Reactions of hydrazonoyl halides 371: Synthesis of triazolo[4,3-a]pyrimidines, 1,3,4-thiadiazoles and 1,3,4-selenadiazoles

Article abstract of DOI:10.1080/10426500490422272

1,2,4-Triazolo[4,3-a]pyrimidines, thiadiazolines and selenadiazolines synthesized via reactions of hydrazonoyl halides with each of ethyl 4-(3,4-dimethoxyphenyl)-6-methyl-2-methylthio-3,4-dihydropyrimidine-5- carboxylate (or ethyl 6-(3,4-dimethylphenyl)-4-methyl-2-thio-1,3,6- trihydropyrimidine-5-carboxylate), ethyl 4-(2,3-dimethoxyphenyl)-6-methyl-2- methylthio-3,4-dihydropyrimidine-5-carboxylate, potassium thiocyanate, potassium selenocyanate, and carbodithioates respectively.

Full text of DOI:10.1080/10426500490422272

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REACTIONS OF HYDRAZONOYL HALIDES 371: SYNTHESIS
OF TRIAZOLO[4,3-a]PYRIMIDINES, 1,3,4-THIADIAZOLES
AND 1,3,4-SELENADIAZOLES
Abdou O. Abdelhamid a , Bassem A.M. Abdel-Wahab a & Ali A. Al-Atoom a
a Cairo University , Giza, Egypt
Published online: 12 Aug 2010.
To cite this article: Abdou O. Abdelhamid , Bassem A.M. Abdel-Wahab & Ali A. Al-Atoom (2004) REACTIONS OF HYDRAZONOYL
HALIDES 371: SYNTHESIS OF TRIAZOLO[4,3-a]PYRIMIDINES, 1,3,4-THIADIAZOLES AND 1,3,4-SELENADIAZOLES, Phosphorus,
Sulfur, and Silicon and the Related Elements, 179:3, 601-613, DOI: 10.1080/10426500490422272
To link to this article: http://dx.doi.org/10.1080/10426500490422272
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Phosphorus, Sulfur, and Silicon, 179:601–613, 2004
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Copyright Taylor & Francis Inc.
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500490422272
REACTIONS OF HYDRAZONOYL HALIDES 371:
SYNTHESIS OF TRIAZOLO[4,3-a]PYRIMIDINES,
1,3,4-THIADIAZOLES AND 1,3,4-SELENADIAZOLES
Abdou O. Abdelhamid, Bassem A. M. Abdel-Wahab,
and Ali A. Al-Atoom
Cairo University, Giza, Egypt
(Received June 6, 2003; accepted September 25, 2003)
1,2,4-Triazolo[4,3-a]pyrimidines, thiadiazolines and selenadiazolines
synthesized via reactions of hydrazonoyl halides with each of ethyl
4-(3,4-dimethoxyphenyl)-6-methyl-2-methylthio-3,4-dihydropyrimi-
dine-5-carboxylate (or ethyl 6-(3,4-dimethylphenyl)-4-methyl-2-thio-
1,3,6-trihydropyrimidine-5-carboxylate), ethyl 4-(2,3-dimethoxyphenyl)-
6-methyl-2-methylthio-3,4-dihydropyrimidine-5-carboxylate, potas-
sium thiocyanate, potassium selenocyanate, and carbodithioates
respectively.
Keywords: 1,3-Dipolar cycloaddition; 1,3,4-selenadiazoles; 1,3,4-
thiadiazoles; hydrazonoyl halides; triazolo[4,3-a]pyrimidines
1,3,4-Thiadiazoles have activities on many biological systems such
as: antitumor,2 hypoglycemic,3 antihistamine4 and anticholinergic
properties.5 Also hydrazonoyl halides have been used widely for the syn-
thesis of heterocyclic compounds.6−10 We report here the synthesis of
triazolo[4,3-a]pyrimidines, 2,3-dihydro-1,3,4-thiadiazoles, 2,3-dihydro-
1,3,4-selenadiazoles and unsymmetrical azines.
RESULTS AND DISCUSSION
The reaction of equimolar amount of ethyl 4-(3,4-dimethoxyphenyl)-
6-methyl-2-methylthio-3,4-dihydropyrimidine-5-carboxylate (1),11 C-
methoxycarbonyl-N-phenylhydrazonoyl chloride (2a), and sodium
ethoxide in boiling ethanol furnished exclusively the correspond-
ing methyl 4-(3,4-dimethoxyphenyl)-5-(ethoxycarbonyl)-6-methyl-1-
phenyl-4,3-dihydro-1,2,4-triazolo[4,3-a]pyrimidine-3-carboxylate (5a)
Address correspondence to Abdou O. Abdelhamid, Department of Chemistry, Faculty
of Science, Cairo University, Giza 12316, Egypt. E-mail: Abdou abdelhamid@yahoo.com
601

602
A. O. Abdelhamid et al.
in excellent yield. Structure 5a was elucidated by analytical, spectral
1
data, and alternative synthesis. H NMR spectrum showed signals at
δ 1.20 (t, 3H, CH2CH3), 2.53 (s, 3H, CH3), 3.82 (s, 3H, OCH3), 3.94
(s, 3H, OCH3), 3.95 (s, 3H, OCH3), 4.08 (q, 2H, CH2CH3), 6.70 (s, 1H,
CH), 6.91–6.97 (m, 3H, ArH), 7.28–7.51 (m, 3H, ArH) and 8.18 (d, 2H,
ArH). IR spectrum revealed peaks at ν = 1735 (CO), 1626 (C N) and
1604 cm−1 (C C).
On the other hand, ethyl 6-(3,4-dimethoxylphenyl)-4-methyl-2-thio-
1,3,6-trihydro-pyrimidine-5-carboxylate (7)12 reacted with 2a in boiling
chloroform in the presence of triethylamine gave a product identical in
all respects (m.p., mixed m.p., and spectra) with compound 5a. The
formation of 5a can be explained by 1,3-addition or 1,3-dipolar cycload-
dition of nitrile imide 6a (generated in situ by the treatment of hydra-
zonoyl chloride 2a with triethylamine) to 1 or 2. The intermediate 4a
was converted to 5a via elimination of methyl mercaptan (Scheme 1).
SCHEME 1
Similar, the appropriate hydrazonoyl halides 2a–g reacted with each
of 1a and 1b in boiling ethanolic sodium hydroxide gave triazolo[4,3-
a]pyrimidines 5a–g and 8a–g, respectively in a good yields.
Treatment of 2,3-dimethoxybenzoylbromide 4-nitrophenylhydra-
zone (9), which prepared by brominating of 2,3-dimethoxyphenyl-4-
nitrophenylhydrazone in acetic acid) with each of potassium thio-
cyanate and potassium selenocyanate in ethanol at room temperature

Reactions Hydrazonoyl Halides
603
SCHEME 2
afforded 5-(2,3-dimethoxyphenyl)-3-(4-nitrophenyl)-1,3,4-thiadiazolin-
2-imine (11a) and 5-(2,3-dimethoxyphenyl)-3-(4-nitrophenyl)-1,3,4-
selenadiazolin-2-imine (11b) (Scheme 2). The structure of 11 was eluci-
dated by elemental analyses, spectral data, alternative synthesis, and
chemical transformation. Thus, IR spectra of 11 revealed the presence
of the imino (NH) band near ν = 3280 and 1519, 1458 cm−1 (NO2). 1H
NMR spectrum of 11a showed signals at δ = 3.92 (s, 3H, OCH3), 3.93
(s, 3H, OCH3), 7.01–8.47 (m, 7H, ArH), and 9.15 (s, br., 1H, NH). Upon
shaking with D2O, a new singlet signal at δ = 4.72 ppm assignable to
DOH proton resonance and signals at δ = 3.92 (s, 3H, OCH3), 3.93 (s,
3H, OCH3), and 6.99–8.46 (m, 7H, ArH). Also, hydrazonoyl bromide
9 reacted with thiourea gave a product identical in all respects (m.p.,
mixed mp. and spectra) with 11a.
Two possible pathways can account for the formation of 11a: i) 1,3-
addition of thiol tautomer of thiourea to nitrilum imide (generated in
situ by treatment 9 with base) can give 12a, nucleophilic cyclization
to yield 13a. ii) Alternatively, 1,3-cycloaddition of the nitrilium imide
to the C S of thiourea can give 13a and then afforded 11a by loss of
ammonia (Scheme 2).

604
A. O. Abdelhamid et al.
Nitrosation of each 11a and 11b with sodium nitrite in acetic acid at
0–5◦C gave 1-[2-(aza-nitrosomethylene)-3-(4-nitrophenyl)(1,3,4-thia-
diazolin-5-yl)]-2,3-dimethoxybenzene (14a) and 1-[2-(aza-nitrosome-
thylene)-3-(4-nitrophenyl)(1,3,4-selenadiazolin-5-yl)]-2,3-dimethoxy-
benzene (14b) respectively. The structure 14 was confirmed by
elemental analysis, spectral data and thermolysis reaction (Scheme 3).
1
Thus, H NMR spectrum of 14a showed signals at δ = 3.93 (s, 3H,
OCH3), 3.95 (s, 3H, OCH3), and 7.04–8.52 (m, 7H, ArH). Its IR
spectrum showed no band at region ν = 3100–3400 cm−1 due to the
absence of NH group.13
SCHEME 3
Thermolysis of each 14a and 14b by boiling in xylene gave 5-(2,3-
dimethoxyphenyl)-3-(4-nitrophenyl)-1,3,4-thiadiazolin-2-one (15a) and
5-(2,3-dimethoxyphenyl)-3-(4-nitrophenyl)-1,3,4-selenadiazolin-2-one
(15b) respectively. Structure 15 was elucidated by elemental analysis
and spectral data. Thus, IR spectra of 15a,b revealed bands at near
1
ν = 1668 (CO) and 1514, 1473 cm−1 (NO2). H NMR spectrum of 15a
showed signals at δ = 3.93 (s, 3H, OCH3), 3.95 (s, 3H, OCH3), and
7.02–8.36 (m, 7H, ArH).
Acylation of each 11a and 11b with acetic anhydride or with
benzoyl chloride in pyridine yielded [5-(2,3-dimethoxyphenyl)-3-(4-
nitrophenyl)(1,3,4-thiadiazolin-2-ylidene)]acetamides (16a,b) and
[5-(2,3-dimethoxyphenyl)-3-(4-nitrophenyl)(1,3,4-selenadiazolin-2-yli-
dene)]benzamides (17a,b) respectively. Both elemental analysis and
spectral data of these products were consistent with their assigned
structures. Thus, IR spectra of 16a and 16a revealed the presence of α,
β-unsaturated acetyl band near ν = 1642 (CO) and 1610 (C N). The 1H

Reactions Hydrazonoyl Halides
605
NMR spectrum of 16a showed signals at δ = 2.39 (s, 3H, CH3CON ),
3.93 (s, 3H, OCH3), 4.03 (s, 3H, OCH3), and 7.04–8.50 (m, 7H, ArH).
However, hydrazonoyl bromide 9 reacts with each of alkyl
carbodithioate14−16 18a and 19a in ethanolic triethylamine at room
temperature afforded the same isolable product (m.p., mixed m.p.,
and spectra) and formulated as: 1-[2-((2Z)-1,2-diaza-3-phenylprop-2-
enylidene)-3-(4-nitrophenyl)-(1,3,4-thiadiazolin-5-yl)]-2,3-dimethoxy-
benzene (22a). Structure 22a was confirmed by elemental analyses and
spectral data. For example, IR spectrum of 22a revealed absorption
bands ν = 1514, 1470 cm−1 (NO2) group. Its 1H NMR spectrum showed
signals at δ = 3.93 (s, 3H, OCH3), 4.01 (s, 3H, OCH3), 7.01–8.58 (m,
12H, ArH), and 8.58 (s, 1H, CH). The formation of 22a is assumed
to proceed via 1,3-addition of thiol tautomer of carbodithioate 18a
or 19a to nitrilum imide (generated in situ by treatment of 9 with
triethylamine) can give 20a, nucleophilic cyclization to yield 21a.
Alternatively, 1,3-cycloaddition of nitrilium imide to the C S of
carbodithioate 18a or 19a can give 21a directly, and then afford 22a
by loss of alkyl mercaptan (Scheme 4).
SCHEME 4

606
A. O. Abdelhamid et al.
By similar route, the appropriate 18b–f or 19b–f reacts with hy-
drazonoyl bromide 9 in ethanolic triethylamine to give unsymmetrical
azines 22b–f respectively (Scheme 4).
Analogy, hydrazonoyl bromide 9 reacts with the appropriate 3-{aza-
[(methylthioxo-methyl)amino]methylene}indoline-2-one17 (23) or 3-
{aza-[(methylthioxo-methyl)amino]methylene}indane-1,3-dione10 (24)
to give unsymmetrical azines 25 and 26 respectively (Scheme 4).
Hydrazonoyl bromide 9 reacts with the appropriate cyanothioanilide
29a–c18−20 in ethanolic triethylamine at room temperature gave 1,3,4-
thiadiazoles 28a–c respectively. Structures 28a–c were confirmed by el-
emental analysis, spectral data, and alternative synthesis. Thus, treat-
ment of 9 with appropriate methyl carbodithioates 29a–c in ethanolic
triethylamine gave a product, in each case, identical in all respects
(m.p., mixed m.p., and spectra) with corresponding 28a–c (Scheme 5).
The formation of 28 can be explained by a stepwise path involving sub-
stitution to give amidrazone 27A, which readily converted to 28 via
elimination of aniline (Scheme 5).
SCHEME 5
Treatment of hydrazonoyl bromide 9 with methyl dithiocarbamate
30a21 in ethanolic triethylamine at room temperature afforded one
isolable product 33a. Structure 33a was confirmed by elemental analy-
sis, spectral data, and alternative synthesis. 1H NMR spectrum of 33a
showed signals at δ = 3.85 (s, 3H, OCH3), 3.90 (s, 3H, OCH3), and
6.99–8.57 (m, 12H, ArH). Thus, treatment of 9 with phenylthiourea
34a in ethanol gave a product identical in all respects (m.p., mixed

Reactions Hydrazonoyl Halides
607
SCHEME 6
m.p., and spectra) with 1-[2-(azaphenylmethylene)-3-(4-nitrophenyl)-
(1,3,4-thiadiazolin-5-yl)]-2,3-dimethoxybenzene (33a) (Scheme 6). For-
mation of 33 is assumed to proceed via 1,3-addition or 1, 3-dipolar cy-
cloaddition of methyl dithiocarbamate 30 to nitrilum imide can give
intermediate 31 and 32, respectively and then loss methyl mercaptain
(Scheme 6). Analogy, the hydrazonoyl bromide 9 reacts with the appro-
priate methyl dithiocarbamates 30b,c or the appropriate arylthiourea
34b,c to afford 2,3-dihydro-1,3,4-thiadiazole derivatives 33b,c respec-
tively (Scheme 6).
EXPERIMENTAL
All melting points were determined on an electrothermal apparatus and
are uncorrected. IR spectra were recorded (KBr discs) on a Shimadzu
1
FT-IR 8201 PC spectrophotometer. H NMR spectra were recorded in
CDCl3 and (CD3)2SO solutions on a Varian Gemini 300 MHz spectrom-
eter and chemical shifts are expressed in δ units using TMS as an in-
ternal reference. Elemental analyses were carried out at the Microan-
alytical Center of the Cairo University.
Synthesis of 1,2,4-triazolo[4,3-a]pyrimidines 5a–g
and 8a–g
Method A: An equimolar amount of each of the appropriate hydra-
zonoyl halides 2a–g, 1 or 1b and sodium ethoxide (5 mmol) in ethanol

608
A. O. Abdelhamid et al.
(20 ml) was refluxed for 3 h. The reaction mixture was cooled and the
resulting solid was collected and crystallized from ethanol to give 5a–g
and 8a–g respectively (Tables I and II).
Method B: A mixture of the appropriate hydrazonoyl halides 2a–g
(5 mmol) and compound 7 (1.68 g, 5 mmol) in chloroform (20 ml) contain-
ing triethylamine (0.5 g (0.75 ml), 5 mmol) was refluxed for 10 h. Chlo-
roform was evaporated under reduced pressure and the residue solid
was crystallized from ethanol to give products identical in all respects
(m.p., mixed m.p., and spectra) with corresponding products obtained
by method A.
Synthesis of 2,3-Dimethoxybenzoylbromide
4-nitrophenylhydrazone (9)
Bromine (4.8 g (1.5 ml), 3 mmol) in acetic acid (20 ml) was added
dropwise while stirring to a suspension of 2,3-dimethoxyphenyl-4-
nitrophenylhydrazone (8.85 g, 3 mmol) in acetic acid (25 ml) at room
temperature. After complete addition the reaction mixture was stirred
for 3 h. at room temperature, then poured onto crushed ice (50 g). The
resulting solid was collected and crystallized from acetic acid to give 9
(Tables I and II).
Synthesis of 1,3,4-Thiadiazoline 11a
and 1,3,4-Selenadiazoline 11b
Method A: A mixture of 9 (1.9 g, 5 mmol) and the appropriate of potas-
sium thiocyanate (0.58 g, 6 mmol) (or potassium selenocyanate (0.086 g,
6 mmol)) in ethanol (25 ml) was stirred at room temperature for 3 h.
The resulting solid was collected, washed with water and crystallized
from ethanol to give 11a and 11b respectively (Tables I and II).
Method B: A mixture of 9 (1.9 g, 5 mmol) and thiourea (0.38 g,
5 mmol) in ethanol (20 ml) was refluxed for 30 min. The solid prod-
uct, which formed after cooling, was collected and crystallized from
ethanol. It was identical in all respects (m.p., mixed m.p., and spectra)
with 11a.
Nitrosation of 11a and 11b
A cold saturated solution of sodium nitrite (10 ml) was added drop-
wise to a solution of 11a or 11b (1 g) in acetic acid (20 ml) in an ice
bath while stirring. The reaction mixture was stirred for 30 min. The
resulting solid was collected, washed with water, and crystallized from
acetone to give 14a and 14b respectively (Tables I and II).

Reactions Hydrazonoyl Halides
609
TABLE I Characterization Data of the Newly Synthesized Compounds
m.p.◦C/
solvent of
crystallization
% Analyses, calcd./(found)
Yield %
color
Mol. formula
Mol. Wt
No.
C
H
N
S
5a
114–5
EtOH
139–40
EtOH
132–3
EtOH
159–60
EtOH
113–4
EtOH
182–4
EtOH
96–8
EtOH
134–5
EtOH
131–2
EtOH
158–8
EtOH
196–7
EtOH
147
EtOH
185–7
EtOH
116–7
EtOH
120–2
AcOH
215–7
Dioxan
198–9
EtOH
150 dec.
Acetone
160 dec.
Acetone
209–10
AcOH
195–6
AcOH
220–1
AcOH
72
Yellow
68
Yellow
58
Yellow
71
Yellow
60
Orange
80
Orange
56
Orange
78
Yellow
84
Yellow
68
Yellow
85
Yellow
66
Yellow
80
Orange
64
Orange
68
Yellow
82
Yellow
78
C25H26N4O6
478.51
C26H28N4O6
492.54
C25H26N4O6
462.51
C30H29N5O5
539.59
C30H28N4O5
524.58
C28H26N4O5S
530.61
62.75 5.48 11.71
62.90 4.30 11.60
63.40 5.73 11.36
63.20 5.80 11.50
64.92 5.67 12.11
65.10 5.60 12.00
66.68 5.42 12.98
66.80 5.20 12.80
68.69 5.38 10.68
68.90 5.10 10.50
—
5b
5c
—
—
—
—
5d
5e
5f
63.38 4.94 10.56 6.04
63.40 5.00 10.60 6.20
5g
C
34H30N4O5
574.64
71.07 5.26
71.10 5.30
9.75
9.80
—
—
—
—
—
—
8a
C25H26N4O6
478.51
62.75 5.48 11.71
62.50 5.50 11.50
63.40 5.73 11.36
63.20 5.60 11.50
64.92 5.67 12.11
64.80 5.60 12.20
66.68 5.42 12.98
66.70 5.30 13.10
68.69 5.38 10.68
68.80 5.50 10.60
8b
C
26H28N4O6
492.54
8c
C25H26N4O6
462.51
C30H29N5O5
539.59
8d
8e
C
30H28N4O5
524.58
8f
C28H26N4O5S
530.61
63.38 4.94 10.56 6.04
63.40 5.10 10.70 5.90
8g
C34H30N4O5
71.07 5.26
71.20 5.00
9.75
9.90
—
574.64
C15H14BrN3O4
380.20
C16H14N4O4S
358.38
9
47.39 3.71 11.05
46.90 4.10 11.10
53.62 3.94 15.63 8.95
53.40 4.20 15.50 9.10
11a
11b
14a
14b
15a
15b
16a
C16H14N4O4Se 47.42 3.48 13.82
—
Yellow
76
Pale red
68
Pale red
69
Pale yellow
72
405.27
16H13N5O5S
387.38
47.10 3.60 13.90
49.61 3.38 18.08 8.28
49.50 3.10 18.00 8.40
C
C16H13N5O5Se 44.25 3.02 16.13
—
434.27 44.40 3.00 16.10
C16H13N3O5S
359.36
53.48 3.65 11.69 8.92
55.30 3.50 11.60 9.10
C16H13N3O5Se 47.30 3.23 10.34
Pale Yellow
83
Pale yellow
406.26
C18H16N4O5S
400.42
47.10 3.30 10.40
53.99 4.03 13.99 8.01
53.70 3.80 14.10 8.20
(Continued on next page)

610
A. O. Abdelhamid et al.
TABLE I Characterization Data of the Newly Synthesized Compounds
(Continued)
m.p.◦C/
solvent of
crystallization
% Analyses, calcd./(found)
Yield %
color
Mol. formula
Mol. Wt
No.
C
H
N
S
16b
231–3
AcOH
235–7
AcOH
276–7
AcOH
195–8
AcOH
208–11
AcOH
199–200
AcOH
244–5
AcOH
196–8
AcOH
252–5
AcOH
283–5
AcOH
249–51
AcOH
249–51
DMF
279–81
DMF
221–3
DMF
200–1
AcOH
212–3
AcOH
196–8
AcOH
79
Pale yellow
68
Pale yellow
71
Page
87
Yellow
64
Orange
68
Yellow
72
Yellow
96
Yellow
62
Yellow
42
Red
51
Red
90
Orange
92
Orange
64
Orange
82
C18H16N4OSe
447.31
C23H18N4O5S
462.49
48.33 3.61 12.53
48.50 3.80 12.40
59.73 3.92 12.11
59.60 3.90 11.90
17a
17b
22a
22b
22c
22d
22e
22f
25
6.93
6.80
—
C23H18N4O5Se 54.23 3.56 11.60
609.38
23H19N5O4S
461.5
84.40 3.70 11.70
59.86 4.15 15.18
59.80 4.40 15.10
C
6.95
7.10
C
21H17N5O4S2 53.95 3.67 14.98 13.72
467.53 53.70 3.80 15.00 13.60
C21H17N5O5S
451.46
55.87 3.80 15.51
55.80 4.00 15.40
60.62 4.45 14.73
60.80 4.50 14.50
56.77 4.11 15.05
56.80 3.90 14.80
7.10
7.00
6.74
6.60
6.89
6.90
C24H21N5O4S
475.53
C22H19N5O5S
465.49
C
22H19N5O4S2 54.87 3.98 14.54 13.32
481.56
24H18N6O5S
502.51
54.70 3.80 14.60 13.50
C
57.37 3.60 16.72
57.10 3.80 16.50
58.25 3.32 13.59
58.40 3.20 13.70
60.11 3.43 14.02
60.20 3.40 14.20
6.38
6.10
6.22
6.40
6.43
6.30
26
C25H17N5O6S
515.50
28a
28b
28c
33a
33b
33c
C25H17N5O5S
499.51
C25H17N5O4S2 58.24 3.32 13.58 12.44
515.57
26H20N6O4S
512.55
58.10 3.50 13.30 12.50
C
60.93 3.93 14.60
60.90 3.80 14.50
60.82 4.18 12.90
60.60 4.10 12.70
61.59 4.49 12.49
61.30 4.20 12.20
59.47 4.34 12.06
59.10 4.10 12.20
6.26
6.10
7.38
7.20
7.15
7.10
6.90
7.10
C22H18N4O4S
434.48
Yellow
81
Yellow
82
C23H20N4O4S
448.48
C23H20N4O5S
464.50
Yellow
Thermolysis of 14a and 14b
A solution of 11a, 11b (0.5 g) in xylene (20 ml) was refluxed for
15 min and then, the solvent was evaporated under reduced pressure.
The residue oil was triturated with petroleum ether (40–60◦C) and
the solid formed was collected and crystallized from acetic acid to give
1,3,4-thiadiazolinone 15a and 1,3,4-selenadiazolinone 15b respectively
(Tables I and II).

Reactions Hydrazonoyl Halides
611
TABLE II 1H NMR Spectra of Some Selected Synthesized Compounds
Compd. no.
1H NMR (δ ppm)
5b
1.25 (t, 3H), 1.52 (t, 3H), 2.53 (s, 3H), 3.85 (s, 6H), 4.07 (q, 2H), 4.45
(q, 2H), 6.69 (d, 1H), 6.92–6.97 (m, 3H), 7.31–7.47 (m, 3H) and
8.14 (d, 2H).
5c
5d
5e
1.22 (t, 3H), 2.51 (s, 3H), 2.53 (s, 3H), 3.81 (s, 3H), 3.83 (s, 3H), 4.07
(q, 2H), 6.69 (d, 1H), 6.73–6.99 (m, 6H) and 8.17 (d, 2H).
1.20 (t, 3H), 2.56 (s, 3H), 3.77 (s, 3H), 3.79 (s, 3H), 4.08 (q, 2H), 6.70
(d, 1H), 7.01–7.60 (m, 11H), 8.15 (d, 2H) and 8.38 (s, 1H).
1.19 (t, 3H), 2.58 (s, 3H), 3.68 (s, 3H), 3.75 (s, 3H), 4.07 (q, 2H), 6.64
(d, 1H), 6.88–6.95 (m, 3H), 7.25–7.48 (m, 6H), 8.06 (d, 2H) and
8.21 (d, 2H).
5f
1.21 (t, 3H), 2.57 (s, 3H), 3.76 (s, 3H), 3.77 (s, 3H), 4.06 (q, 2H), 6.66
(d, 1H), 6.95–6.97 (m, 3H), 7.00–7.17 (m, 3H), 7.47–7.52 (t, 2H),
7.76–7.77 (d, 1H), and 8.23–8.27 (d, 2H).
5g
8a
8b
1.21 (t, 3H), 2.59 (s, 3H), 3.67 (s, 3H), 3.69 (s, 3H), 4.09 (q, 2H), 6.62
(d, 1H), 6.90–6.94 (m, 3H), 7.32–7.55 (m, 5H), 7.96–7.41 (m, 4H),
8.02 (d, 2H) and 8.84 (s, 1H).
1.23 (t, 3H), 2.48 (s, 3H), 3.76 (s, 3H), 3.79 (s, 3H), 3.96 (s, 3H), 4.07
(q, 2H), 7.78 (d, 1H), 6.82–7.07 (m, 3H), 7.25–7.49 (m 3H), and
8.14 (d, 2H).
1.23 (t, 3H), 1.32 (t, 3H), 2.48 (s, 3H), 3.75 (s, 3H), 3.79 (s, 3H), 4.07
(q, 2H), 4.31 (q, 2H), 6.78 (d, 1H), 6.82–7.07 (m, 4H), 7.26–7.49
(m, 3H) and 8.15 (d, 2H).
8c
8d
8e
1.24 (t, 3H), 2.43 (s, 3H), 2.47 (s, 3H), 3.76 (s, 3H), 3.79 (s, 3H), 4.19
(q, 2H), 6.77 (d, 1H), 6.81–7.51 (m, 6H) and 8.18 (d, 2H).
1.24 (t, 3H), 2.48 (s, 3H), 3.76 (s, 3H), 3.78 (s, 3H), 4.05 (q, 2H), 6.76
(d, 1H), 6.78–7.53 (m, 11H), 8.15 (d, 2H) and 8.27 (s, 1H).
1.25 (t, 3H), 2.54 (s, 3H), 3.72 (s, 3H), 3.75 (s, 3H), 4.08 (q, 2H), 6.66
(d, 1H), 6.78–7.02 (m, 3H), 7.26–7.57 (m, 6H), 7.97 (d, 2H) and
8.18 (d, 2H).
8f
1.24 (t, 3H), 2.54 (s, 3H), 3.74 (s, 3H), 3.76 (s, 3H), 4.07 (q, 2H), 6.71
(d, 1H), 6.75–7.00 (m, 3H), 7.26–7.35 (m, 2H), 7.45–7.53 (m, 2H),
7.69–7.72 (m, 1H), 8.14–8.17 (m, 1H) and 8.24–8.26 (d, 2H).
1.26 (t, 3H), 2.56 (s, 3H), 3.66 (s, 3H), 3.77 (s, 3H), 4.11 (q, 2H), 6.77
(d, 1H), 6.98–7.86 (m, 11H), 8.26 (d, 2H) and 8.52 (s, 2H).
3.92 (s, 3H), 3.94 (s, 3H) and 6.98–8.37 (m, 8H).
3.93 (s, 3H), 3.96 (s, 3H) and 7.02–8.35 (m, 7H).
2.42 (s, 3H), 3.93 (s, 3H), 4.03 (s, 3H) and 7.02–8.34 (m, 7H).
3.95 (s, 3H), 4.08 (s, 3H) and 7.05–8.57 (m, 12H).
8g
11b
15b
16b
17a
22b
22c
28a
28b
28c
33b
33c
3.93 (s, 3H), 4.01 (s, 3H), 6.52–8.56 (m, 10H) and 8.58 (s, 1H).
3.93 (s, 3H), 4.01 (s, 3H), 6.52–8.56 (m, 10H) and 8.55 (s, 1H).
3.95 (s, 3H), 4.12 (s, 3H) and 7.05–8.54 (m, 11H).
3.96 (s, 3H), 4.11 (s, 3H) and 7.06–8.47 (m, 11H).
3.91 (s, 3H), 3.93 (s, 3H), 4.04 (s, 3H) and 7.03–8.46 (m, 11H).
2.35 (s, 3H), 3.86 (s, 3H), 3.90 (s, 3H) and 6.99–8.57 (m, 11H).
3.84 (s, 3H), 3.86 (s, 3H), 3.90 (s, 3H) and 6.92–8.57 (m, 11H).

612
A. O. Abdelhamid et al.
Synthesis of N-[5-(2,3-Dimethoxyphenyl)-3-(4-
nitrophenyl)-3H-[1,3,4]thiadiazol-2-ylidene]acetamide
(16a), N-[5-(2,3-Dimethoxyphenyl)-3-(4-nitrophenyl)-3H-
[1,3,4]selenadiazol-2-ylidene]acetamide (16b),
N-[5-(2,3-Dimethoxyphenyl)-3-(4-nitrophenyl)-3H-
[1,3,4]thiadiazol-2-ylidene]benzamide (17a), and
N-[5-(2,3-Dimethoxyphenyl)-3-(4-nitrophenyl)-3H-
[1,3,4]selenadiazol-2-ylidene]benzamide (17b)
a) Acetylation: A mixture of 11a or 11b (1 g) in acetic acid (10 ml) and
acetic anhydride (5 ml) was warmed for 5 min at 70◦C. The reaction
mixture was poured onto ice water (40 ml). The solid was collected and
crystallized to give the N-acetyl derivatives 16a and 16b respectively
(Tables I and II).
b) Benzoylation: 11a or 11b (0.5 g) and benzoyl chloride (3 ml) in
pyridine (15 ml) were refluxed for 10 min, poured onto ice water (50 ml),
and acidified with hydrochloric acid. The resulting product was collected
and washed several time with boiling water. The resulting solid was
crystallized from acetic acid or N,N-dimethylformamide to give the N-
benzoyl derivatives 17a and 17b respectively (Tables I and II).
Synthesis of Thiadiazolines 22a–f, 25, 26, 29a–c,
and 33a–c
Method A: Triethylamine (0.5 g (0.75 ml), 5 mmol) was added dropwise
with stirring to a mixture of the appropriate alkyl carbodithioates 18a–f
(or 19a–f) or 23 or 24 or 27a–c (or 29a–c) or 30a–c (or 34a–c) (5 mmol)
and compound 9 (1.9 g, 5 mmol) in ethanol (20 ml). The resulting solid,
which formed after 30 min, was collected and crystallized from acetic
acid and gave the corresponding thiadiazolines 22a–f, 25, 26, 29a–c,
and 33a–c, respectively, in a good yield (Tables I and II).
Method B: A mixture of 9 and the appropriate arylthiourea (5 mmol
each) in ethanol (20 ml) was refluxed for 2 h. The solid formed was col-
lected, washed with water and crystallized from ethanol gave products
identical in all respects (m.p., mixed m.p., and spectra) with 37a–c.
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