Fused Quinazolinoquinazolinones: Synthesis, Isomerization, Spectroscopic Identification, and Anticancer Activity

Article abstract of DOI:10.1002/jhet.2258

13H-quinazolino[3,4-a]quinazolin-13-ones have been synthesized from 2-aminobenzamides in four steps. An acid-catalyzed or base-catalyzed isomerization of 13H-quinazolino[3,4-a]quinazolin-13-ones to 8H-quinazolino[4,3-b]quinazolin-8-ones in excellent yields (90-95%) has been reported. The differences in the infrared and nuclear magnetic resonance (¹H & ¹³C) data of these isomeric fused quinazolinoquinazolinones afford a useful method for distinguishing between the two series. These analogs showed moderate anticancer activity (EGFR-TK inhibition).

Full text of DOI:10.1002/jhet.2258

Month 2014
Fused Quinazolinoquinazolinones: Synthesis, Isomerization,
Spectroscopic Identification, and Anticancer Activity [1]
a
a
b
c
*
Somepalli Venkateswarlu, Meka Satyanarayana, Vijaybaskar Lakshmikanthan, and Vidavalur Siddaiah
aDrug Discovery, Laila Impex Research Center, No. 1, Phase III, Jawahar Autonagar, Vijayawada 520 007, India
bCellular and Molecular Biology, Laila Impex Research Center, No. 1, Phase III, Jawahar Autonagar, Vijayawada 520 007, India
cDepartment of Organic Chemistry, School of Chemistry, Andhra University, Visakhapatnam 530 003, India
*
E-mail: drvsomepalli@gmail.com
Received February 15, 2014
DOI 10.1002/jhet.2258
Published online 00 Month 2014 in Wiley Online Library (wileyonlinelibrary.com).
O
O
R1
R2
R1
R2
TFA, CHCl3
rt, 20 min,
90 - 95%
N
N
N
N
R3
R4
N
N
Isomerization
R4
R3
13H-quinazolino[3,4-a]quinazolin-13-ones have been synthesized from 2-aminobenzamides in four steps.
An acid-catalyzed or base-catalyzed isomerization of 13H-quinazolino[3,4-a]quinazolin-13-ones to 8H-
quinazolino[4,3-b]quinazolin-8-ones in excellent yields (90–95%) has been reported. The differences in the
infrared and nuclear magnetic resonance (1H & 13C) data of these isomeric fused quinazolinoquinazolinones
afford a useful method for distinguishing between the two series. These analogs showed moderate anticancer
activity (EGFR-TK inhibition).
J. Heterocyclic Chem., 00, 00 (2014).
INTRODUCTION
published [10] approach and is shown in Scheme 1.
Thus, 2-aminobenzamides were condensed [12] with 2-
nitrobenzaldehydes to give 5, which were reduced to 2-(2-
aminophenyl)-2,3-dihydroquinazolin-4(1H)-ones (4). Selective
cyclization of 4 on to N1-nitrogen via path b with
dimethylformamide-dimethylacetal (DMF-DMA) in toluene/
acetic acid at refluxing temperature gave 11b,12-dihydro-13H-
quinazolino[3,4-a]quinazolin-13-ones (3) in 82–88% yield.
Dehydrogenation of 3 with 1.2 equiv of 2,3-dichloro-5,6-
dicyano-1,4-benzoquinone (DDQ) at room temperature (RT)
for 16 h gave 2 in 83–88% yields. All the structures have been
deduced from their spectroscopic data.
8H-Quinazolino[4,3-b]quinazolin-8-one (1a) and 13H-
quinazolino[3,4-a]quinazolin-13-one (2a) are two isomeric
angularly fused quinazolinoquinazolinones (Fig. 1). There
are number of synthetic methods [2–6] reported in the
literature for 1, but synthetic studies on the isomeric
compounds 2 are limited [7–9]. 13H-Quinazolino[3,4-a]
quinazolin-13-one (2a) is the only compound known in the
6-unsubstituted angularly fused quinazolinone series. In addi-
tion, there are only two reports in the literature [7,8]. Calestani
et al. reported 2a as a minor product with very limited spectro-
scopic data [7], while Marinho et al. synthesized 2a starting
from 2-aminobenzonitrile and triethyl orthoformate [8]. How-
ever, we revised [10] the reported structure of 2a by Marinho
et al. to its isomeric compound 1a. These two isomeric fused
quinazolinones were not evaluated for any of their biological
activities. In view of the importance of quinazolines and its
derivatives as active pharmaceuticals and in continuation of
our interest on this chemistry [10,11], herein, we report (a)
synthesis of 13H-quinazolino[3,4-a]quinazolin-13-ones, (b)
acid-catalyzed or base-catalyzed isomerization, (c) spectro-
scopic identification, and (d) anticancer activity.
(b) Isomerization.
In our previous communication
[11b], the formation of 1a from dihydro derivative 3a
under dehydrogenative condition has been reported. Now,
we have speculated that the dehydrogenation of 3a with
DDQ would afford initially 2a which upon isomerization
to 1a under the experimental conditions (Scheme 2). In
order to unequivocally prove our assumption, 13H-
quinazolino[3,4-a]quinazolin-13-one (2a) was chosen as a
model compound and the results were summarized in
Table 1.
Initially, the compound 2a was treated with solvents
such as CHCl3, CHCl3/CH3OH, and DMSO under heating
conditions. The compound was stable under these condi-
tions (entries 1–3). Surprisingly, with 1.0 equiv of
CF3COOH [trifluoroacetic acid (TFA)], the compound 2a
RESULTS AND DISCUSSION
(a) Synthesis. 13H-Quinazolino[3,4-a]quinazolin-13-
ones (2) were synthesized on the basis of our recently
© 2014 HeteroCorporation

S. Venkateswarlu, M. Satyanarayana, V. Lakshmikanthan, and V. Siddaiah
Vol 000
the isomerization reaction proceeded cleanly and rapidly at
RT and gave 1 in 90–95% yield (Table 2). The products
were characterized by their physical and spectroscopic data.
The tentative mechanism for the acid-catalyzed isomeri-
zation of 2a to 1a was depicted in Scheme 3 (an analogous
base-catalyzed mechanism can also be visualized). For the
acid-catalyzed mechanism, the first step is protonation of
oxygen atom to produce carbonium ion at 11b (6). Then,
transfer of lone pair on the nitrogen to the adjacent bond,
followed by cleavage of N5 & C-6 bond to generate a new
carbonium ion (7). Finally, cyclization of 8 onto nitrogen
and loss of a proton gave the isomerized product 1a. The
isomerization of dihydroderivative 3a to 1a requires
dehydrogenative reagents [11b].
Figure 1. 8H-Quinazolino[4,3-b]quinazolin-8-one (1a) and 13H-
quinazolino[3,4-a]quinazolin-13-one (2a).
was isomerized to compound 1a at RT for 20 min in 91%
yield (entry 4). The reaction was also completed with 0.5
equiv or catalytic amounts of TFA, but with longer
duration (entry 5–6). The structure of 1a has been deduced
from its spectroscopic data and confirmed by comparing
with that described in the literature [3,4]. To explore it
further, two strong acids (HCl and p-TSA) and one weak
acid (acetic acid) were chosen to study the isomerization.
Interestingly, the reaction was completed within 15 min at
RT with HCl and p-TSA (entry 7 and 8) but with acetic
acid, the reaction completed upon heating (entry 10). Like-
wise, as expected, the reaction did not undergo completion
even after refluxing for 6 h with a milder acid, hydroqui-
none (entry 11). Further, the reaction was examined under
basic conditions such as NaHCO3, K2CO3, NaOH, and
(C2H5)3 N. Unexpectedly, treatment of 2a with K2CO3 in
ethanol at RT for 30 min afforded 1a in 86% yield (entry
13). However, the reaction did not undergo completion
either with NaHCO3 or (C2H5)3 N even after heating under
reflux for 4 h (entries 12 and 15). But with NaOH, the
reaction was decomposed (entry 14). Thus, the isomeriza-
tion of 13H-quinazolino[3,4-a]quinazolin-13-one to 8H-
quinazolino[4,3-b]quinazolin-8-one was completed either
in the presence of acid or base. The reason might be due
to the fact that the delocalization of π-electrons from
carbonyl (C-8) to the adjacent carbon-6 via insertion of
two benzene rings allowed the formation of more stable
product 1a.
(c) Spectroscopic identification.
A simple and routine
method for the identification of these isomeric compounds is
desirable for the design and synthesis of analogs. Due to the
lack of such knowledge on these isomeric fused
quinazolines, recently reported [8] product obtained from the
reaction of 2-aminobenzonitrile and triethyl orthoformate
has been misinterpreted to be 2a. We have revised the
falsely reported compound to its isomeric compound 1a
[10]. Therefore, a simple protocol for rapidly distinguishing
between the isomeric compounds 1 and 2 is desirable. The
two series of compounds exhibited marked differences in
both physical and spectroscopic data. The compounds 1
were more soluble in usual organic solvents such as CHCl3
and EtOAc and melts at lower temperatures than the
corresponding 2. It was found that the two compounds can
easily be differentiated by the carbonyl absorption band in
the infrared (IR) spectra with the values 1686–1706 and
1634–1656 cmÀ1, respectively for 1 and 2. Then, the
possibility of differentiating these isomeric compounds using
proton NMR was explored. Even though, the quinazolinones
1 were more soluble in CHCl3 than in DMSO, in order to
compare 1 and 2, all the compounds were recorded in
DMSO-d6. It was found that the H-6 proton (1H-NMR) of 2
always further downfield than the H-6 proton of 1. In all
examples, the value of H-6 proton in 1 was in the range
of δ 9.28–9.32 ppm, and the corresponding proton in 2
was in the range of δ 9.60–9.69 ppm; and the difference
Encouraged by the aforementioned results, the reaction
was tried with various 13H-quinazolino[3,4-a]quinazolin-
13-ones (2) with TFA (1.0 equiv) to check the generality
of the method and for generating isomeric angularly fused
quinazolinoquinazolinones (1) (Scheme 1). In all examples,
Scheme 1. Synthesis and isomerization of 2.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2014
Fused Quinazolinoquinazolinones: Synthesis, Isomerization, Spectroscopic
Identification, and Anticancer Activity
Table 2
Scheme 2. Proposed pathway of 1a from 3a.
Isomerization of 2 to 1.a
Table 1
Entry
13-ones (2)
8-ones (1)
Yield (%)b
Isomerization of 2a.
1
2
3
4
5
6
7
2a
2b
2c
2d
2e
2f
1a
1b
1c
1d
1e
1f
91
95
92
90
90
93
94
Entry
Acid/base
Conditionsa
Yield (1a, %)b
No change
No change
No change
1
2
3
—
—
—
DMSO, 130–140°C,
30 min
CHCl3, reflux,
30 min
CHCl3/CH3OH (1:1),
reflux, 30 min
CHCl3, RT, 20 min
2g
1g
aReaction was carried out with 2 (0.5 mmol), TFA (0.5 mmol), and CHCl3
(20 mL) at RT for 20 min.
4
5
6
7
8
9
10
11
12
13
14
15
TFA
91
90
90
90
80
60c
91
10c
5c
bIsolated yields.
TFA (0.5 equiv) CHCl3, RT, 45 min
TFA (cat)
HCl
p-TSA.H2O
AcOH
AcOH
Hydroquinone
NaHCO3
K2CO3
NaOH
(C2H5)3 N
CHCl3, RT, 16 h
CHCl3, RT, 15 min
CHCl3, RT, 10 min
CHCl3, reflux, 6 h
Dioxane, reflux, 4 h
Dioxane, reflux, 6 h
C2H5OH, reflux, 4 h
C2H5OH, RT, 30 min
Scheme 3. Tentative mechanism of the isomerization.
86
C2H5OH, RT, 30 min Decomposed
Dioxane, reflux, 4 h
4c
aAll the reactions were performed with 2a (0.5 mmol), acid/base
(0.5 mmol), and solvent (20 mL).
bIsolated yields.
cReaction not completed.
was useful to unequivocally assign the structure. It was
also found that the carbonyl carbon (13C-NMR) of 2 was
always further downfield from the corresponding carbon of
1. In all examples, the value of C═O carbon in 1 was in
the range of δ 157.9–158.8 ppm, and the corresponding
carbon in 2 was in the range of δ 164.7–166.1 ppm. This
difference was helpful in unequivocal assignment of the
structure. Hence, these isomeric compounds can easily be
distinguishable from their IR, 1H-NMR, and 13C-NMR data.
Table 3
Epidermal growth factor receptor tyrosine kinase inhibitory activity at 1 μM.
% inhibition
Compound
1
2
a
b
d
e
11.1
4.3
21.8
15.4
20.2
17.1
15.5
5.5
(d) Anticancer activity. The quinazolinone moiety is an
important pharmacophore and possesses epidermal growth
factor receptor (EGFR) tyrosine kinase (TK) inhibitory
effects, useful to inhibit tumor growth [13]. For example,
Iressa® (gefetinib) and Tarceva® (erlotinib) are two
selective EGFR-TK inhibitors approved by the FDA in
2004 for locally advanced or metastatic non-small cell
lung cancer therapy and are currently under evaluation in
clinical trials for other tumor types.
13.9
12.5
84.7
90.1
f
Gefetinib
Erlotinib
Anticancer activity of these compounds was deter-
mined [14] by EGFR-TK inhibition and the results were
shown in Table 3. All the compounds showed low to
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

S. Venkateswarlu, M. Satyanarayana, V. Lakshmikanthan, and V. Siddaiah
Vol 000
allowed to RT and diluted with ice cold water (100 mL). The
precipitated solid was filtered, washed with water, and dried.
The compound was recrystallized from chloroform-methanol to
give the product.
moderate inhibition in comparison with the two commer-
cial drugs (gefetinib and erlotinib). It is interesting to note
that all the 13-one compounds (2) showed good activity in
comparison with the 8-one compounds (1). Introducing
proper constituents on the rings and systematic SAR
studies, these fused quinazolinones might be useful as
anticancer agents.
2,3-Dihydro-2-(2-nitrophenyl)quinazolin-4(1H)-one (5a). Pale
yellow solid (830 mg, 88% yield), mp 182–184°C (literature [10b] mp
190–192°C). IR (KBr) νmax 3409 (NH), 3186 (NHCO), 3071, 1656
(CO), 1609, 1357, 1175, 860 cmÀ1; 1H-NMR (400 MHz, DMSO-d6)
δ 8.21 (1H, br s), 8.07 (1H, d, J= 8.0 Hz), 7.87 (1H, d, J=7.6Hz),
7.79 (1H, t, J=7.4Hz), 7.61–7.68 (2H, m), 7.26 (1H, t, J=7.2Hz),
7.00 (1H, br s), 6.78 (1H, d, J= 8.0 Hz), 6.73 (1H, t, J=7.4Hz), 6.35
(1H, s); 13C-NMR (100 MHz, DMSO-d6) δ 163.3, 147.7, 147.1,
135.9, 133.8, 133.5, 129.8, 128.9, 127.3, 124.6, 117.6, 114.9, 114.5,
62.2; LC-MS (positive ion mode): m/z 270 (M + H)+.
2-(4,5-Dimethoxy-2-nitrophenyl)-2,3-dihydroquinazolin-4(1H)-
one (5b). Off-white solid (920 mg, 80% yield), mp 196–198°C.
IR (KBr) νmax 3393 (NH), 3194 (NHCO), 3077, 1663 (CO), 1612,
1371, 1180, 887 cmÀ1; 1H-NMR (400 MHz, DMSO-d6) δ 8.14 (1H,
s), 7.68 (1H, s), 7.67 (1H, d, J= 8.0 Hz), 7.38 (1H, s), 7.28 (1H, t,
J= 7.6 Hz), 6.92 (1H, br s), 6.81 (1H, d, J= 8.4 Hz), 6.74 (1H, t,
J= 7.4 Hz), 6.40 (1H, s), 3.89 (3H, s), 3.83 (3H, s); 13C-NMR
(100 MHz, DMSO-d6) δ 163.6, 152.8, 148.5, 147.6, 140.3, 133.4,
129.8, 127.3, 117.7, 114.8, 114.7, 110.6, 108.0, 62.5, 56.2, 56.1; LC-
MS (positive ion mode): m/z 330 (M + H)+; HRMS-(EI) (m/z):
(M + Na)+ calcd for C16H15N3O5Na 352.0909, found 352.0908.
2-(4,5-Dimethoxy-2-nitrophenyl)-6,7-dimethoxy-2,3-dihydroquinazolin-
4(1H)-one (5c). Yellow solid (1.21 g, 89% yield), mp 224–226°C. IR
(KBr) νmax 3374 (NH), 3205 (NHCO), 1679 (CO), 1620, 1381, 1068,
872 cmÀ1; 1H-NMR (400 MHz, DMSO-d6) δ 7.95 (1H, s), 7.67 (1H, s),
7.37 (1H, s), 7.15 (1H, s), 6.63 (1H, s), 6.45 (1H, s), 6.32 (1H, s), 3.89
(3H, s), 3.84 (3H, s), 3.73 (3H, s), 3.70 (3H, s); 13C-NMR (100 MHz,
DMSO-d6) δ 163.8, 154.0, 152.7, 148.4, 143.3, 141.9, 140.2, 130.0,
110.6, 109.7, 108.1, 106.4, 98.4, 62.9, 56.2, 56.1, 55.9, 55.4; LC-MS
(positive ion mode): m/z 390 (M + H)+; HRMS-(EI) (m/z): (M + Na)+
calcd for C18H19N3O7Na 412.1121, found 412.1122.
CONCLUSIONS
From this study, three conclusions were drawn: (i) syn-
thesis of 13H-quinazolino[3,4-a]quinazolin-13-ones from
2-aminobenzamides has been achieved in four steps; (ii)
these compounds were isomerized to 8H-quinazolino[4,3-
b]quinazolin-8-ones by acidic or basic reagents under mild
conditions with excellent yields (90–95%). (iii) The two
series of compounds were easily distinguishable from their
IR, 1H-NMR, and 13C-NMR data. The carbonyl absorptions
in IR spectra of 1 are at higher value (1686–1706 cmÀ1) than
1
that of 2 (1634–1656 cmÀ1). The H-6 proton in H-NMR
spectra of 2 appeared at lower field, and the value was higher
than that of 1 (~0.32–0.38 ppm). The carbonyl carbon in 13C-
NMR of 2 was at more downfield (δ 164.7–166.1 ppm) than
that of 1 (δ 157.9–158.8 ppm). The fused quinazolinone
compounds (2) showed good anticancer activity than their
isomeric compounds (1).
EXPERIMENTAL
General.
Reagents and solvents were analytical grade and
were used without further purification. Melting points were
determined on a microscopic apparatus and were uncorrected.
Analytical thin layer chromatography (TLC) was performed using
precoated silica gel plate and column chromatography was
carried out on silica gel. IR spectra were recorded on a Fourier
6-Chloro-2-(2-nitrophenyl)-2,3-dihydroquinazolin-4(1H)-one
(5d). Yellow solid (914 mg, 86% yield), mp 210–212°C (literature
[15] mp 200–202°C). IR (KBr) νmax 3414 (NH), 3185 (NHCO),
3068, 1664 (CO), 1612, 1344, 1174, 857 cmÀ1 1H-NMR
;
(400 MHz, DMSO-d6) δ 8.39 (1H, br s), 8.08 (1H, d, J = 8.4 Hz),
7.78–7.85 (2H, m), 7.65 (1H, t, J = 7.0 Hz), 7.59 (1H, br s), 7.30
(1H, dd, J = 8.6, 2.2 Hz), 7.23 (1H, s), 6.81 (1H, d, J = 8.8 Hz),
6.37 (1H, s); 13C-NMR (100 MHz, DMSO-d6) δ 162.1, 147.6,
145.8, 135.6, 134.0, 133.3, 130.0, 128.9, 126.3, 124.7, 121.3,
116.9, 115.5, 62.1; LC-MS (positive ion mode): m/z 304, 306
(M + H)+.
transform infrared spectrometer and peaks are reported in cmÀ1
.
1H-NMR spectra were recorded on 400MHz in DMSO-d6, and
13C-NMR spectra were recorded on 100 MHz in CDCl3 or
DMSO-d6. Chemical shifts (ppm) were recorded with
tetramethylsilane (TMS) as the internal reference standard.
Multiplicities are given as: s (singlet), br s (broad singlet), d
(doublet), t (triplet), dd (doublet of doublets), q (quartet), or m
(multiplet). The number of protons (n) for a given resonance is
indicated by nH, and coupling constants are reported as a J
value in hertz. Mass spectra was recorded on a liquid
chromatography–mass spectrometry (LC-MS) instrument. The
atomic composition of all the new products was established by
their HRMS values. HPLC was recorded under the following
conditions: For 1a–g; column, Phenomenex Luma C18;
flow rate, 1 mL/min; detection at 254 nm and mobile phase,
water: acetonitrile (30:70). For 2a–g; column, Waters,
acquityUPLCBEH C18; flow rate, 0.5 mL/min; detection
at 275 nm and mobile phase, 10 mM ammonium acetate:
acetonitrile (80:20).
6-Bromo-2-(2-nitrophenyl)-2,3-dihydroquinazolin-4(1H)-one
(5e). Yellow solid (1.01 g, 83% yield), mp 222–226°C. IR (KBr)
νmax 3415 (NH), 3183 (NHCO), 3068, 1664 (CO), 1606, 1342,
1
1173, 857 cmÀ1; H-NMR (400 MHz, DMSO-d6) δ 8.39 (1H, br
s), 8.08 (1H, d, J = 8.0 Hz), 7.78–7.88 (2H, m), 7.72 (1H, br s),
7.65 (1H, t, J = 7.4 Hz), 7.41 (1H, dd, J = 8.8, 2.0 Hz), 7.26 (1H,
s), 6.76 (1H, d, J = 8.4 Hz), 6.37 (1H, s); 13C-NMR (100 MHz,
DMSO-d6) δ 162.0, 147.6, 146.1, 136.0, 135.6, 134.0, 130.0,
129.3, 128.8, 124.7, 117.2, 116.0, 108.5, 62.1; LC-MS (positive
ion mode): m/z 370, 372 (M + Na)+; HRMS-(EI) (m/z):
(M + Na)+ calcd for C14H10BrN3O3Na 369.9803, found 369.9801.
6-Chloro-2-(4,5-dimethoxy-2-nitrophenyl)-2,3-dihydroquinazolin-
4(1H)-one (5f). Pale yellow solid (1.04 g, 82% yield), mp 210–212°C.
IR (KBr) νmax 3378 (NH), 3192 (NHCO), 3076, 1666 (CO), 1613, 1324,
1177, 819 cmÀ1; 1H-NMR (400 MHz, DMSO-d6) δ 8.35 (1H, s), 7.68
(1H, s), 7.60 (1H, d, J= 2.0 Hz), 7.34 (1H, s), 7.32 (1H, dd, J=8.8,
General procedure for 5. A mixture of 2-aminobenzamide
(3.50 mmol), 2-nitrobenzaldehyde (4.55 mmol), and water:AcOH
(7.5 mL:2.5 mL) was refluxed for 5 h. The reaction mixture was
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2014
Fused Quinazolinoquinazolinones: Synthesis, Isomerization, Spectroscopic
Identification, and Anticancer Activity
2.4 Hz), 7.16 (1H, s), 6.85 (1H, d, J= 8.4 Hz), 6.42 (1H, s), 3.89 (3H, s),
3.85 (3H, s); 13C-NMR (100 MHz, DMSO-d6) δ 162.5, 152.8, 148.6,
146.4, 140.3, 133.2, 129.4, 126.3, 121.3, 116.8, 115.8, 110.5, 108.1,
62.4, 56.3, 56.1; LC-MS (positive ion mode): m/z 364, 366 (M + H)+;
HRMS-(EI) (m/z): (M + Na)+ calcd for C16H14ClN3O5Na 386.0520,
found 386.0525.
6-Bromo-2-(4,5-dimethoxy-2-nitrophenyl)-2,3-dihydroquinazolin-
4(1H)-one (5g). Pale yellow solid (1.16 g, 81% yield), mp 238–240°
C. IR (KBr) νmax 3382 (NH), 3192 (NHCO), 3073, 1660 (CO), 1608,
1323, 1176, 878 cmÀ1; 1H-NMR (400 MHz, DMSO-d6) δ 8.33 (1H,
s), 7.73 (1H, d, J= 2.0 Hz), 7.68 (1H, s), 7.42 (1H, dd, J=8.4,
2.4 Hz), 7.34 (1H, s), 7.17 (1H, s), 6.79 (1H, d, J= 8.8 Hz), 6.42 (1H,
s), 3.89 (3H, s), 3.85 (3H, s); 13C-NMR (100 MHz, DMSO-d6) δ
162.3, 152.8, 148.6, 146.7, 140.3, 135.9, 129.4, 129.3, 117.2, 116.2,
110.5, 108.5, 108.1, 62.4, 56.3, 56.2; LC-MS (positive ion mode):
m/z 408, 410 (M + H)+; HRMS-(EI) (m/z): (M + H)+ calcd for
C16H14BrN3O5H 408.0195, found 408.0197.
IR (KBr) νmax 3384 (NH), 3183 (NHCO), 3078, 1677 (CO), 1612,
1366, 1160, 852 cmÀ1; 1H-NMR (400 MHz, DMSO-d6) δ 8.12 (1H,
br s), 7.57 (1H, d, J= 2.0 Hz), 7.29 (1H, dd, J= 8.4, 2.4 Hz), 7.20
(1H, d, J= 7.6 Hz), 7.05–7.09 (2H, m), 6.81 (1H, d, J=8.4Hz), 6.71
(1H, d, J= 7.6 Hz), 6.57 (1H, t, J= 7.4 Hz), 5.88 (1H, s), 5.24 (2H,
br s); 13C-NMR (100 MHz, DMSO-d6) δ 163.3, 147.6, 146.6,
132.8, 129.3, 128.5, 126.5, 121.8, 120.9, 116.6, 116.4, 116.0, 115.8,
64.7; LC-MS (positive ion mode): m/z 274, 276 (M + H)+; HRMS-
(EI) (m/z): (M + Na)+ calcd for C14H12ClN3ONa 296.0567, found
296.0569.
2-(2-Aminophenyl)-6-bromo-2,3-dihydroquinazolin-4(1H)-one
(4e). Off-white solid (430 mg, 90% yield), mp 212–214°C. IR
(KBr) νmax 3455 (NH), 3367, 3314, 3178 (NHCO), 1657 (CO),
1
1605, 1362, 1159, 817 cmÀ1; H-NMR (400 MHz, DMSO-d6) δ
8.10 (1H, br s), 7.70 (1H, d, J = 1.6 Hz), 7.40 (1H, dd, J =8.8,
2.0Hz), 7.20 (1H, d, J= 7.6 Hz), 7.04–7.07 (2H, m), 6.76 (1H, d,
J = 8.8 Hz), 6.71 (1H, d, J= 8.0Hz), 6.57 (1H, t, J= 7.4 Hz), 5.88
(1H, s), 5.23 (2H, br s); 13C-NMR (100MHz, DMSO-d6) δ
163.2, 147.9, 146.6, 135.5, 129.4, 129.3, 128.5, 121.9, 117.0,
116.8, 116.0, 115.8, 108.1, 64.7; LC-MS (positive ion mode): m/z
340, 342 (M + Na)+; HRMS-(EI) (m/z): (M + H)+ calcd for
C14H12BrN3OH 318.0242, found 318.0240.
General procedure for 4. To a solution of 5 (1.5 mmol) in
a mixture of water (0.8 mL) and methanol (6.6 mL) was added
conc. hydrochloric acid (0.2 mL). To the previous solution was
added iron powder (7.6 mmol) followed by ammonium chloride
(7.6 mmol) at RT. The reaction mixture was refluxed for 0.5 h
and was then allowed to cool to RT. The solution was poured
into ice cold water (50 mL) and basified with 10% aq sodium
bicarbonate. The precipitated solid was filtered, and the filter
cake was extracted with hot methanol-chloroform (1:1). The
combined organic solvent was filtered to remove iron particles,
and solvent was evaporated to give the amino compound.
2-(2-Aminophenyl)-2,3-dihydroquinazolin-4(1H)-one (4a). Pale
yellow solid (308 mg, 86% yield), mp 174–176°C (literature [12f]
mp 170–173°C). IR (KBr) νmax 3453 (NH), 3364, 3303, 3197
2-(2-Amino-4,5-dimethoxyphenyl)-6-chloro-2,3-dihydroquinazolin-
4(1H)-one (4f). Off-white solid (460 mg, 92% yield), mp 226–228°C.
IR (KBr) νmax 3465 (NH), 3373, 3322, 1679 (CO), 1612, 1349, 1135,
842 cmÀ1 1H-NMR (400 MHz, DMSO-d6) δ 8.02 (1H, s), 7.57
;
(1H, s), 7.29 (1H, d, J= 8.0 Hz), 6.97 (1H, s), 6.87 (1H, s), 6.82 (1H,
d, J= 8.8 Hz), 6.39 (1H, s), 5.85 (1H, s), 4.89 (2H, br s), 3.70
(3H, s), 3.62 (3H, s); 13C-NMR (100 MHz, DMSO-d6) δ 163.4,
150.5, 147.8, 141.4, 140.0, 132.7, 126.5, 120.9, 116.6, 116.5,
114.3, 113.1, 101.3, 64.1, 56.7, 55.4; LC-MS (positive ion mode):
m/z 356, 358 (M + Na)+; HRMS-(EI) (m/z): (M+ H)+ calcd for
C16H16ClN3O3H 334.0955, found 334.0958.
(NHCO), 1655 (CO), 1613, 1380, 1158, 822 cmÀ1 1H-NMR
;
(400 MHz, DMSO-d6) δ 7.91 (1H, br s), 7.66 (1H, dd, J = 7.8,
0.5 Hz), 7.26 (1H, td, J = 7.6, 1.6 Hz), 7.22 (1H, dd, J = 7.6,
1.2 Hz), 7.07 (1H, td, J = 7.6, 1.2 Hz), 6.84 (1H, br s), 6.79
(1H, d, J = 8.4 Hz), 6.70–6.74 (2H, m), 6.57 (1H, td, J = 7.4,
0.8 Hz), 5.86 (1H, s), 5.25 (2H, br s); 13C-NMR (100 MHz,
DMSO-d6) δ 164.5, 148.8, 146.5, 133.0, 129.2, 128.6, 127.4,
122.2, 117.3, 116.0, 115.8, 115.3, 114.7, 65.1; LC-MS
(positive ion mode): m/z 262 (M + Na)+.
2-(2-Amino-4,5-dimethoxyphenyl)-6-bromo-2,3-dihydroquinazolin-
4(1H)-one (4g). Pale yellow solid (490 mg, 86% yield), mp 248–250°
C. IR (KBr) νmax 3464 (NH), 3372, 3327, 1677 (CO), 1605, 1350, 1136,
840 cmÀ1; 1H-NMR (400 MHz, DMSO-d6) δ 7.99 (1H, s), 7.70 (1H, s),
7.40 (1H, d, J= 7.2 Hz), 6.98 (1H, s), 6.87 (1H, s), 6.77 (1H, d,
J= 8.8 Hz), 6.39 (1H, s), 5.84 (1H, s), 4.88 (2H, br s), 3.70 (3H, s), 3.62
(3H, s); 13C-NMR (100 MHz, DMSO-d6) δ 163.3, 150.5, 148.1, 141.4,
140.1, 135.4, 129.4, 117.0, 116.9, 114.3, 113.1, 108.1, 101.3, 64.1, 56.7,
55.4; LC-MS (negative ion mode): m/z 376, 378 (M–H)À; HRMS-(EI)
(m/z): (M + H)+ calcd for C16H16BrN3O3H 378.0453, found 378.0450.
General procedure for 3. To a suspension of 4 (3.0 mmol)
in toluene (20mL) was added successively DMF-DMA (0.8 mL,
6.0 mmol) and acetic acid (0.16 mL, 3.0 mmol) at RT and
refluxed for 2 h. The reaction mixture was allowed to RT, and the
precipitated product was filtered, washed with toluene, and dried.
The crude product was recrystallized from excess of chloroform-
methanol to give 13-one compound (3).
2-(2-Amino-4,5-dimethoxyphenyl)-2,3-dihydroquinazolin-4
(1H)-one (4b). Off-white solid (380 mg, 85% yield), mp 182–184°C.
IR (KBr) νmax 3463 (NH), 3312, 3192 (NHCO), 1650 (CO), 1612, 1382,
1
1138, 854 cmÀ1; H-NMR (400 MHz, DMSO-d6) δ 7.80 (1H, s), 7.64
(1H, d, J= 7.6 Hz), 7.25 (1H, t, J= 7.6 Hz), 6.89 (1H, s), 6.79 (1H, d,
J=8.0Hz), 6.69–6.73 (2H, m), 6.39 (1H, s), 5.82 (1H, s), 4.89 (2H, br
s), 3.69 (3H, s), 3.61 (3H, s); 13C-NMR (100 MHz, DMSO-d6) δ 164.6,
150.3, 149.0, 141.3, 140.0, 133.0, 127.4, 117.3, 115.3, 114.7, 114.4,
113.6, 101.3, 64.4, 56.7, 55.4; LC-MS (positive ion mode): m/z 300
(M + H)+. HRMS-(EI) (m/z): (M + H)+ calcd for C16H17N3O3H
300.1348, found 300.1345.
2-(2-Amino-4,5-dimethoxyphenyl)-6,7-dimethoxy-2,3-dihydroquinazolin-
4(1H)-one (4c). Pale yellow solid (490 mg, 91% yield), mp 216–218°C. IR
(KBr) νmax 3458 (NH), 3315, 1648 (CO), 1618, 1136, 832 cmÀ1; 1H-NMR
(400 MHz, DMSO-d6) δ 7.56 (1H, s), 7.15 (1H, s), 6.89 (1H, s), 6.43 (3H, br
s), 5.75 (1H, s), 4.88 (2H, s), 3.70 (9H, s), 3.63 (3H, s); 13C-NMR (100 MHz,
DMSO-d6) δ 164.7, 153.7, 150.3, 144.8, 141.7, 141.4, 139.9, 114.5, 113.7,
110.2, 107.1, 101.3, 98.4, 65.1, 56.7, 56.0, 55.4, 55.3; LC-MS (positive ion
mode): m/z 360 (M + H)+; HRMS-(EI) (m/z): (M + H)+ calcd for
C18H21N3O5H 360.1559, found 360.1558.
11b,12-Dihydro-13H-quinazolino[3,4-a]quinazolin-13-one (3a).White
solid (615 mg, 82% yield), mp 296–302°C. IR (KBr) νmax
3162 (NHCO), 1686 (CO), 1620, 1603, 1356, 1181,
746 cmÀ1 1H-NMR (400 MHz, DMSO-d6) δ 8.76 (1H, s,
;
exchangeable with D2O), 7.98 (1H, d, J = 7.6 Hz), 7.78 (1H,
s), 7.69 (1H, t, J = 7.8 Hz), 7.64 (1H, d, J = 7.6 Hz), 7.36–7.41
(3H, m), 7.25 (1H, t, J = 7.4 Hz), 7.20 (1H, d, J = 8.0 Hz), 6.50
(1H, s); 13C-NMR (100 MHz, DMSO-d6) δ 162.0, 143.6,
140.8, 139.8, 133.5, 129.9, 128.1, 127.6, 125.8, 125.2, 125.1,
123.1, 118.5, 118.2, 62.0; LC-MS (positive ion mode): m/z
2-(2-Aminophenyl)-6-chloro-2,3-dihydroquinazolin-4(1H)-
one (4d). Off-white solid (370 mg, 90% yield), mp 182–184°C.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

S. Venkateswarlu, M. Satyanarayana, V. Lakshmikanthan, and V. Siddaiah
Vol 000
250 (M + H)+; HRMS-(EI) (m/z): (M + H)+ calcd for
C15H11N3OH 250.0980, found 250.0977.
General procedure for the dehydrogenation of 3. To an
ice cold suspension of 3 (0.50 mmol) in dioxane (20 mL) was
added DDQ (136 mg, 0.60 mmol) and stirred at RT for 16 h.
The reaction mixture was filtered and washed with dioxane to
remove excess reagent. The residue was suspended in 0.1%
aqueous sodium bicarbonate (100 mL) and sonicated for 15 min.
The solid was filtered, washed with water (20 mL), and dried to
give the product. The product was further recrystallized from
excess of chloroform-methanol (1:1).
11b,12-Dihydro-9,10-dimethoxy-13H-quinazolino[3,4-a]quinazolin-
13-one (3b). White solid (788mg, 85% yield), mp 306–308°C. IR
(KBr) νmax 3158 (NHCO), 3039, 1685 (CO), 1626, 1608, 1353,
1
1117, 854 cmÀ1; H-NMR (400 MHz, DMSO-d6) δ 8.73 (1H, s),
7.98 (1H, d, J = 7.6 Hz), 7.72 (1H, s), 7.62–7.69 (2H, m), 7.37
(1H, t, J = 7.8Hz), 6.96 (1H, s), 6.78 (1H, s), 6.43 (1H, s), 3.81
(3H, s), 3.80 (3H, s); 13C-NMR (100MHz, DMSO-d6) δ 162.2,
149.7, 146.8, 141.8, 140.9, 133.5, 128.1, 124.9, 122.6, 118.0,
110.3, 109.9, 108.6, 62.2, 55.7, 55.6; LC-MS (positive ion mode):
m/z 310 (M + H)+; HRMS-(EI) (m/z): (M+ Na)+ calcd for
C17H15N3O3Na 332.1011, found 332.1018.
13H-Quinazolino[3,4-a]quinazolin-13-one (2a).
Pale yellow
solid (105 mg, 85% yield), mp >300°C. IR (KBr) νmax 1656 (CO),
1601, 1352, 1120, 910 cmÀ1; 1H-NMR (400 MHz, DMSO-d6) δ 9.67
(1H, s), 8.70 (1H, d, J= 7.6 Hz), 8.65 (1H, d, J= 8.8 Hz), 8.29 (1H, d,
J= 7.6 Hz), 7.99 (2H, t, J= 7.4 Hz), 7.88 (1H, d, J= 8.0 Hz), 7.77 (1H,
t, J= 7.2 Hz), 7.75 (1H, t, J=7.2Hz); 13C-NMR (100 MHz, DMSO-
d6) δ 166.1, 150.7, 143.9, 139.3, 136.8, 134.9, 133.9, 128.8, 128.2,
127.7, 127.4, 126.4, 120.5, 120.4, 115.8; LC-MS (positive ion mode):
m/z 248 (M + H)+; HRMS-(EI) (m/z): (M + Na)+ calcd for
C15H9N3ONa 270.0643, found 270.0645; HPLC: 99.9%.
2,3,9,10-Tetramethoxy-11b,12-dihydro-13H-quinazolino[3,4-a]
quinazolin-13-one (3c).
Off-white solid (952 mg, 86% yield),
mp >300°C. IR (KBr) νmax 3209 (NHCO), 1677 (CO), 1627,
1
1613, 1350, 1117, 860 cmÀ1; H-NMR (400 MHz, DMSO-d6) δ
8.48 (1H, s, exchangeable with D2O), 7.75 (1H, s), 7.41 (1H, s),
7.22 (1H, s), 6.95 (1H, s), 6.78 (1H, s), 6.35 (1H, s), 3.92 (3H, s),
3.82 (3H, s), 3.81 (3H, s), 3.80 (3H, s); 13C-NMR (100 MHz,
DMSO-d6) δ 162.1, 153.3, 149.6, 146.8, 146.5, 142.3, 135.6,
133.7, 114.5, 110.2, 110.0, 109.5, 108.6, 101.7, 62.5, 56.2, 55.8,
557, 55.6; LC-MS (positive ion mode): m/z 370 (M+ H)+;
HRMS-(EI) (m/z): (M + H)+ calcd for C19H19N3O5H 370.1403,
found 370.1400.
2-Chloro-11b,12-dihydro-13H-quinazolino[3,4-a]quinazolin-
13-one (3d). White solid (745 mg, 88% yield), mp >300°C. IR
(KBr) νmax 3158 (NHCO), 3049, 1689 (CO), 1619, 1604, 1386,
1179, 833 cmÀ1; 1H-NMR (400 MHz, DMSO-d6) δ 8.96 (1H, s,
exchangeable with D2O), 7.91 (1H, s), 7.70–7.77 (3H, m),
7.35–7.42 (2H, m), 7.26 (1H, t, J = 8.0 Hz), 7.21 (1H, d,
J = 7.2 Hz), 6.51 (1H, s); LC-MS (positive ion mode): m/z 284,
286 (M + H)+; HRMS-(EI) (m/z): (M + H)+ calcd for,
C15H10ClN3OH 284.0591, found 284.0596.
9,10-Dimethoxy-13H-quinazolino[3,4-a]quinazolin-13-
one (2b). Off-white solid (135mg, 88% yield), mp >300°C. IR
(KBr) νmax 1643 (CO), 1599, 1347, 1141, 869cmÀ1 1H-NMR
;
(400 MHz, DMSO-d6) δ 9.62 (1H, s), 8.63 (1H, d, J = 8.8 Hz),
8.27 (1H, d, J = 7.6 Hz), 8.00 (1H, s), 7.95 (1H, t, J = 7.4 Hz),
7.72 (1H, t, J = 7.6 Hz), 7.37 (1H, s), 4.00 (3H, s), 3.99 (3H, s);
13C-NMR (100MHz, DMSO-d6) δ 165.8, 155.4, 150.0, 149.9,
140.6, 137.9, 136.8, 133.8, 128.1, 127.7, 120.5, 115.8, 113.5,
108.3, 105.4, 56.3, 56.0; LC-MS (positive ion mode): m/z 308
(M+ H)+; HRMS-(EI) (m/z): (M+ Na)+ calcd for C17H13N3O3Na
330.0855, found 330.0856; HPLC: 99.8%.
2,3,9,10-Tetramethoxy-13H-quinazolino[3,4-a]quinazolin-
13-one (2c).
Off-white solid (155 mg, 84%), mp >300°C. IR
(KBr) νmax 1634 (CO), 1604, 1390, 1086, 884 cmÀ1
;
1H-NMR
(400 MHz, DMSO-d6) δ 9.69 (1H, s), 8.02 (1H, s), 8.01 (1H, s),
7.64 (1H, s), 7.38 (1H, s), 4.06 (3H, s), 4.01 (3H, s), 4.00 (3H, s),
3.94 (3H, s); LC-MS (positive ion mode): m/z 368 (M + H)+;
HRMS-(EI) (m/z): (M + H)+ calcd for C19H17N3O5H 368.1246,
found 368.1244; HPLC: 99.3%.
2-Bromo-11b,12-dihydro-13H-quinazolino[3,4-a]quinazolin-13-
one (3e). Off-white solid (825 mg, 84% yield), mp >300°C. IR
(KBr) νmax 3157 (NHCO), 3047, 1686 (CO), 1621, 1604, 1385,
1180, 836 cmÀ1 1H-NMR (400 MHz, DMSO-d6) δ 8.93 (1H, s,
;
exchangeable with D2O), 8.04 (1H, d, J= 2.0 Hz), 7.87 (1H, dd,
J= 8.8, 2.0 Hz), 7.77 (1H, s), 7.65 (1H, d, J= 8.4 Hz), 7.41 (1H, t,
J= 8.0 Hz), 7.37 (1H, d, J= 8.8 Hz), 7.26 (1H, t, J= 7.6 Hz), 7.21
(1H, d, J= 8.0 Hz), 6.51 (1H, s); LC-MS (positive ion mode): m/z
328, 330 (M + H)+; HRMS-(EI) (m/z): (M + H)+ calcd for,
C15H10BrN3OH 328.0085, found 328.0082.
2-Chloro-13H-quinazolino[3,4-a]quinazolin-13-one (2d). Pale
pink solid (120 mg, 85%), mp >300°C. IR (KBr) νmax 1655 (CO),
1617, 1340, 1126, 822 cmÀ1 1H-NMR (400 MHz, DMSO-d6) δ
;
9.66 (1H, s), 8.71 (1H, d, J= 8.8 Hz), 8.69 (1H, d, J=7.6Hz), 8.21
(1H, br s), 8.06 (1H, d, J= 8.8 Hz), 8.00 (1H, t, J= 7.2 Hz), 7.89 (1H,
d, J= 8.0 Hz), 7.78 (1H, t, J=7.2Hz); 13C-NMR (100 MHz, DMSO-
d6) δ 165.0, 150.9, 143.9, 139.2, 135.8, 135.2, 133.7, 132.9, 128.9,
127.4, 126.6, 126.5, 121.8, 120.3, 118.6; LC-MS (positive ion
mode): m/z 282, 284 (M + H)+; HRMS-(EI) (m/z): (M + Na)+ calcd
for C15H8ClN3ONa 304.0254, found 304.0257; HPLC: 99.6%.
2-Bromo-13H-quinazolino[3,4-a]quinazolin-13-one (2e). Off-
white solid (135 mg, 83% yield), mp >300°C. IR (KBr) νmax
2-Chloro-9,10-dimethoxy-11b,12-dihydro-13H-quinazolino[3,4-a]
quinazolin-13-one (3f). Off-white solid (896 mg, 87% yield), mp
306–308°C. IR (KBr) νmax 3161 (NHCO), 3023, 1683 (CO), 1635,
1611, 1355, 1193, 830 cmÀ1 1H-NMR (400 MHz, DMSO-d6) δ
;
8.88 (1H, s), 7.91 (1H, s), 7.72 (3H, br s), 6.96 (1H, s), 6.79 (1H, s),
6.43 (1H, s), 3.81 (3H, s), 3.80 (3H, s); LC-MS (positive ion mode):
m/z 344, 346 (M + H)+; HRMS-(EI) (m/z): (M + H)+ calcd for,
C17H14ClN3O3H 344.0802, found 344.0807.
1655 (CO), 1618, 1339, 1180, 821 cmÀ1 1H-NMR (400 MHz,
;
DMSO-d6) δ 9.65 (1H, s), 8.68 (1H, d, J = 8.0 Hz), 8.63 (1H, d,
J = 8.8Hz), 8.34 (1H, d, J = 1.2 Hz), 8.17 (1H, dd, J = 8.8, 2.4Hz),
8.00 (1H, t, J = 7.4 Hz), 7.89 (1H, d, J = 8.0 Hz), 7.77 (1H, t,
J = 7.6Hz); 13C-NMR (100MHz, DMSO-d6) δ 164.9, 150.9,
143.9, 139.2, 136.5, 136.1, 135.1, 129.7, 128.9, 127.4, 126.5,
122.0, 121.1, 120.3, 118.7; LC-MS (positive ion mode): m/z 326,
328 (M+ H)+; HRMS-(EI) (m/z): (M+ H)+ calcd for
C15H8BrN3OH 325.9929, found 325.9926; HPLC: 99.6%.
2-Bromo-9,10-dimethoxy-11b,12-dihydro-13H-quinazolino
[3,4-a]quinazolin-13-one (3g).
White solid (966 mg, 83%
yield), mp 324–326°C. IR (KBr) νmax 3161 (NHCO), 1685 (CO),
1636, 1610, 1355, 1120, 853 cmÀ1; 1H-NMR (400 MHz, DMSO-d6)
δ 8.88 (1H, s, exchangeable with D2O), 8.04 (1H, d, J=1.2Hz),
7.85 (1H, dd, J= 8.6, 1.6 Hz), 7.72 (1H, s), 7.65 (1H, d, J=8.4Hz),
6.95 (1H, s), 6.79 (1H, s), 6.43 (1H, s), 3.81 (3H, s), 3.80 (3H, s);
LC-MS (positive ion mode): m/z 388, 390 (M + H)+; HRMS-(EI)
(m/z): (M + H)+ calcd for, C17H14BrN3O3H 388.0297, found
388.0293.
2-Chloro-9,10-dimethoxy-13H-quinazolino[3,4-a]quinazolin-
13-one (2f). Off-white solid (145 mg, 85% yield), mp >300°
1
C. IR (KBr) νmax 1643 (CO), 1594, 1301, 1142, 874 cmÀ1; H-
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2014
Fused Quinazolinoquinazolinones: Synthesis, Isomerization, Spectroscopic
Identification, and Anticancer Activity
(400 MHz, DMSO-d6) δ 9.32 (1H, s), 8.76 (1H, d, J = 8.0), 8.29
(1H, d, J = 1.6 Hz), 8.02 (1H, dd, J = 8.8, 2.0 Hz), 7.86–7.97
(3H, m), 7.77 (1H, t, J = 7.4 Hz); 13C-NMR (100 MHz, DMSO-
d6) δ 158.0, 146.0, 145.0, 143.0, 138.0, 136.0, 134.1, 130.6,
129.6, 129.0, 127.8, 125.8, 125.5, 121.1, 120.0; LC-MS
(positive ion mode): m/z 282, 284 (M + H)+; HRMS-(EI) (m/z):
(M + H)+ calcd for C15H8ClN3OH 282.0434, found 282.0435;
HPLC: 99.8%.
NMR (400 MHz, DMSO-d6) δ 9.61 (1H, s), 8.69 (1H, d,
J = 9.2 Hz), 8.20 (1H, d, J = 2.4 Hz), 8.02 (1H, dd, J = 9.4,
2.6 Hz), 7.99 (1H, s), 7.39 (1H, s), 4.01 (3H, s), 4.00 (3H, s);
13C-NMR (100 MHz, DMSO-d6) δ 164.7, 150.1, 150.0, 140.6,
137.8, 137.7, 137.6, 133.5, 132.7, 126.6, 121.8, 118.5, 113.4,
108.3, 105.4, 56.4, 56.0; LC-MS (positive ion mode): m/z 342,
344 (M + H)+; HRMS-(EI) (m/z): (M + Na)+ calcd for
C17H12ClN3O3Na 364.0465, found 364.0466; HPLC: 99.5%.
2-Bromo-9,10-dimethoxy-13H-quinazolino[3,4-a]quinazolin-
13-one (2g). Off-white solid (165 mg, 86% yield), mp >300°C.
IR (KBr) νmax 1642 (CO), 1595, 1301, 1139, 874 cmÀ1; 1H-NMR
(400 MHz, DMSO-d6) δ 9.60 (1H, s), 8.62 (1H, d, J = 9.2 Hz),
8.34 (1H, d, J = 2.0 Hz), 8.14 (1H, dd, J = 9.0, 2.2 Hz), 7.99 (1H,
s), 7.39 (1H, s), 4.01 (3H, s), 3.99 (3H, s); LC-MS (positive ion
mode): m/z 386, 388 (M + H)+; HRMS-(EI) (m/z): (M + Na)+
calcd for C17H12BrN3O3Na 407.9960, found 407.9960; HPLC:
98.2%.
General procedure for the isomerization of 2. To an ice
cold suspension of 2 (0.50 mmol) in chloroform (20 mL) was
added TFA (0.037 mL, 0.50 mmol) and stirred at RT for
20 min. After completion, the reaction mixture was poured
into ice cold water and stirred for 5 min. The solution was
extracted with chloroform (3 × 50 mL), and the combined
chloroform layer was washed with water, brine, and dried
over sodium sulfate. The solution was filtered and evaporated
the solvent. The residue was chromatographed over silica gel
column using hexane-chloroform (1:1) as eluent to give the
product.
10-Bromo-8H-quinazolino[4,3-b]quinazolin-8-one (1e).
Off-white solid (146 mg, 90% yield), mp 232–234°C (literature [3]
mp 229°C). IR (KBr) νmax 1702 (CO), 1625, 1381, 1118,
828 cmÀ1 1H-NMR (400 MHz, DMSO-d6) δ 9.32 (1H, s), 8.76
;
(1H, d, J= 8.0), 8.42 (1H, d, J= 1.2 Hz), 8.12 (1H, dd, J=8.8,
2.0 Hz), 7.95 (1H, t, J= 7.4 Hz), 7.87 (1H, d, J= 8.0 Hz), 7.82 (1H,
d, J= 8.8 Hz), 7.77 (1H, t, J=7.4Hz); 13C-NMR (100 MHz,
DMSO-d6) δ 157.9, 146.2, 145.0, 143.0, 138.7, 138.0, 134.1,
129.7, 129.1, 128.9, 127.8, 125.5, 121.1, 120.4, 118.6; LC-MS
(positive ion mode): m/z 326, 328 (M + H)+; HPLC: 99.7%.
10-Chloro-2,3-dimethoxy-8H-quinazolino[4,3-b]quinazolin-
8-one (1f). Pale yellow solid (160 mg, 93% yield), mp 272–
274°C. IR (KBr) νmax 1701 (CO), 1624, 1124, 986 cmÀ1 1H-
;
NMR (400 MHz, DMSO-d6) δ 9.29 (1H, s), 8.25 (1H, d,
J = 2.0 Hz), 8.08 (1H, s), 7.97 (1H, dd, J = 8.8, 2.4 Hz), 7.86
(1H, d, J = 8.8 Hz), 7.39 (1H, s), 4.01 (3H, s), 3.99 (3H, s); 13C-
NMR (100 MHz, CDCl3) δ 158.4, 154.6, 150.5, 146.6, 144.4,
139.3, 136.3, 136.1, 131.5, 128.9, 126.6, 118.9, 114.6, 109.0,
105.3, 56.5, 56.4; LC-MS (positive ion mode): m/z 342, 344
(M + H)+;
HRMS-(EI)
(m/z):
(M + Na)+
calcd
for
C17H12ClN3O3Na 364.0465, found 364.0470; HPLC: 99.7%.
8H-Quinazolino[4,3-b]quinazolin-8-one (1a). Pale yellow
solid (112 mg, 91% yield), mp 190–192°C (literature [4] mp
194–196°C). IR (KBr) νmax 1705 (CO), 1625, 1379, 1136,
10-Bromo-2,3-dimethoxy-8H-quinazolino[4,3-b]quinazolin-
8-one (1g). Off-white solid (180 mg, 94% yield), mp 264–266°
1
C. IR (KBr) νmax 1706 (CO), 1625, 1395, 1110, 848 cmÀ1; H-
1
878 cmÀ1; H-NMR (400 MHz, DMSO-d6) δ 9.31 (1H, s), 8.75
NMR (400 MHz, DMSO-d6) δ 9.28 (1H, s), 8.37 (1H, d,
J = 1.6 Hz), 8.06–8.08 (2H, m), 7.77 (1H, d, J = 8.8 Hz), 7.38
(1H, s), 4.00 (3H, s), 3.98 (3H, s); 13C-NMR (100 MHz,
CDCl3) δ 158.2, 154.7, 150.5, 146.9, 144.5, 139.4, 138.8,
136.3, 129.8, 129.1, 119.3, 119.0, 114.6, 109.0, 105.3, 56.5,
56.4; LC-MS (positive ion mode): m/z 386, 388 (M + H)+;
HRMS-(EI) (m/z): (M + H)+ calcd for C17H12BrN3O3H
386.0140, found 386.0144; HPLC: 99.7%.
(1H, d, J = 7.6 Hz), 8.34 (1H, d, J = 8.0 Hz), 7.99 (1H, t,
J = 7.6 Hz), 7.92 (1H, t, J = 7.6 Hz), 7.84–7.87 (2H, m), 7.75
(1H, t, J = 7.4 Hz), 7.62 (1H, t, J = 7.6 Hz); 13C-NMR
(100 MHz, DMSO-d6) δ 158.7, 147.2, 144.5, 142.9, 138.1,
135.9, 133.8, 128.9, 127.7, 127.4, 127.0, 126.5, 125.4, 121.3,
118.8; LC-MS (positive ion mode): m/z 248 (M + H)+; HPLC:
99.8%.
2,3-Dimethoxy-8H-quinazolino[4,3-b]quinazolin-8-one (1b). Pale
yellow solid (144 mg, 95% yield), mp 290–292°C (literature [3] mp
>260°C). IR (KBr) νmax 1690 (CO), 1630, 1602, 1399, 1113,
867 cmÀ1; 1H-NMR (400 MHz, DMSO-d6) δ 9.30 (1H, s), 8.33 (1H, d,
J = 7.6 Hz), 8.12 (1H, s), 7.97 (1H, t, J = 7.8 Hz), 7.86 (1H, d,
J = 8.0 Hz), 7.58 (1H, t, J = 7.2 Hz), 7.40 (1H, s), 4.02 (3H, s),
4.00 (3H, s); 13C-NMR (100 MHz, DMSO-d6) δ 158.8, 154.2,
149.9, 147.6, 139.0, 136.7, 135.9, 127.1, 127.0, 125.7, 122.3,
118.0, 114.2, 109.1, 105.0, 56.2, 56.0; LC-MS (positive ion
mode): m/z 308 (M+ H)+; HPLC: 99.2%.
In vitro kinase assay.
The in vitro kinase activity was
performed on the wild type tyrosine kinase domain of the
human EGFR. The inhibitory potency was tested using
homogeneous time-resolved fluorescence KinEASE-TK assay
(Cisbio) according to manufacturer’s instructions. Adenosine 5′-
triphosphate (ATP) was purchased from Sigma-Aldrich Co., St
Louis, MO, USA. EGFR active was purchased from Millipore,
Darmstadt, Germany. 384-Well low volume plates were
purchased from Griener Bio, Germany.
Briefly, the experiment was performed in two steps. The first step
is the enzymatic reaction in which the TK Substrate-biotin was
incubated with the kinase, and ATP was added to start the
enzymatic reaction. Assays were carried out in low volume, black
384-well plates with a 20μL assay volume containing 100 μM
ATP, 1 μM TK Substrate-biotin and 4 ng of EGFR enzyme. The
plate was incubated at RT for 30min. In the subsequent detection
step, TK-Antibody labeled with Eu3 + ÀCryptate, 125 nM
streptavidin-XL665 were added with EDTA (used to stop the
kinase activity), and the plate was incubated at RT for 60 min.
The fluorescence was measured at 620 nm (Cryptate) and
665 nm (XL665) using Spectramax M5e (Molecular Devices).
2,3,10,11-Tetramethoxy-8H-quinazolino[4,3-b]quinazolin-8-
one (1c). Pale yellow solid (170 mg, 92% yield), mp 328–330°
C (literature [3] mp >260°C). IR (KBr) νmax 1686 (CO), 1606,
1
1398, 1104, 861 cmÀ1; H-NMR (400 MHz, DMSO-d6) δ 9.31
(1H, s), 8.07 (1H, s), 7.60 (1H, s), 7.38 (1H, s), 7.30 (1H, s),
4.01 (6H, s), 3.98 (3H, s), 3.94 (3H, s); 13C-NMR (100 MHz,
CDCl3) δ 158.4, 156.6, 154.2, 150.4, 148.9, 145.0, 143.5,
139.1, 136.8, 115.0, 111.3, 109.0, 107.6, 106.1, 105.1, 56.5,
56.4, 56.4, 56.3; LC-MS (positive ion mode): m/z 368 (M + H)+;
HPLC: 99.8%.
10-Chloro-8H-quinazolino[4,3-b]quinazolin-8-one (1d).
Off-white solid (126 mg, 90% yield), mp 218–220°C. IR (KBr)
νmax 1705 (CO), 1626, 1380, 1143, 829 cmÀ1
;
1H-NMR
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

S. Venkateswarlu, M. Satyanarayana, V. Lakshmikanthan, and V. Siddaiah
Vol 000
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with their high potency to inhibit EGFR were used as a standard
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Acknowledgments. We sincerely thank Sri Gokaraju Ganga Raju,
Chairman, and Mr. Gokaraju Rama Raju, Director, Laila Research
Center, for support and encouragement.
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet