Tetracyanoethene and 1-Amino-1,2,2-ethenetricarbonitrile in the Synthesis of Heterocycles of Prospective Antioxidant and Antibacterial

Article abstract of DOI:10.1002/jhet.2236

Reaction of 1,1,2,2-ethenetetracarbonitrile (TCNE) with aroyl thioureas in dioxane catalyzed by few drops of piperidine, led to the corresponding 1,2,4-oxathiazoles. Under the same reaction condition, thiosemicarbazide or thiosemicarbazone reacted with ei

Full text of DOI:10.1002/jhet.2236

May 2016
Tetracyanoethene and 1-Amino-1,2,2-ethenetricarbonitrile in the Synthesis
of Heterocycles of Prospective Antioxidant and Antibacterial
963
a
b
c
d
e
*
Ashraf A Aly, Tamer El Malah, Esam A. Ishak, Alan B. Brown, and Wael M. Elayat
aChemistry Department, Faculty of Science, Minia University, 61519 El-Minia, Egypt
bNational Research Centre, El Buhouth St., Dokki, Cairo, Egypt
cChemistry Department, Faculty of Science, Al-Azhar University, Assiut, Egypt
dChemistry Department, Florida Institute of Technology, Melbourne, FL 32901, USA
eChemistry Department, Faculty of Science, Aljouf University, Sakaka, Aljouf, Saudi Arabia
*
E-mail: ashrafaly63@yahoo.com
Received December 15, 2013
DOI 10.1002/jhet.2236
Published online 7 March 2016 in Wiley Online Library (wileyonlinelibrary.com).
Reaction of 1,1,2,2-ethenetetracarbonitrile (TCNE) with aroyl thioureas in dioxane catalyzed by few
drops of piperidine, led to the corresponding 1,2,4-oxathiazoles. Under the same reaction condition,
thiosemicarbazide or thiosemicarbazone reacted with either TCNE or 1-amino-1,2,2-ethenetricarbonitrile.
The structures of the products were elucidated via NMR, IR, mass spectra, and elemental analyses. The
mechanism of formation was discussed. Biological (against Gram-positive and Gram-negative bacteria)
and antioxidant activities were tested. Some of these heterocyclic compounds showed high activity as anti-
oxidant and antibacterial compounds. The structure–activity relationship was investigated.
J. Heterocyclic Chem., 53, 963 (2016).
INTRODUCTION
to form ethyl [1,2,4]triazolo[3,4-b][1,3]thiazine-5-carboxyl-
ates [5]. Thus, it appears that the reaction pathways of
substituted thioureas vary from one reagent to another.
Herein, we report the synthesis of various novel heterocycles
during the reaction of various N-naphthoyl-N′-aryl-thioureas
(1a–e) with 1,1,2,2-ethenetetracarbonitrile (TCNE, 2). The
naphthalene moiety was chosen because it is reported to
exhibit antifungal, antibacterial, and antitumor activities
[6,7]. We also report on one-pot reactions of other
hydrazino-carbothioamides with π-acceptors such as
TCNE and 1-aminoethenetricarbonitrile (AETC, 13). The
antioxidant and antibacterial biological activities of the
obtained products were investigated, and structure–activity
relationships (SAR) were discussed.
Thiourea moieties are important chemical building
blocks that have numerous chemical and pharmaceutical
applications. For example, recent reports describe thiourea
derivatives as efficient guanylating agents both in solution
and on solid support [1]. Hyrazinothioureas are another
class of thioureas such as 1-acylthiosemicarbazides,
which reacted with phenyl propiolate in acetic acid
under reflux to afford triazolothiazines [2]. Aly et al. [3] dem-
onstrated that the reaction between N-aroyl-N′-aryl-thioureas
and 2-(1,3-dioxoindan-2-ylidene)-malononitrile furnished
indeno[1,2-d]-[1,3]thiazepines, some of which showed
antitumor and antioxidant activities. One indenothiazepine
derivative showed a high inhibition of the cell growth of
Hep-G2 cells compared with the growth of untreated control
cells, as concluded from their low IC50 value of 21.73μM
[3]. It has been reported that 1,3-thiazines were obtained
from the reaction of N-aroyl-N′-substituted thioureas with
ethyl propiolate, dimethyl but-2-ynedioate, and (E)-1,4-
diphenyl-but-2-ene-1,4-dione [4]. Additionally, diethyl
maleate reacted with N-substituted-hydrazino-carbothioamides
RESULTS AND DISCUSSION
Chemistry. On adding one equivalent of TCNE (2) to
a solution of 1a–e in dioxane containing a few drops
of piperidine, the reaction proceeded under reflux for
10–16 h to give the corresponding products 3a–e and
1,1,2,2-tetracyanoethane (4, 20%; Scheme 1). The
© 2016 Wiley Periodicals, Inc.

964
A. A. Aly, T. E. Malah, E. A. Ishak, A. B. Brown, and W. M. Elayat
Vol 53
Scheme 1. Proposed mechanism of formation of oxathiazoles 3a–e.
Scheme 2. Proposed mechanism for formation of pyrazole 10.
structures of 3a–e were elucidated by 1H NMR, 13C NMR,
IR in addition to elemental analyses. The IR and 1H NMR
spectral data of 3a proved the absence of any NH groups or
any protons in heterocyclic ring. Additionally, the IR and
13C NMR spectral data indicated the absence of C═S and
C═O groups. The two C═N carbon signals appeared in
the 13C NMR at δ = 158.6 and 156.5, and the carbon
signal of Ar–C–OCH3 appeared at δ = 152.5. These
observations indicate that TCNE (2) behaved as an
oxidizing agent. The mechanism is proposed to involve
conjugate addition of the sulfur atom of compound 1 to
the strong electrophilic C═C bond of 2, followed by
cyclization and elimination of 1,1,2,2-tetracyanoethane
(4, Scheme 1). Tetracyanoethane (4), proposed as a by-
product, was in fact isolated.
Scheme 3. Reaction of thiosemicarbazone 12 with acceptor 13.
To show the reactivity of the thioamide group
thiosemicarbazide (7) (hydrazine-carbothioamide), we
reacted compound 7 with TCNE (2) under the same
reaction conditions mentioned earlier. The reaction gave
the corresponding pyrazole 10 via tricyanovinylation
product of 9 (82%; Scheme 2). The mechanism is proposed
to involve nucleophilic attack of the hydrazine-NH on the
electrophilic C═C of 7. Elimination of a molecule of HCN
from 8 followed by cyclization would give the pyrazole 10
(Scheme 2). Cyclization via attack of the thioamido-NH2
on a nitrile carbon, leading to the triazepine 11, was excluded
on the bases of proton integration with the relation (1:1). The
four protons in compound 10 appeared as two broad singlets
at δ = 10.4 and 6.6, assigned to the thiourea-NH2 and the
other free amino protons.
12 to the C-2 in 13, followed by cyclization and the
elimination of two HCN molecules to produce 15.
Under similar condition, the reaction of equimolar
quantities of N,N-dimethylthiourea (16) and 13 gave one
product assigned as 2-amino-2-imino-N,N-dimethylethane-
thioamide (19, Fig. 1). Mass spectra give a molecular weight
of m/z = 131, consistent with the formula C4H9N3S.
The formula requires two degrees of unsaturation (rings
or π bonds). The 13C NMR spectrum (Table 1) shows two
sp2 carbons, the chemical shifts of which is required belong
to two C═Z bonds (Z═heteroatom) as in 17 or 19, rather
than to one C═C bond plus a ring as in 18. There is no
vinylic H. The two methyl carbons give HMBC correlation
with each other’s attached protons, requiring that these
protons and carbons be near each other, most likely
within three bonds; and both methyl proton signals give
HMBC correlation with the same nitrogen, which does
not bear a proton.
Surprisingly, reaction of 2-(1-phenyl-ethylidene)
hydrazinecarbothio-amide (12) [8] with AETC (13)
afforded the corresponding 2-iminothiazole 15 (Scheme 3).
The structure of 15 is supported by NMR, IR, and mass
1
spectra in addition to elemental analysis. The H NMR
spectrum revealed a singlet at δ = 10.50, assigned to the
imino-NH; the other NH protons resonated in the region
of phenyl protons. In the 13C NMR spectrum, C-2
resonated at δ = 156.0. No C═S carbon signal appeared,
but two carbon signals at δ = 70.0 and 178.0 were assigned
to C-4 and C-5, respectively. The mechanism was based
upon nucleophilic addition of the lone pair of thione-S in
The simplest explanation is that the dimethylamino group
remains intact and the methyl groups being non-equivalent
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

May 2016
Tetracyanoethene and 1-Amino-1,2,2-ethenetricarbonitrile in the Synthesis
of Biologically Active Heterocycles
965
Figure 1. Various proposed structure of product of the formula C4H9N3S.
Table 1
NMR spectral data of product 19.
1H NMR (DMSO-d6)
H-H COSY
H-N HSQC
H–N HMBC
Assignment
9.91 (b; 1H)
8.00 (b; 1H)
7.52 (b; 1H)
1.92 (s; 3H)
1.91 (s; 3H)
8.00
9.91, 7.52
8.00
64
108
108
═NH
–NH2
–NH2
–NMe2
–NMe2
301
301
13C NMR (DMSO-d6)
178.36
151.63
25.01
H–C HSQC
H–C HMBC
9.91
9.91, 1.92, 1.91
1.91
Assignment
C═S
C═N
NMe2
NMe2
1.92
1.91
17.54
1.92
because of restricted rotation. Of the three N–H protons, two
give HSQC correlation with the same nitrogen and
presumably are attached to it, again being non-equivalent
because of restricted rotation; the third is on a different nitro-
gen. So, the structure consists of the following parts: –NMe2,
–NH2, –NH–, two ═C, and –S–. If the sp2 carbons are not
doubly bonded to each other, their double bonds must be to
the other divalent groups, that is, there must be C═S and
C═NH double bonds, and the two sp2 carbons must be sin-
gly bonded together as in structure 19. Here, the NH under-
going slower exchange is assigned as being involved in the
internal hydrogen bond (Fig. 2); and CHEMDRAW predicts
δ = 186 for C═S and 163.0 for C═N. Compound 19 is not
known, but several precedents support the observed
characteristics. Both thioamides and amidines are known to
exhibit restricted rotation about C–N bonds [9]. The mass
spectrum contains a fragment at m/z = 88, resulting from loss
of H2N–C═NH, confirming the regiochemistry; this
fragment would be unlikely if the NH2 and NMe2 groups
were interchanged. Therefore, the product was identified as
19. Mechanistically, compound 13 is described as an oxidiz-
ing agent, hence, it enhances dimerization and oxidation of
16 to form adduct 20 (Scheme 4). Rearrangement of interme-
diate 20 accompanied by transformation of amino group to
the adjacent carbon followed by elimination of [(CH3)
2N+H]SÀ would occur to give 19.
Antioxidant and antibacterial results. Antioxidant activity and
relation between structure and the antioxidant activity. The
thione group in the starting materials acts as an active
donating group (electron reducing agent), so that low
antioxidant activity was noted of the products compared
with L-ascorbic acid. In compounds 10 and 15, the amino
and the thione moieties increase the electron-donating
property and so increase the antioxidant activity (Table 2).
The same trend was observed for addition of serum
mixture, although absorbance of compounds in serum
(Table 3) is higher than in CUPRAC solution.
Antimicrobial activity and the SAR.
Because of the
broad spectrum of Ampiclox, we used it as an antibiotic
reference in both cases of Gram-positive chosen bacteria,
Gram-positive bacteria (Staphylococcus aureus), and
Gram-negative bacteria (Escherichia coli.) [10].
Structure–activity relationship describes the relationship
between the chemical or 3D structure of a molecule and
its biological activity. The analysis of SAR enables the
determination of the chemical groups responsible for evoking
a target biological effect in the organism. This allows
Scheme 4. Rationale for the formation of 19.
Figure 2. Proposed hydrogen bond in compound 19.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

966
A. A. Aly, T. E. Malah, E. A. Ishak, A. B. Brown, and W. M. Elayat
Vol 53
Table 2
Relation between concentration (mg/dl) and absorbance of compounds 3a–d, 10, 15 and L-ascorbic acid in CUPRAC solution.
Conc. (mg/dl)
Abs.
Ascorbic acid
3a
3b
3c
3d
10
15
100
10
1
0.4
0.3
0.06
0.03
0.41
0.14
0.091
0.054
0.62
0.29
0.15
0.06
0.49
0.31
0.21
0.06
0.46
0.31
0.24
0.09
0.65
0.26
0.19
0.08
0.79
0.48
0.41
0.09
0.1
Table 3
Relation between concentration (mg/dl) and absorbance of compounds 3a–d, 11, 15 and L-ascorbic acid in serum solution.
Conc. (mg/dl)
Abs.
Ascorbic acid
3a
3b
3c
3d
10
15
100
10
1
0.73
0.51
0.21
0.48
0.33
0.27
0.62
0.29
0.15
0.67
0.43
0.29
0.92
0.67
0.45
1.02
0.76
0.48
1.01
0.89
0.37
modification of the effect or the potency of a bioactive
compound (typically a drug) by changing its chemical
structure.
Table 4
Antimicrobial activity of 3a–d, 10, 15 and 19 against Gram-positive
bacteria (Staphylococcus aureus).
The type of the substitution on the naphthyl ring did not
affect the antimicrobial activity. However, the substitution
on the benzene ring is important. The presence of an elec-
tron-withdrawing group such as a chlorine atom at the para
position of the benzene ring (Ar′) in 3d increased the anti-
microbial activity. However, electron-donating groups
such as methoxy led to higher activity when in the para
position of Ar′ (e.g., 3b) than when in the ortho position
(3e). When Ar′ was an unsubstituted phenyl group (3c),
antimicrobial activity was higher than when electron-
donating substituents were present (Table 4).
Inhibition zone (mm)
Conc (mg/dl)
Methanol
100
10
1
0.1
Zero
Reference antibiotic
(Ampiclox)
4.1
Compounds
3a
3b
3c
3d
3e
10
15
19
5.2
5.4
5.9
6.1
4.7
4.8
5.6
8.2
1.6
2.0
2.5
2.0
1.8
1.3
2.1
4.8
0.9
1.1
1.9
1.0
1.3
1.0
1.5
2.6
0.6
0.7
1.0
0.9
0.7
0.5
0.6
1.5
• The antimicrobial screening of 3a–e led to the following
assumptions about the SAR against Gram-positive bacte-
ria represented by S. aureus (Table 4):
• Pyrazole-carbothiamido derivatives are known for their
biological activities [11]. In our case, the biological
activity of 10 is higher than in that of the reference
antibiotic (Fig. 3).
• Thiazoles are also known to have high biological activ-
ity. In our case, the biological activity of 15 is higher
than that of the reference antibiotic (Fig. 3).
• Thioureas are well known by their biological activities,
especially as antimicrobial agents [8]. Compound 19
showed high biological activity against Gram-positive
bacteria (S. Aureus), (Fig. 3).
The SAR of 3a–e against Gram-negative bacteria repre-
sented by E. coli (Table 5) can be summarized as follows:
• As mentioned before, the type of the substitution on the
naphthyl ring in Ar did not largely affect the antimicro-
bial activity, but the substitution on the benzene ring is
important. The presence of an electron-withdrawing
Figure 3. Order of antimicrobial activity of 3a–d, 10, 15 and 19 against
Gram-positive Staphylococcus Aureus.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

May 2016
Tetracyanoethene and 1-Amino-1,2,2-ethenetricarbonitrile in the Synthesis
of Biologically Active Heterocycles
967
Table 5
EXPERIMENTAL
Antimicrobial activity of selected compounds against Gram-negative
Chemistry. TLC was performed on analytical Merck 9385
silica aluminum sheets (Kieselgel 60) with PF254 indicator. TLCs
were viewed under ν = 254 nm. Melting points were determined
on a Stuart (Bibby Scientific Ltd., Stone, Staffordshire, UK)
electrothermal melting point apparatus and are uncorrected. IR
spectra were recorded as KBr disks on a Shimadzu-408 infrared
spectrophotometer (Shimadzu Corp., Kyoto, Japan), Faculty of
Science, El Minia University. NMR spectra were measured in
DMSO-d6, at 400 MHz for 1H and 100 MHz for 13C, using a
Bruker AV-400 spectrometer (Bruker BioSpin Corp., Billerica,
MA) at Florida Institute of Technology. Chemical shifts are
expressed as δ (ppm). Coupling constants are stated in Hz.
Electron impact (EI) mass spectra were recorded with a JEOL
JMS-600 spectrometer (JEOL Ltd., Tokyo, Japan) at an ionization
voltage of 70eV at the Central lab, Assiut University and the
Micro analytical center, Faculty of Science, Cairo University,
Cairo, Egypt. Thiosemicarbazone 12 was prepared according
to the literature [12]. All chemicals and solvents were bought
from Aldrich.
bacteria (E. coli).
Inhibition zone (mm)
Conc (mg/dl)
Methanol
100
10
1
0.1
Zero
Reference antibiotic
(Ampiclox)
4.1
Compounds
3a
3b
3c
3d
3e
10
15
19
3.2
3.4
3.0
4.6
2.9
4.2
4.4
5.2
1.2
1.3
1.5
2.0
1.0
1.8
1.9
2.2
0.5
0.6
0.4
0.8
0.3
1.6
1.7
2.0
0.04
0.06
0.03
0.08
0.02
0.06
0.07
0.14
General procedure.
General procedure of preparing
aroyl thioureas 1a-e.
Under dry conditions, the aroyl
chloride (30 mmoL) was added to a solution of (30 mmol,
2.28 g) NH4SCN in dried acetone (15 mL) with magnetic
stirring at room temperature over 10 min, after which a white
precipitate of NH4Cl appeared. Without filtration, 30 mmoL of
the appropriate aromatic amine in acetone (20 mL) was slowly
added at room temperature (30°C) with stirring. When the mixture
reached room temperature, it was refluxed for 10 min. After
cooling, the reaction mixture was poured slowly into 400-mL ice
water with strong stirring. Aroyl thioureas 1a–e were precipitated
as solids. The crude product was filtered off, dried, and
recrystallized from solvents then washed with cool diethyl ether.
Reaction of thioureas with 1,1,2,2-ethenetetracarbonitrile (2).
Figure 4. Order of antimicrobial activity of 3a–d, 10, 15 and 19 against
Gram-negative Escherichia coli.
General procedure.
To a stirred solution of 3 mmoL of
thioureas in nearly 100 mL of 1,4-dioxane together with two
drops of piperidine, a solution of 2 (0.384 g, 3 mmoL) was
added dropwise in 10 min. The reaction was then refluxed for
10–16 h and the precipitates formed were filtered off and
recrystallized. Then, 50 mL of n-hexane was added to the filtrate
and the precipitated formed was identified as tetracyanoethane
(4, mp 173°C, lit. [13] 170–175°C).
group such as a chlorine atom at the para position of the
benzene ring (Ar′) in 3d increased the antimicrobial
activity. The same trend was observed in the cases of
3b, 3c, and 3d (Fig. 4). The antibacterial activity of 3b
and 3c is lower than that of the reference antibiotic, but
in case of 3d, the antibiotic activity against the assigned
bacteria is higher than that of the reference antibiotic.
• As previously noted, the activity of compounds 19
against Gram-positive bacteria is high compared with
the reference antibiotic. Compound 19 has higher
activity against Gram-positive bacteria than against
Gram-negative bacteria.
4-Methoxy-N-(5-naphthalen-1-yl)-3H-1,2,4-oxathiazol-3-
ylidene)aniline (3a). Pale red crystals (EtOH), (0.75 g, 75%);
mp 224–226°C. IR: ν = 3090–3050 (w, Ar–CH), 2980–2875
(w, aliph.–CH), 1560 (s, C═C) cmÀ1 1H-NMR: δ = 3.95 (s,
.
3H, OCH3), 6.94 (dd, 2H, J = 8.0, 1.0 Hz, Ar–H), 7.60–7.80
(m, 4H, naphth–H), 7.90–8.20 (m, 3H, naphth–H), 8.50–8.54
(dd, 2H, J = 7.8, 1.0 Hz, Ar–H). 13C-NMR: δ = 158.6, 156.5
(C═N), 152.5 (Ph–C–OCH3), 142.6, 136.7 (naphth–C), 129.8
(naphth–2CH), 128.6 (Ar–2CH–o), 128.0, 127.8 (naphth–CH),
127.2 (naphth–C), 126.9 (naphth–2CH), 124.0 (Ar–C), 118.0
(naphth–CH–2), 116.8 (Ar–2CH–m), 57.8 (OCH3). Calcd. for
C19H14N2O2S (334.39): C, 68.24; H, 4.22; N, 8.38; S, 9.59.
Found: C, 68.00; H, 4.10; N, 8.50; S, 9.67%.
CONCLUSION
4-Methoxy-N-(5-naphthalen-2-yl)-3H-1,2,4-oxathiazol-3-
ylidene)aniline (3b). Pale red crystals (EtOH), (0.85g, 85%);
m.p. 287–288°C. IR: ν = 3080–3052 (w, Ar–CH), 2960–2870
In conclusion, the activities of all products 3a–e, 10, 15,
and 19 against Gram-positive bacteria (S. aureus) are
higher compared with their activities against Gram-negative
bacteria (E coli). Much work should been carried out to
discover more about the chemistry of AETC.
(w, aliph.–CH), 1562 (s, C═C) cmÀ1 1H-NMR: δ = 3.90 (s,
.
3H, OCH3), 6.90 (dd, 2H, J = 8.0, 1.0 Hz, Ar–H), 7.40–7.50
(m, 3H, naphtha–H), 7.62–7.72 (m, 3H, naphth–H), 7.80–7.84
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

968
A. A. Aly, T. E. Malah, E. A. Ishak, A. B. Brown, and W. M. Elayat
Vol 53
(dd, 2H, J = 8.0, 1.0 Hz, Ar–H), 8.10–8.15 (d, 1H, J = 1.2 Hz,
naphth–H). 13C-NMR: δ = 156.8, 156.0 (C═N), 153.0 (Ar–C–
OCH3), 145.0 (naphth–C–2), 135.6, 133.8 (naphth–C), 129.8
(Ar–2CH–m), 128.6 (naphth–2CH), 127.2 (naphth–CH), 126.9
(naphth–2CH), 124.0 (Ar–CH), 122.0 (naphth–CH), 119.0
(naphth–CH–1), 116.8 (Ar–2CH–o), 57.8 (OCH3). Calcd. for
C19H14N2O2S (334.39): C, 68.24; H, 4.22; N, 8.38; S, 9.59.
Found: C, 68.48; H, 4.10; N, 8.12; S, 9.70%.
Reaction of thiosemicarbazone 12 with AETC, 13. To a
stirred solution of thiosemicarbazone (12,0.179g, 1 mmol) in
nearly 30mL of 1,4-dioxane together with two drops of
piperidine, a solution of 13 (0.118 g, 1 mmoL) was added
dropwise in 30 min. The reaction was then refluxed for 4 h
and the precipitate formed was filtered off and recrystallized
from EtOH.
4-Amino-3-(benzylidene-amino)-2-imino-2,3-dihydrothiazole-
5-carbonitrile (15). Yellow crystals (methanol), yield (0.206 g,
85%), mp 182–184°C. IR: ν = 3340–3325 (NH2–NH, m), 2220
N-(5-Naphthalen-1-yl)-3H-1,2,4-oxathiazol-3-ylidene)aniline
(3c).
Brown crystals (EtOH), (0.64 g, 70%); mp 260–262°C.
IR: ν = 3060–3040 (w, Ar–CH), 1560 (s, C═C) cmÀ1. H-NMR:
δ = 6.86–6.90 (dd, 2H, J = 8.0, 1.0 Hz, Ph–H–o), 7.10–7.14 (m,
1H, Ph–p), 7.36–7.40 (dd, 2H, J = 8.0, 1.0 Hz, Ph–m), 7.60–7.64
(m, 2H, naphth–H), 8.10–8.30 (m, 4H, naphth–H), 8.25–8.27 (d,
1H, J = 8.0, 1.0 Hz, naphth–H–1). 13C-NMR: δ = 160.0, 158.2
(C═N), 145.0 (Ph–C), 135.4, 134.0 (naphth–C), 131.0 (Ph–2CH–
m), 128.3 (naphth–C), 128.0 (naphth–2CH), 127.8 (naphth–CH),
126.6 (Ph–CH–p), 126.4 (naphth–2CH), 122.6 (naphth–CH),
119.2 (naphth–CH), 122.8 (Ph–2CH–o). Calcd. for C18H12N2OS
(304.07): C, 71.03; H, 3.97; N, 9.20; S, 10.54. Found: C, 70.88;
H, 4.10; N, 9.10; S, 10.50%.
(CN, s), 1600 (C═N, s), 1560 (C═C, m) cmÀ1 1H-NMR:
.
1
δ = 10.50 (br, s, 1H, NH), 8.20 (s, 1H, CH═N), 7.10–6.80
(m, 7H, Ph–H, NH2). 13C-NMR: δ = 178.0 (C-5), 156.0
(C═NH), 154.0 (CH═N), 132.0 (Ph–C), 128.0 (Ph–2CH–o),
127.2 (Ph–2CH–m), 126.0 (Ph–CH–p), 116.0 (CN), 78.0
(C-4). Calcd. for C11H9N5S: C, 54.31; H, 3.73; N, 28.79. Found:
C, 54.44; H, 3.78; N, 28.66%.
Reaction of 1,1-dimethylthiourea (16) with AETC, 13. To
a stirred solution of 16 (0.104 g, 1 mmol) in nearly 20 mL of 1,4-
dioxane together with two drops of piperidine, a solution of 13
(0.118 g, 1 mmoL) was added dropwise in 30 min. The reaction
was then refluxed for 10 h. The reaction was cooled and the
precipitate was extracted with CHCl3. The solvent was
evaporated in vacuum and formed; the precipitate was filtered
off and recrystallized from CHCl3/EtOH.
4-Chloro-N-(5-naphthalen-1-yl)-3H-1,2,4-oxathiazol-3-ylidene)
aniline (3d). Pale red crystals (CHCl3/MeOH), (0.70 g, 69%); mp
200–202°C. IR: ν = 3068–3050 (w, Ar–CH), 1565 (s, C═C).
1H-NMR: δ = 6.92–6.95 (dd, 2H, J = 7.8, 1.0 Hz, Ph–o),
7.40–7.44 (dd, 2H, J = 8.0, 1.0 Hz, Ph–m), 7.58–7.62 (m,
2H, naphth–H), 8.08–8.22 (m, 4H, naphth–H), 8.40–8.43
(dd, 1H, J = 7.8, 1.0 Hz naphth–CH–1). 13C-NMR: δ = 160.4,
158.6 (C═N), 145.8 (Ph–C), 136.0, 134.8 (naphth–C), 132.0
(Ph–C–Cl), 130.4 (Ph–2CH–m), 128.2 (naphth–C), 128.0
(naphth–CH), 127.8 (naphth–2CH), 127.6 (naphth–CH),
126.6 (naphth–2CH), 122.4 (naphth–CH), 122.8 (Ph–2CH–o), 119.4
(naphth–CH–1). Calcd. for C18H11ClN2OS (338.81): C, 63.81; H,
3.27; N, 8.27; S, 9.46. Found: C, 63.70; H, 3.15; N, 8.20; S, 9.40%.
2-Methoxy-N-(5-naphthalen-1-yl)-3H-1,2,4-oxathiazol-3-ylidene)
aniline (3e). Pale red crystals (ethyl acetate), (0.75 g, 75%); mp
140–142°C. IR: ν = 3090–3050 (w, Ar–CH), 2950–2840
2-Amino-2-imino-N,N-dimethylethanethioamide (19). Brown
crystals (CHCl3/EtOH), yield (0.112 g, 85%), mp 260–262°C. IR:
ν = 3320–3250 (NH2–NH, m), 1600 (C═N, s) cmÀ1
.
1H-
NMR: Table 1. 13C-NMR: Table 1. MS (EI) 131 (100), 116
(67), 97 (12), 89 (10). Calcd. for C4H9N3S: C, 36.62; H,
6.91; N, 32.03. Found: C, 54.44; H, 6.80; N, 31.88%.
Material and methods for antioxidant activity [14]. The
antioxidant activity of each organic compound was measured
alone.
Preparation of CUPRAC assay solution.
CuCl2 solution,
1.0 × 10À2 M was prepared by dissolving 0.426 g CuCl2.2H2O
in water and diluting to 0.250 mL. Ammonium acetate buffer at
pH 7, 1.0 M, was prepared by dissolving 19.27 g NH4AC in
water and diluting to 250 mL. Neocuproine (Nc) solution,
7.5 × 10À3 M, was prepared by dissolving 0.039 g Nc in 96%
ethanol and diluting to 25 mL with ethanol.
(w, aliph.–CH), 1560 (s, C═C) cmÀ1 1H-NMR: δ = 3.92
.
(s, 3H, OCH3), 6.70–6.73 (dd, 1H, J = 7.8, 1.0 Hz|, Ph–H),
7.00–7.30 (m, 3H, Ph–H), 7.40–7.60 (m, 4H, naphth–H), 8.10–8.22
(m, 2H, naphth–H), 8.40–8.43 (dd, 1H, J= 7.8, 1.0 Hz, naphth–H).
13C-NMR: δ = 160.0, 158.0 (C═N), 153.2 (Ph–C–OCH3), 136.2,
135.0 (naphth–C), 134.2 (Ph–C), 130.2 (Ph–CH), 128.4
(naphth–2CH), 128.2 (Ph–CH), 128.0 (naphth–C), 127.0 (Ph–CH),
127.4 (naphth–2CH), 127.0, 125.8, 122.4 (naphth–CH), 120.2
(Ph–CH), 55.0 (OCH3). Calcd. for C19H14N2O2S (334.39):
C, 68.24; H, 4.22; N, 8.38; S, 9.59. Found: C, 68.36; H, 4.30;
N, 8.24; S, 9.40%.
Preparation of standard solution of ascorbic acid
antioxidant. The standard solution of ascorbic acid antioxidant
was prepared at 1.0 × 10À3 M concentration by dissolving ascorbic
acid in water.
Serum extraction and preparation for total antioxidant
CUPRAC assay. Freshly collected serum samples were kept
at +4°C until just prior to analysis. About 1 mL of serum was
transferred to centrifuge tube, 2 mL of 96% ethanol, and 1 mL
of distilled water were added and mixed well. About 4 mL
of n-hexane were added to the mixture and mixed again, and
the final mixture was allowed to stand for a few minutes for
separation of the phases. The solution was separated using
centrifuging technique at 1500 g (5000 rpm) for 5 min. The
upper organic phase was separated and transferred to a dark
tube. The hexane extraction procedure was repeated and the
second hexane extracted was separated and then transferred to
the original dark tube so as to combine with the first extract.
The combined hexane extracts were dried under N2 flow, and
the residue was taken up in 1 mL of dichloromethane for assay
of trichloroacetic acid (TCA)-Protein method.
Reaction of thiosemicarbazide 7 with 2.
To a stirred
solution of thiosemicarbazide (7, 0.273 g, 3 mmol) in 50 mL of
1,4-dioxane together with two drops of piperidine, a solution of
2 (0.384 g, 3 mmoL) was added dropwise in 10 min. The
reaction was then refluxed for 6 h and the precipitate formed
was filtered off and recrystallized from EtOH.
Dicyano-5-imino-2,5-dihydro-1H-pyrazole-1-carbothioamide
(10). Red crystals (0.48 g, 82%); mp 134–136°C. IR: ν = 3360–
3300 (m, NH2, NH), 2220 (s, CN), 1560 (s, C═C) cmÀ1
.
1H-NMR: δ = 10.4 (s, 2H, NH–thioamido), 6.6 (s, 2H, NH2).
13C-NMR: δ = 178.6 (C═S), 156.2 (C═N, C-5), 134.8 (C-3),
111.2, 113.6 (CN), 78.6 (C-4). Calcd. for C6H4N6S: C,
37.49; H, 2.10; N, 43.73; S, 16.68. Found: C, 37.30; H,
2.08; N, 43.90; S, 16.60%.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

May 2016
Tetracyanoethene and 1-Amino-1,2,2-ethenetricarbonitrile in the Synthesis
of Biologically Active Heterocycles
969
REFERENCES AND NOTES
Preparation of different organic material.
The different
organic materials were dissolved in 96% ethanol, and serial
concentrations were prepared.
Standard CUPRAC antioxidant capacity assay applied to
[1] Katritzky, A. R.; Rogovoy, B. V. ARKIVOC 2005, iv, 49.
http://www.arkat-usa.org/get-file/19522/
[2] Aly, A. A.; Brown, A. B.; Abdel-Aziz, M.; Abuo-Rahma,
G. A. A.; Radwan, M. F.; Ramadan, M.; Gamal-Eldeen, A. M.
J Heterocycl Chem 2012, 49, 726.
[3] Aly, A. A.; Brown, A. B.; Abdel-Aziz, M.; Abuo-Rahma,
G. A. A.; Radwan, M. F.; Ramadan, M.; Gamal-Eldeen, A. M.
J Heterocycl Chem 2010, 47, 503.
[4] Aly, A. A.; Ahmed, E. K.; El-Mokadam, K. M. J Heterocycl
Chem 2007, 44, 1431.
serum extract with standard addition.
To a test tube, 1 mL
of copper(II) chloride solution, 1 mL of neocuproine solution,
and 1 mL of NH4Ac buffer solution were added in that order.
An aliquot (1.5 mL) of serum extract was added to this tube.
Ascorbic acid standard and the organic material to be tested
were added to this extract. Absorbance readings were made
against reagent blank at 450 nm.
[5] Aly, A. A.; Hassan, A. A.; Ibrahim, Y. R.; Abdel-Aziz, M.
J Heterocycl Chem 2009, 46, 687.
Antimicrobial activity assay.
The different organic
[6] Upadhayaya, R. S.; Vandavasi, J. K.; Kardile, R. A. S.;
Lahore, S. V.; Dixit, S. S.; Deokar, H. S.; Shinde, P. D.; Sarmah, M. P.;
Chattopadhyaya, J. Eur J Med Chem 2010, 45, 1854.
[7] Milelli, A.; Tumiatti, V.; Micco, M.; Rosini, M.; Zuccari, G.;
Raffaghello, L.; Bianchi, G.; Pistoia, V.; Fernando Diaz, J.; Pera, B.;
Trigili, C.; Barasoain, I.; Musetti, C.; Toniolo, M.; Sissi, C.; Alcaro, S.;
Moraca, F.; Zini, M.; Stefanelli, C.; Minarini, A. Eur J Med Chem
2012, 57, 417.
[8] (a) Chauhana, A.; Sharmaa, P. K.; Kaushika, N.; Kumara, N. Int J
Pharm and Pharmaceutical Sci 2011, 3, 461; (b) Limban, C.; Missir, A. V.;
Chirita, I. C. Rev Chim (Bucharest) 2011, 62, 685; (c) Semenov, V. E.;
Mikhailov, A. S.; Voloshina, A. D.; Kulik, N. V.; Nikitashina, A. D.;
Zobov, V. V.; Kharlamov, S. V.; Latypov, S. K.; Reznik,V. S. Eur J
Med Chem 2011, 46, 4715.
materials were assessed for their antimicrobial activities by
culturing E. coli on nutrient agar for 24 h and then subculture
these Gram-negative bacteria with different concentration of the
organic material and with 96% ethanol alone for 24h. The zone of
inhibition with each organic compound was measured and
compared with the zone of inhibition caused by ethanol alone. By
varying the concentration of the different organic compounds, we
calculate minimal inhibitory concentration of such compounds.
CONCLUSION
In conclusion, we have synthesized a new series of
S-heterocycles in good yields using a convenient set of
synthetic conditions. The chemistry of 1-amino-1,2,2-
ethenetricarbonitrile is under further investigation. The
sulfur heterocycles described herein are promising pro-
spective antioxidant and antibacterial drugs.
[9] Jackman, L. M. Dyn Nucl Magn Reson Spectrosc 1975,
203. CAN 83:77850
[10] Abdullahi M.; Saleh M.; Ibrahim H. M.; Halima, I. M.;
Safiyya A., Mani M. A. International J Sci and Tech 2013, 3, 300.
ISSN 2224–357
[11] Desai, N. C.; Joshi, V. V.; Rajpara, K. M.; Vaghani, H. V.;
Satodiya, H. M. J Fluorine Chem 2012, 142, 67.
[12] Tenorio, R. P.; Carvalho, C. S.; Pessanha, C. S.; de Lima, J. G.;
de Faria, A. R.; Alves, A. J. de Melo, A. J. T.; Goès, A. J. S. Bioorg Med
Chem Lett 2005, 15, 2575.
[13] Zolotoi, A. B.; Konovalikhin, S. V.; Lukin, P. M.; D’yachenko,
O. A.; Zil’berg, S. P.; Nasakin, O. E. Chem Heterocycl Compds 1988,
24, 1166.
Acknowledgments. The authors express their gratitude to Aljouf
University, KSA, for the research funds and its support of this
investigation. The NMR spectrometer at Florida Institute of
Technology was acquired with the assistance of the National
Science Foundation (CHE 03–42251).
[14] Apak, R.; Gü lü, K.; Özyünek, M.; Bektaşoğlu, B.; Bener, M.
Methods Mol Biol (Totowa, N J) 2010, 594, 215.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet