Nano-Co3S4 as a Retrievable and Robust Catalyst for the Synthesis of 2-Oxo-pyridines and 5-Oxo-[1,2,4]triazolo[2,3-a]pyridines

Full text of DOI:10.1080/00304948.2019.1615365

Organic Preparations and Procedures International
The New Journal for Organic Synthesis
ISSN: 0030-4948 (Print) 1945-5453 (Online) Journal homepage: https://www.tandfonline.com/loi/uopp20
Nano-Co3S4 as a Retrievable and Robust Catalyst
for the Synthesis of 2-Oxo-pyridines and 5-Oxo-
[1,2,4]triazolo[2,3-a]pyridines
Javad Safaei-Ghomi, Samane Esmaili, Raheleh Teymuri & Hossein Shahbazi-
Alavi
To cite this article: Javad Safaei-Ghomi, Samane Esmaili, Raheleh Teymuri & Hossein Shahbazi-
Alavi (2019): Nano-Co3S4 as a Retrievable and Robust Catalyst for the Synthesis of 2-Oxo-
pyridines and 5-Oxo-[1,2,4]triazolo[2,3-a]pyridines, Organic Preparations and Procedures
International, DOI: 10.1080/00304948.2019.1615365
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Organic Preparations and Procedures International, 0:1–9, 2019
# 2019 Taylor & Francis Group, LLC
ISSN: 0030-4948 print / 1945-5453 online
DOI: 10.1080/00304948.2019.1615365
OPPI BRIEF
Nano-Co3S4 as a Retrievable and Robust Catalyst
for the Synthesis of 2-Oxo-pyridines and 5-Oxo-
[1,2,4]triazolo[2,3-a]pyridines
Javad Safaei-Ghomi, Samane Esmaili, Raheleh Teymuri, and
Hossein Shahbazi-Alavi
Department of Organic Chemistry, Faculty of Chemistry, University of
Kashan, 51167 Kashan, Iran
Pyridones possess many biological properties such as antibacterial,1 anti-inflammatory,2
antiproliferative,3 antitumor,4 antihepatitis B,5 and anti-HIV-1 activities.6 Finding effective
methods for the preparation of pyridones is a principal challenge. Recently, reports have
appeared on the synthesis of pyridones using such catalysts as [bmim]BF4,7 [RuCl2(p-cym-
ene]2,8 [TMG][Lac] (1,1,3,3-tetramethylguanidine lactate),9 sodium ethoxide,10 piperidine,11
and bismuth(III) nitrate pentahydrate (Bi(NO3)3ꢀ5H2O).12
Despite the use of these procedures, there remains a need for further new methods
for the preparation of pyridones. Nanoscale heterogeneous catalysts present high surface
areas, which are mainly responsible for their catalytic activity.13–15 Among diverse
nanoparticles, metal sulfide nanoparticles have received substantial attention due to
their unique properties and possible applications in numerous fields.16–17 As part of our
ongoing interest in the use of nanoscale heterogeneous catalysts for the preparation of
heterocyclic systems,18–19 we now wish to report the use of Co3S4 nanoparticles as an
efficient catalyst for the preparation of 2-oxo-pyridines by the four-component reaction
of hydrazine hydrate, ethyl cyanoacetate, malononitrile and aldehydes under reflux con-
ditions in ethanol. We have also prepared 5-oxo-[1,2,4]triazolo[2,3-a]pyridines through
the reaction of 2-oxo-pyridines with acetyl chloride in the presence of Co3S4 nanopar-
ticles under reflux conditions in dimethylformamide (DMF) (Scheme 1).
We initially attempted a four-component condensation of hydrazine hydrate, ethyl
cyanoacetate, malononitrile and 4-chlorobenzaldehyde as a model reaction under differ-
ent conditions. Yields were determined in the presence of ZrO2, NiO, SnO, CoO, CoS
and Co3S4 nanoparticles and the results are shown in Table 1. Nano-Co3S4 gave the
best yields in the shortest time and a very good yield of 92% was obtained with
0.4 mol%, which was not improved by increasing to 0.6 mol%. Our nano-Co3S4 was
Received August 14, 2017; in final form January 7, 2019.
Address correspondence to Javad Safaei-Ghomi, Department of Organic Chemistry, Faculty of
Chemistry, University of Kashan, 51167 Kashan, Iran. E-mail: safaei@kashanu.ac.ir
Color versions of one or more of the figures in the article can be found online at www.tandfonline.
com/uopp.
1

2
Safaei-Ghomi et al.
O
O
OEt
CN
CN
NC
R
NH2
NH2
nano-Co S
CH COCl
NC
R
3
4
nano-Co S
;
3 4
3
N
H2N
N
+
R-CHO
+
N
+
O
CH3
NH2
reflux, ethanol
DMF, reflux
CN
N
H
CN
CN
1
2
3
5
4
6
Scheme 1. Synthesis of 2-oxo-pyridines and 5-oxo-[1,2,4]triazolo[2,3-a]pyridines using Co3S4
nanoparticles.
Table 1
Optimization of Reaction Conditions using Different Catalysts and Solventsa
Entry
solvent (reflux)
Catalyst (mol%)
———
Time (min)
Yieldb%
1
2
3
4
5
6
7
8
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
CH3CN
DMF
water
250
100
100
150
45
45
30
30
30
12
48
39
30
55
67
88
92
92
82
70
62
nano-ZrO2 (2)
nano-NiO (3)
nano-SnO (3)
nano-CoO (0.8)
nano-CoS (0.8)
nano-Co3S4 (0.2)
nano-Co3S4 (0.4)
nano-Co3S4 (0.6)
nano-Co3S4 (0.4)
nano-Co3S4 (0.4)
nano-Co3S4 (0.4)
9
10
11
12
30
30
30
aHydrazine hydrate (2 mmol), ethyl cyanoacetate (2 mmol), malononitrile (2 mmol), 4-chloro
benzaldehyde (2 mmol).
bIsolated yield.
characterized (see Experimental Section), and the data were submitted for review. A
reaction run in the absence of any catalyst gave a yield of only 12% (entry 1). EtOH
was a better solvent than MeCN, DMF and water. This work established the opti-
mum conditions.
We next turned to the efficacy of the catalyst using different aldehydes, and the
results are summarized in Table 2. We found our method to be compatible with such
aldehydes as acetaldehyde, propionaldehyde, 4-bromobenzaldehyde, 4-methoxybenzal-
dehyde, 4-nitrobenzaldehyde, and 4-isopropylbenzaldehyde. The products were isolated
in very good to excellent yields under reflux conditions in ethanol. Aldehydes contain-
ing electron-withdrawing groups generally gave yields of the corresponding 2-oxo-pyri-
dines of 90-94% in 30 min (entries 3, 4, 7, 8, 10), but those with electron-donating
groups gave slightly lower yields of 83-86% in a longer reaction time of 45 min (entries
5, 6, 9, 11, 12, 13).
In continuation of our work on the synthesis of pyridones, a series of 5-oxo[1,2,4]-
triazolo [2,3-a] pyridines has been prepared through the reaction of 2-oxo-pyridines
with acetyl chloride in the presence of Co3S4 nanoparticles under reflux conditions in
DMF (Scheme 2).
In this reaction, a plausible mechanism involves Knoevenagel condensation,
Michael addition and cyclization to form the 2-oxo-pyridines.

2-Oxo-pyridines and 5-Oxo-[1,2,4]triazolo[2,3-a]pyridines
3
Table 2
a
Synthesis of 2-oxo-pyridines using Nano-Co3S4
Time
product (min) Yieldb% (found)
mpꢁC
mpꢁC (reported)
(ref)
Entry
R (aldehyde)
1
2
3
4
5
6
7
8
CH3-
CH3CH2-
4-NO2-C6H4
4-Cl-C6H4
4-OMe-C6H4
4-OH-C6H4
4-Br-C6H4
3-NO2-C6H4
3-OH-C6H4
2-Cl-C6H4
5a
5b
5c
5d
5e
5f
5g
5h
5i
5j
5k
5l
5m
5n
55
55
30
30
45
45
30
30
40
30
45
45
45
35
75
78
94
92
85
83
92
90
86
90
85
86
84
88
202-204
209-211
226-227
243-244
224-226
242-245
234-236
218-220
232-235
239-241
212-214
239-241
230-232
237-239
———
———
226-228 (12)
242-243 (12)
222-224 (12)
——
234-236 (19)
——
9
——
10
11
12
13
14
——
4-isopropyl-C6H4
4-CH3-C6H4
4-N(CH3)2-C6H4
C6H5
——
238-240 (12)
——
237-239 (12)
aHydrazine hydrate (2 mmol), ethyl cyanoacetate (2 mmol), malononitrile (2 mmol), benzalde-
hydes (2 mmol) under reflux conditions in ethanol using nano-Co3S4.
bIsolated yield.
O
O
NC
R
NH2
NH2
NC
R
N
N
CH3COCl
nano-Co S
;
N
3 4
CH3
N
H
DMF, reflux
CN
CN
5
6
R= CH3, 4-Cl-C6H4, 4-CH3-C6H4
Scheme 2. Synthesis of 5-oxo[1,2,4]triazolo [2,3-a]pyridines using nano-Co3S4.
We also considered the reusability of the nano-Co3S4 as catalyst for the synthesis
of product 5d and it was found that product yields only reduced to a negligible extent
on each reuse (runs 1-5: 92, 92, 91, 91, 90%). After completion of the reaction (TLC),
acetone was added. The catalyst was insoluble in acetone, and it could therefore be
recycled by an easy filtration. The solvent was then evaporated and the solid obtained
recrystallized from ethanol to afford the 2-oxo-pyridines. The recovered nano-Co3S4
was washed five to seven times with ethanol and dried at room temperature for 20 h.
In this study, we have described a simple and highly efficient procedure for the
synthesis of 2-oxo-pyridines and 5-oxo-[1,2,4]triazolo[2,3-a]pyridines using nano-Co3S4
as a retrievable catalyst. High yields, low reaction times, atom economy, reusability of
the catalyst and low catalyst loading are some of the significant advantages of the pre-
sent method.

4
Safaei-Ghomi et al.
Experimental Section
The products were isolated and characterized by physical and spectral data. 1H NMR and
13C NMR spectra were recorded on Bruker Avance-400 MHz spectrometers in the pres-
ence of tetramethylsilane as internal standard. The progress of the reactions was moni-
tored by thin-layer chromatography (TLC) on Riedel-de Haen plates coated with silica
gel 60 F254. The IR spectra were recorded on FT-IR Magna 550 apparatus using KBr
plates. Melting points were determined on Electro thermal 9200, and are not corrected.
The elemental analyses (C, H, N) were obtained from a Carlo ERBA Model EA 1108
analyzer. Powder X-ray diffraction (XRD) was carried out on a Philips X’pert diffract-
ometer with monochromatized Cu Ka radiation (k¼ 1.5406 Å). Microscopic morphology
of products was visualized by SEM (MIRA 3 TESCAN). The XRD patterns of Co3S4
nanoparticles agreed well with the reported pattern (JCPDS No. 73-1703). Our SEM
image showed particles with diameters in the nanometer range. Energy Dispersive
Spectroscopy (EDS) confirmed the presence of Co and S. XRD, SEM and EDS data
were submitted for review by the Editors and are available from the author upon request.
Preparation of Co3S4 Nanoparticles
Co3S4 nanoparticles were prepared according to the technique reported in the literature.20
In a typical preparation, molar ratios (1:3) of Co(CH3COO)2ꢀ4H2O to thioglycolic acid
were mixed in 200 mL distilled water with stirring. After 30 min stirring the final solution
was sealed in a 250 mL Teflon-lined stainless steel autoclave and heated at 150ꢁC for 48h
in an electric oven. The autoclave was allowed to cool to room temperature and the product
was washed with distilled water and absolute ethanol several times to remove excessive
reactants and by-products, followed by drying in an electric oven at 70ꢁC for 12 h.
General Procedure for the Preparation of 2-oxo-pyridines (5)
A mixture of hydrazine hydrate (2 mmol), ethyl cyanoacetate (2 mmol), malononitrile
(2 mmol), aldehyde (2 mmol) and 0.4 mol% of nano-Co3S4 in ethanol (5 mL) was
refluxed with stirring for the specified time (Table 2). The reaction was monitored by
TLC (n-hexane/ethyl acetate 8:2). After cooling, the reaction mixture was dissolved in
acetone and the mixture stirred for 2 min. The suspended solution was filtered and the
heterogeneous catalyst was recovered. The acetone was evaporated and the solid that sep-
arated out was filtered and recrystallized with ethanol to get pure product. The structures
1
of the products were fully established on the basis of their H NMR, 13C NMR, FT-IR
spectra and melting points. The novel compounds gave satisfactory elemental analyses.
General Procedure for the Preparation of 5-Oxo-[1,2,4]triazolo[2,3-a]pyridines (6)
A mixture of 2-oxo-pyridines 5 (1 mmol) and acetyl chloride (1 mmol) and 0.4 mol% of
nano-Co3S4 in DMF (5 ml) was heated under reflux for 60 min, cooled and poured onto
ice. The solid obtained was filtered off and recrystallized with ethanol to get pure prod-
1
uct 6. The structures of the products were fully established on the basis of their H
NMR, 13C NMR and FT-IR spectra. The structure of compound 5e was confirmed by
1H-1H COSY.

2-Oxo-pyridines and 5-Oxo-[1,2,4]triazolo[2,3-a]pyridines
5
1,6-Diamino-4-methyl-2-oxo-1,2-dihydropyridine-3,5-dicarbonitrile (5a)
White solid, mp 202-204 ꢁC, IR (KBr): ꢀmax 3406, 3450 (NH2), 3303, 3334 (NH2),
2218, 2224 (CN), 1644 (C¼O), 1602 (C¼C) cmꢂ1;1H NMR (400 MHz, DMSO-d6): d
2.06 (s, 3H, CH3), 5.45 (s, 2H, NH2), 8.31 (s, 2H, NH2) ppm; 13C NMR (100 MHz,
DMSO-d6): d 14.18, 72.5, 88.9, 115.4, 115.7, 157.2, 159.2, 160.1 ppm.
Anal. Calcd for C8H7N5O: C, 50.79; H, 3.73; N, 37.02. Found: C, 50.67; H, 3.63;
N, 37.00.
1,6-Diamino-4-ethyl-2-oxo-1,2-dihydropyridine-3,5-dicarbonitrile (5b)
White solid, mp 209-211 ꢁC, IR (KBr): ꢀmax 3407, 3453 (NH2), 3305, 3338 (NH2),
1
2219, 2225 (CN), 1651(C¼O), 1608 (C¼C) cmꢂ1; H NMR (400 MHz, DMSO-d6): d
1.09 (CH3, t, J ¼ 7.6 Hz, 3H), 2.04 (CH2, m, 2H,), 5.53 (s, 2H, NH2), 8.34 (s, 2H, NH2)
ppm; 13C NMR (100 MHz, DMSO-d6): d 12.5, 17.10, 71.4, 87.6, 115.3, 115.5, 157.7,
159.4, 160.3 ppm.
Anal. Calcd for C9H9N5O: C, 53.20; H, 4.46; N, 34.47. Found: C, 53.14; H, 4.35;
N, 34.37.
1,6-Diamino-4-(4-nitrophenyl)-2-oxo-1,2-dihydropyridine-3,5-dicarbonitrile (5c)
Yellow solid, mp 226-228 ꢁC, IR (KBr): ꢀmax 3284, 3393 (NH2), 3318, 3328 (NH2),
2218, 2223 (CN), 1675 (C¼O), 1629 (C¼C) cmꢂ1,1H NMR (400 MHz, DMSO-d6): d
5.73 (s, 2H, NH2), 7.84 (d, 2H, J ¼ 8.8 Hz, CHAr), 8.39 (d, 2H, J ¼ 8.8 Hz, CHAr), 8.84
(s, 2H, NH2) ppm; 13C NMR (100MHz, DMSO-d6): d 74.3, 86.2, 115.3, 115.5, 124.2,
129.3, 140.8, 148.7, 156.7, 157.4, 158.6 ppm. MS (EI) (m/z): 296.
Anal. Calcd for C13H8N6O3: C, 52.71; H, 2.72; N 28.37. Found: C, 52.65; H, 2.82;
N 28.30.
1,6-Diamino-4-(4-chlorophenyl)-2-oxo-1,2-dihydropyridine-3,5-dicarbonitrile (5d)
White solid, mp 243-245˚C, IR (KBr): ꢀmax 3392, 3416 (NH2), 3294, 3303 (NH2), 2214
1
(CN), 1674 (C¼O), 1608 (C¼C) cmꢂ1; H NMR (400 MHz, DMSO-d6): d 5.65 (s, 2H,
NH2), 7.54 (d, 2H, J ¼ 8 Hz, CHAr), 7.65 (d, 2H, J ¼ 8 Hz, CHAr), 8.57 (s, 2H, NH2)
ppm; 13C NMR(100 MHz, DMSO-d6): d 74.5, 86.5, 115.2, 116.4, 128.5, 130.2, 133.1,
135.2, 156.5, 158.4, 159.3 ppm. MS (EI) (m/z): 285 (is due to the 35Cl) and 287 (is due
to the 37Cl).
Anal. Calcd for C13H8N5OCl: C, 54.65; H, 2.82; N, 24.51; Found: C, 54.62; H,
2.93; N, 24.42.
1,6-Diamino-4-(4-methoxyphenyl)-2-oxo-1,2-dihydropyridine-3,5-dicarbonitrile (5e)
Cream solid, mp 222-224 ꢁC, IR (KBr): ꢀmax 3453, 3392 (NH2), 3270, 3222 (NH2),
1
2216, 2128 (CN), 1669 (C¼O), 1643 (C¼C) cmꢂ1, H NMR (400 MHz, DMSO-d6): d
3.84 (s, 3H, OCH3), 5.97 (s, 2H, NH2), 7.12 (d, 2H, J ¼ 7.8 Hz, CHAr), 7.28 (d, 2H,
J ¼ 7.8 Hz, CHAr), 8.45 (s, 2H, NH2) ppm; 13C NMR (100 MHz, DMSO-d6): d 56.3,

6
Safaei-Ghomi et al.
74.4, 87.3, 113.8, 115.6, 116.6, 126.4, 129.8, 156.5, 159.2, 159.4, 160.2 ppm. MS (EI)
(m/z): 281.
Anal. Calcd. for C14H11N5O2: C, 59.78; H, 3.94; N, 24.89. Found: C, 59.72; H,
3.96; N, 24.73.
1,6-Diamino-4-(4-hydroxyphenyl)-2-oxo-1,2-dihydropyridine-3,5-dicarbonitrile (5f)
White solid, mp 242-245 ꢁC, IR (KBr): ꢀmax 3481, 3394 (NH2), 3274, 3226 (NH2),
2208, 2128 (CN), 1669 (C¼O), 1645 (C¼C) cmꢂ1,1H NMR (400 MHz, DMSO-d6): d
5.60 (s, 2H, NH2), 6.89 (d, 2H, J ¼ 7.8 Hz, CHAr), 7.33 (d, 2H, J ¼ 7.8 Hz, CHAr), 8.34
(s, 2H, NH2), 10.12 (s, OH) ppm; 13C NMR (100 MHz, DMSO-d6): d 74.1, 86.0, 115.2,
115.8, 116.7, 124.7, 129.8, 156.6, 159.5, 159.6, 160.4 ppm.
Anal. Calcd. for C13H9N5O2: C, 58.43; H, 3.39; N, 26.21. Found: C, 58.35; H,
3.32; N, 26.17.
1,6-Diamino-4-(4-bromophenyl)-2-oxo-1,2-dihydropyridine-3,5-dicarbonitrile (5g)
Brown crystals, mp 234-236 ꢁC, IR (KBr): ꢀmax 3384, 3412 (NH2), 3292, 3307 (NH2),
1
2214 (CN), 1666 (C¼O), 1609 (C¼C) cmꢂ1, H NMR (400 MHz, DMSO-d6): d 5.67
(s, 2H, NH2), 7.60-7.98 (m, 4H, CHAr), 8.55 (s, 2H, NH2) ppm; 13C NMR (100MHz,
DMSO-d6): d 74.4, 86.5, 115.2, 116.4, 128.6, 130.1, 133.3, 135.3, 156.5, 158.5,
159.2 ppm. MS (EI) (m/z): 329 (is due to 79Br) and 331 (is due to 81Br).
Anal. Calcd. for C13H8N5OBr: C, 47.29; H, 2.44; N, 21.21. Found: C, 47.19; H,
2.33; N, 21.25.
1,6-Diamino-4-(3-nitrophenyl)-2-oxo-1,2-dihydropyridine-3,5-dicarbonitrile (5h)
Yellow solid, mp 218-220 ꢁC, IR (KBr): ꢀmax 3285, 3396 (NH2), 3316, 3323 (NH2),
2215, 2225 (CN), 1673 (C¼O), 1625 (C¼C) cmꢂ1,1H NMR (400 MHz, DMSO-d6): d
5.76 (s, 2H, NH2), 7.92-8.04 (m, 4H, CHAr), 8.64 (s, 2H, NH2) ppm; 13C NMR
(100 MHz, DMSO-d6): d 74.4, 86.6, 115.2, 116.0, 122.2, 124.9, 130.6, 134.8, 136.8,
147.8, 156.7, 157.1, 158.6 ppm. MS (EI) (m/z): 296.
Anal. Calcd. for C13H8N6O3: C, 52.71; H, 2.72; N 28.37. Found: C, 52.63; H, 2.84;
N 28.28.
1,6-Diamino-4-(3-hydroxyphenyl)-2-oxo-1,2-dihydropyridine-3,5-dicarbonitrile (5i)
White solid, mp 232-235 ꢁC, IR (KBr): ꢀmax 3486, 3397 (NH2), 3270, 3224 (NH2),
2203, 2127(CN), 1669 (C¼O), 1642 (C¼C) cmꢂ1,1H NMR (400 MHz, DMSO-d6): d
5.62 (s, 2H, NH2), 6.80-7.34 (m, 4H, CHAr), 8.34 (s, 2H, NH2), 10.14 (s, OH) ppm;
13C NMR (100 MHz, DMSO-d6): d 74.3, 86.5, 115.6, 115.9, 116.8, 124.8, 125.3, 126.7,
129.9, 156.4, 159.1, 159.2, 160.6 ppm.
Anal. Calcd. for C13H9N5O2: C, 58.43; H, 3.39; N, 26.21. Found: C, 58.30; H,
3.30; N, 26.15.

2-Oxo-pyridines and 5-Oxo-[1,2,4]triazolo[2,3-a]pyridines
7
1,6-Diamino-4-(2-chlorophenyl)-2-oxo-1,2-dihydropyridine-3,5-dicarbonitrile (5j)
White solid, mp 239- 241˚C, IR (KBr): ꢀmax 3390, 3413 (NH2), 3292, 3306 (NH2),
1
2216 (CN), 1673 (C¼O), 1608 (C¼C) cmꢂ1; H NMR (400 MHz, DMSO-d6): d 5.67
(s, 2H, NH2), 7.50 -7.65 (m, 4H, CHAr), 8.53 (s, 2H, NH2) ppm; 13C NMR(100 MHz,
DMSO-d6): d 74.4, 86.3, 115.1, 116.2, 127.4, 128.4, 129.7, 130.5, 133.5, 135.5, 156.4,
158.5, 159.4 ppm. MS (EI) (m/z): 285 (is due to the 35Cl) and 287 (is due to the 37Cl).
Anal. Calcd. for C13H8N5OCl: C, 54.65; H, 2.82; N, 24.51. Found: C, 54.60; H,
2.91; N, 24.40.
1,6-Diamino-4-(4-isopropylphenyl)-2-oxo-1,2-dihydropyridine-3,5-dicarbonitrile (5k)
White solid, mp 212-214 ꢁC, IR (KBr): ꢀmax 3404, 3450 (NH2), 3304, 3332 (NH2),
2216, 2220 (CN), 1640 (C¼O), 1603 (C¼C) cmꢂ1,1H NMR (400 MHz, DMSO-d6): d
1.28 (d, J ¼ 7.6 Hz, 2CH3), 3.08-3.14 (m, CH), 5.63 (s, 2H, NH2), 7.28 (d, 2H,
J ¼ 8.0 Hz, CHAr), 7.39 (d, 2H, J ¼ 8.0 Hz, CHAr), 8.52 (s, 2H, NH2) ppm; 13C
NMR(100 MHz, DMSO-d6): d 21.5, 34.5, 74.7, 86.7, 115.2, 116.4, 127.5, 128.7, 131.4,
140.7, 156.4, 159.5, 159.7 ppm.
Anal. Calcd. for C16H15N5O: C, 65.52; H, 5.15; N, 23.88. Found: C, 65.48; H,
5.10; N, 23.80.
1,6-Diamino-4-(4-methylphenyl)-2-oxo-1,2-dihydropyridine-3,5-dicarbonitrile (5l)
White solid; mp 238-240 ꢁC, IR (KBr): ꢀmax 3400, 3454 (NH2), 3305, 3334 (NH2),
2219, 2221 (CN), 1640 (C¼O), 1605 (C¼C) cmꢂ1,1H NMR (400 MHz, DMSO-d6): d
2.27 (s, 3H, CH3), 5.65 (s, 2H, NH2), 7.30 (d, 2H, J ¼ 8.0 Hz, CHAr), 7.35 (d, 2H,
J ¼ 8.0 Hz, CHAr), 8.49 (s, 2H, NH2) ppm; 13C NMR(100 MHz, DMSO-d6):d 21.1,
74.4, 86.9, 115.5, 116.2, 127.3, 128.5, 131.2, 140.6, 156.3, 159.1, 159.6 ppm. MS (EI)
(m/z): 265.
Anal. Calcd. for C14H11N5O: C, 63.39; H, 4.18; N, 26.40. Found: C, 63.14; H,
4.27; N, 26.32.
1,6-Diamino-4-(4-n,n-dimethylaminophenyl)-2-oxo-1,2-dihydropyridine-3,5
dicarbonitrile (5m)
White solid, mp 230-232 ꢁC, IR (KBr): ꢀmax 3405, 3458 (NH2), 3302, 3337 (NH2),
1
2215, 2220 (CN), 1642 (C¼O), 1608 (C¼C) cmꢂ1; H NMR (400 MHz, DMSO-d6): d
2.80 (s, 6H, N(CH3)2), 5.63 (s, 2H, NH2), 7.34 (d, 2H, J ¼ 7.8 Hz, CHAr), 7.47 (d, 2H,
J ¼ 7.8 Hz, CHAr), 8.52 (s, 2H, NH2) ppm; 13C NMR(100 MHz, DMSO-d6):d 39.7,
74.1, 86.5, 115.3, 116.7, 127.4, 128.7, 131.8, 148.3, 156.3, 159.2, 159.7 ppm.
Anal. Calcd. For C15H14N6O: C, 61.21; H, 4.79; N, 28.55. Found: C, 61.15; H,
4.71; N, 28.46.
1,6-Diamino-4-phenyl-2-oxo-1,2-dihydropyridine-3,5-dicarbonitrile (5n)
White solid; mp 237-239 ꢁC, IR (KBr,): ꢀmax 3448, 3353 (NH2), 3242, 3315 (NH2),
1
2224 (CN), 1645 (C¼O), 1606 (C¼C) cmꢂ1, H NMR (400 MHz, DMSO-d6): d 5.64

8
Safaei-Ghomi et al.
(s, 2H, NH2), 7.46-7.56 (m, 5H, CHAr), 8.48 (s, 2H, NH2) ppm; 13C NMR (100MHz,
DMSO-d6): d 74.3, 86.2, 115.5, 1116.4, 127.8, 128.4, 130.2, 134.5, 156.6, 159.2,
159.5 ppm. MS (EI) (m/z): 251.
Anal. Calcd. for C13H9N5O: C, 62.15; H, 3.61; N, 27.87. Found: C, 62.09; H, 3.54;
N, 27.78.
7-Methyl-5-oxo-1H-4,5-dihydro-2-methyl[1,2,4]triazolo[2,3-a]pyridine-6,8-
dicarbonitrile (6a)
White solid, mp 262-264 ꢁC, IR (KBr,): ꢀmax 3205 (NH), 2215 (CN), 1698 (C¼O),
1
1625 (C¼C) cmꢂ1, H NMR (400 MHz, DMSO-d6): d 1.84 (s, 3H, CH3), 2.04 (s, 3H,
CH3), 3.55 (s, 1H, NH), ppm; 13C NMR (100MHz, DMSO-d6): d 14.3, 24.2, 74.4,
86.5, 115.8, 115.9, 146.4, 156.7, 159.5, 160.1 ppm.
Anal. Calcd. for C10H7N5O: C, 56.34; H, 3.31; N, 32.85. Found: C, 56.28; H, 3.25;
N, 32.78.
7-(4-Chlorophenyl)-5-oxo-1H-4,5-dihydro-2-methyl[1,2,4]triazolo[2,3-a]pyridine-6,8-
dicarbonitrile (6b)
White solid, mp 282-285 ꢁC, IR (KBr,): ꢀmax 3207 (NH), 2219 (CN), 1695 (C¼O),
1
1625 (C¼C) cmꢂ1, H NMR (400 MHz, DMSO-d6): d 2.02 (s, 3H, CH3), 3.54 (s, 1H,
NH), 7.30-8.20 (m, 4H, CHAr) ppm; 13C NMR (100 MHz, DMSO-d6): d 24.2, 75.8,
88.7, 115.7, 115.9, 127.8, 129.3, 131.5, 133.6, 147.5, 156.4, 159.8, 161.2 ppm.
Anal. Calcd. for C15H8ClN5O: C, 58.17; H, 2.60; N, 22.61; Found: C, 58.10; H,
2.53; N, 22.54.
7-(4-Methylphenyl)-5-oxo-1H-4,5-dihydro-2-methyl[1,2,4]triazolo[2,3-a]pyridine-6,8-
dicarbonitrile (6c)
White solid, mp 272-275 ꢁC, IR (KBr,): ꢀmax 3212 (NH), 2215(CN), 1690 (C¼O), 1623
1
(C¼C) cmꢂ1, H NMR (400 MHz, DMSO-d6): d 2.02 (s, 3H, CH3), 2.21 (s, 3H, CH3),
3.54 (s, 1H, NH), 7.30-8.20 (m, 4H, CHAr) ppm; 13C NMR (100 MHz, DMSO-d6): d
22.8, 24.4, 75.7, 88.5, 115.6, 115.8, 126.3, 129.6, 130.2, 135.3, 147.8, 155.9,
159.7, 161.5 ppm.
Anal. Calcd. for C16H11N5O: C, 66.43; H, 3.83; N, 24.21. Found: C, 66.38; H,
3.76; N, 24.15.
Acknowledgment
The authors are grateful to the University of Kashan for supporting this work.
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