Antimicrobial studies of some novel quinazolinones fused with [1,2,4]-triazole, [1,2,4]-triazine and [1,2,4,5]-tetrazine rings

Article abstract of DOI:10.1016/j.ejmech.2008.05.033

Three series of novel and new fused heterocyclic systems, viz. triazolo[4,3-a]-quinazolin-7-ones (4), [1,2,4,5]-tetrazino[4,3-a]-quinazolin-8-ones (6) and indolo[2,3-c][1,2,4]-triazino[4,3-a]-quinazolin-8-ones (8) have been synthesized from the key intermediate 3-(substituted-phenyl)-2-hydrazino-quinazolin-4-ones (3). Thus, condensation of (3) with appropriate aromatic acids in the presence of DCC in dichloromethane afforded the fused system (4), while reaction of (3) with isatin in methanol gave the corresponding Schiff base (7) which on cyclodehydration furnished another fused heterocyclic system (8). The intermediate (3) on refluxing with substituted-phenylisothiocyanate gave the substituted-thiosemicarbazide (5), which on oxidative cyclization with bromine in CCl₄ furnished the novel fused system (6). The structures of intermediate and final compounds have been determined by means of IR, ¹H NMR, ¹³C NMR, UV and elemental analysis. All the synthesized compounds have been screened for their antibacterial activity against Gram-negative bacteria, Escherichia coli, Pseudomonas aeruginosa and Gram-positive bacteria, Streptococcus pneumoniae, Bacillus subtilis, as well as demonstrated significant antifungal activity against fungi viz. Candida albicans, Aspergillus fumigatus, Aspergillus flavus, and Aspergillus niger.

Full text of DOI:10.1016/j.ejmech.2008.05.033

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European Journal of Medicinal Chemistry 44 (2009) 1188e1197
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Original article
Antimicrobial studies of some novel quinazolinones fused with
[1,2,4]-triazole, [1,2,4]-triazine and [1,2,4,5]-tetrazine rings
*
Sarvesh Kumar Pandey, Abhishek Singh, Ashutosh Singh, Nizamuddin
Department of Chemistry, D.D.U. Gorakhpur University, Civil Lines, Gorakhpur 273001, Uttar Pradesh, India
Received 3 April 2008; received in revised form 22 May 2008; accepted 26 May 2008
Available online 3 June 2008
Abstract
Three series of novel and new fused heterocyclic systems, viz. triazolo[4,3-a]-quinazolin-7-ones (4), [1,2,4,5]-tetrazino[4,3-a]-quinazolin-8-
ones (6) and indolo[2,3-c][1,2,4]-triazino[4,3-a]-quinazolin-8-ones (8) have been synthesized from the key intermediate 3-(substituted-phenyl)-
2-hydrazino-quinazolin-4-ones (3). Thus, condensation of (3) with appropriate aromatic acids in the presence of DCC in dichloromethane
afforded the fused system (4), while reaction of (3) with isatin in methanol gave the corresponding Schiff base (7) which on cyclodehydration
furnished another fused heterocyclic system (8). The intermediate (3) on refluxing with substituted-phenylisothiocyanate gave the substituted-
thiosemicarbazide (5), which on oxidative cyclization with bromine in CCl4 furnished the novel fused system (6). The structures of intermediate
1
and final compounds have been determined by means of IR, H NMR, 13C NMR, UV and elemental analysis. All the synthesized compounds
have been screened for their antibacterial activity against Gram-negative bacteria, Escherichia coli, Pseudomonas aeruginosa and Gram-positive
bacteria, Streptococcus pneumoniae, Bacillus subtilis, as well as demonstrated significant antifungal activity against fungi viz. Candida albicans,
Aspergillus fumigatus, Aspergillus flavus, and Aspergillus niger.
Ó 2008 Elsevier Masson SAS. All rights reserved.
Keywords: Quinazolinone; Antibacterial; Antifungal activity
1. Introduction
1,2,4,5-Tetrazines are an important class of heterocycles
that find many practical and synthetic applications [12]. In
addition, some tetrazoles have been introduced in the design
of non-peptide ligands for growth hormone secretagogue
(GHS) receptors [13], which shows competitive inhibition
potency for the carbapenem and cephamycin-resistant dinu-
clear zinc mettalo-b-lactamase from Bacteroides fragilis
[14], and used for treatment of type 2 diabetes [15].
Similarly, derivatives of 1,2,4-triazole and 1,2,4-triazine
have been found to possess wide spectrum of pharmacological,
medicinal and biological activities [16e19]. The indole nucleus
plays an important role as a common denominator for various
biocidal activities [20e22].
The pharmacodynamic versatility of 4-quinazolinone moi-
ety has been documented not only in many of its synthetic de-
rivatives but also in several naturally occurring alkaloids
isolated from animals, families of plant kingdoms and from
microorganism [1e3]. These isolated quinazolinones deriva-
tives were found to have wide range of biological properties
including anti-tumour, sedative, analgesic, antidiabetic, antibac-
terial, anti-inflammatory, antifungal and anticancer [4e10]. In
addition, characterization of potential N-methyl-D-aspartate
(NMDA) and cholecystokinin antagonists II-lipophilicity stud-
ies on quinazolinones are also documented [11].
In light of the above observations and keeping in mind that
most of the biologically active quinazolinones are either C-2
or N-3 mono- and/or disubstituted derivatives, we wish to fuse
indole, 1,2,4-triazole, 1,2,4-triazine and 1,2,4,5-tetrazine nuclei
in between N-1 and C-2 positions of quinazolinone ring to
get novel fused systems, triazolo[4,3-a]-quinazolin-7-ones,
* Corresponding author. Tel.: þ91 9415692632 (mob).
E-mail addresses: skpandey1982@yahoo.co.in (S.K. Pandey), prnukhan@
yahoo.co.in (A. Nizamuddin).
0223-5234/$ - see front matter Ó 2008 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2008.05.033

S.K. Pandey et al. / European Journal of Medicinal Chemistry 44 (2009) 1188e1197
1189
tetrazino[4,3-a]-quinazolin-8-ones and indolo[2,3-c][1,2,4]-
triazino[4,3-a]-quinazolin-8-ones, which have not been
reported and studied so far. This structural manipulation
combines different biodynamic heterocyclic moieties in a par-
ent lead compound quinazolinone, which might have encour-
aging pharmacological potential.
Moreover, it was considered of interest to substitute various
groups on phenyl rings to investigate the influence of such
structural variations on the anticipated biological activities.
The above facts and anticipations coupled with our desire
to develop efficacious antimicrobial agents and in continuation
of our work on fused heterocycles with biological interest
[23e26] prompted us to device an efficient and convenient
synthetic method of hitherto unknown and novel title
compounds triazolo[4,3-a]-quinazolin-7-ones, tetrazino[4,3-
a]-quinazolin-8-ones and indolo[2,3-c][1,2,4]-triazino[4,3-a]-
quinazolin-8-ones. The simple synthesis and antimicrobial
results of these newly synthesized compounds are reported
in this paper.
(>C]N) and 2645e2650 cmꢀ1 (eSH). The disappearance
of peaks at 2645e2650 cmꢀ1 and appearance of new peaks
at 1217e1221 cmꢀ1 of thioether (CeSeC) in (2) clearly indi-
cates the methylation at sulfur atom. The band of these thio-
ethers disappeared in the IR spectra of compounds (3). The
appearance of broad bands at 3425e3433 cmꢀ1 (eNH and
eNH2) are more evident for the displacement of eSCH3 group
of (2) by hydrazine hydrate. The IR spectra of compounds (4)
showed only the significant bands at 1660e1670 cmꢀ1 due to
the carbonyl group. The oxidative cyclization of compounds
(5) to compounds (6) was confirmed by the presence of peaks
at 1220e1235 cmꢀ1 (>C]S), 3300e3310 cmꢀ1 (eNeH)
and weak bands at1440e1450 cmꢀ1 (NeN). In the IR spectra
of (7), peaks at 1660e1675 cmꢀ1 and 1650e1660 cmꢀ1 indi-
cate the presence of carbonyl group of amide linkages in five
and six membered rings, respectively, and broad bands at
3190e3200 cmꢀ1 (eNeH). The only prominent peaks at
1655e1665 cmꢀ1 due to carbonyl group of six membered
amide in the IR spectra of (8) indicate the cyclodehydration
of (7) into (8). The other bands of compounds (7) disappeared.
2. Chemistry
3.2. NMR studies
The required starting 3-(substituted-phenyl)-2-mercapto-
quinazolin-4-ones (1) were synthesized from anthranilic acid
and substituted-phenylisothiocyanates. Methylation of (1)
with methyl iodide in the presence of fused sodium acetate
in ethanol afforded 3-(substituted-phenyl)-2-mercaptomethyl-
quinazolin-4-ones (2) in good yields. Nucleophilic displace-
ment of mercaptomethyl group of (2) with hydrazine hydrate
yielded the desired key intermediates (3) in excellent yields.
The condensation reaction between key intermediates (3)
and appropriate aromatic acids in the presence of DCC fur-
nished, triazolo[4,3-a]quinazolin-7-ones (4), while the reac-
tion of appropriate phenylisothiocyanates with intermediates
(3) in methanol afforded corresponding thiosemicarbazides
(5), which on oxidative cyclization with bromine in carbon-
tetrachloride furnished tetrazino[4,3-a]quinazolin-8-ones (6).
Schiff bases (7) were synthesized by refluxing the intermedi-
ates (3) and isatin in methanol, which on cyclodehydration
with cold concentrated H2SO4 yielded indolo[2,3-c][1,2,4]tri-
azino[4,3-a] quinazolin-8-ones (8).
1H NMR spectra of compounds (1) showed multiplet at
d 7.2e8.5 ppm for aromatic protons (8H) and singlets at
d 2.9e3.3 ppm for eSH protons. The appearance of new
singlets in the 1H NMR spectra of compound (2) at d
2.4e2.8 ppm for mercaptomethyl (eSCH3) protons clearly
indicates the methylation at sulfur atom. The 1H NMR spectra
of (3) displayed a triplet and doublet like signals at d 8.2e
8.4 ppm and d 4.5e4.8 ppm corresponding to eNH and e
NH2 protons of hydrazino functionality, respectively. The
disappearance of signals corresponding to the protons of
hydrazino functionality (eNHNH2) and appearance of multi-
plets for aromatic proton in the range of d 7.1e8.6 ppm clearly
indicate the formation of (4).
In the 1H NMR spectra of compounds (5) a quartet like sig-
nal observed at d 8.5e8.7 ppm is due to three eNH protons,
while, aromatic protons resonate at d 7.1e8.3 ppm. The for-
mation of (6) was confirmed by the presence of only a thioa-
mide proton at d 7.8e8.3 ppm and multiplet at d 7.0e8.4 ppm.
Other signals disappeared. The two singlets at d 8.2e8.3 and
1
3. Results and discussion
d 8.7e8.9 ppm in the H NMR spectra of compounds (7) are
due to eNeNeH and amide protons, while multiplet at
d 6.9e8.5 ppm is due to aromatic protons. The disappearance
of these signals and appearance of only a multiplet d 6.8e
All the final compounds (4e8) were prepared in good
yields. The physical parameters of these compounds are men-
tioned in Section 6 and the synthetic route is given in Scheme
1. The structures of the intermediate and final compounds have
been elucidated based on their elemental analysis, UV, IR, H
NMR, 13C NMR and D2O exchange studies.
1
8.4 ppm in the H NMR spectra of (8) suggest cyclodehydra-
tion of compound (7) into (8). The signals at d 8.4 ppm,
8.2 ppm, 8.3 ppm and 8.9 ppm were exchanged with D2O.
Another strong support for the structures of (4), (6) and (8)
is the 13C NMR spectra. The 13C NMR spectra of compounds
were taken in DMSO and the signals obtained were all in
a good agreement with the proposed structures. In the 13C
NMR spectrum of compound 3b 12 peaks were observed.
The carbonyl and imine carbons of quinazolinone ring are
resonates at d 170.0 ppm and 160.1 ppm, respectively. The
aromatic carbon atoms resonate at d 124.2e141.2 ppm. In
1
3.1. IR studies
IR spectra of compounds (1e8) showed useful information
about the structure of the compounds.
The IR spectra of compounds (1) exhibited characteristic
bands at 1670e1680 cmꢀ1 (>C]O), 1620e1630 cmꢀ1

1190
S.K. Pandey et al. / European Journal of Medicinal Chemistry 44 (2009) 1188e1197
R
R
O
N
O
N
NCS
NH2
R
(b)
N
N
(a)
COOH
SCH3
SH
(1)
(2)
R
R
(c)
O
O
O
N
R
N
H
O
N
O
N
NCS
N
N
N
N
NH
R'
NH
N
H
N
H
O
(e)
(g)
NHNH2
S
HN
(3)
R'
(f)
(5)
(7)
COOH
R'
R
(d)
(h)
R
O
R
O
N
N
S
O
N
N
N
N
NH
N
N
N
N
N
N
N
R'
(6)
R'
4a : R= H, R'= H
(4)
(8)
5a, 6a : R= H, R'= H
1a,2a,3a :R= 4-CH3
1b,2b,3b :R= H
1c,2c,3c :R= 4-OCH3
1d,2d,3d :R= 4-Cl
4b : R= H, R'= 2-CH3
4c : R= H, R'= 2-Cl
4d : R= 4-CH3,R'= H
5b, 6b : R= H, R'= 4-CH3
5c, 6c : R= H, R'= 4-OCH3
5d, 6d : R= 4-CH3, R'= H
4e : R= 4-CH3,R'= 2-CH3
4f : R= 4-CH3,R'= 2-Cl
4g : R= 4-OCH3,R'= H
5e, 6e : R= 4-CH3, R'= 4-CH3
7a, 8a : R= H
4h : R= 4-OCH3,R'= 2-CH3
4i : R= 4-OCH3,R'= 2-Cl
4j : R= 4-Cl, R'= H
7b, 8b : R= 4-CH3
7c, 8c : R= 4-OCH3
7d, 8d : R= 4-Cl
4k : R= 4-Cl, R'= 2-CH3
4l : R= 4-Cl, R'= 2-Cl
Scheme 1. Reagents and conditions: (a) Me2CO, reflux for 6 h, (b) CH3COONa, CH3I, 4 h, stirring, (c) NH2NH2H2O, reflux for 6 h, (d) DCC, CH2Cl2, 4 h, (e)
MeOH, reflux for 6 h, (f) Br2/CCl4, 30 min, stirring, (g) MeOH, reflux for 3 h, (h) conc. H2SO4, 5e10 ꢁC, 2 h.
the 13C NMR spectrum of compound 4a 17 peaks were
observed. Peak at d 173.4 ppm is due to carbonyl carbon,
d 149.2e151.3 ppm is of triazole ring carbon atoms and
d 122.4e140.1 ppm for aromatic carbons. In the 13C NMR
spectrum of compound 6b 18 peaks were observed. Peak at
d 190.1 ppm is attributed to thiocarbamide carbon flanked
with two nitrogen atoms, d 170.3 ppm due to carbonyl carbon
and other peaks were observed at d 121.0e157.1 ppm are due
to aromatic and imine carbon atoms. The 13C NMR spectrum
of compound 8c showed 21 signals. Carbonyl carbon resonates
at d 175.0 ppm, d 163.1e166.8 ppm is due to imine carbons,
different aromatic carbons were resonate at d 120.9e
152.1 ppm and methoxy carbon atom at d 51.2 ppm.
The antibacterial data (Table 1) revealed that all tested
compounds of this investigation are moderate to highly active
against all the tested pathogenic bacteria. In general, the com-
pounds 4i, 4l, 6c and 8d having p-methoxy, p-chloro and
o-chloro substituent were showed very promising activity
with MIC 1.56 mg/mL and 3.12 mg/mL against both Gram-
positive B. subtilis and Gram-negative E. coli, P. aeruginosa
whereas the rest of the compounds showed moderate activ-
ity with MIC 6.25 mg/mL, 12.5 mg/mL, 25 mg/mL and
50 mg/mL as compared to the standard drug Ciprofloxacin
(MIC ¼ 1.56 mg/mL, 3.12 mg/mL and 6.25 mg/mL). Com-
pounds 8d and 6c were equipotent as Ciprofloxacin against
P. aeruginosa while, compound 4l was more potent than stan-
dard drug against S. pneumoniae. Therefore, it can be inferred
that presence of polar substitutent imparts much towards anti-
bacterial power of these compounds. The data also revealed
that the activity of compound 4l > 4i > 8d > 6c. The fusion
of different heterocyclic rings in between N-1 and C-2 of
parent quinazolinone viz. 1,2,4-triazole, 1,2,4-triazine and
1,2,4,5-tetrazine exerts a significance influence on the antibac-
terial activity. The presence of triazole ring showed greater
activity than that of triazine and tetrazine. The most active
compound was 4l, which contains a triazole ring. This indi-
cates that the presence of triazole moiety is additive towards
antibacterial activity in this class of compounds.
4. Biological screening
4.1. Antibacterial screening
Preliminary experiments were carried out to determine
the antibacterial activities of titled compounds in vitro
against (i) Gram-positive bacteria: Streptococcus pneumoniae,
Bacillus subtilis and (ii) Gram-negative bacteria: Escheri-
chia coli, Pseudomonas aeruginosa by disc diffusion method
[27].

S.K. Pandey et al. / European Journal of Medicinal Chemistry 44 (2009) 1188e1197
1191
Table 1
Antibacterial activities of compounds [4ae8d]
Compound no.
R
R0
MICs (mg/mL)
E. coli
P. aeruginosa
S. pneumoniae
B. subtilis
4a
4b
H
H
50
25
>50
50
50
25
H
2-CH3
2-Cl
H
>50
25
>50
50
4c
4d
H
12.5
25
6.25
25
4-CH3
4-CH3
4-CH3
4-OCH3
4-OCH3
4-OCH3
4-Cl
4-Cl
4-Cl
H
50
25
50
4e
2-CH3
2-Cl
H
25
>50
6.25
6.25
3.12
1.56
12.5
25
>50
25
4f
4g
12.5
12.5
6.25
3.12
6.25
12.5
1.56
>50
50
12.5
6.25
25
12.5
12.5
3.12
6.25
12.5
1.56
>50
50
4h
4i
2-CH3
2-Cl
H
6.25
12.5
25
4j
4k
2-CH3
2-Cl
H
4l
6a
3.12
50
3.12
25
6b
6c
H
4-CH3
4-OCH3
H
50
25
25
H
6.25
25
3.12
25
3.12
25
6d
6e
4-CH3
4-CH3
H
>50
50
4-CH3
e
e
25
50
50
25
25
50
8a
8b
>50
25
4-CH3
4-OCH3
4-Cl
e
25
>50
12.5
3.12
3.12
25
8c
8d
e
12.5
3.12
1.56
12.5
1.56
6.25
6.25
6.25
1.56
e
Ciprofloxacin
e
4.2. Antifungal screening
5. Conclusion
Titled compounds were screened for their antifungal activ-
ity against Candida albicans, Aspergillus fumigatus, Aspergil-
lus flavus, and Aspergillus niger (recultured) in DMSO by
serial plate dilution method [28].
We have synthesized novel fused quinazolinones (4), (6)
and (8) to evaluate them on antimicrobial screen.
From the antimicrobial data it seems that triazolo[4,3-a]-
quinazolin-7-ones (4) seem to be more potent than tetrazino
[4,3-a]-quinazolin-8-ones (6) and indolo[2,3-c][1,2,4]-tria-
zino[4,3-a]-quinazoline-8-ones (8).
The data also revealed that presence of triazole moiety at
N-1 and C-2 exerted more influence on the antimicrobial pro-
file than triazine and tetrazine moieties.
Therefore, it can be inferred that presence of triazole nu-
cleus at N-1 and C-2 of quinazolinone ring works better for
antimicrobial activity of this series of compounds than others.
The importance of such work lies in the possibility that the
new compounds might be a more efficacious drug against bac-
teria and fungi for which a thorough investigation regarding
the structure activity relationship, toxicity and its biological
effects is essential, which could be helpful in designing
more potent antimicrobial agents for therapeutic use.
The screening data of antifungal activity of these series of
compounds shows moderate to good antifungal activity.
It is of interest that compounds 4i, 4l and 8d showed pro-
nounced antifungal activity against A. niger with MIC
1.56 mg/mL, while these compounds showed good activity
against A. fumigatus and A. flavus with MIC 3.12 mg/mL and
6.25 mg/mL which is quite comparable with standard drug Flu-
conazole (MIC ¼ 1.56 mg/mL, 3.12 mg/mL and 6.25 mg/mL),
tested under similar conditions. High activity was demon-
strated by 4l against A. fumigatus with MIC 3.12 mg/mL,
which is even more than standard drug Fluconazole for same
pathogenic fungus. Compounds particularly 4i and 4l emerged
as very potent compounds of this investigation.
It is interesting to note that a minor alteration in the molec-
ular configuration of investigated compounds may have a pro-
nounced effect on antimicrobial screening, e.g. compounds
4a, 6a and 8a having no substituent in phenyl ring are less
active, while compounds having p-chloro, p-methoxy and
o-chloro substituent in benzene ring are more active than all
other compounds. The compounds 4i and 4l have a fused
1,2,4-triazole ring at N-1 and C-2 of parent compound qui-
nazolinone, and were found more potent than other com-
pounds of this investigation, which having triazine and
tetrazine ring fused at N-1 and C-2 of parent quinazolinone
compound.
6. Experimental
6.1. General
Procedure for one typical case for each step has been
described. Melting points were taken in open capillaries and
are uncorrected. UV spectra were recorded on UVeVisible
spectrophotometer (Shimadzu 160). IR spectra were recorded
in KBr on a Shimadzu 8201 PC Spectrophotometer (nmax
in
cmꢀ1), 1H NMR and 13C NMR spectra in DMSO-d6 on

1192
S.K. Pandey et al. / European Journal of Medicinal Chemistry 44 (2009) 1188e1197
a Bruker DRX-300 (300 MHz) spectrometer using TMS as an
internal reference (chemical shifts in d, ppm). Elemental anal-
yses were performed on an elemental Vario EL III Carlo Erba
1108 CHN analyser. Elemental (C, H, N) analysis indicated
that calculated and observed values were within the acceptable
limits (ꢂ0.4%). The purity of compounds was checked by thin
layer chromatography on silica gel plate using ether and ethyl
acetate as a solvent system. Iodine chamber was used as a
developing chamber. All the reagents used were AR grade.
6.3. General procedure for the preparation of 3-
(substituted-phenyl)-2-mercaptomethyl-quinazolin-4-
ones (2)
A mixture of 3-(substituted-phenyl)-2-mercapto-quinazo-
lin-4-ones (1) (0.1 mol) and anhydrous sodium acetate
(0.15 mol) dissolved in dioxane (100 ml) was treated with
methyl iodide (0.1 mol) gradually with constant stirring for
4 h. The solvent was removed and the residue was poured
into ice-cold water. The compound thus precipitated was fil-
tered, washed, dried, and recrystallized from aq. ethanol.
6.2. General procedure for the preparation of 3-
(substituted-phenyl)-2-mercapto-quinazolin-4-ones (1)
6.3.1. 3-(4-Methylphenyl)-2-mercaptomethyl-quinazolin-4-
one (2a)
An equimolar mixture of anthranilic acid (0.15 mol)
and substituted-phenylisothiocynate (0.15 mol) in acetone
(150 ml) was refluxed for 6 h. The solvent was removed and
residue was poured into water. The compound thus precipi-
tated was filtered, washed, dried, and recrystallized from aq.
ethanol.
Yield 71%; mp 167e169 ꢁC; IR (KBr) cmꢀ1: 1670 (C]O),
1
1625 (C]N), 1590, 1550, 1480 (C]C) 1220 (CeSeC); H
NMR (DMSO-d6): d 7.2e7.5 (m, 4H, pheH), d 7.9 (dd, 2H,
J ¼ 8.3, pheH), d 8.2 (dd, 2H, J ¼ 8.4, pheH), 2.2 (s, 3H,
eCH3), 2.5 (s, 3H, eSCH3). Anal. Calcd. for C16H14N2OS:
C, 68.06; H, 5.00; N, 9.92. Found: C, 68.21; H, 5.12; N, 9.84.
6.3.2. 3-(Phenyl)-2-mercaptomethyl-quinazolin-4-one (2b)
Yield 69%; mp 147e149 ꢁC; IR (KBr) cmꢀ1: 1656 (C]O),
6.2.1. 3-(4-Methyl phenyl)-2-mercapto-quinazolin-4-one
(1a)
1
1629 (C]N), 1563, 1545, 1478 (C]C), 1217 (CeSeC); H
Yield 68%; mp 173e175 ꢁC; IR (KBr) cmꢀ1: 2650 (eSH),
1
1675 (C]O), 1620 (C]N), 1560, 1525, 1440 (C]C); H
NMR (DMSO-d6): d 7.4e8.2 (m, 9H, pheH), 2.4 (s, 3H, e
SCH3). Anal. Calcd. for C15H12N2OS: C, 67.14; H, 4.51; N,
10.44. Found: C, 67.01; H, 4.32; N, 10.34.
NMR (DMSO-d6): d 7.2e7.6 (m, 4H, pheH), d 7.9 (dd, 2H,
J ¼ 8.4, pheH), d 8.2 (dd, 2H, J ¼ 8.5, pheH), 2.4 (s, 3H,
eCH3), 3.3 (s, 1H, eSH). Anal. Calcd. for C15H12N2OS: C,
67.14; H, 4.51; N, 10.44. Found: C, 67.01; H, 4.40; N, 10.34.
6.3.3. 3-(4-Methoxyphenyl)-2-mercaptomethyl-quinazolin-
4-one (2c)
Yield 73%; mp 168e171 ꢁC; IR (KBr) cmꢀ1: 1679 (C]O),
1
1618 (C]N), 1578, 1549, 1470 (C]C), 1221 (CeSeC); H
6.2.2. 3-(Phenyl)-2-mercapto-quinazolin-4-one (1b)
Yield 72%; mp 183e185 ꢁC; IR (KBr) cmꢀ1: 2650 (eSH),
NMR (DMSO-d6): d 7.2e7.8 (m, 4H, pheH), d 8.2 (dd, 2H,
J ¼ 8.5, pheH), d 8.3 (dd, 2H, J ¼ 8.6, pheH), 3.8 (s, 3H,
eOCH3), 2.4 (s, 3H, eSCH3). Anal. Calcd. for
C16H14N2O2S: C, 64.42; H, 4.73; N, 9.39. Found: C, 64.21;
H, 4.62; N, 9.44.
1
1680 (C]O), 1625 (C]N), 1556, 1518, 1432 (C]C); H
NMR (DMSO-d6): d 7.3e8.4 (m, 9H, pheH), 2.9 (s, 1H, e
SH). Anal. Calcd. for C14H10N2OS: C, 66.12; H, 3.96; N,
11.02. Found: C, 66.01; H, 3.82; N, 11.24.
6.3.4. 3-(4-Chlorophenyl)-2-mercaptomethyl-quinazolin-4-
one (2d)
6.2.3. 3-(4-Meyhoxyphenyl)-2-mercapto-quinazolin-4-one
(1c)
Yield 76%; mp above 200 ꢁC; IR (KBr) cmꢀ1: 1659
(C]O), 1623 (C]N), 1564, 1546, 1476 (C]C), 1218 (Ce
SeC); 1H NMR (DMSO-d6): d 7.4e7.9 (m, 4H, pheH),
d 8.3 (dd, 2H, J ¼ 8.6, pheH), d 8.6 (dd, 2H, J ¼ 8.7, phe
H), 2.6 (s, 3H, eSCH3). Anal. Calcd. for C15H11N2OSCl: C,
59.50; H, 3.66; N, 9.25. Found: C, 59.31; H, 3.42; N, 9.34.
Yield 70%; mp 192e193 ꢁC; IR (KBr) cmꢀ1: 2645 (eSH),
1672 (C]O),1630 (C]N), 1542, 1526, 1441 (C]C); 1H
NMR (DMSO-d6): d 7.3e7.8 (m, 4H, pheH), d 8.1 (dd, 2H,
J ¼ 8.5, pheH), d 8.4 (dd, 2H, J ¼ 8.7, pheH), 3.8 (s, 3H,
eOCH3), 3.1 (s, 1H, eSH). Anal. Calcd. for C15H12N2O2S:
C, 63.36; H, 4.25; N, 9.85. Found: C, 63.01; H, 4.52; N, 9.62.
6.4. General procedure for the preparation of 3-
6.2.4.
(1d)
3-(4-Chlorophenyl)-2-mercapto-quinazolin-4-one
(substituted-phenyl)-2-hydrazino-quinazolin-4-ones (3)
Yield 74%; mp 189e191 ꢁC; IR (KBr) cmꢀ1: 2650 (eSH),
A mixture of 3-(substituted-phenyl)-2-mercaptomethyl-qui-
nazolin-4-ones (2) (0.05 mol) and hydrazine hydrate (0.1 mol)
in dioxane (50 ml) was refluxed for 6 h. The solvent was re-
moved and residue was poured into ice-cold water. The com-
pound thus precipitated was filtered, washed, dried, and
recrystallized from aq. ethanol.
1
1680 (C]O), 1624 (C]N), 1543, 1525, 1412 (C]C); H
NMR (DMSO-d6): d 7.4e7.8 (m, 4H, pheH), d 8.3 (dd, 2H,
J ¼ 8.4, pheH), d 8.5 (dd, 2H, J ¼ 8.6, pheH), 3.0 (s, 1H,
eSH). Anal. Calcd. for C14H9ClN2OS: C, 58.23; H, 3.14; N,
9.70. Found: C, 58.41; H, 3.22; N, 9.64.

S.K. Pandey et al. / European Journal of Medicinal Chemistry 44 (2009) 1188e1197
1193
6.4.1. 3-(4-Methylphenyl)-2-hydrazino-quinazolin-4-one (3a)
Yield 68%; mp 114e116 ꢁC; IR (KBr) cmꢀ1: 3425 (eNH),
4.14; N, 16.56. Found: C, 74.41; H, 4.22; N, 16.35; UV
(DMF): 289 nm, 223 nm, 206 nm.
1
1660 (C]O), 1622 (C]N), 1552, 1496, 1415 (C]C); H
NMR (DMSO-d6): d 7.2e7.7 (m, 4H, pheH), d 7.8 (dd, 2H,
J ¼ 8.4, pheH), d 8.1 (dd, 2H, J ¼ 8.5, pheH), 2.3 (s, 3H,
eCH3), 4.8 (br s, 2H, eNH2), 8.3 (br s, 1H, NH). Anal. Calcd.
for C15H14N4O: C, 67.65; H, 5.30; N, 21.04. Found: C, 67.41;
H, 5.42; N, 21.14.
6.5.2. 5-(2-Methylphenyl)-6-(phenyl)-[1,2,4]-triazolo[4,3-
a]-quinazolin-7-one (4b)
Yield 73%; mp 176e178 ꢁC; IR (KBr) cmꢀ1: 1660 (C]O),
1
1618 (C]N), 1531, 1470, 1415 (C]C), 1122 (CeNeC); H
NMR (DMSO-d6): d 7.1e8.2 (m, 13H, pheH), 2.3 (s, 3H, e
CH3). Anal. Calcd. for C22H16N4O: C, 75.00; H, 4.54; N,
15.90. Found: C, 75.31; H, 4.32; N, 15.75.
6.4.2. 3-(Phenyl)-2-hydrazino-quinazolin-4-one (3b)
Yield 73%; mp 111e113 ꢁC; IR (KBr) cmꢀ1: 3430 (eNH),
1
1656 (C]O), 1631 (C]N), 1536, 1445, 1418 (C]C); H
6.5.3. 5-(2-Chlorophenyl)-6-(phenyl)-[1,2,4]-triazolo[4,3-
a]-quinazolin-7-one (4c)
NMR (DMSO-d6): d 7.1e8.3 (m, 9H, ph eH), 4.5 (br s, 2H,
eNH2), 8.2 (br s, 1H, eNH); 13C NMR (DMSO): d 170.2,
160.1, 141.2, 140.5, 131.3, 130.9, 130.2, 129.9, 129.1,
127.6, 127.1, 124.2. Anal. Calcd. for C14H12N4O: C, 66.65;
H, 4.79; N, 22.21. Found: C, 66.43; H, 4.62; N, 22.34.
Yield 70%; mp 169e171 ꢁC; IR (KBr) cmꢀ1: 1660 (C]O),
1
1610 (C]N), 1554, 1465, 1405 (C]C), 1130 (CeNeC); H
NMR (DMSO-d6): d 7.3e8.4 (m, 13H, pheH). Anal. Calcd.
for C21H13N4OCl: C, 67.65; H, 3.48; N, 15.03. Found: C,
67.41; H, 3.32; N, 15.25.
6.4.3. 3-(4-Methoxyphenyl)-2-hydrazino-quinazolin-4-one(3c)
Yield 69%; mp 149e151 ꢁC; IR (KBr) cmꢀ1: 3433 (eNH),
1
1650 (C]O), 1618 (C]N), 1418, 1450, 1542 (C]C); H
6.5.4. 5-(Phenyl)-6-(4-methylphenyl)-[1,2,4]-triazolo[4,3-
a]-quinazolin-7-one (4d)
NMR (DMSO-d6): d 7.2e7.9 (m, 4H, pheH), d 8.2 (dd, 2H,
J ¼ 8.4, pheH), d 8.4 (dd, 2H, J ¼ 8.6, pheH), 3.7 (s, 3H,
eOCH3), 4.6 (br s, 2H, eNH2), 8.4 (br s, 1H, eNH). Anal.
Calcd. for C15H14N4O2: C, 63.82; H, 5.00; N, 19.85. Found:
C, 63.42; H, 5.12; N, 19.74.
Yield 72%; mp 169e171 ꢁC; IR (KBr) cmꢀ1: 1665 (C]O),
1
1620 (C]N), 1540, 1480, 1400 (C]C), 1110 (CeNeC); H
NMR (DMSO-d6): d 7.3e7.7 (m, 9H, pheH), d 7.9 (dd, 2H,
J ¼ 8.5, pheH), d 8.1 (dd, 2H, J ¼ 8.5, pheH), 2.3 (s, 3H,
eCH3). Anal. Calcd. for C22H16N4O: C, 75.00; H, 4.54; N,
15.90. Found: C, 75.31; H, 4.32; N, 15.75.
6.4.4. 3-(4-Chlorophenyl)-2-hydrazino-quinazolin-4-one (3d)
Yield 67%; mp 171e173 ꢁC; IR (KBr) cmꢀ1: 3429 (eNH),
1
1651 (C]O), 1615 (C]N), 1541, 1476, 1412 (C]C); H
6.5.5. 5-(2-Methylphenyl)-6-(4-methylphenyl)-
[1,2,4]-triazolo[4,3-a]-quinazolin-7-one (4e)
NMR (DMSO-d6): d 7.5e7.9 (m, 4H, pheH), d 8.3 (dd, 2H,
J ¼ 8.5, pheH), d 8.6 (dd, 2H, J ¼ 8.7, pheH), 4.7 (br s,
2H, eNH2), 8.2 (br s, 1H, eNH). Anal. Calcd. for
C14H11N4OCl: C, 58.65; H, 3.87; N, 12.37. Found: C, 58.49;
H, 3.57; N, 12.12.
Yield 62%; mp 177e178 ꢁC; IR (KBr) cmꢀ1: 1666 (C]O),
1
1630 (C]N), 1525, 1478, 1410 (C]C), 1129 (CeNeC); H
NMR (DMSO-d6): d 7.2e7.8 (m, 8H, pheH), d 7.9 (dd, 2H,
J ¼ 8.3, pheH), d 8.0 (dd, 2H, J ¼ 8.4, pheH), 2.1 (s, 6H,
2 ꢃ eCH3). Anal. Calcd. for C23H18N4O: C, 79.31; H, 5.17;
N, 16.09. Found: C, 79.11; H, 5.32; N, 16.25.
6.5. General procedure for the preparation of
5,6-(disubstituted-phenyl)-[1,2,4]-triazolo[4,3-a]-
quinazolin-7-ones (4)
6.5.6. 5-(2-Chlorophenyl)-6-(4-methylphenyl)-[1,2,4]-triazolo
[4,3-a]-quinazolin-7-one (4f)
A mixture of 3-(substituted-phenyl)-2-hydrazino-quinazo-
lin-4-one (3) (0.01 mol), substituted-benzoic acid (0.01 mol)
and dicyclohexylcarbodiimide (DCC, 0.01 mol) in dichloro-
methane (20 ml) was stirred for 3 h. After this solvent was re-
moved and the residue was poured into ice-cold water. The
solid mass thus obtained was filtered, washed with water, dried
and recrystallized from aq. ethanol.
Yield 64%; mp 181e183 ꢁC; IR (KBr) cmꢀ1: 1670 (C]O),
1
1610 (C]N), 1535, 1470, 1419 (C]C), 1135 (CeNeC); H
NMR (DMSO-d6): d 7.3e7.9 (m, 8H, pheH), d 8.0 (dd, 2H,
J ¼ 8.5, pheH), d 8.1 (dd, 2H, J ¼ 8.6, pheH), 2.2 (s, 3H,
eCH3). Anal. Calcd. for C22H15N4OCl: C, 68.30; H, 3.88;
N, 14.48. Found: C, 68.10; H, 3.66; N, 14.29.
6.5.1. 5,6-(Diphenyl)-[1,2,4]-triazolo[4,3-a]-quinazolin-7-
one (4a)
6.5.7. 5-(Phenyl)-6-(4-methoxylphenyl)-[1,2,4]-triazolo[4,3-
a]-quinazolin-7-one (4g)
Yield 74%; mp 187e189 ꢁC; IR (KBr) cmꢀ1: 1662 (C]O),
Yield 70%; mp 180e182 ꢁC; IR (KBr) cmꢀ1: 1660 (C]O),
1
1
1635 (C]N), 1540, 1488, 1429 (C]C), 1135 (CeNeC); H
1622 (C]N), 1542, 1486, 1400 (C]C), 1112 (CeNeC); H
NMR (DMSO-d6): d 7.2e8.4 (m, 14H, pheH), 13C NMR
(DMSO): d 170.2, 151.3, 149.2, 140.1, 137.0, 135.1, 133.1,
132.2, 130.8, 130.0, 129.8, 129.3, 129.0, 128.6, 128.1,
125.2, 122.2. Anal. Calcd. for C21H14N4O: C, 74.55; H,
NMR (DMSO-d6): d 7.2e7.9 (m, 9H, pheH), d 8.3 (dd, 2H,
J ¼ 8.5, pheH), d 8.4 (dd, 2H, J ¼ 8.6, pheH), 3.7 (s, 3H,
eOCH3). Anal. Calcd. for C22H16N4O2: C, 71.73; H, 4.34;
N, 15.21. Found: C, 71.50; H, 4.20; N, 15.15.

1194
S.K. Pandey et al. / European Journal of Medicinal Chemistry 44 (2009) 1188e1197
6.5.8.
5-(2-Methylphenyl)-6-(4-methoxylphenyl)-[1,2,4]-
6.6.1.
3-(Phenyl)-2-[4-(phenyl)-thiosemicarbazone]-
triazolo[4,3-a]-quinazolin-7-one (4h)
Yield 69%; mp 185e187 ꢁC; IR (KBr) cmꢀ1: 1670 (C]O),
quinazolin-4-one (5a)
Yield 71%; mp 161e163 ꢁC; IR (KBr) cmꢀ1: 3325 (eNe
H), 1680 (C]O), 1629 (C]N), 1561, 1439, 1427 (C]C),
1235 (C]S), 1119 (CeNeC); 1H NMR (DMSO-d6):
d 7.1e8.3 (m, 14H, pheH), 8.5e8.6 (br s, 3H, eNH). Anal.
Calcd. for C21H17N5OS: C, 65.11; H, 4.39; N, 18.08. Found:
C, 65.26; H, 4.50; N, 18.24.
1
1640 (C]N), 1539, 1460, 1420 (C]C), 1126 (CeNeC); H
NMR (DMSO-d6): d 7.3e7.9 (m, 8H, pheH), d 8.2 (dd, 2H,
J ¼ 8.4, pheH), d 8.3 (dd, 2H, J ¼ 8.5, pheH) 3.8 (s, 3H, e
OCH3), 2.2 (s, 3H, eCH3). Anal. Calcd. for C23H18N4O2: C,
72.25; H, 4.71; N, 14.65. Found: C, 72.30; H, 4.50; N, 14.45.
6.6.2. 3-(Phenyl)-2-[4-(4-methylphenyl)-thiosemicarbazone]-
quinazolin-4-one (5b)
6.5.9. 5-(2-Chlorolphenyl)-6-(4-methoxylphenyl)-[1,2,4]-
triazolo[4,3-a]-quinazolin-7-one (4i)
Yield 70%; mp 169e171 ꢁC; IR (KBr) cmꢀ1: 3331 (eNe
H), 1665 (C]O), 1618 (C]N), 1545, 1430, 1415 (C]C),
Yield 73%; mp 188e190 ꢁC; IR (KBr) cmꢀ1: 1664 (C]O),
1
1629 (C]N), 1530, 1440, 1415 (C]C), 1115 (CeNeC); H
1
1221 (C]S),1126 (CeNeC); H NMR (DMSO-d6): d 7.2e
NMR (DMSO-d6): d 7.3e7.9 (m, 8H, pheH), d 8.3 (dd, 2H,
J ¼ 8.4, pheH), d 8.4 (dd, 2H, J ¼ 8.5, pheH) 3.7 (s, 3H, e
OCH3). Anal. Calcd. for C21H15N4O2Cl: C, 65.59; H, 3.72;
N, 13.91. Found: C, 65.40; H, 3.50; N, 13.70.
7.7 (m, 9H, pheH), d 7.8 (dd, 2H, J ¼ 8.4, pheH), d 8.0
(dd, 2H, J ¼ 8.4, pheH), 2.3 (s, 3H, eCH3), 8.5e8.7 (br s,
3H, eNH). Anal. Calcd. for C22H19N5OS: C, 65.83; H,
4.77; N, 17.44. Found: C, 65.66; H, 4.50; N, 17.20.
6.5.10. 5-(Phenyl)-6-(4-chlorophenyl)-[1,2,4]-triazolo[4,3-
a]-quinazolin-7-one (4j)
6.6.3. 3-(Phenyl)-2-[4-(4-methoxyphenyl)-
thiosemicarbazone]-quinazolin-4-one (5c)
Yield 73%; mp 171e173 ꢁC; IR (KBr) cmꢀ1: 1665 (C]O),
Yield 74%; mp 180e181 ꢁC; IR (KBr) cmꢀ1: 3339 (eNe
H), 1650 (C]O), 1640 (C]N), 1570, 1441, 1410 (C]C),
1231 (C]S), 1134 (CeNeC); 1H NMR (DMSO-d6):
d 7.2e7.8 (m, 9H, pheH), d 8.2 (dd, 2H, J ¼ 8.3, pheH),
d 8.3 (dd, 2H, J ¼ 8.5, pheH), 3.8 (s, 3H, eOCH3), 8.5e8.6
(br s, 3H, eNH). Anal. Calcd. for C22H19N5O2S: C, 65.31;
H, 4.56; N, 17.45. Found: C, 65.50; H, 4.36; N, 17.24.
1
1620 (C]N), 1545, 1425, 1410 (C]C), 1116 (CeNeC); H
NMR (DMSO-d6): d 7.5e7.9 (m, 9H, pheH), d 8.4 (dd, 2H,
J ¼ 8.5, pheH), d 8.6 (dd, 2H, J ¼ 8.7, pheH). Anal. Calcd.
for C21H13N4OCl: C, 67.74; H, 3.49; N, 15.05. Found: C,
67.40; H, 3.26; N, 15.34.
6.5.11.
5-(2-Methylphenyl)-6-(4-chlorophenyl)-[1,2,4]-
6.6.4. 3-(4-Methylphenyl)-2-
triazolo[4,3-a]-quinazolin-7-one (4k)
Yield 70%; mp 175e177 ꢁC; IR (KBr) cmꢀ1: 1660 (C]O),
[4-(phenyl)-thiosemicarbazone]-quinazolin-4-one (5d)
Yield 71%; mp 166e167 ꢁC; IR (KBr) cmꢀ1: 3320 (eNe
H), 1675 (C]O), 1630 (C]N), 1560 1470, 1420 (C]C),
1
1634 (C]N), 1560, 1440, 1416 (C]C), 1130 (CeNeC); H
NMR (DMSO-d6): d 7.5e7.9 (m, 8H, pheH), d 8.4 (dd, 2H,
J ¼ 8.6, pheH), d 8.5 (dd, 2H, J ¼ 8.7, pheH), 2.3 (s, 3H,
eCH3). Anal. Calcd. for C22H15N4OCl: C, 68.30; H, 3.88;
N, 14.48. Found: C, 68.15; H, 3.67; N, 14.36.
1
1230 (C]S),1120 (CeNeC); H NMR (DMSO-d6): d 7.2e
7.6 (m, 9H, pheH), d 7.8 (dd, 2H, J ¼ 8.4, pheH), d 8.1
(dd, 2H, J ¼ 8.5, pheH), 2.2 (s, 3H, eCH3), 8.5e8.7 (br s,
3H, eNH). Anal. Calcd. for C22H19N5OS: C, 65.83; H,
4.77; N, 17.44. Found: C, 65.60; H, 4.51; N, 17.29.
6.5.12.
5-(2-Chlorophenyl)-6-(4-chlorophenyl)-[1,2,4]-
triazolo[4,3-a]-quinazolin-7-one (4l)
6.6.5. 3-(4-Methylphenyl)-2-[4-(4-
Yield 75%; mp 161e163 ꢁC; IR (KBr) cmꢀ1: 1670 (C]O),
methylphenyl)-thiosemicarbazone]-quinazolin-4-one (5e)
Yield 71%; mp 185e187 ꢁC; IR (KBr) cmꢀ1: 3331 (eNe
H), 1656 (C]O), 1635 (C]N), 1535, 1430,1421 (C]C),
1
1629 (C]N), 1546, 1419, 1407 (C]C), 1119 (CeNeC); H
NMR (DMSO-d6): d 7.5e8.0 (m, 8H, pheH), d 8.3 (dd, 2H,
J ¼ 8.5, pheH), d 8.5 (dd, 2H, J ¼ 8.6, pheH). Anal. Calcd.
for C22H12N4OCl2: C, 61.91; H, 2.94; N, 13.75. Found: C,
61.80; H, 2.70; N, 13.40.
1
1235 (C]S),1136 (CeNeC); H NMR (DMSO-d6): d 7.2e
7.6 (m, 4H, pheH), d 7.8e7.9 (dd, 4H, J ¼ 8.3e8.4, pheH),
d 8.0e8.1 (dd, 4H, J ¼ 8.4e8.6, pheH), 2.3 (s, 6H, 2 ꢃ e
CH3), 8.5e8.6 (br s, 3H, eNH). Anal. Calcd. for
C23H21N5OS: C, 66.50; H, 5.06; N, 16.86. Found: C, 66.71;
H, 5.30; N, 16.53.
6.6. General procedure for the preparation of 3-
(substituted-phenyl)-2-[4-substituted-phenyl-
thiosemicarbazone]-quinazolin-4-ones (5)
6.7. General procedure for the preparation
of 5,7-(disubstituted-phenyl)-6-thioxo-
[1,2,4,5]tetrazino[4,3-a]-quinazolin-8-ones (6)
A mixture of 3-(substituted-phenyl)-2-hydrazino-quinazo-
lin-4-one (3) (0.01 mol) and substituted-phenylisothiocyanate
(0.01 mol) in methanol (25 ml) was refluxed for 4 h. The sol-
vent was removed and water was added to it. The precipitated
solid mass was filtered, washed with water, dried and recrys-
tallized from aq. ethanol.
A mixture of 3-(substituted-phenyl)-2-[4-(substituted-phe-
nyl)-thiosemicarbazone]-quinazolin-4-ones (5) (0.01 mol)
and bromine (0.015 mol) in CCl4 (10 ml) was stirred at

S.K. Pandey et al. / European Journal of Medicinal Chemistry 44 (2009) 1188e1197
1195
room temperature for 30 min. The mixture was cooled, when
fine crystals separated out which were filtered and recrystal-
lized from aq. ethanol.
6.8. General procedure for the preparation of
3-(substituted-phenyl)-2-(isatinhydrazone-30-yl)-
quinazolin-4-ones (7)
A mixture of 3-(substituted-phenyl)-2-hydrazino-quinazo-
lin-4-one (3) (0.01 mol) and isatin (0.01 mol) in methanol
(20 ml) was refluxed for 2 h. The solvent was removed and
the residue was poured into water. The solid mass thus
obtained was filtered washed with water, dried and recrystal-
lized from aq. ethanol.
6.7.1. 5,7-(Diphenyl)-6-thioxo-[1,2,4,5]-tetrazino[4,3-a]-
quinazolin-8-one (6a)
Yield 71%; mp 180e181 ꢁC; IR (KBr) cmꢀ1: 3300 (eNe
H), 1660 (C]O), 1616 (C]N), 1556, 1436, 1415 (C]C),
1
1220 (C]S),1136 (CeNeC); H NMR (DMSO-d6): d 7.0e
8.3 (m, 14H, pheH), 8.0 (s, 1H, eNeH). Anal. Calcd. for
C21H15N5OS: C, 65.45; H, 3.89; N, 18.18. Found: C, 65.60;
H, 3.60; N, 18.33. UV (DMF): 293 nm, 273 nm, 224 nm,
206 nm, 202 nm.
6.8.1. 3-(Phenyl)-2-(isatinhydrazone-30-yl)-quinazolin-4-
ones (7a)
Yield 69%; mp 174e176 ꢁC; IR (KBr) cmꢀ1: 3190 (eNe
H), 1660 (C]O, five membered ring), 1660 (C]O, six mem-
bered ring), 1630 (exo C]N), 1610 (endo C]N), 1510, 1444,
1400 (C]C); 1H NMR (DMSO-d6): d 6.9e8.0 (m, 13H, phe
H), 8.2 (br s, 1H, eNeH), 8.8 (br s, 1H, eNeH). Anal. Calcd.
for C22H15N5O2: C, 69.29; H, 3.93; N, 18.37. Found: C, 69.50;
H, 3.32; N, 18.51.
6.7.2.
5-(4-Methylphenyl)-7-(phenyl)-6-thioxo-[1,2,4,5]-
tetrazino[4,3-a]-quinazolin-8-ones (6b)
Yield 73%; mp 172e174 ꢁC; IR (KBr) cmꢀ1: 3305 (eNe
H), 1672 (C]O), 1630 (C]N), 1570, 1445, 1400 (C]C),
1235 (C]S), 1140 (CeNeC); 1H NMR (DMSO-d6):
d 7.2e7.7 (m, 9H, pheH), d 7.9 (dd, 2H, J ¼ 8.5, pheH),
d 8.1 (dd, 2H, J ¼ 8.6, pheH), 2.3 (s, 3H, eCH3), 7.8 (s,
1H, eNeH), 13C NMR (DMSO): 190.1, 170.3, 151.1,
148.2, 143.1, 142.1, 141.9, 133.3, 130.1, 129.4, 129.1,
128.1, 126.2, 125.3, 124.1, 121.9, 121.4, 121.0. Anal. Calcd.
for C21H17N5OS: C, 66.16; H, 4.26; N, 17.54. Found: C,
66.29; H, 4.40; N, 17.40.
6.8.2. 3-(4-Methylphenyl)-2-(isatinhydrazone-30-yl)-
quinazolin-4-ones (7b)
Yield 71%; mp 181e183 ꢁC; IR (KBr) cmꢀ1: 3200 (eNe
H), 1675 (C]O, five membered ring), 1655 (C]O, six mem-
bered ring), 1620 (exo C]N), 1600 (endo C]N), 1530, 1460,
6.7.3. 5-(4-Methoxyphenyl)-7-(phenyl)-6-thioxo-[1,2,4,5]-
tetrazino[4,3-a]-quinazolin-8-ones (6c)
1
1420 (C]C); H NMR (DMSO-d6): d 7.2e7.8 (m, 8H, phe
H), d 7.9 (dd, 2H, J ¼ 8.3, pheH), d 8.2 (dd, 2H, J ¼ 8.4,
pheH), 2.2 (s, 3H, eCH3) 8.3 (br s, 1H, eNeH), 8.9 (br s,
1H, eNeH). Anal. Calcd. for C23H17N5O2: C, 69.87; H,
4.30; N, 17.72. Found: C, 69.60; H, 4.49; N, 17.80.
Yield 71%; mp 179e181 ꢁC; IR (KBr) cmꢀ1: 3309 (eNe
H), 1650 (C]O), 1615 (C]N), 1565, 1450, 1420 (C]C),
1
1229 (C]S),1131 (CeNeC); H NMR (DMSO-d6): d 7.2e
7.9 (m, 9H, pheH), d 8.2 (dd, 2H, J ¼ 8.3, pheH), d 8.4
(dd, 2H, J ¼ 8.6, pheH), 3.8 (s, 3H, eOCH3), 8.2 (s, 1H, e
NeH). Anal. Calcd. for C21H17N5O2S: C, 66.61; H, 4.10; N,
16.87. Found: C, 66.20; H, 4.22; N, 16.52.
6.8.3. 3-(4-Methoxyphenyl)-2-(isatinhydrazone-30-yl)-
quinazolin-4-ones (7c)
Yield 69%; mp 185e186 ꢁC; IR (KBr) cmꢀ1: 3200 (eNe
H), 1660 (C]O, five membered ring), 1650 (C]O, six mem-
bered ring), 1625 (exo C]N), 1616 (endo C]N), 1545, 1440,
6.7.4. 5-(Phenyl)-7-(4-methylphenyl)-6-thioxo-[1,2,4,5]-
tetrazino[4,3-a]-quinazolin-8-ones (6d)
Yield 70%; mp 188e189 ꢁC; IR (KBr) cmꢀ1: 3310 (eNe
H), 1632 (C]O), 1622 (C]N), 1575, 1459,1436 (C]C),
1220 (C]S), 1121 (CeNeC); 1H NMR (DMSO-d6):
d 7.3e7.7 (m, 9H, pheH), d 7.8 (dd, 2H, J ¼ 8.4, pheH),
d 8.0 (dd, 2H, J ¼ 8.5, pheH), 2.2 (s, 3H, eCH3), 8.3 (s,
1H, eNeH). Anal. Calcd. for C22H17N5OS: C, 66.16; H,
4.26; N, 17.54. Found: C, 66.29; H, 4.31; N, 17.80.
1
1415 (C]C); H NMR (DMSO-d6): d 7.2e8.0 (m, 8H, phe
H), d 8.3 (dd, 2H, J ¼ 8.5, pheH), d 8.4 (dd, 2H, J ¼ 8.6,
pheH), 3.8 (s, 3H, eOCH3) 8.3 (br s, 1H, eNeH), 8.7 (br
s, 1H, eNeH). Anal. Calcd. for C23H17N5O3: C, 67.15; H,
4.13; N, 17.03. Found: C, 67.35; H, 4.30; N, 17.10.
6.8.4. 3-(4-Chlorophenyl)-2-(isatinhydrazone-30-yl)-
quinazolin-4-ones (7d)
6.7.5. 5-(4-Methylphenyl)-7-(4-methylphenyl)-6-thioxo-[1,2,
4,5]-tetrazino-[4,3-a]-quinazolin-8-ones (6e)
Yield 69%; mp 171e173 ꢁC; IR (KBr) cmꢀ1: 3195 (eNe
H), 1673 (C]O, five membered ring), 1660 (C]O, six mem-
bered ring), 1622 (exo C]N), 1620 (endo C]N), 1540, 1432,
Yield 69%; mp 193e194 ꢁC; IR (KBr) cmꢀ1: 3301 (eNe
H), 1670 (C]O), 1610 (C]N), 1564, 1444, 1430 (C]C),
1
1235 (C]S),1131 (CeNeC); H NMR (DMSO-d6): d 7.2e
1
1419 (C]C); H NMR (DMSO-d6): d 7.5e7.9 (m, 8H, phe
7.7 (m, 4H, pheH), d 7.8e8.0 (dd, 4H, J ¼ 8.3e8.4, pheH),
d 8.0e8.2 (dd, 4H, J ¼ 8.4e8.6, pheH), 2.1 (s, 6H, 2 ꢃ e
CH3), 8.2 (s, 1H, eNeH). Anal. Calcd. for C23H19N5OS: C,
66.82; H, 4.60; N, 16.94. Found: C, 66.61; H, 4.40; N, 16.50.
H), d 8.3 (dd, 2H, J ¼ 8.4, pheH), d 8.5 (dd, 2H, J ¼ 8.6,
pheH), 8.2 (br s, 1H, eNeH), 8.8 (br s, 1H, eNeH). Anal.
Calcd. for C22H14N5O2Cl: C, 63.13; H, 3.36; N, 16.84. Found:
C, 63.25; H, 3.49; N, 16.98.

1196
S.K. Pandey et al. / European Journal of Medicinal Chemistry 44 (2009) 1188e1197
6.9. General procedure for the preparation of
3-(substituted-phenyl)-indolo-[2,3-c] [1,2,4]-
triazino[4,3-a]-quinazolin-8-ones (8)
nutrient agar plate in a laminar flow cabinet. Sterilized paper
disks (6.0 mm in diameter) were placed on the nutrient agar
plates. Five milligrams of each test compounds were dissolved
in 1 mL of dimethylsulfoxide (DMSO) separately to prepare
stock solution. From stock solution different concentrations
50 mg/mL, 25 mg/mL, 12.5 mg/mL, 6.25 mg/mL, 3.12 mg/mL
and 1.56 mg/mL of each compound were prepared. Thus,
proper amounts of the different concentrations of compounds
were pipetted on the blank disks, which were placed on the
plates. The plates were incubated at 37 ꢁC for 24 h. The min-
imum inhibitory concentrations (MICs), the lowest concentra-
tion (mg/mL) of the test compound that resulted no visible
growth on the plates were recorded in Table 1. DMSO was
used as a solvent control to ensure that solvent had no effect
on bacterial growth. Ciprofloxacin was designated in our ex-
periment as a control drug.
Slurry of 3-(substituted-phenyl)-2-(isatinhydrazone-30-yl)-
quinazolin-4-ones (7) (0.01 mol) in conc. H2SO4 (5.0 ml)
was made below 15 ꢁC and left for 2 h. Sufficient amount of
ice-cold water was added to the reaction mixture and the pre-
cipitated mass was filtered and neutralized with ammonia
solution. The compound thus obtained was filtered, dried,
and recrystallized from aq. ethanol.
6.9.1. 3-(Phenyl)-indolo[2,3-c][1,2,4]-triazino[4,3-a]-
quinazolin-8-ones (8a)
Yield 70%; mp 178e180 ꢁC; IR (KBr) cmꢀ1: 1655 (C]O),
1
1630 (C]N), 1510, 1440, 1400 (C]C); H NMR (DMSO-
d6):
d 6.8e8.0 (m, 13H, pheH). Anal. Calcd. for
C22H13N5O: C, 72.72; H, 3.58; N, 19.28. Found: C, 72.51;
H, 3.70; N, 19.52; UV (DMF): 301 nm, 253 nm, 240 nm,
220 nm, 212 nm.
6.11. Antifungal screening
Titled compounds were screened for their antifungal activ-
ity against C. albicans, A. fumigatus, A. flavus, and A. niger
(recultured) in DMSO by serial plate dilution method [28].
Test compound (5 mg) were dissolved in 1 mL of dimethyl-
sulfoxide (DMSO) and solution was diluted with water
(9 mL). Further progressive dilutions with melted Muller-Hin-
ton agar were performed to obtain required concentrations of
50 mg/mL, 25 mg/mL, 12.5 mg/mL, 6.25 mg/mL, 3.12 mg/mL
and 1.56 mg/mL. Petridishes were inoculated with 1.5 x 10ꢀ4
colony forming units (cfu) and incubated at 37 ꢁC for 26 h.
The minimum inhibitory concentrations (MICs) in mg/mL
were noted. To ensure that solvent had no effect on fungal
growth a control test was performed with test medium
6.9.2. 3-(4-Methylphenyl)-indolo[2,3-c][1,2,4]-triazino[4,3-
a]-quinazolin-8-ones (8b)
Yield 71%; mp 187e189 ꢁC; IR (KBr) cmꢀ1: 1660 (C]O),
1
1630 (C]N), 1510, 1440, 1400 (C]C); H NMR (DMSO-
d6): d 7.2e7.8 (m, 8H, pheH), d 7.9 (dd, 2H, J ¼ 8.2, phe
H), d 8.2 (dd, 2H, J ¼ 8.3, pheH), 2.3 (s, 3H, eCH3). Anal.
Calcd. for C23H15N5O: C, 73.20; H, 3.97; N, 18.56. Found:
C, 73.46; H, 3.80; N, 18.29.
6.9.3. 3-(4-Methoxyphenyl)-indolo[2,3-c][1,2,4]-triazino[4,
3-a]-quinazolin-8-ones (8c)
Yield 69%; mp above 200; IR (KBr) cmꢀ1: 1662 (C]O),
1
1625 (C]N), 1519, 1450, 1410 (C]C); H NMR (DMSO-
Table 2
Antifungal activities of compounds [4ae8d]
d6): d 7.3e8.0 (m, 8H, pheH), d 8.3 (dd, 2H, J ¼ 8.4, phe
H), d 8.4 (dd, 2H, J ¼ 8.5, pheH), 3.7 (s, 3H, eOCH3).
Anal. Calcd. for C23H15N5O2: C, 70.22; H, 3.81; N, 17.81.
Found: C, 70.03; H, 3.50; N, 17.43.
Compound no. R
R0
MICs (mg/mL)
C. albicans A. fumigatus A. flavus A. niger
4a
4b
H
H 25
2-CH3 50
>50
25
>50
25
25
H
>50
6.25
50
6.9.4. 3-(4-Chlorophenyl)indolo[2,3-c][1,2,4]-triazino[4,3-
a]-quinazolin-8-ones (8d)
4c
4d
H
4-CH3
2-Cl
H
25
>50
50
25
12.5
50
Yield 68%; mp 176e178 ꢁC; IR (KBr) cmꢀ1: 1665 (C]O),
4e
4-CH3 2-CH3 25
4-CH3 2-Cl 12.5
4-OCH3 6.25
4-OCH3 2-CH3 12.5
12.5
25
50
50
12.5
6.25
3.12
6.25
1.56
25
1
1630 (C]N), 1530, 1462, 1421 (C]C); H NMR (DMSO-
4f
4g
d6): d 7.5e8.0 (m, 8H, pheH), d 8.3 (dd, 2H, J ¼ 8.5, phe
H), d 8.4 (dd, 2H, J ¼ 8.5, pheH). Anal. Calcd. for
C22H12N5OCl: C, 66.41; H, 3.01; N, 17.61. Found: C, 66.30;
H, 3.19; N, 17.78.
H
12.5
6.25
3.12
6.25
12.5
3.12
>50
25
25
25
4h
4i
4-OCH3 2-Cl
6.25
12.5
3.12
12.5
3.12
6.25
>50
12.5
25
4j
4k
4-Cl
4-Cl
4-Cl
H
H
2-CH3 6.25
12.5
1.56
25
4l
6a
2-Cl
H
1.56
25
6.10. Antibacterial screening
6b
6c
H
4-CH3 >50
4-OCH3 6.25
25
H
4-CH3
12.5
12.5
50
3.12
25
Preliminary experiments were carried out to determine the
antibacterial activities of titled compounds (4ae4l, 6ae6e and
8ae8d) in vitro against (i) Gram-positive bacteria: S. pneumo-
niae, B. subtilis and (ii) Gram-negative bacteria: E. coli, P.
aeruginosa by disc diffusion method [27]. The bacterial strains
were subcultured in broth agar and incubated for 18 h at 37 ꢁC
and then freshly prepared bacterial cells were spread onto
6d
6e
H
4-CH3 4-CH3 25
25
12.5
12.5
25
25
8a
8b
H
e
e
e
e
e
>50
25
25
>50
50
4-CH3
4-OCH3
4-Cl
e
12.5
6.25
6.25
6.25
25
8c
8d
6.25
3.12
1.56
3.12
3.12
3.12
12.5
1.56
1.56
Fluconazole

S.K. Pandey et al. / European Journal of Medicinal Chemistry 44 (2009) 1188e1197
1197
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Med. Chem. 12 (2004) 641e647.
supplemented with DMSO at the same dilutions as used in the
experiment. Fluconazole was used as a standard drug. The
results are incorporated in Table 2.
[10] A.J. Schwartz, J. Mol. Cell. Cardiol. 19 (Suppl. 11) (1987) 49e51.
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Acknowledgement
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1984, p. 531.
The authors are thankful to the Head, Sophisticated Analyt-
ical Instrument Facility, Central Drug Research Institute,
Lucknow, for providing IR, H NMR, & 13C NMR spectral
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data. Authors are grateful to CSIR, New Delhi for financial as-
sistance. The authors are thankful to Prof. S. K. Sengupta &
Dr. O. P. Pandey, Department of Chemistry, D.D.U. Gorakhpur
University, Gorakhpur, respectively, for providing labora-
tory facilities for antifungal activities. Authors are also
thankful to Department of Biotechnology, D.D.U. Gorakhpur
University, Gorakhpur, for help in evaluating antibacterial
activities.
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