Catalyst-free synthesis of 3-sulfone nitrile from sulfonyl hydrazides and acrylonitrile in water

Article abstract of DOI:10.1039/c7ob01558e

A novel catalyst-free sulfonation reaction for synthesizing 3-sulfone nitrile compounds from sulfonyl hydrazides and acrylonitriles in water, without any metal catalyst, ligand or organic solvent, was demonstrated. This catalyst-free protocol provides a new synthetic method for the construction of 3-sulfone nitrile compounds with excellent yields. The D₂O experiment adequately proved that the catalyst-free sulfonation reaction occurs via a Michael addition mechanism and that the hydrogen of 3-sulfone nitrile comes from water.

Full text of DOI:10.1039/c7ob01558e

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Takeharu Haino et al.
Solvent-induced emission of organogels based on tris(phenylisoxazolyl)
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Catalyst-free Synthesis of 3-Sulfone Nitrile from Sulfonyl
Hydrazides and Acrylonitrile in Water
Wei Li,a Lingfeng Gao,a,* Wenyun Zhuge,a Xu Sun,a Gengxiu Zheng,a,*
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
www.rsc.org/
A novel catalyst-free sulfonation reaction of synthesizing 3-sulfone thioether compounds synthesized from the nucleophilic
nitrile compounds was demonstrated from sulfonylhydrazides and substitution reaction are easily oxidized to sulfone
acrylonitriles in water, without any metal catalyst, ligand or compounds8. Then, the leaving groups, such as halogen, alkoxy
organic solvent. The catalyst-free protocol provides
a new group, amidogen or ester groups, were displaced by cyano
synthetic method for the construction of 3-sulfone nitrile group, thus finally leading to the formation of sulfone and
compounds with excellent yields. The D2O experiment sufficiently nitrile compounds. However, some metal catalysts or oxidants,
9
proved that the catalyst-free sulfonation reaction pass a Michael such as Cu(OAc)2 , tert-butyl hydroperoxide (TBHP)10 or
addition mechnism and the hydrogen of 3-sulfone nitrile come palladium salt11 were desired across the reaction process.
from water.
Meanwhile, various side-products are formed along with the
reactions.
Introduction
As a starting substrate in the synthesis of sulfur compounds,
sulfones have been paid attention1. Specially, the sulfone
compounds are of broad-spectrum biological activity, thus
exhibiting wide application in the production of agricultural
chemicals2 and pesticide3. Meanwhile, it is noteworthy that
the key step for the construction of sulfoneis the formation of
C-S bonds,6 for which the shorter synthetic steps with available
reagents and less toxic waste were desired. On the other hand,
nitriles are important unsaturated organic compounds with
unsaturated carbon and nitrogen triple bond4 which could be
easily converted to esters5a, amides5b, amines5c, imines5d and
heterocyclic compounds5e. In view of the important roles of
sulfone and nitrile compounds, it is of great significance to
develop simple method for the construction of sulfone and
nitrile compounds, which would provide more efficient and
powerful tool for constructing biomedical molecules.
a. Michael addition and selectively oxidized sulfur ether
O
[O]
R
Michael addition
S
O
S
SH
CN
CN
R
CN
R
R=Aryl, Alkyl
b. Oxidation of sulfur ether and nucleophilic substitution
O
S
O
S
O
R
Oxidation
Substitution
CN-
S
L
R
L
CN
R
O
O
H
O
N
L= X, OR, NR, O
N
H
O
O
c. Synthesis of cyano group
(1) Oxidative functionalization
(2) Dehydration of amide
R
CH3
R
NH
2 Activating reagent
R
R
NH2
OH
R C N
R C N
O
The traditional dominant synthesis of sulfone and nitrile
compounds was realized by addition and oxidation of toxic
mercaptan or thiophenol7 (Scheme 1a). The common draw-
backs is that a variety of toxic and expensive reagents are
often required in those protocols. As shown in Scheme 1b,
Scheme 1. Typical pathways for constructing of sulfone and
cyano group
As for the synthesis of nitrile, the main synthesis methods
involve direct oxidation functionalization of amines12a
,
hydrocarbons12b
,
alcohols13 (Scheme 1c, 1). Besides, the
dehydration reaction of amide is also important for the
formation of nitrile. However, across those reaction processes,
various Lewis acid activating reagents were adopted.
Furthermore, α-hydroxyl cyano compounds14 could also be
obtained from aldehydes and ketones by nucleophilic addition.
What’s more, the selective reduction of α, β-unsaturated
nitrile is applied for the synthesis of nitrile as well.15 In recent
a.
School of Chemistry and Chemical Engineering, University of Jinan, No. 336 West
Road of Nan Xinzhuang, Jinan 250022, P.R. China.
E-mail: chm_zhenggx@ujn.edu.cn
E-mail: chm_gaolf@ujn.edu.cn
† Footnotes relaꢀng to the ꢀtle and/or authors should appear here.
Electronic Supplementary Information (ESI) available: [details of any
supplementary information available should be included here]. See
DOI: 10.1039/x0xx00000x
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decades, transition metal-catalysed coupling reaction also
With continuous interest in the concepts of “green
supplied a serious of new protocols to construct aryl cyano chemistry”20, we developed a green catalyst-free chemical
compounds16.
methodology to synthesize 3-sulfone nitrile compounds in
water (Scheme 3). We reported herein a novel water smoothly
promoted sulfonation reaction from sulfonyl hydrazides and α,
β-unsaturated nitriles.
Results and discussion
Initially, we chose 4-methylbenzenesulfonohydrazide and
acrylonitrile as substrates, and a series of lewis acids as
catalyst, such as Pd(OAc)2, FeCl3, Cu(OAc)2 and binol
phosphonic acid in water solvent under air atmosphere to
optimize the reaction conditions (Table 1, entries 1–4).
However, all the attempts only produced a trace amount of 3-
tosylpropanenitrile (3aa) (Table 1, entries 1-4). Unexpectedly,
when in the absence of any catalyst, the corresponding
product 3-tospropanenitrile was obtained in 44% yield in
water at 100 oC (Table 2, entry 8). And then, when some
organic solvents were applied to the reaction, such as alcohol,
ester, ether, CH3CN, DMF and DMSO, the solvents could not
promote the reaction at all (Table S1). It is clearly that water
played a key role in the reaction. Additionally, when the
reaction time was extended to 24 h, the yield decreased to
69% for the hydrolysis of 3-tospropanenitrile (Table 2, entry 6).
Scheme 2. The reported reaction of benzenesulfonyl hydrazide
and acrylonitrile.
The reaction of benzenesulfonyl hydrazide and acrylonitrile is
rare reported. In 2014, Huanfeng Jiang17 reported that CuCl2
could catalyse the oxidation of benzenesulfonyl hydrazide and
acrylonitrile to 3-sulfuryl α, β-unsaturated nitriles under the
atmosphere of O2 (Scheme 2a). The new method shown that
benzenesulfonyl hydrazide could generate the nucleophilic
reagent to attack the double bond. In 1967, Novacek
developed
a method that the two nitrogen atoms of
benzenesulfonoylhydrazide as nucleophilic reagent attack
three double bonds of acrylonitriles by Michael addition
reaction (Scheme 2b).18
Table 1 Optimization of the reaction conditionsa
Scheme 3. Synthesis method for the3-sulfone nitriles
The synthesis methodology of 3-sulfone nitrile compounds
are important. The traditional synthetic method was
selectively oxidized to cyano group19a. In 1963, Robert et al.
reported an iodine promoted reaction of p-benzene sulfinic
acid and acrylonitrile for the construction of 3-iodo-3-
tosylpropanenitrile (Scheme 3).19b In 2017, Hua reported the
reaction of benzene sulfinic acid sodium and acrylonitrile in
the promotion of 1.1 equiv. NaOAc for 15 h. In the report, only
acrylonitrile was involved.19c Next year, the protocol for
constructing 3-sulfone nitrile from 4-methylbenzenesulfonyl
cyanide and olefin catalysed by AIBN was revealed by Yi.19d
The influence of reaction time was carefully studied. Along
with the reducing of the reaction time, the substrates could
not completely transform (Table 2, entries 1-4). Extending the
reaction time, hydrolysis of 3-tospropanenitrile leads to a
lower yield. (Table 2, entries 4 and 5). The reaction yield could
be enhanced to 95% at 80 oC for 10 h. Especially, worthy of our
attention is that the occurrence of elevated temperature is
unfavourable to the reaction for the hydrolysis of 3-
2 | J. Name., 2012, 00, 1-3
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tospropanenitrile. (Table 2, entries 8 and 9). Beyond that, be carried out, when temprature was elevated to 120 oC as
lower reaction temperature gave only a lower yield (Table 2, shown in table 4. When 2-buteneolefine was chosen the
entries 6 and 7).
substrates, the sulfonation reaction could proceed smoothly
with good yields. It is simple to acrylonitrile. 2-buteneolefine
with arylsulfonyl hydrazides gave more than 80% of yields
Table 2 Optimization of the reaction time and temperaturea
Yieldb/%
(Table 4, 3ab
with arylsulfonyl hydrazides only gave moderate yields (Table
4, 3bc 3fc). These experimental results showed that the steric
-3gb). Unexpected, the reaction of cinnamonitrile
Entry
t/h
2
Solvent
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
T/°C
80
1
2
3
4
5
6
7
8
9
—
-
4
80
39
hindrance from the acrylonitrile had obvious inhibitory effect
on the reaction.
6
80
42
10
24
10
10
10
10
80
95
80
69
Table 4. Substrate scope of substituted sulfonyl hydrazides
with 2-buteneolefine and cinnamonitrile.a ,b
40
Trace
37
60
100
140
44
49
Reaction conditions: aThe reactions were carried out with 1a (0.5
mmol，96.1 mg, 1 eqiv.), 2a (1 mmol，0.065 mL, 2 eqiv.), solvent
water (1 mL). bYield of isolated product is based on the sulfonyl
hydrazine.
With the optimal conditions in hand, the scope of this
transformation of sulfonylation was examined. The instances
of
the
reaction
between
acrylonitrile
and
benzenesulfonohydrazides were shown in Table 3. The
optimized reaction conditions could be applicable to a list of
substituted sulfonyl hydrazides and acrylonitrile. First, we
investigated a variety of arylsulfonylhydrazides to be carried
out in the water at the optimized conditions. Regardless of the
electron-donating groups (R=Me, tBu, OMe, 2,4,6-trimethyl) or
electon-withdrawing groups (R=NO2, F) on the phenyl ring
could be presented to the desired product 3aa-3ia in excellent
yields of over 92% (Table 3). However, the arylsulfonyl
hydrazides with electron-donating groups gave slightly better
yields than that with electron-withdrawing groups. In addition,
the steric hindrance 4-tert-Butylbenzensulfonyl hydrazides had
slightly effect on the reaction.
Studies on the reaction mechanisms
To get an insight into the mechanism for the synthesis of
sulfonylation process, three control experiments were
conducted. Radical trapping experiments were carried out to
illustrate whether the reaction involves radical species. The
Table 3. Substrate scope of substituted sulfonyl hydrazides
with acrylonitrile a, b
scavenger 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO,
2
equiv.) was introduced under standard conditions to afford
3aa in 85% yield (Scheme 3a), which implied that the reaction
did not occur via a free-radical pathway21.
To further establish the generalization of the transformation,
β-substitutional acrylonitriles were applied in the
transformation. It is noteworthy that the reaction could only
Scheme 3. Control experiments to investigate the mechanism.
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spectrometer. HRMS were recorded on the TOF-HRMS-EI at
University of Ji Nan. All reactions were carried out in thick wall
pressure pipe unless otherwise indicated.
Secondly, to get an insight the hydrogen source of the
product
3, D2O was applied as the solvent. The reaction
afforded a deuterium generation product D-3aa and D-3ab
.
1
(Scheme 3, b). The HNMR indicated that the origin of the α-
hydrogen atom of 3-sulfone nitrile derived from water. On the
other hand, NaOAc or Na2CO3 was adopted as base in the
standard conditions were added in the revised manuscript. As
prediction, the reaction of 4-methylbenzenesulfonohydrazide
and acrylonitrile gave the corresponding products with a
slightly lower yield (86% and 81%, Scheme S2).
General procedure for the preparation of 3-sulfone nitrile 1a-
1i. To a stirred solution of tetrahydrofuran (5 mL) at 0 °C, 0.5 g
benzene sulfonyl chloride was added. The resultant mixture
was stirred for 2 minutes. Then 2 mL hydrazine hydrate was
dropwise added at 0 °C. The solution was stirred for 25
minutes. The mixed solution was extracted. Organic phase was
collected and dried with anhydrous sodium sulfate and
concentrated under reduced pressure to get white solid.
General procedure for the preparation of 3-sulfone nitrile
3aa-3ia. benzenesulfoyl hydrazide (0.5 mmol), acrylonitrile (1
mmol, 0.065 mL) and water (1 mL) were added in a thick wall
pressure pipe. The resultant mixture was stirred at 80 °C under
magnetic stirring for 10 h. After the reaction was completed,
the reaction solution was cooled to room temperature. The
mixture was extracted with EtOAc (2 × 50 mL) and then the
combined organic phase was washed with brine for three
times (3 × 10 mL), dried over anhydrous sodium sulfate, and
filtered. The solvent was removed under reduced pressure and
the residue was purified by column chromatography (EtOAc:
petroleum ether =1: 2), getting a light white solid.
Scheme 4 The proposed mechanism for the reaction
On the basis of our investigations and previous reports, we
proposed a possible mechanism, which was shown in Scheme
4. Initially, sulfonylhydrazide is deprotonated catalyzed by
General procedure for the preparation of 3-sulfone nitrile
3ab-3fc. benzenesulfoyl hydrazide (0.5 mmol), 2-buteneolefine
or (1 mmol, 0.065 mL) and water (1 mL) were added in a thick
wall pressure pipe. The resultant mixture was stirred at 80 °C
under magnetic stirring for 10 h. After the reaction was
completed, the reaction solution was cooled to room
temperature. The mixture was extracted with EtOAc (2 × 50
mL) and then the combined organic phase was washed with
brine for three times (3 × 10 mL), dried over anhydrous sodium
sulfate, and filtered. The solvent was removed under reduced
pressure and the residue was purified by column
chromatography (EtOAc: petroleum ether =1: 2), getting a light
white solid.
water and quickly transformed into a sulphinyl anion
resonate with the sulfur-centered anion in water. And then,
the sulfur-centered anion is selectively added 1a via Michael
addition process, leading to the nitrogen-centered anion
which can resonate with the carbon-centered anion , which
4, which
5
5
6,
7
affords 3aa by a subsequent proton transfer (PT) from
hydronium ions of the water.
Conclusions
In summary, with the solvent of water, the reaction of
sulfonylation and acrylonitrile, 2-buteneolefine, cinnamonitrile
were developed, affording 3-sulfone nitrile with excellent
yields. The sulfonylation reaction was carried out without any
catalyst, additive, ligand or organic solvent and moreover toxic
by-products. Mechanism study demonstrated that the
hydrogen of 3-sulfone nitrile is from water. In addition, a
broad scope of reaction substrates illustrated the wide
application of this reaction. The catalyst-free sulfonation reaction
pass a Michael addition mechanism and further studies to clearly
understand the mechanism are ongoing in our laboratory.
Acknowledgements
This study was supported by the National Natural Science
Foundation of China (Nos. 21601064), the Natural Science
Foundation of Shandong Province (ZR2011BQ016), General
Financial Grant from the China Postdoctoral Science
Foundation (2016M602089). We thank our colleagues for the
characterization studies and their contributions to the project.
Experimental section
Notes and references
General information Unless otherwise indicated, all
commercially available reagents and solvents were used
directly from the supplier without further purification.1HNMR
and 13CNMR were recorded at ambient temperature in CDCl3
(7.27 ppm). Chemical shift values are expressed as parts per
million (ppm) and J values are in Hertz. Splitting patterns are
indicated as s: singlet, d: doublet, t: triplet, q: quartet or
combination, br. s broad singlet or m: multiplet. Infrared
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