Directed ortho-Metalation of Arenesulfonyl Fluorides and Aryl Fluorosulfates

Article abstract of DOI:10.1055/s-0037-1610877

Studies on directed ortho -metalation (DoM) of arenesulfonyl fluorides (ArSO ₂ F) with in situ electrophile trapping are presented. Under optimized conditions (LDA, THF, -78 °C), a series of model substrates was mono- and difunctionalized with trimethylsilyl chloride in good yields. The synthetic results reveal powerful directing character of the SO ₂ F group, being ahead of bromine and methoxy substituents. Under the same metalation conditions, aryl fluorosulfates (ArOSO ₂ F) display fragmentation to arynes and migration of the SO ₂ F group to the ortho position (anionic thia-Fries rearrangement).

Full text of DOI:10.1055/s-0037-1610877

SYNTHESIS
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© Georg Thieme Verlag Stuttgart · New York
2019, 51, A–I
feature
A
en
A. Talko et al.
Feature
Synthesis
Directed ortho-Metalation of Arenesulfonyl Fluorides and Aryl
Fluorosulfates
Alicja Talko
SO2F
SO2F
SO2F
LDA
Me3SiCl
Damian Antoniak
SiMe3
Me3Si
SiMe3
arene
sulfonyl
fluorides
Michał Barbasiewicz*
0
0
0
0-
0
0
0
2-0
9
0
7-7
0
3
4
THF
–78 °C
or
up to 86%
R
R
R
R
R
up to 74%
Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093
Warsaw, Poland
barbasiewicz@chem.uw.edu.pl
OSO2F
OH
aryl
fluoro-
sulfates
SO2F
LDA
or
THF
–78 °C
anionic
thia-Fries
rearrangement
R
Received: 24.02.2019
Accepted after revision: 12.03.2019
Published online: 11.04.2019
ates,11 and alkenes.12–16 Importantly, in the absence of acti-
vators, the fluorosulfonyl group displays an impressive re-
sistance toward reduction, cross-coupling conditions, bases,
acids, and radical precursors.1
DOI: 10.1055/s-0037-1610877; Art ID: ss-2019-z0124-fa
Abstract Studies on directed ortho-metalation (DoM) of arenesulfonyl
fluorides (ArSO2F) with in situ electrophile trapping are presented. Un-
der optimized conditions (LDA, THF, –78 °C), a series of model sub-
strates was mono- and difunctionalized with trimethylsilyl chloride in
good yields. The synthetic results reveal powerful directing character of
the SO2F group, being ahead of bromine and methoxy substituents.
Under the same metalation conditions, aryl fluorosulfates (ArOSO2F)
display fragmentation to arynes and migration of the SO2F group to the
ortho position (anionic thia-Fries rearrangement).
We wondered if the SO2F substituent in arenesulfonyl
fluorides can act as a directing ortho-metalation (DoM)
group,17,18
mimicking
reactivity
of
sulfonamides
(ArSO2NR2),19 sulfonates (ArSO3R),20–23 sulfones (ArSO2R),24
and triflones (ArSO2CF3).25 The most promising approach to
test the metalation seemed to be application of the ‘in situ
electrophile trapping’ procedure (Barbier conditions),26
where contact between nucleophilic aryllithiums and sen-
sitive functional group is reduced, which was successfully
applied for lithiation of benzoates,27,28 benzonitriles,28 and
aryl halides.28,29
Key words sulfonyl fluorides, fluorosulfates, directed ortho-metala-
tion, SuFEx, orthogonal reactivity, in situ trap, lithium amides, anionic
thia-Fries rearrangement
Following literature procedure29 benzenesulfonyl fluo-
ride (1a)30,31 and trimethylsilyl chloride (TMSCl) were treat-
ed with a preformed solution of lithium diisopropyl amide
(LDA) in THF at –78 °C under argon. GC analysis of the mix-
ture revealed the presence of substrate 1a and two products
2a and 3a. To control the reaction course, changes in type
and amount of the base and reaction time were tested (see
the Supporting Information for details of the optimization
studies). Finally, we realized that simple manipulation of
the reaction conditions from 1.2 equivalents LDA, 2.4 equiv-
alents TMSCl, 0.5 hour, to 3.0 equivalents LDA, 6.0 equiva-
lents TMSCl, 4.0 hours switches between predominant for-
mation of mono- (2a) and disilylated32,33 (3a) products, iso-
lated in 80% and 74% of yield, respectively.
With the optimized conditions in hand, we screened
functionalization of a series of arenesulfonyl fluorides 1a–
g, prepared from commercially available sulfonyl chlorides
by a halogen exchange in 90–99% yields.2,8,9 Then, each of
the substrates was subjected to mono- and disilylation con-
ditions, and main products were isolated by column chro-
matography (Table 1). 4-Methylbenzenesulfonyl fluoride
Sulfonyl fluorides (SFs) are versatile reagents, which at-
tract an enormous attention of researchers in the areas of
organic synthesis, chemical biology, drug discovery, and
material science.1–6 The fluorosulfonyl group (SO2F) offers
unique properties, combining enhanced stability, as com-
pared with other sulfonyl halides, and susceptibility to-
wards activation with hydrogen bond donors,2 Lewis acids,7
and nucleophilic catalysts.3 Whereas in biological systems
formation of covalent linkages with enzymes is favored by
the hydrogen bond network around the active sites,2 in syn-
thetic applications, DBU-catalyzed nucleophilic substitu-
tion at the sulfur atom with silyl containing reagents was
applied as a new ‘click reaction’ of excellent characteristics,
referred as SuFEx (Sulfur Fluoride Exchange).2–6 The most
straightforward preparation of sulfonyl fluorides is based
on the halogen exchange reaction of sulfonyl chlorides
(RSO2Cl → RSO2F), realized under biphasic ‘on-water’ condi-
tions with saturated aqueous solution of potassium bifluo-
ride (KHF2).2,8,9 So-formed sulfonyl fluorides are valuable
substrates for the preparation of sulfonamides,7,10 sulfon-
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2019, 51, A–I

B
A. Talko et al.
Feature
Synthesis
(1b) reacted unselectively, giving mixtures of products of
silylation at the ortho and benzylic positions.34,35 4-(tert-
Butyl)benzenesulfonyl fluoride (1c) reacted well, but isolat-
ed yields of mono- and disilylated products were lower
than for 1a (65% of 2c, and 49% of 3c). Presence of the nitro
group in the aromatic ring of 1d inhibited the metalation
process, and resulted in decomposition under more vigor-
ous conditions. 2-Bromobenzenesulfonyl fluoride (1e) led
to a product of monosilylation at the 6-position in a very
good yield (86%, 2e), but attempt of formation of disilylated
derivative gave hardly separable mixture of products.36 1-
Naphthalenesulfonyl fluoride (1f) gave product of silylation
at the ortho position (2f, 85%), but no signs of subsequent
peri-metalation (at the 8-position) were observed with ex-
cess of the reagents. Interestingly, 4-methoxybenzenesulfo-
nyl fluoride (1g) under monosilylation conditions led exclu-
sively to 2-(trimethylsilyl)-4-methoxybenzenesulfonyl flu-
oride (2g) in 86% of yield, whereas disilylation gave a
mixture of 2,6- (3g) and 2,5-bis(trimethylsilyl)-4-methoxy-
benzenesulfonyl fluoride (3g′), isolated in 53 and 43% yield,
respectively (Scheme 1, top). The result suggests that the
fluorosulfonyl group (SO2F) is a powerful directing group,
being ahead of bromine and methoxy substituents, and
only increased steric hindrance enables an alternative
metalation pathway, directed by the OMe group (product
3g′). Commercially available phenylmethanesulfonyl fluo-
ride (PMSF, 1h) likely got deprotonated under the reaction
conditions, and only small amount of ill-defined silylated
products was formed, as confirmed by 1H NMR analysis.
Biographical Sketches
Alicja Talko (1995) is currently
pursuing her Master’s degree in
chemistry at the University of
Warsaw.
Damian Antoniak (1993) ob-
tained his B.Sc. degree (2016)
and M.Sc. degree (2017) from
Warsaw University of Technolo-
gy. Now he is doing his Ph.D. re-
search at the University of
Warsaw.
Michał Barbasiewicz (1978)
was fascinated in chemistry
since early years of life, but the
interests deepened when he
read the famous Organic Chem-
istry of R. T. Morrison and R. N.
Boyd in 1995, and succeeded in
bronze medal at the Interna-
tional Chemistry Olympiad in
1997. Focused on chemical sci-
ences he graduated from War-
saw University of Technology
(M. Fedoryński), and completed
his Ph.D. on intermolecular re-
actions of - and -halocarban-
ions under M. Mąkosza (IOC
PAS, Warsaw). In 2007–2008,
he was an Alexander von Hum-
boldt postdoctoral fellow in the
group of J. A. Gladysz in
Erlangen, Germany (synthesis of
borane-protected cage diphos-
phines). Recently, he completed
his habilitation on Hoveyda–
Grubbs metathesis catalysts
(group of K. Grela), and now
continues independent scientif-
ic career at the University of
Warsaw. In research studies and
as an academic teacher, he de-
lights in fundamentals of organ-
ic chemistry. Privately he loves
nature walking tours, where he
reminds of things that really
matter.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2019, 51, A–I

C
A. Talko et al.
Feature
Synthesis
Table 1 Synthetic Studies of Mono- and Difunctionalization of Arene-
sulfonyl Fluorides 1a–h by DoM with in situ TMSCl Trapping
under standard reaction conditions (Scheme 1, center). In
contrast to the attempt of deprotometalation of 1a with n-
BuLi/TMSCl mixture, where butyl phenyl sulfone was
formed37 (see the Supporting Information for details), the
bromine–lithium exchange ran selectively giving 2,6-
bis(trimethylsilyl)benzenesulfonyl fluoride (3a) in excellent
yield.
2.0 mmol scale
LDA
SO2F
SO2F
SiMe3 Me3Si
or
SiMe3
TMSCl
R
SO2F
1a–h
THF
–78 °C
X
2a–g
X
3a–g
At the end, we tested also triisopropyl borate B(Oi-Pr)3,
as an in situ electrophile under standard conditions with
LDA.27,28 Although the expected ortho-borylation38 product
4 was isolated as a neo-pentyl glycol ester in 58% of yield
(Scheme 1, bottom), attempt at diborylation with an excess
of the reagents failed.
Sulfonyl fluorides 1a–f Yield of monosilylationa Yield of disilylationb
1a (R = Ph)
80% (2a)
74% (3a)
1b (R = 4-MeC6H4)
1c (R = 4-t-BuC6H4)
1d (R = 3-O2NC6H4)
1e (R = 2-BrC6H4)
1f (R = 1-naphthyl)
1g (R = 4-MeOC6H4)
unselectivec
65% (2c)
unselectived
49% (3c)
low conversion (GC)
86% (2e)
unselective (GC) + tars
unselectivee
Having silylation and borylation of the arenesulfonyl
fluorides 1a–g tested under in situ trapping (Barbier) con-
ditions,26 we focused on premetalation conditions, required
for reactions with other electrophiles. First, the monosilyla-
tion procedure was modified by separation of deprotona-
tion from addition of the electrophile. When 1a was treated
with LDA and after 30 minutes TMSCl was added, we ob-
tained a complex mixture, suggesting competitive process-
es that occur.31 However, after multiple chromatography,
we isolated the product of intermolecular sulfonylation 5
(19%),39 which was characterized by X-ray studies (Scheme
2, top). The result was consistent with the literature data,
where 2-methoxynaphthalene, metalated with n-BuLi, was
treated with 1a giving sulfonylated product in 55% yield.40
However, in contrast to the reaction with n-BuLi, deproton-
ation with LDA can be considered a reversible process,41
where reaction with electrophile shifts the equilibrium for-
ward. When silyl reagent is not present, only a slow inter-
molecular reaction with 1a takes place, likely accompanied
with numerous proton shift equilibria. At the same time an
alternative, intramolecular elimination pathway to the
aryne was excluded by a trapping experiment with 1,3-di-
phenylisobenzofuran, which failed to give the expected ad-
duct (Scheme 2, center). Interestingly, elimination of the
fluorosulfonyl group was observed on another substrate,
(E)-2-phenylethene-1-sulfonyl fluoride (1i). Under stan-
dard conditions with sterically hindered lithium 2,2,6,6-te-
tramethylpiperidine amide (LiTMP) and TMSCl, 1i gave a
mixture of silylation and elimination products in low yields
(12% of 2i and 20% of 2i′, respectively; Scheme 2, bottom).
When formation of the -silylated product 2i likely arouse
from -metalation of 1i, elimination of the SO2F to give 2i′42
may result from at least three alternative pathways: -
metalation of 1i, -metalation of 2i, and -metalation of 1i,
followed by migration of phenyl group or hydride anion
85% (2f)
no peri-metalationf
53% (3g) + 43% (3g′)
not tested
86% (2g)
1h (PhCH2SO2F, PMSF) low conversiong
a Conditions: 1.2 equiv LDA, 2.4 equiv TMSCl, 0.5 h.
b Conditions: 3.0 equiv LDA, 6.0 equiv TMSCl, 4.0 h.
c Competitive metalation at the methyl substituent occurs.
d Mixture of ortho-monosilylated product and ortho-, benzyl-disilylated
product (1:3) was formed in ca. 40% yield.
e An inseparable mixture of 2-bromo-3,6-bis(trimethylsilyl)benzenesulfonyl
fluoride and most likely 5-bromo-2-(trimethylsilyl)benzenesulfonyl fluoride
(2:3) was formed in ca. 76% yield.36
f Only 2f was observed in the crude reaction mixture after workup (1H and
19F NMR, GC).
g Crude reaction mixture after workup contained mainly unreacted 1h,
small amount of PhCHO (formed by an unknown mechanism), and ill-de-
fined silylated products (1H NMR,  = +0.2 to –0.1).
SO2F
OMe
SO2F
SO2F
OMe
SiMe3
Me3Si
SiMe3
+
SiMe3
LDA
(1.2)
LDA
(3.0)
Me3Si
products of
reactions
with 1g
OMe
2g, 86%
3g, 53%
3g', 43%
SO2F
SO2F
Me3Si
SiMe3
Me3Si
Br
n-BuLi (0.95)
TMSCl (2.0)
bromine–
lithium
3a, 91%a exchange
THF, –78 °C
0.5 h
2e
SO2F
O
B
SO2F
LDA (1.2)
HO
OH
B(Oi-Pr)3 (2.4)b
O
THF, –78 °C
0.5 h
toluene, r.t., 20 h
4, 58%
borylation
1a
Scheme 1 Products of mono- and disilylation of 4-methoxybenzene-
sulfonyl fluoride (1g, top), silylation of 2e by the bromine–lithium ex-
change (center), and borylation of 1a with B(Oi-Pr)3 as an electrophile
(bottom). Inside parentheses are the number of equivalents. a Yield of
3a was based on 2e (96% based on nominal concentration of n-BuLi
used). b Attempt at diborylation under difunctionalization conditions
gave only 4 (1H NMR, GC).
(the
Fritsch–Buttenberg–Wiechell
rearrangement).43
Hence, elucidation of the actual mechanism of formation of
2i′ requires further studies.
In the last part of the project, we focused on metalation
of aryl fluorosulfates (ArOSO2F),44,45 structurally related an-
alogues of arenesulfonyl fluorides (ArSO2F). Aryl fluorosul-
fates find numerous applications, mimicking reactivity of
To unequivocally establish structure of the monosilyla-
tion product of 2-bromobenzenesulfonyl fluoride, we sub-
jected 2e to a mixture of n-BuLi and trimethylsilyl chloride
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2019, 51, A–I

D
A. Talko et al.
Feature
Synthesis
1. LDA (1.2)
0.5 h
2. TMSCl (2.4)
5 min
fluorosulfate
O
aryne
trapping
product
SO2F
SO2F
Ph
Ph
O2
S
OSO2F
SiMe3
(1.2)
Ph
O
5, 19%
THF, –78 °C
+ mixture of
byproducts
1a
LDA (1.2)
THF, –78 °C
0.5 h
6a
premetalation of 1a leads
to a mixture containing
sulfonylation product 5
7, 54%
Ph
fluorosulfate
anionic Thia-Fries
CCDC 1894350
rearrangement
OSO2F
OH
Cl
O
Cl
SO2F
Ph
Ph
SO2F
1f recovered
in 70%
LDA (1.2)
THF, –78 °C
0.5 h
(1.2)
6b
8, 71%
no aryne
trapping
product
+
migration of the SO2F group
isobenzofuran
recovered
CCDC 1894351
LDA (1.2)
THF, –78 °C
0.5 h
in 78%a
1f
Scheme 3 Under metalation conditions aryl fluorosulfates undergo
elimination to the aryne [for 1-naphthyl fluorosulfate (6a), top], or mi-
gration of the SO2F group to the ortho position [for 2-chlorophenyl
fluorosulfate (6b), bottom]. Inside parentheses are the number of
equivalents. A similar effect of substitution on the reaction course was
observed for aryl triflates (ArOSO2CF3).48–50
LiTMP (1.2)b
TMSCl (2.4)
recovered 1i (46%)
SO2F
SO2F
+
α
β
+
SiMe3
THF, –78 °C
0.5 h
Ph
SiMe3
Ph
Ph
1i
2i, 12%
2i', 20%
α-silylation and elimination products
In conclusion, we have presented metalation studies of
arenesulfonyl fluorides (ArSO2F) ortho-directed by the fluoro-
sulfonyl group. Despite strong electrophilic character the
functionality displays directing effect for lithium amide
deprotometalation with in situ electrophile trapping.
Mono- and difunctionalization were demonstrated using
trimethylsilyl chloride as an electrophile, whereas with tri-
isopropyl borate only monosubstitution was observed. Ori-
entation of the substitution suggests that the SO2F is a more
powerful DoM group than methoxy and bromine. Attempts
at premetalation of model benzenesulfonyl fluoride have
failed, giving products of intermolecular sulfonylation. In-
terestingly, aryl fluorosulfates (ArOSO2F), close analogues of
arenesulfonyl fluorides, display different reactivity. 1-
Naphthyl fluorosulfate metalated in the presence of 1,3-di-
phenylisobenzofuran led to the aryne adduct (not observed
for 1-naphthalenesulfonyl fluoride). In turn, 2-chloro-
phenyl fluorosulfate displayed anionic thia-Fries rearrange-
ment with migration of the SO2F group to the 6-position of
the aromatic ring. Thus, for the two examples of aryl fluoro-
sulfates effect of substitution on the reaction course is the
same as for aryl triflates (ArOSO2CF3), described in the liter-
ature. The presented studies extend methodology of the
DoM chemistry, delivering new derivatives of sulfonyl fluo-
rides, and broadening understanding of reactivity of the
fluorosulfonyl group.
Scheme 2 Attempts at premetalation of sulfonyl fluoride (1a; top),
aryne trapping experiment on 1f (unsuccessful, center), and functional-
ization of the unsaturated (E)-2-phenylethene-1-sulfonyl fluoride 1i
(bottom). Inside parentheses are the number of equivalents. a After the
reaction, 1,3-diphenylisobenzofuran was recovered mainly as 1,2-
dibenzoylbenzene. b LDA was not tested.
aryl triflates (e.g., in metal-catalyzed coupling reactions)46
and displaying properties similar to arenesulfonyl fluorides
(e.g., as covalent enzyme inhibitors).45 When commercially
available 1-naphthyl fluorosulfate (6a) was treated with
LDA/TMSCl system, we obtained a complex mixture of
products, which contained numerous isopropyl groups ob-
1
served by H NMR spectroscopy. However, when the same
reaction was repeated with 1,3-diphenylisobenzofuran, in-
stead of TMSCl, an aryne trapping product 7 was isolated in
54% yield (Scheme 3, top).47 The observed reactivity of aryl
fluorosulfates (ArOSO2F) paralleled aryl triflates (ArOSO2CF3),
which under metalation conditions fragment to the
arynes.48 The similarity encouraged us to test yet another
transformation known for the latter class of compounds. In
2003, Lloyd-Jones reported that aryl triflates, substituted at
the ortho position with electron-withdrawing groups (e.g.,
halogens), undergo anionic thia-Fries rearrangement,
where the SO2CF3 group migrates to the ortho′ position of
the aromatic ring.49–52 Following the idea, we synthesized53
2-chlorophenyl fluorosulfate (6b), and subjected to the
metalation conditions with LDA. Surprisingly, the reaction
ran very clean, and after chromatography, the rearranged
product 8 was isolated in 71% yield. 1H NMR spectrum of 8
was similar to 3-chloro-2-hydroxyphenyl triflone, obtained
by rearrangement of 2-chlorophenyl triflate,50 whereas 19F
NMR displayed a new resonance at +59.1 ppm, characteris-
tic for sulfonyl fluorides (for substrate 6b,  = +40.4). Finally,
structure of 8 was unequivocally established by X-ray stud-
ies (Scheme 3, bottom right).
Benzenesulfonyl chloride, 4-methylbenzenesulfonyl chloride, 4-(tert-
butyl)benzenesulfonyl chloride, 3-nitrobenzenesulfonyl chloride, 1-
naphthalenesulfonyl chloride, 4-methoxybenzenesulfonyl chloride,
Bu4NCl, TMSCl, n-BuLi (2.5 M solution in hexanes), i-Pr2NH, lithium
bis(trimethylsilyl)amide (1.0 M solution in THF), 2,2-dimethylpro-
pane-1,3-diol, 1,3-diphenylisobenzofuran, 1-naphthyl fluorosulfate
(6a), THF (anhyd, inhibitor-free), and DMF (anhyd) were purchased
from Sigma-Aldrich. 2-Chlorophenol and B(Oi-Pr)3 were purchased
from Merck. MeI was purchased from Acros. 2-Bromobenzenesulfonyl
chloride, and potassium bis(trimethylsilyl)amide (20% solution in
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2019, 51, A–I

E
A. Talko et al.
Feature
Synthesis
THF) were purchased from Fluorochem. 2,2,6,6-Tetramethylpiperi-
dine was purchased from Fluka. KHF2 was purchased from Honeywell.
Phenylmethanesulfonyl fluoride (1h) was manufactured by Roche.
Commercially available solvents and materials were used without
further purification. Column chromatography was performed on sili-
ca gel (high-purity grade, pore size 60 Å, 230–400 mesh particle size,
40–63 m, 60737). Analytical GLC was performed on a PerkinElmer
Clarus 580 chromatograph equipped with a flame ionization detector,
and a GL Sciences InertCap 5MS/Sil column with He as a carrier gas
(column 0.25 mm × 30 m, carrier flow 1.5 mL/min, method parame-
ters 50 °C, +10 °C/min to 300 °C, then 15 min at 300 °C). 1H, 19F, and
13C NMR spectra were recorded on Agilent 400 MHz NMR spectrome-
ter. Chemical shifts () are given in parts per million (ppm) with the
solvent resonance as the internal standard (for CDCl3: 7.24 and 77.0
ppm; for acetone-d6: 2.05 and 29.84 ppm, for 1H and 13C NMR, respec-
tively) or with CFCl3 (0.0 ppm for 19F NMR). Standard abbreviations
were used for denoting spin multiplicity.
13C NMR (100 MHz, CDCl3):  = 165.2, 130.6, 123.6 (d, 2JC,F = 24.5 Hz),
114.8, 55.7.
19F NMR (376 MHz, CDCl3):  = 66.93, 66.89 (resonance of 34S mole-
cule, ca. 5%).
(E)-2-Phenylethene-1-sulfonyl Fluoride (1i)56
Yield: 1.821 g (9.78 mmol at 9.99 mmol scale, 98%); white crystals;
mp 96.5–97.5 °C (cyclohexane).
1H NMR (400 MHz, CDCl3):  = 7.80 (d, J = 15.5 Hz, 1 H), 7.57–7.49 (m,
3 H), 7.49–7.42 (m, 2 H), 6.85 (dd, J = 15.5, 2.5 Hz, 1 H).
13C NMR (100 MHz, CDCl3):  = 148.9 (d, 3JC,F = 2.7 Hz), 132.6, 130.9 (d,
4JC,F = 1.2 Hz), 129.4, 129.0, 117.9 (d, 2JC,F = 28.0 Hz).
19F NMR (376 MHz, CDCl3):  = 61.82, 61.76 (resonance of 34S mole-
cule, ca. 5%).
Sulfonyl Fluorides 1d, 1e, and 1f;9 General Procedure
Synthesis of benzenesulfonyl fluoride (1a) was reported recently by
us.9 (E)-2-Phenylethene-1-sulfonyl chloride (substrate for the prepa-
ration of 1i) was prepared according to the literature,54 mp 88.5–89.5 °C
(Lit.54 mp 89–90 °C).
A 50 mL round-bottomed flask was charged with an aq solution of
KHF2 (3.12 g in 8.04 g of H2O; ca. 28% w/w; 40.0 mmol), the respective
arenesulfonyl chloride (20.0 mmol), Bu4NCl (0.056 g, 0.20 mmol, 1
mol%), and DCM (22 mL), and the reaction mixture was stirred vigor-
ously at r.t. for 4 h (1d) and 48 h (1e and 1f). Then, the mixture was
transferred to a separatory funnel, extracted with DCM (3 × 50 mL),
and the combined organic phases were dried (MgSO4). The mixture
was filtered through a pad of silica gel (d = 4 cm; ∅ 6 cm), rinsed with
DCM (500 mL), and the combined filtrates were evaporated, and dried
in vacuo to obtain the desired sulfonyl fluoride. The products 1d, 1e,
and 1f were analytically pure.
Sulfonyl Fluorides 1b, 1c, 1g, and 1i;2,8 General Procedure
A round-bottomed flask was charged with KHF2 (15.6 g, 200 mmol)
and H2O (40.17 g) and the mixture was stirred at r.t. for 1 h. Then, a
solution of the required sulfonyl chloride (100 mmol) in MeCN (45
mL) was added, and the mixture was vigorously stirred for 20 h. Then,
the mixture was transferred to a separatory funnel, extracted with
DCM (2 × 100 mL), and the combined organic phases were dried
(MgSO4). The mixture was filtered, evaporated, and dried in vacuo to
obtain the desired sulfonyl fluoride. The crude products 1b, 1c, 1g,
and 1i were analytically pure.
3-Nitrobenzenesulfonyl Fluoride (1d)57
Yield: 3.714 g (18.10 mmol at 20.02 mmol scale, 90%), yellowish crys-
tals; mp 45–46.5 °C.
1H NMR (400 MHz, CDCl3):  = 8.82 (t, J = 2.0 Hz, 1 H), 8.63 (ddd, J =
8.3, 2.3, 1.0 Hz, 1 H), 8.34 (ddd, J = 7.9, 1.8, 1.0 Hz, 1 H), 7.92 (td, J =
8.1, 0.9 Hz, 1 H).
13C NMR (100 MHz, CDCl3):  = 148.3, 134.7 (d, 2JC,F = 27.6 Hz), 133.7,
131.4, 130.0, 123.7.
4-Methylbenzenesulfonyl Fluoride (1b)55
Yield: 16.693 g (95.8 mmol at 100.0 mmol scale, 96%); white crystals;
mp 39.5–41 °C.
1H NMR (400 MHz, CDCl3):  = 7.86 (d, J = 8.5 Hz, 2 H), 7.40 (d, J = 8.5
Hz, 2 H), 2.47 (s, 3 H).
13C NMR (100 MHz, CDCl3):  = 147.1, 130.2, 129.9 (d, 2JC,F = 24.2 Hz),
19F NMR (376 MHz, CDCl3):  = 65.88, 65.84 (resonance of 34S mole-
cule, ca. 5%).
128.4, 21.8.
19F NMR (376 MHz, CDCl3):  = 65.82, 65.78 (resonance of 34S mole-
cule, ca. 5%).
2-Bromobenzenesulfonyl Fluoride (1e)58
Yield: 4.577 g (19.14 mmol at 20.01 mmol scale, 96%); white solid;
mp 48–49 °C.
1H NMR (400 MHz, CDCl3):  = 8.12 (dd, J = 7.3, 2.4 Hz, 1 H), 7.83 (dd,
J = 7.3, 1.9 Hz, 1 H), 7.60–7.51 (m, 2 H).
13C NMR (100 MHz, CDCl3):  = 136.1, 135.9, 133.9 (d, 2JC,F = 24.3 Hz),
132.0 (d, 3JC,F = 1.6 Hz), 127.9, 121.0 (d, 3JC,F = 1.6 Hz).
19F NMR (376 MHz, CDCl3):  = 57.43, 57.38 (resonance of 34S mole-
4-(tert-Butyl)benzenesulfonyl Fluoride (1c)55
Yield: 4.261 g (19.70 mmol at 19.98 mmol scale, 99%); white solid;
mp 64–64.5 °C.
1H NMR (400 MHz, CDCl3):  = 7.91 (d, J = 8.8 Hz, 2 H), 7.62 (d, J = 8.8
Hz, 2 H), 1.35 (s, 9 H).
13C NMR (100 MHz, CDCl3):  = 159.9, 129.8 (d, 2JC,F = 24.2 Hz), 128.3,
cule, ca. 5%).
126.7, 35.5, 30.9.
19F NMR (376 MHz, CDCl3):  = 65.76, 65.72 (resonance of 34S mole-
cule, ca. 5%).
1-Naphthalenesulfonyl Fluoride (1f)11
Yield: 4.068 g (19.35 mmol at 20.00 mmol scale, 97%); white solid;
mp 52.5–53.5 °C.
1H NMR (400 MHz, CDCl3):  = 8.52 (ddd, J = 8.7, 3.0, 1.0 Hz, 1 H), 8.33
(ddd, J = 7.4, 1.3, 0.7 Hz, 1 H), 8.19 (dd, J = 8.3, 0.6 Hz, 1 H), 7.99–7.93
(m, 1 H), 7.74 (ddd, J = 8.5, 6.9, 1.4 Hz, 1 H), 7.65 (ddd, J = 8.1, 6.9, 1.1
Hz, 1 H), 7.57 (ddd, J = 8.2, 7.4, 1.5 Hz, 1 H).
4-Methoxybenzenesulfonyl Fluoride (1g)55
Yield: 3.651 g (19.20 mmol at 19.99 mmol scale, 96%); yellowish oil.
1H NMR (400 MHz, CDCl3):  = 7.89–7.82 (m, 2 H), 7.04–6.97 (m, 2 H),
3.86 (s, 3 H).
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2019, 51, A–I

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A. Talko et al.
Feature
Synthesis
3
13C NMR (100 MHz, CDCl3):  = 136.9, 134.0, 131.0 (d, JC,F = 1.9 Hz),
HRMS (ASAP): m/z [M – CH3]+ calcd for C12H18FO2SSi: 273.0781;
found: 273.0780.
2
3
129.4, 129.1, 128.9 (d, JC,F = 23.4 Hz), 128.2, 127.7, 124.05 (d, JC,F
=
1.2 Hz), 123.96.
19F NMR (376 MHz, CDCl3):  = 62.08, 62.04 (resonance of 34S mole-
2-Bromo-6-(trimethylsilyl)benzenesulfonyl Fluoride (2e)
cule, ca. 5%).
Yield: 0.537 g (1.73 mmol at 2.01 mmol scale, 86%); colorless oil; Rf =
0.50 (cyclohexane/toluene 3:1).
1H NMR (400 MHz, CDCl3):  = 7.84–7.76 (m, 2 H), 7.46 (t, J = 7.7 Hz, 1
Preparation of LDA
A 20 mL Schlenk flask was flushed with argon and charged with THF
(2 mL) and i-Pr2NH (0.36 mL, 2.57 mmol), and cooled in an ice-water
bath. Then, n-BuLi (0.95 mL, 2.38 mmol, 2.5 M in hexanes) was added
dropwise, and after 15 min, the mixture was transferred via syringe
to the reaction mixture. Volume of the THF remained constant (2 mL)
at the 2 mmol scale (for mono- and disilylation, and optimization
studies).
H), 0.40 (s, 9 H).
13C NMR (100 MHz, CDCl3):  = 146.7, 138.1 (d, 2JC,F = 21.4 Hz), 136.8,
135.5, 134.2, 123.0, 1.3 (d, 5JC,F = 0.8 Hz).
19F NMR (376 MHz, CDCl3):  = 61.58, 61.54 (resonance of 34S mole-
cule, ca. 5%).
MS (EI): m/z (%) = 297, 295 (63, 60, [M – CH3]+).
HRMS (ASAP): m/z [M – CH3]+ calcd for C8H979BrFO2SSi: 294.9260;
Silylation of Sulfonyl Fluorides 1; General Procedure
found: 294.9252.
A 30 mL Schlenk flask was charged with the respective sulfonyl fluo-
ride 1a–h (2.0 mmol), and flushed with argon. Then, THF (2 mL) was
added, the flask was placed in a cooling bath at –78 °C, and TMSCl
(0.61 mL, 4.81 mmol) was added. To the resulting solution was added
a solution of LDA slowly over ca. 1 min. When the reaction was com-
plete (see Table 1 and Supporting Information for the reaction condi-
tions), the cooling bath was removed, and diluted aq HCl (10 mL,
3.5%) was added with vigorous stirring. Then, H2O (50 mL) was added,
and the resulting mixture was extracted with EtOAc (3 × 50 mL). The
combined organic phases were washed with brine (50 mL) and dried
(MgSO4). Then, the mixture was filtered, evaporated, and the residue
was separated by column chromatography (d = 34 cm; ∅ 3 cm; SiO2)
and eluted with cyclohexane, then cyclohexane/toluene to obtain the
respective monosilylated product 2.
2-(Trimethylsilyl)-1-naphthalenesulfonyl Fluoride (2f)
Yield: 0.481 g (1.70 mmol at 2.00 mmol scale, 85%); white solid; mp
26–27 °C; Rf = 0.49 (cyclohexane/toluene 3:1).
1H NMR (400 MHz, CDCl3):  = 8.64 (ddd, J = 8.9, 4.7, 1.0 Hz, 1 H), 8.08
(dd, J = 8.3, 0.9 Hz, 1 H), 7.92–7.83 (m, 2 H), 7.69 (ddd, J = 8.7, 6.9, 1.5
Hz, 1 H), 7.60 (ddd, J = 8.0, 6.9, 1.1 Hz, 1 H), 0.54 (s, 9 H).
13C NMR (100 MHz, CDCl3):  = 145.1, 134.7 (d, 2JC,F = 21.2 Hz), 134.4,
134.1, 130.8, 129.4, 128.9, 128.6, 127.5, 124.5 (d, 3JC,F = 3.2 Hz), 1.5.
19F NMR (376 MHz, CDCl3):  = 66.20 (d, J = 4.9 Hz), 66.16 (d, J = 4.9
Hz; resonance of 34S molecule, ca. 5%).
MS (EI): m/z (%) = 282 (4, [M]+), 267 (95, [M – CH3]+).
HRMS (EI): m/z [M]+ calcd for C13H15FO2SSi: 282.0546; found:
Disilylations and optimization studies were carried out accordingly,
with reactant ratios and conditions listed in Table 1 and Supporting
Information.
282.0560.
4-Methoxy-2-(trimethylsilyl)benzenesulfonyl Fluoride (2g)
Yield: 0.454 g (1.73 mmol at 2.01 mmol scale, 86%); colorless oil; Rf =
0.24 (cyclohexane/toluene 3:1).
1H NMR (400 MHz, CDCl3):  = 8.07 (dd, J = 8.9, 0.7 Hz, 1 H), 7.29 (d, J =
2.7 Hz, 1 H), 6.98 (ddd, J = 8.9, 2.7, 0.8 Hz, 1 H), 3.88 (s, 3 H), 0.39 (s, 9
2-(Trimethylsilyl)benzenesulfonyl Fluoride (2a)
Yield: 0.379 g (1.63 mmol at 2.04 mmol scale, 80%); colorless oil; Rf =
0.51 (cyclohexane/EtOAc 6:1).
1H NMR (400 MHz, CDCl3):  = 8.13 (ddt, J = 7.9, 1.1, 0.5 Hz, 1 H), 7.84
(ddt, J = 7.6, 1.3, 0.6 Hz, 1 H), 7.69 (tdt, J = 7.5, 1.3, 0.6 Hz, 1 H), 7.58
(ddt, J = 7.9, 7.4, 1.3 Hz, 1 H), 0.41 (s, 9 H).
13C NMR (100 MHz, CDCl3):  = 142.1, 137.9 (d, 2JC,F = 22.6 Hz), 137.0,
134.2, 130.3, 129.7, 0.2 (d, 5JC,F = 1.4 Hz).
19F NMR (376 MHz, CDCl3):  = 66.20, 66.16 (resonance of 34S mole-
cule, ca. 5%).
MS (EI): m/z (%) = 217 (90, [M – CH3]+), 153 (54, [M – CH3 – SO2]+).
HRMS (ASAP): m/z [M – CH3]+ calcd for C8H10FO2SSi: 217.0155; found:
H).
2
13C NMR (100 MHz, CDCl3):  = 163.7, 144.5, 133.4, 128.5 (d, JC,F
=
23.0 Hz), 123.8, 113.0, 55.5, 0.0 (d, 5JC,F = 1.2 Hz).
19F NMR (376 MHz, CDCl3):  = 67.86, 67.82 (resonance of 34S mole-
cule, ca. 5%).
MS (EI): m/z (%) = 262 (2, [M]+), 247 (100, [M – CH3]+), 183 (11, [M –
CH3 – SO2]+).
HRMS (EI): m/z [M]+ calcd for C10H15FO3SSi: 262.0495; found:
262.0499.
217.0154.
2,6-Bis(trimethylsilyl)benzenesulfonyl Fluoride (3a)
4-tert-Butyl-2-(trimethylsilyl)benzenesulfonyl Fluoride (2c)
Yield: 0.452 g (1.48 mmol at 2.01 mmol scale, 74%); white solid; mp
77.5–78 °C; Rf = 0.66 (cyclohexane/EtOAc 6:1).
1H NMR (400 MHz, CDCl3):  = 7.86 (d, J = 7.5 Hz, 2 H), 7.60 (t, J = 7.5
Hz, 1 H), 0.41 (s, 18 H).
13C NMR (100 MHz, CDCl3):  = 143.9, 142.5 (d, 2JC,F = 20.9 Hz), 137.6,
132.4, 1.2 (d, 5JC,F = 1.4 Hz).
19F NMR (376 MHz, CDCl3):  = 66.41, 66.37 (resonance of 34S mole-
Yield: 0.378 g (1.31 mmol at 2.00 mmol scale, 65%); white crystals;
mp 71–72 °C; Rf = 0.52 (cyclohexane/toluene 3:1).
1H NMR (400 MHz, CDCl3):  = 8.07 (d, J = 8.4 Hz, 1 H), 7.88 (d, J = 2.1
Hz, 1 H), 7.59 (ddd, J = 8.4, 2.1, 1.0 Hz, 1 H), 1.36 (s, 9 H), 0.43 (s, 9 H).
13C NMR (100 MHz, CDCl3):  = 157.8, 141.6, 134.9 (d, 2JC,F = 22.6 Hz),
134.1, 130.5, 126.7, 35.5, 30.9, 0.2 (d, 5JC,F = 1.4 Hz).
19F NMR (376 MHz, CDCl3):  = 66.69, 66.65 (resonance of 34S mole-
cule, ca. 5%).
MS (EI): m/z (%) = 273 (99, [M – CH3]+), 209 (18, [M – CH3 – SO2]+).
cule, ca. 5%).
MS (EI): m/z (%) = 289 (67, [M – CH3]+), 225 (32, [M – CH3 – SO2]+).
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2019, 51, A–I

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HRMS (ASAP): m/z [M – CH3]+ calcd for C11H18FO2SSi2: 289.0550;
5,5-Dimethyl-2-(2-fluorosulfonylphenyl)-1,3,2-dioxaborinane (4)
found: 289.0547.
Yield: 0.315 g (1.16 mmol at 2.00 mmol scale; 58%); colorless oil; Rf =
0.48 (cyclohexane/EtOAc 2:1).
4-tert-Butyl-2,6-bis(trimethylsilyl)benzenesulfonyl Fluoride (3c)
1H NMR (400 MHz, CDCl3):  = 8.00 (ddt, J = 8.0, 1.1, 0.6 Hz, 1 H), 7.72–
Yield: 0.354 g (0.98 mmol at 2.00 mmol scale, 49%); white solid; mp
7.63 (m, 2 H), 7.57–7.50 (m, 1 H), 3.77 (s, 4 H), 1.05 (s, 6 H).
131.5–132.5 °C; Rf = 0.68 (cyclohexane/toluene 3:1).
1H NMR (400 MHz, CDCl3):  = 7.93 (s, 2 H), 1.38 (s, 9 H), 0.45 (s, 18
H).
13C NMR (100 MHz, CDCl3):  = 135.5 (d, 2JC,F = 23.2 Hz), 134.3, 133.8,
129.6, 128.8, 72.7, 31.8, 21.8 (one resonance was beyond the detec-
tion limit).
13C NMR (100 MHz, CDCl3):  = 155.2, 143.5, 139.6 (d, 2JC,F = 21.0 Hz),
134.8, 35.5, 31.0, 1.2 (d, 5JC,F = 1.2 Hz).
19F NMR (376 MHz, CDCl3):  = 64.97, 64.93 (resonance of 34S mole-
cule, ca. 5%).
19F NMR (376 MHz, CDCl3):  = 66.89, 66.84 (resonance of 34S mole-
MS (EI): m/z (%) = 272 (36, [M]+).
cule, ca. 5%).
HRMS (EI): m/z [M]+ calcd for C11H1411BFO4S: 272.0690; found:
272.0693.
MS (EI): m/z (%) = 345 (72, [M – CH3]+), 281 (36, [M – CH3 – SO2]+).
HRMS (ASAP): m/z [M – CH3]+ calcd for C15H26FO2SSi2: 345.1176;
found: 345.1177.
Premetalation of 1a
Premetalation of 1a was performed according to the General Proce-
dure for monosilylation, but TMSCl was added 30 min after the addi-
tion of the LDA solution and quenched after next 5 min. The reaction
mixture was separated by two column chromatographies using cyclo-
hexane/EtOAc as eluent. The only characterized product was 5,
whereas other fractions contained mixture of ill-defined products.
4-Methoxy-2,6-bis(trimethylsilyl)benzenesulfonyl Fluoride (3g)
Yield: 0.357 g (1.07 mmol at 2.00 mmol scale, 53%); colorless oil; Rf =
0.54 (cyclohexane/toluene 3:1).
1H NMR (400 MHz, CDCl3):  = 7.32 (s, 2 H), 3.90 (s, 3 H), 0.41 (d, 6JH,F
1.2 Hz, 18 H).
=
13C NMR (100 MHz, CDCl3):  = 161.9, 147.2, 133.3 (d, 2JC,F = 21.7 Hz),
122.6, 55.3, 1.1 (d, 5JC,F = 1.1 Hz).
19F NMR (376 MHz, CDCl3):  = 67.92, 67.88 (resonance of 34S mole-
6-Phenylsulfonyl-2-(trimethylsilyl)benzenesulfonyl Fluoride (5)
Yield: 0.070 g (0.188 mmol at 2.01 mmol scale, 19%); white solid; mp
114.5–115.5 °C; Rf = 0.14 (cyclohexane/EtOAc 6:1).
cule, ca. 5%).
1H NMR (400 MHz, CDCl3):  = 8.58 (ddd, J = 7.8, 1.4, 0.5 Hz, 1 H), 8.11
(dt, J = 7.7, 1.2 Hz, 1 H), 7.92–7.82 (m, 3 H), 7.61–7.55 (m, 1 H), 7.53–
7.47 (m, 2 H), 0.41 (d, 6JH,F = 0.7 Hz, 9 H).
13C NMR (100 MHz, CDCl3):  = 148.2, 142.7, 141.3, 141.0, 137.0 (d,
2JC,F = 26.4 Hz), 134.3, 133.7, 133.3, 128.8, 127.8, 1.4 (d, 5JC,F = 1.5 Hz).
MS (EI): m/z (%) = 334 (1, [M]+), 319 (100, [M – CH3]+), 255 (9, [M –
CH3 – SO2]+).
HRMS (EI): m/z [M]+ calcd for C13H23FO3SSi2: 334.0891; found:
334.0888.
19F NMR (376 MHz, CDCl3):  = 68.37, 68.33 (resonance of 34S mole-
cule, ca. 5%).
MS (EI): m/z (%) = 357 (100, [M – CH3]+).
HRMS (ASAP): m/z [M – CH3]+ calcd for C14H14FO4S2Si: 357.0087;
4-Methoxy-2,5-bis(trimethylsilyl)benzenesulfonyl Fluoride (3g′)
Yield: 0.290 g (0.87 mmol at 2.00 mmol scale, 43%); white solid; mp
89–92 °C; Rf = 0.53 (cyclohexane/toluene 3:1).
1H NMR (400 MHz, CDCl3):  = 8.07 (d, 4JH,F = 0.6 Hz, 1 H), 7.18 (s, 1 H),
3.92 (s, 3 H), 0.41 (d, 6JH,F = 0.7 Hz, 9 H), 0.28 (s, 9 H).
13C NMR (100 MHz, CDCl3):  = 167.9, 146.4, 137.7, 130.3, 128.8 (d,
2JC,F = 21.7 Hz), 116.9, 55.4, 0.2, –1.5.
found: 357.0083.
Crystals suitable for X-ray studies were grown by dissolution of 5 in
hot cyclohexane in NMR tube and leaving at r.t.59
19F NMR (376 MHz, CDCl3):  = 68.11, 68.06 (resonance of 34S mole-
cule, ca. 5%).
Aryne Trapping Experiments
Aryne trapping experiments were performed with 1f and 6a as sub-
strates according to the General Procedure (1.0 mmol scale) with LDA
(1.2 mmol), 1,3-diphenylisobenzofuran (0.321 g, 1.19 mmol), and
THF (5 mL).
MS (EI): m/z (%) = 334 (5, [M]+), 319 (100, [M – CH3]+), 255 (7, [M –
CH3 – SO2]+).
HRMS (EI): m/z [M]+ calcd for C13H23FO3SSi2: 334.0891; found:
334.0891.
In experiment with 1f (0.212 g, 1.01 mmol), after chromatography,
1,3-diphenylisobenzofuran (0.028 g, 0.103 mmol, 9% of recovery), 1f
(0.150 g, 0.712 mmol, 70% of recovery), and 1,2-dibenzoylbenzene
(0.235 g, 0.821 mmol, 69% of recovery, based on 1,3-diphenylisoben-
zofuran) were isolated besides a mixture of ill-defined decomposition
products (0.130 g).
Borylation of 1a
Borylation of 1a was performed according to the General Procedure
using B(Oi-Pr)3 (1.1 mL, 4.80 mmol), instead of TMSCl. After drying
(MgSO4), the mixture was filtered, evaporated, and 2,2-dimethyl-1,3-
propanediol (neo-pentyl glycol; 0.254 g, 2.43 mmol) and toluene (8
mL) were added, and the mixture was stirred at r.t. for 20 h. Then, the
solvent was evaporated and the residue was separated by column
chromatography (d = 18 cm; ∅ 3 cm; SiO2) and eluted with cyclohex-
ane/EtOAc to obtain 4.
1,2-Dibenzoylbenzene60
Isolated after trapping experiments; white solid; mp 145.5–146.5 °C;
Rf = 0.24 (cyclohexane/EtOAc 6:1).
1H NMR (400 MHz, CDCl3):  = 7.72–7.65 (m, 4 H), 7.62–7.55 (m, 4 H),
7.51–7.45 (m, 2 H), 7.37–7.30 (m, 4 H).
13C NMR (100 MHz, CDCl3):  = 196.4, 139.9, 137.0, 132.9, 130.3,
129.7, 129.5, 128.2.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2019, 51, A–I

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A. Talko et al.
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Synthesis
In experiment with 6a (0.227 g, 1.00 mmol), after chromatography,
1,3-diphenylisobenzofuran (0.138 g, 0.510 mmol, 43% of recovery)
and aryne adduct 7 (0.214 g, 0.540 mmol, 54%) were isolated besides
a mixture of ill-defined decomposition products (0.109 g), which con-
tained also some amount of 1,2-dibenzoylbenzene.
19F NMR (376 MHz, CDCl3):  = 40.40, 40.36 (resonance of 34S mole-
cule, ca. 5%).
MS (EI): m/z (%) = 212, 210 (39, 96, [M]+), 129, 127 (33, 99, [M –
SO2F]+).
HRMS (EI): m/z [M]+ calcd for C6H435ClFO3S: 209.9554; found:
209.9551.
7,12-Diphenyl-7,12-dihydro-7,12-epoxybenz[a]anthracene (7)61
White solid; mp 200 °C (dec.); Rf = 0.49 (cyclohexane/EtOAc 6:1).
1H NMR (400 MHz, CDCl3):  = 8.10–8.03 (m, 2 H), 8.03–7.98 (m, 2 H),
7.85–7.80 (m, 1 H), 7.69 (ddd, J = 7.1, 1.3, 0.7 Hz, 1 H), 7.66–7.48 (m, 9
H), 7.39 (ddd, J = 7.0, 1.2, 0.7 Hz, 1 H), 7.34 (ddd, J = 8.2, 6.8, 1.3 Hz, 1
H), 7.26 (ddd, J = 8.3, 6.8, 1.3 Hz, 1 H), 7.05 (ddd, J = 7.6, 7.1, 1.3 Hz, 1
H), 7.00 (ddd, J = 7.6, 7.1, 1.2 Hz, 1 H).
13C NMR (100 MHz, CDCl3):  = 153.2, 150.7, 149.3, 147.8, 134.9,
134.6, 132.7, 130.2, 129.4, 128.9, 128.72, 128.70, 128.4, 128.0, 127.5,
127.2, 125.9, 125.4, 125.23, 125.18, 123.6, 122.0, 120.7, 119.0, 93.0,
91.0.
Anionic Thia-Fries Rearrangement of 6b
Anionic thia-Fries rearrangement of 6b was performed according to
the General Procedure for monosilylation without TMSCl.
3-Chloro-2-hydroxybenzenesulfonyl Fluoride (8)
Yield: 0.075 g (0.355 mmol at 0.502 mmol scale, 71%); off-white solid;
mp 74.5–78.5 °C; Rf = 0.33 (cyclohexane/EtOAc 2:1).
1H NMR (400 MHz, acetone-d6):  = 7.90–7.84 (m, 2 H), 7.80–7.50 (br
s, 1 H), 7.17 (td, J = 8.1, 1.6 Hz, 1 H).
13C NMR (100 MHz, acetone-d6):  = 153.4, 138.2, 130.1, 124.1, 122.4
(d, 2JC,F = 23.5 Hz), 121.4.
Silylation of (E)-2-Phenylethene-1-sulfonyl Fluoride (1i)
19F NMR (376 MHz, acetone-d6):  = 59.10, 59.06 (resonance of 34S
molecule, ca. 5%).
Silylation of (E)-2-phenylethene-1-sulfonyl fluoride (1i) was per-
formed according to the General Procedure for monosilylation with
LiTMP (2.4 mmol) as a base. After column chromatography with cy-
clohexane/EtOAc as eluent, followed by column chromatography us-
ing cyclohexane/toluene as eluent, 2i, 2i′, and unreacted 1i (0.171 g,
0.92 mmol, 46%) were isolated besides unidentified by-products.
MS (EI): m/z (%) = 212, 210 (33, 68, [M]+), 192, 190 (27, 61, [M – HF]+),
128, 126 (27, 61, [M – HF – SO2]+).
HRMS (EI): m/z [M – CH3]+ calcd for C6H435ClFO3S: 209.9554; found:
209.9558.
Crystals of 8 suitable for X-ray studies were grown by slow evapora-
(E)-2-Phenyl-1-(trimethylsilyl)ethene-1-sulfonyl Fluoride (2i)
tion of heptane solution from glass vial on air (ca. 2 days).59
Yield: 0.060 g (0.23 mmol at 1.99 mmol scale, 12%); white solid; mp
51–52.5 °C; Rf = 0.48 (cyclohexane/EtOAc 6:1).
1H NMR (400 MHz, CDCl3):  = 8.53 (s, 1 H, H), 7.45–7.37 (m, 3 H,
Funding Information
H
meta,para), 7.33–7.26 (m, 2 H, Hortho), 0.2 [d, J = 1.0 Hz, 9 H, Si(CH3)3].
3
13C NMR (100 MHz, CDCl3):  = 159.0 (d, JC,F = 2.0 Hz, C), 139.2 (d,
This work was financed by the SONATA BIS program of the Narodowe
Centrum Nauki (National Science Centre, Poland, NCN; Grant No.
2JC,F = 16.4Hz, C), 134.3 (d, JC,F = 2.0 Hz, Cipso), 130.2 (Cpara), 128.5
4
(Cmeta), 128.3 (d, 5JC,F = 0.8 Hz, Cortho), 0.1 [d, 4JC,F = 1.1 Hz, Si(CH3)3].
DEC-2013/10/E/ST5/00030).
N
aro
d
o
w
e
C
e
ntur
m
N
a
u
k
i (D
E
C-2
0
1
3/10/E/S
T
5/0
0
0
3
0)
19F NMR (376 MHz, CDCl3):  = 59.79, 59.75 (resonance of 34S mole-
cule, ca. 5%).
Supporting Information
HRMS (ASAP): m/z [M – CH3]+ calcd for C10H12FO2SSi: 243.0311;
found: 243.0300.
Supporting information for this article is available online at
https://doi.org/10.1055/s-0037-1610877.
S
u
p
p
orti
n
gInformati
o
n
S
u
p
p
orti
n
gInformati
o
n
Structure assignment was based on HSQC, HMBC, and NOE experi-
ments.
References
2-Phenyl-1-(trimethylsilyl)acetylene (2i′)62
Yield: 0.070 g (0.40 mmol at 1.99 mmol scale, 20%); yellowish oil; Rf =
0.65 (cyclohexane/EtOAc 6:1).
1H NMR (400 MHz, CDCl3):  = 7.50–7.44 (m, 2 H), 7.33–7.25 (m, 3 H),
0.26 (s, 9 H).
13C NMR (100 MHz, CDCl3):  = 131.9, 128.5, 128.2, 123.1, 105.1, 94.0,
0.0.
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© Georg Thieme Verlag Stuttgart · New York — Synthesis 2019, 51, A–I