Green Organocatalytic Oxidation of Sulfides to Sulfoxides and Sulfones

Article abstract of DOI:10.1055/s-0036-1588315

A highly efficient synthetic methodology towards the selective synthesis of sulfoxides and sulfones is reported using a cheap and green organocatalytic method. Starting from sulfides and using 2,2,2-trifluoroacetophenone as the organocatalyst and H₂O₂ as the oxidant, the high-yielding preparation of sulfoxides or sulfones is described, being dependent on the reaction conditions.

Full text of DOI:10.1055/s-0036-1588315

SYNTHESIS
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© Georg Thieme Verlag Stuttgart · New York
2016, 48, A–H
paper
A
E. Voutyritsa et al.
Paper
Synthesis
Green Organocatalytic Oxidation of Sulfides to Sulfoxides and Sul-
fones
Errika Voutyritsa
O
O
O
O
Ierasia Triandafillidi
catalyst (10 mol%)
catalyst (20 mol%)
S
S
S
R1
Christoforos G. Kokotos*
R1
R2
H2O2
t-BuOH, buffer
R2
CF3
MeCN, H2O2
t-BuOH, buffer
R2
R1
Laboratory of Organic Chemistry, Department of
Chemistry, National and Kapodistrian University of
Athens, Panepistimiopolis, Athens 15771, Greece
ckokotos@chem.uoa.gr
catalyst
15 examples 50–91% yield
15 examples 50–100% yield
Organocatalytic
Cheap
Green
Sustainable
High selectivity
Received: 29.06.2016
Accepted after revision: 26.08.2016
Published online: 21.09.2016
H
O
H
S
O
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O
DOI: 10.1055/s-0036-1588315; Art ID: ss-2016-z0467-op
Nexium
O
Abstract A highly efficient synthetic methodology towards the selec-
tive synthesis of sulfoxides and sulfones is reported using a cheap and
green organocatalytic method. Starting from sulfides and using 2,2,2-
trifluoroacetophenone as the organocatalyst and H2O2 as the oxidant,
the high-yielding preparation of sulfoxides or sulfones is described, be-
ing dependent on the reaction conditions.
Provigil
O
O
S
H2N
NH2
Dapsone
Key words organocatalytic oxidation, sulfoxides, sulfones, hydrogen
peroxide, green chemistry
O
O
O
O
F
S
S
Me
Me
N
O
O
Sulfoxides and sulfones are very important moieties
used in medicinal chemistry and especially in the backbone
of marketed therapeutics1 such as Nexium,2a Provigil,2b the
antibacterial Dapsone,3 Laropiprant4 and the COX-2 inhibi-
tor Vioxx (Figure 1).5 They constitute a common motif in
agrochemicals6 and ligands for transition-metal asymmet-
ric catalysis.7 Also, they are commonly occurring in natural
products with active biological character.8 Moreover, sul-
fide oxidation is the basis for the catalytic oxidative desul-
furization of crude oil, in which sulfur compounds are re-
moved.9 For all these reasons, selective oxidation of sulfides
to either sulfoxides or sulfones is one of the most common
challenges in sulfur chemistry.
As a result, numerous strategies for the selective oxida-
tion of sulfides have been reported. The most traditional
method involves oxidants such as nitric acid, m-chloroper-
benzoic acid,10 UHP,11 NaClO,12 NaIO4,13 Oxone14 or dimeth-
yldioxirane (Scheme 1, path a).15 These methods utilize ex-
pensive reagents in stoichiometric amounts and require
long reaction times. Recently, hydrogen peroxide has been
widely employed as the oxidant and a variety of catalysts
have been developed. Transition-metal catalysts have been
Cl
COOH
Laropiprant
Vioxx
Figure 1 Marketed drugs containing a sulfoxide or a sulfone
reported based on iron,16 manganese,17 zinc18 and a variety
of other metals for the activation of hydrogen peroxide
(Scheme 1, path b). Unfortunately, drawbacks of metal cata-
lysts, such as toxicity and high levels of inorganic waste,
make this method harmful for the environment. Therefore,
metal-free catalysts have been developed with examples
including enzymes19 or flavin-based catalysts (Scheme 1,
path c).20 Furthermore, catalyst-free protocols have been
devised, but only for sulfone synthesis.21 Although, poly-
mers22 have been used to improve the selective oxidation of
sulfides, leading to the desired products in good yields, un-
fortunately, harsh reaction conditions and long reaction
times have to be employed (Scheme 1, path d).
In this work, we employed the green organocatalytic ox-
idative protocol that was developed in our laboratory,23 us-
ing hydrogen peroxide as the oxidant and 2,2,2-trifluoroac-
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–H

B
E. Voutyritsa et al.
Paper
Synthesis
Initially, we optimized the reaction conditions for the
synthesis of sulfoxides (Table 1). Employing 10 mol% of the
catalyst, optimization of the amount of hydrogen peroxide
in order to improve the yield of the desired sulfoxide was
performed (Table 1, entries 1–6). The presence of the cata-
lyst and the aqueous buffer were found to be indispensable
for obtaining high yields of the sulfoxide.
Previous work
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S
R1
R1
R2
R2
R1
R2
a
d
polymers
Having optimized the reaction conditions, we turned
our focus on studying the application of this method with a
variety of substrates (Scheme 2). A series of sulfides was
tested affording the desired products in excellent yields.
Specifically, phenyl sulfides bearing an aliphatic moiety af-
forded the desired sulfoxides in high to quantitative yields
(Scheme 2, products 2a–f). Furthermore, ortho-substituted
phenyl sulfide 1g gave sulfoxide 2g in excellent yield. When
the phenyl sulfide had another substituent containing an
aromatic group, the reaction required more time to reach
completion affording the desired products in very good
variety of
oxidants
H2O2
c
b
metal catalysts
metal-free catalysts
This work
O
CF3
O
S
O
O
S
S
catalyst
H2O2
or
R1
R1
R2
R2
R1
R2
> Cheap
> Green
> Selectivity
O
O
S
10 mol%
Ph
S
CF3
R1
R2
R1
R2
H2O2, t-BuOH, buffer, r.t.,
Scheme 1 Synthetic pathways for the selective synthesis of sulfoxides
and sulfones
1–18 h
1a–p
2a–p
O
S
O
S
O
etophenone as the catalyst. Herein, we have introduced a
cheap, green and environmentally friendly protocol, which
achieves the selective oxidation of sulfides to sulfoxides or
sulfones, being dependent on the reaction conditions. The
advantages of this protocol, such as commercial availability,
low-priced reagents, short reaction time and mild reaction
conditions, serve to make it one of the most easy and user-
friendly oxidation methods (Scheme 1, bottom).
S
68%, 2c
82%, 2a
60%, 2b
O
S
O
S
O
S
O
O
Table 1 Optimization of the Reaction Conditions for the Organocata-
lytic Synthesis of Sulfoxides
50%, 2e
63%, 2d
64%, 2f
O
S
O
S
O
S
O
O
Ph
CF3
S
S
O
conditions
t-BuOH,
1 h, r.t.
91%, 2g
60%, 2h
81%, 2i
1a
2a
O
S
Entry
Cat.
MeCN
(equiv)
H2O2
(equiv)
Bufferb
Yield
(%)c
(mol%)a
O
S
O
S
1
2
3
4
5
6
10
10
0
–
–
3
–
–
–
1.1
3
yes
yes
no
59
83
38
0
86%, 2j
81%, 2m
55%, 2k
3
O
S
0
1.5
1.5
1.5
yes
no
S
S
O
10
10
90
96
O
yes
79%, 2n
89%, 2o
78%, 2p
a 2,2,2-Trifluoroacetophenone was used as the catalyst.
b Aqueous buffer (pH 11) was used.
Scheme 2 Substrate scope for the selective organocatalytic oxidation
of sulfides to sulfoxides
c Yield determined from the crude 1H NMR spectrum.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–H

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E. Voutyritsa et al.
Paper
Synthesis
yields (Scheme 2, products 2h–j). Moreover, benzyl sulfides
were tested and resulted in the isolation of the correspond-
ing products in satisfactory yields (Scheme 2, products 2k
and 2m). Finally, a range of aliphatic sulfides was oxidized
in excellent yields (Scheme 2, products 2n–p).
O
20 mol%
Ph
O
S
S
CF3
R1
R2
R1
R2
H2O2, MeCN
t-BuOH, buffer
r.t., 1–18 h
1a–p
3a–p
In the next step, we studied the synthesis of sulfones
(Table 2). Once the amount of the oxidant had been opti-
mized (Table 2, entries 1–4), different polar and non-polar
solvents were tested (Table 2, entries 5–12), in order to find
the most suitable conditions. Column chromatography
proved to be unnecessary in order to isolate the desired sul-
fone, since the product could be isolated in pure form after
the oxidation via simple extractions.
O
O
O
O
O
O
S
S
S
100%, 3c
100%, 3a
100%, 3b
O
S
O
O
O
O
O
S
S
Table 2 Optimization of the Reaction Conditions for the Organocata-
O
lytic Synthesis of Sulfones
98%, 3e
75%, 3g
50%, 3d
O
O
O
O
Ph
CF3
O
O
S
S
S
O
O
S
S
O
conditions
buffer, 1 h, r.t.
1a
3a
80%, 3h
90%, 3i
100%, 3j
Entry
Cat.
MeCN
(equiv)
H2O2
(equiv)
Solvent
Yield
(%)b
(mol%)a
O
O
O
O
O
O
1
2
10
10
5
2
3
3
3
3
3
3
3
3
3
3
3
2
3
3
3
3
3
3
3
3
3
3
3
t-BuOH
t-BuOH
t-BuOH
t-BuOH
EtOAc
49
88
54
100
80
85
64
76
45
40
39
5
S
S
S
OH
3
82%, 3m
87%, 3k
82%, 3l
4
20
20
20
20
20
20
20
20
20
O
O
5
S
S
S
6
MeOH
MeCN
O
O
O
O
7
100%, 3n
100%, 3o
92%, 3p
8
THF
Scheme 3 Substrate scope for the selective organocatalytic oxidation
of sulfides to sulfones
9
CHCl3
10
11
12
toluene
benzene
DMSO
Overall, the organocatalytic oxidation of sulfides to sulf-
oxides requires the presence of a catalyst, aqueous buffer
and H2O2. The aqueous environment shifts the equilibrium
of the ketone–diol of the activated carbonyl group of the
catalyst toward the diol, which is oxidized by H2O2 to the
corresponding perhydrate.23 We believe that this perhy-
drate is the active oxidant for the oxidation to the sulfoxide.
On the other hand, once MeCN is added to the reaction
mixture, Payne’s intermediate, which is formed under the
basic conditions of the reaction mixture, as well as our pre-
viously described organocatalytic system,23 are in place and
shift the oxidation toward sulfone formation.
a 2,2,2-Trifluoroacetophenone was used as the catalyst.
b Yield determined from the crude 1H NMR spectrum.
Among the substrates that were tested, phenyl sulfides
containing an aliphatic moiety afforded the desired sul-
fones in high yields (Scheme 3, products 3a–e). An ortho-
substituted sulfide also underwent the oxidation to give the
corresponding phenyl sulfone in very good yield (Scheme 3,
product 3g). Other substituted sulfides bearing an aromatic
group were employed successfully, affording the desired
products in very good yields (Scheme 3, products 3h–j).
Moreover, benzyl sulfides were transformed into the corre-
sponding sulfones in high yields (Scheme 3, products 3k–
m) via this method. Finally, a range of aliphatic sulfides was
successfully oxidized to the corresponding sulfones in ex-
cellent yields (Scheme 3, products 3n–p).
In conclusion, the selective organocatalytic oxidation of
sulfides to sulfoxides or sulfones is described. Utilizing dif-
ferent organocatalytic conditions, the desired products
were obtained by employing a cheap and environmentally
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–H

D
E. Voutyritsa et al.
Paper
Synthesis
friendly organic molecule as the catalyst. This protocol was
applied on a variety of aromatic and aliphatic sulfides af-
fording sulfoxides and sulfones in high yields.
Colorless oil; yield: 113 mg (68%).
1H NMR (200 MHz, CDCl3): δ = 7.58–7.50 (m, 2 H, ArH), 7.47–7.37 (m,
3 H, ArH), 5.70–5.44 (m, 1 H, =CH), 5.26 (d, J = 9.3 Hz, 1 H, =CHH), 5.12
(d, J = 17.4 Hz, 1 H, =CHH), 3.52 (dd, J = 12.5, 6.1 Hz, 1 H, CHH), 3.43
(dd, J = 12.5, 7.1 Hz, 1 H, CHH).
13C NMR (50 MHz, CDCl3): δ = 142.5, 130.9, 128.8, 125.0, 124.1, 123.8,
60.5.
MS (ESI): m/z (%) = 167 (100) [M + H]+.
Chromatographic purification of the products was accomplished us-
ing forced-flow chromatography on Merck® Kieselgel 60 F254 (230–
400 mesh). Thin-layer chromatography (TLC) was performed on
Merck aluminum-backed silica plates (0.2 mm, 60 F254). Visualization
of the developed chromatogram was performed by fluorescence
quenching using phosphomolybdic acid, anisaldehyde or potassium
permanganate stains. Melting points were determined on a Buchi®
530 hot stage apparatus and are uncorrected. 1H and 13C NMR spectra
(200 MHz and 50 MHz, respectively) were recorded on a Varian® Mer-
cury spectrometer, and are internally referenced to residual solvent
signals. Data for 1H NMR are reported as follows: chemical shift (δ),
multiplicity (s = singlet, d = doublet, t = triplet, q = quartet, m = multi-
plet, br s = broad singlet), coupling constant, integration and assign-
ment. Data for 13C NMR are reported in terms of chemical shift (δ).
Mass spectra (ESI) were recorded on a Finnigan® Surveyor MSQ LC–
MS spectrometer. HRMS spectra were recorded on a Bruker QTOF
Maxis Impact spectrometer. Mass spectra and the conversions of the
reactions were recorded on a Shimadzu® GCMS-QP2010 Plus gas
(But-3-en-1-ylsulfinyl)benzene (2d)22
The reaction mixture was stirred for 1 h.
Colorless oil; yield: 113 mg (63%).
1H NMR (200 MHz, CDCl3): δ = 7.71–7.56 (m, 2 H, ArH), 7.54–7.43 (m,
3 H, ArH), 5.91–5.65 (m, 1 H, =CH), 5.13–5.03 (m, 2 H, =CH2), 2.87 (t,
J = 7.7 Hz, 2 H, CH2), 2.62–2.42 (m, 1 H, CHH), 2.40–2.23 (m, 1 H, CHH).
13C NMR (50 MHz, CDCl3): δ = 143.2, 134.8, 131.1, 129.2, 124.0, 117.1,
56.0, 26.2.
MS (ESI): m/z (%) = 181 (100) [M + H]+.
(Cyclohexylsulfinyl)benzene (2e)27
The reaction mixture was stirred for 1 h.
chromatograph–mass spectrometer utilizing
(MEGA-5, F.T.: 0.25 μm, I.D.: 0.25 mm, length: 30 m, Tmax: 350 °C, Col-
umn ID# 11475).
a
MEGA® column
Pale yellow solid; yield: 104 mg (50%); mp 64–65 °C.
1H NMR (200 MHz, CDCl3): δ = 7.64–7.40 (m, 5 H, ArH), 2.66–2.45 (m,
1 H, CH), 1.94–1.70 (m, 4 H, 4 × CHH), 1.66–1.56 (m, 1 H, CHH), 1.51–
1.08 (m, 5 H, 5 × CHH).
13C NMR (50 MHz, CDCl3): δ = 141.8, 130.9, 128.9, 125.0, 63.1, 26.2,
25.6, 25.4, 25.3, 24.0.
Organocatalytic Oxidation of Sulfides to Sulfoxides; General Pro-
cedure
Sulfide (1.00 mmol) was placed in a round-bottom flask, followed by
t-BuOH (0.5 mL), 2,2,2-trifluoroacetophenone (17.4 mg, 0.10 mmol),
aq buffer solution (0.5 mL, 0.6 M K2CO3/4 × 10–4 M EDTA disodium
salt) and 30% aq H2O2 (0.18 mL, 1.50 mmol). The reaction mixture
was stirred for 1–18 h. The crude residue was purified using flash col-
umn chromatography (40–60% EtOAc in PE) to afford the desired
product.
MS (ESI): m/z (%) = 209 (100) [M + H]+.
Ethyl 3-(Phenylsulfinyl)propanoate (2f)28
The reaction mixture was stirred for 5 h.
Colorless oil; yield: 145 mg (64%).
1H NMR (200 MHz, CDCl3): δ = 7.64–7.47 (m, 2 H, ArH), 7.47–7.34 (m,
3 H, ArH), 4.02 (q, J = 7.1 Hz, 2 H, OCH2), 3.24–3.02 (m, 1 H, CHH),
3.01–2.58 (m, 2 H, 2 × CHH), 2.56–2.34 (m, 1 H, CHH), 1.14 (t, J = 7.1
Hz, 3 H, CH3).
13C NMR (50 MHz, CDCl3): δ = 171.0, 142.2, 131.0, 129.1, 123.8, 60.9,
50.8, 25.9, 13.9.
MS (ESI): m/z (%) = 227 (100) [M + H]+.
(Methylsulfinyl)benzene (2a)24
The reaction mixture was stirred for 1 h.
Colorless oil; yield: 115 mg (82%).
1H NMR (200 MHz, CDCl3): δ = 7.61–7.51 (m, 2 H, ArH), 7.45–7.35 (m,
3 H, ArH), 2.63 (s, 3 H, CH3).
13C NMR (50 MHz, CDCl3): δ = 145.1, 130.8, 129.1, 123.2, 43.5.
MS (ESI): m/z (%) = 141 (100) [M + H]+.
HRMS (ESI): m/z [M + H]+ calcd for C7H9OS: 141.0369; found:
1-Methoxy-2-(methylsulfinyl)benzene (2g)29
The reaction mixture was stirred for 18 h.
141.0374.
Pale yellow solid; yield: 155 mg (91%); mp 75–79 °C.
1H NMR (200 MHz, CDCl3): δ = 7.69 (dd, J = 7.5, 1.7 Hz, 1 H, ArH),
7.37–7.25 (m, 1 H, ArH), 7.05 (t, J = 7.5 Hz, 1 H, ArH), 6.81 (d, J = 8.2
Hz, 1 H, ArH), 3.76 (s, 3 H, OCH3), 2.65 (s, 3 H, SCH3).
(Εthylsulfinyl)benzene (2b)25
The reaction mixture was stirred for 3 h.
13C NMR (50 MHz, CDCl3): δ = 154.4, 132.5, 131.7, 124.1, 121.2, 110.3,
55.4, 40.8.
MS (ESI): m/z (%) = 171 (100) [M + H]+.
Colorless oil; yield: 92 mg (60%).
1H NMR (200 MHz, CDCl3): δ = 7.61–7.23 (m, 5 H, ArH), 2.95–2.60 (m,
2 H, CH2), 1.13 (t, J = 7.4 Hz, 3 H, CH3).
13C NMR (50 MHz, CDCl3): δ = 142.9, 130.9, 129.1, 124.1, 50.1, 5.9.
MS (ESI): m/z (%) = 155 (100) [M + H]+.
Sulfinyldibenzene (2h)26
The reaction mixture was stirred for 18 h.
White solid; yield: 121 mg (60%); mp 70–72 °C.
1H NMR (200 MHz, CDCl3): δ = 7.46–7.09 (m, 10 H, ArH).
(Αllylsulfinyl)benzene (2c)26
The reaction mixture was stirred for 5 h.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–H

E
E. Voutyritsa et al.
Paper
Synthesis
13C NMR (50 MHz, CDCl3): δ = 144.9, 131.1, 129.3, 124.7.
MS (ESI): m/z (%) = 203 (100) [M + H]+.
13C NMR (50 MHz, CDCl3): δ = 48.3, 24.1, 18.6.
MS (ESI): m/z (%) = 119 (100) [M + H]+.
(Benzylsulfinyl)benzene (2i)26
Tetrahydrothiophene 1-Oxide (2p)25
The reaction mixture was stirred for 18 h.
Colorless oil; yield: 81 mg (78%).
The reaction mixture was stirred for 18 h.
White solid; yield: 175 mg (81%); mp 124–126 °C.
1H NMR (200 MHz, CDCl3): δ = 7.43–7.24 (m, 5 H, ArH), 7.23–7.05 (m,
3 H, ArH), 6.98–6.81 (m, 2 H, ArH), 4.02 (d, J = 12.5 Hz, 1 H, CHH), 3.93
(d, J = 12.5 Hz, 1 H, CHH).
13C NMR (50 MHz, CDCl3): δ = 142.4, 130.9, 130.1, 128.8, 128.6, 128.1,
127.9, 124.1, 63.1.
1H NMR (200 MHz, CDCl3): δ = 2.96 (t, J = 7.5 Hz, 4 H, 2 × CHH), 2.19–
2.11 (m, 4 H, 4 × CHH).
13C NMR (50 MHz, CDCl3): δ = 51.0, 22.6.
MS (ESI): m/z (%) = 105 (100) [M + H]+.
MS (ESI): m/z (%) = 217 (100) [M + H]+.
Organocatalytic Oxidation of Sulfides to Sulfones; General Proce-
dure
(Phenethylsulfinyl)benzene (2j)30
The reaction mixture was stirred for 2 h.
Colorless oil; yield: 198 mg (86%).
1H NMR (200 MHz, CDCl3): δ = 7.65–7.51 (m, 2 H, ArH), 7.49–7.31 (m,
3 H, ArH), 7.27–6.98 (m, 5 H, ArH), 3.15–2.73 (m, 4 H, 2 × CH2).
Sulfide (1.00 mmol) was placed in a round-bottom flask, followed by
t-BuOH (0.5 mL), 2,2,2-trifluoroacetophenone (34.8 mg, 0.20 mmol),
aq buffer solution (0.5 mL, 0.6 M K2CO3/4 × 10–4 M EDTA disodium
salt), MeCN (0.15 mL, 3.00 mmol) and 30% aq H2O2 (0.36 mL, 3.00
mmol). The reaction mixture was stirred for 1–5 h. The reaction was
quenched with 1 M HCl (5 mL) and extracted with CHCl3 (3 × 10 mL).
The combined organic layers were dried over Na2SO4, filtered and
concentrated in vacuo to afford the desired product.
13C NMR (50 MHz, CDCl3): δ = 143.1, 138.3, 130.6, 128.8, 128.3, 128.1,
126.3, 123.5, 57.7, 27.7.
MS (ESI): m/z (%) = 231 (100) [M + H]+.
(Methylsulfonyl)benzene (3a)33
[(Methylsulfinyl)methyl]benzene (2k)25
The reaction mixture was stirred for 18 h.
White solid; yield: 85 mg (55%); mp 55–57 °C.
The reaction mixture was stirred for 1 h.
White solid; yield: 156 mg (100%); mp 88–90 °C.
1H NMR (200 MHz, CDCl3): δ = 8.02–7.76 (m, 2 H, ArH), 7.71–7.44 (m,
1H NMR (200 MHz, CDCl3): δ = 7.42–7.36 (m, 5 H, ArH), 4.23 (s, 2 H,
3 H, ArH), 3.02 (s, 3 H, CH3).
13C NMR (50 MHz, CDCl3): δ = 140.3, 133.6, 129.3, 127.2, 44.3.
MS (ESI): m/z (%) = 157 (100) [M + H]+.
HRMS (ESI): m/z [M + H]+ calcd for C7H9O2S: 157.0318; found:
CH2), 2.73 (s, 3 H, CH3).
13C NMR (50 MHz, CDCl3): δ = 133.4, 130.4, 129.0, 128.1, 61.0, 38.9.
MS (ESI): m/z (%) = 155 (100) [M + H]+.
157.0321.
[Sulfinylbis(methylene)]dibenzene (2m)26
The reaction mixture was stirred for 18 h.
White solid; yield: 186 mg (81%); mp 133–135 °C.
(Ethylsulfonyl)benzene (3b)25
The reaction mixture was stirred for 1 h.
1H NMR (200 MHz, CDCl3): δ = 7.42–7.12 (m, 10 H, ArH), 3.89 (d, J =
13.0 Hz, 2 H, 2 × CHH), 3.79 (d, J = 13.0 Hz, 2 H, 2 × CHH).
13C NMR (50 MHz, CDCl3): δ = 129.9, 128.5, 127.9, 56.8.
MS (ESI): m/z (%) = 231 (100) [M + H]+.
Colorless oil; yield: 170 mg (100%).
1H NMR (200 MHz, CDCl3): δ = 7.91–7.77 (m, 2 H, ArH), 7.68–7.44 (m,
3 H, ArH), 3.08 (q, J = 7.4 Hz, 2 H, CH2), 1.22 (t, J = 7.4 Hz, 3 H, CH3).
13C NMR (50 MHz, CDCl3): δ = 138.1, 133.6, 129.1, 128.0, 50.4, 7.3.
MS (ESI): m/z (%) = 171 (100) [M + H]+.
HRMS (ESI): m/z [M + H]+ calcd for C14H15OS: 231.0838; found:
231.0846.
(Allylsulfonyl)benzene (3c)26
(Ethylsulfinyl)ethane (2n)31
The reaction mixture was stirred for 1 h.
The reaction mixture was stirred for 8 h.
Colorless oil; yield: 182 mg (100%).
1H NMR (200 MHz, CDCl3): δ = 7.86–7.71 (m, 2 H, ArH), 7.64–7.37 (m,
3 H, ArH), 5.86–5.50 (m, 1 H, =CH), 5.23 (d, J = 10.1 Hz, 1 H, =CHH),
5.06 (d, J = 18.3 Hz, 1 H, =CHH), 3.76–3.70 (m, 2 H, CH2).
13C NMR (50 MHz, CDCl3): δ = 137.9, 133.6, 128.8, 128.1, 124.5, 124.3,
60.5.
Colorless oil; yield: 84 mg (79%).
1H NMR (200 MHz, CDCl3): δ = 2.60 (q, J = 7.4 Hz, 4 H, 2 × CH2), 1.87 (t,
J = 7.4 Hz, 6 H, 2 × CH3).
13C NMR (50 MHz, CDCl3): δ = 44.5, 6.6.
MS (ESI): m/z (%) = 107 (100) [M + H]+.
MS (ESI): m/z (%) = 183 (100) [M + H]+.
Tetrahydro-2H-thiopyran 1-Oxide (2o)32
The reaction mixture was stirred for 1 h.
White solid; yield: 105 mg (89%); mp 60–62 °C.
(But-3-en-1-ylsulfonyl)benzene (3d)22
The reaction mixture was stirred for 1 h.
Colorless oil; yield: 98 mg (50%).
1H NMR (200 MHz, CDCl3): δ = 2.84–2.43 (m, 4 H, 2 × CH2), 2.20–1.87
(m, 2 H, CH2), 1.62–1.22 (m, 4 H, 2 × CH2).
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–H

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E. Voutyritsa et al.
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Synthesis
1H NMR (200 MHz, CDCl3): δ = 7.97–7.76 (m, 2 H, ArH), 7.70–7.40 (m,
3 H, ArH), 5.79–5.53 (m, 1 H, =CH), 5.12–4.81 (m, 2 H, =CH2), 3.30–
2.99 (m, 2 H, CH2), 2.50–2.24 (m, 2 H, CH2).
13C NMR (50 MHz, CDCl3): δ = 138.6, 137.1, 133.6, 129.1, 128.5, 128.0,
127.7, 126.6, 57.1, 28.4.
MS (ESI): m/z (%) = 247 (100) [M + H]+.
13C NMR (50 MHz, CDCl3): δ = 138.8, 133.8, 133.7, 129.3, 128.1, 117.1,
[(Methylsulfonyl)methyl]benzene (3k)25
The reaction mixture was stirred for 1 h.
White solid; yield: 148 mg (87%); mp 124–126 °C.
1H NMR (200 MHz, CDCl3): δ = 7.40–7.35 (m, 5 H, ArH), 4.22 (s, 2 H,
CH2), 2.72 (s, 3 H, CH3).
55.3, 26.8.
MS (ESI): m/z (%) = 197 (100) [M + H]+.
(Cyclohexylsulfonyl)benzene (3e)34
The reaction mixture was stirred for 1.5 h.
Yellow solid; yield: 220 mg (98%); mp 71–73 °C.
13C NMR (50 MHz, CDCl3): δ = 130.4, 128.9, 128.8, 128.1, 60.9, 38.8.
MS (ESI): m/z (%) = 171 (100) [M + H]+.
1H NMR (200 MHz, CDCl3): δ = 7.95–7.74 (m, 2 H, ArH), 7.71–7.39 (m,
3 H, ArH), 2.99–2.76 (m, 1 H, CH), 2.11–1.95 (m, 2 H, 2 × CHH), 2.93–
1.73 (m, 2 H, 2 × CHH), 1.71–1.54 (m, 1 H, CHH), 1.51–0.99 (m, 5 H,
5 × CHH).
13C NMR (50 MHz, CDCl3): δ = 137.0, 133.5, 128.92, 128.88, 63.3, 25.4,
25.0, 24.9.
2-(Benzylsulfonyl)ethan-1-ol (3l)37
The reaction mixture was stirred for 1 h.
Colorless oil; yield: 164 mg (82%).
1H NMR (200 MHz, CDCl3): δ = 7.51–7.32 (m, 5 H, ArH), 5.56 (br s, 1 H,
OH), 4.33 (s, 2 H, CH2), 4.00 (t, J = 6.2 Hz, 2 H, CH2), 3.07 (t, J = 6.2 Hz, 2
H, CH2).
13C NMR (50 MHz, CDCl3): δ = 130.9, 128.9, 128.8, 127.5, 60.8, 55.9,
53.1.
MS (ESI): m/z (%) = 201 (100) [M + H]+.
MS (ESI): m/z (%) = 225 (100) [M + H]+.
1-Methoxy-2-(methylsulfonyl)benzene (3g)21
The reaction mixture was stirred for 3 h.
White solid; yield: 140 mg (75%); mp 88–90 °C.
1H NMR (200 MHz, CDCl3): δ = 7.85 (dd, J = 8.0, 1.5 Hz, 1 H, ArH), 7.77
(dd, J = 8.0, 1.7 Hz, 1 H, ArH), 7.56 (m, 1 H, ArH), 7.36 (td, J = 7.8, 1.7
Hz, 1 H, ArH), 3.90 (s, 3 H, OCH3), 3.11 (s, 3 H, SCH3).
13C NMR (50 MHz, CDCl3): δ = 157.0, 135.5, 129.4, 128.0, 120.5, 112.5,
56.1, 42.7.
[Sulfonylbis(methylene)]dibenzene (3m)26
The reaction mixture was stirred for 1 h.
White solid; yield: 202 mg (82%); mp 151–153 °C.
1H NMR (200 MHz, CDCl3): δ = 7.46–7.03 (m, 10 H, ArH), 4.13 (s, 4 H,
2 × CH2).
MS (ESI): m/z (%) = 187 (100) [M + H]+.
13C NMR (50 MHz, CDCl3): δ = 130.7, 129.9, 128.7, 127.3, 57.7.
MS (ESI): m/z (%) = 247 (100) [M + H]+.
Sulfonyldibenzene (3h)35
The reaction mixture was stirred for 5 h.
White solid; yield: 174 mg (80%); mp 121–123 °C.
1H NMR (200 MHz, CDCl3): δ = 8.01–7.85 (m, 4 H, ArH), 7.64–7.32 (m,
6 H, ArH).
(Ethylsulfonyl)ethane (3n)38
The reaction mixture was stirred for 1 h.
White solid; yield: 122 mg (100%); mp 73–75 °C.
1H NMR (200 MHz, CDCl3): δ = 2.87 (q, J = 7.5 Hz, 4 H, 2 × CH2), 1.25 (t,
J = 7.5 Hz, 6 H, 2 × CH3).
13C NMR (50 MHz, CDCl3): δ = 45.6, 6.1.
MS (ESI): m/z (%) = 123 (100) [M + H]+.
13C NMR (50 MHz, CDCl3): δ = 141.3, 133.1, 130.8, 129.1, 129.0, 127.4,
126.9, 124.6.
MS (ESI): m/z (%) = 219 (100) [M + H]+.
(Benzylsulfonyl)benzene (3i)26
The reaction mixture was stirred for 1 h.
Τetrahydro-2H-thiopyran 1,1-Dioxide (3o)32
The reaction mixture was stirred for 1 h.
White solid; yield: 209 mg (90%); mp 146–148 °C.
1H NMR (200 MHz, CDCl3): δ = 7.65–7.44 (m, 3 H, ArH), 7.41–7.33 (m,
2 H, ArH), 7.26–7.10 (m, 3 H, ArH), 7.09–6.98 (m, 2 H, ArH), 4.27 (s, 2
H, CH2).
White solid; yield: 134 mg (100%); mp 101–103 °C.
1H NMR (200 MHz, CDCl3): δ = 2.99–2.77 (m, 4 H, 2 × CH2), 2.06–1.85
(m, 4 H, 2 × CH2), 1.63–1.42 (m, 2 H, CH2).
13C NMR (50 MHz, CDCl3): δ = 137.5, 133.6, 130.6, 130.1, 128.6, 128.3,
124.1, 62.5.
MS (ESI): m/z (%) = 233 (100) [M + H]+.
13C NMR (50 MHz, CDCl3): δ = 51.8, 24.0, 23.4.
MS (ESI): m/z (%) = 135 (100) [M + H]+.
HRMS (ESI): m/z [M + H]+ calcd for C5H11O2S: 135.0474; found:
135.0476.
(Phenethylsulfonyl)benzene (3j)36
The reaction mixture was stirred for 1.5 h.
Colorless oil; yield: 246 mg (100%).
1H NMR (200 MHz, CDCl3): δ = 8.02–7.81 (m, 2 H, ArH), 7.73–7.38 (m,
3 H, ArH), 7.32–6.99 (m, 5 H, ArH), 3.42–3.32 (m, 2 H, CH2), 3.12–2.90
(m, 2 H, CH2).
Tetrahydrothiophene 1,1-Dioxide (3p)25
The reaction mixture was stirred for 3 h.
Colorless oil; yield: 110 mg (92%).
1H NMR (200 MHz, CDCl3): δ = 2.93 (t, J = 7.5 Hz, 4 H, 4 × CHH), 2.16–
2.09 (m, 4 H, 4 × CHH).
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–H

G
E. Voutyritsa et al.
Paper
Synthesis
13C NMR (50 MHz, CDCl3): δ = 50.9, 22.5.
MS (ESI): m/z (%) = 121 (100) [M + H]+.
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Acknowledgment
The authors gratefully acknowledge the Operational Program ‘Educa-
tion and Lifelong Learning’ for financial support through the NSRF
program ‘ΕΝΙΣΧΥΣΗ ΜΕΤΑΔΙΣΑΚΤΟΡΩΝ ΕΡΕΥΝΗΤΩΝ (PE 2431)’ co-
financed by the ESF and the Greek State.
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Supporting Information
Supporting information for this article is available online at
http://dx.doi.org/10.1055/s-0036-1588315.
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