Design, synthesis and anticancer evaluation of structurally modified substituted aryl-quinazoline derivatives as anticancer agents

Article abstract of DOI:10.1080/00397911.2021.1941113

A new library of structurally modified aryl quinazoline-isoxazole (12a–j) derivatives have been designed, synthesized and characterized by ¹HNMR, ¹³CNMR and mass spectral data. Further these compounds were evaluated for anticancer applications against four human cancer cell lines including PC3, DU-145 (prostate cancer), A549 (lung cancer) and MCF-7 (breast cancer) by utilizing the MTT assay. The results were compared with etoposide which was used as positive control. Most of the compounds showed good to moderate anticancer activities against the four cancer cell lines. Among them, compounds 12a, 12b, 12c, 12d and 12j exhibited more potent activities. Further, molecular docking studies were carried out for all synthesized compounds against the cancer targets Selective Human Androgen Receptor (PDB ID: 3V49) and Abl-Tyrosine kinase (PDB ID: 1IEP). All the docked ligands have exhibited good binding interactions with the targeted protein.

Full text of DOI:10.1080/00397911.2021.1941113

Synthetic Communications
An International Journal for Rapid Communication of Synthetic Organic
Chemistry
ISSN: (Print) (Online) Journal homepage: https://www.tandfonline.com/loi/lsyc20
Design, synthesis and anticancer evaluation of
structurally modified substituted aryl-quinazoline
derivatives as anticancer agents
Tasqeeruddin Syed, Yahya I. Asiri, Shaheen Shaheen & Kiran Gangarapu
To cite this article: Tasqeeruddin Syed, Yahya I. Asiri, Shaheen Shaheen & Kiran Gangarapu
(
2021): Design, synthesis and anticancer evaluation of structurally modified substituted
aryl-quinazoline derivatives as anticancer agents, Synthetic Communications, DOI:
0.1080/00397911.2021.1941113
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https://doi.org/10.1080/00397911.2021.1941113
Design, synthesis and anticancer evaluation of structurally
modified substituted aryl-quinazoline derivatives as
anticancer agents
a
b
c
d
Tasqeeruddin Syed , Yahya I. Asiri , Shaheen Shaheen , and Kiran Gangarapu
a
Department of Pharmaceutical Chemistry, College of Pharmacy, King Khalid University, Abha, Saudi
b
Arabia; Department of Pharmacology, College of Pharmacy, King Khalid University, Abha, Saudi Arabia;
c
d
Anwarul Uloom College of Pharmacy, Mallepally, Hyderabad, India; School of Pharmacy, Anurag
Group of Institutions, Hyderabad, India
ABSTRACT
ARTICLE HISTORY
A new library of structurally modified aryl quinazoline-isoxazole
Received 8 March 2021
(
12a–j) derivatives have been designed, synthesized and character-
1 13
ized by HNMR, CNMR and mass spectral data. Further these com-
pounds were evaluated for anticancer applications against four
human cancer cell lines including PC3, DU-145 (prostate cancer),
A549 (lung cancer) and MCF-7 (breast cancer) by utilizing the MTT
assay. The results were compared with etoposide which was used as
positive control. Most of the compounds showed good to moderate
anticancer activities against the four cancer cell lines. Among them,
compounds 12a, 12b, 12c, 12d and 12j exhibited more potent
activities. Further, molecular docking studies were carried out for all
synthesized compounds against the cancer targets Selective Human
Androgen Receptor (PDB ID: 3V49) and Abl-Tyrosine kinase (PDB ID:
KEYWORDS
Erlotinib; isoxazole and
anticancer; luminespib;
quinazoline
1
IEP). All the docked ligands have exhibited good binding interac-
tions with the targeted protein.
GRAPHICAL ABSTRACT
Introduction
Generally, nitrogen atoms contained heterocyclic molecules such as quinazolines and
their derivatives were more privileged structural scaffolds and which were widely
applied in medicinal chemistry. These derivatives were possessed a broad spectrum of
CONTACT Tasqeeruddin Syed
tasqeeruddinchem1@gmail.com
Department of Pharmaceutical Chemistry, College
of Pharmacy, King Khalid University, Abha, Saudi Arabia.
Supplemental data for this article can be accessed on the publisher’s website.
ß 2021 Taylor & Francis Group, LLC

2
T. SYED ET AL.
Figure 1. Chemical structures of anticancer drugs and designed analogs.
[
1]
[2]
[3]
biological activities including anticancer, antitubercular, analgesic, anti-inflamma-
[
4]
[5]
[6]
[7]
[8]
[9]
tory, antibacterial, antifungal, anti-hypertensive, antiviral, anti-HIV, anti-
[
10]
[11]
oxidant
and tyrosine kinase inhibitors.
The U.S. FDA-approved chemotherapeutic
agent Erlotinib (1, Figure 1) contains quinazoline skeleton, used for treatment for non-
[
12]
small cell lung cancer.
In addition, isoxazoles is a unique class of five-ring heterocyc-
lic framework with significant biological importance in medicinal chemistry, pesticide
[
13]
and herbicides.
Recently, expansion of 1,2-isoxazole contained molecules are becom-
ing more demand target molecules in medicinal chemistry due to their numerous
pharmaceutical properties. Previously many researchers were synthesized and reported
[
14]
[15]
a variety of biological properties including anticancer,
immunomodulatory,
anti-
[
16]
[17]
[18]
[19]
[20]
convulsant,
antimicrobial,
and antiviral.
analgesic,
anti-inflammatory,
Among all 1,2-isoxazole derivatives, molecule with iso-
antiparasitic,
[
21]
[22]
anti-diabetic,
xazole units as a back-bone of the chemical structure like Luminespib (NVP-AUY922,
[
23]
2) were approved for treatment of cancers.
Now days, several researchers were turned their attention to synthesize two or more
biologically efficient heterocyclic molecules combined with one single framework. It is
more useful to discovery, development of novel therapeutic agents with lesser toxic and
more biological efficacy. In this regard, we have designed and synthesized a new series
of 1,2-isoxazole bearing quinazoline derivatives (12a–j) and their structures were con-
firmed by different types of spectral techniques. Finally, all compounds were evaluated
for their anticancer activity toward human cancer cell lines PC3, DU-145, A549 and
MCF-7.
Results and discussion
Chemistry
The synthetic route for the preparation of structurally modified substituted aryl-quina-
zoline derivatives (12a–j) was depicted in Scheme 1. The key intermediate 5 was devel-
oped by the reaction of methyl 2-amino-4,5-dimethoxybenzoate (3) with acetonitrile (4)
in the presence of HCl gas at reflux for 12 h. The resulting intermediate 5 was treated
ꢀ
with POCl in Diisopropyl ethylamine (DIPEA) in toluene at 80 C for 2 h to give a
3
pure compound 6. Next, Compound 6 was subjected to oxidation with SeO in dry 1,4-
2
dioxane at reflux for 1 h to give pure aldehyde intermediate 7. Further, compound 7
was subjected to Claisen-Schmidt reaction with 1-(3,4,5-trimethoxyphenyl)ethanone (8)

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Scheme 1. Synthetic route of aryl-quinazoline derivatives (12a–j).
in the presence of catalytic amount of piperidine base in ethanol at reflux for 1 h to
afford chalcone intermediate 9. Furthermore, this chalcone intermediate was reacted
with hydroxyl amine hydrochloride in isopropyl alcohol and pyridine at reflux for 2 h
to give isoxazole intermediate 10. Later, compound 10 was subjected to Suzuki-cross
coupling reaction with various types of aryl boronic acids (11a–j) in the presence of
Pd(dppf)Cl2 and Cs CO in THF at reflux for 12 h to afford pure final com-
2
3
pounds 12a–j.
Biological evaluation
In vitro cytotoxicity
The newly developed aryl-quinazoline-isoxazole (12a–j) derivatives were investigated for
their preliminary anticancer profile against four different types of human cancer cell
lines such as prostate (PC3 and DU-145), lung (A549) and breast (MCF-7) by using of
MTT assay by using etoposide as a positive control. These results were incorporated in
Table 1. Among the evaluated compounds, six compounds (12a, 12b, 12c, 12d and 12j)
displayed more potent anticancer activity on all tested cell lines. In which two

4
T. SYED ET AL.
a
Table 1. Anticancer activity of newly developed compounds (12a–j) with IC in mM.
5
0
c
d
e
f
Compound
PC3
A549
MCF-7
DU-145
ND
1
1
1
1
1
1
1
1
1
1
2a
2b
2c
2d
2e
2f
2g
2h
2i
2.13 ± 1.70
0.75 ± 0.023
0.34 ± 0.091
1.66 ± 0.85
1.02 ± 0.066
2.99 ± 1.95
3.71 ± 1.66
ND
1.73 ± 0.54
1.29 ± 0.17
0.07 ± 0.005
0.82 ± 0.019
1.99 ± 0.36
3.41 ± 1.57
ND
1.92 ± 0.85
1.47 ± 0.51
0.01 ± 0.008
2.08 ± 0.77
1.57 ± 0.18
ND
4.15 ± 2.01
5.88 ± 2.13
ND
0.083 ± 0.001
2.11 ± 0.024
0.92 ± 0.072
0.15 ± 0.011
1.81 ± 0.63
1.63 ± 0.55
2.11 ± 0.43
7.23 ± 2.36
9.10 ± 3.48
6.82 ± 3.10
0.76 ± 0.063
1.97 ± 0.45
3.59 ± 1.35
13.4 ± 6.55
0.06 ± 0.005
2.39 ± 1.56
ND
2j
0.021 ± 0.008
3.08 ± 0.135
Etoposide
ND: Not determine.
a
b,c
Each data represents as mean ± S.D values. From three different experiments performed in triplicates. PC3: human
prostate cancer cell line. A549: human lung cancer cell line. MCF-7: human breast cancer cell line. DU-145: human
d
e
f
prostate cancer cell line.
compounds 12c and 12j possessed excellent activity than with positive control. Further,
all compounds were determined for structure-activity relationship (SARs) study, the
results indicated that the compound 12c (3,4,5-trimethoxy) and 12j (2,4,6-trimethoxy)
with electron-donating substitutions on the aryl ring attached to quinazoline skeleton
showed
A549 ¼ 0.07 ± 0.005 mM; MCF-7 ¼ 0.01 ± 0.008 mM and DU-145 ¼ 0.15 ± 0.011 mM) and
PC3 ¼ 0.06 ± 0.005 mM; A549 ¼ 0.021 ± 0.008 mM; MCF-7 ¼ 0.083 ± 0.001 mM and DU-
45 ¼ 0.76 ± 0.063 mM) when compared with etoposide. Whereas, compound 12d con-
tain 3,5-dimethoxy group on the aryl ring showed slightly decreased activity
PC3 ¼ 1.66 ± 0.85 mM; A549 ¼ 0.82 ± 0.019 mM; MCF-7 ¼ 2.08 ± 0.77 mM and DU-
45 ¼ 1.81 ± 0.63 mM) than with 12c and 12j. Similarly, 4-methoxy group contain com-
pound 10e showed lower activity (PC3 ¼ 1.02 ± 0.066 mM; A549 ¼ 1.99 ± 0.36 mM; MCF-
¼ 1.57 ± 0.18 mM and DU-145 ¼ 1.63 ± 0.55 mM) than with 12c, 12j and 12d.
Interestingly, the weak-electron-donating group substituted compound 12a (4-methyl)
showed good activity A549 ¼ 1.73 ± 0.54 mM; MCF-
(PC3 ¼ 2.13 ± 1.70 mM;
higher
potency
of
anticancer
activity
(PC3 ¼ 0.34 ± 0.091 mM;
(
1
(
1
7
7
¼ 1.92 ± 0.85 mM). Similarly, compound 12b with 4-(dimethylamino) substitution on
aryl moiety displayed improved anticancer activity (PC3 ¼ 0.75 ± 0.023 mM;
A549 ¼ 1.29 ± 0.17 mM; MCF-7 ¼ 1.47 ± 0.51 mM and DU-145 ¼ 0.92 ± 0.072 mM) when
compared with 12a. The electron-withdrawing group contain compound 12f (4-chloro)
showed acceptable activity (PC3 ¼ 2.99 ± 1.95 mM; A549 ¼ 3.41 ± 1.57 mM; and DU-
1
45 ¼ 2.11 ± 0.43 mM). Whereas, compounds 12g (4-bromo), 12h (4-nitro) and 12i (4-
cyano) groups on the aryl ring displayed moderate anticancer activity.
Molecular docking studies with selective androgen receptor modulator SARM
(PDB ID: 3V49)
To understand the molecular interactions of the synthesized compounds against
Prostate cancer cells we have carried out molecular docking studies with cancer target
[
24]
SARM (PDB ID: 3V49).
AR) ligand binding domain with SARM inhibitor 1 (PDB ID: 3V49) were obtained
from RCSB PDB Data Bank. The active site is generated and the following are the active
The X-ray crystal structure of human Androgen Receptor
(

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Figure 2. 3D and 2D interactions of co-crystal ligand with SARM (PDB ID: 3V49).
Table 2. Docking score and binding interactions of aryl quinazoline-isoxazole (12a–j) derivatives
with selective androgen receptor modulator SARM (PDB ID: 3V49).
S. no Compound Dock score
H-bond
Hydrophobic interactions
1
2
3
4
5
6
7
8
9
12a
12b
12c
12d
12e
12f
ꢁ3.59
ꢁ2.83
ꢁ5.59
ꢁ8.18
ꢁ11.22
ꢁ4.12
ꢁ9.38
ꢁ8.14
ꢁ15.67
Thr860(2.25), Glu793(2.56), Ser865(2.95)
Lys808, Leu863, Ala748, Lys861, Leu862,
Leu790, Leu744,
Pro868, Ile869, Tyr915, Phe916, His917,
Ile815, Ala870
Leu712, His714, Arg710, Met894, Lys717,
Pro682, His714, Trp718, Val713
Val715, Trp718, Ala719, Ala748, Leu744,
Lys808, Lys720, Val685
Leu744, Met745, Leu790,Met807, Leu811,
Trp718, Ala748, Ile835, Leu838, Val715,
Val716, Leu712, Val713, Met894, Lys717,
Lys720, His714
Leu811, Phe794, Trp718, Phe747, Ala809,
Met749, Leu811, Leu812, Lys808
Leu881, Val889, Ile882, Lys883,
Phe878, Leu880
Leu704, Leu707,Arg752, Met780, Met787,
Leu873, Ala748
Val716, Leu712, Met894, Lys717, Lys720
Met742, Met745, Trp741, Phe764, Met780,
Val746, Met749, Ile899, Leu704, Leu707
Glu872(3.25), Leu810(3.79)
Glu709(2.60), Leu707(3.76), Val716(2.93)
Met807(2.87), Lys717(3.26),
Arg752(3.32), Trp718(3.51)
Leu863(2.17), Leu744(2.59), Lys808(3.46)
Val716(2.69)
12g
12h
12i
Leu812(3.36), Leu744(2.64), Ser740(3.61),
Leu805(3.15), Cys806(2.62)
Ser884(3.34), Thr877(2.59), Asp879(2.57)
Tyr763(3.66), Thr877(3.77),
Gln711(2.77), Gln711(2.27)
Gln711(2.95)
Arg752(2.87), His874(2.77),
Gly708(3.51), Thr877(3.17)
1
1
0
1
12j
Co-crystal
ꢁ4.89
ꢁ10.38
residues involved with co-crystal ligand as it forms hydrogen bond interactions with
Arg752(2.87), His874(2.77), Gly708(3.51), Thr877(3.17) amino acid residues with dis-
o
tance in A and hydrophobic interactions with Met742, Met745, Trp741, Phe764,
Met780, Val746, Met749, Ile899, Leu704, Leu707. Initially, the docking was validated by
performing redocking the co-crystal ligand into the binding site and observed the
docked co-crystal ligand pose were recuperates the information of crystal structure.
o
After redocking of co-crystal ligand the RMSD value is found to be 1.85 A which is
o
under 3.00 A of acceptable limit. All the docked ligands were also exhibited similar
interactions as mentioned earlier with respect to co-crystal ligand (Figure 2). The dock-
ing score and interactions with amino acid residues are represented in Table 2.

6
T. SYED ET AL.
Figure 3. 3D and 2D interactions of 12i with SARM (PDB ID: 3V49).
Among the ligands docked against SARM, Compound 12i with cyano substitution on
phenyl ring has showed highest rDock Score ꢁ15.67. It forms H-bond interactions with
amino acid residues Tyr763(3.66), Thr877(3.77), Gln711(2.77), Gln711(2.27) and hydro-
phobic interactions with residues Leu704, Leu707,Arg752, Met780, Met787, Leu873,
Ala748 (Figure 3). Similarly same type of interactions have noted for compound 12e
with methoxy substitution on phenyl ring having rDock Score value ꢁ11.22.
Compound 12e exerted H-bond interactions with Leu863(2.17), Leu744(2.59),
Lys808(3.46) and hydrophobic residues with Leu744, Met745, Leu790, Met807, Leu811,
Trp718, Ala748, Ile835, Leu838, Val715 amino acid residues (Figure 4). Interestingly,
the cyano group present in the structure of ligands and co-crystal ligand favors strong
interactions in SARM. It signifies that docked ligands is occupying the same residues of
active site of co-crystal ligand.
Molecular docking studies with Abl-Tyrosine kinase (PDB ID: 1IEP)
All the synthesized compounds were also performed docking studies with Abl-Tyrosine
[
25]
kinase (PDB ID: 1IEP) which is a potential target in cancer.
Before performing dock-
ing for synthesized compounds, docking protocol was validated with co-crystal ligand
which perfectly repositioned between co-crystal structure and re-docked structure was
observed. The co-crystal ligand has involved H-bond interactions with Glu286(2.57),
o
Asp381(2.42), Met318(3.06) Gly383(2.08) with bond distance in A and hydrophobic
interactions with Leu248, Leu370, Phe317, Phe382, Tyr253, Met290, Lys285, Ile313,
Val289, Ala269 amino acid residues with rDock Score ꢁ14.93. Among the ligand
docked against Abl-Tyrosine kinase (PDB ID: 1IEP), ligand 12a has shown highest
rDock Score ꢁ9.49. Compound 12a exerted H-bond interactions with Ile360(1.99),
Phe382(2.93), Gly383(2.16) amino acid residues and hydrophobic interactions with

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Figure 4. 3D and 2D interactions of 12e with SARM (PDB ID: 3V49).
Figure 5. 3D and 2D interactions of co-crystal ligand with Abl protein (PDB ID: 1IEP).
Leu354, Phe359, His361, Val289, Lys285 amino acid residues. All the
ligands have showed same interactions with active site of co-crystal ligand. (Figures
5
–7). The docking score and interactions with amino acid residues are represented in
Table 3.
In summary, the designed compounds showed good anticancer activity and excellent
free energy of binding interactions with Selective Androgen Receptor Modulator SARM
PDB ID: 3V49), and Abl-Tyrosine kinase (PDB ID: 1IEP).
(

8
T. SYED ET AL.
Figure 6. 3D and 2D interactions of 12a with Abl protein (PDB ID: 1IEP).
Figure 7. 3D and 2D Interactions of 12 g with Abl protein (PDB ID: 1IEP).
In silico drug likeliness and toxicity prediction
In silico drug likeliness properties of aryl quinazoline-isoxazole (12a–j) was assessed by
[
26]
using Drug-likeness quantitative estimation (QED) in Galaxy.
All the compounds
were determined molecular descriptors for Rule of 5 (Lipinski rule) which states the
oral bioavailability and drug like properties. The determinants are Molecular weight ꢂ
5
00, no of H-Acceptors ꢂ 10, no of H-Donor ꢂ 5. All compounds have violated Rule
of 5 (Table 4). QED (Quantitative Estimation Drug-Likeliness) is calculated from eight
properties such as M.W, ALOGP, HBA, HBD, PSA, ROTBs, AROMs, ALERTS. The

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Table 3. Docking score and binding interactions of aryl quinazoline-isoxazole (12a–j) derivatives
with Abl-Tyrosine kinase (PDB ID: 1IEP).
S. no
1
Compound
Dock score
H-bond
Hydrophobic interactions
Leu354, Phe359, His361,
Val289, Lys285
His375, Val377, Val339, Met343,
Tyr253, Tyr342, His375,
12a
ꢁ9.49
Ile360(1.99),
Phe382(2.93), Gly383(2.16),
Tyr253(3.01), Gly372(3.04),
Leu376(2.35), Val339(2.59)
2
12b
ꢁ0.67
Val335, Val371
3
4
12c
12d
0.08
Ala366(2.79), Arg367(3.11),
Cys369(3.09), Pro484(3.41), Glu409
Ala366(2.56), Asp381(3.01), Glu409
Ala365, Ala366, Arg367, Leu428,
Lys419, Arg483, Cys369, Val377
His375, Val377, Met343, His375,
Val335, Val371
ꢁ5.34
5
6
12e
12f
ꢁ4.59
ꢁ5.99
Thr315(2.87), Asp381(2.84),
Gly249(3.50)
Ala395, Arg386, Met388
Pro439, Arg367, Met388, Leu324,
Tyr393, Trp405, Arg367, Ala365
Leu248, Tyr253, Val256, Val299,
Phe382, Leu248, Ala269
7
8
9
12g
ꢁ9.39
Tyr253(3.34), Phe382(3.67),
Thr315(2.88),
Asp381(3.72), Gln252(3.02),
Glu329(2.78), Thr315(3.54),
Glu316(2.81), Tyr253(3.56)
12h
ꢁ5.75
Leu248, Tyr253, Gly321, Ala269,
Val256, Leu370, Phe382,
Leu248, Leu370
Lys285, Ala288, Leu284, Lys285,
Ala288, Val289
Leu248, Val256, Arg367,
His375, Val371
Leu248, Leu370, Phe317, Phe382,
Tyr253, Met290, Lys271, Ile313,
Val289, Ala269
12i
12j
ꢁ2.45
ꢁ6.71
Glu281(3.03), Lys285(3.55)
Gln252(2.58), Asp381(2.74)
1
0
1
1
Co-crystal
ꢁ14.93
Glu286(2.57),
Asp381(2.42), Met318(3.06)
value ranges from 0 (unfavorable properties) to 1 (favorable properties). All compounds
are also predicted for toxicity properties by using Data Warrior Software and all com-
pounds free from Mutagenic, Tumorigenic, Reproductive Effective and Irritant proper-
ties. The compounds also predicted for Natural Product (NP) Likeness for assessing the
similarity of structure space by known NP. The score with more positive value the
higher the NP-likeliness. None of the compounds have shown NP-likeliness.
MTT assay
Individual wells of a 96-well tissue culture micro titer plate were inoculated with 100 mL
4
ꢀ
of complete medium containing 1 ꢃ 10 cells. The plates were incubated at 37 C in a
humidified 5% CO incubator for 18 h prior to the experiment. After medium removal,
2
1
00 mL of fresh medium containing the test compounds and etoposide at different con-
ꢀ
centrations such as 0.5, 1, and 2 mM were added to each well and incubated at 37 C for
2
4 h. Then the medium was discarded and replaced with 10 mL MTT dye. Plates were
ꢀ
incubated at 37 C for 2 h. The resulting formazan crystals were solubilized in 100 mL
extraction buffer. The optical density (O.D) was read at 570 nm with micro plate reader
(
Multi-mode Varioskan Instrument-Themo Scientific). The percentage of DMSO in the
[
27]
medium never exceeded 0.25%.
Molecular docking studies
[
28]
The molecular docking studies were carried out in rDock.
The 3-dimensional pro-
teins (PDB: 3V49 and 1IEP) were retrieved from the protein data bank. The molecular

1
0
T. SYED ET AL.

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11
docking studies of all aryl quinazoline-isoxazole (12a–j) derivatives in the active site of
SARM, Selective Androgen Receptor Modulator (PDB ID: 3V49) https://www.rcsb.org/
structure/3V49, and Abl-Tyrosine kinase (PDB ID: 1IEP) https://www.rcsb.org/struc-
ture/1IEP were carried out in order to predict the binding efficiencies. The molecular
docking scores are summarized in Tables 2 and 3.
All the proteins were converted into Mol2 format. The receptor grid around their co-
crystal ligands were generated using rDock cavity definition which generates the active
site for docking. All the ligand structures were drawn in Marvin sketch and optimized
into 3 D structures. All the ligands to be docked were prepared in SDF format. The
number of docking poses is set as 10 and number of best poses is given as 10. The
rDock Score is sum of intermolecular, site intramolecular, ligand intramolecular and
external restraint. The 3 D and 2 D interactions were generated with Discovery Studio
Experimental section
All chemicals and reagents were obtained from Aldrich (Sigma–Aldrich, St. Louis, MO,
USA), Lancaster (Alfa Aesar, Johnson Matthey Company, Ward Hill, MA, USA) and
were used without further purification. Reactions were monitored by TLC, performed
on silica gel glass plates containing 60 F-254, and visualization on TLC was achieved by
1
13
UV light or iodine indicator. H and C NMR spectra were recorded on BRUKER
NMR (300 MHz, 400 MHz) instrument. Chemical shifts (d) are reported in ppm down-
field from internal TMS standard. ESI spectra were recorded on Micro mass, QuattroLC
using ESI þ software with capillary voltage 3.98 kV and ESI mode positive ion trap
detector. Melting points were determined with anelectro thermal melting point appar-
atus, and are uncorrected.
6,7-Dimethoxy-2-(3-(3,4,5-trimethoxyphenyl)isoxazol-5-yl)-4-p-
tolylquinazoline (12a)
To a solution of compound 10 (400 mg, 0.87 mmol) and 4-methylphenylboronic acid
(
11a)(154 mg, 1.13 mmol) in anhydrous THF (80 mL), Pd(dppf)Cl (32 mg, 0.043 mmol,
2
5
mol%), and Cs CO (567 mg, 1.74 mmol) was added. The reaction mixture was stirred
2 3
at reflux for 12 h. After completion of the reaction by TLC, the reaction mixture was
diluted with water and extracted with ethyl acetate. The combined organic extracts were
dried with anhydrous Na SO and concentrated under vacuum to afford crude product
2
4
which was purified by column chromatography (hexane/ethyl acetate, 6:4) to afford
ꢀ
1
pure compound 12a, as 298.4 mg with 67% yield with white solid. MP: 310–312 C; H
NMR (300 MHz, DMSO-d6): d 2.73 (s, 3H), 3.89 (s, 6H), 3.93 (s, 3H), 4.07 (s, 3H), 4.09
(
s, 3H), 7.27–7.38 (m, 3H), 7.52 (d, 2H, J ¼ 7.2 Hz), 7.66 (s, 1H), 7.74 (d, 2H,
13
J ¼ 7.2 Hz), 7.89 (s, 1H); C NMR (75 MHz, DMSO-d6): d 26.7, 57.4, 58.6, 58.9, 62.1,
1
1
02.7, 105.4, 108.3, 113.6, 130.2, 130.7, 131.5, 134.6, 141.3, 141.7, 142.5, 149.2, 151.7,
þ
52.5, 153.4, 154.5, 157.4, 163.6,169.8; MS (ESI): m/z 514 [M þ H] . HRMS (ESI): m/z
þ
calculated for C H O N [M þ H] 514.1978, found 514.1982.
2
9
28 6 3

1
2
T. SYED ET AL.
Conclusion
In conclusion, we have synthesized a novel series of different aryl-substituted quinazo-
line-isoxzaole derivatives (12a–j) and their structures were confirmed by spectroscopic
techniques. All compounds were examined for their anticancer properties against
human PC3 and DU-145 (prostate), A549 (lung) and MCF-7 (breast) cancer cell lines
by employing MTT analysis with clinical drug as etoposide used as positive control.
Among them, compounds 12a, 12b, 12c, 12d and 12j exhibited more potent anticancer
activities on all cell lines. All the docked ligands have exhibited good binding interac-
tions with the targeted protein. In the future, a detailed mechanistic studies could be
performed for the potent anticancer agents and further lead optimization will also
be studied.
Acknowledgments
The authors are thankful to the Dean of Scientific Research, King Khalid University and the
College of Pharmacy, Department of Pharmaceutical Chemistry for providing facilities to carry
out our research work.
Disclosure statement
The authors declare that they have no competing interests.
Funding
This work was supported by the Dean of Scientific Research, King Khalid University for the
financial support is greatly appreciated for the General Research Project under grant number
[
R.G.P2/83/41].
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