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Der Chemica Sinica, 2010, 1 (2): 15-20
ISSN: 0976-8505 CODEN (USA) CSHIA5
Microwave Assisted One Pot Synthesis of Substituted Dihydropyrimidine-2(1H) ones using 5-sulphosalicyclic acid as a Catalyst
Nazeruddin N. Gulam Mohammed*, Mahesh S. Pandharpatte Dept. of Chemistry (P.G Centre) A.K.IS Poona College of Arts, Science & Commerce, Camp, Pune -411001 ______________________________________________________________________________ ABSTRACT An efficient microwave assisted one pot synthesis of Dihydropyrimidine-2 (1H) from aldehydes, diketones and urea/thiourea using 5-sulphosalicylic acid as a catalyst is described, compared to classical Biginielli reaction the new method has advantage of good yield and short reaction time. Keywords: One Pot Synthesis, Dihydropyrimidine-2 (1H) ones, 5-silphosalicylic acid ______________________________________________________________________________ INTRODUCTION In recent years, dihydropyrimidine-2(1H)one derivatives have gained much interest for their biological and pharmaceuticals Properties such as HIV gp-120-CD4 inhibitors[1], calcium channel blockers[2], -adrenergic and neuropeptide Y antagonists[3], as well as antihypertensive, antitumor, antibacterial, anti-inflammatory[4] agent. The scope of this pharmacophore has been further increased by the identification of the Monostrol as a novel as a cell-permeable lead compound for the development of the new anticancer drugs[5] bearing the dihydropyrimidones core. Thus the development of facile and environmental friendly synthetic method towards dihydropyrimidines constitute active area of investigation of in organic synthesis, the first synthetic method for the preparation of dihydropyrimidine-2(1H) ones (DHPMs) was recorded by Biginelli [6], that involves the one pot three component condensation of aldehyde, 1, 3-dicarbonyl compounds and urea or thiourea in ethanol under strongly acidic conditions producing DHPMs, albeit in low yields. In the view of the pharmaceuticals importance of these compounds many improved catalytic methods have been developed [7-11]. Although these methods have their long reaction time, harsh reaction conditions, unsatisfactory yield and use of large quantity of catalyst. Therefore improvements with respect to the above 15 Pelagia Research Library
Nazeruddin N. Gulam Mohammed et al Der Chemica Sinica, 2010, 1 (2):15-20 ______________________________________________________________________________ have been continuously sought. In this paper we wish to report an efficient environment friendly procedure for the synthesis of DHPMs for aryl aldehyde using 5-sulphosalicyclic acid catalyst in microwave irradiation system. Several catalysts like PPA, AlCl3, H3BO3, conc., BF3OEt, NH4Cl, CAN, NBS, triflates of lanthanide compounds and In, Bi, Cu, along with microwave irradiation etc. have been tried[1216] to improve yields and conditions of Biginelli reaction. However, all these several methods involving these various catalyst suffer from one or the other drawback like, expensive reagents i.e., triflates of Bi, Cu, lanthanides etc., prolonged reaction time, and strongly acidic conditions, unsatisfactory yields and tedious workup procedures (e.g. acidic alumina) for the isolation of the pure product in good yields. Catalysts like, ferric oxide nano composites is effective and give good result, but the preparation procedure of this catalyst is very difficult. This requires the development of a new catalyst for high yield and the lack of inexpensive reagent, which requires shorter reaction time and with easier workup procedure. In this paper we wish to report an efficient environment friendly procedure for the synthesis of DHPMs for aryl aldehyde using 5sulphosalicyclic acid catalyst in microwave irradiation system. MATERIALS AND METHODS All reagents were purchased from Merck and Loba and used without further purification. Melting points were measured in open capillary and are uncorrected. The products were characterized by IR spectra, and 1H NMR. IR spectra were recorded on SHIMADZU instrument. 1 H NMR was recorded on MSL-300 instrument using TMS as an internal standard. Microwave irradiation was carried out in a domestic microwave oven (LG Model MG 1742 WE, 2450 MHz). General Procedure The mixture of an aldehyde (5mmoles), ethyl acetoacetate / acetyl acetone (6 mmoles), Urea/thiourea (10mmoles) and 5-silphosalicylic acid (0.164gm, 0.75mmol).mixed thoroughly in beaker and this reaction mixture were irradiated in microwave oven. Reaction was monitored by TLC After the completion of the reaction, the mixture was poured in water and crude product was collected as a precipitate and recrystallized by ethanol. RESULTS AND DISCOSSION

The condensation of aldehydes, diketones and urea/thiourea (carrying both electron-withdrawing and electron-donating groups in aldehydes), in presence of 5-sulphosalicylic acid as a catalyst under solvent free conditions yielded desired Dihydropyrimidine-2 (1H) ones derivatives in purity with good to excellent yields. As expected, satisfactory results were observed. The reaction is depicted in scheme 1 and results are summarized in Table 1. It was found that 5sulphosalicylic acid shows better catalytic activity.
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Nazeruddin N. Gulam Mohammed et al Der Chemica Sinica, 2010, 1 (2):15-20 ______________________________________________________________________________ SCHEME 1
O + RR1= Ar. R2= OEt,Me X= O, S H RCH3 O O + H2 N 3 NH2 O X 5-sulphosalicylic acid R2 M.W. H3 C N H 4 R1 NH X
Spectral Data 1)5-Ethoxycarbonyl-6-methyl-4-(phenyl)-3,4-dihydropyrimidin-2(1H)-one 1 H NMR (CDCl3) : 1.09 (t ,3H ,CH3), 2.24 (s ,3H ,CH3), 3.94 (q,2H, CH3), 5.09 (d, 1H, CH), 9.14 (brs, 1H, NH), 7.69 (brs, 1H, NH), 7.1-7.29 (m, 5H, Ar-H) ; I.R(KBr) : 3244.38, 3122.86, 2953.12, 1726.35, 1645.33, 1467.88, 1419.66 cm-1. 2)5-Ethoxycarbonyl-6-methyl-4-(4-Chlorophenyl)-3,4-dihydropyrimidin-2(1H)-one H NMR (CDCl3) : 1.17 (t, 3H, CH3), 2.83 (s, 3H, CH3), 4.07 (q, 2H, CH2), 5.85 (d, 1H, CH), 5.89 (s, 1H, NH), 7.21-7.28 (H, m, Ar-H), 8.14 (s, 1H, NH); I.R(KBr) : 3242.45, 3117.07, 2980.12, 1708, 1647.26 cm-1.
3)5-Ethoxycarbonyl-6-methyl-4-(2-Chloro phenyl)-3,4-dihydropyrimidin-2(1H)-one H NMR (CDCl3) : 1.07 (t, 3H, CH3), 2.33 (t, 3H, CH3), 4.0 (q, 2H, CH2), 5.78 (brs, 1H, NH), 5.87(d,1H,CH), 7.2 (d, 1H, Ar-H), 7.25 (t, 1H, Ar-H), 7.36 (t, 1H, Ar-H), 7.37 (d, 1H, Ar-H), 8.54 (brs, 1H, NH) ; I.R(KBr) : 3352.39, 3225.09, 3117.07, 2978.79, 1695.49, 1641.48, 1570.11, 1448.59cm-1
4)5-Ethoxycarbonyl-6-methyl-4-(4-Methoxyphenyl )-3,4-dihydropyrimidin-2(1H)- thione H NMR (CDCl3) : 1.16 (t, 3H, CH3), 2.34 (s, 3H, CH3), 3.76 (s, 3H, CH3), 4.08 (q, 2H, CH2), 5.3 (d, 1H, CH), 6.8 (d, 2H, Ar-H), 7.18 (d, 2H, Ar-H), 7.83 (s, 1H, NH), 8.47 (s, 1H, NH) ; I.R(KBr): 3315.74, 3173.01, 2985.91, 2937.68, 1720, 1664.64, 1570.11, 1510.31, 1454.38 cm-1.
5)5-Ethoxycarbonyl-6-methyl-4-(phenyl)-3,4-dihydropyrimidin-2(1H)-thione 1 H NMR (CDCl3): 1.14(t, 3H, CH3), 2.2((s ,3H ,CH3),4.1(q,2H, CH3), 5.3(s, 1H, NH), 6.87.9(m,5H,Ar-H),8.1(s,1H,NH) ; I.R(KBr):3327.32,3176.87,2983.98,1672.34,1572.04 cm-1.
6) 5-Acetyl--6-methyl- 4-phenyl -3,4-dihydropyrimidin-2(1H)-one H NMR (CDCl3): 1.57 (s, 3H, CH3), 1.24 (s, 3H, CH3), 2.12 (s, 1H, NH), 2.35 (s, 1H, NH), 5.43 (d, CH, NH), 7.23-7.31 (m, 5H, Ar-H) ; I.R(KBr) : 3259.81, 2924.18, 1701.27, 1606.76, 1572.42, 1462.45 cm-1
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Nazeruddin N. Gulam Mohammed et al Der Chemica Sinica, 2010, 1 (2):15-20 ______________________________________________________________________________ 7) 5-Acetyl- 6-methyl 4-(4-methoxy phenyl) -3,4-dihydropyrimidin-2(1H)-one 1 H NMR (CDCl3) : 1.24 (s, 3H, CH3), 2.47 (s, 3H, CH3), 3.76 (s, 3H, CH3), 5.86 (brs, 1H, NH), 8.0 (brs, 1H, NH), 5.4 (d, 1H, CH), 6.8 (d, 2H, Ar-H), 7.2 (d, 2H, Ar-H) ; I.R(KBr) : 3383.26, 3230.87, 2953.12, 1697.41, 1597.11, 1510.31cm-1 8) 13-acetyl-9-methyl-11-oxo-8-oxa-10,12-diazatricyclo [7.3.1.02,7] trideca-2,4,6-triene 1 H NMR (CDCl3) : 1.24 (s, 3H, CH3), 1.55 (s, 3H, CH3), 1.8 (brs, 1H, NH, D2O exch), 2.2 (brs, 1H, NH, D2O exch), 5.47 (t, 1H, CH), 4.57 (q, 1H, CH), 6.82 (d, 1H, Ar-H), 6.92 (t, 1H, Ar-H), 7.11 (d, 1H, Ar-H), 7.21 (t, 1H, Ar-H) ; I.R(KBr) : 3236.66, 3109.35, 2941.54, 1693.56, 1591.33, 1506.46 cm-1. 9) 5-Acetyl- 6-methyl 4- phenyl -3,4-dihydropyrimidin-2(1H)-thione 1 H NMR (CDCl3) : 1.65 (brs, 1H, NH), 2.14 (s, 3H, CH3), 2.35 (s, 3H, CH3), 5.45 (d, 1H, NH), 7.24-7.38 (m, 5H, Ar-H), 7.62 (brs, 1H, NH) ; I.R(KBr) : 3294.53, 3198.08, 2994.50, 1610.61, 1572.04, 1452.45 cm-1. 10) 5-Ethoxycarbonyl-6-methyl-4-(2-nitrophenyl)-3,4-dihydropyrimidin-2(1H)-thione H NMR (CDCl3) : 1.13 (t, 3H, CH3), 2.53 (s, 3H, CH3), 4.05 (q, 2H, CH2), 5.02 (d, 1H, CH), 7.23 (s, 1H, NH), 7.35-7.49 (m, 5H, Ar-H & NH), 7.96 (brs, 1H, NH) ; I.R(KBr) :3379.40, 3304.17, 3066.92, 2933.83, 1683.91, 1645.33, 1591.33, 1533.46 cm-1.
Table 1: Data for the synthesis of Dihydropyrimidine-2 (1H) ones in the presence 5silphosalicylic acid of catalyst in microwave oven power 350 W Entry R12 C6H5 4-(Cl)- C6H4 2-(Cl)- C6H4 4-(CH3O)- C6H4 C6H5 C6H5 4-(CH3O)- C6H4 2-(OH)- C6H4 C6H5 2-NO2- C6H4 4-(CH3O)- C6H4 2-(Cl)- C6H4 R2 OEt OEt OEt OEt OEt Me Me Me Me OEt OEt OEt X O O O S S O O O S S O S Time(minut es ) 2.0 1.5 2.3 3.3 2.3 1.45 2.30 2.45 1.45 4.3 3.30 4.0 Yield (%) M.P(obs/lit)C 205 /2047c 217 /216-21714c 215-216/215-/150-15216 208-209/( 208-209 )/242-/166-/ 200-/220-22216 229-230(228-230)18 149-150/(150-152)19 205-20621
11)5-Ethoxycarbonyl-6-methyl-4-(4-Methoxyphenyl)-3,4-dihydropyrimidin-2(1H)- one 1 H NMR (CDCl3) : 1.2 (t, 3H, CH3), 2.3 (s, 3H, CH3), 3.7(s, 3H, CH3), 4.1 (q, 2H, CH2), 5.3 (d, 1H, CH), 5.7 (brs, 1H, NH),6.8 (d, 2H, Ar-H), 7.3 (d, 2H, Ar-H) ,8.1(brs,1H,NH) ;I.R(KBr) :3242.45,3107.43,2982.05,2910.68,2835.45,1707.06, 1647.26,1510.31,1448.59,1386.86,1224.84,1091.75.
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Nazeruddin N. Gulam Mohammed et al Der Chemica Sinica, 2010, 1 (2):15-20 ______________________________________________________________________________ 12)5-Ethoxycarbonyl-6-methyl-4-(2-Chlorophenyl)-3,4-dihydropyrimidin-2(1H)-thione 1 HNMR(CDCl3)::7.30(m,5H,C6H5),7.07(s,1H,NH),6.50(d,,1H,CH),6.24(dd,.4Hz,1H,CH),5.35( s,1H, NH),5.01(s,1H,CH),4.20(s,2H,CH2),2.32(s, 3H, CH3),1.21(t, 3H, CH3); I.R(KBr) : 3240, 3109, 2976, 1703, 1653, 1460, 1226, 1093, 783 CONCLUSION In conclusion, a simple, quick and efficient method for the synthesis of Dihydropyrimidine-2 (1H) ones using 5-sulphosalicylic acid as catalyst was developed. The important advantage of the present protocol is the ability to tolerate variations in all the components of the reaction. This is one of the quickest and simple alternative giving moderates to good yield towards the synthesis of Dihydropyrimidine-2 (1H) ones. Acknowledgement Authors are thankful to Anjuman Khairul Islam Trust, Mumbai for financial assistance. REFERANCE [1] A. D. Patil, N. V. Kumar, W. C. Kokke , M.F. Bean, A.J. Freyer, C. Bors, S.Mai, A. Trunch, D.J. Faulkner, B.Carte, A.L.Preen, R.P. Hertzberg, R.K. Johnson & W.J. Westley, J. Org. Chem, 1995,60,1182, [2] K.S. Atwal, G.C. Rovnyak, S.D Kimball, D.M. Floyd,. J. Z. Gourgoutas, J. Sehwartz, K.M. Smillie & M.F. Malley, J. Med. Chem., 1990,33,2629. [3] C.O. Kappe. Eur. J. Med. Chem., 2000 ,35, 1043. [4] D.Bozing, P.Benko L.Petocz, M.Szecsey, P.Toempe, G.Gigler, I.Gacsalyi &I. Gyertyan, (EGIS Gyogyszergyar) Eur. Pat. Appl. EP) 1991,409.233,; Chem. Absrt, 1991,114, 247302z. [5] T.U. Mayer, S.J. Haggarty, R.W. King, S.I. Schreiber & T.J. Mitchison, Science, 1999,286,971, [6] P. Biginelli, Gazz. Chim. Ital., 1893,23, 360, [7] (a) M. M. Khodaei, A.R. Khosropur, M. Beygzadeh, Synth. Commun., 2004,34,1551, (b) S. Tu, F.Fang, S. Zhu, T Li, X. Zhang., Q.Zhuang, Synlett, 2004,93,537.(c) M.Gohain, D. Prajapatti, J. S.Sandhu, Synlett 2004. (d) D. S.Boss, K. Kumar, L. Fatima, Synlett 2004,279,(e) Z. T. Wang., L. W. Xu., C. G.Xia & H. Q. Wang Tetrahedron Lett., 2004,45,7951. [8] (a) P.Salehi, M Dabiri., M. Zolfigol , Bodagh Ford,. Tetradedron Lett., 2003,44. 2889.(b) G. S.Kiran Kumar ,K.Bhaskar.Reddy, C.h.Srinivas,J. S. Yadav, G.Sabitha, Synlett 2003,67. (c) K. R. Reddy., C. V. Reddy, M.Mahesh, P. V. Raju., V. N. Reddy Terahedron Lett., 2003,44.8173(d) S.Tu, F.Fang, C.Mioo, H.Jiang, Y. Feng, D.Shi, X.Wang, Tetrahedron Lett., 2003,44,6153 [9] (a) A. S.Paraskar, G. K.Dewkar & A. Sudalai, Tetrahedron Lett, 2003,44, 3305, (b) S.D.Boss, L. Fatima & H. B. Mereyala, J. Org. Chem. 2003,68,587, [10] (a)C. V.Reddy, M Mahesh., P. V. K Raju., T. R.BaBu, V.N.Reddy, Tetrahedron Lett.,2002.43, 2657.(b) J.Lu, Y.Bai, Synthesis 2002,23,466,(c) T. S.Zhang,S.L.Zhang,S.Y.Zhang,J.J.Guo, T. Li, J. Chem. Res. (S), 2002,37,. [11] (a) J.Lu, Y. Bai., Z.Wang., B. Yang.& B. Ma. Tetrahedron Lett.2000, 41.9075, (b) C. O Kappe, J. Org. Chem., 1997,62,7201, [12] Barluengo J, Thomus M, Rubio V & Gotor V J. J Chem Soc1979, 675. 19 Pelagia Research Library

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Der Pharma Chemica, 2011, 3(1):322-326 (http://derpharmachemica.com/archive.html)
ISSN 0975-413X CODEN (USA): PCHHAX
Microwave Promoted Perchloric Acid catalyzed One Pot Synthesis of Xanthene Derivatives under solvent free conditions
Nazeruddin N. Gulam Mohammed* and Mahesh S. Pandharpatte Department of Chemistry (P.G. Centre), Poona College of Arts, Science & Commerce, Pune _____________________________________________________________________________ ABSTRACT Microwave Promoted Perchloric Acid catalyzed One Pot Synthesis of 14-aryl 14H dibenzo[a,j]xanthene and 12-aryl-8, 9, 10, 12-tetrahydrobenzo[a]-xanthen-11-one derivatives by condensation of various substituted benzaldehydes , -naphthol and dimedone under solvent free conditions is described. Keywords: xanthenes, perchloric acid, solvent free conditions, microwave irradiation. _____________________________________________________________________________ INTRODUCTION Multi component reactions (MCRs) are continuously increasing their importance in organic and medicinal chemistry [13]. In the drug discovery process multi component reaction strategies offer significant advantages over conventional linear type syntheses [4-6]. In such reactions, three or more reactants come together in a single reaction vessel to form new products that contain portions of all the components. The search and discovery for new MCRs on one hand [7] and the full exploitation of the already known multi component reactions on the other hand, is therefore of considerable current interest. One such MCR that belongs to the latter category is synthesis of xanthene derivatives. Xanthenes and benzoxanthenes have attracted considerable interest because they possess various pharmaceutical activities such as anti-bacterial [8], anti-inflammatory [9], and anti-viral [10]. These structural motifs have also found a niche as antagonists for paralyzing the action of zoxazolamine[11] and demonstrate efficacy in photodynamic therapy[12]. In addition, these compounds have been employed as dyes [13] and pH-sensitive fluorescent materials for visualization of biomolecular assemblies [14] and utilized in laser technologies [15]. Thus a broad utility range has made xanthenes as a prime synthetic candidate thereby accentuating the 322 www.scholarsresearchlibrary.com
N. N. Gulam Mohammed et al Der Pharma Chemica, 2011, 3 (1):322-326 _____________________________________________________________________________ need to develop newer synthetic routes for scaffold manipulation of xanthene derivatives. The synthesis of tetrahydrobenzo[a]xanthen-11-ones has been reported in the presence of strontium triflate[16], indium trichloride, phosphorus pentaoxide[17], NaHSO4-SiO2 under reflux in halogenated solvents[18] for long hours. However, these methodologies suffer from one or more disadvantages such as low yields, lack of easy availability of the starting materials, prolonged reaction time (16 h), use of toxic organic solvents, requirement of excess of reagent catalyst and special apparatus. Thus, there is a need for development of an alternative route to synthesize the xanthene derivatives. In this context, we decided to investigate the possibility of synthesizing tetrahydrobenzo[a]xanthen-11-one derivatives through one-pot three-component condensation reaction strategy of -naphthol with aldehydes and cyclic 1, 3-dicarbonyl compounds using Perchloric acid as a catalyst under Microwave irradiation and solvent free conditions. The reaction is depicted in (Scheme 1& 2). The application of microwave irradiation [19] to the combinatorial chemistry becomes powerful tool in accelerating the pace of library synthesis. Microwave oven is most popularly used in synthesis because of its low cost and readily availability. Generally microwave irradiation enhances the rate of reaction and products are obtained in good to excellent yields.

HClO4 M.W. Solvent free

Scheme1

R-CHO 2 +

OH O CH3 CH3

O CH3 CH3

R=H,Cl,4-NO2

Scheme 2

MATERIALS AND METHODS All reagents were purchased from Merck and Loba and used without further purification. Melting points were measured in open capillary and are uncorrected. The products were characterized by IR spectra and 1H NMR. IR spectra were recorded on PerkinElmer FT-IR1710 instrument. 1H NMR was recorded on BrukerAC-200 MHz and BrukerMSL-300 MHz instrument using TMS as an internal standard. Microwave oven was used LG MOD-MG1742WE with 230V, 2450MHz and 700 W maximum.
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N. N. Gulam Mohammed et al Der Pharma Chemica, 2011, 3 (1):322-326 _____________________________________________________________________________ General procedure for the synthesis of 12-aryl-8, 9, 10, 12-tetrahydrobenzo[a]-xanthen11-one and 14-aryl -14H- dibenzo[a,j] xanthene derivatives : A mixture of aromatic aldehydes(1mmol), and -naphthol (1mmol),dimedone (1.1mmol) was taken in a borosil beaker (50mL), followed by addition of Perchloric acid (0.3 mmol).The reaction mixture was mixed properly with help of a glass rod and irradiated in a microwave oven at 420W for an appropriate time(Table 1).The reaction was monitored by TLC. After completion of the reaction , the reaction mixture was cooled to room temperature and treated with ice cool water.The product was filtered ,dried and recrystallized from ethanol.Identification of the compounds was done by comparing the physical constant and spectral data with those reported in the literature. The same procedure is applied for 14-aryl -14H- dibenzo[a,j] xanthene derivative using aldehydes(1mmol), and -naphthol (2mmol) and Perchloric acid (0.3mmol). 14-(phenyl)-14H-dibenzo[ a.j]xanthene(3a): Yield: 92%.; mp183C. IR (KBr, cm-1): 1151(CO- Str).; 1H NMR (300MHz, CDCl3): ppm 6.4(s, 1H), 6.89-8.4(m, 17H).
14-(4-chlorophenyl)-14H-dibenzo[a.j]xanthene(3b):Yield: 91%.; mp 286-288C. IR(KBr, cm) : 1163(C-O-C Str); 1H NMR (300MHz, CDCl3): ppm 6.43(s, 1H), 7.051-8.2(m, 16H). 14-(2-chlorophenyl)-14H-dibenzo[a.j]xanthene(3c): Yield: 88%.; mp 213-215C. IR(KBr, cm): 1165(C-O- Str).; 1H NMR (300 MHz, CDCl3): ppm 6.81(s, 1H), 6.902-8.7(m, 6H).

14-(4-methoxyphenyl)-14H-dibenzo[a.j]xanthene(3d):Yield:90%.; mp 202C. IR(KBr, cm-1): 1180(C-O- Str). ; 1H NMR (300MHz, CDCl3): ppm 6.422(s, 1H), 6.634-8.36(m, 16H), 3.59(s, 3H) 14-(4-Nitrophenyl)-14H-dibenzo[a.j]xanthene(3e):Yield:85%.; mp291-293C. IR (KBr, cm-1): 1166(C-O- Str); 1H NMR (300MHz, CDCl3): ppm 6.7(s, 1H), 7.019-8.511(m, 16H). 9, 9-Dimethyl-12-phenyl-8, 9, 10, 12-tetrahydrobenzo[a]-xanthen-11-one: (4a): Yield: 83%.; mp 150152 oC. IR (KBr, cm-1): 1645(C=O), 1185(C-O Str). 1H NMR (300 MHz, CDCl3): ppm: 7.99 (d, J=8.1Hz, 1H), 7.787.74 (m, 2H, Ar-H ), 7.427.04 (m, 8H, Ar-H), 5.70(s, 1H, CH), 2.57(s, 2H, CH2), 2.33(d, J=16.2Hz, 1H), 2.26(d, J=16.2Hz, 1H), 1.11 (s, 3H, CH3), 0.96 (s, 3H, CH3). 12-(4-Chlorophenyl)-9,9-dimethyl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-one(4b): Yield: 89%.: mp 180oC. IR (KBr, cm-1): 1649(C=O), 1185(C-O Str). 1H NMR (300 MHz, CDCl3): ppm: 7.92 (d, J=8.1Hz, 1H), 7.797.75(m, 2H, Ar-H), 7.457.11 (m, 7H, Ar-H), 5.67 (s, 1H, CH), 234(d, J=16.2Hz, 1H), 2.24(d, J=16.2Hz, 1H), 1.12 (s, 3H, CH3), 0.96 (s, 3H, CH3). 12-(4-Methoxyphenyl)-9,9-dimethyl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-one(4c): Yield :87%.; m.p. 206 oC. IR (KBr, cm-1): 1646(C=O), 1185 (C-O Str). 1H NMR (300 MHz, CDCl3): ppm: 7.99 (d, J=8.1Hz, 1H), 7.777.72 (m, 2H, Ar-H), 7.447.22 (m, 5H, Ar-H), 6.70 (d, J=8.4Hz, 1H), 5.65 (s, 1H, CH2), 3.8 (s, 3H,-OCH3), 2.55 (s, 2H, CH2), 2.33(d, J=16.2Hz, 1H), 2.26(d, J=16.2Hz, 1H), 1.11 (s, 3H, CH3), 0.97 (s, 3H, CH3).
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N. N. Gulam Mohammed et al Der Pharma Chemica, 2011, 3 (1):322-326 _____________________________________________________________________________ 12-(4-nitrophenyl)-9,9-Dimethyl-8,9,10,12-tetrahydrobenzo-[a]xanthen-11-one (4d): Yield :90%.: mp 174176oC. IR (KBr, cm-1): 1646(C=O), 1184(C-O Str). 1H NMR (300 MHz, CDCl3): ppm: 8.04 (d, J=8.5, 1H), 7.827.79 (m, 3H, Ar-H), 7.527.33 (m, 5H, Ar-H), 5.81 (s, 1H, CH), 2.59 (s, 2H, CH2), 2.37(d, J=16.4Hz, 1H), 2.3(d, J=16.4Hz, 1H), 1.13 (s, 3H, CH3), 0.94 (s, 3H, CH3). 12-(2-Chlorophenyl)-9,9-dimethyl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-one (4e): Yield :85%.; mp 179180oC. IR (KBr, cm-1): 1651(C=O), 1184(C-O Str). 1H NMR (300 MHz, CDCl3): ppm: 8.23 (d, J=8.4Hz, 1H), 7.767.72 (m, 2H, Ar-H), 7.497.26 (m, 5H, Ar-H), 7.076.96 (m, 2H, Ar-H), 5.98 (s, 1H, CH), 2.60 (s, 2H, CH2), 2.34(d, J=16.2Hz, 1H), 2.24 (d, J=16.2Hz, 1H), 1.13 (s, 3H,CH3), 0.99 (s, 3H,CH3). RESULT AND DISCUSSION We report here in a simple and efficient one pot synthesis of 14-aryl -14H- dibenzo[a,j] xanthene and 12-aryl-8, 9, 10, 12-tetrahydrobenzo[a]-xanthen-11-one derivatives by condensation of various substituted benzaldehydes, -naphthol and dimedone using perchloric acid as catalyst under microwave irradiation and solvent free condition. In all cases, aromatic aldehydes substituted with either electron-donating or electron-withdrawing groups underwent the reaction smoothly and gave the products in good to excellent yields. The results are shown in table 1.

Table: 1 Synthesis of 14-aryl 14H dibenzo [a,j] xanthene derivative in presence of perchloric acid as catalyst from -naphthol and aromatic aldeydes under microwave irradiation and solvent free condition
Product 3a 3b 3c 3d 3e 4a 4b 4c 4d 4e
R H 4-Cl 2-Cl 4-OCH3 2-NO2 H 4-Cl 4-OMe 4-NO2 2-Cl
Time (min) 120 2.2 2.0 3.0 2.5 2.5
Yield (%) Pure and Isolated 85 85
M.P.(C) (Obs / lit) 183 183[20] 286-288 287-288[22] 213-215 215[21] 202 200[20] 292 293[23] 150-152 151-153[17] 180 180-182[17] 206 204-205[17] 176-178 178-180[17] 179-180 179-180[17]
CONLUSION In summary we have developed an efficient one pot synthesis of 14-aryl -14H- dibenzo[a,j] xanthene and 12-aryl-8, 9, 10, 12-tetrahydrobenzo[a]-xanthen-11-one derivatives by condensation of various substituted benzaldehydes, -naphthol and dimedone using perchloric acid as catalyst under microwave irradiation and solvent free conditions. This methodology is having several advantages such as inexpensive catalyst and easily available reactant, shorter reaction time and products are obtained in excellent yields. Further this methodology also follows several principles of green chemistry.
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