K2S2O8-mediated nitration of alkenes with NaNO2 and 2,2,6,6-tetramethylpiperidine-1-oxyl: Stereoselective synthesis of (E)-nitroalkenes

Article abstract of DOI:10.1016/j.tetlet.2015.11.064

A transition-metal-free nitration of alkenes with NaNO₂ in the presence of K₂S₂O₈ and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) is developed. The transformation exhibits a broad substrate scope and good functional group tolerance, thus providing a new and expedient protocol for stereoselective synthesis of (E)-nitroalkenes with moderate to good yields. Moreover, the nitration processes of (E)- and (Z)-stilbene are also studied: even though the proportion of substrates is different, the E/Z ratio of the products is basically the same. Based upon experimental observations, a possible reaction mechanism is proposed.

Full text of DOI:10.1016/j.tetlet.2015.11.064

Accepted Manuscript
K S O -Mediated Nitration of Alkenes with NaNO and 2,2,6,6-Tetramethyl-
2
2
8
2
piperidine-1-oxyl: Stereoselective Synthesis of (E)-Nitroalkenes
An Zhao, Qing Jiang, Jing Jia, Bin Xu, Yufeng Liu, Mingzhong Zhang, Qiang Liu, Weiping
Luo, Cancheng Guo
PII:
S0040-4039(15)30371-3
DOI:
http://dx.doi.org/10.1016/j.tetlet.2015.11.064
TETL 47004
Reference:
To appear in:
Tetrahedron Letters
Received Date:
Revised Date:
Accepted Date:
8 October 2015
17 November 2015
23 November 2015
Please cite this article as: Zhao, A., Jiang, Q., Jia, J., Xu, B., Liu, Y., Zhang, M., Liu, Q., Luo, W., Guo, C.,
K S O -Mediated Nitration of Alkenes with NaNO and 2,2,6,6-Tetramethylpiperidine-1-oxyl: Stereoselective
2
2
8
2
Synthesis of (E)-Nitroalkenes, Tetrahedron Letters (2015), doi: http://dx.doi.org/10.1016/j.tetlet.2015.11.064
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Graphical Abstract.
Leave this area blank for abstract info.
and 2,2,6,6-Tetramethylpiperidine-1-oxyl:
K
2
S
2
O
8
-Mediated Nitration of Alkenes with NaNO
2
Stereoselective Synthesis of (E)-Nitroalkenes
An Zhao, Qing Jiang, Jing Jia, Bin Xu, Yufeng Liu, Mingzhong Zhang, Qiang Liu, Weiping Luo, Cancheng Guo*

Tetrahedron Letters
1
Tetrahedron Letters
K S O -Mediated Nitration of Alkenes with NaNO and 2,2,6,6-
2
2
8
2
Tetramethylpiperidine-1-oxyl: Stereoselective Synthesis of (E)-Nitroalkenes
An Zhao, Qing Jiang, Jing Jia, Bin Xu, Yufeng Liu, Mingzhong Zhang, Qiang Liu, Weiping Luo,
Cancheng Guo*
College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China
*
Corresponding author. Tel.: +86-731-88821488; fax: +86-731-88821667; e-mail: ccguo@hnu.edu.cn
ARTICLE INFO
ABSTRACT
Article history:
Received
Received in revised form
Accepted
2 2 2 8
A transition-metal-free nitration of alkenes with NaNO in the presence of K S O and
2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) is developed. The transformation exhibits a
broad substrate scope and good functional group tolerance, thus providing a new and
expedient protocol for stereoselective synthesis of (E)-nitroalkenes with moderate to good
yields. Moreover, the nitration processes of (E)- and (Z)-stilbene are also studied: even
though the proportion of substrates is different, the E/Z ratio of the products is basically the
same. Based upon experimental observations, a possible reaction mechanism is proposed.
Available online
Keywords:
persulfate salts
nitration
2
015 Elsevier Ltd. All rights reserved.
alkenes
stereoselective
nitroalkenes
Direct nitration of alkenes has attracted much attention
because the resulting nitroalkenes are vital importan1t
intermediates in natural pharmaceuticals and chemical industry.
Besides, nitroalkenes can be easily used in various organic
transformations, including the construction of different carbon
accessible reagents, thus offering a simple and efficient approach
for stereoselective construction of (E)-nitroalkenes. Moreover,
the stereoselectivities of nitration were also discussed with
different proportion of (E)- and (Z)-stilbene, nitro products with
almost the same E/Z ratio were obtained.
2
skeletons, and the formation of amines, heterocyclics,
3
hydroxylamines, oximes and nitroso compounds. Consequently,
considerable efforts have been made for the development of
direct nitration of alkenes (Scheme 1). In previous studies, direct
4
5
alkene nitration involved HNO
3
and nitrogen oxides like NO
and NO as the nitro agents. However, these strategies suffer
2
from harsh reaction conditions, narrow substrate scope and poor
functional group tolerance. Alternatively, transition-metal agents
6
7
8
9
such as AgNO
been employed in the nitration process.
and coworkers reported the direct nitration process with nitrite or
2
, AgNO
3
, Fe(NO
3
)
3
, and Cu(NO
3
)
2
have also
6
-10
Among them, Maiti
Scheme 1. Different methods to synthesize nitroalkenes
6a, 6c, 8c, 11
nitrate/2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO),
The reaction of styrene with NaNO
2
in the presence of K
and TEMPO at 100 C for 24 h in 1,2-dichloroethane
ClCH CH Cl) gave β-nitrostyrene in 85% isolated yield.
Hydrogen atom at the β-position of styrene was substituted by a
NO group, and only (E)-β-nitrostyrene was obtained.
2 2 8
S O
and these protocols have made great significants in this field.
Recently, Nichols and Kuhakarn independently reported the
transition-metal-free nitrification of styrene with alkaline metals
o
(
2
2
MNO (M=K, Na) in the presence of stoichiometric amount of
2
12
2
iodine. Unfortunately, these nitration approaches have some
limitations including poor substrate scope and poor functional
group tolerance. Despite these advances, it is still highly
desirable to develop novel approaches for the construction of
nitroalkene compounds. According to Yang’s work, when N-
The initial survey of the reaction conditions was performed
with styrene as the model substrate, and the results were
summarized in Table 1. K
nitration. In the absence of K
were not obtained (Table 1, Entries 1-2). Changing the solvent to
CH CN or DMSO afforded only 33-36% yield of desired product
2 2
S O
8
and TEMPO were crucial for the
2 2 8
S O or TEMPO, β-nitrostyrene
methyl-N-arylacrylamide reacted with NaNO
2
and K
nitro-containing oxindoles were obtained. Herein we report a
transition-metal-free nitration of alkenes with NaNO that
combined K and TEMPO in this system. The present
2 2 8
S O , only
13
3
2
(Table 1, Entries 3-5). Among the reaction temperature screened,
o
2 2
S O
8
100 C was found to be the most effective (Table 1, Entries 3, 6-
method is characterized by its broad substrate scope and high
functional group compatibility utilizing inexpensive and easily
7). Subsequently, increasing the amount of K
slight drop in terms of product yield (Table 1, Entries 3, 8-9).
2 2 8
S O resulted in a

2
Tetrahedron Letters
Increasing the amount of TEMPO increased the yield of 2a
Table 1, Entries 8 and 10), while a comparable yield (70%) was
obtained when the amount of TEMPO was increased to 1.5
equiv. (Table 1, Entry 11). The influence of NaNO loading was
also investigated, a higher yield was obtained when the amount
of NaNO was 1.5 equiv. (Table 1, Entries 8, 12-13). Oxidant
screening indicated that K was the best choice for this
obtained in good yield (Table 2. 2q). A heterocyclic alkene, 2-
vinyl thiophene, underwent the reaction to provide the desired
product in 54% yield (Table 2. 2r). While the aliphatic
nitroalkenes, like (E)-1-nitro-1-tetradecene, (E)-1-nitro-1-octene
and (E)-(2-nitrovinyl)cyclohexane were also obtained in 48-57%
yield (Table 2. 2s-2u). In summary, nitroalkenes were obtained in
good yield ranging from 48-96% (Table 2. 2a-2u).
(
2
2
2 2 8
S O
reaction (Table 1, Entries 12, 14-15). To our delight, a longer
reaction time improved the yield (Table 1, Entry 16). In all cases,
a
Table 2. Nitration reaction of mono substituted alkenes.
(E)-nitro alkene was obtained as a single stereoisomer.
a
Table 1. Screening of the reaction conditions.
b
NaNO
2
Oxidant
(equiv.)
TEMPO
(equiv.)
T
o
Yield
(%)
Entry
solvent
(equiv.)
( C)
K
(
2
S
2.5)
2
O
8
1
2
3
4
5
6
7
8
9
2.0
-
ClCH
ClCH
ClCH
2
2
2
CH
CH
CH
2
2
2
Cl
Cl
Cl
100
trace
0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
1.5
2.5
1.5
1.5
1.5
-
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.2
0.5
1.5
1.2
1.2
1.2
1.2
1.2
100
100
100
100
80
K
2
(
K S O
2 2
(
2 2
K S O
(
K S O
2 2
(
2 2
K S O
(
2 2
K S O
(
K S O
2 2
(
K
2
(
2 2
K S O
(
K S O
2 2
(
2 2
K S O
(
Na
S
2
O
8
8
8
8
8
8
8
8
8
8
8
68
36
33
61
58
71
61
67
70
74
58
67
51
92
2.5)
CH
3
CN
2.5)
DMSO
2.5)
ClCH
ClCH
ClCH
ClCH
ClCH
ClCH
ClCH
ClCH
ClCH
ClCH
ClCH
2
2
2
2
2
2
2
2
2
2
2
CH
CH
CH
CH
CH
CH
CH
CH
CH
CH
CH
2
2
2
2
2
2
2
2
2
2
2
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
2.5)
120
100
100
100
100
100
100
100
100
100
2.5)
2.0)
3.0)
S
2
O
a
1
1
1
1
1
1
0
1
2
3
4
5
Reaction condition: Alkenes (0.5mmol), NaNO
2
(1.5 equiv.), K
2
S
2
O
8
(2.0
2.0)
o
equiv.), TEMPO (1.2 equiv.), ClCH
yields.
2 2
CH Cl (2 mL), 100 C, 24 h. Isolated
2.0)
To investigate the stereo-selectivity of nitration, multi
substituted alkenes were examined. As expected, the
corresponding nitro products were achieved smoothly under the
optimized reaction condition (Table 3). When Me was installed at
α- or β-position of styrene, a ˃ 6:1 E/Z mixture was obtained for
nitroalkenes (Table 3. Entries 1, 3). 1,1-diphenylethylene
underwent the nitration to form the desired product in 88% yield
(Table 3. Entry 2). When stilbene was chosen as the substrate, the
yield of nitroalkenes decreased significantly, and the E/Z ratio
was almost the same (Table 3. Entries 4-5). It is worth noting that
2.0)
2.0)
2
S
2
O
8
(
2.0)
NH
2.0)
(
4
)
2
S
2
O
8
(
c
2 2 8
K S O
(
1
6
2.0)
a
Reaction conditions: styrene (0.5mmol), NaNO
2
, oxidant, TEMPO, solvent
b
c
(
2 mL), T, 15 h. Determined by GC. Reaction time: 24 h.
3
-nitro-1,2-dihydronaphthalene and 1-nitrocyclohexene were
achieved under the optimized reaction condition (Table 3. Entries
-7). Additional, chalcone and norbornylene did not provide the
With the optimized reaction conditions in hand, the substrate
6
scope of the reaction was explored. First, mono substituted
alkenes were studied, and the results are summarized in Table 2.
All the products were (E) stereoisomer only in contrast to the
earlier-reported methods. Styrene was smoothly nitrated to
provide product 2a in 85% isolated yield. Diverse functionality
like alkyl, alkoxy, acetoxy and chloromethyl were well tolerated
desired product in this transformation (Table 3. Entries 8-9).
Based on the results outlined in Table 2 and 3, it’s interesting
5a
that the mono substituted alkenes, disubstituted alkenes that
1
2
R =R and cyclic alkenes, could undergo the reaction to obtain (E)
stereoisomer of nitroalkenes only (Table 2 and Table 3, Entries 2,
(
Table 2. 2b-2j). Compared with the previous transition-metal-
6
-7). On the other hand, multi substituted alkenes with the group
12
1 2
free methods, this transformation exhibits better generality. For
example, styrenes containing electron-donating substituents like
4
R ≠R except cyclic alkenes could be converted to the mixtures
of (E) and (Z) stereoisomer of corresponding nitroalkenes, and
the (E) stereoisomer was the main product (Table 3, Entries 1, 3-
-Me and 4-OMe could also provide corresponding nitro
products (Table 2. 2b, 2g). Notably, nitroalkenes with steric
hindrance were still achieved in good yield (Table 2. 2d-2e). The
reaction was found to be compatible with fluorine, bromine, and
chlorine groups on the aryl ring (Table 2. 2k-2p), and the
corresponding products are useful for further functionalization.
Styrenes containing the same substituent at different positions of
the aryl ring had an influence on the efficiency of this nitration.
For example, 4-bromo-styrene gave higher yield than 3-/2-
bromo-styrene (Table 2, 2n-2p). 2-Vinyl naphthalene was also
5
).
a
Table 3. Nitration reaction of multi substituted alkenes.
1
2
3
Entry
R
R
R
Product 4
Yield of 4

Tetrahedron Letters
3
b
c
decreased to 11%. Notably, the (E) nitro product was also the
main product in this process, the E/Z of products calculated about
1
2
3
Me
Ph
H
Ph
Ph
Ph
Ph
H
H
H
4a
4b
4c
62% (E:Z=6:1)
88%
2.36:1. From these two figures, it’s shown that (Z)-stilbene was
b
c
converted into (E)-stilbene at first when it was chosen as the
substrate, and then the (E) compound underwent the reaction to
obtain the corresponding products. This could explain the results
in Table 4, that the E/Z ratio of nitro products was approximately
equal, even the initial loading of (E)- and (Z)-stilbene was
different.
Me
Ph
Ph
78% (E:Z=8:1)
d
b
c
c
4
5
H
35% (E:Z=2.4:1)
d
b
Ph
39% (E:Z=2.3:1)
6
4e
4f
81%
62%
N.D.
N.D.
a
Figure 1. The nitration process of (E)-stilbene.
7
8
9
1.0
Ph
H
Bz
4g
4h
0.9
0.8
0.7
0.6
Conversion of (E)-Stilbene
a
0.5
0.4
Yield of (E)-(1-nitroethene-1,2-diyl)dibenzene
Yield of (Z)-(1-nitroethene-1,2-diyl)dibenzene
Reaction condition: Alkenes (0.5mmol), NaNO
2
(1.5 equiv.), K
2
S
2
O
8
(2.0
o
equiv.), TEMPO (1.2 equiv.), ClCH
2
CH
2
c
Cl (2 mL), 100 C, 24 h. Isolated
0.3
0.2
0.1
0.0
b
1
d
yields. Yield of (E) stereoisomer only. Determined by H NMR. The
product was mainly (E)-(1-nitroethene-1,2-diyl)dibenzene.
Next, stilbene was chosen to study the stereoselectivity of this
method (Table 4). Under the optimized reaction conditions, the
0
2
4
6
8
10
12
14 16
18
20 22
24
Time (h)
(
E) nitro compound was achieved as the main product. It is
a
Reaction condition: (E)-stilbene (0.5mmol), NaNO
2
(1.5 equiv.), K
2
S
2
O
8
noteworthy that regardless the ratio of (E)- and (Z)-stilbene, the
E/Z ratio of the products was ~2.3-2.7:1 determined by HNMR
o
1
(2.0 equiv.), TEMPO (1.2 equiv.), ClCH
GC-MS.
Figure 2. The nitration process of (Z)-stilbene.
2
CH
2
Cl (2 mL), 100 C. Detected by
(Table 4, Entries 1-5). Interestingly, when (Z)-stilbene was
a
chosen as the substrate, (E)-stilbene was detected by TLC at the
end of reaction. The reason for this phenomenon may be the
different thermodynamic stabilities between (E)- and (Z)-stilbene.
Under the optimized condition (100 C), (Z)-stilbene could be
transformed into (E)-stilbene in the reaction process (see below).
1.0
0.9
o
0.8
Conversion of (Z)-Stilbene
Yield of (E)-Stilbene
Yield of (E)-(1-nitroethene-1,2-diyl)dibenzene
Yield of (Z)-(1-nitroethene-1,2-diyl)dibenzene
0
.7
.6
0
a
Table 4. Stereoselective nitration reaction.
0.5
0
0
0
0
0
.4
.3
.2
.1
.0
b
Entry
Substrate
E:Z
1
2
3
4
5
(E)-stilbene
2.30:1
2.43:1
2.68:1
2.36:1
2.51:1
0
2
4
6
8
10
12
14 16
18
20 22
24
(Z)-stilbene
Time (h)
a
(E)- and (Z)-stilbene (1:1)
(E)- and (Z)-stilbene (2:1)
(E)- and (Z)-stilbene (1:2)
Reaction condition: (Z)-stilbene (0.5mmol), NaNO
2.0 equiv.), TEMPO (1.2 equiv.), ClCH CH
2
(1.5 equiv.), K
2
S
2
O
8
o
(
2
2
Cl (2 mL), 100 C. Detected by
GC-MS.
Several control experiments were carried out to probe the
mechanism of this nitration method. According to the literature,
13
a
Reaction condition: Stilbene (0.5mmol), NaNO
2
(1.5 equiv.), K
2
S
2
O
8
(2.0
o
b
equiv.), TEMPO (1.2 equiv.), ClCH
2
CH
2
Cl (2 mL), 100 C, 24 h.
1
Determined by H NMR.
In order to verify the inference, the process of the nitration
under standard condition was investigated. The nitration of (E)-
and (Z)-stilbene monitored by GC-MS are shown in Figure 1 and
2, respectively. As shown in Figure 1, with increasing reaction
time, the conversion of (E)-stilbene increased fast at first and
then slowed down. The yield of (E)-(1-nitroethene-1,2-
diyl)dibenzene increased faster than that of (Z) nitro product. In
this process, when the substrate was (E)-stilbene, (E)-(1-
nitroethene-1,2-diyl)dibenzene was the main product, and the E/Z
ratio of nitro products was about 2.42:1. It is clearly that no (Z)-
stilbene was found in reaction process. In another case, from
Figure 2, with the time going by, the conversion of (Z)-stilbene
increased fast from 0 to 2 h, and then came to a balance. The
increasing tendency of (E) and (Z) nitro products was similar to
Figure 1. It could be found that (E)-stilbene was detected in the
whole process, which was consistent with the result detected by
TLC. The yield of (E)-stilbene increased firstly and then
Standaed conditions: styrene (0.5mmol), NaNO
equiv.), TEMPO (1.2 equiv.), ClCH CH Cl (2 mL), 100 C, 24 h. For a,
without K (2.0 equiv.). For b, BHT (2.0 equiv.) was added. For c,
without TEMPO (1.2 equiv.). For d, TEMPO (1.2 equiv.) was replaced by
NHPI (10 mol%). Detected by GC/GC-MS.
2 2 2 8
(1.5 equiv.), K S O (2.0
o
2
2
2 2 8
S O
Scheme 2. Control experiments.

4
Tetrahedron Letters
-
NO
2
could form a nitrogen dioxide radical in the presence of
. Without addition of K , (E)-β-nitrostryene was
(e) Wu, M.-Y.; Wang, M.-Q.; Li, K.; Feng, X.-W.; He, T.; Wang, N.;
Yu, X.-Q. Tetrahedron Lett. 2011, 52, 679-683; (f) Yan, R.-L.; Yan,
H.; Ma, C.; Ren, Z.-Y.; Gao, X.-A.; Huang, G.-S.; Liang, Y.-M. J.
Org. Chem. 2012, 77, 2024-2028; (g) Rahmani-Nezhad, S.; Safavi, M.;
Pordeli, M.; Ardestani, S. K.; Khosravani, L.; Pourshojaei, Y.;
Mahdavi, M.; Emami, S.; Foroumadi, A.; Shafiee, A. Eur. J. Med.
Chem. 2014, 86, 562-569; (h) Denmark, S. E.; Thorarensen, A. Chem.
Rev. 1996, 96, 137-165; (i) Arai, T.; Mishiro, A.; Yokoyama, N.;
Suzuki, K.; Sato, H. J. Am. Chem. Soc. 2010, 132, 5338-5339; (j)
Albrecht, Ł.; Dickmeiss, G.; Acosta, F. C.; Rodríguez-Escrich, C.;
Davis, R. L.; Jørgensen, K. A. J. Am. Chem. Soc. 2012, 134, 2543-
2546.
K
2
S
2
O
8
2 2 8
S O
almost not detected by GC and GC-MS (Scheme 2a). When the
radical inhibitor, 2,6-di-tert-butyl-4-methylphenol (BHT) was
added in the standard reaction, trace product was detected
(Scheme 2b). This result indicated that the reaction presumably
underwent a radical pathway. And another control experiment
showed that the nitro product was not obtained without TEMPO
(Scheme 2c). For further research the role of TEMPO, N-
hydroxyphthalimide (NHPI) was added into this reaction to
replace TEMPO, and (E)-β-nitrostryene was obtained in 12%
yield (Scheme 2d). It indicated that TEMPO could abstract the
hydrogen atom like phthalimide-N-oxyl radical (PINO) which
could be generated from NHPI under oxidation condition . And
the intermediate TEMPOH was also detected by GC-MS .
3.
(a) Larock, R. C. Comprehensive Organic Transformations; John
Wiley and Sons, Inc., New York, 1999; (b) Ballini, R.; Petrini, M.
Tetrahedron 2004, 60, 1017-1047; (c) Corma, A.; Serna, P.; García, H.
J. Am. Chem. Soc. 2007, 129, 6358-6359; (d) Zheng, B.; Wang, H.;
Han, Y.; Liu, C.-L.; Peng, Y.-G. Chem. Commun. 2013, 49, 4561-
4563; (e) Quan, X.-J.; Ren, Z.-H.; Wang, Y.-Y.; Guan, Z.-H. Org. Lett.
14
15
2
014, 16, 5728-5731.
6c,
Based on the above experimental results and previous reports
4
.
Tinsley, S. W. J. Org. Chem. 1961, 26, 4723-4724.
8c, 9, 11, 13, 16
,
a plausible mechanism is proposed and shown in
5.
(a) Jovel, I.; Prateeptongkum, S.; Jackstell, R.; Vogl, N.; Weckbecker,
C.; Beller, M. Adv. Synth. Catal. 2008, 350, 2493-2497; (b) Suzuki, H.;
Mori, T. J. Org. Chem. 1997, 62, 6498-6502; (c) Bryant, D. K.;
Challis, B. C.; Iley, J. J. Chem. Soc., Chem. Commun. 1989, 1989,
-
2-
2 2 8
Scheme 3. Firstly, NO reacted with S O to generate a nitrogen
dioxide radical, and then the free radical added to the carbon–
carbon double bond of alkene to afford the intermediate A.
TEMPO abstracted the hydrogen atom next to nitro group, and
the carbon–carbon double bond was formed. Though the
plausible mechanism is supported, more details still need to be
1
027-1028.
6
.
(a) Maity, S.; Naveen, T.; Sharma, U.; Maiti, D. Synlett 2014, 25, 603-
607; (b) Sy, W.-W.; By, A. W. Tetrahedron Lett. 1985, 26, 1193-1196;
(c) Maity, S.; Manna, S.; Rana, S.; Naveen, T.; Mallick, A.; Maiti, D.
J. Am. Chem. Soc. 2013, 135, 3355-3358.
studied.
7
8
.
.
Kancharla, P. K.; Reddy, Y. S.; Dharuman, S.; Vankar, Y. D. J. Org.
Chem. 2011, 76, 5832-5837.
(a) Varma, R. S.; Naicker, K. P.; Liesen, P. J. Tetrahedron Lett. 1998,
3
2
9, 3977-3980; (b) Taniguchi, T.; Fujii, T.; Ishibashi, H. J. Org. Chem.
010, 75, 8126-8132; (c) Naveen, T.; Maity, S.; Sharma, U.; Maiti, D.
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9
1
.
Begari, E.; Singh, C.; Nookaraju, U.; Kumar, P. Synlett 2014, 25, 1997-
2
000.
0. (a) Corey, E. J.; Estreicher, H. J. Am. Chem. Soc. 1978, 100, 6294-6295;
b) Hwu, J. R.; Chen, K.-L.; Ananthan, S.; Patel, H. V.
Scheme 3. Proposed mechanism of nitration method.
(
Organometallics 1996, 15, 499-505; (c) Campos, P. J.; García, B.;
Rodríguez, M. A. Tetrahedron Lett. 2000, 41, 979-982.
1. Maity, S.; Naveen, T.; Sharma, U.; Maiti, D. Org. Lett. 2013, 15, 3384-
In summary, an efficient transition-metal-free,
2 2 8
K S O -
mediated direct nitration of alkenes with NaNO in the presence
2
1
of TEMPO was developed. A wide range of alkenes including
styrenes, heterocyclic and aliphatic alkenes were compatible
under this condition, affording (E)-nitroalkenes in moderate to
good yields. Moreover, the effect of the stereostructures of alkene
on the stereoselectivity of nitro products were also studied: even
though the proportion of (E)- and (Z)- substrates is different, the
E/Z ratio of the resulting nitro products is almost the same.
3
387.
12. (a) Ghosh, D.; Nichols, D. E. Synthesis 1996, 1996, 195-197; (b)
Hlekhlai, S.; Samakkanad, N.; Sawangphon, T.; Pohmakotr, M.;
Reutrakul, V.; Soorukram, D.; Jaipetch, T.; Kuhakarn, C. Eur. J. Org.
Chem. 2014, 2014, 7433-7442.
1
3. Li, Y.-M.; Wei, X.-H.; Li, X.-A.; Yang, S.-D. Chem. Commun. 2013,
9, 11701-11703.
14. (a) Sheldon, R. A.; Arends, I. W. C. E. J. Mol. Catal. A: Chem. 2006,
4
2
3
51, 200-214; (b) Recupero, F.; Punta, C. Chem. Rev. 2007, 107, 3800-
842; (c) Lee, J.-M.; Park, E.-J.; Cho, S.-H.; Chang, S. J. Am. Chem.
Acknowledgment
Soc. 2008, 130, 7824–7825; (d) Orlińska, B. Tetrahedron Lett. 2010,
1, 4100-4102; (e) Zhao, H.-Q.; Sun, W.; Miao, C.-X.; Zhao, Q.-Y. J.
5
We are grateful for the financial support from the National
Natural Science Foundation of China (21372068, 21572049).
Mol. Catal. A: Chem. 2014, 393, 62-67.
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1
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