Nano-Fe3O4 encapsulated-silica particles bearing sulfonic acid groups as an efficient, eco-friendly and magnetically recoverable catalyst for synthesis of various xanthene derivatives under solvent-free conditions Academic research paper on "Chemical sciences"

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Nano-Fe3O4 encapsulated-silica particles bearing sulfonic acid groups as an efficient, eco-friendly and magnetically recoverable catalyst for synthesis of various xanthene derivatives under solvent-free conditions

Journal of Saudi Chemical Society

PII: DOI:

Reference:

Firouzeh Nemati, Samane Sabaqian

S1319-6103(14)00065-9 http://dx.doi.org/10.1016/joscs.2014.04.009 JSCS 655

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Journal of Saudi Chemical Society

Received Date: 7 December 2013

Revised Date: 17 April 2014

Accepted Date: 26 April 2014

Please cite this article as: F. Nemati, S. Sabaqian, Nano-Fe3O4 encapsulated-silica particles bearing sulfonic acid groups as an efficient, eco-friendly and magnetically recoverable catalyst for synthesis of various xanthene derivatives under solvent-free conditions, Journal of Saudi Chemical Society (2014), doi: http://dx.doi.org/10.1016/ j.jscs.2014.04.009

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Title page

Nano-Fe3O4 encapsulated-silica particles bearing sulfonic acid groups as an efficient, eco-friendly and magnetically recoverable catalyst for synthesis of

various xanthene derivatives under solvent-free conditions

Firouzeh Nemati, Samane Sabaqian

-19111, Iran . ac. ir

Department of Chemistry, Semnan University, Semnan 35131 E-mail: fnemati 1350@yahoo.com; fnemati@se, Tel: +98 09122057819, Fax: +98 (231) 3354

Keywords: Magnetic nanoparticle; 1,8-dioxo-octahydroxanthene, 14H-dibenzo[a,j] xanthenes; 12-aryl-tetrahydrobenzo[a]xanthenes-11-one; 13-aryl-5H-dibenzo[b,i]xanthene-5,7,12,14(13H)-tetraone; 2-Hydroxynaphthalene- 1,4-dione.

31) 3354

ahydroxanthe ne; 13-aryl-5H-

Nano-Fe3O4 encapsulated-silica particles bearing sulfonic acid groups as an efficient, eco-friendly and magnetically recoverable catalyst for synthesis of various xanthene derivatives under solvent-free conditions

Firouzeh Nemati*, Samane Sabaqian ^^^

ment of Chemistry, Semnan University, Semnan 35131-19111, ran E-mail: fnemati 1350@yahoo.com; fnemati@semnan. ac. ir

Tel: +98 09122057819, Fax: +98 (231) 3354057

Abstract: This report describes an efficient method for synthesis of 1,8-dioxo-octahydroxanthene, 14H-dibenzo[a,j] xanthene, 12-aryl-tetrahydrobenzo[a]xanthenes-11-one and 13-aryl-5H-dibenzo[b,i]xanthene-5,7,12,14(13H)-tetraone derivatives in the presence of a catalytic amount of nano-iron oxide encapsulated silica particles bearing sulfonic acid groups. Results present an efficient, environmentally friendly and magnetically recoverable catalyst under solvent-free conditions at 110-130°C.

Keywords: Magnetic nanoparticle; 1,8-dioxo-octahydroxanthene, 14H-dibenzo[a,j] xanthenes; 12-aryl-tetrahydrobenzo[a]xanthenes-11-one; 13-aryl-5H-dibenzo[b,i]xanthene-5,7,12,14(13H)-tetraone; 2-Hydroxynaphthalene- 1,4-dione. 1. Introduction

Xanthene and benzoxanthene derivatives are important as biologically and pharmacologically active compounds. Research has shown that these properties include antiplasmodial (Zelefack et al., 2009), antiviral (Lambert et al., 1997) and anti-inflammatory activities (Poupelin et al., 1978). Xanthene and benzoxanthene derivatives are also useful in photodynamic therapy (Ion et

al., 1998) and for antagonism of the paralyzing action of zoxazolamine (Saint-Ruf et al., 1975). Furthermore, due to the useful spectroscopic properties of these derivatives they also have application in industries related to the production of dyes and fluorescent materials, particularly for products that require visualization of bio-molecules (Banerjee & Mukherjee, 1981; Menchen

et al., 2003). Other useful applications of these heterocycles are as leucodyes (Menchen et al.,

2003) and in laser technologies (Ahmad et al., 2002).

In according with these useful properties and related applications as above-mentioned, a number of methods have been reported for synthesis of such compounds. For example, 14-aryl-14H-dibenzo[a,j]xanthenes has been synthesized by one-pot multi-component condensation of ß-naphthol (2 eq.) with various aldehydes (1 eq.) (Rivera et al., 2012; Mokhtary & Refahati 2013; Fareghi-Alamdari et al., 2013). The best method for preparation of tetra-hydrobenzo[a]xanthene-11-ones is a one-pot condensation reaction between ß-naphthol, arylaldehydes and dimedone (Sudha & Pasha 2012; Wan et al., 2013), and the most common protocol for the preparation of 1,8-dioxo-octahydroxanthenes involves the reaction of two molecules of dimedone with one molecule of aldehyde (Ilangovan et al,. 2011; Mulakayala et al., 2012; Khaksar & Behzadi 2012; Karami et al., 2013). In addition, the synthesis of 13-aryl-5H-dibenzo[b,i]xanthene-5,7,12,14(13H)-tetraones was reported from the reaction of 2 mmol 2-hydroxynaphthalene-1,4-dione and 1 mmol aldehyde (Tisseh et al., 2008; Shaterian et al., 2011). Many of these reported synthetic methods are limited because they involve only one class of xanthene; accordingly there 1S a cruc.al need to develop a novel catalyst to synthesize the various xanthene derivatives, indicating a strong demand for this research.

The recent trend of green chemistry has contributed to a recent increase in research attention directed toward the synthesis of magnetic nanoparticles and their application in catalysis (Nasir

Baig & Varma 2012; Davarpanah et al., 2013). Properties of nano-sized particles such as high surface area show a remarkable level of catalytic performance. In addition, due to their magnetic properties, the catalyst could be quickly and easily recovered by means of an external magnet (Rafiee & Eavani 2011). However simplicity of the catalyst preparation is very important in terms of practicality and considerations for application.

During the course of our recent research program on the development of new condition for organic transformations (Bigdeli et al., 2007; Bigdeli et al., 2008; Nemati & Kiani 2011; Nemati & Elhampour 2012), recently, sulfonic acid-functionalized silica-coated nano-Fe3O4 particles have been prepared in our laboratory (Nemati et al., 2012). It displayed a high stability and an impressive catalytic activity in synthesis of tetraketones, pyrimido[4,5-b]quinolines and indeno fused pyrido[2,3-d]pyrimidines in water under mild condition (Nemati & Saeedirad 2013). The performance and recyclability behavior of this nano magnetic catalyst in the preparation of various xanthene derivatives under solvent-free condition is reported in this study to extend possibilities for of this new catalyst (Scheme 1).

Scheme 1.

2. Results and discussion

At the outset of our study, to examine the catalytic activity of the catalyst, the reaction of benzaldehyde (1 mmol) with dimedone (2 mmol) was performed under refluxing in various solvents as shown in Table 1. Then, with particular reference to the current importance of green chemistry, this transformation was attempted without the presence of a solvent. Interestingly, as demonstrated by the results shown in Table 1, product yield was increased to 94% under the solvent-free condition. To study the function of SO3H, an experiment was conducted in the presence of Fe3O4@SiO2, and the results showed that the reaction proceeded for a longer period

and produced a lower yield (Table 1, entry 2). However when Fe3O4@SiO2-SO3H was used, the reaction resulted the desired product in high yield (94% yields). In addition, a trace amount of the product was formed in absence of the catalyst. Thus it can be determined that Fe3O4@SiO2-

Screenings of temperature and amounts of catalyst were investigated and are presented (Table 1, entries 8-12). The best results were obtained by using 0.05 g Fe3O4@SiO2-SO3H at 130°C (Table 1, entry 10). No significant improvement in yield was obtained past that point, so 130°C was chosen as the most appropriate reaction temperature for all further studies. Likewise, increasing the amount of catalyst did not lead to any change in yield of 1a.

Hence, performing the reaction without a solvent and in the presence of 0.05 g catalyst at 130°C was the determined as the optimal cond

Using the optimized reaction condition, the scope and limitations of this methodology were evaluated using a variety of aromatic aldehydes. In general, aromatic aldehydes bearing electron-donating or electron-withdrawing functional groups reacted smoothly with dimedone and within a short reaction time to generate the 1,8-dioxo-octahydroxanthene derivatives with good to excellent yields (Table 2, entries 1a-12a). Only using aldehyde with strongly electron-withdrawing group (-NO2) at ortho position afforded the desired product with a moderate yield (entry 4a). Moreover, this reaction also worked well with aliphatic aldehyde, heteroaromatic aldehyde and hindered aldehyde (Table 2, entries 9a, 11a and 12a).

Preparation of 14H-dibenzo[a,j]xanthenes were also examined to further expand the scope of this nano-magnetic catalyst in the synthesis of xanthene derivatives (Scheme 1). The reaction of 2-naphthol (2 mmol) and arylaldehydes 1 mmol) (carrying both electron-donating and electron-

SO3H was essential to obtain the desired product.

Table 1

withdrawing functional groups), in the presence of 0.05g Fe3O4@SiO2-SO3H proceeded efficiently to furnish to the corresponding 14H-dibenzo[a,j]xanthenes derivatives producing high yields, as summarized in Table 2, entries 13b-18b. The reactions were completed in 25-65 min at 130°C under solvent-free conditions.

Subsequently, application of the catalyst was successfully extended on the condensation of

aldehyde with 2-naphthol and dimedone. The obtained results demonstrated efficiency of this method in the synthesis of 12-aryl-tetrahydrobenzo[a]xanthenes-11-ones at 110°C under solventfree conditions (Table 2, entries 19c-23c). Also 13-aryl-5-H-dibenzo[b,j]xanthenes-5,7,12,14(13H)-tetraones were synthesized using Fe3O4@SiO2-SO3H under the same conditions from the reaction of 2-hydroxynaphthalene-1,4-dione with aryl and naphthyl aldehydes, the results of which are given in Table 2, entries 24d-

Table 2

Good reusability of the catalyst is an important aspect of green chemistry so the potential for recovery of Fe3O4@SiO2-SO3H was investigated. After completion of the reaction of benzaldehyde and dimedone, hot ethanol was added to the reaction mixture and the catalyst was recovered simply by application of an external magnet. Then the recovered catalyst was first washed with diethyl ether and then with methanol, and dried at 60°C for 1 h. The recovered catalyst was added to a fresh reaction mixture under the same conditions for five runs with only a slight loss of its catalytic activity (Figure 1). The recoverability and reusability of catalyst was also checked for synthesis of other xanthenes derivatives, the results summarized in Table 3. The results confirm that the Fe3O4@SiO2-SO3H have good stability and recyclable applicability for the synthesis various xanthenes derivatives. As depicted in Table 3, after four runs, a minor

decline contributing ca. 10-15% is observed. The decrease in the activity could be mainly attributed to unavoidable loss of the catalyst during the process of collection and washing.

Table 3

Another test was done to determine the percentage of leaching of the SO3H group; the reaction of benzaldehyde and 2-naphthol was carried out in the presence of the nano-magnetic catalyst for 10 min in the reaction condition, and then at that point the catalyst was removed by an external magnet. The reaction was then allowed to proceed further, but no meaningful progress was observed even after 80 min of heating at 130°C. Thus it can be concluded that no homogeneous catalyst was involved.

Figure 1.

The TEM image of the used catalyst showed that size and shape of the catalyst particles remained almost the same after five runs (Figure 2) (Nemati et al., 2012). Furthermore, the intensity and peak positions between the used and fresh catalyst in the FTIR spectra after the reaction, indicated that structure of the catalyst had remained the same as that of fresh catalyst (Figure 3).

Figure 2. Figure 3.

The XRD pattern of a reused catalyst (Figure 4) exhibits a broad peak at 20=25.5, which is typical for amorphous silica (Chen et al., 2013). Some distinct peaks at 20 values of 30.24, 35.60, 43.24, 53.7, 57.6 and 62.8 assigned to the (2 2 0), (3 1 1), (4 0 0), (4 2 2), (5 1 1) and (4 4 0) planes of Fe3O4 (Sun et al., 2005).

Figure 4.

The rationale sequence of events is depicted in Scheme 2 according to the commonly accepted mechanism for such reactions. Initially the SO3H groups, as acid sites, are active in protonating the carbonyl group of aldehyde. This intermediate is attacked by 2-naphthol, dimedone or 2-hydroxynaphthalene-1,4-dione to form the Knoevenagel products. In the next

step, each of these intermediates is converted to the desired product via Michael type addition

and cyclization with the removal of a molecule of water (Scheme 2).

Scheme 2.

Table 4 compares efficiency of the present method for synthe sis arious xanthenes with results recently reported by other catalysts in the related liter _ E ach of these methods has its

own merits, but some of them often suffer from some troubles such as use of organic solvents (entries 3, 9, 10, 15), long reaction times (entries 7, 8, 9, 10, 14, 15) employ of non-recyclable or expensive catalyst (entries 3, 8, 9, 10, 11). So Fe3O4@SiO2-SO3H acts as a highly effective and economical catalyst in terms of time and yield produced by the reaction.

Table 4

3. Experimental

Chemicals were purchased from the Fluka, Merck and Aldrich chemical companies. Melting

points were determined on Electrothermal 9100 without further corrections. TLC on commercial

aluminum-backed plates of silica gel 60 F254 was used to monitor the progress of reactions.

Infrared spectra were recorded on a Shimadzu 8400s spectrometer with KBr plates. Only

representative absorptions are given. NMR spectra were taken in CDCl3 or DMSO-d6 on a

Bruker Avance3-400 MHz instrument at 20-25 C. Elemental analyses were performed by

Perkin-Elmer CHN analyzer, 2400 series II. The wide-angle X-ray diffraction (XRD)

measurements were performed at room temperature on a PW 1800 diffractometer (Philips) with

graphite monochromatized Cu Ka radiation (X =1.5401 A). The scanning rate was 0.08 °/s over a range of 20 =4-80°. The sizes of MNPs were evaluated using a transmission electron microscope (TEM, 100 kV, Philips-CM 10).

3.1. Preparation of the catalyst

The FeзO4@SiOd-SOзH was prepared in accordance to our earlier report (Nemati et al., 2012).

3.2. General procedure for the synthesis of xanthene derivatives:

In a 25 mL flask, a mixture of aldehyde (1 mmol), desired substrate (according to Scheme 1) and Fe3O4@SiO2-SO3H (0.05 g) was heated in an oil bath at appropriate temperature under solvent-free conditions (Table 1). After completion of the reaction as monitored by TLC, the resulting solid product was cooled, hot ethanol added to it and stirred for 10 min. Then the catalyst was removed magnetically. The remained alcoholic solution was kept overnight to afford the pure product. The removed catalyst was washed exhaustively with diethyl ether and methanol and dried at 60°C for 1 h prior to reuse in subsequent reaction. All the desired products were characterized by comparison of their physical data with those reported compounds. The spectral data of new compounds are given below:

3.3. The spectral data of new products

3.3.1. 9-(3-Ethoxy-4-hydroxyphenyl)-3,4,6,7-tetrahydro-3,3,6,6-tetramethyl-2H-xanthene-1,8 (5H,9H)-dione (Table 2, 10a)

m.p. 193-194 °C, IR (KBr, cm-1 ): Vmax : 3434, 1666, 1623; 1H NMR (400 MHz, CDQ3): 3,

1.02 (s, 6H), 1.12 (s, 6H), 1.43 (t, /=6.8 Hz, 3H), 2.22 (q, J=7.2 Hz, 4H), 2.47 (s, 4H), 4.16 (q, J=7.2 Hz, 2H), 4.67 (s, 1H), 5.57 (s, br, 0.82H), 6.58 (dd, J=8Hz, J=2 Hz, 1H), 6.57 (d, J=8Hz,

1H), 7.01 (d, J=2 Hz, 1H); 13C NMR (100 MHz, CDCl3): 3c 14.89, 27.31, 29.32, 31.32, 32.21,

ble 2, 26c H16O5: C

ata for

40.87, 50.79, 64.34, 113.16, 113.84, 115.83, 119.88, 136.37, 144.10, 145.14, 162.07, 196.61; Anal. calcd for Cd5HзoO5: C 73.17, H 7.31; found: C 72.99, H 7.11.

The followed products were very low soluble, so we can't report appropriate spectral data for these compounds.

3.3.2. 13-(Naphthalen-2-yl)-5H-dibenzo[b,i]xanthene-5,7,12,14(13H)-tetraone (Table 2, 26d)

m.p. 292-293 C, IR (KBr, cm-1 ): Vmax : 3061, 1662, 1610; calcd for C31H16O5: C 79.48, H 3.41; found: C 79.32, H 3.31.

3.3.3.13-(4-Hydroxy-3-methoxyphenyl)-5H-dibenzo[b,i]xanthene-5,7,12,14(13H)-tetraone (Table 2, 27d)

m.p. 303-304 °C, IR (KBr, cm-1 ): Vmax : 3482, 1661, 1652; 1H NMR (400 MHz, DMSO): 3 3.71 (s, 3H), 4.99 (s, 1H), 6.61 (d, J=8 Hz, 1H), 6.77 (d, J=8 Hz, 1H), 6.93 (s, 1H), 7.88 (m, 2H), 7.95 (m, 2H), 8.00 (d, J=7.2 Hz, 2H), 8.09 (m, 2H), 8.91 (s, br, 1H); Anal. calcd for

C28H16O7: C 72.41, H 3.44; found:

H 3.35.

4. Conclusion

In summary, an efficient and environmentally benign procedure has been developed for the synthesis of various xanthene derivatives using Fe3O4@SiO2-SO3H as a nano magnetic catalyst under thermal and solvent-free conditions. The reaction produced corresponding products with excellent yield and within a short reaction time. The most noteworthy aspects of this

method reusabi

logy are simplicity of its operation, easy isolation of the product and excellent sability potential of the catalyst. The attractiveness of this protocol lies in its green approach in that the catalyst is easily recoverable using an external magnet, which makes the process economical.

Acknowledgements

We thank the Department of Chemistry and office of gifted student at Semnan University for their financial support. References

Ahmad M, King T A, Do-K Ko, Cha B H, Lee J. (2002) Performance and photo stability of

xanthenes and pyrromethene laser dyes in sole gel phases. J Phys D Appl Phys, 35, 1473-1476. Banerjee A, Mukherjee A K. (1981) Chemical aspects of santalin as a histological stain. Sain. Technol, 56, 83-85.

Bigdeli M A, Nemati F, Mahdavinia G H. (2007) HClO4-SiO2 catalyzed stereoselective synthesis of b-amino ketones via a direct Mannich-type reaction. Tetrahedron Lett, 48, 68016804.

Bigdeli M A, Heravi M M, Nemati F, Mahdavinia G H. (2008) Polyethyleneglycol an efficient solvent for stereoselective synthesis of P-amino ketones via direct Mannich reaction. ARKIVOC, xiii, 243-248.

Chen Z, Xue Z, Chen L, Geng Z, Yang R, Chen L, Wang Z. (2013) One-pot template-free synthesis of water-dispersive Fe3O4@C nanoparticles for adsorption of bovine serum albumin. New J Chem, 37, 3731-3736.

Darviche F, Balalaie S, Chadegani F, Salehi P. (2007) Diammonium Hydrogen Phosphate as a Neutral and Efficient Catalyst for Synthesis of 1,8-Dioxo-octahydroxanthene Derivatives in Aqueous Media, Synth Commun, 37,4059-4066.

Davarpanah J, Kiasat A R, Noorizadeh S, Ghahremani M. (2013) Nano magnetic double-charged diazoniabicyclo[2.2.2]octane dichloride silica hybrid: Synthesis, characterization, and application as an efficient and reusable organic-inorganic hybrid silica with ionic liquid

framework for one-pot synthesis of pyran annulated heterocyclic compounds in water, J Mol Catal A Chem, 376, 78-89.

Fareghi-Alamdari R, Golestanzadeh M, Agend F, Zekri N. (2013) Application of highly sulfonated single-walled carbon nanotubes: An efficient heterogeneous catalyst for the synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes under solvent-free conditions. C R Chimie, 16, 878-887.

Fatma Sh, Singh P K, Ankit P, Shireen, Singh M, Singh J. (2013) Thiamine hydrochloride as a promoter for the efficient and green synthesis of 12-aryl-8,9,10,12 tetrahydrobenzoxanthene-11-one derivatives in aqueous micellar medium. Tetrahedron let, 54, 6732-6736. Gong K, Fang D, Wang H L, Zhou X L, Liu, Z L. (2009) The one-pot synthesis of 14-alkyl- or aryl-14H-dibenzo[a,j]xanthenes catalyzed by task-specific ionic liquid. Dyes Pigments, 80, 3033.

Ilangovan A, Malayappasamy S, Muralidharan1S , Maruthamuthu S. (2011) A highly efficient green synthesis of 1, 8-dioxooctahydroxanthenes. Chem Cent J, 5, 81-87. Ion RM, Frackowiak D, Wiktorowicz K. (1998) The incorporation of various porphyrins into blood cells measured via flow cytometry, absorption and emission spectroscopy. Acta Biochim Polonica, 45, 833-845.

Karami B, Eskandari KH, Gholipour S , Jamshidi M. (2013) Facile and Rapid Synthesis of 9-Aryl 1,8-dioxooctahydroxanthenes Derivativesusing Tungstate Sulfuric Acid. Org Prep Proceed Int, 45, 220-226.

Khaksar S, Behzadi N. (2012) Mild and Highly Efficient Method for Synthesis of 14-Aryl(alkyl)-14H-dibenzo[a,j]xanthenes and 1,8-Dioxooctahydroxanthene Derivatives Using Pentafluorophenyl Ammonium Triflate as a Novel Organocatalyst. Chin J Catal, 33, 982-985.

Khazaei A, Zolfigol M A, Moosavi-Zare A R, Zare A, Khojasteh M, Asgari Z, Khakyzadeh V, Khalafi-Nezhad A. (2012) Organocatalyst trityl chloride efficiently promoted the solvent-free synthesis of 12-aryl-8,9,10,12-tetrahydrobenzo[a]-xanthen-11-ones by in situ formation of carbocationic system in neutral media. Catal Commun, 20, 54-57. Khazaei A, Reza Moosavi-Zare A, Mohammadi Z, Zare A, Khakyzadeh V, Darvishi G. (2013)

Efficient preparation of 9-aryl-1,8-dioxo-octahydroxanthenes catalyzed by nano-TiO2 with high

tion of hi G. (2

irkes KEB, r

recyclability. RSC Adv, 3, 1323-1326. Khurana J M, Magoo D, Aggarwal K, Aggarwal N, Kumar R, Srivastava C. (2012) Synthesis of novel 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthene-11-thiones and evaluation of their biocidal effects. Eur J Med Chem, 58, 470-477. Lambert RW, Martin JA, Merrett JH, Parkes KEB, Thomas GJ. (1997) PCT Int. Appl. WO Chem Abstr, 126, 212377y. Menchen S M, Benson S C, Lam J Y L, Zhen W G, Sun D Q, Rosenblum B B, Khan S H, Taing M.(2003) U.S. Patent, 6, 583-568.

Mokhtary M, Refahati S. (2013) Polyvinylpolypyrrolidone-supported boron trifluoride (PVPP-BF3); mild and efficient catalyst for the synthesis of 14-aryl-14#-dibenzo[a,j]xanthenes and bis(naphthalen-2-yl-sulfane) derivatives. Dyes Pigments, 99, 378-381.

Mulakayala N, Pavan KumarG, Rambabu D, Aeluri M, Basaveswara Rao M V, Pal M A. (2012) greener synthesis of 1,8-dioxo-octahydroxanthene derivatives under ultrasound. Tetrahedron Lett, 53, 6923-6926.

Nasir Baig R B, Varma R S. (2012) A highly active magnetically recoverable nano ferrite-glutathione-copper (nano-FGT-Cu) catalyst for Huisgen 1,3-dipolar cycloadditions. Green Chem, 14, 625-632.

Nemati F, Kiani H. (2011) A green and highly efficient protocol for catalyst-free Knoevenagel condensation and Michael addition of aromatic aldehydes with 1,3- cyclic diketones in PEG-400. Chin J Chem, 29, 2407-2410.

Nemati F, Arghan M, Amoozadeh A. (2012) Efficient, Solvent-Free Method for the One-Pot Condensation of P-Naphthol,Aromatic Aldehydes, and Cyclic 1,3-Dicarbonyl Compounds Catalyzed by Silica Sulfuric Acid. Synth Commun, 42, 33-39.

Nemati F, Elhampour A. (2012) Cellulose sulphuric acid as a biodegradable catalyst for conversion of aryl amines into azides at room temperature under mild conditions. J Chem Sci, 124, 889-892.

Nemati F, Heravi M M, Saeedirad R. (2012) Nano-Fe3O4 encapsulated-silica particles bearing sulfonic acid groups as a magnetically separable catalyst for highly efficient Knoevenagel condensation and Michael addition reactions of aromatic aldehydes with 1,3-cyclic diketones. Chin J Catal, 33, 1825-1831. Nemati F, Saeedirad R. (2013) Nano-Fe3O4 encapsulated-silica particles bearing sulfonic acid groups as a magnetically separable catalyst for green and efficient synthesis of functionalized

iano-Fe3(

pyrimido[4,5-b]quinolines and indeno fused pyrido[2,3-d]pyrimidines in water. Chin Chem Lett, 24, 370-372.

Poupelin JP, Saint-Rut G, Foussard-Blanpin O, Narcisse G, Uchida-Ernouf G, Lacroix R. (1978) Synthesis and anti-inflammatory properties of bis(2-hydroxy-1-naphthyl)methane derivatives. I. Monosubstituted derivatives. Eur J Med Chem, 13, 67-71.

Rafiee E, Eavani S. (2011) H3PW12O40 supported on silica-encapsulated Fe2O3 nanoparticles: a novel magnetically-recoverable catalyst for three-component Mannich-type reactions in water. Green Chem, 13, 2116-2122.

Rivera T S, Sosa A, Romanelli G P, Blanco M N, Pizzio L R. (2012) Tungstophosphoric acid/zirconia composites prepared by the sol-gel method: An efficient and recyclable green catalyst for the one-pot synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes. Appl Catal /

Safaei-Ghomi J, Ghasemzadeh M A. (2012) Zinc oxide nanoparticles: A highly efficient and readily recyclable catalyst for the synthesis of xanthenes. Chin Chem Lett, 23, 1225-1229. Safaei-Ghomi J, Ghasemzadeh M A. (2012) An efficient multi-component synthesis of 14-aryl-14H-dibenzo[a,j]xanthene derivatives by Agl nanoparticles. J Saudi Chem Soc, http://dx.doi.org/10.1016/jjscs.2012.05.007.

Saint-Ruf G, Hieu H T, Poupelin H P. (1975) The effect of dibenzoxanthenes on the paralyzing action of zoxazolamine. Naturwissenschaften, 62, 584-585.

Shaterian H R, Ranjbar M, Azizi K. (2011) Synthesis of benzoxanthene derivatives using Br0nsted acidic ionic liquids (BAILs), 2-pyrrolidonium hydrogen sulfate and (4-sulfobutyl)tris(4-sulfophenyl) phosphonium hydrogen sulfate. J Mol Liq, 162, 95-99. Shirini F, Khaligh N G. (2012) Succinimide-N-sulfonic acid: An efficient catalyst for the synthesis of xanthene derivatives under solvent-free conditions. Dyes Pigments, 95, 789-794. Sudha S, Pasha M A. (2012) Ultrasound assisted synthesis of tetrahydrobenzo[c]xanthene-11-ones using CAN as catalyst. Ultrason Sonochem, 19, 994-998.

Sun Y, Duan L, Guo Z, DuanMu Y, Ma M, Xu L, Zhang Y, Gu N. (2005) An improved way to prepare superparamagnetic magnetite-silica core-shell nanoparticles for possible biological application. J Magn Mater, 285, 65-70.

444, 207-213.

Tisseh Z N, Azimi S C, Mirzaei P, Bazgir A.(2008) The efficient synthesis of aryl-5H-dibenzo[b,i]xanthene-5,7,12,14 (13H)-tetraone leuco-dye derivatives. Dyes Pigments, 79, 273275.

Wan Y, Zhang X, Wang C, Zhao L, Chen L F, Liu G X, Huang S Y, Yue S N, Zhang W L, Wu H. (2013) The first example of glucose-containing Br0nsted acid synthesis and catalysis: efficient synthesis of tetrahydrobenzo[a]xanthens and tetrahydrobenzo[a]acridines in water. Tetrahedron, 69, 3947-3950.

Zare A, Moosavi-Zare A R, Merajoddin M, Zolfigol M A, Hekmat-Zadeh T, Hasaninejad A, Khazaei A, Mokhlesi M, Khakyzadeh V, Derakhshan-Panah F, Beyzavi M H, Rostami E, Arghoon A, Roohandeh R. (2012) Ionic liquid triethylamine-bonded sulfonic acid {[Et3N-SO3H]Cl} as a novel, highly efficient and homogeneous catalyst for the synthesis of P-acetamido

ketones, 1,8-dioxo-octahydroxanthenes and 14-aryl-14H-dibenzo[a,j]xanthenes. J Mol Liq, 167, 69-77'

Zelefack F, Guilet D, Fabre N, Bayet C, Chevalley S, Ngouela S, Lenta BN, Valentin A, Tsamo

E, Dijoux-Franca M G. (2009) Cytotoxic and Antiplasmodial Xanthones from Pentadesma butyracea. J Nat Prod, 72, 954-957.

Table 1. Optimization of the model reactiona

Entry Catalyst Catalyst loading Condition Time Yield (%)

(g) (min)

1 no ----------------neat/130°C 15 trace

2 Fe3O4@SiO2 0.05 neat/130°C 60 56

3 Fe3O4@SiO2-SO3H 0.05 EtOH/reflux 60 35

4 Fe3O4@SiO2-SO3H 0.05 H2O/reflux 60 nill

6 Fe3O4@SiO2-SO3H 0.05 CH3CN/reflux 60 45

7 Fe3O4@SiO2-SO3H 0.05 Toluene/reflux 60 55

8 Fe3O4@SiO2-SO3H 0.05 Neat/110°C 15 72

9 Fe3O4@SiO2-SO3H 0.05 Neat/120°C 15 81

10 Fe3O4@SiO2-SO3H 0.05 neat/130°C 4 94

11 Fe3O4@SiO2-SO3H 0.025 neat/130°C 35 94

12 Fe3O4@SiO2-SO3H 0.075 neat/130°C 4 94

aReaction condition: Dimedone(2 mmol), benzaldehyde (1 mmol), catalyst (0.05 g) at 130°C under solvent free condition.

Table 2. Fe3O4@SiO2-SO3H catalyzed synthesis of various xanthene derivatives.

Entry Aldehyde Product Yield Time M.p(Lit.) (°C)

(%)a (min)

»02-204(2(

(202-204)

94 4 (S afaei-Ghomi, &

Ghasemzadeh 2012)

224-227(225-227) 95 5 (Ilangovan et al., 2011)

235-238(228-239) (Shirini & Khaligh 2012)

250-256(248-249)(Safaei-Ghomi, & zadeh 2012)

hasemzai

171-172(166-168) (Safaei-Ghomi, & Ghasemzadeh 2012)

226-228(225-226) (Safaei-Ghomi, & Ghasemzadeh 2012)

239-241(240-241) (Safaei-Ghomi, & Ghasemzadeh 2012)

241-243(241-243) (Safaei-Ghomi, & Ghasemzadeh 2012)

-198(197-199) Shirini & Khaligh 2012)

193-194

197-199(198-200) (Mulakayala et al., 2012)

94 30 94 30

175-176(176-177) (Karami et al., 2013)

181-183(181-183) (Safaei-Ghomi, & Ghasemzadeh 2012)

215(214-215) (Gong et al., 2009)

191-193(192-194) (Safaei-Ghomi, & Ghasemzadeh 2012)

90 45 (Safaei-Ghomi, &

Ghasemzadeh 2012)

240-241(240-242)

311-313(312-314)(Zare et al., 2012)

295-297(295-296) (Safaei-Ghomi & Ghasemzadeh 2012)

149-151(149-151) (Nemati et al., 2012)

184-185(184-186) (Khurana et al., 2012)

167-169(167-170) (Khazaei et al., 2012)

178-179(179-180) ((Nemati et al., 2012)

204-206(204-205) (Khurana et al., 2012)

304-306(305-307)

(Tisseh et al., 2008) #

335-336(333-335) (Tisseh et al., 2008)

91 60 292-293

97 40 303-304

aAll yields refer to isolated products after crystallization.

Table 3. Effect of reusability of Fe3O4@SiO2-SO3H on the xanthenes yields. Product Yield% (cycle 1) Yield% (cycle 2) Yield% (cycle 3) Yield% (cycle 4)

13b 19c 24d

90 93 92

86 90 87

Table 4. Comparison of the results obtained for the synthesis of 3,3,6,6-tetramethyl-9-(4-chloro phenyl)-1,8-dioxo- octahydroxanthene (3a), tetra-hydrobenzo[a]xanthene-11-ones (13b), 9 dihydro-9,9-dimethyl-12-phenyl-8H-benzo[a]xanthen-11(12H)-one (19c) and 13-aryl

dibenzo[b,i]xanthene-5,7,12,14(13H)-tetraones (24d) catalyzed by Fe3Ü4@Si

O2-SO3

those recently reported catalysts.

Catalyst

Time Yiel

Condition

product

Succinimide-N-sulfonic

Neat/80°C

18 92 (Shirini & Khaligh 2012)

T"g"" " "" ™°°C ^

(Karami et al., 2013)

CAN/ultra son.

Nano-ZnO

2-Propanol/50°C 3a

40 93 (Mulakayala et al., 2012)

[Et3N-SÜ3H]Cl Nano-Ti

Neat/80°C

Neat/80°C

Neat/100°C

(NH4)2HPO4 then H2SO4 Water/25°C SmCl3

(Safaei-Ghomi, & Ghasemzadeh 2012)

(Zare et al., 2012) (Khazaei et al., 2013)

PFPATa

90 70 (Darviche et al., 2007) 3a 9 h 97 (Ilangovan et al., 2011) Toluene/25-30°C 3a 3 h 97 (Khaksar & Behzadi 2012)

Neat/120°C

CAN/ultra son.

SSWC nano tubeb

Nano-ZnO

[H-NMP] [HSO4]

DCM, EtOH 19c 120 85 (Sudha' & Pasha 2012)

PFPATa

Neat/70°C

Neat/80°C

Neat/110°C

Neat/100°C

Thiamine hydrochloride Rt /aqueous

micellar system

Fe3O4@SiO2-SO3H

Fe3O4@SiO2-SO3H

Neat/130°C

Neat/130°C

Fe3O4@SiO2-SO3H Neat/110°C

Fe3°4@Si°2-SO3H Neat/110°C

Toluene/25-30°C 13b 4.5 h

(Fareghi-Alamdari et al., 2013) (Safaei-Ghomi, &

13b 28 87

Ghasemzadeh 2012)

13b 12 94

24d 81

(Noroozi Tisseh et al., 2008)

90 (Khaksar & Behzadi 2012)

13b 30 94

(Fatma et al., 2013)

This work This work

This work

This work

aPentafluorophenyl ammonium triflate bsulfonated single-walled carbon nanotubes

Scheme 1. Synthesis of various Xanthene derivatives in the presence of Fe3O4@SiO2-SO3H

under solvent free condition.

Scheme 2. Plausible mechanism

Figure

^usability of Fe3O4@SiO2-SO3H for the preparation of tetrahydro-3,3,6,6-tetramethyl-9-phenyl-2H-xanthene-1,8(5H,9H)-dione (1a).

re 2. TEM image of Fe3O4@SiO2-SO3H after 5 runs.

Figure 3. FTIR spectra of Fe3O4@SiO2-SO3H (a) fresh, (b) after 5 runs recycle.

11111111111111111111111111111111111111111111111111111111111 10 20 30 40 50 60 70

20 (degree)

ttern of r

Figure 4. The XRD pattern of reused Fe3O4@SiO2-SO3H.

Captions of Figures and Schemes:

Scheme 1. Synthesis of various Xanthene derivatives in the presence of Fe3O4@SiO2-SO3H under solvent free condition. Scheme 2. Plausible mechanism. Figure 1. The reusability of Fe3O4@SiO2-SO3H for the preparation of tetrahydro-3,3,6,6-tetramethyl-9-phenyl-2H-xanthene-1,8(5H,9H)-dione (1a). Figure 2. TEM image of Fe3O4@SiO2-SO3H after 5 runs Figure 3. FTIR spectra of Fe3O4@SiO2-SO3H (a) fresh, (b) after 5 runs recycle. Figure. 4. The XRD pattern of reused Fe3O4@SiO2-SO3H

fter 5 run /