Synthesis of 3-Alkynylselenophene Derivatives by a Copper-Free Sonogashira Cross-Coupling Reaction

Article abstract of DOI:10.1002/ejoc.200700707

3-Iodoselenophene derivatives undergo direct Sonogashira cross-coupling reactions with several terminal alkynes in the presence of a catalytic amount of Pd(PPh₃)₂Cl₂ in DMF with Et₃N as the base under cocatalyst

Full text of DOI:10.1002/ejoc.200700707

FULL PAPER
DOI: 10.1002/ejoc.200700707
Synthesis of 3-Alkynylselenophene Derivatives by a Copper-Free Sonogashira
Cross-Coupling Reaction
Diego Alves,[a] Joel S. dos Reis,[a] Cristiane Luchese,[a] Cristina W. Nogueira,[a] and
Gilson Zeni*[a]
Keywords: Palladium / Cross-coupling / Selenium / Selenophene
3-Iodoselenophene derivatives undergo direct Sonogashira
cross-coupling reactions with several terminal alkynes in the
presence of a catalytic amount of Pd(PPh3)2Cl2 in DMF with
Et3N as the base under cocatalyst-free conditions. This cross-
coupling reaction proceeded cleanly under mild conditions
and was performed with propargylic alcohols and propar-
gylic ethers, as well as alkyl, vinyl and aryl alkynes to furnish
the corresponding 3-alkynylselenophenes in good-to-excel-
lent yields.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2008)
conductive-doped polythiophenes on electrochemical poly-
merization.[6]
Introduction
Palladium-catalyzed carbon–carbon bond formation, a
key stage in the synthesis of many currently interesting het-
erocycle-containing compounds,[1] has proved to proceed
generally and effectively. As a consequence of the current
interest in the development of coupling substrates that are
more economic and more easily accessible and reactive,
even under mild conditions, there has been significant pro-
gress in the optimization of palladium-catalyzed coupling
systems. The palladium-catalyzed cross-coupling reactions
of vinyl or aryl halides with terminal alkynes is a powerful
and versatile synthetic tool for the preparation of substi-
tuted acetylenes.[2] Numerous modifications to the original
protocol and the improvement of many aspects of sp–sp2
carbon bond formation have led to widespread application
of this reaction in the synthesis of a variety of compounds,
including various heterocyclic compounds.[3] Carbon–car-
bon bond formation is thus a useful method for the synthe-
sis of building blocks that can be used in the preparation
of natural products.[4]
Halochalcogenophenes are an important class of com-
pounds that can undergo further functionalization.[7] In
particular, 2-iodo- and 2-bromoselenophenes are useful
substrates for a variety of C–C, C–N and C–S bond-form-
ing reactions. Our continued interest in the syntheses[8] and
applications[7] of chalcogenophenes in organic synthesis
prompted us to examine and expand the scope of the Sono-
gashira reaction of 3-iodoselenophene derivatives with dif-
ferent terminal alkynes to obtain 3-alkynylselenophenes 3a–
o (Scheme 1).
Scheme 1. General scheme for the cross-coupling of 3-iodoseleno-
phene derivatives with terminal alkynes.
Among heterocycles, chalcogenophene derivatives play
an important role in organic synthesis because of their ex-
cellent electrical properties and environmental stability.
Chalcogenophene oligomers are compounds of current
interest because many of them show photoenhanced bio-
logical activity,[5] and α-type chalcogenophene oligomers,
such as 5,2Ј:5Ј,2ЈЈ-terthiophene, produce crystalline, electro-
Results and Discussion
Our initial studies focused on the development of opti-
mal reaction conditions. For this purpose, 2,5-diphenyl-3-
iodoselenophene (1a) and 2-methyl-3-butyn-2-ol (2a) were
used as standard substrates. Starting 3-iodoselenophene 1a
was prepared by using an electrophilic cyclization proto-
col.[8] Thus, a mixture of 3-iodoselenophene 1a (0.5 mmol),
alkyne 2a (1.5 mmol) and Et3N (1mL) in DMF (2.5 mL)
was treated with a variety of palladium catalysts (Table 1).
[a] Laboratório de Síntese, Reatividade, Avaliação Farmacológica
e Toxicológica de Organocalcogênios, CCNE, Universidade
Federal de Santa Maria,
Santa Maria, Rio Grande do Sul, 97105-900, Brazil
Fax: +55-55-3220-8998
E-mail: gzeni@quimica.ufsm.br
Supporting information for this article is available on the
WWW under http://www.eurjoc.org or from the author.
Eur. J. Org. Chem. 2008, 377–382
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
377

D. Alves, J. S. dos Reis, C. Luchese, C. W. Nogueira, G. Zeni
Table 2. Optimization of reaction conditions.[a]
FULL PAPER
Table 1. Influence of catalyst in the reaction of 1a and 2a.[a]
Entry
Base
Solvent
Yield of 3a [%][a]
Entry
Palladium salt [mol-%]
Yield of 3a [%]
1
2
3
4
5
6
7
8
Et3N
K2CO3
KOAc
K3PO4
KOH
Et3N
Et3N
Et3N
Et3N
Et3N
Et3N
Et3N
Et3N
Et3N
DMF
DMF
DMF
DMF
DMF
THF
CH2Cl2
toluene
MeOH
pyrrolidine
DME
1,4-dioxane
DMSO
H2O
91
65
62
46
79
39
52
28
28
trace
60
trace
88
65
1
2
3
4
5
6
7
8
9
10
PdCl2(PPh3)2 (10)
PdCl2(PhCN)2 (10)
PdCl2 (10)
Pd(OAc)2 (10)
Pd(acac)2 (10)
Pd(PPh3)4 (10)
Pd(dba)2 (10)
Pd(dppe)2 (10)
PdCl2(PPh3)2 (5)
PdCl2(PPh3)2 (1)
91
14
26
25
16
trace
17
trace
57
21
9
10
11
12
13
14
[a] Reaction time was 12 h.
[a] Reaction time was 12 h.
We found that the cross-coupling reaction of 3-iodoselen-
ophene 1a with terminal alkyne 2a was best catalyzed by
PdCl2(PPh3)2 (Table 1, Entry 1). By using this catalyst
(10 mol-%), corresponding 3-alkynylselenophene 3a was
obtained in high yield (91% isolated product). Other
The reaction worked well for a variety of propargylic
palladium complexes, such as PdCl2(PhCN)2, PdCl2, alcohols (Table 3). Both hindered and nonhindered propar-
Pd(OAc)2, Pd(acac)2, Pd(PPh3)4, Pd(dba)2 and Pd(dppe)2, gylic alcohols gave the desired products in excellent yields
were less effective (Table 1, Entries 2–8). It is important to (Table 3, Entries 1–5). Our experiments showed that the re-
note that when the amount of catalyst was reduced from action with propargylic ether gave the coupled product in
10 to 1 mol-%, a decrease in yield was observed (Table 1, moderate yield (Table 3, Entry 6). Alkynes containing an
Entries 9 and 10).
aryl or vinyl group were coupled in excellent yields (Table 3,
We also observed that the nature of the base was critical Entries 7 and 8). We found that steric effects have an influ-
to the success of the coupling. When different bases such ence on the coupling reaction, as alkyne 2j containing a
as K2CO3, KOAc, K3PO4 and KOH were used instead of tert-butyl group gave a lower yield of product relative to
Et3N, moderate yields of desired product 3a were obtained that obtained with n-pentane-substituted alkyne 2i (Table 3,
(Table 2, Entries 2–5).
Entry 9 vs. 10).
With regard to the influence of the solvent in this coup-
In an attempt to broaden the scope of our synthetic pro-
ling reaction, optimal results were achieved by using DMF cedure, the possibility of performing the reaction with other
and DMSO (Table 2; Entries 1 and 13). By using CH2Cl2, 3-iodoselenophenes containing a hydroxy, an aryl or an
DME or H2O (Table 2, Entries 7, 11 and 14, respectively) as alkyl group within the side chain was also investigated. As
the solvents moderate yields were obtained, whereas other illustrated in Table 3, the cross-coupling reaction of 1b–e
solvents such as THF, toluene and MeOH (Table 2, En- with alkynes, under the same reaction conditions, led to
tries 6, 8 and 9, respectively) furnished only small amounts corresponding coupling products 3k–o in high yields
of desired product 3a. Only trace amounts of product 3a (Table 3, Entries 11–15).
were obtained with the use of pyrrolidine or 1,4-dioxane as
The 3-alkynylselenophenes obtained by this protocol ap-
the solvent (Table 2, Entries 10 and 12, respectively).
pear highly promising as intermediates in the preparation
Careful analysis of the results of these reactions revealed of more highly substituted selenophenes. To demonstrate
the optimum conditions to include the use of PdCl2- this, we carried out the synthesis of vinylic telluride 4 from
(PPh3)2 (10 mol-%), 3-iodoselenophene 1a (0.5 mmol), ter- compound 3a. Many classes of organotellurium com-
minal alkyne 2a (1.5 mmol) and Et3N (1 mL) in DMF pounds have been prepared and studied to date and vinylic
(2.5 mL) at room temperature for 12 h. Under these reac- tellurides are certainly the most useful and promising of
tion conditions we were able to prepare 4-(2,5-diphenylsele- these in organic synthesis.[9] Thus, 3-alkynylselenophene 3a
nophen-3-yl)-2-methyl-but-3-yn-2-ol (3a) in 91% yield. To was treated with NaOH in toluene and heated under reflux
demonstrate the efficiency of this protocol and to explore for 4 h. The terminal alkyne generated in situ was treated
the generality of our method, we extended the reaction to with BuTeTeBu and NaBH4 in ethanol, and the reaction
several terminal alkynes and other 3-iodoselenophenes mixture was stirred under reflux for 6 h to give correspond-
(Table 3).
ing vinylic telluride 4 in 68% yield (Scheme 2).
378
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© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2008, 377–382

Synthesis of 3-Alkynylselenophene Derivatives under Cu-Free Conditions
Table 3. Cross-coupling reaction of 3-iodoselenophenes 1a–e and alkynes 2a–j.
[a] Yields of 3a–o are given for isolated products.
Eur. J. Org. Chem. 2008, 377–382
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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379

D. Alves, J. S. dos Reis, C. Luchese, C. W. Nogueira, G. Zeni
FULL PAPER
29.1, 9.0ppm. MS: m/z (%) = 361 (100), 332 (53), 317 (22), 281
(71), 206 (44), 129 (56), 77 (35). HRMS: calcd. for C22H20OSe
380.0679; found 380.0683.
1-(2,5-Diphenylselenophen-3-ylethynyl)cyclohexanol (3c): Yield:
1
0.174 g (86%). H NMR (200 MHz, CDCl3): δ = 7.84–7.79 (m, 2
H), 7.56–7.51 (m, 3 H), 7.43–7.29 (m, 6 H), 2.12 (s, 1 H), 1.72–1.52
(m, 8 H), 1.36–1.17 (m, 2 H) ppm. 13C NMR (50 MHz, CDCl3): δ
= 151.6, 147.4, 135.5, 135.4, 129.8, 128.9, 128.4, 128.1, 128.0, 127.9,
126.0, 120.2, 93.8, 81.3, 69.3, 39.9, 25.2, 23.3 ppm. MS: m/z (%) =
387 (100), 305 (32), 281 (65), 206 (47), 129 (63), 77 (41). HRMS:
calcd. for C24H22OSe 406.0836; found 406.0831.
1-(2,5-Diphenylselenophen-3-yl)pent-1-yn-3-ol (3d): Yield: 0.166 g
(91%). 1H NMR (200 MHz, CDCl3): δ = 7.83–7.78 (m, 2 H), 7.55–
7.50 (m, 3 H), 7.44–7.29 (m, 6 H), 4.54–4.49 (m, 1 H), 2.00 (s, 1
H), 1.87–1.73 (m, 2 H), 1.04 (t, J = 7.4 Hz, 3 H) ppm. 13C NMR
(50 MHz, CDCl3): δ = 151.9, 147.5, 135.5, 135.4, 129.7, 128.9,
128.5, 128.1, 128.0, 127.9, 126.0, 119.9, 90.9, 82.0, 64.3, 30.8,
9.4 ppm. MS: m/z (%) = 347 (100), 318 (21), 281 (69), 206 (52),
129 (73), 77 (35). HRMS: calcd. for C211H8OSe 366.0523; found
366.0528.
Scheme 2. Synthesis of vinylic telluride 4.
Conclusions
3-(2,5-Diphenylselenophen-3-yl)prop-2-yn-1-ol (3e): Yield: 0.128 g
(74%). 1H NMR (200 MHz, CDCl3): δ = 7.82–7.77 (m, 2 H), 7.55–
7.29 (m, 9 H), 4.46 (s, 2 H), 1.78 (s, 1 H) ppm. 13C NMR
(100 MHz, CDCl3): δ = 152.2, 147.6, 135.4, 135.3, 129.7, 128.9,
128.6, 128.2, 128.0, 127.9, 125.9, 119.8, 88.2, 82.7, 51.6 ppm. MS:
m/z (%) = 319 (100), 281 (55), 206 (47), 129 (63), 77 (40). HRMS:
calcd. for C191H4OSe 338.0210; found 338.0207.
We have explored the Sonogashira reaction of 3-iodose-
lenophenes with several terminal alkynes in the presence of
a catalytic amount of Pd(PPh3)2Cl2 with DMF as the sol-
vent and Et3N as the base under mild cocatalyst-free condi-
tions. We thus established a new route for the preparation
of 3-alkynylselenophene derivatives, which were produced
in excellent yields. The 3-alkynylselenophenes obtained ap-
pear to be highly promising as intermediates in the prepara-
tion of more highly substituted selenophenes. Studies of the
biological activity of these compounds are under study in
our lab.
3-(3-Ethoxyprop-1-ynyl)-2,5-diphenylselenophene (3f): Yield: 0.122 g
(67%). 1H NMR (200 MHz, CDCl3): δ = 7.83–7.78 (m, 2 H), 7.55–
7.50 (m, 3 H), 7.44–7.29 (m, 6 H), 4.34 (s, 2 H), 2.61 (q, J = 6.9 Hz,
2 H), 1.24 (t, J = 6.9 Hz, 3 H) ppm. 13C NMR (100 MHz, CDCl3):
δ = 152.1, 147.5, 135.5, 135.4, 129.8, 128.9, 128.5, 128.1, 128.0,
127.9, 126.0, 120.0, 86.5, 83.1, 65.4, 58.6, 15.0 ppm. MS: m/z (%)
= 365 (100), 320 (73), 281 (41), 206 (61), 129 (55), 77 (47). HRMS:
calcd. for C211H8OSe 366.0523; found 366.0518.
Experimental Section
2,5-Diphenyl-3-phenylethynylselenophene (3g): Yield: 0.180 g (94%).
1H NMR (400 MHz, CDCl3): δ = 7.92–7.89 (m, 2 H), 7.61 (s, 1 H),
7.58–7.56 (m, 2 H), 7.49–7.29 (m, 11 H) ppm. 13C NMR (100 MHz,
CDCl3): δ = 151.8, 147.5, 135.7, 135.5, 131.4, 129.6, 129.0, 128.6,
128.4, 128.16, 128.15, 128.14, 128.0, 126.1, 123.4, 120.6, 90.3,
86.9 ppm. MS: m/z (%) = 383 (100), 306 (56), 282 (77), 204 (38),
128 (51), 101 (19), 77 (28). HRMS: calcd. for C241H6Se 384.0417;
found 384.0411.
General Procedure for Iodoselenophene–Alkyne Cross-Coupling Re-
actions: To a Schlenk tube, under an atmosphere of argon, contain-
ing the appropriate 3-iodoselenophene (0.50 mmol) in DMF
(2.5 mL) was added Pd(PPh3)2Cl2 (0.035g, 0.05 mmol). The re-
sulting solution was stirred for 5 min at room temperature. After
this time, the appropriate terminal alkyne (1.5 mmol) dissolved in
Et3N (1 mL) was added dropwise, and the reaction mixture was
allowed to stir at room temperature for 12 h. After this time, the
mixture was diluted with CH2Cl2 (20 mL) and washed with brine
(3ϫ20 mL). The organic phase was separated, dried with MgSO4
and concentrated under vacuum. The residue was purified by flash
chromatography on silica gel (ethyl acetate/hexane, 1:8).
3-Cyclohex-1-enylethynyl-2,5-diphenylselenophene
(3h):
Yield:
1
0.180 g (93%). H NMR (200 MHz, CDCl3): δ = 7.88–7.83 (m, 2
H), 7.57–7.25 (m, 9 H), 6.19–6.14 (m, 1 H), 2.22–2.12 (m, 4 H),
1.68–1.59 (m, 4 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 150.5,
147.0, 135.8, 135.6, 135.1, 129.8, 128.9, 128.4, 128.0, 127.9, 127.8,
126.0, 121.0, 120.8, 92.4, 84.2, 28.9, 25.8, 22.3, 21.5 ppm. MS: m/z
(%) = 387 (100), 306 (65), 281 (56), 206 (42), 129 (39), 77 (62).
HRMS: calcd. for C24H20Se 388.0730; found 388.0734.
Diphenylselenophen-3-yl)-2-methyl-but-3-yn-ol (3a): Yield: 0.166 g
(91%). 1H NMR (400 MHz, CDCl3): δ = 7.83–7.81 (m, 2 H), 7.54–
7.50 (m, 3 H), 7.42–7.29 (m, 6 H), 2.11 (s, 1 H), 1.60 (s, 6 H) ppm.
13C NMR (100 MHz, CDCl3): δ = 151.7, 147.4, 135.5, 135.4, 129.5,
128.9, 128.4, 128.1, 128.0, 127.9, 125.9, 119.9, 94.6, 79.4, 65.6,
31.2 ppm. MS: m/z (%) = 347 (100), 305 (77), 281 (61), 128 (50),
77 (21). HRMS: calcd. for C21H18OSe 366.0523; found 366.0529.
3-Hept-1-ynyl-2,5-diphenylselenophene (3i): Yield: 0.182 g (97%).
1H NMR (200 MHz, CDCl3): δ = 7.87–7.83 (m, 2 H), 7.56–7.49
(m, 3 H), 7.41–7.28 (m, 6 H), 2.39 (t, J = 7.1 Hz, 2 H), 1.67–1.49
(m, 2 H), 1.46–1.28 (m, 4 H), 0.91 (t, J = 7.1 Hz, 3 H) ppm. 13C
1-(2,5-Diphenylselenophen-3-yl)-3-methylpent-1-yn-3-ol (3b): Yield:
1
0.183 g (97%). H NMR (200 MHz, CDCl3): δ = 7.83–7.78 (m, 2 NMR (100 MHz, CDCl3): δ = 150.3, 146.9, 135.8, 135.6, 130.2,
H), 7.56–7.50 (m, 3 H), 7.44–7.29 (m, 6 H), 2.07 (s, 1 H), 1.76 (q, 128.9, 128.4, 127.9, 127.8, 127.8, 126.0, 121.3, 91.7, 77.7, 31.1, 28.2,
J = 7.5 Hz, 2 H), 1.54 (s, 3 H), 1.05 (t, J = 7.5 Hz, 3 H) ppm. 13C
NMR (100 MHz, CDCl3): δ = 151.7, 147.4, 135.5, 135.4, 129.7,
128.9, 128.4, 128.1, 128.0, 127.9, 126.0, 120.0, 93.7, 80.5, 69.2, 36.4,
22.2, 19.5, 14.0 ppm. MS: m/z (%) = 377 (100), 362 (73), 348 (33),
334 (30), 320 (26), 281 (56), 206 (58), 129 (61), 77 (53). HRMS:
calcd. for C23H22Se 378.0887; found 378.0882.
380
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Synthesis of 3-Alkynylselenophene Derivatives under Cu-Free Conditions
3-(3,3-Dimethylbut-1-ynyl)-2,5-diphenylselenophene (3j): Yield:
to reach room temperature, diluted with EtOAc (60 mL) and
washed with brine (3ϫ30 mL) and water (3ϫ30 mL). The organic
1
0.127 g (70%). H NMR (200 MHz, CDCl3): δ = 7.89–7.85 (m, 2
H), 7.56–7.48 (m, 3 H), 7.44–7.27 (m, 6 H), 1.31 (s, 9 H) ppm. 13C phase was dried with anhydrous MgSO4, the solvent was removed
NMR (50 MHz, CDCl3): δ = 150.2, 146.8, 135.8, 135.6, 130.1,
128.9, 128.3, 127.9, 127.8, 127.7, 126.0, 121.2, 99.6, 76.5, 30.8,
28.2 ppm. MS: m/z (%) = 363 (100), 318 (63), 281 (68), 206 (42),
129 (58), 77 (39). HRMS: calcd. for C22H20Se 364.0730; found
364.0733.
under reduced pressure and the residue was purified by flash
chromatography on silica gel (hexane). Yield: 0.335 g (68%). 1H
NMR (400 MHz, CDCl3): δ = 7.80 (s, 1 H), 7.59–7.57 (m, 2 H),
7.48–7.23 (m, 9 H), 6.91 (d, J = 10.8 Hz, 1 H), 2.76 (t, J = 7.4 Hz,
2 H), 1.83 (quint., J = 7.4 Hz, 2 H), 1.42 (sext., J = 7.4 Hz, 2 H),
0.94 (t, J = 7.4 Hz, 3 H) ppm. 13C NMR (100 MHz, CDCl3): δ =
148.1, 138.6, 136.1, 132.9, 129.6, 129.4, 128.9, 128.5, 127.7, 127.6,
126.1, 125.3, 124.2, 105.1, 34.0, 24.9, 13.4, 8.4 ppm. MS: m/z (%)
= 495 (100), 438 (25), 311 (86), 282 (70), 210 (62), 204 (38), 184
(75), 128 (51), 77 (25). HRMS: calcd. for C22H22SeTe 495.9949;
found 495.9954.
4-(2,5-Dibutylselenophen-3-yl)-2-methylbut-3-yn-2-ol (3k): Yield:
0.134 g (83%). 1H NMR (200 MHz, CDCl3): δ = 6.76 (s, 1 H), 2.89
(t, J = 7.8 Hz, 2 H), 2.75 (t, J = 7.5 Hz, 2 H), 2.07 (s, 1 H), 1.70–
1.56 (m, 10 H), 1.49–1.28 (m, 4 H), 0.97–0.88 (m, 6 H) ppm. 13C
NMR (100 MHz, CDCl3): δ = 155.0, 148.5, 128.0, 119.6, 94.6, 78.5,
65.7, 34.3, 34.2, 32.1, 31.6, 31.1, 22.1, 22.0, 13.8, 13.7 ppm. MS:
m/z (%) = 307 (100), 278 (34), 242 (77), 211 (63), 183 (52), 155 (39),
129 (32). HRMS: calcd. for C17H26OSe 326.1149; found 326.1153.
Supporting Information (see footnote on the first page of this arti-
cle) Spectroscopic data for 3a–o and 4.
2,5-Dibutyl-3-phenyletynylselenophene (3l): Yield: 0.161 g (94%).
1H NMR (200 MHz, CDCl3): δ = 7.55–7.45 (m, 2 H), 7.36–7.28
(m, 3 H), 6.88 (s, 1 H), 3.00 (t, J = 7.8 Hz, 2 H), 2.78 (t, J = 7.5 Hz,
2 H), 1.76–1.30 (m, 8 H), 0.99–0.89 (m, 6 H) ppm. 13C NMR
(100 MHz, CDCl3): δ = 155.2, 148.5, 131.3, 128.2, 128.1, 127.8,
123.8, 120.3, 90.1, 85.9, 34.5, 34.3, 32.2, 31.3, 22.2, 22.1, 13.8,
13.7 ppm. MS: m/z (%) = 343 (100), 266 (72), 242 (70), 211 (51),
183 (62), 155 (44), 129 (47). HRMS: calcd. for C20H24Se 344.1043;
found 344.1048.
Acknowledgments
We are grateful to Conselho Nacional de Desenvolvimento
Científico e Tecnológico, Coordenação de Aperfeiçoamento de Pes-
soal de Nível Superior (SAUX) and Fundação de Amparo à Pes-
quisa do Estado do Rio Grande do Sul for a fellowship and finan-
cial support.
4-(2,5-Di-p-methylphenylselenophen-3-yl)-2-methylbut-3-yn-2-ol
1
(3m): Yield: 0.184 g (94%). H NMR (200 MHz, CDCl3): δ = 7.71
(d, J = 8.3 Hz, 2 H), 7.44–7.40 (m, 3 H), 7.22–7.15 (m, 4 H), 2.38–
2.36 (m, 6 H), 1.99 (s, 1 H), 1.60 (s, 6 H) ppm. 13C NMR
(100 MHz, CDCl3): δ = 151.5, 147.0, 138.1, 137.9, 132.8, 132.7,
129.6, 129.2, 129.0, 127.8, 125.9, 119.4, 94.5, 79.7, 65.7, 31.3, 21.3,
21.2 ppm. MS: m/z (%) = 375 (100), 345 (47), 309 (78), 128 (58),
91 (57). HRMS calcd. for C23H22OSe 394.0836; found 394.0840.
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4-(2-Butyl-5-phenylselenophen-3-yl)-2-methylbut-3-yn-2-ol (3n):
1
Yield: 0.134 g (78%). H NMR (200 MHz, CDCl3): δ = 7.77–7.72
(m, 2 H), 7.40–7.25 (m, 3 H), 6.96 (s, 1 H), 2.81 (t, J = 7.5 Hz, 2
H), 2.02 (s, 1 H), 1.73–1.56 (m, 8 H), 1.41 (sext., J = 7.5 Hz, 2 H),
0.94 (t, J = 7.5 Hz, 3 H) ppm. 13C NMR (50 MHz, CDCl3): δ =
150.6, 150.4, 135.9, 130.7, 128.3, 127.9, 127.7, 118.4, 94.2, 79.8,
65.7, 34.2, 32.2, 31.2, 22.1, 13.8 ppm. MS: m/z (%) = 327 (100),
297 (52), 261 (56), 246 (33), 232 (21), 155 (45), 128 (42), 77 (34).
HRMS: calcd. for C19H22OSe 346.0836; found 346.0831.
4-[5-(1-Hydroxy-1-methylethyl)-2-phenylselenophen-3-yl]-2-meth-
ylbut-3-yn-2-ol (3o): Yield: 0.156 g (90%). 1H NMR (200 MHz,
CDCl3): δ = 7.76–7.71 (m, 2 H), 7.40–7.25 (m, 3 H), 7.05 (s, 1 H),
2.61 (s, 1 H), 2.46 (s, 1 H), 1.62 (s, 6 H), 1.55 (s, 6 H) ppm. 13C
NMR (100 MHz, CDCl3): δ = 159.6, 151.1, 135.7, 128.3, 127.95,
127.94, 127.8, 118.4, 94.1, 79.6, 72.7, 65.6, 31.9, 31.2 ppm. MS: m/z
(%) = 311 (100), 281 (72), 245 (45), 206 (31), 128 (56), 77 (21).
HRMS: calcd. for C18H20O2Se 348.0629; found 348.0624.
3-(2-Butyltellanylvinyl)-2,5-diphenylselenophene
(4):
Powered
NaOH (0.044g; 1.1 mmol) was added to a two-neck round-bot-
tomed flask, equipped with a reflux condenser, containing a solu-
tion of alkynylselenophene 3a (0.365g, 1.0 mmol) in dry toluene
(2 mL) under an argon atmosphere. The mixture was slowly heated
to reflux. The reaction mixture became dark brown and was heated
at reflux for 4 h. The resulting solution was cooled to room tem-
perature and a solution of dibutylditelluride (0.185g; 0.5 mmol) in
95% EtOH (10 mL) was added. NaBH4 (0.092g; 2.5 mmol) was
added with vigorous stirring and gas evolution was observed during
addition. The reaction mixture was stirred at reflux for 6 h, allowed
Eur. J. Org. Chem. 2008, 377–382
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
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D. Alves, J. S. dos Reis, C. Luchese, C. W. Nogueira, G. Zeni
FULL PAPER
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H. A. Stefani, Acc. Chem. Res. 2003, 36, 731–738; d) J. V. Com-
asseto, L. W. Ling, N. Petragnani, H. A. Stefani, Synthesis
1997, 373.
Received: July 28, 2007
Published Online: November 2, 2007
382
www.eurjoc.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2008, 377–382