β-Trifluoromethyl-α-functionalized-vinyl sulfides as a potential synthetic intermediate

Article abstract of DOI:10.1016/j.tet.2009.01.097

The β-(trifluoromethyl)vinyl sulfides on treatment with n-BuLi/TMEDA at -78 °C were readily lithiated at an α-position of the sulfanyl group, and the generated β-trifluoromethyl-α-sulfanylvinyl anions were reacted with a variety of electrophiles to give the corresponding β-trifluoromethyl-α-functionalized-vinyl sulfides 4aa-4aq in good to excellent yields. The reactivity of some products has been examined. The palladium-catalyzed cross-coupling reaction as well as homo-coupling reaction of 4af provided the corresponding products in good yields, respectively. The Diels-Alder reaction of cyclic dienes and 14 derived from 4ao provided the desired six-membered cyclic products with high endo-trifluoromethyl group selectivity.

Full text of DOI:10.1016/j.tet.2009.01.097

Tetrahedron 65 (2009) 2757–2765
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
b-Trifluoromethyl-a-functionalized-vinyl sulfides as a potential synthetic
intermediate
,
a
a
a
a
Takeshi Hanamoto a , Ryoko Anno , Kenji Yamada , Kousuke Ryu , Ryoko Maeda ,
*
Kazuya Aoi a, Hiroshi Furuno b
a Department of Chemistry and Applied Chemistry, Saga University, Honjyo-machi 1, Saga 840-8502, Japan
b Institute for Materials Chemistry and Engineering (IMCE), Kyushu University, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
The
at an
b
-(trifluoromethyl)vinyl sulfides on treatment with n-BuLi/TMEDA at ꢀ78 ꢁC were readily lithiated
Received 10 January 2009
Received in revised form 28 January 2009
Accepted 28 January 2009
Available online 4 February 2009
a
-position of the sulfanyl group, and the generated
b
-trifluoromethyl-a-sulfanylvinyl anions were
reacted with a variety of electrophiles to give the corresponding
b
-trifluoromethyl-a-functionalized-vinyl
sulfides 4aa–4aq in good to excellent yields. The reactivity of some products has been examined. The
palladium-catalyzed cross-coupling reaction as well as homo-coupling reaction of 4af provided the
corresponding products in good yields, respectively. The Diels–Alder reaction of cyclic dienes and 14
derived from 4ao provided the desired six-membered cyclic products with high endo-trifluoromethyl
group selectivity.
Keywords:
Trifluoromethyl group
Vinyl sulfide
Functionalization
CF3-Building block
Ó 2009 Elsevier Ltd. All rights reserved.
1. Introduction
availability and promising reactivity.5 Moreover, the report con-
cerning the preparation of a-sulfanylvinyl anion and its synthetic
The significant expansion in the use of fluorinated compounds
has drawn much attention to chemists in various fields such as
agrochemicals, pharmaceuticals, polymers, and dyes.1 For example,
a great advantage of biologically active fluorinated compounds over
non-fluorinated ones is probably considered to appear in its in-
creasing lipophilicity and metabolic stability. Among them, the
trifluoromethyl moiety (CF3) is particularly encountered in many
biologically active pharmaceutical and agrochemical compounds
presumably due to its intrinsic properties. Therefore, the de-
velopment of a new methodology for the selective introduction of
trifluoromethyl group into readily available promising organic
compounds constitutes most important study on organofluorine
chemistry.2 As part of our research to develop versatile fluorinated
building blocks,3 we have interested in the preparation of bifunc-
tionalized olefins containing the trifluoromethyl group. One of the
straightforward ways to prepare such olefins seemed to be the
introduction of another functional group to trifluoromethylated
olefins bearing one functional group in advance. We sought an
appropriate scaffolding molecule in view of this strategy.4 By lit-
application also encouraged us to examine this strategy.6 Although
some reactions of vinyl sulfoxide and sulfone have been reported in
the literature, no detailed examination has been made in associated
research.7 The preliminary results have been reported in our pre-
vious communication.8 We report here a full account of our studies
on the synthesis of various
vinyl sulfides from -(trifluoromethyl)vinyl sulfides and their
synthetic applications.
b-trifluoromethyl-a-functionalized-
b
2. Results and discussion
2.1. Synthesis of -(trifluoromethyl)vinyl sulfides
b
According to the reported procedure, we found that the simple
addition–elimination reaction of 2-bromo-3,3,3-trifluoropropene 1
and thiophenols 2 under basic conditions afforded the corre-
sponding aryl b
-(trifluoromethyl)vinylsulfides 3 in good yields.5 The
reactions smoothly proceeded giving the E-isomers preferentially in
all cases (Scheme 1). The obtained E/Z-isomers could be easily sep-
arated from each other by column chromatography on silica gel.
erature survey we concluded that b-(trifluoromethyl)vinyl sulfide
would be the best precursor to our purpose due to its easy
2.2.
a-Functionalization of b-(trifluoromethyl)vinyl sulfide
Taguchi et al. reported one
(trifluoromethyl)vinyl sulfone as the related compound, however
a-substitution reaction using b-
* Corresponding author. Tel.: þ81 952 28 8704; fax: þ81 952 28 8548.
E-mail address: hanamoto@cc.saga-u.ac.jp (T. Hanamoto).
0040-4020/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2009.01.097

2758
T. Hanamoto et al. / Tetrahedron 65 (2009) 2757–2765
F3C
Br
F3C
F3C
TMS
STol
F3C
H
TBAF, AcOH
rt, THF
KOH
+
ArSH
EtOH
STol
SAr
(E/Z)
4aa
3a'
1
2
3
Scheme 2. Desilylation of 4aa by means of TBAF.
a: Ar= p-Tol
b: Ar = Ph
a: 84% (88/12)
b: 83%(80/20)
c:59% (90/10)
c:Ar= 2-Py
Scheme 1. Preparation of b-(trifluoromethyl)vinyl sulfide 3.
efficient protocol for the synthesis of
b-trifluoromethyl-a-func-
tionalized-vinyl sulfides. It is noteworthy that the sulfanyl group
should play an important role of these substitution reactions in
comparison with the corresponding sulfonyl group.4
the product yield was reasonable.4 One the other hand, Takeda
et al. reported the successful -substitution reaction employing
a
(b-methyl or b-phenyl)vinyl sulfides, which lead us to examine
3a under the similar conditions.6 Using the reaction of (E)-3a and
TMSCl as a model, we screened reaction conditions (Table 1). The
(E)-b-trifluoromethyl-a-(p-tolylsulfanyl)vinyl anion was gener-
2.3. Synthetic application of
functionalized-vinyl p-tolyl sulfides
b-trifluoromethyl-a-
ated in situ by addition of n-BuLi (1.2 equiv) to a solution of (E)-
3a in the presence of TMEDA (1.2 equiv) in THF at ꢀ78 ꢁC, and the
resulting anion was treated with TMSCl (1.1 equiv) at this tem-
perature to afford the desired product 4aa in 82% yield (entry 2).9
It is noteworthy that the combined use of n-BuLi and TMEDA is
essential to the successful reaction.6 The use of n-BuLi alone
substantially decreased the yield (entry 1). On the contrary to our
expectation, the reaction using 2-pyridyl sulfide 3c gave no de-
sired product and recovered 3c almost intact (entry 4). This
finding suggested that an electron-withdrawing group attached
to sulfur atom did not necessarily stabilize the adjacent vinyl
anion.
Although it is well accepted that vinyl anions have a tendency
toward their configuration with retention to a high degree,10 we
decided to confirm the configuration of the product as follows. We
conducted the desilylation–protonation process of the product 4aa
by means of TBAF in the presence of a small amount of acetic acid
(Scheme 2). The clean reaction proceeded giving a single product by
monitoring the GC–MS analysis of the crude reaction mixture. The
structural assignment of this sulfide 3a0 was performed on the basis
of comparison of its 1H NMR spectrum and GC–MS data. The
spectrum chart and retention time of 3a0 were identical with those
of the parent sulfide (E)-3a. We therefore assigned the E configu-
ration to the product 4aa.
After having examined the preparation of various
b-tri-
fluoromethyl- -functionalized-vinyl p-tolyl sulfides, we embarked
a
on the next study to explore their useful transformation. It is
well accepted that fluoride ion initiated allylation of carbonyl
compound with allylsilanes.11 We initially investigated the
generation of allyl anion equivalent from vinyl sulfide 4ae and
its subsequent addition reaction to aldehyde (Scheme 3). Thus,
to a solution of 4ae and benzaldehyde in THF was added
a
catalytic amount of TBAF in THF solution under various
conditions. Although complete consumption of 4ae was ob-
served, no adducts were obtained and benzaldehyde remained
intact. Attempts to isolate the main by-product from the re-
action mixture gave the difluorobutadiene 5 along with a small
amount of contaminants. Although the complete separation of
5 wasn’t successful, the structure of 5 was determined by 1H
NMR and 19F NMR spectroscopy. The existence of the CF2]CH–
group was confirmed by appearance of two signals of fluorine
atoms with typically geminal coupling constants (J¼22.9 Hz)
and trans and cis coupling of fluorines to single hydrogen atom
(J¼22.9 and 2.7 Hz, respectively). These results suggested that
rapid elimination of the fluoride ion from the generated allyl
anion equivalent occurred prior to addition to aldehyde on the
contrary to our expectation. On the basis of these findings we
preliminary examined the Diels–Alder reaction of 5.12 Heating
a mixture of 5 and N-phenylmaleimide in toluene in a sealed
tube at 110 ꢁC for 12 h caused only decomposition of 5.
We next briefly investigated the cross-coupling reaction of 4af
having tributylstannyl moiety. After several attempts, according to
Corey’s procedure of the Stille cross-coupling reaction of vinyl-
stannane and aryl halide,13 the reaction of 4af with 40-iodoaceto-
phenone in the presence of [Pd(PPh3)4] (5 mol %), LiCl (5 mol %),
CuTC (20 mol %) in DMSO at 50 ꢁC for 2 h smoothly proceeded
affording the desired cross-coupling product 6 in 87% yield
(Scheme 4).
Table 2 illustrates the wide generality of this substitution
reaction. The reactions with a variety of electrophiles such as
chlorosilanes, iodoalkanes, chlorostannane, iodine, thiosulfo-
nates, isocyanate, aldehydes, acyl chloride, cyanoformate, chloro-
formates proceeded well to provide the corresponding products
in good to excellent yields except for acetophenone (entry 13).
These results indicate that the
b-trifluoromethyl-a-sulfanylvinyl
anion should provide useful -(trifluoromethyl)vinyl compounds
b
in organic synthesis. We therefore present here a facile and
In addition to the cross-coupling reaction of 4af, the corre-
sponding homo-coupling reaction for the synthesis of bis(tri-
fluoromethyl)butadiene 7 was also attractive for us.14 Extensive
screening of the reaction conditions using Cu(NO3)2$3H2O revealed
that trimethyl orthoformate as a solvent was effective for this
homo-coupling reaction.15 The results are shown in Table 3.
Moreover, conducting the homo-coupling reaction at lower tem-
perature improved the product yield (entry 9). On the other hand,
the corresponding vinyl chloride 8 and vinyl bromide 9 as a major
product, respectively, were obtained in good yield along with
a small amount of 7 when we employed CuCl2 or CuBr2 in the
presence of Pd(OAc)2 instead of using Cu(NO3)2$3H2O for this
homo-coupling reaction (Scheme 5).16 These vinyl halides also
could be a useful intermediate for the synthesis of trifluoromethyl
compounds.
Table 1
Synthesis of (E)-aryl
b
-trifluoromethyl-
a
-(trimethylsilyl)vinyl sulfide 4a
i) n-BuLi/TMEDA
ii) TMSCl
F3C
F3C
TMS
SAr
-78 °C, THF
SAr
3
4
Entry
Vinyl sulfide
Additive
Productb (yield, %)
1
2
3
4
3a
3a
3b
3c
None
4aa (45)
4aa (82)
4ba (90)
4ca (0)
TMEDA
TMEDA
TMEDA
a
All reactions were conducted in THF at ꢀ78 ꢁC.
b
Isolated yield.

T. Hanamoto et al. / Tetrahedron 65 (2009) 2757–2765
2759
Table 2
Synthesis of b-trifluoromethyl-a
-functionalized-vinyl p-tolyl sulfide (4a)a
i) n-BuLi/TMEDA
F3C
F3C
E
ii) Electrophile (E+)
–78 °C, THF
15min
STol
STol
E-3a
4a
Entry
1
Electrophile
Me3SiCl
Product
Yieldb (%)
Entry
10
Electrophile
Product
Yieldb (%)
F3C
F3C
CONHPh
SiMe3
4aa (82)
Phenylisocyanate
4aj (54)
STol
SiEt3
STol
STol
2
3
Et3SiCl
4ab (71)
4ac (81)
11
12
2-Ethylbutanal
4ak (98)
4al (86)
HO
F3C
F3C
HO
STol
iPr2HSiCl
Anisaldehyde
i
F3C
SiH Pr2
F3C
OMe
Me
STol
Me
STol
4
MeI
4ad (83)
4ae (91)
13
14
Acetophenone
No reaction
4am (0)
4an (79)
F3C
STol
5c
Me3SiCH2I
p-Toluoyl chloride
O
F3C
CH2SiMe3
F3C
STol
STol
O
6
7
8
Bu3SnCl
4af (81)
4ag (91)
4ah (95)
15
16
17
Ethyl cyanoformate
Ethyl chloroformate
Methyl chloroformate
4ao (60)
4ao (72)
4ap (75)
F3C
F3C
F3C
SnBu3
OEt
F3C
STol
STol
I2
O
I
F3C
F3C
OEt
STol
STol
PhSS(O)2Ph
O
SPh
STol
OMe
STol
9
TolSS(O)2Tol
4ai (58)
18
2-Ethylhexyl chloroformate
4aq (76)
O
STol
STol
F3C
O
F3C
Et
Bu
STol
a
All reactions were conducted using E-3a (1 equiv) with electrophiles (1.1 equiv) at ꢀ78 ꢁC for 15 min.
b
c
Isolated yield.
Reaction time was 4 h.
With 7 in hand, we successively examined the thermal Diels–
to steric bulkiness of the CF3 group at the 1,4-positions of the
butadiene.
We next tried to construct the CF3-containing heterocyclic
compound. Thus, the reaction of a,b-unsaturated ketone 4an with
hydrazine monohydrate was conducted in ethanol for 15 h under
reflux conditions. On the contrary to our expectation, the corre-
sponding 3-p-tolyl-5-trifluoromethyl-1H-pyrazole 10 was obtained
Alder reaction. A toluene solution of 7 and N-phenylmaleimide in
a sealed tube was refluxed for 12 h then heated up to 180 ꢁC for 6 h.
However, no desired cycloadduct was obtained and only a small
amount of partially isomerized product derived from 7 was ob-
served by GC–MS analysis in the reaction mixture. This observation
suggested that no reactivity of 7 as a diene for the Diels–Alder re-
action may attribute to have difficulty with s-cis conformation due
SnBu3
STol
F3C
O
+
I
Ph
cat. TBAF
THF
F3C
F3C
TMS
+
PhCHO
O
OTMS
4af
Pd(PPh3)4
STol
4ae
STol
LiCl, CuTC
DMSO, 50 °C
F3C
F
F
STol
STol
Scheme 3. Reaction of 4ae with PhCHO in the presence of TBAF.
6 (87%)
5
Scheme 4. Cross-coupling reaction of 4af with 40-iodoacetophenone.

2760
T. Hanamoto et al. / Tetrahedron 65 (2009) 2757–2765
F3C
Table 3
F3C
OH
STol
CO2Me
STol
DIBAL
Homo-coupling reaction of 4af under various conditions
CH2Cl2, 0 °C
TolS
F3C
SnBu3
STol
Cu(NO3)2•3H2O
F3C
4ap
11(88%)
CF3
F3C
F3C
OAc
Br
STol
STol
Ac2O, DMAP
CH2Cl2, rt
CBr4, PPh3
THF, rt
11
4af
7
STol
12 (94%)
13 (89%)
Entry
Solvent
Cu(NO3)2$3H2O (equiv)
Temp (ꢁC)
Yielda (%)
1
2
3
4
5
6
7
8
9
Ether
Ether
Ether
Hexane
THF
Dioxane
MTBEb
CH(OMe)3
CH(OMe)3
1.0
2.0
5.0
2.0
2.0
2.0
2.0
2.0
2.0
25
25
25
25
25
25
25
25
Trace
19
Scheme 8. Transformation of 4ap.
11
NRc
20
F3C
F3C
CO2Me
STol
CO2Me
Ts
mCPBA
46
29
55
74
-78 °C ~rt
CH2Cl2
ꢀ50 to 0
4ap
14 (80%)
a
Isolated yield.
Methyl tert-butyl ether.
No reaction occurred.
Scheme 9. Oxidation of 4ap with m-CPBA.
b
c
Oxidation of 4ap with m-CPBA afforded the desired product 14 in
80% yield (Scheme 9).
F3C
F3C
SnBu3
STol
X
CuCl2 or CuBr2
Pd(OAc)2
+
7
We subsequently examined the Diels–Alder reaction of 14 with
cyclopentadiene. The reaction was conducted using 14 and an ex-
cess of cyclopentadiene in toluene at 100 ꢁC for 2 h giving the
cycloadducts with a ratio of 90:10 in 74% combined yield (Scheme
10). When the same reaction was carried out in a sealed tube in
CH2Cl2 at 60 ꢁC for 2 h, the diastereoselectivity of the products
slightly improved to 92:8 in 65% yield. The diastereomer was sep-
arated from the reaction mixture using silica gel chromatography.
The structure of the main product 15 was successfully determined
to be endo-CF3-endo-CO2Me-exo-Ts after its X-ray crystallography
analysis (Fig. 1).
STol
X= Cl (74%) 8
X= Br (68%) 9
4af
Scheme 5. Halogenation of 4af with CuCl2 or CuBr2.
as a desulfurization product in 88% yield (Scheme 6).17 Although the
detailed reaction mechanism is not clear, the plausible mechanism
of the formation of 10 was depicted in Scheme 7.
Me
Me
Ts
CO2Me
CF3
100 °C, 2h
+
14
+
NH2NH2•H2O
EtOH, reflux
toluene
(74%)
CO2Me
Ts
F3C
O
CF3
15
N
F3C
90 : 10 16
Scheme 10. Diels–Alder reaction of cyclopentadiene and 14.
N
H
STol
4an
10, 88%
Scheme 6. Synthesis of pyrazole 10.
We have also explored the possibility of ordinary functional
transformation of an ester group at position . Reduction of 4ap
a
with DIBAL in CH2Cl2 at 0 ꢁC afforded the allylic alcohol 11 in 88%
yield.18 The use of LiAlH4 in the same reaction resulted in con-
tamination of the saturated alcohol as an over-reduction product.
Acetylation and bromination of 11 smoothly proceeded giving the
corresponding allylic acetate 12 and allylic bromide 13 as a po-
tential synthetic intermediate in 94% and 89%, respectively
(Scheme 8).
As a further application of 4ap, the thermal Diels–Alder reaction
was investigated.7c,19 When a mixture of 4ap and cyclopentadiene
was refluxed in toluene for 1 h, only a trace amount of the cyclo-
adduct was detected by GC–MS analysis. To enhance the reactivity
of the dienophile 4ap, we planed to transfer the sulfanyl group into
the sulfonyl group as a stronger electron-withdrawing group.
Figure 1. X-ray structure of 15 (50% probability level).
Ar
TolS
F3C
TolS
F3C
Ar
Ar
TolS
Ar
F3C
NNH2
4an
10
=
NH
N
NNH2
CF3
N
H
N
H
STol
Ar = p-Tol
Scheme 7. Plausible mechanism for the formation of 10.

T. Hanamoto et al. / Tetrahedron 65 (2009) 2757–2765
2761
On the other hand, the reaction of 1,4-cyclohexadiene with 14 in
toluene at 40–60 ꢁC for 84 h afforded the single diastereomer 17
albeit in 31% yield. The structure of 17 was also assigned the endo-
CF3-endo-CO2Me-exo-Ts configuration on the basis of its 1H NMR
and 19F NMR data in comparison with that of 15. Finally, the Diels–
Alder reaction of 14 and 2,3-dimethylbutadiene under mild con-
ditions provided the corresponding cyclohexene derivative 18 in
65% yield (Scheme 11).
7.22 (2H, d, J¼7.7 Hz), 7.35 (2H, d, J¼8.1 Hz); 13C NMR (CDCl3,
75 MHz)
d
3.4 (q, J¼2.5 Hz), 7.3, 21.3, 118.2 (q, J¼35.5 Hz), 123.5 (q,
J¼270.3 Hz), 126.3, 130.8, 135.8, 140.1, 153.8 (q, J¼5.6 Hz); 19F NMR
(CDCl3, 283 MHz)
179 (43), 141 (34), 105 (30), 91 (52), 77 (100), 59 (31). Anal. Calcd for
C16H23F3SSi: C, 57.80; H, 6.97. Found: C, 57.70; H, 6.83%.
d
ꢀ57.2 (d, J¼10.0 Hz); GC–MS m/z 332 (4, Mþ),
3.1.3. (E)-(3,3,3-Trifluoro-1-(p-tolylthio)prop-1-enyl)-
diisopropylsilane (4ac)
Colorless oil; yield 81%; IR (neat) 2945, 2890, 2867, 1583, 1492,
Ts
1463, 1316, 1270, 1135, 1114, 1009, 909, 847, 809, 785, 664 cmꢀ1; 1H
CO2Me
Ts
CO2Me
14
NMR (CDCl3, 300 MHz)
d
1.12 (6H, d, J¼7.0 Hz), 1.14 (6H, d,
rt
40 ~ 60 °C
CF3
J¼7.0 Hz), 1.22–1.35 (2H, m), 2.40 (3H, s), 3.82 (1H, sxt, J¼4.8 Hz),
5.30 (1H, q, J¼8.4 Hz), 7.25 (2H, d, J¼8.1 Hz), 7.33 (2H, d, J¼8.1 Hz);
CF3
17 (31%)
18 (65%)
13C NMR (CDCl3, 75 MHz)
d
11.06 (d, J¼3.1 Hz), 11.08 (d, J¼3.1 Hz),
Scheme 11. Diels–Alder reaction of 14 with two dienes.
18.85, 18.87, 21.3, 118.9 (q, J¼34.9 Hz), 123.4 (q, J¼270.3 Hz), 126.1,
130.8, 135.6, 140.3, 152.0 (q, J¼5.6 Hz); 19F NMR (CDCl3, 283 MHz)
In summary, we have demonstrated the convenient synthesis of
4aa–4aq as a promising trifluoromethylated building block from
readily available b-(trifluoromethyl)vinyl sulfide. Actually we have
illustrated the cross-coupling reactions, reduction, cyclization, and
Diels–Alder reaction of selected products by taking advantage of
potential functional groups introduced. These products were also
expected to be useful candidates for building up more complex
trifluoromethylated compounds.
d
ꢀ57.5 (dd, J¼7.3, 5.5 Hz); GC–MS m/z 332 (3, Mþ), 269 (27), 179
(40), 161 (42), 141 (92), 123 (70), 91 (100), 77 (58), 63 (55). Anal.
Calcd for C16H23F3SSi: C, 57.80; H, 6.97. Found: C, 57.80; H, 6.93%.
3.1.4. (E)-(4,4,4-Trifluorobut-2-en-2-yl)(p-tolyl)sulfane (4ad)
Colorless oil; yield 83%; IR (neat) 3026, 2927, 1638, 1581, 1274,
1134, 1004, 811, 737 cmꢀ1 1H NMR (CDCl3, 300 MHz)
; d 2.13 (3H,
dq, J¼1.1, 2.2 Hz), 2.39 (3H, s), 4.93 (1H, qq, J¼8.3, 1.1 Hz), 7.23 (2H,
d, J¼7.9 Hz), 7.37 (2H, d, J¼8.1 Hz); 13C NMR (CDCl3, 75 MHz)
d 18.5
3. Experimental
3.1. General
(q, J¼1.2 Hz), 21.3, 109.4 (q, J¼34.3 Hz), 123.5 (q, J¼270.3 Hz), 125.9,
130.6, 135.5, 140.3, 151.5 (q, J¼5.6 Hz); 19F NMR (CDCl3, 283 MHz)
d
ꢀ57.2 (d, J¼6.4 Hz); GC–MS m/z 232 (8, Mþ), 148 (14), 91 (50), 77
(22), 65 (15), 59 (100). Anal. Calcd for C11H11F3S: C, 56.88; H, 4.77.
Found: C, 57.06; H, 4.85%.
Melting points are uncorrected. Infrared (IR) spectra are repor-
ted in cmꢀ1. 1H, 19F, and 13C NMR spectra were measured in CDCl3
solutions. Chemical shifts were given by
d
relative to that of an
3.1.5. (E)-(4,4,4-Trifluoro-2-(p-tolylthio)but-2-enyl)trimethyl-
silane (4ae)
internal Me4Si (TMS) for 1H NMR and 13C NMR spectra, and ben-
zylidyne trifluoride (CF3C6H5) or hexafluorobenzene (C6F6) for 19F
NMR spectra.
White solid; yield 91%; mp 29.8–32.5 ꢁC; IR (KBr) 3025, 2957,
2927, 1611, 1494, 1351, 1258, 1188, 1135, 1079, 915, 840, 811 cmꢀ1
;
1H NMR (CDCl3, 300 MHz)
d
0.16 (9H, s), 2.09 (2H, q, J¼1.8 Hz), 2.38
3.1.1. Preparation of (E)-(3,3,3-trifluoro-1-(p-tolylthio)prop-1-
enyl)trimethylsilane (4aa)
(3H, s), 4.70 (1H, q, J¼8.4 Hz), 7.22 (2H, d, J¼7.7 Hz), 7.35 (2H, d,
J¼8.1 Hz); 13C NMR (CDCl3, 75 MHz)
d
ꢀ0.68, 21.3, 24.4, 105.6 (q,
To a solution of E-3a (84.0 mg, 0.385 mmol)8 in THF (2 mL)
J¼34.3 Hz), 123.8 (q, J¼270.3 Hz), 125.9, 130.6, 135.5, 140.3, 154.9
under argon was added TMEDA (74
m
L, 0.46 mmol) at room tem-
(q, J¼5.6 Hz); 19F NMR (CDCl3, 283 MHz)
d
ꢀ56.4 (d, J¼8.8 Hz);
perature, and the whole mixture was cooled to ꢀ78 ꢁC. After being
GC–MS m/z 304 (0.6, Mþ), 196 (5), 123 (9), 107 (17), 91 (22), 77 (48),
73 (100). Anal. Calcd for C14H19F3SSi: C, 55.23; H, 6.29. Found: C,
55.53; H, 6.31%.
stirred for 10 min at this temperature, to this mixture was added n-
BuLi (2.71 M in hexane solution, 170
mL, 0.46 mmol) dropwise via
syringe. After being stirred for 10 min, TMSCl (54
mL, 0.42 mmol)
was added to the solution, and the whole mixture was stirred for
15 min. The reaction was quenched with water at this temperature
and extracted with hexane/ether¼3:1. Additional extraction was
repeated twice. The combined organic solution was dried over
Na2SO4 and concentrated in vacuo. The residue was purified by
Florisil chromatography (hexane as eluant) to give 91.7 mg of 4aa as
pale yellow oil in 82% yield: IR (neat) 3025, 2957, 1585, 1276, 1135,
3.1.6. (Z)-Tributyl(3,3,3-trifluoro-1-(p-tolylthio)prop-1-enyl)-
stannane (4af)
Colorless oil; yield 81%; IR (neat) 2958, 2923, 1578, 1302, 1271,
1128, 1106, 880, 810 cmꢀ1; 1H NMR (CDCl3, 300 MHz)
d 0.92 (9H, t,
J¼7.2 Hz), 1.09–1.21 (6H, m), 1.30–1.42 (6H, m), 1.51–1.62 (6H, m),
2.38 (3H, s), 5.37 (1H, q, J¼7.9 Hz), 7.23 (2H, d, J¼8.3 Hz), 7.31 (2H, d,
J¼8.1 Hz); 13C NMR (CDCl3, 75 MHz)
d 11.6, 13.6, 21.3, 27.2, 28.4,
1109, 847, 817 cmꢀ1; 1H NMR (CDCl3, 300 MHz)
d
0.34 (9H, s), 2.39
116.3 (q, J¼33.6 Hz), 124.1 (q, J¼269.1 Hz), 127.2, 130.6, 135.2, 139.8,
(3H, s), 5.22 (1H, q, J¼9.2 Hz), 7.24 (2H, d, J¼8.4 Hz), 7.32 (2H, d,
156.5 (q, J¼7.5 Hz); 19F NMR (CDCl3, 283 MHz)
d
ꢀ59.3 (d,
J¼8.1 Hz); 13C NMR (CDCl3, 75 MHz)
d
ꢀ0.49 (q, J¼2.5 Hz), 21.3,
J¼6.1 Hz); GC–MS m/z 450 (4.3, MþꢀBu), 179 (75), 178 (100), 135
(2), 123 (10), 119 (16), 107 (41), 91 (72), 65 (8). Anal. Calcd for
C22H35F3SSn: C, 52.09; H, 6.95. Found: C, 51.82; H, 6.99%.
117.8 (q, J¼35.5 Hz), 123.6 (q, J¼270.3 Hz), 126.2, 130.8, 135.7, 140.1,
155.9 (q, J¼5.6 Hz); 19F NMR (CDCl3, 283 MHz)
d
ꢀ56.9 (d,
J¼10.0 Hz); GC–MS m/z 290 (0.5, Mþ), 141 (48), 107 (47), 91 (21), 77
(55), 73 (100), 65 (17). Anal. Calcd for C13H17F3SSi: C, 53.76; H, 5.90.
Found: C, 53.87; H, 5.78%.
3.1.7. (Z)-(3,3,3-Trifluoro-1-iodoprop-1-enyl)(p-tolyl)sulfane (4ag)
Colorless oil; yield 91%; IR (neat) 3038, 2924, 1597, 1492, 1400,
1286, 1260, 1132, 832, 810, 667 cmꢀ1 1H NMR (CDCl3, 300 MHz)
;
3.1.2. (E)-Triethyl(3,3,3-trifluoro-1-(p-tolylthio)prop-1-enyl)-
silane (4ab)
d
2.39 (3H, s), 5.82 (1H, q, J¼7.2 Hz), 7.27 (2H, d, J¼8.3 Hz), 7.42 (2H,
d, J¼8.1 Hz); 13C NMR (CDCl3, 75 MHz)
d
21.5, 103.8 (q, J¼6.2 Hz),
Colorless oil; yield 71%; IR (neat) 3024, 2959, 2878, 1620, 1581,
119.3 (q, J¼36.7 Hz), 121.8 (q, J¼270.9 Hz), 129.2, 130.9, 134.8, 141.3;
1274, 1134, 1004, 811, 737 cmꢀ1; 1H NMR (CDCl3, 300 MHz)
d
0.82–
19F NMR (CDCl3, 283 MHz)
(0.4, Mþ), 343 (0.6), 217 (26), 173 (9), 148 (31), 147 (31), 123 (33), 91
d
ꢀ59.2 (d, J¼8.4 Hz); GC–MS m/z 344
0.91 (6H, m), 0.99–1.06 (9H, m), 2.39 (3H, s), 5.26 (1H, q, J¼9.4 Hz),

2762
T. Hanamoto et al. / Tetrahedron 65 (2009) 2757–2765
(68), 77 (20), 65 (100). Anal. Calcd for C10H8F3IS: C, 34.90; H, 2.34.
Found: C, 35.07; H, 2.36%.
94 (35), 77 (44), 65 (20). Anal. Calcd for C18H17F3O2S: C, 61.00; H,
4.84. Found: C, 60.94; H, 4.92%.
3.1.8. (E)-4-(3,3,3-Trifluoro-1-(phenylthio)prop-1-enylthio)-1-
methylbenzene (4ah)
3.1.13. (E)-4,4,4-Trifluoro-1-p-tolyl-2-(p-tolylthio)but-2-en-
1-one (4an)
Colorless oil; yield 95%; IR (neat) 3058, 3025, 2924, 1586, 1296,
White solid; yield 79%; mp 61.8–62.5 ꢁC; IR (KBr) 3030, 2958,
1259, 1138, 841, 809, 746, 689 cmꢀ1
;
1H NMR (CDCl3, 300 MHz)
2925, 1676, 1606, 1334, 1276, 1147, 1015, 858, 810 cmꢀ1 1H NMR
;
d
2.37 (3H, s), 5.38 (1H, q, J¼7.9 Hz), 7.15–7.25 (3H, m), 7.34–7.40
(CDCl3, 300 MHz)
d
2.39 (3H, s), 2.44 (3H, s), 5.28 (1H, q, J¼7.9 Hz),
(4H, m), 7.45–7.53 (2H, m); 13C NMR (CDCl3, 75 MHz)
d
21.0, 113.1
7.22 (2H, d, J¼8.1 Hz), 7.29 (2H, d, J¼8.1 Hz), 7.40 (2H, d, J¼8.1 Hz),
(q, J¼35.5 Hz), 122.8 (q, J¼270.9 Hz), 126.6, 128.8, 129.8, 130.6,
7.84 (2H, d, J¼8.3 Hz); 13C NMR (CDCl3, 75 MHz)
d 21.3, 21.8, 110.8
134.2, 135.0, 139.4, 140.4, 151.4 (q, J¼5.0 Hz); 19F NMR (CDCl3,
(q, J¼35.5 Hz), 122.1 (q, J¼270.9 Hz), 129.1, 129.5, 129.6, 129.8, 130.8,
283 MHz)
d
ꢀ56.8 (d, J¼8.7 Hz); GC–MS m/z 326 (2.2, Mþ), 217 (5),
135.8, 141.0, 145.5, 151.1 (q, J¼5.6 Hz), 190.4; 19F NMR (CDCl3,
183 (7), 153 (18), 134 (50), 124 (54), 91 (67), 77 (100), 65 (69). Anal.
Calcd for C16H13F3S2: C, 58.88; H, 4.01. Found: C, 58.99; H, 4.06%.
283 MHz)
d
ꢀ58.7 (d, J¼8.8 Hz); GC–MS m/z 336 (0.8, Mþ), 119
(100), 91 (39), 65 (15). Anal. Calcd for C18H15F3OS: C, 64.27; H, 4.49.
Found: C, 64.26; H, 4.52%.
3.1.9. 4-(3,3,3-Trifluoro-1-(p-tolylthio)prop-1-enylthio)-1-
methylbenzene (4ai)
3.1.14. (E)-Ethyl 4,4,4-trifluoro-2-(p-tolylthio)but-2-enoate (4ao)
Pale yellow oil; yield 72%; IR (neat) 2985, 1741, 1629, 1493, 1448,
1370,1334, 1275, 1223, 1140, 1018, 984, 852, 811, 669 cmꢀ1; 1H NMR
White solid; yield 58%; mp 57.5–59.0 ꢁC; IR (KBr) 3059, 3024,
2922, 2861, 1574, 1295, 1258, 1137, 1104, 845, 809, 663 cmꢀ1 1H
;
NMR (CDCl3, 300 MHz)
d
2.37 (3H, s), 2.38 (3H, s), 5.27 (1H, q,
(CDCl3, 300 MHz)
d
1.25 (3H, t, J¼7.5 Hz), 2.39 (3H, s), 4.20 (2H, q,
J¼7.9 Hz), 7.18 (4H, d, J¼8.1 Hz), 7.24 (2H, d, J¼8.1 Hz), 7.40 (2H, d,
J¼7.2 Hz), 5.23 (1H, q, J¼7.9 Hz), 7.25 (2H, d, J¼8.1 Hz), 7.42 (2H,
J¼8.1 Hz); 13C NMR (CDCl3, 75 MHz)
d
21.3, 113.1 (q, J¼35.5 Hz),
d, J¼8.3 Hz); 13C NMR (CDCl3, 75 MHz)
d 13.7, 21.3, 62.6, 113.3 (q,
122.8 (q, J¼270.9 Hz), 126.6, 126.8, 129.8, 130.6, 134.2, 135.0, 139.4,
J¼36.7 Hz), 120.0, 121.8 (q, J¼270.0 Hz), 130.8, 135.5, 141.1, 145.4 (q,
140.4, 151.4 (q, J¼5.0 Hz); 19F NMR (CDCl3, 283 MHz)
d
ꢀ57.0 (d,
J¼5.6 Hz), 163.4; 19F NMR (CDCl3, 283 MHz)
d
ꢀ59.6 (d, J¼8.1 Hz);
J¼8.8 Hz); GC–MS m/z 340 (6, Mþ), 217 (19), 167 (29), 148 (25), 124
(44), 107 (13), 91 (100), 77 (32), 65 (80). Anal. Calcd for C17H15F3S2:
C, 59.98; H, 4.44. Found: C, 60.20; H, 4.43%.
GC–MS m/z 290 (7, Mþ), 217 (3), 149 (94), 123 (53), 108 (18), 91 (87),
77 (29), 65 (100). Anal. Calcd for C13H13F3O2S: C, 53.78; H, 4.51.
Found: C, 53.83; H, 4.40%.
3.1.10. (E)-4,4,4-Trifluoro-N-phenyl-2-(p-tolylthio)but-2-
enamide (4aj)
3.1.15. (E)-Methyl 4,4,4-trifluoro-2-(p-tolylthio)but-2-enoate (4ap)
Pale yellow oil; yield 75%; IR (neat) 2956, 1744, 1626, 1493, 1436,
White solid; yield 54%; mp 126.9–128.3 ꢁC; IR (KBr) 3301, 1663,
1339, 1276, 1230, 1139, 1017, 927, 856, 812 cmꢀ1 1H NMR (CDCl3,
;
1536, 1446, 1336,1273, 1143, 1107, 858, 809, 757, 693 cmꢀ1; 1H NMR
300 MHz)
d
2.39 (3H, s), 3.75 (3H, s), 5.24 (1H, q, J¼7.8 Hz), 7.25 (2H,
(CDCl3, 300 MHz)
d
2.39 (3H, s), 5.24 (1H, q, J¼7.9 Hz), 7.10–7.50
21.3,
d, J¼8.1 Hz), 7.42 (2H, d, J¼8.3 Hz); 13C NMR (CDCl3, 75 MHz)
d 21.3,
(9H, m), NH proton is missing; 13C NMR (CDCl3, 75 MHz)
d
53.0, 113.5 (q, J¼36.5 Hz), 121.7 (q, J¼270.5 Hz), 123.8, 130.8, 135.4,
112.2 (q, J¼36.1 Hz), 120.5, 122.0 (q, J¼270.9 Hz), 123.6, 125.4, 129.1,
141.1, 145.1 (q, J¼5.8 Hz), 163.8; 19F NMR (CDCl3, 283 MHz)
d
ꢀ59.9
130.9, 135.2, 136.6, 141.1, 148.7 (q, J¼5.6 Hz), 161.0; 19F NMR (CDCl3,
(d, J¼6.9 Hz); GC–MS m/z 275 (34, Mþ), 244 (3), 217 (15), 173 (23),
148 (95), 123 (54), 91 (80), 65 (100). Anal. Calcd for C12H11F3O2S: C,
52.17; H, 4.01. Found: C, 52.43; H, 3.99%.
283 MHz)
d
ꢀ58.8 (d, J¼8.0 Hz); GC–MS m/z 337 (6, Mþ), 268 (2),
217 (5), 148 (19), 123 (49), 107 (24), 91 (74), 77 (84), 65 (100). Anal.
Calcd for C17H14F3NOS: C, 60.52; H, 4.18; N, 4.15. Found: C, 60.43; H,
4.16; N, 4.16%.
3.1.16. (E)-2-Ethylhexyl 4,4,4-trifluoro-2-(p-tolylthio)but-
2-enoate (4aq)
3.1.11. (E)-5-Ethyl-1,1,1-trifluoro-3-(p-tolylthio)hept-
2-en-4-ol (4ak)
Pale yellow oil; yield 76%; IR (neat) 2961, 2931, 1741, 1629, 1493,
1463, 1382, 1335, 1276, 1223, 1141, 1018, 855, 811, 670 cmꢀ1 1H
;
Pale yellow oil; yield 98%; IR (neat) 3439, 2966, 2937,1626,1493,
NMR (CDCl3, 300 MHz)
d
0.87 (3H, t, J¼7.5 Hz), 0.90 (3H, t,
1326, 1267, 1112, 1021, 913, 857, 812, 669 cmꢀ1
;
1H NMR (CDCl3,
J¼7.2 Hz), 1.20–1.42 (8H, m), 1.50–1.65 (1H, m), 2.39 (3H, s), 4.00
(1H, dd, J¼11.0, 5.7 Hz), 4.05 (1H, dd, J¼10.6, 5.5 Hz), 5.26 (1H, q,
J¼7.9 Hz), 7.24 (2H, d, J¼8.1 Hz), 7.42 (2H, d, J¼8.3 Hz); 13C NMR
300 MHz)
d
0.92 (3H, t, J¼7.3 Hz), 0.95 (3H, t, J¼7.3 Hz), 1.20–1.46
(2H, m), 1.52–1.70 (1H, m), 1.70–1.95 (3H, m), 2.40 (3H, s), 4.75 (1H,
d, J¼8.6 Hz), 4.84 (1H, q, J¼8.8 Hz), 7.25 (2H, d, J¼7.9 Hz), 7.38 (2H,
(CDCl3, 75 MHz) d 10.8, 14.0, 21.3, 22.9, 23.5, 28.8, 30.1, 38.5, 68.8,
d, J¼8.1 Hz); 13C NMR (CDCl3, 75 MHz)
d
9.4, 11.1, 20.1, 21.1, 21.3,
113.4 (q, J¼36.7 Hz), 121.7 (q, J¼270.3 Hz), 124.0, 130.8, 135.4, 140.9,
44.5, 71.5, 110.7 (q, J¼35.5 Hz), 123.2 (q, J¼270.9 Hz), 125.2, 130.9,
145.4 (q, J¼5.6 Hz), 163.7; 19F NMR (CDCl3, 283 MHz)
d
ꢀ59.7 (d,
135.9, 140.4, 160.1 (q, J¼5.6 Hz); 19F NMR (CDCl3, 283 MHz)
d
ꢀ55.1
J¼8.0 Hz); GC–MS m/z 374 (0.7, Mþ), 373 (4, Mþꢀ1), 261 (3), 216 (4),
173 (2), 149 (22), 123 (20), 91 (24), 77 (7), 69 (54), 65 (21), 57 (100).
Anal. Calcd for C19H25F3O2S: C, 60.94; H, 6.73. Found: C, 61.18; H,
6.67%.
(d, J¼9.2 Hz); GC–MS m/z 318 (0.8, Mþ), 248 (9), 124 (100), 91 (59),
77 (21), 65 (15). Anal. Calcd for C16H21F3OS: C, 60.36; H, 6.65. Found:
C, 60.30; H, 6.72%.
3.1.12. (E)-4,4,4-Trifluoro-1-(p-methoxyphenyl)-2-(p-tolylthio)but-
2-en-1-ol (4al)
3.2. Preparation of (E)-1-(4-(3,3,3-trifluoro-1-(p-
tolylthio)prop-1-enyl)phenyl)ethanone (6)
Pale yellow oil; yield 86%; IR (neat) 3443, 2936, 1612, 1512, 1264,
1149, 1109, 1033, 856, 813, 670 cmꢀ1
;
1H NMR (CDCl3, 300 MHz)
To a solution of 4af (101.5 mg, 0.200 mmol) in DMSO (1 mL)
under argon were successively added 40-iodoacetophenone
(43.0 mg, 0.175 mmol), CuTC (1.9 mg, 0.01 mmol), LiCl (3.1 mg,
0.07 mmol), and Pd(PPh3)4 (12.5 mg, 0.01 mmol) at room tem-
perature. The whole mixture was heated to 80 ꢁC for 2 h. After
the mixture was cooled to room temperature, the reaction was
quenched with water and extracted with hexane/ethyl
acetate¼3:1. Additional extraction was repeated twice. The
d
2.37 (3H, s), 2.51 (1H, d, J¼5.1 Hz), 3.82 (3H, s), 4.92 (1H, q,
J¼8.8 Hz), 6.05 (1H, d, J¼5.0 Hz), 6.93 (2H, d, J¼8.8 Hz), 7.21 (2H, d,
J¼7.9 Hz), 7.33 (2H, d, J¼8.1 Hz), 7.48 (2H, d, J¼8.8 Hz); 13C NMR
(CDCl3, 75 MHz)
d
21.3, 55.2, 70.8 (q, J¼1.9 Hz), 110.3 (q, J¼34.9 Hz),
113.8, 123.1 (q, J¼271.5 Hz), 125.4, 127.4, 130.8, 132.0, 135.7, 140.3,
159.4, 159.8 (q, J¼5.6 Hz); 19F NMR (CDCl3, 283 MHz)
d
ꢀ55.4 (d,
J¼8.4 Hz); GC–MS m/z 354 (0.01, Mþ), 217 (9), 137 (100), 123 (12),

T. Hanamoto et al. / Tetrahedron 65 (2009) 2757–2765
2763
combined organic solution was dried over Na2SO4 and concen-
d
ꢀ59.4 (d, J¼7.1 Hz); GC–MS m/z 298 (7, Mþ
[
81Br]), 296 (6, Mþ
trated in vacuo. The residue was purified by silica gel chroma-
tography (hexane/ethyl acetate¼20:1 as eluant) to give 51.0 mg of
6 as a white solid in 87% yield. Mp 135.5–136.8 ꢁC; IR (KBr) 3042,
1682, 1634, 1600, 1494, 1403, 1346, 1269, 1187, 1135, 1098, 1016,
[
79Br]), 227 (4), 217 (30), 173 (26), 148 (83), 123 (40), 91 (43), 77
(22), 65 (100). Anal. Calcd for C10H8BrF3S: C, 40.42; H, 2.71.
Found: C, 40.56; H, 2.73%.
962, 822, 811, 776, 666 cmꢀ1
;
1H NMR (CDCl3, 300 MHz)
d
2.40
3.4. 5-Trifluoromethyl-3-p-tolyl-1H-pyrazole (10)17a
(3H, s), 2.62 (3H, s), 5.16 (1H, q, J¼7.9 Hz), 7.25 (2H, d, J¼7.9 Hz),
7.43 (2H, d, J¼8.1 Hz), 7.49 (2H, d, J¼8.3 Hz), 7.95 (2H, d,
To a solution of 4an (23.1 mg, 0.069 mmol) in ethanol (2 mL)
under argon was added NH2NH2$H2O (9.0 mL, 0.186 mmol) at room
J¼8.1 Hz); 13C NMR (CDCl3, 75 MHz)
d
21.3, 26.6, 110.6 (q,
J¼34.9 Hz), 122.6 (q, J¼270.9 Hz), 125.6, 128.0, 128.76, 128.77,
temperature, and the whole mixture was gently warmed up to
80 ꢁC. After the reaction mixture was stirred for 15 h at this tem-
perature, the solution was directly concentrated. To the residue
were added ethyl acetate and water. After separation of the organic
layer, additional extraction was repeated twice. The combined or-
ganic solution was dried over Na2SO4 and concentrated in vacuo.
The residue was purified by silica gel chromatography (hexane/
ethyl acetate¼4:1 as eluant) to give 13.6 mg of 10 as a white solid in
130.8, 135.4, 137.4, 140.0, 140.7, 153.6 (q, J¼5.6 Hz), 197.3; 19F NMR
(CDCl3, 283 MHz)
d
ꢀ55.9 (d, J¼7.6 Hz); GC–MS m/z 336 (5, Mþ),
267 (19), 163 (90), 124 (37), 101 (34), 91 (100), 77 (45), 65 (33).
Anal. Calcd for C18H15F3OS: C, 64.27; H, 4.49. Found: C, 64.18; H,
4.43%.
3.3. (2E,4E)-1,1,1,6,6,6-Hexafluoro-3,4-bis(p-tolylthio)hexa-
2,4-diene (7)
88% yield. Mp 155.3–156.8 ꢁC; 1H NMR (CDCl3, 300 MHz)
d
2.39
(3H, s), 6.70 (1H, s), 7.25 (2H, d, J¼8.1 Hz), 7.45 (2H, d, J¼8.1 Hz),
To a solution of 4af (88.5 mg, 0.174 mmol) in CH(OMe)3 (1 mL)
under argon was added Cu(NO3)2$3H2O (85.6 mg, 0.348 mmol) at
ꢀ50 ꢁC, and the whole mixture was gently warmed to 0 ꢁC over 2 h.
The reaction was quenched with water and extracted with hexane/
ether¼3:1 solution. Additional extraction was repeated twice. The
combined organic solution was dried over Na2SO4 and concen-
trated in vacuo. The residue was purified by silica gel chromatog-
raphy (hexane/triethylamine¼200:1 as eluant) to give 28.0 mg of 7
as a white solid in 74% yield. Mp 100.8–102.1 ꢁC; IR (KBr) 3068,
2924, 1651, 1614, 1596, 1491, 1361, 1295, 1280, 1162, 1138, 1107, 1017,
11.74 (1H, br s); 19F NMR (CDCl3, 283 MHz)
d
ꢀ63.6 (s); GC–MS m/z
226 (100, Mþ), 205 (19), 177 (17), 157 (27), 130 (49), 90 (37), 63 (42),
51 (75).
3.5. Preparation of (E)-4,4,4-trifluoro-2-(p-tolylthio)but-2-
en-1-ol (11)
To a solution of 4ap (776.8 mg, 2.81 mmol) in CH2Cl2 (10 mL)
under argon was added DIBAL (0.98 M in hexane, 6.89 mL,
6.75 mmol) dropwise via syringe at 0 ꢁC, and the whole mixture
was stirred for 20 min at this temperature. The reaction was slowly
quenched with Na2SO4$10H2O. A small amount of additional
Na2SO4 and NaF was added to the reaction mixture. The solution
was separated and the residual precipitate was washed with hex-
ane/ether¼3:1. The combined organic solution was dried over
Na2SO4 and concentrated in vacuo. The residue was purified by
silica gel chromatography (hexane/ether¼3:1 as eluant) to give
697.3 mg of 11 as pale yellow oil in 88% yield. IR (neat) 3351, 1628,
908, 852, 814, 807, 669 cmꢀ1; 1H NMR (CDCl3, 300 MHz)
d 2.41 (6H,
s), 4.69 (2H, br q, J¼7.0 Hz), 7.26 (4H, d, J¼8.1 Hz), 7.42 (4H, d,
J¼8.1 Hz); 13C NMR (CDCl3, 75 MHz)
d
21.4, 111.7 (q, J¼35.5 Hz),
122.1 (q, J¼270.9 Hz), 124.7, 130.8, 136.0, 141.1, 146.9; 19F NMR
(CDCl3, 283 MHz)
d
ꢀ59.7 (d, J¼8.5 Hz); GC–MS m/z 434 (7, Mþ),
291 (3), 241 (10), 214 (6), 155 (11), 125 (100), 91 (97), 79 (59), 77
(43), 65 (17). Anal. Calcd for C20H16F6S2: C, 55.29; H, 3.71. Found: C,
55.45; H, 3.84%.
1450, 1326, 1266, 1107, 1053, 852, 811, 667 cmꢀ1
300 MHz)
1.94 (1H, t, J¼6.8 Hz), 2.40 (3H, s), 4.52 (2H, d, J¼6.6 Hz),
4.93 (1H, q, J¼8.6 Hz), 7.25 (2H, d, J¼7.9 Hz), 7.40 (2H, d, J¼8.3 Hz);
13C NMR (CDCl3, 75 MHz)
21.3, 60.7 (q, J¼2.1 Hz), 110.0 (q,
;
1H NMR (CDCl3,
3.3.1. (Z)-(1-Chloro-3,3,3-trifluoroprop-1-enyl)(p-tolyl)sulfane (8)
To a solution of 4af (370.6 mg, 0.731 mmol) in THF (3 mL)
under argon were added CuCl2 (201.7 mg, 1.50 mmol) and
Pd(OAc)2 (16.6 mg, 0.074 mmol) at 25 ꢁC, and the whole mixture
was stirred for 2 h. The reaction was quenched with water and
extracted with hexane/ethyl acetate¼3:1 solution. Additional ex-
traction was repeated twice. The combined organic solution was
dried over Na2SO4 and concentrated in vacuo. The residue was
purified bysilica gel chromatography (hexane/triethylamine¼200:1
as eluant) to give 136.9 mg of 8 as colorless oil in 74% and 31.7 mg
of 7 as a white solid in 20% yield, respectively. IR (neat) 3070,
2927, 1619, 1493, 1293, 1257, 1141, 1125, 915, 848, 810, 691,
d
d
J¼35.7 Hz), 123.1 (q, J¼270.9 Hz), 125.1, 130.9, 131.1, 140.5, 155.9 (q,
J¼5.4 Hz); 19F NMR (CDCl3, 283 MHz)
d
ꢀ56.6 (dt, J¼8.6, 2.1 Hz);
GC–MS m/z 248 (19, Mþ), 217 (18), 149 (16), 123 (17), 92 (49), 91
(100), 75 (33), 65 (26). Anal. Calcd for C11H11F3OS: C, 53.22; H, 4.47.
Found: C, 53.32; H, 4.54%.
3.6. Preparation of (E)-4,4,4-trifluoro-2-(p-tolylthio)but-2-
en-1-yl acetate (12)
667 cmꢀ1
;
1H NMR (CDCl3, 300 MHz)
d
2.40 (3H, s), 5.48 (1H, q,
To a solution of 11 (443.7 mg,1.79 mmol) in CH2Cl2 (10 mL) were
added Ac2O (0.26 mL, 2.68 mmol) and DMAP (667.0 mg,
5.37 mmol) at room temperature. After being stirred for 15 min, the
solution was concentrated to about one tenth of its original volume.
The resulting solution was directly purified by silica gel chroma-
tography (hexane/ether¼3:1 as eluant) to give 489.4 mg of 12 as
pale yellow oil in 94% yield. IR (neat) 3026, 2954, 2927, 1752, 1634,
J¼7.1 Hz), 7.26 (2H, d, J¼8.1 Hz), 7.43 (2H, d, J¼8.1 Hz); 13C NMR
(CDCl3, 75 MHz)
d
21.4, 112.6 (q, J¼36.7 Hz), 121.8 (q,
J¼270.3 Hz), 125.3, 130.9, 135.1, 141.3, 144.8 (q, J¼6.2 Hz); 19F
NMR (CDCl3, 283 MHz)
d
ꢀ59.1 (d, J¼7.5 Hz); GC–MS m/z 254
(10, Mþ 37Cl]), 252 (24, Mþ 35Cl]), 217 (10), 183 (41), 148 (90),
[ [
123 (64), 91 (48), 77 (37), 65 (100). Anal. Calcd for C10H8ClF3S:
C, 47.53; H, 3.19. Found: C, 47.57; H, 3.19%.
1326, 1268, 1222, 1163, 1114, 1062, 851, 812, 666 cmꢀ1 1H NMR
;
(CDCl3, 300 MHz) d 2.15 (3H, s), 2.40 (3H, s), 4.94 (2H, s), 4.99 (1H, q,
3.3.2. (Z)-(1-Bromo-3,3,3-trifluoroprop-1-enyl)(p-tolyl)sulfane (9)
J¼8.4 Hz), 7.26 (2H, d, J¼8.4 Hz), 7.39 (2H, d, J¼8.3 Hz); 13C NMR
Colorless oil; yield 68%; IR (neat) 3055, 2926, 1611, 1492,
(CDCl3, 75 MHz)
d
20.6, 21.3, 61.1 (q, J¼2.1 Hz), 111.7 (q, J¼35.7 Hz),
1289, 1256, 1134, 843, 810, 669 cmꢀ1
;
1H NMR (CDCl3,
122.8 (q, J¼270.6 Hz), 124.6, 130.9, 135.6, 140.7, 150.8 (q, J¼5.4 Hz),
300 MHz)
d
2.40 (3H, s), 5.72 (1H, q, J¼7.0 Hz), 7.27 (2H, d,
170.1; 19F NMR (CDCl3, 283 MHz)
d
ꢀ57.2 (dt, J¼8.2, 1.8 Hz); GC–MS
J¼8.1 Hz), 7.43 (2H, d, J¼8.1 Hz); 13C NMR (CDCl3, 75 MHz)
m/z 290 (23, Mþ), 230 (16), 161 (47), 124 (70), 105 (25), 91 (100), 77
(59), 65 (48). Anal. Calcd for C13H13F3O2S: C, 53.79; H, 4.51. Found:
C, 53.97; H, 4.62%.
d
21.4, 114.8 (q, J¼36.7 Hz), 121.9 (q, J¼270.3 Hz), 126.6, 130.9,
132.6 (q, J¼6.3 Hz), 135.0, 141.4; 19F NMR (CDCl3, 283 MHz)

2764
T. Hanamoto et al. / Tetrahedron 65 (2009) 2757–2765
3.7. Preparation of (E)-(1-bromo-4,4,4-trifluorobut-2-en-2-
yl)(p-tolyl)sulfane (13)
145.7, 165.4; 19F NMR (CDCl3, 283 MHz)
d
ꢀ62.4 (br s); GC–MS m/z
374 (0.2, Mþ), 235 (7), 219 (50), 199 (15), 159 (19), 139 (14), 109 (20),
91 (100), 66 (57), 65 (27), 59 (55). Anal. Calcd for C17H17F3O4S: C,
54.54; H, 4.58. Found: C, 54.14; H, 4.66%.
To a solution of 11 (610.3 mg, 2.46 mmol) in THF (15 mL) under
argon were added PPh3 (1.00 g, 3.45 mmol) and tetrabromo-
methane (CBr4, 1.50 g, 4.43 mmol) at once at room temperature.
After being stirred for 5 min, the reaction was quenched with sat-
urated NaHCO3 solution, and extracted with hexane/ether¼3:1.
Additional extraction was repeated twice. The combined organic
solution was washed with brine, dried over Na2SO4, and concen-
trated in vacuo. The residue was purified by silica gel chromatog-
raphy (hexane/triethylamine¼200:1 as eluant) to give 682.7 mg of
13 as pale yellow oil in 89% yield. IR (neat) 1629, 1493, 1330, 1265,
3.8.2. Methyl 6-(trifluoromethyl)-5-tosylbicyclo[2,2,2]oct-2-en-5-
carboxylate (17)
Colorless syrup; yield 40%; IR (neat) 3056, 2953, 2879, 1761,
1597, 1436, 1319, 1289, 1256, 1161, 1143, 1107, 818, 697, 669 cmꢀ1
;
1H NMR (CDCl3, 300 MHz)
d 1.20–1.45 (2H, m), 1.85–1.96 (1H, m),
2.40–2.50 (1H, m), 2.44 (3H, s), 3.00–3.15 (1H, m), 3.53 (3H, s),
3.62–3.67 (1H, m), 3.68 (1H, q, J¼10.3 Hz), 6.20–6.45 (2H, m),
7.32 (2H, d, J¼8.1 Hz), 7.70 (2H, d, J¼8.3 Hz); 13C NMR (CDCl3,
1116, 811 cmꢀ1; 1H NMR (CDCl3, 300 MHz)
d
2.40 (3H, s), 4.17 (2H, d,
75 MHz)
d
18.8, 21.7, 25.5, 31.5 (q, J¼2.9 Hz), 37.4, 48.6 (q,
J¼0.9 Hz), 5.13 (1H, q, J¼8.3 Hz), 7.26 (2H, d, J¼7.7 Hz), 7.42 (2H, d,
J¼28.4 Hz), 52.6, 80.9, 125.7 (q, J¼279.6 Hz), 129.3, 129.7, 130.1,
J¼8.1 Hz); 13C NMR (CDCl3, 75 MHz)
d
21.3, 25.4 (q, J¼1.9 Hz), 113.0
132.4, 134.4, 145.6, 165.4; 19F NMR (CDCl3, 283 MHz)
d
ꢀ62.9 (d,
(q, J¼35.5 Hz), 122.6 (q, J¼270.9 Hz), 124.9, 130.9, 135.6, 140.8, 151.5
J¼9.9 Hz); GC–MS m/z 249 (1), 233 (44), 213 (16), 185 (19), 173
(31), 155 (43), 133 (23), 127 (24), 105 (39), 91 (84), 79 (47), 77
(46), 59 (100). Anal. Calcd for C18H19F3O4S: C, 55.66; H, 4.93.
Found: C, 55.75; H, 4.93%.
(q, J¼5.6 Hz); 19F NMR (CDCl3, 283 MHz)
d
ꢀ57.6 (d, J¼8.4 Hz); GC–
MS m/z 312 (17, Mþ 81Br]), 310 (16, Mþ 79Br]), 231 (68), 211 (66),
[ [
161 (51), 123 (100), 91 (40), 79 (80), 77 (99), 69 (37), 65 (31). Anal.
Calcd for C11H10BrF3S: C, 42.46; H, 3.24. Found: C, 42.71; H, 3.28%.
3.8.3. Methyl 6-(trifluoromethyl)-3,4-dimethyl-1-tosylcyclohex-3-
en-1-carboxylate (18)
3.8. Preparation of (E)-methyl 4,4,4-trifluoro-2-tosylbut-2-
enoate (14)
White solid; yield 65%; mp 117.9–119.7 ꢁC; IR (KBr) 2954, 2928,
2862, 1741, 1322, 1276, 1156, 1109, 814, 708, 661 cmꢀ1 1H NMR
;
To a solution of 4ap (209.3 mg, 0.758 mmol) in CH2Cl2 (4 mL)
under argon was added m-CPBA (77%, 464.0 mg, 2.07 mmol) at
ꢀ78 ꢁC, and the whole mixture was stirred at this temperature for
1 h. The reaction was gently warmed to room temperature over
18 h. The reaction was quenched with saturated Na2S2O3 solution
and saturated NaHCO3 solution, successively, and extracted with
CH2Cl2. Additional extraction was repeated twice. The combined
organic solution was dried over Na2SO4 and concentrated in vacuo.
The residue was purified by silica gel chromatography (hexane/
ethyl acetate¼3:1 as eluant) to give 186.8 mg of 14 as a white solid
in 80% yield. Mp 87.3–88.9 ꢁC; IR (KBr) 3064, 2965, 1752, 1747, 1441,
(CDCl3, 300 MHz)
d
1.44 (3H, s), 1.49 (3H, s), 2.26 (1H, d, J¼17.8 Hz),
2.44 (3H, s), 2.51 (1H, d, J¼19.3 Hz), 2.79 (2H, d, J¼17.8 Hz), 3.65–
3.78 (1H, m), 3.68 (3H, s), 7.32 (2H, d, J¼8.1 Hz), 7.72 (2H, d,
J¼8.4 Hz); 13C NMR (CDCl3, 75 MHz)
d 18.2, 18.5, 21.6, 29.0
(q, J¼2.5 Hz), 31.6, 40.6 (q, J¼26.8 Hz), 53.0, 73.2, 121.9, 122.3, 126.2
(q, J¼283.2 Hz), 129.3, 129.7, 134.0, 145.6, 167.3; 19F NMR (CDCl3,
283 MHz)
d
ꢀ67.8 (d, J¼9.5 Hz); GC–MS m/z 234 (47), 213 (19), 199
(38), 175 (33), 165 (62), 155 (38), 139 (25), 121 (24), 105 (36), 91
(100), 77 (26), 65 (39), 59 (55). Anal. Calcd for C18H21F3O4S: C,
55.37; H, 5.42. Found: C, 55.31; H, 5.49%.
1343, 1328, 1295, 1274, 1236, 1187, 1151, 1082, 818, 683 cmꢀ1 1H
;
3.9. Crystal data for 15
NMR (CDCl3, 300 MHz)
d 2.48 (3H, s), 3.82 (3H, s), 6.95 (1H, q,
J¼7.0 Hz), 7.39 (2H, d, J¼8.6 Hz), 7.77 (2H, d, J¼8.6 Hz); 13C NMR
C17H17F3O4S: M¼374.37, T¼93(2) K, triclinic, space group P-1,
a¼7.810(7) Å, b¼8.731(11) Å, c¼12.978(13) Å, V¼815.1(15) Å3, Z¼2,
Dc¼1.525 Mg mꢀ3, m¼0.251 mmꢀ1, l¼0.71073 Å, qmax¼27.45ꢁ, 7946
measured reflection, 3661 independent reflections, 226 refined
(CDCl3, 75 MHz)
d
21.7, 53.7, 120.6 (q, J¼273.2 Hz), 127.8 (q,
J¼38.0 Hz), 129.2, 130.1, 134.5, 146.0 (q, J¼4.8 Hz), 146.5, 160.4; 19F
NMR (CDCl3, 283 MHz)
d
ꢀ63.2 (d, J¼7.3 Hz); GC–MS m/z 308 (0.2,
Mþ), 244 (2), 229 (2), 185 (3), 155 (11), 139 (6), 91 (100), 65 (27).
Anal. Calcd for C12H11F3O4S: C, 46.75; H, 3.60. Found: C, 46.83; H,
3.69%.
parameters,
GOF¼1.038,
R[F2>2s(F2)]¼0.0482,
wR(F2)¼
0.1337. The intensity data were collected on a Rigaku RAXIS-RAPID
diffractometer. The structure was solved by direct methods
(SIR200220) and the non-hydrogen atoms were refined anisotrop-
ically by full-matrix least-squares procedures on F2 for all re-
ductions (SHELXL9721). All hydrogen atoms were positioned
geometrically and refined as riding. CCDC-715697 contains the
supplementary crystallographic data for this paper. These data can
be obtained free of charge via www.ccdc.cam.ac.uk/data_request/
cif, or by e-mailing data_request@ccdc.cam.ac.uk, or by contacting
The Cambridge Crystallographic Data Centre, 12, Union Road,
Cambridge CB2 1EZ, UK; fax: þ44 1223 336033.
3.8.1. Methyl 6-(trifluoromethyl)-5-tosylbicyclo[2,2,1]hept-2-en-5-
carboxylate (15)
A sealed glass tube was successively charged with 14 (58.2 mg,
0.189 mmol), cyclopentadiene (77.0 mL, 0.934 mmol, freshly pre-
pared from dicyclopentadiene), and toluene (1 mL). The resulting
mixture was heated at 100 ꢁC for 2 h. After the mixture was cooled
to room temperature, toluene was evaporated at reduced pressure.
The residue was purified by silica gel chromatography (hexane/
ethyl acetate¼10:1 as eluant) to give 52.5 mg of 15 as a mixture of
two diastereomers in 74% combined yield. Major isomer 15 (endo-
CF3-adduct) was partially obtained by the second silica gel chro-
matography (hexane/ethyl acetate¼20:1 as eluant) in a pure form.
White solid; mp 129.5–130.2 ꢁC; IR (KBr) 2954, 1743, 1321, 1312,
Acknowledgements
We greatly thank F-Tech. Co., Ltd for a gift of 2-bromo-3,3,3-
trifluoropropene.
1289, 1276, 1265, 1149, 1131, 1119, 824, 707, 667 cmꢀ1
(CDCl3, 300 MHz)
;
1H NMR
d
1.54 (1H, d, J¼9.0 Hz), 2.37 (1H, d, J¼9.0 Hz),
References and notes
2.46 (3H, s), 3.27 (1H, br s), 3.51 (3H, s), 3.73 (1H, dq, J¼3.0, 9.3 Hz),
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(2H, d, J¼8.4 Hz), 7.72 (2H, d, J¼8.3 Hz); 13C NMR (CDCl3, 75 MHz)
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