Visible-Light Promoted Stereoselective Arylselanyl Functionalization of Alkynes

Article abstract of DOI:10.1002/ejoc.201801303

Functionalization of double bonds with arylselenium groups found in the literature, commonly uses high temperatures in the presence of metal catalysts, reducing agents or other additives. In this context, this work presents a series of bis-arylselanyl ole

Full text of DOI:10.1002/ejoc.201801303

DOI: 10.1002/ejoc.201801303
Communication
Photochemistry
Visible-Light Promoted Stereoselective Arylselanyl
Functionalization of Alkynes
Andressa C. H. Weber,[a] Felipe L. Coelho,[a] Ricardo F. Affeldt,*[b] and Paulo H. Schneider*[a]
Abstract: Functionalization of double bonds with arylselenium diselenide comprises the UV/Visible region of spectra, a mixture
groups found in the literature, commonly uses high tempera- of arylacetylene and diaryl diselenide in dichloromethane was
tures in the presence of metal catalysts, reducing agents or irradiated with white light from compact (household) fluores-
other additives. In this context, this work presents a series of cent lamp. The optimized procedure allows preparation of
bis-arylselanyl olefins synthesized by photoinduced reaction E-olefins due to radical addition followed by photoisomeriza-
without heating or additives. Since the absorption range of the tion with low cost and low environmental impact.
Introduction
pared from terminal alkynes and selenols by hydrochalcogena-
tion. Following these approach, authors reported selenol gener-
ation in situ from reduction of diorganoyl diselenides and reac-
tion proceeded according to an anti-Markovnikov orientation
with major formation of the Z isomer.[9a] Interestingly, the pro-
tocol only affords monoselenylated products and total (Z) to (E)
isomerization was observed in few days.
Organochalcogenyl compounds have received increased atten-
tion in last decades mainly because of their unique reactivity
as synthetic intermediates and pharmacological properties. An
extraordinary number of novel protocols have been developed
for preparation of molecules bearing the phenylselenoether
group showing related biological activity.[1] In this context, 1,2-
bis-organylselanyl alkenes emerges as an important class being
used as versatile precursor to enediynes and other functional-
ized olefins.[2] Furthermore, recent studies revealed antinocicep-
tive and antioxidant activities for these compounds.[3]
Classical protocols for 1,2-bis-organylselanyl alkene synthesis
involve reaction between alkynes and diorganoyl diselenides.
In Scheme 1 is depicted most representative methodologies for
this purpose. The stereoselective synthesis of (E)-1,2-bis-aryl-
selanyl alkenes includes (i) use of deep eutethic solvents to
carry the reaction in the presence of sodium borohydride,[4]
(ii) CuI/Zn/glycerol as a recyclable catalytic system[5] and (iii)
microwave reaction using KF/Al2O3 or NaBH4 in PEG-400 yield-
ing also the 1-arylselanylalkyne as byproduct.[6] The (Z)-1,2-bis-
arylselanyl alkenes are prepared (iv) with palladium catalysis
and trialkylphosphite ligands in degassed toluene at 100 °C (di-
nuclear and mononuclear trans palladium-arylchalcogen inter-
mediate complexes were isolated),[7] and (v) through cesium
selenolate nulceophiles generated from diaryl diselenides and
cesium salts or hydroxide and subsequent addition to terminal
alkynes.[8] Furthermore, 1-arylselanyalkenes can also be pre-
Scheme 1. Described protocols towards vinylic selenides.
Different methodologies from mentioned above comprise
hydrohalogenation of acetylenic selenides,[9b] reaction of vinyl
dichlorides with thiolate anions,[10] and photo-initiated addition
of diphenyl diselenide to allenes.[11] In general, published pro-
tocols starting from diselenides require the use of reducing
agents, transition metals as catalysts or other additives, as well
as high temperatures or complex starting materials.
In this context, photocatalysis arose in last decades as an
alternative for classical catalysis using transition metals and
other additives. Photochemical reactions can achieve noncon-
[a] Instituto de Química, Universidade Federal do Rio Grande do Sul (UFRGS),
Av. Bento Gonçalves 9500. CEP 91501-970, PO Box 15003, Porto Alegre, RS,
Brazil
E-mail: paulos@iq.ufrgs.br
[b] Laboratório de Catálise e Fenômenos Interfaciais,
Universidade Federal de Santa Catarina (UFSC),
CEP 88040-900 Florianópolis-SC, Brazil
E-mail: ricardo.affeldt@ufsc.br
Supporting information and ORCID(s) from the author(s) for this article are
available on the WWW under https://doi.org/10.1002/ejoc.201801303.
Eur. J. Org. Chem. 0000, 0–0
1
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Communication
ventional reactivity modes that are difficult to access via other mal reaction conditions, which are shown in Table 1. Our initial
pathways. Thereby, photochemistry reemerged as an important tests were conducted to verify light dependency and bismuth
tool for development of a wide array of novel synthetic meth- oxide effect (entries 1–6, Table 1). To our satisfaction, light-in-
odologies.[12] The most common photochemical mechanisms duced reaction allowed phenylselenyl insertion into alkyne in
comprehend light-induced atom transfer and photoredox catal- acetonitrile and argon atmosphere forming the desired (1-
ysis. These protocols have already been applied to chalcogen phenylethene-1,2-diyl)bis(phenylselane) (3a) in 80 % yield with
derivatives synthesis in which several classes of compounds, stereoselectivity of 93:7 (E:Z) (entry 1). The use of higher power
including indole, imidazole, selenophenes, selenides and selen- lamp did not improve yield and selectivity (entry 3). Addition
ylcyanates were prepared.[13]
of bismuth oxide, whose effectiveness on visible light is compa-
rable to traditional photocatalysts,[22] did not affect reaction
yield (entries 2 and 4). The presence of light, however, was es-
sential for product formation, since reactions conduced in the
dark, with or without heating, led to traces of the product only
(entries 5–7).
In this framework, the photolysis of dibenzyldiselenide under
UV 280 nm irradiation in acetonitrile was already described in
1975, leading to symmetric selenides through several radical
and excited intermediates.[14] Although the efficiency of radical
selenium species on reactions involving intramolecular cycliza-
tion in the presence of initiators such as tributhyltin and AIBN
is well established,[15] it was Ogawa's seminal work that de-
scribed the light-induced formation of phenylseleno radical and
addition to alkynes. The sources of light the authors used were
sunlight, UV 365 nm and tungsten 500 W, where the latter re-
sulted in high yields of (E)-bis-selenylated products after 24
hours at 40 °C without solvent, under argon atmosphere.[16]
They have also described (i) production of mono selenylated
compounds reacting alkynes with benzeneselenol in the pres-
ence of 10 mol-% of diphenyl diselenide upon the same light
irradiation in chloroform. The yields, reaction times and stereo-
selectivity were highly dependent on the alkyne substituents[17]
and (ii) the use of visible light (Xenon, >300 nm) on similar
transformations, e.g., reduction of dienes with benzenethiol and
diphenyl diselenide to internal alkenes,[18] also on three-compo-
nent coupling between diphenyl diselenide, alkenes and ethyl
propiolate.[19] They propose the formation of α-seleno radical
specie, which was already observed by trapping with isoprene
in the absence of oxygen.[20]
Table 1. Optimization of reaction conditions.[a]
Entry
Lamp
Aditive Solvent Time
Yield (%)[b,c]
1
2
3
4
5
6
CFL 27W
CFL 27W
CFL 45W
CFL 45W
–
–
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
DCM
MeCN
DCM
THF
2h
2h
2h
2h
2h
2h
1h
2h
89 (93:7)
88 (94:6)
90 (92:8)
81 (98:2)
6 (>99:1)
4 (>99:1)
5 (>99:1)
14 (96:4)
95 (89:11)
88 (87:13)
75 (82:18)
70 (74:26)
80 (93:7)
95 (97:3)
94 (96:4)
95 (90:10)
63 (95:5)
95 (92:8)
32 (>99:1)
60 (>99:1)
Bi2O3
–
Bi2O3
–
–
–
Bi2O3
7[d]
8[e]
9
–
–
–
–
–
–
–
–
–
–
–
–
–
–
CFL 27W
CFL 27W
CFL 27W
CFL 27W
CFL 27W
CFL 27W
CFL 27W
CFL 27W
CFL 27W
CFL 27W
Blue 26W
Green 26W
CFL UV 26W
2h
2h
2h
10
11
12
13
14
15
16[f]
17[g]
18
19
20
DMF
DCM
DCM
DCM
DCM
DCM
DCM
DCM
DCM
DCM
5 min
10 min
20 min
40 min
20 min
20 min
20 min
20 min
20 min
Since visible light is of easy access and of low environmental
and economic cost, we envisioned its use as source of energy
capable of tuning the reactivity of organochalcogen com-
pounds to prepare differently substituted olefins. The main fo-
cus of this work relies on the lack of a systematic study concern-
ing the light induced reactions of dichalcogenide compounds
with alkynes and also the avoidance of metals, reducing agents,
additives or other substances which are commonly described
in literature.
[a] Reaction conditions: phenylacetylene (0.1 mmol), diphenyldiselenide
(0.1 mmol) under argon atmosphere. [b] Isolated yield. [c] E/Z ratio in paren-
theses. [d] Temperature = 65 °C. [e] Aerobic condition. [f] 1.2 equivalents of
diphenyl diselenide. [g] 1.2 equivalents of phenylacetylene.
Although several methods are being developed, the chemis-
try of organoselenium compounds still lacks low environmental
impact and economic conditions. Regarding the synthesis of
the 1,2-bis-selenyl alkenes, which are important synthetic inter-
mediates and of biological relevance, and in consonance with
our continuous interest in the synthesis of organoselenium
compounds,[21] we describe our efforts to develop a very cheap
and simple method. This is important since we are very inter-
ested on selective functionalization of C–C bonds by organyl-
selanyl groups through intermediates generated by light irradi-
ation.
When reaction was performed under aerobic condition a sig-
nificant decrease on yield (14 %) was observed (entry 8). The
formation of oxidized products from alkynes in presence of or-
ganoyl dichalcogenides under oxygen atmosphere is already
reported and could be related with the observed low yield.[23]
Application of other solvents, such as, dichloromethane (DCM),
tetrahydrofurane (THF) and dimethylformamide (DMF) were
also evaluated (entries 9–11). Best result of the series was
achieved with DCM in which a slight increase of yield and selec-
tivity was observed.
In the following tests, reaction pathway was monitored ac-
cording to time by 1H-NMR and GC–MS (entries 12–15) and
maximum conversion (95 %) and regioselectivity (97:3) was
Results and Discussion
To begin our study, diphenyl diselenide 1a and phenylacetylene reached in 20 min only. Furthermore, stoichiometric changes
2a were selected as model substrates for investigation of opti- showed that no improvement occurred with excess of diphenyl
Eur. J. Org. Chem. 0000, 0–0
www.eurjoc.org
2
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Communication
diselenide while excess of phenylacetylene was harmful to the
reaction (entries 16–17).
Table 3. Reaction scope for differently substituted olefins.
It is worth to mention that reaction results were similar when
applying blue lamp in substitution to white lamp while other
light sources gave unsuccessful results. This was already ex-
pected according to observed absorption spectra of diphenyl
diselenide and it will be discussed in the following. After opti-
mization study, the following conditions were established:
diaryl diselenide (1 equiv.), alkyne (1 equiv.), dichloromethane,
room temperature and CFL 27 W irradiation for 20 minutes un-
der inert atmosphere.
A study of UV/Visible absorption of diaryl dichalcogenides
were performed for different substituted diaryl diselenides
bearing electron donating and withdrawing groups, and for
sulfur and tellurium related compounds in dichloromethane, as
shown in Table 2. These results revealed that absorption
maxima of diaryl diselenides are located around 340 nm, with
corresponding absorption band extending from visible light re-
gion to UVA. Disulfide and ditelluride exhibited absorption max-
ima at 280 and 400 nm, respectively. Comparing absorption
range according to chalcogenide, sulfide presented hypsochro-
mic absorption band (< 350 nm) with its maxima in the UVA
region, while telluride absorption relies on visible (400 nm).
These results corroborates the use of commercial white lamp
as suitable for preparing seleno or telluro-functionalized olefins.
UV/Vis spectroscopic data for the dichalcogenides as well as
UV/Vis emission profile of the lamps used in the reactions are
available in ESI section.
The scope of the procedure was next investigated (Table 3).
The generality of the reaction was proved in terms of yield and
stereoselectivity. Introduction of various substituents in ortho,
meta and para positions of diaryl diselenide moiety was toler-
ated, and the corresponding products were isolated in 31–95 %
yield (3a–f). Both derivatives 3d and 3f presented moderated
yields evidencing that steric hindrance influence in reaction
success. The variation with respect to the alkyne substituents
such as p-Me, p-Cl, p-OMe, p-NO2, p-COOMe, o-NH2 and disub-
[a] Isolated yields. [b] E/Z ratio calculated by GC-MS. [c] E/Z ratio calculated by
1H NMR spectroscopy. [d] Gram-scale reaction (10 mmol). [e] 12h of reaction.
stituted o-CH3-p-OMe was tolerated allowing preparation of ogy, a gram-scale reaction was performed for 3m compound in
compounds 3g–m. In contrast with excellent results obtained which resulted in a very little decrease in regioselectivity (E/Z
for o-NH2 3m product, only 40 % yield was achieved for o- ratio of 90:10). It is worth to mention that reaction did proceed
methylated substituted 3j. Noteworthy, for screened alkynes using ditolyl ditelluride, however it was not possible to isolate
the E/Z ratio remained virtually the same.
the product by column chromatography due to its low stability.
Conversion and E/Z ratio were estimated by 1H NMR of the
crude mixture as ca. 45 % (69:31) (See ESI Section).
Additionally, electron-donating and electron-withdrawing
substituents in alkyne and diaryl diselenide were combined giv-
ing 3n–3q. Moderately selectivity was observed for 3n and 3p
The outstanding stereoselectivity of photo-induced function-
and the yield achieved for 3q reinforce steric effect of ortho alization of C–C bonds by organoselenium groups led us to
functionalized diselenides. In such cases of lower yields, no perform additional experiments in search of mechanism in-
other by-products were obtained and only the reactants were sights. First, reaction of diphenyl diselenide (1a) and phenyl-
recovered. To show the synthetic usefulness of this methodol- acetylene (2a) was conducted turning on and turning off light
Table 2. UV/Vis absorption data of diaryl dichalcogenides in dichloromethane (10–4
M).
abs
max
abs
Dichalcogenide
ε
(M
–1 cm–1
)
λ
(nm)
max
Absorption range (nm)
Diphenyl diselenide
922
1570
888
1390
588
330
360
350
280
400
< 460
< 460
< 460
< 350
340–500
Bis(p-methoxyphenyl) diselenide
Bis(m-trifluoromethylphenyl) diselenide
Diphenyl disulfide
Diphenyl diteluride
Eur. J. Org. Chem. 0000, 0–0
www.eurjoc.org
3
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Communication
source and monitoring by GC–MS for 0–25 minutes (Figure 1). ing to formation of anti-Markovnikov intermediate. A second
In those periods that reaction kept in absence of light, no reac- insertion of radical selenium moiety produces both E and Z
tion or transformation occurred. In presence of light, it was ob- olefins. A last step of photoisomerization of Z to E affords
served both E-Z isomers being formed with major E-isomer. mainly the E formation.
While reaction proceeds, a decreased amount of Z-isomer is
observed in opposite to the increase of the E-isomer. This in-
crease of E-isomer in reaction progress is also observed in
1HNMR (Figure 2) in which singlet attributed to olefinic
hydrogen located at δ = 7.06 ppm increase its intensity.[24]
A
control experiment showed that 2,2,6,6-tetramethylpiperidin-1-
yloxyl (TEMPO) as radical scavenger inhibits product formation
suggesting the likely involvement of
(Scheme 2).
a radical process
Scheme 3. Proposed reaction radical mechanism induced by light.
Conclusions
In summary, a photo-induced process proved to be an efficient,
fast, and highly selective methodology to achieve selenium
functionalized compounds, avoiding use of metal catalysts or
additives, high temperatures, long reaction times, and complex
reagents. This light driven reaction allows preparation of several
compounds through radical selenium addition mechanism tol-
erating a wide range of functional groups. Further investiga-
tions to apply these olefins as intermediates in other organic
reactions, such as C-H activation and intramolecular hydroamin-
ation are underway.
Figure 1. Reaction conversion monitoring by GC–MS in which white and grey
areas are related to lamp on-lamp off, respectively.
Acknowledgments
This research was financially supported in part by CNPq, CAPES
and FAPERGS.
Keywords: Photochemistry · Selenium · Stereoselective
synthesis · Isomerization · Visible light
Figure 2. Reaction conversion monitoring by 1H NMR, showing the decrease
of the diphenyl diselenide signals and the increasing of (E)-product signal.
[1] a) G. A. M. Jardim, E. H. G. da Cruz, W. O. Valença, D. J. B. Lima, B. C.
Cavalcanti, C. Pessoa, J. Rafique, A. L. Braga, C. Jacob, E. N. S. Júnior,
Molecules 2018, 23, 83; b) S. Kumar, N. Sharma, I. K. Maruya, A. K. K.
Bhasin, N. Wangoo, P. Brandão, V. Félix, K. K. Bhasin, R. K. Sharma, Eur. J.
Med. Chem. 2016, 123, 916; c) F. S. S. Souza, N. Seus, D. Alves, H. D. Salles,
P. H. Schneider, L. Savegnago, M. Castro, Neurosci. Lett. 2017, 651, 182;
d) J. B. Ramalho, A. P. Izaguirry, M. B. Soares, C. C. Spiazzi, N. F. Pavin,
R. F. Affeldt, D. S. Lüdtke, S. Pinton, F. W. Santos, M. Prigol, Physiol. Behav.
2018, 184, 27.
Scheme 2. Controlled experiment in presence of radical scavenger.
[2] a) D. Alves, R. F. Schumacher, R. Brandão, C. W. Nogueira, G. Zeni, Synlett
2006, 7, 1035; b) G. Zeni, D. Alves, J. M. Pena, A. L. Braga, H. A. Stefani,
C. W. Nogueira, Org. Biomol. Chem. 2004, 2, 803; c) A. V. Martynov, V. A.
Potapov, S. V. Amosova, N. A. Makhaeva, I. P. Beletskaya, L. J. Hevesi,
Organomet. Chem. 2003, 674, 101.
According to the experimental results and previous reports,
a proposed reaction mechanism is presented in Scheme 3. The
first step comprises the reversible homolytic cleavage of Se–Se
bond. The selenium radical specie adds to the triple bond lead-
Eur. J. Org. Chem. 0000, 0–0
www.eurjoc.org
4
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Communication
[3] a) G. Sartori, J. S. S. Neto, A. P. Pesarico, D. F. Back, C. W. Nogueira, G.
Zeni, Org. Biomol. Chem. 2013, 11, 1199; b) E. J. Lenardão, L. C. C. Gon-
çalves, F. N. Victório, D. B. Lima, P. M. Y. Borba, G. Perin, L. Savegnago,
Tetrahedron Lett. 2014, 55, 5275.
[14]
J. Y. C. Chu, D. G. Marsh, W. H. H. Guenther, J. Am. Chem. Soc. 1975, 97,
4905.
J. E. Lyons, C. H. Shiesser, K. J. Sutej, Org. Chem. 1993, 58, 5632.
A. Ogawa, H. Yokoyama, K. Yokoyama, T. Masawaki, N. Kambe, N. J. Son-
oda, Org. Chem. 1991, 56, 5721.
A. Ogawa, R. Obayashi, M. Sekiguchi, T. Masawaki, N. Kambe, N. Sonoda,
Tetrahedron Lett. 1992, 33, 1329.
T. Mitamura, Y. Imanishi, A. Nomoto, M. Sonoda, A. Ogawa, Bull. Chem.
Soc. Jpn. 2007, 80, 2443.
[15]
[16]
[4] E. F. Lopes, L. C. Gonçalves, J. C. G. Vinueza, R. G. Jacob, G. Perin, C. Santi,
E. J. Lenardão, Tetrahedron Lett. 2015, 56, 6890.
[17]
[18]
[19]
[5] L. C. C. Gonçalves, F. N. Victória, D. B. Lima, P. M. Y. Borba, G. Perin, L.
Savegnago, E. J. Lenardão, Tetrahedron Lett. 2014, 55, 5275.
[6] a) R. G. Lara, P. C. Rosa, L. K. Soares, M. S. Silva, R. G. Jacob, G. Perin,
Tetrahedron 2012, 68, 10414; b) G. Perin, E. L. Borges, D. Alves, Tetrahe-
dron Lett. 2012, 53, 2066.
[7] a) V. P. Ananikov, M. A. Kabeshov, I. P. Beletskaya, V. N. Khrustalev, M. Y.
Antipin, Organometallics 2005, 24, 1275; b) M. Cai, Y. Wang, W. Hao,
Green Chem. 2007, 9, 1180.
[8] a) N. Yutaka, O. Haruko, K. Yuya, Bull. Chem. Soc. Jpn. 2009, 82, 1170; b)
R.-L. Lu, X.-H. Xu, W. Q. Liu, Q.-L. Zhang, X. Chen, Chin. Chem. Lett. 2005,
16, 325.
[9] a) J. V. Comasseto, P. H. Menezes, H. A. Stefani, G. Zeni, A. L. Braga,
Tetrahedron 1996, 52, 9687; b) C. Tidei, L. Sancineto, L. Bagnoli, B. Battis-
telli, F. Marini, C. Santi, Eur. J. Org. Chem. 2014, 5968.
A. Ogawa, M. Doi, I. Ogawa, T. Hirao, Angew. Chem. Int. Ed. 1999, 38,
2027; Angew. Chem. 1999, 111, 2066.
[20]
[21]
M. M. Alam, O. Ito, Y. Koga, A. Ouchi, Int. J. Chem. Kinet. 1998, 30, 193.
a) M. C. D. F. Xavier, B. Goldani, R. F. Schumacher, G. Perin, P. H. Schneider,
D. Alves, Mol. Catal. 2017, 427, 73; b) R. A. Balaguez, V. G. Ricordi, R. C.
Duarte, J. M. Toldo, C. M. Santos, P. H. Schneider, P. F. B. Gonçalves, F. S.
Rodembusch, D. Alves, RSC Adv. 2016, 6, 49613.
a) L. Buglioni, P. Riente, E. Palomares, M. A. Pericàs, Eur. J. Org. Chem.
2017, 6986; b) P. Riente, A. M. Adams, J. Albero, E. Palomares, M. A.
Pericàs, Angew. Chem. Int. Ed. 2014, 53, 9613; Angew. Chem. 2014, 126,
9767; c) H.-Y. Jiang, J. Liu, K. Cheng, W. Sun, J. Lin, J. Phys. Chem. C 2013,
117, 20029; d) H. Kisch, Angew. Chem. Int. Ed. 2013, 52, 812; Angew.
Chem. 2013, 125, 842.
[22]
[10] a) W. E. Truce, M. M. Boudakian, R. F. Heine, R. J. Mc-Manimie, J. Am.
Chem. Soc. 1956, 78, 2743.
[11] A. Ogawa, K. Yokoyama, H. Yokoyama, M. Sekiguchi, N. Kambe, N. Son-
oda, Tetrahedron Lett. 1990, 31, 5931.
[12] a) N. A. Romero, D. A. Nicewicz, Chem. Rev. 2016, 116, 10075; b) M. H.
Shaw, J. Twilton, D. W. C. MacMillan, J. Org. Chem. 2016, 81, 6898.
[13] a) J. Martens, K. Praefcke, J. Organomet. Chem. 1980, 98, 321; b) S. Saba,
J. Rafique, M. S. Franco, A. R. Schneider, L. Espíndola, D. O. Silva, A. L.
Braga, Org. Biomol. Chem. 2018, 16, 880.
[23]
[24]
V. Strukil, I. Sajko, Chem. Commun. 2017, 53, 9101.
G. Perin, R. G. Jacob, L. G. Dutra, F. Azambuja, G. F. F. Santos, E. J. Le-
nardão, Tetrahedron Lett. 2006, 47, 935.
Received: August 21, 2018
Eur. J. Org. Chem. 0000, 0–0
www.eurjoc.org
5
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Communication
Photochemistry
A. C. H. Weber, F. L. Coelho,
R. F. Affeldt,* P. H. Schneider* ........ 1–6
Visible-Light Promoted Stereoselec-
tive Arylselanyl Functionalization of
Alkynes
In this work a series of bis-arylselanyl achieved in a very clean and fast way,
olefins were synthesized using visible yielding E-olefins with good stereo-
white light from common fluorescent selectivity, through radical addition-
lamps as energy source, without cata- photoisomerization.
lyst or additives. The products were
DOI: 10.1002/ejoc.201801303
Eur. J. Org. Chem. 0000, 0–0
www.eurjoc.org
6
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim