Ultrasound-promoted regioselective synthesis of chalcogeno-indolizines by a stepwise 1,3-dipolar cycloaddition

Article abstract of DOI:10.1016/j.ultsonch.2020.105228

A series of new organochalcogen derivatives of indolizines was synthesized in moderate to excellent yields from pyridinium salts and chalcogeno-alkynes. The reaction can be carried out under thermal conditions or by sonochemical processes in short reaction times. The stepwise cycloaddition reaction forming chalcogeno-indolizines is regioselective and extends to a broad range of functional groups. Furthermore, novel chalcogeno-alkynes are reported and the first derivatives of teluro-indolizine are described. The influence of selenium functionalization on the photophysical properties of indolizines is also described, in which the compounds showed absorption in the UV–Vis region around 360 nm and emission in the blue-to-green region. Relatively low fluorescence quantum yield (?_fl) values were calculated, in agreement with the chalcogen effect on other heterocycles.

Full text of DOI:10.1016/j.ultsonch.2020.105228

Journal Pre-proofs
Ultrasound-promoted regioselective synthesis of chalcogeno-indolizines by a
stepwise 1,3-dipolar cycloaddition
Marcelo M. Vieira, Bianca T. Dalberto, Felipe L. Coelho, Paulo H. Schneider
PII:
S1350-4177(20)30417-X
DOI:
Reference:
https://doi.org/10.1016/j.ultsonch.2020.105228
ULTSON 105228
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Ultrasonics Sonochemistry
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Revised Date:
Accepted Date:
5 March 2020
20 May 2020
11 June 2020
Please cite this article as: M.M. Vieira, B.T. Dalberto, F.L. Coelho, P.H. Schneider, Ultrasound-promoted
regioselective synthesis of chalcogeno-indolizines by a stepwise 1,3-dipolar cycloaddition, Ultrasonics
Sonochemistry (2020), doi: https://doi.org/10.1016/j.ultsonch.2020.105228
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Ultrasound-promoted regioselective synthesis of chalcogeno-indolizines
by a stepwise 1,3-dipolar cycloaddition
Marcelo M. Vieira, Bianca T. Dalberto, Felipe L. Coelho, Paulo H. Schneider*
Federal University of Rio grande do Sul (UFRGS), Chemistry Institute
Av. Bento Gonçalves 9500. CEP 91501-970, PO Box 15003, Porto Alegre, RS, Brazil.
*Corresponding Author: Paulo Henrique Schneider
E-mail: paulos@iq.ufrgs.br, +55 51 3308 9636
Keywords: Cycloaddition • Fluorescence • Indolizines • Selenium • Ultrasound
Abstract: A series of new organochalcogen derivatives of indolizines was synthesized
in moderate to excellent yields from pyridinium salts and chalcogeno-alkynes. The
reaction can be carried out under thermal conditions or by sonochemical processes in
short reaction times. The stepwise cycloaddition reaction forming chalcogeno-
indolizines is regioselective and extends to a broad range of functional groups.
Furthermore, novel chalcogeno-alkynes are reported and the first derivatives of teluro-
indolizine are described. The influence of selenium functionalization on the
photophysical properties of indolizines is also described, in which the compounds
showed absorption in the UV-Vis region around 360 nm and emission in the blue-to-
green region. Relatively low fluorescence quantum yield (fl) values were calculated, in
agreement with the chalcogen effect on other heterocycles.
Introduction
Within the whole class of N-heterocycles, the indolizine core has a set of
properties, including aromaticity, planarity, physiologically compatible polarity,
protonation site, and fluorescence, that allow a diverse range of application in both
medicinal and materials chemistry.[1] Although the natural occurrence is low, synthetic
derivatives have shown substantial biological activity as cardiovascular agents,[2] anti-
inflammatories,[3] anticancer agents,[4] antibacterials,[5] central nervous system

depressants, calcium entry blockers,[6] and phosphatase inhibitors,[7] among others. On
the other hand, the optical properties, such as absorption/emission profile, fluorescence
quantum efficiency, and electronic properties,[8] have been explored in
electroluminescent material for optoelectronic devices,[9] dyes,[10] sensors,[11] and
biomarkers[12] comprising pH and turn-on/off fluorescent sensors,[13] detection of
volatile organic compounds,[14] cell labelling,[12] dye-sensitized solar cells[15] and
photoresponsive materials.[16] Some of example compounds and applications are
illustrated in Figure 1.
Bioimaging fluorescent probe
Me
O
PO3H2
Ph
CO2Me
N
N
O
S
N
N
CHO
NH2
NC
Sensitizer component for DSCs
CO2H
O
Turn-on/off fluorescent sensor
Figure 1. Some emissive indolizine derivatives and their respective applications.
Since the first reported synthesis by Scholtz in 1912,[17] numerous methods for
the preparation and functionalization of indolizines have been developed, including
different starting materials and synthetic approaches.[1] Reflecting the structural
features, most protocols are based on pyrrole and pyridine derivatives as building
blocks, through condensation reactions, 1,3-dipolar cycloadditions, or 1,5-dipolar
cycloadditions.[18]
Moreover, with the increasing interest in the development of more efficient
methodologies in organic synthesis, ultrasound-assisted protocols emerge as an
alternative to traditional methods, enhancing reaction rates, allied to high yield, simple
and controllable experimental conditions, and waste minimization.[19]
The acceleration of reactions provided by ultrasound irradiation is attributed to
the formation, growth, and implosive collapse of bubbles in liquid, creating
microreactors and contributing to the dispersion of materials in a finely divided form.
All of these characteristics put sonochemistry among the privileged green chemical
methods.[20] In Scheme 1, some important protocols for the synthesis of indolizines
under ultrasound irradiation are presented.[21] A variety of structures can be obtained [22]
by the proper choice of starting materials.[23]

On the other hand, even though selenium compounds have been continuously
attracting the interest of chemists, because of their several biological, medicinal and
technological applications, few protocols are reported for the synthesis of selenium-
containing indolizines (Scheme 1d).[24] Usually, these chalcogeno-indolizines were also
obtained through the cyclization of propargylpyridines with diorganyl dichalcogenides,
catalyzed by copper(I) iodide[25] or by functionalization of an indolizine core with
diorganyl dichalcogenides, by metalation with organometallic bases[26] or palladium(II)
or copper(II) catalysis.[27]
Previous work
1. CF2Br2, Pb, Bu4NBr,
ultrasound
CO2Me
2.
MeO2C
CO2Me
CO2Me
R1
R1
16-48%
(Ref. 21)
(Ref. 22)
N
3. MnO2
N
F
CN
CN
CN
Ph
O
Ph
N
N
R1
NEt3, ultrasound
Br
Cl
O
R1
91-94%
EtO2C
(Ref. 23)
O
O
biocatalyst
Br
N
N
Ph
Ph
N
N
O
+
phosphate buffer
(pH = 7), ultrasound
O
Ph
60-67%
CO2Et
OEt
YR
K2CO3, glycerol
YR
Ph
(Ref. 24)
N
N
ultrasound, 5 min
Ph
Br
Y = S, Se; R = alkyl, aryl
O
This work
Y
R3
CO2R
Y
R3
CO2R
R1
R1
N
N
Cs2CO3
DMF,ultrasound,
5 min
Br
R2
R2
O
O
Y = Se, Te
Scheme 1. General protocols for indolizine functionalization under ultrasound.

With this in mind, and in line with our continuous interest in synthesis of
chalcogen compounds,[28] the present work describes the regioselective synthesis of
chalcogeno-indolizines. The efficiency of the stepwise 1,3-cycloaddition between
pyridinium ylides and alkynes promoted by ultrasound irradiation appears not to have
been investigated previously. Furthermore, novel chalcogeno-alkynes and the first
teluro-indolizine derivatives are described. A photophysical study of a chalcogen-
indolizine is presented, in which the influence of the chalcogen atom on the
photophysical properties of the indolizine core is evaluated.
Experimental
Hydrogen Nuclear Magnetic Resonance (1H NMR), Carbon-13 Nuclear
Magnetic Resonance (13C NMR) and Selenium-77 Nuclear Magnetic Resonance (77Se
NMR) spectra were recorded in CDCl3 or DMSO-d6 solutions on a Varian 400 MHz
and Bruker 400 MHz spectrometers. Chemical shifts () are given in part per million
from the solvent peak of CDCl3 at δ = 7.26 ppm (1H NMR) and δ = 77.16 ppm (13C
NMR) and DMSO-d6 at δ = 2.50 ppm (1H NMR) and δ = 39.52 (13C NMR) or from the
1
13
signal of tetramethylsilane at δ = 0.00 ppm in H NMR and C NMR, or diphenyl
77
diselenide at δ = 463 ppm for Se NMR, as internal standards. Data are reported as
follows: chemical shift (δ), multiplicity, coupling constant (J) in Hertz and integrated
intensity. High resolution mass spectra (HMRS) were recorded on a Micromass Q-Tof
spectrometer, using electrospray ionization (ESI). Melting points were determined on a
Buchi Melting Point M-545. Column chromatography was performed using silica gel
(230-400 mesh). The ultrasound-promoted reactions were performed using a Branson
Digital Sonifier model W-450 D, with a maxim power of 400ꢀW, operating at amplitude
of 40% and a frequency of 20ꢀkHz. Reagents and solvents were handled using standard
syringe techniques. The diorganoyl diselenides were prepared according previous
described procedures.[29] Spectroscopic grade solvents were used in the photophysical
characterization. UV-Vis absorption spectra were acquired on a Shimadzu UV-2450
spectrophotometer at a concentration of 10-5 M, and the steady-state fluorescence
spectra were measured on a Shimadzu spectrofluorometer model RF-5301PC. The
maximum absorption wavelength (WL) was used as the excitation WL for fluorescence
emission measurements. The relative quantum yield of fluorescence (fl) was
determined in the dilute optical method. Quinine sulphate in H2SO4 (fl =0.55) was used

as the quantum yield standard. All measurements were performed at room temperature
(25°C).
General procedure for preparation of pyridinium salts 3a-f
In a round-bottom flask under air atmosphere, 1 mmol of corresponding 2-
bromoacetophenone was dissolved in 3 mL of acetone followed by addition of 1 mmol
of pyridine derivative. The reaction was stirred for 4-8 hours at reflux temperature. The
precipitate was filtrated and washed with cold ethyl acetate (25 mL) affording the
desired pyridinium salt.
1-(2-oxo-2-phenylethyl)pyridinium bromide (3a)[30]
The title compound was prepared according to the general procedure using 2-
bromoacetophenone (200 mg) and pyridine (81 µL) yielding 96 % (285 mg) of the
1
desired product as white solid. H NMR (400 MHz, DMSO-d6) δ 9.05 (dd, J = 6.7, 1.3
Hz, 1H), 8.75 (tt, J = 7.9, 1.3 Hz, 1H), 8.29 (dd, J = 7.8, 1.3 Hz, 1H), 8.11 – 8.05 (m,
13
1H), 7.83 – 7.78 (m, 1H), 7.70 – 7.65 (m, 1H), 6.55 (s, 1H). C NMR (100 MHz,
DMSO-d6) δ 191.2, 146.8, 146.7, 135.2, 134.0, 129.6, 128.7, 128.3, 66.7.
4-(dimethylamino)-1-(2-oxo-2-phenylethyl)pyridinium bromide (3b) [30]
The title compound was prepared according to the general procedure using 2-
bromoacetophenone (200 mg) and 4-dimethylaminopyridine (122 mg) yielding 85 %
1
(204 mg) of the desired product as white solid. H NMR (400 MHz, DMSO-d6) δ 8.23
(d, J = 7.8 Hz, 2H), 8.08 – 8.01 (m, 2H), 7.77 (t, J = 7.4 Hz, 1H), 7.64 (t, J = 7.8 Hz,
2H), 7.14 (d, J = 7.8 Hz, 2H), 6.04 (s, 2H), 3.24 (s, 6H). 13C NMR (101 MHz, DMSO-
d6) δ 192.8, 156.5, 143.7, 134.9, 134.3, 129.5, 128.5, 107.8, 62.8.
4-(cyano)-1-(2-oxo-2-phenylethyl)pyridinium bromide (3c) [31]
The title compound was prepared according to the general procedure using 2-
bromoacetophenone (200 mg) and 4-pyridinecarbonitrile (104 mg) yielding 75 % (226
mg) of the desired product as white solid. 1H NMR (400 MHz, DMSO-d6) δ 9.28 (d, J =
6.6 Hz, 2H), 8.80 (d, J = 6.5 Hz, 2H), 8.08 (d, J = 7.8 Hz, 2H), 7.81 (t, J = 7.4 Hz, 1H),
13
7.67 (t, J = 7.7 Hz, 2H), 6.58 (s, 2H). C NMR (101 MHz, DMSO-d6) δ 190.3, 148.1,
135.4, 133.8, 131.2, 129.7, 128.8, 128.4, 115.3, 67.6.

1-(2-oxo-2-phenylethyl)quinolinium bromide (3d) [30]
The title compound was prepared according to the general procedure using 2-
bromoacetophenone (200 mg) and quinoline (129 mg) yield 52 % (128 mg) of the
desired product as white solid. 1H NMR (400 MHz, DMSO-d6) δ: 9.55 – 9.48 (m, 1H),
9.45 (d, J = 8.3 Hz, 1H), 8.56 (dd, J = 8.2, 1.2 Hz, 1H), 8.46 (d, J = 8.9 Hz, 1H), 8.33
(dd, J = 8.4, 5.8 Hz, 1H), 8.23 (dt, J = 8.8, 1.2 Hz, 1H), 8.16 (dd, J = 8.3, 1.1 Hz, 2H),
8.10 – 8.04 (m, 1H), 7.87 – 7.80 (m, 1H), 7.74 – 7.66 (m, 2H), 7.01 (s, 2H).13C NMR
(100 MHz, DMSO-d6) δ: 191.2, 151.5, 149.1, 139.1, 136.4, 135.3, 134.1, 131.1, 130.5,
129.9, 129.6, 129.1, 122.7, 119.7, 63.7.
1-(2-(4-nitrophenyl)-2-oxoethyl)pyridinium bromide (3e) [32]
The title compound was prepared according to the general procedure using 2-bromo-4′-
nitroacetophenone (244 mg) and pyridine (81 µL) yielding 85 % (206 mg) of the
desired product as white solid. 1H NMR (400 MHz, DMSO-d6) δ 9.02 (d, J = 6.7, 2H),
8.77 (tt, J = 7.9, 1.3 Hz, 1H), 8.53 – 8.45 (m, 2H), 8.31 (m, 4H), 6.57 (s, 1H). 13C NMR
(101 MHz, DMSO-d6) δ 190.5, 151.1, 147.1, 146.8, 138.7, 130.2, 128.4, 124.7, 66.9.
1-(2-(4-methoxy)-2-oxoethyl)pyridinium bromide (3f) [32]
The title compound was prepared according to the general procedure using 2-bromo-4′-
methoxyacetophenone (229 mg) and pyridine (81 µL) yielding 61 % (139 mg) of the
1
desired product as white solid. HNMR (400 MHz, DMSO-d6) δ: 9.00 (d, J = 6.4 Hz,
2H), 8.74 (t, J = 7.8 Hz, 1H), 8.28 (t, J = 7.0 Hz, 2H), 8.05 (d, J = 9.4 Hz, 2H), 7.27 –
13
7.14 (m, 2H), 6.44 (s, 2H), 3.91 (s, 3H). C NMR (100 MHz, DMSO-d6) δ: 189.4,
164.8, 146.8, 131.2, 128.3, 126. 8, 114.9, 66.4, 56.3.
General procedure for preparation of chalcogenyl alkynes 6a-l
Method 1: To a round-bottom flask was added as follow: dimethylsulfoxide (1.0 mL),
terminal alkyne (0.25 mmol), diorganyl dichalcogenide (0.125 mmol) and CuI (4 mol%,
1.9 mg).The reaction was stirred at room temperature for 18 hours. The reaction mixture
was diluted with water, extracted with AcOEt (3x25 mL), dried and purified by column
chromatography using hexane or a mixture of hexane/ethyl acetate (Hex:AcOEt, 99:1),
as the eluent, to afford the desired products.

Method 2: To a round-bottom flask was added as follow: dichloromethane (1.5 mL),
terminal alkyne (1.0 mmol), diorganyl dichalcogenide (0.5 mmol) and AgNO3 (10 mol
%, 17 mg). The mixture was stirred at 25 °C until complete consumption of terminal
alkyne (by TLC). After that, the solvent was evaporated and the crude product was
purified by column chromatography on silica gel using hexane or a mixture of
hexane/ethyl acetate (Hex:AcOEt, 99:1) as the eluent to afford the desired products.
methyl 3-(phenylselanyl)propiolate (6a)
The title compound was prepared according to the method 1, using methyl propiolate
1
(23 µL) and diphenyl diselenide (39 mg). Yield: 90 % (25 mg) as yellow oil. H NMR
(400 MHz, CDCl3) δ: 7.56 – 7.51 (m, 2H), 7.37 – 7.28 (m, 3H), 3.77 (s, 3H). 13C NMR
(100 MHz, CDCl3) δ: 152.8,130.0, 129.8, 128.1, 125.9, 95.9, 75.3, 52.5. HRMS (ESI)
calcd for C10H8NaO2Se (M+Na)+ requires 262.9587, found 262.9582.
ethyl 3-(phenylselanyl)propiolate (6b)
The title compound was prepared according to the method 2, using ethyl propiolate (101
µL) and diphenyl diselenide (156 mg). Yield: 88 % (104 mg) as yellow oil. 1HNMR
(400 MHz, CDCl3) δ: 7.59 – 7.53 (m, 2H), 7.41 – 7.29 (m, 3H), 4.26 (q, J = 7.1 Hz,
13
2H), 1.32 (t, J = 7.1 Hz, 3H). C NMR (100 MHz, CDCl3) δ: 152.63, 130.19, 129.90,
128.21, 126.04, 96.32, 74.80, 62.00, 14.09. HRMS (ESI) calcd for C11H10NaO2Se
(M+H)+ requires 276.9744, found 276.9741.
methyl 3-((4-chlorophenyl)selanyl)propiolate (6c)
The title compound was prepared according to the method 1, using methyl propiolate
(23 µL) and 1,2-bis(4-chlorophenyl)diselenide (60 mg). Yield: 85 % (27 mg) as dark
1
orange oil. HNMR (400 MHz, CDCl3) δ: 7.45 – 7.42 (m, 1H), 7.29 – 7.26 (m, 1H),
13
3.76 (s, 2H). C NMR (100 MHz, CDCl3) δ: 152.8, 134.6, 131.5, 130.0, 124.1, 96.3,
74.6, 52.7. HRMS (ESI) calcd for C10H8ClO2Se (M+H)+ requires 274.9376, found
274.9377.
ethyl 3-((4-chlorophenyl)selanyl)propiolate (6d)
The title compound was prepared according to the method 1, using ethyl propiolate (25
µL) and 1,2-bis(4-chlorophenyl)diselenide (60 mg). Yield: 78 % (26 mg) as yellow oil.
1HNMR (400 MHz, CDCl3) δ: 7.52 – 7.47 (m, 2H), 7.37 – 7.31 (m, 2H), 4.27 (q, J = 7.1

13
Hz, 2H), 1.33 (t, J = 7.1 Hz, 3H). C NMR (100 MHz, CDCl3) δ: 152.4, 134.5, 131.5,
130.0, 124.1, 96.5, 73.9, 62.0, 14.0. HRMS (ESI) calcd for C11H9ClNaO2Se (M+H)+
requires 310.9352, found 310.9354.
ethyl 3-(p-tolylselanyl)propiolate (6e)
The title compound was prepared according to the method 2, using ethyl propiolate (101
µL) and 1,2-di-p-tolyldiselenide (170 mg). Yield: 85 % (107 mg) as yellow oil. 1HNMR
(400 MHz, CDCl3) δ: 7.51 – 7.36 (m, 2H), 7.21 – 7.10 (m, 2H), 4.31 – 4.16 (m, 2H),
2.34 (s, 3H), 1.38 – 1.25 (m, 3H). 13C NMR (100 MHz, CDCl3) δ: 152.7, 138.5, 130.7,
122.1, 95.7, 75.5, 61.9, 21.1, 14.1. HRMS (ESI) calcd for C12H12NaO2Se (M+H)+
requires 290.9901, found 326.9902.
ethyl 3-((3-(trifluoromethyl)phenyl)selanyl)propiolate (6f)
The title compound was prepared according to the method 1, using ethyl propiolate (25
µL) and 1,2-bis(3-(trifluoromethyl)phenyl)diselenide (56 mg). Yield: 60 % (22 mg) as
yellow oil. 1HNMR (400 MHz, CDCl3) δ: 7.82 – 7.74 (m, 2H), 7.59 (d, J = 7.8 Hz, 1H),
13
7.50 (t, J = 7.8 Hz, 1H), 4.28 (q, J = 7.1 Hz, 2H), 1.34 (t, J = 7.3 Hz, 3H). C NMR
(100 MHz, CDCl3) δ: 152.5, 133.3, 132.2 (q, J = 32.9 Hz), 130.4, 126.6 (q, J = 3.9 Hz),
125.1 (q, J = 3.7 Hz), 123,5 (q, J= 272,8 Hz), 97.4, 73.0, 62.2, 14.1. HRMS (ESI) calcd
for C12H9F3NaO2Se (M+H)+ requires 344.9618, found 344.9617.
ethyl 3-((2-methoxyphenyl)selanyl)propiolate (6g)
The title compound was prepared according to the method 1, using ethyl propiolate (25
µL) and 1,2-bis(2-methoxyphenyl)diselenide (47 mg). Yield: 62 % (20 mg) as yellow
oil. 1HNMR (400 MHz, CDCl3) δ: 7.68 (dd, J = 7.8, 1.5 Hz, 1H), 7.27 (ddd, J = 8.3, 6.2,
1.5 Hz, 1H), 7.03 (td, J = 7.7, 0.9 Hz, 1H), 6.83 (d, J = 7.6 Hz, 1H), 4.28 (q, J = 7.1 Hz,
2H), 3.86 (s, 3H), 1.34 (t, J = 7.1 Hz, 3H). 13C NMR (100 MHz, CDCl3) δ: 155.6, 152.6,
128.7, 128.6, 122.4, 115.8, 110.4, 98., 74.1, 61.9, 55.9, 14.0. HRMS (ESI) calcd for
C12H12NaO3Se (M+H)+ requires 306.9850, found 306.9853.
methyl 3-(2-tolylselanyl)propiolate (6h)
The title compound was prepared according to the method 1, using methyl propiolate
(23 µL) and 1,2-di-o-tolyldiselenide (42 mg). Yield: 72 % (21 mg) as yellow oil.
1HNMR (400 MHz, CDCl3) δ: 7.76 – 7.72 (m, 1H), 7.30 – 7.20 (m, 3H), 3.82 (s, 3H),

13
2.40 (s, 3H). C NMR (100 MHz, CDCl3) δ: 153.1, 137.8, 130.9, 130.7, 128.6, 127.6,
126.8, 95.8, 75.2, 52.7, 21.4. HRMS (ESI) calcd for C11H10NaO2Se (M+Na)+ requires
276.9744, found 276.9739.
ethyl 3-(naphthalen-2-ylselanyl)propiolate (6i)
The title compound was prepared according to the method 2, using ethyl propiolate (101
µL) and 1,2-di(naphthalen-2-yl)diselenide (206 mg). Yield: 60 % (81 mg) as dark oil.
1HNMR (400 MHz, CDCl3) δ: 8.08 – 8.02 (m, 1H), 8.02 – 7.97 (m, 1H), 7.90 – 7.85 (m,
2H), 7.61 (ddd, J = 8.4, 6.9, 1.5 Hz, 1H), 7.56 (ddd, J = 8.1, 7.0, 1.3 Hz, 1H), 7.49 –
7.44 (m, 1H), 4.24 (q, J = 7.1 Hz, 2H), (t, J = 7.1 Hz, 3H). 13C NMR (100 MHz, CDCl3)
δ: 13C NMR (101 MHz, cdcl3) δ 152.7, 134.2, 132.5, 131.2, 129.7, 128.8, 127.3, 126.7,
126.3, 125.7, 124.5, 95.4, 74.7, 62.0, 14.1. HRMS (ESI) calcd for C15H12NaO2Se
(M+H)+ requires 326.9901, found 326.9901.
ethyl 3-(mesitylselanyl)propiolate (6j)
The title compound was prepared according to the method 1, using ethyl propiolate (25
µL) and 1,2-dimesityl diselenide (50 mg). Yield: 62 % (20 mg) Yield: 69 % (24 mg) as
yellow oil. 1HNMR (400 MHz, CDCl3) δ: 6.99 (s, 1H), 4.21 (q, J = 7.1 Hz, 2H), 2.57 (s,
6H), 2.31 (s, 3H), 1.30 (t, J = 7.1 Hz, 3H). 13C NMR (100 MHz, CDCl3) δ: 152.8, 142.4,
140.1, 129.3, 123.6, 91.1, 61.8, 24.2, 21.0, 14.1. HRMS (ESI) calcd for C14H16NaO2Se
(M+H)+ requires 319.0214, found 319.0211.
ethyl 3-(phenyltellanyl)propiolate (6k)
The title compound was prepared according to the method 1, using ethyl propiolate (25
1
µL) and 1,2-diphenyl ditelluride (52 mg). Yield: 65 % (23 mg) as brown oil. HNMR
(400 MHz, CDCl3) δ: 7.79 – 7.74 (m, 1H), 7.38 – 7.30 (m, 2H), 4.27 (q, J = 7.1 Hz,
13
1H), 1.33 (t, J = 7.1 Hz, 2H). C NMR (100 MHz, CDCl3) δ: 152.2, 139.2, 136.5,
130.1, 128.9, 110.9, 107.4, 62.1, 55.3, 29.7, 14.1. HRMS (ESI) calcd for C11H10NaO2Te
(M+Na)+ requires 326.9641, found 326.9638.
ethyl 3-(p-tolyltellanyl)propiolate (6l)
The title compound was prepared according to the method 1, using ethyl propiolate (25
1
µL) and 1,2-di-p-tolylditelluride (66 mg). Yield: 62 % (23 g) as brown oil. HNMR
(400 MHz, CDCl3) δ: 7.68 – 7.64 (m, 2H), 7.16 – 7.11 (m, 2H), 4.24 (q, J = 7.1 Hz,

2H), 2.38 (s, J = 7.7 Hz, 3H), 1.31 (t, J = 7.1 Hz, 3H). 13C NMR (100 MHz, CDCl3) δ:
152.3 , 139.3, 137.2, 130.1, 106.8, 62.0, 55.5, 29.7, 21.3, 14.1. HRMS (ESI) calcd for
C12H12NaO2Te (M+H)+ requires 340.9796, found 340.9798.
General procedure for preparation of chalcogenyl indolizines 7a-s
The pyridinium salt (0.5 mmol) and cesium carbonate (0.6 mmol, 195 mg) was
dissolved in 0.5 mL of DMF in a glass tube followed by addition of chalcogenyl alkyne
(0.25 mmol). An ultrasound probe was placed in the glass tube containing the reaction
mixture. The amplitude of the ultrasound waves was fixed at 40%. Then, the reaction
mixture was sonicated for 5 min. Crude was diluted with water, extracted with AcOEt
(3x25 mL), dried and purified by column chromatography (Hex:AcOEt, 95: 5).
methyl 3-benzoyl-2-(phenylselanyl)indolizine-1-carboxylate (7a)
The title compound was prepared according to the general procedure, using 1-(2-oxo-2-
phenylethyl)pyridinium bromide (139 mg) and methyl 3-(phenylselanyl)propiolate (59
1
mg). Yield: 93 % (101 mg) as yellow solid. M.p.: 153-155 °C. H NMR (400 MHz,
CDCl3) δ 9.12 (dt, J = 7.1, 1.1 Hz, 1H), 8.27 (dt, J = 9.1, 1.2 Hz, 1H), 7.56 – 7.52 (m,
2H), 7.48 (tt, J = 7.5, 1.2 Hz, 1H), 7.33 – 7.26 (m, 3H), 7.08 (tt, J = 7.4, 1.3 Hz, 1H),
7.03 – 6.98 (m, 2H), 6.95 – 6.91 (m, 2H), 6.88 (td, J = 7.0, 1.4 Hz, 1H), 3.80 (s, 3H).
13C NMR (101 MHz, CDCl3) δ 187.8, 164.4, 139.0, 138.9, 133.1, 132.4, 131.1, 129.4,
129.0, 128.2, 126.8, 126.6, 126.5, 126.4, 123.6, 119.0, 114.4, 107.4, 51.2. FTIR (KBr,
νmax/cm−1): 1675, 1606, 1498, 1447. HRMS (ESI) calcd for C23H17NNaO3Se (M+H)+
requires 458.0273, found 458.0274.
ethyl 3-benzoyl-2-(phenylselanyl)indolizine-1-carboxylate (7b)
The title compound was prepared according to the general procedure, using 1-(2-oxo-2-
phenylethyl)pyridinium bromide (139 mg) and ethyl 3-(phenylselanyl)propiolate (64
1
mg). Yield: 90 % (101 mg) as yellow solid. M.p.: 151-153 °C. HNMR (400 MHz,
CDCl3) δ: 9.12 (dt, J = 7.1, 1.1 Hz, 1H), 8.27 (dt, J = 9.1, 1.2 Hz, 1H), 7.56 – 7.52 (m,
3H), 7.33 – 7.26 (m, 3H), 7.08 (tt, J = 7.4, 1.3 Hz, 1H), 7.03 – 6.98 (m, 2H), 6.94 – 6.88
(m, 3H), 4.26 (q, J = 7.1 Hz, 2H), 1.22 (t, J = 7.2 Hz, 3H). 13C NMR (100 MHz, CDCl3)
δ: 118.0, 164.1, 139.0, 138.9, 132.4, 131.0, 129.5, 129.0, 128.2, 126.5, 126.4, 119.2,
114.4, 107.7, 60.3,14.4. FTIR (KBr, νmax/cm−1): 1678, 1608, 1495, 1447. HRMS (ESI)
calcd for C24H19NNaO3Se (M+Na)+ requires 472.0429, found 472.0420.

methyl 3-benzoyl-2-((4-chlorophenyl)selanyl)indolizine-1-carboxylate (7c)
The title compound was prepared according to the general procedure, using 1-(2-oxo-2-
phenylethyl)pyridinium
bromide
(139
mg)
and
methyl
3-((4-
chlorophenyl)selanyl)propiolate (68 mg). Yield: 75 % (88 mg) as yellow solid. M.p.:
1
146-148 °C. H NMR (400 MHz, CDCl3) δ 9.12 (d, J = 6.6 Hz, 1H), 8.28 (d, J = 8.2
Hz,1H), 7.60 – 7.55 (m, 2H), 7.51 (td, J = 2.2, 1.7 Hz, 1H), 7.38 – 7.29 (m, 3H), 7.02 –
6.96 (m, 2H), 6.93 (td, J = 6.9, 1.1 Hz, 1H), 6.89 – 6.83 (m, 2H), 3.85 (s, 3H). 13C NMR
(100 MHz, CDCl3) δ: 187.7, 164.3, 138.9, 132.7, 132.6,132.5,131.3, 129.4, 129.1,
77
128.3, 119.1, 114.5, 107.2, 51.2. Se NMR (76 MHz, CDCl3) δ 361.3. FTIR (KBr,
νmax/cm−1): 1700, 1593, 1495, 1437. HRMS (ESI) calcd for C25H21NNaO3Se (M+H)+
requires 486.0586, found 486.0589.
ethyl 3-benzoyl-2-(p-tolylselanyl)indolizine-1-carboxylate (7d)
The title compound was prepared according to the general procedure, using 1-(2-oxo-2-
phenylethyl)pyridinium bromide (139 mg) and ethyl 3-(p-tolylselanyl)propiolate (63
1
mg). Yield: 81 % (94 mg) as yellow solid. M.p.: 151-153 °C. H NMR (400 MHz,
CDCl3) δ 9.08 (d, J = 7.1 Hz, 1H), 8.28 (d, J = 9.0 Hz, 1H), 7.53 (d, J = 7.2 Hz, 2H),
7.48 (t, J = 7.4 Hz, 1H), 7.28 (m, 3H), 6.87 (t, 1H), 6.80 (s, 3H), 4.33 (q, J = 7.1 Hz,
2H), 2.24 (s, 3H), 1.36 (t, J = 7.1 Hz, 3H). 13C NMR (101 MHz, CDCl3) δ 187.9, 164.2,
138.9, 138.8, 136.5, 132.4, 131.4, 129.8, 129.5, 128.1, 127.2, 126.7, 126.2, 123.3,
119.1, 114.2, 107.6, 60.3, 29.7, 21.0, 14.5. FTIR (KBr, νmax/cm−1): 1701, 1587, 1530.
HRMS (ESI) calcd for C25H21NNaO3Se (M+Na)+ requires 486.0586, found 486.0589.
ethyl 3-benzoyl-2-((3-(trifluoromethyl)phenyl)selanyl)indolizine-1-carboxylate (7e)
The title compound was prepared according to the general procedure, using 1-(2-oxo-2-
phenylethyl)pyridinium
bromide
(139
mg)
and
ethyl
3-((3-
(trifluoromethyl)phenyl)selanyl)propiolate (76 mg). Yield: 59 % (76 mg) as yellow
1
solid. M.p.: 139-141 °C. HNMR (400 MHz, CDCl3) δ: 9.14 (d, J = 7.2 Hz, 1H), 8.34
(d, J = 9.1 Hz, 1H), 7.52 (dd, J = 7.2, 5.7 Hz, 3H), 7.40 – 7.29 (m, 5H), 7.20 (p, J = 7.9
Hz, 2H), 7.09 (s, 1H), 6.96 (td, J = 7.0, 1.1 Hz, 1H), 4.38 (q, J = 7.1 Hz, 2H), 1.39 (t, J
= 7.1 Hz, 3H). 13C NMR (100 MHz, CDCl3) δ: 187.7, 164.0, 138.8, 138.6, 138.4 (J=4.1
Hz), 132.7, 131.1 (J=32.4 Hz), 129.4, 129.3, 128.3, 127.3 (J=3.9 Hz), 126.9, 126.6,
125.7, 125.5 (J=272.8 Hz), 123.4 (J=3.7 Hz), 119.3, 114.6, 107.6, 60.5, 14.4. 77Se NMR

(76 MHz, CDCl3) δ 372.7. FTIR (KBr, νmax/cm−1): 1678, 1614, 1507, 1439. HRMS
(ESI) calcd for C25H18F3NNaO3Se (M+Na)+ requires 540.0303, found 540.0302.
ethyl 3-benzoyl-2-((2-methoxyphenyl)selanyl)indolizine-1-carboxylate (7f)
The title compound was prepared according to the general procedure using 1-(2-oxo-2-
phenylethyl)pyridinium
bromide
(139
mg)
and
ethyl
3-((2-
methoxyphenyl)selanyl)propiolate (68 mg). Yield: 58 % (69 mg) as yellow solid. M.p.:
1
149-151 °C. HNMR (400 MHz, CDCl3) δ: 9.11 (d, J = 7.1 Hz, 1H), 8.35 (d, J = 9.0
Hz, 1H), 7.57 – 7.52 (m, 2H), 7.46 (t, J = 7.4 Hz, 2H), 7.35 – 7.27 (m, 2H), 7.11 – 7.05
(m, 1H), 6.94 – 6.83 (m, 2H), 6.68– 6.59 (m, 2H), 4.32 – 4.24 (m, 2H), 3.58 (d, J = 1.4
13
Hz, 3H). C NMR (100 MHz, CDCl3) δ: 188.4, 164.2, 156.6, 139.3, 132.2, 131.2,
129.2, 128.1, 127.6, 126.8, 126.2, 124.6, 124.4, 122.9, 121.5, 119.3, 114.4, 110.2,
108.2, 60.3, 55.4, 29.7, 14.22. FTIR (KBr, νmax/cm−1): 1674, 1635, 1587, 1518, 1470.
HRMS (ESI) calcd for C25H21NNaO4Se (M+H)+ requires 502.0535, found 502.0533.
methyl 3-benzoyl-2-(o-tolylselanyl)indolizine-1-carboxylate (7g)
The title compound was prepared according to the general procedure using 1-(2-oxo-2-
phenylethyl)pyridinium bromide (139 mg) and methyl 3-(2-tolylselanyl)propiolate (63
1
mg). Yield: 54 % (60 mg) as yellow solid. M.p.: 143-145 °C. H NMR (400 MHz,
CDCl3) δ 9.07 (d, J = 7,1 Hz, 1H), 8.29 (d, J = 9.6 Hz, 1H), 7.48 (t, J = 9.6 Hz, 2H),
7.36 – 7.15 (m, 2H), 7.02 (t, J = 7.3 Hz, 1H), 6.87 (m 2H), 3.84 (s, 2H), 1.87 (s, 2H).
13C NMR (101 MHz, CDCl3) δ 188.1, 164.5, 139.1, 138.9, 138.4, 133.9, 132.5, 132.0,
129.9, 129.3, 128.1, 126.9, 126.8, 126.6, 126.4, 126.2, 123.8, 119.1, 114.4, 107.6, 51.2,
77
21.6. Se NMR (76 MHz, CDCl3) δ 320.0. FTIR (KBr, νmax/cm−1): 1678, 1614, 1507,
1439. HRMS (ESI) calcd for C24H19NaO3Se (M+Na)+ requires 472.0429, found
472.0423.
ethyl 3-benzoyl-2-(naphthalen-2-ylselanyl)indolizine-1-carboxylate (7h)
The title compound was prepared according to the general procedure, using 1-(2-oxo-2-
phenylethyl)pyridinium bromide (139 mg) and methyl ethyl 3-(naphthalen-2-
ylselanyl)propiolate (72 mg). Yield: 49 % (61 mg) as yellow solid. M.p.: 162-164 °C.
1H NMR (400 MHz, CDCl3) δ 8.95 (d, J = 7.1 Hz, 1H), 8.31 (d, J = 9.0 Hz, 1H), 7.69 (t,
2H), 7.64 (d, J = 8.1 Hz, 1H), 7.41 – 7.15 (m, 7H), 7.11 (t, 7.7 Hz, 1H), 7.02 (t, J = 7.7
Hz, 2H), 6.85 (td, J = 7.0, 1.1 Hz, 1H), 4.33 (q, J = 7.1 Hz, 2H), 1.32 (t, J = 7.1 Hz,

13
3H). C NMR (101 MHz, CDCl3) δ 187.8, 164.3, 138.7, 138.4, 133.7, 132.7, 132.5,
132.3, 131.1, 128.9, 128.2, 127.8, 127.8, 126.8, 126.6, 126.3, 126.2, 126.1, 126.0,
125.9, 123.3, 119.1, 114.2, 107.5, 60.4, 29.7, 14.4. FTIR (KBr, νmax/cm−1): 1695, 1608,
1500, 1442. HRMS (ESI) calcd for C28H22NO3Se (M+H)+ requires 500.0767, found
500.0766.
ethyl 3-benzoyl-7-(dimethylamino)-2-(phenylselanyl)indolizine-1-carboxylate (7i)
The title compound was prepared according to the general procedure, using 4-
(dimethylamino)-1-(2-oxo-2-phenylethyl)pyridinium bromide (160 mg) and ethyl 3-
(phenylselanyl)propiolate (64 mg). Yield: 37 % (45 mg) as yellow solid. M.p.: 140-142
°C. 1HNMR (400 MHz, CDCl3) δ: 9.24 (d, J = 7.9 Hz, 1H), 7.55 – 7.52 (m, 2H), 7.47 –
7.50 (m, 1H), 7.38 (d, J = 2.8 Hz, 1H), 7.33 – 7.27 (m, 2H), 7.09 – 7.00 (m, 3H), 6.98 –
6.92 (m, 2H), 6.59 (dd, J = 7.9, 2.9 Hz, 1H), 4.22 (q, J = 7.1 Hz, 2H), 1.28 (t, J = 7.1
13
Hz, 3H). C NMR (100 MHz, CDCl3) δ: 186.9, 164.7, 148.9, 142.7, 140.4, 135.9,
131.5, 130.6, 130.5, 129.6, 129.3, 128.6, 128.4, 128.0, 122.1, 104.2, 95.1, 59.8, 39.9,
21.0, 14.4. FTIR (KBr, νmax/cm−1): 1667, 1638, 1589, 1511, 1491, 1423. HRMS (ESI)
calcd for C26H25N2O3Se (M+H)+ requires 493.1032, found 493.1032.
ethyl 3-benzoyl-7-(dimethylamino)-2-(p-tolylselanyl)indolizine-1-carboxylate (7j)
The title compound was prepared according to the general procedure, using 4-
(dimethylamino)-1-(2-oxo-2-phenylethyl)pyridinium bromide (160 mg) and ethyl 3-(p-
tolylselanyl)propiolate (63 mg). Yield: 35 % (43 mg) as yellow solid. M.p.: 125-127 °C.
1HNMR (400 MHz, CDCl3) δ: 9.22 (d, J = 8.0 Hz, 1H), 7.57 – 7.51 (m, 2H), 7.51 –
7.43 (m, 1H), 7.36 (d, J = 2.8 Hz, 1H), 7.34 – 7.29 (m, 2H), 6.87 – 6.81 (m, 4H), 6.57
(dd, J = 7.9, 2.9 Hz, 1H), 4.24 (q, J = 7.1 Hz, 2H), 3.16 (d, J = 12.0 Hz, 6H), 2.25 (s,
3H), 1.30 (dt, J = 6.9, 5.0 Hz, 4H). 13C NMR (100 MHz, CDCl3) δ: 186.9, 164.7, 148.8,
142.6, 140.3, 135.9, 131.5, 130.5, 129.6, 129.2, 128.6, 128.3, 127.9, 122.1, 104.1, 95.0,
59.8, 39.9, 21.0, 14.4. FTIR (KBr, νmax/cm−1): 1667,1638, 1590, 1515, 1489, 1417.
HRMS (ESI) calcd for C27H27N2O3Se (M+H)+ requires 507.1189, found 507.1189.
ethyl 3-benzoyl-2-((4-chlorophenyl)selanyl)-7-(dimethylamino)indolizine-1-
carboxylate (7k)
The title compound was prepared according to the general procedure, using 4-
(dimethylamino)-1-(2-oxo-2-phenylethyl)pyridinium bromide (160 mg) and ethyl 3-((4-

chlorophenyl)selanyl)propiolate (71 mg). Yield: 34 % (44 mg) as yellow solid. M.p.:
1
133-135 °C. HNMR (400 MHz, CDCl3) δ: 9.19 (dd, J = 7.9, 0.4 Hz, 1H), 7.56 – 7.50
(m, 2H), 7.49 – 7.42 (m, 1H), 7.34 (d, J = 2.8 Hz, 1H), 7.32 – 7.27 (m, 2H), 7.00 – 6.95
(m, 2H), 6.87 – 6.83 (m, 2H), 6.57 (dd, J = 7.9, 2.9 Hz, 1H), 4.23 (q, J = 7.1 Hz, 2H),
13
1.29 (t, J = 7.1 Hz, 3H). C NMR (100 MHz, CDCl3) δ: 186.8, 164.5, 149.9, 142.6,
140.3, 132.6, 132.0, 131.7, 131.6, 129.3, 128.9, 128.4, 128.1, 127.1, 122.2, 104.4,
104.1, 95.1, 59.8, 58.5, 39.9, 18.4, 14.4. FTIR (KBr, νmax/cm−1): 1724, 1371. HRMS
(ESI) calcd for C26H23ClN2NaO3Se (M+Na)+ requires 549.0460 found 549.0457.
ethyl 3-benzoyl-7-cyano-2-(phenylselanyl)indolizine-1-carboxylate (7l)
The title compound was prepared according to the general procedure, using 4-(cyano)-
1-(2-oxo-2-phenylethyl)pyridinium
bromide
(151
mg)
and
ethyl
3-
(phenylselanyl)propiolate (64 mg). Yield: 76 % (90 mg) as yellow solid. M.p.: 132-134
1
°C. H NMR (400 MHz, CDCl3) δ: 8.94 (d, J = 7.4 Hz, 1H), 8.68 (s, 1H), 7.60 – 7.46
(m, 3H), 7.33 (t, J = 7.7 Hz, 2H), 7.14 (t, J = 7.4 Hz, 1H), 7.02 (t, J = 7.6 Hz, 2H), 6.96
(dd, J = 7.4, 1.7 Hz, 1H), 6.90 (d, J = 7.6 Hz, 2H), 4.42 (q, J = 7.1 Hz, 2H), 1.42 (t, J =
13
7.1 Hz, 3H). C NMR (100 MHz, CDCl3) δ: 187.8, 163.3, 137.5, 135.6, 133.3, 132.0,
131.7, 129.5, 129.3, 128.4, 128.2, 127.2, 126.7, 125.3, 124.9, 117.5, 113.7, 110.4,
77
108.1, 61.1, 14.5. Se NMR (76 MHz, CDCl3) δ 372.8. FTIR (KBr, νmax/cm−1): 2222,
1684,1632, 1515, 1427. HRMS (ESI) calcd for C25H18N2NaO3Se (M+Na)+ requires
497.0382, found 497.0382.
ethyl 3-benzoyl-7-cyano-2-(p-tolylselanyl)indolizine-1-carboxylate (7m)
The title compound was prepared according to the general procedure, using 4-(cyano)-
1-(2-oxo-2-phenylethyl)pyridinium
bromide
(151
mg)
and
ethyl
3-(p-
tolylselanyl)propiolate (63 mg). Yield: 90 % (109 mg) as yellow solid. M.p.: 135-137
1
°C. H NMR (400 MHz, CDCl3) δ 8.89 (d, J = 7.4 Hz, 1H), 8.66 (s, 1H), 7.59 – 7.49
(m, 3H), 7.34 (t, J = 7.8 Hz, 2H), 6.93 (dd, J = 7.4, 1.8 Hz, 1H), 6.80 (q, J = 8.2 Hz,
13
4H), 4.43 (q, J = 7.1 Hz, 2H), 2.28 (s, 3H), 1.44 (t, J = 7.1 Hz, 3H). C NMR (100
MHz, CDCl3) δ: 188.0, 165.0, 138.8, 137.9, 137.4, 132.4, 130.1, 129.8, 128.1, 126.4,
125.9, 124.5, 118.8, 114.6, 113.7, 113.4, 60.6, 21.2, 14.6. FTIR (KBr, νmax/cm−1): 2236,

1695, 1608, 1510, 1422. HRMS (ESI) calcd for C25H17ClN2NaO3Se (M+H)+ requires
530.9990, found 530.9990.
ethyl 3-benzoyl-2-((4-chlorophenyl)selanyl)-7-cyanoindolizine-1-carboxylate (7n)
The title compound was prepared according to the general procedure, using 4-(cyano)-
1-(2-oxo-2-phenylethyl)pyridinium bromide (151 mg) and ethyl 3-((4-
chlorophenyl)selanyl)propiolate (71 mg). Yield: 73 % (93 mg) as yellow solid. M.p.:
1
150-152 °C. HNMR (400 MHz, CDCl3) δ: 8.92 (d, J = 7.4 Hz, 1H), 8.67 (d, J = 0.8
Hz, 1H), 7.60 – 7.51 (m, 3H), 7.42 – 7.31 (m, 2H), 7.03 – 6.91 (m, 3H), 6.88 – 6.78 (m,
13
2H), 4.45 (p, J = 7.1 Hz, 2H), 1.52 – 1.39 (m, 3H). C NMR (100 MHz, CDCl3) δ:
187.5, 163.2, 137.4, 135.5, 133.5, 133.4, 133.1, 131.7, 130.0, 129.5, 129.4, 129.3,
128.8, 128.6, 128.4, 127.7, 126.7, 125.2, 124.7, 117.4, 113.7, 110.2, 108.3, 61.1, 29.7,
14.5. FTIR (KBr, νmax/cm−1): 2230, 1638, 1625, 1508, 1469. HRMS (ESI) calcd for
C26H21N2O3Se (M+H)+ requires 489.0719, found 489.0720.
ethyl 3-benzoyl-2-(phenylselanyl)pyrrolo[1,2-b]quinoline-1-carboxylate (7o)
The title compound was prepared according to the general procedure, using 1-(2-oxo-2-
phenylethyl)quinolinium bromide (163 mg) and ethyl 3-(phenylselanyl)propiolate (71
1
mg). Yield: 22 % (27 mg) as yellow solid. M.p.: 167-169 °C. H NMR (400 MHz,
CDCl3) δ 8.32 (d, J = 9.5 Hz, 1H), 7.85 (d, J = 7.1 Hz, 2H), 7.75 (dd, J = 7.6, 1.6 Hz,
1H), 7.59 – 7.47 (m, 3H), 7.40 – 7.30 (m, 4H), 7.16 – 7.12 (m, 2H), 7.11 – 7.05 (m,
13
3H), 4.26 (q, J = 7.1 Hz, 2H), 1.22 (t, J = 7.2 Hz, 3H). C NMR (101 MHz, CDCl3) δ
191.0, 164.0, 138.1, 137.4, 134.0, 133.2, 132.2, 130.6, 130.2, 130.0, 129.1 ,128.8,
126.2, 125.2, 124.9, 118.2, 118.1, 115.6, 109.7, 60.2, 14.2. FTIR (KBr, νmax/cm−1):
1684, 1645, 1587, 1538, 1479. HRMS (ESI) calcd for C28H21NNaO3Se (M+H)+ requires
522.0587, found 522.0582.
methyl 3-(4-nitrobenzoyl)-2-(phenylselanyl)indolizine-1-carboxylate (7p)
The title compound was prepared according to the general procedure, using 1-(2-(4-
nitrophenyl)-2-oxoethyl)pyridinium
bromide
(80
mg)
and
ethyl
3-
(phenylselanyl)propiolate (71 mg). Yield: 52 % (62 mg) Yield: 52 % as yellow solid.
1
M.p.: 147-149 °C. H NMR (400 MHz, CDCl3) δ 9.34 (dd, J = 7.1, 1.0 Hz, 1H), 8.33
(dd, J = 9.0, 1.1 Hz, 1H), 8.11 – 8.06 (m, 2H), 7.62 – 7.57 (m, 2H), 7.42 (ddd, J = 9.0,
6.9, 1.0 Hz, 1H), 7.17 – 7.11 (m, 1H), 7.06 – 7.00 (m, 3H), 6.89 – 6.85 (m, 2H), 3.88 (s,

13
3H). C NMR (101 MHz, CDCl3) δ 185.5, 164.2, 149.5, 143.8, 139.3, 133.2, 130.6,
130.0, 129.4, 127.9, 127.6, 127.3, 126.9, 123.1, 119.2, 115.2, 108.7, 51.4. FTIR (KBr,
νmax/cm−1): 1690, 1587, 1490, 1431. HRMS (ESI) calcd for C23H17N2O5Se (M+H)+
requires 481.0304, found 481.0314.
methyl 3-(4-methoxybenzoyl)-2-(phenylselanyl)indolizine-1-carboxylate (7q)
The title compound was prepared according to the general procedure, using 1-(2-(4-
methoxy)-2-oxoethyl)pyridinium
bromide
(154
mg)
and
ethyl
3-
(phenylselanyl)propiolate (71 mg). Yield: 72 % (86 mg) as yellow solid. M.p.: 143-145
1
°C. HNMR (400 MHz, CDCl3) δ: 8.99 (d, J = 7.1 Hz, 1H), 8.29 (d, J = 9.0 Hz, 1H),
7.57 (d, J = 8.8 Hz, 2H), 7.34 – 7.25 (m, 2H), 7.12 (t, J = 7.1 Hz, 1H), 7.02 (dt, J = 8.4,
4.5 Hz, 4H), 6.89 (td, J = 7.0, 1.2 Hz, 1H), 6.83 (d, J = 8.8 Hz, 2H), 3.90 (s, 3H), 3.85
(s, 3H). 13C NMR (100 MHz, CDCl3) δ: 186.7, 164.6, 163.5, 138.7, 133.0, 131.9, 131.8,
131.3, 129.0, 126.7, 126.0, 126.0, 125.6, 123.8, 119.1, 114.1, 113.5, 106.8, 55.5, 51.2,
77
29.7. Se NMR (76 MHz, CDCl3) δ 359.5. FTIR (KBr, νmax/cm−1): 1691, 1593, 1495,
1446. HRMS (ESI) calcd for C24H19NNaO4Se (M+Na)+ requires 488.0378, found
488.0375.
ethyl 3-benzoyl-2-(mesitylselanyl)indolizine-1-carboxylate (7r)
The title compound was prepared according to the general procedure, using 1-(2-oxo-2-
phenylethyl)pyridinium bromide (139 mg) and ethyl 3-(mesitylselanyl)propiolate (73
1
mg). Yield: 45 % (55 mg) as yellow solid. M.p.: 152-154 °C. HNMR (400 MHz,
CDCl3) δ: 8.70 – 8.63 (m, 1H), 8.22 (dt, J = 9.1, 1.1 Hz, 1H), 7.55 – 7.43 (m, 3H), 7.34
(dd, J = 11.0, 4.4 Hz, 2H), 7.30 – 7.20 (m, 1H), 6.79 (td, J = 6.9, 1.3 Hz, 1H), 6.62 (s,
2H), 4.44 (q, J = 7.1 Hz, 2H), 2.21 (d, J = 12.7 Hz, 3H), 1.84 (s, 6H), 1.47 (t, J = 7.1
Hz, 3H). 13C NMR (100 MHz, CDCl3) δ: 13C NMR (101 MHz, CDCl3) δ 187.7, 164.5,
141.7, 138.4, 138.1, 137.8, 132.8, 129.4, 129.3, 128.7, 128.2, 128.0, 125.8, 125.6,
122.5, 118.8, 113.6, 106.1, 60.3, 23.1, 20.8, 14.6. FTIR (KBr, νmax/cm−1): 1673, 1614,
1497, 1439. HRMS (ESI) calcd for C27H25NNaO3Se (M+Na)+ requires 514.0899, found
514.0890.
ethyl 3-benzoyl-2-(phenyltellanyl)indolizine-1-carboxylate (7s)
The title compound was prepared according to the general procedure, using 1-(2-oxo-2-
phenylethyl)pyridinium bromide (139 mg) and ethyl 3-(phenyltellanyl)propiolate (75

1
mg).Yield: 61 % (76 mg) as yellow solid. M.p.: 135-137 °C. HNMR (400 MHz,
CDCl3) δ: 9.04 (d, J = 7.1 Hz, 1H), 8.25 (d, J = 9.0 Hz, 1H), 7.56 – 7.45 (m, 3H), 7.31 –
7.24 (m, 4H), 7.17 (dd, J = 16.0, 7.2 Hz, 3H), 6.99 (t, J = 7.6 Hz, 2H), 6.86 (td, J = 7.0,
1.3 Hz, 1H), 4.51 – 4.37 (m, 2H), 1.52 – 1.42 (m, 3H). 13C NMR (100 MHz, CDCl3) δ:
188.0, 165.0, 138.8, 137.9, 137.1, 132.4, 129.8, 129.2, 128.2, 127.3, 126.5, 126.0,
124.6, 118.8, 118.8, 113.8, 113.1, 109.6, 60.6, 14.6. FTIR (KBr, νmax/cm−1): 1650, 1611,
1494, 1426. HRMS (ESI) calcd for C24H19NNaO3Te (M+Na)+ requires 522.0327, found
522.0323.
ethyl 3-benzoyl-2-(p-tolyltellanyl)indolizine-1-carboxylate (7t)
The title compound was prepared according to the general procedure, using 1-(2-oxo-2-
phenylethyl)pyridinium bromide (139 mg) and ethyl 3-(p-tolyltellanyl)propiolate (78
1
mg).Yield: 56 % (71 mg) as yellow solid. M.p.: 141-143 °C. HNMR (400 MHz,
CDCl3) δ: 8.99 (dt, J = 7.1, 0.9 Hz, 1H), 8.24 (dt, J = 9.0, 1.1 Hz, 1H), 7.57 – 7.43 (m,
3H), 7.33 – 7.22 (m, 3H), 7.04 (d, J = 8.0 Hz, 2H), 6.83 (ddd, J = 12.5, 9.0, 4.5 Hz, 3H),
13
4.44 (q, J = 7.1 Hz, 2H), 2.32 (s, 3H), 1.48 (t, J = 7.1 Hz, 3H). C NMR (100 MHz,
CDCl3) δ: δ 188.0, 165.0, 138.8, 137.9, 137.4, 137.3, 132.4, 130.1, 129.8, 128.1, 126.4,
125.9, 124.5, 118.8, 114.6, 113.7, 113.4, 109.5, 60.6, 21.2, 14.6. FTIR (KBr, νmax/cm−1):
1667, 1608, 1501, 1433. HRMS (ESI) calcd for C25H21NNaO3Te (M+H)+ requires
536.0483, found 536.0483.
Results and Discussion
The synthetical approach selected for chalcogeno-indolizine preparation was
based on a stepwise 1,3-dipolar cycloaddition between pyridinium ylides and alkynes.
Since the electronic nature of the reagents, mainly the dipolarophile, has a strong effect
on reaction effectiveness, the choice of electronically poor chalcogeno-alkynes was
realized rather than selanylylide reagents. Thus, the initial optimization experiments
were carried out with 1-(2-oxo-2-phenylethyl)pyridin-1-ium bromide (3) and methyl 3-
(phenylselanyl)propiolate (6) as model substrates. Briefly, the pyridinium salt 3 was
prepared from quaternization of pyridine with 2-bromoacetophenone in acetone, and
selenoalkynes was obtained from copper(I)[33] or silver(I)[34] catalyzed coupling between
methyl or ethyl propiolate and diorganyl diselenides (Scheme 2).

O
H
Br
Se
+
+
Se
CO2Et
N
5
( )
1
( )
2
( )
4
( )
Se
N
+
CO2Et
Br
6
( )
O
Cs2CO3,
DMF
3
( )
EtO
O
Se
N
O
7
( )
Scheme 2. Synthetic route for preparation of chalcogeno-indolizines.
Initially, our study was based on determining the best conditions to obtain the
desired product 2-(phenylselanyl)indolizine (7a) via a stepwise 1,3-dipolar
cycloaddition (Table 1). The first cyclization attempt was based on previous work
employing a stoichiometric ratio of 2:1 between pyridinium salt and alkyne,[35] using
cesium carbonate as base, in DMF at 70 ºC. The reaction was carried out in two steps in
air atmosphere where, first, the pyridinium salt reacted with the base for 15 min,
followed by addition of chalcogeno-alkyne. The initial thermal conditions allowed the
desired product to form in 65% yield (Table 1, entry 1). With this promising result in
the initial test, and even though 2-halosubstituted pyridinium salts could also be
employed for this reaction, the substrate 3 was chosen for the reaction optimization, as
it presents an easy preparation allied to suitable reactivity.
Table 1. Reaction optimization of ylide-alkyne cycloaddition.
MeO
O
Se
Reaction
N
Se
+
Conditions
N
CO2Me
Br
O
O
6a
)
3a
(
(
)
7a
(
)
#
3a(eq.) 6a (eq.)
Base
T (°C)
Solvent
Time (h)
Yield (%)

1a
2a
3a
4a
5b
6
2
1
2
2
2
2
2
2
2
2
1
1
1
1
1
1
1
1
1
1
Cs2CO3
Cs2CO3
Cs2CO3
K2CO3
KOtBu
-
70
70
110
70
70
70
70
70
70
70
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMSO
MeOH
DMF
1
1
65
43
56
58
52
-
1
1
1
1
7b
8b
9b
10b
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
1
97
75
68
60
1
1
0.5
a 1.2 eq. of base b 2.4 eq. of base.
In order to evaluate the stoichiometry, the amount of the substrate 3a was
reduced to 1 equivalent, and a decreased yield was observed, proving that an excess of
ylide must be used. A temperature increase to 100 ºC or base change to K2CO3 and
KOtBu negatively affected the reaction while no product formation was observed in
absence of base (Table 1, entries 4-6), demonstrating the crucial role of base in this
reaction. Therefore, an increase of base amount was tested, leading to product 7a in
97% yield (Table 1, entry 7). Lately, other solvents such as DMSO and MeOH were
evaluated as well as shorter reaction time, but both reduced the reaction yield of 7a
(Table 1, entries 8-10).
As ultrasound irradiation increases reaction rates, the reaction was also evaluated
under ultrasonic irradiation (Table 2), aiming mainly to reduce the reaction time and,
ideally, to perform the reaction in a single step. The reaction was performed under
previously optimized conditions using an ultrasonic probe (20 KHz). The sonic
amplitude and reaction time were evaluated, and similar results were achieved in 5 min
using 40% of sonic amplitude (93 % yield).
Table 2. Reaction optimization by ultrasound irradiation.

MeO2C
O
Cs2CO3
(2.4 eq.)
Se
N
Se
+
N
O
DMF,
US (20 KHZ)
CO2Me
Br
O
3a
7a
(
)
6a
(
)
(
)
#
1
2
3
4
5
3a (eq.)
6a (eq.) Amplitude (%)
Time (min)
Yield (%)
2
1
2
2
2
1
1
1
1
1
20
40
40
40
40
3
3
71
86
93
92
85
5
7
10
The successful and highly efficient ultrasound-assisted cycloaddition between
unsubstituted pyridinium ylides and alkynes led us to continue using this approach in
reaction scope evaluation. This approach also allows the simultaneous mixing of all
reagents, unlike thermal conditions in which the reaction is performed in two steps, and
highlights that the reaction does not require inert atmosphere or dry solvent. Thus, our
best reaction conditions to synthesize the desired product 2-(phenylselanyl)indolizine
(7a), was using 1-(2-oxo-2-phenylethyl)pyridin-1-ium bromide (3a) (2 equivalents), 3-
(phenylselanyl)propiolate (6a) (1 equivalent), Cs2CO3 (2.4 equivalents) and DMF as the
solvent under ultrasound irradiation (20 kHz) for 5 min.
The scope of the procedure was next investigated employing other derivatives of
pyridinium salts (3) and chalcogeno-alkynes (6), introducing substituents with electron-
donating and electron-withdrawing features, in different positions (ortho, meta and
para), to verify electronic and steric effects. Most of these chalcogeno-alkynes used in
this part of the study were not reported yet in the literature, and for that reason an
optimization of the already reported protocols was necessary, and a series of novel
derivatives (6c-6l) was obtained (Table 3).
Table 3. Novel chalcogeno-alkynes prepared to investigate the reaction scope.

R2
R2
R2
H
Y
Y
+
Y
CO2R1
CO2R1
6a-l
Alkyne
6a
Y
R1
R2
H
Method
Yield (%)
Se
Se
Se
Se
Se
Se
Se
Se
Se
Se
Te
Te
Me
Et
1
2
1
1
2
1
1
1
2
1
1
1
90
95
80
78
88
60
62
72
59
69
65
62
6b
6c
H
Me
Et
4-Cl
6d
6e
4-Cl
Et
4-CH3
3-CF3
2-OCH3
2-Me
Naphtyl
Mesityl
H
6f
Et
6g
Et
6h
6i
Me
Et
6j
Et
6k
6l
Et
Et
4-CH3
Method 1: DMSO (1.5 mL), alkyne (0.25 mmol), CuI (0.01 mmol), diorganyl
dichalcogenide (0.125 mmol). Method 2: CHCl2 (1.5 mL), alkyne (1 mmol), Ag2NO3
(10 mol %), diorganyl dichalcogenide (0.5 mmol).
The substrates were prepared from diorganyl dichalcogenides and alkyl
propiolates using copper iodide[25] (Method 1) or silver nitrate[27] (Method 2), Table 3
showing which method reached the higher yields (for detailed methodology, see
Supporting Information). Surprisingly, in some cases it was necessary to employ methyl
propiolates to achieve the desired chalcogeno-alkyne, as no product was obtained with
ethyl propiolate.
The generality of the synthesis of the presented chalcogeno-indolizines was
proved in terms of yield and regioselectivity, as in all examples only one regioisomer
was observed. As chalcogeno-alkynes derived from methyl or ethyl propiolate were
employed in the investigation, it was verified that substitution of methyl for ethyl
moiety did not significantly affect the reaction yield (Table 4, 7 and 7b). The
introduction of substituents on the aryl ring of the alkyne led to good to moderate

yields, in which substitution position seems to have a major influence in comparison
with electronic effects, as can be observed in 7f-7h and 7r derivatives.
The presence of electron-donating substituents on the pyridine ring of
pyridinium salts 3 decreased the yield of 7i-7k derivatives (22, 20 and 17% yield,
respectively); the same effect was observed for quinolinyl derivative 7o, while the
presence of electron-withdrawing substituents (7l-7n) did not show the same tendency.
The effect of electron-donating substituents will be addressed in the reaction mechanism
discussion. In order to improve the reaction yield, the time of the ultrasound-promoted
reaction for -N(CH3)2 substituted indolizines 7i-7k was set to 10 min, and even so, the
products were obtained in 31-37% yield.
Table 4. Substrate scope of ultrasound-promoted indolizine preparation.
R1
R3
R4
O
R1
Se
R2
CsCO3 (2.4 eq)
+
Se
Br
N
R4
N
DMF, US, 5 min
R3
R4 = CO2Me
CO2Et
R2
O
O
3a-e
6a-l
7a-t
MeO
Cl
CH3
EtO
MeO
EtO
O
O
O
O
Se
Se
Se
Se
N
N
N
N
O
O
O
O
7a (93 %)
7b (90 %)
7c (75 %)
7d (81 %)

EtO
EtO
MeO
EtO
O
O
O
O
CF3
Se
Se
Se
Se
N
O
N
O
N
O
N
O
OCH3
CH3
7e (59 %)
7f (58 %)
7g (54 %)
7h (49 %)
EtO
O
CH3
EtO
O
Cl
EtO
O
EtO
O
N
N
NC
N
Se
N
Se
N
Se
N
Se
N
O
O
O
O
7i (37 %)a
7j (31 %)a
7k (34 %)a
7l (76 %)
Cl
EtO
O
EtO
O
MeO
O
CH3
EtO
O
NC
NC
Se
N
Se
N
Se
N
Se
N
O
O
O
O
NO2
CH3
7m (90 %)
7n (73 %)
7o (22 %)
7p (52 %)
EtO
MeO
O
EtO
O
EtO
O
O
Te
Se
N
Se
N
Te
N
N
O
O
O
O
OCH3
7q (72 %)
7r (45 %)
7s (61 %)
7t (56 %)
a Reaction carried out for 10 min
The nitro- and methoxy- substituted products 7p and 7q, were obtained in good
yields, confirming the generality of our method. Furthermore, we highlight that the
employment of tellanyl-alkynes as substrates allowed the preparation of the first
examples of tellurium- containing indolizines in the literature (7s-7t) achieving the
derivatives in good yields.
Two additional experiments were realized to perform the synthesis of the
indolizine 7a from pyridine (1) and bromoacetophenone (2) in a one-pot approach and
by multicomponent reaction (Scheme 3).

Se
EtO
O
O
CO2Et
6
( )
Br
+
N
Se
N
O
DMF, US,
3 min
US, Cs2CO3,
DMF, 5 min
N
Br
1
( )
2
( )
3
( )
O
7a
(76 %)
EtO
O
US, Cs2CO3,
DMF, 5 min
O
Se
Br
Se
+
+
CO2Et
N
O
N
1
( )
2
( )
6
( )
7a
(40 %)
Scheme 3. Indolizine synthesis by one-pot two-steps or multicomponent approach
In the first case, the ylide was prepared in situ from pyridine and acetophenone
under ultrasound conditions, and then the selenyl-alkyne 6 was added to the reaction
medium, leading to indolizine 7a in 76 % yield. The multicomponent reaction between
pyridine, acetophenone derivative and selanyl-alkyne achieved 40% yield of the same
product. The efficiency of this multicomponent approach may be reduced due to
formation of some side-products, observed by TLC analysis.
In contrast, the results obtained in the one-pot methodology in comparison with
the multi-step synthesis shows that this approach comprises an attractive protocol for
the indolizine preparation, as on the one hand, a slight decrease in reaction yield is
observed (global yield of multi-step is 89%), but on the other hand, the purification of
the intermediates are excluded.
The general mechanism of the stepwise 1,3-dipolar cycloaddition presented for
compound 7a in Scheme 5 involves two main steps.[36] First, the deprotonated
pyridinium ylide attacks the selanyl-alkyne to generate an allenoate intermediate. This
step explains the observed regioselectivity of the reaction as attack on carbon 1 of the
selanyl-alkyne (Scheme 5) allows negative charge stabilization by the carboxymethyl
group. Probably, the lower charge stabilization by the selenium moiety makes the attack
regioselective to carbon 1. The next step of intramolecular cyclization from allenoate to
pyridinium ring provide the nitrogen bicycle (not isolated) that after aromatization
arrives at the indolizine core.

Br
O
Cs2CO3
N
O
N
+
Se
CO2Me
1
2
N
C
O
O
Se
OMe
MeO
O
Se
N
O
ppm
s, 3.80
H
H
NOE
H
O
H
O
ppm
[O]
8.26
dt,
ppm
7.28
m,
Se
N
H
NOE
O
H
ppm
tt, 7.48
Scheme 4. Proposed reaction mechanism for chalcogeno-indolizines.
To further understand the mechanism involved, two additional experiments were
performed; one under argon atmosphere, and another, in the standard optimized
conditions, in presence of radical scavenger TEMPO (Scheme 4).
Cs2CO3, DMF,
1 h, 70 °C, Ar
7a
(not observed)
Se
N
+
CO2Me
Br
Cs2CO3, DMF,
1 h, 70 °C
O
7a
(42 %)
6a
)
3a
(
(
)
TEMPO (3 eq.)
Scheme 5. Control experiments.
The absence of product 7a in the experiment under argon atmosphere led us to
believe that aromatization promoted by oxigen is a crucial step for product formation.
The initial steps comprise reversible processes in which irreversible aromatization led to
the product. Whit these informations, we can infer that the aromatization follows a
radical pathway.

The lower yields in the series of indolizine 7i-7k containing strong electron-
donating substituents is believed to be related to high electron density in the pyridine
ring, that would disfavor attack on that ring. The regioselectivity of the product was
confirmed by two-dimensional NMR (see supporting information).
Although the photophysical properties of indolizine derivatives have been
investigated,[37] any correlation relating the chalcogen effect until now was reported. In
this sense, this study presents a comparative photophysical study between indolizine
derivatives containing and not containing the selenium functionalization, in order to
verify the influence of chalcogen in the optical properties of the heterocycle as the
solvent effect. For this, compound 7u, presented in Fig. 2, was synthesized. The
relevant data obtained from this investigation are summarized in Figure 2 and Table 5.
Figure 2. UV-Vis (a and c) and fluorescence emission (b and d) spectra of compound 7a
and 7u in dichloromethane and acetonitrile (10-5 M).
Table 5. General photophysical data of indolizines 7a and 7u, where  is the molar
extinction coefficient (x104 M-1·cm-1), abs is the absorption maxima (nm), fe is the
calculated oscillator strength, ke0 is the calculated radiative rate constant (108 s-1), 0 is

the calculated pure radiative lifetime (ns), em is the emission maxima (nm), ST is the
Stokes shift (cm-1) and QY is the fluorescence quantum yield (%).
0
#
Solvent
fe
k0
QY
em ST

abs
e
CH2Cl2 2.62 364 0.25 1.92 0.52 526 162 0.31
CH3CN 2.62 360 0.42 3.26 0.31 534 174 0.38
CH2Cl2 1.08 375 0.14 1.01 0.99 538 163 0.18
CH3CN 1.08 373 0.15 1.06 0.95 542 169 0.19
7u
7a
Both compounds 7a and 7u present absorption in the UV region with maxima
(λabs) located around 373 and 363 nm, respectively. In addition, it can also be observed
that the solvent seems not to influence the maxima location, with an almost absent
solvatochromic effect.
From the UV-Vis spectra and applying the Strickler-Berg relations (see
Supporting Information), the oscillator strengths (fe) and the radiative rate constants
(k0 ), as well as the pure radiative lifetimes (0) were obtained.[38] The values for
e
oscillator fe (0.25-0.42 for 7u and 0.09-0.15 for 7a), the molar absorptivity coefficient 
values (104 M-1.cm-1) and the calculated radiative rate constant k0 (108 s-1) corroborates
e
with electronic dipole-allowed transitions, related to spin and symmetry allowed *
electronic transitions.[39] Additionally, the pure radiative lifetime (0) shows that
radiation absorption led to population of the same excited state independent of the
presence of chalcogen.
The fluorescence emission spectra of 7a and 7u are shown in Figure. 2. The
emission curves were obtained by exciting the compounds at the respective absorption
maxima wavelengths. A main fluorescence emission can be observed in both
compounds and solvents, with maxima located in the blue to green region.
Moreover, both compounds present a Stokes shift around 130-160 nm,
indicating a significative energy loss in the excited state. On the base of these
preliminary, results, the photophysical properties seem to be tailored by the indolizine
skeleton, where the chalcogen atom does not plays a significant role. The main
influence of the chalcogen in indolizine structure was observed in the fluorescence
quantum yield (fl). A significant fluorescence quenching was observed in the selenium

containing compound 7a, as expected, where the insertion of the chalcogen can
probably be related to triplet state population via intersystem crossing (ISC).[40]
Conclusion
In summary, the ultrasound-promoted methodology comprise an efficient way to
prepare chalcogen-indolizine starting from pyridinium ylides and alkynes. The products
are obtained in short reaction times, good yields, high regioselectivity and is extended to
a wide range of functionalization on all aromatic rings of the product. Furthermore, the
reaction can also be performed under thermal conditions with the same efficiency. The
alternative one-pot two-step procedure for synthesize of these compounds starting from
simple precursors enhances the feasibility of the reaction, highlighting that only a
common base is required, without the necessity of metal catalysts or other additives. For
this study, novel selanyl- and tellanyl-alkynes were synthesized, in which the latter
precursors led to the first derivatives of teluro-indolizine described. The photophysical
study of a selenium indolizine was investigated to determine the influence of chalcogen
in the properties of the compound. The presence of the chalcogen caused a decrease in
fluorescence quantum yield.
Acknowledgements
We are grateful to Coordenação de Aperfeiçoamento de Pessoal de Nível Superior -
Brasil (CAPES) - Finance Code 001, CNPq, INCT-CMN and FAPERGS for financial
and technical support.
References
[1]
https://doi.org/10.1039/C6OB00985A; (b) K. M. Elattar, I. Youssef, A. A. Fadda,
Synthetic Communications, 2016, 46, 719.
https://doi.org/10.1080/00397911.2016.1166252
(a) B. Sadowski, J. Klain, D. T. Gryko, Org. Biomol. Chem., 2016, 14, 7804.
[2] J. Gubin, M. Descamps, P. Chatelain, D. Nisato, (European Patent Application)
EP 235111, 1987.
[3]
K. M. Dawood, H. Abdel-Gawad, M. Ellithey, H. A. Mohamed, B. Hegazi,
Arch. Pharm. Chem. Life Sci. 2006, 339, 133. https://doi.org/10.1002/ardp.200500176
[4]
W. M. Bloch, S. M. Derwent-Smith, F. Issa, J. C. Morris, L. M.; Sumby, C. J.
Rendina, Tetrahedron 2011, 67, 9368. https://doi.org/10.1016/j.tet.2011.09.133

[5]
A. Hazra, S. Mondal, A. Maity, S. Naskar, P. Saha, R. Paira, K. B. Sahu, P.
Paira, S. Ghosh, C. Sinha, A. Samanta, S. Banerjee, N. B. Mondal, Eur. J. Med. Chem.
2011, 46, 2132. https://doi.org/10.1016/j.ejmech.2011.02.066
[6]
S. P. Gupta, A. N. Mathur, A. N. Nagappa, D. Kumar, S. Kumaran, Eur. J. Med.
Chem. 2003, 38, 867. https://doi.org/10.1016/j.ejmech.2003.08.001
[7]
T. Weide, L. Arve, H. Prinz, H. Waldmann, H. Kessler, Bioorg. Med. Chem.
Lett. 2006, 16, 59. https://doi.org/10.1016/j.bmcl.2005.09.051
[8] (a) R. Sarkar, T. Chaudhuri, A. Karmakarb, C. Mukhopadhyay, Org. Biomol.
Chem., 2015, 13, 11674. (b) Y. R. Song, C. W. Lim, T. W. Kim, Luminescence, 2015,
31, 364. https://doi.org/10.1039/C5OB01646K
[9]
(a) J. Wang, G. Zhang, Z. Liu, X. Gu,; Y. Yan, C. Zhang, Z. Xu, Y. S. Zhao, H.
Fu, D. Zhang, Tetrahedron, 2013, 69, 2687; https://doi.org/10.1016/j.tet.2013.02.041.
(b) J. Wan, C. J. Zheng, M. K. Fung, X. K. Liu, C. S. Lee, X. H. Zhang, J. Mater.
Chem. 2012, 22, 4502. https://doi.org10.1039/C2JM14904D.
[10] (a) Y. Ooyama, Y. Oda, Y. Hagiwara, H. Fukuoka, E. Miyazaki, T. Mizumo, J.
Ohshita, Tetrahedron, 2013, 69, 5818; https://doi.org/10.1016/j.tet.2013.05.047. (b) D.
Kumar, K. R. J. Thomas, Y.L. Chen, Y.C. Jou, J.-H. Jou, Tetrahedron 2013, 69, 2594.
https://doi.org/10.1016/j.tet.2013.01.046.
[11] (a) A. V. Moro, P. C. Ferreira, P. Migowski, F. S. Rodembusch, J. Dupont, D. S.
Lüdtke, Tetrahedron 2013, 69, 201; https://doi.org/10.1016/j.tet.2012.10.043. (b) F.
Delattre, P. Woisel, G. Surpateanu, F. Cazier, P. Blach, Tetrahedron 2005, 61, 3939.
https://doi.org/10.1016/j.tet.2005.02.063.
[12] (a) B. Liu, Z. Wang, N. Wu, M. Li, J. You, J. Lan, Chem. Eur. J. 2012, 18, 1599;
https://doi.org/10.1002/chem.201103329. (b) F. F. D. Oliveira, D. C. B. D. Santos, A.
A. M. Lapis, J. R. Correa, A. F. Gomes, F. C. Gozzo, P. F. Moreira, V. C. de Oliveira,
F. H. Quina, B. A. D. Neto, Bioorg. Med. Chem. Lett. 2010, 20, 6001.
https://doi.org/10.1016/j.bmcl.2010.08.073.
[13] (a) E. Kim, S. Lee, S. B. Park, Chem. Commun. 2011, 47, 7734;
https://doi.org/10.1039/C1CC12618K (b) M. S. Jeong, E. Kim, H. J. Kang, E. J. Choi,
A. R. Cho, S. J. Chung, S. B. Park, Chem. Commun., 2012, 48, 6553;
https://doi.org/10.1039/C2CC31377D (c) E. J. Choi, E. Kim, Y. Lee; A. Jo, S. B. Park,
Angew. Chem. Int. Ed. 2014, 53, 1346. https://doi.org/10.1002/anie.201308826
[14] G. G. Surpateanu, M. Becuwe, N. C. Lungu, P. I. Dron, S. Fourmentin, D.
Landy, G. J. Surpateanu, Photochem. Photobiol. A-Chem. 2007, 185, 312.
https://doi.org/10.1016/j.jphotochem.2006.06.037
[15] A. J. Huckaba, F. Giordano, L. E. McNamara, K. M. Dreux, N. I. Hammer, G. S.
Tschumper, S. M. Zakeeruddin, M. Grätzel, M. K. Nazeeruddin, J. H. Delcamp, Adv.
Energy Mater. 2015, 5, 1401629. https://doi.org/10.1002/aenm.201401629
[16] Y. Zhang, J. Garcia-Amorós, B. Captain, F. M. Raymo, J. Mater. Chem., 2016,
4, 2744. https://doi.org/10.1039/C5TC03331D