Redox Active Sodium Iodide/Recyclable Heterogeneous Solid Acid: An Efficient Dual Catalytic System for Electrochemically Oxidative α-C?H Thiocyanation and Sulfenylation of Ketones

Article abstract of DOI:10.1002/adsc.201701401

An efficient electrochemically oxidative α-C?H thiocyanation and sulfenylation of ketones has been developed in a simple undivided cell under constant current condition.?The electrochemistry performs using NaI as the redox catalyst and heterogeneous solid salt Amberlyst-15(H) (A-15(H)) as proton catalyst?without the addition of external conductive salts. The protocol proved to be practical since the solid salt could be reused in up to five consecutive gram-scale runs without significant decrease in efficiency. Control experiments and cyclic voltammetry analysis disclose that the reaction proceeds likely via a cascade α-halogenation and subsequent thiocyanation or sulfenylation. (Figure presented.).

Full text of DOI:10.1002/adsc.201701401

Title: Redox active sodium iodide / recyclable heterogeneous solid
acid: An efficient dual catalytic system for electrochemically
oxidative α-C-H thiocyanation and sulfenylation of ketones
Authors: Sen Liang, Cheng-Chu Zeng, Hongyu Tian, baoguo sun,
xugang luo, and fazheng ren
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To be cited as: Adv. Synth. Catal. 10.1002/adsc.201701401
Link to VoR: http://dx.doi.org/10.1002/adsc.201701401

10.1002/adsc.201701401
Advanced Synthesis & Catalysis
FULL PAPER
DOI: 10.1002/adsc.201((will be filled in by the editorial staff))
Redox active sodium iodide / recyclable heterogeneous solid
acid: An efficient dual catalytic system for electrochemically
oxidative α-C-H thiocyanation and sulfenylation of ketones
Sen Liang,a,b Cheng-Chu Zeng,a,c,* Hong-Yu Tian,a Bao-Guo Sun,a,* Xu-Gang Luo,b
Fa-zheng Ren b
a
Beijing advanced innovation center for food nutrition and human health, School of Food and Chemical Engineering,
Beijing Technology and Business University, Beijing 100048, China
Beijing advanced innovation center for food nutrition and human health, College of Food Science & Nutritional
b
Engineering, China Agricultural University, Beijing 100083, China
College of Life Science & Bioengineering, Beijing University of Technology, Beijing 100124, China
c
Corresponding author: phone:010-67396211, fax number: 010-67396211, e-mail address: zengcc@bjut.edu.cn;
sunbg@btbu.edu.cn
Received: ((will be filled in by the editorial staff))
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201######.((Please
delete if not appropriate))
Abstract. An efficient electrochemically oxidative α-C-H Control experiments and cyclic voltammetry analysis
thiocyanation and sulfenylation of ketones has been disclose that the reaction proceeds likely via a cascade α-
developed in a simple undivided cell under constant current halogenation and subsequent thiocyanation or sulfenylation.
condition. The electrochemistry performs using NaI as the
redox catalyst and heterogeneous solid salt Amberlyst-
15(H)® (A-15(H)) as proton catalyst without the addition of
external conductive salts. The protocol proved to be practical
since the solid salt could be reused in up to five consecutive
gram-scale runs without significant decrease in efficiency.
Keywords: electrochemistry, redox chemistry, C-H
functionalization, C-S bond formation, indirect electrolysis,
halide ion as redox catalyst
atom economic characteristics as well as avoiding the
prefunctionlization of substrates. For example,
Introduction
Kumar and co-workers reported
a
direct α-
The efficient synthesis of sulfur-containing
compounds is significant in organic chemistry,
pharmaceutical industry and materials science.[1]
thiocyanation of carbonyl compounds with
ammonium thiocyanate using K2S2O8 as an oxidant in
the presence of catalytic amounts of copper (II)
Among various sulfur-containing organic compounds, sulfate (Scheme 1a).[5a] The oxidative cross
α-thiocyanato and sulfenyl ketones have been paid
much attention due to their widespread existing as
core structural scaffolds in various natural products
and pharmaceuticals.[2] In addition, as versatile
building blocks and pivotal intermediates, α-
thiocyanato and sulfenyl ketones have also been
employed in preparing sulfur-containing heterocycles
such as thiazoles,[3a-3b] in oxidative generation of
sulfoxides or sulfones,[3c-3d] in ring cleavage forming
1,2-diketones,[3e] in 1,2-carbonyl transposition,[3f] and
in preparation of α,β-unsaturated ketones via the
dehydrosulfenylation.[3g]
dehydrogenative coupling of ketones with
heteroaromatic thiols was also achieved in the
presence of aqueous HClO4 (Scheme 1b).[5b] Very
recently, a one-pot synthesis of α-sulfenyl ketones
has also been developed by Barman and co-workers
using I2 as the catalyst and DMSO as the oxidant in t-
BuOH/DMI(1,3-Dimethyl-2-imidazolidinone)
solvent (Scheme 1c).[5c] Although much progress has
been made in the oxidative cross coupling for the
formation of C-S bonds, there is still great challenge
due to the instability of most of sulfur reagents under
oxidative conditions.[6] In addition, most of these
methods suffer from certain limitations, including the
use of toxic transition metal catalysts and excess of
external oxidants, which deter the development of
green and sustainable chemistry (Scheme 1).[7]
Consequently, to develop more efficient, economical
and practical synthetic methods for synthesizing α-
Although the substitution reaction of a α-halo ketone
with a S-centered nucleophilic agent is typically used
for the preparation of α-thiocyanato and sulfenyl
[4]
ketones,
the oxidative cross coupling of ketones
with S-centered agents has recently emerged as a
dominant and popular strategy due to its step- and
1
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10.1002/adsc.201701401
Advanced Synthesis & Catalysis
thiocyanato and sulfenyl ketones remains
challenging task.
a
conditions. Based on our previous successful use of
the graphite working electrode in halide ion-induced
[8]
C-H bonds functionalization, we decided to use it
Scheme 1. Methods for the synthesis of α-thiocyanato and
sulfenyl ketones
rather than to explore other options. The initial
constant current electrolysis of a mixture of 1a and 2a
was carried out using NaI as a redox catalyst in
o
aqueous EtOH at 50 C and the desired product 3a
was not detected (entry 1, Table 1). Considering that
the keto-enol tautomerization of
a
carbonyl
compound can be catalyzed via either a base or an
acid, we initially tested the effects of bases on the
electrochemical reaction. However, our attempt failed
and no desired 3a was detected in the presence of
bases tested (entries 2-5). Then, we turned to examine
the role of acids. As shown in Table 1, the reaction
did work and gave the desired 3a in 20% and 30%
yields when H2SO4 and p-toluenesulfonic acid
(PTSA) were employed, respectively (entries 6-7).
Since usage of H2SO4 or PTSA results in tedious
workup and isolation process as well as producing
large amounts of waste, we envisioned that
heterogeneous solid acid (such as Amberlyst-15(H)®),
which is recyclable and easily to workup by simple
filter, might overcome these limitations. To our
delight, the desired product 3a was obtained in 44%
yields when Amberlyst-15(H)® was employed (entry
Electrochemistry provides an alternative method to
achieve the formation of a new chemical bond by
heterogeneous electron transfer between an electrode
and a substrate (direct electrolysis) or by using a
redox catalyst (indirect electrolysis).[8] In the context,
we have achieved electrochemical C-H bond
functionalization, leading to the formation of new C-
C, C-N, C-O and C-S bonds using simple halide ions
as redox catalysts.[9] Based on our experience, we
hypothesized that a constant current electrolysis
(CCE) of ketone in the presence of a halide ion might
initially form active α-halogenated ketone, which
o
8). Increasing temperature to 70 C improved the
yield of 3a to 60% (entry 9). Notably, chloride and
bromide are inefficient for the reaction; only trace 3a
was detected (entries 10-11).10
Subsequent solvent screening disclosed that
DMSO as a solvent benefited the electrochemically
oxidative thiocyanation of ketone since the desired
product 3a was obtained in lower yields when the
electrochemical reactions were performed in aqueous
MeCN or aqueous 1,2-dimethoxyethane (DME)
(entries 12-13), [11] whereas, it increased to 70% yield
in aqueous DMSO (entry 14). Owing to the tedious
workup process in using large amount of DMSO as
solvent, we decided to perform the reaction in a
mixed solution comprising EtOH (10 mL), DMSO (3
mL) and H2O (2 mL), and more than 75% yield of 3a
was afforded (entry 15). The addition of water is
necessary; it improves the solubility of NaSCN and
enhances the conductivity of the reaction system.
then
undergoes
substitution
reaction
with
nucleophilic sulfur agents to fulfill the desired α-
thiocyanato or sulfenyl ketones (Scheme 1).
Herein we reported an efficient electrochemical
protocol for the one-pot α-C-H thiocyanation and
sulfenylation of ketones employing redox active NaI /
heterogeneous solid acid Amberlyst-15(H)® dual
catalysts system in a simple undivided cell. In this
protocol, the solid acid plays two-fold roles: to
suppress the polymerization of sulfur-containing
agents and to promote the enolization of the carbonyl
group for an easier α-halogenation. This protocol
features step- and atom economy, avoiding pre-
functionalization of the starting ketone compounds
and tedious isolation of intermediates. Moreover, the
solid acid Amberlyst-15(H)® could be reused without
significant decrease in efficiency.
Table 1. Optimization of the reaction conditions a
Results and Discussion
At the outset, to demonstrate the feasibility of the
one-pot electrochemical α-thiocyanation of ketones
via the cascade α-halogenation and thiocyanation
sequence, we chose propiophenone (1a) and NaSCN
(2a) as model substrates to optimize the reaction
2
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10.1002/adsc.201701401
Advanced Synthesis & Catalysis
obtained in only 15% yields due to the steric
hindrance and most of the starting 1c was recovered.
Notably, the α-thiocyanation of 2-cyclopropyl-1-
phenylethanone, 1d, proceeded smoothly to afford
the corresponding 3d in 50% yield. This observation
implies that the electrochemical α-thiocyanation of
ketones may not involve a radical pathway (Detailed
discussion see mechanism discussion and Scheme 5).
It was observed the electrochemical α-thiocyanation
was more efficient when an electron-donating
substituent was appended on the benzene ring of
propiophenone. For example, the methyl- and
methoxyl substituted propiophenones afforded the
corresponding adducts 3e and 3g in 71% and 72%
yields, respectively, whereas, the corresponding 3h
and 3j was isolated in a slightly lower yield when
chloro- or fluoro- were installed in the phenyl ring.
Cyclic aromatic ketones were also amenable to the
reaction. For example, 3k was afforded in a 45%
yield.
Entry
1
J /mA·cm-2 T/ o
50
C
Redox catalyst
NaI
Additive
-
Solvent e
EtOH/H2O
Yield b
0
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
2
6
4
4
4
4
4
c
2
50
50
50
50
50
50
50
70
70
70
70
70
70
70
70
70
70
70
70
70
50
NaI
Na2CO3
EtOH/H2O
0
3
NaI
NaOHc
DBUc
2,6-lutidinec
EtOH/H2O
0
4
NaI
EtOH/H2O
0
5
NaI
EtOH/H2O
0
c
6
NaI
H2SO4
EtOH/H2O
15
30
44
60
Trace
6
7
NaI
PTSAc
EtOH/H2O
8
NaI
A-15(H)®
A-15(H)®
A-15(H)®
A-15(H)®
A-15(H)®
A-15(H)®
A-15(H)®
A-15(H)®
A-15(H)®
A-15(H)®
A-15(H)®
A-15(H)®
A-15(H)®
A-15(H)®
A-15(H)®
EtOH/H2O
9
NaI
EtOH/H2O
10
11
12
13
14
15
16
17
18
19
20
21d
22
NaCl
NaBr
NaI
EtOH/H2O
EtOH/H2O
MeCN/H2O
6
NaI
DME/ H2O
23
70
75
68
74
73
75
72
52
trace
NaI
DMSO/H2O
NaI
EtOH/DMSO/H2O
EtOH/DMSO/H2O
EtOH/DMSO/H2O
EtOH/DMSO/H2O
EtOH/DMSO/H2O
EtOH/DMSO/H2O
EtOH/DMSO/H2O
EtOH/DMSO/H2O
NaI
NaI
NH4I
Et4NI
Bu4NI
NaI
Owing to less prone to enolization, simple aliphatic
ketones are generally not suitable substrates for the
oxidative α-functionalization. To our delight, our
protocol could also be applied to aliphatic ketones,
although in a bit lower yield compared with that of
aromatic ketones. For example, when symmetric
aliphatic ketone, such as 1l, was subjected to reaction
with NaSCN under the standard electrochemical
conditions, the corresponding product 3l was isolated
in 35% yields. In the case of an unsymmetrical
-
a
Reaction conditions: propiophenone 1a (1 mmol),
NaSCN 2a in 15 mL of solvent, undivided cell, graphite
plate anode and cathode, CCE. b 1H NMR yields using
c
1,3,5-trimethoxybenzene as an internal standard. 5 equiv.
additives were used. d 0.2 equiv. NaI was added. EtOH
e
(13 mL) / H2O (2 mL); MeCN (13 mL) / H2O (13 mL);
DME (13 mL) / H2O (13 mL); DMSO (13 mL) / H2O (13
mL); EtOH (10 mL) / DMSO (3 mL) / H2O (2 mL)
aliphatic
ketone,
such
as
4-oxopentyl-4-
chlorobenzoate (1m), a mixture of regioisomers of
3m and 3m’ was obtained in 28% total yield and
most of 1m was recovered. 1,3-Dicarbonyl
compounds were also suitable substrates for the α-
The evaluation of current density indicated that
comparative yields of 3a was produced when a
density of 2 mA/cm2 (entry 16) and 6 mA/cm2 (entry
17) were employed instead of the optimal 4 mA/cm2.
Interestingly, almost same yields of 3a was isolated
when NH4I, Et4NI, n-Bu4NI was used as a mediator
(entries 18-20). In addition, lowering the amount of
NaI to 0.2 equiv resulted in a decrease of the yield of
3a to 52 % (entry 21). The reactions did not proceed
in the absence of NaI (entry 22). These observations
indicate that iodide ion plays the essential role.
thiocyanation reaction due to their easier keto-enol
[12]
tautomerism.
As expected, 3n and 3o were
afforded in good yields.
Table 2. Electrochemical oxidative α-thiocyanation of
different ketones a,b
From the results described above, we concluded
that the optimal reaction conditions call for the
constant current electrolysis at a current density of 4
mA/cm2 at 70 oC, using 0.5 equiv of NaI as the redox
catalyst in the presence of Amberlyst-15(H)®. The
reaction prefers proceeding in an undivided cell
equipped with graphite plate anode and cathode using
aqueous EtOH and DMSO solvent (entry 15).
With the optimized conditions in hand, we turned
to explore the scope and limitation of the α-
thiocyanation of ketones (Table 2). First, the
reactions of NaSCN with different aromatic and
aliphatic ketones were investigated. It was observed
that the α-thiocyanation of aromatic ketones
proceeded smoothly. For example, propiophenone
and acetophenone afforded the corresponding α-
thiocyanated products 3a and 3b in 70% and 60%
isolated yield under the standard conditions. The α-
thiocyanation of α-methyl propiophenone (1c) also
proceeded but the corresponding product 3c was
3
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10.1002/adsc.201701401
Advanced Synthesis & Catalysis
Gram scale experiments of the one-pot
electrochemical α-thiocyanation proved our protocol
to be practicable. For example, when 5 mmol of 1a
(0.671 g) was subjected to electrolysis with NaSCN
under the standard reaction conditions, the desired
product 3a was isolated in a 60% yield without
significant loss in reaction efficiency (Scheme 2).
Moreover, the recovered solid acid Amberlyst-15(H)®
could be reused after prior treatment with 0.1 N HCl
for 5 h. As shown in Scheme 2, the desired product
3a was afforded in the range of 55 to 60% yields
when the pre-activated solid acid was reused in five
successive gram-scale reactions, without significant
decrease of catalytic efficiency.
Scheme 2. Gram scale electrochemically oxidative α-C-H
thiocyanation of propiophenone (1a) and recyclability of
Amberlyst-15(H)®
a
Reaction conditions: ketones 1 (1 mmol), NaSCN 2a (3
mmol) and in EtOH 10 mL / DMSO 3 mL / H2O 2 mL of
solvent, undivided cell, graphite plate anode and cathode,
CCE.b Isolated yield
This protocol proved to be general and could also
be applied in α-sulfenylation of ketones. As shown in
Table 3, the reactions of propiophenone with various
aromatic thiols, such as 2-mercaptobenzoxazole, 2-
mercaptobenzothiazole,
methyltetrazole,
5-mercapto-1-
2-mercapto-5-methyl-1,3,4-
In order to better understand the reaction
mechanism, several control experiments were
conducted. As shown in Scheme 3, when
molecular iodine was employed as oxidant, the
desired product was obtained in a 55% yield
(Scheme 3a). Therefore, the in situ generated
molecular iodine (I2) is likely one of the active
species. Moreover, the reaction of separated
synthesized 2-iodo-1-phenylpropan-1-one, 5a,
with NaSCN afforded excellent yield of 3a
(Scheme 3b), which suggests that 5a is a possible
intermediate in this transformation and that a
nucleophilic substitution might be involved in
the reaction process.
thiadiazole, and 2-mercaptopyridine proceeded
smoothly to furnish the desired products 3p-3t in
moderate yields. For 2-mercapto-benzimidazole, 1u,
it failed to give the corresponding 3u. Moreover,
when p-toluenethiol was subjected to reaction with
propiophenone under the standard conditions, the
desired 3v was not afforded, instead, p-tolyl-p-
toluenesulfinate, 4, was isolated due to the over-
oxidation of homocoupling product of starting p-
toluenethiol. [5]
Table 3. Electrochemical oxidative sulfenylation of ketone
with different thiols a,b
Scheme 3. Control experiments
a Reaction conditions: propiophenone 1a (1 mmol), thiols 2
(3 mmol) in a mixed solvent of EtOH (10 mL) / DMSO (3
mL) / H2O (2 mL), undivided cell, graphite plate anode
and cathode, CCE. b isolated yield
It is worth noting that oxidative α-thiocyanation of
ketone may also proceed via a radical pathway. For
example, iodine radical from homolytic dissociation
of molecular iodine abstracts one of the α-H of
propiophenone, generating the carbon-centered
4
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10.1002/adsc.201701401
Advanced Synthesis & Catalysis
radical intermediate A. Followed by single electron
transfer (oxidation), carbonic cation B afforded.
Finally, the nucleophilic substitution of NaSCN to B
gives the desired α-sulfenyl products (Scheme 4).
Such a radical mechanism was previously proposed
in the cases of α-C−H amination [13] and α-nitrotion of
stoichiometric or catalytic amount of iodide ion is
required.
Scheme 6. A proposed reaction mechanism for the
electrochemical α-thiocyanation / sulfenylation of ketones
ketones [14]
.
Scheme 4. A possible radical pathway for the α-
thiocyanation of ketones
This proposed mechanism is consistent with cyclic
voltammetry analysis. As shown in Figure 1, CV of
NaI exhibits two typical oxidative waves at 0.62 V
and 0.86V vs Ag/AgCl (3M KCl) (curve b). When
1.0 equiv of propiophenone was added to the solution
of NaI, a dramatic increase of the oxidation peak
current was observed, along with a decrease of
reduction peak current (curve c). Since
propiophenone is not oxidized in the potential range
from 0.0 V to 1.4 V vs Ag/AgCl that was used (curve
d), the increase in the oxidative peak current is
attributed to a catalytic current, resulting from the
reaction of the in situ electrochemically generated I2
and propiophenone, affording α-iodopropiophenone 5
and regenerated iodine ion that leads to the
appearance of catalytic current and decrease of
reduction current (the conversion of 1 to 5 in Scheme
6). Although a slight increase of catalytic current was
observed in the presence of solid acid Amberlyst-
15(H)® (curve e), subsequent addition of NaSCN to
the system led to an additional increase of catalytic
current, simultaneously, the reduction peak
disappeared completely (curve f). This is due to the
nucleophilic substitution of 5 and SCN- under the
acidic medium, generating desired product 3 and
regenerating iodide ion (the conversion of 5 to 3 in
Scheme 6).
To clarify whether our electrochemical α-
thiocyanation of ketones involves the formation of
carbon-centered radical A, a radical clock experiment
was performed (Scheme 5). As mentioned in Table 2,
when substrate 1d was subjected to electrolysis in the
presence of 2a under the standard electrochemical
conditions, adduct 3d was obtained in a 50% yield,
whereas possible products, such as 5-iodo-1-phenyl-
2-penten-1-one, 1-phenylpenta-2,4-dienone or 5-
thiocyanato-1-phenyl- 2-penten-1-one, were not
detected from 1H NMR experiment, therefore we can
rule out the radical pathway in our electrochemical α-
thiocyanation of ketones.
Scheme 5. A radical clock experiment.
Based on these control experiments and radical
clock experiment, a possible reaction mechanism for
the electrochemical α-thiocyanation / sulfenylation of
ketones with NaSCN or heterocyclic thiols is
proposed. As illustrated in Scheme 6, the reaction
begins with the anodic oxidation of iodide ion to
generate molecular iodine, which undergoes reaction
with enol isomer of ketone 1 to form α-iodo ketone 5,
along with one molecule of HI. Once the key
intermediate 5 is formed, it soon undergoes a
nucleophilic substitution reaction with NaSCN or
heterocyclic thiols, leading to the final α-
thiocyanation
/
sulfenylation
product
3,
accompanying the generation of a second molecule of
HI. Simultaneously, the in situ generated HI is
reduced to evolve H2 on the surface of cathode. In the
course of the reaction, iodide ion is regenerated from
steps of the α-iodination of ketone 1, leading to 5 and
following nucleophilic substitution of 5 to 3, and re-
enters the redox catalyst cycle, thereby only sub-
Figure 1. Cyclic voltammogram NaI, propiophenone and
NaSCN in 0.1 M LiClO4 in a mixed solvent of EtOH (10
5
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10.1002/adsc.201701401
Advanced Synthesis & Catalysis
standard: TMS). Coupling constants are reported in Hz.
Cyclic voltammograms were obtained using Metrohm
Autolab. Starting materials and solvents were obtained
from commercial sources and used without further
purification. Products were purified by chromatography on
silica gel (Petroleum ether/EtOAc).
mL), DMSO (3 mL) and H2O (2 mL) using GC disk
working electrode, Pt wire and Ag/AgCl as counter and
reference electrode at 100 mV/s scan rate. a) background,
b) NaI (0.1 M), c) NaI (0.1 M) and 1a (0.1 M), d) 1a (0.1
M), e) NaI (0.1 M), 1a (0.1 M), Amberlyst-15(H)® (0.5 g),
f) NaI (0.1 M), 1a (0.1 M), Amberlyst-15(H)® (0.5 g) and
NaSCN (0.3 M).
General procedure for the electrochemical oxidation
sulfenylation of ketones
It is well known that an acid (Brønsted acid or
Lewis acid) can promote the keto-enol tautomization
of a ketone. In addition, it is well documented by
Becker and coworkers in their electrochemical
thiocyanation of alkenes and aromatics that
A 50 mL undivided cell was equipped with a graphite plate
cathode and a graphite plate anode (each about 2 × 3 cm2
and the inter electrode distance is about 0.5 cm) which
were connected to a DC regulated power supply. To the
cell was added ketone 1 (1 mmol), NaSCN 2 (3 mmol),
NaI (0.5 mmol), Amberlyst-15(H)® (1 g) and dissolved in
EtOH 10 mL + DMSO 3 mL + H2O 2 mL. The mixture
was electrolyzed under constant current conditions at 4
mA/cm2 at 70 oC while stirring. The electrolysis was
terminated when 15 F/mol of charge had been consumed.
After the electrolysis, the solvent was removed under
reduced pressure. The residue was poured into a saturated
aqueous Na2S2O3 and the product was then extracted with
EtOAc (3×10 mL), dried over MgSO4, and concentrated in
vacuum. The residue was purified by column
chromatography on silica gel using a mixture of petroleum
ether/EtOAc as eluent.
polymerization of thiocyanate or thiol is diminished
[15]
considerably in the presence of acid recourse.
In
our electrochemical α-thiocyanation / sulfenylation of
ketones, Amberlyst-15(H)® not only promotes the
enolization of the carbonyl group for the easier α-
halogenation, but also suppress the polymerization of
sulfur-containing reagents.
[16]
1-Phenyl-2-thiocyanatopropan-1-one (3a)
Yield: 134
Conclusion
mg, 70%; Brown oil; Flash chromatography (Petroleum
1
ether/EtOAc, 15 / 1). H NMR (300 MHz, CDCl3) δ 1.87
(d, J = 7.2 Hz, 3H), 5.09 (q, J = 7.2 Hz, 1H), 7.54 (t, J =
7.8 Hz, 2H), 7.67 (t, J = 7.2 Hz, 1H), 7.93 (d, J = 7.8 Hz,
2H); 13C NMR (75 MHz, CDCl3) δ 19.9, 50.0, 111.5, 128.8,
129.2, 133.1, 134.6, 194.8.
In conclusion, we have developed an efficient
electrochemical protocol for the α-thiocyanation /
sulfenation of ketones via the cascade oxidative α-C-
H
halogenation of ketones and subsequent
[15]
nucleophilic substitution with NaSCN or heterocyclic
thiols. The electrochemistry was performed under
constant current conditions in a simple undivided cell
equipped with simple graphite plate electrodes using
NaI as the redox catalyst in the presence of
Amberlyst-15(H)® without the assistance of
additional conductive salts. A wide range of
functional groups are proved to be compatible with
the standard conditions. Gram scale reaction of 1a
and 2a demonstrates the practicality of the protocol.
The heterogeneous catalyst, Amberlyst-15(H)®, can
be reused in up to five consecutive runs without
significant loss in reaction efficiency. Mechanistic
studies reveal that the electrochemical α-
1-Phenyl-2-thiocyanatoethanone (3b)
Yield: 106 mg,
60%; Brown oil; Flash chromatography (Petroleum
1
ether/EtOAc, 10 / 1). H NMR (300 MHz, CDCl3) δ 4.75
(s, 2H), 7.53 (t, J = 7.5 Hz, 2H), 7.68 (t, J = 7.2 Hz, 1H),
7.94 (d, J = 7.8 Hz, 2H); 13C NMR (75 MHz, CDCl3) δ
43.0, 111.8, 128.4, 129.2, 133.9, 134.8, 190.8.
2-Methyl-1-phenyl-2-thiocyanatopropan-1-one (3c) Yield:
31 mg, 15%; Brown oil; Flash chromatography (Petroleum
1
ether/EtOAc, 20 / 1). H NMR (300 MHz, CDCl3) δ 2.01
(s, 6H), 7.49 (t, J = 7.8 Hz, 2H), 7.60 (t, J = 7.2 Hz, 1H),
7.91 (d, J = 8.1 Hz, 2H); 13C NMR (75 MHz, CDCl3) δ
27.8, 64.1, 111.9, 128.7, 129.1, 133.2, 133.9, 198.4;
HRMS (ESI) m/z calcd for C11H12NOS (M+H)+ 206.06341,
found 206.06356; HRMS (ESI) m/z calcd for C11H15N2OS
(M+NH4)+ 223.08996, found 223.09019; HRMS (ESI) m/z
calcd for C11H11NNaOS (M+Na)+ 228.04536, found
228.04560.
thiocyanation
undergoes initial α-iodination, followed by
/
sulfenation of ketones likely
a
2-Cyclopropyl-1-phenyl-2-thiocyanatoethanone
(3d)
nucleophilic substitution of NaSCN or heterocyclic
thiols. In this way, the iodide ion can be used
catalytically, thereby avoiding the utilization of
stoichiometrical amount of molecular iodine or a
combination of iodide and co-oxidant and thereby
represents an environmentally benign means by
which to achieve the transformation. Application of
these ideas and results to other types of reactions is
underway in our laboratory.
Yield: 108 mg, 50%; Brown oil; Flash chromatography
(Petroleum ether/EtOAc, 15 / 1). 1H NMR (600 MHz,
CDCl3) δ 0.53-0.57 (m, 1H), 0.70-0.75 (m, 1H), 0.77-0.81
(m, 1H), 0.88-0.94 (m, 1H), 1.53-1.59 (m, 1H), 4.49 (d, J =
9.0 Hz, 1H), 7.53 (t, J = 7.8 Hz, 2H), 7.66 (t, J = 7.8 Hz,
1H), 7.92 (d, J = 7.8 Hz, 2H); 13C NMR (150 MHz,
CDCl3) δ 5.8, 6.7, 14.6, 58.1, 111.7, 128.9, 129.1, 134.4,
134.5, 194.0; HRMS (ESI) m/z calcd for C12H12NOS
(M+H)+ 218.06341, found 218.06286; HRMS (ESI) m/z
calcd for C12H15N2OS (M+NH4)+ 235.08996, found
235.08944; HRMS (ESI) m/z calcd for C12H11NNaOS
(M+Na)+ 240.04536, found 240.04487.
2-Thiocyanato-1-(p-tolyl) propan-1-one (3e) Yield: 145
Experimental Section
mg, 71%; Brown oil; Flash chromatography (Petroleum
1
ether/EtOAc, 15 / 1). H NMR (300 MHz, CDCl3) δ 1.85
Instruments and reagents
(d, J = 7.2 Hz, 3H), 2.44 (s, 3H), 5.07 (q, J = 7.2 Hz, 1H),
7.32 (d, J = 7.8 Hz, 2H), 7.83 (d, J = 8.1 Hz, 2H); 13C
NMR (75 MHz, CDCl3) δ 20.0, 21.8, 50.2, 111.7, 128.9,
129.8, 130.5, 145.8, 194.4; HRMS (ESI) m/z calcd for
C11H12NOS (M+H)+ 206.06341, found 206.06286; HRMS
(ESI) m/z calcd for C11H15N2OS (M+NH4)+ 223.08996,
NMR spectra were recorded with a spectrometer (300
1
MHz or 600 MHz H frequency, 75 MHz or 150 MHz 13C
frequency). Chemical shifts are given as δ values (internal
6
This article is protected by copyright. All rights reserved.

10.1002/adsc.201701401
Advanced Synthesis & Catalysis
found 223.08948; HRMS (ESI) m/z calcd for
C11H11NNaOS (M+Na)+ 228.04536, found 228.04491.
4-Thiocyanatononan-5-one (3l) Yield: 70 mg, 35%; Brown
oil; Flash chromatography (Petroleum ether/EtOAc, 15 / 1).
1H NMR (300 MHz, CDCl3) δ 0.91 (t, J = 7.5 Hz, 3H),
0.97 (t, J = 7.5 Hz, 3H), 1.24-1.52 (m, 4H), 1.56-1.66 (m,
2H), 1.85-2.11 (m, 2H), 2.51-2.70 (m, 2H), 3.94 (t, J = 6.6
Hz, 1H); 13C NMR (75 MHz, CDCl3) δ 13.6, 13.8, 19.5,
22.2, 25.7, 33.0, 40.1, 56.6, 110.7, 204.3; HRMS (ESI) m/z
calcd for C10H18NOS (M+H)+ 200.11036, found
200.11046; HRMS (ESI) m/z calcd for C10H21N2OS
(M+NH4)+ 217.13691, found 217.13699; HRMS (ESI) m/z
calcd for C10H17NNaOS (M+Na)+ 222.09231, found
222.09247.
2-Thiocyanato-1-(m-tolyl) propan-1-one (3f) Yield: 144
mg, 70%; Brown oil; Flash chromatography (Petroleum
1
ether/EtOAc, 15 / 1). H NMR (300 MHz, CDCl3) δ 1.85
(d, J = 7.1 Hz, 3H), 2.43 (s, 3H), 5.08 (q, J = 6.9 Hz, 1H),
7.38-7.48 (m, 2H), 7.70-7.74 (m, 2H); 13C NMR (75 MHz,
CDCl3) δ 19.9, 21.3, 50.1, 111.5, 126.0, 129.0, 129.3,
133.1, 135.3, 139.1, 195.0; HRMS (ESI) m/z calcd for
C11H12NOS (M+H)+ 206.06341, found 206.06280; HRMS
(ESI) m/z calcd for C11H15N2OS (M+NH4)+ 223.08996,
found 223.08941; HRMS (ESI) m/z calcd for
C11H11NNaOS (M+Na)+ 228.04536, found 228.04482.
4-Oxo-3-thiocyanatopentyl 4-chlorobenzoate (3m) Yield:
30 mg, 10%; Brown oil; Flash chromatography (Petroleum
ether/EtOAc, 6 / 1). 1H NMR (600 MHz, CDCl3) δ 2.41 (s,
3H), 2.40-2.45 (m, 1H), 2.60-2.66 (m, 1H), 4.02 (t, J = 6.6
Hz, 1H), 4.48-4.55 (m, 2H), 7.43 (d, J = 8.4 Hz, 2H), 7.92
(d, J = 8.4 Hz, 2H); 13C NMR (150 MHz, CDCl3) δ 27.7,
30.1, 53.6, 61.2, 109.3, 127.9, 129.0, 131.0, 140.0, 165.5,
200.3; HRMS (ESI) m/z calcd for C13H13ClNO3S (M+H)+
298.02992, found 298.02940; HRMS (ESI) m/z calcd for
C13H16ClN2O3S (M+NH4)+ 315.05647, found 315.05598;
HRMS (ESI) m/z calcd for C13H12ClNNaO3S (M+Na)+
320.01186, found 320.01139.
1-(4-Methoxyphenyl)-2-thiocyanatopropan-1-one
(3g)
Yield: 159 mg, 72%; Brown oil; Flash chromatography
(Petroleum ether/EtOAc, 10 / 1). 1H NMR (300 MHz,
CDCl3) δ 1.85 (d, J = 7.2 Hz, 3H), 3.90 (s, 3H), 5.07 (q, J
= 7.2 Hz, 1H), 6.99 (d, J = 9.0 Hz, 2H), 7.91 (d, J = 9.0 Hz,
2H); 13C NMR (75 MHz, CDCl3) δ 20.2, 50.3, 55.7, 111.9,
114.4, 125.9, 131.3, 164.7, 193.3; HRMS (ESI) m/z calcd
for C11H12NO2S (M+H)+ 222.05833, found 222.05851;
HRMS (ESI) m/z calcd for C11H15N2O2S (M+NH4)+
239.084488, found 239.08500; HRMS (ESI) m/z calcd for
C11H11NNaO2S (M+Na)+ 244.04027, found 244.04077.
4-Oxo-5-thiocyanatopentyl 4-chlorobenzoate (3m’) Yield:
53 mg, 18%; Brown oil; Flash chromatography (Petroleum
1-(4-Chlorophenyl)-2-thiocyanatopropan-1-one (3h) Yield:
135 mg, 60%; Brown oil; Flash chromatography
(Petroleum ether/EtOAc, 12 / 1). 1H NMR (300 MHz,
CDCl3) δ 1.85 (d, J = 7.2 Hz, 3H), 4.99 (q, J = 7.2 Hz, 1H),
7.51 (d, J = 8.4 Hz, 2H), 7.88 (d, J = 8.4 Hz, 2H); 13C
NMR (75 MHz, CDCl3) δ 19.6, 49.3, 111.0, 129.6, 130.2,
131.5, 141.3, 193.5; HRMS (ESI) m/z calcd for
C10H9ClNOS (M+H)+ 226.00879, found 226.00869;
HRMS (ESI) m/z calcd for C10H12ClN2OS (M+NH4)+
243.03534, found 243.03511; HRMS (ESI) m/z calcd for
C10H8ClNNaOS (M+Na)+ 247.99073, found 247.99064.
1
ether/EtOAc, 6 / 1). H NMR (600 MHz, CDCl3) δ 2.12-
2.16 (m, 2H), 2.76 (t, J = 6.6 Hz, 2H), 4.04 (s, 2H), 4.36 (t,
J = 6.0 Hz, 2H), 7.42 (d, J = 8.4 Hz, 2H), 7.95 (d, J = 8.4
Hz, 2H); 13C NMR (150 MHz, CDCl3) δ 22.8, 37.9, 43.6,
63.8, 111.3, 128.3, 128.8, 128.8, 131.0, 139.7, 165.7,
200.2; HRMS (ESI) m/z calcd for C13H13ClNO3S (M+H)+
298.02992, found 298.02948; HRMS (ESI) m/z calcd for
C13H16ClN2O3S (M+NH4)+ 315.05647, found 315.05608;
HRMS (ESI) m/z calcd for C13H12ClNNaO3S (M+Na)+
320.01186, found 320.01149.
Ethyl 3-hydroxy-2-thiocyanatobut-2-enoate (3n) Yield: 93
mg, 50%; Brown oil; Flash chromatography (Petroleum
ether/EtOAc, 5 / 1). 1H NMR (600 MHz, CDCl3) δ 1.33 (t,
J = 7.2 Hz, 3H), 2.49 (s, 3H), 4.27 (q, J = 7.2 Hz, 2H),
10.63 (br, 1H); 13C NMR (150 MHz, CDCl3) δ 13.7, 14.3,
61.2, 105.1, 141.9, 161.6, 174.0; HRMS (ESI) m/z calcd
for C7H10NO3S (M+H)+ 188.03759 found 188.03698;
HRMS (ESI) m/z calcd for C7H13N2O3S (M+NH4)+
205.06414, found 205.06358; HRMS (ESI) m/z calcd for
C7H9NNaO3S (M+Na)+ 210.01953, found 210.01899.
1-(3-Chlorophenyl)-2-thiocyanatopropan-1-one (3i) Yield:
140 mg, 62%; Brown oil; Flash chromatography
(Petroleum ether/EtOAc, 10 / 1). 1H NMR (300 MHz,
CDCl3) δ 1.85 (d, J = 6.9 Hz, 3H), 4.97 (q, J = 6.9 Hz, 1H),
7.48 (t, J = 7.8 Hz, 1H), 7.63 (d, J = 6.9 Hz, 1H), 7.80 (d, J
= 7.2 Hz, 1H), 7.91 (s, 1H); 13C NMR (75 MHz, CDCl3) δ
19.4, 49.1, 110.8, 126.8, 128.8, 130.5, 134.4, 134.8, 135.6,
193.4; HRMS (ESI) m/z calcd for C10H9ClNOS (M+H)+
226.00879, found 226.00882; HRMS (ESI) m/z calcd for
C10H12ClN2OS (M+NH4)+ 243.03534, found 243.03525;
HRMS (ESI) m/z calcd for C10H8ClNNaOS (M+Na)+
247.99073, found 247.99075.
Ethyl 3-hydroxy-3-phenyl-2-thiocyanatoacrylate (3o)
Yield: 137 mg, 55%; Brown oil; Flash chromatography
(Petroleum ether/EtOAc, 5 / 1). 1H NMR (600 MHz,
CDCl3) δ 1.22 (t, J = 7.2 Hz, 3H), 4.18 (q, J = 7.2 Hz, 2H),
7.46-7.49 (m, 3H), 7.54-7.56 (m, 2H), 9.75 (br, 1H); 13C
NMR (150 MHz, CDCl3) δ 14.0, 61.4, 105.7, 128.4, 128.6,
129.0, 130.6, 142.3, 160.6, 172.1; HRMS (ESI) m/z calcd
for C12H12NO3S (M+H)+ 250.05324 found 250.05303;
HRMS (ESI) m/z calcd for C12H15N2O3S (M+NH4)+
267.07979, found 267.07961; HRMS (ESI) m/z calcd for
C12H11NNaO3S (M+Na)+ 272.03518, found 272.03495.
1-(4-Fluorophenyl)-2-thiocyanatopropan-1-one (3j) Yield:
127 mg, 61%; Brown oil; Flash chromatography
(Petroleum ether/EtOAc, 12 / 1). 1H NMR (300 MHz,
CDCl3) δ 1.85 (d, J = 7.2 Hz, 3H), 5.02 (q, J = 7.2 Hz, 1H),
7.18-7.23 (m, 2H), 7.95-8.00 (m, 2H); 13C NMR (75 MHz,
CDCl3) δ 19.7, 49.5, 111.2, 116.5 (d, J = 21.8 Hz), 129.6
(d, J = 3.1 Hz), 131.6 (d, J = 9.6 Hz), 166.5 (d, J = 256.5
Hz), 193.2; HRMS (ESI) m/z calcd for C10H9FNOS
(M+H)+ 210.03834, found 210.03770; HRMS (ESI) m/z
calcd for C10H12FN2OS (M+NH4)+ 227.06489, found
227.06428; HRMS (ESI) m/z calcd for C10H8FNNaOS
(M+Na)+ 232.02028, found 232.01972.
2-(Benzo[d]oxazol-2-ylthio)-1-phenylpropan-1-one (3p)
[16]
Yield: 85 mg, 30%; Brown oil; Flash chromatography
1
(Petroleum ether/EtOAc, 15 / 1). H NMR (300 MHz,
CDCl3): δ 1.83 (d, J = 6.0 Hz, 3H), 5.72 (q, J = 6.0 Hz,
1H), 7.23-7.32 (m, 2H), 7.43 (d, J = 6.9 Hz, 1H), 7.50 (t, J
= 7.2 Hz, 2H), 7.62 (t, J = 6.9 Hz, 2H), 8.09 (d, J = 7.2 Hz,
2H); 13C NMR (75 MHz, CDCl3): δ 19.2, 47.6, 110.0,
118.5, 124.1, 124.4, 128.9, 133.9, 134.4, 141.7, 152.0,
163.8, 197.0.
2-Thiocyanato-3,4-dihydronaphthalen-1(2H)-one
(3k)
Yield: 91 mg, 45%; Brown oil; Flash chromatography
(Petroleum ether/EtOAc, 10 / 1). 1H NMR (300 MHz,
CDCl3) δ 2.36-2.50 (m, 1H), 2.82-2.90 (m, 1H), 3.17-3.21
(m, 2H), 4.56 (dd, J = 4.8, 13.2 Hz, 1H), 7.29-7.39 (m, 2H),
7.43 (dt, J = 3.0, 7.8 Hz, 1H), 8.02 (d, J = 7.2 Hz, 1H); 13
C
NMR (75 MHz, CDCl3) δ 29.0, 31.4, 55.7, 111.7, 127.4,
128.0, 130.6, 134.8, 143.4, 191.7; HRMS (ESI) m/z calcd
for C11H10NOS (M+H)+ 204.04776, found 204.04736;
HRMS (ESI) m/z calcd for C11H13N2OS (M+NH4)+
221.07431, found 21.07393; HRMS (ESI) m/z calcd for
C11H9NNaOS (M+Na)+ 226.02971, found 226.02938.
2-(Benzo[d]thiazol-2-ylthio)-1-phenylpropan-1-one (3q)
[16] Yield: 209 mg, 70%; Brown oil; Flash chromatography
(Petroleum ether/EtOAc, 15 / 1). 1H NMR (300 MHz,
CDCl3): δ 1.76 (d, J = 7.2 Hz, 3H), 5.87 (q, J = 6.9 Hz,
1H), 7.28 (t, J = 7.5 Hz, 1H), 7.39 (t, J = 7.8 Hz, 1H), 7.45
(t, J = 7.5 Hz, 2H), 7.57 (t, J = 7.2 Hz, 1H), 7.72 (d, J= 7.8
7
This article is protected by copyright. All rights reserved.

10.1002/adsc.201701401
Advanced Synthesis & Catalysis
Hz, 1H), 7.82 (d, J = 8.1 Hz, 1H), 8.09 (d, J=7.8 Hz, 2H);
13C NMR (75 MHz, CDCl3): δ 18.3, 47.0, 121.0, 121.5,
124.4, 126.0, 128.7, 128.8, 133.5, 134.9, 135.6, 152.8,
164.6, 197.1.
[3] a) R. Yefidoff-Freedman, T. Chen, R. Sahoo, L. Chen,
G. Wagner, J. A. Halperin, B. H. Aktas, M. Chorev,
Chembiochem 2014, 15, 595-611. b) I. Lagoja, C.
Pannecouque, G. Griffioen, S. Wera, V. M.
Rojasdelaparra, A. Van-Aerschot, Eur. J. Pharm. Sci.
2011, 43, 386-392. c) M. H. Ali, W. C. Stevens,
Synthesis 1997, 7, 764-768. d) J. S. Grossert, S.
Sotheeswaran, H. R. W. Dharmaratne, T. S. Cameron,
Can. J. Chem. 1988, 66, 2870-2879. e) B. M. Trost, G.
S. Massiot, J. Am. Chem. Soc. 1977, 99, 4405-4412.
f) V. V. Kane, V. Singh, A. Martin, D. L. Doyle,
Tetrahedron 1983, 39, 345-394. g) B. M. Trost, T. N.
Salzmann, K. Hiroi, J. Am. Chem. Soc. 1976, 98,
4887-4902.
2-((1-Methyl-1H-tetrazol-5-yl) thio)-1-phenylpropan-1-one
(3r) Yield: 124 mg, 50%; Brown oil; Flash
1
chromatography (Petroleum ether/EtOAc, 6 / 1). H NMR
(300 MHz, CDCl3): δ 1.78 (d, J = 7.2 Hz, 3H), 3.91 (s, 3H),
5.72 (q, J = 7.2 Hz, 1H), 7.50 (t, J = 7.5 Hz, 2H), 7.62 (t, J
= 7.5 Hz, 1H), 8.01 (d, J = 7.2 Hz, 2H); 13C NMR (75
MHz, CDCl3): δ 19.4, 33.5, 49.5, 128.8, 129.0, 133.9,
134.2, 153.1, 196.8; HRMS (ESI) m/z calcd for
C11H13N4OS (M+H)+ 249.08046 found 249.08083; HRMS
(ESI) m/z calcd for C11H12N4NaOS (M+Na)+ 271.06240,
found 271.06257.
2-((5-Methyl-1,3,4-thiadiazol-2-yl) thio)-1-phenylpropan-
1-one (3s) Yield: 118 mg, 45%; Brown oil; Flash
[4] a) S. Hirozo, I. Eiji, B. Chem. Soc. Jpn. 1965, 38,
495-497. b) M. L. Tedjamulia, Y. Tominaga, R. N.
Castle, J. Heterocyclic. Chem. 983, 20, 1485-1495.
1
chromatography (Petroleum ether/EtOAc, 6 / 1). H NMR
(300 MHz, CDCl3): δ 1.73 (d, J = 6.9 Hz, 3H), 2.72 (s, 3H),
5.76 (q, J = 7.2 Hz, 1H), 7.48 (t, J = 7.8 Hz, 2H), 7.60 (t, J
= 7.5 Hz, 1H), 8.04 (d, J = 7.5 Hz, 2H); 13C NMR (75
MHz, CDCl3): δ 15.6, 18.5, 47.6, 128.8, 128.8, 133.8,
134.6, 163.4, 165.9, 196.9; HRMS (ESI) m/z calcd for
C12H13N2OS2 (M+H)+ 265.04638 found 265.04667; HRMS
(ESI) m/z calcd for C12H12N2NaOS2 (M+Na)+ 287.02833,
found 287.02895.
[5] a) A. Kumar, P. Ahamd, R. A. Maurya, Tetrahedron
Lett. 2007, 48, 1399-1401. b) B. V. Varun, K. Gadde,
K. R. Prabhu, Org. Biomol. Chem. 2016, 14, 7665-
7670. c) N. Devi, R. Rahaman, K. Sarma, T. Khan, P.
Barman, Eur. J. Org. Chem. 2017, 2017, 1520-1525.
1-Phenyl-2-(pyridin-2-ylthio) propan-1-one (3t) Yield: 68
[6] a) G. K. Prakash, S. T. Mathew, C. Panja, G. A. Olah,
J. Org. Chem. 2007, 72, 5847-5850. b) H. Wang, Q.
Q. Lu, C. H. Qian, C. Liu, W. Liu, K. Chen, A. W.
Lei, Angew. Chem., Int. Ed. 2016, 55, 1094-1097.
mg, 28%; Brown oil; Flash chromatography (Petroleum
1
ether/EtOAc, 15 / 1). H NMR (600 MHz, CDCl3): δ 1.64
(d, J = 7.2 Hz, 3H), 5.78 (q, J = 6.6 Hz, 1H), 7.00 (t, J =
6.0 Hz, 1H), 7.15 (d, J = 7.8 Hz, 1H), 7.43 (t, J = 7.8 Hz,
2H), 7.47 (t, J = 7.2 Hz, 1H), 7.54 (t, J = 7.8 Hz, 1H), 8.06
(d, J = 8.4 Hz, 2H), 8.39 (d, J = 4.2 Hz, 1H); 13C NMR
(150 MHz, CDCl3): δ 17.6, 42.7, 119.9, 122.5, 128.5,
128.7, 133.1, 135.6, 136.2, 149.3, 156.8, 198.4; HRMS
(ESI) m/z calcd for C14H14NOS (M+H)+ 244.07906 found
244.07833; HRMS (ESI) m/z calcd for C14H13NNaOS
(M+Na)+ 266.06101, found 266.06029.
[7] a) A. S. Matlack, Introduction to Green Chemistry,
Marcel Dekker Inc.: New York, 2001. b) H. J.
Schꢀfer, C. R. Chim. 2011, 14, 745-765. c) B. A.
Frontana-Uribe, R. D. Little, J. G. Ibanez, A. Palma,
R. Vasquez-Medrano, Green Chem. 2010, 12, 2099-
2119. d) J. C. Charpentier, Chem. Eng. J. 2007, 134,
84-92. e) R. J. Batterham, Chem. Eng. Sci. 2006, 61,
4188-4193.
[18]
S-p-tolyl 4-methylbenzenesulfinothioate (4)
white solid,
m.p.: 54~56oC; Flash chromatography (Petroleum
1
ether/EtOAc, 15 / 1). H NMR (300 MHz, CDCl3): δ 2.37
(s, 3H), 2.41 (s, 3H), 7.13 (d, J = 7.8 Hz, 2H), 7.19-7.24
(m, 4H), 7.44 (d, J = 8.1 Hz, 2H); 13C NMR (75MHz,
CDCl3): δ 21.4, 21.6, 124.5, 127.5, 129.3, 130.1, 136.4,
140.3, 142.0, 144.6.
[8] For
some
excellent
reviews
of
organic
electrochemical reactions used in synthesis, see: a) J.
I. Yoshida, K. Kataoka, R. Horcajada, A. Nagaki,
Chem. Rev. 2008, 108, 2265-2299. b) M. Yan, Y.
Kawamata, P. S. Baran, Chem. Rev., 2017, 117,
13230-13319. For recent reviews of indirect
electrolysis, see: c) Y. N. Ogibin, M. N. Elinson, G. I.
Nikishin, Russ. Chem. Rev. 2009, 78, 89-140. d) R.
Francke, R. D. Little, Chem. Soc. Rev. 2014, 43,
2492-2521. For recent examples, see: e) T. Morofuji,
A. Shimizu, J. I. Yoshida, J. Am. Chem. Soc. 2014,
136, 4496-4499. f) K. J. Frankowski, R. Z. Liu, G. L.
Milligan, K. D. Moeller, J. Aubꢁ, Angew. Chem., Int.
Ed. 2015, 54, 10555-10558. g) L. Zhu, P. Xiong, Z. Y.
Mao, Y. H. Wang, X. M. Yan, X. Lu, H. C. Xu,
Angew. Chem., Int. Ed. 2016, 55, 2226-2229. h) T.
Gieshoff, A. Kehl, D. Schollmeyer, K. D.Moeller, S.
R.Waldvogel, J. Am. Chem. Soc., 2017, 139, 12317-
12324. i) H. B. Zhao, Z. J. Liu, J. Song, H. C. Xu,
Angew. Chem. Int. Ed. 2017, 56, 12732-12735. j) Q.
L. Yang, Y. Q. L, C. Ma, P. Fang, X. J. Zhang, T. S.
Mei, J. Am. Chem. Soc., 2017, 139, 3293-3298.
Acknowledgements
A This work was supported by grants from the national key
research and development program (2016YFD0400801) and the
National Natural Science Foundation of China (No. 21472011,
21272021). ZCC and SBG are grateful to Beijing advanced
innovation center for food nutrition and human health for
fostering our collaboration.
References
[1] a) F. Pan, X. L. Li, X. M. Chen, C. Shu, P. P. Ruan, C.
H. Shen, X. Lu, L. W. Ye, ACS Catal. 2016, 6, 6055-
6062. b) S. K. R. Parumala, R. K. Peddinti, Green
Chem. 2015, 17, 4068-4072. c) I. P. Beletskaya, V. P.
Ananikov, Chem. Rev. 2011, 111, 1596-1636.
[2] a) M. I. Hegab, A. E. Rashad, A. H. Shamroukh, I. A.
Hamza, J. Sulfur. Chem. 2006, 27, 213-224. b) J. A.
Miller, A. W. Pugh, G. M. Ullah, G. M. Welsh,
Tetrahedron Lett. 2001, 42, 955-959.
[9] a) W. C. Li, C. C. Zeng, L. M. Hu, H. Y. Tian, R. D.
Little, Adv. Synth. Catal. 2013, 355, 2884-2890. b) J.
Chen, W. Q. Yan, C. M. Lam, C. C. Zeng, L. M. Hu,
8
This article is protected by copyright. All rights reserved.

10.1002/adsc.201701401
Advanced Synthesis & Catalysis
R. D. Little, Org. Lett. 2015, 17, 986-989. and
[13] Q. Jiang, B. Xu, A. Zhao, J. Jia, T. Liu, C. C. Guo, J.
Org. Chem. 2014, 79, 8750-8756.
references cited therein c) S. Liang, C. C. Zeng, X. G.
Luo, F. Z. Ren, H. Y. Tian, B. G. Sun, R. D. Little,
Green Chem. 2016, 18, 2222-2230. d) L. S. Kang, M.
H. Luo, C. M. Lam, L. M. Hu, R. D. Little, C. C.
Zeng, Green Chem. 2016, 18, 3767-3774. e) S. Liang,
C. C. Zeng, H. Y. Tian, B. G. Sun, X. G. Luo, F. Z.
Ren, J. Org. Chem. 2016, 81, 11565-11573.
[14] S. U. Dighe, S. Mukhopadhyay, K. Priyanka, S. Batra,
Org. Lett. 2016, 18, 4190-4193.
[15] a) A. Levy and J. Y. Becker, Electrochim. Acta. 2015,
178, 294. b) A. Gitkis, J. Y. Becker, J. Electroanal.
Chem. 2006, 593, 29-33. c) A. Gitkis, J. Y. Becker,
Electrochim. Acta. 2010, 55, 5854-5859.
[10] With high possibility, it is due to the almost identical
oxidation potential of NaBr (0.98 V vs Ag/AgNO3)
with NaSCN (0.90 V vs Ag/Ag NO3), which lead to
the direct oxidation of NaSCN.
[16] H. Y. Huang, H. M. Wang, R. S. Hou, H. T. Cheng, L.
C. Chen, J. Chin. Chem. Soc.-TAIP. 2008, 55, 1204-
1207.
[11] Y. Siddaraju, K. R. Prabhu, Org. Lett. 2016, 18,
[17] B. V. Varun, K. Gadde, K. R. Prabhu, Org. Biomol.
Chem. 2016, 14, 7665-7670.
6090-6093.
[12] B. V. Varun, K. Gadde, K. R. Prabhu, Org. Lett. 2015,
17, 2944-2947.
[18] D. A. Lanfranchi, G. Hanquet, J. Org. Chem. 2006,
71, 4854-4861.
9
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FULL PAPER
Redox active sodium iodide / recyclable
heterogeneous solid acid: An efficient dual
catalytic system for electrochemically oxidative
α-C-H thiocyanation and sulfenylation of
ketones
Adv. Synth. Catal. Year, Volume, Page – Page
Sen Liang,a,b Cheng-Chu Zeng,a,c,* Hong-Yu
Tian,a Bao-Guo Sun,a,* Xu-Gang Luo,b Fa-
zheng Ren b
10
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