Synthesis of 12-aryl-12H-benzo[i][1,3]-dioxolo[4,5-b]xanthene-6,11-diones using silica sulfuric acid as an efficient and versatile catalyst under solvent-free conditions

Article abstract of DOI:10.1002/jhet.511

Some novel 12-aryl-12H-benzo[i][1,3]-dioxolo[4,5-b]xanthene-6,11-diones can be rapidly and efficiently synthesized in excellent yields by condensing a variety of aldehydes with 3,4-methylenedioxyphenol and 2-hydroxy-1,4- naphthoquinone in the presence of

Full text of DOI:10.1002/jhet.511

January 2011
Synthesis of 12-Aryl-12H-benzo[i][1,3]-dioxolo[4,5-b]xanthene-
6,11-diones Using Silica Sulfuric Acid as an Efficient and
Versatile Catalyst under Solvent-Free Conditions
83
Liqiang Wu,a* Shujun Chao,b and Fulin Yana
aSchool of Pharmacy, Xinxiang Medical University, Xinxiang, Henan 453003,
People’s Republic of China
bDepartment of Chemistry, Xinxiang Medical University, Xinxiang, Henan 453003,
People’s Republic of China
*E-mail: wliq870@163.com
Received May 1, 2010
DOI 10.1002/jhet.511
Published online 2 September 2010 in Wiley Online Library (wileyonlinelibrary.com).
Some novel 12-aryl-12H-benzo[i][1,3]-dioxolo[4,5-b]xanthene-6,11-diones can be rapidly and effi-
ciently synthesized in excellent yields by condensing a variety of aldehydes with 3,4-methylenedioxy-
phenol and 2-hydroxy-1,4-naphthoquinone in the presence of a catalytic amount of silica sulfuric acid
under solvent-free conditions. The simple experimental procedure, solvent-free reaction conditions, utili-
zation of an inexpensive and readily available catalyst, short period of conversion, and excellent yields
are the advantages of the present method. Furthermore, the catalyst can be recycled and reused three
times without significant loss of activity. The structures of the novel compounds are confirmed by IR,
1H-NMR, 13C-NMR, MS, and elemental analysis.
J. Heterocyclic Chem., 48, 83 (2011).
INTRODUCTION
ease of preparation, catalyst recycling, and ease of
handling [10]. Herein, we wish to report a facile,
three-component one-pot synthesis of novel 12-aryl-
12H-benzo[i][1,3]-dioxolo[4,5-b]xanthene-6,11-diones
(4a–h), which have not been published before, from
the condensation of 3,4-methylenedioxyphenol (1),
aldehydes (2), and 2-hydroxy-1,4-naphthoquinone (3)
in the presence of a catalytic amount of SSA under
solvent-free conditions (Scheme 1).
Xanthenes and benzoxanthenes have recently received
great attention because of their wide range of therapeu-
tic and biological properties, such as antibacterial [1],
antiviral [2], and anti-inflammatory activities [3]. Fur-
thermore, these compounds show useful spectroscopic
properties and are used as dyes [4], in laser technologies
[5], and in fluorescent materials for visualization of bio-
molecules [6]. A number of xanthene dyes are extracted
naturally from soil and plants, such as Indigofera lon-
geracemosa [7]. Thus, the development of new and sim-
ple synthetic methods for the efficient preparation of
new xanthenes is therefore an interesting challenge. 1,3-
Dioxolo[4,5-b]benzopyrans and their derivatives are
very important group of heterocyclic tricyclic systems,
which are widely found in natural products and have
potent anti-inflammatory activity [8,9].
RESULTS AND DISCUSSION
Initially, to optimize the reaction temperature, the
reaction of 3,4-methylenedioxyphenol (1, 1 mmol) with
benzaldehyde (2a, 1 mmol) and 2-hydroxy-1,4-naphtho-
quinone (3, 1 mmol) was studied under solvent-free con-
ditions in the presence of 5 mol % SSA at different tem-
peratures. The results are summarized in Table 1. As
shown in Table 1, the reaction at 100ꢀC proceeded in
highest yield.
In recent years, the use of heterogeneous catalysts has
received considerable interest in various disciplines
including organic synthesis. They are advantageous over
their homogeneous counterparts due to the prime
advantage that in most of the cases, the catalyst can be
recovered easily and reused. Silica sulfuric acid (SSA)
has been used as efficient heterogeneous catalysts for
many organic transformations because of their low cost,
Next, the study set out to determine optimal amount
of SSA, the reaction was carried out by varying amount
of the catalyst (Table 2). Maximum yield was obtained
with 0.05 equiv SSA. Further increase in the amount of
C
V
2010 HeteroCorporation

84
L. Wu, S. Chao, and F. Yan
Vol 48
Scheme 1
Table 2
The amounts of catalyst optimization for the synthesis of
12-phenyl-12H-benzo[i][1,3]-dioxolo[4,5-b]-xanthene-6, 11-dionea.
Entry
SSA (mol %)
Time (h)
Yield (%)b
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
5
8
49
62
69
74
86
85
86
84
3
2
2
the catalyst in the mentioned reaction did not have any
significant effect on the product yield.
1.5
1.5
1.5
1.5
1.5
Based on the optimized reaction conditions, a variety
of aldehydes reacted smoothly with 3,4-methylenedioxy-
phenol and 2-hydroxy-1,4-naphthoquinone in the pres-
ence of 0.05 equiv of SSA at 100ꢀC under solvent-free
conditions to furnish the corresponding 12-aryl-12H-ben-
zo[i][1,3]-dioxolo[4,5-b]xanthene-6,11-diones in high
yields. The reactions were rapid and in most cases, 12-
aryl-12H-benzo[i][1,3]-dioxolo[4,5-b]xanthene-6,11-dio-
nes formation was complete in 2.5 h with excellent
yields (Table 3). The structures of the products were
a Reaction conditions: 3,4-methylenedioxyphenol (1 mmol); benzalde-
hyde (1 mmol); 2-hydroxy-1,4-naphthoquinone (1 mmol); 100ꢀC; neat.
b Isolated yield.
A tentative mechanism for this transformation is pro-
posed in Scheme 2. It is conceivable that SSA catalyses
the formation of carbocation 5 in a reversible reaction
with the aromatic aldehyde. The higher reactivity of the
carbocation compared with the carbonyl species is used
to facilitate Knoevenagel condensation between arylal-
dehyde 2 and 2-hydroxy-1,4-naphthoquinone 3, via in-
termediate 6 and after dehydration, olefin 7 is produced.
Subsequent Michael-type addition of 3,4-methylenediox-
yphenol 1 to the olefin followed by cyclization and
dehydration to afford the corresponding products 4a–4h.
To emphasize the effect of catalyst, the model reac-
tion of 3,4-methylenedioxyphenol, benzaldehyde, and 2-
hydroxy-1,4-naphthoquinone was described and different
catalysts, which have been reported recently for synthe-
sis of benzoxanthenes [11], were subjected to the reac-
tion. All the reactions were run in the same conditions
1
established from their spectral properties (IR, H-NMR,
13C-NMR, and elemental analysis). All of the products 4
1
exhibited a singlet in their H spectra at d ¼ 5.03–5.52
1
for H-12, two singlet in their H spectra at d ¼ 5.98–
6.05 ppm for OCH2O, a distinguishing peak at d ¼
35.61–38.35 for C-12 in their 13C-NMR spectra, and a
distinguishing peak at d ¼ 98.42–99.06 for C-2 in their
13C-NMR spectra. There were two overlapping doublets
at d ¼ 7.98–8.15, which probably arise form the protons
peri to the quinone C¼¼O. The resonances of two none-
quivalent carbonyl groups in their 13C-NMR spectrum
of 4 appeared at d ¼ 177.92–178.35. In these experi-
ments, the catalyst was isolated by filtration and could
be recycled up to three times without significant loss of
activity (entry 1). When this reaction was carried out
with aliphatic aldehyde such as butanal or pentanal,
Table 3
1
thin-layer chromatography (TLC) and H-NMR spectra
Preparation of 12-aryl-12H-benzo[i][1,3]-dioxolo[4,5-b]xanthene-6,
11-diones catalyzed by SSAa.
of the reaction mixture showed a combination of starting
materials and numerous products, the yield of the
expected product was very poor (entries 9 and 10).
Time
(H)
Yield
(%)b
Entry
R
Product
1
2
3
C6H5
4-Cl-C6H4
1.5
2
1.5
1.5
2
4a
4b
4c
4d
4e
4f
4g
4h
4i
86 (84,82,79)c
Table 1
88
84
91
82
89
82
87
0
4-MeO-C6H4
4-Me-C6H4
4-NO2-C6H4
3-NO2-C6H4
3,4-Cl2-C6H3
2-F-C6H4
Temperature optimization for the synthesis of 12-phenyl-12H-
benzo[i][1,3]-dioxolo[4,5-b]-xanthene-6, 11-dione.
4
5
6
2
Entry
Temperature (ꢀC)
Time (h)
Yield (%)a
7
8
2.5
2
1
2
3
4
5
6
7
25
50
5
5
<10
22
9
10
CH3(CH2)2CH2
CH3(CH2)3CH2
4
4
80
90
2
2
65
69
4j
0
a Reaction conditions: 3,4-methylenedioxyphenol (1 mmol); aldehyde
(1 mmol); 2-hydroxy-1,4-naphthoquinone (1 mmol); SSA (20 mg);
100ꢀC; neat.
b Isolated yield.
c Yields after three times of catalyst recovery.
100
110
120
1.5
1.5
1.5
86
86
85
a Isolated yield.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

January 2011
Synthesis of 12-Aryl-12H-benzo[i][1,3]-dioxolo[4,5-b]xanthene-6,11-diones Using
Silica Sulfuric Acid as an Efficient and Versatile Catalyst Under Solvent-Free Conditions
85
Scheme 2
General procedure for the preparation of 4. To a mixture
of 3,4-methylenedioxyphenol (1 mmol), aldehyde (1 mmol),
and 2-hydroxy-1,4-naphthoquinone (1 mmol), SSA (20 mg,
0.05 mmol) was added. The mixture was stirred at 100ꢀC for
1.5–2.5 h. After completion of the reaction (TLC), CHCl3 (20
mL) was added, and the solid catalyst was removed by filtra-
tion. The solvent was evaporated and the crude product was
puried by silica gel column chromatography using CHCl3 as
eluent.
12-Phenyl-12H-benzo[i][1,3]-dioxolo[4,5-b]-xanthene-6, 11-
dione (4a). Marron powder, m.p. 242–243ꢀC; IR (KBr) m:
1706, 1642, 1607, 1577, 1504, 1481, 1374, 1290, 1188, 1141,
1031, 913 cmꢁ1 1H-NMR (DMSO-d6, 400 MHz) d: 8.15 (d,
;
and similar amounts of catalyst (5 mol %) were used.
As can be seen in Table 4, satisfactory results were
obtained only with SSA (entry 12).
In conclusion, we have developed a convenient and
efficient method for the synthesis of 12-aryl-12H-ben-
zo[i][1,3]-dioxolo[4,5-b]xanthene-6,11-diones by single-
pot condensation of 3,4-methylenedioxyphenol with
aldehydes and 2-hydroxy-1,4-naphthoquinone in the
presence of SSA. The simple experimental procedure,
solvent-free reaction conditions, utilization of an inex-
pensive and readily available catalyst, short period of
conversion, and excellent yields are the advantages of
the present method.
1H, J ¼ 7.6 Hz), 8.12 (d, 1H, J ¼ 7.6 Hz), 8.04–7.70 (m, 2H),
Table 4
EXPERIMENTAL
Effect of catalyst on the reaction of 3,4-methylenedioxyphenol,
benzaldehyde, and 2-hydroxy-1,4-naphthoquinonea.
NMR spectra were determined on Bruker AV-400 instru-
ment at room temperature using TMS as internal standard,
coupling constants (J) were measured in Hz; IR spectra were
determined on FTS-40 infrared spectrometer; elemental analy-
sis were performed by a Vario-III elemental analyzer; mass
spectra were taken on a macro mass spectrometer (Waters) by
electrospray method; melting points were determined on a XT-
4 binocular microscope and were uncorrected; commercially
available reagents were used throughout without further purifi-
cation unless otherwise stated.
Preparation of SSA. A 500-mL suction flask was used. It
was equipped with a constant pressure-dropping funnel con-
taining chlorosulfonic acid (23.3 g, 0.2 mol) and gas inlet tube
for conducting HCl gas over an adsorbing solution. Into it
were charged 60.0 g of silica gel. Chlorosulfonic acid was
added dropwise over a period of 30 min at room temperature.
HCl gas evolved from the reaction vessel immediately. After
the addition was complete, the mixture was shaken for 30 min.
A white solid of 76.0 g was obtained.
Entry
Catalyst
Time (h)
Yield (%)b
1
2
3
H14[NaP5W30O110
]
1
84
70
62
76
84
82
70
76
72
69
78
86
KAl(SO4)2ꢂ12H2O
Sulfamic acid
Dowex-50W
BF3ꢂSiO2
1
2
4
5
1
0.5
2
1.5
2
6
7
I2
LiBr
Cyanuric chloride
Ce(SO4)2
Al(HSO4)3
Silica chloride
SSA
8
9
2
2.5
2
10
11
12
1.5
a Reaction conditions: 3,4-methylenedioxyphenol (1 mmol); benzalde-
hyde (1 mmol); 2-hydroxy-1,4-naphthoquinone (1 mmol); catalyst
(0.05 mmol); 100ꢀC; neat.
b Isolated yield.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

86
L. Wu, S. Chao, and F. Yan
Vol 48
7.44–7.13 (m, 6H), 6.61 (s, 1H), 6.05 (s, 1H), 5.99 (s, 1H),
5.52 (s, 1H); 13C-NMR (CDCl3, 100 MHz) d: 178.12, 178.10,
158.09, 147.39, 145.56, 142.89, 135.63, 135.12, 132.91,
131.98, 131.38, 130.66, 130.46, 130.17, 130.02, 129.56,
128.24, 127.24, 124.62, 115.70, 107.77, 101.82, 98.42, 35.61;
MS (ESI) m/z 383 (M þ 1); Anal. Calcd. for C24H14O5: C
75.39, H 3.69; Found: C 75.52, H 3.51.
1233, 1188, 1144, 1039, 937, 774, 731 cmꢁ1
;
1H-NMR
(DMSO-d6, 400 MHz) d: 8.19–8.15 (m, 2H), 8.13–7.98 (m,
2H), 7.90–7.531 (m, 4H), 7.16 (s, 1H), 6.86 (s, 1H), 6.05 (s,
1H), 6.00 (s, 1H), 5.32 (s, 1H); 13C-NMR (CDCl3, 100 MHz)
d: 178.01, 177.99, 157.97, 148.48, 147.89, 146.30, 146.01,
143.36, 135.29, 134.77, 131.67, 130.38, 130.05, 129.53,
129.44, 124.86, 123.13, 122.16, 114.81, 113.93, 107.94,
102.07, 98.84, 38.27; MS (ESI) m/z 428 (M þ 1); Anal. Calcd.
for C27H13NO7: C 67.45, H 3.07, N 3.28; Found: C 67.38, H
3.02, N 3.34.
12-(4-Chlorophenyl)-12H-benzo[i][1,3]-dioxolo[4,5-b]-xan-
thene-6, 11-dione (4b). Marron powder, m.p. 229–230ꢀC; IR
(KBr) m: 2903, 1701, 1646, 1606, 1502, 1481, 1371, 1288, 1242,
1183, 1143, 1035, 935, 909, 776 cmꢁ1
;
1H-NMR (DMSO-d6,
12-(3,4-Dichlorophenyl)-12H-benzo[i][1,3]-dioxolo[4,5-b]-
xanthene-6, 11-dione (4g). Orange powder, m.p. 227–228ꢀC;
IR (KBr) m: 2975, 1694, 1644, 1608, 1503, 1480, 1374, 1291,
400 MHz) d: 8.14 (d, 1H, J ¼ 7.6 Hz), 7.99 (d, 1H, J ¼ 7.6 Hz),
7.90–7.68 (m, 2H), 7.35–7.13 (m, 5H), 6.82 (s, 1H), 6.05 (s, 1H),
5.99 (s, 1H), 5.12 (s, 1H); 13C-NMR (CDCl3, 100 MHz) d:
178.21, 178.14, 157.59, 147.51, 145.77, 143.37, 142.88, 135.15,
132.73, 131.38, 130.65, 129.99, 129.57, 129.42, 128.72, 126.71,
124.59, 115.93, 114.85, 110.18, 108.06, 101.92, 98.54, 37.80;
MS (ESI) m/z 417 (M þ 1); Anal. Calcd. for C24H13ClO5: C
69.16, H 3.14; Found: C 69.32, H 3.01.
1238, 1144, 1037, 915, 863 cmꢁ1 1H-NMR (CDCl3, 400
;
MHz) d: 8.13 (d, 1H, J ¼ 7.6 Hz), 8.09 (d, 1H, J ¼ 7.6 Hz),
7.81–7.78 (m, 1H), 7.64–7.60 (m, 1H), 7.34–7.18 (m, 3H),
6.85 (s, 1H), 6.51 (s, 1H), 6.02 (s, 1H), 5.99 (s, 1H), 5.13 (s,
1H); 13C-NMR (CDCl3, 100 MHz) d: 178.14, 178.03, 157.76,
147.75, 145.92, 144.46, 143.35, 135.19, 132.63, 131.54,
131.08, 130.50, 130.45, 130.11, 130.04, 129.48, 127.78,
124.69, 115.19, 114.25, 107.97, 102.01, 98.66, 37.71; MS
(ESI) m/z 451 (M þ 1); Anal. Calcd. for C24H12Cl2O5: C
63.88, H 2.68; Found: C 64.02, H 2.52.
12-(4-Methoxylphenyl)-12H-benzo[i][1,3]-dioxolo[4,5-b]-
xanthene-6, 11-dione (4c). Marron powder, m.p. 201–202ꢀC;
IR (KBr) m: 2982, 1736, 1700, 1645, 1606, 1511, 1479, 1372,
1
1287, 1255, 1139, 1037, 910, 834 cmꢁ1; H-NMR (DMSO-d6,
12-(4-Fluorophenyl)-12H-benzo[i][1,3]-dioxolo[4,5-b]-xanthene-
6, 11-dione (4h). Marron powder, m.p. 251–252ꢀC; IR (KBr) m:
2930, 1701, 1646, 1605, 1502, 1480, 1373, 1288, 1186, 1143,
400 MHz) d: 8.13 (d, 1H, J ¼ 8.0 Hz), 7.98 (d, 1H, J ¼ 7.6
Hz), 7.89–7.67 (m, 2H), 7.21–7.12 (m, 3H), 6.80–6.78 (m, 3H),
6.04 (s, 1H), 5.99 (s, 1H), 5.03 (s, 1H), 3.67 (s, 3H); 13C-NMR
(CDCl3, 100 MHz) d: 178.35, 178.31, 158.39, 157.29, 147.24,
145.63, 143.42, 136.79, 135.07, 131.16, 130.90, 129.98,
129.33, 129.18, 124.49, 116.83, 115.58, 113.91, 108.18,
101.80, 98.41, 55.22, 37.48; MS (ESI) m/z 413 (M þ 1); Anal.
Calcd. for C25H16O6: C 72.81, H 3.91; Found: C 72.92, H 3.82.
12-(4-Methylphenyl)-12H-benzo[i][1,3]-dioxolo[4,5-b]-
xanthene-6, 11-dione (4d). Orange powder, m.p. 215–
216ꢀC; IR (KBr) m: 2932, 1700, 1644, 1575, 1480, 1373,
1
1035, 935, 909 cmꢁ1; H-NMR (DMSO-d6, 400 MHz) d: 8.14
(d, 1H, J ¼ 7.6 Hz), 7.99 (d, 1H, J ¼ 7.6 Hz), 7.90–7.86 (m,
1H), 7.71–7.67 (m, 1H), 7.36–7.03 (m, 5H), 6.82 (s, 1H), 6.05
(s, 1H), 5.99 (s, 1H), 5.12 (s, 1H); 13C-NMR (DMSO-d6, 100
MHz) d: 178.22, 177.97, 157.61, 147.39, 145.51, 143.19,
141.71, 135.40, 131.82, 130.77, 130.65, 130.03, 129.95,
128.80, 124.80, 116.91, 115.65, 115.43, 114.46, 108.19,
102.29, 99.06, 37.29; MS (ESI) m/z 401 (M þ 1); Anal. Calcd.
for C24H13FO5: C 72.00, H 3.27; Found: C 72.15, H 3.18.
1288, 1234, 1186, 1142, 1037, 912, 769 cmꢁ1 1H-NMR
;
(DMSO-d6, 400 MHz) d: 8.14 (d, 1H, J ¼ 7.6 Hz), 7.98 (d,
1H, J ¼ 7.6 Hz), 7.91–7.88 (m, 1H), 7.71–7.68 (m, 1H), 7.19–
7.03 (m, 5H), 6.81 (s, 1H), 6.04 (s, 1H), 5.98 (s, 1H), 5.05 (s,
1H), 2.20 (s, 3H); 13C-NMR (DMSO-d6, 100 MHz) d: 178.24,
178.05, 157.51, 147.24, 145.42, 143.16, 142.66, 136.10,
135.46, 131.78, 130.71, 130.66, 129.44, 128.84, 127.90,
124.77, 117.32, 114.78, 108.22, 102.23, 98.99, 37.65, 20.95;
MS (ESI) m/z 397 (M þ 1); Anal. Calcd. for C25H16O5: C
75.75, H 4.07; Found: C 75.84, H 4.01.
Acknowledgments. We are pleased to acknowledge the finan-
cial support from Xinxiang Medical University.
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6.06 (s, 1H), 6.00 (s, 1H), 5.30 (s, 1H); 13C-NMR (CDCl3,
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C 67.32, H 3.14, N 3.20.
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

January 2011
Synthesis of 12-Aryl-12H-benzo[i][1,3]-dioxolo[4,5-b]xanthene-6,11-diones Using
Silica Sulfuric Acid as an Efficient and Versatile Catalyst Under Solvent-Free Conditions
87
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet