Design and synthesis of 4-amino-2-phenylquinazolines as novel topoisomerase i inhibitors with molecular modeling

Article abstract of DOI:10.1016/j.bmc.2011.05.012

4-Amino-2-phenylquinazolines 7 were designed as bioisosteres of 3-arylisoquinolinamines 6 that were energy minimized to provide stable conformers. Interestingly, the 2-phenyl ring of 4-amino-2-phenylquinazolines was parallel to the quinazoline ring and improved their DNA intercalation ability in the DNA-topo I complex. Among the synthesized 4-amino group-substituted analogs, 4-cyclohexylamino-2-phenylquinazoline 7h exhibited potent topo I inhibitory activity and strong cytotoxicity. Interestingly, consistency was observed between the cytotoxicities and topo I activities in these quinazoline analogs, suggesting that the target of 4-amino-2-phenylquinazolines is limited to topo I. Molecular docking studies were performed with the Surflex-Dock program to afford the ideal interaction mode of the compound into the binding site of the DNA-topo I complex in order to clarify the topo I activity of 7h.

Full text of DOI:10.1016/j.bmc.2011.05.012

Bioorganic & Medicinal Chemistry 19 (2011) 4399–4404
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
Design and synthesis of 4-amino-2-phenylquinazolines as novel topoisomerase
I inhibitors with molecular modeling
Thanh Nguyen Le a, Su Hui Yang a, Daulat Bikram Khadka a, Hue Thi My Van a, Suk Hee Cho a,
Youngjoo Kwon b, Eung-Seok Lee c, Kyung-Tae Lee d, Won-Jea Cho a,
⇑
a College of Pharmacy and Research Institute of Drug Development, Chonnam National University, Gwangju 500-757, Republic of Korea
b College of Pharmacy, Ewha Womans University, Seoul 120-750, Republic of Korea
c College of Pharmacy, Yeungnam University, Kyongsan 712-749, Republic of Korea
d College of Pharmacy, Kyung-Hee University, Seoul 130-701, Republic of Korea
a r t i c l e i n f o
a b s t r a c t
Article history:
4-Amino-2-phenylquinazolines 7 were designed as bioisosteres of 3-arylisoquinolinamines 6 that were
energy minimized to provide stable conformers. Interestingly, the 2-phenyl ring of 4-amino-2-phenylqui-
nazolines was parallel to the quinazoline ring and improved their DNA intercalation ability in the
DNA–topo I complex. Among the synthesized 4-amino group-substituted analogs, 4-cyclohexylamino-
2-phenylquinazoline 7h exhibited potent topo I inhibitory activity and strong cytotoxicity. Interestingly,
consistency was observed between the cytotoxicities and topo I activities in these quinazoline analogs,
suggesting that the target of 4-amino-2-phenylquinazolines is limited to topo I. Molecular docking stud-
ies were performed with the Surflex–Dock program to afford the ideal interaction mode of the compound
into the binding site of the DNA–topo I complex in order to clarify the topo I activity of 7h.
Ó 2011 Elsevier Ltd. All rights reserved.
Received 4 April 2011
Revised 6 May 2011
Accepted 7 May 2011
Available online 20 May 2011
Keywords:
4-Amino-2-phenylquinazolines
Topoisomerase I
Cytotoxicity
Docking study
DNA intercalation
1. Introduction
We investigated the structure–activity relationships of 3-
arylisoquinolinones 1 against human tumor cell lines with molec-
Eukaryotic DNA topoisomerase I (topo I) is a crucial enzyme
that works to relax supercoiled DNA during replication, transcrip-
tion, and mitosis.1 In a number of human solid tumors, the intra-
cellular level of topo I is higher than that in normal tissues,
signifying that controlling the topo I level is essential in treating
cancers.2 By stabilizing the cleavable topo I–DNA ternary complex
with drug, topo I inhibitors exhibit their antitumor activities.
Therefore, topo I enzyme has been considered a promising target
for the development of novel cancer chemotherapeutics.3
Representative topo I inhibitors, such as topotecan and irinotec-
an as analogs of camptothecin (CPT), have been launched as clini-
cally used drugs. However, severe drawbacks of these drugs, such
as unstable chemical structure and rapid efflux from the cell by
membrane pumps, prompted us to develop non-camptothecin
topo I inhibitors.4
ular modeling study and conducted a diverse modification study of
3-arylisoquinoline skeleton to furnish indeno[1,2-c]isoquinolines
2,12 isoindolo[2,1-b]isoquinolinones 3,13 12-oxobenzo[c]phenanth-
ridinones 4,14 and benz[b]oxepines 515 as the constrained forms of
the 3-aryl rings as shown in Figure 1. Most of these 3-arylisoquin-
oline analogs showed micromolar cytotoxicities against several tu-
mor cell lines as topo I inhibitors.
In this investigation, we observed that the amide carbonyl
group of 3-arylisoquinolinone played an important role in the cyto-
toxicities, and the transformation of the amides to amines in-
creased water solubility while retaining the biological potency.
Among the 3-arylisoquinolinamines, 6a was subjected to in vivo
assay using BDF1 mice (P388 leukemia) and afforded 160 T/C%
with low toxicity.16 The high oral bioavailability and promising
pharmacokinetic data of 6a provided valuable information for
studying related compounds.
In general, the binding mode of a drug to its receptor site is
influenced by subtle electronic or steric factors, and these two
functions play an important role in the bioactive conformation of
the drug molecule. Rigid structures are commonly considered to
have little conformational entropy compared to flexible molecules
and can be more efficiently fitted into the binding site of a recep-
tor.17 However, additional methylene unit or heteroatoms in a con-
strained structure affect the physicochemical and/or biological
The non-CPT topo I inhibitors include indenoisoquinolines,5
indolocarbazones,6 saintopin,7 benzophenazines,8 terpyridines,9
and 3-arylisoquinolines.10 The X-ray crystal structures of topo I–
DNA complex bound to topotecan, indenoisoquinoline, and indo-
locarbazone have been solved.11
⇑
Corresponding author. Tel.: +82 62 530 2933; fax: +82 62 530 2911.
E-mail address: wjcho@jnu.ac.kr (W.-J. Cho).
0968-0896/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2011.05.012

4400
T. N. Le et al. / Bioorg. Med. Chem. 19 (2011) 4399–4404
R2
R3
R2
R2
R1
R1
N
R1
NH
NMe
O
O
O
Isoindolo[2,1-b]isoquinolines (3)
3-Arylisoquinolinones (1)
Indeno[1,2-c]isoquinolines (2)
O
O
N
R2
R2
R2
N
R
R
O
O
Benz[b]oxepines(5)
12-Oxobenzophenanthridinones (4)
Figure 1. Chemical modification of 3-arylisoquinolinones (1) to indeno[1,2-c]isoquinolines (2), isoindolo[2,1-b]isoquinolines (3), 12-oxobenzophenanthridinones (4) and
benz[b]oxepines (5).
effects, too. We have also observed that the flatness of the com-
pounds provides an advantage for positioning in the topo I–DNA
ternary complex due to its DNA intercalating ability.
The X-ray crystallographic structure of 3-arylisoquinoline
showed that the torsion angle of the 3-phenyl ring with the iso-
quinoline plate was 30° and it was not suitable for intercalation
into the DNA base pairs.18
N
N
amine
N
N
dioxane
R
Cl
7
In the above investigation, we designed the 4-amino-2-phenyl-
quinazolines as the bioisosteres of 3-arylisoquinolines. When
4-amino-2-phenylquinazoline was minimized in Sybyl, the torsion
angle of the 2-phenyl ring with the quinazoline ring was only 8.2°,
meaning that all pi electrons of the 2-phenyl ring could
conjugate with those in the quinazoline template. Moreover, we
assumed that the stable conformer of 4-amino-2-phenyl-
quinazolines could be effective as a DNA intercalator in the
DNA–topo I complex because they do not contain an extra methy-
lene unit or heteroatoms.
Me
Me
g:
a:
R=
NH
N
N
N Me
O
h:
i:
b:
c:
NH
NH
OMe
COOEt
N
H
HCl
2. Chemistry
Diverse substitution on C4 was accomplished by the reaction of
4-chloro-2-phenylquinazoline with various amines in dioxane to
furnish the desired products in good yield as shown in Scheme 1.
j:
d:
N Me
NHMe
N
3. Results and discussion
3.1. Biological evaluation
HCl
NH
COOMe
NH
NH
k:
l:
e:
f:
Me
Me
N
The in vitro cytotoxicity experiments of the synthesized com-
pounds were conducted against four human tumor cell lines
including A 549 (lung), SKOV-3 (ovarian), SK-MEL-2 (melanoma),
and HCT 15 (colon) cells using sulforhodamine B (SRB) assays.19
The topo I inhibitory activity assay was performed using the
supercoiled DNA unwinding method.20 The compounds were dis-
solved in DMSO at 20 mM as stock solutions. The DNA topo I po-
tency was determined by assessing the relaxation of supercoiled
DNA pBR322. A mixture of 200 ng of pBR322 plasmid DNA and 2
units of calf thymus DNA topo I (Fermentas, USA) was incubated
without and with the prepared compounds at 37 °C for 30 min in
relaxation buffer (35 mM Tris–HCl (pH 8.0), 72 mM KCl, 5 mM
MgCl2, 5 mM dithiothreitol, 2 mM spermidine, 0.01% bovine serum
N
Me
Scheme 1. Synthesis of 4-amino-2-phenylquinazolines (7a–l).
ethidium bromide (0.5 lg/ml). DNA bands were visualized by
transillumination with UV light and were quantitated using Alpha-
Imager™ (Alpha Innotech Corporation).
In Table 1, the IC50 cytotoxicity values obtained with cell lines
and the relative topo I activities of the compounds are expressed
semi-quantitatively as follows: – no activity, + very weak activity,
++ weak activity, +++ lower activity than CPT, ++++ similar or
greater activity than CPT.
As expected, 4-amino-2-phenylquinazolines showed excellent
topo I inhibitory activity compared to 3-arylisoquinolinamines as
depicted in Figures 2 and 3 and Table 1. In particular, isopropyla-
mino- or cyclohexyl-substituted quinazolines 7g and 7h exhibited
potent topo I poison (++++) comparable to the representative topo I
albumin). The reaction (final volume: 20
lL) was terminated by
adding 5 L of stop solution containing 10% SDS, 0.2% bromophe-
l
nol blue, 0.2% xylene cyanol and 30% glycerol. DNA samples were
then electrophoresed on 1% agarose gels at 15 V for 6 h in TAE run-
ning buffer. Gels were stained for 30 min in an aqueous solution of

T. N. Le et al. / Bioorg. Med. Chem. 19 (2011) 4399–4404
4401
Table 1
Synthetic yield, IC50 cytotoxicity (
l
g/mL) and topo I inhibitory activity of the compounds
No.
Compd
Yield
A549
26.88
52.76
27.45
24.10
36.26
15.13
7.53
7.23
>100
29.32
9.79
28.13
0.01
HCT15
OV-3
26.84
MEL-2
37.04
Topo Ia
1
2
3
4
5
6
7
8
7a
7b
7c
7d
7e
7f
7g
7h
7i
7j
7k
7l
88
94
90
88
85
84
89
84
88
88
84
91
22.37
51.84
26.84
20.10
37.46
13.91
4.11
++
+++
+
+++
+
56.98
22.90
26.10
35.50
31.73
16.90
9.82
>100
33.62
9.50
65.23
27.64
36.55
37.63
31.21
16.47
9.63
++
++++
++++
ꢀ
2.76
9
>100
21.17
6.13
26.47
0.05
>100
10
11
12
13
14
24.36
15.78
28.92
0.09
6.88
ꢀ
ꢀ
25.53
0.08
1.54
++
Doxorubicin
Camptothecin
0.072
0.096
++++
a
Activity is expressed semi-quantitatively as follows: – no activity, + very weak activity, ++ weak activity, +++ lower activity than
CPT, ++++ similar or greater activity than CPT.
N
N
N
NHR
NHR
1-Amino-3-phenylisoquinolines (6)
4-Amino-2-phenylquinazolines (7)
N
N
N
N
N
N
N
Me
Me
7a
6a
Figure 2. The structures of 1-amino-3-phenylisoquinolines (6) and 4-amino-2-phenylquinazolines (7). Energy minimized conformers and comparison of torsion angles
between N-methylpiperazinyl-3-arylisoquinoline (6a) and 2-phenyl-4-N-methylpiperazinylquinazoline (7a).
Figure 3. Topo I inhibitory activities of the synthesized quinazolines. Lanes # 1–12 correspond to the synthesized compounds: 1 (7a), 2 (7b), 3 (7c), 4 (7d), 5 (7e), 6 (7f), 7
(7g), 8 (7h), 9 (7i), 10 (7j), 11 (7k), 12 (7l).
inhibitor CPT. Moderate topo I inhibitory activity (+++) was ob-
served in morpholine- or N-methylhomopiperazinyl-substituted
compounds 7b and 7d. Overall, the topo I activities of the hetero-
atom containing amines such as N-methylpiperidine 7a, methoxy-
ethylamine 7c, methylacetateamine 7e, and ethylpropionateamine
7i were poor. In many cases a discrepancy between the cytotoxic-
ity and topo I poison was reported.21 This was also observed in
indenoisoquinoline and benzazepine derivatives, and it could be
explained by problems in drug penetration, cell membrane distri-
bution, and different targets. However, compounds 7g and 7h dis-
played potent cytotoxicities (2.76–16.47 lg/ml) as well as topo I
inhibitory activity (++++). Consistency between cytotoxicities and
topo I activities was also observed in other poorly active com-
pounds. Based on the observation, we can exclude the possibility
of other targets for explaining the cytotoxicities of these
4-amino-2-phenylquinazolines.

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T. N. Le et al. / Bioorg. Med. Chem. 19 (2011) 4399–4404
3.2. Docking study
amino-2-phenylquinazoline 7h exhibited potent topo I inhibitory
activity as well as strong cytotoxicity. As expected, molecules con-
taining the 4-amino-2-phenylquinazolines exhibited potent topo I
inhibitory activities with relatively strong cytotoxicities against
four different tumor cell lines. On the other hand, the heteroatom
containing amines such as N-methylpiperidine 7a, methoxyethyl-
amine 7c, methylacetateamine 7e, and ethylpropionateamine 7i
showed poor topo I poison, even though some of them exhibited
strong cytotoxicity. Consistency between cytotoxicities and topo I
activities was observed in these series, suggesting that the target
of 4-amino-2-phenylquinazolines is limited to topo I enzyme.
Molecular docking studies were performed with the Surflex–
Dock program in order to clarify the topo I activity of 7h and to af-
ford the ideal interaction mode of the compound in the binding site
of the DNA–topo I complex.
We found the bioisosteres of 3-arylisoquinolines by inserting
nitrogen atom at C-4 and obtained topo I inhibitory activities sim-
ilar to those of the constrained structures such as indenoisoquino-
lines, isoindolo[2,1-b]isoquinolines, and ben[b]oxepines. In further
studies of other rigidified structures of 3-arylisoquinolines, struc-
tural modifications such as 3,4-diarylation of 3-arylisoquinolines
are currently being performed and will be reported in due course.
The docking study was conducted using Surflex–Dock in Sybyl
version 8.1.1 by Tripos Associates, operating under Red Hat Linux
4.0 with an IBM computer (Intel Pentium 4, 2.8 GHz CPU, 1 GB
memory).
With the X-ray crystallographic structure of topo I–DNA com-
plex with indenoisoquinoline, docking studies of indenoisoquino-
lines in the active site have been more realistic than those of
molecules at non-clarified binding sites. The structure of the inhib-
itor 7h was drawn into the Sybyl package with standard bond
lengths and angles, and was minimized using the conjugate gradi-
ent method. The Gasteiger–Huckel charge, with a distance-depen-
dent dielectric function, was applied for the minimization of the
molecule. We chose the 1SC7 (PDB code) structure from the Pro-
tein Data Bank and the structure was modified. The phosphoester
bond of G12 in 1SC7 was constructed and the SH of G11 on the
scissile strand was changed to OH.
After performing Surflex–Dock, the scores of 10 docked con-
formers were ranked in a molecular spread sheet. We chose the
best total scoring conformer (7.80) and speculated regarding the
detailed binding modes in the cavity. The resulting docking model
exposed a binding pattern similar to the indenoisoquinoline model.
In this model, the isoquinoline ring intercalated between the ꢀ1
and +1 bases, parallel to the plane of the base pairs, and the C-1
nitrogen of 4-amino-2-phenyl-cyclohexylaminoquinazoline 7h
had a H-bond to Arg 364, which is considered an important amino
acid that interacts with the ligand in the DNA–topo I active site. In
this model, the isoquinoline ring worked as a DNA intercalator. The
4-cyclohexyl amino group of 7h showed hydrophobic interaction
with T 10 methyl group and Ala 351 side chain and seemed to in-
crease the topo I activity of 7h. Moreover, the 2-phenyl group is
positioned to DNA base pairs as the parallel form to the isoquino-
line ring of 7h. Thus, the importance of the DNA intercalation of 7h
and the hydrogen bond was clarified through the molecular dock-
ing study. Docking and space filling models of 7h are shown in
Figure 4.
5. Experimental section
5.1. Chemistry
Melting points were determined by the capillary method on an
Electrothermal IA9200 digital melting point apparatus and were
uncorrected. Nuclear magnetic resonance (NMR) data for 1H NMR
were collected on a Varian 300 FT spectrometer at the Korea Basic
Science Institute and were reported in ppm, downfield from the
peak of the internal standard, tetramethylsilane. The data are re-
ported as follows: chemical shift, number of protons, multiplicity
(s: singlet, d: doublet, t: triplet, q: quartet, m: multiplet, br: broad-
ened). IR spectra were recorded on JASCO-FT IR spectrometer using
CHCl3 or KBr pellets. Mass spectra were obtained on JEOL JNS-DX
303 using the electron-impact (EI) method. Column chromatogra-
phy was performed on Merck silica gel 60 (70–230 mesh). TLC was
performed using plates coated with silica gel 60 F254 that were
purchased from Merck.
4. Conclusion
In conclusion, we designed the 4-amino-2-phenylquinazolines
as bioisosteres of 3-arylisoquinolinamines. The conformers of the
energy minimized quinazolines and 3-arylisoquinolines are quite
different. Interestingly, the 2-phenyl ring of the 4-amino-2-phenyl-
quinazolines was parallel to the quinazoline ring and improved the
DNA intercalation ability in the DNA–topo I complex. Among the
synthesized 4-amino group-substituted analogs, 4-cyclohexyl-
5.2. General procedure for the synthesis of 4-amino-2-
phenylquinazolines
A
suspension of 4-chloro-2-phenylquinazoline (200 mg,
0.83 mmol) and amine (17 mmol) in dioxane (10 mL) was refluxed
Figure 4. Stereo viewing docked models of 7h in the active site of DNA–topo I complex.

T. N. Le et al. / Bioorg. Med. Chem. 19 (2011) 4399–4404
4403
for 24 h. The reaction was quenched with water and extracted with
methylene chloride. The methylene chloride solution was sequen-
tially washed with 5% aqueous NaOH, water, and brine and dried
over anhydrous sodium sulfate. After removing the solvent, the
residue was separated by column chromatography on silica gel
with methylene chloride–methanol (20:1) to give the desired com-
pound. Treatment of the free amine compound with cHCl in ace-
tone gave the hydrochloride salt form of the amines as precipitates.
1H), 4.41 (m, 1H), 2.25 (m, 2H), 1.87–1.31 (m, 8H). Anal.
(C20H21N) C, H, N. EIMS m/z (%): 303 (M+, 10).
5.2.9. 3-(2-Phenylquinazolin-4-ylamino)propionic acid ethyl
ester (7i)
Oil (88%). mp: 268–270 °C (HCl salt). IR (cmꢀ1): 3402, 1728,
1571, 1531. 1H NMR (300 MHz, CDCl3) d: 8.57–8.53 (m, 2H); 7.91
(m, 1H); 7.73–7.68 (m, 2H); 7.49–7.39 (m, 4H); 6.51 (t, J = 5.7 Hz,
1H); 4.15 (q, J = 6 Hz, 2H); 4.09 (q, J = 7.2 Hz, 2H); 2.81 (t,
J = 6 Hz, 2H); 1.25 (t, J = 7.2 Hz, 3H). HRMS-EI (Calcd for C18 H17
N3O2): 307.3551. Found: 307.3556. EIMS m/z (%): 307 (M+, 65).
5.2.1. 4-(4-Methylpiperazin-1-yl)-2-phenylquinazoline (7a)
White solid (88%). mp: 92.5–93.5 °C, 270–272 °C (HCl salt). IR
(cmꢀ1): 2963, 1557, 1500. 1H NMR (300 MHz, CDCl3) d: 8.55 (m,
2H), 7.97 (m, 1H), 7.95 (m, 1H), 7.72 (m, 1H), 7.49–7.40 (m, 4H),
3.90 (t, J = 5 Hz, 4H), 2.67 (t, J = 5 Hz, 4H), 2.39 (s, 3H). Anal.
(C19H20N4) C, H, N. EIMS m/z (%): 304 (M+, 3).
5.2.10. Methyl(2-phenylquinazolin-4-yl)amine (7j)
White solid (81%). mp: 94–96 °C, 297–299 °C (HCl salt). IR
(cmꢀ1): 3340, 2956, 1570, 1527. 1H NMR (300 MHz, CDCl3) d:
8.60–8.56 (m, 2H), 7.90 (m, 2H), 7.69–7.63 (m, 1H), 7.49–7.34
(m, 4H), 5.83 (d, J = 4.2 Hz, 1H), 3.28 (d, J = 4.2 Hz, 2H). Anal.
(C15H13N3) C, H, N. EIMS m/z (%): 235 (M+, 48).
5.2.2. 4-Morpholin-4-yl-2-phenylquinazoline (7b)
White solid (94%), IR (cmꢀ1): 2968, 1560, 1500. mp: 124–
125 °C, 291–293 °C (HCl salt). 1H NMR (300 MHz, CDCl3) d: 8.57–
8.54 (m, 2H), 7.98 (m, 1H), 7.88 (m, 1H), 7.73 (m, 1H), 7.50–7.42
(m, 4H), 3.96–3.93 (m, 4H), 3.87–3.83 (m, 4H). Anal. (C18H17N3O)
C, H, N. EIMS m/z (%): 291 (M+, 39).
5.2.11. N,N,N0-Trimethyl-N0-(2-phenylquinazolin-4-yl)ethane-
1,2-diamine (7l)
Oil (91%). mp: 286–288 °C (HCl salt). IR (cmꢀ1): 2963, 1557,
1500. 1H NMR (300 MHz, CDCl3) d: 8.56–8.52 (m, 2H), 8.01 (m,
1H), 7.92 (m, 1H), 7.68 (m, 1H), 7.48–7.34 (m, 4H), 3.94 (t,
J = 8 Hz, 2H), 3.46 (s, 3H), 2.79 (d, J = 8 Hz, 2H), 2.34 (s, 6H).
HRMS-EI (Calcd for C19 H22 N4): 306.4139. Found: 306.4135. EIMS
m/z (%): 306 (M+, 28).
5.2.3. (2-Methoxyethyl)-(2-phenylquinazolin-4-yl)amine (7c)
Yellow solid (90%). mp: 130.5–131.5 °C, 228–230 °C (HCl salt).
IR (cmꢀ1): 3355, 2978, 1570, 1533. 1H NMR (300 MHz, CDCl3) d:
8.57–8.53 (m, 2H), 7.92 (m, 1H), 7.73–7.68 (m, 2H), 7.50–7.37
(m, 4H), 6.14 (t, J = 4.7 Hz, 1H), 4.01 (q, J = 5.1 Hz, 2H), 3.73 (t,
J = 5.1 Hz, 2H), 3.44 (s, 3H). Anal. (C17H17N3O) C, H, N. EIMS m/z
(%): 279 (M+, 85).
Acknowledgment
This work was supported by Korea Research Foundation grant
(KRF-2009-0071379).
5.2.4. 4-(4-Methyl-[1,4]diazepan-1-yl)-2-phenylquinazoline
(7d)
White solid (88%). mp: 81–83 °C. IR (cmꢀ1): 2962, 1557, 1500.
1H NMR (300 MHz, CDCl3) d: 8.57–8.52 (m, 2H), 7.97–7.91 (m,
2H), 7.68 (m, 2H), 7.50–7.38 (m, 4H), 4.19 (m, 2H), 4.09 (t,
J = 5 Hz, 2H), 3.00 (m, 2H), 2.68 (m, 2H), 2.42 (s, 3H), 2.23 (m,
2H). Anal. (C20H22N4) C, H, N. EIMS m/z (%): 318 (M+, 40).
References and notes
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5.2.5. (2-Phenylquinazolin-4-ylamino)acetic acid methyl ester
(7e)
White solid (85%). mp: 140–141 °C, 235–237 °C (HCl salt). IR
(cmꢀ1): 1342, 1728, 1571, 1531. 1H NMR (300 MHz, CDCl3) d:
8.57–8.54 (m, 2H), 7.92 (m, 1H), 7.81–7.70 (m, 2H), 7.49–7.40
(m, 4H), 6.49 (t, J = 4.8 Hz, 1H), 4.52 (d, J = 4.8 Hz, 2H), 3.84 (s,
3H). EIMS m/z (%): 293 (M+, 44).
6. Yamashita, Y.; Fujii, N.; Murakaya, C.; Ashizawa, T.; Okabe, M.; Nakano, H.
Biochemistry 1992, 31, 12069.
5.2.6. Benzyl(2-phenylquinazolin-4-yl)amine (7f)
White solid (84%). mp: 121.5–123.5 °C, 272–274 °C (HCl). IR
(cmꢀ1): 3300, 1561, 1530. 1H NMR (300 MHz, CDCl3) d: 8.59–
8.55 (m, 2H), 7.93 (m, 1H), 7.73–7.70 (m, 2H), 7.48–7.37 (m, 9H),
5.96 (t, 1H), 5.02 (t, J = 5.4 Hz, 2H). Anal. (C21H17N3) C, H, N. EIMS
m/z (%): 311 (M+, 78).
7. Yamashita, Y.; Kawada, S.; Fujii, N.; Nakano, H. Biochemistry 1991, 30, 5838.
8. Vicker, N.; Burgess, L.; Chuckowree, I. S.; Dodd, R.; Fokes, A. J.; Hardick, D.;
Hancox, T. C.; Miller, W.; Milton, J.; Sohal, S.; Wang, S.; Wren, S. P.; Charlton, P.
A.; Dangerfield, W.; Liddle, C.; Mistry, P.; Stewart, A. J.; Denny, W. A. J. Med.
Chem. 2002, 45, 721.
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Lee, E.-S. Bioorg. Med. Chem. 2010, 18, 377.
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L.; Burgin, A. B. J. Med. Chem. 2005, 48, 2336.
12. (a) Van, H. T. M.; Le, Q. M.; Lee, K. Y.; Lee, E. S.; Kwon, Y.; Kim, T. S.; Le, T. N.; Lee,
S. H.; Cho, W. J. Bioorg. Med. Chem. Lett. 2007, 17, 5763; (b) Cho, W. J.; Le, Q. M.;
Van, H. T. M.; Lee, K. Y.; Kang, B. Y.; Lee, E. S.; Lee, S. K.; Kwon, Y. Bioorg. Med.
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13. Van, H. T. M.; Cho, W. J. Bioorg. Med. Chem. Lett. 2009, 19, 2551.
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15. Khadka, B. K.; Cho, W. J. Bioorg. Med. Chem. 2011, 19, 724.
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2001, 217, 101.
17. Merabet, N.; Dumond, J.; Collinet, B.; Van Baelinghem, L.; Boggetto, N.; Ongeri,
S.; Ressad, F.; Reboud-Ravaux, M.; Sicsic, S. J. Med. Chem. 2004, 47, 6392.
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E. S. Bioorg. Med. Chem. 2002, 10, 2953.
5.2.7. Isopropyl(2-phenylquinazolin-4-yl)amine (7g)
Yellow solid (89%). mp: 147–148 °C, 280–282 °C (HCl salt). IR
(cmꢀ1): 3285, 2964, 1566, 1524. 1H NMR (300 MHz, CDCl3) d:
8.58–8.55 (m, 2H), 7.90 (m, 1H), 7.73–7.66 (m, 2H), 7.49–7.42
(m, 4H), 5.48 (d, 1H), 4.73 (m, 1H), 1.41 (d, J = 5 Hz, 6H). Anal.
(C17H17N3) C, H, N. EIMS m/z (%): 263 (M+, 36).
5.2.8. Cyclohexyl(2-phenylquinazolin-4-yl)amine (7h)
White solid (84%). mp: 154–155 °C, 262–264 °C. IR (cmꢀ1):
3300, 1561, 1530. 1H NMR (300 MHz, CDCl3) d: 8.56–8.53 (m,
2H), 7.90 (m, 1H), 7.72–7.65 (m, 2H), 7.49–7.39 (m, 4H), 5.54 (d,

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