Synthesis and anti-inflammatory evaluation of some condensed [4-(3,4-dimethylphenyl)-1(2H)-oxo-phthalazin-2-yl]acetic acid hydrazide

Article abstract of DOI:10.1016/j.ejmech.2009.10.028

Some new 1,3,4-triazolo-, 1,3,4-oxadiazolo-, 1,3,4-thiadiazol-, and pyrazolo-3,4-dimethylphenyl-1(2H)-oxo-phthalazine derivatives were synthesized and identified by IR, ¹H NMR, MS and elemental analysis. Most of the newly synthesized products were tested for their anti-inflammatory activities. Among them, compounds 11, 17b, 20, 21 and 22 are active compare to the activity of indomethacin.

Full text of DOI:10.1016/j.ejmech.2009.10.028

European Journal of Medicinal Chemistry 45 (2010) 1267–1277
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Synthesis and anti-inflammatory evaluation of some condensed
[4-(3,4-dimethylphenyl)-1(2H)-oxo-phthalazin-2-yl]acetic acid hydrazide
,
a
a
c
Mosaad S.M. Abd alla a, Mohamed I. Hegab b , Nageh A. Abo Taleb , Sherifa M. Hasabelnaby , A. Goudah
*
a Pharmaceutical organic chemistry Department, Faculty of Pharmacy, Helwan University, Ain Helwan, Cairo, Egypt
b Photochemistry Department, National Research Centre, 12622 Dokki, Cairo, Egypt
c Pharmacology Department, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt
a r t i c l e i n f o
a b s t r a c t
Article history:
Some new 1,3,4-triazolo-, 1,3,4-oxadiazolo-, 1,3,4-thiadiazol-, and pyrazolo-3,4-dimethylphenyl-1(2H)-
oxo-phthalazine derivatives were synthesized and identified by IR, 1H NMR, MS and elemental analysis.
Most of the newly synthesized products were tested for their anti-inflammatory activities. Among them,
compounds 11, 17b, 20, 21 and 22 are active compare to the activity of indomethacinÒ.
Ó 2009 Elsevier Masson SAS. All rights reserved.
Received 25 April 2009
Received in revised form
18 September 2009
Accepted 15 October 2009
Available online 23 October 2009
Keywords:
1(2H)-Oxo-phthalazine
1,3,4-Triazole
1,3,4-Oxadiazole
1,34-Thiadiazol
Pyrazole
Anti-inflammatory
1. Introduction
several phthalazine derivatives have been reported to possess
antitumor [2–5], antihypertensive [6,7], antithrombotic [8],
Most of the current nonsteroidal anti-inflammatory drugs
(NSAIDs) show serious side effects including gastrointestinal
disorders and kidney damage. Therefore, studies for developing
safer NSAIDs lacking the gastrointestinal and renal side effects of
currently used ones have recently been of interest for many
researchers. Most of the classical NSAIDs exert their side effects by
inhibition of COX-1 enzyme. Since the COX-1 isoform is the
constitutive one that is responsible for regulation of physiological
processes, and the COX-2 isoform is discovered to be the enzyme
induced by a inflammatory stimuli, selective inhibition of COX-2
provides a rationale for developing anti-inflammatory and anal-
gesic agents that lack the GI liabilities exhibited by currently mar-
keted NSAIDs. Although the diarylheterocyclic compounds are
mainly studied as new class of NSAIDs without gastric side effects,
many studies have also focused on a different type of compounds to
develop safer NSAIDs [1].
anticonvulsant [9,10], antidiabetic [11,12], antimicrobial [13], anti-
trypanosomal [14], and anti-inflammatory activities [1,15–20].
In view of the aforementioned facts, it seemed most interesting
to synthesize some condensed [4-(3,4-dimethylphenyl)-1(2H)-
oxo-phthalazin-2-yl]acetic acid hydrazides with the aim to
evaluate their anti-inflammatory activities.
2. Results and discussion
2.1. Chemistry
4-(3,4-Dimethylphenyl)phthalazin-1(2H)-one (3) was obtained
from the reaction of 2-(3,4-Dimethylbenzoyl)benzoic acid (2) with
hydrazine hydrate. The IR spectrum showed a characteristic
absorption band at v ¼ 1664 cmꢀ1 corresponding to CO group. The
1H NMR spectrum showed NH at
d
¼ 11.17 ppm. Compound 3 was
In the last few years, the attention was oriented towards the
synthesis and biological evaluation of phthalazine derivatives as
they exhibit a board spectrum of biological activities. Indeed,
treated with ethyl chloroacetate to afford the corresponding
phthalazine acetic acid ethyl ester 4 (Scheme 1). The structure of
compound 4 was confirmed by spectral data (IR, 1H NMR, and MS).
Its mass spectrum shows the prominent ion peak at m/z 336 (Mþ,
60). The 1H NMR showed a triplet signal at
d
1.20 assigned for
* Corresponding author. Tel.: þ20 102944790; fax: þ20 3370931.
E-mail address: apmihegab65@yahoo.com (M.I. Hegab).
CH3CH2, a quartet signal at 4.20 assigned for CH2CH3, a singlet
0223-5234/$ – see front matter Ó 2009 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2009.10.028

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M.S.M. Abd alla et al. / European Journal of Medicinal Chemistry 45 (2010) 1267–1277
CH3
Ar
Ar
O
CH3
O
N
NH2NH2
O
AlCl3
OH
NH
O
O
O
1
2
3
CH3
Ar =
ClCH2CO2C2H5,
K2CO3
CH3
Ar
Ar
N
N
NH2NH2
NCH2CONHNH2
NCH2CO2C2H5
O
O
5
4
Scheme 1.
signal at 4.97 assigned for CH2CO, besides 2 CH3 and aromatic
protons. The phthalazine acetic acid ethyl ester 4 was converted to
the corresponding hydrazide 5 in high yield by the reaction with
hydrazine hydrate (Scheme 1). The 1H NMR of compound 5 shows
obtained previously, through cyclization at
d
¼ 4.35 and NH at
d
¼ 8.56 ppm. The mass spectrum of compound 8b showed the
prominent ion peak at m/z (%) ¼ 263 (Mþ, 70). However, triazolo
phthalazine 8b could be obtained, in higher yield than that
obtained previously, through cyclization of phthalazine thio-
semicarbazide 9 with sodium hydroxide (Scheme 2). The treatment
of mercapto triazolo phthalazine 8b with methyl iodide gave the
corresponding methylthio triazolo phthalazine 10. Its 1H NMR
d
¼ 4.40 (s, 2H, NH2 exchangeable with D2O), 4.90 (s, 2H, CH2CO),
9.30 (s, 1H, NH exchangeable with D2O) ppm and aromatic protons.
Whereas, the hydrazide derivatives constitute a class of compounds
that have served as useful intermediates towards construction of
different heterocyclic compounds [21]. The hydrazide derivative 5
reacted with some aromatic aldehydes namely, furfural,
showed SCH3 at
d
¼ 2.53 ppm.
Accordingly, the hydrazide 5 reacted with carbon disulfide to
obtain the corresponding oxadiazole thione 11 which is converted
to the methylthio oxadiazolo phthalazine 12 (Scheme 3). The 1H
2-methoxybenazldehyde,
2-hydroxybenzaldehyde,
2-chloro-
benzaldehyde, and 3,4,5-trimethoxybenzaldehyde to obtain the
corresponding phthalazinyl acetic acid methylidene hydrazides
6a–e (Scheme 2). The 1H NMR spectra of compounds 6a–e showed
NMR of compound 11 revealed the signal at
for NH. Whatever, the 1H NMR of compound 12 showed the absence
of NH and showed the signal at
d
¼ 7.06 ppm assigned
the methylidene protones at
d
¼ 8.96–9.33 ppm. On the other hand,
d
¼ 2.55 ppm assigned for SCH3.
[4-(3,4-dimethylphenyl)-1(2H)-oxo-phthalazin-2-yl]acetic acid [1-
(2-chlorophenyl)methylidenehydrazide] (6d) reacted with thio-
glycolic acid to afford the corresponding thiazolidine derivative 7d
in moderate yield (Scheme 2). The 1H NMR of compound 7d shows
Also, the hydrazide 5 reacted with benzoyl chloride and acetyl
chloride to give the compounds 13a,b, respectively. The 1H NMR of
compound 13a showed 2 NH at
d
¼ 10.08 and 10.21 ppm, and the
¼ 2.04 ppm. The
1H NMR of compound 13b showed COCH3 at
d
d
¼ 3.02 for assigned SCH2, 5.50 for assigned CH, 8.80 ppm for
derivatives 13a,b are cyclized to the corresponding oxadiazolo
phthalazines 14a,b, respectively by the reaction with phosphorus
oxychloride (Scheme 3). The required structures 14a,b were
confirmed by spectral data (see the experimental part). However,
The derivatives 13a,b are cyclized to the corresponding pyrazolo
phthalazines 15a,b, respectively by the reaction with sodium eth-
oxide (Scheme 3). The 1H NMR of compounds 15a,b showed the
assigned NH, and the aromatic protons.
However, fusion of the hydrazide derivative 5 with urea and/or
thiourea afforded the corresponding triazolo phthalazines 8a and
8b, respectively. The 1H NMR of compound 8a showed
d
¼ 8.57,
10.77 ppm assigned for 2 NH which are exchangeable with D2O.
The IR spectrum of compound 8a revealed the absence of hydroxyl
group. So, the structure of compound 8a exists in the keto-form.
The 1H NMR of compound 8b revealed that the structure exists
pyrazolo protons at
d
¼ 7.10 and at ¼ 7.00 ppm, respectively.
d
The hydrazide derivative 5 reacted with acrylonitrile to afford
the corresponding cyanoethyl hydrazide 16 in good yield. The
structure of compound 16 was confirmed by the 1H NMR, where
predominantly in the enol-form, whereas SH appears at
d
¼ 4.35
and NH at
d
¼ 8.56 ppm. The mass spectrum of compound 8b
showed the prominent ion peak at m/z (%) ¼ 263 (Mþ, 70).
the ethyl protones appear at
d
¼ 3.02, and 3.17. Also, the hydrazide
However, triazolo phthalazine 8b could be obtained, in higher yield
derivative 5 reacted with three isothiocyanate derivatives, namely
phenyl, benzyl, and methyl to give the corresponding thio-
carbamate derivatives 17a–c, respectively. Similarly, the hydrazide
derivative 5 reacted with phenyl and ethyl isocyanate to produce
the corresponding carbamate derivatives 18a,b, respectively. The
than that obtained previously, through cyclization at
d
¼ 4.35 and
NH at
d
¼ 8.56 ppm. The mass spectrum of compound 8b showed
the prominent ion peak at m/z (%) ¼ 263 (Mþ, 70). However, triazolo
phthalazine 8b could be obtained, in higher yield than that

M.S.M. Abd alla et al. / European Journal of Medicinal Chemistry 45 (2010) 1267–1277
1269
Ar
Ar
Ar'
N
N
HSCH2COOH
S
6d
NCH2CONH
N
NCH2CONHNH=CHAr'
O
O
O
7d
6
a, 2-C4H3O; b, Ar' = 2-OCH3C6H4; c, Ar' = 2-OHC6H4; d, Ar' = 2-ClC6H4; e, Ar' = 3,4,5(OCH3)3C6H2
Ar'CHO
Ar
Ar
N
HN
N
NH2C(X)NH2
N
NCH2
NCH2CONHNH2
N
XH
O
O
5
KSCN
Ar
Ar
N
NCH2
HN
NH
N
N
X
NCH2CONHNHCSNH2
O
8
a, X= O; b, X = S
CH3I
O
9
8b
Ar
NaOH
N
HN
8b
N
NCH2
N
SCH3
O
10
Scheme 2.
1H NMR of compound 17a showed
exchangeable with D2O), 12.52 (s, 1H, NHPh, exchangeable with
D2O) ppm. The 1H NMR of compound 18a showed
for NHPh (exchangeable with D2O), and 10.14 ppm assigned for
CONH (exchangeable with D2O). However, the hydrazide derivative
reacted with triethyl orthoformate in the presence of acetic anhy-
dride gave 2-N,N-diacetyl hydrazide derivative 19 rather than ethyl
imidate derivative 20 which is obtained via the reaction of the
hydrazide 5 with triethyl orthoformate only. The 1H NMR of
d
¼ 10.08 (s, 1H, CONH,
hydrazino hydrazide derivative 21 was obtained from the reaction
of ethyl imidate derivative 20 with hydrazine hydrate in benzene,
whereas the hydrazide 5 was obtained when the ethyl imidate
derivative 20 treated with hydrazine hydrate in ethanol. The 1H
NMR of compound 21 showed the absence of ethyl protons and
showed 4.35 assigned for NH2, 4.51 assigned for NH, and 10.58 ppm
assigned for CONH. The mass spectrum of compound 21 shows the
prominent ion peak at m/z (%) ¼ 364 (Mþ, 2) (Scheme 4).
d
¼ 9.26 assigned
The hydrazide derivative 5 reacted with ethyl acetoacetate to
afford the corresponding pyrazolo phthalazine derivative 22 in
keto–enol form, whichturn cyclized to pyrazolotriazolophthalazine
derivative 23 by the reaction with hydrazine hydrate. The 1H NMR of
compound 19 showed
the 1H NMR of compound 20 showed
CH3CH2), 4.10 (q, J, 10 Hz, 3H, CH3CH2), and 7.40 (s, 1H, CH]N). The
d
¼ 2.48 ppm assigned for 2 COCH3 whereas
d
¼ 1.30 (t, J, 10 Hz, 3H,

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M.S.M. Abd alla et al. / European Journal of Medicinal Chemistry 45 (2010) 1267–1277
Ar
N
CH3I
N
N
NCH2
O
SCH3
Ar
O
12
Ar
N
N
NH
N
NCH2
N
N
O
S
NCH2
O
O
SH
11
O
CS2
Ar
Ar
N
RCOCl
N
NCH2CONHNHCOR
NCH2CONHNH2
O
O
5
13a,b
a, R= C6H5; b, R = CH3
NaOC2H5
POCl3
Ar
Ar
N
N
O
N
N
N
NCH2
O
NH
O
R
R
N
O
15a,b
14a,b
Scheme 3.
compound 22 showed
d
¼ 2.30 assigned for CH3, 4.97 assigned CH2,
(s, 3H, N]CCH3), 2.29 (s, 3H, OCCH3), 2.54 (s, 2H,N]CCH2),10.60 (s,
and 6.10 ppm assigned for 4-CH2. The mass spectrum of compound
22 showed the prominent ion peak at m/z (%) ¼ 386 (Mþꢀ2, 4). The
structure of compound 23 was verified by the spectral data. Where,
the IR showed the absorption bandat v ¼ 1664 cmꢀ1 assigned for CO,
1H, NH, exchangeable with D2O) ppm. While, the 1H NMR of
compound 25 showed
d
¼ 2.30 (s, 3H, CH3), 2.48 (s, 3H, CH3), 4.64 (s,
2H, CH2), 6.18 (s, H, CH), ppm. On the other hand, on heating of the
hydrazide derivative 5 on oil bath gave the corresponding carboxylic
acid 26 (Scheme 5). The structure of acid 26 was confirmed by
spectral data. The IR showed the absorption band at v ¼ 2542–3500
assigned for (OH), 1701, 1667 assigned for (2 CO) cmꢀ1. The 1H NMR
and the 1H NMR showed
d
¼ 1.94 (s, 3H, CH3), 2.46 (s, 6H, 2 CH3), 2.60
(s, 2H,CH2), 5.30 (s, 2H,CH2), 7.28–8.50 (m, 7H, Ar–H) ppm.
Accordingly, the hydrazide derivative 5 condensed with acetyl
acetone to produce the required derivative 24 which was cyclized to
the corresponding pyrazol derivative 25 via treatment with sodium
showed
d
¼ 2.34 (s, 6H, 2 CH3), 4.82(s, 2H, CH2), 7.30–8.20 (m, 7H,
Ar–H) ppm. The mass spectrum showed the prominent ion peak at
ethoxide (Scheme 5). The 1H NMR of compound 24 showed
d
¼ 1.96
m/z (%) ¼ 307 (Mþꢀ1, 41).

M.S.M. Abd alla et al. / European Journal of Medicinal Chemistry 45 (2010) 1267–1277
Ar
1271
Ar
N
N
NCH2CONHNHCH2CH2CN
NCH2CONHNHCSNHR
O
16
O
17a-c
a, R = C6H5; b, R = C7H7, c, R= CH3
CH2=CHCN
RNCS
Ar
Ar
N
RNCO
N
NCH2CONHNHCO
NHR
NCH2CONHNH2
O
18a,b
TEOF
O
a, R = C6H5; b, R = C2H5
5
in presence (CH3CO)2O
Ar
NH2NH2
EtOH
in absence
of (CH3CO)2O
N
Ar
COCH3
NCH2CONHN
N
COCH3
O
NCH2CONHN
CHOC2H5
19
Ar
O
20
N
NH2NH2, C6H6
NCH2CONHN
CHNHNH2
O
21
Scheme 4.
The thiocarbamate derivatives 17a–c were cyclized to the cor-
responding triazole derivatives 27a–c by treatment with sodium
hydroxide, while they were cyclized to the corresponding thiadia-
zolo phthalazine derivatives 28a–c by using conc. Sulfuric acid
(Scheme 6). The required structures were verified by spectral data.
4-aryl substituted on the phthalazinone nucleus contributes to
a good anti-inflammatory and nociceptive activities. It is also well-
known that some heteroaryl acetic acids possess anti-inflammatory
activities [24,25]. Substitution of the acetamide side chain on the
lactam nitrogen in the phthalazinone derivatives [1] resulted in
compounds having considerably high antinociceptive and anti-
inflammatory activities without gastric lesion and bleeding at the
given dose.
2.2. Anti-inflammatory testing
It was of interest to prepare a number of 4-aryl-oxophthalazine-
2-yl acetic acid derivatives for pharmacological screening.
Various pyrazole derivatives including the drugs butazolidin,
celebrex were reported as effective anti-inflammatory agents
[1,26]. Consequently, it was though worthwhile to incorporate
A series of phthalazin-4-yl acetic acid derivatives [22] was
reportedly prepared and showed anti-inflammatory activity in the
carrageenin and edema test. Recently, several groups have studied
the structure-activity relationship of novel series of 4-aryl-
substituted phthalazinones [17,23] and showed that the presence of

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M.S.M. Abd alla et al. / European Journal of Medicinal Chemistry 45 (2010) 1267–1277
Ar
Ar
N
N
fusion
NCH2COOH
NCH2CONHNH2
O
26
O
5
CH3COCH2COOC2H5
Ar
CH3COCH2COCH3
N
O
N
NCH2C
N
Ar
CH3
O
O
N
CH3
22
NCH2CONHN
CH2
NH2NH2
O
24
O
CH3
Ar
CH3
NaOC2H5
N
N
N
N
NCH2
Ar
N
O
N
O
CH3
N
23
NCH2C
N
O
H3C
25
Scheme 5.
pyrazole moieties in the 2 position of phthalazinone nucleus in
a hope to yield safe and potent anti-inflammatory compounds.
Compounds 11, 17b, 20, 21 and 22 showed the higher anti-
inflammatory activities than that of the reference drug (Table 1).
The presence of: oxadiazole thione ring in compound 11, tolyl thi-
ocarbamate group in compound 17b, ethoxy imidine moiety in
derivative 20, hydrazino imidine function in derivative 21, and
pyrazolone ring in compound 22, it might be, increased the anti-
inflammatory activity. The most potent anti-inflammatory activi-
ties were recorded for compound 17b.
4. Experimental
4.1. Chemistry
All melting points are uncorrected and measured using Electro-
thermal IA 9100 apparatus (Shimadzu, Japan). IR spectra were recor-
ded as potassium bromide pellets on Bruker FT-IR spectrophotometer
and the data are given in vmax (cmꢀ1), Faculty of Science, Cairo
University, Cairo, Egypt.1H NMR spectrawere determined on a Jeol-Ex-
300 NMR spectrometer and chemical shifts were expressed as part per
million; ppm (d values) against TMS as internal reference (Faculty of
Science, Cairo University, Cairo, Egypt). Mass spectra were recorded on
3 and EI þ Q1 MSLMR UPLR, National Research Centre, Cairo, Egypt.
Microanalyses were operated at the Microanalytical Center, Cairo
University, Cairo, Egypt and the results were within the accepted range
(ꢁ0.4%) of the calculated values. 2-(3,4-Dimethybenzoyl)benzoic acid
(2) was obtained as reported [27].
3. Conclusion
We reported here the synthesis of different 4-(3,4-dimethyl-
phenyl)phthalazin-1(2H)-ones. Most of the newly synthesized
compounds were tested for their anti-inflammatory activity. The
results in Table 1 revealed that compounds 11,17b, 20, 21 and 22 are
active compared to the activity of indomethacinÒ, while all other
compounds showed no significant difference compared to that
of reference drug.
4.1.1. 4-(3,4-Dimethylphenyl)phthalazin-1(2H)-one (3)
Hydrazine hydrate (98%) 0.5 mL was added to a solution of 5 g 2
(0.02 mol) in 20 mL absolute ethanol. The reaction mixture was

M.S.M. Abd alla et al. / European Journal of Medicinal Chemistry 45 (2010) 1267–1277
1273
Table 1
dry acetone was heated under reflux for 30 h, cooled at room
temperature and poured into water. The obtained solid was filtered
off and crystallized from petroleum ether 40–60 ꢂC to give 2.7 g 4 in
yield 70% as yellowish white crystals. Mp 140–143 ꢂC. 1H NMR
Anti-inflammatory activity of new [4-(3,4-dimethylphenyl)-1(2H)-oxo-phthalazin-
2-yl] acetic acid hydrazides in the sponge implantation test.
Groups
Mean
differences
q-Value
p-Value
Conclusion
Significant
(300 MHz, DMSO-d6,
d
ppm): 1.20 (t, J ¼ 10 Hz, 3H, CH3CH2), 2.46 (s,
Control (c) vs
indomethacin
c vc 6a
c vc 6b
c vc 6c
c vc 6d
c vc 8b
c vc 9
c vc 11
c vc 13a
c vc 13b
c vc 16
c vc 17a
c vc 17b
c vc 17c
c vc 18a
c vc 18b
c vc 19
c vc 20
c vc 21
c vc 22
c vc 24
14.47
8.339
P < 0.001
6H, 2 CH3), 4.20 (q, J ¼ 10 Hz, 2H, CH2CH3), 4.97 (s, 2H, CH2CO),
7.28–8.36 (Ar–H). MS (m/z, %): 336 (Mþ, 60), 263 (100). Anal.
(C20H20N2O3).
7.81
7.42
7.91
8.72
8.44
7.54
15.23
7.26
8.93
8.61
8.12
17.15
7.45
7.74
8.67
8.24
15.12
14.37
15.532
7.94
6.87
3.921
4.639
3.737
2.246
2.761
4.418
9.738
4.934
1.859
2.448
3.350
13.273
4.584
4.050
2.338
3.871
9.536
10.351
9.862
3.985
4.538
P > 0.05
P > 0.05
P > 0.05
P > 0.05
P > 0.05
P > 0.05
P < 0.001
P > 0.05
P > 0.05
P > 0.05
P > 0.05
P < 0.001
P > 0.05
P > 0.05
P > 0.05
P > 0.05
P < 0.001
P < 0.001
P < 0.001
P > 0.05
P > 0.05
Non significant
Non significant
Non significant
Non significant
Non significant
Non significant
Significant
Non significant
Non significant
Non significant
Non significant
Significant
Non significant
Non significant
Non significant
Non significant
Significant
4.1.3. [4-(3,4-Dimethylphenyl)-1(2H)-oxo-phthalazin-2-yl]acetic
acid hydrazide (5)
A mixture of 3.2 g 4 (0.01 mol) and 2 mL hydrazine hydrate in
50 mL absolute ethanol was refluxed for 3 h and cooled at room
temperature. The resultant solid was filtered and crystallized
from ethanol to give 2.5 g 5 in yield 79% as colorless crystals. Mp
238–240 ꢂC. IR (KBr, v cmꢀ1): 3335,3300 (NH2), 3191 (NH),
1652(CO). 1H NMR (300 MHz, DMSO-d6,
d ppm): 2.30 (s, 6H, 2
CH3), 4.40 (s, 2H, NH2 exchangeable with D2O), 4.90 (s, 2H,
CH2CO), 7.31–8.35 (Ar–H), 9.30 (s, 1H, NH exchangeable with
D2O). Anal. (C18H18N4O2).
Significant
Significant
Non significant
Non significant
4.1.4. Reaction of phthalazine hydrazide derivative 5 with some
aromatic aldehydes
c vc 26
A mixture of 0.3 g the acetic acid hydrazide 5 (0.001 mol) and an
appropriate aromatic aldehyde (0.001 mol) was refluxed in 20 mL
absolute ethanol for 3 h. After cooling the separated solid was
collected by filtration, dried and crystallized from the proper
solvent to give aryl methylidene hydrazide derivatives 6a–e.
refluxed for 2 h, after cooling the obtained solid was filtered off and
crystallized from ethanol to give 4.6 g 3 in 92% yield as colorless
crystals. Mp 264–266 ꢂC. IR (KBr, v cmꢀ1): 3157(NH), 1664(CO). 1H
NMR (300 MHz, DMSO-d6, d ppm): 2.46 (s, 6H, 2 CH3), 7.28–8.50 (m,
4.1.4.1. [4-(3,4-Dimethylphenyl)-1(2H)-oxo-phthalazin-2-yl]acetic
acid (1-furylmethylidene)hydrazide (6a). >0.32 g 6a in yield 80% as
faint brown crystals from toluene. Mp 232–234 ꢂC. IR (KBr, cmꢀ1):
7H, Ar–H), 11.17 (s, 1H, NH, exchangeable with D2O). MS (m/z, %):
250 (Mþ, 81), 249 (100). Anal. (C16H14N2O).
3198 (NH), 1655 (CO). 1H NMR (300 MHz, DMSO-d6,
d ppm): 2.35 (s,
4.1.2. [4-(3,4-Dimethylphenyl)-1(2H)-oxo-phthalazin-2-yl]acetic
acid ethyl ester (4)
A mixture of 3.0 g 3 (0.012 mol), 5.8 g ethyl chloroacetate
(0.048 mol) and 6.7 g potassium carbonate (0.048 mol) in 30 mL
6H, 2 CH3), 5.45 (s, 2H, CH2), 5.70(s, 1H, NH, exchangeable with
D2O), 6.39–7.97 (m, 10 H, Ar–H), 8.97 (s, 1H, CH). Anal.
(C23H20N4O3).
Ar
N
NCH2CONHNHCSNHR
O
17a-c
a, R = C6H5; b, R = C7H7, c, R= CH3
NaOH
H2SO4
Ar
Ar
N
N
N
N
NH
NCH2
N
NCH2
N
S
O
S
R
O
NHR
27a-c
28a-c
Scheme 6.

1274
M.S.M. Abd alla et al. / European Journal of Medicinal Chemistry 45 (2010) 1267–1277
4.1.4.2. [4-(3,4-Dimethylphenyl)-1(2H)-oxo-phthalazin-2-yl]acetic
acid [1-(2-methoxyphenyl)methylidenehydrazide] (6b). 0.34 g 6b in
yield 78% as colorless crystals from ethanol. Mp 152–154 ꢂC. IR (KBr,
v cmꢀ1): 3282 (NH), 1649 (CO). 1H NMR (300 MHz, DMSO-d6,
pale yellow crystals from ethanol. Mp 178–181 ꢂC. IR (KBr, v cmꢀ1):
3205,3154 (2 NH), 1675 (CO), 1255 (CS). 1H NMR (300 MHz, DMSO-
d6,
d ppm): 2.0 (s, 2H, NH, exchangeable with D2O), 2.35 (s, 6H, 2
CH3), 4.46 (s, 2H, CH2), 7.35–8.18 (m, 7H, Ar–H). MS (m/z, %): 263
d
ppm): 2.30 (s, 6H, 2 CH3), 3.81 (s, 3H, OCH3), 5.27(s, 1H, NH,
(Mþ, 70), 249 (21), 236 (100). Anal. (C19H17N5OS).
exchangeable with D2O), 5.50 (s, 2H, CH2), 6.80–7.85 (m, 11H, Ar–
H), 8.96(s, 1H, CH). Anal. (C26H24N4O3).
4.1.7. 1-{2-[4-(3,4-Dimethylphenyl)-1(2H)-oxo-phthalazin-2-
yl]acetyl}thiosemicarbazide (9)
4.1.4.3. [4-(3,4-Dimethylphenyl)-1(2H)-oxo-phthalazin-2-yl]acetic
acid [1-(2-hydroxyphenyl)methylidenehydrazide] (6c). 0.32 g 6c in
yield 75% as colorless crystals from toluene. Mp 220–224 ꢂC. IR
(KBr, v cmꢀ1): 4200 (OH), 1619 (CO). 1H NMR (300 MHz, DMSO-d6,
A mixture of 0.3 g the acetic acid hydrazide 5 (0.001 mol), 0.09 g
potassium thiocyanate (0.00 mol), 0.8 mL conc. HCl, and water
20 mL was refluxed for 12 h. After cooling the precipitated solid
was filtered off to give 0.27 g 9 in yield 70% as colorless crystals
from ethanol. Mp 184–186 ꢂC. IR (KBr, v cmꢀ1): 3444 (NH2), 3290,
3159 (2 NH), 1661 (CO), 1240 (CS). 1H NMR (300 MHz, DMSO-d6,
d
ppm): 2.33 (s, 6H, 2 CH3), 4.93 (s, 2H, CH2), 6.16(s, 1H, NH,
exchangeable with D2O), 6.85–7.99 (m, 11H, Ar–H), 8.74 (s, 1H, CH),
11.26 (s, 1H, OH, exchangeable with D2O). Anal. (C25H22N4O3).
d
ppm): 1.96(s, 1H, NHCS, exchangeable with D2O), 2.36 (s, 6H, 2
CH3), 5.80 (s, 2H, CH2), 6.01(s, 1H, CONH, exchangeable with D2O),
7.26–7.80 (m, 7H, Ar–H), 8.55(s, 2H, NH2, exchangeable with D2O).
MS (m/z, %) ¼ 265 (Mþ–NH2, 4), 291 (47), 263 (100). Anal.
(C19H19N5O2S).
4.1.4.4. [4-(3,4-Dimethylphenyl)-1(2H)-oxo-phthalazin-2-yl]acetic
acid [1-(2-chlorophenyl)methylidenehydrazide] (6d). 0.36 g 6d in
yield 82% as yellow crystals from toluene. Mp 240–244 ꢂC. IR (KBr, v
cmꢀ1): 3207 (NH),1659 (CO); 1H NMR (300 MHz, DMSO-d6,
d ppm):
2.35 (s, 6H, 2 CH3), 5.01 (s, 2H, CH2), 6.09 (s, 1H, NH, exchangeable
with D2O), 6.75–8.00 (m, 11H, Ar–H), 8.99(s, 1H, CH). MS (m/z, %):
446 (MþCl37, 1), 444 (MþCl35, 4), 263 (100). Anal. (C25H21ClN4O2).
4.1.8. Reaction of 9 with NaOH
A mixture of NaOH (8%, 15 mL) and thiosemicarbazide 9 (0.3 g,
0.001 mol) in 20 mL absolute ethanol was refluxed for 10 h. The solu-
tion was then cooled and neutralized with 2 N HCl. The solid obtained
was filtered, washed with water and crystallized from ethanol to give
a product which is identical in Mp, TLC to 8b; in yield 71%.
4.1.4.5. [4-(3,4-Dimethylphenyl)-1(2H)-oxo-phthalazin-2-yl]acetic
acid [1-(3,4,5-trimethoxyphenyl)methylidenehydrazide] (6e). 0.43 g
6e in yield 85% as colorless crystals from toluene. Mp 232–236 ꢂC.
IR (KBr, v cmꢀ1): 3177 (MH), 1665 (CO). 1H NMR (300 MHz, DMSO-
4.1.9. Reaction of 8b with methyl iodide
d6,
d
ppm): 2.32 (s, 6H, 2 CH3), 3.34 (s, 9H, 3 CH3), 4.88 (s, 2H, CH2),
To a suspension of the triazole 8b (0.36 g, 0.001 mol) in ethanol
(15 mL), sodium hydroxide solution (1 mL, 15%) was added fol-
lowed by the addition of methyl iodide (0.001 mol) and the reaction
mixture was refluxed on a water bath for 5 h then left overnight,
diluted with water and cooled. The solid product that formed was
filtered off to give 0.33 g 2-[(5-methythio-4H-1,2,4-triazol-3-yl)
methyl]-4-(3,4-dimethylphenyl)-phthalazin-1(2H)-one (10) in
yield 87% as pale yellow crystals from dilute ethanol. Mp 159–
161 ꢂC. IR (KBr, v cmꢀ1): 3195 (NH), 1668 (CO); 1H NMR (300 MHz,
6.33 (s, 1H, NH, exchangeable with D2O), 7.31–8.66 (m, 9H, Ar–H),
8.54(s, 1H, CH). Anal. (C28H28N4O5).
4.1.5. 2-[4-(3,4-Dimethylphenyl)-1(2H)-oxo-phthalazin-2-yl]N-[4-
oxo-2-(2-chlorophenyl)thiazolidin-3-yl]acetamide (7d)
A mixture of 0.6 g chloromethylidene hydrazide derivative 6d
(0.0013 mol), 0.1 mL thioglycolic acid (0.0013 mol), 0.5 g anhydrous
zinc chloride and few drops of piperidine was refluxed in 20 mL dry
N,N-dimethylformamide for 24 h. The reaction mixture was then
poured onto water and the precipitated solid was filtered off,
washed several times with water, dry to give 0.32 g 7d in yield 53%
as yellowish brown crystals from toluene. Mp 298–301 ꢂC. IR (KBr, v
cmꢀ1): 3177 (NH), 1715, 1663 (2 CO); 1H NMR (300 MHz, DMSO-d6,
DMSO-d6, d ppm): 2.34 (s, 6H, 2 CH3), 2.53 (s, 3H, SCH3), 5.00 (s, 2H,
CH2), 7.01–8.10 (m, 7H, Ar–H), 14.05 (s, 1H, NH, exchangeable with
D2O). Anal. (C20H19N5OS).
4.1.10. 4-(3,4-Dimethylphenyl)-2-[(4,5-dihydro-5-thiooxo-1,3,4-
oxadiazol-2-yl)methyl] phthalazin-1(2H)-one (11)
d
ppm): 2.31 (s, 6H, 2 CH3), 3.02 (s, 2H, SCH2), 5.00 (s, 2H, CH2), 5.50
(s, 1H, CH), 6.67–8.50 (m, 11H, Ar–H), 8.80 (s, 1H, NH, exchangeable
with D2O). Anal. (C25H23ClN4O2).
0.3 g Hydrazide 5 (0.001 mol) was added to 0.14 g potassium
hydroxide solution in 20 mL absolute ethanol. Then, 3 mL carbon
disulfide was added portionwise and the reaction mixture was
refluxed till no odour of hydrogen sulfide evolved (14 h). The
reaction mixture was poured onto ice water and rendered acidic
with hydrochloric acid. The precipitated solid was filtered, dried
and crystallized from ethanol to give 0, 21 g 6 in yield 58% as yellow
crystals. Mp 178–180 ꢂC. IR (KBr, v cmꢀ1): 3191 (NH), 1655 (CO),
4.1.6. Reaction of phthalazine hydrazide derivative 5 with urea and/
or thiourea
A mixture of0.3 g the acetic acid hydrazide 5 (0.001 mol) andurea
or thioure (0.001 mol) was heated in oil bath at 195 ꢂC for 8 h. After
cooling,thestickymasswasdissolvedin30 mL8%sodiumhydroxide,
filtered, and the filtrate was acidified with 2 N HCl. The solid was
collected by filtration, dried and crystallized from the proper solvent
to give triazolo phthalazine derivatives 8a,b, respectively.
1240 (CS). 1H NMR (300 MHz, DMSO-d6,
d ppm): 2.34 (s, 6H, 2 CH3),
5.02 (s, 2H, CH2CO), 7.06 (s, 1H, NH exchangeable with D2O), 7.26–
7.76 (Ar–H). MS (m/z, %): 264 (Mþ–C2N2OS, 23), 103 (41), 64 (100).
Anal. (C19H16N4O2S).
4.1.6.1. 5-[4-(3,4-Dimethylphenyl)-1(2H)-oxo-phthalazin-2-yl]methyl-
1,2,4-triazol-3-one (8a). 0.15 g 8a in yield 43% as colorless crystals
from ethyl acetate. Mp 156–158 ꢂC. IR (KBr, v cmꢀ1): 3290 (NH),
4.1.11. Reaction of 11 with CH3I
To a mixture of absolute ethanol 20 mL containing KOH (0.05 g,
0.001 mol), compound 11 (0.36 g, 0.001 mol) methyl iodide
(0.001 mol) was added. The reaction mixture was stirred overnight
and poured onto water. The precipitated solid was collected by
filtration, dried and crystallized from ethanol to give 1,2-dihydro-4-
(3,4-dimethylphenyl)-2-[(5-methylthio)-1,3,4-oxadiazol-2-yl]ph-
thalazine (12); 0.19 g in yield 50% as colorless crystals. Mp
1650, 1634 (2CO); 1H NMR (300 MHz, DMSO-d6,
d ppm): 2.0(s, 1H,
NH, exchangeable with D2O), 2.34 (s, 6H, 2 CH3), 4.46(s, 2H, CH2),
7.20–8.10 (m, 7H, Ar–H), 8.0 (s, 1H, CONH, exchangeable with D2O).
Anal. (C19H17N5O2).
4.1.6.2. 2-[(5-mercapto-4H-1,2,4-triazol-3-yl)methyl]-4-(3,4-dime-
thylphenyl)-phthalazin-1(2H)-one (8b). 0.18 g 8b in yield 51% as
120–124 ꢂC. 1H NMR (300 MHz, DMSO-d6,
d ppm): 2.34 (s, 6H, 2

M.S.M. Abd alla et al. / European Journal of Medicinal Chemistry 45 (2010) 1267–1277
1275
CH3), 2.55 (s, 3H, SCH3), 5.10 (s, 2H, CH2), 7.18–7.80 (m, 7H, Ar–H).
Anal. (C20H18N4O2S).
as colorless crystals from petroleum ether 40–60 ꢂC. Mp 191–
194 ꢂC. IR (KBr, v cmꢀ1): 3219 (NH), 1701, 1632 (CO); 1H NMR
(300 MHz, DMSO-d6,
d ppm): 1.94(s, 3H, CH3), 2.40 (s, 6H, 2 CH3),
4.1.12. Reaction of phthalazine hydrazide derivative 5 with acid
chlorides
4.48 (s, 1H, CH), 7.0(s, 1H, NH, exchangeable with D2O), 7.20–8.00
(m, 7H, Ar–H). Anal. (C19H17N4O2).
A mixture of 0.5 g the acetic acid hydrazide 5 (0.002 mol) and
benzoyl chloride or acetyl chloride (0.004 mol) in 20 mL dry N,N-
dimethylformamide containing few drops of triethylamine was
refluxed for 14 h. After cooling, the reaction mixture poured onto
ice water. The precipitated solid was collected by filtration, dried
and crystallized from the proper solvent to give 13a,b, respectively.
4.1.15. N0-(2-cyanoethyl)-2-(4-(3,4-dimethylphenyl)-1-
oxophthalazin-2(1H)-yl)acetohydrazide (16)
A mixture of 0.3 g the acetic acid hydrazide 5 (0.001 mol) and
0.1 g acrylonitrile (0.001 mol) in 20 mL pyridine was refluxed for
13 h. After cooling, the reaction mixture poured onto ice water and
HCl. The precipitated solid was collected by filtration, dried and
crystallized from methanol to give 0.24 g 16 in yield 63% as pale
4.1.12.1. N-Benzoyl-1-{2-[4-(3,4-dimethylphenyl)-1(2H)-oxo-phtha-
lazin-2-yl]aceto}hydrazide (13a). 0.7 g 13a in yield 82% as colorless
crystals from toluene. Mp > 350 ꢂC. IR (KBr, v cmꢀ1): 3295, 3200 (2
yellow crystals. Mp 160–163 ꢂC. IR (KBr, v cmꢀ1): 3203 (NH), 2200
1
(CN), 1630 (CO). H NMR (300 MHz, DMSO-d6,
d ppm): 2.0 (s, 1H,
NH), 1658 (CO). 1H NMR (300 MHz, DMSO-d6,
d
ppm): 2.37 (s, 6H, 2
NHCH2, exchangeable with D2O), 2.30 (s, 6H, 2 CH3), 3.02 (t,
J ¼ 10.0 Hz, 2H, NHCH2), 3.17 (t, J ¼ 10.0 Hz, 2H, CH2CN), 5.00 (s, 2H,
CH2CO), 7.20–8.30 (m, 7H, Ar–H), 8.0 (s, 1H, CONH, exchangeable
with D2O). Anal. (C21H21N5O2).
CH3), 5.10 (s, 2H, CH2), 7.27–8.50 (m, 12H, Ar–H), 10.08(s, 1H, CONH,
exchangeable with D2O), 10.21 (s, 1H, NHCOPh, exchangeable with
D2O). MS (m/z, %): 263 (100), 105 (30), 77 (72). Anal. (C25H22N4O3).
4.1.12.2. N-Acetyl-1-{2-[4-(3,4-dimethylphenyl)-1(2H)-oxo-phthala-
zin-2-yl]aceto}hydrazide (13b). 0.62 g 13b in yield 85% as colorless
crystals from toluene. Mp 300–302 ꢂC. IR (KBr, v cmꢀ1): 3298, 3165
4.1.16. Reaction of phthalazine hydrazide derivative 5 with
isothiocyanate derivatives
A mixture of 0.5 g the acetic acid hydrazide 5 (0.002 mol) and
isothiocyanate derivatives namely, phenyl, benzyl, and/or methyl
(0.002 mol) in 20 mL dry N,N-dimethylformamide containing few
drops of triethylamine was refluxed for 24 h. After cooling, the
reaction mixture poured onto ice water and HCl. The precipitated
solid was collected by filtration, dried and crystallized from the
proper solvent to give 17a–c, respectively.
(2 NH), 1661 (CO). 1H NMR (300 MHz, DMSO-d6,
d): 2.04 (s, 3H,
COCH3), 2.32 (s, 6H, 2 CH3), 5.33 (s, 2H, CH2), 7.26–7.74 (m, 10H, Ar–
H), 10.10 (s, 2H, 2 NH, exchangeable with D2O). Anal. (C20H20N4O3).
4.1.13. Reaction 13a,b with phosphorus oxychloride
To 5 mL phosphorus oxychloride, 13a and/or 13b (0.001 mol)
was added portionwise with stirring at 0 ꢂC. The temperature was
elevated gradually to 150 ꢂC and the temperature was kept for 6 h.
After cooling, the reaction mixture poured onto ice water. The
precipitated solid was collected by filtration, dried and crystallized
from the proper solvent to give 14a,b, respectively.
4.1.16.1. 1-{2-[4-(3,4-dimethylphenyl)-1-oxophthalazin-2(1H)-yl]
acetyl}-4-phenylthiosemicarbazide (17a). 0.65 g 17a in yield 72% as
colorless crystals from toluene. Mp > 350 ꢂC. IR (KBr, v cmꢀ1): 3338,
3294, 3154 (3 NH),1663 (CO). 1H NMR (300 MHz, DMSO-d6,
d ppm):
2.0 (s,1H, NHCS, exchangeable with D2O), 2.34 (s, 6H, 2 CH3), 5.10 (s,
2H, COCH2), 6.81–8.19 (m, 12H, Ar–H), 10.08 (s, 1H, CONH,
exchangeable with D2O), 12.52 (s, 1H, NHPh, exchangeable with
D2O). Anal. (C25H23N5O2S).
4.1.13.1. 4-(3,4-Dimethylphenyl)-2-[(5-phenyl-1,3,4-oxadiazol-2-yl)
methyl] phthalazin-1(2H)-one (14a). 0.24 g 14a in yield 58% as dark
brown crystals from ethanol. Mp 201–204 ꢂC. IR (KBr, v cmꢀ1): 1649
(CO). 1H NMR (300 MHz, DMSO-d6,
d ppm): 2.32 (s, 6H, 2 CH3), 5.47
(s, 2H, CH2), 7.45–8.19 (m, 12H, Ar–H). Anal. (C25H20N4O2).
4.1.16.2. 1-{2-[4-(3,4-dimethylphenyl)-1-oxophthalazin-2(1H)-yl]
acetyl}-4-benzylthiosemicarbazide (17b). 0.64 g 17b in yield 68% as
colorless crystals from toluene. Mp 290–294 ꢂC. IR (KBr, v cmꢀ1):
3294, 3228, 3154 (3 NH), 1653 (CO), 1274 (CS). 1H NMR (300 MHz,
4.1.13.2. 4-(3,4-Dimethylphenyl)-2-[(5-methyl-1,3,4-oxadiazol-2-yl)
methyl] phthalazin-1(2H)-one (14b). 0.24 g 14b in yield 69% as
reddish brown crystals from ethanol. Mp 130–132 ꢂC. IR (KBr, v
DMSO-d6, d ppm): 2.35 (s, 6H, 2 CH3), 5.10(s, 2H, COCH2), 5.80(s, 2H,
cmꢀ1): 1657 (CO). 1H NMR (300 MHz, DMSO-d6,
d
ppm): 2.29 (s, 6H,
CH2Ph), 7.20–8.53 (m, 12H, Ar–H), 10.08(s, 1H, CONH, exchangeable
with D2O), 12.10 (s, 1H, NHCS, exchangeable with D2O), 12.15 (s, 1H,
CSNHCH2, exchangeable with D2O). Anal. (C26H25N5O2S).
2 CH3), 2.50 (s, 3H, CH3), 5.40 (s, 2H, CH2), 7.10–8.01 (m, 7H, Ar–H).
MS (m/z, %): 346 (Mþ, 12), 263 (100), 249 (6). Anal. (C20H18N4O2).
4.1.14. Reaction 13a,b with sodium ethoxide
4.1.16.3. 1-{2-[4-(3,4-dimethylphenyl)-1-oxophthalazin-2(1H)-yl]
acetyl}-4-methylthiosemicarbazide (17c). 0.55 g 17c in yield 70% as
colorless crystals from ethanol. Mp 234–238 ꢂC. IR (KBr, v cmꢀ1):
3298, 3221, 3153 (3 NH), 1660 (CO), 1234 (CS). 1H NMR (300 MHz,
To a solution of sodium ethoxide (0.23 g Na in 20 mL abs.
ethanol), 13a and/or 13b (0.001 mol) was added. The reaction
mixture was refluxed for 5 h. After cooling, the reaction mixture
poured onto ice/HCl. The precipitated solid was collected by
filtration, dried and crystallized from the proper solvent to give
15a,b, respectively.
DMSO-d6,
d ppm): 2.00 (s, 3H, NHCH3), 2.10 (s, 1H, NHCS,
exchangeable with D2O), 2.34 (s, 6H, 2 CH3), 5.08 (s, 2H, COCH2),
7.34–8.12 (m, 7H, Ar–H), 10.10 (s, 1H, CONH, exchangeable with
D2O). Anal. (C20H21N5O2S).
4.1.14.1. 2-(4,5-Dihydro-3-phenyl-5-oxo-1H-pyrazol-4-yl)-4-(3,4-
dimethylphenyl)phthalazin-1(2H)-one (15a). 0.3 g 15a in yield 75%
as colorless crystals from ethanol. Mp 238–240 ꢂC. IR (KBr, v cmꢀ1):
4.1.17. Reaction of phthalazine hydrazide derivative 5 with
isocyanate derivatives
3190 (NH), 1694, 1653 (CO); 1H NMR (300 MHz, DMSO-d6,
d
ppm):
A mixture of 0.5 g the acetic acid hydrazide 5 (0.002 mol) and
isocyanate derivatives namely, phenyl, and/or ethyl (0.004 mol) in
20 mL dry N,N-dimethylformamide was refluxed for 18 h. After
cooling, the reaction mixture poured onto ice water. The precipi-
tated solid was collected by filtration, dried and crystallized from
the proper solvent to give 18a,b, respectively.
2.38 (s, 6H, 2 CH3), 4.40 (s, 1H, CH), 7.10 (s, 1H, NH, exchangeable
with D2O), 7.20–8.50 (m, 12H, Ar–H). Anal. (C24H19N4O2).
4.1.14.2. 2-(4,5-Dihydro-3-methyl-5-oxo-1H-pyrazol-4-yl)-4-(3,4-
dimethylphenyl)phthalazin-1(2H)-one (15b). 0.24 g 15b in yield 72%

1276
M.S.M. Abd alla et al. / European Journal of Medicinal Chemistry 45 (2010) 1267–1277
4.1.17.1. 1-{2-[4-(3,4-dimethylphenyl)-1-oxophthalazin-2(1H)-yl]
acetyl}-4-phenylsemicarbazide (18a). 0.64 g 18a in yield 73% as
colorless crystals from toluene. Mp 196–200 ꢂC. IR (KBr, v cmꢀ1):
70.5% as faint yellow crystals. Mp 268–280 ꢂC. IR (KBr, v cmꢀ1):
1668, 1660, 1649 (3 CO). 1H NMR (300 MHz, DMSO-d6,
ppm): 2.30
(s, 3H, CH3), 2.34 (s, 6H, 2 CH3), 2.50 (s, 2H,CH2), 4.97 (s, 2H, CH2),
7.5–8.6 (m, 7H, Ar–H). MS (m/z, %): 386 (Mþ–2, 4), 263 (100). Anal.
(C22H20N4O3).
d
3204 (NH), 1664 (CO); 1H NMR (300 MHz, DMSO-d6,
d ppm): 2.33
(s, 6H, 2 CH3), 4.92 (s, 2H, COCH2), 6.01 (s, 1H, NHCO, exchangeable
with D2O), 7.26–8.40 (m, 12H, Ar–H), 9.26 (s, 1H, NHPh,
exchangeable with D2O), 10.14 (s, 1H, CONH, exchangeable with
D2O). Anal. (C25H23N5O3).
4.1.22. 2-[(6-methyl-7H-pyrazolo[5,1-c][1,2,4]triazol-3-yl)methyl]-
4-(3,4-dimethylphenyl)phthalazin-1(2H)-one (23)
Hydrazine hydrate (98%) 0.5 cm3 was added to a solution of 0.4 g
22 (0.001 mol) in 10 cm3 absolute ethanol. The reaction mixture
was refluxed for 6 h, after cooling the obtained solid was filtered off
and crystallized from ethanol to give 0.32 g 23 in yield 84.2% as
4.1.17.2. 1-{2-[4-(3,4-dimethylphenyl)-1-oxophthalazin-2(1H)-yl]
acetyl}-4-ethylsemicarbazide (18b). 0.60 g 18b in yield 76% as color-
less crystals from toluene. Mp 250–252 ꢂC. IR (KBr, v cmꢀ1): 3291,
3262, 3157 (3 NH), 1692 (CO). 1H NMR (300 MHz, DMSO-d6,
d
ppm):
colorless crystals. Mp 240–244 ꢂC; IR (KBr): v ¼ 1664ðCOÞ cmꢀ1
;
1.00 (t, J, 10 Hz, 3H, CH3CH2), 2.30 (s, 6H, 2 CH3), 3.03 (q, J, 10 Hz, 3H,
CH3CH2), 4.8 (s, 2H, COCH2), 7.30–8.30 (m, 7H, Ar–H), 9.90(s, 1H,
CONH, exchangeable with D2O), 6.37 (s,1H, NHCO, exchangeablewith
D2O), 6.19(s,1H, NHCH2, exchangeable with D2O). Anal. (C21H23N5O3).
1H NMR (DMSO-d6, 300 MHz):
d
¼ 1.94 (s, 3H, CH3), 2.46 (s, 6H,
2CH3), 2.60 (s, 2H,CH2), 5.30 (s, 2H,CH2), 7.28–8.50 (m, 7H, Ar–H)
ppm; MS: m/z (%) ¼ 250 (Mþ, 81), 249 (100). Anal. (C22H20N6O).
4.1.23. Reaction of phthalazine hydrazide derivative 5 with acetyl
acetone
4.1.18. Reaction of phthalazine hydrazide derivative 5 with triethyl
orthoformate in acetic anhydride
A mixture of 0.6 g the acetic acid hydrazide 5 (0.002 mol) and
0.30 g acetyl acetone (0.003 mol) in 20 mL ethanol was refluxed for
13 h. After cooling the obtained solid was collected, dried and
crystallized from ethanol to give 2-(4-(3,4-dimethylphenyl)-1-
oxophthalazin-2(1H)-yl)-N0-(4-oxopentan-2-ylidene)acetohy-
drazide 24; 0.62 g in yield 77.5% as faint yellow crystals. Mp
206–209 ꢂC. IR (KBr, v cmꢀ1): 3191(NH), 1655, 1630 (2CO); 1H NMR
A mixture of 0.6 g the acetic acid hydrazide 5 (0.002 mol) and
0.5 mL triethyl orthoformate were refluxed in 5 mL acetic anhy-
dride for 6 h. The solution was allowed to cool and then the
formed solid was collected, dried and crystallized from ethanol to
give
N0,N0-diacetyl-2-(4-(3,4-dimethylphenyl)-1-oxophthalazin-
2(1H)-yl)acetohydrazide (19); 0.66 g in yield 80.5% as colorless
crystals. Mp 180–184 ꢂC. IR (KBr, v cmꢀ1): 3194 (NH), 1667, 1619
(300 MHz, DMSO-d6,
d
ppm): 1.96 (s, 3H, N ¼ CCH3), 2.29 (s, 3H,
(4CO). 1H NMR (300 MHz, DMSO-d6,
d
ppm): 2.30 (s, 6H, 2 CH3),
OCCH3), 2.36 (s, 6H, 2 CH3), 2.54 (s, 2H, N]CCH2), 4.83 (s, 2H,CH2),
7.50–8.20 (m, 7H, Ar–H), 10.60 (s, 1H, NH, exchangeable with D2O).
Anal. (C23H24N4O3).
2.48 (s, 6H, 2 COCH3), 5.30 (s, 2H, COCH2), 7.30–8.30 (m, 7H, Ar–
H), 8.32 (s, 1H, NH, exchangeable with D2O). Anal. (C24H22N4O4).
4.1.19. Reaction of phthalazine hydrazide derivative 5 with triethyl
orthoformate
4.1.24. 2-(2-(3,5-Dimethyl-1H-pyrazol-1-yl)-2-oxoethyl)-4-(3,4-
dimethylphenyl)phthalazin-1(2H)-one (25)
A mixture of 0.6 g the acetic acid hydrazide 5 (0.002 mol) and
5 mL triethyl orthoformatewererefluxed for 13 h on steam bath. The
formed solid was collected, dried and crystallized from ethyl acetate
to give N0-(ethoxymethylene)-2(4-(3,4-dimethylphenyl)-1-oxoph-
thalazine-2(1H)-yl)acetohydrazide (20); 0.54 g in yield 71.1% as
colorless crystals. Mp 218–222 ꢂC. IR (KBr, v cmꢀ1): 3350, 3300
To a solution of sodium ethoxide (0.23 g Na in 20 mL abs.
ethanol), 0.39 g 24 (0.001 mol) was added. The reaction mixture
was refluxed for 11 h. After cooling, the reaction mixture poured
onto ice/HCl. The precipitated solid was collected by filtration, dried
and crystallized from ethyl acetate to give compound 25; 0.35 g in
yield 89.7% as faint brown crystals. Mp 102–106 ꢂC. IR (KBr, v cmꢀ1):
(NH2), 3250 (NH),1670 (2CO).1H NMR (300 MHz, DMSO-d6,
d
ppm):
1648 (CO). 1H NMR (300 MHz, DMSO-d6,
d ppm): 2.30 (s, 3H, CH3),
1.30 (t, J, 10 Hz, 3H, CH3CH2), 2.30 (s, 6H, 2CH3), 4.10 (q, J, 10 Hz, 3H,
CH3CH2), 5.30 (s, 2H, COCH2), 7.40 (s, 1H, CH]N), 7.30–8.30 (m, 7H,
Ar–H),10.32 (s,1H, NH, exchangeable with D2O). Anal. (C21H19N4O3).
2.36 (s, 6H, 2CH3), 2.48 (s, 3H, CH3), 4.64 (s, 2H, CH2), 6.18 (s, H, CH),
7.50–8.20 (m, 7H, Ar–H). Anal. (C23H22N4O2).
4.1.25. Fusion of the hydrazide derivative 5
4.1.20. Reaction of N0-(ethoxymethylene)-2(4-(3,4-dimethylphenyl)-
1-oxophthalazine-2(1H)-yl)acetohydrazide (20) with hydrazine
hydrate in benzene
To a solution of 0.76 g 20 (0.002 mol) in 10 mL benzene, 0.2 mL
hydrazine hydrate 100% was added. The reaction mixture was
refluxed for 9 h. After cooling the obtained solid was collected,
dried and crystallized from ethyl acetate to give compound 21;
0.62 g in yield 86.1% as colorless crystals. Mp 248–250 ꢂC. IR (KBr, v
cmꢀ1): 3190 (NH), 1640 (2 CO); 1H NMR (300 MHz, DMSO-d6,
The hydrazide derivative 5 (0.6 g, 0.002 mol) was heated in an
oil bath at 200 ꢂC for 1 h. After cooling, crystallize from ethanol to
give 2-(4-(3,4-dimethylphenyl)-1-oxophthalazin-2(1H)-yl)acetic
acid 26; 0.40 g in yield 65.57% as brown crystals. Mp 138–141 ꢂC. IR
(KBr, v cmꢀ1): 2542–3500 (OH), 1701, 1667 (2 CO). 1H NMR
(300 MHz, DMSO-d6,
d ppm): 2.34 (s, 6H, 2CH3), 4.82(s, 2H, CH2),
7.30–8.20 (m, 7H, Ar–H). MS (m/z, %): 307 (Mþꢀ1, 41), 263 (100),
294 (43). Anal. (C18H16N2O3).
d
ppm): 2.34 (s, 6H, 2 CH3), 4.35 (s, 2H, NH2, exchangeable with
4.1.26. Reaction of thiocarbamate derivatives 17a–c with NaOH
(0.001 mol) of thiocarbamate derivatives 17a, 17b, or 17c was
dissolved in sodium hydroxide solution (2 N, 20 mL). The clear
solutionwas heated on a water bath for 2 h, filtered after cooling and
neutralized with dilute hydrochloric acid. The precipitated solid was
collected by filtration, dried and crystallized from the proper solvent
to give the corresponding triazole derivatives 27a–c, respectively.
D2O), 4.51 (s, 1H, CHNH, exchangeable with D2O), 5.21 (s, 2H,
COCH2), 7.50 (s, 1H, CH]N), 7.5–8.6 (m, 7H, Ar–H), 10.58 (s, 1H,
CONH, exchangeable with D2O). MS (m/z, %): 364 (Mþ, 2), 291 (60),
262 (100). Anal. (C19H20N6O2).
4.1.21. 5-methyl-3-oxo-2-[10(2H)-oxo-40-(3,4-dimethylphenyl)
phthalazin-20-ylmethylcarbonyl]-3,4-dihydropyrazol (22)
A mixture of 0.6 g the acetic acid hydrazide 5 (0.002 mol) and
0.39 g ethylacetoacetate (0.003 mol) in 20 mL ethanol was refluxed
for 7 h. After cooling the obtained solid was collected, dried and
crystallized from diethyl ether to give compound 22; 0.55 g in yield
4.1.26.1. 2-[(5-mercapto-4-phenyl-4H-1,2,4-triazol-3-yl)methyl]-4-
(3,4-dimethylphenyl)phthalazin-1(2H)one (27a). 0.38 g 27a in yield
86% as colorless crystals from ethanol. Mp > 350 ꢂC. IR (KBr, v
cmꢀ1): 3204 (NH), 1670 (CO). 1H NMR (300 MHz, DMSO-d6,
d ppm):

M.S.M. Abd alla et al. / European Journal of Medicinal Chemistry 45 (2010) 1267–1277
1277
2.30 (s, 6H, 2CH3), 4.20 (s, 2H, CH2), 7.00–8.20 (m, 12H, Ar–H), 13.80
(s, 1H, NH, exchangeable with D2O). Anal. (C25H21N5OS).
separated from the underlying muscle layer by insertion of blunt
forceps to form separate cavities into which sponges are inserted.
Four sponges are implanted per rat and each incision is closed by
two stitches.
The sponges were lefted for 10 days during which the tested
compounds or Indomethacin (reference standard) was injected
intraperitoneally. Indomethacin was given at a dose level 20 mg/kg
and tested compounds were given at equimolar dose levels.
Animals in the control group were given the solvent (10% aqueous
solution of Tween 80) at dose volume comparable to the test doses.
The animals are sacrificed, the sponges prepared and dried until the
weight remain constant. The net dry weight after subtracting the
weight of the sponge is determined.
4.1.26.2. 2-[(5-mercapto-4-benzyl-4H-1,2,4-triazol-3-yl)methyl]-4-
(3,4-dimethylphenyl)phthalazin-1(2H)one (27b). 0.36 g 27b in yield
80% as colorless crystals from ethanol. Mp 256–269 ꢂC. IR (KBr, v
cmꢀ1): 3204 (NH), 1663 (CO). 1H NMR (300 MHz, DMSO-d6,
d ppm):
2.30 (s, 6H, 2CH3), 4.42 (s, 2H,CH2), 5.74 (s, 2H,CH2Ph), 7.20–8.19 (m,
12H, Ar–H), 13.45(s, 1H, NH, exchangeable with D2O). Anal.
(C26H23N5OS).
4.1.26.3. 2-[(5-mercapto-4-methyl-4H-1,2,4-triazol-3-yl)methyl]-4-
(3,4-dimethylphenyl)phthalazin-1(2H)one (27c). 0.30 g 27c in yield
78.9% as colorless crystals from ethanol. Mp 250–252 ꢂC. IR (KBr, v
cmꢀ1): 3195 (NH), 1671 (CO). 1H NMR (300 MHz, DMSO-d6,
d
ppm):
4.2.3. Anti-Inflammatory activity
2.34 (s, 6H, 2CH3), 3.0 (s, 3H, CH3), 4.21 (s, 2H, CH2),13.50 (s, 1H, NH,
exchangeable with D2O). Anal. (C20H19N5OS).
One-way Analysis of Variance (ANOVA): F ¼ 2.985
The P value is <0.0001, considered extremely significant. Vari-
ation among column means it is significantly greater than expected
by chance.
Tukey-Kramer Multiple Comparisons Test: If the value of q is
greater than 5.132 then the P value is less than 0.05.
4.1.27. Reaction of thiocarbamate derivatives 17a–c with H2SO4
(0.001 mol) of of thiocarbamate derivatives 17a, 17b, or17c was
mixed with conc. H2SO4 (5 mL), left overnight. The reaction mixture
poured onto ice water, the precipitated solid was collected by
filtration, dried and crystallized from the proper solvent to give
thiadiazol derivatives 28a–c, respectively.
References
4.1.27.1. 4-(3,4-Dimethyl)-2-[(5-phenylamino-1,3,4-thiadiazol-2-yl)
methyl]phthalazin-1-(2H)-one (28a). 0.32 g 28a in yield 72.73% as
colorless crystals from ethanol. Mp 142–146 ꢂC. IR (KBr, v cmꢀ1):
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3215 (NH), 1670 (CO). 1H NMR (300 MHz, DMSO-d6,
d ppm): 2.30 (s,
6H, 2CH3), 5.10 (s, 2H, CH2), 6.81–8.19 (m, 12H, Ar–H), 10.10 (s, 1H,
NH, exchangeable with D2O). Anal. (C25H21N5OS).
4.1.27.2. 4-(3,4-Dimethyl)-2-[(5-benzylamino-1,3,4-thiadiazol-2-yl)
methyl]phthalazin-1-(2H)-one (28b). 0.38 g 28b in yield 84.4% as
colorless crystals from ethanol. Mp 101–104 ꢂC. IR (KBr, v cmꢀ1):
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3215 (NH), 1664 (CO). 1H NMR (300 MHz, DMSO-d6,
d ppm): 2.34 (s,
6H, 2CH3), 4.2 (s, 1H, NH, exchangeable with D2O), 4.35(s, 2H, CH2),
5.10 (s, 2H,CH2Ph), 7.20–8.19 (m, 12H, Ar–H). Anal. (C25H21N5OS).
4.1.27.3. 4-(3,4-Dimethyl)-2-[(5-methylamino-1,3,4-thiadiazol-2-yl)
methyl]phthalazin-1-(2H)-one (28c). 0.32 g 28c in yield 84.2% as
colorless crystals from ethanol. Mp 138–140 ꢂC. IR (KBr, v cmꢀ1):
3190 (NH), 1669 (CO). 1H NMR (300 MHz, DMSO-d6,
d ppm): 2.34 (s,
6H, 2CH3), 2.78 (s, 3H, 2 CH3), 5.10(s, 2H, CH2), 7.34 (s, 1H, NH,
exchangeable with D2O), 7.45–8.19 (m, 12H, Ar–H). Anal.
(C25H21N5OS).
4.2. Anti-inflammatory testing
4.2.1. Animals
Male rats (180–200 g) were used taking into account the inter-
national principles and local, regulations concerning the care and
the use of laboratory animals [28]. The animal had free access to
a standard commercial diet and water, keeping at rooms main-
tained at about 25 ꢂC.
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92(1980), 76533v.
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U. Thibaut, H. Timmerman, J. Med. Chem. 44 (2001) 2523–2535.
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P.C. Isakson, J. Med. Chem. 40 (1997) 1347–1365.
4.2.2. Sponge implantation technique
The sponge implantation technique was described previously
[28]. Sponges used are prepared from polyvinyl foam sheets
(thickness 5 mm). Discs are punched out to a standard size and
weight (2.5 ꢁ 0.05 mg) using a 5.0 mm cork borer. The sponges are
then soaked in 70%v/v ethanol for 30 min, rinsed four times with
distilled water and heated at 80 ꢂC for 2 h. Sponges are implanted in
rats under diethyl ether anesthesia. Four 5 mm ventral incisions are
made, 2 in both groins and axellae on both sides, and the dermis
[27] J.P. Danial, R.J. Carl, Laboratory Text for Organic Chemistry, 1979, pp 363.
[28] P.N. Sexena, Arch. Int. Pharmacodyn. Ther. 126 (1960) 228.