One-pot synthesis of 2-amino-3,4-dicyanopyridines from ketoximes and tetracyanoethylene via Cu(I)-catalyzed cyclization

Article abstract of DOI:10.1016/j.tet.2019.02.032

A novel approach to 2-amino-3,4-dicyanopyridines has been discovered from Cu(I)-catalyzed cyclizations of simple and easily available ketoximes and tetracyanoethylene (TCNE). The complexed radical mechanism involves cleavage of several O[sbnd]H/N[sbnd]O/C

Full text of DOI:10.1016/j.tet.2019.02.032

Accepted Manuscript
One-pot synthesis of 2-amino-3,4-dicyanopyridines from ketoximes and
tetracyanoethylene via Cu(I)-catalyzed cyclization
Ziwei Han, Jianguang Lv, Jianmin Zhang
PII:
S0040-4020(19)30191-7
https://doi.org/10.1016/j.tet.2019.02.032
TET 30155
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 5 December 2018
Revised Date: 24 January 2019
Accepted Date: 15 February 2019
Please cite this article as: Han Z, Lv J, Zhang J, One-pot synthesis of 2-amino-3,4-dicyanopyridines
from ketoximes and tetracyanoethylene via Cu(I)-catalyzed cyclization, Tetrahedron (2019), doi: https://
doi.org/10.1016/j.tet.2019.02.032.
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ACCEPTED MANUSCRIPT
Graphical Abstract
One-pot synthesis of 2-amino-3,4-dicyanopyridines
from ketoximes and tetracyanoethylene via
Cu(I)-catalyzed cyclization
Leave this area blank for abstract info.
Ziwei Hana, Jianguang Lv a, Jianmin Zhang a,b,
*
a Department of Chemistry, College of Sciences, Shanghai University, Shanghai 200444, PR China
b Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of
Sciences, 345 Lingling Road, Shanghai 200032, PR China

1
ACCEPTED MANUSCRIPT
Tetrahedron
journal homepage: www.elsevier.com
One-pot synthesis of 2-amino-3,4-dicyanopyridines from ketoximes and
tetracyanoethylene via Cu(I)-catalyzed cyclization
Ziwei Hana, Jianguang Lv a, Jianmin Zhang a,b,
*
a Department of Chemistry, College of Sciences, Shanghai University, Shanghai 200444, PR China
b Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032,
PR China
ARTICLE INFO
ABSTRACT
Article history:
Received
A novel approach to 2-amino-3,4-dicyanopyridines has been discovered from Cu(I)-
catalyzed cyclizations of simple and easily available ketoximes and tetracyanoethylene (TCNE).
The complexed radical mechanism involves cleavage of several O-H/N-O/C-H bonds, and new
C-C/C-N bonds formation. A wide variety of substrates with different functional groups could
be smoothly converted into the corresponding products in moderate yields.
Received in revised form
Accepted
Available online
Keywords:
tetracyanoethylene
radical cyclization
ketoximes
copper-catalyzed
one-pot synthesis
Introduction
Compounds containing 2-aminopyridine skeleton play an
important role in organic synthesis, medicine and material
sciences (Figure 1) [1]. 2-aminopyridines are key skeletons in
drugs such as anti-cancer [2], anti-AIDS [3], anti-inflammatory
[4], and anti-neurodegenerative diseases [5]. Starting from 2-
aminopyridines, many complex nitrogen-containing heterocyclic
compounds, e.g., indoles [6], 1,8-naphthalidines [7],
pyridinopyrimidines [8], and pyridinoimidazoles [9], can be
easily obtained. For example, the reaction of 2-amino-5-
fluoropyridine with copper chloride and hydrochloric acid could
generate the (5FAP)2CuCl4 complex, which has remarkable
magnetic interaction to be used as potential high-temperature
superconducting materials.
Figure 1 The compounds containing 2-aminopyridine
2-Aminopyrindes were traditionally prepared by Chichibabin
reaction in moderate yields by using strong bases [10]. A large
number of synthetic methods for the preparation of 2-
aminopyridine derivatives have been reported [11], such
as amination of halogenated pyridine [12], hydrogenation of 2-
nitropyridine [13], amination of pyridin-2-ylboronic acids [14],
Lossen rearrangement of N-hydroxypicolinamide with base
catalysis [15]. In the past decades, transition-metal catalyzed
cyclization has emerged as a powerful method for the synthesis
of pyridines and their derivatives [16,17].
Tetracyanoethylene (TCNE) is a highly electron-deficient
alkene and therefore is commonly used as an important raw

2
Tetrahedron
ACCEPTED MANUSCRIPT
Table 1 The optimization of reaction conditions
material for the syntheses of various organic building blocks in
many applications [18]. For instance, in the presence of
hydrolytic chloride and H2O, TNCE could react with ketones
containing
an α-hydrogen
to
give
2-chloro-3,4-
dycaynopyridines via the acid-catalyzed Michael-type addition
(Scheme 1) [18h, i]. To our best knowledge, the direct approach
to aminopyridines from simple ketoximes has not been reported.
Herein, we report on the novel copper-catalyzed one-pot
synthesis of 2-amino-3,4-dicyanopyrindes from readily available
ketoximes and TNCE (Scheme 1). The employed copper catalyst
in the present protocol enables the installation of an amino group
at the ortho-position of pyridine by utilizing the nitrogen atom
from ketoxime moiety. Meanwhile, the avoidance of using strong
acids allows a broad scope of functionalities to be incorporated
into the final products.
Entry
1
Cat.
Cu(OAc)2
Cu
Additive
Solvent
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
T (oC) Atm. Yield a (%)
/
/
/
/
/
/
/
120
120
120
120
120
120
120
120
120
60
Air
Air
Air
Air
Air
Air
Air
Air
Air
Air
Air
Air
N2
22
15
2
3
CuI
28
4
CuCl
CuBr
Pd(OAc)2
FeCl3
CuCl
CuCl
CuCl
CuCl
CuCl
CuCl
CuCl
/
35
5
30
6
14
7
Trace
32
8
NaHSO3 Toluene
9
Na2SO4
Na2SO4
Na2SO4
Na2SO4
Na2SO4
Na2SO4
Na2SO4
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
50
10
11
12
13
14
15
12
90
35
135
120
120
120
28
24
O2
Trace
2
Scheme 1 One-pot synthesis of 2-amino-3,4-dicyanopyridines
Air
Results and discussion
a Reaction conditions: 1a (0.1 mmol), 2 (0.15 mmol), catalyst (0.02 mmol)
and additive (0.2 mmol), toluenet (2 ml).
–
It is known that TCNE can release the anion radical [TCNE]•
in the presence of copper catalyst [19]. We assume that a suitable
ketoxime could trap the in situ generated anion radical to form
new heterocycles under copper’s catalysis. In order to evaluate
our hypothesis, we chose the simple acetophenone oxime (1a) in
the reaction with TCNE as our initial studies (Table 1). In the
presence of 20 mol% Cu(OAc)2, 2-amino-3,4-dicyanopyridine
(3a) was readily obtained in 22% yield from the reaction of 1a
with TCNE (Table 1, entry 1). The structure of 3a was
unambiguously confirmed by single crystal X-ray diffraction
analysis [20]. We then further optimized the reaction conditions,
including catalysts, temperatures and additives, in order to
improve the yield of the reaction. At the outset, the choice of
catalyst was made from a bundle of reactions in toluene with
different catalysts such as Cu(OAc)2, Cu, CuCl, CuI, CuBr, FeCl3
and Pd(OAc)2 (Table 1, entries 1-7). Cuprous chloride turned out
to be the best catalyst among all the copper salts (Table 1, entries
3-5), and other metal catalysts are not as effective as copper
(Table 1, entries 6-7). Na2SO4 as an additive could further
improve the yield (Table 1, entry 9), which is probably because
of scavenging the water generated from the reaction. The reaction
occurs in nitrogen atmosphere (Table 1, entry 13), but it is
severely affected by oxygen (Table 1, entry 14). Control reaction
indicated that copper catalyst is crucial for the process (Table 1,
entry 15). However, the yield could not be further improved,
probably due to the decomposition of both ketoxime and TCNE
during the reaction. Thus the optimized reaction conditions were
achieved as below: in the presence of 20 mol% of CuCl, a
mixture of acetophenone oxime 1a and TCNE 2 (1:1.5) was
refluxed in anhydrous toluene followed by addition of Na2SO4
In order to verify the universality of the reaction, different
substituted ketoximes 1 were used to react with TCNE. As shown
in Table 2, a series of 2-amino-3,4-dicyanopyridines could be
synthesized in moderate yields. Firstly, we investigated on the
effect of electron-withdrawing groups on the reactions. Fluorine,
chlorine, bromine, trifluoromethyl, cyano and nitro-substituted
acetophenone oximes could undergo cyclization smoothly. The
target products (3b-3t) were obtained in 37%-61% yields.
Methoxy and methylacetophenone oximes with electron-donating
groups could also afford the target products (3u-3w) in 35-38%
yields. Even when heterocyclic ketoximes were applied to TCNE,
the corresponding products 3y and 3z could be obtained. When
acetophenone oxime 1a is replaced by propiophenone oxime 1za,
the corresponding methyl-substituted product 3za was obtained
in only 8% (Scheme 2). The reaction of TCNE with a more
sterically hindered substrate 2-methyl-1-phenylpropan-1-one
oxime 1zb could not proceed (Scheme 3). Furthermore, the UV
and fluorescence spectra of the products show that these
compounds have good fluorescence properties and wide Stokes
shift (see in supporting information).
Table 2 CuCl catalyzed one-pot synthesis of 2-amino-3,4-dicyanopyridines
o
(2.0 equiv.) as an additive at 120 C for 10h, affording 2-amino-
3,4-dicyanopyridine 3a in 50% yield.

3
ACCEPTED MANUSCRIPT
NO2
terminal cyano group occurs, generating intermediate B [23]. It
O2
N
NC
is rapidly captured by hydrogen radical to release the
intermediate C, followed by tautomerization to afford the desired
2-amino-3,4-dicyanopyridine.
N
NH2
CN
N
NH2
CN
N
NH2
N
NH2
CN
CN
CN
CN
CN
CN
3b, 59%
3c, 43%
3a, 50%
3d, 51%
F
F
F
F3C
N
NH2
CN
N
NH2
CN
N
NH2
CN
N
NH2
CN
CN
CN
CN
CN
3f, 40%
3g, 45%
3h, 45%
3e, 40%
Br
Br
F
F
Br
N
NH2
CN
N
NH2
CN
N
NH2
CN
N
NH2
CN
CN
CN
CN
CN
Scheme 4 The reaction of acetophenone oxime and TCNE with TEMPO
3l
, 45%
3j
3i
, 42%
3k
, 39%
, 46%
Cl
F
Cl
F
Cl
N
NH2
CN
N
NH2
CN
N
NH2
CN
N
NH2
CN
CN
CN
CN
CN
3m, 44%
3o, 46%
3n, 51%
3p
, 45%
F
F
F
F
F
F
F
N
NH2
N
NH2
CN
N
NH2
CN
N
NH2
CN
F
F
CN
CN
CN
CN
CN
3t
, 39%
3q
3r
3s
, 61%
, 42%
, 37%
H3CO
Ph
N
NH2
CN
N
NH2
CN
N
NH2
CN
N
NH2
CN
CN
CN
CN
CN
3u, 35%
3w, 37%
3x, 38%
3v, 38%
N
N
NH2
CN
N
NH2
CN
S
CN
CN
3y
3z
, 28%
, 36%
b Reaction conditions:
Na2SO4 (1 mmol) in toluene (10 mL), 120 oC, 10 h, under air
atmosphere. Isolated yields based on
1 (0.5 mmol), 2 (0.75 mmol), CuCl (0.1 mmol),
1.
Scheme 2 The reaction of propiophenone oxime and TCNE
Scheme 5 Plausible mechanism for this cyclization
Conclusion
Scheme 3 The reaction of 2-methyl-1-phenylpropan-1-one oxime and TCNE
In summary, we have developed a novel one-pot synthesis of
2-amino-3,4-dicyanopyridine derivatives from the reaction of
TCNE with readily available ketoximes under mild conditions. In
the presence of inexpensive copper catalyst, a variety of
ketoximes can be smoothly converted into the corresponding
products in moderate yields. Based on literatures and control
experiments, the proposed pathway probably involves the
Control experiments were performed to gain some insight into
the reaction mechanism. When a strong radical scavenger
2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) was added to the
reaction, the cyclization was totally blocked (Scheme 4). This
fact indicates that the pathway of the reaction probably involves
free radical mechanism (Scheme 5). The employed copper
copper-promoted formation of radical anion [TCNE •–, which
]
catalyst promotes the formation of anion radical [TCNE •–, which
]
further affords the [C2(CN)3]• radical, followed by a radical
cyclization. The overall process includes cleavage of multiple O-
H/N-O/C-H bonds and new C-C/C-N bonds formation. Further
evaluation on the synthesis of pyridine derivatives as well as the
studies of their applications in medical chemistry and material
science are ongoing in our laboratory.
further loses the CN- group to afford the [C2(CN)3]• radical
[18,19]. An electron transfer process occurs between the
previously generated Cu(II) and oxime 1a, releasing iminoxy
radical with the regeneration of Cu(I) [21]. Meanwhile, the
radical coupling reaction between the [C2(CN)3]• radical and
ketoxime enamine tautomer 1a' formed by the isomerization of
ketoxime 1a takes place [22]. After dehydration of the resulting
product, the corresponding intermediate A is thus produced. The
following intramolecular cyclization of imino radical and the
4. Experimental
4.1 General

4
Tetrahedron
ACCEPTED MANUSCRIPT
1H NMR, 19F NMR and 13C NMR spectra were recorded
= 8.82 Hz), 125.59, 116.39, 116.22,115.67,115.21,111.70,88.16.
FT-IR ν/cm-1 (KBr): 3481, 3356, 2208, 1609, 1561, 1452, 1346,
1272, 1224, 1154, 840. MALDI-FTICR MS m/z Calcd for
C13H7N4F [M+H]+ 239.0728, Found 239.0726.
respectively on 500-MHz NMR Bruker spectrometers in
diethylsulfoxide (DMSO-d6) and Chloroform (CDCl3). High-
resolution mass data were recorded on a higheresolution mass
spectrometer in the MALDL mode. The absolute configurations
of 3a was assigned by the X-ray analysis. UV spectra were
recorded on a UV-2501PC spectrometer. Fluorescence spectra
were recorded on a Shimadzu RF-5310 spectrometer. X-ray
photoelectron spectra were obtained by using Thermo Scientific
Escalab 250Xi X-ray photoelectron spectrometer.
4.2.6 2-Amino-6-(3-fluorophenyl)pyridine-3,4-dicarbonitrile (3f)
Yellow solid, 40% yield, m.p. 186.6-186.8oC. H NMR (500
1
MHz, DMSO-d6) δ 8.032-7.884 (m, 2H), 7.867 (s, 1H), 7.663 (s,
2H), 7.570 (td, J = 8.0, 6.0 Hz, 1H), 7.379 (tdd, J = 8.4, 2.7, 0.9
Hz, 1H). 19F NMR (470 MHz, Chloroform-d) δ -112.52(m,1F).
13C NMR (126 MHz, DMSO) δ 162.99 (d, JFC = 241.25 Hz),
160.13, 159.05 (d, JFC = 2.76 Hz), 138.95 (d, JFC = 7.16 Hz),
131.41 (d, JFC = 8.18 Hz), 125.81, 123.88 (d, JFC = 2.61 Hz),
118.44 (d, JFC = 21.6 Hz), 115.62, 115.11, 114.36 (d, JFC = 23.07
Hz), 112.04, 88.98. FT-IR ν/cm-1 (KBr): 3479, 3356, 2209, 1614,
1562, 1454, 1418, 1270, 858, 796. MALDI-FTICR MS m/z
Calcd for C13H7N4F [M+H]+ 239.0728, Found 239.0725.
4.2 General Procedure for Synthesis of 2-amino-3,4-
dicyanopyridines (3)
Ketoxime 1 (1 eq), tetracyanoethylene 2 (1.5 eq), CuCl (0.2
eq) and anhydrous Na2SO4 (2.0 eq) followed by anhydrous
toluene (2 mL) were added to a 10 mL reaction tube. The mixture
was stirred for 10 hours at 120oC. Then the solvent was
evaporated under reduced pressure, and the products were
purified by column chromatography (petroleum ether/ ethyl
acetate).
4.2.7 2-Amino-6-(2-fluorophenyl)pyridine-3,4-dicarbonitrile (3g)
Yellow solid, 45% yield, m.p. 163.5-164.1oC. H NMR (500
1
MHz, Chloroform-d) δ 7.995 (td, J = 7.9, 1.8 Hz, 1H), 7.535 (d, J
= 1.0 Hz, 1H), 7.492 (dddd, J = 8.2, 7.1, 5.0, 1.9 Hz, 1H), 7.352-
7.271 (m, 1H), 7.196 (ddd, J = 11.7, 8.3, 1.1 Hz, 1H), 5.534 (s,
2H). 19F NMR (470 MHz, Chloroform-d) δ -114.87(m,1F). 13C
NMR (126 MHz, CDCl3) δ 161.00 (d, JFC = 254.52 Hz), 159.08,
157.47 (d, JFC = 2.77 Hz), 132.96 (d, JFC = 9.17 Hz), 130.84 (d,
4.2.1 2-Amino-6-phenylpyridine-3,4-dicarbonitrile(3a)
1
Yellow solid, 50% yield, m.p. 179.0-179.3oC. H NMR (500
MHz, Chloroform-d) δ 8.080-7.855 (m, 2H), 7.558-7.467 (m,
3H), 7.407 (s, 1H), 5.538 (s, 2H). 13C NMR (126 MHz, CDCl3) δ
161.47, 159.30, 135.98, 131.51, 129.13, 127.42, 125.18, 114.42,
114.02, 113.08, 89.63. FT-IR ν/cm-1 (KBr): 3479, 3340, 2212,
1621, 1562, 1451, 1344, 1263, 845, 771. MALDI-FTICR MS m/z
Calcd for C13H8N4 [M+H]+ 221.0822, Found 221.0821.
JFC = 1.85 Hz), 125.04, 124.85 (d, JFC = 3.67 Hz), 124.38 (d, JFC
=
11.11 Hz), 116.90, 116.81 (t, JFC = 22.91 Hz), 114.31, 113.82,
90.28. FT-IR ν/cm-1 (KBr): 3472, 3354, 2217, 1639, 1560, 1267,
1216, 765. MALDI-FTICR MS m/z Calcd for C13H7N4F [M+H]+
239.0728, Found 239.0727.
4.2.2 2-Amino-6-(4-chlorophenyl)pyridine-3,4-dicarbonitrile (3b)
1
Yellow solid, 59% yield, m.p. 227.8-228.1oC. H NMR (500,
4.2.8 2-Amino-6-(4-(trifluoromethyl)phenyl)pyridine-3,4-
dicarbonitrile (3h)
MHz, Chloroform-d) δ 8.485-8.269 (m, 2H), 8.255-8.056 (m,
2H), 7.465 (s, 1H), 5.617 (s, 2H).13C NMR (126 MHz, CDCl3) δ
159.22, 158.75, 149.44, 141.53, 128.38, 125.90, 124.23, 113.94,
113.45, 113.31, 91.62. FT-IR ν/cm-1 (KBr): 3466, 3343, 2225,
1640, 1563, 1520, 1346, 1265, 847. MALDI-FTICR MS m/z
Calcd for C13H7N5O2 [M+H]+ 266.0673, Found 266.0672.
1
Yellow solid, 45% yield, m.p. 189.1-189.6oC. H NMR (500
MHz, DMSO-d6) δ 8.300 (dt, J = 7.9, 1.0 Hz, 2H), 7.899 (d, J =
3.5 Hz, 2H), 7.879 (s, 1H), 7.716 (s, 2H). 19F NMR (470 MHz,
Chloroform-d) δ-61.30 (s,3F). 13C NMR (126 MHz, DMSO) δ
160.19, 158.96, 140.29, 131.22 (q, JFC = 32.76 Hz), 128.54,
127.71, 126.21 (q, JFC = 3.78 Hz), 125.95, 125.55, 123.38,
115.56, 115.02, 112.33, 89.51. FT-IR ν/cm-1 (KBr): 3351, 3234,
2226, 1634, 1562, 1320, 1167, 1136, 841. MALDI-FTICR MS
m/z Calcd for C14H7N4F3 [M+H]+ 289.0696, Found 289.0693.
4.2.3 2-Amino-6-(3-nitrophenyl)pyridine-3,4-dicarbonitrile (3c)
1
Yellow solid, 43% yield, m.p. 207.9-208.1oC. H NMR (500
MHz, DMSO-d6) δ 8.926 (t, J = 2.0 Hz, 1H), 8.546 (dt, J = 7.9,
1.3 Hz, 1H), 8.369 (ddd, J = 8.2, 2.4, 0.9 Hz, 1H), 8.009 (s, 1H),
7.826 (t, J = 8.0 Hz, 1H), 7.774 (s, 2H). 13C NMR (126 MHz,
DMSO) δ 160.17, 158.09, 148.87, 138.13, 133.96, 131.03,
126.14, 125.90, 122.26, 115.53, 114.98, 112.18, 89.74. FT-IR
ν/cm-1 (KBr): 3425, 3328, 2253, 1637, 1561, 1532, 1343, 1270,
842, 736. MALDI-FTICR MS m/z Calcd for C13H7N5O2 [M+H]+
266.0673, Found 266.0671.
4.2.9 2-Amino-6-(4-bromophenyl)pyridine-3,4-dicarbonitrile (3i)
1
Green solid, 46% yield, m.p. 254.4-254.7oC. H NMR (500
MHz, Chloroform-d) δ 7.905-7.799 (m, 2H), 7.721-7.564 (m,
2H), 7.377 (s, 1H), 5.527 (s, 2H). 13C NMR (126 MHz, CDCl3) δ
160.23, 159.23, 134.80, 132.37, 128.86, 126.42, 125.42, 114.23,
113.84, 112.69, 90.10. FT-IR ν/cm-1 (KBr): 3469, 3345, 2220,
1634, 1563, 1455, 1344, 1267, 825. MALDI-FTICR MS m/z
Calcd for C13H7N4Br [M+H]+ 298.9927, Found 298.9926.
4.2.4 2-Amino-6-(4-cyanophenyl)pyridine-3,4-dicarbonitrile (3d)
1
Brown solid, 51% yield, m.p. 205.3-206.4oC. H NMR (500
MHz, DMSO-d6) δ 8.406-8.138 (m, 2H), 8.059-7.947 (m, 2H),
7.902 (s, 1H), 7.713 (s, 2H). 13C NMR (126 MHz, DMSO) δ
160.12, 158.57, 140.57, 133.25, 128.45, 126.00, 118.89, 115.53,
114.99, 113.65, 112.44, 89.75. FT-IR ν/cm-1 (KBr): 3467, 3354,
2224, 1626, 1561, 1457, 1401, 1267, 880, 550. MALDI-FTICR
MS m/z Calcd for C14H7N5 [M+H]+ 246.0774, Found 266.0673.
4.2.10 2-Amino-6-(3-bromophenyl)pyridine-3,4-dicarbonitrile
(3j)
1
Yellow solid, 42% yield, m.p. 201.8-201.9oC. H NMR (500
MHz, DMSO-d6) δ 8.321 (dp, J = 5.7, 1.8 Hz, 1H), 8.164-8.051
(m, 1H), 7.940-7.824 (m, 1H), 7.777-7.612 (m, 3H), 7.565-7.372
(m, 1H). 13C NMR (126 MHz, DMSO) δ 160.12, 158.81, 138.70,
134.11, 131.43, 130.30, 126.75, 125.80, 122.86, 115.59, 115.08,
112.03, 89.05. FT-IR ν/cm-1 (KBr): 3457, 3364, 2217, 1621,
1561,1452, 1402, 1329, 1260, 849, 789. MALDI-FTICR MS m/z
Calcd for C13H7N4Br [M+H]+ 298.9927, Found 298.9926.
4.2.5 2-Amino-6-(4-fluorophenyl)pyridine-3,4-dicarbonitrile (3e)
1
Yellow solid, 40% yield, m.p. 206.8-207.2oC. H NMR (500
MHz, DMSO-d6) δ 8.272-8.030 (m, 2H), 7.792 (s, 1H), 7.608 (s,
2H), 7.349 (t, J = 8.8 Hz, 2H). 19F NMR (470 MHz, Chloroform-
d) δ -109.61(m,1F). 13C NMR (126 MHz, DMSO) δ 165.40,
163.42, 160.16, 159.49, 133.01 (d, JFC = 3.78 Hz), 130.28 (d, JFC

5
ACCEPTED MANUSCRIPT
4.2.11 2-Amino-6-(2-bromophenyl)pyridine-3,4-dicarbonitrile
J = 4.3, 1.5 Hz, 1H), 7.361 (dddq, J = 8.3, 6.8, 5.0, 1.6 Hz, 1H).
19F NMR (470 MHz, DMSO-d6) δ -138.27 (m,1F),-141.31
(m,1F). 13C NMR (126 MHz, DMSO) δ 160.16, 156.38, 151.55
(d, JFC = 12.60 Hz), 149.57 (dd, JFC = 13.86,7.56 Hz), 147.51 (d,
JFC = 7.56 Hz), 127.53, 127.48 (dd, JFC = 8.16, 5.04 Hz) 126.26,
125.60, 119.87 (d, JFC = 17.64 Hz), 115.40, 114.93, 89.68. FT-IR
ν/cm-1 (KBr): 3430, 3335, 2218, 1631, 1562, 1486, 1545, 1346,
1266, 1060, 799. MALDI-FTICR MS m/z Calcd for C13H6N4F2
[M+H]+ 257.0633, Found 257.0631.
(3k)
White solid, 39% yield, m.p. 172.6-173.3oC. H NMR (500
1
MHz, Chloroform-d) δ 7.698 (dd, J = 8.1, 1.1 Hz, 1H), 7.490-
7.417 (m, 2H), 7.340 (ddd, J = 8.0, 7.2, 1.9 Hz, 1H), 7.292 (s,
1H), 5.593 (s, 2H).13C NMR (126 MHz, CDCl3) δ 162.66,
159.23, 138.35, 133.82, 131.37, 130.91, 127.85, 124.44, 121.12,
117.31, 114.15, 113.70, 90.40. FT-IR ν/cm-1 (KBr): 3467, 3342,
2220, 1631, 1561, 1343, 1259, 760, 632. MALDI-FTICR MS m/z
Calcd for C13H7N4Br [M+H]+ 298.9927, Found 298.9926.
4.2.17 2-Amino-6-(3,4,5-trifluorophenyl)pyridine-3,4-
dicarbonitrile (3q)
4.2.12 2-Amino-6-(2,4-difluorophenyl)pyridine-3,4-dicarbonitrile
(3l)
1
Yellow solid, 61% yield, m.p. 212.5-212.9oC. H NMR (500
MHz, Chloroform-d) δ 7.709-7.606 (m, 2H), 7.307 (s, 1H), 5.573
(s, 2H).19F NMR (470 MHz, Chloroform-d) δ -132.01(m,1F),-
154.82(m,2F). 13C NMR (126 MHz, DMSO) δ 159.93, 156.79,
152.02 (dd, JFC = 10.08, 3.85 Hz), 150.05 (dd, JFC = 9.45,3.50
Hz), 142.05, 141.93, 139.90, 126.04, 115.46, 114.89, 112.48 (dd,
JFC = 17.64,5.04 Hz), 111.69, 89.55. FT-IR ν/cm-1 (KBr): 3437,
3338, 2218, 1637, 1565, 1523, 1457, 1366, 1265, 1043, 752, 518.
MALDI-FTICR MS m/z Calcd for C13H5N4F3 [M+H]+ 275.0539,
Found 275.0538.
1
Yellow solid, 45% yield, m.p. 194.8-195.2oC. H NMR (500
MHz, DMSO-d6) δ 8.138 (ddd, J = 12.2, 7.8, 2.2 Hz, 1H), 8.059-
7.930 (m, 1H), 7.835 (s, 1H), 7.653 (s, 2H), 7.591 (dt, J = 10.4,
8.5 Hz, 1H). 19F NMR (470 MHz, DMSO-d6) δ -134.90(m,1F),-
137.61(m,1F). 13C NMR (126 MHz, DMSO) δ 160.04, 158.11,
150.91 (dd, JFC = 12.60, 57.69 Hz), 149.18 (d, JFC = 12.60Hz),
134.06 (dd, JFC = 2.52, 6.93 Hz), 125.81, 125.01 (dd, JFC = 2.52,
6.93 Hz), 118.52 (d, JFC = 17.64 Hz). FT-IR ν/cm-1 (KBr): 3440,
3341, 2216, 1635, 1555, 1512, 1456, 1347, 1269, 1115, 827, 768,
520. MALDI-FTICR MS m/z Calcd for C13H6N4F2 [M+H]+
257.0633, Found 257.0631.
4.2.18 2-Amino-6-(3,5-difluorophenyl)pyridine-3,4-dicarbonitrile
(3r)
1
4.2.13 2-Amino-6-(4-chlorophenyl)pyridine-3,4-dicarbonitrile
Yellow solid, 42% yield, m.p. 201.6-201.7oC. H NMR (500
MHz, DMSO-d6) δ 7.894 (s, 1H), 7.873-7.788 (m, 2H), 7.696 (s,
2H), 7.429 (tt, J = 9.0, 2.4 Hz, 1H). 19F NMR (470 MHz, DMSO-
d6) δ -108.86(m,1F). 13C NMR (126 MHz, DMSO) δ 164.18 (d,
JFC = 13.86 Hz), 162.22 (d, JFC =13.86 Hz), 159.99, 157.61 (t, JFC
= 3.15 Hz), 140.07 (t, JFC = 9.45 Hz), 126.02, 115.50, 114.94,
112.04, 110.84 (dd, JFC =5.67, 20.79 Hz), 106.77 (t, JFC = 25.20
Hz), 89.71. FT-IR ν/cm-1 (KBr): 3484, 3354, 2224, 1637, 1560,
1355, 1120, 985, 852. MALDI-FTICR MS m/z Calcd for
C13H6N4F2 [M+H]+ 257.0633, Found 257.0631.
(3m)
Yellow solid, 44% yield, m.p. 243.8-244.1oC. H NMR (500
1
MHz, Chloroform-d) δ 8.001-7.847 (m, 2H), 7.562-7.422 (m,
2H), 7.376 (s, 1H), 5.556 (s, 2H).13C NMR (126 MHz, CDCl3) δ
160.13, 159.22, 137.94, 134.34, 129.40, 128.68, 125.40, 114.25,
113.84, 112.73, 90.03. FT-IR ν/cm-1 (KBr): 3472, 3349, 2220,
1634, 1567, 1457, 1346, 1267, 1089, 828. MALDI-FTICR MS
m/z Calcd for C13H7N4Cl [M+H]+ 255.0432, Found 255.0431.
4.2.14 2-Amino-6-(3-chlorophenyl)pyridine-3,4-dicarbonitrile
4.2.19 2-Amino-6-(3,4-difluorophenyl)pyridine-3,4-dicarbonitrile
(3n)
(3s)
1
Yellow solid, 51% yield, m.p. 196.2-196.5oC. H NMR (500
1
Yellow solid, 37% yield, m.p. 200.5-200.6oC. H NMR (500
MHz, Chloroform-d) δ 8.002 (t, J = 2.0 Hz, 1H), 7.822 (dt, J =
7.7, 1.6 Hz, 1H), 7.494 (dt, J = 8.2, 1.5 Hz, 1H), 7.441 (t, J = 7.8
Hz, 1H), 7.379 (s, 1H), 5.568 (s, 2H). 13C NMR (126 MHz,
CDCl3) δ 159.87, 159.22, 137.68, 135.39, 131.40, 130.33,
127.61, 125.50, 125.39, 114.20, 113.77, 112.91, 90.44. FT-IR
ν/cm-1 (KBr): 3451, 3357, 2216, 1626, 1561, 1454, 1403, 1330,
1261, 848, 791. MALDI-FTICR MS m/z Calcd for C13H7N4Cl
[M+H]+ 255.0432, Found 255.0431.
MHz, DMSO-d6) δ 8.149 (dddd, J = 12.8, 8.5, 4.8, 2.4 Hz, 1H),
8.071-7.926 (m, 1H), 7.843 (td, J = 3.7, 1.9 Hz, 1H), 7.652 (s,
2H), 7.592 (dh, J = 11.5, 3.4, 3.0 Hz, 1H). 19F NMR (470 MHz,
DMSO-d6) δ -134.90(m,1F),-137.62(m,1F). 13C NMR (126 MHz,
DMSO) δ 160.06, 158.13, 152.64 (d, JFC = 13.86 Hz), 150.92 (dd,
JFC = 57.96, 12.60 Hz), 149.19 (d, JFC = 13.86 Hz), 134.12,
125.83, 125.00 (dd, JFC = 7.56, 2.52 Hz), 117.69 (dd, JFC
=
214.20, 17.64 Hz), 115.57, 115.05, 111.76, 88.87. FT-IR ν/cm-1
(KBr): 3439, 3339, 2217, 1634, 1561, 1514, 1348, 1270, 825,
769. MALDI-FTICR MS m/z Calcd for C13H6N4F2 [M+H]+
257.0633, Found 257.0631.
4.2.15 2-Amino-6-(2-chlorophenyl)pyridine-3,4-dicarbonitrile
(3o)
1
Yellow solid, 46% yield, m.p. 188.8-189.1oC. H NMR (500
4.2.20 2-Amino-6-(2,5-difluorophenyl)pyridine-3,4-dicarbonitrile
MHz, Chloroform-d) δ 7.567-7.5022 (m, 1H), 7.522-7.480 (m,
1H), 7.409 (pd, J = 7.4, 1.8 Hz, 2H), 7.348 (s, 1H), 5.835-5.282
(m, 2H). 13C NMR (126 MHz, CDCl3) δ 161.25, 159.30, 136.29,
132.04, 131.35, 131.10, 130.64, 127.33, 124.47, 117.39, 114.18,
113.73, 90.36. FT-IR ν/cm-1 (KBr): 3468, 3342, 2220, 1633,
1563, 1344, 1262, 760. MALDI-FTICR MS m/z Calcd for
C13H7N4Cl [M+H]+ 255.0432, Found 255.0431.
(3t)
Yellow solid, 39% yield, m.p. 206.2-206.2oC. H NMR (500
MHz, DMSO-d6) δ 7.731 (s, 2H), 7.706-7.649 (m, 1H), 7.497 (q,
J = 1.4 Hz, 1H), 7.441 (ddt, J = 8.4, 5.8, 1.4 Hz, 2H).19F NMR
(470 MHz, DMSO-d6) δ -117.98 (m, 1F), -119.75 (m, 1F). 13C
1
NMR (126 MHz, DMSO) δ 160.07, 159.55, 157.68 (dd, JFC
=
7.56, 2.52 Hz), 155.89, 126.47 (dd, JFC =13.86,7.56 Hz), 125.66,
119.72, 118.98, 117.01, 115.41, 114.83, 89.74. FT-IR ν/cm-1
(KBr): 3483,3337,2215,1622,1561,1492,1261,826,757. MALDI-
FTICR MS m/z Calcd for C13H6N4F2 [M+H]+ 257.0633, Found
257.0631.
4.2.16 2-Amino-6-(2,3-difluorophenyl)pyridine-3,4-dicarbonitrile
(3p)
1
Yellow solid, 45% yield, m.p. 193.7-194.2oC. H NMR (500
MHz, DMSO-d6) δ 7.735 (s, 2H), 7.687-7.527 (m, 2H), 7.498 (dt,

6
Tetrahedron
ACCEPTED MANUSCRIPT
4.2.21 2-Amino-6-(4-methoxyphenyl)pyridine-3,4-dicarbonitrile
1562, 1446, 1408,1359, 1269, 1116, 833, 710. MALDI-FTICR
MS m/z Calcd for C11H6N4S [M+H]+ 227.0386, Found 227.0385.
(3u)
Yellow solid, 35% yield, m.p. 229.5-229.8oC. H NMR (500
MHz, DMSO-d6) δ 8.097 (dd, J = 9.4, 2.7 Hz, 2H), 7.745 (d, J =
5.9 Hz, 1H), 7.523 (s, 2H), 7.056 (dd, J = 9.3, 2.7 Hz, 2H), 3.83
(s, 1H). 13C NMR (126 MHz, DMSO) δ 162.26, 160.28, 160.19,
129.58, 128.82, 125.20, 115.83, 115.46, 114.72, 111.30, 86.91,
55.89, FT-IR ν/cm-1(KBr): 3447, 3356, 2213, 1645, 1559, 1510,
1240, 1169, 1033, 827. MALDI-FTICR MS m/z Calcd for
C14H10N4O [M+H]+ 251.0927, Found 251.0926.
1
Acknowledgements
We gratefully acknowledge the National Nature Science
Foundationof China (No. 21272151) for financial support.
References and notes
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1
Yellow solid, 38% yield, m.p. 237.7-238.4oC. H NMR (500
MHz, DMSO-d6) δ 8.088-7.942 (m, 2H), 7.763 (s, 1H), 7.561 (s,
2H), 7.408-7.250 (m, 2H), 2.367 (s, 3H).13C NMR (126 MHz,
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125.38, 115.76, 115.34, 111.65,87.69, 22.56. FT-IR ν/cm-1 (KBr):
3469, 3349, 2212, 1632, 1560, 1451, 1406, 1344, 1264, 816.
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4.2.23 2-Amino-6-(o-tolyl)pyridine-3,4-dicarbonitrile (3w)
1
Yellow solid, 37% yield, m.p. 173.5-173.6oC. H NMR (500
MHz, DMSO-d6) δ 7.611 (s, 2H), 7.409 (dd, J = 7.6, 1.4 Hz, 1H),
7.324 (d, J = 0.8 Hz, 1H), 7.318-7.264 (m, 2H), 2.354 (s, 3H).
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131.35, 129.95, 129.73, 126.38, 124.82, 115.62, 115.31, 115.20,
87.72, 20.56. FT-IR ν/cm-1 (KBr): 3418, 3322, 2208, 1636, 1559,
1450, 1250, 767, 518. MALDI-FTICR MS m/z Calcd for
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Brown solid, 38% yield, m.p. 224.9-225.3oC. H NMR (500
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7.810 (m, 2H), 7.765 (dt, J = 6.5, 1.2 Hz, 2H), 7.632 (s, 2H),
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Yellow solid, 36% yield, m.p. 251.6-251.6oC. H NMR (500
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(dt, J = 8.3, 1.3 Hz, 1H), 8.021 (ddd, J = 7.8, 6.5, 1.8 Hz, 1H),
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1563, 1430, 1349, 1267, 790. MALDI-FTICR MS m/z Calcd for
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1
Yellow solid, 28% yield, m.p. 173.5-173.6oC. H NMR (500
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156.11, 142.53, 132.56, 129.97, 129.40, 125.23, 115.62, 115.30,
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