New basic ionic liquid from ethan-1,2-diyl bis (hydrogen sulfate) and DBU (1,8-diazobicyclo[5.4.0]undec-7-ene) as an efficient catalyst for one-pot synthesis of xanthene derivatives

Article abstract of DOI:10.1016/j.dyepig.2015.08.009

For the first time a new basic ionic liquid from ethan-1,2-diyl-bis (hydrogen sulfate) and 1,8-diazobicyclo[5.4.0]undec-7-ene was suggested. The catalytic activity of the new ionic liquid was tested for synthesis of xanthene derivatives by condensation of aldehydes with i) dimedone ii) β-naphthol iii) 2-hydroxynaphthalene-1,4-dione iv) dimedone and β-naphthol v) 2-hydroxynaphthalene-1,4-dione and dimedone vi) β-naphthol and 2-hydroxynaphthalene-1,4-dione. This approach is a clean, environmentally friendly and convenient work up protocol. The new ionic liquid is an effective and inexpensive catalyst that could easily be recycled and reused five times without significant loss of catalytic activity.

Full text of DOI:10.1016/j.dyepig.2015.08.009

Accepted Manuscript
New basic ionic liquid from ethan-1,2-diyl bis (hydrogen sulfate) and DBU (1,8-
diazobicyclo[5.4.0]undec-7-ene) as an efficient catalyst for one-pot synthesis of
xanthene derivatives
Behrooz Maleki, Elahe Akbarzadeh, Saeed Babaee
PII:
S0143-7208(15)00318-6
10.1016/j.dyepig.2015.08.009
DYPI 4890
DOI:
Reference:
To appear in: Dyes and Pigments
Received Date: 2 July 2015
Revised Date: 3 August 2015
Accepted Date: 5 August 2015
Please cite this article as: Maleki B, Akbarzadeh E, Babaee S, New basic ionic liquid from ethan-1,2-diyl
bis (hydrogen sulfate) and DBU (1,8-diazobicyclo[5.4.0]undec-7-ene) as an efficient catalyst for one-pot
synthesis of xanthene derivatives, Dyes and Pigments (2015), doi: 10.1016/j.dyepig.2015.08.009.
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ACCEPTED MANUSCRIPT
New basic ionic liquid from ethan-1,2-diyl bis (hydrogen sulfate)
and DBU (1,8-diazobicyclo[5.4.0]undec-7-ene) as an efficient
catalyst for one-pot synthesis of xanthene derivatives
Behrooz Maleki,*a Elahe Akbarzadeh,b Saeed Babaeea
aDepartment of Chemistry, Hakim Sabzevari University, Sabzevar 96179-76487, Iran
*Corresponding author; Tel: +985144013324; Fax: +9844010300
*E mail: b.maleki@hsu.ac.ir
bYoung Researchers and Elite Club, Islamshahr Branch, Islamic Azad University,
Islamshahr, Iran
Graphical Abstract:
1

ACCEPTED MANUSCRIPT
New basic ionic liquid from ethan-1,2-diyl bis (hydrogen sulfate)
and DBU (1,8-diazobicyclo[5.4.0]undec-7-ene) as an efficient
catalyst for one-pot synthesis of xanthene derivatives
Behrooz Maleki,*a Elahe Akbarzadeh,b Saeed Babaeea
aDepartment of Chemistry, Hakim Sabzevari University, Sabzevar 96179-76487, Iran
*Corresponding author; Tel: +985144013324; Fax: +9844010300
*E mail: b.maleki@hsu.ac.ir
bYoung Researchers and Elite Club, Islamshahr Branch, Islamic Azad University,
Islamshahr, Iran
Abstract:
For the first time a new basic ionic liquid from ethan-1,2-diyl-bis (hydrogen sulfate) and 1,8-
diazobicyclo[5.4.0]undec-7-ene was suggested. The catalytic activity of the new ionic liquid
was tested for synthesis of xanthene derivatives by condensation of aldehydes with i)
dimedone ii) β-naphthol iii) 2-hydroxynaphthalene-1,4-dione iv) dimedone and β-naphthol v)
2-hydroxynaphthalene-1,4-dione and dimedone vi) β-naphthol and 2-hydroxynaphthalene-
1,4-dione. This approach is a clean, environmentally friendly and convenient work up
protocol. The new ionic liquid is an effective and inexpensive catalyst that could easily be
recycled and reused five times without significant loss of catalytic activity.
Keywords:
β-Naphthol,
Aldehydes,
Bis-2,3,4,6,7,8,9,10-octahydropyrimido[1,2-
a]azepinnium-ethyl disulfate [DBU]2[EDS], Dimedone; 2-hydroxynaphtalene-1,4-dione,
DBU-based ionic liquid
2

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1. Introduction
Multi component reactions (MCRs) are of considerable importance in organic and
medicinal chemistry because they have been proved to be remarkably successful in
generating molecular complexity in a single synthetic operation [1]. However, great efforts
have been and still are being made to find and develop new MCRs.
In recent years, green chemistry has become a major driving force for organic chemists to
develop environmentally benign routes to a myriad of materials. Hence, ionic liquids have
received recognition as green media in organic synthesis due to their favorable properties,
such as negligible vapor pressure, tunable polarity, wide liquid range, good solvating
capability, high thermal stability, and case of recyclability [2].
Xanthenes and their derivatives are of considerable interest as they possess a wide range
of biological and pharmaceutical properties such as anti-inflammatory [3], activities as well
as efficacy in photo dynamic therapy, antiviral, antibacterial, and antagonists for the
paralyzing action of zoxazolamine [4]. In addition, they can be used as dyes, pH-sensitive
fluorescent material for visualization of bio molecules and utilized in laser technologies [5].
A number of synthetic methods for the synthesis of these compounds have been
developed during the past decades [6]. The most commonly used methods involves the
condensation of aldehydes with i) dimedone ii) β-naphthol iii) 2-hydroxynaphthalene-1,4-
dione iv) dimedone and β-naphthol v) 2-hydroxynaphthalene-1,4-dione and dimedone vi) β-
naphthol and 2-hydroxynaphthalene-1,4-dione in the presence of a catalyst [7]. However,
these methodologies suffer from one or more disadvantages, such as low yields, tedious
workup, strong corrosive and harmful acids, prolonged reaction time, toxic organic solvents,
need for excess of the reagents/catalyst, and non-reusability of the catalysts. Therefore, the
development of mild, green, inexpensive, non toxic and facile methods for the synthesis of
xanthenes derivatives is a necessary part of organic chemistry.
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2. Experimental section
2.1. General
Chemicals were obtained from Merck and Sigma-Aldrich. IR spectra were recorded on a
Shimadzu 435-U-04 spectrophotometer (KBr pellets). 1H NMR spectra were obtained using a
Jeol FT NMR 300 MHz spectrometer in CDCl3 or D2O using TMS as an internal reference.
Melting points were determined in open capillary tubes in a Stuart BI Branstead
Electrothermal Cat No: IA92003 apparatus and were uncorrected.
2.1. Preparation of ionic liquid
2.1.1. Ethan-1,2-diyl bis (hydrogen sulfate)
To 12.4g ethylene glycol (0.2 mol), 46.6g chlorosulfonic acid (0.4 mol) was added drop
wise with good cooling (0 to 5oC). After drying in vacuum for 20 min, 43 g (97%) of product
1
were isolated as a pure oily liquid. H NMR (300 MHz, D2O): δ = 3.71 (s, 4H) ppm; Ana.
Calcd (%) for C2H6O8S2 (222.19): C, 10.81; H, 2.72; S, 28.86; found: C, 10.62; H, 2.71; S,
28.56.
2.1.2. Bis-2,3,4,6,7,8,9,10-octahydropyrimido[1,2-a]azepinium-ethyl disulfate [DBU]2[EDS]
DBU (1,8-diazobicyclo[5.4.0]undec-7-ene) (10.2g, 0.1 mol) in dichloromethane (10 mL)
was added during 10 min to a rapidly stirred solution of ethan-1,2-diyl bis (hydrogen sulfate)
(11.1 g, 0.05 mol) in dichloromethane (20 mL) that was cooled in ice bath. Stirring was
continued for 15 min, upper layer was separated. After drying in vacuum for 60 min at 70oC,
15.8 g (98%) was obtained as an oily product. The synthesized ionic liquid was characterized
by different methods such as IR, 1H and 13C-NMR spectrometer. 1H NMR (300 MHz, D2O) δ
1.33-1.37 (m, 6H), 1.65 (t, J=5.8 Hz, 2H), 2.26-2.29 (m, 2H), 2.97 (t, J=5.7 Hz, 2H), 3.15-
13
3.23 (m, 4H), 3.30 (s, 2H) ppm; C NMR (75 MHz, D2O): δ 18.2, 22.6, 25.2, 27.7, 32.1,
37.3, 47.5, 53.4, 61.9, 165.2 ppm; IR (KBr disk): 3450-3100, 2980, 1620, 1300, 1170, 1000,
1050, 890, 590 cm-1.
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2.2. General Procedure for Synthesis of 9-Aryl-1,8-dioxo-octhydroxanthenes
A mixture of cyclic 1,3-dicarbonyl (2 mmol), aldehydes (1 mmol), and [DBU]2[EDS] (40
mol%) was stirred at 120oC in oil bath for the time show in Table 2. Upon completion of the
reaction as indicated by TLC (hexane:ethyl acetate, 8:2), hot EtOH (96%, 1 ml) was added to
the mixture which was stirred for 2 min. Then the reaction mixture was poured onto crushed
ice and the precipitated solid was collected and recrystallized from ethanol (96%, 3 ml) to
afford the pure 9-aryl-1,8-dioxo-octhydroxanthenes derivatives (2). Under the same
conditions, this approach can be repeated for synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes,
12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthene-1,6,10-ones,
14-aryl-14H-
dibenzo[a,i]xanthenes-8,13-ones, 13-aryl-5H-dibenzo[b,i]xanthenes-5,7,12,14(13H)-tetraones
and 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthene-11-ones.
3. Results and discussions
Due to the reasonable needs to clean and green recoverable homogenous catalyst, we
synthesized
bis-2,3,4,6,7,8,9,10-octahydropyrimido[1,2-a]azepinium-ethyl
disulfate
[DBU]2[EDS] as a new basic ionic liquid from Ethan-1,2-diyl bis (hydrogen sulfate) and
DBU. Firstly, Ethan-1,2-diyl bis (hydrogen sulfate) was prepared by the reaction of ethylene
glycol with chlorosulfonic acid in dichloromethane. Finally, the reaction of Ethan-1,2-diyl bis
(hydrogen sulfate) with DBU at 0oC gave bis-2,3,4,6,7,8,9,10-octahydropyrimido[1,2-
a]azepinium-ethyl disulfate [DBU]2[EDS] (Scheme 1).
Scheme 1.
Based on our research interests [8], herein we report an efficient synthesis of 9-aryl-1,8-
dioxo-octhydroxanthenes,
14-aryl-14H-dibenzo[a,j]xanthenes,
13-aryl-5H-
dibenzo[b,i]xanthenes-5,7,12,14(13H)-tetraones,
12-aryl-8,9,10,12-
tetrahydrobenzo[a]xanthene-11-ones, 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthene-1,6,10-
5

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ones and 14-aryl-14H-dibenzo[a,i]xanthenes-8,13-ones in the presence [DBU]2[EDS] under
solvent-free conditions at 120oC (Scheme 2).
Scheme 2.
The most suitable reaction conditions for the proposed reaction were achieved by
investigating the model reaction of aldehyde (1 mmol), dimedone (2 mmol), and
[DBU]2[EDS] (40 mol %). The best result was obtained when the reaction was carried at
120oC in the absence of any solvent. As shown in Table 1, increasing temperature up to
120oC can result in improving the yields (entries 1-3). And, decreasing in yield at 130oC
(entry 4), may be related to decomposition of respective IL. By comparing entries 3 and 5-7
at 120oC in Table 1, we recognized that the 40 mol % of IL was optimum amount for this
reaction. Using [EDS] as a catalyst in the reaction caused low yields (entry 8) and in absence
of any IL, no reaction occurred (entry 10). Also, when DBU was used as catalyst, 2,2'-
arylmethylene bis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) was the major product.
Table 1 Optimization of reaction conditions for the synthesis of 9-phenyl-1,8-dioxo-octhydroxanthene
Entry
Catalyst
Conditions
Time (min)
Yielda (%)
1
2
3
4
5
6
7
[DBU]2[EDS](40 mol %)
[DBU]2[EDS] (40 mol %)
[DBU]2[EDS] (40 mol %)
[DBU]2[EDS] (40 mol %)
[DBU]2[EDS] (50 mol %)
[DBU]2[EDS] (30 mol %)
[DBU]2[EDS] (20 mol %)
Solvent-Free/1000C
Solvent-Free/1100C
Solvent-Free/1200C
Solvent-Free/1300C
Solvent-Free/1200C
Solvent-Free/1200C
Solvent-Free/1200C
10
10
5
80
85
92
90
89
86
82
5
5
10
15
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8
9
[EDS] (40 mol %)
Solvent-Free/1200C
Solvent-Free/1200C
Solvent-Free/1200C
10
10
10
60
64b
-
[DBU] (40 mol %)
-
10
aIsolated yields.b2,2'-arylmethylene bis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) was major product.
Subsequently, reactions of variously substituted aromatic aldehydes with 2 equivalent of
dimedone (A) were carried out under the most suitable reaction condition (Table 2, entries 1-
10). In all cases studied, the reaction proceeded smoothly to give the corresponding 9-aryl-
1,8-dioxo-octhydroxanthene derivatives in satisfactory yields. Most importantly, aromatic
aldehydes with substituents bearing electron-donating or electron-withdrawing groups reacted
successfully in the presence of [DBU]2[EDS] as catalyst.
The protocol was further extended by exploring with 2 equivalent of β-naphthol (B) and
aromatic aldehydes (entries 11-15). As shown in Table 2, aldehydes with electron-
withdrawing groups disappeared faster by producing high yield products in short time.
Similarly, reaction of 2 equivalent of 2-hydroxynaphthalene-1,4-dione (C) and different
substituted aromatic aldehydes under the above optimized reaction condition proceeded
smoothly to afford the corresponding 13-aryl-5H-dibenzo[b,i]xanthenes-5,7,12,14(13H)-
tetraones (entries 16-20).
The scope of this reaction was extended by replacing one equivalent of β-naphthol (B)
with dimedone (A). It was also observed that in the presence of IL (40 mol%) high yields of
12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthene-11-ones were resulted (entries 21-25).
In continuation, by using dimedone (A) and 2-hydroxynaphthalene-1,4-dione (C) with
aromatic aldehydes, corresponding 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthene-1,6,10-
ones obtained within 5-9 minutes with high yields (entries 26-29). And finally, we completed
our study using one equivalent of β-naphthol (B), 2-hydroxynaphthalene-1,4-dione (C) and
aromatic aldehydes (entries 30-33).
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Table 2 Preparation of various xanthenes derivatives using [DBU]2[EDS] as a basic ionic liquid
o
Entry
1
Products
Time (min)
Yielda (%)
Mp ( C)
Found
Reported
5
92
198-200 203–205 [7g]
O
O
CH3
CH3
H3C
O
CH3
2a
OCH3
2
4
92
242-243 242–245 [7g]
O
O
CH3
CH3
H3C
CH3
O
2b
NO2
O
3
4
95
167-170 170–172 [7g]
O
CH3
CH3
H3C
CH3
O
2c
Cl
4
4
92
231-233 230–233 [7g]
O
O
CH3
CH3
H3C
O
CH3
2d
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OCH3
5
5
92
182-184 179–182 [7g]
OCH3
O
O
CH3
CH3
H3C
CH3
O
2e
CH3
6
10
90
216-218 212–214 [7g]
O
O
CH3
CH3
H3C
CH3
O
2f
CH(CH3)2
7
12
90
235-238 236–239 [7r]
O
O
CH3
CH3
H3C
CH3
O
2g
NO2
O
8
5
90
280-282 277-279 [7o]
O
O
2h
9
10
88
201-203 203-205 [7o]
O
O
O
2i
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CH3
10
15
86
216-218 218-220 [7o]
O
O
O
2j
11
7
93
188-190 183-185 [7o]
O
3a
NO2
12
6
95
213-215 212-213 [7o]
O
3b
OCH3
13
6
94
200-201 202–203 [7o]
O
3c
Cl
14
5
92
294-296
290-292 [7o]
O
3d
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CH(CH3)2
15
10
88
150-152 153–155 [7s]
O
3e
OCH3
16
8
92
≥300
≥300 [7l]
O
O
O
O
O
4a
NO2
O
17
8
94
≥300
≥300 [7l]
O
O
O
O
4b
Cl
18
10
86
≥300
≥300 [7l]
O
O
O
O
O
4c
Br
19
10
92
≥300
≥300 [7l]
O
O
O
O
O
4d
11

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20
10
90
≥300
305–307 [7a]
O
O
O
O
O
4e
21
6
90
148-150 148–151 [7b]
O
CH3
CH3
O
5a
Cl
22
5
94
177-180 178–179 [7b]
O
CH3
CH3
O
5b
CH(CH3)2
23
15
90
153-155 150–152 [7q]
O
CH3
CH3
O
5c
NO2
24
5
92
170-171 167–170 [7b]
O
CH3
CH3
O
5d
12

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OCH3
25
8
91
202-204
204-206 [7b]
O
CH3
CH3
O
5e
26
5
90
260-264 263–265 [7m]
O
O
O
O
O
CH3
CH3
O
6a
OCH3
27
6
95
245-247 245–248 [7m]
O
O
CH3
CH3
O
6b
Cl
28
9
96
280-283 282–284 [7m]
O
O
CH3
CH3
O
6c
NO2
29
7
92
263-265 265–268 [7m]
O
O
O
CH3
CH3
O
6d
13

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30
8
90
293-295 294–297 [7m]
O
O
O
7a
Cl
31
7
92
280-283 281–284 [7m]
O
O
O
7b
OCH3
32
6
95
280-281 279–280 [7m]
O
O
O
7c
NO2
33
10
96
≥300
304-305 [7m]
O
O
O
7d
aIsolated yields.
We have illustrated the plausible mechanism for reaction of dimedone and aldehyde in
presence of IL in Scheme 3. The reaction proceeds through hydrogen bondings of carbonyl
groups in aldehyde and dimedone with the respective bifunctional IL (form (a) in Fig.1). As
we used basic IL, dimedone can be more stable in enolate state (form (b)). In addition, IL
14

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structure may exist in form (c) due to resonating of lone pair electrons of the bridged nitrogen
on DBU. Therefore, applied IL can activate reaction via three routes: (i) by approaching
aldehyde and dimedone to initiate reaction, (ii) by converting dimedone to enolate form
which is more prone to react with aldehyde, and (iii) by hydrogen bonding which makes
carbonyl group of aldehyde more susceptible to dimedone nucleophilic addition.
Fig. 1.
Scheme 3.
As shown in Scheme 3, addition of dimedone (A) to corresponding aldehyde produce 2-
hydroxy ketone compound which followed by dehydration at 120oC. Then, the second
dimedone in enolate form approaches to this adduct with assistance of IL and addition occurs.
In presence of basic IL, hydrogen at alpha position of carbonyl, in resulted adduct, removed
and reaction accompanied with cyclization. Finally, the process continues by second water
elimination at the reported reaction temperature (120oC) to produce 9-aryl-1,8-dioxo-
octhydroxanthenes derivatives and releases IL. So, the IL can be recycle and utilize in the
next reaction.
However, mechanism for β-naphthol (B) or 2-hydroxynaphthalene-1,4-dione (C) with
aldehyde is generally similar to the mentioned process. The only difference is that here
hydrogen of alcoholic group is removed in basic DBU-based IL to start the reaction.
The reusability of the [DBU]2[EDS] was also determined. After each run, water was
added to the reaction mixture and the product was filtered and the containing ionic liquid was
extracted with CH2Cl2 (5 ml) to remove non-ionic organic impurities. Then the water was
evaporated and the catalyst was dried at 70oC under reduced pressure for 2 h and reused in
15

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next reactions under solvent-free conditions at 120oC. It could be observed that this IL easily
recycled for five times and reused in next reaction (Fig. 2).
Fig. 2.
4. Conclusions
In conclusion, by using a new efficient DBU-based ionic liquid as a bifunctional catalyst
in a solvent-free environment, we accomplished some useful xanthenes, which would be
helpful for dye applications. Operational simplicity, easy work up, short reaction times, and
inexpensive, non-toxic and recyclable medium/catalyst, are additional advantages of this
protocol.
Acknowledgements
The author thanks the Research Council of Hakim Sabzevari University for partial
support of this work.
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one-pot, three-component synthesis of tetrahydrobenzo[α]xanthene-11-ones. J Mol
Catal A: Chem 2014;393:309-16.
(c) Napoleon AA, Nawaz Khan, FR, Jeong ED, Chung EH. Regioselective synthesis
of 3,4,6,7-tetrahydro-3,3-dimethyl-9-phenyl-2H-xanthene-1,8(5H,9H)-diones through
ascorbic acid catalyzed three-component domino reaction. Tetrahedron Lett
2014;55:5656-9.
(d) Naeimi H, Nazifi ZS. Environmentally benign and one-pot synthesis of 14-aryl-
14H-dibenzo[a,j]xanthenes catalyzed by acyclic Brønsted acidic ionic liquid [H-
NMP][HSO4] under green conditions. CR Chim 2014;17:41-8.
18

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(e) Mokhtary M, Refahati S. Polyvinyl polypyrrolidone-supported boron trifluoride
(PVPP-BF3): Mild and efficient catalyst for the synthesis of 14-aryl-14H-dibenzo [a,j]
xanthenes and bis(naphthalen-2-yl-sulfane) derivatives. Dyes Pigm 2013;99:378-81.
(f) Shirini F, Abedini M, Pourhasan R. N-sulfonic acid poly(4-vinylpyridinium)
chloride: A novel polymeric and reusable catalyst for the preparation of xanthenes
derivatives. Dyes Pigm 2013;99:250-5.
(g) Ilangovan A, Muralidharan S, Sakthivel P, Malayappasamy S, Karuppusamy S,
Kaushik MP. Simple and cost effective acid catalysts for efficient synthesis of 9-aryl-
1,8-dioxooctahydroxanthene. Tetrahedron Lett 2013;54:491-4.
(h) Noroozi Tisseh Z, Azimi SC, Mirzaei P, Bazgir A. The efficient synthesis of aryl-
5H-dibenzo[b,i]xanthene-5,7,12,14(13H)-tetraone leuco-dye derivatives. Dyes Pigm
2008;79:273-5.
(i) Zarei A, Hajipour AR, Khazdooz L. The one-pot synthesis of 14-aryl or alkyl-14H-
dibenzo[a,j]xanthenes catalyzed by P2O5/Al2O3 under microwave irradiation. Dyes
Pigm 2010;85:133-8.
(j) Shaterian HR, Ghashang M, Hassankhani A. One-pot synthesis of aryl 14H-
dibenzo[a,j]xanthene leuco-dye derivatives. Dyes Pigm 2008;76:564-568.
(k) Wu LQ, Wu YF, Yang CG, Yang LM, Yang LJ. Silica supported perchloric acid:
an sufficient catalyst for the synthesis of 14-aryl-14H-dibenzo[a,i]xanthene-8,13-
diones. J Braz Chem Soc 2010;221:941-5.
(l) Chen Y, Wu S, Tu S, Li C, Shi F. A simple procedure for the synthesis of
benzoxanthene derivatives under microwave irradiation conditions. J Het Chem
2008;45:931-4.
19

ACCEPTED MANUSCRIPT
(m) Rahmatpour A. Polystyrene-supported GaCl3 as a highly efficient and reusable
heterogeneous Lewis acid catalyst for the three-component synthesis of
benzoxanthene derivatives. Monatsh Chem 2013;144:1205–12.
(n) Shaterian HR, Azizi K. Brønsted acidic ionic liquids catalyzed one-pot synthesis
of benzoxanthene leuco-dye derivatives. Res Chem Intermed 2015;41:409-17.
(o) Maleki B, Gholizadeh M, Sepehr Z. 1,3,5-Trichloro-2,4,6-triazinetrion: a versatile
heterocycle for the one-pot synthesis of 14-aryl- or alkyl -14H-dibenzo[a,j]xanthene,
1,8-dioxooctahydroxanthene and 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthene-11-
one derivatives under solvent-free conditions. Bull Korean Chem Soc 2011;32:1697-
1702.
(p) Tayebee R, Maleki B. Assembling of H5PW10V2O40/MCM-48 and studying its
superior catalytic performance in the synthesis of 14-aryl-14-H-dibenzo[a,
j]xanthenes. J Chem Sci 2013;125:335-44.
(q) Shirini F, Ghaffari Khaligh N. Succinimide-N-sulfonic acid: an efficient catalyst
for the synthesis of xanthenes derivatives under solvent-free conditions. Dyes Pigm
2012;95:789-94.
(r) Karami B, Zare Z, Eskandari K. Molybdate sulfonic acid: preparation,
characterization, and application as an effective and reusable catalyst for
octahydroxanthene-1,8-dione synthesis. Chem Paper 2013;67:145-54.
(s) Shirini F, Yahyazadeh A, Mohammadi K. One-pot synthesis of various xanthene
derivatives using ionic liquid 1,3-disulfonic acid imidazolium hydrogen sulfate as an
efficient and reusable catalyst under solvent-free conditions. Chin Chem Lett
2014;25:341-7.
20

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8. (a) Veisi H, Maleki B, Hamelian M, Sedigh Ashrafi S. Chemoselective hydration of
nitriles to amides by hydrated ionic liquid (IL) tetrabutylammonium hydroxide
(TBAH) as a green catalyst. RSC Adv 2015;5:6365-71.
(b) Maleki B, Rezaee-Seresht E, Ebrahimi, Z. Friedlander synthesis of quinolines
promoted by polymer-bound sulfonic acid. Org Prep Proced Int 2015;47:149-60.
(c) Maleki B. Solvent-free synthesis of 2,4,6-triarylpyridine derivatives promoted by
1,3-dibromo-5,5-dimethylhydantoin. Org Prep Proced Int 2015; 47: 173-8.
(d) Maleki B, Taimazi F. One-pot synthesis of 1-amidoalkyl-2-naphthols under
solvent-free conditions. Org Prep Proced Int 2014;46:252-60.
(e) Maleki B, Hemmati S, Sedrpoushan A, Sedigh Ashrafi S. Selective synthesis of
sulfoxides and sulfones from sulfides by silica bromide as heterogeneous promoter
and hydrogen peroxide as the terminal oxidant. RSC Adv 2014;4:40505-10.
(f) Maleki B, Sedigh Ashrafi S. Nano α-Al2O3 supported ammonium dihydrogen
phosphate (NH4H2PO4/Al2O3): preparation, characterization and its application as a
novel
and
heterogeneous
catalyst
for
the
one-pot
synthesis
of
tetrahydrobenzo[b]pyran and pyrano[2,3-c] pyrazole derivatives. RSC Adv
2014;4:42873-91.
(g) Maleki B, Sedigh Ashrafi S, Tayebee R. Lewis acid free synthesis of 3,4-dihydro-
1H-indazolo[1,2-b]phthalazine-1,6,11(2H,13H)-triones promoted by 1,1,1,3,3,3-
hexafluoro-2-propanol, RSC Adv 2014;4:41521-8
(h) Tayebee R, Jarrahi M, Maleki B, Kargar Razi M, Mokhtari ZB, Baghbanian SM.
A new method for the preparation of 1,3,5-triarylbenzenes catalyzed by
nanoclinoptilolite/HDTMA, RSC Adv 2015;5:10869-77.
(i) Tayebee R, Jomei M, Maleki B, Kargar Razi M, Veisi H, Bakherad M. A new
natural based ionic liquid 3-sulfonic acid 1-imidazolopyridinium hydrogen sulfate as
21

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an efficient catalyst for the preparation of 2H-indazolo[2,1-b]phthalazine-
1,6,11(13H)-triones. J Mol Liq 2015;206:119-28.
(j) Maleki B, Barat Nam Chalaki S, Sedigh Ashrafi S, Rezaee Seresht E, Moeinpour
F, Khojastehnezhad A, Tayebee R. Caesium carbonate supported on hydroxyapatite
encapsulated Ni0.5Zn0.5Fe2O4 nanocrystallites as a novel magnetically basic catalyst
for the one-pot synthesis of pyrazolo[1,2-b]phthalazine-5,10-diones. Appl Organomet
Chem 2015;4:290-5.
(k) Maleki B, Babaee S, Tayebee R. Zn(L-proline)2 as a powerful and reusable
organometallic catalyst for the very fast synthesis of 2-amino-4H-benzo[g]chromene
derivatives under solvent-free conditions. Appl Organomet Chem 2015;4:408-11.
(l) Maleki B, Sheikh S. RSC Adv 2105; 5:42997-3005.
(m) Veisi H, Naeimi AR, Maleki B, Sedigh Ashrafi S, Sedrpoushan AR. Synthesis of
5-alkylidene-2,4-thiazolidinediones
and
rhodanines
promoted
by
propylaminofunctionalized nano-structured SBA-15. Org Prep Proced Int
2015;47:309-15.
22

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Captions for Tables
Table 1 Optimization of reaction conditions for the synthesis of 9-phenyl-1,8-dioxo-octhydroxanthene
Table 2 Preparation of various xanthenes derivatives using [DBU]2[EDS] as a basic ionic liquid

ACCEPTED MANUSCRIPT
Table 1 Optimization of reaction conditions for the synthesis of 9-phenyl-1,8-dioxo-octhydroxanthene
Entry
Catalyst
Conditions
Time (min)
Yielda (%)
1
2
[DBU]2[EDS](40 mol %)
[DBU]2[EDS] (40 mol %)
[DBU]2[EDS] (40 mol %)
[DBU]2[EDS] (40 mol %)
[DBU]2[EDS] (50 mol %)
[DBU]2[EDS] (30 mol %)
[DBU]2[EDS] (20 mol %)
[EDS] (40 mol %)
Solvent-Free/1000C
Solvent-Free/1100C
Solvent-Free/1200C
Solvent-Free/1300C
Solvent-Free/1200C
Solvent-Free/1200C
Solvent-Free/1200C
Solvent-Free/1200C
Solvent-Free/1200C
Solvent-Free/1200C
10
10
5
80
85
92
90
89
86
82
60
64b
-
3
4
5
5
5
6
10
15
10
10
10
7
8
9
[DBU] (40 mol %)
10
-
aIsolated yields.b2,2'-arylmethylene bis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) was major product.

ACCEPTED MANUSCRIPT
Table 2 Preparation of various xanthenes derivatives using [DBU]2[EDS] as a basic ionic liquid
o
Entry
1
Products
Time (min)
Yielda (%)
Mp ( C)
Found
Reported
5
92
198-200 203–205 [7g]
O
O
CH3
CH3
H3C
O
CH3
2a
OCH3
2
4
92
242-243 242–245 [7g]
O
O
CH3
CH3
H3C
CH3
O
2b
NO2
O
3
4
95
167-170 170–172 [7g]
O
CH3
CH3
H3C
CH3
O
2c
Cl
4
4
92
231-233 230–233 [7g]
O
O
CH3
CH3
H3C
O
CH3
2d

ACCEPTED MANUSCRIPT
OCH3
5
5
92
182-184 179–182 [7g]
OCH3
O
O
CH3
CH3
H3C
CH3
O
2e
CH3
6
10
90
216-218 212–214 [7g]
O
O
CH3
CH3
H3C
CH3
O
2f
CH(CH3)2
7
12
90
235-238 236–239 [7r]
O
O
CH3
CH3
H3C
CH3
O
2g
NO2
O
8
5
90
280-282 277-279 [7o]
O
O
2h
9
10
88
201-203 203-205 [7o]
O
O
O
2i

ACCEPTED MANUSCRIPT
CH3
10
15
86
216-218 218-220 [7o]
O
O
O
2j
11
7
93
188-190 183-185 [7o]
O
3a
NO2
12
6
95
213-215 212-213 [7o]
O
3b
OCH3
13
6
94
200-201 202–203 [7o]
O
3c
Cl
14
5
92
294-296
290-292 [7o]
O
3d

ACCEPTED MANUSCRIPT
CH(CH3)2
15
10
88
150-152 153–155 [7s]
O
3e
OCH3
16
8
92
≥300
≥300 [7l]
O
O
O
O
O
4a
NO2
O
17
8
94
≥300
≥300 [7l]
O
O
O
O
4b
Cl
18
10
86
≥300
≥300 [7l]
O
O
O
O
O
4c
Br
19
10
92
≥300
≥300 [7l]
O
O
O
O
O
4d

ACCEPTED MANUSCRIPT
20
10
90
≥300
305–307 [7a]
O
O
O
O
O
4e
21
6
90
148-150 148–151 [7b]
O
CH3
CH3
O
5a
Cl
22
5
94
177-180 178–179 [7b]
O
CH3
CH3
O
5b
CH(CH3)2
23
15
90
153-155 150–152 [7q]
O
CH3
CH3
O
5c
NO2
24
5
92
170-171 167–170 [7b]
O
CH3
CH3
O
5d