A general method for the preparation of perfluoroalkanesulfonyl chlorides

Article abstract of DOI:10.1016/j.jfluchem.2005.05.007

A mild two-step synthesis of perfluoroalkanesulfonyl chlorides starting from perfluoroalkyl iodides has been developed. Reaction of perfluoroalkyl iodides with sodium dithionite gave sodium perfluoroalkanesulfinate salts which were converted into perfluoroalkanesulfonyl chlorides in 25-73% yield (two steps) using N-chlorosuccinimide.

Full text of DOI:10.1016/j.jfluchem.2005.05.007

Journal of Fluorine Chemistry 126 (2005) 1196–1201
www.elsevier.com/locate/fluor
A general method for the preparation of
perfluoroalkanesulfonyl chlorides
Peter J.H. Scott a, Ian B. Campbell b, Patrick G. Steel a,
*
a Department of Chemistry, University of Durham, South Road, Durham, DH1 3LE, UK
b GlaxoSmithKline, Gunnels Wood Road, Stevenage, Herts., SG1 2NY, UK
Received 26 April 2005; received in revised form 21 May 2005; accepted 26 May 2005
Available online 28 June 2005
Abstract
A mild two-step synthesis of perfluoroalkanesulfonyl chlorides starting from perfluoroalkyl iodides has been developed. Reaction of
perfluoroalkyl iodides with sodium dithionite gave sodium perfluoroalkanesulfinate salts which were converted into perfluoroalkanesulfonyl
chlorides in 25–73% yield (two steps) using N-chlorosuccinimide.
# 2005 Elsevier B.V. All rights reserved.
Keywords: Perfluoroalkanesulfonyl chlorides; N-chlorosuccinimide
1. Introduction
fluoroalkyl iodides using mild conditions which are tolerant
of a range of functionalities.
Perfluoroalkanesulfonyl chlorides are common reagents
in synthetic chemistry and are used to introduce perfluor-
oalkanesulfonyl groups into organic molecules. Tradition-
ally, they have been used in the preparation of a range of
perfluoroalkyl species including perfluoroalkanesulfonate
esters [1] and perfluoroalkanesulfonamides [1,2]. More
recently, perfluoroalkanesulfonyl groups have also found
extensive applications as fluorous tags in the work of
Fluorous Technologies [3]. Conventional methods for the
preparation of perfluoroalkanesulfonyl chlorides include
chlorination of sodium perfluoroalkanesulfinate salts [4,5] or
perfluoroalkyl thioethers [6]; addition of perfluoroalkyl
Grignard reagents either directly to sulfuryl chloride or
addition to sulfur dioxide and subsequent chlorination [7]; or
transformation of the corresponding perfluoroalkanesulfonic
acid using phosphorus pentachloride [8]. However, these
conditions were found to be too harsh for functional groups
present in our systems and so we felt there was scope for a
mild generally applicable synthesis of perfluoroalkanesul-
fonyl chlorides. In this note we present a novel two-step
synthesis of perfluoroalkanesulfonyl chlorides from per-
2. Results and discussion
In connection with a project developing new linkers for
solid phase chemistry [9], we had a need for perfluoroalk-
anesulfonyl chloride (3). We speculated that perfluoroalk-
anesulfonyl chloride (3) could be derived from
perfluoroalkyl iodide (1), which in turn could be obtained
from the addition of 1,4-diiodooctafluorobutane to allyl
alcohol (Scheme 1). The radical addition of 1,4-diiodooc-
tafluorobutane to allyl alcohol was carried out neat at 70 8C
in the presence of AIBN (50 mol%) to furnish perfluor-
oalkyliodide (1) in 83% yield. Attention then turned to the
conversion of perfluoroalkyliodide (1) into the correspond-
ing perfluoroalkanesulfonyl chloride (3) using chemistry
reported by Qiu and Burton [4]. Reaction of perfluoroalk-
yliodide (1) with sodium dithionite and sodium bicarbo-
nate was carried out in acetonitrile and water (3:1) and
monitored by 19F NMR spectroscopy. The complete
disappearance of the CF2-I signal at ꢀ59 ppm and the
appearance of a CF2-SO2Na signal at ꢀ127 ppm indicated
quantitative conversion to sodium perfluoroalkanesulfinate
* Corresponding author. Tel.: +44 191 334 2131; fax: +44 191 384 4737.
E-mail address: p.g.steel@durham.ac.uk (P.G. Steel).
0022-1139/$ – see front matter # 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2005.05.007

P.J.H. Scott et al. / Journal of Fluorine Chemistry 126 (2005) 1196–1201
1197
Scheme 1.
(2) in 4 h. The reaction mixture was then concentrated, the
sulfinate salt redissolved in water and treated with chlorine
gas at 0 8C. However, rapid decomposition of the substrate
occurred. We suspect that the acidic conditions involved
were too harsh although attempts to buffer the reaction
mixture were equally unsuccessful.
no reaction and starting material was recovered in both
cases. Conversely, a combination of phosphorus pentachlor-
ide and phosphoryl chloride [8] caused decomposition of
materials resulting in complex polymeric mixtures.
As it was not possible to derive sulfonyl chlorides from
the corresponding sulfonic acids, we investigated the
synthesis of perfluorobutyl benzyl thioether (7) and its
subsequent conversion to perfluorobutylsulfonyl chloride (5)
using Moore’s chlorination procedure [6]. Perfluorobutyl
benzyl thioether (7) was synthesised in 23% yield from 1-
iodononafluorobutane and benzyl mercaptan following
Feiring’s report (Scheme 3) [11]. However, attempts to
convert this to perfluorobutylsulfonyl chloride using
molecular chlorine also resulted in decomposition. Similarly
alternative strategies exploring oxidative chlorination of the
corresponding sulfone (8) were not successful, leading only
to recovered starting material. A more typical strategy for
the oxidation of sulfones uses potassium permanganate as
shown by Lewis et al. [12]. However, as the aim of the work
was to ultimately oxidise perfluoroalkyliodide (1) contain-
ing a free hydroxyl group, we felt that potassium
permanganate could cause unwanted oxidation side-reac-
tions and consequently did not represent a desirable route
towards perfluorosulfonyl chlorides.
At this stage, generation of perfluroalkanesulfonyl
chlorides was explored further using 1-iodononafluorobu-
tane as a model substrate (Scheme 2). Treatment of
perfluorobutanesulfinate (4) with chlorine gas also resulted
in decomposition. This was a surprising result as we have
previously employed this reaction successfully on a number
of similar substrates [9] and it has also been used to
synthesize perfluorobutylsulfonyl chloride (5) by Clavel
et al. [10]. However, we had no means of quantifying how
the amount of chlorine added or the rate of addition
compared to those used by Clavel and as the reaction was
proving problematic in our hands, alternative methods for
the synthesis of perfluoroalkanesulfonyl chlorides were
examined. We decided to explore a two step procedure via
the corresponding sulfonic acid (6). Oxidation of sodium
perfluorobutanesulfinate (4) was achieved using aqueous
hydrogen peroxide at 0 8C and proceeded in 4 h to give acid
(6) in 47% yield. However, attempts to convert this to the
sulfonyl chloride (5) using a range of chlorinating agents
proved unsuccessful. Treatment of perfluorobutanesulfonic
acid (6) with oxalyl chloride or thionyl chloride resulted in
At this point we were attracted by a report by Vedsø et al.
describing the oxidation of lithium arylsulfinate salts to the
corresponding arylsulfonyl chlorides using N-chlorosucci-
Scheme 2.

1198
P.J.H. Scott et al. / Journal of Fluorine Chemistry 126 (2005) 1196–1201
Scheme 3.
Scheme 4.
nimide [13]. Following this literature precedent, sodium
perfluorobutanesulfinate (4) was suspended in dichloro-
methane and treated with excess N-chlorosuccinimide. The
reaction was monitored by 19F NMR spectroscopy and
complete conversion to perfluorobutanesulfonyl chloride (5)
was observed after 2 h by the disappearance of the CF2-
SO2Na signal at ꢀ127 ppm and the appearance of a CF2-
SO2Cl signal at ꢀ104 ppm. A reductive workup using
saturated sodium thiosulfate was attempted in order to
remove molecular iodine formed as a by-product but was
found to cause decomposition of the product. Therefore, the
reaction was repeated and iodine was removed in vacuo.
Additional purification by flash chromatography gave
perfluorobutanesulfonyl chloride (5) in 30% yield over
two steps (Scheme 4). The large excess of NCS is required
due to the presence of sodium iodide formed as a by-product
of the initial sulfonation step. Whilst this can be avoided by
purification of the intermediate sulfinate salt by continuous
extraction into methanol, in cases where the iodine does not
have a detrimental step, it is operationally simpler to carry
out the sulfonation and oxidation as a single process.
With
a mild synthesis of perfluoroalkanesulfonyl
chlorides in hand, we wanted to demonstrate that it was
applicable to molecules containing a range of functionalised
substrates (Table 1). Chlorination of sodium perfluoroalk-
ylsulfinate (2) in dichloromethane at room temperature
(entry 2) gave a low 25% yield of perfluoroalkanesulfonyl
chloride (3), which was attributed to the low solubility of
sodium perfluoroalkylsulfinate (2) in dichloromethane. In
order to improve this, the reaction was repeated in a biphasic
dichloromethane and water (5:1) solvent system to furnish
perfluoroalkanesulfonyl chloride (3) in 63% yield over two
steps (entry 3). Similarly, oxidation of the corresponding
silyl ether and acetate containing substrates proceeded
smoothly (entries 4 and 5) demonstrating that acid sensitive
functional groups are compatible with this process.
Table 1
Conversion of perfluoroalkyl iodides into perfluoroalkanesulfonyl chlorides
ðiÞNa
S
O
;NaHCO ;MeCNꢀH
O
2
2
4
3
2
RFꢀIꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀ!RFꢀSO2Cl
ðiiÞðAÞNCS;DCM;rt;2h
ðBÞNCS;DCMꢀH O;rt;3h
2
Entry RF
Method Yield (%) (two steps)
3. Conclusions
1
2
C4F9
A
A
30
25
In summary, a mild two-step one pot synthesis of
perfluoroalkanesulfonyl chlorides from iodoperfluoroalk-
anes has been developed involving initial conversions to the
corresponding sodium perfluoroalkylsulfinate salts by
treatment with sodium dithionite and subsequent oxidation
with N-chlorosuccinimide. This method is very mild and is
tolerant of a range of functional groups that would otherwise
be unsuitable for traditional methods of chlorination.
3
4
5
B
B
B
63
36
73

P.J.H. Scott et al. / Journal of Fluorine Chemistry 126 (2005) 1196–1201
1199
4. Experimental
4.2. 1,1,2,2,3,3,4,4-Octafluoro-7-hydroxy-6-iodo-
heptanesulfonyl chloride (3)
All reagents were used as received. AIBN was obtained
from Acro¯s Organics and stored in a refrigerator. Petroleum
ether refers to the fraction of petroleum ether, which boils
between 40 and 60 8C and was redistilled prior to use. Where
mixtures of solvents were used, ratios given refer to volumes
4,4,5,5,6,6,7,7-Octafluoro-2,7-diiodoheptan-1-ol (1) (0.5 g,
0.98 mmol) was dissolved in water (0.8 cm3) and acetoni-
trile (2.4 cm3). Sodium dithionite (0.34 g, 1.96 mmol) and
sodium bicarbonate (0.18 g, 2.16 mmol) were added and the
reaction stirred for6 h at rt. After this time inorganic materials
were removed by filtration and the solvent was evaporated
under reduced pressure to give sodium sulfinate (2) as a white
residue. This was suspended in DCM (10 cm3) and water
(2 cm3) and N-chlorosuccinimide (0.33 g, 2.45 mmol) was
added. The reaction was stirred for 1 h at rt after which time
DCM (50 cm3) and water (10 cm3) were added. The organic
layer was separated and washed further with saturated sodium
thiosulfate (50 cm3). The layers were separated again and the
organic layer was dried (MgSO4), filtered and evaporated to
give a crudewhite solid. Purification by flash chromatography
(pet. ether, pet. ether/ethyl acetate [9:1], pet. ether/ethyl
acetate [8:2]) yielded title compound (3) as a white solid
(0.30 g, 63%); mp 50–52 8C; m/z (ESꢀ) 449 (M ꢀ Cl, 10%),
321 (M ꢀ (I + Cl), 30%); nmax(ATR) 3302 (br. OH), 1560,
1422 (SO2Cl), 1212 (SO2Cl) and 1050 cmꢀ1; dH (CDCl3;
300 MHz) 2.48 (1H, br. s, OH), 2.63–2.83 (1H, m,
CHAHBCF2), 2.95–3.15 (1H, m, CHAHBCF2), 3.80 (2H, m,
CH2OH), 4.34–4.42 (1H, m, CHI); dC (CDCl3; 100 MHz)
1
used. H NMR spectra were analysed in CDCl3 on Varian
Oxford 200, Bruker AM250, Varian Unity 300, Varian VXR
400 or Varian Inova 500 spectrometers. The residual protic
solvent CHCl3 (dH = 7.26 ppm) was used as an internal
reference. 13C NMR spectra were recorded at 63 MHz on the
Bruker AM250 spectrometer or 125 MHz on the Varian
Inova 500 spectrometer. The central resonance of CDCl3
(dC = 77.00 ppm) was used as an internal reference. 19F
NMR spectra were analysed in CDCl3 at 188 MHz on the
Varian Oxford 200 spectrometer, 283 MHz on the Varian
Unity 300 spectrometer or 375 MHz on the Varian Inova 500
spectrometer and were referenced to CFCl3 (dF = 0 ppm).
Chemical shifts are quoted in parts per million relative to
tetramethylsilane (dH = 0 ppm) and coupling constants are
quoted in Hertz. Compound purity was confirmed by GC and
GCMS obtained on VG Analytical 7070E or VG Autospec
Organic Mass spectrometers. High resolution mass spectra
were obtained where possible from the EPSRC National
Mass Spectrometry Service Centre, University of Wales
Swansea, UK. In all cases, electrospray or electron
ionisation methods were used to generate ions. It was not
possible to obtain HRMS of perfluoroalkanesulfonyl
chlorides (3 and Table 1 entries 4 and 5) as these compounds
were found to be unstable in the mass spectrometer. In these
cases, purity was confirmed by GC, 19F and 1H NMR
spectroscopy.
2
21.2 (CHI), 37.3 (t, JC–F 21 Hz, CH2CF2), 67.8 (CH2OH),
108.3 (m, CF2), 111.0 (m, CF2), 115.5 (tt, 2JC–F 35 Hz, 1JC–F
311 Hz, CF2), 117.7 (tt, 2JC–F 31 Hz, 1JC–F 257 Hz, CF2); dF
(CDCl3; 280 MHz) ꢀ104.50 (2F, m, CF2SO2Cl), ꢀ113.80
(2F, m, CH2CF2), ꢀ119.45 (2F, m, CF2CF2SO2Cl), ꢀ123.61
(2F, m, CF2).
4.3. 1,1,2,2,3,3,4,4,4-Nonafluorobutane-1-sulfonyl
chloride (5) [12]
4.1. 4,4,5,5,6,6,7,7-Octafluoro-2,7-diiodoheptan-1-ol
(1)
Sodium dithionite (2.01 g, 11.56 mmol) and sodium
hydrogen carbonate (1.07 g, 12.72 mmol) were added to a
stirred suspension of 1-iodononafluorobutane (2.0 g,
5.78 mmol) in acetonitrile (7.5 cm3) and water (5 cm3)
and stirred at room temperature for 20 h. After this time, the
reaction mixture was filtered and evaporated under reduced
pressure to yield sodium sulfinate salt (4) as a white residue.
This was suspended in DCM (10 cm3) and N-chlorosucci-
nimide (3.86 g, 28.92 mmol) was added. The reaction was
stirred for 1 h at rt after which time DCM (50 cm3) and water
(10 cm3) were added. The organic layer was separated, dried
(MgSO4), filtered and evaporated to give a crude solid.
Purification by flash chromatography (pet. ether, pet. ether/
ethyl acetate [9:1], pet. ether/ethyl acetate [8:2]) yielded title
compound (5) as a pale oil (0.55 g, 30%); m/z (ESꢀ) 283
(C4F9SO2, 100%); nmax(film) 1417 (SO2Cl), 1220 (SO2Cl),
1147, 1078, 782 and 722 cmꢀ1; dF (CDCl3; 188 MHz)
ꢀ81.27 (3F, m, CF3), ꢀ104.54 (2F, m, CF2SO2Cl), ꢀ119.36
(2F, s, CF2 CF2SO2Cl), ꢀ123.21 (2F, m, CF2); all data
agreed with that previously reported.
Allyl alcohol (0.26 g, 0.30 cm3, 4.40 mmol) was added
dropwise to a stirred solution of AIBN (0.36 g, 2.20 mmol)
and 1,4-diiodooctafluorobutane (10.0 g, 4.0 cm3, 22.00
mmol). The reaction was then heated to 70 8C and stirred
overnight. After this time, the crude reaction mixture was
cooled and purification by flash chromatography (pet. ether,
pet. ether/ethyl acetate [9:1], pet. ether/ethyl acetate [8:2])
yielded the title compound 1 as a pale yellow oil (1.88 g,
83%); m/z (EI) 512 (M+, 5%), 385 (M ꢀ I, 100%); HRMS
(EI) 511.8375 (M+), C7H6F8I2O requires 511.8370; nmax(-
film) 3447 (br. OH), 1170, 1069, and 674 cmꢀ1; dH (CDCl3;
400 MHz) 2.44 (1H, br. s, OH), 2.65–2.80 (1H, m,
CHAHBCF2), 2.92–3.07 (1H, m, CHAHBCF2), 3.78 (2H,
m, CH2OH), 4.36–4.41 (1H, m, CHI); dC (CDCl3; 125 MHz)
2
23.3 (CHI), 37.3 (t, JC–F 21 Hz, CH2CF2), 67.8 (CH2OH),
94.0 (tt, 2JC–F 42 Hz, 1JC–F 320 Hz, CF2-I), 108.9 (m, CF2),
109.7 (m, CF2), 117.6 (tt, 2JC–F 31 Hz, 1JC–F 257 Hz, CF2);
dF (CDCl3; 375 MHz) ꢀ59.32 (2F, m, ICF2), ꢀ113.16 (2F,
m, CF2), ꢀ113.77 (2F, m, CH2CF2), ꢀ123.16 (2F, m, CF2).

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P.J.H. Scott et al. / Journal of Fluorine Chemistry 126 (2005) 1196–1201
4.4. 1,1,2,2,3,3,4,4,4-Nonafluorobutane-1-sulfonic acid
(6) [14]
this time the reaction was cooled to rt and water (10 cm3)
was added, resulting in a white precipitate. Recrystallisation
of the precipitate from petroleum ether yielded the title
compound (8) as a white crystalline solid (0.15 g, 34%); mp
79–81 8C; m/z (ESꢀ) 413 (M + K, 100%), 373 (M ꢀ H+
60%), 219 (C4F9, 100%); HRMS (ESꢀ) 372.9948 (M ꢀ H+),
C11H6F9SO2 requires 372.9939; nmax(KBr Disk) 1421,
1224, 1144 (SO2), 1059, 782 and 505 cmꢀ1; dH (CDCl3;
500 MHz) 4.52 (2H, s, CH2), 7.38–7.47 (5H, m, ArH); dC
(CDCl3; 125 MHz) 58.0 (CH2), 128.9 (2C), 130, 131, 132.0
(2C), ca. 100–130 (4ꢁ v. weak m, 3ꢁ CF2 and CF3); dF
(CDCl3; 283 MHz) ꢀ81.03 (3F, m, CF3), ꢀ112.48 (2F, m,
CF2SO2), ꢀ121.50 (2F, m, CF2), ꢀ126.27 (2F, m, CF2).
Sodium dithionite (3.48 g, 29 mmol) and sodium hydro-
gen carbonate (2.02 g, 34.8 mmol) were added to a stirred
suspension of 1-iodononafluorobutane (10.0 g, 28.9 mmol)
in acetonitrile (7.5 cm3) and water (5 cm3) and stirred at
room temperature for 20 h. After this time, the reaction
mixture was filtered and evaporated under reduced pressure
to yield sodium sulfinate salt (4) as a white residue. This was
redissolved in water (15 cm3), cooled to 0 8C and hydrogen
peroxide was added dropwise (3.10 cm3, 37% w/w solution,
33 mmol). The reaction was stirred for 20 h at 0 8C and then
water (20 cm3) and diethyl ether (20 cm3) were added. The
layers were separated and the organic layer was extracted
with water (3ꢁ 20 cm3). The combined aqueous layers were
acidified (1 M HCl) and extracted with diethyl ether (3ꢁ
30 cm3). The combined diethyl ether fractions were dried
(MgSO4) and evaporated to yield the title compound (6) as a
yellow oil (4.12 g, 47%); m/z (ESꢀ) 299 (M ꢀ H+, 25%),
283 (C4F9SO2, 100%); nmax(film) 3357 (OH), 1187, 1137,
1021, 657 cmꢀ1; dH (CDCl3; 200 MHz) 7.92 (1H, br. s,
SO3H); dF (CDCl3; 188 MHz) ꢀ83.07 (3F, m, CF3),
ꢀ125.46 (2F, s, CF2), ꢀ128.36 (2F, s, CF2S), ꢀ132.21
(2F, m, CF2); all data agreed with that previously reported.
4.7. 7-(tert-Butyldimethylsilyloxy)-1,1,2,2,3,3,4,4-
octafluoro-6-iodoheptanesulfonyl chloride (Table 1,
entry 4)
tert-Butyldimethyl-(4,4,5,5,6,6,7,7-octafluoro-2,7-diiodo-
heptyloxy)silane (0.50 g, 0.80 mmol) was dissolved in water
(2 cm3) and acetonitrile (6 cm3). Sodium dithionite (0.28 g,
1.60 mmol) and sodiumbicarbonate (0.14 g, 1.76 mmol) were
added and the reaction mixture was stirred at rt overnight.
Inorganic materials were then removed by filtration and the
solvent was evaporated under reduced pressure to give the
sodium sulfinate salt as a white residue. This was suspended in
DCM (25 cm3) and water (5 cm3) and N-chlorosuccinimide
(0.53 g, 4.0 mmol) was added. The reaction was stirred
overnight at rt after which time DCM (50 cm3) and saturated
sodium thiosulfate (50 cm3) were added. The layers were
separated and the organic layer was dried (MgSO4), filtered
and evaporated to give the crude product. Purification by flash
chromatography (pet. ether, pet. ether:ethyl acetate [9:1], pet.
ether:ethyl acetate [8:2]) yielded the title compound as a clear
oil (0.17 g, 36%); m/z (EI) 541: 543 (3: 1, M-t-Bu, 5%), 474
(5%), 383 (10%), 185 (40%); nmax(ATR) 1418 (SO2Cl), 1213
(SO2Cl), 1139 (Si–O), 836, and 540 cmꢀ1; dH (CDCl3;
500 MHz) 0.083 (3H, s, Si–CH3), 0.096 (3H, s, Si–CH3), 0.91
(9H, s, C(CH3)3), 2.62 (1H, m, CHAHBCF2), 3.16 (1H, m,
CHAHBCF2), 3.75 (1H, dd, 3J 4 Hz, 2J 11 Hz, CHAHB), 3.88
(1H, dd, 3J 4 Hz, 2J 11 Hz, CHAHB), 4.23–4.27 (1H, m, CHI);
dC (CDCl3; 125 MHz) ꢀ5.5 (Si–CH3), ꢀ5.4 (Si–CH3), 17.9,
4.5. 1,1,2,2,3,3,4,4-Octafluoro-4-iodobutyl benzyl
sulfide (7)
Benzyl mercaptan (1.24 g, 1.18 cm3, 10 mmol) was added
dropwise to a stirred suspension of potassium hydride (1.37 g,
35% suspension in oil, 12 mmol) in DMF (10 cm3) at 0 8C.
The reaction was allowed to warm to rt and then 1-
iodononafluorobutane (4.15 g, 2.07 ml, 12 mmol) was added
dropwise and the reaction stirred for 24 h. Diethyl ether
(50 cm3) was then added and the organic layer was washed
with water (4ꢁ 10 cm3), dried (MgSO4) and evaporated under
reduced pressure to yield the crude product. Purification by
flash chromatography (pet. ether) yielded the title compound
(7) as a clear oil (0.80 g, 23%); m/z (EI) 342 (M+ 60%), 121
(100%); 89 (100%); HRMS (EI) 342.0120, C11H7F9S
requires 342.0125; nmax(film) 1497, 1350, 1135, 1095, 992,
and864 cmꢀ1;dH (CDCl3;300 MHz)4.18(2H, s, CH2), 7.31–
7.37 (5H, m, ArH); dC (CDCl3; 125 MHz, 19F de-coupled)
33.0 (CH2), 109.1 (CF2), 110.6 (CF2), 117.7 (CF2), 124.6
(SCF2), 128.2 128.9 (2C), 129.2 (2C), 134.5; dF (CDCl3;
280 MHz) ꢀ81.38 (3F, m, CF3), ꢀ88.20 (2F, m, SCF2),
ꢀ121.10 (2F, m, CF2), ꢀ125.95 (2F, m, CF2).
2
18.2, 25.7 (C(CH3)3), 36.9 (t, JC–F 24.5 Hz, CH2CF2), 68.2
(CH2), 111.1 (m, CF2), 115.6 (tt, 2JC–F 35 Hz, 1JC–F 290 Hz,
2
1
CF2), 116.0 (m, CF2), 117.8 (tt, JC–F 32 Hz, JC–F 259 Hz,
CF2); dF (CDCl3; 188 MHz) ꢀ104.45 (2F, m, CF2SO2Cl),
ꢀ113.94 (2F, m, CF2), ꢀ119.45 (2F, m, CF2CF2SO2Cl),
ꢀ123.83 (2F, m, CF2).
4.6. Nonafluorobutyl Benzyl Sulfone (8)
4.8. 7-Chlorosulfonyl-4,4,5,5,6,6,7,7-octafluoro-2-
iodoheptyl acetate (Table 1, entry 5)
1,1,2,2,3,3,4,4-Octafluoro-4-iodobutyl benzyl sulfide
(0.40 g, 1.17 mmol) was dissolved in acetic acid (2 cm3).
Hydrogen peroxide (0.53 cm3, 35% w/w solution,
6.0 mmol) in acetic acid (2 cm3) was added dropwise and
the reaction was heated to 100 8C and stirred for 4 h. After
4,4,5,5,6,6,7,7-Octafluoro-2,7-diiodoheptyl acetate
(0.16 g, 0.29 mmol) was dissolved in water (0.4 cm3) and
acetonitrile (1.2 cm3). Sodium dithionite (0.1 g, 0.58 mmol)
and sodium bicarbonate (0.054 g, 0.64 mmol) were added

P.J.H. Scott et al. / Journal of Fluorine Chemistry 126 (2005) 1196–1201
1201
and the reaction mixture was stirred for at rt for 6 h. After this
time inorganic materials were removed by filtration and the
solvent was evaporated under reduced pressure to give the
sodium sulfinatesalt asa whiteresidue. This was suspendedin
dry DCM (10 cm3) and N-chlorosuccinimide (0.086 g,
0.64 mmol) was added. The reaction was stirred for 1 h at
rt after which time DCM (50 cm3) and water (10 cm3) were
added. The organic layer was separated and washed with
saturated sodium thiosulfate (50 cm3). The layers were
separated again and the organic layer was dried (MgSO4),
filteredandevaporatedtogive acrudewhitesolid. Purification
by flash chromatography (pet. ether, pet. ether:ethyl acetate
[9:1], pet. ether:ethylacetate[8:2])yieldedthe titlecompound
as a colourless oil (0.11 g, 73%); m/z (ESꢀ) 491 (M ꢀ Cl,
100%), 363 (M ꢀ (I + Cl), 30%); nmax(ATR) 1745 (C O),
1415 (SO2Cl), 1210 (SO2Cl), 1181, 1137, 1046, and
737 cmꢀ1; dH (CDCl3; 300 MHz) 2.12 (3H, s, CH3), 2.67–
3.03 (2H, m, CH2CF2), 4.25–4.40(3H, m, CHI and CH2OAc);
dC (CDCl3; 100 MHz) 11.5 (CH3), 20.7 (CHI), 38.0 (t, 2JC–F
21 Hz, CH2CF2), 68.4 (CH2OAc), 170.1 (C O), ca. 100–130
(4ꢁ v. weak m, 4ꢁ CF2); dF (CDCl3; 280 MHz) ꢀ104.53 (2F,
m, CF2SO2Cl), ꢀ113.80 (2F, m, CH2CF2), ꢀ119.45 (2F, m,
CF2CF2SO2Cl), ꢀ123.60 (2F, m, CF2).
Spectrometry Service Centre at Swansea for HRMS and Dr.
Simon de Sousa for some preliminary reactions.
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We thank the EPSRC and GlaxoSmithKline for the
financial support of this work, the EPSRC National Mass