Preparation of various xanthene derivatives over sulfonic acid functionalized imidazolium salts (SAFIS) as novel, highly efficient and reusable catalysts

Article abstract of DOI:10.1016/j.crci.2012.05.003

In this work, some novel sulfonic acid functionalized imidazolium salts (SAFIS), as a new category of ionic liquids, are synthesized by eco-friendly and simple procedures, and used as highly efficient and reusable catalysts to promote the following one-pot multicomponent organic transformations under solvent-free conditions: (i) the synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes from β-naphthol (2 eq.) and arylaldehydes (1 eq.), (ii) the preparation of tetrahydrobenzo[a]xanthene-11-ones from β-naphthol, arylaldehydes and dimedone, and (iii) the synthesis of 1,8-dioxo-octahydroxanthenes from dimedone (2 eq.) and aromatic aldehydes (1 eq.). Environmentally benign, simple methodologies, easy workup procedure, clean reaction, short reaction time, high yield and easy preparation of the catalysts are some advantages of this work.

Full text of DOI:10.1016/j.crci.2012.05.003

C. R. Chimie 15 (2012) 719–736
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´
Full paper/Memoire
Preparation of various xanthene derivatives over sulfonic acid
functionalized imidazolium salts (SAFIS) as novel, highly efficient
and reusable catalysts
a
a
Mohammad Ali Zolfigol a, , Vahid Khakyzadeh , Ahmad Reza Moosavi-Zare ,
*
Abdolkarim Zare b, Seyedeh Bahareh Azimi c, Zhila Asgari a, Alireza Hasaninejad d
a Faculty of Chemistry, Bu-Ali Sina University, Hamedan 6517838683, Iran
b Department of Chemistry, Payame Noor University, PO Box 19395-4697, Tehran, Iran
c Department of Chemistry, Hamedan branch, Islamic Azad University, Hamedan, Iran
d Department of Chemistry, Faculty of Sciences, Persian Gulf University, Bushehr 75169, Iran
A R T I C L E I N F O
Article history:
A B S T R A C T
Received 3 March 2012
Accepted after revision 2 May 2012
In this work, some novel sulfonic acid functionalized imidazolium salts (SAFIS), as a new
Available online 9 June 2012
category of ionic liquids, are synthesized by eco-friendly and simple procedures, and used
as highly efficient and reusable catalysts to promote the following one-pot multicompo-
Keywords:
nent organic transformations under solvent-free conditions: (i) the synthesis of 14-aryl-
Sulfonic acid functionalized imidazolium
14H-dibenzo[a,j]xanthenes from
b
-naphthol (2 eq.) and arylaldehydes (1 eq.), (ii) the
-naphthol, arylaldehydes and
salt
preparation of tetrahydrobenzo[a]xanthene-11-ones from
b
Ionic liquid
dimedone, and (iii) the synthesis of 1,8-dioxo-octahydroxanthenes from dimedone (2 eq.)
and aromatic aldehydes (1 eq.). Environmentally benign, simple methodologies, easy
workup procedure, clean reaction, short reaction time, high yield and easy preparation of
the catalysts are some advantages of this work.
14-aryl-14H-dibenzo[a,j]xanthene
Tetrahydrobenzo[a]xanthene-11-one
1,8-dioxo-octahydroxanthene
Solvent-free
ß 2012 Published by Elsevier Masson SAS on behalf of Acade´mie des sciences.
1. Introduction
imidazolium salts with Brønsted acidic property, and their
successful applications in organic transformations [6–9],
Ionic liquids (based imidazolium or other organic
cations) have received considerable interest as eco-friendly
solvents, catalystsand reagentsinorganicsynthesisbecause
of their unique properties, such as low volatility, non-
flammability, high thermal stability, negligible vapor
pressure and ability to dissolve a wide range of materials
[1–9]. Among them, Brønsted acidic ionic liquids, with the
useful characteristics of solid acids and mineral liquid acids,
have designed to replace the traditional mineral liquid acids
like sulfuric acid and hydrochloric acid in chemical
procedures [10–14]. Considering the unique properties of
more recently, we have synthesized some sulfonic acid
functionalized imidazolium salts, with Brønsted acidic
property, including ionic liquid 3-methyl-1-sulfonic acid
imidazolium chloride {[Msim]Cl} [10–13], ionic liquid 1,3-
disulfonic acid imidazolium chloride {[Dsim]Cl} and 3-
methyl-1-sulfonic acid imidazolium tetrachloroaluminate
{[Msim]AlCl4} (as a solid) (Figs. 1 and 2) [13], and
successfully applied them as highly efficient catalysts and
reagents in organic synthesis [10–13]. Along this line, in this
presented work, we have reported the preparation of two
sulfonic acid functionalized imidazolium salts (SAFIS), 3-
methyl-1-sulfonic acid imidazolium hexafluorophospha-
te(V) {[Msim]PF6} and 3-methyl-1-sulfonic acid imidazo-
lium tetrafluoroborate {[Msim]BF4} as new ionic liquids
(Fig. 2). We wish to use them as effective catalysts for
* Corresponding author.
E-mailaddresses:zolfi@basu.ac.ir, mzolfigol@yahoo.com(M.A.Zolfigol).
1631-0748/$ – see front matter ß 2012 Published by Elsevier Masson SAS on behalf of Acade´mie des sciences.
http://dx.doi.org/10.1016/j.crci.2012.05.003

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M.A. Zolfigol et al. / C. R. Chimie 15 (2012) 719–736
Xanthene derivatives are of importance as they have
various biological activities such as antiplasmodial [18],
and anti-inflammatory properties [19], and have been
utilized as antagonists for drug-resistant leukemia lines
[20]. Furthermore, these heterocyclic molecules have been
widely used as dyes [21], and in pH-sensitive fluorescent
materials [22] and laser technologies [23]. Many benzox-
anthene derivatives are also potent nonpeptidic inhibitors
of recombinant human calpain I [24], and novel CCR1
receptor antagonists [25]. Therefore, synthesis of
xanthenes is of great importance. Synthesis of 14-aryl-
14H-dibenzo[a,j]xanthenes has been achieved by the one-
Fig. 1. The preparation of sulfonic acid functionalized imidazolium salt
[Dsim]Cl.
different organic transformations. Herein, we have found
that the preparation of 14-aryl-14H-dibenzo[a,j]xanthenes,
tetrahydrobenzo[a]xanthene-11-ones and 1,8-dioxo-octa-
hydroxanthenes can be efficiently performed in the
presence of these ionic liquids under eco-friendly reaction
conditions.
Design of highly efficient chemical reactions, which
provide maximum structural complexity and diversity
with a minimum number of synthetic steps to assemble
compounds, is a major challenge of modern drug discovery
[14]. Recently, multicomponent reactions have emerged as
a highly valuable synthetic tool in the context of modern
drug discovery. Atom economy and convergent character,
simplicity of a one-pot procedure, possible structural
variations, accessible complexity of molecules, and very
large number of accessible compounds are among the
described advantages of multicomponent reactions [15].
Thus, they are perfectly amenable to automation for
combinatorial synthesis [16,17].
pot multicomponent condensation of
b-naphthol (2 eq.)
with aldehydes (1 eq.) (Scheme 1), in the presence of some
catalysts such as selectfluorTM [26], KAl(SO4)2, 12H2O
(alum) [27], Nano-TiO2 [28], MeSO3H [29], iodine [30],
silica sulfuric acid [31], cyanuric chloride [32] and [Et3N-
SO3H]Cl [33]. The best method for preparation of tetra-
hydrobenzo[a]xanthene-11-ones is the one-pot the mul-
ticomponent condensation reaction between
b-naphthol,
arylaldehydes and dimedone (5,5-dimethyl-1,3-cyclohex-
anedione) (Scheme 2) using some catalysts, e.g. sulfamic
acid [34], NaHSO4/ionic liquid ([bmim]BF4) [35], dodeca-
tungstophosphoric acid [36], iodine [37], InCl3/P2O5 [38]
and p-toluenesulfonic acid/ionic liquid ([bmim]BF4) [39].
The most common protocol for the preparation of 1,8-
dioxo-octahydroxanthenes involves the reaction of two
molecules of dimedone with one molecule of aldehydes
PF6
N
N
KCl
SO3H
KPF6
[Msim]PF6
Cl
AlCl4
ClSO3H
AlCl3
N
N
N
N
N
N
SO3H
SO3H
[Msim]AlCl4
[Msim]Cl
NaBF4
BF4
SO3H
N
N
NaCl
[Msim]BF4
Fig. 2. The preparation of the sulfonic acid functionalized imidazolium salts {[Msim]X}.
Scheme 1. The reaction of
b-naphthol with aldehydes catalyzed by the sulfonic acid functionalized imidazolium salts.

M.A. Zolfigol et al. / C. R. Chimie 15 (2012) 719–736
721
Scheme 2. The reaction of
b-naphthol, aldehydes and dimedone catalyzed by the SAFIS.
Scheme 3. The reaction of dimedone with aldehydes under using the SAFIS.
(Scheme 3) [40–42], in the presence of several catalysts,
including [Et3N-SO3H]Cl [33], p-dodecylbenzenesulfonic
acid [43], triethylbenzylammonium chloride [44], dia-
mmonium hydrogen phosphate [45], p-dodecylbenzene-
sulfonic acid under ultrasonic irradiation [46], MCM-41-
SO3H using ultrasonic irradiation [47], SbCl3/SiO2 [48],
silica-supported preyssler nano particles [49], sulfonic acid
on silica gel (SiO2-R-SO3H) [50], and trimethylsilylchloride
[51]. Nevertheless, many of the reported methods are
associated with one or more of the following drawbacks:
(i) low yields, (ii) long reaction times, (iii) the use of large
amount of catalyst, (iv) the use of toxic or expensive
catalysts, and (v) inefficiency of method.
identified by 1H, 13C and 31P NMR as well as mass spectra.
The corresponding spectral data are reported in the
Experimental section.
In another study, to confirm that [Msim]Cl was
completely converted to [Msim]BF4, a solution of AgNO3
in distilled water was added to a solution of [Msim]BF4 in
distilled water. The absence of AgCl precipitate indicates
complete conversion of the [Msim]Cl to [Msim]BF4.
Having the above points in mind, we report here our
results on the efficient solvent-free synthesis of 14-aryl-
14H-dibenzo[a,j]xanthenes, tetrahydrobenzo[a]xanthene-
11-ones and 1,8-dioxo-octahydroxanthenes in the pres-
ence of a catalytic amount of ionic liquids 1,3-disulfonic
acid imidazolium chloride {[Dsim]Cl}, 3-methyl-1-sulfonic
acid imidazolium hexafluorophosphate(V) {[Msim]PF6} or
3-methyl-1-sulfonic acid imidazolium tetrafluoroborate
{[Msim]BF4} under solvent-free conditions (Schemes 1, 2
and 3). Interestingly, these methods for the preparation of
the xanthene derivatives have none of the above-
mentioned drawbacks at all.
2. Results and discussion
At first, ionic liquid 1,3-disulfonic acid imidazolium
chloride {[Dsim]Cl} was prepared by the reaction of
imidazole (1 eq.) with chlorosulfonic acid (2 eq.) in CH2Cl2
(Fig. 1) [13]. In the next step, 3-methyl-1-sulfonic acid
imidazolium chloride {[Msim]Cl} was prepared by the
reaction of 1-methylimidazole with chlorosulfonic acid in
CH2Cl2 with almost 100% atom economy [10–13]. Then, the
other SAFIS, 3-methyl-1-sulfonic acid imidazolium hexa-
fluorophosphate(V) {[Msim]PF6} and 3-methyl-1-sulfonic
acid imidazolium tetrafluoroborate {[Msim]BF4}, were
prepared by anion exchange procedure (Fig. 2). As it is
shown in Fig. 2, [Msim]Cl was reacted with Lewis acids
KPF6 and NaBF4 to afford ionic liquids [Msim]PF6 and
[Msim]BF4, respectively. The structures of the SAFIS were
Fig. 3. Thermal gravimetry (TG) and differential thermal gravimetry
(DTG) of the [Dsim]Cl, [Msim]PF6 and [Msim]BF4.

722
M.A. Zolfigol et al. / C. R. Chimie 15 (2012) 719–736
Table 1
Effect of amounts of the catalysts and temperature on the condensation of
b-naphthol (2 mmol with 4-cholorobenzaldehyde) (1 mmol).
Entry
Catalyst amount (mol%)
Temp. (8C)
[Dsim]Cl
[Msim]PF6
[Msim]BF4
Time
Yielda
(%)
Time
Yielda
(%)
Time
Yielda
(%)
(min)
(min)
(min)
1
2
3
4
5
6
7
8
9
–
110
110
110
110
120
100
90
720
8
32
88
90
98
97
92
93
90
98
720
14
9
29
89
93
98
99
90
91
89
98
720
17
10
7
30
91
90
97
95
91
92
87
98
5
7.5
10
10
10
10
10
15
5
3
6
3
6
6
5
8
11
12
18
7
9
11
15
6
80
14
3
110
a
Isolated yield.
Thermal gravimetric analysis (TGA) of the sulfonic acid
In a plausible mechanism (Scheme 4), at first, aromatic
aldehyde is activated by the acidic group of [Dsim]Cl (or
functionalized imidazolium salts was also studied (Fig. 3).
As thermal gravimetry (TG) and differential thermal
gravimetric (DTG) diagrams indicate, weight losses of
[Dsim]Cl happened in four steps after 150 8C, and
[Msim]PF6 and [Msim]BF4 were decomposed after 200 8C
and 230 8C, respectively. The TG pattern of [Msim]PF6 and
[Msim]BF4 is similar to single stage decomposition in
which no intermediate was exactly identified. But, we
observed multistage decomposition pattern in [Dsim]Cl.
Some weight losses were observed about 10%, 30%, 15%
and 44% which can be related to loss of CH2 = CH2 or HCl,
SO3, CH3CN and ClSO3H, correspondingly. Therefore,
[Msim]PF6, [Msim]BF4 and [Dsim]Cl could be applied as
catalysts under 200 8C, 230 8C and 150 8C.
the other SAFIS) to produce I. Then,
b-naphthol attacks to
the carbonyl group of the activated aldehyde, and affords
intermediate II. Next, by removing H2O from II, orthoqui-
none methide (o-QM, III) is prepared. [Dsim]Cl again
activates intermediate III to give IV as a Michael acceptor.
Afterward, Michael addition of another
b-naphthol to
intermediate IV affords V. Intermediate V converts to VI
after tautomerisation. Finally, by removing H2O from VI,
14-aryl-14H-dibenzo[a,j]xanthene forms.
In another study, the reaction of aldehyde,
b-naphthol
and dimedone, to produce tetrahydrobenzo[a]xanthene-
11-ones, in the presence of the SAFIS was investigated
(Scheme 2). In this regard, the condensation of b-naphthol
Satisfactory application of these catalysts in organic
synthesis encouraged us to use them for preparation of
xanthene derivatives.
In our initial study on the applicability of the SAFIS in
organic synthesis, we investigated the preparation of 14-
(1 mmol) with dimedone (1 mmol) and 4-cholorobenzal-
dehyde (1 mmol) was checked using different amounts of
[Dsim]Cl, [Msim]PF6 or [Msim]BF4, at range of 90–120 8C in
the absence of solvent (Table 3). As it is clear from Table 3,
10 mol% of the SAFIS was sufficient to promote the reaction
efficiently at 110 8C, and afford the product in excellent
yields and in very short reaction times (Table 3, entry 3).
Moreover, [Msim]PF6 and [Msim]BF4 were more effective
than [Dsim]Cl. The solvent-free condensation was also
tested at 110 8C without catalyst in which the reaction did
not significantly progress even after long reaction time
(12 h).
To assess the efficiency and the scope of the SAFIS in the
synthesis of tetrahydrobenzo[a]xanthene-11-ones, various
aromatic aldehydes (including aldehydes with electron-
releasing substituents, electron-withdrawing substituents
and halogens on their aromatic ring) were reacted with
aryl-14H-dibenzo[a,j]xanthenes from
aldehydes in the presence of them (Scheme 1). For this
purpose, the condensation of -naphthol (2 mmol) with 4-
b-naphthol and
b
cholorobenzaldehyde (1 mmol) was examined using dif-
ferent amounts of [Dsim]Cl, [Msim]PF6 or [Msim]BF4 at
various temperatures under solvent-free conditions. The
results are summarized in Table 1. Interestingly, the three
SAFIS were highly efficient, and 10 mol% of them was
sufficient to afford the product in excellent yields and in
very short reaction times at 110 8C (Table 1, entry 3). No
improvement in the reaction results was observed by
increasing the amount of the catalysts and the tempera-
ture. The solvent-free condensation was also tested at
110 8C without catalyst in which the reaction did not
significantly progress even after long reaction time (12 h).
b-naphthol and dimedone in the optimal reaction condi-
tions to furnish the corresponding products in high yields
and in short reaction times. The results are tabulated in
Table 4.
Under the optimal reaction conditions, b-naphthol was
condensed with different aromatic aldehydes (including
aldehydes bearing electron-releasing substituents, elec-
tron-withdrawing substituents or halogens on their
aromatic ring) using [Dsim]Cl, [Msim]PF6 or [Msim]BF4
(Table 2). As it can be seen in Table 2, all catalysts were
highly efficient and general, and gave the desired 14-aryl-
14H-dibenzo[a,j]xanthenes in high yields and short reac-
tion times.
Mechanistically (Scheme 5), at first, aromatic aldehyde
is activated by acidic group of [Msim]X (X = PF6 or BF4) or
[Dsim]Cl to produce I. Then,
b-naphthol attacks to the
carbonyl group of the activated aldehyde, and affords
intermediate II. Next, by removing H2O from II, orthoqui-
none methide (o-QM, III) is prepared. [Msim]X again
activates intermediate III to give IV as a Michael acceptor.
Afterward, Michael addition of dimedone to intermediate

M.A. Zolfigol et al. / C. R. Chimie 15 (2012) 719–736
723
Table 2
The solvent-free synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes using the sulfonic acid functionalized imidazolium salts.
Productb
[Dsim]Cl
[Msim]PF6
[Msim]BF4
Mp 8C
(Lit.)
Time
Yielda
(%)
Time
Yielda
(%)
Time
Yielda
(%)
(min)
(min)
(min)
5
90
7
85
8
88
186–188
(184–185) [28]
3
98
6
98
7
97
284–286
(289–290) [27]
2
97
4
97
5
98
207–209
(206–211) [28]
4
90
8
91
7
88
209–211
(214–216) [28]
3
98
5
95
6
93
186–188
(190–191) [28]
3
99
5
98
7
99
312–314
(311–312) [26]
3
96
4
99
7
94
215–217
(213–214) [26]

724
M.A. Zolfigol et al. / C. R. Chimie 15 (2012) 719–736
Table 2 (Continued )
Productb
[Dsim]Cl
[Msim]PF6
[Msim]BF4
Mp 8C
(Lit.)
Time
Yielda
(%)
Time
Yielda
(%)
Time
Yielda
(%)
(min)
(min)
(min)
5
86
10
91
8
87
212–214
(214–215) [28]
6
99
7
98
8
96
225–227
(227–229) [28]
7
10
9
97
90
91
8
15
14
95
88
85
8
13
18
98
91
88
200–202
(203–205) [27]
289–292
(290–295) [53]
162–164
(163–165) [53]
a
Isolated yield.
b
These reactions were carried out by the reaction of
b-naphthol (2 mmol) with 4-cholorobenzaldehyde (1 mmol) using SAFIS (10 mol%) at 110 8C.
IV affords V. Intermediate
tautomerisation. Finally, tetrahydrobenzo[a]xanthene-
11- one produces by removing H2O from VI.
The last group of xanthenes mentioned in the present
work is 1,8-dioxo-octahydroxanthenes. To optimize the
reaction conditions, the solvent-free condensation of
V
converts to VI after
[Dsim]Cl, [Msim]PF6 or [Msim]BF4, at range of 25–75 8C
was studied (Table 5). As it can be seen in Table 5, [Dsim]Cl
were more effective than [Msim]PF6 or [Msim]BF4, and the
best results were obtained using 10 mol% of the ionic
liquids at 70 8C (Table 5, entry 6). This condensation was
also examined at 70 8C without catalyst under solvent-free
condition in which the reaction did not significantly
progress even after long reaction time (12 h).
dimedone
(2 mmol)
with
4-cholorobenzaldehyde
(1 mmol) (Scheme 3), using different molar ratios of

M.A. Zolfigol et al. / C. R. Chimie 15 (2012) 719–736
725
Scheme 4. The plausible mechanism for the condensation reaction of
b-naphthol with aldehydes using the SAFIS.
After optimization the reaction conditions, the efficacy
of the catalysts was studied using various aromatic
aldehydes to produce 1,8-dioxo-octahydroxanthenes
(Table 6). As it is shown in Table 6, [Dsim]Cl, [Msim]PF6
as well as [Msim]BF4 were highly efficient and general,
and the reaction efficiently proceeded using all kinds of
aldehydes.
According to the application of the SAFIS in the above-
mentioned mechanisms, initially, aromatic aldehyde is
activated by acidic group of [Dsim]Cl (or the others) to give
I. Then, dimedone attacks to the carbonyl group of the
activated aldehyde, and affords intermediate II. Next, by
removing H2O from II, III is prepared. [Msim]X again
activates intermediate III to give IV as a Michael acceptor.
Afterward, Michael addition of dimedone to intermediate
IV affords V. Intermediate converts to VI after
tautomerisation. Finally, 1,8-dioxo-octahydroxanthenes
forms by removing H2O from VI (Scheme 6).
As previsously showed, [Dsim]Cl, [Msim]PF6 and
[Msim]BF4 were highly efficient and general for the
synthesis of the xanthene derivatives. To raise the catalysts
worth, their recoverability and reusability were studied.
V
For this purpose, the reaction of
b-naphthol with
4-chlorobenzaldehyde using [Msim]PF6 was carried out
several times, and the reaction mixtures were combined.
Afterward, H2O was added to the combined reaction
mixtures, stirred for 5 min, and filtered [Msim]PF6 is
soluble in H2O; however, the reaction mixture is not
Table 3
Effect of amounts of the catalysts and temperature on the condensation of
b-naphthol (1 mmol), dimedone (1 mmol) and 4-cholorobenzaldehyde (1 mmol).
Entry
Catalyst amount
(mol%)
Temp.
[Dsim]Cl
[Msim]PF6
[Msim]BF4
(8C)
Time
Yielda
(%)
Time
Yielda
(%)
Time
Yielda
(%)
(min)
(min)
(min)
1
2
3
4
5
6
7
8
9
–
110
110
110
110
120
100
90
720
15
13
10
9
26
80
86
88
70
81
84
80
88
720
13
10
8
22
90
89
93
90
88
88
86
92
720
12
10
7
21
88
91
95
91
90
91
89
95
5
7.5
10
10
10
10
10
15
8
6
11
17
20
10
12
14
17
8
15
17
22
7
80
110
a
Isolated yield.

726
M.A. Zolfigol et al. / C. R. Chimie 15 (2012) 719–736
Table 4
The solvent-free synthesis of tetrahydrobenzo[a]xanthene-11-ones using the sulfonic acid functionalized imidazolium salts.
Productb
[Dsim]Cl
[Msim]PF6
[Msim]BF4
Mp 8C
(Lit.)
Time
Yielda
(%)
Time
Yielda
(%)
Time
Yielda
(%)
(min)
(min)
(min)
15
85
12
90
10
93
148–151
(151–153) [38]
10
88
8
93
7
95
178–179
(180–182) [38]
14
88
95
93
8
9
8
93
93
92
7
9
7
95
95
93
175–178
(–) [39]
7
222–224
(223–225) [52]
6
179–181
(181–182) [36]
15
88
8
93
8
95
185–187
(186–187) [37]

M.A. Zolfigol et al. / C. R. Chimie 15 (2012) 719–736
727
Table 4 (Continued )
Productb
[Dsim]Cl
[Msim]PF6
[Msim]BF4
Mp 8C
(Lit.)
Time
Yielda
(%)
Time
Yielda
(%)
Time
Yielda
(%)
(min)
(min)
(min)
13
14
13
90
85
88
8
11
10
92
83
95
10
13
8
92
85
97
161–164
(–) [39]
169–171
(170–172) [35]
175–178
(178–180) [38]
15
10
14
86
88
83
11
91
90
90
10
93
92
93
167–170
(168–170) [38]
9
8
237–239
(240–241) [38]
10
8
158–160
(159–162) [34]
a
Isolated yield.
b
These reactions were carried out by the condensation of b-naphthol (1 mmol), dimedone (1 mmol) and 4-cholorobenzaldehyde (1 mmol) using SAFIS
(10 mol%) at 110 8C.

728
M.A. Zolfigol et al. / C. R. Chimie 15 (2012) 719–736
Scheme 5. The plausible mechanism for the condensation reaction of
b-naphthol with aldehydes and dimedone catalyzed by the SAFIS.
soluble in H2O. In the aqueous media, a quantity of
[Msim]PF6 hydrolyzed to 1-methylimidazole (as moni-
tored on TLC) and H2SO4. To complete hydrolysis of
[Msim]PF6, and consequently formation of 1-methyli-
midazole, a solution of NaOH (10%) was added to the
filtrate, and stirred for 5 min. The solution was extracted
with t-butylmethyl ether, washed with H2O and dried.
Evaporation of the solvent gave 1-methylimidazole. The
recovered 1-methylimidazole was reacted with chlor-
osulfonic acid to give [Msim]Cl. [Msim]Cl was reacted
with NaPF6 to produce [Msim]PF6. The catalytic activity
of the reproduced [Msim]PF6 was as same as the first
one. The regeneration of this catalyst is summarized in
Fig. 4. [Dsim]Cl and [Msim]BF4 were also reproduced
accordingly.
It should be mentioned that [Msim]Cl and [Msim]AlCl4
were also successfully employed in the synthesis of the
xanthenes derivatives, and the results were similar to
[Dsim]Cl, [Msim]PF6 and [Msim]BF4. Therefore, we did not
mention the results of the application of [Msim]Cl and
[Msim]AlCl4 in the presented work.
The mentioned xanthenes derivatives which produce in
achiral media were racemic. To confirm this subject,
optical activity of the compounds were measured by
polarimeter. This study clearly confirmed the racemization
of the xanthene derivatives in our protocol.
Table 5
Effect of amounts of the catalysts and temperature on the condensation of dimedone (2 mmol) and 4-cholorobenzaldehyde (1 mmol).
Entry
Catalyst Amount
(mol%)
Temp.
[Dsim]Cl
[Msim]PF6
[Msim]BF4
(8C)
Time (min)
Yielda
(%)
Time
Yielda
(%)
Time
Yielda
(%)
(min)
(min)
1
2
3
4
5
6
7
8
9
–
70
70
70
25
45
65
70
75
70
720
20
8
14
70
73
40
50
70
98
96
98
720
25
15
60
30
10
5
13
65
70
35
44
66
95
92
96
720
22
17
60
30
12
6
10
60
71
38
48
68
94
93
94
5
7.5
10
10
10
10
10
15
60
15
4
3
3
4
5
3
4
6
a
Isolated yield.

M.A. Zolfigol et al. / C. R. Chimie 15 (2012) 719–736
729
Table 6
The solvent-free synthesis of 1,8-dioxo-octahydroxanthenes using the sulfonic acid functionalized imidazolium salts.
Productb
[Dsim]Cl
[Msim]PF6
[Msim]BF4
Mp 8C
(Lit.)
Time
Yielda
(%)
Time
Yielda
(%)
Time
Yielda
(%)
(min)
(min)
(min)
6
98
8
95
10
96
199–201
(201–203) [51]
3
97
13
91
15
95
224–226
(228–230) [49]
5
94
85
95
15
11
15
90
87
87
13
13
12
93
81
92
164–166
(168–170) [50]
7
220–222
(217–218) [48]
13
243–245
(248–250) [49]
11
91
14
91
17
88
178–180
(175–176) [48]

730
M.A. Zolfigol et al. / C. R. Chimie 15 (2012) 719–736
Table 6 (Continued )
Productb
[Dsim]Cl
[Msim]PF6
[Msim]BF4
Mp 8C
(Lit.)
Time
Yielda
(%)
Time
Yielda
(%)
Time
Yielda
(%)
(min)
(min)
(min)
10
94
5
98
7
97
216–218
(219–221) [51]
7
90
10
83
13
85
249–251
(250–252) [33]
3
98
5
95
6
94
229–231
(230–232) [51]
5
96
10
93
9
89
186–187
(183–185) [48]
4
96
6
91
8
95
242–244
(240–242) [51]
6
80
3
84
5
85
172–174
(177–178) [50]
a
Isolated yield.
b
These reactions were carried out by the reaction of dimedone (2 mmol) with 4-cholorobenzaldehyde (1 mmol) using SAFIS (10 mol%) at 70 8C.

M.A. Zolfigol et al. / C. R. Chimie 15 (2012) 719–736
731
Scheme 6. The plausible mechanism for the condensation reaction of dimedone and aldehydes in the presence of the SAFIS.
8-dioxo-octahydroxanthenes, by the one-pot multicom-
ponent condensation reaction, were efficiently catalyzed
by these imidazolium salts. The promising points for the
presented methodology are efficiency, generality, high
yields, very short reaction times, cleaner reaction profile,
simplicity, ease of preparation of the catalyst.
KCl
+
PF6
N
N
SO3H
KPF6
i and ii
4. Experimental
+
Cl
N
N
SO3H
4.1. General
N
N
All chemicals were purchased from Merck or Fluka
Chemical Companies. The known products were identified
by comparison of their melting points and spectral data
with those reported in the literature. Progress of the
reactions was monitored by TLC using silica gel SIL G/UV
254 plates. IR spectra were run on a Shimadzu FTIR-8300
ClSO3H
i) The synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes
ii) Addition of NaOH solution
spectrophotometer. The 1H NMR (500 or 300 MHz) and 13
NMR (125 or 75 MHz) were run on a Bruker Avance DPX.
FT-NMR spectrometer ( in ppm). Melting points were
C
Fig. 4. The regeneration of [Msim]PF6.
d
recorded on a Bu¨chi B-545 apparatus in open capillary
tubes. Optical rotations were measured in spectral grade
solvents using a Perkin–Elmer 341 polarimeter.
3. Conclusions
In summary, we have introduced some novel sulfonic
acid functionalized imidazolium salts including [Dsim]Cl,
[Msim]PF6 and [Msim]BF4 as highly efficient, regenerable
catalysts for organic transformations. For instance,
in this work, the synthesis of 14-aryl-14H-dibenzo[a,j]
xanthenes, tetrahydrobenzo[a]xanthene-11-ones and 1,
4.2. Preparation of ionic liquid [Dsim]Cl
To a round-bottomed flask (100 mL) containing imid-
azole (0.340 g, 5 mmol) in CH2Cl2 (50 mL), was added
chlorosulfonic acid (1.177 g, 10.2 mmol) dropwise over a

732
M.A. Zolfigol et al. / C. R. Chimie 15 (2012) 719–736
period of 20 min at room temperature (Fig. 1). After the
addition was completed, the reaction mixture was stirred
for 12 h under pressure of nitrogen (to remove the
produced HCl), stand for 5 min, and the CH2Cl2 was
decanted. The residue was washed with dry CH2Cl2
(3 Â 50 mL) and dried under vacuum to give [Dsim]Cl as
a viscous pale yellow oil in 95% yield, 1.257 g [13].
(0.1 mmol) in a 10 mL round-bottomed flask connected
to a reflux condenser, was stirred in an oil-bath (110 8C).
After completion of the reaction, as monitored by TLC,
the reaction mixture was cooled to room temperature,
H2O (15 mL) was added to it, stirred for 3 min to remove
ionic liquid, and filtered. Then, hot EtOH (2 mL) was
added to the resulting solid (crude product), stirred for
3 min, and filtered (the product is insoluble in EtOH;
however, the starting materials dissolve in EtOH). The
solid residue was washed with EtOH (2 mL) to give the
pure product.
4.3. Preparation of ionic liquid [Msim]Cl
A round-bottomed flask (100 mL) was charged with 1-
methylimidazole (0.410 g, 5 mmol) in dry CH2Cl2 (50 mL),
and then chlorosulfonic acid (0.583 g, 5 mmol) was added
dropwise over a period of 5 min at room temperature
(Fig. 2). After the addition was completed, the reaction
mixture was stirred for 20 min, stand for 5 min, and the
CH2Cl2 was decanted. The residue was washed with dry
CH2Cl2 (3 Â 50 mL) and dried under vacuum to give
[Msim]Cl as a viscous colorless oil in 97% yield, 0.964 g [13].
4.7. Spectral data of 14-aryl-14H-dibenzo[a,j]xanthenes
4.7.1. 14-Phenyl-14H-dibenzo[a,j]xanthene (1a)
Rf (EtOAc/n-hexane: 1/9) = 0.40; 1H NMR (400 MHz,
DMSO-d6):
d (ppm) 6.74 (s, 1H), 6.97 (t, J = 7.6 Hz, 1H), 7.14
(t, J = 7.6 Hz, 2H), 7.45 (t, J = 7.2 Hz, 2H), 7.57 (d, J = 8.8 Hz,
2H), 7.62–7.66 (m, 4H), 7.91–7.93 (m, 4H), 8.70 (d, J = 8.8,
2H); 13C NMR (100 MHz, DMSO-d6):
d (ppm) 37.0, 117.9,
4.4. Preparation of ionic liquids [Msim]PF6 and [Msim]BF4
118.2, 123.9, 124.9, 126.7, 127.4, 128.4, 128.8, 129.1, 129.5,
131.1, 131.4, 146.0, 148.5.
A mixture of [Msim]Cl (0.993 g, 5 mmol) and KPF6
(0.92 g, 5 mmol) or NaBF4 (0.548 g, 5 mmol) in a round-
bottomed flask (100 mL) was stirred for 12 h at 60 8C
(Fig. 2). Afterward, to separate produced ionic liquid from
KCl or NaCl, absolute ethanol (25 mL) was added to the
reaction mixture, stirred for 2 min, and filtered (KCl and
NaCl are insoluble in absolute ethanol). The solvent of the
filtrate was evaporated under vacuum to give [Msim]PF6 or
[Msim]BF4 in 92% (1.421 g) and 94% (1.173 g) yields,
respectively.
4.7.2. 14-(4-Chlorophenyl)-14H-dibenzo[a,j]xanthene (1b)
Rf (EtOAc/n-hexane: 1/9) = 0.50; 1H NMR (300 MHz,
DMSO-d6):
7.46–7.64 (m, 10H), 8.92 (d, J = 7.79 Hz, 2H), 8.66 (d,
J = 7.6 Hz, 2H); 13C NMR (75 MHz, DMSO-d6):
(ppm) 36.3,
d (ppm) 6.76 (s, 1H), 7.18 (d, J = 6.8 Hz, 2H),
d
117.4, 118.1, 123.4, 123.7, 125.0, 127.4, 128.8, 129.1, 129.6,
130.1, 131.1, 131.2, 144.8, 148.4.
4.7.3. 14-(3-Chlorophenyl)-14H-dibenzo[a,j]xanthene (1c)
Rf (EtOAc/n-hexane: 1/9) = 0.20; 1H NMR (300 MHz,
4.5. Spectral data of [Msim]PF6 and [Msim]BF4
DMSO-d6): d (ppm) 6.74 (s, 1H), 7.01 (d, J = 8.1, 1H), 7.13 (t,
J = 7.8, 1H), 7.42 (t, J = 7.2, 2H), 7.52–7.66 (m, 6H), 7.91 (d,
J = 8.7, 4H), 8.67 (d, J = 8.7, 2H); 13C NMR (75 MHz, DMSO-
4.5.1. 3-Methyl-1-sulfonic acid imidazolium
hexafluorophosphate(V) {[Msim]PF6}
d6):
d (ppm) 36.5, 117.2, 118.1, 123.7, 125.1, 126.8, 127.0,
1H NMR (300 MHz, DMSO-d6):
d
(ppm) 3.82 (s, 3H,
CH3), 7.55 (s, 2H), 8.90 (s, 1H), 14.15 (s, 1H); 13C NMR
(75 MHz, DMSO-d6): (ppm) 35.6, 119.9, 123.4, 136.0;
127.5, 127.9, 129.1, 129.7, 130.7, 131.1, 131.2, 133.5, 148.2,
148.5.
d
CHN Analysis: Anal. Calcd for C4H7F6N2O3PS: C, 15.59; H,
2.29; N, 9.09. Found: C, 15.67; H, 2.37; N, 8.94; MS: m/
z = 309 (M+ + 1), 308 (M+), 163 (M+-PF6), 293 (M+-CH3), 227
(M+-SO3H); 31P NMR (121 MHz, DMSO-d6): À143.7 (septet,
1J (P,F) = 711 Hz, PF6À).
4.7.4. 14-(2-Chlorophenyl)-14H-dibenzo[a,j]xanthene (1d)
Rf (EtOAc/n-hexane: 1/9) = 0.75; 1H NMR (300 MHz,
DMSO-d6):
d (ppm) 6.64 (s, 1H), 6.91–7.03 (m, 2H), 7.27 (d,
J = 7.7 Hz, 2H), 7.38–7.50 (m, 5H), 7.57–7.70 (m, 2H), 7.76–
7.90 (m, 4H), 8.54 (d, J = 8.4 Hz, 1H); 13C NMR (75 MHz,
DMSO-d6):
d (ppm) 34.8, 116.9, 118.2, 123.3, 124.9, 127.4,
4.5.2. 3-Methyl-1-sulfonic acid imidazolium
tetrafluoroborate {[Msim]BF4}
128.5, 128.8, 129.2, 129.8, 130.2, 130.3, 130.9, 131.4, 132.0,
143.2, 148.7.
1H NMR (300 MHz, DMSO-d6):
d
(ppm) 3.83 (s, 3H,
CH3), 7.51 (s, 1H), 7.56 (s, 1H), 8.89 (s, 1H), 14.05 (s, 1H);
13C NMR (75 MHz, DMSO-d6):
(ppm) 35.7, 119.9, 123.5,
4.7.5. 14-(3-Bromophenyl)-14H-dibenzo[a,j]xanthene (1e)
d
Rf (EtOAc/n-hexane: 1/9) = 0.25; 1H NMR (300 MHz,
135.9; CHN Analysis: Anal. Calcd for C4H7BF4N2O3S: C,
19.22; H, 2.82; N, 11.21. Found: C, 18.97; H, 2.94; N, 11.03;
MS: m/z = 251 (M+ + 1), 250 (M+), 163 (M+-BF4), 235 (M+-
CH3), 169 (M+-SO3H).
DMSO-d6): d (ppm) 6.63 (s, 1H), 6.90–7.02 (m, 2H), 7.26 (d,
J = 7.7 Hz, 2H), 7.37–7.49 (m, 5H), 7.58 (t, J = 7.9 Hz, 2H),
7.85–7.89 (m, 4H), 8.53 (d, J = 8.5 Hz, 1H); 13C NMR
(75 MHz, DMSO-d6):
d (ppm) 34.8, 116.9, 118.2, 123.3,
124.9, 127.4, 128.5, 128.8, 129.1, 129.8, 130.2, 130.3, 130.9,
131.4, 132.0, 143.2, 148.6.
4.6. General procedure for the synthesis of 14-aryl-14H-
dibenzo[a,j]xanthene derivatives
4.7.6. 14-(4-Nitrophenyl)-14H-dibenzo[a,j]xanthene (1f)
A mixture of
b
-naphthol (0.42 g, 2 mmol), aldehyde
Rf (EtOAc/n-hexane: 1/9) = 0.44; 1H NMR (300 MHz,
(1 mmol) and sulfonic acid functionalized imidazolium salt
DMSO-d6):
d (ppm) 6.95 (s, 1H), 7.43 (t, J = 7.2 Hz, 3H),

M.A. Zolfigol et al. / C. R. Chimie 15 (2012) 719–736
733
7.58–7.65 (m, 4H), 7.81 (d, J = 7.5 Hz, 1H), 7.90–7.95 (m,
4H), 8.14 (d, J = 7.8, 1H), 8.45 (s, 1H), 8.72 (d, J = 8.4 Hz, 2H);
13C NMR (75 MHz, DMSO-d6):
(ppm) 36.4, 116.9, 118.2,
4.8. General procedure for the synthesis of
tetrahydrobenzo[a]xanthene-11-ones derivatives
d
122.0, 123.6, 125.2, 127.7, 129.1, 130.0, 130.4, 131.11,
134.7, 147.9, 148.3, 148.6.
A mixture of b-naphthol (0.144 g, 1 mmol), dimedone
(0.140 g, 1 mmol), aldehyde (1 mmol) and SAFIS
(0.1 mmol) in a 10 mL round-bottomed flask connected
to a reflux condenser, was stirred in an oil-bath (110 8C).
After completion of the reaction, as monitored with TLC,
the reaction mixture was cooled to room temperature, H2O
(15 mL) was added to it, stirred for 3 min to remove ionic
liquid, and filtered. The crude product was recrystallized
from ethanol to afford the pure product.
4.7.7. 14-(3-Nitrophenyl)-14H-dibenzo[a,j]xanthene (1g)
Rf (EtOAc/n-hexane: 1/9) = 0.20; 1H NMR (300 MHz,
DMSO-d6):
7.43–7.48 (m, 2H), 7.55–7.71 (m, 4H), 7.88–8.03 (m, 7H),
8.66 (d, J = 8.4 Hz, 2H); 13C NMR (75 MHz, DMSO-d6):
d (ppm) 6.91 (s, 1H), 7.11–7.25 (m, 1H),
d
(ppm) 36.7, 116.6, 118.2, 120.1, 123.6, 124.2, 125.2,
127.6, 129.1, 129.5, 130.0, 131.1, 131.2, 134.2, 146.3,
148.4, 153.1.
4.9. Spectral data of tetrahydrobenzo[a]xanthene-11-ones
4.7.8. 14-(2-Nitrophenyl)-14H-dibenzo[a,j]xanthene (1h)
4.9.1. 9,9-dimethyl-12-phenyl-9,10-dihydro-8H-
benzo[a]xanthen-11(12H)-one (2a)
Rf (EtOAc/n-hexane: 1/9) = 0.36; 1H NMR (300 MHz,
DMSO-d6):
d
(ppm) 6.94 (s, 1H), 7.41–7.46 (m, 3H), 7.56–
Rf (EtOAc/n-hexane: 1/9) = 0.40; 1H NMR (300 MHz,
7.65 (m, 4H), 7.79 (d, J = 2.1, 1H), 7.89–7.94 (m, 4H), 8.13 (d,
J = 7.8, 1H), 8.45 (s, 1H), 8.70 (d, J = 6, 2H); 13C NMR
DMSO-d6): d (ppm) 0.84 (s, 3H), 1.02 (s, 3H), 2.09 (d,
J = 16.2 Hz, 1H), 2.30 (d, J = 16.2 Hz, 1H), 2.60 (Distorted AB
System, 2H), 5.54 (s, 1H), 7.00 (t, J = 7.2 Hz, 1H), 7.14 (t,
J = 7.8 Hz, 2H), 7.27 (d, J = 7.8 Hz, 2H), 7.36–7.48 (m, 3H),
7.89 (d, J = 8.5 Hz 2H), 8.01 (d, J = 8.4 Hz, 1H), 13C NMR
(75 MHz, DMSO-d6):
d (ppm) 36.4, 116.9, 118.1, 122.0,
122.5, 123.6, 125.2, 127.7, 129.1, 130.0, 130.4, 131.1, 134.7,
138.2, 147.9, 148.3, 148.6.
(75 MHz, DMSO-d6):
d (ppm) 26.6, 29.2, 32.3, 34.5,40.7,
4.7.9. 14-(4-Methylphenyl)-14H-dibenzo[a,j]xanthene (1i)
50.5, 113.6, 117.6, 117.7, 123.7, 125.4, 126.6, 127.6, 128.5,
128.6, 129.0, 129.5, 131.0, 131.5, 145.3, 147.6, 164.3, 196.2.
Rf (EtOAc/n-hexane: 1/9) = 0.42; 1H NMR (300 MHz,
DMSO-d6):
2H), 7.40–7.61 (m, 8H), 7.88 (t, J = 2.7, 4H), 8.61 (d, J = 8.7,
2H); 13C NMR (75 MHz, DMSO-d6):
(ppm) 20.8, 37.4,
117.9, 118.1, 123.8, 124.9, 127.3, 128.2, 129.0, 129.3, 129.3,
131.1, 131.3, 135.8, 143.0, 148.3.
d (ppm) 2.01 (s, 3H), 6.63 (s, 1H), 6.90 (d, J = 7.2,
4.9.2. 12-(4-chlorophenyl)-9,9-dimethyl-9,10-dihydro-8H-
benzo[a]xanthen-11(12H)-one (2b)
d
Rf (EtOAc/n-hexane: 1/9) = 0.50; 1H NMR (500 MHz,
DMSO-d6):
d (ppm) 0.86 (s, 3H), 1.04 (s, 3H), 2.12 (d,
J = 16.1 Hz, 1H), 2.32 (d, J = 16.1 Hz, 1H), 2.56 (d, J = 17.3 Hz,
1H), 2.66 (d, J = 17.4 Hz, 1H), 5.58 (s, 1H), 7.23 (d, J = 8.4 Hz,
2H), 7.30 (d, J = 8.4 Hz, 2H), 7.41–7.49 (m, 3H), 7.89–7.92
(m, 2H), 7.99 (d, J = 8.3 Hz, 1H), 13C NMR (125 MHz, DMSO-
4.7.10. 14-(4-Methoxyphenyl)-14H-dibenzo[a,j]xanthene
(1j)
Rf (EtOAc/n-hexane: 1/9) = 0.44; 1H NMR (300 MHz,
DMSO-d6):
2H), 7.19–7.62 (m, 8H), 7.87–7.92 (m, 4H), 8.64 (d, J = 8.7,
2H); 13C NMR (75 MHz, DMSO-d6):
(ppm) 36.0, 55.3,
d
(ppm) 3.52 (s, 3H), 6.63 (s, 1H), 6.67 (d, J = 7.5,
d6): d (ppm) 27.0, 29.6, 32.7, 32.4, 41.0, 50.9, 113.6, 117.5,
118.0, 124.0, 125.9, 128.1, 128.9, 129.4, 130.2, 130.8, 131.3,
131.6, 131.9, 144.6, 148.0, 164.8, 196.7.
d
114.1, 118.1, 123.9, 124.9, 127.9, 124.9, 127.3, 129.2, 131.1,
135.7, 138.1, 147.0, 149.4, 157.9.
4.9.3. 12-(3-chlorophenyl)-9,9-dimethyl-9,10-dihydro-8H-
benzo[a]xanthen-11(12H)-one (2c)
4.7.11. 4-(14H-dibenzo[a,j]xanthen-14-yl)-N,N-
dimethylaniline (1k)
Rf (EtOAc/n-hexane: 1/9) = 0.22; 1H NMR (500 MHz,
DMSO-d6):
d (ppm) 0.88 (s, 3H), 1.03 (s, 3H), 2.11 (d,
Rf (EtOAc/n-hexane: 1/9) = 0.32; 1H NMR (DMSO,
J = 12.8 Hz, 1H), 2.32 (d, J = 16.1 Hz, 1H), 2.61 (Distorted AB
System, 2H), 5.60 (s, 1H), 7.11 (s, 1H), 7.19 (d, J = 4.4 Hz,
2H), 7.36 (s, 1H), 7.40–7.50 (m, 3H), 7.89–8.01 (m, 2H),
8.02 (d, J = 8.3 Hz, 1H), 13C NMR (125 MHz, DMSO-d6):
d
300 MHz):
1H), 7.37–7.92 (m, 12H), 8.64 (d, J = 8, 2H), 13C NMR (CDCl3,
75 MHz): 36.0, 40.8, 112.6, 118.1, 118.4, 123.9, 124.8,
d 2.60 (s, 6H), 6.42 (d, J = 7.2 Hz, 2H), 6.56 (s,
d
127.2, 128.8, 128.9, 129.0, 131.1, 131.4, 133.8, 148.3, 149.0.
MS: m/z = 402 (M+ + 1), 401 (M+), 357 (M+-N(CH3)2), 281
(M+-N,N-dimethylaniline).
(ppm) 27.0, 29.6, 32.7, 34.7, 41.0, 50.9, 113.5, 117.3, 118.0,
124.0, 125.9, 127.2, 127.6, 128.2, 128.8, 129.4, 130.3, 130.9,
131.3, 131.9, 133.5, 148.03, 148.07, 165.0, 196.7.
4.7.12. 14-(4-Benzyloxyphenyl)-14H-dibenzo[a,j]xanthene
(1l)
4.9.4. 12-(2,3-dichlorophenyl)-9,9-dimethyl-9,10-dihydro-
8H-benzo[a]xanthen-11(12H)-one (2d)
Rf (EtOAc/n-hexane: 1/9) = 0.30; 1H NMR (300 MHz,
Rf (EtOAc/n-hexane: 1/9) = 0.35; 1H NMR (500 MHz,
DMSO-d6):
d
(ppm) 4.42 (s, 2H), 4.82 (s, 1H), 6.65 (s, 1H),
DMSO-d6): d (ppm) 0.88 (s, 3H), 1.06 (s, 3H), 2.10 (d,
6.75 (d, J = 7.8 Hz, 1H), 7.27 (s, 5H), 7.41–7.78 (m, 8H), 7.88
(t, J = 6.4, 4H) 8.66 (d, J = 8.3, 2H); 13C NMR (75 MHz,
J = 16.0 Hz, 1H), 2.32 (d, J = 16.0 Hz, 1H), 2.57 (d, J = 17.3 Hz,
1H), 2.69 (d, J = 17.3 Hz, 1H), 5.86 (s, 1H), 7.16–7.22 (m, 1),
7.27 (s, 1H), 7.36 (d, J = 7.7 Hz, 1H), 7.41–7.43 (m, 2H), 7.50
(t, J = 7.8 Hz, 1H), 7.91 (t, J = 6.6 Hz, 2H), 8.04 (d, J = 8.4 Hz,
DMSO-d6):
d (ppm) 36.2, 62.5, 114.9, 118.0, 123.8, 124.8,
127.2, 127.9, 128.1, 128.7, 129.0, 129.2, 129.3, 131.1, 131.3,
137.3, 138.3, 148.3, 157.1. MS: m/z = 465 (M+ + 1), 464
(M+), 373 (M+-C7H7), 281 (M+-C13H11O).
1H), 13C NMR (125 MHz, DMSO-d6):
32.6, 32.6, 41.1, 51.0, 113.3, 118.1, 123.7, 125.9, 126.3,
d (ppm) 27.0, 29.6,

734
M.A. Zolfigol et al. / C. R. Chimie 15 (2012) 719–736
127.7, 128.1, 128.8, 129.5, 129.6, 130.5, 131.0, 131.7, 131.8,
132.9, 137.3, 148.2, 165.2, 196.6.
123.0, 123.6, 125.6, 127.9, 129.1, 130.2, 130.8, 131.5, 135.3,
147.3, 147.7, 148.0, 164.8, 196.4.
4.9.5. 12-(2,4-Dichlorophenyl)-9,9-dimethyl-8,9,10,12-
tetrahydrobenzo[a]xanthen-11-one (2e)
4.9.10. 9,9-dimethyl-12-(3-nitrophenyl)-9,10-dihydro-8H-
benzo[a]xanthen-11(12H)-one (2j)
Rf (EtOAc/n-hexane: 1/9) = 0.50; 1H NMR (500 MHz,
Rf (EtOAc/n-hexane: 1/9) = 0.15; 1H NMR (500 MHz,
DMSO-d6):
d
(ppm) 0.89 (s, 3H), 1.05 (s, 3H), 2.09 (d,
DMSO-d6): d (ppm) 0.84 (s, 3H), 1.04 (s, 3H), 2.13 (d,
J = 16.0 Hz, 1H), 2.31 (d, J = 16.0 Hz, 1H), 2.65 (d, J = 16.8 Hz,
1H), 2.67 (d, J = 17.3 Hz, 1H), 5.77 (s, 1H), 7.22–7.28 (m,
2H), 7.37–7.42 (m, 3H), 7.47–7.50 (m, 1H), 7.88–7.91 (m,
2H), 8.03 (d, J = 8.4 Hz, 1H), 13C NMR (125 MHz, DMSO-d6):
J = 16.0 Hz, 1H), 2.33 (d, J = 16.1 Hz, 1H), 2.64 (Distorted AB
System, 2H), 5.77 (s, 1H), 7.40–7.49 (m, 4H), 7.73 (d,
J = 7.8 Hz, 1H), 7.89–7.95 (m, 3H), 8.03 (d, J = 8.4 Hz, 1H),
8.17 (t, J = 1.8 Hz, 1H), 13C NMR (125 MHz, DMSO-d6):
d
d
(ppm) 27.0, 29.5, 32.5, 32.6, 41.1, 51.0, 118.0, 123.7,
(ppm) 27.0, 29.5, 32.7, 34.8, 41.7, 50.8, 113.2, 116.7, 117.0
118.0, 122.3, 123.4, 124.0, 126.0, 128.3, 129.5, 130.6, 131.2,
132.0, 135.6, 147.7, 148.1, 148.4, 165.2, 196.8.
125.9, 127.5, 128.1, 128.3, 129.6, 129.7, 130.5, 131.6, 131.8,
132.5, 133.7, 140.7, 148.2, 165.1, 196.5.
4.9.6. 12-(4-bromophenyl)-9,9-dimethyl-9,10-dihydro-8H-
benzo[a]xanthen-11(12H)-one (2f)
4.9.11. 12-(3-hydroxyphenyl)-9,9-dimethyl-9,10-dihydro-
8H-benzo[a]xanthen-11(12H)-one (2k)
Rf (EtOAc/n-hexane: 1/9) = 0.40; 1H NMR (500 MHz,
Rf (EtOAc/n-hexane: 1/9) = 0.19; 1H NMR (300 MHz,
DMSO-d6):
d
(ppm) 0.86 (s, 3H), 1.04 (s, 3H), 2.12 (d,
DMSO-d6): d (ppm) 0.90 (s, 3H), 1.05 (s, 3H), 2.15 (d,
J = 16.0 Hz, 1H), 2.32 (d, J = 16.0 Hz, 1H), 2.61 (Distorted AB
System, 2H), 5.56 (s, 1H), 7.24 (d, J = 8.3 Hz, 2H), 7.36 (d,
J = 8.3 Hz, 2H), 7.40–7.49 (m, 3H), 7.90 (t, J = 5.0 Hz 2H),
J = 16.1 Hz, 1H), 2.32 (d, J = 16.1 Hz, 1H), 2.54 (Distorted AB
System, 2H), 5.49 (s, 1H), 6.45 (dd, J = 6.3, J = 1.5, 4H), 6.66
(s, 1H), 6.73 (d, J = 7.1 Hz, 1H), 6.96 (t, J = 7.8 Hz, 1H), 7.42–
7.89 (m, 3H), 7.90 (d, J = 9.0 Hz, 2H), 8.01 (d, J = 8.4 Hz, 1H),
7.98 (d, J = 8.4 Hz, 1H), 13C NMR (125 MHz, DMSO-d6):
d
(ppm) 27.1, 29.6, 32.7, 34.5, 41.0, 50.9, 113.5, 117.4, 118.0,
120.1, 124.0, 125.9, 128.1, 129.4, 130.2, 131.2, 131.3,
131.91, 131.96, 145.0, 148.0, 164.8, 196.7.
9.20 (s, 1H), 13C NMR (75 MHz, DMSO-d6):
d (ppm) 27.1,
29.6, 32.7, 34.8, 41.1, 51.0, 114.1, 115.9, 118.0, 118.2,
119.8, 124.1, 125.8, 127.9, 129.3, 129.8, 131.6, 131.9, 147.0,
148.0, 157.9, 164.5. 196.7.
4.9.7. 12-(3-bromophenyl)-9,9-dimethyl-9,10-dihydro-8H-
benzo[a]xanthen-11(12H)-one (2g)
4.9.12. 9,9-dimethyl-12-o-tolyl-9,10-dihydro-8H-
benzo[a]xanthen-11(12H)-one (2l)
Rf (EtOAc/n-hexane: 1/9) = 0.35; 1H NMR (500 MHz,
DMSO-d6):
d
(ppm) 0.88 (s, 3H), 1.05 (s, 3H), 2.13 (d,
Rf (EtOAc/n-hexane: 1/9) = 0.45; 1H NMR (500 MHz,
J = 16.1 Hz, 1H), 2.31 (d, J = 16.1 Hz, 1H), 2.62 (Distorted AB
System, 2H), 5.52 (s, 1H), 6.85 (d, J = 6.2 Hz, 1H), 7.03–7.07
(m, 2H), 7.11 (s, 1H), 7.40–7.50 (m, 3H), 7.89 (d, J = 8.7 Hz
2H), 8.04 (d, J = 8.4 Hz, 1H), 13C NMR (125 MHz, DMSO-d6):
DMSO-d6): d (ppm) 0.87 (s, 3H), 1.06 (s, 3H), 2.11 (d,
J = 15.5 Hz, 1H), 2.12 (s, 3H), 2.31 (d, J = 16.1 Hz, 1H), 2.56
(d, J = 17.2 Hz, 1H), 2.66 (d, J = 17.3 Hz, 1H), 5.52 (s, 1H),
6.96 (d, J = 7.9 Hz, 2H), 7.16 (d, J = 7.9 Hz, 2H), 7.39–7.49 (m,
3H), 7.89 (d, J = 8.6 Hz, 2H), 8.02 (d, J = 8.4 Hz, 1H) 13C NMR
d
(ppm) 27.0, 29.6, 32.7, 34.9, 41.1, 51.3, 114.1, 118.0,
118.2, 124.1, 125.8, 126.2, 127.7, 127.9, 128.8, 129.3, 129.5,
129.8, 131.5, 131.9, 137.9, 145.7, 148.0, 164.9, 196.7.
(125 MHz, DMSO-d6): d (ppm) 21.3, 27.1, 29.7, 32.7, 34.5,
41.1, 51.0, 114.1, 118.0, 118.3, 124.1, 125.7, 127.9, 128.8,
129.3, 129.5, 129.8, 131.5, 131.9, 136.0, 142.8, 147.9, 164.5,
196.7.
4.9.8. 12-(2-bromophenyl)-9,9-dimethyl-9,10-dihydro-8H-
benzo[a]xanthen-11(12H)-one (2h)
Rf (EtOAc/n-hexane: 1/9) = 0.36; 1H NMR (500 MHz,
4.10. General procedure for the synthesis of 1,8-dioxo-
octahydroxanthene derivatives
DMSO-d6):
d (ppm) 0.89 (s, 3H), 1.06 (s, 3H), 2.09 (d,
J = 16 Hz, 1H), 2.32 (d, J = 16 Hz, 3H), 2.57 (d, J = 17.4 Hz,
1H), 2.70 (d, J = 17.3 Hz, 1H), 5.76 (s, 1H), 6.97–7.00 (m,
1H), 7.18 (t, J = 7.2 Hz, 1H), 7.22 (s, 1H), 7.41–7.43 (m, 2H),
7.47–7.51 (m, 2H), 7.89–7.92 (m, 2H), 8.20 (d, J = 16 Hz,
To a mixture of dimedone (2 mmol) and aldehyde
(1 mmol) in a 10 mL round-bottomed flask connected to a
reflux condenser, SAFIS (0.1 mmol) was added. The
resulting mixture was stirred in an oil-bath (70 8C), and
the reaction was monitored by TLC. After completion of the
reaction, H2O (5 mL) added to the mixture, stirred for 3 min
to remove ionic liquid and filtered. The solid residue was
recrystallized from EtOH to give the product.
1H), 13C NMR (125 MHz, DMSO-d6):
d (ppm) 27.0, 29.7,
32.6, 35.5, 41.2, 51.1, 118.1, 123.5, 124.3, 125.9, 127.9,
128.7, 129.1, 129.5, 130.3, 131.83, 131.87, 133.8, 148.1,
164.8, 196.5.
4.9.9. 9,9-dimethyl-12-(4-nitrophenyl)-9,10-dihydro-8H-
benzo[a]xanthen-11(12H)-one (2i)
4.11. Spectral data of 1,8-dioxo-octahydroxanthenes
Rf (EtOAc/n-hexane: 1/9) = 0.20; 1H NMR (300 MHz,
DMSO-d6):
d
(ppm) 0.82 (s, 3H), 1.02 (s, 3H), 2.11 (d,
4.11.1. 3,3,6,6-Tetramethyl-9-(phenyl)-1,8-dioxo-
octahydroxanthene (3a)
J = 15.9 Hz, 1H), 2.32 (d, J = 16.2 Hz, 1H), 2.63 (Distorted AB
System, 2H), 5.75 (s, 1H), 7.38–7.48 (m, 4H), 7.72 (d,
J = 7.5 Hz, 1H), 7.88–7.94 (m, 3H), 8.02 (d, J = 8.4 Hz, 1H),
8.15 (s, 1H), 13C NMR (75 MHz, DMSO-d6):
Rf (EtOAc/n-hexane: 1/9) = 0.25; 1H NMR (500 MHz,
DMSO-d6):
d (ppm) 0.90 (s, 6H), 1.04 (s, 6H), 2.09 (d,
d
(ppm) 26.6,
J = 16.1 Hz, 2H), 2.27 (d, J = 16.2 Hz, 2H), 2.53 (d, J = 17.1 Hz,
2H), 2.58 (d, J = 17.7 Hz, 2H), 4.53 (s, 1H), 7.10 (t, J = 7.0 Hz,
29.1, 32.4, 34.4, 40.8, 50.4, 112.8, 116.4, 117.6, 121.9,

M.A. Zolfigol et al. / C. R. Chimie 15 (2012) 719–736
735
1H), 7.18 (d, J = 7.0 Hz, 2H), 7.21 (t, J = 7.20 Hz, 2H); 13C
NMR (125 MHz, DMSO-d6): (ppm) 27.7, 29.6, 32.3, 32.6,
J = 6.9 Hz, 2H); 13C NMR (125 MHz, CDCl3):
27.8, 29.7, 31.9, 32.6, 41.3, 51.2, 116.2, 128.7, 129.2, 136.1,
141.6, 162.5, 196.8.
d
(ppm) 21.5,
d
41.3, 51.2, 116.1, 126.8, 128.4, 128.8, 144.5, 162.7, 196.8.
4.11.2. 3,3,6,6-Tetramethyl-9-(4-nitro-phenyl)-1,8-dioxo-
octahydroxanthene (3b)
4.11.8. 3,3,6,6-Tetramethyl-9(5-bromo-2-hydroxy-Phenyl)-
1,8-dioxo-octahydroxanthene (3h)
Rf (EtOAc/n-hexane: 1/9) = 0.36; 1H NMR (500 MHz,
Rf (EtOAc/n-hexane: 1/9) = 0.22; 1H NMR (500 MHz,
CDCl3):
d
(ppm) 0.99 (s, 6H), 1.12 (s, 6H), 2.16 (d,
DMSO-d6): d (ppm) 0.90 (s, 6H), 0.97 (s, 3H), 1.05 (s, 3H),
J = 16.3 Hz, 2H), 2.26 (d, J = 16.3 Hz, 2H), 2.51 (t,
J = 18.7 Hz, 4H), 4.83 (s, 1H), 7.48 (d, J = 8.2 Hz, 2H), 8.08
2.04 (d, J = 15.8 Hz, 2H), 2.25 (d, J = 15.9 Hz, 2H), 2.34 (d,
J = 17.3 Hz, 2H), 2.55 (d, J = 17.4 Hz, 2H), 5.04 (s, 1H), 6.95
(d, J = 8.64 Hz, 1H), 7.04 (s, 1H), 7.28 (d, J = 8.60 Hz, 1H),
(2H, J = 8.2 Hz, 2H); 13C NMR (125 MHz, CDCl3):
d (ppm)
27.7, 29.6, 32.6, 32.8, 41.2, 51.0, 114.9, 123.8, 129.8, 146.8,
152.0, 163.5, 196.7.
10.59 (s, 1H); 13C NMR (125 MHz, DMSO-d6):
d (ppm) 26.9,
28.4, 30.0, 32.5, 51.2, 100.4, 111.3, 116.3, 129.1, 130.6,
131.4, 149.8, 165.3, 196.5.
4.11.3. 3,3,6,6-Tetramethyl-9-(3-nitro-phenyl)-1,8-dioxo-
octahydroxanthene (3c)
4.11.9. 3,3,6,6-Tetramethyl-9-(4-chloro-phenyl)-1,8-dioxo-
octahydroxanthene (3i)
Rf (EtOAc/n-hexane: 1/9) = 0.30; 1H NMR (500 MHz,
CDCl3):
d
(ppm) 1.01 (s, 6H), 1.13 (s, 6H), 2.18 (d,
Rf (EtOAc/n-hexane: 1/9) = 0.35; 1H NMR (500 MHz,
J = 16.3 Hz, 2H), 2.27 (d, J = 16.3 Hz, 2H), 2.53 (t,
J = 18.5 Hz, 4H), 4.85 (s, 1H), 7.41 (t, J = 7.9 Hz, 1H), 7.81
(d, J = 7.5 Hz, 1H), 7.99 (d, J = 8.2 Hz, 1H), 8.06 (s, 1H); 13C
DMSO-d6): d (ppm) 0.90 (s, 6H), 1.04 (s, 6H), 2.09 (d,
J = 16.1 Hz, 2H), 2.27 (d, J = 16.1 Hz, 2H), 2.52 (d, 2H), 2.57
(d, J = 17.6 Hz, 2H), 4.51 (s, 1H), 7.19 (d, J = 8.3 Hz, 2H), 7.29
(d, J = 8.2 Hz, 2H); 13C NMR (125 MHz, DMSO-d6):
d (ppm)
NMR (125 MHz, CDCl3):
d
(ppm) 27.7, 29.6, 32.5, 32.7, 41.2,
51.0, 114,9, 122.0, 123.1, 129.2, 136.0, 146.8, 148.7, 163.5,
196.8.
27.7, 29.7, 31.8, 32.6, 41.3, 51.1, 115.6, 128.6, 130.2, 132.4,
143.1, 162.8, 196.7.
4.11.4. 3,3,6,6-Tetramethyl-9-(4-cyano-phenyl)-1,8-dioxo-
octahydroxanthene (3d)
4.11.10. 3,3,6,6-Tetramethyl-9-(3-chloro-phenyl)-1,8-dioxo-
octahydroxanthene (3j)
Rf (EtOAc/n-hexane: 1/9) = 0.33; 1H NMR (400 MHz,
Rf (EtOAc/n-hexane: 1/9) = 0.20; 1H NMR (500 MHz,
CDCl3):
d
(ppm) 0.99 (s, 6H), 1.13 (s, 6H), 2.17 (d,
CDCl3): d (ppm) 1.02 (s, 6H), 1.12 (s, 6H), 2.18–2.27
J = 16.4 Hz, 2H), 2.26 (d, J = 16.4, 2H), 2.52 (t, J = 15.4 Hz,
4H), 4.78 (s, 1H), 7.43 (d, J = 8.4 Hz, 2H), 7.53 (2H, J = 8.0 Hz,
(Distorted AB system, 4H), 2.52 (t, J = 14.0 Hz, 4H), 4.74 (s,
1H), 7.09 (d, J = 7.6 Hz, 1H), 7.16 (t, J = 7.9 Hz, 2H), 7.25 (s,
1H); 13C NMR (125 MHz, CDCl3):
d (ppm)27.8, 29.6, 32.2,
2H); 13C NMR (100 MHz, CDCl3):
d
(ppm) 27.3, 29.2, 32.2,
32.4, 40.8, 50.6, 110.2, 114.6, 119.1, 129.3, 131.9, 149.5,
162.9, 196.3.
32.6, 41.2, 51.1, 115.5, 127.0, 127.4, 128.8, 129.6, 134.3,
146.6, 163.1, 196.7.
4.11.5. 3,3,6,6-Tetramethyl-9-(4-methoxy-phenyl)-1,8-
dioxo-octahydroxanthene (3e)
4.11.11. 3,3,6,6-Tetramethyl-9-(4-bromo-phenyl)-1,8-
dioxo-octahydroxanthene (3k)
Rf (EtOAc/n-hexane: 1/9) = 0.40; 1H NMR (400 MHz,
Rf (EtOAc/n-hexane: 1/9) = 0.35; 1H NMR (500 MHz,
CDCl3):
d
(ppm) 1.01 (s, 6H), 1.12 (s, 6H), 2.18 (d,
DMSO-d6): d (ppm) 0.91 (s, 6H), 1.04 (s, 6H), 2.07 (d,
J = 16.4 Hz, 2H), 2.25 (d, J = 16.4 Hz, 2H), 2.48 (s, 4H),
3.75 (s, 3H), 4.72 (s, 1H), 6.77 (d, J = 8.8 Hz, 2H), 7.22 (d,
J = 16.1 Hz, 2H), 2.25 (d, J = 16.1 Hz, 2H), 2.50–2.59 (Dis-
torted AB system, 4H), 4.49 (s, 1H), 7.13 (d, J = 8.4 Hz, 2H),
7.42 (d, J = 8.4 Hz, 2H).
J = 8.8 Hz, 2H); 13C NMR (100 MHz, CDCl3):
d (ppm) 27.3,
29.3, 30.9, 32.2, 40.9, 50.8, 55.1, 113.5, 115.8, 129.3, 136.5,
157.9, 162.1, 196.5.
4.11.12. 3,3,6,6-Tetramethyl-9-(2-phenyl-ethylene)-1,8-
dioxo-octahydroxanthene (3l)
4.11.6. 3,3,6,6-Tetramethyl-9-(3,4-dimethoxy-phenyl)-1,8-
dioxo-octahydroxanthene (3f)
Rf (EtOAc/n-hexane: 1/9) = 0.37; 1H NMR (500 MHz,
DMSO-d6):
d (ppm) 1.04 (s, 6H), 1.06 (s, 6H), 2.25 (d,
Rf (EtOAc/n-hexane: 1/9) = 0.31; 1H NMR (500 MHz,
J = 16.04 Hz, 2H), 2.31 (d, J = 16.02 Hz, 2H), 2.52 (s, 4H), 4.15
(d, J = 5.29 Hz, 1H), 6.19 (d, J = 16.05 Hz, 1H), 6.21 (dd, 1H),
7.19 (m, 1H), 7.27 (d, J = 3.7 Hz, 4H); 13C NMR (125 MHz,
DMSO-d6):
d (ppm) 0.92 (s, 6H), 1.04 (s, 6H), 2.10 (d,
J = 16.1 Hz, 2H), 2.27 (d, J = 16.1 Hz, 2H), 2.51 (d, J = 17.6 Hz,
2H), 2.57 (d, J = 17.4 Hz, 2H), 3.68 (s, 6H), 4.48 (s, 1H), 6.67
(dd, J = 8.3, 1.9 Hz, 1H), 6.72 (d, J = 1.9 Hz, 1H), 6.80 (d,
DMSO-d6):
d (ppm) 27.7, 28.3, 29.4, 32.8, 50.9, 114.1,
126.8, 128.2, 129.4, 130.4, 132.2, 137.5, 164.4, 197.1.
J = 8.31 Hz, 1H); 13C NMR (125 MHz, DMSO-d6):
d (ppm)
Acknowledgements
27.2, 29.6, 31.4, 32.7, 50.9, 56.3, 56.3, 112.2, 112.9, 115.4,
120.9, 137.7, 148.1, 148.9, 163.6, 196.9.
The authors gratefully acknowledge partial support of
this work by the Research Affairs Office of Bu-Ali Sina
University (Grant number 32-1716 entitled development
of chemical methods, reagents and molecules), and Center
of Excellence in Development of Chemical Method
(CEDCM), Hamedan, I.R. Iran.
4.11.7. 3,3,6,6-Tetramethyl-9-(4-methyl-phenyl)-1,8-dioxo-
octahydroxanthene (3g)
Rf (EtOAc/n-hexane: 1/9) = 0.33; 1H NMR (500 MHz,
CDCl3):
d (ppm) 1.02 (s, 6H), 1.25 (s, 6H), 2.17–2.27 (m,
7H), 2.49 (s, 4H), 4.74 (s, 1H), 7.04 (d, J = 7.5 Hz, 2H), 7.20 (d,

736
M.A. Zolfigol et al. / C. R. Chimie 15 (2012) 719–736
[26] P.S. Kumar, B.S. Kumar, B. Rajitha, P.N. Reddy, N. Sreenivasulu, Y.T.
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