Synthesis of a novel series of 7-hydroxy-10-aryl-10H-indeno[1,2-b]chromen-11-ones, indeno[1,2-b]naphtho[1,2-e]pyran-12(13H)-one, and indeno[1,2-b]naphtho[3,2-e]pyran-5,11,13-trione catalyzed by reusable polyvinylpolypyrrolidone-supported triflic acid

Article abstract of DOI:10.1007/s11164-015-1949-x

Polyvinylpolypyrrolidone-supported triflic acid (PVPP.OTf) has been used as a recyclable catalyst for synthesis of a series of 7-hydroxy-10-aryl-10H-indeno[1,2-b]chromen-11-one derivatives by condensation of aldehydes, resorcinol, and 2H-indene-1,3-dione. 13-Phenylindeno[1,2-b]naphtho[1,2-e]pyran-12(13H)-one and 12-phenyl-12H-indeno[1,2-b]naphtho[3,2-e]pyran-5,11,13-trione were also synthesized by condensation of benzaldehyde, β-naphthol or 2-hydroxynaphthalene-1,4-dione, and 2H-indene-1,3-dione with PVPP.OTf as catalyst. The heterogeneous catalyst was used for four runs. This method has the advantages of high yields, simple methodology, short reaction times, and easy work-up.

Full text of DOI:10.1007/s11164-015-1949-x

Res Chem Intermed
DOI 10.1007/s11164-015-1949-x
Synthesis of a novel series of 7-hydroxy-10-aryl-10H-
indeno[1,2-b]chromen-11-ones, indeno[1,2-
b]naphtho[1,2-e]pyran-12(13H)-one, and indeno
[1,2-b]naphtho[3,2-e]pyran-5,11,13-trione catalyzed
by reusable polyvinylpolypyrrolidone-supported
triflic acid
•
Syed Sheik Mansoor Majid Ghashang
Received: 11 October 2014 / Accepted: 3 February 2015
Ó Springer Science+Business Media Dordrecht 2015
Abstract Polyvinylpolypyrrolidone-supported triflic acid (PVPP.OTf) has been
used as a recyclable catalyst for synthesis of a series of 7-hydroxy-10-aryl-10H-
indeno[1,2-b]chromen-11-one derivatives by condensation of aldehydes, resorcinol,
and 2H-indene-1,3-dione. 13-Phenylindeno[1,2-b]naphtho[1,2-e]pyran-12(13H)-
one and 12-phenyl-12H-indeno[1,2-b]naphtho[3,2-e]pyran-5,11,13-trione were also
synthesized by condensation of benzaldehyde, b-naphthol or 2-hydroxynaphthalene-
1,4-dione, and 2H-indene-1,3-dione with PVPP.OTf as catalyst. The heterogeneous
catalyst was used for four runs. This method has the advantages of high yields,
simple methodology, short reaction times, and easy work-up.
Keywords Polyvinylpolypyrrolidone-supported triflic acid (PVPP.OTf) Á
Indeno[1,2-b]chromen-11-one Á 2H-Indene-1,3-dione Á Recyclable catalyst
Introduction
Multi-component reactions (MCRs) have become very popular for discovery of
biologically active novel compounds and are of great interest in diversity-oriented
synthesis, especially generation of compound libraries for screening purposes [1].
The development of environmentally benign, efficient, and economical methods for
synthesis of biologically interesting compounds remains a significant challenge in
synthetic chemistry. Performing MCRs in water as reaction medium is one of the
S. S. Mansoor (&)
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, M. Ghashang
most suitable methods, and a major aspect of green chemistry, because they enable
simple and rapid access to a large number of organic molecules by sustainable
methods [2, 3].
In recent years, 4H-pyrans and their derivatives have attracted much interest
because of their useful biological and pharmacological activity, for example
anticoagulant, spasmolytic, anticancer, and antianaphylactin properties [4]. Fur-
thermore, substituted 4H-pyrans also constitute structural units of several natural
products [5]. The 4H-pyrans also antitumor [6], antibacterial [7], antioxidant [8],
antigenotoxic [9], and antiangiogenic activity [10].
Considering the importance of these compounds, numerous methods have been
reported for synthesis of 4H-pyran derivatives with a variety of catalysts, for
example CuO–CeO2 nanocomposite [11], carbon-based solid acid [12], tetramethy-
lammonium hydroxide [13], SB-DABCO [14], silica-bonded N-propylpiperazine
sodium n-propionate [15], silica nanoparticles [16], and DBU under microwave-
irradiation [17].
Among different pyran structures, the indenopyran nucleus, in particular, is a
‘‘privileged medicinal scaffold’’ used for development of pharmaceutical agents
with a variety of applications [7, 18–20]. Compounds containing this structure have
a wide range of pharmacological properties, including antidepressant [21], antiulcer
[22], and antiallergenic [23] activity. Consequently, methods for synthesis of novel
indenopyrans are of particular interest to organic and medicinal chemists [24–26].
Trifluoromethanesulfonic acid or triflic acid is a well known Brønsted superacid
which has been extensively studied as a catalyst in a wide range of organic
transformations, including stereoselective Friedel–Crafts aminoalkylation of indoles
and pyrroles [27], annelation of aromatic sulfonamides [28], synthesis of b-
acetamido ketones [29], acylation of alcohols [30], cyclization of unsaturated
alcohols [31], and addition of allylboranes to aldehydes [32].
However, TfOH is highly corrosive and is a fuming liquid, so there are
difficulties involved in storage, transportation, handling, and waste disposal, thus
severely restricting its application in industry. Immobilization of triflic acid on
inorganic materials, for example silica gel, affords solid acids that can be easily
handled, because they are invariably low-toxicity, non-corrosive, free-flowing
powders with superior thermal and mechanical stability under catalytic conditions.
Silica gel-supported triflic acid is readily prepared by simple absorption of TfOH on
chromatographic silica gel. This solid acid has been used as an efficient catalyst for
heterogeneous addition of a variety of b-dicarbonyl compounds to alcohols and
alkenes, affording moderate to excellent yields under solvent-free conditions or in
nitromethane. Moreover, this silica gel supported catalyst results in higher reaction
yields than homogeneous catalysts and can be readily recovered and reused up to six
times with almost unchanged reactivity and yields [33]. Processes for immobiliza-
tion of TfOH on solid supports have already been reported [34–37].
Polymer-supported reagents have attracted much attention in recent years for
development of novel organic reaction methods [38, 39], because their heteroge-
neous nature enables reactions to be conducted under mild conditions and the
organic products to be isolated with relative ease from the reaction media.
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Reusable polyvinylpolypyrrolidone-supported triflic acid
Furthermore, the toxicity of these systems is low. Taken together, the special
properties associated with polymeric reagents prompted us to investigate their
application to organic synthesis.
Polyvinylpolypyrrolidone has strong binding affinity for small molecules. An
efficient procedure for acetylation of alcohols and phenols with acetic anhydride in the
presence of a catalytic amount of polyvinylpolypyrrolidone tribromide has been
successfully developed [40]. Trimethylsilylation of alcohols has been achieved with
1,1,1,3,3,3-hexamethyldisilazane (HMDS) as silylating agent, in the presence of
polyvinylpolypyrrolidone tribromide in acetonitrile at room temperature [41].
Polyvinylpolypyrrolidone-supported boron trifluoride (PVPP-BF3) has been studied
for synthesis of 4-methylcoumarin by the Pechmann reaction [42], for synthesis of
14-aryl-14H-dibenzo[a,j]xanthenes and bis(naphthalen-2-yl-sulfane) derivatives
[43], for preparation of amides by reaction of nitriles with benzhydrol and tertiary
alcohols [44], and for oxidation of sulfides to sulfones in the presence of 35 %
hydrogen peroxide [45]. Polyvinylpolypyrrolidone-supported hydrogen peroxide
(PVP-H2O2), silica–sulfuric acid (SiO2OSO3H), and catalytic amounts of ammonium
bromide (NH4Br) have been introduced as green media for in-situ generation of the
bromonium ion (Br?), which was used for selective oxidation of sulfides and alcohols
to sulfoxides and carbonyl compounds, respectively [46]. Polyvinylpolypyrrolidone-
supported triflic acid (PVPP.OTf) has recently attracted much attention as an efficient
catalyst for construction of carbon–carbon and carbon–heteroatom bonds [47–49],
because of its eco-friendly nature, ease of handling, high reactivity, and easy work-up
procedures. PVPP.OTf has been reported as a recyclable heterogeneous solid-acid
catalyst for synthesis of tetrahydrobenzo[a]xanthen derivatives [47], synthesis of bis-
indolyl methane derivatives [48], and synthesis of quinoxaline derivatives [49].
As a continuation of our studies on the use of solid catalysts in organic transformations
[50–53], we report an efficient method for synthesis of a series of 7-hydroxy-10-aryl-10H-
indeno[1,2-b]chromen-11-one derivatives, with polyvinylpolypyrrolidone-supported tri-
flic acid (PVPP.OTf) as catalyst, by three-component condensation of aromatic aldehydes,
resorcinol, and 2H-indene-1,3-dione in water at 80 °C (Scheme 1). We have also used
PVPP.OTf as catalyst for condensation of benzaldehyde, b-naphthol or 2-hydroxynaph-
thalene-1,4-dione, and 2H-indene-1,3-dione for synthesis of 13-phenylindeno[1,2-
b]naphtha[1,2-e]pyran-12(13H)-one and 12-phenyl-12H-indeno[1,2-b]naphtho[3,2-e]
pyran-5,11,13-trione under similar conditions (Scheme 2).
Experimental
Apparatus 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 acquired by use of a
123

S. S. Mansoor, M. Ghashang
CHO
R1
R1
PVPP.OTf
(30 mg)
O
O
1a-n
+
Water
80 oC
HO
O
4a-n
HO
OH
3
O
2
*
*
CF3SO3
N
O
PVPP.OTf
H
Scheme 1 Reaction of aldehyde, resorcinol, and 2H-indene-1,3-dione for synthesis of a series of
7-hydroxy-10-aryl-10H-indeno[1,2-b]chromen-11-one derivatives
OH
O
CHO
4
O
5a
PVPP.OTf
(30 mg)
1a
O
O
O
+
Water
80 oC
O
O
O
OH
6
3
O
O
7a
*
*
O
CF3SO3
N
PVPP.OTf
H
Scheme 2 Reaction of benzaldehyde, b-naphthol or 2-hydroxynaphthalene-1,4-dione, and 2H-indene-
1,3-dione for synthesis of 13-aryl-indeno[1,2-b]naphtha[1,2-e]pyran-12(13H)-one and 12-aryl-12H-
indeno[1,2-b]naphtho[3,2-e]pyran-5,11,13-trione
Varian Saturn 2000 GC–MS instrument. Elemental analysis were performed by
means of a Perkin–Elmer 2400 CHN elemental analyzer.
Preparation of polyvinylpolypyrrolidone triflate (PVPP.OTf)
Polyvinylpolypyrrolidone triflate was prepared as reported elsewhere [47]. TfOH
(2.0 g, 13 mmol) was added to a suspension of polyvinylpolypyrrolidone (3.0 g) in
toluene (35 mL) and the mixture was stirred magnetically for 60 min at room
temperature. The toluene was removed under reduced pressure and the residue was
dried at 110 °C for 2 h to afford PVPP.OTf as a white powder. The number of H?
sites on PVPP.OTf, determined by acid–base titration, was 10 mequiv/g.
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Reusable polyvinylpolypyrrolidone-supported triflic acid
General procedure for preparation of 7-hydroxy-10-aryl-10H-indeno[1,2-
b]chromen-11-one derivatives
A mixture of aldehyde (1 mmol), resorcinol (1 mmol), and 2H-indene-1,3-dione
(1 mmol) was added to PVPP.OTf (30 mg), and the mixture was stirred at 80 °C in
5 ml water for an appropriate time. The reaction was monitored by TLC. On
completion of the reaction the mixture was diluted with CH2Cl2 (20 mL), and
filtered to recover the catalyst. The filtrate was then collected and evaporated to
dryness to give the crude product, which was purified by silica gel column
chromatography with CH2Cl2 as mobile phase.
Spectral data for compounds 4a–n
7-Hydroxy-10-phenyl-10H-indeno[1,2-b]chromen-11-one (4a)
1
IR (KBr, cm-1): 3,444, 2,977, 1,655, 1,596, 1,377, 1,222, 1,198, 1,074, 795; H
NMR (500 MHz, DMSO-d6): d 4.66 (s, 1H, CH), 6.62 (d, J = 4.2 Hz, 1H, Ar–H),
6.80 (dd, J = 4.2 Hz, J = 8.2 Hz, 1H, Ar–H), 6.92 (d, J = 8.2 Hz, 1H, Ar–H),
7.14–7.30 (m, 5H, Ar–H), 7.70–7.88 (m, 4H, Ar–H), 9.69 (s, 1H, OH) ppm; 13C
NMR (125 MHz, DMSO-d6): d 31.2, 104.5, 105.1, 110.7, 124.3, 125.9, 126.6,
128.3, 128.7, 129.7, 130.2, 134.3, 135.0, 136.6, 144.0, 156.0, 159.0, 162.7,
189.3 ppm. MS (ESI): m/z 327 [M ? H]?. Anal. Calcd. for C22H14O3: C, 80.98; H,
4.29 %. Found: C, 80.87; H, 4.24 %.
7-Hydroxy-10-(4-chlorophenyl)-10H-indeno[1,2-b]chromen-11-one (4b)
1
IR (KBr, cm-1): 3,438, 2,972, 1,652, 1,597, 1,378, 1,224, 1,194, 1,066, 812; H
NMR (500 MHz, DMSO-d6): d 4.65 (s, 1H, CH), 6.61 (d, J = 4.1 Hz, 1H, Ar–H),
6.81 (dd, J = 4.1 Hz, J = 8.0 Hz, 1H, Ar–H), 6.94 (d, J = 8.0 Hz, 1H, Ar–H), 7.11
(d, 2H, J = 8.0 Hz, Ar–H), 7.34 (d, 2H, J = 8.0 Hz, Ar–H), 7.73–7.89 (m, 4H, Ar–
H), 9.74 (s, 1H, OH) ppm; 13C NMR (125 MHz, DMSO-d6): d 31.1, 104.1, 104.8,
111.0, 124.5, 125.8, 126.5, 128.5, 128.9, 129.5, 130.7, 134.4, 135.1, 136.3, 144.1,
156.2, 159.2, 162.5, 189.0 ppm. MS (ESI): m/z 361.4 [M ? H]?. Anal. Calcd. for
C22H13ClO3: C, 73.24; H, 3.61 %. Found: C, 73.19; H, 3.57 %.
7-Hydroxy-10-(4-methylphenyl)-10H-indeno[1,2-b]chromen-11-one (4c)
1
IR (KBr, cm-1): 3,442, 2,966, 1,647, 1,590, 1,375, 1,227, 1,193, 1,065, 816; H
NMR (500 MHz, DMSO-d6): d 2.14 (s, 3H, CH3), 4.59 (s, 1H, CH), 6.64 (d,
J = 4.1 Hz, 1H, Ar–H), 6.83 (dd, J = 4.1 Hz, J = 8.2 Hz, 1H, Ar–H), 6.93 (d,
J = 8.2 Hz, 1H, Ar–H), 7.09 (d, 2H, J = 8.1 Hz, Ar–H), 7.30 (d, 2H, J = 8.1 Hz,
Ar–H), 7.69–7.85 (m, 4H, Ar–H), 9.76 (s, 1H, OH) ppm; 13C NMR (125 MHz,
DMSO-d6): d 20.9, 31.2, 104.0, 104.6, 111.1, 124.2, 126.2, 126.8, 128.2, 128.9,
129.3, 130.4, 134.4, 134.9, 136.1, 144.0, 155.7, 158.6, 162.3, 188.7 ppm. MS (ESI):
m/z 341 [M ? H]?. Anal. Calcd. for C23H16O3: C, 81.18; H, 4.71 %. Found: C,
81.11; H, 4.67 %.
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S. S. Mansoor, M. Ghashang
7-Hydroxy-10-(4-methoxyphenyl)-10H-indeno[1,2-b]chromen-11-one (4d)
1
IR (KBr, cm-1): 3,430, 2,968, 1,648, 1,590, 1,375, 1,219, 1,192, 1,070, 788; H
NMR (500 MHz, DMSO-d6): d 3.64 (s, 3H, OCH3), 4.60 (s, 1H, CH), 6.68 (d,
J = 4.1 Hz, 1H, Ar–H), 6.80 (dd, J = 4.1 Hz, J = 8.2 Hz, 1H, Ar–H), 6.92 (d,
J = 8.2 Hz, 1H, Ar–H), 7.21 (d, 2H, J = 8.0 Hz, Ar–H), 7.32 (d, 2H, J = 8.0 Hz,
Ar–H), 7.71–7.83 (m, 4H, Ar–H), 9.66 (s, 1H, OH) ppm; 13C NMR (125 MHz,
DMSO-d6): d 30.9, 54.9, 104.3, 105.1, 110.7, 124.1, 126.3, 126.8, 128.4, 128.8,
129.2, 130.5, 134.3, 134.9, 136.2, 143.7, 155.4, 158.7, 162.4, 188.5 ppm. MS (ESI):
m/z 357 [M ? H]?. Anal. Calcd. for C23H16O4: C, 77.53; H, 4.49 %. Found: C,
77.50; H, 4.45 %.
7-Hydroxy-10-(4-bromophenyl)-10H-indeno[1,2-b]chromen-11-one (4e)
1
IR (KBr, cm-1): 3,436, 2,969, 1,640, 1,591, 1,374, 1,218, 1,189, 1,077, 794; H
NMR (500 MHz, DMSO-d6): d 4.66 (s, 1H, CH), 6.67 (d, J = 4.1 Hz, 1H, Ar–H),
6.82 (dd, J = 4.1 Hz, J = 8.1 Hz, 1H, Ar–H), 6.91 (d, J = 8.1 Hz, 1H, Ar–H), 7.18
(d, 2H, J = 8.1 Hz, Ar–H), 7.39 (d, 2H, J = 8.1 Hz, Ar–H), 7.75–7.88 (m, 4H, Ar–
H), 9.78 (s, 1H, OH) ppm; 13C NMR (125 MHz, DMSO-d6): d 30.8, 103.9, 104.8,
110.5, 124.4, 126.4, 126.9, 128.6, 128.9, 129.6, 130.6, 134.6, 135.2, 136.4, 143.5,
155.6, 158.7, 162.2, 188.3 ppm. MS (ESI): m/z 405.8 [M ? H]?. Anal. Calcd. for
C22H13BrO3: C, 65.20; H, 3.21 %. Found: C, 65.12; H, 3.19 %.
7-Hydroxy-10-(4-nitrophenyl)-10H-indeno[1,2-b]chromen-11-one (4f)
1
IR (KBr, cm-1): 3,438, 2,973, 1,651, 1,595, 1,373, 1,219, 1,189, 1,075, 822; H
NMR (500 MHz, DMSO-d6): d 4.62 (s, 1H, CH), 6.63 (d, J = 4.2 Hz, 1H, Ar–H),
6.81 (dd, J = 4.2 Hz, J = 8.1 Hz, 1H, Ar–H), 6.90 (d, J = 8.1 Hz, 1H, Ar–H), 7.17
(d, 2H, J = 8.1 Hz, Ar–H), 7.31 (d, 2H, J = 8.1 Hz, Ar–H), 7.74–7.90 (m, 4H, Ar–
H), 9.77 (s, 1H, OH) ppm; 13C NMR (125 MHz, DMSO-d6): d 31.1, 104.3, 104.9,
110.8, 124.6, 126.1, 126.9, 128.5, 128.8, 129.4, 130.6, 134.7, 135.3, 136.4, 143.6,
155.4, 158.8, 162.7, 188.4 ppm. MS (ESI): m/z 372 [M ? H]?. Anal. Calcd. for
C22H13NO5: C, 71.16; H, 3.50; N, 3.77 %. Found: C, 71.11; H, 3.47; N, 3.78 %.
7-Hydroxy-10-(4-fluorophenyl)-10H-indeno[1,2-b]chromen-11-one (4g)
1
IR (KBr, cm-1): 3,433, 2,974, 1,647, 1,594, 1,377, 1,221, 1,187, 1,073, 806; H
NMR (500 MHz, DMSO-d6): d 4.61 (s, 1H, CH), 6.69 (d, J = 4.2 Hz, 1H, Ar–H),
6.79 (dd, J = 4.2 Hz, J = 8.0 Hz, 1H, Ar–H), 6.93 (d, J = 8.0 Hz, 1H, Ar–H), 7.19
(d, 2H, J = 8.0 Hz, Ar–H), 7.39 (d, 2H, J = 8.0 Hz, Ar–H), 7.77–7.94 (m, 4H, Ar–
H), 9.69 (s, 1H, OH) ppm; 13C NMR (125 MHz, DMSO-d6): d 31.1, 104.2, 104.9,
110.3, 124.8, 126.3, 127.0, 128.3, 128.7, 129.3, 130.4, 134.5, 135.0, 136.5, 143.7,
155.8, 158.9, 162.6, 188.2 ppm. MS (ESI): m/z 345 [M ? H]?. Anal. Calcd. for
C22H13FO3: C, 76.74; H, 3.78 %. Found: C, 76.70; H, 3.75 %.
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Reusable polyvinylpolypyrrolidone-supported triflic acid
7-Hydroxy-10-(3-nitrophenyl)-10H-indeno[1,2-b]chromen-11-one (4h)
1
IR (KBr, cm-1): 3,443, 2,975, 1,649, 1,590, 1,379, 1,225, 1,190, 1,069, 822; H
NMR (500 MHz, DMSO-d6): d 4.68 (s, 1H, CH), 6.68 (d, J = 4.1 Hz, 1H, Ar–H),
6.81 (dd, J = 4.1 Hz, J = 8.1 Hz, 1H, Ar–H), 6.92 (d, J = 8.1 Hz, 1H, Ar–H),
7.22–7.41 (m, 4H, Ar–H), 7.72–7.84 (m, 4H, Ar–H), 9.73 (s, 1H, OH) ppm; 13C
NMR (125 MHz, DMSO-d6): d 31.3, 103.9, 104.6, 110.4, 124.4, 126.2, 127.0,
128.3, 128.6, 129.7, 130.2, 134.5, 135.1, 136.7, 143.5, 155.7, 159.0, 162.4,
189.1 ppm. MS (ESI): m/z 372 [M ? H]?. Anal. Calcd. for C22H13NO5: C, 71.16;
H, 3.50; N, 3.77 %. Found: C, 71.09; H, 3.45; N, 3.74 %.
7-Hydroxy-10-(2-chlorophenyl)-10H-indeno[1,2-b]chromen-11-one (4i)
1
IR (KBr, cm-1): 3,441, 2,974, 1,646, 1,593, 1,369, 1,226, 1,189, 1,068, 794; H
NMR (500 MHz, DMSO-d6): d 4.66 (s, 1H, CH), 6.69 (d, J = 4.3 Hz, 1H, Ar–H),
6.82 (dd, J = 4.1 Hz, J = 8.2 Hz, 1H, Ar–H), 6.94 (d, J = 8.2 Hz, 1H, Ar–H),
7.24–7.40 (m, 4H, Ar–H), 7.78–7.96 (m, 4H, Ar–H), 9.77 (s, 1H, OH) ppm; 13C
NMR (125 MHz, DMSO-d6): d 30.7, 104.2, 104.5, 111.2, 124.3, 125.8, 126.5,
128.3, 128.9, 129.6, 130.9, 134.6, 134.7, 136.3, 143.7, 156.0, 159.2, 162.3,
189.0 ppm. MS (ESI): m/z 361.4 [M ? H]?. Anal. Calcd. for C22H13ClO3: C,
73.24; H, 3.61 %. Found: C, 73.16; H, 3.58 %.
7-Hydroxy-10-(2-fluorophenyl)-10H-indeno[1,2-b]chromen-11-one (4j)
1
IR (KBr, cm-1): 3,448, 2,972, 1,644, 1,594, 1,366, 1,219, 1,200, 1,070, 830; H
NMR (500 MHz, DMSO-d6): d 4.60 (s, 1H, CH), 6.64 (d, J = 4.1 Hz, 1H, Ar–H),
6.81 (dd, J = 4.1 Hz, J = 8.2 Hz, 1H, Ar–H), 6.90 (d, J = 8.2 Hz, 1H, Ar–H),
7.20–7.38 (m, 4H, Ar–H), 7.75–7.92 (m, 4H, Ar–H), 9.64 (s, 1H, OH) ppm; 13C
NMR (125 MHz, DMSO-d6): d 30.8, 104.2, 105.2, 110.5, 124.3, 126.0, 126.6,
128.1, 128.9, 129.6, 131.2, 134.4, 134.9, 136.5, 143.4, 156.0, 159.2, 162.4,
188.6 ppm. MS (ESI): m/z 345 [M ? H]?. Anal. Calcd. for C22H13FO3: C, 76.74;
H, 3.78 %. Found: C, 76.68; H, 3.77 %.
7-Hydroxy-10-(2,4-dichlorophenyl)-10H-indeno[1,2-b]chromen-11-one (4k)
1
IR (KBr, cm-1): 3,437, 2,969, 1,649, 1,597, 1,365, 1,218, 1,202, 1,072, 832; H
NMR (500 MHz, DMSO-d6): d 4.65 (s, 1H, CH), 6.65 (d, J = 4.1 Hz, 1H, Ar–H),
6.82 (dd, J = 4.1 Hz, J = 8.2 Hz, 1H, Ar–H), 6.93 (d, J = 8.2 Hz, 1H, Ar–H),
7.04–7.09 (m, 2H, Ar–H), 7.30–7.35 (m, 1H, Ar–H), 7.73–7.90 (m, 4H, Ar–H), 9.66
(s, 1H, OH) ppm; 13C NMR (125 MHz, DMSO-d6): d 31.0, 104.4, 105.1, 110.7,
124.4, 126.1, 126.5, 128.2, 128.8, 129.4, 131.3, 134.5, 134.9, 136.6, 144.2, 155.8,
158.7, 162.7, 188.8 ppm. MS (ESI): m/z 395.9 [M ? H]?. Anal. Calcd. for
C22H12Cl2O3: C, 66.85; H, 3.04 %. Found: C, 66.80; H, 3.05 %.
123

S. S. Mansoor, M. Ghashang
7-Hydroxy-10-(3,4-dichlorophenyl)-10H-indeno[1,2-b]chromen-11-one (4l)
1
IR (KBr, cm-1): 3,436, 2,974, 1,649, 1,588, 1,368, 1,222, 1,196, 1,074, 786; H
NMR (500 MHz, DMSO-d6): d 4.67 (s, 1H, CH), 6.66 (d, J = 4.2 Hz, 1H, Ar–H),
6.81 (dd, J = 4.2 Hz, J = 8.0 Hz, 1H, Ar–H), 6.89 (d, J = 8.0 Hz, 1H, Ar–H),
7.12–7.21 (m, 2H, Ar–H), 7.28–7.36 (m, 1H, Ar–H), 7.74–7.89 (m, 4H, Ar–H), 9.68
(s, 1H, OH) ppm; 13C NMR (125 MHz, DMSO-d6): d 31.3, 104.0, 105.1, 110.6,
124.6, 125.9, 127.0, 128.2, 128.7, 129.8, 131.0, 134.3, 134.8, 136.6, 144.1, 155.7,
158.5, 163.0, 188.7 ppm. MS (ESI): m/z 395.9 [M ? H]?. Anal. Calcd. for
C22H12Cl2O3: C, 66.85; H, 3.04 %. Found: C, 66.77; H, 3.00 %.
7-Hydroxy-10-(3-chlorophenyl)-10H-indeno[1,2-b]chromen-11-one (4m)
1
IR (KBr, cm-1): 3,435, 2,976, 1,643, 1,590, 1,370, 1,219, 1,194, 1,075, 796; H
NMR (500 MHz, DMSO-d6): d 4.68 (s, 1H, CH), 6.64 (d, J = 4.1 Hz, 1H, Ar–H),
6.82 (dd, J = 4.1 Hz, J = 8.2 Hz, 1H, Ar–H), 6.94 (d, J = 8.2 Hz, 1H, Ar–H),
7.17–7.31 (m, 4H, Ar–H), 7.70–7.84 (m, 4H, Ar–H), 9.70 (s, 1H, OH) ppm; 13C
NMR (125 MHz, DMSO-d6): d 31.4, 104.3, 105.2, 110.9, 124.7, 125.8, 126.8,
128.3, 128.9, 129.8, 131.2, 134.3, 134.9, 136.5, 144.2, 155.9, 158.7, 163.1,
188.5 ppm. MS (ESI): 361.45 [M ? H]?. Anal. Calcd. for C22H13ClO3: C, 73.24;
H, 3.61 %. Found: C, 73.15; H, 3.59 %.
7-Hydroxy-10-(3-bromophenyl)-10H-indeno[1,2-b]chromen-11-one (4n)
1
IR (KBr, cm-1): 3,432, 2,970, 1,645, 1,592, 1,370, 1,217, 1,188, 1,073, 822; H
NMR (500 MHz, DMSO-d6): d 4.63 (s, 1H, CH), 6.68 (d, J = 4.1 Hz, 1H, Ar–H),
6.82 (dd, J = 4.1 Hz, J = 8.2 Hz, 1H, Ar–H), 6.92 (d, J = 8.2 Hz, 1H, Ar–H),
7.21–7.37 (m, 4H, Ar–H), 7.72–7.86 (m, 4H, Ar–H), 9.68 (s, 1H, OH) ppm; 13C
NMR (125 MHz, DMSO-d6): d 30.8, 104.2, 104.9, 111.0, 124.5, 126.4, 126.9,
128.4, 128.9, 129.7, 131.0, 134.6, 135.2, 136.4, 144.0, 155.6, 158.6, 162.7,
188.4 ppm. MS (ESI): m/z 405.8 [M ? H]?. Anal. Calcd. for C22H13BrO3: C,
65.20; H, 3.21 %. Found: C, 65.15; H, 3.18 %.
General procedure for preparation of 13-phenylindeno[1,2-b]naphtho[1,2-
e]pyran-12(13H)-one and 12-phenyl-12H-indeno[1,2-b]naphtho[3,2-e]pyran-
5,11,13-trione
A mixture of aldehyde (1 mmol), b-naphthol or 2-hydroxynaphthalene-1,4-dione
(1 mmol), and 2H-indene-1,3-dione (1 mmol) was added to PVPP.OTf (30 mg),
and the mixture was stirred at 80 °C in water for an appropriate time. The reaction
was monitored by TLC. On completion of the reaction the mixture was diluted with
CH2Cl2 (20 mL), and filtered to recover the catalyst. The filtrate was then collected
and evaporated to dryness to give the crude product, which was purified by silica gel
column chromatography with CH2Cl2 as mobile phase.
123

Reusable polyvinylpolypyrrolidone-supported triflic acid
Spectral data for compounds 5a and 7a
13-Phenyl-indeno[1,2-b]naphtho[1,2-e]pyran-12(13H)-one (5a)
1
IR (KBr, cm-1): 2,988, 1,652, 1,590, 1,366, 1,224, 1,180; H NMR (500 MHz,
DMSO-d6): d 5.50 (s, 1H, CH), 7.07 (t, J = 7.4 Hz, 1H, Ar–H), 7.18 (t, J = 7.6 Hz,
2H, Ar–H), 7.26–7.40 (m, 8H, Ar–H), 7.61 (d, J = 8.8 Hz, 1H, Ar–H), 7.77–7.89
(m, 3H, Ar–H); 13C NMR (125 MHz, DMSO-d6): d 34.0, 111.6, 116.0, 116.8,
117.7, 120.4, 123.8, 125.0, 125.6, 126.6, 127.3, 128.0, 129.1, 130.8, 131.4, 132.0,
132.6, 133.0, 137.2, 143.0, 148.5, 166.7, 192.9; MS (ESI): m/z 361 [M ? H]?;
Anal. Calcd for C26H16O2: C, 86.66 %; H, 4.44 %; Found: C, 86.56 %; H 4.40 %.
12-Phenyl-12H-indeno[1,2-b]naphtho[3,2-e]pyran-5,11,13-trione (7a)
IR (KBr, cm-1): 3,044, 1,676, 1,660, 1,642; 1H NMR (500 MHz, DMSO-d6): d 5.38
(s, 1H, CH), 7.24–7.49 (m, 6H, Ar–H), 7.66–7.88 (m, 4H, Ar–H), 7.94 (d,
J = 8.4 Hz, 1H, Ar–H), 8.08 (d, J = 7.6 Hz, 1H, Ar–H), 8.22 (d, J = 7.6 Hz, 1H,
Ar–H) ppm; 13C NMR (125 MHz, DMSO-d6): d 38.9, 102.3, 120.6, 123.4, 123.7,
126.4, 126.8, 127.7, 128.2, 128.5, 130.6, 131.6, 134.4, 135.1, 136.3, 137.7, 144.4,
161.0, 172.0, 178.2, 182.6, 190.9 ppm. MS (ESI): m/z 391 [M ? H]?; Anal. Calcd
for C26H14O4: C, 79.99; H, 3.61 %; Found: C, 79.86 %; H, 3.57 %.
Results and discussion
In this paper we report a very efficient one-pot, three-component synthesis of
7-hydroxy-10-aryl-10H-indeno[1,2-b]chromen-11-one derivatives catalyzed by
PVPP.OTf. To optimize the reaction conditions, we chose the condensation of
4-chlorobenzaldehyde (1 mmol), resorcinol (1 mmol), and 2H-indene-1,3-dione
(1 mmol), catalyzed by PVPP.OTf under different conditions, as model reaction.
The results are summarized in Table 1. The effect of solvent, temperature, and
amount of catalyst was examined.
Several different solvents (methanol, ethanol, toluene, dichloromethane, tetrahy-
drofuran, acetonitrile and water) were screened in the model reaction (Table 1,
entries 1–7). The results suggested that a good yield was obtained in water (Table 1,
entry 7). To determine the effect of temperature on the model reaction, we studied
the effect of different temperatures (room temperature, 50, 60, 70, 80, and 90 °C;
Table 1, entries 7–12). As shown in Table 1, when the reaction temperature was
varied from room temperature to 80 °C product yield gradually increased, with the
highest yield being obtained at 80 °C, i.e. product yield was not affected by further
increasing the reaction temperature. To optimize catalyst loading the model reaction
was performed with 0, 10, 20, 30, and 40 mg PVPP.OTf at 80 °C in water (Table 1,
entries 7 and 13–16). Thirty milligrams of PVPP.OTf was found to be sufficient to
promote the reaction; larger amounts of the catalyst did not lead to any significant
improvement in product yield. It should be mentioned that when the reaction was
123

S. S. Mansoor, M. Ghashang
Table 1 Synthesis of 7-hydroxy-10-(4-chlorophenyl)-10H-indeno[1,2-b]chromen-11-one in the pres-
ence of the PVPP.OTf catalyst under different reaction conditions
Entry
Solvent
Catalyst (mg)
Temperature (°C)
Time (min)
Yield (%)a
1
MeOH
EtOH
30
30
30
30
30
30
30
30
30
30
30
30
0
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
80
120
120
120
150
150
150
75
70
77
61
49
37
45
94
44
57
75
84
94
–
2
3
Toluene
CH2Cl2
THF
4
5
6
CH3CN
Water
Water
Water
Water
Water
Water
Water
Water
Water
Water
7
8
RT
180
150
120
90
9
50
10
11
12
13
14
15
16
60
70
90
75
80
240
120
90
10
20
40
80
48
73
94
80
80
75
Reaction conditions: 4-chlorobenzaldehyde (1 mmol), resorcinol (1 mmol), 2H-indene-1,3-dione
(1 mmol)
a
Isolated yield
performed in the absence of catalyst over a long period of time (240 min) at 80 °C
in water, no yield of the product was obtained.
With these optimized conditions we proceeded to investigate the general scope
and applicability of this method with a variety of simple and readily available
aldehydes (Table 2). A wide range of aromatic aldehydes containing electron-
withdrawing (i.e., Cl, Br, and NO2) or electron-donating (i.e., CH3 and OCH3)
groups at the ortho, meta, or para position of the benzene ring were readily
converted into the corresponding 7-hydroxy-10-aryl-10H-indeno[1,2-b]chromen-
11-ones in good to excellent isolated yields with short reaction times under the
optimized conditions (Table 2, entries 1–14). Aromatic aldehydes with electron-
donating groups required longer reaction times and led to lower yields than those
with electron-withdrawing groups.
Inspired by the catalytic potential of PVPP.OTf, we extended the procedure by
using b-naphthol or 2-hydroxynaphthalene-1,4-dione instead of resorcinol. Con-
densation of benzaldehyde, b-naphthol or 2-hydroxynaphthalene-1,4-dione, and 2H-
indene-1,3-dione was conducted under similar reaction conditions. The desired
products, 13-phenylindeno[1,2-b]naphtho[1,2-e]pyran-12(13H)-one (5a) and
12-phenyl-12H-indeno[1,2-b]naphtho[3,2-e]pyran-5,11,13-trione (7a), were ob-
tained in 91 and 90 % yield, respectively (Table 3).
The reusability of the catalyst was evaluated. Briefly, the model reaction was
studied under the optimized reaction conditions. On completion of the reactions the
123

Reusable polyvinylpolypyrrolidone-supported triflic acid
Table 2 Synthesis of a variety of 7-hydroxy-10-aryl-10H-indeno[1,2-b]chromen-11-one derivatives
Entry
Aldehydes
Product
Time (min)
Yield (%)b
Mp (oC)
O
HO
O
4a
1
CHO
80
92
245 – 247
Cl
Cl
O
HO
O
4b
2
3
CHO
75
90
90
94
89
90
219 – 220
201 – 202
211 – 213
CH3
CH3
O
HO
O
4c
CHO
OCH3
OCH3
CHO
O
HO
O
4d
4
Br
Br
O
HO
HO
HO
O
4e
5
6
CHO
NO2
CHO
70
70
94
94
208 – 210
233 – 235
NO2
O
O
4f
F
F
O
O
4g
7
CHO
65
95
199 – 200
123

S. S. Mansoor, M. Ghashang
Table 2 continued
Entry
Aldehydes
Product
Time (min)
Yield (%)b
Mp (oC)
O2N
O
O2N
HO
O
4h
8
CHO
CHO
75
75
93
90
214 – 216
247 – 248
Cl
O
Cl
HO
O
4i
9
F
O
HO
F
O
4j
10
CHO
75
75
91
90
223 – 225
Cl
Cl
Cl
O
Cl
HO
O
4k
11
CHO
206 – 208
Cl
Cl
Cl
O
Cl
HO
O
4l
12
CHO
75
91
231 – 232
Cl
O
Cl
HO
O
4m
13
14
CHO
CHO
70
65
92
93
212 – 214
244 – 245
Br
O
Br
HO
O
4n
Reaction conditions: aldehydes (1 mmol), resorcinol (1 mmol) and 2H-indene-1,3-dione (1 mmol)
heating at 80 °C in the presence of PVPP.OTf (30 mg) in water
a
Isolated yields
123

Reusable polyvinylpolypyrrolidone-supported triflic acid
Table 3 Reaction of benzaldehyde, b-naphthol or 2-hydroxynaphthalene-1,4-dione, and 2H-indene-1,3-
dione for synthesis of 13-phenylindeno[1,2-b]naphtha[1,2-e]pyran-12(13H)-one and 12-phenyl-12H-in-
deno[1,2-b]naphtho[3,2-e]pyran-5,11,13-trione
Entry Hydroxy compound
Product
Time (min)
Yield (%)b
Mp (oC)
245 – 247
311 – 313
O
OH
O
5a
4
1
2
30
91
90
O
O
O
O
O
O
7a
OH
6
35
Reaction conditions: aldehydes (1 mmol), hydroxy compound (1 mmol) and 2H-indene-1,3-dione
(1 mmol) heating at 80 °C in the presence of PVPP.OTf (30 mg) in water
a
Isolated yields
96
Recyclability of catalyst
94%
94
93%
92
91%
90
88%
88
86
84
1
2
3
4
Runs
Fig. 1 Recyclability of the catalyst PVPP.OTf in the synthesis of 7-hydroxy-10-(4-chlorophenyl)-10H-
indeno[1,2-b]chromen-11-one in water at 80 °C
catalyst was separated by filtration, washed with diethyl ether, dried under vacuum,
and used again in the same reaction. This process was repeated over four runs and
the results showed that the reactions proceeded efficiently to give the desired
123

S. S. Mansoor, M. Ghashang
OH
O
O
HA
*
*
N
O
O
H
H
HA
O
OH
O
CHO
HA
H
OH
Route a
H
OH
O
O
OH
Route b
O
OH
OH
H
OH
O
OH OH
O
OH
HA
H
HA
OH2
O
OH2 OH
O
OH
OH
O
OH
-H2O
-H
OH
OH
OH
O
OH
OH
O
OH
OH
-H
-H2O
-H2O
O
O
OH
Scheme 3 Possible mechanism of formation of 7-hydroxy-10-aryl-10H-indeno[1,2-b]chromen-11-one
123

Reusable polyvinylpolypyrrolidone-supported triflic acid
products without any significant changes in yield of the products. As shown in
Fig. 1, the solid acid PVPP.OTf can be recycled at least four times without
significant decrease in catalytic activity; the yields ranged from 94 to 88 %.
A rational mechanism showing the probable sequence of events in the formation
of 7-hydroxy-10-aryl-10H-indeno[1,2-b]chromen-11-ones with PVPP.OTf as cata-
lyst is given in Scheme 3. The reaction could proceed via two different routes, i.e.,
routes a and b.
Conclusions
In summary, we have shown that PVPP.OTf is an efficient solid-acid catalyst for
synthesis of 7-hydroxy-10-aryl-10H-indeno[1,2-b]chromen-11-one derivatives by
condensation of aldehydes with resorcinol and 2H-indene-1,3-dione at 80 °C in
water. We also synthesized 13-phenylindeno[1,2-b]naphtho[1,2-e]pyran-12(13H)-
one and 12-phenyl-12H-indeno[1,2-b]naphtho[3,2-e]pyran-5,11,13-trione by con-
densation of benzaldehyde, b-naphthol or 2-hydroxynaphthalene-1,4-dione, and 2H-
indene-1,3-dione with PVPP.OTf as catalyst. The non-hazardous experimental
conditions, reusable catalyst, ease of reaction, short reaction times, high yields, and
metal-free catalyst are notable advantages of this procedure. It is, thus, a better and
more practical alternative to existing methods.
Acknowledgments The author Mansoor is grateful to the management of C. Abdul Hakeem College,
Melvisharam-632 509 (Tamil Nadu), India for facilities and support.
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