Organylzinc Chalcogenolate Promoted Michael-Type Addition of α,β-Unsaturated Carbonyl Compounds

Article abstract of DOI:10.1002/ejoc.201301497

We present the chemo-, regio-, and stereoselective synthesis of vinyl chalcogenide compounds promoted by organylzinc chalcogenolates. In this protocol, reductive cleavage of diorganyl dichalcogenide bonds by the Zn/NH₄OH system led to organylzi

Full text of DOI:10.1002/ejoc.201301497

FULL PAPER
DOI: 10.1002/ejoc.201301497
Organylzinc Chalcogenolate Promoted Michael-Type Addition of
α,β-Unsaturated Carbonyl Compounds
Vanessa Lóren Nunes,[a] Ingryd Cristina de Oliveira,[a] and Olga Soares do Rêgo Barros*[a]
Keywords: Michael addition / Zinc / Chemoselectivity / Regioselectivity
We present the chemo-, regio-, and stereoselective synthesis
of vinyl chalcogenide compounds promoted by organylzinc
chalcogenolates. In this protocol, reductive cleavage of di-
organyl dichalcogenide bonds by the Zn/NH4OH system led
to organylzinc chalcogenolates. The reaction was performed
with propiolic acids and esters and afforded β-organochalco-
genacrylic acids and esters under mild basic conditions. The
stereochemistry corresponded to anti-Markovnikov addition
of the organyl chalcogenolate constituents across the triple
bond.
zinc, the preparation of zinc telurolate has remained unex-
plored. Realizing the importance of the development of en-
vironmentally benign protocols for the preparation of vinyl
chalcogenides by applying milder and inexpensive methods,
the goal of this study was the preparation β-organochalcog-
enacrylic acids and esters 3 through Michael-type addition
of various diorganyl dichalcogenides 1 to propiolic acids
Introduction
Organochalcogen compounds have emerged as impor-
tant reagents and intermediates in modern organic synthe-
ses in view of their chemo-, regio-, and stereoselectivity re-
actions[1] and their useful biological activities, as was re-
cently reviewed.[2] A chalcogen can be introduced in an or-
ganic substrate as an electrophile or a nucleophile under
mild experimental conditions.[3] After being introduced into
a substrate, the organochalcogen group can be easily re-
moved[4] or directly converted into different functional
groups.[5]
and esters
2 promoted by the Zn/NH4OH system
(Scheme 1).
The development of new methods for the efficient and
inexpensive introduction of a chalcogen group into organic
molecules with a highly reactive reagent has been explored.
In the last decade, several zinc systems, such as Zn/
MeCN,[6] Zn/AlCl3,[7] Zn/ZrCl4,[8] Zn/BMIM-BF4 (BMIM
=
1-butyl-3-methylimidazolium hexafluorophosphate),[9]
Scheme 1. General scheme.
Zn/CAN (CAN = ceric ammonium nitrate),[10] and Zn/
RuCl3,[11] have been employed to produce “in situ” zinc se-
lenolate through reductive cleavage of the Se–Se bond.
These selenolate anions can be easily introduced into or-
ganic substrates, primarily by addition to unsaturated or-
ganic compounds through hydroselenation reactions. In ad-
dition, treatment of electrophilic selenium species, such as
phenylselenyl halides, with zinc dust leads to air-stable zinc
selenolate compounds (PhSeZnX), which have shown nucle-
ophilic reactivity in water suspensions.[12] However, there
are few reports describing the preparation of thiolate anions
by the reductive cleavage of the S–S bond or through an
umpolung process on the electrophilic sulfur species.[10,13]
Additionally, despite the well-known reducing properties of
Results and Discussion
Our initial studies focused on the development of an op-
timized set of reactions to obtain β-selenoacrylic acids and
esters. For preliminary optimization of the reaction condi-
tions, we chose ethyl propiolate, diphenyl diselenide, and
zinc dust as the model system. We examined the reaction
behavior by changing solvents, temperatures, molar ratios,
and additives under a nitrogen atmosphere. The results of
these studies are shown in Table 1.
It is very important to select the proper solvent to readily
promote the insertion of zinc into the Se–Se bond. There-
fore, acetonitrile or an acetonitrile/water system is com-
monly used;[6] however, in our case, good yields of 3aa were
obtained in these solvents but with an unsatisfactory dia-
stereoselectivity even at reflux temperature. Other solvents
including toluene and CH2Cl2 at room temperature or un-
[a] Instituto de Química, Universidade Federal de Goiás,
Campus Samambaia, 74001-970 Goiânia Goiás, Brazil
E-mail: Olga_barros@ufg.br
http://labsim.quimica.ufg.br/
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201301497.
Eur. J. Org. Chem. 2014, 1525–1530
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V. Lóren Nunes, I. C. de Oliveira, O. Soares do Rêgo Barros
FULL PAPER
Table 1. Optimization of the reaction condition.
Table 2. Michael-type addition of α,β-unsaturated carbonyl com-
pounds promoted by organylzinc chalcogenolate.
Entry
Solvent
(2 mL)
Additive
(0.2 mL)
T
[°C]
Yield
[%][a]
1
2
3
4
5
6
7
8
9
10
CH3CN
CH3CN
CH2Cl2
toluene
THF
H2O
–
–
–
–
H2O
H2O
CH3COOH
HCl
82
82
45
110
65
65
65
100
100
100
80
n.r.
n.r.
n.r.
32
37
48
50
60
96
THF
1,4-dioxane
1,4-dioxane
1,4-dioxane
1,4-dioxane
NH4OH
[a] Yield of pure isolated product characterized by spectroscopic
methods; n.r. = no reaction.
der reflux were also ineffective, and the starting material
was recovered. Next, the use of 1,4-dioxane and THF as
the solvent was investigated; however, no improvement in
the yield or diastereoselectivity was observed. We also
evaluated the reaction by using 1,4-dioxane as the solvent
in the presence of a base (NH4OH) and a neutral (H2O)
or acid (HCl and EtOAc) medium. Through the control
experiments, we found that the use of 1,4-dioxane in base
medium (NH4OH) at the boiling point of the solvent
proved to be the best reaction conditions for obtaining the
desired product in good yield with high diastereoselectivity.
Thus, careful analysis of the optimized reaction revealed
that the best conditions for Michael addition to the α,β-
unsaturated ester were the use of zinc (1 mmol) in 1,4-diox-
ane (2 mL) with diphenyl diselenide (0.5 mmol), ethyl pro-
piolate (0.5 mmol), and NH4OH (0.2 mL). The reaction
mixture was heated at reflux for 24 h to afford products 3
with yields up of 96%. To demonstrate the efficiency of
this reaction, we explored the generality of our method and
extended the conditions to diphenyl disulfides, diphenyl and
dibutyl ditellurides, as well as to various functionalized α,β-
unsaturated acids and esters. The results are summarized in
Table 2.
Inspection of Table 2 shows that the Michael-type ad-
ditions worked well for a variety of propiolic acids and es-
ters with high regio- and stereoselectivity. The observed Z
stereochemistry preference is consistent with minimized
steric interactions between the carbonyl oxygen atom and
the chalcogen atom.[14,16] In general, terminal propiolic
acids and esters gave better yields than internal acids and
esters. However, the reaction performed with the use of di-
butyl ditelluride did not proceed well, which resulted in
considerable losses in the yields, most likely due to the in-
stability of these products during chromatographic purifica-
tion. To avoid this instability, the reaction was performed
[a] Phenyl propiolic acid (1 mmol). [b] 3Ј/gen according to ref.[16]
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Eur. J. Org. Chem. 2014, 1525–1530

Organylzinc Chalcogenolate Promoted Michael-Type Addition
by using diphenyl ditelluride, which gave the products in “in situ”. We concluded that our method works as both a
acceptable yields (Table 2, entries 8, 12, and 16). This set of one-pot synthetic procedure and if the zinc selenolate was
experiments demonstrated that stereochemical control de- previously prepared (Scheme 3). A more detailed study of
pends on the diorganyl dichalcogenide group. The Michael the crystal structure of the [(PhSe)2Zn] intermediate by X-
addition of zinc selenolates [(PhSe)2Zn] preferentially af- ray diffraction analysis is underway in our laboratory.
forded (Z)-β-acrylic selenides in a 10:1 ratio, whereas zinc
tellurolates [(RTe)2Zn] exclusively afforded (Z)-β-acrylic
acid tellurides, diastereoisomers 3ac and 3bc. Moreover, a
significant loss in stereoselectivity was observed with the
addition of zinc thiolates [(PhS)2Zn] to propiolic acids,
which afforded a mixture of (Z)- and (E)-β-acrylic sulfides
in a 3:2 ratio (Table 2, entries 6 and 10). We also observed
that internal propiolic acids with a phenyl group provided
Scheme 3. Reagents and conditions: (a) (PhSe)2Zn (1 equiv.), ethyl
propiolate (1 equiv.), 1,4-dioxane/NH4OH. (b) Zn0 (2 equiv.),
PhSeSePh (1 equiv.), ethyl propiolate (1 equiv.), 1,4-dioxane/
NH4OH.
the geminal regioisomer (Table 2, entries 13, 15, and 16).
To determine how to prepare exclusively the (Z)-β-acrylic
chalcogenide diastereoisomer, we investigated the reaction
mechanism in an attempt to explain the generation of the
mixture of the (Z)- and (E)-β-acrylic sulfides and selenides.
Bieber and co-workers[15] described the preparation of alkyl
phenyl selenides by using zinc dust in acetonitrile/water.
They reported that the formation of the products could be
explained by two different reaction mechanisms: a single-
electron transfer (SET) reaction to produce a radical species
if the reaction medium is basic and an ionic mechanism
under neutral conditions. Therefore, we performed the reac-
tions by using the radical inhibitor 2,2,6,6-tetramethylpiper-
idine-N-oxyl (TEMPO) under reaction conditions similar
to those previously described to investigate a radical hydro-
chalcogenation mechanism. The (Z)-β-acrylic selenide and
(Z)-β-acrylic thiolate diastereoisomers were obtained with
significant improvement in the stereoselectivity with a com-
parable yield (Scheme 2). On the basis of these results, we
deduced that the reaction proceeds through competing radi-
cal and ionic mechanisms.
Conclusions
In summary, we have developed a regio- and stereoselec-
tive protocol for the Michael-type addition of several propi-
olic acids and esters promoted by organylzinc chalcogenol-
ates by using either a one-pot synthesis or a previously pre-
pared reagent to afford the corresponding (Z)-β-acrylic
chalcogenides in moderate to excellent yields. In the pres-
ence of the TEMPO radical inhibitor, we produced (Z)-β-
acrylic chalcogenides with high diastereoselectivity. Efforts
to explore the detailed mechanism and extend the applica-
tions of the Zn/NH4OH system as a reaction partner in
other transformations are underway in our laboratory.
Experimental Section
General Remarks: All new compounds were characterized by 1H
1
NMR, 13C NMR, and IR spectroscopy and elemental analysis. H
NMR and 13C NMR spectra were obtained with a Bruker Avance
III 500 (500 MHz for 1H, 125 MHz for 13C) spectrometer. All spec-
tra were recorded in CDCl3, and the chemical shifts are given
in ppm with respect to tetramethylsilane as an internal standard.
Near-IR spectra were obtained with a Perkin–Elmer Precisely Spec-
trum 400 FTIR/FTFIR spectrometer. Column chromatography
was performed by using Merck silica gel (230–400 mesh). Thin-
layer chromatography (TLC) was performed by using Merck silica
gel GF254 (0.25 mm thickness). For visualization, TLC plates were
either placed under UV light or stained with iodine vapor or acidic
vanillin. Most reactions were monitored by TLC for disappearance
of the starting material. Elemental analyses were performed with
a Thermo scientific Flash 2000 Organic Elemental Analyzer. The
IUPAC names were obtained by using ChemDraw software, ver-
sion 8.0. Spectroscopic data of 3da, 3dc, and 3dd are in accord with
the data reported in ref.[16] Compounds 3ad, 3bc, 3cc, 3dc, and 3dd
were easily purified by column chromatography; however, they were
unstable and reliable elemental analysis could not be obtained.
Scheme 2. Michael addition of propiolic acid with TEMPO.
In another study, we investigated the formation of the
zinc selenolate intermediate through reductive cleavage of
the Se–Se bond by zinc. In this experiment, a mixture of
zinc dust, diphenyl diselenide, 1,4-dioxane, and NH4OH
was stirred at reflux temperature for 2 h until the yellow
solution became gray. Then, the solvent was evaporated un-
der reduced pressure to afford a gray powdered stable inter-
mediate. The Michael addition of ethyl propiolate pro-
moted by this previously prepared intermediate afforded
product 3 in the same yield and stereochemistry as the reac-
General Procedure for the Preparation of β-Acrylic Chalcogenides 3/
3Ј by a One-Pot Synthesis: In a Schlenk tube, a mixture of zinc
tion that proceeded through a zinc selenolate prepared dust (0.064 g, 1.0 mmol), diphenyl diselenide (0.157 g, 0.5 mmol),
Eur. J. Org. Chem. 2014, 1525–1530
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V. Lóren Nunes, I. C. de Oliveira, O. Soares do Rêgo Barros
FULL PAPER
ethyl propiolate (0.049 g, 0.5 mmol), and NH4OH (0.2 mL) was
suspended in 1,4-dioxane (2 mL). The reaction mixture was heated
at reflux for 24 h under a nitrogen atmosphere. Then, the reaction
was quenched with NH4Cl (10 mL), and the mixture was extracted
with EtOAc (2ϫ 10 mL). The organic layer was then dried with
Na2SO4. The solvent was evaporated under reduced pressure, and
the crude mixture was purified by silica gel column chromatog-
raphy (hexane/ethyl acetate, 7:3) to afford ethyl 3-(phenylselanyl)-
acrylate 3aa (0.123 g, 0.5 mmol, 97%) as a colorless oil. The yields
reported in Table 2 refer to the isolated products, and the Z/E ratios
were determined through NMR spectroscopy.
3-(Butyltellanyl)acrylic Acid (3bc): 1H NMR (500 MHz, CDCl3):
δ = 8.67 (d, J = 9.8 Hz, 1 H), 7.81 (d, J = 9.8 Hz, 0.2 H), 6.95 (d,
J = 9.8 Hz, 1 H), 6.36 (d, J = 9.8 Hz, 0.2 H), 2.60 (t, J = 7.6 Hz,
2 H), 1.82 (quint., J = 7.6 Hz, 2 H), 1.42 (sext, J = 7.5 Hz, 2 H),
0.93 (t, J = 7.5 Hz, 3 H) ppm. 13C NMR (125 MHz, CDCl3): δ =
172.77, 140.36, 122.63, 33.92, 24.96, 13.40, 9.82 ppm. IR (KBr): ν
˜
= 3440, 2958, 1727, 1463, 1288, 1124, 1073, 670 cm–1.
1
3-(Phenyltellanyl)acrylic Acid (3bd): H NMR (500 MHz, CDCl3):
δ = 8.86 (d, J = 16.5 Hz,0.1 H), 8.72 (d, J = 9.6 Hz, 1 H), 7.83–
7.81 (m, 2 H), 7.38–7.35 (m, 1 H), 7.31–7.28 (m, 2 H), 7.05 (d, J
= 9.6 Hz, 1 H), 6.15 (d, J = 16.5 Hz, 0.1 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 173.3, 145.0, 138.4, 129.6, 128.6, 122.2,
Ethyl 3-(Phenylselanyl)acrylate (3aa): 1H NMR (500 MHz,
CDCl3): δ = 8.12 (d, J = 15.4 Hz, 0.1 H), 7.73 (d, J = 9.6 Hz, 1
H), 7.60–7.58 (m, 2 H), 7.33–7.32 (m, 3 H), 6.34 (d, J = 9.6 Hz, 1
H), 5.85 (d, J = 15.4 Hz, 0.1 H), 4.25 (q, J = 7.2 Hz, 2 H), 4.13 (q,
J = 7.2 Hz, 0.3 H), 1.31 (t, J = 7.2 Hz, 3 H), 1.24 (t, J = 7.2 Hz,
0.3 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 167.2, 149.8, 134.8,
133.3, 132.9, 132.5, 129.7, 129.3, 128.2, 116.7, 60.5, 14.3 ppm. IR
119.7 ppm. IR (KBr): ν = 2960, 2629, 1650, 1549, 1424, 1237,
˜
730 cm–1. C9H8O2Te (275.76): calcd. C 39.20, H 2.92; found C
39.13, H 2.89.
3-(Phenylselanyl)but-2-enoic Acid (3ca): 1H NMR (500 MHz,
CDCl3): δ = 7.67–7.66 (m, 1 H), 7.66–7.65 (m, 1 H), 7.43–7.40 (m,
1 H), 7.37–7.34 (m, 2 H), 6.24 (q, J = 1.2 Hz, 1 H), 1.95 (d, J =
1.2 Hz, 3 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 171.52,
162.78, 137.49, 129.27, 129.14, 127.59, 114.00, 26.67 ppm. IR
(KBr): ν = 3437, 2924, 1664, 1567, 1245, 736 cm–1. C H O Se
˜
12 12
2
(267.19): calcd. C 51.78, H 4.74; found C 52.37, H 4.63.
Ethyl 3-(Phenylthio)acrylate (3ab): 1H NMR (500 MHz, CDCl3):
δ = 7.75 (d, J = 15.1 Hz, 0.2 H), 7.48–7.45 (m, 2 H), 7.38–7.32 (m,
3 H), 7.26 (d, J = 10.1 Hz, 1 H), 5.90 (d, J = 10.1 Hz, 1 H), 5.64
(d, J = 15.1 Hz, 0.2 H), 4.23 (q, J = 7.2 Hz, 2 H), 4.14 (q, J =
7.2 Hz, 0.4 H), 1.31 (t, J = 7.2 Hz, 3 H), 1.25 (t, J = 7.2 Hz, 0.6
H) ppm. 13C NMR (125 MHz, CDCl3): δ = 166.7, 165.4, 149.8,
146.9, 136.4, 133.1, 131.3, 129.8, 129.5, 128.4, 113.6, 60.5,
(KBr): ν = 3437, 2923, 1654, 1438, 1225, 694 cm–1. C H O Se
˜
10 10
2
(241.15): calcd. C 49.81, H 4.18; found C 51.81, H 4.29.
3-(Phenylthio)but-2-enoic Acid (3cb): 1H NMR (500 MHz, CDCl3):
δ = 7.55–7.53 (m, 1.4 H), 7.50–7.48 (m, 2.2 H), 7.45–7.36 (m, 5.4
H), 5.87 (q, J = 1.2 Hz,. 0.9 H), 5.20 (q, J = 1.1 Hz, 1.5 H), 2.43
(d, J = 1.1 Hz, 4.5 H), 1.84 (d, J = 1.2 Hz, 3 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 171.4, 170.8, 163.8, 162.1, 136.3, 135.7,
130.6, 130.3, 130.1, 129.8, 129.3, 111.4, 109.9, 25.7, 20.7 ppm. IR
14.5 ppm. IR (KBr): ν = 2981, 1699, 1165, 1569, 1025, 744,
˜
691 cm–1. C11H12O2S (208.27): calcd. C 63.43, H 5.81; found C
63.64, H 5.93.
(KBr): ν = 2922, 1673, 1597, 1442, 1233, 916, 751 cm–1. C H O S
˜
10 10
2
(194.25): calcd. C 61.83, H 5.19; found C 61.62, H 5.38.
Ethyl 3-(Butyltellanyl)acrylate (3ac): 1H NMR (500 MHz, CDCl3):
δ = 8.42 (d, J = 9.8 Hz, 1 H), 7.61 (d, J = 9.8 Hz, 0.2 H), 6.90 (d,
J = 9.8 Hz, 1 H), 6.28 (d, J = 9.8 Hz, 0.2 H), 4.23 (q, J = 7.2 Hz,
2.5 H), 2.58 (t, J = 7.6 Hz, 2 H), 1.81 (quint., J = 7.6 Hz, 2 H),
1.41 (sext, J = 7.6 Hz, 2.6 H), 1.3 (t, J = 7.2 Hz, 4.5 H), 0.92 (t, J
= 7.6 Hz, 4.3 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 168.84,
136.40, 123.55, 117.28, 60.87, 34.26, 25.23, 14.58, 13.64, 9.57 ppm.
3-(Butyltellanyl)but-2-enoic Acid (3cc): 1H NMR (500 MHz,
CDCl3): δ = 6.62 (q, J = 1.4 Hz, 0.5 H), 6.17 (q, J = 1.2 Hz, 1 H),
2.80 (t, J = 7.6 Hz, 2.4 H), 2.66 (t, J = 7.8 Hz, 1 H), 2.42 (d, J =
1.4 Hz, 1.4 H), 2.33 (d, J = 1.2 Hz, 2.8 H), 1.75 (quint., J = 7.8 Hz,
1.5 H), 1.66 (quint., J = 7.6 Hz, 2.3 H), 1.49–1.35 (m, 4.5 H), 0.94
(t, J = 7.8 Hz, 4.9 H), 0.89 (t, J = 7.8 Hz, 1.2 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 172.1, 171.3, 154.1, 152.3, 120.5, 114.7,
33.6, 32.0, 25.7, 25.5, 23.9, 23.3, 13.80, 13.7, 8.4, 6.4 ppm. IR
IR (KBr): ν = 3450, 2958, 1682, 1556, 1332, 1204, 803 cm–1.
˜
C9H16O2Te (283.82): calcd. C 38.09, H 5.68; found C 39.74, H 5.76.
(KBr): ν = 3435, 2959, 1652, 1650, 1463, 1288 cm–1.
˜
Ethyl 3-(Phenyltellanyl)acrylate (3ad): 1H NMR (500 MHz,
CDCl3): δ = 8.54 (d, J = 16.5 Hz, 0.1 H), 8.46 (d, J = 9.3 Hz, 1
H), 7.79–7.77 (m, 2 H), 7.33–7.23 (m, 3 H), 6.95 (d, J = 9.3 Hz, 1
H), 6.13 (d, J = 16.5 Hz, 0.1 H), 4.26 (q, J = 7.2 Hz, 2 H), 4.14 (q,
J = 7.2 Hz, 0.2 H), 1.31 (t, J = 7.2 Hz, 3 H), 1.23 (t, J = 7.1 Hz,
0.3 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 168.7, 140.4, 139.6,
137.9, 129.7, 129.1, 128.0, 122.3, 119.6, 60.8,14.2 ppm.
3-(Phenyltellanyl)but-2-enoic Acid (3cd): 1H NMR (500 MHz,
CDCl3): δ = 7.93–7.90 (m, 2 H), 7.42 (m, 1 H), 7.30 (m, 2 H), 6.69
(q, J = 1.2 Hz, 1 H), 2.10 (d, J = 1.2 Hz, 3 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 172.6, 156.7, 141.8, 129.5, 129.4, 119.6,
117.0, 29.0 ppm. IR (KBr): ν = 2979, 2602, 1646, 1560, 1434, 1224,
˜
737 cm–1. C10H10O2Te (289.79): calcd. C 41.45, H 3.48; found C
42.90, H 3.45.
1
3-(Phenylselanyl)acrylic Acid (3ba): H NMR (500 MHz, CDCl3):
(Z)-3-Phenyl-3-(phenylselanyl)acrylic Acid and 3-Phenyl-2-(phen-
ylselanyl)acrylic Acid (3da): 1H NMR (500 MHz, CDCl3): δ = 8.41
(s, 0.4 H), 7.75–7.77 (m, 1 H), 7.39–7.41 (m, 2 H), 7.19–7.24 (m, 3
H), 6.98–7.11 (m, 8 H), 6.38 (s, 1 H) ppm. 13C NMR (125 MHz,
CDCl3): δ = 171.69, 165.41, 149.36, 139.20, 136.53, 131.42, 130.98,
130.46, 129.50, 129.31, 128.77, 128.70, 128.53, 128.45, 128.28,
δ = 8.26 (d, J = 15.6 Hz, 0.1 H), 7.85 (d, J = 9.6 Hz, 1 H), 7.51–
7.53 (m, 2 H), 7.27 (d, J = 1.8 Hz, 2 H), 7.26 (d, J = 1.8 Hz, 1 H),
6.33 (d, J = 9.6 Hz, 1 H), 5.78 (d, J = 15.6 Hz, 0.1 H) ppm. 13C
NMR (125 MHz, CDCl3): δ = 172.5, 153.8, 153.7, 133.6, 133.5,
132.5, 129.6, 128.6, 116.5, 116.3 ppm. IR (KBr): ν = 3437, 2924,
˜
1664, 1567, 1245, 690 cm–1. C9H8O2Se (227.12): calcd. C 47.59, H
3.55; found C 48.80, H 3.52.
127.77, 127.32, 116.47 ppm. IR (KBr): ν = 3057, 2594, 2347, 1663,
˜
1558, 1209, 737, 689 cm–1. C15H12O2Se (303.22): calcd. C 59.42, H
3.99; found C 59.20, H 4.40.
3-(Phenylthio)acrylic Acid (3bb): 1H NMR (500 MHz, CDCl3): δ =
7.92 (d, J = 14.9 Hz, 1 H), 7.47–7.49 (m, 5 H), 7.41 (d, J = 10.2 Hz,
1.6 H), 7.32–7.39 (m, 5 H), 5.93 (d, J = 10.2 Hz, 1.6 H), 5.63 (d, J (Z)-3-Phenyl-2-(phenylthio)acrylic Acid and 3-Phenyl-3-(phenyl-
1
= 14.9 Hz, 1 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 171.6,
170.6, 152.9, 150.3, 135.8, 133.0, 131.1, 129.7, 129.4, 129.4
thio)acrylic Acid (3db): H NMR (500 MHz, CDCl3): δ = 9.6 (s, 1
H), 8.33 (s, 0.5 H), 7.18–7.15 (m, 4 H), 7.13–7.10 (m. 3 H), 7.07–
7.03 (m, 3 H) 6.13 (s, 1 H), 5.36 (s, 0.5 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 170.00, 162.41, 138.14, 134.14, 132.07,
128.4,114.4, 112.6 ppm. IR (KBr): ν = 3468, 2924, 1668, 1419,
˜
1244, 689 cm–1. C9H8O2S (180.22): calcd. C 59.98, H 4.47; found
C 60.28, H 4.32.
128.75, 128.60, 128.44, 127.91, 127.79, 115.22 ppm. IR (KBr): ν =
˜
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Eur. J. Org. Chem. 2014, 1525–1530

Organylzinc Chalcogenolate Promoted Michael-Type Addition
2601, 1664, 1561, 1412, 1312, 1211, 703 cm–1. C15H12O2S (256.32):
calcd. C 70.29, H 4.72; found C 99.71, H 4.53.
Acknowledgments
The authors thank the Conselho Nacional de Desenvolvimento
Científico e Tecnológico (CNPq) and Coordenação de Aper-
feiçoamento de Pessoal de Nível Superior (CAPES) for financial
support, and V. L. N. gratefully acknowledges CNPq for the award
of a scholarship.
(Z)-2-(Butyltellanyl)-3-phenylacrylic Acid and (Z)-3-(Butyltellanyl)-
3-phenylacrylic Acid (3dc): H NMR (500 MHz, CDCl3): δ = 8.25
1
(s, 0.1 H), 7.34–7.27 (m, 5 H), 7.24–7.18 (m, 3 H), 7.15–7.14 (m, 2
H), 6.60 (s, 1 H), 2.08 (t, J = 7.5 Hz, 2.0 H), 1.42 (quint., J =
7.5 Hz, 2.0 H), 1.12 (sext, J = 7.5 Hz. 2.0 H), 0.72 (t, J = 7.5 Hz, 3.0
H) ppm. 13C NMR (125 MHz, CDCl3): δ = 171.39, 156.65, 142.29,
128.46, 128.33, 127.46, 122.20, 33.40, 25.22, 13.40, 10.44 ppm. IR
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(KBr): ν = 2958, 1660, 1561, 1230, 702 cm–1. C H O Te (331.87):
˜
13 16
2
calcd. C 47.05, H 4.86; found C 42.11, H 4.16.
(Z)-3-(Phenyltellanyl)-3-phenylacrylic Acid and (Z)-3-Phenyl-2-
1
(phenyltellanyl)acrylic Acid (3dd): H NMR (500 MHz, CDCl3): δ
= 10.19 (s, 1.5 H), 8.39 (s, 1 H), 7.64–7.62 (m, 2 H), 7.50–7.48 (m,
2 H), 7.43–7.41 (m, 2 H), 7.34–7.33 (m, 3 H), 7.22–7.19 (m, 1 H),
7.14–7.11 (m, 2.6 H), 7.02–7.00 (m, 2 H), 6.97–6.94 (m, 2.4 H),
6.79 (s, 0.6 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 173.39,
160.25, 151.54, 140.99, 140.55, 138.11, 129.78, 129.35, 128.67,
128.56, 128.10, 128.07, 127.94, 127.46, 120.91, 119.10, 114.50,
111.85 ppm. IR (KBr): ν = 2977, 2594, 1652, 1558, 1477, 1212,
˜
738 cm–1.
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General Procedure for the Preparation of β-Acrylic Chalcogenides
3/3Ј Effected Under the (PhSe)2Zn Previously Prepared: In a
Schlenk tube, ethyl propiolate (0.049 g, 0.5 mmol) was mixed with
(PhSe)2Zn (0.189 g, 0.5 mmol) and 1,4-dioxane (2 mL), and the re-
action mixture was heated at reflux for 24 h under a nitrogen atmo-
sphere. Then, the reaction was quenched with NH4Cl (10 mL), and
the mixture was extracted with EtOAc (2ϫ 10 mL). The organic
layer was then dried with (Na2SO4). The solvent was evaporated
under reduced pressure, and the crude mixture was purified by sil-
ica gel column chromatography (hexane/ethyl acetate, 7:3) to afford
ethyl 3-(phenylselanyl)acrylate 3aa (0.123 g, 0.5 mmol, 97%) as a
colorless oil.
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General Procedure for the Preparation of (Z)-β-Acrylic Chalco-
genides Effected Under Radical Inhibitor (TEMPO) Conditions: In
a Schlenk tube, a mixture of zinc dust (0.064 g, 1.0 mmol), diphenyl
diselenide (0.157 g, 0.5 mmol), propiolic acid (0.035 g, 0.5 mmol),
NH4OH (0.2 mL), and TEMPO (0.078 g, 0.5 mmol) was suspended
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Procedure for the Preparation of (PhSe)2Zn: In a Schlenk tube, a
mixture of zinc dust (0.064 g, 1.0 mmol), diphenyl diselenide
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in air.
Supporting Information (see footnote on the first page of this arti-
cle): Experimental procedures, characterization data, and copies of
1
the H NMR and 13C NMR spectra of β-acrylic chalcogenides 3/
3Ј.
Eur. J. Org. Chem. 2014, 1525–1530
© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
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V. Lóren Nunes, I. C. de Oliveira, O. Soares do Rêgo Barros
FULL PAPER
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Received: October 2, 2013
Published Online: January 8, 2014
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Eur. J. Org. Chem. 2014, 1525–1530