Oxoketene Dithiols: Synthesis of Some Heterocycles as Antimicrobials Utilizing Shrimp Chitin as a Natural Catalyst

Article abstract of DOI:10.1080/10426507.2014.887075

1, 2-dithiol 3-thione derivatives, as starting materials, were subjected to cycloaddition reactions in the presence of the dried outer shell of shrimp (chitin), under different reaction conditions to produce the 1, 3-dithiole-2-ylidene system. On treating 4-bromo dithiol 3-one, with dimethyl ester of acetylene dicarboxylic acid the bromo oxothiafulvene was produced. Further addition of DMAD to bromotrithiafulvene afforded the spiro bromo derivative. Trithiones and trithiafulvenes were also added to quinones, cyclohexadiene and cyclopentadiene monomer, and the corresponding adducts were produced through 1,3-dipole cycloaddition reactions. On testing some of the products against the isolated micro-organisms from sugar cane factory, the inhibition zones at concentration 1 × 10^-6 were found. Products (2, 6, 9, 16, 23, 25, and 26) showed high activities against Bacillus sub., E.Coli and Asper. Niger.

Full text of DOI:10.1080/10426507.2014.887075

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Phosphorus, Sulfur, and Silicon and the
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Oxoketene Dithiols: Synthesis of Some
Heterocycles as Antimicrobials Utilizing
Shrimp Chitin as a Natural Catalyst
Salem E. Zayeda, Awatef M. El-Maghrabya & Entesar A. Hassana
a Chemistry Department, Faculty of Science, South Valley University,
Qena, 83523, Egypt
Accepted author version posted online: 30 Apr 2014.Published
online: 29 Sep 2014.
To cite this article: Salem E. Zayed, Awatef M. El-Maghraby & Entesar A. Hassan (2014):
Oxoketene Dithiols: Synthesis of Some Heterocycles as Antimicrobials Utilizing Shrimp
Chitin as a Natural Catalyst, Phosphorus, Sulfur, and Silicon and the Related Elements, DOI:
10.1080/10426507.2014.887075
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Phosphorus, Sulfur, and Silicon, 189:1–17, 2014
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426507.2014.887075
OXOKETENE DITHIOLS: SYNTHESIS OF SOME
HETEROCYCLES AS ANTIMICROBIALS UTILIZING
SHRIMP CHITIN AS A NATURAL CATALYST
Salem E. Zayed, Awatef M. El-Maghraby,
and Entesar A. Hassan
Chemistry Department, Faculty of Science, South Valley University, Qena 83523,
Egypt
GRAPHICAL ABSTRACT
Abstract 1, 2-dithiol 3-thione derivatives, as starting materials, were subjected to cycload-
dition reactions in the presence of the dried outer shell of shrimp (chitin), under different
reaction conditions to produce the 1, 3-dithiole-2-ylidene system. On treating 4-bromo dithiol
3-one, with dimethyl ester of acetylene dicarboxylic acid the bromo oxothiafulvene was pro-
duced. Further addition of DMAD to bromotrithiafulvene afforded the spiro bromo derivative.
Trithiones and trithiafulvenes were also added to quinones, cyclohexadiene and cyclopenta-
diene monomer, and the corresponding adducts were produced through 1,3-dipole cycload-
dition reactions. On testing some of the products against the isolated micro-organisms from
sugar cane factory, the inhibition zones at concentration 1 × 10−6 were found. Products (2,
6, 9, 16, 23, 25, and 26) showed high activities against Bacillus sub., E.Coli and Asper.
Niger.
Keywords Gem-dithioacetals; thiafulvenes; trithiafulvenes; ketoketene dithioles; antimicrobs
Received 22 November 2012; accepted 21 January 2014.
Address correspondence to Awatef M. El-Maghraby, Chemistry Department, Faculty of Science, South
Valley University, Qena 83523, Egypt. E-mail: awatef elmaghraby@yahoo.com
1

2
S. E. ZAYED ET AL.
INTRODUCTION
The keto ketene dithioacetals are useful three-carbon synthons and are extensively
employed for the synthesis of a wide variety of heterocyclic compounds and also in several
ring annulation reactions. They were considered versatile reagents for the synthesis of some
sulfur heterocycles. Over the past three decades, thiafulvalenes and their derivatives have
received attention because of their electroconductivity and superconducting properties.1–7
An important condition for photoconduction is the transport of the charge carriers within the
bulk of the polymer film toward the chemical contacts without capture or recombination.8
Generally, the photoconductivity of the polymer film is provided by the presence of three
types of molecules; donors, acceptors, and photogeneration centers of charge carriers.8 The
conductivity properties are attributed to the π-electron donor of sulfur.9 Tri and tetrathi-
afulvenes (TTF)7,10 still remain one of the most studied systems in the field of materials
because of their ability to conduct electricity (super) conducting cation radical salts of
charge transfer complex.11
A number of electron donors, e.g. thiafulvenes and thiafulvalenes, have been in-
tensively developed during the last two decades because of their potential applications
in materials science,9,11 e.g. molecular magnet, nonlinear optics, molecular superconduc-
tor, and redoxactive molecular sensor. Organic superconductors are considered a part of
the organic conductor family, which includes molecular salts, polymers, and pure carbon
nanotubes.12
Thiafulvenes have become a subject of great interest for electrochemical studies.13
Chemical modifications of TTFs from work have been added to improve their electrical
conductance properties.14,15
Molecular geometry, electronic structure, effect of the substitution, and structure
physical-chemical property relationship for 1,2-dithiole-3-thione derivatives have been
studied by molecular mechanics and other physical methods. The calculated values, namely
net charges, bond lengths, dipole moments, electron-affinities, and heats of formation
properties are reported and discussed in terms of the biological activity of 1,2-dithiole-3-
thione derivatives.16
RESULTS AND DISCUSSION
The prepared and synthesized compounds were examined to stop or at least delay
the growth of the harmful micro-organisms that infect sugar industry and cause damage to
sucrose molecules and great loss in sugar production. Sulfurization of 1 and/or 217–21 with
phosphorous pentasulfide generated the 1, 2-dithiol 3-thione derivatives (3,4).22 The full
analysis of the prepared products (1–4) was found to support the postulated structure.22
The reactions of 3–5 with acetylene dimethyl ester in organic solvents are well known in
the current literatures.23–27
To our knowledge, such reactions in water/sunlight in the presence of chitin∗ are not
reported. 1, 2-dithiol 3-thione derivatives (3) and (4)22 were reacted with dimethyl ester of
acetylene dicarboxylic (DMAD) acid in boiling xylene or in methylene chloride23–27 and
also in different reaction conditions and in different molar ratios.
∗Chitin, the ubiquitous natural polysaccharide, [D-glucopyranose (2-acetamido-2-
deoxy-D-glucose1N-acetylglucosamine)] is a base catalyst extract from fungi and the outer
cortex of orthopoda, e.g. shrimp).28

OXOKETENE DITHIOLS
3
Scheme 1
Reaction of (3) or (4) with DMAD proceeded in an equimolar ratio in H2O as a
solvent and in sunlight∗∗ for 3 days and realized by the 1,3-dipolar cycloaddition reactions,
as well as when the same reaction was proceeded in methylene chloride, either at room
temperature or gentle boiling on a water bath; or in water and chitin as a catalyst,29–37 the
products (5) and (6) were separated respectively. (In the present work we used the dried
outer shell of shrimp.)
∗∗At Qena (in summer) the temperature range is 44–48◦C.
Scheme 1:
Processing reactions in H2O and in sunlight gave the highest yield and pure products
(83% and 88% respectively). Reaction under the effect of sunlight in water as a solvent is
proceeded either thermally or sun ultraviolet waves, we suggest that both factors facilitate
the reaction proceeding.
On reacting different molar ratios from DMAD acid (two molar ratios) with (3) or
(4) (1 mol) in boiling xylene, the spiroproduct (7) was produced in a satisfactory yield
(72%). It is noticed that the reactions in H2O/sunlight or in chitin/water conditions gave
the highest yield and pure product (7). The suggested mechanism is the reaction proceeded
via Diels–Alder (2+4) cycloaddition reaction38–40 while the acetylene molar ratio (3 mols)
with 1 mol from (3) and/or (4) gave the same product (7).
Scheme 2:
On the other hand, reactions of 1,2-dithiole 3-thione (3) or (4) with acetylene dimethyl
ester in 1:2 or 1:3 molar ratio afforded the same product (7).
It is postulated that the reaction was proceeded through two steps: the first is the
1:3 dipolar cycloaddition reaction and the second is the Diels–Alder (2+4) cycloaddition
reaction.38–40

4
S. E. ZAYED ET AL.
COOMe
COOMe
S
S
S
S
5
MeOOC
COOMe
H2O/sunlight or
chitosan/boiling
(1:1) TTF:DMAD
boiling xylene
(1:2) TTF:DMAD
boiling xylene
(1:3) TTF:DMAD
boiling xylene
MeOOC
S
COOMe
S
COOMe
COOMe
S
7
S
S
1:3- molar ratio
S
S
S
3
H3COOC
COOCH3
Scheme 2
Subsequently, oxidation of trithione (3)17 with potassium permanganate in acetone
yielded the 1,2-dithiol 3-one derivative (8)17 in a satisfactory yield (59%). Bromination of
(8) in chloroform afforded the 4-bromo1,2-dithiol 3-thione derivative (9) in a satisfactory
yield.17
Br
S
KMnO4
acetone
S
S
Br2/CHCl3
S
S
S
S
O
X
O
S
3
S
8
S
9
S
S
O
S
8 X= H
9 X= Br
CH3OOC COOCH3
xylene, reflux
CH3OOC COOCH3
xylene, reflux
COOMe
COOMe
COOMe
H
Br
S
S
S
S
O
O
COOMe
S
S
10
11
Scheme 3

OXOKETENE DITHIOLS
5
S
S
COOMe
COOMe
S
Br2
CHCl3
S
5
Br
S
S
COOMe
COOMe
xylene
boiling
S
S
12
COOMe
S
S
S
MeOOC
MeOOC
COOMe
COOMe
S
COOMe
COOMe
S
S
MeOOC
14
S
S
Br
S
COOMe
EtOH/Na
S
COOMe
13
S
MeOOC
MeOOC
S
COOMe
S
S
S
S
COOMe
15
Scheme 4
Cycloaddition reactions of 1,2-dithiol-3-one derivatives (8 or 9) with acetylene
dimethyl ester in boiling xylene passed through 1, 3-dipole cycloaddition reaction38–40
and obtained trithiafulvene (10) and bromo oxothiafulvene (11) respectively.
Scheme 3:
Bromotrithiafulvene (12) could also be prepared via bromination of trithiafulvene (5)
in chloroform, the bromo derivative (12) obtained in excellent yield. Furthermore, treating
(12) with acetylene dimethyl ester gave the spiroproduct (13). Dimerization of (5) via
boiling in xylene for 2 h afforded the tetrathiafulvalene derivative (14). Reduction of the
adduct (14) by sodium metal in ethanol gave the adduct (15).
Scheme 4:
S
+
S
S
S
S
S
COOMe
COOMe
- 2S
14
S
S
5
S
S
S
S
Scheme 5

6
S. E. ZAYED ET AL.
S
S
S
S
NH2
DMF
S
O
CNCH2CSNH2
COOMe
S
+
S
CN
S
8
16
COOMe
COOMe
S
H2O2
S
S
S
S
excess
COOMe
S
SO2
17
5
Scheme 6
Structure (5) was proven to be a δ-cis conformation due to S . . . . . . .S 1, 5 in 1,5
interaction.
Scheme 5:
Furthermore, reaction of 1,2-dithiole-3-one derivative (8) with cyano thioacetamide
in boiling dimethylformamide produced (16) via condensation of keto group in (8) with the
methylene group in cyano thioacetamide.
Scheme 6:
On oxidation of trithiafulvene (5) with excess hydrogen peroxide at room temperature,
the sulfone derivative (17) was produced.
A trial to investigate the reactivity of (5) towards malononitrile in two different
reaction conditions was successful. Mono and di-molar ratios from malononitrile were
allowed to react with trithiafulvene (5) in boiling dimethylformamide which was successful,
obtaining two different products (18) and (18a) respectively.
Scheme 7:
Addition of 1,2-dithiole-3-thione derivatives (3) or (4) to quinones was studied, and
found to pass through 1,3-dipole cycloaddition reactions and the products (19–26) were
obtained.
Scheme 8:
COOMe
COOMe
S
S
S
CH2(CN)2
1 : 2 mol
DMF
CH2(CN)2
1:1 mol
DMF
S
5
- H2S
- H2S
COOMe
COOMe
COOMe
COOMe
S
S
S
S
S
S
NH2
CN
,
NC
NC
NC
18
CN
Scheme 7

OXOKETENE DITHIOLS
7
O
S
X
S
S
O
25, X = S
26, X= O
1:2 mol
1:1 mol
O
xylene
reflux
O
1:1 mol
1:1 mol
O
O
O
Cl
Cl
O
O
O
Cl
Cl
S
S
O
X
23, X = S
24, X = O
S
S
S
S
X
S
xylene
reflux
xylene
reflux
S
O
S
3, X= S
4, X= O
19, X = S
20, X = O
X
1:2 mol
1:2 mol
O
S
S
X
S
- Cl2
O
21, X = S
22, X = O
Scheme 8
2,3-dichloronaphthoquinone adds as a dienophile to the sulfur atoms located at positions 1
and 3 followed by ring opening and finally due to steric effect, the two chlorine atoms were
eliminated. The first step may be formation of the intermediates (19, 20), then losing two
chlorine atoms from (21) and (22).
Structures (21, 22) were confirmed by performing the chemical test for chlorine
(AgNO3) as a preliminary test and it was negative.
Furthermore, dienophiles, e.g. cyclopentadiene (27) and cyclohexadiene (28), were
reacted with (3) in boiling xylene and the dipole cycloaddition reactions were furnished, as
a result of which products (29) and (30) were obtained respectively.
S
S
S
S
xylene
boiling
xylene
boiling
3
28
27
S
S
S
S
S
S
S
S
30
29
Scheme 9

8
S. E. ZAYED ET AL.
S
S
COOCH3
COOCH3
S
S
5
COOCH3
O
O
O
COOCH3
S
H3COOC
S
COOCH3
COOCH3
O
H3COOC
27
S
S
S
S
32
O
COOCH3
H3COOC
S
S
O
33
S
S
S
S
31
Scheme 10
Meanwhile, a trial to react dithiol-3-thione derivative (3) with dienophiles (27) or
(28) in water or in water/chitosan mixture failed, and the only product was the starting
materials.
Scheme 9:
Reactions of dienophiles cyclopentadiene (27), methylacrylate, and maleic anhydride
with trithiafulvene (5) in boiling xylene were postulated to behave as Diels–Alder (2+4)
cycloaddition reactions and gave the spiro thiopyrane derivatives (31–33).
Scheme 10:
The behavior of trithiafulvene(5) towards someamines was alsostudied. Cyanoguani-
dine reacts with (5) in two different molar ratios in ethanol in the presence of few drops of
triethylamine. The reaction products either on using equimolar or 2 mols from the amine
were found identical and the only product is (34). Detection of hydrogen sulfide and col-
oring the wetted paper with lead acetate indicates the reaction of amino group with thione
group.
On reacting amino guanidine sulfate with trithiafulvene (5) in dimethylformamide in
the presence of triethylamine in a catalytic quantity yielded (35).
Trithiafulvene (5) when boiled with ammonium hydroxide (28%) for 20 h afforded
the diamide derivatives (36).
The disappearance of a signal characteristic for ester groups indicates the structure
of (36). The appearance of an amidic peak in the IR spectrum also supported the hydrolysis
of the two ester groups.
Scheme 11:

OXOKETENE DITHIOLS
9
COOMe
S
S
S
CO
NH
NH
N
NH
NH
H2N
H2N NH
35
1:2 mol
(NH2 NH(C=NH) NH2)2 H2SO4
1:1 mol
DMF/Et3N
1:1 mol
1:2 mol
NH
COOMe
S
S
NCNHCNH2
EtOH/Et3N
COOMe
S
S
S
CO
NH
N
S
COOMe
NH
HN
S
NH
CN
NH
5
NC
34
Boiling NH4OH
CONH2
CONH2
S
S
S
S
36
Scheme 11
MATERIALS AND METHODS
The Antimicrobial Results
The biological comparison studies of the tested compounds against the separated
micro-organisms from sugar cane factory in Nag-Hammady, Qena, Egypt; shows that on
testing some of the products against the isolated micro-organisms, the inhibition zones at
concentration 1 × 10−6 were sound. Products (2, 6, 9, 16, 23, 25, and 26) showed high
activities against Bacillus sub., E.Coli and Asper.Niger.
Compound (26) is more effective than (6) and (16) for all isolated micro-organisms,
indicating high effect of quinone moiety, while the higher effectiveness of compound (2)
than (23), (25) and (9) may be due to the presence of thioles group present in this compound
(supplementary data).
Experimental
Instruments. The elemental analysis was carried out at the Microanalytical unit,
Cairo University; mass spectra was obtained on a GCMC-QP 1000 EX mass spectrometer
with ionization potential of 70 eV and a mass spectrometer MS 30 MS9 (AEI) at 70 eV;
IR spectra was determined with Shimadzu IR 408 infrared spectrophotometer using KBr
1
wafer technique. H-NMR was carried out on varian EM 390 (300 MHz) using TMS as
internal standard and chemical shifts are expressed as δ. Melting points are all uncorrected
and were determined either on sulfuric acid apparatus or on Kofler melting point apparatus.
Synthesis of Dithiols (1) and (2).
General procedure. Carbon disulfide (0.60 mL, 0.01 mol) was added to 0.01 mol
ace-tylthiophene or acetylfuran in dry benzene (150 mL) and the mixture was cooled

10
S. E. ZAYED ET AL.
to 0–5◦C. Potassium tertiary butoxide (2.8 g, 0.025 mol) was added gradually to the
cooled mixture with continuous shaking, cold water was then added with continuous
shaking and the benzene layer was separated. The aqueous layer was washed several times
with petroleum ether 40/60. The aqueous layer was cooled and gradually acidified with
concentrated sulfuric acid. The separated precipitate was filtered off and recrystallized from
benzene to give:
Thiol (1):13,17–21 from acetylthiophene as red crystals, mp 83◦C;
Thiol (2):13,17–21 from acetylfuran as yellowish-brown crystals, mp 50◦C.
Synthesis of 1,2-dithiacyclopentene-3-thiones (3), (4).
General procedure. To the dithiole (1) or (2) (0.01 mol) in dry benzene was added
phosphoruspentasulfide (0.15 mol). The reaction mixture was heated on a water bath for
5 h, and then filtered while hot. The clear benzene layer was concentrated to its half volume
followed by addition of appropriate quantity of petroleum ether 40/60. The precipitated
solid product was filtered off and washed twice with petroleum ether 40/60, giving the
required thione (3) or (4).
Dithiole (1) gave 1,2-dithiole-3-thione (3) as reddish-brown crystals from methylene
chloride, mp 118◦C, yield 79%. Elemental analysis: C7H4S4 (216.342) Calcd: C, 38.86; H,
1.86; S, 59.28%. Found: C, 39.01; H, 1.82; S, 60.02%.
Dithiole (2) gave 1,2-dithiole-3-thione (4) as brown crystals from methylene chloride,
mp 110◦C, yield 85%. Elemental analysis: C7H4OS3 (200.282) Calcd: C, 41.98; H, 2.01;
S, 48.02%. Found: C, 42.01; H, 2.00; S, 48.03%.
Synthesis of 1,3-dithiole-2-ylidene system (5), (6): (a) Dimethyl-2-(2-thi
en-2-yl-2-thioxoethylidene)-1,3-dithiole-4,5-dicarboxylate (5). Dithiolethione
(3) (2.16 g, 0.01 mol) was treated with dimethyl acetylenedicarboxylate (DMAD)
(1.20 mL, 0.01 mol) in different conditions; compound (5) was obtained. In the case of
1-CH2Cl2/hot the yield was 78%, 2-CH2Cl2/r.t. the yield was 80%, 3-H2O/sunlight gives
88%, 4- while in H2O/ chitosan the yield was 84%, mp 140◦C, color: violet, solvent
of crystallization: methanol. Elemental analysis: C13H10O4S4 (358.48) Calcd: C, 43.56;
H, 2.81; S, 35.78%. Found: C, 43.44; H, 2.83; S, 35.72%. Mass spectrum, m/e (I,%),
358 (M+., 35), (216, 100). IR (KBr): ν (cm−1) = 1175 ( C S), 1480 ( C CH), 1735
( C O), 1−HNMR (DMSO): δ (ppm) = 3.91–3.93 (s, 6H, 2CH3), 7.10–7.60 (t, J =
10 Hz, 2d, J = 14 Hz, 3H, thienyl), 8.09 (s, 1H, CH C).
(b) Dimethyl-2-(2-fur-2-yl)-2-thioxoethylidene)-1,3-dithiole-4, 5-dicar-box
ylate (6). When dithiolethione (4) (2.00 g, 0.01 mol) was treated with DMAD (1.20 mL,
0.01 mol), compound (6) was obtained. In the case of 1-CH2Cl2/hot the yield was 76%,
2-CH2Cl2/r.t. the yield was 83%, 3-H2O/sunlight gives 87%, 4- while in H2O/chitosan
(chitine) the yield was 84%, mp 120◦C, color: violet, solvent of crystallization: methanol.
Elemental analysis: C13H10O5S3 (342.41) Calcd: C, 45.60; H, 2.94; S, 28.09%. Found:
C, 45.77; H, 2.95; S, 28.07%. Mass spectrum, m/e (I,%), 342 (M+., 27), (200, 71), (59,
100). IR (KBr): ν (cm−1) = 1086 ( C S), 1739 ( C O),1−HNMR (DMSO): δ (ppm) =
3.70–3.80 (s, 6H, 2CH3), 6.70–8.00 (t, J = 16 Hz, 2d, J = 18 Hz, 3H, furyl), 8.50 (s, 1H,
C CH).
Synthesis of tetramethyl-9-(thien-2-yl)-1,4,8-trithiaspiro [4.5]deca-2,6,
9-triene-2,3,6,7-tetracarboxylate (7). A mixture of compound (3) (1.00 mol;
1.08 g, 0.005 mol) and DMAD (3 mols; 1.83 mL, 0.015 mol) in 50 mL dry xylene
was heated under reflux for 7 h, then the solution was concentrated and left to cool.
The product precipitated and then collected by filtration, it was recrystallized from
ethanol as black crystals, mp 165◦C, yield 72%. Also compound (7) can be prepared

OXOKETENE DITHIOLS
11
by heating a mixture of compound (5) (1.00 mol; 1.19 g, 0.0033 mol) and DMAD
(1 mol; 0.4 mL, 0.0033 mol) in 50 mL dry xylene for 7 h.
Elemental analysis: C19H16O8S4 (500.59) Calcd: C, 45.59; H, 3.22; S, 25.62%.
Found: C, 45.42; H, 3.25; S, 25.61%. Mass spectrum, m/e (I,%), 500 (M+., 60), (441, 100).
IR (KBr): ν (cm−1) = 1726 ( C O), 1−HNMR (DMSO): δ (ppm) = 3.60–4.60 (s, 12H,
4CH3), 7.20–7.80 (m, J = 40 Hz, 3H, thienyl), 8.60 (s, 1H, CH C).
Synthesis of 5-(thien-2-yl)-3H-1,2-dithiol-3-one (8). 2.16 g, 0.01 mol of com-
pound (3) was dissolved in 100 mL of acetone; to this solution was added 3.65 g, 0.05 mol
of KMnO4 gradually with continuous stirring at room temperature for 4 h, then the mixture
was left to stand over night. The solution was filtered off to do without the undissolved
materials and then the filtrate was concentrated and left to cool. The product precipitated on
cooling, and then it was collected and recrystallized from ethanol as pale yellow crystals,
mp 90◦C, and yield 59%. Elemental analysis: C7H4OS3 (200.30) Calcd: C, 41.97; H, 2.01;
S, 48.03%. Found: C, 42.02; H, 2.03; S, 47.94%. Mass spectrum, m/e (I,%), 200 (M+., 12),
(111, 100). IR (KBr): ν (cm−1) = 1660 (C O), 1−HNMR (DMSO): δ (ppm) = 7.20–7.90
(t, J = 20 Hz, 2d, J = 20 Hz, 3H, thienyl), 9.10 (s, 1H, CH C).
Synthesis of 4-bromo-5-(thien-2-yl)-3H-1,2-dithiol-3-one (9). 1 g, 0.005
mol of compound (8) was dissolved in 50 mL chloroform; to this solution was added
0.795 mL, 0.005 mol of bromine in 30 mL chloroform, gradually on portions, with stirring
in direct sunlight. After complete addition of bromine solution, the reaction was heated
under reflux on a water bath for 3 h. The solution was left to evaporate at room temperature.
The product was collected and recrystallized from ethanol as buff powder, mp 180◦C, yield
77%. Elemental analysis: C7H3BrOS3 (279.20) Calcd: C, 30.11; H, 1.08; Br, 28.62; S,
34.45%. Found: C, 30.21; H, 1.03; Br, 28.51; S, 34.52%. Mass spectrum, m/e (I,%), 279
(M+., 60), (213, 100), (83, 5), 1−HNMR (DMSO): δ (ppm) = 7.20–7.80 (t, J = 12 Hz, 2d,
J = 10 Hz, 3H, thienyl).
Synthesis of (E)-dimethyl-2-(2-thien-2-yl)-2-thioxoethylid-ene)-1,3-oxat
hiole-4,5-dicarboxylate (10). 1.00 g, 0.005 mol of compound (8) was dissolved in
30 mL dry xylene; to this solution was added 0.61 mL, 0.005 mol of DMAD. The mixture
was refluxed for 28 h, then it was concentrated and left to cool. The product precipitated
which was collected and recrystallized from methanol as brown powder, mp 128–130◦C,
and yield 17%. Elemental analysis: C13H10O5S3 (342.41) Calcd: C, 45.60; H, 2.94;
S, 28.09%. Found: C, 45.61; H, 2.83; S, 28.17%. Mass spectrum, m/e (I,%), 342 (M+.,
14), (241, 38), (59, 100), 1−HNMR (DMSO): δ (ppm) = 3.50–4.20 (s, 6H, 2CH3), 5.30 (s,
1H, CH C), 6.80–7.00 (t, 2d, J = 10 Hz, 3H, thienyl).
Synthesis of (Z)-dimethyl-2-(1-bromo-2-(thien-2-yl)-2-thioxoethylidene)
1,3-oxathiole-4,5-dicarboxylate (11). A mixture of compound (9) (1.39 g, 0.005 mol)
and DMAD (0.61 mL, 0.005 mol) in 50 mL dry xylene was heated under reflux for 7 h. The
mixture was concentrated and left to cool; the product precipitated and was then collected by
filtration. It was recrystallized from dioxane as dark green crystals, mp 150◦C, yield 72%.
Elemental analysis: C13H9BrO5S3 (421.31) Calcd: C, 37.06; H, 2.15; Br, 18.97; S, 22.83%.
Found: C, 37.11; H, 2.17; Br, 18.93; S, 22.77%. Mass spectrum, m/e (I,%), 421(M+., 28),
(64, 100). IR (KBr): ν (cm−1) = 1738 ( C O), 1−HNMR (DMSO): δ (ppm) = 3.60–3.70
(s, 6H, 2CH3), 7.30–7.80 (t, J = 10 Hz, 2d, J = 14 Hz, 3H, thienyl).
Synthesis of dimethyl-2-(1-bromo-2-(thien-2-yl)-2-thioxo-ethylidene)-1,
3-dithiole-4,5-dicarboxylate (12). 1.79 g, 0.005 mol of compound (5) was dissolved
in 100 mL chloroform. To this solution was added 1.59 g, 0.01 mol bromine solution in
20 mL chloroform. Bromine solution was added drop wisely with stirring in direct sunlight.

12
S. E. ZAYED ET AL.
After complete addition of bromine solution, the mixture was left to concentrate at room
temperature. The product was collected and recrystallized from methanol as dark brown
crystals, mp 78–80◦C, and yield 68%. Elemental analysis: C13H9BrO4S4 (437.37) Calcd:
C, 35.70; H, 2.07; Br, 18.27; S, 29.33%. Found: C, 35.58; H, 2.11; Br, 18.13; S, 29.41%.
Mass spectrum, m/e (I,%), 437 (M+., 13), (111, 100), (83, 10). IR (KBr): ν (cm−1) = 1735
(C O), 1−HNMR (DMSO): δ (ppm) = 3.92 (s, 6H, 2CH3), 6.90–8.20 (t, J = 14 Hz, 2d, J
= 18 Hz, 3H, thienyl).
Synthesis of tetramethyl-10-bromo-9-(thien-2-yl)-1,4,8-tri-thiaspiro[4.5]
deca-2,6,9-triene-2,3,6,7-tetracarboxylate (13). A mixture of compound (12)
(1.09 g, 0.0025 mol) and DMAD (0.30 mL, 0.0025 mol) in 30 mL dry xylene was refluxed
for 2 h. The mixture was concentrated and left to cool, the product precipitated, which
was collected and recrystallized from methanol as black crystals, mp 210–212◦C, yield
59%. Elemental analysis: C19H15BrO8S4 (579.48) Calcd: C, 39.38; H, 2.61; Br, 13.79; S,
22.13%. Found: C, 39.38; H, 2.65; Br, 13.75; S, 22.24%. Mass spectrum, m/e (I,%), 579
(M+., 200), (111, 100). IR (KBr): ν (cm−1) = 1731 (C O), 1−HNMR (DMSO): δ (ppm)
= 3.80 (s, 12H, 4CH3), 6.90–8.30 (t, J = 12 Hz, 2d, J = 18Hz, 3H, thienyl).
Synthesis of (E)-tetramethyl-2,2ꢁ-(2,3-di(thien-2-yl)but-2-ene-1,4-diylid
ene)bis(1,3-dithiole-4,5-dicarboxylate) (14). 1.79 g, 0.005 mol of compound (5)
was boiled in 30 mL dry xylene for 10 h. The solution was concentrated and left to cool,
the product was collected, and recrystallized from methylene chloride as black crystals, mp
78–80◦C, yield 61%. Elemental analysis: C26H20O8S6 (652.82) Calcd: C, 47.84; H, 3.09;
S, 29.47%. Found: C, 47.88; H, 2.93; S, 30.02%. Mass spectrum, m/e (I,%), 652 (M+., 24),
(82, 100). IR (KBr): ν (cm−1) = 1734 (C O), 1−HNMR (DMSO): δ (ppm) = 3.70–3.90
(s, 12H, CH3), 6.00 (s, 2H, CH , CH ), 7.20–7.80 (m, J = 12 Hz, 6H, 2 thienyl rings).
Synthesis of (E)tetramethyl-2,2ꢁ-(2,3-di(thien-2-yl)but-2-ene-1,4-diyl)bis
(1,3-dithiole-4,5-dicarboxylate) (15). 0.5 g, 0.00076 mol of compound (14) was dis-
solved in absolute ethanol (30 mL); to this solution was added sodium metal (0.2 g).
The mixture was stirred for 1 h at room temperature, and then it was left to concentrate.
The product precipitated which was collected and recrystallized from methanol as violet
powder, mp 120◦C, yield 33%.
Elemental analysis: C26H24O8S6 (656.85) Calcd: C, 47.54; H, 3.68; S, 29.29%.
Found: C, 47.37; H, 3.56; S, 29.17%. Mass spectrum, m/e (I,%), 656 (M+., 24), (299, 100),
1−HNMR (DMSO): δ (ppm) = 1.05 (d, J = 12 Hz, 4H, 2CH2), 1.50 (t, J = 10 Hz, 2H,
2CH), 3.70–3.90 (s, 12H, CH3), 7.10–8.00 (m, J = 14Hz, 6H, 2 thienyl rings)
Synthesis of (Z)-2-cyano-2-(5-(thien-2-yl)-3H-1,2-dithiol-3-ylidene)ethan
ethioamide (16). A mixture of compound (8) (1.00 g, 0.005 mol) and cyano thioac-
etamide (0.5 g, 0.005 mol) in DMF (30 mL) was refluxed for 5 h. The solution was
concentrated and left to cool. The product precipitated and then collected, it was recrystal-
lized from dioxane as dark brown crystals, mp > 300, and yield 74%. Elemental analysis:
C10H6N2S4 (282.43) Calcd: C, 42.53; H, 2.14; N, 9.92; S, 45.41%. Found: C, 42.68; H,
2.23; N, 9.55; S, 45.45%. Mass spectrum, m/e (I,%), 282 (M+., 32), (232, 100), (83, 34).
IR (KBr): ν (cm−1) = 2202 (CN), 3313, 3188 (NH2), 1−HNMR (DMSO): δ (ppm) = 6.50
(s, 1H, CH C), 7.00–7.60 (t, J = 12 Hz, 2d, J = 14 Hz, 3H, thienyl), 8.20 (s, 2H, NH2).
Synthesis of dimethyl-2-(2-thien-2-yl)-2-thioxosulfonyl ethylidene)-1,3-
dithiole-4,5-dicarboxylate(17). 1.79 g, 0.005 mol of compound (5) was dissolved in
30 mL hydrogen peroxide, the solution was stirred at room temperature for 2 h then it
was left at room temperature to concentrate. The product precipitated and collected as
buff crystals from water, mp > 300, and yield 21.77%. Elemental analysis: C13H10O6S4

OXOKETENE DITHIOLS
13
(390.47) Calcd: C, 39.99; H, 2.58; S, 32.85%. Found: C, 39.75; H, 2.62; S, 32.77%.
Mass spectrum, m/e (I,%), 390 (M+., 17), (64, 100), 1−HNMR (DMSO): δ (ppm) =
3.90 (s, 1H, 2CH3), 4.80 (s, 1H, CH C), 7.20–7.90 (t, J = 10 Hz, 2d, J = 8 Hz, 3H,
thienyl).
Synthesis of dimethyl-2-(3,3-dicyano-2-(thien-2-yl)allylid-ene)-1,3-dith
iole-4,5-dicarboxylate (18). A mixture of compound (5) (1.79 g, 0.005 mol) and
malononitrile (0.33 g, 0.005 mol) in 50 mL DMF was heated under reflux for 4 h. The
mixture was concentrated and left to cool, the product precipitated, which was collected
and recrystallized from methanol/DMF as dark brown crystals, mp 180–182◦C, yield 75%.
Elemental analysis: C16H10N2O4S3 (390.46) Calcd: C, 49.22; H, 2.58; N, 7.17; S, 32.85%.
Found: C, 49.31; H, 2.45; N, 7.17; S, 32.89%. Mass spectrum, m/e (I,%), 390 (M+., 1),
(44, 100). IR (KBr): ν (cm−1) = 2199 (CN), 1704 (C O), 1−HNMR (DMSO): δ (ppm)
= 3.80 (s, 1H, 2CH3), 6.50 (s, 1H, CH ), 7.20–7.90 (t, J = 12 Hz, 2d, J = 10 Hz, 3H,
thienyl).
Synthesis of (Z)-dimethyl-2-(4-amino-3,5,5-tricyano-2-(thien-2-yl)penta-
2,4-dienylidene)1,3-dithiole-4,5-dicarbo-xylate (18a). A mixture of compound (5)
(1.79 g, 0.005 mol) and malononitrile (0.33 g, 0.005 mol) in 50 mL DMF was heated under
reflux for 4 h. The mixture was concentrated and left to cool, the product precipitated,
which was collected and recrystallized from methanol/DMF as violet crystals, mp 330◦C,
yield 62%. Elemental analysis: C19H12N4O4S3 (456.52) Calcd: C, 49.99; H, 2.65; N, 12.27;
S, 21.07%. Found: C, 49.87; H, 2.64; N, 12.09; S, 21.11%. Mass spectrum, m/e (I,%), 456
(M+., 5), (44, 100). IR (KBr): ν (cm−1) = 2204 (CN), 1704 (C O), 1−HNMR (DMSO): δ
(ppm) = 3.80 (s, 1H, 2CH3), 6.50 (s, 1H, CH ), 7.20–7.90 (t, J = 8 Hz, 2d, J = 10 Hz,
3H, thienyl).
Synthesis of 2-(2-(thien-2-yl)-2-thioxoethylidene)naphtha [2,3-d][1,3]dit
hiole-4,9-dione (21). A mixture of compound (3) (1.08 g, 0.005 mol) and 2,3-dichlor-
1,4-naphthoquinone (1.13 g, 0.005 mol) in 50 mL dry xylene was refluxed for 7 h. The
mixture was concentrated and left to cool, the product precipitated, which was collected
and recrystallized from ethanol as dark brown crystals, mp 310◦C, yield 72%. This result
was obtained also when 1 mol of compound (3) was reacted with 2 mols of 2,3-dichloro-
1,4-naphthoquinone. Elemental analysis: C17H8O2S4 (372.50) Calcd: C, 54.81; H, 2.16; S,
34.43%. Found: C, 54.67; H, 2.25; S, 34.26%. Mass spectrum, m/e (I,%), 372 (M+., 85),
(168, 100), (83, 4) (76,56), 1−HNMR (DMSO): δ (ppm)= 4.70 (s, 1H, CH ), 7.00–7.70
(t, J = 12 Hz, 2d, J = 16 Hz, 3H, thienyl), 7.90 (m, J = 8 Hz, 4H, aromatic-H).
Synthesis of 2-(2-(fur-2-yl)-2-thioxoethylidene)naphtho-[2,3-d] [1,3]dith
iole-4,9-dione (22). A mixture of compound (4) (1.00 g, 0.005 mol) and 2,3-dichloro-
1,4-naphthoquinone (1.13 g, 0.005 mol) in 50 mL dry xylene was heated under reflux for
7 h. The solution was concentrated and left to cool, the product precipitated, which was
collected and recrystallized from ethanol as dark brown crystals, mp 170◦C, yield 49%.The
product (22) can be obtained also by reaction of 1 mol of compound (4) with 2 mols of 2,3-
dichloro-1,4-naphthoquinone. Elemental analysis: C17H8O3S3 (356.44) Calcd: C, 57.28;
H, 2.26; S, 26.99%. Found: C, 57.25; H, 2.29; S, 26.91%. Mass spectrum, m/e (I,%), 356
(M+., 33), (98, 100). IR (KBr): ν (cm−1) = 1702 (C O), 1−HNMR (DMSO): δ (ppm) =
4.90 (s, 1H, CH C), 6.30–7.10 (t, J = 10 Hz, 2d, J = 12 Hz, 3H, furyl), 7.70 (m, J =
8 Hz, 4H, aromatic-H).
Synthesis of 2-(2-(thien-2-yl)-2-thioxoethylidene)naphtho [2,3-d][1,3]dit
hiole-4,9(3aH,9aH)-dione (23). A mixture of compound (3) (1.08 g, 0.005 mol) and
1,4-naphthoquinone (0.79 g, 0.005 mol) in 50 mL dry xylene was refluxed for 7 h. The

14
S. E. ZAYED ET AL.
mixture was concentrated and left to cool, the product precipitated, which was collected and
recrystallized from ethanol as dark brown crystals, mp 204◦C, yield 56%.This result was
obtained also when we react 1 mol of compound (3) with 2 mols of 1,4-naphthoquinone.
Elemental analysis: C17H10O2S4 (374.52) Calcd: C, 54.52; H, 2.69; S, 34.25%.
Found: C, 54.61; H, 2.55; S, 34.26%. Mass spectrum, m/e (I,%), 374 (M+., 75), (76, 100),
1−HNMR (DMSO): δ (ppm) = 2.20 (d, J = 14 Hz, 2H, CH CH), 4.70 (s, 1H, CH C),
7.00–7.60 (t, J = 10 Hz, 2d, J = 12 Hz, 3H, thienyl), 8.00–8.20 (m, J = 8 Hz, 4H, aromatic
protons).
Synthesis of 2-(2-(fur-2-yl)-2-thioxoethylidene)naphtho-[2,3-d][1,3]dithi
ole-4,9(3aH,9aH)-dione (24). A mixture of compound (4) (1.00 g, 0.005 mol) and
1,4-naphthoquinone (0.79 g, 0.005 mol) in 50 mL dry xylene was heated under reflux for
7 h. The solution was concentrated and left to cool, the product precipitated, which was
collected and recrystallized from ethanol as dark brown crystals, mp 218–220◦C, yield
64%. The product (24) can be obtained also by reaction of 1 mol of compound (4) with
2 mols of 1,4-naphthoquinone. Elemental analysis: C17H10O3S3 (358.45) Calcd: C, 56.96;
H, 2.81; S, 26.84%. Found: C, 56.83; H, 2.77; S, 26.91%.
Mass spectrum, m/e (I,%), 358 (M+., 12), (168, 100), 1−HNMR (DMSO): δ (ppm) =
2.30 (d, J = 12 Hz, 2H, CH CH), 4.80 (s, 1H, CH ), 6.90–7.60 (t, J = 10 Hz, 2d, J =
16 Hz, 3H-furyl), 8.10 (m, J = 8 Hz, 4H, aromatic-H).
Synthesis of 2-(2-thien-2-yl)-2-thioxoethylidene)benzo[d] [1,3]dithiole-4,
7(3aH,7aH)-dione (25). A mixture of compound (3) (1.08 g, 0.005 mol) and p-
benzoquinone (0.54 g, 0.005 mol) in 50 mL dry xylene was heated under reflux for 7 h. The
mixture was concentrated and left to cool, the product precipitated, which was collected
and recrystallized from ethanol as dark brown crystals, mp 210◦C, yield 76%. The same
result was obtained when we react 1 mol of compound (3) with 2 mols of p-benzoquinone.
Elemental analysis: C13H8O2S4 (324.46) Calcd: C, 48.12; H, 2.49; S, 39.53%. Found:
C, 48.04; H, 2.66; S, 39.45%. Mass spectrum, m/e (I,%), 324 (M+., 68), (110, 100), (83,
28), 1−HNMR (DMSO): δ (ppm) = 2.70 (d, J = 12 Hz, 2H, CH-CH), 4.70 (s, 1H,
CH C), 6.30 (d, J = 10 Hz, 2H, CH CH), 7.00–7.60 (t, J = 12 Hz, 2d, J = 16 Hz, 3H,
thienyl).
Synthesis of 2-(2-(fur-2-yl)-2-thioxoethylidene)benzo[d][1, 3]dithiole-4,
7(3aH,7aH)-dione (26). A mixture of compound (4) (1.00 g, 0.005 mol) and p-
benzoquinone (0.54 g, 0.005 mol) in 50 mL dry xylene was heated under reflux for 7 h and
then it was concentrated and left to cool. The product precipitated which was collected and
recrystallized from ethanol as black crystals, mp 158–160◦C, and yield 80%. Product (26)
also can be obtained by reacting 1 mol of compound (4) with 2 mols of p-benzoquinone.
Elemental analysis: C13H8O3S3 (308.40) Calcd: C, 50.63; H, 2.61; S, 31.19%. Found:
C, 50.56; H, 2.59; S, 31.07%. Mass spectrum, m/e (I,%), 308 (M+., 79), (120, 100), 1−HNMR
(DMSO): δ (ppm) = 2.19 (d, J = 10 Hz, 2H, CH CH), 4.80 (s, 1H, CH ), 5.90 (d, J =
10 Hz, 2H, CH CH), 6.50–6.90 (t, J = 12 Hz, 2d, J = 12 Hz, 3H, furyl).
Synthesis of 2-[3,5-dithia-tricyclo(5.2.1.0∗ 2,6∗) dec-8-en-4ylidene]-1-
thiophen-2-yl-ethanethione (29). A mixture of compound (3) (1.08 g, 0.005 mol)
and 1,3- cyclopentadiene (0.41 mL, 0.005 mol) in 30 mL dry xylene was refluxed for
5 h. The mixture was concentrated and left to cool, the product precipitated, then it was
collected and recrystallized from ethanol as black crystals, mp 243–244◦C, and yield
65.79%. Elemental analysis: C14H12S4 (308.51) Calcd: C, 54.51; H, 3.92; S, 41.57%.
Found: C, 54.54; H, 3.97; S, 42.05%, 1−HNMR (DMSO): δ (ppm) = (C4 cyclohexene,
1H s, 2.80), (C5 cyclohexene 1H, 3.00) 2H CH2 d,d 2.11 (C3-cyclohexene-1H),s, 3.75,

OXOKETENE DITHIOLS
15
(C4-cyclohexene,1H,s 3.22) (C5,cyclohexene s,6.01) (C6-cyclohexene s,1H 6.25), 6.01 (s,
1H, CH C), 6.60–7.50 (t, J = 12 Hz, 2d, J = 16 Hz, 3H, thienyl).
Synthesis of (Z)-2-(3a,4,5,7a-tetrahydrobenzo[d][1,3] dithiol -2-ylidene)-
1-(thien-2-yl)ethanethione (30). A mixture of compound (3) (1.08 g, 0.005 mol) and
1,3-cyclohexadiene (0.46 mL, 0.005 mol) in 30 mL dry xylene was refluxed for 5 h. The
mixture was concentrated and left to cool, the product precipitated, then it was collected and
recrystallized from ethanol as black crystals, mp 205–207◦C, and yield 63%. Elemental
analysis: C13H12S4 (296.49) Calcd: C, 52.66; H, 4.08; S, 43.26%. Found: C, 52.63; H,
4.12; S, 43.19%. Mass spectrum, m/e (I,%), 296 (M+., 23), (200, 100), (83, 4), 1−HNMR
(DMSO): δ (ppm) = 1.60 (q, 2H, CH2), 1.90 (q, 2H, CH2), 2.80 (q, 1H, H), 3.30 (t, 1H, H)
4.90 (s, 1H, CH C), 6.20 (m, 2H, CH CH), 7.10–7.70 (t, J = 12 Hz, 2d, J = 16 Hz, 3H,
thienyl).
Synthesis of 5,7-dimethyl-2-(thienyl–2-yl)-5,7a-dihydro-4aH-spiro[b]thio
pyran-4,2ꢁ-[1,3]dithiole]- 4ꢁ,5ꢁ dicarboxylate–bicyclo[2.3.1] hept-2-ene (31). A
mixture of compound (5) (1.79 g, 0.005 mol) and 1,3-cyclopentadiene (0.41 g, 0.005 mol)
in 50 mL dry xylene for 6 h. The solution was concentrated and left to cool, the product
precipitated, then it was collected and recrystallized from methanol as violet crystals, which
chars at 305◦C, and melts over 305◦C, yield 40%. Elemental analysis: C21H22O4S4 (466.66)
Calcd: C, 54.05; H, 4.75; S, 27.48%. Found: C, 53.93; H, 4.79; S, 27.17%. IR (KBr): ν
(cm−1) = 1736 (C O), 1−HNMR (DMSO): δ (ppm) = 1.82 (t, 2H, CH2), 3.77, 3.88 (s,
6H, 2CH3) 4.80 (t, 1H, Hb), 4.50 (m, 2H, CH CH), 6.22, 6.71 (m, 2H, CH CH) 6.70 (s,
1H, CH ), 7.35–8.22 (t, J = 12 Hz, 2d, J = 10 Hz, thienyl).
Synthesis of trimethyl-9-(thien-2-yl)-1,4,8- trithiaspiro [4.5] deca-2,9-die
ne-2,3,6-tricarboxylate (32). A mixture of compound (5) (1.79 g, 0.005 mol) and
methyl-acrylate (0.45 mL, 0.005 mol) in 50 mL dry xylene was heated under reflux for
6 h, the solution was concentrated and left to cool. The product precipitated, and then it was
collected and recrystallized from methanol as dark brown crystals, which char at 300◦C
and melt over 302◦C, yield 38%.
Elemental analysis: C17H16O6S4 (444.57) Calcd: C, 45.93; H, 3.63; S, 28.85%.
Found: C, 45.78; H, 3.54; S, 28.91%. Mass spectrum, m/e (I,%), 444 (M+., 5), (213, 100).
IR (KBr): ν (cm−1) = 1739 (C O).
Synthesis of dimethyl-5ꢁ,7ꢁ-dioxo-2ꢁ-(thien-2-yl)-4aꢁ,5ꢁ,7ꢁ, 7aꢁ-tetrahydro
spiro[[1,3]dithiole-2,4ꢁ-thiopyrano[2,3-c] furan]-4,5-dicarboxylate (33). A mix-
ture of compound (5) (1.79 g, 0.005 mol) and maleic anhydride (0.49 g, 0.005 mol) in
50 mL dry xylene was refluxed for 1 h. The mixture was concentrated and left to cool, the
product precipitated, then it was collected and recrystallized from methanol as dark brown
crystals, chars, yield 42%. Elemental analysis: C17H12O7S4 (456.53) Calcd: C, 44.72; H,
2.65; S, 28.09%. Found: C, 44.69; H, 2.65; S, 28.11%. Mass spectrum, m/e (I,%), 456
(M+., 7), (54, 100). IR (KBr): ν (cm−1) = 1737 (C O of ester), 1807 (C O of anhydride),
1−HNMR (DMSO): δ (ppm) = 1.56 (d, 1H, Ha), 2.80 (d, 1H, Hb), 3.70–3.80 (s, 6H, 2CH3),
6.80 (s, 1H, CH ), 7.00–8.00 (t, J = 12 Hz, 2d, J = 10 Hz, 3H, thienyl).
Synthesis of (2E)-methyl-5-(N-cyanocarbamimidoylcarba-moyl)-2-(2-(N-
cyanocarbamimidolylimino)-2-(thien-2-yl) ethylidene)-1,3-dithiole-4-carboxy
late (34). 1.79 g, 0.005 mol of compound (5) was dissolved in 50 mL absolute ethanol; to
this solution was added 0.42 g, 0.005 mol of dicyanodiamide and few drops of triethylamine.
The mixture was heated under reflux for 5 h and then it was concentrated. The product
precipitated and then it was collected and recrystallized from methanol as brown crystals,
mp 108–110◦C, yield 70%. The same result obtained when (1 mol) of compound (5) was

16
S. E. ZAYED ET AL.
treated with (2 mol) of dicyanodiamide. Elemental analysis: C16H12N8O3S3 (460.51) Calcd:
C, 41.73; H, 2.63; N, 24.33; S, 20.89%. Found: C, 41.73; H, 2.58; N, 24.37; S, 21.88%.
Mass spectrum, m/e (I,%), 460 (M+., 40), (216, 100). IR (KBr): ν (cm−1) = 2204 (CN),
1722 (C O), 1−HNMR (DMSO): δ (ppm) = 1.20 (s, 2H, 2NH-CN), 3.90 (s, 1H, 2CH3),
4.30 (s, 2H, 2NH=C), 4.70 (s, 1H, CH ), 7.20–7.90 (t, J = 10 Hz, d, J = 12 Hz, 3H,
thienyl), 8.70 (s, 2NH2).
Synthesis of (2E)-methyl-5(2-carbamimidoylhydrazinecar-bonyl)-2-(2-(2-
carbamimidoylhydrazono)-2-(thien-2-yl)et-hylidene)-1,3-dithiole-4-carboxyla
te (35). A mixture of compound (5) (1.79 g, 0.005 mol) and guanidine sulfate (1.30 g,
0.005 mol) in 50 mL DMF and few drops of triethylamine was refluxed for 6 h. The
solution was concentrated and left to cool. The product precipitated, then it was collected
and washed several times with distilled water; it was recrystallized from methanol as dark
red crystals, mp 128–130◦C, and yield 82%. The same result was obtained when 1 mol of
compound (5) was reacted with 2 mols of guanidine sulfate. Elemental analysis: C14H16
N8O3S3 (440.52) Calcd: C, 38.17; H, 3.66; N, 25.44; S, 21.84%. Found: C, 38.17; H, 3.57;
N, 25.44; S, 22.01%. Mass spectrum, m/e (I,%), 440 (M+., 7), (216, 100). IR (KBr): ν
(cm−1) = 1703 (C O), 1−HNMR (DMSO): δ (ppm) = 1.30–1.37 (d, 2H, 2NHa), 3.80 (s,
3H, CH3), 4.30–4.37 (s, 1H, NHb), 4.70 (s, 1H, CH ), 7.20–7.90 (t, J = 10 Hz, d, J =
12 Hz, 3H, thienyl), 8.20 (s, 1H, NHd), 8.50 (s, 1H, NHc), 8.70 (s, 1H, 2NH2).
Synthesis of 2-(2-(thien-2-yl)-2-thioxoethylidene)-1,3-dith-iole-4,5-dicar
boxamide (36). 1.79 g, 0.005 mol of compound (5) was dissolved in ammonia solution
(100 mL). The solution was heated under reflux for 20 h, then it was left to cool and concen-
trate. The product precipitated, which was collected and recrystallized from methanol as
dark violet crystals, chars, yield 16%. Elemental analysis: C11H8N2O2S4 (328.45) Calcd:
C, 40.22; H, 2.45; N, 8.53; S, 39.05%. Found: C, 40.20; H, 2.27; N, 8.55; S, 39.09%. Mass
spectrum, m/e (I,%), 328 (M+., 3), (57, 100), 1−HNMR (DMSO): δ (ppm) = 4.90 (s, 1H,
CH C), 8.10 (s, 4H, 2CONH2), 7.40 (m, 3H, thienyl).
ACKNOWLEDGMENT
The authors thank Prof. Dr. M. H. Elnagdi, Chemistry Department, Kuwait University,
for providing facilities and his kind help during this work.
SUPPLEMENTAL MATERIAL
Supplementary data for this article can be accessed on the publisher’s website,
www.tandfonline.com/gpss. (Tables S1–S3).
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