Reaction in dry media: Silica gel supported ferric chloride catalyzed synthesis of 1,8-dioxo-octahydroxanthene derivatives

Article abstract of DOI:10.1080/10426500802066096

Herein, we describe a green procedure for the one-pot preparation of 1,8-dioxo-octahydroxanthene derivatives by condensation of dimedone and substituted benzaldehydes in the presence of FeCl3-SiO2 as an efficient and heterogeneous catalyst under microwave

Full text of DOI:10.1080/10426500802066096

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Reaction in Dry Media: Silica
Gel Supported Ferric Chloride
Catalyzed Synthesis of 1,8-
Dioxo-octahydroxanthene
Derivatives
a
a
Hamid Reza Shaterian , Asghar Hosseinian
&
a
Majid Ghashang
a
Department of Chemistry, Faculty of Sciences ,
University of Sistan and Baluchestan , Zahedan, Iran
Published online: 03 Nov 2008.
To cite this article: Hamid Reza Shaterian , Asghar Hosseinian & Majid Ghashang
(2008) Reaction in Dry Media: Silica Gel Supported Ferric Chloride Catalyzed Synthesis
of 1,8-Dioxo-octahydroxanthene Derivatives, Phosphorus, Sulfur, and Silicon and the
Related Elements, 183:12, 3136-3144, DOI: 10.1080/10426500802066096
To link to this article: http://dx.doi.org/10.1080/10426500802066096
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Phosphorus, Sulfur, and Silicon, 183:3136–3144, 2008
Copyright © Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500802066096
Reaction in Dry Media: Silica Gel Supported Ferric
Chloride Catalyzed Synthesis of
1,8-Dioxo-octahydroxanthene Derivatives
Hamid Reza Shaterian, Asghar Hosseinian,
and Majid Ghashang
Department of Chemistry, Faculty of Sciences, University of Sistan
and Baluchestan, Zahedan, Iran
Herein, we describe a green procedure for the one-pot preparation of 1,8-dioxo-
octahydroxanthene derivatives by condensation of dimedone and substituted ben-
zaldehydes in the presence of FeCl3 -SiO2 as an efficient and heterogeneous catalyst
under microwave irradiation and thermal conditions. This method has the advan-
tages of high yields, cleaner reactions, efficient and cost-effective method, simple
methodology, short reaction times, easy workup, and greener conditions.
Keywords Aldehyde; dimedone; 1,8-dioxo-octahydroxanthene; FeCl3-SiO2; heteroge-
neous catalyst
INTRODUCTION
Avoiding organic solvents during the reactions in organic synthesis
leads to a clean, efficient, and economical technology (green chem-
istry); safety is largely increased, work-up is considerably simplified,
cost is reduced, increased amounts of reactants can be used in the
some equipment, and the reactivities, and sometimes selectivities, are
enhanced without dilution.1 Due to all these advantages there is an
−3
increasing interest in the use of environmentally benign reagents and
3
procedures. Or, in other words, the absence of solvents coupled with
the high yields and short reaction times often associated with reac-
tions of this type make these procedures very attractive for synthesis.3,4
In the present discussion, we describe the advantages of dry reaction
Received 25 February 2008; accepted 19 March 2008.
We are thankful to the Sistan and Baluchestan University Research Council for the
partial support of this research.
Address correspondence to Hamid Reza Shaterian, Department of Chemistry, Faculty
of Sciences, University of Sistan and Baluchestan, P.O. Box 98135-674, Zahedan, Iran.
E-mail: hrshaterian@hamoon.usb.ac.ir
3136

Synthesis of 1,8-Dioxo-octahydroxanthene Derivatives
3137
techniques coupled with microwave activation and their applications
to organic synthesis using solid supports.
Xanthenes are an important class of organic compounds that
have attracted strong interest due to their useful biological and
5
6
pharmacological properties, such as antibacterial, antiviral, anti-
7
inflammatory activities, as well as efficiency in photodynamic
therapy and antagonist for the paralyzing action of zoxazolamine.
8
9
In addition, they also constitute a structural unit of a series of
natural products and because of the inherent reactivity of the inbuilt
pyran ring are versatile synthesis.10 Furthermore, these compounds
1
1
can be employed as cosmetics, pigments and utilized as potential
biodegradable agrochemicals.12 The synthesis of xanthenediones
usually condenses appropriate active methylene carbonyl compounds
1
3
with aldehydes catalyzed by sulfuric acid or hydrochloric acid.
Recently, many procedures have been reported to synthesis 1,8-
dioxo-octahydroxanthene derivatives by condensation of dime-
1
4
15
done and aldehydes using silica sulfuric acid,
Dowex-50W,
HClO4-SiO2 and PPA-SiO2,16 silica chloride and NaHSO4-
1
7
18
3+
19
SiO2,
p-dodecylbenzenesulfonic acid,
Fe -montmorillonite,
amberlyst-15,20 diammonium hydrogen phosphate, TMSCl, tetra-
21
22
2
3
24
butylammonium hydrogen sulphate and [Hmim]TFA as catalyst.
However, some of the reported methods suffer from drawbacks such as
long reaction time,1
7,20,24
and toxic reagents and by-products. There-
22
fore, a great need still exists for versatile, simple and environmentally
friendly processes.
Herein, we report an efficient one-pot synthesis of 1,8-dioxo-
octahydroxanthene derivatives by the condensation reaction of vari-
ous aromatic aldehydes with dimedone under thermal solvent-free and
microwave conditions in the presence of FeCl3-SiO2 (Scheme 1).
SCHEME 1
RESULTS AND DISCUSSION
For choice optimum conditions, we tried to minimizing the time,
temperature, and amount of the catalyst. Thus, the reaction of
2,5-dimethoxybenzaldehyde and dimedone was selected as model to

3138
H. R. Shaterian et al.
TABLE I FeCl
3
-SiO
2
Catalyzed Multicomponent Synthesis of
9
-(2,5-Dimethoxyphenyl)-3,3,6,6-tetramethyl-3,4,6,7-tetrahydro-2H-
xanthene-1,8(5H,9H)-dione
Method Aa
time (min)/
yield(%)
Method Ba
time (min)/
yield (%)
Microwave
power (W)
◦
b
b
Entry
Catalyst (g)
Temperature ( C)
1
2
3
4
5
6
7
8
9
0.01
0.02
0.03
0.04
0.03
0.03
0.03
0.03
0.03
120
120
120
120
90
60
—
—
—
—
—
—
—
—
30/75
19/83
8/91
7/91
36/74
50/60
—
—
—
—
—
—
—
—
180
300
450
11/67
9/72
5/84
—
—
a
b
Molar ratio: benzaldehyde (1 mmol), dimedone (2 mmol); and isolated yield.
investigate the effects of the catalyst at different reaction tempera-
◦
tures (60, 90, and 120 C) and the different amount of catalyst (0.01,
0
.02, 0.03, and 0.04 g) for method A and the different power of mi-
crowave irradiation (180, 300 and 450 W) for method B. The best result
was obtained by carrying out the reaction with 1:2 molar ratios of alde-
hyde/dimedone and SiO2-FeCl3 (0.03 g) at 120 C (Table I, Method A) or
◦
4
50 W microwave power (Table I, Method B) in solvent-free conditions.
Thus, we prepared a range of aryl 1,8-dioxo-octahydroxanthenes un-
der the optimized reaction conditions: aryl aldehyde (1 equiv), dime-
done (2 equiv) in the presence of FeCl3-SiO2 (0.03 g) (Table II).
As summarized in Table II, several different aromatic aldehydes and
dimedone were reacted in the presences FeCl3-SiO2 as catalyst under
thermal solvent-free and microwave conditions resulting corresponding
aryl 1,8-dioxo-octahydroxanthene in good to excellent yields (Scheme 1,
Table II). The reaction was performed with benzaldehyde containing
withdrawing as well as electron donating groups, but benzaldehyde
with electron donating groups are generally more reactive than their
corresponding benzaldehyde with electron withdrawing groups and
give the desired product at short reaction time with excellent yield
(
Table II).
FeCl3-SiO2 can act as Brønsted and Lewis acid catalysts,26 as illus-
trated in Scheme 2.
The effect of catalyst and their abilities to acts as a Brønsted or Lewis
acid (empty π orbital of Fe in FeCl3-SiO2) in this reactions is unknown.
But, in this suggested mechanism, we have proposed, that an acid-base

Synthesis of 1,8-Dioxo-octahydroxanthene Derivatives
3139
TABLE II Preparation of 1,8-Dioxo-octahydroxanthene Derivatives
Method A
Method B
time (min)/
yield (%)
time (min)/
yield (%)
a
a
Entry
Aldehyde
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
Benzaldehyde
7/90
8/89
8/85
10/92
11/90
14/84
10/87
10/93
6/88
8/91
7/94
50/76
13/86
9/91
5/79
9/78
6/76
7/80
8/85
11/75
9/78
8/81
4/79
6/78
7/80
17/60
10/73
6/82
6/83
5/85
5/80
10/89
2-Chlorobenzaldehyde
3-Chlorobenzaldehyde
4-Chlorobenzaldehyde
2,4-Dichlorobenzaldehyde
3-Nitrobenzaldehyde
4-Nitrobenzaldehyde
4-Methylbenzaldehyde
4-Methoxybenzaldehyde
4-Hydroxybenzaldehyde
4-Hydroxy-3-methoxybenzaldehyde
2-Pyridinecarbaldehyde
Cinnamaldehyde
4-Fluorobenzaldehyde
3-Fluorobenzaldehyde
2-Hydroxybenzaldehyde
2,5-Dimethoxybenzaldehyde
1-Naphthaldehyde
1
1
1
1
1
1
1
1
1
7/89
8/93
8/91
20/95
aYields refer to the pure isolated products. All known products have been reported
previously in the literature and were characterized by comparison of IR and NMR
14−24
spectra with authentic samples.
interaction between FeCl3-SiO2 and loan pair of oxygen polarizes C O
bond of aldehyde.
As reported in the literature, the reaction of dimedone with
aldehydes in the presence of acid catalyst is known to give
ortho-quinone methides (o-QMs). The same o-QMs, generated in
situ, have been reacted with another dimedone to form V in-
termediate. A possible reasonable explanation for this result can
be given by considering the Michael addition of dimedone as
CH acid to o-QMs intermediate is favorable via conjugate addi-
SCHEME 2 Brønsted acidity arising from inductive effect of Lewis acid center
coordinated to a silicasupport.26

3140
H. R. Shaterian et al.
SCHEME 3
TABLE III Comparison Results of FeCl
3
2
-SiO with Other Catalysts
a
Reported in the Literature
Entry Catalyst
Conditions
Time/yield (%)
1 h/97
◦
1
2
3
4
5
6
7
8
9
0
1
Silica sulfuric acid
NaHSO4.SiO2
Solvent-free; 80 C; catalyst
(
0.2 g)
CH3CN; under reflux; catalyst
0.1 g)
6.5 h/90
3.5 h/88
8 h/84.1
5 h/92
(
Tetrabutylammonium
hydrogen sulfate
TMSCl
1,4-dioxane/water: 1/4; r.t.;
catalyst (10 mol%)
CH3CN; under reflux; catalyst
(
1 mmol)
CH3CN; under reflux; catalyst
0.2 g)
ethanol; under reflux; catalyst
0.05 g)
Solvent-free; 80 C; catalyst
0.1 g)
Solvent-free; 100 C; catalyst
0.4 g)
p-Dodecylbenzenesulfonic H2O; ultrasonic; 25–30 C;
Amberlyst-15
(
Fe3 -Montmorillonite
+
6 h/94
(
◦
[Hmim]TFA
3 h/86
(
◦
Dowex-50W
3 h/87
(
◦
1 h/89
acid
PPA-SiO2
catalyst (10 mol%)
Solvent-free; 140 C; catalyst
◦
1
1
0.5 h/92.8
7 min/90
(
10 mol%)
Solvent-free; 120 C; catalyst
0.03 g)
◦
FeCl3-SiO2
(
a
Based on dimedone (2 equiv.), benzaldehyde (1 equiv.)

Synthesis of 1,8-Dioxo-octahydroxanthene Derivatives
3141
tion on α,β-unsaturated carbonyl group. Cyclodehydration of VI
intermediate afford 1,8-dioxo-octahydroxanthene (Scheme 3). To
show the merit of the present work in comparison with re-
ported results in the literature, we compared results of FeCl3-
1
4
15
16
SiO2 with silica sulfuric acid, Dowex-50W, PPA-SiO2, NaHSO4-
1
7
18
3+
19
23
SiO2,
p-dodecylbenzenesulfonic acid,
Fe -montmorillonite,
2
0
22
amberlyst-15, TMSCl, tetrabutylammonium hydrogen sulphate,
and [Hmim]TFA24 in the synthesis of 1,8-dioxo-octahydroxanthene
derivatives. As shown in Table III, FeCl3-SiO2 can act as effec-
tive catalyst with respect to reaction times, yields and the obtained
products.
CONCLUSION
In summary, an efficient method for the one-pot preparation of 1,8-
dioxo-octahydroxanthene derivatives by the condensation of an aro-
matic aldehydes and dimedone using FeCl3-SiO2 as a heterogeneous
catalyst under solvent-free, thermal and microwave conditions with
short reaction times was developed.
EXPERIMENTAL
All reagents were purchased from Merck and Aldrich and used with-
out further purification. All yields refer to isolated products after pu-
rification. Products were characterized by comparison with authentic
1
13
samples and by spectroscopy data (IR, H NMR, and C NMR spec-
tra) and melting point. The NMR spectra were recorded on a Bruker
Avance DPX 500 and 300 MHz instrument. The spectra were measured
in CDCl3 relative to TMS (0.00 ppm). Mass spectra were recorded on
an Agilent Technologies 5973 Network Mass Selective Detector (MSD)
operating at an ionization potential of 70 eV. IR spectra were recorded
on a JASCO FT-IR 460 plus spectrophotometer. All of the compounds
were solid and solid-state IR spectra were recorded using the KBr disk
technique. Melting points were determined in open capillaries with a
BUCHI 510 melting point apparatus and are uncorrected. TLC was
performed on Silica-gel polygram SIL G/UV 254 plates.
Preparation of FeCl -SiO2
3
Acetone solution (600 ml) of FeCl3.6H2O (50 g, or anhydrous FeCl3,
3
6
0 g) and chromatographic grade silica gel (500 g, Merck Kieselgel
0, 70–230 Mesh ASTM) were stirred at room temperature in a rotary

3142
H. R. Shaterian et al.
evaporator until dry and then in high vacuum (0.1 torr) for 3 h, resulting
in the “inactive” FeCl3-SiO2 reagent (yellow powder). This powder was
◦
heated for 1 h at 100 C in a rotary evaporator to give a brownish powder
(
“active” FeCl3-SiO2 reagent).25a
General Procedure for Preparation of 1,8-dioxo-octahydrxan-
thene Derivatives by Using FeCl -SiO as Catalyst
3
2
Solvent-Free Thermal (Method A)
To a mixture of aldehyde (10 mmol), dimedone (20 mmol), FeCl3-
SiO2 (0.3 g) was added and the mixture was inserted in an oil bath
◦
and heated at 120 C for the appropriate time (Table II); completion of
the reaction was indicated by TLC. After completion, the reaction mass
◦
was cooled to 25 C. Then CH2Cl2 was added and the mixture stirred,
until solid crude product was dissolved and filtered; the filtrate solution
was concentrated. The solid product was purified by recrystallization
procedure in aqueous EtOH (30%).
Solvent-Free Microwave Irradiation (Method B)
To a mixture of aldehyde (10 mmol), dimedone (20 mmol), FeCl3-
SiO2 (0.3 g) was added. The mixture was inserted in a microwave oven
(
Samsung, model KE300R) and irradiated at 450 W for the appropriate
time (Table II); completion of the reaction was indicated by TLC. After
completion, the reaction mass was cooled to 25 C. Then CH2Cl2 was
◦
added and the mixture stirred until solid crude product was dissolved
and filtered; the filtrate solution was concentrated. The solid product
was purified by recrystallization procedure in aqueous EtOH (30%).
The desired pure products were characterized by comparison of their
physical data with those of known 1,8-dioxo-octahydrxanthene. The
spectral data of some representative 1,8-dioxo-octahydroxanthenes are
given as follows.
9
-(3-fluorophenyl)-3,3,6,6-tetramethyl-3,4,6,7-tetrahydro-2H-
◦
1
xanthene-1,8(5H,9H)-dione (Table II, Entry 16). [m.p.: 178–179 C]; H
NMR (CDCl3, 500 MHz): δ = 0.99 (s, 6H), 1.10 (s, 6H), 2.20 (q, J =
1
6.3 Hz, 4H), 2.46 (s, 4H), 4.75 (s, 1H), 6.76–6.80 (m, 1H), 6.97–6.93
1
3
(
(
5
1
2
m, 1H), 7.10 (d, J = 7.6 Hz, 1H), 7.14–7.18 (m, 1H) ppm; C NMR
CDCl3, 125 MHz): δ = 27.30, 29.30, 29.35, 31.66, 31.67, 32.12, 40.83,
0.70, 113.18, 113.35, 115.05, 115.18, 115.23, 124.20, 129.24, 129.31,
−1
46.60, 146.64, 161.78, 162.46, 163.73, 196.14 ppm; IR (KBr, cm
)
961, 2873, 1660, 1624, 1590, 1485, 1450, 1361, 1241, 1201, 1165,

Synthesis of 1,8-Dioxo-octahydroxanthene Derivatives
3143
+
1
140, 1003, 930, 769, 696, 575; Mass(m/z (%)): 368.1 (M , 56), 274.1
(21), 273.1 (100), 231.1 (24), 217.1 (16), 161.1 (9), 55.2 (5).
9
-(2-hydroxyphenyl)-3,3,6,6-tetramethyl-3,4,6,7-tetrahydro-2H-
◦
1
xanthene-1,8(5H,9H)-dione (Table II, Entry 17). [m.p.: 206–208 C]; H
NMR (CDCl3, 500 MHz): δ = 0.98 (d, J = 2.5 Hz, 6H), 1.01 (s, 3H), 1.11
(
(
(
s, 3H), 1.96 (q, J = 16.5 Hz, 2H), 2.27–2.58 (m, 6H), 4.68 (s, 1H), 6.98
13
d, J = 4.9 Hz, 3H), 7.11–7.15 (m, 1H), 10.44 (s, 1H) ppm; C NMR
CDCl3, 125 MHz): δ = 26.60, 27.11, 27.66, 29.17, 29.68, 30.97, 32.20,
4
1.53, 43.19, 49.96, 50.59, 111.04, 115.69, 118.28, 124.39, 124.48,
27.42, 128.00, 150.97, 168.84, 170.66, 196.50, 200.55 ppm; IR (KBr,
1
−1
cm ) 3148, 2961, 2884, 1628, 1578, 1489, 1457, 1377, 1313, 1233,
1
186, 1151, 1134, 1079, 1023, 872, 763, 656, 584, 474; Mass(m/z (%)):
+
366.1 (M , 45), 283.1 (21), 282.1 (100), 281.1 (50), 267.1 (10), 227.1
(73), 171.1 (23), 115.1 (13), 83.2 (6), 55.2 (5).
9
-(2,5-dimethoxyphenyl)-3,3,6,6-tetramethyl-3,4,6,7-tetrahydro-
◦
2
H-xanthene-1,8(5H,9H)-dione (Table II, Entry 18). [m.p.: 201–202 C];
1
H NMR (CDCl3, 500 MHz): δ = 0.95 (s, 6H), 1.07 (s, 6H), 2.15 (q, J =
1
6.2 Hz, 4H), 2.40 (q, J = 17.6 Hz, 4H), 3.73 (s, 3H), 3.74 (s, 3H), 4.82
(
s, 1H), 6.62 (dd, J = 3.0, 8.8 Hz, 1H), 6.67 (d, J = 8.8 Hz, 1H), 6.95 (d,
1
3
J = 3.0 Hz, 1H) ppm; C NMR (CDCl3, 125 MHz): δ = 26.81, 29.31,
2
1
1
1
3
1
9.35, 31.97, 40.90, 50.75, 55.50, 55.76, 111.59, 112.70, 113.72, 117.38,
−1
31.79, 152.06, 153.21, 162.68, 196.30 ppm; IR (KBr, cm ) 2962, 2872,
675, 1655, 1617, 1502, 1463, 1350, 1247, 1226, 1165, 1136, 1045,
+
004, 860, 813, 730, 686, 573; Mass(m/z (%)): 410.2 (M , 85), 395.1 (7),
80.1 (28), 379.1 (100), 323.1 (10), 295.1 (12), 273.1 (38), 217.1 (14),
61.1 (14), 83.2 (14), 55.2 (8).
3
,3,6,6-tetramethyl-9-(naphthalen-1-yl)-3,4,6,7-tetrahydro-2H-
◦
1
xanthene-1,8(5H,9H)-dione (Table II, Entry 19). [m.p.: 236–238 C]; H
NMR (CDCl3, 500 MHz): δ = 0.96 (s, 6H), 1.10 (s, 6H), 2.15 (q, J =
1
7
6.3 Hz, 4H), 2.53 (s, 4H), 5.57 (s, 1H), 7.24 (brs, 1H), 7.34 (t, J =
.4 Hz, 1H), 7.47 (t, J = 7.1 Hz, 1H), 7.64 (t, J = 8.0 Hz, 1H), 7.77 (t,
1
3
J = 8.0 Hz, 1H), 8.86 (brs, 1H) ppm; C NMR (CDCl3, 125 MHz): δ =
2
7.00, 27.29, 29.23, 32.11, 40.91, 50.63, 116.59, 124.82, 125.20, 125.50,
25.75, 126.18, 127.32, 128.06, 131.70, 133.56, 142.38, 162.05, 196.40
1
−1
ppm; IR (KBr, cm ) 3049, 2954, 2869, 1667, 1628, 1508, 1466, 1356,
+
1195, 1165, 1142, 1006, 767, 567, 459; Mass(m/z (%)): 400.4 (M , 67),
384.3 (18), 383.3 (57), 274.2 (20), 273.3 (100), 217.2 (21), 189.2 (7),
161.1 (13), 83.2 (5), 55.2 (4).

3144
H. R. Shaterian et al.
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