Silica-bonded S-sulfonic acid as recyclable catalyst for the synthesis of 1,8-dioxo-decahydroacridines and 1,8-dioxo-octahydroxanthenes

Article abstract of DOI:10.1002/jhet.303

(Chemical Equation Presented) Silica-bonded S-sulfonic acid (SBSSA) has been found to be an efficient catalyst for the synthesis of 1,8-dioxo- decahydroacridines and 1,8-dioxo-octahydroxanthenes in excellent yields. The former have been synthesized from a

Full text of DOI:10.1002/jhet.303

292
Silica-Bonded S-Sulfonic Acid as Recyclable Catalyst for the
Synthesis of 1,8-Dioxo-decahydroacridines and
1,8-Dioxo-octahydroxanthenes
Vol 47
Khodabakhsh Niknam,* Farhad Panahi, Dariush Saberi,
and Molki Mohagheghnejad
Faculty of Sciences, Department of Chemistry, Persian Gulf University, Bushehr 75169, Iran
*E-mail: khniknam@gmail.com
Received July 7, 2009
DOI 10.1002/jhet.303
Published online 23 February 2010 in Wiley InterScience (www.interscience.wiley.com).
Silica-bonded S-sulfonic acid (SBSSA) has been found to be an efficient catalyst for the synthesis of
1,8-dioxo-decahydroacridines and 1,8-dioxo-octahydroxanthenes in excellent yields. The former have
been synthesized from aromatic aldehydes, amines, and 5,5-dimethyl-1,3-cyclohexanedione, whereas the
latter from this mixture without amines. The method is an easy access to functionalized acridine and
xanthene derivatives. The catalyst can be reused.
J. Heterocyclic Chem., 47, 292 (2010).
INTRODUCTION
homogeneous catalysts and at the same time these spe-
cies have the advantage of being recyclable in the same
fashion as heterogeneous catalysts. In view of this, sev-
eral types of solid sulfonic acid functionalized silica
(both amorphous and ordered) have been synthesized
and applied as an alternative to traditional sulfonic acid
resins and homogeneous acids in catalyzing chemical
transformations [4,5]. Application of solid acids in or-
ganic transformation has an important role, because
these species have many advantages, such as, simplicity
in handling, decreased reactor and plant corrosion prob-
lems, and more environmentally safe disposal [4–10].
1,8-Dioxo-9-aryl-10-aryl-decahydroacridines and their
derivatives are polyfunctionalized 1,4-dihydropyridine
derivatives. In recent years, 1,4-dihydropyridines and
their derivatives have attracted strong interest for the
treatment of cardiovascular diseases, such as, angina
pectoris [11] and hypertension [12]. Acridine derivatives
have been used to synthesize labeled conjugates with
medicinals, peptides, proteins, and nucleic acids [13–15]
that exhibit antitumor and DNA-binding properties.
Multicomponent reactions (MCRs) constitute, an
The development of heterogeneous catalysts for fine
chemical synthesis has become a major area of research.
The potential advantages of these materials over homo-
geneous systems (simplified recovery and reusability,
the potential for incorporation in continuous reactors
and micro reactors) can lead to novel and environmen-
tally benign chemical procedures for academia and
industry [1]. From this viewpoint, catalytic reactions
lead to valuable processes, because the use of stoichio-
metric reagents that are often toxic poses inherent limi-
tations from both an economical and an environmental
viewpoint and in specific relation to product purification
and waste management [2]. It is clear that green chemis-
try not only requires the use of environmentally benign
reagents and solvents but also it is very crucial to
recover and reuse the catalyst. One way to overcome
the problem of recyclability of the traditional acid cata-
lyst is to chemically anchor their reactive center onto a
large surface area inorganic solid carrier to create new
organic–inorganic hybrid catalyst [3]. In these types of
solids, the reactive centers are highly mobile similar to
C
V
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1,8-Dioxo-decahydroacridines and 1,8-Dioxo-octahydroxanthenes
293
Scheme 1. Preparation of silica bonded S-sulfonic acid.
ride [30], amberlyst-15 [18d], silica sulfuric acid [31],
tetrabutylammonium hydrogen sulfate [32], trimethylsi-
lylchloride [33], 1-butyl-3-methylimidazolium hydrogen
sulfate [34], montmorillonite K-10-supported [35], and
covalently anchored sulfonic acid on silica gel [36].
Each of these methods have their own advantages but
also some of them often suffer from one or more disad-
vantages, such as, prolonged reaction time, tedious
work-up processes, low yield [37], expensive reagents
[18d,25], and hazardous organic solvents [37]. Conse-
quently, there is scope for further innovation of methods
with milder reaction conditions, short reaction times,
increase in variation of the substituents in the compo-
nents, and better yields in the synthesis of 1,8-dioxode-
cahydroacridines and 1,8-dioxo-octahydroxanthenes,
which can be possibly achieved by choosing silica-
bonded S-sulfonic acid (SBSSA) as a catalyst for this
MCR.
especially attractive synthetic strategy, for rapid and ef-
ficient library generation because the products are
formed in a single step and diversity can be achieved
simply by varying the reaction components [16]. Thus,
new routes utilizing a MCR protocol for the synthesis of
these molecules can attract considerable attention in the
search for rapid-entry methods to these heterocycles.
Reportedly, the conventional synthesis of acridines
and their derivatives has been performed in an organic
acid, such as, HOAc [17]. Recently, few methodologies
have been reported in the literature for the synthesis of
decahydroacridines [18]. Each of these methods has lim-
itations, such as, poor yields, cumbersome work up pro-
cedure, and generation of polluting effluents [17].
RESULTS AND DISCUSSION
Recently, we have reported the preparation of SBSSA
and its application as catalyst for the synthesis of 1,1-
diacetates [5a], quinoxaline [5b], and coumarin deriva-
tives [5c] (Scheme 1).
In our continued interest in the development of a
highly expedient methodology for the synthesis of fine
chemicals and heterocyclic compounds of biological
importance [38], we report here the synthesis of 1,8-
dioxo-9-aryl-10-aryl-decahydroacridines and 1,8-dioxo-
octahydroxanthenes in the presence of SBSSA as a
heterogeneous solid acid (Scheme 2).
Xanthenes are an important class of organic com-
pounds that find use as dyes, fluorescent material for
visualization of biomolecules, and in laser technologies
due to their useful spectroscopic properties [19]. Xan-
thenes have also received significant attention from
many pharmaceutical and organic chemists essentially
because of the broad spectrum of their biological and
pharmaceutical properties, such as, antiviral [20], anti-
bacterial [21], antinociceptive activities [22] as well as
efficiency in photodynamic therapy [23] and anti-inflam-
matory activities [24]. There are several reports in the
literature for the synthesis of 1,8-dioxooctahydroxan-
thene derivatives using aromatic aldehydes and 5,5-di-
methyl-1,3-cyclohexanedione, these include InCl3ꢀ4H2O
in ionic liquid [25], solid-state condensation by grinding
at room temperature [26], diammonium hydrogen phos-
phate [27], p-dodecylbenzenesulfonic acid in water [28],
Fe3þ-montmorilonite [29], NaHSO4-SiO2 or silica chlo-
To determine the scope of the designed protocol, a
number of commercially available aromatic aldehydes
have condensed with dimedone and aryl amines under
optimized reaction conditions, and the results are sum-
marized in Table 1. We investigated further the elec-
tronic effect of different substituents present on the alde-
hyde component. It was observed that a wide range of
aldehydes having both electron-donating and electron-
withdrawing groups were equally facile for the reaction,
resulting in the formation of decahydroacridine deriva-
tives in very good yields. We also observed that various
aniline derivatives reacted smoothly under the reaction
conditions.
Scheme 2. Synthesis of 1,8-dioxo-9-aryl-10-aryl-decahydroacridines and 1,8-dioxo-octahydroxanthene using SBSSA as catalyst.
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Table 1
Synthesis of 1,8-dioxo-9-aryl-10-aryl-decahydroacridines derivatives in the presence of SBSSA under reflux conditions.a
Entry
Ar
Ar0
Product
Time (h)
1.0
Yieldb (%)
1
2
3
4
4-ClAC6H4
4-MeAC6H4
96
85
93
89
5a
3-NO2AC6H4
4-MeSAC6H4
3-CNAC6H4
4-MeAC6H4
4-MeAC6H4
4-MeAC6H4
2.5
3.0
4.5
5b
5c
5d
5
3-NO2AC6H4
3-CNAC6H4
3.0
84
5e
6
7
3-HOAC6H4
3-CNAC6H4
3.0
2.5
92
95
5f
4-ClAC6H4
3-HOAC6H4
5g
8
4-NO2AC6H4
2-HOAC6H4
1.5
96
5h
a Reaction conditions: Dimedone (2 mmol), aldehyde (1 mmol), aniline derivative (1 mmol), catalyst (0.03 g) in refluxing ethanol.
b Isolated yield.
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295
Table 2
Synthesis of 1,8-dioxo-octahydroxanthenes derivatives in the presence of SBSSA in ethanol under reflux conditions.a
Entry
1
Ar
Product
Time (h)
10.0
Yieldb (%)
98
C6H5
6a
6b
2
4-ClAC6H4
4.0, 4.0, 4.5, 5.0, 5.0
92, 91, 89, 91, 90
3
4-BrAC6H4
3.0
96
6c
4
5
6
7
8
9
2-ClAC6H4
5.0
5.0
2.0
3.0
3.0
6.0
90
90
95
87
94
91
6d
6e
6f
3-ClAC6H4
4-NO2AC6H4
2-NO2AC6H4
3-NO2AC6H4
4-MeOAC6H4
6g
6h
6i
(Continued)
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Table 2
(Continued)
Entry
Ar
Product
Time (h)
9.0
Yieldb (%)
10
11
12
13
14
4-MeAC6H4
91
64
65
71
94
6j
4-OHCAC6H4
3-OHCAC6H4
3-Pyridyl
5.0
7.0
6.0
3.0
6k
6l
6m
C6H5ACH¼CHA
6n
a Reaction conditions: Dimedone (2 mmol), aldehyde (1 mmol), catalyst (0.03 g) in refluxing ethanol.
b Isolated yield.
Encouraged by these results, we carried out reaction
of 5,5-dimethyl-1,3-cyclohexanedione (3) and aromatic
aldehydes (4) in the presence of SBSSA (0.03 g) in
refluxing ethanol, which afforded 1,8-dioxo-octahydrox-
anthene derivatives 6a–n in excellent yields within a
short period of time (Scheme 2, Table 2). Here also the
aromatic aldehydes containing both electron-donating
and electron-withdrawing groups afforded the products
in high yields.
The practical synthetic efficiency of this reaction was
highlighted by the reaction of terephthaldehyde (7) and
isophthaldehyde (8) with dimedone (3) to give structur-
ally complex xanthenone derivatives (6k and 6l),
Scheme 3.
An important feature of this method is that the hetero-
cyclic functionality present in the molecule remains
Scheme 3. Synthesis of bis(1,8-dioxo-octahydroxanthenes).
Scheme 4. Synthesis of 9-(pyridine-3-yl)-1,8-dioxo-octahydroxanthene.
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297
1
291ꢁC, (ref. 18e. 285–287ꢁC); H NMR (CDCl3, 500 MHz), d:
unaffected. This fact was amply demonstrated by the
reaction of pyridine-3-caboxaldehyde (9) with dimedone
(3), which gave 9-(pyridine-3-yl)-1,8-dioxo-octahydrox-
anthene (6m) in excellent yield (Scheme 4).
0.81 (s, 6H), 0.99 (s, 6H), 1.92 (dd, 2H, J1 ¼ 17.5 Hz, J2
¼
0.9 Hz), 2.15 (d, 4H, J ¼ 16.6 Hz), 2.24 (d, 2H, J ¼ 16.2 Hz),
2.52 (s, 3H), 5.38 (s, 1H), 7.14–7.23 (m, 2H), 7.40–7.45 (m,
3H), 7.97–8.01 (m, 2H), 8.25 (t, 1H, J ¼ 1.9 Hz); 13C NMR
(CDCl3, 125 MHz), d: 21.71, 27.05, 30.10, 32.87, 33.31,
42.13, 50.53, 114.21, 121.53, 122.37, 129.22, 129.95, 130.93,
131.79, 135.70, 136.38, 140.22, 148.85, 151.26, 196.11.
The possibility of recycling the catalyst was examined
using the condensation reaction of 5,5-dimethyl-1,3-
cyclohexanedione and 4-chlorobenzaldehyde in ethanol
under the optimized conditions. When the reaction was
complete, the mixture was filtered and the remaining
was washed with warm ethanol, and the catalyst reused
in the next reaction. The recycled catalyst could be
reused four times without any additional treatment. No
observation of any appreciable loss in the catalytic ac-
tivity of SBSSA was observed (Table 2, entry 2).
In conclusion, we have developed an efficient method
for the synthesis of 1,8-dioxo-9-aryl-10-aryl-decahydro-
acridines and 1,8-dioxo-octahydroxanthenes in high
yields using SBSSA as a catalyst. The catalyst was
recovered and reused without any noticeable loss of
reactivity. The mild reaction conditions and simplicity
of the procedure offers improvements over many exist-
ing methods.
3,4,6,7-Tetrahydro-3,3,6,6-tetramethyl-9-(4-(methylthio)-
phenyl)-10-p-tolyl-acridine-1,8-(2H,5H,9H,10H)-dione (5c). mp
239ꢁC; IR (KBr): 3080, 2960, 2880, 1639, 1570, 1505, 1360,
1220, 882, 838, 730, 562, 520 (cmꢂ1); H NMR (CDCl3, 500
1
MHz), d: 0.84 (s, 6H), 0.97 (s, 6H), 1.87 (d, 2H, J ¼ 17.5
Hz), 2.10 (d, 2H, J ¼ 17.5 Hz), 2.15 (d, 2H, J ¼ 16.2 Hz),
2.22 (d, 2H, J ¼ 16.2 Hz), 2.46 (s, 3H), 2.52 (s, 3H), 5.26 (s,
1H), 7.12 (d, 2H, J ¼ 7.7 Hz), 7.19 (d, 2H, J ¼ 8.1 Hz),
7.36–7.40 (m, 4H); 13C NMR (CDCl3, 125 MHz), d: 16.59,
21.71, 27.23, 30.15, 32.76, 32.80, 42.20, 50.64, 114.85,
127.26, 128.86, 135.52, 136.79, 139.92, 144.06, 150.38,
196.23; Anal. Calc. C, 76.66; H, 7.26; N, 2.88; S, 6.60; Found
C, 76.49; H, 7.09; N, 2.67.
3-(1,2,3,4,5,6,7,8,9,10-Decahydro-3,3,6,6-tetramethyl-1,8-dioxo-
10-p-tolylacridin-9-yl)benzonitrile (5d). mp 256–257ꢁC; IR
(KBr): 3080, 2960, 2880, 2320, 1638, 1590, 1558, 1480, 1450,
1360, 1308, 1220, 1140, 998, 930, 842, 830, 720 (cmꢂ1); 1H
NMR (CDCl3, 500 MHz), d: 0.80 (s, 6H), 0.94 (s, 6H), 1.86
(d, 2H, J ¼ 17.5 Hz), 2.09 (d, 2H, J ¼ 14.6 Hz), 2.12 (d, 2H,
J ¼ 12.5 Hz), 2.19 (d, 2H, J ¼ 16.2 Hz), 2.47 (s, 3H), 5.24 (s,
1H), 7.05 (d, 1H, J ¼ 7.9 Hz), 7.10 (d, 2H, J ¼ 8.3 Hz), 7.15
(t, 1H, J ¼ 7.8 Hz), 7.33–7.36 (m, 3H), 7.39 (d, 1H, J ¼ 1.7
Hz); 13C NMR (CDCl3, 125 MHz), d: 21.68, 27.13, 30.09,
32.77, 33.00, 42.13, 50.60, 114.36, 126.46, 126.65, 128.42,
128.98, 129.66, 130.06, 134.13, 136.50, 140.06, 148.68,
150.83, 196.09; Anal. Calc. C, 80.14; H, 6.94; N, 6.03; Found
C, 79.97; H, 6.77; N, 5.87.
EXPERIMENTAL
General. Chemicals were purchased from Fluka, Merck,
and Aldrich Chemical Companies. All of the products are
known, except 5c–5h, and characterized by comparison of
their spectral (IR, 1H NMR) and physical data with those
reported in literature. SBSSA was prepared according to our
previous reported procedure [5].
3-(1,2,3,4,5,6,7,8-Octahydro-3,3,6,6-tetramethyl-9-(3-nitro-
(5e). mp
General procedure for the synthesis of 1,8-dioxo-9-aryl-
10-aryl-decahydroacridines derivatives. To a solution of an
aromatic aldehyde (1 mmol), 5,5-dimethyl-1,3-cyclohexane-
dione (2 mmol) and aryl amine (1 mmol) in ethanol (2 mL) in
a round-bottom flask, SBSSA (0.03 g) was added. The mixture
was heated under reflux conditions and the reaction was moni-
tored by TLC. After completion of the reaction, the mixture
was filtered and the remaining was washed with warm ethanol
in order to separate catalyst. Then, water (20 mL) was added
to the filtrate and was allowed to stand at room temperature
for 1 h. During this time, crystals of the pure product were
formed, which were collected by filtration and dried. For fur-
ther purification, if needed, the products were recrystalized
from hot ethanol. The spectral data are given below.
phenyl)-1,8-dioxo-acridin-10(9H)-yl)benzonitrile
266–268ꢁC; IR (KBr): 3080, 2960, 2880, 2203, 1643, 1635,
1595, 1578, 1440, 1362, 1240, 1220, 1140, 879, 801, 699
1
(cmꢂ1); H NMR (CDCl3, 500 MHz), d: 0.83 (s, 6H), 1.01 (s,
6H), 1.83 (d, 2H, J ¼ 17.4 Hz), 2.13 (d, 2H, J ¼ 17.5 Hz),
2.17 (d, 2H, J ¼ 16.4 Hz), 2.26 (d, 2H, J ¼ 16.3 Hz), 5.37 (s,
1H), 7.46 (t, 1H, J ¼ 7.9 Hz), 7.63–7.68 (m, 2H), 7.82 (t, 1H,
J ¼ 7.8 Hz), 7.91–7.95 (m, 2H), 8.00 (dd, 1H, J1 ¼ 8.2 Hz, J2
¼ 1.4 Hz), 8.21 (s, 1H); 13C NMR (CDCl3, 125 MHz), d:
27.15, 30.04, 33.03, 33.23, 42.35, 50.39, 114.91, 117.53,
121.77, 122.26, 129.47, 133.82, 135.62, 140.17, 148.26,
148.81, 149.80, 195.90; Anal. Calc. C, 72.71; H, 5.90; N,
8.48; Found C, 72.57; H, 5.76; N, 8.32.
3-(1,2,3,4,5,6,7,8-Octahydro-9-(3-hydroxyphenyl)-3,3,6,6-tet-
ramethyl-1,8-dioxo-acridin-10(9H)-yl)benzonitrile (5f). mp
>300ꢁC decomp.; IR (KBr): 3250, 3080, 2960, 2880, 2320,
1610, 1590, 1555, 1500, 1460, 1410, 1340, 1260, 1240, 1142,
9-(4-Chlorophenyl)-3,4,6,7-tetrahydro-3,3,6,6-tetramethyl-10-
p-tolylacridine-1,8-(2H,5H,9H,10H)-dione (5a). mp 273–
1
275ꢁC, (ref. 18e, 270–271ꢁC); H NMR (CDCl3, 500 MHz), d:
0.82 (s, 6H), 0.97 (s, 6H), 1.87 (d, 2H, J ¼ 17.4 Hz), 2.08–
2.15 (m, 4H), 2.22 (d, 2H, J ¼ 16.2 Hz), 2.51 (s, 3H), 5.26 (s,
1H), 7.12 (d, 2H, J ¼ 8.2 Hz), 7.23 (d, 2H, J ¼ 8.3 Hz),
7.36–7.40 (m, 4H); 13C NMR (CDCl3, 125 MHz), d: 21.73,
27.15, 30.15, 32.80, 32.87, 42.18, 50.60, 114.56, 128.56,
129.13, 129.74, 130.05, 131.84, 136.60, 140.06, 145.34,
150.64, 196.21.
1
1110, 838, 710 (cmꢂ1); H NMR [CDCl3-DMSO-d6 (2%), 500
MHz], d: 0.72 (s, 6H), 0.85 (s, 6H), 1.63 (d, 2H, J ¼ 17.3
Hz), 1.94 (d, 2H, J ¼ 17.3 Hz), 2.01 (d, 2H, J ¼ 16.2 Hz),
2.08 (d, 2H, J ¼ 16.2 Hz), 5.06 (s, 1H), 6.47 (dd, 1H, J1
¼
7.8 Hz, J2 ¼ 2.0 Hz), 6.75–6.78 (m, 4H), 6.93 (t, 1H, J ¼ 7.8
Hz), 7.48 (d, 1H, J ¼ 7.3 Hz), 7.62 (t, 2H, 7.8 Hz), 7.76 (d,
1H, J ¼ 7.8 Hz), 8.5 (brs, 1H); 13C NMR [CDCl3-DMSO-d6
(2%), 125 MHz], d: 27.05, 29.86, 32.31, 32.64, 41.99, 50.39,
3,4,6,7-Tetrahydro-3,3,6,6-tetramethyl-9-(3-nitrophenyl)-10-
p-tolylacridine-1,8-(2H,5H,9H,10H)-dione (5b). mp 289–
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1
113.56, 114.84, 114.94, 117.68, 119.27, 129.10, 133.47,
135.01, 140.06, 147.30, 149.16, 157.50, 195.72; Anal. Calc. C,
77.23; H, 6.48; N, 6.00; Found C, 77.09; H, 6.33; N, 5.81.
9-(4-Chlorophenyl)-3,4,6,7-tetrahydro-10-(3-hydroxyphenyl)-
3,3,6,6-tetramethyl-acridine-1,8-(2H,5H,9H,10H)-dione (5g). mp
267–269ꢁC; IR (KBr): 3390, 3120, 2960, 2880, 1639, 1595,
1560, 1480, 1443, 1360, 1305, 1220, 1140, 998, 935, 840,
720, 560 (cmꢂ1); 1H NMR [CDCl3-DMSO-d6 (2%), 500
MHz], d: 0.68 (s, 6H), 0.83 (s, 6H), 1.82 (d, 2H, J ¼ 17.5
Hz), 1.97–2.09 (m, 6H), 5.07 (s, 1H), 6.54–6.58 (m, 2H), 6.90
(d, 1H, J ¼ 5.0 Hz), 7.07 (d, 2H, J ¼ 8.3 Hz), 7.20–7.24 (m,
3H), 9.52 (brs, 1H); 13C NMR [CDCl3-DMSO-d6 (2%), 125
MHz], d: 26.93, 30.03, 32.66, 41.73, 50.52, 114.12, 128.39,
128.62, 131.63, 139.76, 145.27, 150.96, 195.40; Anal. Calc. C,
73.17; H, 6.35; Cl, 7.45; N, 2.94; Found C, 73.01; H, 6.19; N,
2.81.
240–242ꢁC); H NMR (CDCl3, 500 MHz), d: 1.03 (s, 6H), 1.14
(s, 6H), 2.20 (d, 2H, J ¼ 16.3 Hz), 2.27 (d, 2H, J ¼ 16.3 Hz),
2.50 (s, 4H), 4.74 (s, 1H), 7.21 (d, 2H, J ¼ 8.4 Hz), 7.37 (d,
2H, J ¼ 8.4 Hz). 13C NMR (CDCl3, 125 MHz), d: 27.73, 29.69,
31.98, 32.62, 41.28, 51.12, 115.63, 120.66, 130.60, 131.57,
143.64, 162.82, 196.69.
3,4,6,7-Tetrahydro-3,3,6,6-tetramethyl-9-(2-chlorophenyl)-2H-
xanthene-1,8-(5H,9H)-dione (6d). mp 225–227ꢁC, (ref. 32,
1
225–227ꢁC); H NMR (CDCl3, 500 MHz), d: 1.05 (s, 6H), 1.13
(s, 6H), 2.19 (d, 2H, J ¼ 16.2 Hz), 2.26 (d, 2H, J ¼ 16.2 Hz),
2.48 (s, 4H), 5.03 (s, 1H), 7.09 (dt, 1H, J1 ¼ 7.6 Hz, J2 ¼ 1.6
Hz), 7.19 (dt, 1H, J1 ¼ 7.6 Hz, J2 ¼ 1.1 Hz), 7.26 (dd, 1H, J1
¼ 7.9 Hz, J2 ¼ 1.0 Hz),), 7.46 (d, 1H, J ¼ 7.3 Hz). 13C NMR
(CDCl3, 125 MHz), d: 27.79, 29.69, 32.28, 32.43, 41.25, 51.14,
114.13, 126.74, 128.20, 130.56, 133.34, 133.88, 140.32, 163.37,
196.84.
3,4,6,7-Tetrahydro-10-(2-hydroxyphenyl)-3,3,6,6-tetramethyl-
9-(4-nitrophenyl)-acridine-1,8-(2H,5H,9H,10H)-dione (5h). mp
>300ꢁC decomp.; IR (KBr): 3380, 3120, 2960, 2880, 1638,
1595, 1520, 1360, 1340, 1220, 1140, 998, 860, 827 (cmꢂ1);
1H NMR [CDCl3-DMSO-d6 (2%), 500 MHz], d: 0.67 (s, 6H),
0.84 (s, 6H), 1.84 (d, 2H, J ¼ 17.5 Hz), 1.98 (d, 2H, J ¼ 16.3
Hz), 2.04–2.10 (m, 4H), 5.18 (s, 1H), 6.55–6.59 (m, 2H), 6.92
(d, 2H, J ¼ 7.9 Hz), 7.21–7.24 (m, 1H), 7.47 (d, 2H, J ¼ 8.7
Hz), 7.98 (d, 2H, 8.7 Hz), 9.48 (brs, 1H); 13C NMR [CDCl3-
DMSO-d6 (2%), 125 MHz], d: 26.95, 29.98, 32.68, 41.73,
50.44, 113.44, 123.69, 129.14, 139.58, 146.38, 154.10, 196.09;
Anal. Calc. C, 71.59; H, 6.21; N, 5.76; Found C, 71.43; H,
6.09; N, 5.29.
General procedure for the synthesis of 1,8-dioxo-octahy-
droxanthene derivatives. To a solution of an aromatic alde-
hyde (1 mmol) and 5,5-dimethyl-1,3-cyclohexanedione (2
mmol) in ethanol (2 mL) in a round-bottom flask, SBSSA
(0.03 g) was added. The mixture was heated under reflux con-
ditions and the reaction was monitored by TLC. After comple-
tion of the reaction, the mixture was filtered and the remaining
was washed with warm ethanol in order to separate catalyst.
Then, water (20 mL) was added to the filtrate and was allowed
to stand at room temperature for 1 h. During this time, crystals
of the pure product were formed, which were collected by fil-
tration and dried. For further purification if needed, the prod-
ucts recrystalized from hot ethanol. The NMR data are given
below.
3,4,6,7-Tetrahydro-3,3,6,6-tetramethyl-9-(3-chlorophenyl)-2H-
xanthene-1,8-(5H,9H)-dione (6e). mp 184–186ꢁC, (ref. 32,
182–184ꢁC); 1H NMR (CDCl3, 500 MHz), d: 0.99 (s, 6H),
1.09 (s, 6H), 2.17 (d, 2H, J ¼ 16.2 Hz), 2.22 (d, 2H, J ¼ 16.2
Hz), 2.46 (s, 4H), 4.71 (s, 1H), 7.06 (dt, 1H, J1 ¼ 9.1 Hz, J2
¼ 1.5 Hz), 7.13 (t, 1H, J ¼ 7.9 Hz), 7.21 (d, 1H, J ¼ 1.2
Hz),), 7.23 (t, 1H, J ¼ 1.3 Hz). 13C NMR (CDCl3, 125 MHz),
d: 27.79, 29.62, 32.16, 32.63, 41.27, 51.13, 115.51, 127.05,
127.40, 128.75, 129.65, 134.28, 146.54, 162.99, 196.67.
3,4,6,7-Tetrahydro-3,3,6,6-tetramethyl-9-(4-nitrophenyl)-2H-
xanthene-1,8-(5H,9H)-dione (6f). mp 222–223ꢁC, (ref. 32,
221–223ꢁC); 1H NMR (CDCl3, 500 MHz), d: 1.02 (s, 6H),
1.15 (s, 6H), 2.20 (d, 2H, J ¼ 16.3 Hz), 2.29 (d, 2H, J ¼ 16.3
Hz), 2.53 (s, 4H), 4.86 (s, 1H), 7.51 (dd, 2H, J1 ¼ 7.0 Hz, J2
¼ 1.7 Hz), 8.12 (dd, 2H, J1 ¼ 7.0 Hz, J2 ¼ 1.7 Hz). 13C
NMR (CDCl3, 125 MHz), d: 27.70, 29.64, 32.64, 32.79, 41.27,
51.03, 114.96, 123.83, 129.78, 146.92, 151.94, 163.36, 196.63.
3,4,6,7-Tetrahydro-3,3,6,6-tetramethyl-9-(2-nitrophenyl)-2H-
xanthene-1,8-(5H,9H)-dione (6g). mp 252–254ꢁC, (ref. 32,
248–249ꢁC); 1H NMR (CDCl3, 500 MHz), d: 0.98 (s, 6H),
1.07 (s, 6H), 2.13 (d, 2H, J ¼ 16.2 Hz), 2.21 (d, 2H, J ¼ 16.2
Hz), 2.45 (s, 4H), 5.51 (s, 1H), 7.21 (dt, 1H, J1 ¼ 7.7 Hz, J2
¼ 1.4 Hz), 7.34 (d, 1H, J ¼ 7.5 Hz), 7.41 (dt, 1H, J1 ¼ 7.5
Hz, J2 ¼ 1.2 Hz),), 7.73 (d, 1H, J ¼ 8.1 Hz). 13C NMR
(CDCl3, 125 MHz), d: 28.00, 29.16, 29.36, 32.48, 41.26,
51.04, 114.60, 125.03, 127.59, 131.46, 132.40, 138.46, 150.27,
163.44, 196.73.
3,4,6,7-Tetrahydro-3,3,6,6-tetramethyl-9-phenyl-2H-xanthene-
1,8-(5H,9H)-dione (6a). mp 203–204ꢁC, (ref. 32, 204–206ꢁC);
1H NMR (CDCl3, 500 MHz), d: 1.02 (s, 6H), 1.13 (s, 6H),
2.19 (d, 2H, J ¼ 16.2 Hz), 2.26 (d, 2H, J ¼ 16.2 Hz), 2.50 (s,
4H), 4.78 (s, 1H), 7.12 (t, 1H, J ¼ 7.2 Hz), 7.24 (t, 2H, J ¼
7.5 Hz), 7.32 (d, 2H, J ¼ 7.6 Hz). 13C NMR (CDCl3, 125
MHz), d: 27.75, 29.69, 32.26, 32.61, 41.29, 51.18, 116.07,
126.76, 128.45, 128.80, 144.54, 162.70, 196.76.
3,4,6,7-Tetrahydro-3,3,6,6-tetramethyl-9-(4-chlorophenyl)-2H-
xanthene-1,8-(5H,9H)-dione (6b). mp 230–232ꢁC, (ref. 33,
230–232ꢁC); 1H NMR (CDCl3, 500 MHz), d: 1.03 (s, 6H),
1.14 (s, 6H), 2.20 (d, 2H, J ¼ 16.3 Hz), 2.27 (d, 2H, J ¼ 16.3
Hz), 2.50 (s, 4H), 4.75 (s, 1H), 7.22 (d, 2H, J ¼ 8.5 Hz), 7.27
(d, 2H, J ¼ 8.5 Hz). 13C NMR (CDCl3, 125 MHz), d: 27.72,
29.68, 31.89, 32.61, 41.28, 51.13, 115.69, 128.63, 130.19,
132.45, 143.13, 162.83, 196.71.
3,4,6,7-Tetrahydro-3,3,6,6-tetramethyl-9-(3-nitrophenyl)-2H-
xanthene-1,8-(5H,9H)-dione (6h). mp 170–172ꢁC, (ref. 32,
170–172ꢁC); 1H NMR (CDCl3, 500 MHz), d: 0.98 (s, 6H),
1.10 (s, 6H), 2.15 (d, 2H, J ¼ 16.3 Hz), 2.24 (d, 2H, J ¼ 16.3
Hz), 2.49 (s, 4H), 4.82 (s, 1H), 7.38 (t, 1H, J ¼ 7.9 Hz), 7.79
(d, 1H, J ¼ 7.7 Hz), 7.96 (dd, 1H, J1 ¼ 8.0 Hz, J2 ¼ 1.9
Hz),), 8.02 (t, 1H, J ¼ 1.9 Hz). 13C NMR (CDCl3, 125 MHz),
d: 27.72, 29.61, 32.52, 32.66, 41.23, 51.06, 114.96, 122.06,
123.02, 129.21, 136.07, 146.74, 148.73, 163.46, 196.76.
3,4,6,7-Tetrahydro-3,3,6,6-tetramethyl-9-(4-methoxyphenyl)-
2H-xanthene-1,8-(5H,9H)-dione (6i). mp 242–244ꢁC, (ref. 32,
240–242ꢁC); 1H NMR (CDCl3, 500 MHz), d: 0.98 (s, 6H),
1.08 (s, 6H), 2.15 (d, 2H, J ¼ 16.3 Hz), 2.21 (d, 2H, J ¼ 16.3
Hz), 2.44 (s, 4H), 3.71 (s, 3H), 4.68 (s, 1H), 6.74 (dd, 2H, J1
¼ 6.8 Hz, J2 ¼ 1.9 Hz), 7.19 (dd, 2H, J1 ¼ 6.8 Hz, J2 ¼ 1.9
Hz). 13C NMR (CDCl3, 125 MHz), d: 27.76, 29.69, 31.38,
32.61, 41.29, 51.20, 55.52, 113.89, 116.21, 129.73, 136.98,
158.38, 162.48, 196.86.
3,4,6,7-Tetrahydro-3,3,6,6-tetramethyl-9-(4-bromophenyl)-2H-
xanthene-1,8-(5H,9H)-dione (6c). mp 240–241ꢁC, (ref. 33,
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

March 2010
Silica-Bonded S-Sulfonic Acid as Recyclable Catalyst for the Synthesis of
1,8-Dioxo-decahydroacridines and 1,8-Dioxo-octahydroxanthenes
299
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3,4,6,7-Tetrahydro-3,3,6,6-tetramethyl-9-p-tolyl-2H-xanthene-
1
1,8-(5H,9H)-dione (6j). mp 215–217ꢁC, (ref. 32, 217–218ꢁC); H
NMR (CDCl3, 500 MHz), d: 0.98 (s, 6H), 1.09 (s, 6H), 2.15 (d,
2H, J ¼ 16.3 Hz), 2.20–2.23 (m, 5H), 2.45 (s, 4H), 4.70 (s, 1H),
7.00 (d, 2H, J ¼ 8.0 Hz), 7.17 (d, 2H, J ¼ 8.0 Hz). 13C NMR
(CDCl3, 125 MHz), d: 21.47, 27.80, 29.69, 31.86, 32.62, 41.30,
51.20, 116.19, 128.66, 129.20, 136.17, 141.63, 162.51, 196.80.
3,4,6,7-Tetrahydro-9-(4-(2,3,4,5,6,7,8,9-octahydro-3,3,6,6-tet-
ramethyl-1,8-dioxo-1H-xanthen-9-yl)phenyl)-3,3,6,6-tetra-
methyl-2H-xanthene-1,8(5H,9H)-dione (6k). mp >300ꢁC
(dec.), (ref. 34, >300ꢁC); 1H NMR (CDCl3, 500 MHz), d:
0.87 (s, 12H), 0.99 (s, 12H), 2.07 (d, 4H, J ¼ 16.2 Hz), 2.11
(d, 4H, J ¼ 16.2 Hz), 2.33 (d, 4H, J ¼ 17.6 Hz), 2.39 (d, 4H,
J ¼ 17.6 Hz), 4.59 (s, 2H), 6.99 (s, 4H); 13C NMR (CDCl3,
125 MHz), d: 27.80, 29.41, 31.03, 32.57, 41.12, 51.10, 115.91,
128.16, 142.15, 162.93, 196.73.
3,4,6,7-Tetrahydro-9-(3-(2,3,4,5,6,7,8,9-octahydro-3,3,6,6-tet-
ramethyl-1,8-dioxo-1H-xanthen-9-yl)phenyl)-3,3,6,6-tetramethyl-
2H-xanthene-1,8(5H,9H)-dione (6l). mp 238–240ꢁC, (ref. 32,
236–238ꢁC); 1H NMR (CDCl3, 500 MHz), d: 1.03 (s, 12H),
1.11 (s, 12H), 2.16 (d, 4H, J ¼ 16.2 Hz), 2.21 (d, 4H, J ¼
16.2 Hz), 2.46 (d, 4H, J ¼ 17.4 Hz), 2.56 (d, 4H, J ¼ 17.4
Hz), 4.72 (s, 2H), 7.07–7.09 (m, 3H), 7.15 (s, 1H). 13C NMR
(CDCl3, 125 MHz), d: 28.02, 29.57, 31.76, 32.56, 41.27,
51.27, 116.01, 126.84, 128.18, 128.66, 144.04, 162.72, 196.66.
3,4,6,7-Tetrahydro-3,3,6,6-tetramethyl-9-(pyridin-3-yl)-2H-
xanthene-1,8(5H,9H)-dione (6m). mp 184–186ꢁC, (ref. 34,
184–186ꢁC); 1H NMR (CDCl3, 500 MHz), d: 1.01 (s, 6H),
1.12 (s, 6H), 2.18 (d, 2H, J ¼ 16.3 Hz), 2.26 (d, 2H, J ¼ 16.3
Hz), 2.50 (s, 4H), 4.73 (s, 1H), 7.16–7.18 (m, 1H), 7.72–7.75
(dt, 1H, J1 ¼ 7.8 Hz, J2 ¼ 1.9 Hz), 8.36 (dd, 1H, J1 ¼ 4.7
Hz, J2 ¼ 1.5 Hz), 8.45 (d, 1H, J ¼ 1.9 Hz); 13C NMR
(CDCl3, 125 MHz), d: 27.79, 29.58, 32.63, 41.20, 51.03,
115.11, 123.44, 136.96, 140.07, 148.04, 149.90, 163.24,
196.73.
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3,4,6,7-Tetrahydro-3,3,6,6-tetramethyl-9-styryl-2H-xanthene-
1,8-(5H,9H)-dione (6n). mp 174–176ꢁC, (ref. 32, 176–178ꢁC);
1H NMR (CDCl3, 500 MHz), d: 1.16 (s, 12H), 2.31 (d, 2H, J
¼ 16.3 Hz), 2.35 (d, 2H, J ¼ 16.3 Hz), 2.45 (d, 2H, J ¼ 18.7
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Hz), 7.17–7.20 (m, 1H), 7.26 (t, 2H, J ¼ 7.5 Hz), 7.31 (dd,
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127.51, 128.70, 130.84, 131.76, 137.69, 163.44, 196.91.
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