-
(COSY) and heteronuclear (HSQC, HMBC) NMR
spectra of the reaction products were recorded in
CDCl3 on a Bruker Avance 400 spectrometer [400.13
(1H) and 100.62 (13C) MHz], the chemical shifts
were referred to TMS. Gas chromatography–mass
spectrometry was performed on a Finigan 4021 system
(glass capillary column 50000 × 0.25 mm, stationary
phase HP-5, carrier gas He, temperature programming
from 50 to 300°С at a rate of 5 deg/min, injector
temperature280°С,ionsourcetemperature250°С,70eV).
The elemental compositions were obtained on a
Carlo Erba 1106 analyzer. The reaction progress was
monitored by TLC on Sorbfil PTSKh-AF-V plates,
eluent hexane–ethyl acetate (100 : 1–9), visualization in
iodine vapor. Column chromatography was performed
on Acrus silica gel (0.060–0.200 mm). Reactions with
organometallic reagents were carried out under dry
argon. THF was dried by refluxing over Na metal and
used freshly distilled. Commercial EtAlCl2 was used as
received.
The synthesized aromatically substituted 1H-
pyrroles show moderate fluorescence and high quantum
yields and can be used as efficient components of
optical devices, for example, violet and blue organic
luminescent diodes.
Thus, we have developed a method for the synthesis
of 2,3,5-substituted 1H-pyrroles by the reaction of
terminal alkynes with aromatic nitriles and EtAlCl2,
catalyzed by Cp2TiCl2. We have also studied the effect
of the starting terminal alkynes and organic nitriles on
the reaction direction. It was shown that the developed
reaction is very sensitive to the structure of the starting
alkynes and nitriles. Aromatic and heteroaromatic
nitriles quite successfully react with terminal alkynes
containing aliphatic, cycloaliphatic, aromatic, and
heteroaromatic substituents.
EXPERIMENTAL
The FL spectra and the lifetimes of the excited states
were measured on a Fluorolog-3 spectrofluorimeter
Chromatographic analysis was performed on a
Shimadzu GC-9Achromatograph, column 2000 × 2 mm,
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 56 No. 2 2020

SYNTHESIS OF 2,3,5-SUBSTITUTED 1H-PYRROLES
221
Scheme 5.
MgHal
Hal
10
H(D)
Ph
MgHal
Cp2Ti
Ph
N
"Cp2Ti"
TiCp2
MgCl2
Mg
11
H(D)
12
8a, 8b–9a, 9b
2PhCN
MgHal
Ph
Ph
H(D)
Ph
Ph
N
N
+
Cp2TiCl2
Ti
N
H(D)3N
Cp2
H(D)
13
–Cp2TiCl2
EtAlCl2
H(D)2O
MgHal
Ph
H(D)
Ph
Ph
Ph
H(D)2O
N
H(D)
N
H(D)
N
N
Al
Et
14
equipped with a Hamamatsu P928 detector. Compounds
5, 15, and 16 in THF solutions (10–3 M) in quartz cells
(l 1 cm), were exposed to radiation of a 450-W xenon
lamp or a NanoLED pulsed excitation source. The FL
quantum yields (φ) were determined from a comparison
of integral intensities by the procedure described in [20].
A 10–5 M solution of anthracene in ethanol was used as a
fluorescence standard (φFL 0.28). The absorption spectra
were recorded on an Agilent Cary-60 spectrophotometer
in sealed 0.1- or 1-cm quartz cells. The experiments
were carried out at room temperature (298 K).
Compounds 2–9 (general procedure).Acooled glass
reactor mounted on a magnetic stirrer was charged with
45 mL of THF, 3.5 mL (25 mmol) of EtAlCl2, 0.28 g
(12 mmol) of Mg powder, and 0.248 g (1 mmol) of
Cp2TiCl2 under argon and cooling at 0°С. After 15-min
stirring at 0°С until a green color appeared, 10 mmol
Table 1. Spectral luminescence characteristics of compounds 5, 15, and 16 in THF at 298 K
Absorption
λmax, cm–1
ε
FL
max, nm
Lifetime
τ, nsа
Quantum yield
Stokes shift Δνs,
Соmpound
L mol–1 cm–1
λ
φ, %
cm–1
5
32600
31100
31700
12500
98000
12100
383
396
380
1.7
2.2
1.7
0.34
0.33
0.61
6500
6000
5400
15
16
а Registered under a NanoLED-295 pulsed excitation radiation (λexc 294nm).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 56 No. 2 2020

222
KHAFIZOVA et al.
135.52, 141.72, 142.84, 145.05, 147.22. Mass spectrum,
1
1.0
0.5
0.0
1.0
0.5
0.0
m/z: 275 [М]+. Found, %: C 78.51; H 4.77. C18H13NО2.
Calculated, %: C 78.53; H 4.76; N 5.09; О 11.62.
2
3
5
15
16
6
4
5
3-Hexyl-2,5-di(thioiphen-2-yl)-1H-pyrrole (3a).
Yield 1.32 g (42%). Light brown oily liquid. Rf 0.53
(hexane‒ethylacetate,100:7).IRspectrum(film),ν,cm–1:
3437, 3088, 2960, 2870, 1717, 1460, 1111, 813, 808. 1Н
NMRspectrum,CDCl3,δ,ppm:0.91t(3H,CH3,J8.0Hz),
1.34 m (4H, CH2), 1.42 m (2H, CH2), 1.64 quintet (2H,
CH2, J 8.0 Hz), 2.63 t (2H, CH2, J 8.0 Hz), 6.50 d.d (1H,
СНthioph, J 3.6, 1.1 Hz), 6.63 d.d (1H, СНthioph, J 3.6,
1.2 Hz), 6.71 d (1H, СH, J 4.0 Hz), 6.82 m (1H, СHthioph),
7.03 d.d (1H, СHthioph, J 5.1, 1.1 Hz), 7.10–7.15 m (2H,
2СHthioph), 8.34 br.s (1H, NH). 13С NMR spectrum,
δ, ppm: 14.61, 22.69, 26.84, 29.25, 31.11, 32.18,
108.28, 124.13, 124.98, 125.54, 126.91, 127.39, 128.63,
129.13, 129.51, 132.43, 132.93, 133.02. Mass spectrum,
m/z: 315 [М]+. Found, %: C 68.53; H 6.76. C18H21NS2.
Calculated, %: C 68.52; H 6.71; N 4.44; S 20.33.
300
350
400
Ȝ, nm
450
500
Fig. 1. (1, 2, 3)Absorption and (4, 5, 6) fluorescence spectra of
compounds 5, 15, and 16. T 298 K, λexc 315 nm, Fluorolog-3,
Δλ 1 nm.
of acetylene and 20 mmol of nitrile were added. The
reaction mixture was stirred for 8 h, cooled to 0°С, and
30 mL of Et2O and 0.1 M NaOH (3.5 mL) were added
one after another. The organic layer was separated, and
the inorganic layer was treated with 3 portions of ether.
The combined organic extracts were dried over MgSO4
and passed through the SiO2 layer. The solvent was
evaporated under a vacuum, and the target compound
was isolated by column chromatography in hexane–
ethyl acetate.
3-Phenyl-2,5-di(thioiphen-2-yl)-1H-pyrrole (3b).
Yield 1.41 g (46%), mp 118–119°C. Yellow powder. Rf
0.59 (hexane–ethyl acetate, 100 : 9). IR spectrum (film),
1
ν, cm–1: 3435, 3098, 2962, 2873, 1943, 1194, 791. Н
NMR spectrum, CDCl3, δ, ppm: 6.53 d.d (1H, СНthioph
,
J 3.6, 1.1 Hz), 6.65 d.d (1H, СНthioph, J 3.6, 1.2 Hz), 6.74
d (1H, СH, J 4.0 Hz), 6.83 m (1H, СHthioph), 7.05 d.d
(1H, СHthioph, J 5.1, 1.1 Hz), 7.14–7.20 m (3H, CHarom
,
2СHthioph), 7.23–7.54 m (4Harom), 8.34 br.s (1H, NH).
13С NMR spectrum, δ, ppm: 108.61, 124.40, 124.83,
125.71, 126.51, 126.75, 127.12, 128.31, 128.58, 128.94,
129.04,129.42, 132.34, 132.86, 133.61, 135.82. Mass
spectrum, m/z: 307 [М]+. Found, %: C 70.29; H 4.25.
C18H13NS2. Calculated, %: C 70.32; H 4.26; N 4.56;
S 20.86.
2,5-Di(furан-2-yl)-3-hexyl-1H-pyrrole (2a). Yield
1.04 g (37%). Yellow oily liquid. Rf 0.53 (hexane‒ethyl
acetate, 100 : 3). IR spectrum (film), ν, cm–1: 3431,
2958, 2872, 1716, 1458, 802. 1Н NMR spectrum, CDCl3,
δ, ppm: 0.91 t (3H, CH3, J 8.0 Hz), 1.36 m (4H, CH2),
1.45 m (2H, CH2), 1.67 quintet (2H, CH2, J 8.0 Hz),
2.67 t (2H, CH2, J 8.0 Hz), 5.34 d (1H, СHfur, J 3.3 Hz),
5.84–5.90 m (1H, СHfur), 6.22 m (2H, 2СHfur), 6.35 d
(1H, СH, J 4.0 Hz), 7.20 m (1H, СНfur), 7.32 d (1H,
СНfur, J 0.9 Hz), 8.32 br.s (1H, NH). 13С NMR spectrum,
δ, ppm: 14.31, 22.85, 29.58, 31.35, 32.03, 26.94,
104.35, 108.96, 111.02, 111.57, 112.24, 123.59, 128.37,
130.04, 141.51, 142.13, 145.61, 147.54. Mass spectrum,
m/z: 283 [М]+. Found, %: C 76.33; H 7.50. C18H21NO2.
Calculated, %: C 76.29; H 7.47; N 4.94; О 11.29.
3-(Trimethylsilyl)-2,5-diphenyl-1H-pyrrole (4).
Yield 1.11 g (38%). Light orange oily liquid. Rf 0.59
(hexane‒ethyl acetate, 100 : 2). IR spectrum (film), ν,
cm–1: 3450, 3061, 3019, 2957, 2850. 1Н NMR spectrum,
CDCl3, δ, ppm: 0.12 s (9Н, 3СН3), 6.57 d (1H, CH, J
4.0 Hz), 7.22–7.54 m (10Harom), 8.24 s (1H, NH). 13С
NMR spectrum, δ, ppm: 0.54, 113.81, 117.25, 123.98,
126.12, 126.61, 127.36, 128.74, 128.85, 133.45, 134.83,
135.41,142.06.Massspectrum,m/z:291[М]+.Found,%:
C 78.33; H 4.31. C19H21NSi. Calculated, %: C 78.30;
H 7.26; N 4.81; Si 9.64.
2,5-Di(furаn-2-yl)-3-phenyl-1H-pyrrole(2b).Yield
1.1 g (40%), mp 87–89°C. Light yellow powder. Rf 0.56
(hexane‒ethylacetate,100:3).IRspectrum(film),ν,cm–1:
3429,3067,2958,2861,1718.1НNMRspectrum,CDCl3,
δ, ppm: 5.28 d (1H, СHfur, J 3.3 Hz), 5.86–5.93 m (1H,
СHfur), 6.19 m (2H, 2СHfur), 6.39 d (1H, СH, J 4.0 Hz),
7.12–7.41m(7Н,5CHarom,2СНfur),8.39br.s(1H,NH).13С
NMR spectrum, δ, ppm: 105.82, 108.61, 110.81, 111.23,
111.94, 123.16, 126.32, 127.42, 128.06, 129.03, 129.42,
2-(2,5-Diphenyl-1H-pyrrole-3-yl)pyridine
(5).
Yield 1.54 g (52%). Light cream powder, mp 83–85°C.
Rf 0.61 (hexane–ethyl acetate, 100 : 5). IR spectrum
(film), ν, cm–1: 3451, 3059, 3023, 2958, 2852, 1720.
1Н NMR spectrum, CDCl3, δ, ppm: 6.65 s (1H, CH),
6.90‒7.28 m (12H, CH), 7.53 m (1H, CH), 8.05 d (1H,
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 56 No. 2 2020

SYNTHESIS OF 2,3,5-SUBSTITUTED 1H-PYRROLES
223
CH, J 12.0 Hz), 8.85 s (1H, NH). 13С NMR spectrum,
δ, ppm: 107.79, 119.94, 122.06, 123.86, 125.19, 125.82,
127.65, 127.95, 128.12, 128.29, 128.47, 130.54, 132.55,
133.38, 135.25, 146.15, 149.13. Mass spectrum, m/z:
296 [М]+. Found, %: C 85.14; H 5.40. C21H16N2.
Calculated, %: C 85.11; H 5.44; N 4.95.
acetate, 100 : 1). IR spectrum (film), ν, cm–1: 3450, 3061,
3023, 2957, 2851, 1761, 1107, 802. 1Н NMR spectrum,
CDCl3, δ, ppm: 0.94 t (3H, CH3, J 8.0 Hz), 1.34‒1.45 m
(2H, CH2), 2.24 t (3H, CH2, J 8.0 Hz), 6.52 s (1H, CH),
7.28–7.54 m (10Harom), 8.36 br.s (1H, NH). 13С NMR
spectrum, δ, ppm: 14.03, 23.76, 29.69, 108.32, 123.63,
123.89, 126.75, 127.85, 128.81, 129.39, 129.91, 130.86,
131.58, 132.37, 133.61. Mass spectrum, m/z: 261 [М]+.
Found, %: C 87.29; H 7.30. C19H19N. Calculated, %: C
87.31; H 7.33; N 5.36.
2,5-Diphenyl-3-(thiophen-2-yl)-1H-pyrrole (6).
Yield 1.62 g (54%). Brown powder, mp 96–98°C. Rf
0.55 (hexane–ethyl acetate, 100 : 3). IR spectrum (film),
ν, cm–1: 3449, 3098, 3059, 3030, 2960, 2853, 1414,
1
720. Н NMR spectrum, CDCl3, δ, ppm: 6.74 s (1H,
3-(3-Deuteropropyl)-2,5-diphenyl-1D-pyrrole
(9b). Rf 0.49 (hexane‒ethyl acetate, 100 : 1). IR spectrum
(film), ν, cm–1: 2170 (CD). 1Н NMR spectrum, CDCl3,
δ, ppm: 0.94 t (2H, CH2D, J 8.0 Hz), 1.34‒1.45 m (2H,
CH2), 2.24 t (3H, CH2, J 8.0 Hz), 6.52 s (1H, CH), 7.28–
7.54 m (10Harom). 13С NMR spectrum, δ, ppm: 13.74 t
(JCD 19.0 Hz), 23.72, 29.64, 108.28, 123.61, 123.87,
126.73, 127.82, 128.76, 129.33, 129.79, 130.82, 131.63,
132.34, 133.58. Mass spectrum, m/z: 263 [М]+.
СH), 7.16 d.d (1H, СHthioph, J 5.1, 1.1 Hz), 7.20–7.41 m
(12Н,10CHarom,2СНthioph),9.20br.s(1H,NH).13СNMR
spectrum,δ,ppm:108.16,119.95,123.98,124.89,125.45,
126.37, 127.92, 128.12, 128.53, 128.58, 128.68, 128.72,
128.90, 132.15, 132.28, 132.80. Mass spectrum, m/z:
301 [М]+. Found, %: C 79.66; H 4.70. C20H15NS.
Calculated, %: C 79.70; H 5.02; N 4.65; S 10.64.
2,5-Diphenyl-3-(furan-2-yl)-1H-pyrrole (7). Yield
0.97 g (34%). White powder, mp 69–71°C. Rf 0.49
(hexane‒ethylacetate,100:2).IRspectrum(film),ν,cm–1:
ACKNOWLEDGMENTS
The authors are grateful to Can. Sci. (Phys.-Math.)
А.A. Tukhbatullin for help in spectral luminescence
measurements and discussion of their results. The structural
research was performed using a unique equipment at the
Agidel Regional Center for Collective Use, Institute of
Petrochemistry and Catalysis, Ufa Research Center, Russian
Academy of Sciences.
1
3447, 3429, 3059, 2960, 2871, 1761, 715. Н NMR
spectrum, CDCl3, δ, ppm: 6.22 d (1H, СHfur, J 12.0 Hz),
6.37 d (1H, СHfur, J 3.2 Hz), 6.61 d (1H, CH, J 3.4 Hz),
7.19–7.54 m (11H, 10CHarom, СНfur), 8.45 br.s (1H, NH).
13С NMR spectrum, δ, ppm: 108.59, 110.21, 113.51,
118.94, 126.16, 126.51, 127.42, 128.81, 128.95, 129.12,
129.54, 131.72, 132.54, 133.55, 140.42, 152.31. Mass
spectrum, m/z: 285 [М]+. Found, %: C 84.22; H 5.29.
C20H15NO. Calculated, %: C 84.19; H 5.30; N 4.91;
О 5.61.
FUNDING
The work was financially supported by the
Russian Foundation for Basic Research (project no. 17-43-
020676 р_а). Structural research was funded by the Ministry
for Education and Science of the Russian Federation (FTsP
grant no. 2019-05-595-000-058).
3-Methyl-2,5-diphenyl-1H-pyrrole (8a). Yield
1.74 g (75%). Light brown oily liquid. Rf 0.48 (hexane‒
ethyl acetate, 100 : 1). IR spectrum (film), ν, cm–1: 3453,
CONFLICT OF INTEREST
The authors declare no conflict of interest.
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3063, 3023, 2956, 2853, 1760, 1108, 720. Н NMR
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132.34,133.33.Massspectrum,m/z:233[М]+.Found,%:
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