An efficient electrochemical synthesis of β-keto sulfones from sulfinates and 1,3-dicarbonyl compounds

Article abstract of DOI:10.1016/j.tet.2015.06.063

An efficient electrochemical synthesis of β-keto sulfones from sulfinates and 1,3-dicarbonyl compounds has been developed. The present electrochemical route could afford the target products in high to excellent yields under mild conditions.

Full text of DOI:10.1016/j.tet.2015.06.063

Accepted Manuscript
An efficient electrochemical synthesis of β-keto sulfones from sulfinates and 1,3-
dicarbonyl compounds
Xiao-Jun Pan, Jian Gao, Gao-Qing Yuan
PII:
S0040-4020(15)00960-6
10.1016/j.tet.2015.06.063
TET 26899
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 7 May 2015
Revised Date: 13 June 2015
Accepted Date: 16 June 2015
Please cite this article as: Pan X-J, Gao J, Yuan G-Q, An efficient electrochemical synthesis of β-
keto sulfones from sulfinates and 1,3-dicarbonyl compounds, Tetrahedron (2015), doi: 10.1016/
j.tet.2015.06.063.
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An efficient electrochemical synthesis of β-keto sulfones
from sulfinates and 1,3-dicarbonyl compounds
Xiaojun Pan, Jian Gao and Gaoqing Yuan*

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Xiao-Jun Pan, Jian Gao and Gao-Qing Yuan*
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Tetrahedron
journal homepage: www.elsevier.com
An efficient electrochemical synthesis of β-keto sulfones from sulfinates and 1,3-
dicarbonyl compounds
Xiao-Jun Pan, Jian Gao and Gao-Qing Yuan*
School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China.
ARTICLE INFO
ABSTRACT
Article history:
Received
Received in revised form
Accepted
An efficient electrochemical synthesis of β-keto sulfones from sulfinates and 1,3-dicarbonyl
compounds has been developed. The present electrochemical route could afford the target
products in high to excellent yields under mild conditions.
2009 Elsevier Ltd. All rights reserved
.
Available online
Keywords:
Electrosynthesis
β-Keto sulfones
Sulfinates
1,3-Dicarbonyl compounds
1. Introduction
Corresponding author. E-mail: gqyuan@scut.edu.cn (G. Yuan)
synthesis of β-keto sulfones from sulfinates and 1,3-dicarbonyl
compounds by using ammonium iodide as the supporting
electrolyte.
Sulfones are a core functional group in both organic and
medicinal chemistry.1 Among their derivatives, β-keto sulfones
are important motifs in pharmaceuticals synthesis.2-4 For
instance, some β-keto sulfones have been confirmed as new
antagonists of bacterial quorum sensing in Vibrio harveyi (Fig.
1a),2 and β-keto sulfones derivatives are found as potent
inhibitors of several enzymes, such as LpxC and MMP (Fig. 1b
and c).3 In addition, β-keto sulfones as synthetic intermediates
could achieve particular transformations.4 The routine synthesis
of β-keto sulfones is based on acylation of alkyl sulfones.5 Other
attractive approaches include alkylation of metallic arene
sulfinates,6 oxidation of β-oxo-sulfides,7 and the Roskamp
reaction.8 From the viewpoint of synthetic methodology, it is
still needed to develop a new route for the synthesis of β-keto
sulfones.
2. Result and Discussion
2.1. Influence of supporting electrolytes
In our initial study, the reaction of ethyl acetoacetate (1a) with
sodium p-tolylsulfinate (2a) was selected as a model reaction.
According to our previous experience, we would examine three main
factors affecting on this reaction, such as supporting electrolytes,
solvents and electrode materials. It was found that different
supporting electrolytes were involved in this transformation
leading to different results, as shown in Table 1. When NH4I was
used as the supporting electrolyte, the desired product could be
obtained in 95% yield (Table 1, entry 1). However, no
corresponding product could be obtained at all with a similar
ammonium salt NH4Br or NH4Cl as the supporting electrolyte
(Table 1, entries 2 and 3). Moreover, the efficiency of this
transformation slightly decreased if the supporting electrolyte
NH4I was replaced by n-Bu4NI (Table 1, entry 4). Similar results
were obtained when employing alkali metal iodide salts as the
supporting electrolyte instead of NH4I (Table 1, entries 5–6 and
Fig. 1 β-Keto sulfones as inhibitors
An electrochemical method has been widely applied in
organic synthesis because it could be used to develop
environmentally compatible processes.9 In recent years, iodine-
mediated10 or iodine-catalyzed11 reactions have attracted more
and more attention in organic synthesis. In our previous
investigations, we found that the in situ generated I2 by an
electrochemical method could promote some transformations
effectively.12 Based on our interest in organic electrosynthesis,
herein we report an efficient and convenient electrochemical
8
–9). Strangely, only 24% yield of the corresponding product
was obtained when KI was employed as the supporting
electrolyte (Table 1, entry 7). This is mainly due to the formation
of side-product 1-tosylpropan-2-one. In addition, it should be
noted the raw materials could not be converted into the
corresponding product successfully under the same reaction
conditions with NH4OAc as the supporting electrolyte (Table 1,
entry 10). This means that iodide salts are necessary for this

Tetrahedron
transformation.
Table 1
Table 3
ACCEPTED MANUSCRIPT
Influence of cathode materials on the electrosynthesis of β-
keto sulfones a
Influence of supporting electrolytes on the electrosynthesis of
β-keto sulfones a
Entry
Anode-Cathode
C—Ni
Supporting
electrolyte
Solvent
Yield (%) b
Entry
Anode-Cathode
Supporting
electrolyte
Solvent
Yield (%) b
1
NH4I
NH4I
NH4I
NH4I
DMSO
DMSO
DMSO
DMSO
95
93
90
91
1
2
3
4
5
6
7
8
9
C—Ni
C—Ni
C—Ni
C—Ni
C—Ni
C—Ni
C—Ni
C—Ni
C—Ni
C—Ni
NH4I
NH4Br
NH4Cl
n-Bu4NI
LiI
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
95
0
2
3
4
C—Cu
C—Al
C—Ag
0
a Electrolytic conditions as shown in Table 1. b Isolated yield based on 1a.
81
90
88
24
75
70
0
According to the experimental results (Table 1–3), the
optimized conditions for this reaction was summarized as follows:
1a (1 mmol), 2a (1.2 mmol), supporting electrolyte NH4I (4
mmol), solvent DMSO (8 mL), Ni cathode and graphite anode,
electrolysis with current 50 mA for 2 h and then continuously
stirring for 5 h at room temperature.
NaI
KI
RbI
CsI
10
a
NH4OAc
2.4. Electrosynthesis of β-keto sulfones from sulfinates and
1,3-dicarbonyl compounds
Electrolytic conditions: 1a (1 mmol), 2a (1.2 mmol), solvent (8 mL),
supporting electrolyte (0.5 mol L–1), undivided cell, electrolysis with constant
current 50 mA for 2 h and then continuously stirring for 5 h at rt. b Isolated
yield based on 1a.
Table 4
Reaction of β-diketones 1 with sodium p-tolylsulfinate 2aa
O
O
O
electrolysis
O
O
S
2.2. Influence of solvents
R1
S
O
ONa
R1
R2
R2
Electrolytic medium (solvent) was an important factor as well.
Compared to other solvents, DMSO was the most suitable
solvent for this transformation (Table 2, entry 1). In the N,N-
dimethylacetamide (DMA) or formamide and H2O solvents, the
corresponding products were obtained in 75%, 87% and 70%
yield, respectively (Table 2, entries 3–5). When N,N-
dimethylformamide (DMF) was employed as the electrolytic
medium, only a trace amount of the desired product was detected
(Table 2, entry 2). In the DMF solvent, side-product sulfonamide
was formed so that the yield of the desired product was greatly
decreased.
2a
3
1
O
O
O
O
O
O
S
S
O
S
O
O
O
O
O
O
3ba, 85%
3ca, 94%
3da, 90%
O
O
O
O
O
O
S
S
O
S
O
O
O
O
O
3ea, 89%
3fa, 93%
3ga, 93%
O
O
O
O
O
O
O
Table 2
S
S
S
N
N
O
N
Influence of solvents on the electrosynthesis of β-keto
O
O
H
H
sulfones a
3ia, 80%
3ha, 88%
3ja, 84%
Cl
O
O
S
O
O
O
S
O
O
O
N
S
O
N
H
H
3ka, 85%
3la, 88%
3ma, 90%
Entry
Anode-Cathode
Supporting
electrolyte
Solvent
Yield (%) b
O
O
S
O
O
1
2
3
4
5
C—Ni
C—Ni
C—Ni
C—Ni
C—Ni
NH4I
NH4I
NH4I
NH4I
NH4I
DMSO
DMF
95
3na, 86%
trace
75
DMA
a Electrolytic conditions as shown in Table 1. Isolated yield based on 1.
formamide 87
H2O
Under the optimized electrolytic conditions, the scope of 1,3-
dicarbonyl compounds was first examined and the results were
summarized in Table 4. With the methyl or tert-butyl 3-
oxobutanoate as a substrate instead of ethyl 3-oxobutanoate, the
desired products 3ba and 3ca were isolated in 85% and 94%
yield, respectively. Furthermore, 2-methoxyethyl or allyl 3-
oxobutanoate and ethyl 2-methyl-3-oxobutanoate were allowed
to react with sodium sulfinates smoothly exhibiting the
corresponding products in excellent yields (3da–3fa). 3-
acetyldihydrofuran-2(3H)-one also provided a good result (3ga).
In addition, 1,3-dicarbonyl compounds bearing amide groups
70
a Electrolytic conditions as shown in Table 1. b Isolated yield based on 1a.
2.3. Influence of cathode materials
From the experimental results listed in Table 3, the cathode
materials including Ni, Cu, Al and Ag were well appropriate for
this reaction, giving desired products in excellent yields (Table 3,
entries 1–4).

Tetrahedron
ACCEPTED MANUSCRIPT
3
could react with 2a effectively to afford the corresponding
sulfinate with ethyl acetoacetate (1a) could be smoothly
sulfonyl acetamides (3ha–3la). N-phenyl-2-tosylacetamide with
chloro, methyl and methoxyl (3ja–3la) on aryl rings gave higher
yields than that without substituents (3ia). Interestingly, 1,3-
butanedione bearing phenyl and furfuryl groups could be also
transformed into the desired products under the optimized
conditions (3ma, 3na).
converted to 3af (i.e., IC50 inhibitor as shown in Fig. 1) in 82%
yield under the standard conditions (Table 5, entry 5). This
means that the present electrochemical route has a potential
application.
2.5. Reaction mechanism
Table 5
To obtain a better understanding of the reaction mechanism,
several control experiments were carried out (Scheme 1). No
desired product 3ba was formed when methyl 2,2-dimethyl-3-
oxobutanoate was employed as the substrate (Eq. 1). The reaction
of ethyl 2-iodo-3-oxobutanoate with sodium p-tolylsulfinate (2a)
was performed to afford the product 3aa in yield 67% in the
presence of CH3COONH4 and DMSO (Eq. 2). However, when 1a
was used as a substrate instead of ethyl 2-iodo-3-oxobutanoate,
no product was obtained (Eq. 3). Therefore, we deduced that
ethyl 2-iodo-3-oxobutanoate may be an intermediate for this
transformation. When sodium p-tolylsulfinate (2a) was replaced
by freshly prepared 4-methylbenzene-1-sulfonyl iodide,12c the
raw materials could not be converted into the desired product,
which indicated that 4-methylbenzene-1-sulfonyl iodide was not
an intermediate for this reaction (Eq. 4). In addition, 30% yield of
the desired product was obtained even under non-electrochemical
conditions in the presence of iodine (Eq. 5). According to this
result, we infer that the in situ electrogenerated I2 plays an
important role in this transformation.
The scope of various sodium sulfinates a
O
O
O
O
O
electrolysis
Product
R
R S
ONa
S
Y
Y
O
Y=OCH2CH3, Ph
2
3
Entry
1
Yield (%)
Sodium sulfinate
O
S
ONa
O
O
S
90
O
O
3ab
F
O
O
O
O
O
O
O
2
3
81
85
88
F
S
S
ONa
O
O
3ac
Cl
O
S
ONa
Cl
S
O
O
3ad
Br
O
S
ONa
Br
4
5
6
S
O
O
3ae
O
S
O
O
O
82
92
ONa
S
O
O
3af
3ag
3ah
O
O
S
O
S
ONa
O
O
O
O
7
8
S
S
ONa
O
89
90
O
S
O
S
ONa
O
3ai
O
O
O
S
O
9
S
ONa
O
84
0
3aj
O
S
O
F3C
10
F3C S
ONa
O
Scheme 1. Control experiments
3ak
a Electrolytic conditions as shown in Table 1. Isolated yield based on 1,3-
dicarbonyl compounds.
Further, we examined various sodium sulfinates. As shown in
Table 5, benzene sulfinic acid sodium salt or its derivatives
reacted readily with ethyl 3-oxobutanoate, affording the desired
products in 81–90% yields (3ab–3af). When aliphatic or benzene
sulfinic acid sodium reacted with 1-phenylbutane-1,3-dione,
excellent yields of desired products were observed (3ag–3aj).
However, no corresponding product could be obtained when
trifluoromethane sulfinic acid sodium was subjected to the
reaction, indicating that strong electron-withdrawing groups had
a great impact on the transformation under the optimized
conditions. It is worth mentioning that sodium biphenyl-4-
Scheme 2. Proposed reaction mechanism

Tetrahedron
[M+Na]+, 251.0349; found 251.0345.
The reaction of sulfinates with α-chloro-β-dicarbonyl
compounds to synthesis of β-keto sulfones via C-C bond
ACCEPTED MANUSCRIPT
4.2.3.
tert-Butyl 2-tosylacetate (3ca)
cleavage has been reported by Kowal et al., who demonstrated
that the reaction proceeded via SN mechanism.13 In the present
case, the formation of β-keto sulfones may undergo the similar
reaction mechanism. On the basis of the above results and the
reported literatures, a possible mechanism is outlined in Scheme
2. Iodine ions are electro-oxidized to I2 at the inert graphite anode
(2I– → I2 + 2e–),14 followed by the reaction with 1,3-dicarbonyl
compounds to afford the intermediate product A.15 Then, the
reaction of A with sulfinate B gives β-keto sulfone C via SN
mechanism.13
1H NMR (400 MHz, CDCl3): δ 7.87 (d, J=8.4 Hz, 2H), 7.38 (d,
J=8 Hz, 2H), 5.39 (s, 2H), 2.48 (s, 3H), 1.39 (s, 9H) ppm. 13C
NMR (100 MHz, CDCl3): δ 162.8, 146.1, 131.8, 130.4, 129.6,
84.9, 36.0, 27.4, 21.8 ppm. HRMS (ESI) m/z: calcd for
C13H18NaO4S [M+Na]+, 293.0818; found 293.0811.
4.2.4.
2-Methoxyethyl 2-tosylacetate (3da)
1H NMR (400 MHz, CDCl3): δ 7.82 (d, J=6.4 Hz, 2H), 7.36 (d, J
= 6.4 Hz, 2H), 4.21 (d, J=4.4 Hz, 2H), 4.17 (s, 2H), 3.50 (d,
J=4.8 Hz, 2H), 3.35–3.29 (m, 3H), 2.45 (d, J=4.8 Hz, 3H) ppm.
13C NMR (100 MHz, CDCl3): δ 162.2, 145.1, 135.5, 129.5,
128.2, 69.4, 64.7, 60.5, 58.5, 21.3 ppm. HRMS (ESI) m/z: calcd
for C12H16NaO5S [M+Na]+, 295.0611; found 295.0618.
3. Conclusion
We have developed an efficient electrochemical synthesis of
β-keto sulfones from sulfinates and 1,3-dicarbonylcompounds,
which is promoted by the in situ electrogenerated I2. The present
work provides a new route for the synthesis of β-keto sulfones.
Further mechanistic studies on this transformation are currently
underway in our laboratory.
4.2.5.
Allyl 2-tosylacetate (3ea)
1H NMR (400 MHz, CDCl3): δ 7.81 (d, J=8.4 Hz, 2H), 7.36 (d,
J=8.0 Hz, 2H), 5.84–5.75 (m, 1H), 5.32–5.20 (m, 2H), 4.57 (dd, J
=4.4, 1.2 Hz, 2H), 4.14 (s, 2H), 2.44 (s, 3H) ppm. 13C NMR (100
MHz, CDCl3): δ 162.0, 145.2, 135.6, 130.7, 129.7, 128.3, 119.4,
66.5, 60.8, 21.5 ppm. HRMS (ESI) m/z: calcd for C12H14NaO4S
[M+Na]+, 277.0505; found 277.0514.
4. Experimental section
4.1. Instrumentation
1H and 13C NMR spectra were recorded on a Brüker Advance
400 spectrometer (1H: 400 MHz, 13C: 100 MHz). The chemical
shifts were referenced to signals at 7.26 and 77.0 ppm,
respectively. The following abbreviations were used to explain
the multiplicities: s = singlet, d = doublet, t = triplet, q = quartet,
m = multiplet. Mass spectra were recorded on a Shimadzu
GCMS-QP5050A spectrometer at an ionization voltage of 70 eV
equipped with a DB-WAX capillary column (internal diameter:
0.25 mm, length: 30 m). GC-MS was obtained using electron
ionization. HRMS analysis was performed in a MAT95XP high
resolution mass spectrometer.
4.2.6.
Ethyl 2-tosylpropanoate (3fa)
1H NMR (400 MHz, CDCl3): δ 7.87 (d, J=6.4 Hz, 2H), 7.35 (d,
J=7.6 Hz, 2H), 4.25–4.21 (m, 3H), 2.47 (s, 3H), 2.39 (t, J=1.6 Hz,
3H), 1.30–1.25 (m, 3H) ppm. 13C NMR (100 MHz, CDCl3): δ
166.5, 145.9, 131.6, 130.5, 129.2, 63.5, 51.7, 27.5, 21.7, 13.5
ppm. HRMS (ESI) m/z: calcd for C12H16NaO4S [M+Na]+,
279.0662; found 279.0670.
4.2.7.
3-Tosyldihydrofuran-2(3H)-one (3ga)
1H NMR (400 MHz, CDCl3): δ 7.79 (d, J=8.4 Hz, 2H), 7.37 (d,
J=8.0 Hz, 2H), 4.39–4.29 (m, 2H), 4.16 (q, J=5.1 Hz, 1H), 2.88–
2.63 (m, 2H), 2.44 (s, 3H) ppm. 13C NMR (100 MHz, CDCl3): δ
168.3, 145.7, 133.4, 129.7, 128.9, 66.8, 63.1, 23.8, 21.4 ppm.
HRMS (ESI) m/z: calcd for C11H12NaO4S [M+Na]+, 263.0349;
found 263.0358.
4.2. A typical procedure for the electrosynthesis of β-keto
sulfones
In a typical experiment, 1,3-dicarbonyl compounds (1 mmol),
sodium sulfinates (1.2 mmol), DMSO (8 mL) and NH4I (4 mmol)
were added to the undivided cell. The electrosynthesis was
carried out in the undivided cell fitted with a Ni sheet cathode (2
cm × 2.5 cm × 0.02 cm) and a graphite rod anode at a constant
current (50 mA) at room temperature under magnetic stirring for
2 h and then continuously stirring for 5 h. After the reaction was
finished, the electrolyte solution was decolorized with Na2S2O3,
and then washed with distilled water (50 mL) and extracted with
ethyl acetate (10 mL × 3). The solvent was removed under
reduced pressure, and the crude product was purified by column
chromatography on silica gel using petroleum ether-ethyl acetate
(5:1) as eluent.
4.2.8.
N,N-Diethyl-2-tosylacetamide (3ha)
1H NMR (400 MHz, CDCl3): δ 7.90 (d, J=8.0 Hz, 2H), 7.36 (d,
J=8.4 Hz, 2H), 5.81 (s, 2H), 3.39–3.24 (m, 4H), 2.46 (s, 3H),
1.23 (t, J=7.2 Hz, 3H), 1.06 (t, J=6.8 Hz, 3H) ppm. 13C NMR
(100 MHz, CDCl3): δ 62.5, 145.9, 131.9, 131.4, 129.1, 43.5,
42.0, 33.7, 21.8, 14.3, 12.2 ppm. HRMS (ESI) m/z: calcd for
C13H19NNaO3S [M+Na]+, 292.0978; found 292.0984.
4.2.9.
N-Phenyl-2-tosylacetamide (3ia)
1H NMR (400 MHz, CDCl3): δ 8.55 (s, 1H), 7.80 (d, J=8.4 Hz,
2H), 7.49 (d, J=7.6 Hz, 2H), 7.38–7.30 (m, 4H), 7.16 (t, J=7.6
Hz, 1H), 4.15 (s, 2H), 2.44 (s, 3H) ppm. 13C NMR (100 MHz,
CDCl3): δ 158.8, 145.8, 137.1, 135.0, 130.1, 129.0, 128.1, 125.1,
120.2, 63.1, 21.6 ppm. HRMS (ESI) m/z: calcd for
C15H15NNaO3S [M+Na]+, 312.0665; found 312.0674.
4.2.1.
Ethyl 2-tosylacetate (3aa)
1H NMR (400 MHz, CDCl3): δ 7.82 (d, J=8.4 Hz, 2H), 7.37 (d,
J=8.0 Hz, 2H), 4.15 (q, J=7.2 Hz, 2H), 4.09 (s, 2H), 2.46 (s, 3H),
1.20 (t, J=7.2 Hz, 3H) ppm. 13C NMR (100 MHz, CDCl3): δ
162.4, 145.4, 135.8, 129.8, 128.5, 62.3, 61.1, 21.6, 13.8 ppm.
HRMS (ESI) m/z: calcd for C11H14NaO4S [M+Na]+, 265.0505;
found 265.0516.
4.2.10. N-(4-Methoxyphenyl)-2-tosylacetamide (3ja)
1H NMR (400 MHz, CDCl3): δ 8.54 (s, 1H), 7.79 (d, J=8.0 Hz,
2H), 7.39–7.32 (m, 4H), 6.83 (d, J=8.8 Hz, 2H), 4.15 (s, 2H),
3.78 (s, 3H), 2.43 (s, 3H) ppm. 13C NMR (100 MHz, CDCl3): δ
158.6, 156.9, 145.7, 135.1, 130.1, 128.2, 126.4, 122.0, 114.2,
62.9, 55.4, 21.7 ppm. HRMS (ESI) m/z: calcd for C16H17NNaO4S
[M+Na]+, 342.0770; found 342.0780.
4.2.2.
Methyl 2-tosylacetate (3ba)
1H NMR (400 MHz, CDCl3): δ 7.82 (d, J=8.0 Hz, 2H), 7.38 (d,
J=8.0 Hz, 2H), 4.13 (s, 2H), 3.71 (s, 3H), 2.46 (s, 3H) ppm. 13C
NMR (100 MHz, CDCl3): δ 162.9, 145.4, 135.6, 129.8, 128.4,
60.8, 53.0, 21.6 ppm. HRMS (ESI) m/z: calcd for C10H12NaO4S
4.2.11. N-(4-Chlorophenyl)-2-tosylacetamide (3ka)

Tetrahedron
ACCEPTED MANUSCRIPT
5
1H NMR (400 MHz, CDCl3): δ 8.71 (s, 1H), 7.78 (d, J=8.4 Hz,
1H NMR (400 MHz, CDCl3): δ 8.01 (d, J=7.8 Hz, 2H), 7.78 (d,
2H), 7.44 (d, J=8.8 Hz, 2H), 7.36 (d, J=8.0 Hz, 2H), 7.30–7.22
(m, 2H), 4.18 (s, 2H), 2.44 (s, 3H) ppm. 13C NMR (100 MHz,
CDCl3): δ 158.8, 146.0, 135.6, 134.8, 130.2, 129.7, 129.1, 128.1,
121.4, 63.0, 21.7 ppm. HRMS (ESI) m/z: calcd for
C15H14ClNNaO3S [M+Na]+, 346.0275; found 346.0283.
J=7.8 Hz, 2H), 7.62 (d, J=7.4 Hz, 2H), 7.51–7.42 (m, 3H), 4.20–
4.15 (m, 4H), 1.21 (t, J=7.0 Hz, 3H). 13C NMR (100 MHz,
CDCl3): δ 162.4, 147.2, 139.0, 137.2, 129.1, 128.8, 127.8, 127.4,
62.4, 61.1, 13.8.
4.2.20. 2-(Methylsulfonyl)-1-phenylethanone (3ag)
1H NMR (400 MHz, CDCl3): δ 8.00 (d, J=7.2 Hz, 2H), 7.66 (t,
J=7.4 Hz, 1H), 7.53 (t, J=7.8 Hz, 2H), 4.61 (s, 2H), 3.15 (s, 3H)
ppm. 13C NMR (100 MHz, CDCl3): δ 189.2, 135.6, 134.7, 129.2,
129.0, 61.2, 41.8 ppm. HRMS (ESI) m/z: calcd for C9H10NaO3S
[M+Na]+, 221.0243; found 221.0249.
4.2.12. N-(o-Tolyl)-2-tosylacetamide (3la)
1H NMR (400 MHz, CDCl3): δ 8.46 (s, 1H), 7.81 (d, J=8.0 Hz,
2H), 7.72 (t, J=6.8 Hz, 1H), 7.35 (d, J=7.6 Hz, 2H), 7.22–7.15
(m, 2H), 7.09 (t, J=7.2 Hz, 1H), 4.19 (s, 2H), 2.43 (s, 3H), 2.32
(d, J=2.8 Hz, 3H) ppm. 13C NMR (100 MHz, CDCl3): δ 158.8,
145.8, 135.1, 135.0, 130.6, 130.2, 128.0, 126.6, 125.7, 122.8,
122.7, 62.5, 21.6, 17.7 ppm. HRMS (ESI) m/z: calcd for
C16H17NNaO3S [M+Na]+, 326.0821; found 326.0830.
4.2.21. 2-(Ethylsulfonyl)-1-phenylethanone (3ah)
1H NMR (400 MHz, CDCl3): δ 8.00 (d, J=7.6 Hz, 2H), 7.64 (t,
J=7.2 Hz, 1H), 7.51 (t, J=7.6 Hz, 2H), 4.57 (s, 2H), 3.27 (q,
J=7.2 Hz, 2H), 1.44 (t, J=7.2 Hz, 3H) ppm. 13C NMR (100 MHz,
CDCl3): δ 189.2, 135.7, 134.6, 129.2, 128.9, 58.7, 48.2, 6.5 ppm.
HRMS (ESI) m/z: calcd for C10H12NaO3S [M+Na]+, 235.0399;
found 235.0404.
4.2.13. 1-Phenyl-2-tosylethanone (3ma)
1H NMR (400 MHz, CDCl3): δ 7.95 (d, J=7.2 Hz, 2H), 7.76 (d,
J=8.0 Hz, 2H), 7.62 (t, J=7.2 Hz, 1H), 7.48 (t, J=8.0 Hz, 2H),
7.33 (d, J=8.0 Hz, 2H), 4.72 (s, 2H), 2.44 (s, 3H) ppm. 13C NMR
(100 MHz, CDCl3): δ 188.1, 145.3, 135.8, 134.3, 129.8, 129.3,
128.8, 128.6, 127.4, 63.6, 21.7 ppm. HRMS (ESI) m/z: calcd for
C15H14NaO3S [M+Na]+, 297.0556; found 297.0560.
4.2.22. 2-(Cyclopropylsulfonyl)-1-phenylethanone (3ai)
1H NMR (400 MHz, CDCl3): δ 8.05 (dd, J=8.4, 1.2 Hz, 2H), 7.68
(t, J=7.4 Hz, 1H), 7.54 (t, J=7.8 Hz, 2H), 4.67 (s, 2H), 2.81–2.75
(m, 1H), 1.31–1.28 (m, 2H), 1.14–1.09 (m, 2H) ppm. 13C NMR
(100 MHz, CDCl3): δ 188.9, 135.8, 134.5, 129.3, 129.0, 61.0,
30.8, 5.5 ppm. HRMS (ESI) m/z: calcd for C11H12NaO3S
[M+Na]+, 247.0399; found 247.0406.
4.2.14. 1-(Furan-2-yl)-2-tosylethanone (3na)
1H NMR (400 MHz, CDCl3): δ 7.76 (d, J=8.0 Hz, 2H), 7.61 (s,
1H), 7.35–7.31 (m, 3H), 6.58 (s, 1H), 4.57 (s, 2H), 2.44 (s, 3H)
ppm. 13C NMR (100 MHz, CDCl3): δ 175.8, 151.8, 148.0, 145.3,
135.7, 129.8, 128.5, 120.4, 113.1, 63.6, 21.6 ppm. HRMS (ESI)
m/z: calcd for C13H12NaO4S [M+Na]+, 287.0349; found
287.0357.
4.2.23. 1-Phenyl-2-(phenylsulfonyl)ethanone (3aj)
1H NMR (400 MHz, CDCl3): δ 7.97–7.91 (m, 4H), 7.71–7.61(m ,
2H), 7.57 (t, J=7.6 Hz, 2H), 7.50 (t, J=7.4 Hz, 2H), 4.74 (s, 2H)
ppm. 13C NMR (100 MHz, CDCl3): δ 187.9, 138.7, 135.7, 134.4,
129.3, 129.2, 128.8, 128.6, 63.4 ppm. HRMS (ESI) m/z: calcd for
C14H12NaO3S [M+Na]+, 283.0399; found 283.0404.
4.2.15. Ethyl 2-(phenylsulfonyl)acetate (3ab)
1H NMR (400 MHz, CDCl3): δ 7.95 (d, J=7.6 Hz, 2H), 7.69 (t,
J=7.4 Hz, 1H), 7.58 (t, J=7.2 Hz, 2H), 4.16–4.09 (m, 4H), 1.18 (t,
J=7.2 Hz, 3H) ppm. 13C NMR (100 MHz, CDCl3): δ 162.2,
138.7, 134.2, 129.1, 128.4, 62.2, 60.9, 13.7 ppm. HRMS (ESI)
m/z: calcd for C10H12NaO4S [M+Na]+, 251.0349; found
251.0354.
Acknowledgments
We thank the National Natural Science Foundation of China
(21172079), and the Science and Technology Planning Project of
Guangdong Province (2011B090400031) for financial support.
4.2.16. Ethyl 2-((4-fluorophenyl)sulfonyl)acetate (3ac)
1H NMR (400 MHz, CDCl3): δ 8.04–7.95 (m, 2H), 7.27 (t, J=8.4
Hz, 2H), 4.19–4.12 (m, 4H), 1.21 (t, J=7.0 Hz, 3H) ppm. 13C
NMR (100 MHz, CDCl3): δ 167.3, 163.5 (d, JC-F = 250.0 Hz),
134.6, 134.6, 131.5, 131.4, 116.5, 116.3, 62.3, 60.8, 13.7 ppm.
HRMS (ESI) m/z: calcd for C10H11FNaO4S [M+Na]+, 269.0254;
found 269.0259.
References and notes
1. (a) Nielsen, M.; Jacobsen, C. B.; Holub, N.; Paixão, M. W.; Jørgensen,
K. A. Angew. Chem. Int. Ed. 2010, 49, 2668; (b) Meadows, D. C.;
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4.2.17. Ethyl 2-((4-chlorophenyl)sulfonyl)acetate (3ad)
1H NMR (400 MHz, CDCl3): δ 7.90 (d, J=8.8 Hz, 2H), 7.56 (d,
J=8.8 Hz, 2H), 4.16 (q, J=7.2 Hz, 2H), 4.12 (s, 2H), 1.22 (t,
J=7.2 Hz, 3H) ppm. 13C NMR (100 MHz, CDCl3): δ 162.2,
141.1, 137.1, 130.1, 129.5, 62.5, 60.9, 13.8 ppm. HRMS (ESI)
m/z: calcd for C10H11ClNaO4S [M+Na]+, 284.9959; found
284.9965.
3.
(a) Montgomery, J. I.; Brown, M. F.; Reilly, U.; Price, L. M.; Abramite,
J. A.; Arcari, J.; Barham, R.; Che, Y.; Chen, J. M.; Chung, S. W.;
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Harris, T. M.; Huband, M.; Knafels, J. D.; Leach, K. L.; Liu, S.; Marfat,
A.; McAllister, L.; McElroy, E.; Menard, C. A.; Mitton-Fry, M.;
Mullins, L.; Noe, M. C.; O’Donnell, J.; Oliver, R.; Penzien, J.; Plummer,
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V.; Grosu, G. T.; Davis, J. M.; Hu, B.; Ellingboe, J.; Baker, J. L.;
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L. M.; Walter, T.; Jin, G.; Cowling, R. J. Med. Chem. 2003, 46, 2361.
4.2.18. Ethyl 2-((4-bromophenyl)sulfonyl)acetateethyl (3ae)
1H NMR (400 MHz, CDCl3): δ 7.82 (d, J=8.0 Hz, 2H), 7.73 (d,
J=7.6 Hz, 2H), 4.16 (q, J=6.8 Hz, 2H), 4.11 (s, 2H), 1.22 (t,
J=7.2 Hz, 3H) ppm. 13C NMR (100 MHz, CDCl3): δ 162.2,
137.7, 132.5, 130.2, 129.8, 62.5, 60.9, 13.9 ppm. HRMS (ESI)
m/z: calcd for C10H11BrNaO4S [M+Na]+, 328.9454; found
328.9452.
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4.2.19. Ethyl 2-([1,1'-biphenyl]-4-ylsulfonyl)acetate (3af) 16

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Supporting Information
An efficient electrochemical synthesis of β-keto sulfones
from sulfinates and 1,3-dicarbonyl compounds
Xiao-Jun Pan, Jian Gao and Gao-Qing Yuan*
School of Chemistry and Chemical Engineering, South China University of Technology,
Guangzhou 510640, China
E-mail: gqyuan@scut.edu.cn
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NMR spectra
Fig. S-1. 1H-NMR spectrum of (3aa).
Fig. S-2. 13C-NMR spectrum of (3aa).
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Fig. S-3. 1H-NMR spectrum of (3ba).
Fig. S-4. 13C-NMR spectrum of (3ba).
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Fig. S-5. 1H-NMR spectrum of (3ca).
Fig. S-6. 13C-NMR spectrum of (3ca).
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Fig. S-7. 1H-NMR spectrum of (3da).
Fig. S-8. 13C-NMR spectrum of (3da).
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Fig. S-9. 1H-NMR spectrum of (3ea).
Fig. S-10. 13C-NMR spectrum of (3ea).
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Fig. S-11. 1H-NMR spectrum of (3fa).
Fig. S-12. 13C-NMR spectrum of (3fa).
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Fig. S-13. 1H-NMR spectrum of (3ga).
Fig. S-14. 13C-NMR spectrum of (3ga).
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Fig. S-15. 1H-NMR spectrum of (3ha).
Fig. S-16. 13C-NMR spectrum of (3ha).
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Fig. S-17. 1H-NMR spectrum of (3ia).
Fig. S-18. 13C-NMR spectrum of (3ia).
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Fig. S-19. 1H-NMR spectrum of (3ja).
Fig. S-20. 13C-NMR spectrum of (3ja).
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Fig. S-21. 1H-NMR spectrum of (3ka).
Fig. S-22. 13C-NMR spectrum of (3ka).
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Fig. S-23. 1H-NMR spectrum of (3la).
Fig. S-24. 13C-NMR spectrum of (3la).
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Fig. S-25. 1H-NMR spectrum of (3ma).
Fig. S-26. 13C-NMR spectrum of (3ma).
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Fig. S-27. 1H-NMR spectrum of (3na).
Fig. S-28. 13C-NMR spectrum of (3na).
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Fig. S-29. 1H-NMR spectrum of (3ab).
Fig. S-30. 13C-NMR spectrum of (3ab).
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Fig. S-31. 1H-NMR spectrum of (3ac).
Fig. S-32. 13C-NMR spectrum of (3ac).
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Fig. S-33. 1H-NMR spectrum of (3ad).
Fig. S-34. 13C-NMR spectrum of (3ad).
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Fig. S-35. 1H-NMR spectrum of (3ae).
Fig. S-36. 13C-NMR spectrum of (3ae).
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Fig. S-37. 1H-NMR spectrum of (3af).
Fig. S-38. 13C-NMR spectrum of (3af).
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Fig. S-39. 1H-NMR spectrum of (3ag).
Fig. S-40. 13C-NMR spectrum of (3ag).
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