Facile one-pot synthesis of a novel series of 7-aryl-8H-benzo[h]indeno[1,2-b]quinoline-8-one derivatives catalyzed by tribromomelamine

Article abstract of DOI:10.1007/s11164-014-1787-2

Tribromomelamine, has been used as an efficient, inexpensive, and green catalyst for one-pot, three-component synthesis of 7-aryl-8H-benzo[h]indeno[1,2-b]quinoline-8-ones by reaction of 1,3-indanedione, aromatic aldehydes, and 1-naphthylamine under solvent-free conditions. The several advantages of this reaction include high yields, short reaction time, and high catalyst efficiency.

Full text of DOI:10.1007/s11164-014-1787-2

Res Chem Intermed
DOI 10.1007/s11164-014-1787-2
Facile one-pot synthesis of a novel series of 7-aryl-8H-
benzo[h]indeno[1,2-b]quinoline-8-one derivatives
catalyzed by tribromomelamine
•
Syed Sheik Mansoor Majid Ghashang
Krishnamoorthy Aswin
•
Received: 4 June 2014 / Accepted: 11 August 2014
Ó Springer Science+Business Media Dordrecht 2014
Abstract Tribromomelamine, has been used as an efficient, inexpensive, and
green catalyst for one-pot, three-component synthesis of 7-aryl-8H-benzo[-
h]indeno[1,2-b]quinoline-8-ones by reaction of 1,3-indanedione, aromatic alde-
hydes, and 1-naphthylamine under solvent-free conditions. The several advantages
of this reaction include high yields, short reaction time, and high catalyst efficiency.
Keywords Indeno[1,2-b]quinoline-8-one Á Solvent-free condition Á
Tribromomelamine Á 1,3-Indanedione Á 1-Naphthylamine
Introduction
Multicomponent reactions (MCRs) have recently become regarded as superior
synthetic strategies. MCRs are very flexible and proceed through a sequence of
reaction equilibria, yielding the target product. MCRs are important in combina-
torial chemistry because of their suitability for synthesis of small drug-like
molecules with high structural diversity. Other features of MCRs include simple
procedures for formation of the final products in a one-pot process from at least
three starting materials, atomic and structural economy, minimization of waste, easy
construction of complex organic molecules, and avoidance of complicated
purification processes. In the past decade much effort has been devoted to the
development of new three and four-component MCRs [1, 2].
S. S. Mansoor (&) Á K. Aswin
Bioactive Organic Molecule Synthetic Unit, Research Department of Chemistry, C. Abdul Hakeem
College, Melvisharam 632 509, Tamil Nadu, India
e-mail: smansoors2000@yahoo.co.in
M. Ghashang
Faculty of Sciences, Najafabad Branch, Islamic Azad University, Najafabad, Esfahan, Iran
123

S. S. Mansoor et al.
The quinoline skeleton is present in many biologically active compounds and is
frequently condensed with other heterocycles [3–7]. Synthesis of a series of
tetracyclic indenoquinolines and their evaluation as potential anticancer agents have
been reported [8]. The design, synthesis, and biological activity of less complex
quinoline derivatives with potent anti-TB activity has also recently been reported
[9–13]. A new class of conformationally locked indeno[2,1-c]quinoline compounds
with excellent antimycobacterial activity has been discovered [14]. Since the
discovery of indenoisoquinolines as a novel class of potential anticancer drug
candidates, extensive structural modifications have been investigated by altering the
substituent on the tetracyclic pharmacophore [15]. Some indolo[2,3-b]quinoline
derivatives have been synthesized and their antiproliferative activity has been
evaluated, on the grounds that these tetracyclic heterocycles may intercalate into the
DNA double helix resulting in inhibition of DNA replication and transcription [16].
Much effort has therefore been made to investigate new, simple, and direct
approaches to the construction of indenoquinoline skeletons.
Many methods have been reported for synthesis of indeno[2,1-b]quinolineone
derivatives [17–24]. Novel 7,8-dihydro-10-aryl-5H-indeno[1,2-b]quinoline-9,11-
diones have been synthesized, and their application as new pH indicators has been
shown to be feasible [25]. Recently, Khaligh et al. reported the synthesis of 7-aryl-
8H-benzo[f]indeno[2,1-b]quinoline-8-one derivatives by one-pot condensation of
2-naphthylamine, aromatic aldehydes, and indane-1,3-dione in the presence of
poly(4-vinylpyridinium)hydrogen sulfate [26] and 3-methyl-1-sulfonic acid imi-
dazolium hydrogen sulfate [27] as catalysts. Many of the above procedures have
their own merits. However, most of these procedures require heating under reflux
for hours in organic solvents, complex steps, use of expensive catalysts, and tedious
work-up. Therefore, the development of simple, efficient, clean, high-yielding, and
environmentally friendly approaches using new catalysts for synthesis of
indeno[2,1-b]quinolineones is an important task for organic chemists.
In recent years, TBM has received much attention as an inexpensive and nontoxic
catalyst for a series of organic transformations [28–31], because of its cost-
effectiveness, eco-friendly nature, easy handling, high reactivity, and easy work-up
procedures. TBM, a homogeneous, non-hygroscopic solid catalyst, has been used in
such organic transformations as the trimethylsilylation of hydroxyl groups with
1,1,1,3,3,3-hexamethyldisilazane (HMDS) [28], synthesis of 2-aryl thiazolines [29],
synthesis of 1-amidoalkyl-2-naphthols [30], and acetylation and formylation
reactions of alcohols [31]. TBM is stable under a variety of reaction conditions,
including acidic and basic conditions. It is noteworthy that TBM is produced via a
facile and clean process that does not require a complicated work-up procedure.
Prompted by these findings and because of our recent interest in the development
of practical and environmentally friendly procedures for synthesis of biologically
active organic compounds [32–35] by use of multi-component reactions, we have
developed an efficient synthesis of 7-aryl-8H-benzo[h]indeno[1,2-b]quinoline-8-one
derivatives by cyclocondensation reaction of 1,3-indanedione, aromatic aldehydes,
and 1-naphthylamine under solvent-free conditions at 80 °C with TBM as an
efficient, novel, homogeneous catalyst (Scheme 1).
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Facile one-pot synthesis of a novel series
BrHN
N
NHBr
Ar
N
O
N
N
O
NHBr
Ar
+
+
H2N
CHO
Solvent-free
80 oC
O
1a-n
2
3
4a-n
Scheme 1 Synthesis of 7-aryl-8H-benzo[h]indeno[1,2-b]quinoline-8-ones
Experimental
Chemicals and analysis
Chemicals were purchased from Merck, Fluka, and Aldrich. All yields refer to
isolated products unless otherwise stated. 1H NMR (500 MHz) and 13C NMR
(125 MHz) spectra were obtained by use of a Bruker DRX-500 Avance at ambient
temperature, with TMS as internal standard. FT-IR spectra were obtained as KBr
discs by use of a Shimadzu spectrometer. Mass spectra were determined on a
Varian–Saturn 2000 GC–MS instrument. Elemental analysis was performed by use
of a Perkin Elmer 2400 CHN elemental analyzer.
Preparation of tribromomelamine
Tribromomelamine (TBM) is readily prepared by dropwise addition of Br2 to a
solution of melamine in 5 M NaOH at room temperature (Scheme 2) [28].
General procedure for synthesis of 7-aryl-8H-benzo[h]indeno[1,2-b]quinoline-8-
ones (4a–n)
A mixture of 1,3-indanedione 1 (1 mmol), aromatic aldehyde 2 (1 mmol), 1-naph-
thylamine 3 (1 mmol), and tribromomelamine (10 mol%) was heated in an oil bath at
80 °C for 45–75 min. The progress of the reaction was monitored by TLC. On
completion of the transformation, the reaction mixture was cooled to room
temperature and hot chloroform was added. The filtrate was then collected and
distilled to dryness to give the crude product, which was recrystallized from a mixture
of EtOH and H2O to give compounds 4a–n in high yields (Scheme 1).
Spectral data for the synthesized compounds (4a–n)
7-Phenyl-8H-benzo[h]indeno[1,2-b]quinoline-8-one (4a)
IR (KBr, cm-1): 3,065, 1,714, 1,621, 1,570, 1,510, 1,482, 1,080, 840, 832, 815, 750;
1H NMR (500 MHz, CDCl3) d: 7.46–7.52 (m, 3H, Ar–H), 7.56–7.65 (m, 4H, Ar–
H), 7.70–7.82 (m, 5H, Ar–H), 7.88 (d, J = 7.7 Hz, 1H, Ar–H), 8.18 (d, J = 7.7 Hz,
1H, Ar–H), 9.38 (d, J = 8.0 Hz, 1H, Ar–H) ppm; 13C NMR (125 MHz, CDCl3) d:
123

S. S. Mansoor et al.
BrHN
N
NHBr
H2N
N
NH2
NaOH (aq.)
+
Br2
N
N
N
N
NHBr
Tribromomelamine(TBM)
NH2
Melamine
Scheme 2 Preparation of tribromomelamine (TBM)
121.4, 123.5, 124.3, 124.8, 125.4, 126.1, 127.3, 127.7, 128.4, 129.2, 129.6, 130.2,
131.4, 133.4, 135.6, 136.0, 137.4, 143.3, 146.3, 147.3, 149.0, 160.3, 193.0 ppm;
MS(ESI): m/z 358 (M ? H)?; Anal. Calcd for C26H15NO: C, 87.37; H, 4.23; N,
3.92 %. Found: C, 86.80; H, 4.69; N, 3.88 %.
7-(4-Chlorophenyl)-8H-benzo[h]indeno[1,2-b]quinoline-8-one (4b)
IR (KBr, cm-1): 3,072, 1,700, 1,602, 1,591, 1,574, 1,556, 1,488, 1,083, 842, 815,
1
750, 741; H NMR (500 MHz, CDCl3) d: 7.41 (d, J = 8.0 Hz, 2H, Ar–H), 7.48 (t,
J = 7.6 Hz, 1H, Ar–H), 7.52–7.63 (m, 3H, Ar–H), 7.66–7.77 (m, 5H, Ar–H), 7.80
(d, J = 7.6 Hz, 1H, Ar–H), 8.14 (d, J = 7.6 Hz, 1H, Ar–H), 9.42 (d, J = 8.0 Hz,
1H, Ar–H) ppm; 13C NMR (125 MHz, CDCl3) d: 122.0, 123.7, 124.2, 124.7, 125.7,
126.4, 127.0, 127.5, 128.2, 129.0, 129.5, 130.5, 131.3, 134.0, 135.4, 136.3, 138.0,
139.0, 139.6, 143.0, 146.7, 147.0, 149.5, 161.5, 192.4 ppm; MS(ESI): m/z 392.5
(M ? H)?; Anal. Calcd for C26H14ClNO: C, 79.69; H, 3.60; N, 3.57 %. Found: C,
79.58; H, 3.55; N, 3.50 %.
7-(4-Methylphenyl)-8H-benzo[h]indeno[1,2-b]quinoline-8-one (4c)
IR (KBr, cm-1): 3,061, 1,707, 1,608, 1,572, 1,502, 1,344, 1,025, 840, 832, 815, 750;
1H NMR (500 MHz, CDCl3) d: 2.54 (s, 3H, CH3), 7.37 (d, J = 8.0 Hz, 2H, Ar–H),
7.40 (d, J = 8.0 Hz, 2H, Ar–H), 7.47 (t, J = 7.40 Hz, 1H, Ar–H), 7.56–7.74 (m,
6H, Ar–H), 7.83 (d, J = 7.6 Hz, 1H, Ar–H), 8.14 (d, J = 7.2 Hz, 1H, Ar–H), 9.40
(d, J = 8.0 Hz, 1H, Ar–H) ppm; 13C NMR (125 MHz, CDCl3) d: 21.6, 122.7,
123.3, 124.0, 124.5, 125.5, 126.6, 127.5, 127.8, 128.5, 129.0, 129.7, 130.4, 131.7,
134.5, 135.3, 136.4, 138.0, 139.3, 139.5, 142.4, 146.6, 147.3, 149.5, 162.5,
192.7 ppm; MS(ESI): m/z 372 (M ? H)?; Anal. Calcd for C27H17NO: C, 87.31; H,
4.61; N, 3.77 %. Found: C, 87.22; H, 4.57; N, 3.75 %.
7-(4-Methoxyphenyl)-8H-benzo[h]indeno[1,2-b]quinoline-8-one (4d)
IR (KBr, cm-1): 3,075, 2,965, 1,725, 1,605, 1,582, 1,570, 1,500, 1,495, 1,455,
1,245, 1,025, 840, 750; 1H NMR (500 MHz, CDCl3) d: 3.98 (s, 3H, OCH3), 7.15 (d,
J = 8.6 Hz, 2H, Ar–H), 7.45 (d, J = 8.6 Hz, 2H, Ar–H), 7.49 (t, J = 7.4 Hz, 1H,
Ar–H), 7.56–7.73 (m, 6H, Ar–H), 7.85 (d, J = 7.9 Hz, 1H, Ar–H), 8.17 (d,
J = 7.4 Hz, 1H, Ar–H), 9.43 (d, J = 8.0 Hz, 1H, Ar–H) ppm; 13C NMR (125 MHz,
CDCl3) d: 54.4, 121.6, 123.3, 124.4, 124.8, 125.8, 126.3, 126.7, 127.0, 128.5, 129.4,
123

Facile one-pot synthesis of a novel series
129.7, 130.3, 131.8, 133.7, 134.5, 136.5, 137.7, 139.5, 139.9, 142.8, 146.7, 147.7,
149.7, 161.4, 193.4 ppm; MS(ESI): m/z 388 (M ? H)?; Anal. Calcd for
C27H17NO2: C, 83.70; H, 4.42; N, 3.62 %. Found: C, 83.66; H, 4.40; N, 3.55 %.
7-(4-Fluorophenyl)-8H-benzo[h]indeno[1,2-b]quinoline-8-one (4e)
IR (KBr, cm-1): 3,072, 1,709, 1,603, 1,572, 1,504, 1,155, 1,069, 852, 840, 815, 798,
772, 744; 1H NMR (500 MHz, CDCl3) d: 7.20 (d, J = 8.6 Hz, 2H, Ar–H),
7.44–7.53 (m, 3H, Ar–H), 7.57 (d, J = 9.1 Hz, 1H, Ar–H), 7.62–7.77 (m, 5H, Ar–
H), 7.82 (d, J = 7.2 Hz 1H, Ar–H), 8.11 (d, J = 8.0 Hz, 1H, Ar–H), 9.34 (d,
J = 8.1 Hz, 1H, Ar–H) ppm; 13C NMR (125 MHz, CDCl3) d: 121.7, 122.9, 123.9,
124.4, 125.4, 126.5, 126.9, 127.4, 128.2, 128.7, 129.3, 130.4, 132.0, 133.8, 134.5,
136.4, 137.7, 139.0, 142.2, 142.7, 146.5, 147.7, 149.0, 162.7, 190.8 ppm; MS(ESI):
m/z 376 (M ? H)?; Anal. Calcd for C26H14FNO: C, 83.19; H, 3.76; N, 3.73 %.
Found: C, 83.11; H, 3.71; N, 3.68 %.
7-(3-Chlorophenyl)-8H-benzo[h]indeno[1,2-b]quinoline-8-one (4f)
IR (KBr, cm-1): 3,066, 2,925, 1,705, 1,602, 1,584, 1,575, 1,485, 1,455, 1,261,
1,025, 845, 753; 1H NMR (500 MHz, CDCl3) d: 7.33–7.52 (m, 6H, Ar–H),
7.63–7.71 (m, 5H, Ar–H), 7.83 (d, J = 7.8 Hz, 1H, Ar–H), 8.15 (d, J = 7.4 Hz, 1H,
Ar–H), 9.33 (d, J = 8.0 Hz, 1H, Ar–H) ppm; 13C NMR (125 MHz, CDCl3) d:
122.5, 123.7, 124.5, 124.8, 125.2, 126.0, 126.8, 127.3, 127.9, 128.9, 129.3, 129.7,
132.3, 134.0, 135.2, 136.7, 137.0, 139.4, 141.2, 142.6, 146.7, 147.9, 149.5, 160.8,
191.5 ppm; MS(ESI): m/z 392.5 (M ? H)?; Anal. Calcd for C26H14ClNO: C, 79.69;
H, 3.60; N, 3.57 %. Found: C, 79.60; H, 3.57; N, 3.53 %.
7-(3-Nitrophenyl)-8H-benzo[h]indeno[1,2-b]quinoline-8-one (4g)
IR (KBr, cm-1): 3,057, 2,944, 1,711, 1,612, 1,582, 1,577, 1,480, 1,459, 1,272,
1,015, 822, 743; 1H NMR (500 MHz, CDCl3) d: 7.37–7.55 (m, 6H, Ar–H),
7.60–7.73 (m, 5H, Ar–H), 7.86 (d, J = 7.8 Hz, 1H, Ar–H), 8.12 (d, J = 7.4 Hz, 1H,
Ar–H), 9.37 (d, J = 8.0 Hz, 1H, Ar–H) ppm; 13C NMR (125 MHz, CDCl3) d:
121.8, 123.8, 124.4, 124.7, 125.5, 126.0, 127.4, 127.7, 128.4, 128.8, 129.4, 129.7,
132.5, 134.0, 135.3, 135.9, 137.0, 139.5, 141.4, 142.8, 146.9, 147.4, 148.9, 160.6,
193.1 ppm; MS(ESI): m/z 403 (M ? H)?; Anal. Calcd for C26H14N2O3: C, 77.60;
H, 3.51; N, 6.96 %. Found: C, 77.52; H, 3.47; N, 6.90 %.
7-(3-Bromophenyl)-8H-benzo[h]indeno[1,2-b]quinoline-8-one (4h)
IR (KBr, cm-1): 3,074, 2,925, 1,705, 1,602, 1,580, 1,570, 1,484, 1,451, 1,266,
1
1,019, 837, 812, 744; H NMR (500 MHz, CDCl3) d: 7.33–7.52 (m, 6H, Ar–H),
7.59–7.71 (m, 5H, Ar–H), 7.84 (d, J = 7.8 Hz, 1H), 8.10 (d, J = 7.4 Hz, 1H), 9.35
(d, J = 8.0 Hz, 1H) ppm; 13C NMR (125 MHz, CDCl3) d: 121.9, 123.7, 124.3,
124.9, 125.5, 126.4, 127.4, 127.8, 128.6, 129.2, 129.6, 130.0, 131.7, 133.6, 135.1,
135.7, 137.1, 139.6, 140.3, 143.0, 146.0, 147.4, 148.8, 162.4, 192.7 ppm; MS(ESI):
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S. S. Mansoor et al.
m/z 436.9 (M ? H)?; Anal. Calcd for C26H14BrNO: C, 71.57; H, 3.24; N, 3.21 %.
Found: C, 71.50; H, 3.21; N, 3.17 %.
7-(4-Nitrophenyl)-8H-benzo[h]indeno[1,2-b]quinoline-8-one (4i)
IR (KBr, cm-1): 3,072, 2,933, 1,715, 1,610, 1,577, 1,572, 1,480, 1,450, 1,266,
1
1,033, 840, 753; H NMR (500 MHz, CDCl3) d: 7.41 (d, J = 8.0 Hz, 2H, Ar–H),
7.52 (t, J = 7.6 Hz, 1H, Ar–H), 7.55–7.63 (m, 3H, Ar–H), 7.74–7.82 (m, 5H, Ar–
H), 7.90 (d, J = 7.6 Hz, 1H, Ar–H), 8.21 (d, J = 7.6 Hz, 1H, Ar–H), 9.33 (d,
J = 8.0 Hz, 1H, Ar–H) ppm; 13C NMR (125 MHz, CDCl3) d: 121.3, 123.9, 124.4,
124.7, 125.2, 125.9, 127.4, 127.6, 128.5, 129.4, 129.8, 130.7, 131.9, 133.7, 135.4,
135.6, 137.0, 139.4, 139.7, 143.1, 144.9, 147.4, 148.9, 162.5, 192.9 ppm; MS(ESI):
m/z 403 (M ? H)?; Anal. Calcd for C26H14N2O3: C, 77.60; H, 3.51; N, 6.96 %.
Found: C, 77.49; H, 3.44; N, 6.94 %.
7-(2,4-Dichlorophenyl)-8H-benzo[h]indeno[1,2-b]quinoline-8-one (4j)
IR (KBr, cm-1): 3,080, 1,711, 1,612, 1,576, 1,478, 1,101, 1,069, 852, 815, 798, 772,
1
744; H NMR (500 MHz, CDCl3) d: 7.34 (d, J = 8.5 Hz, 1H, Ar–H), 7.38 (d,
J = 8.5 Hz, 1H, Ar–H), 7.46–7.49 (m, 2H, Ar–H), 7.66–7.77 (m, 6H, Ar–H), 7.85
(d, J = 7.7 Hz, 1H, Ar–H), 8.11 (d, J = 7.4 Hz, 1H, Ar–H), 9.32 (d, J = 8.1 Hz,
1H, Ar–H) ppm; 13C NMR (125 MHz, CDCl3) d: 122.1, 122.9, 124.2, 124.6, 125.0,
125.8, 127.7, 127.9, 128.6, 129.4, 129.8, 130.7, 131.8, 133.6, 135.6, 136.3, 137.8,
139.6, 139.8, 143.1, 146.7, 147.6, 149.8, 160.7, 193.4 ppm; MS(ESI): m/z 426.9
(M ? H)?; Anal. Calcd for C26H13Cl2NO: C, 73.25; H, 3.07; N, 3.29 %. Found: C,
73.17; H, 3.03; N, 3.25 %.
7-(4-Bromophenyl)-8H-benzo[h]indeno[1,2-b]quinoline-8-one (4k)
IR (KBr, cm-1): 3,060, 1,705, 1,606, 1,570, 1,550, 1,480, 1,010, 995, 840, 810, 760,
1
740; H NMR (500 MHz, CDCl3) d: 7.32 (d, J = 8.2 Hz, 2H, Ar–H), 7.46 (t,
J = 7.5 Hz, 1H, Ar–H), 7.51 (d, J = 8.4 Hz, 1H, Ar–H), 7.62–7.76 (m, 7H, Ar–H),
7.82 (d, J = 7.8 Hz, 1H, Ar–H), 8.13 (d, J = 7.7 Hz, 1H, Ar–H), 9.36 (d,
J = 8.0 Hz, 1H, Ar–H) ppm; 13C NMR (125 MHz, CDCl3) d: 122.6, 123.3, 124.5,
124.9, 125.4, 126.0, 126.9, 127.3, 128.0, 128.7, 129.0, 129.7, 131.8, 134.2, 135.6,
136.1, 137.8, 139.4, 139.7, 143.0, 146.5, 147.7, 149.7, 160.5, 193.2 ppm; MS(ESI):
m/z 436.9 (M ? H)?; Anal. Calcd for C26H14BrNO: C, 71.57; H, 3.24; N, 3.21 %.
Found: C, 71.48; H, 3.18; N, 3.19 %.
7-(2-Methoxyphenyl)-8H-benzo[h]indeno[1,2-b]quinoline-8-one (4l)
IR (KBr, cm-1): 3,078, 1,714, 1,608, 1,582, 1,573, 1,471, 1,045, 832, 808, 792, 755,
1
734; H NMR (500 MHz, CDCl3) d: 3.74 (s, 3H, OCH3), 7.17 (d, J = 8.4 Hz, 1H,
Ar–H), 7.24 (t, J = 7.4 Hz, 1H, Ar–H), 7.35 (d, J = 7.5 Hz, 1H, Ar–H), 7.45–7.56
(m, 3H, Ar–H), 7.62–7.77 (m, 5H, Ar–H), 7.81 (d, J = 7.8 Hz, 1H), 8.11 (d,
J = 7.4 Hz, 1H, Ar–H), 9.35 (d, J = 8.0 Hz, 1H, Ar–H) ppm; 13C NMR (125 MHz,
123

Facile one-pot synthesis of a novel series
CDCl3) d: 55.2, 122.5, 123.3, 124.2, 124.9, 125.9, 126.7, 127.3, 127.5, 128.0, 128.9,
129.5, 130.2, 131.9, 134.1, 135.3, 136.3, 137.5, 139.5, 139.9, 143.2, 146.5, 147.6,
149.7, 160.6, 193.3 ppm; MS(ESI): m/z 388 (M ? H)?; Anal. Calcd for
C27H17NO2: C, 83.70; H, 4.42; N, 3.62 %. Found: C, 83.64; H, 4.37; N, 3.59 %.
7-(2-Chlorophenyl)-8H-benzo[h]indeno[1,2-b]quinoline-8-one (4m)
IR (KBr, cm-1): 3,064, 1,714, 1,611, 1,577, 1,570, 1,466, 1,043, 822, 811, 777, 750,
1
734; H NMR (500 MHz, CDCl3) d: 7.17–7.23 (m, 2H, Ar–H), 7.33–7.42 (m, 3H,
Ar–H), 7.46 (d, J = 8.0 Hz, 1H, Ar–H), 7.49–7.63 (m, 5H, Ar–H), 7.79 (d,
J = 7.7 Hz, 1H, Ar–H), 8.05 (d, J = 7.4 Hz, 1H, Ar–H), 9.31 (d, J = 8.0 Hz, 1H,
Ar–H) ppm; 13C NMR (125 MHz, CDCl3) d: 123.0, 123.8, 124.4, 124.7, 125.9,
126.7, 127.3, 127.8, 128.4, 129.4, 129.9, 130.7, 131.9, 133.8, 135.4, 136.5, 137.2,
139.6, 139.8, 143.2, 146.7, 147.6, 149.8, 160.8, 193.4 ppm; MS(ESI): m/z m/z 392.5
(M ? H)?; Anal. Calcd for C26H14ClNO: C, 79.69; H, 3.60; N, 3.57 %. Found: C,
79.55; H, 3.53; N, 3.56 %.
7-(3,4-Dichlorophenyl)-8H-benzo[h]indeno[1,2-b]quinoline-8-one (4n)
IR (KBr, cm-1): 3,085, 1,715, 1,605, 1,570, 1,470, 1,100, 1,065, 852, 840, 798, 772,
1
755; H NMR (500 MHz, CDCl3) d: 7.34 (d, J = 8.5 Hz, 1H, Ar–H), 7.38 (d,
J = 8.5 Hz, 1H, Ar–H), 7.47–7.52 (m, 2H, Ar–H), 7.65–7.80 (m, 6H, Ar–H), 7.88
(d, J = 7.7 Hz, 1H, Ar–H), 8.12 (d, J = 7.4 Hz, 1H, Ar–H), 9.37 (d, J = 8.1 Hz,
1H) ppm; 13C NMR (125 MHz, CDCl3) d: 122.4, 123.4, 124.1, 124.8, 125.7, 126.8,
127.4, 127.9, 128.7, 129.2, 129.7, 130.7, 131.6, 133.7, 135.5, 136.7, 137.8, 139.4,
139.9, 143.8, 146.7, 147.7, 148.5, 161.1, 193.1 ppm; MS(ESI): m/z 426.9
(M ? H)?; Anal. Calcd for C26H13Cl2NO: C, 73.25; H, 3.07; N, 3.29 %. Found:
C, 73.19; H, 3.01; N, 3.22 %.
Results and discussion
Our efforts to develop an efficient and environmentally benign method for synthesis
of 7-aryl-8H-benzo[h]indeno[1,2-b]quinoline-8-one derivatives focused initially on
three-component cyclocondensation of 1,3-indanedione (1 mmol) with 4-chloro-
benzaldehyde (1 mmol) and 1-naphthylamine (1 mmol) as model reaction.
In an initial endeavor, the model reaction was conducted in the presence of TBM
(10 mol%) with a variety of solvents (1,4-dioxane, CH3CN, CH3OH, C2H5OH, and
CHCl3) under reflux (Table 1, entries 1–5). The reaction was also performed in the
absence of solvent at 80 °C (Table 1, entry 6). The results indicated the solvents had
a significant effect on product yield. The best conversion was observed when the
reaction was performed under solvent-free conditions at 80 °C (Table 1, entry 6).
To further optimize the yield of the reaction, we performed experiments at room
temperature, 50, 60, 70, 80, and 90 °C (Table 1, entries 6–11). As shown in Table 1,
we found that high temperature could improve the reaction yield and shorten the
reaction time. On the basis of these results we selected solvent-free conditions for
123

S. S. Mansoor et al.
Table 1 Optimization of the reaction conditions for synthesis of 4b
Entry
Catalyst
Amount
(mol%)
Solvent
Temperature
(°C)
Time
(min)
Yield
(%)a
1
TBM
TBM
TBM
TBM
TBM
TBM
TBM
TBM
TBM
TBM
TBM
TBM
TBM
TBM
TBM
PFPAT
LiBr
10
10
10
10
10
10
10
10
10
10
10
0
1,4-Dioxane
CH3CN
Reflux
Reflux
Reflux
Reflux
Reflux
80
120
120
100
90
50
48
69
76
33
95
50
64
77
85
95
23
47
64
95
55
48
72
2
3
MeOH
4
EtOH
5
CHCl3
120
45
6
Solvent-free
Solvent-free
Solvent-free
Solvent-free
Solvent-free
Solvent-free
Solvent-free
Solvent-free
Solvent-free
Solvent-free
Solvent-free
Solvent-free
Solvent-free
7
rt
120
90
8
50
9
60
75
10
11
12
13
14
15
16
17
18
70
60
90
45
80
120
90
2
80
5
80
60
15
10
10
10
80
45
80
120
90
80
p-TSA
80
90
Reaction conditions: 1,3-indanedione (1 mmol), 4-chlorobenzaldehyde (1 mmol) and 1-naphthylamine
(1 mmol), solvent 5 mL
a
Isolated yields
one-pot reaction of 1,3-indanedione, aromatic aldehydes, and 1-naphthylamine at
80 °C to give corresponding substituted 7-aryl-8H-benzo[h]indeno[1,2-b]quinoline-
8-one derivatives (Table 1, entry 6). When 0, 2, 5, 10, and 15 mol% of TBM were
used, the yields were 21, 44, 67, 95, and 95 %, respectively, at 80 °C (Table 1,
entries 6 and 12–15). Because use of 15 mol% of TBM did not significantly increase
the yield (Table 1, entry 15), 10 mol% of TBM was sufficient (Table 1, entry 6).
Among the different catalysts tested (pentafluorophenylammonium triflate
(PFPAT), LiBr, p-toluene sulfonic acid, and TBM) TBM was the most efficient
in terms of reaction time and product yield (Table 1, entries 6 and 16–18).
To evaluate the scope of this catalytic transformation, the optimized reaction
conditions were subsequently applied to the reaction of 1,3-indanedione and
1-naphthylamine with a variety of different aromatic aldehydes (Table 2, entries
1–14). A wide range of aromatic aldehydes bearing either electron-donating or
electron-withdrawing substituents reacted successfully with 1,3-indanedione and
1-naphthylamine to give the corresponding 7-aryl-8H-benzo[h]indeno[1,2-b]quin-
oline-8-one derivatives in high yields and with short reaction times. The yields of
indeno[1,2-b]quinolines were strongly affected by the electronic nature and position
of the substituent on the aromatic aldehydes. Aldehydes with electron-withdrawing
123

Facile one-pot synthesis of a novel series
123

S. S. Mansoor et al.
123

Facile one-pot synthesis of a novel series
123

S. S. Mansoor et al.
123

Facile one-pot synthesis of a novel series
123

S. S. Mansoor et al.
123

Facile one-pot synthesis of a novel series
123

S. S. Mansoor et al.
HN
N
NHBr
BrHN
N
NHBr
H2N
N
NHBr
N
N
N
N
N
N
TBM
NHBr
NHBr
NHBr
TBM
TBMH
Br
TBM
O
TBM
O
+
Ar
H
Ar
H
a
H
O
Br
O
O
+ TBM
- TBM
+ TBMH
O
O
O
OH
OH
O
Br
Br
Ar
O
+
Ar
H
O
b
O
TBM
Br
Br
O
O
O
O
Route a
OH
Ar
OH
Ar
+
TBM
+ TBM
d
c
O
O
O
TBMH
OH
Ar
+
TBMH
-TBM
-H2O
Ar
O
f
e
TBM
NH2
Br
Br
O
O
O
Ar
+ TBM
NH
Ar
O
g
h
Scheme 3 Plausible mechanism for synthesis of 7-aryl-8H-benzo[h]indeno[1,2-b]quinoline-8-ones
123

Facile one-pot synthesis of a novel series
Br
O
O
O
Ar
Ar
NH2
TBM
NH2
+ TBM
O
i
j
TBM
Ar
O
O
O
Ar
NH2
+ TBM
O
H2N
Br
Br
l
k
TBM
O
O
N
Ar
O
N
Ar
Ar
-H2O
Oxidation
O
HN
H
Scheme 3 continued
substituents provided the desired indeno[1,2-b]quinolines in good yields (Table 2,
entries 2, 5, 9, and 11) whereas yields were slightly lower for aldehydes with
electron-donating substituents (entries 3, 4, and 12). Aldehydes with ortho
substituents gave slightly lower yields than those with para substituents (Table 2,
entries 12 and 13). Aliphatic aldehydes were not good substrates, the reactions did
not proceed.
A mechanistic rationale portraying the probable sequence of events in the
formation of 7-aryl-8H-benzo[h]indeno[1,2-b]quinoline-8-one using TBM as cata-
lyst is given in Scheme 3. In this reaction, the tribromomelamine could act as a
bifunctional catalyst [30] which would activate both the carbonyl oxygen of the
aldehyde and the acidic hydrogen of 1,3-indanedione. Because tribromomelamine
contains Br atoms that are attached to N atoms, it is likely that Br? would be
released in situ, and that this species would act as a catalyst in the reaction medium,
leading to a substantial increase in the electrophilicity of the aldehyde (intermediate
a).
It is proposed that tribromomelamine produces two different species, N2,N4-
dibromo-1,3,5-triazine-2,4,6-triamine (TBMH) and the anion remaining after
123

S. S. Mansoor et al.
O
O
H
O
O
O
Route b
TBM
Br
OH
Ar
Ar
NH2
TBM
O
O
O
O
Ar
NH2
+ TBM+
H2O
NH
Ar
j
TBM
Ar
- TBM
O
Ar
O
NH2
O
H2N
Br
O
l
Br
k
TBM
O
O
O
N
Ar
Ar
Ar
-H2O
Oxidation
O
HN
N
H
Scheme 3 continued
release of Br? from TBM (TBM-). The reaction proceeds by attack of 1,3-
indanedione on the activated carbonyl to afford intermediate b. This reaction
proceeds until formation of intermediate c. The reaction could continue via two
different routes. In route a, Michael addition results in formation of intermediates d,
e, f, g, and h. Route b proceeds via nucleophilic attack on the sp3 carbon atom, as
revealed in Scheme 3. Subsequent processes include cyclization, water removal,
and aromatization, leading to formation of 7-aryl-8H-benzo[h]indeno[1,2-b]quino-
line-8-ones.
123

Facile one-pot synthesis of a novel series
Table 3 Effects of the different catalysts used for synthesis of 7-aryl-8H-benzo[h]indeno[1,2-b]quino-
line-8-ones by condensation of 1,3-indanedione, benzaldehyde, and 1-naphthylamine
Entry Catalyst (amount)
Solvent
Temperature Time Yield Ref.
(h)
(°C)
(%)
1
2
3
4
5
[Fe(HSO4)3] (10 mol%)
DMSO
90
4
92
90
90
86
94
[24]
H6P2W18O62Á18H2O (10 mol%) Acetic acid
AMPS (15 mol%)
P(4-VPH)HSO4 (20 mg)
TBM (10 mol%)
Reflux
Reflux
Reflux
4
[21]
CH3CN
2
[23]
EtOH
2
[26]
Solvent-free 80
0.75
This work
Comparison of the reaction times and yields of this TBM-catalyzed synthesis of
7-aryl-8H-benzo[h]indeno[1,2-b]quinoline-8-one derivatives with those of methods
reported in the literature reveals the merit of this method for synthesis of the desired
products. In comparison with other catalysts used for the model reaction, TBM had
much greater activity, which resulted in short reaction times under mild reaction
conditions (Table 3). As shown in Table 3, compared with other reported catalysts
(ferric hydrogensulfate [Fe(HSO4)3] [24], H6P2W18O62Á18H2O [21], cross-linked
poly(2-acrylamido-2-methyl propane sulfonic acid (AMPS) [23], and poly(4-
vinylpyridinium)hydrogen sulfate [26]) TBM was superior in terms of yield and
reaction time.
Conclusions
An economic, rapid, and environmentally benign procedure has been developed for
one-pot synthesis of 7-aryl-8H-benzo[h]indeno[1,2-b]quinoline-8-one derivatives
by three-component reaction of 1,3-indanedione with aromatic aldehydes and
1-naphthylamine, under solvent-free conditions, with tribromomelamine as homo-
geneous catalyst. The method has several advantages, including short reaction
times, high yields, facile workup, and the absence of any hazardous organic
solvents, which makes it a useful and attractive procedure for synthesis of these
compounds. The procedure is also advantageous in the sense that, because it is
solvent-free, it is environmentally friendly.
Acknowledgments The author Mansoor is grateful to C. Abdul Hakeem College Management for
facilities and support.
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