Reactions with hydrazonoyl halides 591: Synthesis and antimicrobial activity of 2,3-dihydro-1,3,4-thiadiazole, triazolino[4,3-a]pyrimidine, and pyrimido[1,2-b][1,2,4,5]tetrazin-6-one containing benzofuran moiety

Article abstract of DOI:10.1080/10426500701734265

2,3-Dihydro-1,3,4-thiadiazole, triazolino[4,3-a]pyrimidine and pyrimido[1,2-b][1,2,4,5]tetrazin-6-one containing benzofuran Moiety were synthesized from C-benzofuran-2-yl-N-phenylhydrazonoyl bromides, and the appropriate alkyl arylidenehydrazinecabodithioates and pyrimidine-2-thione and N-aminopyrimidine-2-thione, respectively. All structures of the newly synthesized compounds were elucidated by elemental analysis, spectral data, and alternative synthetic methods whenever possible. Newly compounds are capable of high inhibiting the growth of bacteria (gram positive and gram negative). Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/10426500701734265

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Phosphorus, Sulfur, and Silicon
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Reactions With Hydrazonoyl
Halides 59: Synthesis and
Antimicrobial Activity of 2,3-
Dihydro-1,3,4-thiadiazole,
Triazolino[4,3-a]pyrimidine,
and Pyrimido[1,2-b]
[1,2,4,5]tetrazin-6-one
Containing Benzofuran Moiety
Abdou O. Abdelhamid a , Mahmoud A. Mohamed b &
Yasser H. Zaki c
a Department of Chemistry, Faculty of Science ,
Cairo University , Giza, Egypt
b Department of Textile, Faculty of Industrial
Education , Beni-Suef University , Egypt
c Department of Chemistry, Faculty of Science ,
Beni-Suef University , Egypt
Published online: 24 Jun 2008.
To cite this article: Abdou O. Abdelhamid , Mahmoud A. Mohamed & Yasser H. Zaki
(2008) Reactions With Hydrazonoyl Halides 59: Synthesis and Antimicrobial Activity
of 2,3-Dihydro-1,3,4-thiadiazole, Triazolino[4,3-a]pyrimidine, and Pyrimido[1,2-b]
[1,2,4,5]tetrazin-6-one Containing Benzofuran Moiety, Phosphorus, Sulfur, and Silicon
and the Related Elements, 183:7, 1746-1754, DOI: 10.1080/10426500701734265
To link to this article: http://dx.doi.org/10.1080/10426500701734265

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Phosphorus, Sulfur, and Silicon, 183:1746–1754, 2008
Copyright © Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500701734265
Reactions With Hydrazonoyl Halides 591: Synthesis and
Antimicrobial Activity of 2,3-Dihydro-1,3,4-thiadiazole,
Triazolino[4,3-a]pyrimidine, and
Pyrimido[1,2-b][1,2,4,5]tetrazin-6-one Containing
Benzofuran Moiety
Abdou O. Abdelhamid,1 Mahmoud A. Mohamed,2
and Yasser H. Zaki3
1Department of Chemistry, Faculty of Science, Cairo University,
Giza, Egypt
2Department of Textile, Faculty of Industrial Education, Beni-Suef
University, Egypt
3Department of Chemistry, Faculty of Science, Beni-Suef University,
Egypt
2,3-Dihydro-1,3,4-thiadiazole, triazolino[4,3-a]pyrimidine and pyrimido[1,2-
b][1,2,4,5]tetrazin-6-one containing benzofuran Moiety were synthesized from
C-benzofuran-2-yl-N-phenylhydrazonoyl bromides, and the appropriate alkyl aryli-
denehydrazinecabodithioates and pyrimidine-2-thione and N-aminopyrimidine-
2-thione, respectively. All structures of the newly synthesized compounds were
elucidated by elemental analysis, spectral data, and alternative synthetic methods
whenever possible. Newly compounds are capable of high inhibiting the growth of
bacteria (gram positive and gram negative).
Keywords 2,3-Dihydro-1,3,4-thiadiazole; hydrazonoyl bromide; pyrimido[1,2-b]
[1,2,4,5]tetrazin-6-one; triazolino[4,3-a]pyrimidine
INTRODUCTION
Benzofuran are very important compounds due to their broad spectrum
of biological and pharmacological effects. Benzofuran are considered
non-steroidal anti-inflammatory drugs (NSAID), where the action of
(NSAID) is lowering the prostaglandin production through inhibition of
cyclooxygenase (COX). Benzofuran are among the COX-2 inhibitors.2,3
In addition, diverse pharmacological properties have been associated
with benzofuran derivatives.4−8 These include pesticidal,9 fungicidal,
Received 17 July 2007; accepted 4 September 2007.
Address correspondence to Abdou O. Abdelhamid, Department of Chemistry, Faculty
of Science, Cairo University, Giza 12613, Egypt. E-mail: abdelhamid45@gmail.com
1746

Reactions With Hydrazonoyl Halides 59
1747
antimicrobial, antioxidant,10 anti-inflammatory,11 antihistaminic,12
antiallergic,13 antitumar,14 anticonvulsant, and antinociceptive15
agent. We report here several heterocyclic compounds benzofuran moi-
ety expected to possess biological activity.
RESULTS AND DISCUSSION
Treatment of C-(2-benzofuranyl)-N-phenylhydrazonoyl bromide (1)
with the appropriate alkyl carbodithioates16−18 3(a–e) or 4 (a–
e) in ethanol containing triethylamine afforded 2,3-dihydro-1,3,4-
thiadiazoles 7(a–e), respectively (Scheme 1). Structures 7 were con-
firmed by elemental analysis, spectral data (cf. Experimental).
SCHEME 1
In the light of the foregoing results, the mechanism outlined in
Scheme 1 seems to be the most plausible pathway for the formation
of 7 from the reaction of the 1 with 3 or 4. The reaction involves ini-
tial formation of thiohydrazonate 5, which undergoes to yield the in-
termediate 6 or via 1,3-dipolar cycloaddition of nitrilimine 2, (which
was prepared in situ from 1 with triethylamine) to C S double bond
of 3 (or 4). The formation of 5 and 6 are similar to the reaction of hy-
drazonoyl chloride with 1-phenyl-1,4-dihydrotetrazole-5-thione19 and
5-phenyl-1,3,4-thiadiazole-2(3H)-thione.20
Analogously, 1 reacted with each of 3-{aza-[(methylthioxomethyl)-
amino]methylene}indoline-2-one,21 3-{aza-[(methylthioxomethylamino]

1748
A. O. Abdelhamid et al.
methylene}-indan-1,3-dione,22 methyl 1-(4-isopropylphenyl)ethyl-
idenedithiohydrazono-carbodithioate23 and methyl, (1,3-benzodioxol-
4-yl)ethylidenedithiohydrazono-carbodithioate23 to give 2-{1,2-diaza-
2-[5-(benzo[d]furan-2-yl)carbonyl]-3-phenyl-(1,3,4-thiadiazolin-2-ylid-
ene}indane-1,3-dione (9), 3-{1,2-diaza-2-[5-(benzo[d]furan-2-yl)carbo-
nyl]-3-phenyl-(1,3,4-thiadiazolin-2-ylidene}indolin-2-one (10), 2-{1,2-
diaza-3-[4-(methylethyl)phenyl]prop-2-enylidene}-3-phenyl(1,3,4-
thiadiazolin-5-yl)benzo[d]furan-2-ylketone (11) and 2-(3-(2H)-benzo
[d]1,3-dioxolan-4-yl)-1,2-diazaprop-2-enylidene)-3-phenyl(1,3,4-thiadi-
azolin-5-yl)benzo[d]furan-2-ylketone (12) (Scheme 2).
SCHEME 2
Also, treatment of 1 with each of the pyrimidine-2-thione 13 and
20 in boiling chloroform to give triazolino[4,3-a]pyrimidines in a good
yields 17 and 21, respectively (Scheme 3). The structure of 17 was
elucidated by elemental analysis, spectral data, and alternative syn-
thesis route. Thus, 1H NMR spectrum of 17 showed signals at δ =
1.23 (t, 3H, CH2CH3), 2.56 (s, 3H, CH3), 4.09 (q, 2H, CH2CH3), 5.05
(s, 1H, pyrimidine H-4), 7.16–7.25 (m, 3H, thiophene protons), 7.44–
7.72 (m, 7H, ArH’s), 8.05 (s, 1H, benzofuran H-4), and 8.24 (d, J =
8Hz, 2H, ArH’s). Its IR spectrum revealed bands at 1702 (CO ester),
1650 (CO conjugated) and 1615 (C N). Also, compound 17 was ob-
tained from the reaction of ethyl 6-methy-2-methylthio-4-(2-thienyl)-
3,4-dihydropyrimidine-5-carboxylate 18 with 1 in boiling sodium ethox-
ide solution. The mechanism outlined in Scheme 3 seems to be the
most plausible pathway for the formation of 17 from the reaction
of 1 with 13 or 18. Two possible pathways can account for the for-
mation 17: 1)- 1,3- addition of the thiol tautomer 13A to the nitril-
ium imide 2 to give the thiohydrazonate ester 14 which undergoes

Reactions With Hydrazonoyl Halides 59
1749
SCHEME 3
nucleophilic cyclization to yield spiro compounds 15. The latter ring
open to 16 which cyclized to yield 17 by loss hydrogen sulfide; and 2)-
1,3-cycloaddition of nitrilium imide 2 to C S double bond of 13 can give
directly 16 (Scheme 3). All attempts to isolate any intermediates are
unsuccessful.
Treatment of 1 with 3-amino-6-phenyl-2-thioxo-2,3-dihyro-1H-
pyrimidine-4-one24 (22) in boiling ethanol containing triethylamine
gave
3-(4-methyl-2-phenyl)thiazol-5-oyl-1,7-diphenyl-4a-hydro-4H-
pyrimidino[1,2-b]1,2,4,5-tetrazin-5-one (25), respectively (Scheme 4).
Structure 25 was based on spectral and microanalysis data. IR spec-
trum of 25 revealed bands at 3290 and 1680 cm−1 due to NH and CO
groups, respectively. Its 1H NMR spectrum showed signals at δ = 6.84
(s, 1H, pyrimidine H-5), 6.42-7.54 (m, 15H, ArH’s) and 8.52 (s, br., 1H,
NH). 13C NMR spectrum of 25 showed 23 signals: δ = 152 (benzofuran

1750
A. O. Abdelhamid et al.
SCHEME 4
C-2), 116 (benzofuran C-3), 131 (benzofuran C-3a), 121, 123, 124, 111
(benzofuran C-4, C-5, C-6, C-7), 161 (benzofuran C-7a), 154 (tetrazine
C-3), 163 (tetrazine C-5 or pyramidine C-2), 110 (pyrimidine C-5), 156
(pyramidine C-6), 126, 128, 136 (phenyl attach pyrimidine ring), 116,
118, 129, 144 (phenyl attach to tetrazine ring), 159, 178 (2 C O).
Formation of 25 from reaction of hydrazonoyl bromide 1 with ei-
ther 22a or 22b, it is suggested that the reaction starts with the
formation of amidrazone 23 followed by cyclization to 24 to give
the product 25 via elimination of hydrogen sulfide or methanethiol
(Scheme 4).
Antimicrobial Activity
The tested microorganism was gram +ve bacteria, gram −ve bacte-
ria and some Fungal-plant. Sensitivity of the selected microorgan-
isms to some synthesized compounds were determined in vitro cul-
ture that were dissolved in chloroform, the tests were carried out
using the filter paper and hole plate method.25,26 Studies on the bi-
ological activity of compounds in comparison with Chlorumphinecol
and Terbinafin showed in Table I. In general, all tested compounds
were capable of a high inhibiting the growth of gram positive and
gram negative. Also, showed the tested compounds were a high in-
hibition towards Candida albicans (Fungus) and negative Aspergills
flvus (Fungus).

Reactions With Hydrazonoyl Halides 59
1751
TABLE I Response of Various Microorganisms to Some Synthesized
Compounds in vitro (Culture)
Bacillus
Aspergills Candida
flvus albicans
Microorganisms subtilis Echerichia Staphylococcus Streptococcus
/compound no.
(G+)
coli (G−)
albus (G+)
faecalis (G+) (Fungus) (Fungus)
7a
7b
7c
7d
7e
9
10
11
12
17
21
25
13
13
13
12
13
12
12
12
13
12
12
12
14
13
13
13
12
13
13
13
14
12
12
12
14
14
14
11
13
12
14
13
14
13
13
12
13
12
13
13
13
13
13
14
13
13
13
12
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
14
15
13
12
13
13
13
12
14
13
13
12
Reference standard; chlorumphinecol was used as a standard antibacterial agent;
and terbinafin was used as a slandered antifungal agent. Values show zone of inhibition
in mm. Diameter of the inhibition zones were: high (11–15 mm), moderate (6–10 mm),
slight (1–5 mm), and negative (0).
EXPERIMENTAL
All melting points were uncorrected. IR spectra were recorded (KBr
disc) on a Shimadzu FT-IR 8201 PC Spectrophotometer. 1H-NMR spec-
tra were recorded in CDCl3 or (CD3)3SO on a Varian Gemini 200 MHz
Spectrometer and chemical shifts were expressed in units using TMS
as an internal reference. Elemental analyses were carried out at the
Microanalytical Center, Cairo University, Giza, Egypt, and National
Research Centre. Hydrazonoyl bromide 1 was prepared as previously
reported in literature.27
2,3-Dihydro-1,3,4-Thiadiazoles 7a–e and 9–12
Triethylamine (0.5 g (0.75 ml), 5 mmol) was added dropwise with stir-
ring to a mixture of the appropriate alkyl carbodithioates 3a–e (or 4a–
e), 8a–d (5 mmol) and 1 (1.8 g, 5 mmol) in ethanol (20 mL). The resulting
solid, which formed after 30 min, was collected and recrystallized from
dioxin-ethanol to give 2,3-dihydro-1,3,4-thiadiazoles 7a–e and 9–12,
respectively, in a good yield (Tables II and III).

1752
A. O. Abdelhamid et al.
TABLE II Characterization Data of the Newly Synthesized
Compounds
Calcd./found (%)
Comp.
no.
Mp.◦C
(solvent)
Color
yield (%)
Mol. Formula
(mol. wt.)
C
H
N
S
7a
7b
7c
7d
7e
9
210
Dioxan-EtOH
195
Dioxan-EtOH
190
Dioxan-EtOH
190
Dioxan-EtOH
180
Dioxan-EtOH
264
Dioxan-EtOH
>300
Dioxan-EtOH
175
Dioxan-EtOH
220
Red
87
Orange
85
Red
82
Orange
78
Brown
80
Red
84
Yellow
79
Orange
82
Brown
83
Orange
68
Yellow
74
Red
71
C24H16N4O2S
424.48
67.91 3.80
67.71 3.90
61.38 3.28
61.45 3.00
63.76 3.40
63.67 3.04
68.48 4.14
68.35 4.10
62.14 3.63
62.10 3.52
64.51 3.25
64.72 3.35
65.27 2.95
65.42 2.75
69.51 4.75
69.40 4.75
64.09 3.44
64.21 3.54
65.87 4.34
65.70 4.21
70.89 3.31
70.84 3.55
69.79 3.83
69.54 3.65
13.20
13.02
13.01 14.90
13.24 15.10
13.52
13.32
12.78
12.87
12.60 14.43
12.41 14.34
15.04
14.95
11.71
11.92
12.01
11.95
11.96
12.10
10.97
10.72
15.31
15.35
15.65
15.87
7.55
7.42
C
22H14N4O2S2
430.51
C22H14N4O3S
414.45
7.74
7.54
7.31
7.51
C
25H18N4O2S
438.51
C
23H16N4O2S2
444.54
C25H15N5O3S
465.49
6.89
6.75
6.70
6.85
6.87
6.68
6.84
6.95
6.28
6.48
10
11
12
17
21
25
C
26H14N4O4S
478.49
C27H22N4O2S
466.57
C
25H16N5O4S
468.49
Dioxan-EtOH
158
EtOH
285–290
Dioxan
C
28H22N4O4S
510.58
C
27H15N5O3
457.45
−
214–216
EtOH
C
26H17N5O3
447.46
−
1,2,4-Triazolo[4,3-a]pyrimidines 17, 21, and
Pyrimidino[1,2-b]1,2,4,5-tetrazin-5-one 25
Method A
An equimolar amount of the hydrazonoyl bromide 1, the appropriate
pyrimidine2-thione 13 (or 20), 22b and sodium ethoxide (5 mmol) in
ethanol (20 mL) was refluxed for 3 h. The reaction mixture was cooled
and the resulting solid was collected and recrystallized from ethanol to
give 17, 21, and 25, respectively (Tables II and III).
Method B
A mixture of the hydrazonoyl bromide 1 (1.8 g, 5 mmol), 13 (1.48 g,
5 mmol) or 22a (1.08 g, 5 mmol) and triethylamine (0.5 g, (0.75 mL),
5 mmol) in chloroform (20 mL) containing was refluxed for 10 hrs. Chlo-
roform was evaporated under reduced pressure and the residue solid

Reactions With Hydrazonoyl Halides 59
1753
TABLE III Spectral Data of Some Newly Synthesized Compounds
Comp. no
Spectral data
7a
7b
7c
7d
7e
9
1H NMR: δ = 7.01–7.59 (m, 15 H, ArH’s) and 8.47 (s, 1H, CH ).
1H NMR: δ = 6.48–7.59 (m, 13 H, ArH’s) and 8.35 (s, 1H, CH ).
1H NMR: δ = 6.48–7.59 (m, 13 H, ArH’s) and 8.42(s, 1H, CH ).
1H NMR: δ = 2.12 (s, 3H, CH3), 6.45–7.85 (m 15 H, ArH’s).
1H NMR: δ = 2.12 (s, 3H, CH3), 6.45–7.85 (m 13 H, ArH’s).
1H NMR: δ = 6.46–7.82 (m, 19H, ArH’s), 9.23 (s, br., 1H, NH).
1H NMR: δ = 7.39–8.37 (m, ArH’s).
10
11,
1H NMR: δ = 1.26 (d, 6H, J= 8 Hz, (CH3)2CH, 2.95 (sept., 1H,
(CH3)2CH), 7.31–7.81 (m, 10 H, ArH’s), 8.05 (d, 2H, ArH’s), 8.24 (s, 1H,
benzofuran H-4), 8.42 (s, 1H, CH ).
12
17
1H NMR: δ = 5.02 (s, 2H, OCH2O), 6.85 (d, 1H), 7.15 (d, 1H), 7.26–7.64
(m, 9 H), 7.77 (d, 1H), 8.04 (d, 1H), 8.23 (s, 1H, CH ).
1H NMR: δ = 1.23 (t, 3H, CH2CH3), 2.56 (s, 3H, CH3), 4.09 (q, 2H,
CH2CH3), 5.05 (s, 1H, pyrimidine H-4), 7.16–7.25 (m, 3H, thiophene
protons), 7.44–7.72 (m, 7H, ArH’s), 8.05 (s, 1H, benzofuran H-4) and
8.24 (d, J = 8Hz, 2H, ArH’s).
21
25
1H NMR: δ = 6.46-7.82 (m, ArH’s).
1H NMR: δ = 6.84 (s, 1H, pyrimidine H-5), 6.46–7.72 (m, 15H, ArH’s),
8.52 (s, 1H, NH).
was crystallized from ethanol to give products identical in all aspects
(m.p., mixed m.p., and spectra) with corresponding products obtained
by Method A.
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