Copper-mediated synthesis of α-trifluoromethylthio- and seleno-α,β-unsaturated carbonyl compounds

Article abstract of DOI:10.1016/j.tet.2013.11.093

A novel route to the synthesis of α-trifluoromethylthio- and seleno-α,β-unsaturated carbonyl compounds via a copper-mediated trifluoromethylthiolation/trifluoromethylselenolation of α-halo-α, β-unsaturated carbonyl substrates is reported.

Full text of DOI:10.1016/j.tet.2013.11.093

Tetrahedron 70 (2014) 672e677
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Copper-mediated synthesis of
a-trifluoromethylthio- and
seleno- -unsaturated carbonyl compounds
a,b
*
Peitao Zhu, Xing He, Xiaoqing Chen, Yi You, Yaofeng Yuan, Zhiqiang Weng
Department of Chemistry, Fuzhou University, Fujian 350108, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 6 October 2013
Received in revised form 18 November 2013
Accepted 25 November 2013
Available online 3 December 2013
A novel route to the synthesis of
via a copper-mediated trifluoromethylthiolation/trifluoromethylselenolation of a-halo-a,b-unsaturated
carbonyl substrates is reported.
a
-trifluoromethylthio- and seleno-a,b-unsaturated carbonyl compounds
Ó 2013 Elsevier Ltd. All rights reserved.
Keywords:
Trifluoromethylthiolation
Trifluoromethylselenolation
a
-Halo-a,b-unsaturated carbonyl
compounds
Copper reagent
1. Introduction
The results showed that the cross-coupling stereochemistry could be
altered by the gem-carbonyl groups in some cases. These procedures
a
,
b
-Unsaturated carbonyl compounds have served as versatile
provided practical access to a wide range of
unsaturated esters.
a-trifluoromethyl-a,b-
intermediates in countless syntheses of biologically active natural
products, pharmaceuticals, agrochemicals, and advanced mate-
Compared to the trifluoromethylate compounds, the CF3S-
substituted -unsaturated carbonyl species are even less well
rials.1 Particularly,
a
-trifluoromethyl-
a
,
b
-unsaturated carbonyl
a,b
compounds are important building blocks for preparing fluorine-
containing nucleosides,2 which have shown a broad spectrum of
antiviral and anticancer activity.3,4 Their unique properties stems
largely from the metabolic stability, lipophilicity, and electro-
negativity of fluorine group.5,6
known. For example, Harris reported that a free-radical addition of
trifluoromethanesulfenyl chloride to methyl acrylate with sub-
sequent elimination of hydrogen chloride gave a mixture of 2- and
3-trifluoromethylthioacrylate regioisomers.11 Wakselman and co-
workers reported the synthesis of 2-trifluoromethylthioacrylate
and its derivatives via the Knoevenagel condensation of ethyl
(trifluoromethylthio)acetate with aldehydes.12 However, these
reactions suffer serious limitations of using highly toxic and ex-
pensive reagents that preclude their practical use.
Despite the demonstrated pharmaceutical importance of
a-tri-
fluoromethyl-
a,b
-unsaturated carbonyl compounds,7 synthetic
methods for these species have been sporadically reported. For
example, Lang and co-workers reported that the reaction of methyl
2,2-dichloro-3,3,3-trifluoro-propionate with aldehydes followed by
Given the importance and high hydrophobicity parameter13 of
the trifluoromethylthio moiety in various biologically and phar-
maceutically active species,14e17 it is highly desirable and valuable
to develop a new, efficient, and safe approach to synthesize these
compounds.
acylation and reductive elimination afforded a-trifluoromethyl-a,b-
unsaturated esters with a 1:1 mixture of E and Z isomers.8 Qing and
co-workers developed copper-mediated trifluoromethylation of
a-bromo-a,b-unsaturated esters with FSO2CF2CO2Me to furnish the
corresponding
a
-trifluoromethyl-
a
,
b
-unsaturated esters with high E
On the basis of our success on development of copper-mediated
diastereostereoselectivity.2,9 Robins and co-workers described fur-
ther trifluoromethylation of E and Z isomers of bromo- and iodoal-
kenes by using (CF3)2Hg/Cu/DMA (DMA¼N,N-dimethylacetamide).10
trifluoromethylation18 and trifluoromethylthiolation,19 we envisaged
that an efficient approach for the synthesis of
and seleno- -unsaturated carbonyl compounds could be achieved
by trifluoromethylthiolation and trifluoromethylselenolation of
halo- -unsaturated carbonyl substrates using copper reagents.
Herein, we report our results on these reactions.
a-trifluoromethylthio-
a,b
a-
a,b
* Corresponding author. Tel./fax: þ86 59122866121; e-mail address: zweng@fzu.
edu.cn (Z. Weng).
0040-4020/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2013.11.093

P. Zhu et al. / Tetrahedron 70 (2014) 672e677
673
2. Results and discussion
As an initial experiment, we chose the reaction of (bpy)Cu(SCF3)
(2)19a with 2-bromo-3-phenylacrylaldehyde (1a) as the model re-
action to investigate the feasibility and efficiency of the new pro-
tocol (Table 1).
Scheme 1. Plausible reaction pathway for trifluoromethylthiolation of a-bromo-a,b-
unsaturated carbonyl compounds.
Table 1
Optimization of the trifluoromethylthiolation of 2-bromo-3-phenylacrylaldehydea
As shown in Table 2, the reactions of ketone substrates 1b and c
with (bpy)Cu(SCF3) (2) gave 3b and c in 62 and 61% yields, re-
spectively, and moderate E/Z ratios (entries 2, 3). Likewise, the
a-
bromo- -unsaturated esters 1deg could also be reactive under
a,b
the standard reaction conditions, leading to the corresponding
product 3deg in acceptable yields (53e69%; entries 4e7). The E
isomers of products 3 were generated as the major products. The
configurations of 3 were established based on the chemical shifts of
the alkenyl protons.2,9
Entry Solvent
Base
T (ꢀC) Time (h) Yield (%)b E:Z
1
CH3CN
d
d
d
d
d
d
d
d
d
d
d
d
d
110
110
110
110
80
24
24
24
24
24
24
24
24
24
24
24
24
16
24
24
24
24
31
2
2
22
0
19:1
d
2
DMF
3
DMSO
d
4
HMPA
d
Table 2
5
CH3OH
d
Trifluoromethylthiolation of
a-bromo-a,b-unsaturated carbonyl compounds 1 by
(bpy)Cu(SCF3) 2a
6
CH2Cl2
30
0
d
7
THF
80
11
46
37
28
47
65
58
70
59
64
34
10:1
10:1
8:1
8:1
9:1
6:1
7:1
10:1
6:1
8:1
8:1
8
Diglyme
110
110
110
110
140
140
140
140
9
Toluene
10
11
12
13
14
15
16
17
Xylene
CH3CN/xylene (1:9)
CH3CN/xylene (1:9)
CH3CN/xylene (1:9)
CH3CN/xylene (1:9) CsF
CH3CN/xylene (1:9) KF
Entry
1
a
-Bromo-
carbonyl compound 1
a
,
b
-unsaturated
Product
Yield E:Z
(%)b
CH3CN/xylene (1:9) K2CO3 140
CH3CN/xylene (1:9) NEt3 140
65
62
10:1
a
Reaction conditions: 1a (0.025 mmol), 2 (0.050 mmol), base (0.050 mmol),
solvent (1.0 mL), under N2 atmosphere.
b
The yield was determined by 19F NMR spectroscopy with PhOCF3 as internal
standard.
2
3
3:2
2:1
1:1
5:3
Treatment of 1a (0.025 mmol) with 2 (0.050 mmol) in 1.0 mL of
CH3CN at 110 ꢀC under N2 atmosphere provided 3-phenyl-2-(tri-
fluoromethylthio)acrylaldehyde (3a) in 31% yield with an E/Z ratio
of 19:1 (19F NMR) (Table 1, entry 1).
61
53
59
With the hypothesis that the reaction might occur more effi-
ciently in other types of medium, we evaluated the effect of the
type of solvent on the reaction. We found that the polar aprotic
solvents DMF, DMSO, HMPA (entries 2e4) and the protic solvent
methanol (entry 5) and CH2Cl2 (entry 6) retarded the reaction. The
use of THF as solvents provided product in inferior yield (entry 7).
Performing the reactions in diglyme (entry 8), or in nonpolar sol-
vents, such as toluene and xylene, or in a CH3CN/xylene (1:9) sol-
vents mixture resulted in comparable yields and stereoselectivities
(entries 9e11).
To further elucidate the influence of various trifluoromethyl
thiolation parameters, the reaction temperature and time were also
evaluated. Gratifyingly, increasing the temperature from 110 to
140 ꢀC resulted in increasing yields of the expected product to 65%
(entry 12). Shortening the reaction time to 16 h led to a decrease of
yield to 58% (entry 13).
Notably, the presence of 2 equiv of CsF facilitated this trans-
formation. The role of CsF in the reaction might be to facilitate the
formation of active intermediate A as shown in Scheme 1. Thus, the
optimization study concluded that the best yields (70%) with a re-
spectable E/Z ratio (10:1) were obtained with the combining CH3CN
and xylene (1:9) as solvent at 140 ꢀC for 24 h (entry 14). Replacing
CsF by KF, K2CO3 or NEt3 diminished the yield of 3a considerably
(entries 15e17).
4
5
6
56
69
5:3
5:2
7
a
Reaction conditions: 1 (0.25 mmol), 2 (0.50 mmol), MeCN/xylene (1:9) (2.0 mL),
CsF (0.50 mmol), 140 ꢀC, 24 h.
b
Isolated yields.
With the optimal reaction conditions available, the generality
for the trifluoromethylthiolation was subsequently investigated
After the successful application of copper-mediated synthesis of
a
-trifluoromethylthio-
a,b-unsaturated carbonyl compounds, we
with various a-halo-a,b-unsaturated carbonyl substrates.
were interested in whether our copper reagent could also be

674
P. Zhu et al. / Tetrahedron 70 (2014) 672e677
effective for preparation of their selenium analogs. Gratifyingly,
treatment of 1 with 1 equiv of [(bpy)Cu(SeCF3)]2 (4)20 in MeCN/
xylene (1:9) at 140 ꢀC for 24 h generated E and Z isomeric mixture of
the desired trifluoromethylselenolate products 5aeg in good yields
shifts were reported in parts per million (ppm) downfield from
tetramethylsilane and 19F NMR chemical shifts were determined
relative to CFCl3 as the external standard and low field is positive.
Coupling constants (J) are reported in Hertz (Hz). The residual
solvent peak was used as an internal reference: 1H NMR (chloro-
(71e88%; Table 3). In general, the yields of
a-trifluoromethylseleno-
a
,b
-unsaturated carbonyl compounds are higher than those of
form d d 77.0). The following
7.26) and 13C NMR (chloroform
sulfur analogs, presumably due to the stronger nucleophilicity of
SeCF3e. Again, the major products of 5 were the E-isomers.
abbreviations were used to explain the multiplicities: s¼singlet,
d¼doublet, t¼triplet, q¼quartet, m¼multiplet, br¼broad. HRMS
were obtained on Waters GCT-TOF at the Shanghai Institute of Or-
ganic Chemistry. (bpy)Cu(SCF3),19a [(bpy)Cu(SeCF3)]2,20 and
a-
Table 3
bromo-a,b
-unsaturated carbonyl substrates2,23 were prepared
Trifluoromethylselenolation of
a-bromo-a,b-unsaturated carbonyl compounds 1 by
[(bpy)Cu(SeCF3)]2 4a,b
according to the published procedures. Other reagents were re-
ceived from commercial sources. Solvents were freshly dried and
degassed according to the purification handbook Purification of
Laboratory Chemicals prior to use. Column chromatography purifi-
cations were performed by flash chromatography using Merck
silica gel 60.
4.2. General procedure for trifluoromethylthiolation/tri-
fluoromethylselenolation of
a-bromo-a,b-unsaturated car-
bonyl compounds with (bpy)Cu(SCF3)/[(bpy)Cu(SeCF3)]2
a
-Bromo-a,b-unsaturated carbonyl compounds 1 (0.25 mmol),
[(bpy)Cu(SCF3)] (160 mg, 0.50 mmol, 2 equiv) or [(bpy)Cu(SeCF3)]2
(184 mg, 0.25 mmol, 1 equiv), CsF (76 mg, 0.50 mmol, 2 equiv) and
CH3CN/xylene (1:9; 2 mL) were added to a reaction tube equipped
with a stir bar. The mixture was stirred at 140 ꢀC for 24 h. The re-
action mixture was filtered through a pad of Celite. The filtrate was
added water (3ꢁ10 mL) at 0 ꢀC. The resulting mixture was extracted
with Et2O (3ꢁ15 mL), and the combined organic layers was washed
with water, and then dried over MgSO4. The solvent was removed
by rotary evaporation in an ice bath and the resulting product was
purified by column chromatography on silica gel with pentane/
CH2Cl2.
A plausible reaction pathway, adapted from the mechanistic
studies performed on the copper-mediated trifluoromethylthiolation
of aryl halides,19a is shown in Scheme 1. The first step involves
4. 2.1. 3-Phenyl-2-(tr ifluoromethylthio)acrylaldehyde
(3a). Following the general procedure and workup, 3a was isolated
as a light-yellow solid (38 mg, 65% yield).
the oxidative addition of the
a-bromo-a,b-unsaturated carbonyl
E-Isomer 3a: Mp 59e61 ꢀC. Rf (7% CH2Cl2/n-pentane) 0.090. 1H
compounds to (bpy)Cu(SCF3) (2) to form a copper(III) species A.21
The subsequent reductive elimination from A affords the tri-
fluoromethylthiolated product together with (bpy)CuBr. Additionally,
the higher E-isomer product selectivity indicated that gem-carbonyl
NMR (400 MHz, CDCl3)
2H), 7.59e7.49 (m, 3H). 19F NMR (376 MHz, CDCl3)
13C NMR (101 MHz, CDCl3)
189.9 (s), 158.7 (s), 132.6 (s), 132.5 (s),
d
9.70 (s, 1H), 8.11 (s, 1H), 8.05 (d, J¼7.1 Hz,
d
ꢂ39.82 (s, 3F).
d
132.1 (s),129.0 (s),128.9 (q, J¼310.8 Hz) 124.3 (d, J¼1.5 Hz). IR (KBr):
3064, 3032, 2962, 2929, 2848, 1695, 1593, 1573, 1450, 1163, 1095,
1050, 760, 690 cmꢂ1. GCeMS m/z 231 (MþꢂH). HRMS (EI) calcd for
groups in
a-bromo-a,b-unsaturated carbonyl compounds 1 can
alter trifluoromethylthiolation or trifluoromethylselenolation ste-
reochemistry. The copper allenoates species10,22 could be involved in
the formation of products with inverted configurations.
C10H7F3OS: 232.0170; Found: 232.0171.
4.2.2. 1,3-Diphenyl-2-(trifluoromethylthio)prop-2-en-1-one
(3b). Following the general procedure and workup, 3b was isolated
as a yellow oil (48 mg, 62% yield).
3. Conclusions
E-Isomer 3b: Rf (7% CH2Cl2/n-pentane) 0.020. 1H NMR
In summary, an efficient method for the preparation of
fluoromethylthio- and seleno- -unsaturated carbonyl com-
pounds have been developed. The trifluoromethylthiolation/
trifluoromethylselenolation of -bromo- -unsaturated carbonyl
substrates with copper reagents give the corresponding aldehyde,
ketone, and ester products in moderate to good yields. Current
efforts are focused on expanding the scope of this methodology to
other classes of substrates.
a-tri-
a,b
(400 MHz, CDCl3)
d
ppm 7.90 (d, J¼7.6 Hz, 2H), 7.81e7.78 (m, 2H),
7.74 (s, 1H), 7.65 (t, J¼7.4 Hz, 1H), 7.58e7.46 (m, 5H). 19F NMR
ppm ꢂ39.81 (s, 3F). 13C NMR (101 MHz,
a
a,b
(376 MHz, CDCl3)
d
CDCl3)
d ppm 193.8 (s), 150.9 (s), 136.4 (s), 133.1 (s), 133.1 (s),
130.9 (s), 130.9 (s), 129.9 (s), 129.2 (q, J¼310.4 Hz), 128.7 (s), 128.7
(s), 125.4 (q, J¼2.0 Hz).
Z-Isomer 3b: Rf (7% CH2Cl2/n-pentane) 0.080. 1H NMR (400 MHz,
CDCl3)
d
ppm 7.89 (d, J¼8.0 Hz, 2H), 7.71 (s, 1H), 7.52 (t, J¼7.7 Hz,
4. Experimental
1H), 7.38 (t, J¼7.7 Hz, 2H), 7.28e7.19 (m, 5H). 19F NMR (376 MHz,
CDCl3)
d
ppm ꢂ40.86 (s, 3F). 13C NMR (101 MHz, CDCl3)
d ppm 194.0
4.1. General experimental
(s), 147.7 (d, J¼1.0 Hz), 134.6 (s), 133.9 (s), 133.6 (s), 130.1 (s), 129.6
(s), 129.3 (s), 129.1 (q, J¼310.3 Hz), 128.7 (s), 128.6 (s), 123.1 (d,
J¼1.8 Hz). IR (KBr): 3064, 3027, 2958, 2929, 2848, 1667, 1597, 1446,
1266, 1225, 1156, 1111, 1021, 756, 694 cmꢂ1. GCeMS m/z 307
1H NMR, 19F NMR, and 13C NMR spectra were recorded using
Bruker AVIII 400 spectrometer. 1H NMR and 13C NMR chemical

P. Zhu et al. / Tetrahedron 70 (2014) 672e677
675
(MþꢂH). HRMS (EI) calcd for C16H11F3OS: 308.0483; Found:
5.18e5.07 (m, 1H), 1.20 (d, J¼6.3 Hz, 6H). 19F NMR (376 MHz, CDCl3)
308.0486.
d
ꢂ42.10 (s, 3F). 13C NMR (101 MHz, CDCl3)
d ppm 165.7 (s), 149.2 (q,
J¼1.0 Hz), 134.0 (s), 131.3 (s), 129.2 (d, J¼310.1 Hz), 128.9 (s), 128.5
(s), 118.6 (q, J¼2.1 Hz), 70.1 (s), 21.2 (s). IR (KBr): 3064, 3027, 2987,
4.2.3. 1-Phenyl-3-p-tolyl-2-(trifluoromethylthio)prop-2-en-1-one
(3c). Following the general procedure and workup, 3c was isolated
as a yellow oil (49 mg, 61%).
2925, 2855, 1728, 1597, 1454, 1266, 1229, 1107, 751, 694 cmꢂ1
.
GCeMS m/z 289 (MþꢂH). HRMS (EI) calcd for C13H13F3O2S:
E-Isomer 3c: Rf (7% CH2Cl2/n-pentane) 0.040. 1H NMR (400 MHz,
290.0588; Found: 290.0593.
CDCl3)
d
ppm 7.87 (d, J¼8.1 Hz, 2H), 7.75 (s, 1H), 7.73 (s, 2H), 7.64 (t,
Z-Isomer 3f: 1H NMR (400 MHz, CDCl3)
d ppm 8.39 (s, 1H),
J¼7.4 Hz, 1H), 7.53 (t, J¼7.6 Hz, 2H), 7.30 (s, 1H), 7.28 (s, 1H), 2.44 (s,
7.90e7.82 (m, 2H) 7.50e7.44 (m, 3H), 5.26e5.17 (m, 1H), 1.39 (d,
3H). 19F NMR (376 MHz, CDCl3)
(101 MHz, CDCl3)
d
ppm ꢂ39.99 (s, 3F). 13C NMR
J¼6.3 Hz, 6H). 19F NMR (376 MHz, CDCl3)
d
ppm ꢂ40.74 (s, 3F). 13
C
d
ppm 194.0 (s), 151.5 (s), 141.9 (s), 136.7 (s), 132.9
NMR (101 MHz, CDCl3)
d
ppm 165.0 (s), 153.1 (q, J¼1.2 Hz), 133.3 (s),
(s), 131.2 (s), 130.3 (s), 129.8 (s), 129.5 (s), 129.3 (q, J¼310.3 Hz),
131.0 (s), 130.0 (s), 129.1 (d, J¼310.6 Hz), 128.6 (s), 116.9 (d,
128.6 (s), 124.2e123.5 (m), 21.6 (s).
J¼2.2 Hz), 70.3 (s), 21.7 (s).
Z-Isomer 3c: Rf (7% CH2Cl2/n-pentane) 0.13. 1H NMR (400 MHz,
CDCl3)
d
ppm 7.90 (d, J¼8.0 Hz, 2H), 7.66 (s, 1H), 7.53 (t, J¼7.6 Hz,
4.2.7. Methyl 3-(4-methoxyphenyl)-2-(trifluoromethylthio)acrylate
(3g). Following the general procedure and workup, 3g was isolated
as a yellow oil (51 mg, 69% yield).
1H), 7.39 (t, J¼7.6 Hz, 2H), 7.16 (d, J¼8.0 Hz, 2H), 7.01 (d, J¼8.0 Hz,
2H), 2.26 (s, 3H). 19F NMR (376 MHz, CDCl3)
NMR (101 MHz, CDCl3)
d
ꢂ41.05 (s, 3F). 13C
d
ppm 194.3 (s), 147.9 (s), 140.6 (s), 134.6 (s),
E-Isomer 3g: Rf (5% CH2Cl2/n-pentane) 0.040. 1H NMR
133.8 (s), 130.8 (d, J¼15.0 Hz), 129.6 (s), 129.4 (s), 129.3 (s), 129.2 (q,
J¼310.4 Hz), 128.7 (s), 121.7 (q, J¼1.6 Hz), 21.3 (s). IR (KBr): 3060,
3027, 2962, 2921, 2848, 1667, 1597, 1450, 1234, 1160, 1107, 1017, 805,
(400 MHz, CDCl3)
d
ppm 7.49 (s, 1H), 7.41 (d, J¼8.8 Hz, 2H), 6.91
(d, J¼8.8 Hz, 2H), 3.86 (s, 3H), 3.83 (s, 3H). 19F NMR (376 MHz,
CDCl3)
d
ppm ꢂ42.88 (s, 3F). 13C NMR (101 MHz, CDCl3)
d ppm
690 cmꢂ1
.
GCeMS m/z 321 (MþꢂH). HRMS (EI) calcd for
166.9 (s), 161.5 (s), 151.0 (d, J¼0.9 Hz), 134.2 (s), 131.4 (s), 129.2 (q,
J¼310.1 Hz), 126.3 (s), 114.1 (s), 55.4 (s), 52.8 (s). IR (KBr): 3011,
2954, 2933, 2844, 1728, 1605, 1511, 1462, 1438, 1311, 1262, 1225,
1171, 1111, 1033, 829, 756, 547, 527 cmꢂ1. GCeMS m/z 291
(MþꢂH). HRMS (EI) calcd for C12H11F3O3S: 292.0381; Found:
292.0385.
C
17H13F3OS: 322.0639; Found: 322.0641.
4.2.4. Methyl
3-phenyl-2-(trifluoromethylthio)acrylate
(3d). Following the general procedure and workup, 3d was isolated
as an orange-red oil (35 mg, 53% yield).
E-Isomer 3d: Rf (10% CH2Cl2/n-pentane) 0.26. 1H NMR (400 MHz,
Z-Isomer 3g: Spectral parameters for the Z isomer were ob-
tained on an enriched chromatographic fraction still containing
CDCl3)
(376 MHz, CDCl3)
d
ppm 7.56 (s, 1H), 7.44e7.35 (m, 5H), 3.80 (s, 3H). 19F NMR
d
ppm ꢂ42.40 (s, 3F). 13C NMR (101 MHz, CDCl3)
the E-isomer. 1H NMR (400 MHz, CDCl3)
d ppm 8.38 (s, 1H), 8.00
d
166.6 (s), 150.4 (d, J¼1.0 Hz), 133.8 (s), 130.3 (s), 129.1 (q,
(d, J¼8.9 Hz, 2H), 6.98 (d, J¼8.9 Hz, 2H), 3.92 (s, 3H), 3.90 (s, 3H).
J¼310.1 Hz), 128.9 (s), 128.6 (s), 117.4 (q, J¼2.2 Hz), 52.9 (s). IR (KBr):
3064, 3032, 2962, 2925, 2851,1724,1597,1577,1495,1454,1261,1208,
1159, 1133, 1105, 1033, 800, 772, 686 cmꢂ1. GCeMS m/z 261 (MþꢂH).
HRMS (EI) calcd for C11H9F3O2S: 262.0275; Found: 262.0273.
Z-Isomer 3d: Rf (10% CH2Cl2/n-pentane) 0.20. 1H NMR
19F NMR (376 MHz, CDCl3)
(101 MHz, CDCl3)
d
ppm ꢂ41.33 (s, 3F). 13C NMR
d
ppm 166.5 (s), 162.4 (s), 153.6 (s), 134.2 (s),
129.2 (q, J¼310.8 Hz), 125.8 (s), 114.2 (s), 113.9 (q, J¼2.5 Hz), 55.4
(s), 53.2 (s).
(400 MHz, CDCl3)
3H), 3.94 (s, 3H). 19F NMR (376 MHz, CDCl3)
NMR (101 MHz, CDCl3)
131.4 (s), 131.3 (s), 129.0 (q, J¼310.6 Hz), 128.6 (s), 116.0 (q,
J¼2.0 Hz), 53.3 (s).
d
8.43 (s, 1H), 7.97e7.79 (m, 2H), 7.58e7.39 (m,
4.2.8. 3-Phenyl-2-(trifluoromethylselanyl)acrylaldehyde
(5a). Following the general procedure and workup, 5a was isolated
as a yellow solid (56 mg, 80% yield).
d
ꢂ40.97 (s, 3F). 13
C
d
166.0 (s), 153.9 (d, J¼0.8 Hz), 133.1 (s),
E-Isomer 5a: Mp 64e66 ꢀC. Rf (20% CH2Cl2/n-pentane) 0.17. 1H
NMR (400 MHz, CDCl3)
d ppm 9.63 (s, 1H), 8.16 (s, 1H), 7.91 (d,
J¼7.7 Hz, 2H), 7.59e7.42 (m, 3H). 19F NMR (376 MHz, CDCl3)
4.2.5. Ethyl 3-phenyl-2-(trifluoromethylthio)acrylate (3e).12 Following
the general procedure and workup, 3e was isolated as a yellow oil
(41 mg, 59% yield).
d
ppm ꢂ32.73 (s, 3F). 13C NMR (101 MHz, CDCl3)
d ppm 190.1 (s),
158.7 (s), 133.3 (s), 132.1 (s), 131.5 (s), 128.8 (s), 126.1 (q,
J¼1.0 Hz), 121.7 (q, J¼334.9 Hz). IR (KBr): 3064, 3027, 2958, 2925,
2851, 1695, 1593, 1572, 1454, 1143, 1091, 764, 686 cmꢂ1. GCeMS
m/z 279 (Mþ). HRMS (EI) calcd for C10H7F3O74Se: 273.9674;
Found: 273.9669.
E-Isomer 3e: Rf (7% CH2Cl2/n-pentane) 0.090. 1H NMR (400 MHz,
CDCl3)
d
ppm 7.55 (s, 1H), 7.41e7.38 (m, 5H), 4.27 (q, J¼7.1 Hz, 2H),
1.23 (t, J¼7.1 Hz, 3H). 19F NMR (376 MHz, CDCl3)
d
ppm ꢂ42.25 (s,
3F). 13C NMR (101 MHz, CDCl3)
d
ppm 166.1 (s), 149.9 (q, J¼1.0 Hz),
133.9 (s), 130.2 (s), 129.1 (d, J¼310.2 Hz), 128.9 (s), 128.5 (s), 118.0 (d,
J¼2.2 Hz), 62.1 (s), 13.6 (s). IR (KBr): 3064, 3031, 2958, 2929, 2851,
4.2.9. 1,3-Diphenyl-2-(trifluoromethylselanyl)prop-2-en-1-one
(5b). Following the general procedure and workup, 5b was isolated
as a yellow oil (66 mg, 74% yield).
1728, 1597, 1450, 1372, 1262, 1221, 1159, 1111, 1037, 756, 690 cmꢂ1
.
GCeMS m/z 275 (MþꢂH).
E-Isomer 5b: Rf (10% Et2O/n-pentane) 0.41. 1H NMR (400 MHz,
Z-Isomer 3e: Rf (7% CH2Cl2/n-pentane) 0.040. 1H NMR (400 MHz,
CDCl3)
d
7.92 (d, J¼7.2 Hz, 2H), 7.76 (s, 1H), 7.66e7.61 (m, 3H), 7.54
CDCl3)
d
ppm 8.42 (s, 1H), 7.89e7.86 (m, 2H), 7.49e7.44 (m, 3H),
(t, J¼7.7 Hz, 2H), 7.50e7.43 (m, 3H). 19F NMR (376 MHz, CDCl3)
4.39 (q, J¼7.1 Hz, 2H), 1.41 (t, J¼7.1 Hz, 3H). 19F NMR (376 MHz,
d
ppm ꢂ32.93 (s, 3F). 13C NMR (101 MHz, CDCl3)
d ppm 194.0 (s),
CDCl3)
d
ppm ꢂ40.82 (s, 3F). 13C NMR (101 MHz, CDCl3)
d
ppm 165.5
149.4 (d, J¼0.7 Hz), 136.4 (s), 134.1 (s), 133.1 (s), 130.5 (s), 130.2 (s),
130.0 (s), 128.7 (s), 128.6 (s), 126.8 (q, J¼1.5 Hz), 122.1 (q,
J¼334.6 Hz).
(s), 153.4 (d, J¼1.0 Hz), 133.2 (s), 131.3 (s), 130.3 (s), 128.6 (s), 116.5
(s), 62.5 (s), 14.1 (s).
Z-Isomer 5b: Rf (10% Et2O/n-pentane) 0.52. 1H NMR (400 MHz,
4.2.6. Isopropyl
3-phenyl-2-(trifluoromethylthio)acrylate
CDCl3)
d
ppm 7.89 (d, J¼7.4 Hz, 2H), 7.75 (s, 1H), 7.51 (t, J¼7.4 Hz,
(3f). Following the general procedure and workup, 3f was isolated
as a yellow oil (41 mg, 56% yield).
1H), 7.38 (t, J¼7.8 Hz, 2H), 7.27e7.17 (m, 5H). 19F NMR (376 MHz,
CDCl3)
d
ppm ꢂ34.23 (s, 3F). 13C NMR (101 MHz, CDCl3)
d 194.8 (s),
E-Isomer 3f: Spectral parameters for the E isomer were obtained
on an enriched chromatographic fraction still containing the Z-
147.2 (s), 134.3 (s), 133.8 (s), 129.8 (s), 129.6 (s), 129.2 (s), 128.7 (s),
128.6 (s), 122.3 (d, J¼334.4 Hz), 122.1 (d, J¼0.8 Hz). IR (KBr): 3060,
isomer. 1H NMR (400 MHz, CDCl3)
d
ppm 7.51 (s, 1H), 7.39 (s, 5H),
3027, 2917, 2848, 1667, 1593, 1446, 1229, 1140, 1095, 760, 694 cmꢂ1
.

676
P. Zhu et al. / Tetrahedron 70 (2014) 672e677
GCeMS m/z 355 (Mþ). HRMS (EI) calcd for C16H11F3O74Se:
fraction still containing the Z-isomer. 1H NMR (400 MHz, CDCl3)
349.9987; Found: 349.9988.
d
ppm 7.55 (s, 1H), 7.39 (s, 5H), 5.19e5.06 (m, 1H), 1.21 (d, J¼6.3 Hz,
6H). 19F NMR (376 MHz, CDCl3)
(101 MHz, CDCl3)
d
ppm ꢂ35.18 (s, 3F). 13C NMR
4.2.10. 1-Phenyl-3-p-tolyl-2-(trifluoromethylselanyl)prop-2-en-1-
one (5c). Following the general procedure and workup, 5c was
isolated as a yellow oil (82 mg, 88%).
d
ppm 166.6 (s), 148.5 (q, J¼1.1 Hz),134.3 (s),130.6
(s), 128.7 (s), 128.5 (s), 122.3 (q, J¼334.4 Hz), 116.7 (q, J¼1.4 Hz), 70.0
(s), 21.2 (s). IR (KBr): 3060, 3023, 2983, 2929,1720, 1605,1454, 1373,
1266, 1225, 1139, 1095, 1005, 739, 690 cmꢂ1. GCeMS m/z 338
(MþþH). HRMS (EI) calcd for C13H13F3O724Se: 332.0092; Found:
332.0089.
E-Isomer 5c: Rf (2.5% Et2O/n-pentane) 0.23. 1H NMR (400 MHz,
CDCl3)
d
ppm 7.90 (d, J¼7.3 Hz, 2H), 7.74 (s, 1H), 7.67e7.60 (m, 1H),
7.60e7.49 (m, 5H), 7.27 (s, 1H), 2.43 (s, 3H). 19F NMR (376 MHz,
CDCl3)
d
ppm ꢂ33.08 (s, 3F). 13C NMR (101 MHz, CDCl3)
d
ppm
Z-Isomer 5f: Rf (1% Et2O/n-pentane) 0.22. 1H NMR (400 MHz,
194.2 (s), 149.9 (s), 141.3 (s), 136.6 (s), 132.9 (s), 130.5 (s), 129.9 (s),
129.3 (s), 128.6 (s), 128.5 (s), 125.6 (d, J¼1.4 Hz), 122.1 (q,
J¼334.8 Hz), 21.5 (s).
CDCl3)
d
ppm 8.41 (s, 1H), 7.67 (dd, J¼6.6, 2.9 Hz, 2H), 7.48e7.43 (m,
3H), 5.26e5.16 (m, 1H), 1.39 (d, J¼6.3 Hz, 6H). 19F NMR (376 MHz,
CDCl3)
d
ppm ꢂ33.92 (s, 3F). 13C NMR (101 MHz, CDCl3)
d ppm 165.0
Z-Isomer 5c: Rf (2.5% Et2O/n-pentane) 0.41. 1H NMR (400 MHz,
(s), 151.7 (dd, J¼2.0, 0.9 Hz), 134.6 (s), 130.4 (s), 129.8 (s), 128.4 (s),
CDCl3)
1H), 7.39 (t, J¼7.6 Hz, 2H), 7.15 (d, J¼8.1 Hz, 2H), 7.01 (d, J¼8.1 Hz,
2H), 2.26 (s, 3H). 19F NMR (376 MHz, CDCl3)
ppm ꢂ34.38 (s, 3F).
13C NMR (101 MHz, CDCl3)
ppm 195.0 (s), 147.4 (s), 140.3 (s), 134.4
d
ppm 7.91 (d, J¼7.2 Hz, 2H), 7.71 (s, 1H), 7.52 (t, J¼7.6 Hz,
121.9 (d, J¼334.8 Hz), 117.7 (dd, J¼2.8, 1.4 Hz), 70.4 (s), 21.6 (s).
d
4.2.14. Methyl 3-(4-methoxyphenyl)-2-(trifluoromethylselanyl)acry-
late (5g). Following the general procedure and workup, 5g was
isolated as a yellow oil (70 mg, 82% yield).
d
(s), 133.8 (s), 131.5 (s), 129.6 (s), 129.4 (s), 129.3 (s), 128.7 (s), 122.4
(q, J¼334.7 Hz), 120.7 (d, J¼1.0 Hz), 21.3 (s). IR (KBr): 3060, 3032,
2921, 2852, 1667, 1597, 1511, 1446, 1225, 1135, 1099, 1017, 812,
E-Isomer 5g: Rf (1% Et2O/n-pentane) 0.11. 1H NMR (400 MHz,
CDCl3)
d
ppm 7.53 (s, 1H), 7.37 (d, J¼8.8 Hz, 2H), 6.91 (d, J¼8.8 Hz,
690 cmꢂ1
C
.
GCeMS m/z 369 (Mþ). HRMS (EI) calcd for
2H), 3.86 (s, 3H), 3.83 (s, 3H). 19F NMR (376 MHz, CDCl3)
d
ppm
17H13F3O74Se: 364.0143; Found: 364.0138.
ꢂ35.86 (s, 3F). 13C NMR (101 MHz, CDCl3)
d ppm 167.8 (s), 161.2 (s),
150.0 (s), 131.0 (s), 126.9 (s), 122.3 (q, J¼334.7 Hz), 114.1 (s), 112.3 (d,
J¼1.1 Hz), 55.4 (s), 52.8 (s). IR (KBr): 3011, 2954, 2925, 2844, 1724,
1601, 1507, 1458, 1434, 1364, 1303, 1262, 1221, 1180, 1136, 1095,
1029, 825, 735, 523 cmꢂ1. GCeMS m/z 340 (MþþH). HRMS (EI)
calcd for C12H11F3O734Se: 333.9885; Found: 333.9887.
4.2.11. Methyl
3-phenyl-2-(trifluoromethylselanyl)acrylate
(5d). Following the general procedure and workup, 5d was isolated
as a yellow oil (55 mg, 71% yield).
E-Isomer 5d: Rf (1% Et2O/n-pentane) 0.17. 1H NMR (400 MHz,
CDCl3)
(376 MHz, CDCl3)
d
ppm 7.59 (s, 1H), 7.43e7.35 (m, 5H), 3.80 (s, 3H). 19F NMR
Z-Isomer 5g: Spectral parameters for the Z isomer were ob-
tained on an enriched chromatographic fraction still containing the
d
ppm ꢂ35.46 (s, 3F). 13C NMR (101 MHz, CDCl3)
d
ppm 167.5 (s), 149.6 (q, J¼1.1 Hz), 134.4 (s), 130.1 (s), 128.7 (s),
E-isomer. 1H NMR (400 MHz, CDCl3)
d ppm 8.40 (s, 1H), 7.84 (d,
128.6 (s), 122.3 (q, J¼334.4 Hz), 115.4 (q, J¼1.5 Hz), 52.8 (s). IR (KBr):
3064, 3032, 2953, 2925, 2852, 1732, 1601, 1434, 1221, 1136, 1095,
1009, 760, 735, 690 cmꢂ1. GCeMS m/z 309 (Mþ). HRMS (EI) calcd for
J¼8.8 Hz, 2H), 6.98 (d, J¼8.8 Hz, 2H), 3.92 (s, 3H), 3.89 (s, 3H). 19
F
NMR (376 MHz, CDCl3)
d
ppm ꢂ34.46 (s, 3F). 13C NMR (101 MHz,
CDCl3)
d ppm 166.5 (s), 161.9 (s), 152.3 (s), 133.4 (s), 126.4 (s), 122.0
C
11H9F3O724Se: 303.9779; Found: 303.9775.
(q, J¼335.0 Hz), 114.0 (s), 112.4 (d, J¼1.2 Hz), 55.4 (s), 53.2 (s).
Z-Isomer 5d: 1H NMR (400 MHz, CDCl3)
d ppm 8.44 (s, 1H),
7.70e7.68 (m, 2H), 7.50e7.42 (m, 3H), 3.94 (s, 3H). 19F NMR
Acknowledgements
(376 MHz, CDCl3)
d
ꢂ34.18 (s, 3F). 13C NMR (101 MHz, CDCl3)
d ppm
166.1 (s), 152.4 (d, J¼1.0 Hz), 134.2 (s), 130.6 (s), 128.4 (s), 121.9 (q,
This work was supported by National Natural Science Founda-
tion of China (21072030), Research Fund for the Doctoral Program
of Higher Education of China (No. 20123514110003), the SRF for
ROCS, SEM, China (2012-1707), the Science Foundation of the Fujian
Province, China (2013J01040), and Fuzhou University (022318,
022494).
J¼334.9 Hz), 116.6 (q, J¼1.5 Hz), 53.3 (s).
4.2.12. Ethyl
3-phenyl-2-(trifluoromethylselanyl)acrylate
(5e). Following the general procedure and workup, 5e was isolated
as a yellow oil (64 mg, 79% yield).
E-Isomer 5e: Rf (1% Et2O/n-pentane) 0.22. 1H NMR (400 MHz,
CDCl3)
d
ppm 7.58 (s, 1H), 7.39 (s, 5H), 4.27 (q, J¼7.1 Hz, 2H), 1.23 (t,
Supplementary data
J¼7.1 Hz, 3H). 19F NMR (376 MHz, CDCl3)
d
ppm ꢂ35.33 (s, 3F). 13
C
NMR (101 MHz, CDCl3)
d
ppm 167.0 (s), 149.1 (q, J¼1.1 Hz), 134.5 (s),
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.tet.2013.11.093.
129.9 (s),128.7 (s),128.6 (s),122.3 (q, J¼334.4 Hz),116.1 (q, J¼1.4 Hz),
62.1 (s), 13.7 (s). IR (KBr): 3060, 3027, 2986, 2929, 1724, 1597, 1454,
1373, 1217, 1139, 1099, 1029, 757, 743, 694 cmꢂ1. GCeMS m/z 323
(Mþ). HRMS (EI) calcd for C12H11F3O724Se: 317.9936; Found: 317.9940.
Z-Isomer 5e: Spectral parameters for the Z isomer were ob-
tained on an enriched chromatographic fraction still containing the
References and notes
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d ppm 8.43 (s, 1H), 7.73e7.63
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for the E isomer were obtained on an enriched chromatographic

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