Improved and efficient synthesis of pyrrolo[2,3,4-kl]acridin-1-one derivatives under ultrasound irradiation

Article abstract of DOI:10.1002/jhet.1882

A improved and efficient procedure for the synthesis of pyrrolo[2,3,4-kl]acridin-1-one derivatives via the reaction of isatin and enaminone catalyzed by ceric ammonium nitrate under ultrasonic condition has been developed. Compared with the conventional methods, the remarkable advantages of this method are mild reaction conditions, operational simplicity, higher yield, and shorter reaction times.

Full text of DOI:10.1002/jhet.1882

Month 2014
Improved and Efficient Synthesis of Pyrrolo[2,3,4-kl]acridin-1-one
Derivatives under Ultrasound Irradiation
*
*
Li-Li Li, Hui-Yuan Wang, Wei Lin, Zhi-Bin Huang, and Da-Qing Shi
Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials
Science, Soochow University, Suzhou 215123, People’s Republic of China
*
E-mail: zbhuang@suda.edu.cn; dqshi@suda.edu.cn
Received September 9, 2012
DOI 10.1002/jhet.1882
Published online 00 Month 2014 in Wiley Online Library (wileyonlinelibrary.com).
A improved and efficient procedure for the synthesis of pyrrolo[2,3,4-kl]acridin-1-one derivatives via the
reaction of isatin and enaminone catalyzed by ceric ammonium nitrate under ultrasonic condition has been
developed. Compared with the conventional methods, the remarkable advantages of this method are mild
reaction conditions, operational simplicity, higher yield, and shorter reaction times.
J Hetercyclic Chem., 00, 00 (2014).
INTRODUCTION
recent years, and numerous examples under this condition
for constructing heterocycles with interesting properties
have been reported in the literature [19]. As a part of our
interest in the synthesis of heterocyclic compounds under
ultrasound irradiation [20], herein, we report the facile syn-
thesis of pyrrolo[2,3,4-kl]acridin-1-one derivatives via the
reaction of isatin and enaminone catalyzed by CAN under
ultrasonic condition.
Nitrogen-containing heterocyclic compounds are wide-
spread in natural products and medicinal agents [1], and
their applications to biologically active pharmaceuticals,
agrochemicals, and functional materials are becoming
more and more important [2]. Among them, acridine deri-
vatives are very interesting compounds and have received
considerable attention as a result of their biological activity
and an interesting template for medicinal chemistry.
Many of those compounds are known as antiparasitic [3],
antibacterial [4], and antitumor activity [5]. Pyrrolo[2,3,4-kl]
acridin-1-ones are pyrrole-fused acridine derivatives, which
are the skeleton of some alkaloids [6]. Recently, there have
been studies on the synthesis of these molecules [7]. However,
these methods require multistep synthesis. Thus, there is a
need for the development of concise and efficient methods
for the constructing of this heterocyclic skeleton library.
Ceric ammonium nitrate (CAN) is an orange solid and
commercially available. It has been widely used in industry
and academia during the past seven decades. In academia,
CAN is explored extensively in organic reactions. Repre-
sentative examples include oxidation [8], oxidative addi-
tion [9], photooxidation [10], nitration [11], deprotection
[12], graft polymerization [13], and so forth. Intermediates
formed in these reactions may undergo oxidative fragmen-
tation [14], rearrangement [15], or cleavages of C—H and
C—C bonds [16]. Recently, CAN have been used in cata-
lyzing multicomponent reactions [17].
RESULTS AND DISCUSSION
To achieve suitable conditions for the synthesis of
pyrrolo[2,3,4-kl]acridin-1-ones, various reaction conditions
have been investigated in the reaction of 5-bromoisatin (1i)
and 3-(3,5-dimethylphenylamino)-5,5-dimethylcyclohex-2-
enone (2i) as a model reaction (Scheme 1).
Initially, we examined the effects of the solvents through
some experiments. To search for the optimal solvent, the
ultrasonic-assisted reaction was examined using ethanol,
methanol, THF, acetonitrile, dioxane, toluene, and water
as solvent. The results were summarized in Table 1. The
observation revealed that the reaction using ethanol as
solvent gave the best result, which afforded the product
not only in good yield but also with higher reaction rates
(94% yield in 1.5 h) (Table 1, entry 1). Methanol, THF,
acetonitrile, dioxane, and toluene afforded moderate yields
of desired products but took comparatively longer reaction
time (Table 1, entries 2–6). When the reaction was
performed in water, unfortunately, the desired product was
not detected (Table 1, entry 7). Thus, ethanol was chosen
as the solvent for all further reactions.
Ultrasonic irradiation [18], as a powerful tool in modern
chemistry for the organic reactions, has attracted more at-
tention of chemists in the recent two decades. The ultra-
sonic irradiation with its advantages of convenient
operation, milder reaction conditions, short reaction time,
and high efficiency has become particularly popular in
To optimize the catalyst loading, 5, 10, 15, and 20 mol%
of CAN was tested, respectively. The results are summa-
rized in Table 2. A 10 mol% loading of CAN was sufficient
© 2014 HeteroCorporation

L.-L. Li, H.-Y. Wang, W. Lin, Z.-B. Huang, and D.-Q. Shi
Vol 000
Scheme 1. Modle reaction. CAN, ceric ammonium nitrate.
to push the reaction forward, and 5 mol% of CAN was not
enough. Higher amounts of CAN did not lead to significant
change in the reaction yields.
After optimizing the reaction conditions, the generality of
this method was examined by the reaction of several substi-
tuted isatins and enaminone in ethanol under ultrasound irradi-
ation; the results are shown in Table 3. To our delight, under
the aforementioned optimized conditions, the reactions
proceeded smoothly, and a variety of the desired pyrrolo
[2,3,4-kl]acridin-1-one derivatives 3 were obtained in good
yields whether the isatin (1) or enaminone (2) are the bearing
electron-withdrawing substituents or electron-donating
substituents (Table 3, entries 1–11). To the best of our
knowledge, this new procedure provides the first example
of an efficient and ultrasound-promoted one-pot approach
for synthesis of pyrrolo[2,3,4-kl]acridin-1-one derivatives.
To find the specific effect of ultrasound on this reaction,
all previously mentioned were carried out under the same
conditions in the absence of ultrasound irradiation (Ta-
ble 3). When the reaction was carried out under conven-
tional method, it gave comparatively low yields of
products and took longer reaction time, whereas the same
reaction carried in the influence of ultrasonic irradiation
gave excellent yields of product in short reaction time.
Thus, ultrasonic irradiation was found to have beneficial
effect on the synthesis of pyrrolo[2,3,4-kl]acridin-1-one
derivatives that was superior to the traditional method with
respect to yield, reaction time, particularly when considering
the basic green chemistry concept. It is apparent that ultra-
sound irradiation can accelerate the reaction significantly to
give higher yield. The reason may be the phenomenon of
cavitation produced by ultrasound. The effects of ultrasound
observed during organic reaction are due to cavitation. It has
been experimentally shown that, the cavitational collapse
creates drastic conditions inside the medium for an extremely
short time and temperatures of 2000–5000 K, pressures up to
Table 1
Optimization the solvents for the synthesis of 3i.
With USa
Without USb
Entry
Solvent
Ethanol
Methanol
THF
Acetonitrile
Dioxane
Toluene
Water
Time (h) Yieldc (%) Time (h) Yieldc (%)
1
2
3
4
5
6
7
1.5
2
3
3.5
4
2.5
94
82
70
72
75
80
NR
4
4.5
6
7
10
80
62
68
70
60
76
NR
5
24
11
US, ultrasound
NR, no reaction.
aReaction under ultrasonic waves at RT.
bReaction under refluxing temperature.
cYields of isolated products.
Table 2
Effect of the amount of catalyst for the synthesis of 3i.
Amounts of
CAN (mol%)
Entry
Time (h)
Isolated yield (%)
1
5
10
15
20
3
1.5
2
85
94
90
87
2
3
4
2
CAN, ceric ammonium nitrate.
Table 3
Synthesis of 3 under sonication and conventional conditions.
With US
Without US
Entry
Product
R1
R2
Time (h)
Yielda(%)
Time (h)
Yielda(%)
1
2
3
4
5
6
7
8
9
3a
3b
3c
3d
3e
3f
3g
3h
3i
H
H
5-F
4-CH3C6H4
2-ClC6H4
0.8
1.5
0.8
1.5
1.5
0.7
0.8
1
91
90
91
89
84
92
92
90
94
90
86
3
2.5
3
3.5
4
2
2.5
3
2.5
3
82
76
80
80
65
76
74
82
79
78
69
4-CH3OC6H4
CH3(CH2)3
4-NO2C6H4
4-(CH3)3CC6H4
2-ClC6H4
4-CH3OC6H4
3,5-(CH3)2C6H3
C6H5
5-Cl
5-Cl
5-Cl
6-Cl
5-Br
5-Br
5-CH3
7-CF3
1.5
1
1
10
11
3j
3k
Naphthalene-1-yl
3.5
aYields of isolated products.
bUS, ultrasound.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2014
Synthesis of Pyrrolo[2,3,4-kl]acridin-1-one under Ultrasound Irradiation
1800 atm inside the collapsing cavity have been produced
under sonic condition [21]. In addition, ultrasound is known
to generate extremely fine emulsions from mixtures of immis-
cible phases. On closer inspection, this disturbance can be
seen as a large number of tiny “explosions” at the interface,
effectively sending small jets of liquid from one phase into
the other. One of the main consequences of these emulsions
is the dramatic increase in the interfacial contact area between
the immiscible phases, that is, an increase in the region over
which any reaction between species dissolved in the different
phases can take place [22].
To expand the scope of the current method, N-substituted
3-aminocyclohex-2-enone (4) was examined as a replacement
for the N-substituted 3-amino-5,5-dimethylcyclohex-2-enone
(2). To our surprise, under the aforementioned optimized
conditions, the desired products 4,5-dihydropyrrolo-
[2,3,4-kl]acridin-1-one derivatives 3 were not obtained.
Its oxidation products pyrrolo[2,3,4-kl]-acridin-1-one
derivatives 5 were obtained instead in good yields
(Scheme 2 and Table 4). So, the reaction pathways could
therefore be controlled by varying the enaminones
with a different substituted pattern to give a series of
novel 4,5-dihydropyrrolo[2,3,4-kl]acridin-1-ones and pyrrolo
[2,3,4-kl]-acridin-1-ones selectively.
Figure 1. The structure of compound 3a.
According to the literature [23], we proposed the plausible
mechanism for the formation of pyrrolo[2,3,4-kl]acridine
derivatives 3 (Scheme 3). The first step involves the
formation of intermediate A by the nucleophilic addition
of enaminone (2) to isatin (1) catalyzed by CAN. The
intermediate A was followed by imine–enamine tautomer-
ization to produce B. Intermediate B, through intramolec-
ular cyclization and ring-opening reactions formed
D. Subsequently, the NH2 attacked the intramolecular
carbonyl group catalyzed by CAN to form intermediate
E, which, through losing water, produced F. Finally, F lost
a molecule water to result in the product 3.
The structures of the products 3 and 5 were identified
1
from their IR, H-NMR, 13C-NMR, and HRMS spectra.
The structure of compound 3a was further confirmed by
X-ray analysis (Figure 1).
Scheme 2. The synthesis of compounds 5 under sonication and conven-
In conclusion, we have described an approach to explore
the use of ultrasound irradiation for the synthesis of pyrrolo
[2,3,4-kl]acridin-1-one derivatives via domino reaction of
isatin and enaminone catalyzed by CAN. Compared with
traditional methods, the procedure offers several advan-
tages including milder reaction conditions, excellent
yields, and shorter reaction time.
tional conditions. CAN, ceric ammonium nitrate.
Table 4
Synthesis of 5 under sonication and conventional conditions.
With US
Without US
Entry
Product
R1
R2
n-C4H9
4-NO2C6H4
C6H5
Time (h)
Yielda(%)
Time (h)
Yielda(%)
1
2
3
4
5
6
7
8
9
5a
5b
5c
5d
5e
5f
5g
5h
5i
H
H
1.5
2
1
2
1.5
1
1
1.5
1
1.5
1
70
56
77
72
74
70
81
75
78
80
72
3.5
4.5
4
4
4
3
3
4
3
56
35
66
58
65
52
65
61
64
62
62
5-Cl
5-Cl
5-Cl
5-Cl
5-Br
5-Br
5-CH3
5-F
4-ClC6H4
4-CH3C6H4
Naphthalene-1-yl
4-t-BuC6H4
3,5-(CH3)2C6H3
3,5-(CH3)2C6H3
4-CH3OC6H4
2,6-Cl2C6H3
10
11
5j
5k
4
3.5
7-CF3
aYields of isolated products.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

L.-L. Li, H.-Y. Wang, W. Lin, Z.-B. Huang, and D.-Q. Shi
Vol 000
Scheme 3. Proposed mechanism for the formation of 3. CAN, ceric ammonium nitrate.
(1 mmol), enaminone 2 or 4 (1 mmol), and CAN (0.1 mmol) in
ethanol (10 mL). The mixture was sonicated in the water bath of
an ultrasonic cleaner under air condition at RT. After the
completion of the reaction (monitored by TLC), the solvent was
evaporated under reduced pressure, and the residue was purified
by column chromatography using petrolum ether–acetone (6:1)
as eluent to produce the desired corresponding products 3 or 5.
4,4-Dimethyl-2-(4-methylphenyl)-4,5-dihydropyrrolo[2,3,4-kl]
acridin-1(2H)-one (3a). yellow solid; mp 176–178ꢀC; IR (KBr,
cmÀ1): 3031, 2941, 1705, 1491, 1341, 1107, 817; 1H-NMR (300 MHz,
CDCl3): d (ppm) 1.32 (s, 6H, 2 Â CH3), 2.44 (s, 3H, CH3), 3.21 (s, 2H,
CH2), 5.59 (s, 1H, CH), 7.37 (s, 4H, ArH), 7.63–7.78 (m, 2H, ArH),
8.17 (d, J= 8.4 Hz, 1H, ArH), 8.73 (d, J= 7.8 Hz, 1H, ArH); 13C-
NMR (75 MHz, CDCl3): d (ppm) 21.2, 30.9, 37.0, 44.2, 118.2,
122.6, 124.2, 125.0, 126.3, 126.4, 127.7, 129.4, 129.5, 130.5,
132.0, 133.5, 137.5, 149.7, 154.6, 166.8; HRMS Calcd for
EXPERIMENTAL
All reagents were purchased from commerical sources and used
without further purification. Ultrasonication was performed in a
KQ-250E medical ultrasound cleaner ( Kunshan Ultrasonic Instru-
ments Co., Ltd, Kunshan, China ) with a frequency of 40 kHz and
an output power of 250W (Built-in heating, 30–110ꢀC thermostat-
ically adjustable). Melting points are uncorrected. IR spectra were
recorded on Varian F-1000 spectrometer ( Varian Inc., Palo Alto,
CA, USA ) in KBr with absorptions in reciprocal centimeters.
1H-NMR and 13C-NMR were determined on Varian Inova-300 or
Inova-400 MHz spectrometers ( Varian Inc., Palo Alto, CA, USA)
in CDCl3 solution. J values are in hertz. Chemical shifts are
expressed in parts per million downfield from internal standard
TMS. HRMS data were obtained using Bruker micrOTOF-Q
instrument (Bruker Daltonics Inc., Billerica, MA, USA). X-Ray
diffraction was recorded on a Rigaku Mercury CCD/AFC diffrac-
tometer (Rigaku Corporation, Tokyo, Japan). The reaction flask
was located at the maximum energy area in the cleaner; the surface
C23H20N2ONa [M + Na]: 363.1473, found: 363.1479.
2-(2-Chlorophenyl)-4,4-dimethyl-4,5-dihydropyrrolo[2,3,4-kl]
acridin-1(2H)-one (3b). gray solid; mp 136–138ꢀC; IR (KBr,
cmÀ1): 2966, 2866, 1715, 1655, 1587, 1484, 1376, 1349, 1246,
1138, 1090, 1059, 962, 859, 836, 771, 739, 674; 1H-NMR
(300MHz, CDCl3): d (ppm) 1.31 (d, J = 7.2 Hz, 6H, 2 Â CH3),
3.22 (d, J = 7.8 Hz, 2H, CH2), 5.29 (t, J = 10.8 Hz, 1H, CH),
7.45–7.47 (m, 3H, ArH), 7.62–7.76 (m, 3H, ArH), 8.20
(d, J = 9.3 Hz, 1H, ArH), 8.73 (d, J = 7.5 Hz, 1H, ArH); 13C-NMR
(75 MHz, CDCl3): d (ppm) 30.8, 37.1, 44.2, 118.1, 122.6, 124.3,
124.9, 126.9, 127.8, 129.4, 129.5, 130.2, 130.7, 132.3, 132.9,
133.3, 149.6, 154.7, 166.6; HRMS Calcd for C22H18ClN2O
of reactants is slightly lower than the leave of the water.
General procedure for the synthesis of pyrrolo[2,3,4-kl]
acridin-1-ones (3 and 5) under conventional conditions
(method A).
A 100-mL flask was charged with isatin (1)
(1 mmol), enaminone 2 or 4 (1 mmol), and CAN (0.1 mmol) in
ethanol (10 mL). The mixture was stirred at refluxing temperature.
After the completion of the reaction (monitored by TLC), the
solvent was evaporated under reduced pressure, and the residue was
purified by column chromatography using petrolum ether–acetone
(6:1) as eluent to produce the desired corresponding products 3 or 5.
General procedure for the synthesis of pyrrolo[2,3,4-kl]
acridin-1-ones (3 and 5) under sonochemical conditions
[M+ H]: 361.1108, found: 361.1103.
2-Butyl-9-chloro-4,4-dimethyl-4,5-dihydropyrrolo[2,3,4-kl]
acridin-1(2H)-one (3c).
(KBr, cmÀ1): 2935, 1701, 1655, 1510, 1446, 1363, 1335,
yellow solid; mp 144–146ꢀC; IR
(method B).
A 100-mL flask was charged with isatin (1)
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Month 2014
Synthesis of Pyrrolo[2,3,4-kl]acridin-1-one under Ultrasound Irradiation
1288, 1091, 964, 832, 795, 739, 719; 1H-NMR (300 MHz, CDCl3)
d (ppm) 0.98 (d, J = 6.9 Hz, 3H, CH3), 1.25–1.50 (m, 8H, CH2 and
2 Â CH3), 1.60–1.76 (m, 2H, CH2), 3.14 (s, 2H, CH2), 3.79 (s, 2H,
CH2), 5.55 (s, 1H, CH), 7.63 (d, J = 6.6 Hz, 1H, ArH), 8.03 (d,
J = 8.7 Hz, 1H, ArH), 8.64 (s, 1H, ArH); 13C-NMR (101 MHz,
CDCl3): d (ppm) 9.2, 15.6, 26.4, 26.5, 32.5, 35.4, 39.5, 112.9,
118.6, 118.7, 120.3, 122.4, 125.5, 126.1, 128.4, 129.0, 143.3,
150.0, 162.4; HRMS Calcd for C20H22ClN2O [M + H]: 341.1421,
(d, J= 9.0 Hz, 1H, ArH), 8.02 (d, J= 9.0 Hz, 1H, ArH), 8.88 (s, 1H,
ArH); 13C-NMR (101 MHz, CDCl3): d (ppm) 16.8, 26.3, 32.6, 39.6,
114.6, 117.5, 119.1, 119.6, 120.0, 122.0, 122.3, 125.0, 126.3, 128.3,
128.8, 129.7, 134.7, 143.6, 150.5, 161.7; HRMS Calcd for
C24H22BrN2O [M + H]: 433.0915, found: 433.0906.
4,4,9-Trimethyl-2-phenyl-4,5-dihydropyrrolo[2,3,4-kl]acridin-
1(2H)-one (3i). yellow solid; mp 168–170ꢀC; IR (KBr, cmÀ1):
2958, 1712, 1651, 1594, 1511, 1500, 1418, 1401, 1365, 1344,
1249, 1153, 1120, 1095, 1065, 887, 824, 759; 1H-NMR
(300MHz, CDCl3): d (ppm) 1.32 (s, 6H, 2 Â CH3), 2.59 (s, 3H,
CH3), 3.20 (s, 2H, CH2), 5.61 (s, 1H, CH), 7.41–7.56
(m, 6H, ArH), 8.06 (d, J = 8.4 Hz, 1H, ArH), 8.51 (s, 1H, ArH);
13C-NMR (101 MHz, CDCl3): d (ppm) 22.3, 31.4, 37.6, 44.6,
118.7, 123.1, 123.8, 126.9, 127.0, 127.9, 129.6, 129.9, 132.2,
133.9, 135.4, 138.6, 148.8, 153.9, 167.4; HRMS Calcd for
C23H21N2O [M+ H]: 341.1654, found: 341.1677.
found: 341.1426.
2-(4-tert-Butylphenyl)-9-chloro-4,4-dimethyl-4,5-dihydropyrrolo
[2,3,4-kl]acridin-1(2H)-one (3d). yellow solid; mp 180–182ꢀC;
IR (KBr, cmÀ1): 2952, 2865, 1703, 1652, 1602, 1460, 1417, 1340,
1292, 1205, 1151, 1119, 1093, 963, 841, 750, 656; 1H-NMR
(300 MHz, CDCl3): d (ppm) 1.33 (s, 6H, 2 Â CH3), 1.39 (s, 9H, C
(CH3)3), 3.20 (s, 2H, CH2), 5.69 (s, 1H, CH), 7.42 (d, J=6.6Hz,
2H, ArH), 7.56 (d, J= 7.8 Hz, 2H, ArH), 7.69 (d, J=7.2Hz, 1H,
ArH), 8.09 (d, J= 9.0 Hz, 1H, ArH), 8.71 (s, 1H, ArH); 13C-NMR
(101 MHz, CDCl3): d (ppm) 31.4, 31.9, 35.3, 37.7, 44.6, 119.8,
123.7, 123.8, 124.8, 126.3, 126.9, 127.5, 130.8, 131.3, 132.3,
133.7, 134.3, 148.5, 151.1, 155.4, 166.8; HRMS Calcd for
8-Chloro-2-(2-chlorophenyl)-4,4-dimethyl-4,5-dihydropyrrolo
[2,3,4-kl]acridin-1(2H)-one (3j). yellow solid; mp 162–164C;
IR (KBr, cmÀ1): 2962, 1715, 1654, 1508, 1484, 1380, 1294,
1162, 1119, 1093, 1065, 901, 883, 848, 767, 653; 1H-NMR
(300 MHz, CDCl3): d (ppm) 1.32 (s, 6H, 2 Â CH3), 3.21 (s, 2H,
CH2), 5.31 (s, 1H, CH), 7.45 (s, 3H, ArH), 7.62 (d, J = 6.3 Hz,
2H, ArH), 8.18 (s, 1H, ArH), 8.63 (d, J = 8.4 Hz, 1H, ArH);
13C-NMR (75 MHz, CDCl3): d (ppm) 30.7, 30.8, 37.2, 44.1,
118.7, 121.0, 124.9, 125.3, 126.9, 127.9, 128.7, 130.3, 130.6,
130.7, 132.1, 132.7, 133.2, 135.4, 150.0, 156.0, 166.2; HRMS
Calcd for C22H17Cl2N2O [M+ H]: 395.0718, found: 395.0717.
2-Butylpyrrolo[2,3,4-kl]acridin-1(2H)-one (5a). read solid;
mp 110–112ꢀC; IR (KBr, cmÀ1): 2962, 2872, 1700, 1634, 1513,
1462, 1401, 1362, 1315, 1244, 1145, 1078, 1005, 962, 922, 858,
C26H26ClN2O [M + H]: 417.1734, found: 417.1726.
9-Chloro-4,4-dimethyl-2-(4-nitrophenyl)-4,5-dihydropyrrolo
[2,3,4-kl]acridin-1(2H)-one (3e).
red solid; mp 178–180ꢀC;
IR (KBr, cmÀ1): 2962, 2867, 1735, 1633, 1594, 1521, 1499,
1401, 1302, 1241, 1181, 1145, 1113, 1065, 1018, 860, 832,
1
784, 767, 733, 691, 663; H-NMR (300 MHz, CDCl3): d (ppm)
1.37 (s, 6H, 2 Â CH3), 3.31 (s, 2H, CH2), 5.82 (s, 1H, CH),
7.77 (d, J = 8.4 Hz, 3H, ArH), 8.12 (d, J = 7.2 Hz, 1H, ArH),
8.43 (d, J = 8.7 Hz, 2H, ArH), 8.91 (d, J = 7.5 Hz, 1H, ArH);
13C-NMR (75 MHz, CDCl3): d (ppm) 30.8, 37.3, 44.1, 120.4,
122.8, 124.0, 124.9, 126.1, 126.7, 127.8, 127.9, 128.2, 131.8,
140.5, 146.0, 146.1, 155.5, 165.9; HRMS Calcd for
785, 721; 1H-NMR (400 MHz, CDCl3):
d (ppm) 0.98
(t, J = 7.2 Hz, 3H, CH3), 1.46 (dd, J = 15.2, 7.6 Hz, 2H, CH2),
1.81–1.86 (m, 2H, CH2), 3.96 (t, J = 7.2 Hz, 2H, CH2), 6.86
(d, J = 6.8 Hz, 1H, ArH), 7.65 (dd, J1 = 6.8 Hz, J2 = 8.8 Hz, 1H,
ArH), 7.75–7.79 (m, 2H, ArH), 7.85–7.89 (m, 1H, ArH),
8.38 (d, J = 8.8 Hz, 1H, ArH), 8.84 (d, J = 8.4 Hz, 1H, ArH);
13C-NMR (101 MHz, CDCl3): d (ppm) 14.0, 20.4, 31.1, 40.5,
104.8, 119.9, 122.2, 123.1, 124.3, 128.5, 129.1, 130.6, 130.8,
133.0, 140.5, 146.5, 151.9, 168.2; HRMS Calcd for C18H17N2O
[M + H]: 277.1341, found: 277.1355.
2-(4-Nitrophenyl)pyrrolo[2,3,4-kl]acridin-1(2H)-one (5b). yellow
solid; mp >300ꢀC; IR (KBr, cmÀ1): 2925, 1751, 1687, 1595, 1349,
1116, 852, 772, 720, 657; 1H-NMR (400 MHz, CDCl3): d (ppm) 7.18
(d, J= 7.6 Hz, 1H, ArH), 7.75–7.96 (m, 6H, ArH), 8.48 (d,
J = 8.0 Hz, 3H, ArH), 8.93 (d, J = 8.8 Hz, 1H, ArH); 13C-NMR
(101 MHz, CDCl3): d (ppm) 106.8, 120.2, 123.2, 123.9, 124.2,
125.3, 125.6, 126.9, 130.0, 131.1, 131.2, 132.7, 132.9, 138.6,
141.0, 146.7, 152.2, 166.9; HRMS Calcd for C20H12N3O3 [M + H]:
342.0879, found: 342.0863.
9-Chloro-2-phenylpyrrolo[2,3,4-kl]acridin-1(2H)-one (5c). yellow
solid; mp 206–208 C; IR (KBr, cmÀ1): 3035, 1700, 1632, 1503, 1382,
1123, 1087, 829, 721; 1H-NMR (400 MHz, CDCl3): d (ppm) 7.03 (d,
J= 7.2 Hz, 1H, ArH), 7.47 (t, J= 6.8 Hz, 1H, ArH), 7.58–7.72 (m,
5H, ArH), 7.85 (dd, J1 =8.8Hz, J2 = 7.2 Hz, 2H, ArH), 8.36 (d,
J= 9.6 Hz, 1H, ArH), 8.90 (d, J= 2.4 Hz, 1H, ArH); 13C-NMR
(75 MHz, CDCl3): d (ppm) 106.5, 120.2, 123.1, 123.5, 124.6,
126.3, 128.1, 129.7, 130.1, 131.2, 131.3, 133.3, 135.3, 140.5,
147.0, 152.4, 167.6; HRMS Calcd for C20H12ClN2O [M+H]:
331.0638, found: 331.0619.
C22H17ClN3O3 [M + H]: 406.0958, found: 406.0955.
9-Fluoro-2-(4-methoxyphenyl)-4,4-dimethyl-4,5-dihydropyrrolo
[2,3,4-kl]acridin-1(2H)-one (3f).
yellow solid; mp 164–166ꢀC;
IR (KBr, cmÀ1): 2956, 1709, 1651, 1620, 1453, 1419, 1346, 1252,
1
1215, 1119, 1035, 879, 794, 701; H-NMR (300 MHz, CDCl3): d
(ppm) 1.32 (s, 6H, 2 Â CH3), 3.19 (s, 2H, CH2), 3.88 (s,
3H, CH3O), 5.58 (s, 1H, CH), 7.06 (d, J = 6.6Hz, 2H, ArH),
7.35–7.67 (m, 3H, ArH), 8.17 (d, J = 5.4 Hz, 1H, ArH), 8.33
(d, J = 8.7Hz, 1H, ArH); 13C-NMR (101 MHz, CDCl3): d (ppm)
26.3, 32.6, 39.4, 51.0, 103.6, 103.8, 110.1, 114.2, 114.5, 114.8,
118.8, 120.2, 122.3, 122.6, 123.2, 127.0, 127.1, 129.1, 142.1,
149.2, 154.3, 162.0; HRMS Calcd for C23H20FN2O2 [M + H]:
375.1509, found: 375.1505.
9-Bromo-2-(4-methoxyphenyl)-4,4-dimethyl-4,5-dihydropyrrolo
[2,3,4-kl]acridin-1(2H)-one (3g). yellow solid; mp 140–142ꢀC;
IR (KBr, cmÀ1): 2961, 2806, 1705, 1650, 1602, 1508, 1464, 1376,
1249, 1153, 1136, 1062, 1028, 834, 797, 775; 1H-NMR
(300 MHz, CDCl3): d (ppm) 1.33 (s, 6H, 2 Â CH3), 3.19 (s, 2H,
CH2), 3.89 (s, 3H, CH3O), 5.60 (s, 1H, CH), 7.07 (d, J=4.8Hz,
2H, ArH), 7.40 (d, J= 4.8 Hz, 2H, ArH), 7.83 (d, J=6.9Hz, 1H,
ArH), 8.03 (d, J= 8.4 Hz, 1H, ArH), 8.88 (s, 1H, ArH); 13C-NMR
(75 MHz, CDCl3): d (ppm) 27.7, 30.9, 37.1, 44.0, 55.5, 114.6,
119.0, 122.0, 123.5, 124.0, 126.4, 126.8, 127.1, 127.7, 127.8,
130.8, 132.9, 133.5, 148.1, 155.0, 158.8, 166.3; HRMS Calcd for
C23H20BrN2O2 [M + H]: 435.0708, found: 435.0702.
9-Bromo-2-(3,5-dimethylphenyl)-4,4-dimethyl-4,5-dihydropyrrolo
[2,3,4-kl]acridin-1(2H)-one (3h). yellow solid; mp 160–162ꢀC; IR
(KBr, cmÀ1): 2957, 1700, 1650, 1596, 1439, 1415, 1366, 1314, 1211,
1150, 1098, 967, 891, 847, 825, 792, 748, 689; 1H-NMR (300 MHz,
CDCl3): d (ppm) 1.33 (s, 6H, 2 Â CH3), 2.41 (s, 6H, 2 Â CH3), 3.18
(s, 2H, CH2), 5.64 (s, 1H, CH), 7.08 (d, J= 4.8 Hz, 3H, ArH), 7.82
9-Chloro-2-(4-chlorophenyl)pyrrolo[2,3,4-kl]acridin-1(2H)-
one (5d). gray solid; mp 220–222ꢀC; IR (KBr, cmÀ1): 3096,
1710, 1634, 1499, 1464, 1418, 1380, 1325, 1250, 1156, 1070,
1
952, 884, 830, 774, 732, 662; H-NMR (400 MHz, CDCl3): d
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

L.-L. Li, H.-Y. Wang, W. Lin, Z.-B. Huang, and D.-Q. Shi
Vol 000
(ppm) 7.03 (d, J = 7.2 Hz, 1H, ArH), 7.58 (s, 4H, ArH), 7.72
(t, J = 7.6 Hz, 1H, ArH), 7.85–7.91 (m, 2H, ArH), 8.38
(d, J = 9.2 Hz, 1H, ArH), 8.90 (s, 1H, ArH); 13C-NMR
(75 MHz, CDCl3): d (ppm) 106.6, 122.7, 123.4, 124.5, 125.8,
126.3, 126.5, 127.8, 129.3, 129.6, 132.1, 133.2, 134.5, 134.6,
140.0, 146.6, 150.2, 166.6; HRMS Calcd for C20H11Cl2N2O
9-Fluoro-2-(4-methoxyphenyl)pyrrolo[2,3,4-kl]acridin-1(2H)-
one (5j). red solid; mp 240–242 C; IR (KBr, cmÀ1): 2922, 1701,
1635, 1520, 1474, 1384, 1299, 1254, 1180, 1035, 968, 865, 826,
1
798, 771, 721, 660; H-NMR (400 MHz, CDCl3): d (ppm) 3.90
(s, 3H, CH3O), 6.94 (d, J = 6.8 Hz, 2H, ArH), 7.10 (d, J = 8.8 Hz,
2H, ArH), 7.51 (d, J = 8.8 Hz, 2H, ArH), 7.65–7.72 (m, 2H,
ArH), 7.85 (d, J = 8.8 Hz, 1H, ArH), 8.42–8.49 (m, 2H,
ArH); 13C-NMR (101 MHz, CDCl3): d (ppm) 55.8, 106.5,
107.2, 107.4, 115.1, 120.0, 122.2, 122.5, 122.7, 127.4,
127.6, 132.9, 133.6, 133.7, 140.4, 146.0, 149.4, 159.2,
167.3; HRMS Calcd for C21H14FN2O2 [M + H]: 345.1039,
found: 345.1040.
[M + H]: 365.0248, found: 365.0236.
9-Chloro-2-(4-methylphenyl)pyrrolo[2,3,4-kl]acridin-1(2H)-
one (5e). yellow solid; mp 230–232ꢀC; IR (KBr, cmÀ1): 2993,
1
1746, 1700, 1632, 1514, 1384, 1126, 938, 827, 777; H-NMR
(300 MHz, CDCl3): d (ppm) 2.47 (s, 3H, CH3), 6.97 (s, 1H,
ArH), 7.27–7.51 (m, 4H, ArH), 7.68 (s, 1H, ArH), 7.83 (s, 2H,
ArH), 8.34 (s, 1H, ArH), 8.87 (s, 1H, ArH); 13C-NMR
(101 MHz, CDCl3): d (ppm) 106.4, 119.9, 122.5, 122.8, 123.0,
125.7, 126.8, 130.2, 131.9, 132.0, 132.1, 133.1, 135.8, 137.8,
140.2, 146.5, 150.0, 166.7; HRMS Calcd for C21H13ClN2ONa
2-(2,6-Dichlorophenyl)-7-trifluoromethylpyrrolo[2,3,4-kl]
acridin-1(2H)-one (5k).
orange solid; mp 210–212 C; IR
(KBr, cmÀ1): 3009, 1713, 1638, 1492, 1460, 1440, 1415,
1343, 1307, 1255, 1142, 1103, 1059, 1015, 942, 867, 800, 687;
1H-NMR (400 MHz, CDCl3): d (ppm) 6.68 (d, J = 6.8 Hz, 1H,
ArH), 7.46 (dd, J1 = 7.6 Hz, J2 = 8.8 Hz, 1H, ArH), 7.59
(d, J = 8.4 Hz, 2H, ArH), 7.74 (dd, J1 = 7.2 Hz, J2 = 9.2 Hz, 1H,
ArH), 7.86 (t, J = 8.0 Hz, 1H, ArH), 8.02 (d, J = 9.2 Hz, 1H, ArH),
8.32 (d, J = 7.2 Hz, 1H, ArH), 9.13 (d, J = 8.4 Hz, 1H, ArH);
13C-NMR (101 MHz, CDCl3): d (ppm) 106.7, 123.7, 127.6,
127.8, 128.8, 129.3, 129.6, 131.3, 133.8, 136.1, 138.5, 147.1,
147.8, 166.4; HRMS Calcd for C21H10Cl2F3N2O [M + H]:
433.0122, found: 433.0123.
[M + Na]: 367.0614, found: 367.0602.
9-Chloro-2-(naphthalen-1-yl)pyrrolo[2,3,4-kl]acridin-1(2H)-
one (5f).
1710, 1631, 1577, 1483, 1403, 1318, 1261, 1154, 1120, 1083,
874, 721; 1H-NMR (400 MHz, CDCl3):
(ppm) 6.60
red solid; mp 208–210ꢀC; IR (KBr, cmÀ1): 2924,
d
(d, J = 6.8 Hz, 1H, ArH), 7.50–7.73 (m, 6H, ArH), 7.89 (d,
J = 8.8 Hz, 2H, ArH), 7.88–7.90 (m, 2H, ArH), 8.42 (d, J = 9.6 Hz,
1H, ArH), 8.94 (d, J = 2.0 Hz, 1H, ArH); 13C-NMR
(101MHz, CDCl3): d (ppm) 106.9, 116.6, 118.1, 122.7, 123.2,
125.9, 126.8, 126.9, 127.4, 128.9, 129.9, 130.5, 131.0, 132.3, 132.5,
133.5, 135.0, 136.1, 141.4, 144.8, 146.8, 150.4, 151.0; HRMS Calcd
for C24H14ClN2O [M+ H]: 381.0795, found: 381.0790.
9-Bromo-2-(4-tert-butylphenyl)pyrrolo[2,3,4-kl]acridin-1(2H)-
one (5g).
Acknowledgment. This work were partially supported by the Major
Basic Research Project of the Natural Science Foundation of the
Jiangsu Higher Education Institutions (No. 10KJA150049), A
Project Funded by the Priority Academic Project Development of
Jiangsu Higher Education Institutions and the Foundation of Key
Laboratory of Organic Synthesis of Jiangsu Province (No. JSK0812).
red solid; mp 208–210ꢀC; IR (KBr, cmÀ1): 2958,
1711, 1631, 1503, 1460, 1381, 1252, 1154, 1126, 1055, 1007,
1
888, 823, 776, 720; H-NMR (300MHz, CDCl3): d (ppm) 1.40
(s, 9H, C(CH3)3), 7.01 (d, J = 4.8 Hz, 1H, ArH), 7.50–7.68
(m, 5H, ArH), 7.83 (d, J = 8.7 Hz, 1H, ArH), 7.95 (d, J = 8.1Hz,
1H, ArH), 8.26 (d, J = 9.0 Hz, 1H, ArH), 9.06 (s, 1H, ArH);
13C-NMR (75 MHz, CDCl3): d (ppm) 37.0, 40.5, 112.3, 128.2,
128.9, 130.0, 130.9, 131.9, 132.2, 132.6, 137.5, 137.8, 138.8,
140.0, 145.7, 152.2, 155.7, 156.5, 172.3; HRMS Calcd for
REFERENCES AND NOTES
C24H20BrN2O [M+ H]: 431.0759, found: 431.0737.
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9-Bromo-2-(3,5-dimethylphenyl)pyrrolo[2,3,4-kl]acridin-1(2H)-
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3012, 1702, 1634, 1595, 1476, 1381, 1337, 1206, 1155, 1079,
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2.43 (s, 6H, 2 Â CH3), 2.67 (s, 3H, CH3), 6.98 (d, J = 6.6 Hz,
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106.0, 119.6, 122.4, 123.1, 123.5, 126.3, 129.3, 130.3, 132.1,
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet