A mild and efficient synthesis of buta-1,3-dienes substituted with a terminal pentafluoro-6-sulfanyl group

Article abstract of DOI:10.1055/s-0030-1258254

An efficient four-step route towards the synthesis of conjugated 1,3-dienes substituted with a terminal SF₅-group was proposed. Key steps of the synthetic sequence are the bromination of 1-(pentafluoro-λ⁶- sulfanyl)alk-1-enes followed by dehydrobromination of the corresponding products. Georg Thieme Verlag Stuttgart · New York.

Full text of DOI:10.1055/s-0030-1258254

3906
PAPER
A Mild and Efficient Synthesis of Buta-1,3-dienes Substituted with a Terminal
Pentafluoro-l6-sulfanyl Group
Maxim V. Ponomarenko,*a,b Yurii A. Serguchev,a Gerd-Volker Röschenthaler*b
a
Institute of Organic Chemistry, National Academy of Sciences of Ukraine, 5 Murmanskaya Str., 02094 Kiev, Ukraine
Fax +38(44)5732643; E-mail: maxponom@yahoo.co.uk
b
School of Engineering and Science, Jacobs University Bremen gGmbH, Campus Ring 1, 28759 Bremen, Germany
Fax +49(241)2003229; E-mail: g.roeschenthaler@jacobs-university.de
Received 25 June 2010; revised 6 July 2010
However, to the best of our knowledge only two 1,3-
Abstract: An efficient four-step route towards the synthesis of con-
dienes with a terminal SF5 group have been recently de-
jugated 1,3-dienes substituted with a terminal SF5-group was pro-
scribed. A 1-(pentafluoro-l6-sulfanyl)-1,3-diene was ob-
posed. Key steps of the synthetic sequence are the bromination of 1-
tained by dehydration of 4-(pentafluoro-l6-sulfanyl)but-
3-en-2-ol in 35–40% yield,9b and 1-chloro-1,3-diphenyl-
4-(pentafluoro-l6-sulfanyl)diene was found as a byprod-
uct of sulfur chloride pentafluoride addition to phenyl-
acetylene in 27% yield.11a
(pentafluoro-l6-sulfanyl)alk-1-enes followed by dehydrobromina-
tion of the corresponding products.
Key words: butadienes, alkenes, pentafluorosulfanyl group, elimi-
nation
Herein we propose an efficient route towards the synthesis
of conjugated 1,3-dienes substituted with a terminal SF5
group. As outlined in Scheme 1, our strategy is based on
four key steps: (i) radical addition of sulfur chloride pen-
tafluoride to olefins 1 with a terminal double bond; (ii) de-
hydrochlorination; (iii) bromination of SF5CH=CH
olefins 3 with bromine; and (iv) dehydrobromination.
It is a well-known fact that the introduction of a fluorine
atom into organic compounds often influences the biolog-
ical activity of pharmaceutical and agrochemical com-
pounds to a considerable extent.1 The pentafluoro-l6-
sulfanyl (SF5) group is a fluorine-containing substituent
that has attracted increasing interest as providing com-
pounds with low surface energy, high chemical resistance,
thermal stability, high electronegativity, and lipophilicity,
which is of significant importance especially for the agro-
chemical and pharmaceutical chemistry.2 Also a number
of patents describe the properties of pentafluoro-l6-sulfa-
nyl derivatives, such as fungicides, herbicides, and insec-
ticides.2d,f,3,4 The above-mentioned properties have often
been compared to those of the trifluoromethyl group, and
the advantages of the SF5 group have, hence, been referred
to as a ‘super CF3 function’.2a,d,f,5 The utility of pentafluo-
ro-l6-sulfanyl-substituted compounds has been noted in
the chemistry of polymeric products,6 energetic materi-
als,2b,7 liquid crystals,2a,3,8 and others.
Br
R1
SF5
iv
SF5
R3
R2
iii
Br
R2
R3 = H or Alk
R1, R2 = Alk
SF5
Cl
R1
R1
SF5
R1
ii
i
R2
R2
R2
1
2
3
iii
R
1 = H, R2 = Alk
SF5
R5
Br
iv
The introduction of a pentafluoro-l6-sulfanyl group into
organic compounds has been known for the past 50 years,
but the number of SF5-containing compounds is limited
by the availability of SF5 sources or building blocks.
SF5
R4
R2
R4 = Alk or Ph
R
5 = H or Alk
Scheme 1 General strategy for SF5-terminal substituted 1,3-dienes
The most important and convenient method for the addi-
tion of the SF5 group into organic compounds is based
upon radical addition of sulfur halide pentafluorides
SF5Hal (Hal = Cl, Br) to unsaturated substrates.9–14 Such
addition products are widely used for the synthesis of var-
ious SF5-based unsaturated compounds (SF5CH=CH-,
SF5C≡CH-), utilized in the synthesis of SF5-aromatics,15
heterocycles,2b,7,11b,16 carbocycles,9,17 and other useful
products.
The first step, the radical addition of sulfur chloride pen-
tafluoride to olefins 1a–d, was carried out by two different
procedures; UV irradiation in n-hexane or by using trieth-
ylborane (0.1 equiv) for radical initiation in dichlo-
romethane solution at –40 °C (Scheme 2, Table 1). The
method, which was proposed by Dolbier and co-workers
for improving the addition reaction of sulfur chloride pen-
tafluoride to alkenes and alkynes,11 with the use of trieth-
ylborane gave better yields of the corresponding products
2a–d (Table 1).
SYNTHESIS 2010, No. 22, pp 3906–3912
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Advanced online publication: 14.09.2010
DOI: 10.1055/s-0030-1258254; Art ID: T13810SS
© Georg Thieme Verlag Stuttgart · New York

PAPER
Synthesis of 1-(Pentafluoro-l6-sulfanyl)buta-1,3-dienes
3907
3a–d in these eliminations have been proved by 1H NMR
spectroscopy (3JHHtrans = 14.2–14.7 Hz), which in agree-
ment with the literature data for SF5-substituted ole-
fins.5,9,18
SF5Cl
(a) or (b)
Cl
R
SF5
R
1a–d
2a–d
(a) UV irradiation in n-hexane at r.t.
(b) Et3B, CH2Cl2, –40 °C
Cl
Scheme 2 Radical sulfur chloride pentafluoride addition
K2CO3, DMF
SF5
SF5
3a (91%)
3b (88%)
3c (87%)
3d (78%)
R
R
50–55 °C
10 h
2a R = Cy
2b R = i-Pr
2c R = (CH2)2Ph
2d R = CH2Cy
In most cases, pure products 2a,b,d were obtained by fil-
tration of the hexane solution through a short column of
silica gel. However, reactions of olefin 1c with sulfur
chloride pentafluoride using both methods (a) and (b) did
not give complete conversion of the starting olefin, which
was observed in the reaction mixture with product 2c,
which was separated by distillation of the reaction mixture
under reduced pressure (20 mbar).
Scheme 3 1,2-Elimination of hydrogen chloride from sulfur chlo-
ride pentafluoride adducts
In the third step, we found a difference in bromination re-
actions of the SF5-olefins 3a,b and 3c,d carried out using
bromine (1.2 equiv) in hexane solution under ambient
conditions without any special initiation. In the case of
olefins 3a,b with a dialkyl-substituted carbon in the 2-po-
sition of the 1-SF5-substituted double bond, the corre-
sponding dibromides 4a,b were obtained in high yields
(Scheme 4). In contrast to the bromination of 3a,b, the re-
action of 3c,d with bromine under the same conditions oc-
curred with the formation of allylic bromination products
4c,d (Scheme 5). The bromination reactions of 3a–d were
monitored using 19F NMR spectroscopy showing exclu-
sive formation of 4a,b and 4c,d were formed as the main
product with only minor amounts of byproducts. The
products 4c,d were isolated in pure form by column chro-
matography. The volatility of 4b meant that pentane was
found to be a better solvent for the reaction and the sepa-
ration of the pure product. The structures of 4a–d were
Table 1 Reaction of Olefins 1a–d with Sulfur Chloride Pentafluo-
ride
Starting Olefin
Time (h)
Method and yield (%)
6
2
(a) 84
(b) 95
1a
4
(b) 92
1ba
8
6
(a) 25
(b) 48
1c
proved using H, 19F, and 13C NMR spectroscopy. The
1
8
4
(a) 56
(b) 91
substituent CHBrCHBrSF5 in 4a,b forms similar groups
of multiplets in the 1H NMR spectra, namely a doublet at
d = 6.75 (JHH = 14.7 Hz) and a doublet of quintets at d =
6.52 with characteristic coupling constants JHF = 6 Hz and
JHH = 14.7 Hz for the CHSF5 proton. The 1H NMR spectra
of 4c,d exhibits multiplets of the CHBr proton at d = 4.98
and 4.23 for 4c and 4d, respectively. Multiplets of the
double bonded protons of 4c,d overlap in the d = 6.4–6.6
region. Quintets of the carbon atoms of 4a–d bound to the
SF5-group and the b-carbon atoms to SF5-group were ob-
served in the 13C NMR spectra with characteristic cou-
1d
a The volatility of olefin 1b meant that only method (b) was used.
The elimination of HCl from sulfur chloride pentafluoride
adducts has been achieved previously using various
bases.9,11,15b,17 We tested several procedures for the 1,2-
elimination from 2a and 2b. Using a large excess of potas-
sium hydroxide (10–15-fold) in hexane or diethyl ether,
the HCl elimination reaction of 2a took several weeks to
go to completion. Using lithium hydroxide monohydrate
(5 equiv) in dimethyl sulfoxide, the elimination product
3a was obtained in 72% yield after stirring at 50–55 °C for
34 hours. Treatment of 2b with potassium hydroxide and
lithium hydroxide monohydrate led to dark-colored reac-
tion mixtures in all cases, which contained SF5 product 3b
only as an admixture as observed by 19F NMR spectrosco-
py. The best results were achieved by stirring a mixture of
2a with potassium carbonate (5 equiv) in N,N-dimethyl-
formamide at 50–55 °C overnight, giving 3a in 91% yield
after workup. The latter system was used satisfactorily for
the dehydrochlorination of 2b–d (Scheme 3), where the
corresponding products can be used for the next step with-
out further purification. Formation of the trans-isomers
Br
Br2
SF5
SF5
R
R
pentane, r.t.
Br
3a R = Cy
3b R = i-Pr
4a (93%)
4b (87%)
Scheme 4 Bromination of SF5-substituted double bonds of 3a,b
SF5
SF5
Br2
R
R
hexane, r.t.
– HBr
Br
3c R = Bn
3d R = Cy
4c (75%)
4d (68%)
Scheme 5 Allylic bromination of 3c,d
Synthesis 2010, No. 22, 3906–3912 © Thieme Stuttgart · New York

3908
M. V. Ponomarenko et al.
PAPER
pling constants 2JCF = 20–21 Hz and 3JCF = 6.7–7.7 Hz in We found a dramatic distinction in the elimination of HBr
the d = 135–144 region.
from 4d using potassium carbonate or DBU as the base
(Scheme 7). After treatment of 4d with potassium carbon-
ate (5 equiv) in N,N-dimethylformamide, we separated
1,3-diene 5d in only 42% yield and 3d as a byproduct
formed as a complicated mixture of products using col-
umn chromatography.
To the best of our knowledge, elimination of two HBr
molecules from an 1,2-dibromoalkane by treatment with a
base has never been used for the synthesis of such 1,3-
dienes. We have found that HBr elimination from 4a us-
ing bases, such as DBU, LiOH·H2O, or K2CO3, leads to
the formation only of the target 1,3-diene 5a with high To our surprise, using an equimolar amount of DBU in re-
yields (Scheme 6, Table 2). Standard workup of the reac- action with 4d did not lead to the elimination product 5d,
tion, followed by filtration of a hexane solution through but gave only the product of base-induced double bond
silica gel was used effectively for purification of 5a. It migration 6 in good yield (Scheme 7). In contrast to the
might be supposed, that bisdehydrobromination from 4a reaction of 4d, 1,3-diene 5c was detected and isolated ex-
includes two steps (Scheme 6), the first a 2,3- and the next clusively in 78% yield in the reaction of 4c with DBU.
a 1,4-HBr elimination. However, we observed only the The latter can be explained by the formation of a favorable
starting dibromide 4a and the product 5a in the 1H and 19F conjugated system of 1,3-double bonds with the benzene
NMR spectra of the reaction mixture using a deficit of ring in 5c.
base for this reaction.
K2CO3, DMF
Bn
SF5
Ph
SF5
Br
50–55 °C
10 h
H
Br
5c (86%)
4c
SF5
SF5
base
K2CO3, DMF
– HBr
2,3-elimination
Br
Br
SF5
+ 3d (15%)
H
4a
50–55 °C
10 h
5d (42%)
– HBr
1,4-elimination
base
Cy
Cy
Br
DBU, hexane
r.t., 12 h
SF5
Br
SF5
SF5
SF5
4d
5a
Br
DBU
(2.1 equiv)
SF5
Cy
Br
SF5
n-heptane
reflux, 4h
Br
4b
6 (72%)
5b (28%, 74% by 19F NMR)
Scheme 7 Dehydrobromination of 4c,d
Scheme 6 Bisdehydrobromination of 4a,b
We have found only several other examples of double
bond migration in substituted allyl chlorides that are sim-
ilar to the reaction of 4d with DBU.19 Recently V. Brel
and co-workers described one example of nucleophile-
induced double bond migration in the reaction of 3-chlo-
ro-1-(pentafluorosulfanyl)prop-1-ene with a CN– anion.19b
Treatment of 4d with lithium hydroxide monohydrate in
dimethyl sulfoxide yielded only 2–3% of 3d and a mixture
of decomposition products.
Table 2 Elimination of Hydrogen Bromide from 4a
Conditions
Time (h) Yielda (%) of 5a
K2CO3 (10 equiv), DMF, 55 °C
LiOH (10 equiv), DMSO, 55 °C
DBU (2.1 equiv), n-heptane, reflux
a After silica gel chromatography.
10
10
5
87
76
72
In the 19F NMR spectra of 5a–d the typical appearance of
the AB4-spin system for structurally non-equivalent fluo-
rine atoms2,5 of the SF5 substituent was observed with nine
lines for the axial fluorine atom (A-part) at d = 84.3–87.0
and a doublet of multiplets of the equatorial fluorines (B4-
part) at d = 64.3–64.8 (JFF = 148–150 Hz and JHF = 5.8–
6.9 Hz). The quintets of carbon atoms of the CHSF5 group
For the dehydrobromination reaction of the dibromide 4b,
DBU afforded better results than the other bases. In the 19F
NMR spectrum of the corresponding mixture of products,
1,3-diene 5b was observed in 74% yield, but it was isolat-
ed only in 28% yield after distillation and subsequent col-
umn chromatography. Using potassium carbonate for the
HBr elimination from 4b led to an increase in the reaction
time, up to 3–4 days, and a more complicated mixture of
products, as observed by 19F NMR. Treatment of 4b with
lithium hydroxide monohydrate in dimethyl sulfoxide
gave only the decomposition mixture of products without
the SF5 group. Elimination of HBr from 4c with potassium
carbonate (5 equiv) in N,N-dimethylformamide gave 1,3-
diene 5c in good yield (Scheme 7).
2
(d = 136.3–141.1 with J = 19–24 Hz), quintets of b-car-
bon atoms to the SF5 substituent (d = 132.0–139.8 with
3J = 6.7–7.7 Hz), and singlets of the C3=C4 atoms (d =
116.5–154.8) of the corresponding 1-SF5-1,3-dienes 5a–d
1
were observed in the 13C NMR spectra. The H NMR
spectra of products 5a–d show characteristic doublet of
quintets of the CHSF5 proton at d = 6.37–6.65 with
3JHHtrans = 13.7–15.1 Hz and 3JHF = 5.8–6.9 Hz.
Synthesis 2010, No. 22, 3906–3912 © Thieme Stuttgart · New York

PAPER
Synthesis of 1-(Pentafluoro-l6-sulfanyl)buta-1,3-dienes
3909
13C NMR (100 MHz, CDCl3): d = 76.3 (quint, J = 13.6 Hz, CSF5),
61.3 (quint, J = 3.7 Hz, CCl), 44.3 (Cy), 30.3 (Cy), 27.3 (Cy), 26.3
(Cy), 26.1 (Cy).
19F NMR (376 MHz, CDCl3): d = 88.3 (9 lines, A-part), 70.7 (dm,
J = 146.5 Hz, B4-part).
The most useful tool for the confirmation of structure of
the product 6 is H NMR spectroscopy. A triplet for the
proton of the double bond at d = 5.95 (J = 7.3 Hz) and sex-
tet of the CH2SF5 group at d = 4.48 (JHF and HH = 7.3 Hz) in
the 1H NMR spectrum of 6 are clearly resolved.
1
MS (CI+, NH3): m/z (%) = 126 (10), 109 (100) [M – SF5H – Cl]+, 83
In conclusion, we have developed a convenient and effi-
cient four-step method for the preparation of novel 1-
(pentafluoro-l6-sulfanyl)-1,3-dienes 5a–d. It was shown
that olefins with dialkyl-substituted carbons in the second
positions of the 1-SF5-double bonds (3a,b) led to the ad-
dition products of bromine to the double bond (4a,b) in
contrast to the allylic bromination of 1-SF5-2-CH2Alk-
substituted olefins 3c,d under the same reaction condi-
tions. The choice of base for HBr elimination from 4a–d
depends on structure of these products. In all cases, the
treatment of 4a–d with potassium carbonate led to the de-
sired 1-(pentafluoro-l6-sulfanyl)-1,3-dienes 5a–d. In case
of the elimination of HBr from 4b, DBU gave better yield
of 5b than potassium carbonate, but reaction of DBU with
4d led to the unexpected formation of base-induced dou-
ble bond migration product 6. Future studies on opportu-
nities of this double bond migration are in progress.
Synthetic application of 1-(pentafluoro-l6-sulfanyl)-1,3-
dienes 5a–d, 1,2-dibromides 4a,b, and 6 will be reported
in due course.
(20).
Anal. Calcd for C8H14ClF5S: C, 35.23; H, 5.17; Cl, 13.00; S, 11.76.
Found: C, 35.20; H, 5.18; Cl, 12.91; S, 11.77.
2-Chloro-3-methyl-1-(pentafluoro-l6-sulfanyl)butane (2b)
Colorless oil.
1H NMR (400 MHz, CDCl3): d = 4.34 (td, J = 6.0, 3.2 Hz, 1 H,
CHCl), 3.88–4.01 (m, JHF = 7.2 Hz, 2 H, CH2SF5), 2.14 (sept d,
J = 6.4, 3.2 Hz, 1 H, CH), 1.07 (d, J = 6.4 Hz, 3 H, CH3), 0.98 (d,
J = 6.4 Hz, 3 H, CH3).
13C NMR (100 MHz, CDCl3): d = 75.9 (quint, J = 13.4 Hz, C1),
61.7 (quint, J = 3.8 Hz, C2), 33.9 (CH), 19.9 (CH3), 16.1 (CH3).
19F NMR (376 MHz, CDCl3): d = 83.6 (9 lines, A-part), 66.3 (dt,
J = 145.9, 7.2 Hz, B4-part).
Anal. Calcd for C5H10ClF5S: C, 25.81; H, 4.33; Cl, 15.21; S, 13.78.
Found: C, 25.78; H, 4.30; Cl, 5.12; S, 13.74.
[3-Chloro-4-(pentafluoro-l6-sulfanyl)butyl]benzene (2c)
Colorless oil; bp 121–123 °C/20 mbar.
1H NMR (400 MHz, CDCl3): d = 7.28–7.34 (m, 2 H, Ph), 7.17–7.26
(m, 3 H, Ph), 4.29 (dtd, J = 9.2, 6.0, 3.2 Hz, 1 H, CHCl), 4.02 (m,
JHF = 8.2 Hz, 1 HA, CH2SF5), 3.90 (m, JHF = 8.2 Hz, 1 HB, CH2SF5),
2.93 (ddd, J = 14.2, 9.2, 5.0 Hz, 1 HA, CH2), 2.77 (ddd, J = 14.2,
8.7, 7.3 Hz, 1 HB, CH2), 2.28 (m, J = 14.2, 3.2 Hz, 1 HA, CH2), 2.06
(dtd, J = 14.2, 9.2, 5.0 Hz, 1 HB, CH2).
13C NMR (100 MHz, CDCl3): d = 139.8 (Ph), 128.8 (Ph), 128.6
(Ph), 126.6 (Ph), 76.9 (quint, J = 14.4 Hz, CH2SF5), 55.1 (quint,
J = 4.8 Hz, CHCl), 39.1 (CH2), 32.3 (CH2).
1
The H (399.78 MHz), 13C (100.53 MHz), and 19F (376.17 MHz)
NMR spectra were recorded on a Jeol ECX-400 spectrometer using
CDCl3 as solvent and TMS or CCl3F as internal standards. MS (EI)
were obtained on a Varian MAT CH7A instrument at 70 eV.
Alkenes 1a–d and SF5Cl were purchased from Acros, Sigma-
Aldrich, and ABCR. Column chromatography was performed on
Kieselgel Merck 60 (230–400 mesh) using hexane.
19F NMR (376 MHz, CDCl3): d = 83.3 (9 lines, A-part), 62.9 (dt,
J = 145.2, 8.2 Hz, B4-part).
MS (EI): m/z (%) = 294 (7) [M]+, 131 (28) [M – HCl – SF5]+, 91
2-Chloro-1-(pentafluoro-l6-sulfanyl)alkanes 2a,c,d; General
Procedure Using UV Irradiation
A mixture of olefin 1a–d (0.012 mol) and SF5Cl (0.018 mol) in an-
hyd n-hexane (20 mL) contained in a quartz tube were irradiated for
6–8 h with a high-pressure Hg vapor lamp at r.t. Volatiles were re-
moved by evaporation giving the crude products 2a,c,d. The pure
products were isolated by column chromatography (silica gel, n-
hexane or pentane) (see Table 1).
(100).
Anal. Calcd for C10H12ClF5S: C, 40.75; H, 4.10; Cl, 12.03; S, 10.88.
Found: C, 40.71; H, 4.08; Cl, 11.89; S, 10.89.
[2-Chloro-3-(pentafluoro-l6-sulfanyl)propyl]cyclohexane (2d)
Colorless oil.
1H NMR (400 MHz, CDCl3): d = 4.42 (dtd, J = 10.0, 6.0, 3.2 Hz, 1
H, HCCl), 3.93–4.08 (m, JHF = 8.2 Hz, 1 HA, CH2SF5), 3.79–4.93
(m, JHF = 8.2 Hz, 1 HB, CH2SF5), 1.50–1.85 (m, 7 H), 1.08–1.35 (m,
4 H, Cy), 0.98 (m, 1 H, Cy), 0.85 (m, 1 H, Cy).
13C NMR (100 MHz, CDCl3): d = 77.6 (quint, J = 12.5 Hz,
CH2SF5), 53.6 (quint, J = 4.8 Hz, CHCl), 45.2 (CH2), 34.5 (Cy),
33.7 (Cy), 31.5 (Cy), 26.4 (Cy), 26.2 (Cy), 25.9 (Cy).
19F NMR (376 MHz, CDCl3): d = 83.5 (9 lines, A-part), 66.4 (dt,
J = 145.9, 8.2 Hz, B4-part).
MS (EI): m/z (%) = 123 (31) [M – HCl – SF5]+, 83 (100), 81 (32),
2-Chloro-1-(pentafluoro-l6-sulfanyl)alkanes 2a–d; General
Procedure Using Triethylborane
To a 3-necked flask equipped with a dry ice reflux condenser and a
N2 inlet was added olefin 1a–d (0.012 mol) in anhyd CH2Cl2 (40
mL) and it was cooled to –40 °C. Then SF5Cl (0.018 mol) was con-
densed into the soln. The soln was stirred at –40 °C and 1 M Et3B
in n-hexane (1.2 mL) was added slowly using a syringe. The soln
was stirred vigorously for 2–6 h at –30 °C, and then the mixture was
warmed up to r.t. The mixture was hydrolyzed with 10% aq
NaHCO3 and the organic layer was dried (Na2SO4). The solvent was
removed, and the purity products 2a–d were isolated by column
chromatography (silica gel, pentane) (see Table 1).
55 (85).
Anal. Calcd for C9H16ClF5S: C, 37.70; H, 5.62; Cl, 12.36; S, 11.18.
Found: C, 37.68; H, 5.60; Cl, 12.24; S, 11.20.
[1-Chloro-2-(pentafluoro-l6-sulfanyl)ethyl]cyclohexane (2a)
Colorless oil.
1H NMR (400 MHz, CDCl3): d = 4.31 (m, J = 4.4 Hz, 1 H, CHCl),
3.81–4.12 (m, JHF = 7.2 Hz, 2 H, CH2SF5), 1.56–1.95 (m, 6 H, Cy),
1.05–1.45 (m, 5 H, Cy).
1-(Pentafluoro-l6-sulfanyl)alk-1-enes 3a–d from 2a–d; General
Procedure
To a soln of 2a–d (4.23 mmol) in DMF (20 mL) was added K2CO3
(21 mmol, 5 equiv). The mixture was stirred at 50–55 °C for 10 h
Synthesis 2010, No. 22, 3906–3912 © Thieme Stuttgart · New York

3910
M. V. Ponomarenko et al.
PAPER
and then the mixture was poured into H2O (~100 mL) and extracted
with n-hexane (4 × 20 mL). The organic layers were combined,
washed with brine, and dried (Na2SO4). The solvent was removed,
and the residue was purified by chromatography (silica gel, n-hex-
ane or pentane), giving pure alkenes 3a–d (Scheme 3).
Anal. Calcd for C9H15F5S: C, 43.19; H, 6.04; S, 12.81. Found: C,
43.11; H, 6.01; S, 12.83.
1,2-Dibromo-1-(pentafluoro-l6-sulfanyl)alkanes 4a,b and 3-
Bromo-1-(pentafluoro-l6-sulfanyl)alk-1-enes 4c,d; General
Procedure
A soln of 3a–d (10.8 mmol) in n-hexane or pentane (50 mL) was
stirred with Br2 (13 mmol) at r.t. for 12 h. Volatiles were removed
and the crude products were purified by chromatography (silica gel,
n-hexane or pentane) giving pure 4a–d (Schemes 4 and 5).
[(E)-2-(Pentafluoro-l6-sulfanyl)vinyl]cyclohexane (3a)
Colorless oil; yield: 91%.
1H NMR (400 MHz, CDCl3): d = 6.21–6.57 (m, 2 H, CH=CH), 2.13
(m, 1 H, Cy), 1.60–1.92 (m, 5 H, Cy), 1.00–1.45 (m, 5 H, Cy).
13C NMR (100 MHz, CDCl3): d = 144.3 (quint, J = 6.8 Hz, C2),
139.5 (quint, J = 19.2 Hz, CSF5), 39.7 (Cy), 32.0 (Cy), 26.1 (Cy),
26.0 (Cy).
[1,2-Dibromo-2-(pentafluoro-l6-sulfanyl)ethyl]cyclohexane
(4a)
Colorless oil; yield: 93%; bp 97–99 °C/20 mbar.
19F NMR (376 MHz, CDCl3): d = 84.3 (9 lines, A-part), 62.6 (dm,
J = 153.4 Hz, B4-part).
1H NMR (400 MHz, CDCl3): d = 6.75 (d, J = 14.7 Hz, 1 H, H1),
6.52 (d quint, JHH = 14.7 Hz, JHF = 6.0 Hz, 1 H, H2), 2.00–2.30 (m,
2 H, Cy), 1.56–1.80 (m, 8 H, Cy), 1.29 (m, 1 H, Cy).
13C NMR (100 MHz, CDCl3): d = 143.9 (quint, J = 6.8 Hz, C1),
139.5 (quint d, J = 20.8, 1.5 Hz, C2), 66.1 (Cy), 39.7 (Cy), 25.3
(Cy), 23.2 (Cy).
MS (CI+, NH3): m/z (%) = 217 (18) [M – F]+, 126 (28), 109 (100)
[M – SF5H]+, 81 (18), 67 (28).
Anal. Calcd for C8H13F5S: C, 40.67; H, 5.55; S, 13.57. Found: C,
40.61; H, 5.51; S, 13.55.
19F NMR (376 MHz, CDCl3): d = 83.0 (9 lines, A-part), 64.0 (dd,
J = 150.3, 6.0 Hz, B4-part).
(1E)-3-Methyl-1-(pentafluoro-l6-sulfanyl)but-1-ene (3b)
Colorless oil; yield: 88%.
MS (EI): m/z (%) = 393 (10) [M – H]+, 395 (15) [M – H + 2]+, 397
1H NMR (400 MHz, CDCl3): d = 6.46 (dd, J = 14.7, 6.4 Hz, 1 H,
H2), 6.36 (d quint, JHH = 14.7 Hz, JHF = 5.8 Hz, 1 H, H1), 2.44 (m,
1 H, H3), 1.08 (d, J = 6.9 Hz, 6 H, CH3).
13C NMR (100 MHz, CDCl3): d = 145.1 (quint, J = 6.7 Hz, C2),
138.8 (quint, J = 19.2 Hz, C1), 30.1 (CH), 21.1 (CH3).
19F NMR (376 MHz, CDCl3): d = 84.7 (9 lines, A-part), 63.2 (dd,
J = 148.8, 5.8 Hz, B4-part).
(10) [M – H + 4]+, 127 (100) [SF5], 81 (42) [Br]+, 79 (42) [Br]+.
Anal. Calcd for C8H13Br2F5S: C, 24.26; H, 3.31; Br, 40.35; S, 8.10.
Found: C, 24.25; H, 3.29; Br, 40.21; S, 8.09.
1,2-Dibromo-3-methyl-1-(pentafluoro-l6-sulfanyl)butane (4b)
Colorless oil; yield: 87%.
1H NMR (400 MHz, CDCl3): d = 6.77 (d, J = 14.7 Hz, 1 H, H2),
6.52 (d quint, JHH = 14.7 Hz, JHF = 6.0 Hz, 1 H, H1), 1.90 (s, 6 H,
CH3), 1.75–2.01 (m, 1 H, CH).
Anal. Calcd for C5H9F5S: C, 30.61; H, 4.62; S, 16.34. Found: C,
30.62; H, 4.63; S, 16.29.
13C NMR (100 MHz, CDCl3): d = 144.1 (quint, J = 6.7 Hz, C2),
138.6 (quint, J = 21.1 Hz, C1), 57.1 (CH), 32.7 (CH3).
19F NMR (376 MHz, CDCl3): d = 82.7 (9 lines, A-part), 64.0 (dd,
J = 150.3, 6.0 Hz, B4-part).
[(3E)-4-(Pentafluoro-l6-sulfanyl)but-3-enyl]benzene (3c)
Colorless oil; yield: 87%.
1H NMR (400 MHz, CDCl3): d = 7.10–7.40 (m, 5 H, Ph), 6.52 (dt,
J = 14.2, 6.8 Hz, 1 H, SF5CH=CH), 6.39 (d quint, JHH = 14.2 Hz,
JHF = 5.8 Hz, 1 H, SF5CH), 2.73–2.81 (m, 2 H, PhCH2), 2.43–2.52
(m, 2 H, CH2).
MS (EI): m/z (%) = 195 (100) [M – HBr – Br]+, 87 (45), 67 (25)
[M – 2 HBr – SF5]+.
Anal. Calcd for C5H9Br2F5S: C, 16.87; H, 2.55; Br, 44.89; S, 9.01.
Found: C, 16.90; H, 2.58; Br, 44.65; S, 8.98.
13C NMR (100 MHz, CDCl3): d = 141.1 (quint, J = 19.2 Hz,
HCSF5), 140.1 (Ph), 138.1 (quint, J = 6.7 Hz, HC=CHSF5), 128.7
(Ph), 128.5 (Ph), 126.6 (Ph), 34.3 (CH2), 32.4 (CH2).
19F NMR (376 MHz, CDCl3): d = 84.3 (9 lines, A-part), 62.9 (dd,
J = 153.2, 5.8 Hz, B4-part).
[(3E)-2-Bromo-4-(pentafluoro-l6-sulfanyl)but-3-enyl]benzene
(4c)
Colorless oil; yield: 75%.
1H NMR (400 MHz, CDCl3): d = 7.28–7.48 (m, 5 H, Ph), 6.47 (m,
J = 6.0 Hz, 1 H, SF5CH=CH), 6.40–6.52 (m, 1 H, SF5CH), 4.98 (dd,
J = 8.7, 6.0 Hz, 1 H, BrCH), 3.03–3.40 (m, 1 HB, CH2), 2.94–3.03
(m, 1 HA, CH2).
13C NMR (100 MHz, CDCl3): d = 143.0 (quint, J = 20.1 Hz,
HCSF5), 140.4 (Ph), 135.0 (quint, J = 7.7 Hz, HC=CHSF5), 129.0
(Ph), 127.2 (Ph), 51.4 (CHBr), 40.8 (CH2).
MS (EI): m/z (%) = 131 (30) [M – SF5]+, 91 (100).
Anal. Calcd for C10H11F5S: C, 46.51; H, 4.29; S, 12.42. Found: C,
46.47; H, 4.26; S, 12.41.
[(2E)-3-(Pentafluoro-l6-sulfanyl)prop-2-enyl]cyclohexane (3d)
Colorless oil; yield: 78%.
1H NMR (400 MHz, CDCl3): d = 6.47 (dt, J = 14.4, 6.9 Hz, 1 H,
SF5CH=CH), 6.37 (d quint, JHH = 14.4 Hz, JHF = 6.0 Hz, 1 H,
SF5CH), 2.02 (m, 2 H, HCBr), 1.55–1.78 (m, 5 H, Cy), 1.41 (m, 1
H, Cy), 1.10–1.31 (m, 3 H), 0.80–1.00 (m, 2 H, Cy).
13C NMR (100 MHz, CDCl3): d = 141.0 (quint, J = 19.2 Hz,
HCSF5), 138.0 (quint, J = 6.7 Hz, HC=CHSF5), 38.3 (Cy), 37.1
(Cy), 32.9 (Cy), 26.3 (Cy), 26.2 (Cy).
19F NMR (376 MHz, CDCl3): d = 84.7 (9 lines, A-part), 62.9 (dd,
J = 150.3, 6.0 Hz, B4-part).
MS (EI): m/z (%) = 123 (10) [M – SF5]+, 121 (15), 83 (76), 81 (40),
19F NMR (376 MHz, CDCl3): d = 83.1 (9 lines, A-part), 62.6 (dm,
J = 148.7 Hz, B4-part).
MS (EI): m/z (%) = 257 (32) [M – SF5]+,256 (35) [M – HSF5]+, 130
(30) [M – BrSF5]+, 129 (100) [M – HBr – SF5]+.
Anal. Calcd for C10H10BrF5S: C, 35.62; H, 2.99; Br, 23.70; S, 9.51.
Found: C, 35.59; H, 2.97; Br, 23.45; S, 9.53.
[(2E)-1-Bromo-3-(pentafluoro-l6-sulfanyl)prop-2-enyl]cyclo-
hexane (4d)
Colorless oil; yield: 68%.
55 (100).
Synthesis 2010, No. 22, 3906–3912 © Thieme Stuttgart · New York

PAPER
Synthesis of 1-(Pentafluoro-l6-sulfanyl)buta-1,3-dienes
3911
1H NMR (400 MHz, CDCl3): d = 6.55 (m, J = 6.9 Hz, 1 H,
SF5CH=CH), 6.49–6.60 (m, 1 H, SF5CH), 4.23 (t, J = 6.9 Hz, 1 H,
HCBr), 1.95 (m, 1 H, Cy), 1.54–1.93 (m, 5 H, Cy), 0.98–1.35 (m, 5
H, Cy).
13C NMR (100 MHz, CDCl3): d = 141.4 (quint, J = 20.1 Hz,
HCSF5), 137.3 (quint, J = 7.7 Hz, HC=CHSF5), 55.8 (BrCH), 44.1
(Cy), 30.6 (Cy), 30.5(Cy), 26.0 (Cy), 25.9 (Cy), 25.8 (Cy).
19F NMR (376 MHz, CDCl3): d = 82.4 (9 lines, A-part), 63.4 (dm,
J = 148.8, B4-part).
MS (EI): m/z (%) = 121 (100) [M – HSF5 – HBr]+, 93 (85), 83 (80),
Anal. Calcd for C5H7F5S: C, 30.93; H, 3.63; S, 16.51. Found: C,
30.89; H, 3.58; S, 16.48.
[(1E,3E)-4-(Pentafluoro-l6-sulfanyl)buta-1,3-dienyl]benzene
(5c)
White solid; yield: 86%; mp 41–42 °C.
1H NMR (400 MHz, CDCl3): d = 7.46–7.42 (m, 2 H, Ph), 7.40–7.30
(m, 3 H, Ph), 7.04 (dd, J = 13.7, 11.5 Hz, 1 H, SF5CH=CH), 6.89 (d,
J = 15.6 Hz, 1 H, PhCH), 6.65 (dd, J = 15.6, 11.5 Hz, 1 H,
PhCH=CH), 6.65 (d quint JHH = 13.7 Hz, JHF = 5.7 Hz, 1 H,
SF5CH).
13C NMR (100 MHz, CDCl3): d = 141.3 (PhCH), 141.1 (quint,
J = 20.1 Hz, HCSF5), 136.7 (quint, J = 7.7 Hz, HC=CHSF5), 135.6
(Ph), 129.4 (Ph), 128.9 (Ph), 127.2 (Ph), 122.6 (PhCH=CH).
81 (35), 79 (50), 55 (34).
Anal. Calcd for C9H14BrF5S: C, 32.84; H, 4.29; Br, 24.27; S, 9.74.
Found: C, 32.81; H, 4.27; Br, 24.01; S, 9.71.
19F NMR (376 MHz, CDCl3): d = 84.7 (9 lines, A-part), 64.5 (dd,
J = 150.3, 5.8 Hz, B4-part).
MS (EI): m/z (%) = 256 (83) [M]+, 237 (38) [M – F]+, 147 (17), 129
(100) [M – HSF5]+, 128 (98) [PhC4H3]+, 127 (30), 102 (10)
[PhC2H]+.
1-(Pentafluoro-l6-sulfanyl)alka-1,3-diene 5a,c,d by Dehydro-
bromination with Potassium Carbonate; General Procedure
To a soln of 4a,c,d (4.23 mmol) in DMF (20 mL) was added K2CO3
(42 mmol, 10 equiv, for 4a and 21 mmol, 5 equiv, for 4c,d). The
mixture was stirred at 55 °C for 10 h, and then the mixture was
poured into ice water (~100 mL), extracted with n-hexane (4 × 20
mL). The organic layers were combined, washed with brine, and
dried (Na2SO4). The solvent was removed under reduced pressure,
and then the residue were purified by chromatography (silica gel, n-
hexane) to give 1,3-dienes 5a,c,d (Schemes 6 and 7, Table 2).
Anal. Calcd for C10H9F5S: C, 46.87; H, 3.54; S, 12.51. Found: C,
46.85; H, 3.52; S, 12.49.
[(2E)-3-(Pentafluoro-l6-sulfanyl)prop-2-enylidene]cyclohex-
ane (5d)
Colorless oil; yield: 42%.
(1E)-3-Methyl-1-(pentafluoro-l6-sulfanyl)buta-1,3-diene (5b)
by Dehydrobromination of 4b with DBU
1H NMR (400 MHz, CDCl3): d = 7.17 (dd, J = 13.7, 11.5 Hz, 1 H,
SF5CH=CH), 6.37 (d quint, JHH = 13.7 Hz, JHF = 6.9 Hz, 1 H,
SF5CH), 5.71 (d, J = 11.5 Hz, 1 H, HC=Cy), 2.32 (m, 2 H, Cy), 2.21
(m, 2 H, Cy), 1.50–1.85 (m, 3 H, Cy), 1.05–1.31 (m, 3 H, Cy).
13C NMR (100 MHz, CDCl3): d = 154.8 (Cy), 139.6 (quint, J = 19.2
Hz, HCSF5), 132.0 (quint, J = 7.7 Hz, HC=CHSF5), 116.5 (CH),
37.8 (Cy), 29.8 (Cy), 28.5 (Cy), 27.8 (Cy), 26.5 (Cy).
A soln of 4b (8.8 mmol) and DBU (18.5 mmol) in n-heptane (20
mL) was refluxed for 4 h. Then the mixture was diluted with pen-
tane (40 mL), washed with H2O (4 × 10 mL), and dried (Na2SO4).
The solvents were removed by distillation giving the crude mixture.
Distillation under static vacuum and subsequent column chroma-
tography (silica gel; pentane) gave 5b in 28% yield (Scheme 6).
19F NMR (376 MHz, CDCl3): d = 85.8 (9 lines, A-part), 64.8 (dd,
J = 151.7, 6.9 Hz, B4-part).
1-[(E)-2-(Pentafluoro-l6-sulfanyl)vinyl]cyclohexene (5a)
Colorless oil; yield: 87%.
MS (EI): m/z (%) = 248 (43) [M]+, 229 (35) [M – F]+, 121 (100) [M
1H NMR (400 MHz, CDCl3): d = 6.86 (d, J = 14.7 Hz, 1 H,
SF5CH=CH), 6.38 (d quint, JHH = 14.7 Hz, JHF = 6.8 Hz, 1 H,
SF5CH), 6.13 (br s, 1 H, Cy), 2.20 (m, 2 H, Cy), 2.05 (m, 2 H, Cy),
1.69 (m, 2 H, Cy), 1.63 (m, 2 H, Cy).
– HSF5]+, 93 (82) [M – HSF5 – C2H4]+, 81 (48), 79 (88), 67 (88).
Anal. Calcd for C9H13F5S: C, 43.54; H, 5.28; S, 12.92. Found: C,
43.43; H, 5.26; S, 12.93.
13C NMR (100 MHz, CDCl3): d = 139.8 (quint, J = 7.7 Hz,
HC=CHSF5), 139.3 (CH in Cy), 136.3 (quint, J = 19.2 Hz, HCSF5),
132.0 (Cy), 26.4 (Cy), 23.9 (Cy), 21.9 (Cy), 21.8 (Cy).
19F NMR (376 MHz, CDCl3): d = 87.0 (9 lines, A-part), 64.8 (dd,
J = 148.8, 6.8 Hz, B4-part).
[(1E)-1-Bromo-3-(pentafluoro-l6-sulfanyl)prop-1-enyl]cyclo-
hexane (6) from Reaction of 4d with DBU
A soln of 4d (8.8 mmol) and DBU (8.8 mmol) in n-hexane (20 mL)
was stirred at r.t. for 12 h. Then the mixture was diluted with n-hex-
ane (40 mL), washed with H2O (4 × 10 mL), and dried (Na2SO4).
The solvents were removed under reduced pressure giving the crude
product. Column chromatography (silica gel; pentane) gave 5b in
72% yield (Scheme 7).
1H NMR (400 MHz, CDCl3): d = 5.95 (t, J = 7.3 Hz, 1 H, CBrCH),
4.48 (sext, J = 7.3 Hz, 2 H, SF5CH2), 2.28 (m, 1 H, Cy), 1.52–1.90
(m, 5 H, Cy), 1.11–1.40 (m, 5 H, Cy).
13C NMR (100 MHz, CDCl3): d = 144.2 (CBr), 116.1 (quint, J = 3.8
Hz, HCCH2SF5), 72.4 (quint, J = 16.3 Hz, H2CSF5), 49.4 (CH in
Cy), 32.0 (Cy), 25.9 (Cy), 25.9 (Cy).
19F NMR (376 MHz, CDCl3): d = 82.3 (9 lines, A-part), 65.8 (dt,
J = 145.9, 7.3 Hz, B4-part).
MS (EI): m/z (%) = 234 (46) [M]+, 233 (30) [M – H]+, 107 (70) [M
– SF5]+, 91 (65), 79 (100).
Anal. Calcd for C8H11F5S: C, 41.02; H, 4.73; S, 13.69. Found: C,
41.00; H, 4.71; S, 13.67.
(1E)-3-Methyl-1-(pentafluoro-l6-sulfanyl)buta-1,3-diene (5b)
Colorless oil; yield: 28%.
1H NMR (400 MHz, CDCl3): d = 6.95 (d, J = 15.1 Hz, 1 H,
SF5CH=CH), 6.47 (d quint, JHH = 15.1 Hz, JHF = 6.4 Hz, 1 H,
SF5CH), 5.37 (br s, 1 H, CH2), 5.35 (br s, 1 H, CH2), 1.83 (s, 3 H,
CH3).
13C NMR (100 MHz, CDCl3): d = 139.6 (quint, J = 21.1 Hz,
HCSF5), 139.0 (quint, J = 6.7 Hz, HC=CHSF5), 137.8 (C3), 125.4
(CH2), 20.5 (CH3).
19F NMR (376 MHz, CDCl3): d = 84.3 (9 lines, A-part), 64.3 (dd,
J = 150.3, 6.4 Hz, B4-part).
MS (EI): m/z (%) = 121 (100) [M – HBr – SF5]+, 93 (81), 79 (45),
67 (28).
Anal. Calcd for C9H14BrF5S: C, 32.84; H, 4.29; Br, 24.27; S, 9.74.
Found: C, 32.79; H, 4.28; Br, 24.04; S, 9.70.
Synthesis 2010, No. 22, 3906–3912 © Thieme Stuttgart · New York

3912
M. V. Ponomarenko et al.
PAPER
(6) (a) St. Clair, T. L.; St. Clair, A. K.; Thrasher, J. S. US
Acknowledgment
5,220,070, 1993. (b) Winter, R. W.; Nixon, P. G.; Gard, G.
L.; Castner, D. G.; Holcomb, N. R.; Hu, Y.-H.; Grainger, D.
W. Chem. Mater. 1999, 11, 3044.
This work was supported by the Deutsche Forschungsgemeinschaft
(436 UKR 113/99/0-1).
(7) Abe, T.; Tao, G.-H.; Joo, Y.-H.; Winter, R. W.; Gard, G. L.;
Shreeve, J. M. Chem. Eur. J. 2009, 15, 9897.
(8) (a) Nishino, S.; Shima, H.; Omata, Y.; Oda, H. WO
2009,028,514, 2009. (b) Kirsch, P.; Tarumi, K.; Krause, J.
DE 19,748,108, 1999.
(9) (a) Brel, V. K. J. Fluorine Chem. 2007, 128, 862. (b) Brel,
V. K. Synthesis 2005, 1245. (c) Brel, V. K. Synthesis 2006,
339.
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Synthesis 2010, No. 22, 3906–3912 © Thieme Stuttgart · New York