Synthesis, antimicrobial studies, and molecular docking of some new dihydro-1,3,4-thiadiazole and pyrazole derivatives derived from dithiocarbazates

Article abstract of DOI:10.1080/00397911.2020.1843179

A series of 3-acetyl-2-aryl-5-methylthio-2,3-dihydro-1,3,4-thiadiazoles 3a–g,N- (4-acetyl-5-aryl-4,5-dihydro-1,3,4-thiadiazol-2-yl) acetamide derivatives 5a–e and spiro-compound 7 was prepared from starting material dithiocarbazates using N-methylpyrrolid

Full text of DOI:10.1080/00397911.2020.1843179

Synthetic Communications
An International Journal for Rapid Communication of Synthetic Organic
Chemistry
ISSN: (Print) (Online) Journal homepage: https://www.tandfonline.com/loi/lsyc20
Synthesis, antimicrobial studies, and molecular
docking of some new dihydro-1,3,4-thiadiazole and
pyrazole derivatives derived from dithiocarbazates
Amr Hassan Moustafa , Doaa H. Ahmed , Mohamed T. M. El-Wassimy &
Mamdouh F. A. Mohamed
To cite this article: Amr Hassan Moustafa , Doaa H. Ahmed , Mohamed T. M. El-Wassimy &
Mamdouh F. A. Mohamed (2020): Synthesis, antimicrobial studies, and molecular docking of some
new dihydro-1,3,4-thiadiazole and pyrazole derivatives derived from dithiocarbazates, Synthetic
Communications, DOI: 10.1080/00397911.2020.1843179
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https://doi.org/10.1080/00397911.2020.1843179
Synthesis, antimicrobial studies, and molecular docking of
some new dihydro-1,3,4-thiadiazole and pyrazole
derivatives derived from dithiocarbazates
Amr Hassan Moustafaa , Doaa H. Ahmeda, Mohamed T. M. El-Wassimya, and
Mamdouh F. A. Mohamedb
b
aDepartment of Chemistry, Faculty of Science, Sohag University, Sohag, Egypt; Department of
Pharmaceutical Chemistry, Faculty of Pharmacy, Sohag University, Sohag, Egypt
ABSTRACT
ARTICLE HISTORY
Received 12 September 2020
A series of 3-acetyl-2-aryl-5-methylthio-2,3-dihydro-1,3,4-thiadiazoles
3a–g, N- (4-acetyl-5-aryl-4,5-dihydro-1,3,4-thiadiazol-2-yl) acetamide
derivatives 5a–e and spiro-compound 7 was prepared from starting
material dithiocarbazates using N-methylpyrrolidone (NMP) /acetic
anhydride mixture. Furthermore, a new series of 5-amino-3- (methyl-
thio) -1-substituted-1H-pyrazole-4-carbonitrile derivatives 12a–d was
prepared using two synthetic routes: (i) via reaction of bis (methyl-
thio) methylene malononitrile 8 with carbothiohydrazides 11a–d, or
(ii) via reaction of methyl 5-amino-4-cyano-3- (methylthio) -1H-pyra-
zole-1-carbodithioate 9a with primary/secondary amines. The anti-
microbial screening of newly synthesized compounds revealed that
compounds 3b, 7, and 12d are the most potent against the Gram-
positive (S. aureus) and the Gram-negative (E. coli) bacteria compared
to ciprofloxacin as reference drug. Mechanistically, the theoretical
docking results of 3b, 7 and 12d suggested that they may act as
potent inhibitors of theDNA gyrase.
KEYWORDS
Antimicrobial; carbothiohy-
drazides; 2,3-dihydo-1,3,4-
thiadiazole; dithiocarba-
zates; pyrazole
GRAPHICAL ABSTRACT
CONTACT Amr H. Moustafa
amr_hassanegypt@ymail.com
Department of Chemistry, Faculty of Science, Sohag
University, Sohag, Egypt
Supplemental data for this article is available online at https://doi.org/10.1080/00397911.2020.1843179
ß 2020 Taylor & Francis Group, LLC

2
A. H. MOUSTAFA
Introduction
Dithiocarbazates (DTCs) possessing both hydrazino and thione groups, are the active
and the interesting arrangement structures for many scientists.[1] Their S-substituted are
easily synthesized via one-pot multicomponent reaction of hydrazine hydrate, carbon
disulfide and alkyl halides in aqueous basic medium.[2,3] They are valuable raw materials
for the preparation of carbothiohydrazides,[4,5] carbothiohydrazones[6–8] and various
aza-heterocyclic compounds such as pyrazoles,[2,9,10] 1,3,4-thiadiazoles,[11,12] 1,2,4-triazo-
les,[2]pyrazolo[1,5-a][1,3,5]triazines.[13,14]
Further, the 1,3,4-thiadiazole nucleus, which makes up the azole group, has a versatile
application in medicinal, agricultural, and materials chemistry.[15–19] Their derivatives
exhibit a wide variety of biological activities including antimicrobial,[20,21] anticonvul-
sant,[22] antioxidant,[23] antiparasitic,[24] antituberculosis,[25] antileishmanial,[26] anti-
inflammatory,[27] antidepressant,[28] anticancer[29] and antiviral agents.[30] They also
have gained great attention due to the large number of their reported diverse synthetic
methods[16,31] for example: (i) via cyclization of thiosemicarbazides,[32,33] thiosemicarba-
zones,[34] aldehyde methylthio (thiocarbonyl) hydrazones[35] or acylhydrazines[36,37]; (ii)
via transformation of 1,3,4-oxadiazoles.[38] In contrast to this, limited methods were
succeeded for preparing them from DTCs via the reaction with chloroacetylchloride,[12]
or hydrazonoyl bromide.[11]
On the other hand, pyrazole derivatives are found to be versatile compounds showing
widespread biological and pharmaceutical activities[39,40] such as: antimicrobial,[41] anti-
inflammatory,[42] analgesic,[43] antidiabetic,[44] antidepressant,[45] anticonvulsant,[45]
antiviral,[46] and anticancer activities.[47] Many derivatives containing pyrazole cores
have been applied in crop protection.[48]
Despite the large number of chemotherapeutics and antibiotics, the appearance of old
and new antibiotic-resistant bacterial strains represents a substantial need for the syn-
thesis and discovery of new safer and potent antimicrobial agents.[49]
In the light of the foregoing data and as continuation of our program of identifica-
tion of new biologically active leads,[50–57] the present work reports the new synthesis
and the antimicrobial evaluation of 2,3-dihydro-1,3,4-thiadiazole and pyrazole deriva-
tives starting from DTCs.
Results and discussion
Chemistry
Herein, a series of 3-acetyl-2-aryl-5-methylthio-2,3-dihydro-1,3,4-thiadiazoles 3a–g was
synthesized by heating of methyl/benzyl 2-benzylidenehydrazinecarbodithioate deriva-
tives 2a–g with acetic anhydride in polar aprotic solvent of N-methylpyrrolidone
(NMP) (Scheme 1). In this route, the starting materials thiocarbohydrazones 2a–g were
prepared according to the reported method carbothiohydrazones[7] and via Schiff base
[3,5]
condensation between methyl/benzyl hydrazinecarbodithioate 1a,b
with various aro-
matic aldehydes and/or ketones.
The formation of products 3a-g was produced through acid anhydride-catalyzed
intramolecular cyclization of intermediate 20a-g via nucleophilic lone pair addition of

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Scheme 1. The Synthetic route for the preparation of 2,3-dihydro-1,3,4-thiadiazoles 3a–g.
Scheme 2. Plausible mechanism for the formation of 3a–g using NMP and acetic anhydride.
sulfur at carbon Schiff base bond, followed by electrophilic acetylation at nitrogen Schiff
base bond with elimination of acetic acid molecule (Scheme 2). The simple cyclic amide
of NMP containing tertiary aliphatic amine is an excellent cleaning solvent and it can
use to facilitate the acetylation reactions through the formation of intermediate I
(Scheme 2).[58,59]
The chemical structures of the new 2,3-dihydro-1,3,4-thiadiazoles 3a-g were con-
firmed based on their spectral (IR, 1H, 13C NMR) and elemental analyses (see
Experimental part & Supporting Information). For example, the IR spectrum of 3 g
showed a characteristic absorption band at 1662 cmꢀ1 for C¼O; 2,90,62,92,82,949 cmꢀ1
1
for the aliphatic C–H and 3,00,83,052 cmꢀ1 for the aromatic C–H. Its H NMR spec-
trum showed the presence of two singlet signals at d 2.23 and 3.75 ppm characteristic of
methyl and methoxy groups, respectively; two doublet signals at d 6.87–6.90 and
7.42–7.44 ppm for four aromatic protons with coupling constant J ¼ 8.6 and 7.0 Hz,
respectively; also it exhibited doublet of doublets signals at d 4.36–4.45 ppm with cou-
pling constant J ¼ 7.9, 13.6 Hz due to methylene group; and two multiplet signals at d
7.13–7.15 and 7.30–7.37 ppmdue to six protons of aromatic and methine-SP3 group.
The 13C NMR spectrum of 3g showed ten signals at d 114.4, 127.3, 128.0, 128.9, 129.5,
133.2, 137.1, 149.4, 159.7, 167.8 ppm, which are assigned to carbonyl group and aro-
matic carbons; two signals at d 22.6, 55.6 ppm due to methyl and methoxy groups,

4
A. H. MOUSTAFA
Scheme 3. Synthesis of dihydro-1,3,4-thiadiazoles 5a–e.
respectively; while carbons of methylene and methine–SP3 groups are characterized by
signals at d 37.1 (disappeared with DEPT-135) and 69.7 ppm, respectively.
In the same manner, a new series of N- (4-acetyl-5-aryl-4,5-dihydro-1,3,4-thiadiazol-
2-yl) acetamide derivatives 5a–e was produced by the heating of benzaldehyde,
4-chloro- or 4-methoxybenzaldehyde N-phenylthiosemicarbazones 4a–c, 4-chlorobenzal-
dehyde N-benzylthiosemicarbazone 4d and/or 4-methoxybenzaldehyde N- (2-phenyl-
ethyl) thiosemicarbazone 4e in a mixture of acetic anhydride and NMP, respectively
(Scheme 3). The structures of the newly synthesized compounds 5a–e were confirmed
1
by their spectral (IR, H, 13C NMR) and elemental analyses (see Experimental Part &
Supporting Information).
In light of these results, the opportunity to use this strategy to synthesize the new spiro-
dihydro-1,3,4-thiadiazoles can be pursued. Thus 1,30-diacetyl-50- (methylthio) -30H-spiro[in-
dole-3,20-[1,3,4]thiadiazol]-2 (1H) -one (7) was produced by heating of methyl 2-(2-oxo-1,2-
[8]
dihydro-3H-indol-3-ylidene) hydrazinecarbodithioate (6)
in NMP/acetic anhydride
(Scheme 4). The analytical data supports the structures (see Experimental Part &
Supporting Information).
On the other hand, reaction of bis (methylthio) methylene malononitrile 8 with
methyl hydrazinecarbodithioate 1a and/or benzyl hydrazinecarbodithioate 1 b was previ-
ously described[60] giving polyfunctionalized-pyrazoles 9a,b, respectively (Scheme 5).
Using this synthetic strategy is suitableto synthesize the new 5-amino-3- (methylthio)
-1-substituted-1H-pyrazole-4-carbonitrile derivatives 12a–d via reaction of bis (methyl-
thio) methylene malononitrile 8 with carbothiohydrazides 11a–d, which prepared
through reported procedure via reaction of 1a with primary/secondary amines
10a–d,[4,5] respectively (Method A, Scheme 5). Formation of the products 9a,b and
12a–d has been confirmed by their spectral IR, NMR and elemental analyses.
Compound 12c was also confirmed using melting point comparison with reported syn-
thesis by another method.[60] Also the structures of the synthesized compounds 12a–d
were chemically confirmed by their preparation through another route via the
reaction of 9a with primary/secondary amines 10a–d namely, dimethylamine, phenyle-
thylamine, morpholine, and 1- (4-methoxyphenyl) piperazine, respectively (Method B,
Scheme 5).

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5
Scheme 4. Synthesis of 1,3’-diacetyl-5’-(methylthio)-3’H-spiro[indole-3,2’-[1,3,4]thiadiazol]-2(1H)-
one (7).
Scheme 5. The Synthetic route for the preparation of polyfunctionalized-pyrazole derivatives 9a,b
and 12a–d.
IR spectrum of compound 12d showed absorption peaks at 1616 cmꢀ1 for C¼N;
2215 cmꢀ1 for CꢁN; 2819, 2921, 2952 cmꢀ1 for C–H aliphatic; 3032 cmꢀ1 for C–H aro-
matic; and 3,30,03,393 cmꢀ1 for NH2 group. 1H NMR spectrum of compound 12d
showed the presence of four singlet signals at d 2.50, 3.23, 3.71 and 7.18 ppm character-
istic of SCH3, two CH2, OCH3 and NH2 (exchangeable with D2O) groups, respectively;
broad singlet signal at d 4.01 ppm for other two methylene groups of piperazine; also it
exhibited two doublet signals at d 6.84–6.87 and d 6.92–6.94 ppm with coupling

6
A. H. MOUSTAFA
constant J ¼ 8.9 Hz for phenylene protons. Its 13C NMR spectrum showed nine peaks at
d 73.9, 113.6, 115.1, 118.3, 144.9, 150.7, 154.1, 154.5, 176.0, which are assigned to SP2
and SP carbon atoms; while the two methyl carbons (SCH3, OCH3) and four methylene
carbons were characterized by peaks at d 13.6, 49.8, 51.2 and 55.9 ppm.
Antimicrobial evaluation
The in vitro antimicrobial activity of newly synthesized 2,3-dihydro-1,3,4-thiadiazoles
3a–g, 5a–e, 7 and polyfunctionalized-pyrazoles 9a,b, 12a–d was evaluated against
Staphylococcus aureus (ATCC9027) Escherichia coli (ATCC6538) and Candia albicans
(ATCC10231) using well diffusion method[15,61–63] and the results are presented in
Table 1. Among the compounds tested, the spiro-compound 7, was found to be the
most active against both the Gram-positive (S. aureus) and the Gram-negative (E. coli)
bacteria with inhibition zone 20 and 15 mm, respectively. However, compound 7 did
not show significant antifungal activity against C. albicans.
Regarding 3-acetyl-2-aryl-5-methylthio-2,3-dihydro-1,3,4-thiadiazoles derivatives
3a–g, the antimicrobial screening showed that among this series compounds 3a, 3b,
and 3c are the most active. Compound 3b showed the highest inhibition zone 18
and 20 mm against both the Gram-positive (S. aureus) and the Gram-negative (E.
coli) bacteria, respectively. Compound 3c exhibited strong activity against Gram-
negative (E. coli) bacteria with 18 mm inhibition zone and moderate activity against
the Gram-positive (S. aureus) bacteria with 12 mm inhibition zone. While compound
3a exerted moderate activity against both S. aureus and E. coli with inhibition
zone 12 mm. furthermore, compound 3e and 3 g showed weak activity against the
Gram-negative (E. coli) bacteria only with inhibition zone 8 mm. With respect to the
antifungal activity, all derivatives of this series did not exhibit notable antifun-
gal activity.
Ongoing through the results of N- (4-acetyl-5-aryl-4,5-dihydro-1,3,4-thiadiazol-2-yl)
acetamide derivatives 5a–e, the antimicrobial investigation revealed that compound 5b
has strong activity against Gram-negative (E. coli) bacteria with 18 mm inhibition zone
and moderate activity against the Gram-positive (S. aureus) bacteria with 12 mm inhib-
ition zone. In addition, 5e has a moderate activity against both S. aureus and E. coli
with inhibition zone 15 and 12 mm, respectively, and weak antifungal activity against C.
albicans with 7 mm inhibition zone. Compounds 5a, 5c and 5d did not exhibit notable
antibacterial activity, however, 5c showed weak antifungal activity against C. albicans
with 6 mm inhibition zone. Finally, among the pyrazole derivatives 9a,b and 12a–d,
compound 12d exhibited strong activity against Gram-negative (E. coli) bacteria with
20 mm inhibition zone and moderate activity against the Gram-positive (S. aureus) bac-
teria with 12 mm inhibition zone without any notable antifungal activity. Also, com-
pound 12c showed a moderate activity against both S. aureus and E. coli with inhibition
zone 12 mm and did not exhibit notable antifungal activity. Additionally, compound
12b showed weak activity against Gram-negative (E. coli) bacteria with 8 mm inhibition
zone and did not exert any activity against the Gram-positive (S. aureus) bacteria or
against C. albicans. Compounds 9a, b, and 12a did not exhibit notable antimicro-
bial activity.

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7
Table 1. The in vitro antimicrobial activity of 2,3-dihydro-1,3,4-thiadiazoles 3a–g, 5a–e, 7 and poly-
functionalizedpyrazoles 9a,b and 12a–d.
Compound
R2
Inhibition Zone diameter (mm)
S. A. E. C. C. A.
No.
R
R1
n
3a
3b
3c
3d
3e
3f
3g
5a
5b
5c
5d
5e
7
9a
9b
12a
12b
12c
12d
Cipro
Fluc
Me
Me
Me
Me
Bn
Bn
Bn
H
Cl
MeO
Cl
MeO
—
Me
Bn
—
H
H
H
Me
H
H
H
Cl
MeO
Cl
H
Cl
MeO
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
0
0
0
1
2
—
—
—
—
—
—
—
12
18
12
0
0
0
0
0
12
0
0
15
20
0
0
0
12
20
18
0
8
0
8
0
18
0
0
12
15
0
0
0
0
0
0
0
0
0
0
0
0
6
0
7
0
0
0
0
0
H
—
—
—
—
—
—
—
—
Me
H
Me
—
—
—
ꢀCH2CH2Ph
0
8
R1R2N-: 4-morphinyl
—
—
31
—
12
20
31
—
0
0
—
25
R1R2N-: 1-(4-methoxyphenyl)-4-piperazinyl
C.A.: Candida albicans; Cipro: ciprofloxacin; E. C.: Escherichia coli; Fluc.: fluconazole; S. A.: Staphylococcus aureus.
Docking studies
The docking simulation experiments were performed using the bacterial DNA gyrase
structure with the most active of newly synthesized compounds 3b, 7, and 12d. The
DNA gyrase structure was obtained from RCSB Protein data base (PDB ID: 4URO).
DNA gyrase is a unique type II topoisomerase which is responsible for the super-coiling
activity of DNA in bacteria.[64,65] We used the CDOCKER docking protocol, embedded
in the Discovery Studio software 2.5 (San Diego, USA).
The docking results revealed that compound 3b, nicely bound to the substrate bind-
ing pocket of 4URO (Figure 1) via incorporation of four hydrogen bonds with Arg84,

8
A. H. MOUSTAFA
Figure 1. 3D and 2D docking and binding pattern of compound 3b (cyan) into the active site of
DNA gyrase (PDB entry: 4URO).
Figure 2. 3D and 2D docking and binding pattern of compound 7 (blue) into the active site of DNA
gyrase (PDB entry: 4URO).
Gly85, Arg144 and Thr173. In addition to five hydrophobic interactions with Glu58,
Arg84, Pro87 and Ile102 and this may explain the high antibacterial activity of com-
pound 3b.
Compound 7 engaged in two hydrogen bonds, one with Arg84 and Arg144.
Additionally, compound 7 forms one hydrophobic interactions with Ile86 as shown in
Figure 2.
Moreover, docking analysis of compound 12d showed that it forms three hydrogen
bonds with Gly85, Gln91, and Thr173 and seven hydrophobic interactions with the
amino acid residues Gly83, Arg84, Ile86, Pro87, Ala98, and Ile102 (Figure 3).
Interestingly, these theoretical docking results are in good agreement with experimental
results which shows that 3b, 7, and 12d may act as potent inhibitors of theDNA gyrase.

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9
Figure 3. 3D and 2D docking and binding pattern of compound 12d (violet) into the active site of
DNA gyrase (PDB entry: 4URO).
Experimental
Chemistry
All commercially available reagents were purchased from Aldrich, Merck and Fluka
and were used without further purification. For more details, see Supporting
Information.
General procedure for the synthesis of 3-acetyl-2-aryl-5-methylthio-2,3-dihydro-
1,3,4-thiadiazoles (3a-g);N- (4-acetyl-5-aryl-4,5-dihydro-1,3,4-thiadiazol-2-yl)
acetamide derivatives (5a–e) and 1,3’-diacetyl-5’- (methylthio) -3’H-spiro[indole-
3,2’-[1,3,4]thiadiazol]-2 (1H) -one (7)
To a solution of thiocarbohydrazones 2a–g, 4a–e, 6 (2 mmole) in 10 mL N-methylpyrro-
lidone (NMP), aceticanhydride (20 mmole, 1.9 mL) was added and there action mixture
was heated and stirred insteam bath for 2 h. After complement of there action (moni-
tored with TLC), there action mixture was then cooled to room temperature, poured
into crushed ice and neutralized by ammonium hydroxide. The formed precipitate
was collected by filtration, washed by distilled water, dried, and recrystallized
from ethanol.
3-Acetyl-5- (benzylthio) -2- (4-methoxyphenyl) -2,3-dihydro-1,3,4-thiadiazole (3 g):
Yield 82%; beige solid; m.p.: 65–67 ꢂC. IR (ATR) ꢀmax 3052, 3008 (CH aromatic), 2949,
1
2928, 2906 (CH aliphatic), 1662 (C¼O) cmꢀ1; H NMR (400 MHz, DMSO-d6) d (ppm):
2.23 (s, 3H, CH3), 3.75 (s, 3H, OCH3), 4.36–4.45 (dd, J ¼ 7.9, 13.6 Hz, 2H, CH2),
6.87–6.90 (d, J ¼ 8.6 Hz, 2H, CHarom.), 7.13–7.15 (m, 3H, N–CH þ 2CHarom.), 7.30–7.37
(m, 3H, CHarom.), 7.42–7.44 (d, J ¼ 7.0 Hz, 2H, CHarom.); 13C NMR (100 MHz, DMSO-
d6) d (ppm): 22.6, 37.1 (exchangeable with DEPT-135), 55.6, 69.7, 114.4, 127.3, 128.0,
128.9, 129.5, 133.2, 137.1, 149.4, 159.7, 167.8. Elemental Analysis Calcd. (%) for
C18H18N2O2S2 (358.47): C, 60.31; H, 5.06; N, 7.81. Found: C, 60.21; H, 4.89; N, 7.76.

10
A. H. MOUSTAFA
General procedure for the synthesis of 5-amino-3-(methylthio)-1-substituted-1H-
pyrazole-4-carbonitrile derivatives (12a–d)
ꢃ
Method A: A mixture of bis (methylthio) methylene malononitrile 8 (0.34g,
2mmol) and carbothiohydrazides 11a–d (2mmol) was refluxed indioxane for 2h
(monitored by TLC). A fter cooling the formed precipitate was collected by
filtration, dried and recrystallized from dioxanetoafford 12a–d.
ꢃ
Method B: A mixture of methyl 5-amino-4-cyano-3-(methylthio)-1H-pyrazole-1-
carbodithioate 9a (0.49, 2 mmol) and primary/secondary amines 10a–d
(2 mmol) was refluxed indioxane for 4h (monitored by TLC). A fter cooling the
formed precipitate was collected by filtration, dried and recrystallized from
dioxane to afford 12a–d.
5-Amino-1-f[4-(4-methoxyphenyl) piperazin-1-yl]carbonothioylg-3-(methylthio)-1H-
pyrazole-4-carbonitrile (12d):
Yield (method A: 92%, method B: 87%); gray solid; m.p.: 198–200 ꢂC. IR (ATR)) ꢀmax
3393, 3300 (NH2), 3032 (CH aromatic), 2952, 2921, 2819 (CH aliphatic), 2215 (CꢁN),
1
1616 (C¼N) cmꢀ1; H NMR (400 MHz, DMSO-d6) d (ppm): 2.50 (s, 3H, SCH3), 3.23
(s, 4H, 2CH2), 3.71 (s, 3H, OCH3), 4.01 (br. s, 4H, 2CH2), 6.84–6.87 (d, J ¼ 8.9 Hz, 2H,
CHarom.), 6.92–6.94 (d, J ¼ 8.9 Hz, 2H, CHarom.), 7.18 (s, 2H, NH2, disappeared by
D2O); 13C NMR (100 MHz, DMSO-d6) d (ppm): 13.6, 49.8, 51.2, 55.9, 73.9, 113.6 (CN),
115.1, 118.3, 144.9, 150.7, 154.1, 154.5, 176.0. Elemental Analysis Calcd. (%) for
C17H20N6OS2 (388.51): C, 52.56; H, 5.19; N, 21.63. Found: C, 52.84; H, 4.93; N, 21.44.
Biological activity
Antibacterial and antifungal activities
The in vitro antibacterial and antifungal activities of the newly synthesized 2,3-dihydro-
1,3,4-thiadiazoles 3a–g, 5a–e, 7 and polyfunctionalized-pyrazoles 9a,b and 12a–d were
screened using the well diffusion method.[15,61–63] For more details, see Supporting
Information.
Docking methodology
Discovery Studio 2.5 software (Accelrys Inc., San Diego, CA, USA) was used for dock-
ing analysis.[66,67] For more details, see Supporting Information.
Conclusion
A series of 3-acetyl-2-aryl-5-methylthio-2,3-dihydro-1,3,4-thiadiazoles 3a–g, N-(4-acetyl-
5-aryl-4,5-dihydro-1,3,4-thiadiazol-2-yl) acetamide derivatives 5a–e and 1,30-diacetyl-50-
(methylthio)-30H-spiro[indole-3,20-[1,3,4]thiadiazol]-2 (1H)-one (7) was produced by
heating of thiosemicarbazone derivatives 2a–g, 4a–e, 6 in a mixture of NMP/acetic
anhydride, respectively. Also, a series of 5-amino-3-(methylthio)-1-substituted-1H-pyra-
zole-4-carbonitrile derivatives 12a–d was produced from bis (methylthio) methylene

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11
malononitrile 8, using two synthetic pathways. In addition, all synthesized compounds
were screened for their antimicrobial activity against Staphylococcus aureus
(ATCC9027) Escherichia coli (ATCC6538) and Candia albicans (ATCC10231) by means
of paper disk diffusion method (9 mm) on Muller Hinton agar. Some of them were
found to possess antibacterial activity and exhibited moderate-to-good activity. The
results revealed that compounds 3b, 7, and 12d are the most potent and elicited
remarkable antibacterial activity against the Gram-positive (S. aureus) and the Gram-
negative (E. coli) bacteria compared to ciprofloxacin as a reference drug. The molecular
docking results of 3b, 7, and 12d suggested that they may act as potent inhibitors of
theDNA gyrase.
1
Full experimental detail, H and 13C NMR spectra. This material can be found via
the “Supplementary Content” section of this article’s webpage.
Acknowledgments
The authors thank Dr. EsamRashwan, Head of the confirmatory diagnostic unit VACSERA,
Egypt, for carrying out the in-vitro antimicrobial screening. This research did not receive any
specific grant from any funding agencies.
Disclosure statement
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ORCID
Amr Hassan Moustafa
http://orcid.org/0000-0001-7242-6527
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