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Aza-Diels–Alder Reactionswith Lanthanide Triflates:Syntheses of Quinoline andPhenanthridine DerivativesKadir Turhan a , Emel Pelit a & Zuhal Turgut aa Faculty of Art and Science, Yildiz TechnicalUniversity, Department of Chemistry , İstanbul,TurkeyPublished online: 15 Apr 2009.

To cite this article: Kadir Turhan , Emel Pelit & Zuhal Turgut (2009) Aza-Diels–Alder Reactions with Lanthanide Triflates: Syntheses of Quinoline andPhenanthridine Derivatives, Synthetic Communications: An International Journalfor Rapid Communication of Synthetic Organic Chemistry, 39:10, 1729-1741, DOI:10.1080/00397910802585902

To link to this article: http://dx.doi.org/10.1080/00397910802585902

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Aza-Diels–Alder Reactions with LanthanideTriflates: Syntheses of Quinoline and

Phenanthridine Derivatives

Kadir Turhan, Emel Pelit, and Zuhal TurgutFaculty of Art and Science, Yildiz Technical University,

Department of Chemistry, Istanbul, Turkey

Abstract: The aza-Diels–Alder reactions of cyclopentadiene and cyclo-1,3-hexadiene with various substituted N-arylimines in the presence of Yb=Sctriflates as catalyst in MeCN at room temperature gave quinoline andphenanthridine derivatives in moderate to high yields. Some of the cycloaddi-tion reactions were carried out in ionic liquid.

Keywords: Aza-Diels–Alder, heterocyclic compounds, phenanthridine, quinoline,triflates

INTRODUCTION

Nitrogen-containing six-membered compounds such as piperidines,tetrahydroquinolines, and phenanthridine derivatives are important het-erocycles in medicinal chemistry and useful intermediates in organicsynthesis. The aza-Diels–Alder reaction is one of the most usefulsynthetic tools for constructing N-containing six-membered hetero-cycles.[1–6] Usually the aza-Diels–Alder (or Povarov) reaction is carriedout in the presence of a Lewis acid such as ZnCl2, BF3, TiCl4, or InCl3or at high temperature in organic solvents.[7] Although Lewis acids oftenpromote these reactions, more than stoichiometric amounts of the acids

Received September 29, 2008.Address correspondence to Zuhal Turgut, Yildiz Technical University,

Faculty of Art and Science, Department of Chemistry, Davutpasa Campus,Esenler, 34220, Istanbul, Turkey. E-mail: zturgut61@yahoo.com

Synthetic Communications1, 39: 1729–1741, 2009

Copyright # Taylor & Francis Group, LLC

ISSN: 0039-7911 print=1532-2432 online

DOI: 10.1080/00397910802585902

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are required because of their strong coordination to N-atoms. In the lastcentury, Kobayashi and other researchers have reported that lanthanidetriflates are stable in H2O and that they are environmentally benignLewis acids.[8–11] Only a catalytic amount of the triflate is enough to com-plete these reactions. Good yields were obtained when these reactionswere performed in ionic liquids, and the used ionic liquid and catalystwere recovered.[12–15]

RESULTS AND DISCUSSION

In the presence of 10mol%of catalyst [Yb(OTf)3 or Sc(OTf)3],N-aryliminesreactedwith cyclopentadiene or cyclo-1,3-hexadiene inMeCNat room tem-perature (Scheme 1). The aza-Diels–Alder reaction proceeded smoothly toafford the corresponding tetrahydroquinoline (1a–l) derivatives in 51–84%moderate yields (Table 1) and hexahydrophenanthridine (2a–c) derivativesin 28–49% yields (Table 2). The obtained crude reaction mixture was sepa-rated by silica-gel chromatography, and isolated products were character-ized by the spectral evidence. In this reaction, the aromatic imines actedas azadienes toward one of the C¼C bonds of cyclodiene as a dienophile.The reaction yield was improved when Sc(OTf)3 was used instead ofYb(OTf)3 as catalyst. The triflates work as Lewis acids; they are stable inH2O, can be recovered after the reactions were completed, and can bereused.Only a catalytic amountof the triflate is enough to complete this typeof reaction.[16]Nevertheless, theyieldswere found tobequite low in the reac-tion with cyclo-1,3-hexadiene.

The 4- and 8-substituted-3a,4,5,9b-tetrahydro-3H-cyclopenta[c]qui-nolines 1 and 6-substituted phenyl-2-methyl=brom-5,6,6a,7,8,10a-hexa-hydrophenanthridines 2 were obtained using only a catalytic amount of

Scheme 1. Aza-Diels–Alder reactions of cyclopentadienes and cyclo-1,3-hexadiene with arylimines catalyzed by triflates.

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Table 1. Triflate-catalyzed Diels–Alder reaction with arylimines and cyclopenta-diene

Entry Dien R1 R2 Compound SolventCat.

(10mol%)Yielda

(%)

1 CH3� 1a CH3CN Yb(OTf)3 67

2 CH3� 1b CH3CN Yb(OTf)3 80

3 CH3� 1c CH3CN Yb(OTf)3 69

4 Br� 1d CH3CN Yb(OTf)3 76

5 CH3� 1e CH3CN Yb(OTf)3 58

6 Br� 1f CH3CN, ionicliquid

Yb(OTf)3 67, 71b

7 CH3� 1 g CH3CN, ionicliquid

Yb(OTf)3 78, 83b

8 CH3� 1 h CH3CN, ionicliquid

Yb(OTf)3 79, 84b

9 Br� 1i CH3CN, ionicliquid

Yb(OTf)3,Sc(OTf)3

76, 81c,84b

(Continued )

Synthesis of Quinoline Derivatives 1731

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the Yb=Sc (trifluoromethanesulfonate). The maximum eluated productwas separated after the thin-layer chromatography (TLC) was doneand compared with the starting materials. The structure of the new com-pounds have been clarified by Fourier transform–infrared (FTIR), mass,and NMR techniques and confirmed with elemental analysis. Thecharacteristic absorption bands of NH groups were observed at 3327–3386 cm�1 in the FTIR spectra of the tetrahydroquinoline and hexahy-drophenantridine derivatives. Olefinic proton signals, which belong toboth phenantridine and cyclopentaquinoline compounds, were observedat around 5.67 and 5.78 ppm. The H-atoms of CH2, which belong tothe cyclopentene ring, absorb in the ranges 1.69–1.89 and 2.37–2.80 ppm. The signals of CH2 that belong to the cyclohexene ring ofthe hexahydrophenanthridines were observed in the ranges 1.40–1.78and 1.90–2.21 ppm. The mass spectra of all new compounds showedthe expected molecular ion peaks. In each case, the endo diastereoisomerwas isolated almost exclusively. There exist three chrial centers at thesaturated part of the quinoline ring where the N atom is placed. The posi-tions of chrial centers of new molecules were found by the analysis oftheir correlation spectroscopy (COSY) spectrums.

Table 1. Continued

Entry Dien R1 R2 Compound SolventCat.

(10mol%)Yielda

(%)

10 Br� 1j CH3CN Yb(OTf)3,Sc(OTf)3

74, 80c

11 Br� 1k CH3CN Yb(OTf)3,Sc(OTf)3

51, 63c

12 CH3� 1l CH3CN Yb(Otf)3 65

aYields of pure isolated products, characterized by FTIR, GC-EIMS, 1H NMR,13C NMR, and elemental analysis.

bWith ionic liquid and Sc(OTf)3.cWith acetonitrile and Sc(OTf)3.

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Recently, some new ionic liquids have been used instead of organicsolvents in aza-Diels–Alder reactions.[12–15] Commonly used Diels–Alderreactions yield organic solvents and soluble Lewis acids such as ZnCl2,BF3, TiCl4, and InCl3 as wastes. These problems can be handled in alow-waste and recyclable reaction system based on an ionic liquid as alow volatility reaction medium and metal triflate as a recoverable cata-lyst. Therefore, we describe the use of 8-ethyl-1,8-diazabicyclo[5.4.0]-7-undecenium trifluoromethanesulfonate, which was prepared directlyfrom the 1,8-diazabicyclo[5.4.0]-7-undecene with ethyl trifluoromethane-sulfonate.[14] In our study, we examined the reactions of the correspond-ing imines with dienes in ionic liquid by using 10mol% catalyst Sc(OTf)3.Again the compounds 1f–i and 2a–c were obtained at room temperaturein high yields.

CONCLUSION

Substituted quinoline and phenanthridine derivatives 1 and 2 were synthe-sized from the reactions of arylimines with the cyclopentadiene and

Table 2. Triflate-catalyzed Diels–Alder reaction with arylimines and cyclo-1,3-hexadiene

Entry Dien R1 R2 Compound SolventCat.

(10mol%)Yielda

(%)

1 CH3� 2a CH3CN,ionicliquid

Yb(OTf)3,Sc(OTf)3

28b, 35c,39d

2 CH3� 2b CH3CN,ionicliquid

Yb(OTf)3,Sc(OTf)3

34b, 38c,43d

3 Br� 2c CH3CN,ionicliquid

Yb(OTf)3,Sc(OTf)3

43b, 48c,49d

aYields of pure isolated products, characterized by FTIR, GC-EIMS, 1H NMR,13C NMR, and elemental analysis.

bWith acetonitrile and Yb(OTf)3.cWith acetonitrile and Sc(OTf)3.dWith ionic liquid and Sc(OTf)3.

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cyclohexadiene in the presence of metal triflates that were expected to showbiological activities and were obtained by the aza-Diels–Alder reactions.It is believed that a small contribution has been made to this kind ofanalysis by cycloadditional reactions performed with variable substitutedarylimines in the presence of Yb(OTf)3 and=or Sc(OTf)3 catalysts.

In addition, for the same compounds using the reusable ionic liquid,we reduced the waste and hence reduced the harm to the environment.

EXPERIMENTAL

NMR spectra were recorded on Bruker Digital FT-NMR Avance-400400-MHz spectrometer. Chemical shifts d are in parts per million(ppm) with CDCl3 as solvent and are relative to tetramethylsilane(TMS) as the internal reference. The FTIR spectra were recorded on aPerkin-Elmer FT-IR spectrometer (KBr). Gas chromatography–electronimpact mass spectrometry (GC-EIMS) spectra were measured on aVarian SAT2100 T GC3900 spectrometer using ionization by fast atombombardment (FAB). Melting points were measured on a Gallenkampmelting-point apparatus. Silica gel 60 (Merck) was used for columnseparations. TLC was conducted on standard conversion aluminumsheets precoated with a 0.2-mm layer of silica gel. Elemental analyseswere measured with Flash EA 1112 series apparatus and were in goodagreement (�0.2%) with the calculated values.

General Procedure of Aza-Diels–Alder Reactions

Substituted imine compounds (0.5mmol) and cyclopentadiene(0.75mmol) in MeCN (1.5mL) were added successively to a solution ofYb(OTf)3 or Sc(OTf)3 (0.05mmol, 10mol%) in MeCN (1.0mL) at roomtemperature. The reaction mixture was stirred for 24 h, sat. aq. NaH-CO3(10mL) was added, and the product was extracted with EtOAc(3� 10mL). After drying (Na2SO4) and evaporation of the EtOAc phase,crude oil compounds 1a–l and 2a–c were obtained, which were furtherextracted by column chromatography, eluting with the indicated solvents.

Ionic Liquid: 8-Ethyl-1,8-Diazabicyclo[5.4.0]-7-Undecenium

Trifluoro Methanesulfonate

Ethyl trifluoromethanesulfonate (0.4mmol) was added slowly into anice-bath flask containing 1,8-diazabicyclo(5,4,0)-7-undecene (0.4mmol).

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After stirring for 2 h at room temperature, the mixture was heated to70�C and held 1 h at this temperature to remove the volatile materials,giving the viscous liquid in 96% yield.[14]

General Procedure of Aza-Diels–Alder Reactions in Ionic Liquid

A selected imine compound (3mmol) in ionic liquid (1 g) that had beenprepared according to the method used in Ref. 14 was stirred for30min at room temperature, and then cyclopentadiene (7mmol) orcyclohexadiene (7mmol) and Sc(OTf)3 (10mol%) were added to themixture. After 20–25 h of stirring at room temperature, the crude pro-duct was extracted with diethyl ether (10� 20mL). After removal ofthe solvent, tetrahydroquinoline or hexahydrophenanthridine wasobtained in moderate yields by column chromatography using amixture of solvents.

Data

4-(4-Methylphenyl)-8-methyl-3a,4,5,9b-tetrahydro-3H-cyclopenta[c] Qui-noline (1a)

Pale yellow crystals; mp 47�C [from toluene=n-hexane (1:1)]; 1H NMR(400MHz, CDCl3 d): 1.84–1.94 (m, 1H), 2.33 (s, 3H), 2.34 (s, 3H),2.64–2.71 (m, 1H), 3.07–3.11 (m, 1H), 3.64–3.67 (m, 1H), 4.19 (d, 1H,J¼ 8.8Hz), 4.62 (d, 1H, J¼ 3.2Hz), 5.46–5.48 (m, 1H), 5.86–5.75(m, 1H), 6.54–7.43 (m, 7H); 13C NMR (100MHz, CDCl3 d): 20.71,21.45, 32.71, 36.13, 37.70, 39.13, 42.71, 43.75, 47.61, 48.97, 53.53,61.60, 113.25, 126.91, 129.47, 130.05, 137.05, 146.27; GC-MS(EI, 70 eV): 275 (Mþ); FTIR (KBr) n 3383, 1505. Anal. calcd. forC20H21N (275.39): C, 87.22; H, 7.60; N, 5.09. Found: C, 87.19; H,7.61; N, 5.07.

4-(4-Chlorophenyl)-8-methyl-3a,4,5,9b-tetrahydro-3H-cyclopenta[c]Quinoline (1b)

Colorless crystals; mp 123�C [from toluene=n-hexane (3:1)]; 1H NMR(400MHz, CDCl3 d): 1.76–1.83 (m, 1H), 2.35 (s, 3H), 2.56–2.64(m, 1H), 2.92–2.99 (m, 1H), 3.60 (m, 1H), 4.07–4.10 (d, NH, 1H,J¼ 8.8Hz), 4.58–4.60 (d, 1H, J¼ 3.2Hz), 5.65–5.67 (m, 1H), 5.86–5.88(m, 1H), 6.55–7.41 (m, 7H). 13C NMR (100MHz, CDCl3 d): 20.88,

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31.54, 46.15, 46.52, 57.59, 116.25, 126.20, 127.35, 128.85, 129.63, 130.56,133.03, 134.27, 141.76, 143.01; GC-MS (EI, 70 eV): 296 (Mþ). FTIR(KBr) n 3384, 1463. Anal. calcd. for C19H18NCl (295.80): C, 77.15; H,6.13; N, 4.70. Found: C, 77.18; H, 6.14; N, 4.72.

4-(4-Bromophenyl)-8-methyl-3a,4,5,9b-tetrahydro-3H-cyclopenta[c] Qui-noline (1c)

Colorless crystals; mp 153�C [from n-hexane=toluene, (3:2)]; 1H NMR(400MHz, CDCl3 d): 1.79–1.85 (m, 1H), 2.35 (s, 3H), 2.37–2.46(m, 1H), 2.91–2.99 (m, 1H), 3.61 (m, 1H), 4.07–4.10 (d, 1H, J¼ 8.9Hz),4.58–4.60 (d, 1H, J¼ 3.2Hz), 5.65–5.68 (m, 1H), 5.86–5.88 (m, 1H),6.53–7.42 (m, 7H). 13C NMR (100MHz, CDCl3 d): 20.91, 31.66, 45.15,46.51, 58.11, 116.85, 126.27, 127.38, 128.76, 129.71, 130.56, 132.13,135.27, 141.25, 143.02. GC-MS (EI, 70 eV): 340 (Mþ). FTIR (KBr) n3379, 1469. Anal. calcd. for C19H18NBr (340.26): C, 67.07; H, 5.33; N,4.11. Found: C, 67.10; H, 5.34; N, 4.12.

4-(4-Bromophenyl)-8-brom-3a,4,5,9b-tetrahydro-3H-cyclopenta[c]Quinoline (1d)

Colorless crystals; mp 166�C [from toluene=n-hexane (1:1)]; 1H NMR(400MHz, CDCl3 d): 1.75–1.85 (m, 1H), 2.54–2.66 (m, 1H), 2.99(m, 1H), 3.61 (m, 1H), 4.08 (d, 1H, J¼ 8.7Hz), 4.56–4.60 (d, 1H,J¼ 3.1Hz), 5.67 (m, 1H), 5.81 (m, 1H), 6.57–7.45 (m, 7H). 13C NMR(100MHz, CDCl3 d): 21.02, 31.44, 45.74, 46.31, 58.29, 117.20, 123.40,126.21, 127.35, 128.65, 129.63, 130.17, 133.63, 134.27, 142.10, 143.76.GC-MS (EI, 70 eV): 405 (Mþ). FTIR (KBr) n 3379, 1484. Anal. calcd.for C18H15NBr2 (405.13) C, 53.36; H, 3.73; N, 3.45. Found: C, 53.39;H, 3.71; N, 3.44.

4-(4-Methoxyphenyl)-8-methyl-3a,4,5,9b-tetrahydro-3H-cyclopenta[c]Quinoline (1e)

Colorless crystals; mp 74�C [from toluene=n-hexane (1:1)]; 1H NMR(400MHz, CDCl3 d) 1.77–1.86 (m, 1H), 2.35 (s, 3H), 2.54–2.66 (m, 1H),2.91–2.99 (m, 1H), 3.62 (m, 1H), 3.75 (s, 3H), 4.11 (d, NH, 1H,J¼ 8.9Hz), 4.58 (d, 1H, J¼ 3.1Hz), 5.65–5.69 (m, 1H), 5.82–5.86 (m,1H), 6.52–7.41 (m, 7H); 13C NMR (100MHz, CDCl3 d): 20.93, 31.44,46.15, 46.82, 57.59, 116.25, 126.20, 127.35, 127.85, 128.10, 128.63,

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130.76, 133.23, 133.97, 141.76, 143.00; GC-MS (EI, 70 eV): 291 (Mþ);FTIR (KBr) n 3374, 1507. Anal. calcd. for C20H21NO (291.39): C,82.43; H, 7.26; N, 4.81. Found: C, 82.41; H, 7.27; N, 4.81.

4-(4-Methoxyphenyl)-8-brom-3a,4,5,9b-tetrahydro-3H-cyclopenta[c]Quinoline (1f)

Colorless crystals; mp 126�C [from toluene=n-hexane (1:1)] 1H NMR(400MHz, CDCl3 d): 1.77–1.83 (m, 1H), 2.46–2.54 (m, 1H), 2.90–2.98(m, 1H), 3.60 (m, 1H), 3.75 (s, 3H), 4.07–4.10 (d, 1H, J¼ 8.9Hz),4.56–4.60 (d, 1H, J¼ 3.3Hz), 5.63–5.67 (m, 1H), 5.85–5.88 (m, 1H),6.51–7.41 (m, 7H). 13C NMR (100MHz, CDCl3 d): 31.54, 46.52,57.69, 116.25, 126.20, 127.35, 127.85, 129.53, 130.56, 133.11, 133.37,141.96, 143.11. GC-MS (EI, 70 eV): 356 (Mþ). FTIR (KBr) n 3377,1489. Anal. calcd. for C19H18NBrO (356.25): C, 64.06; H, 5.09; N:3.93. Found: C, 64.08; H, 5.09; N, 3.94.

4-(2,4-Dimethylphenyl)-8-methyl-3a,4,5,9b-tetrahydro-3H-cyclopenta[c]Quinoline (1g)

Colorless crystals; mp 113�C [from toluene=n-hexane (1:1)]; 1H NMR(400MHz, CDCl3 d): 1.76–1.88 (m, 1H), 2.30 (s, CH3, 3H), 2.31(s, 3H), 2.33 (s, 3H), 2.68–2.80 (m, 1H), 3.04–3.06 (m, 1H), 3.42(m, 1H), 4.10 (d, 1H, J¼ 8.6Hz), 4.79 (d, 1H, J¼ 3.3Hz), 5.70 (m, 1H),5.86 (m, 1H), 6.42–7.55 (m, 6H); 13C NMR (100MHz, CDCl3 d): 20.81,21.13, 24.75, 39.10, 46.89, 54.71, 126.19, 127.23, 129.60, 130.79, 131.45,134.15, 135.06, 136.58; GC-MS (EI, 70 eV): 289 (Mþ). FTIR (KBr)n 3337, 1447. Anal. calcd. for C21H23N (289.42): C, 87.15; H, 8.01; N,4.84. Found: C, 87.12; H, 8.03; N, 4.86.

4-(2,4-Dichlorophenyl)-8-methyl-3a,4,5,9b-tetrahydro-3H-cyclopenta[c]Quinoline (1h)

Colorless crystals; mp 151�C [from toluene=n-hexane (1:1)]; 1H NMR(400MHz, CDCl3 d): 1.62–1.69 (m, 1H), 2.17 (s, 3H), 2.44–2.51(m, 1H), 3.07–3.15 (m, 1H), 3.35 (m, 1H), 4.01 (d, 1H, J¼ 8.5Hz), 4.83(d, 1H, J¼ 3.2Hz), 5.57–5.58 (m, 1H), 5.77–5.79 (m, 1H), 6.45–7.55(m, 6H). 13C NMR (100MHz, CDCl3 d): 19.96, 31.90, 41.21, 42.71,54.10, 114.70, 126.13, 126.91, 127.80, 129.21, 132.10, 132.70, 129.76,141.10. GC-MS (EI, 70 eV): 330 (Mþ). FTIR (KBr) n 3367, 1466. Anal.

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calcd. for C19H17NCl2 (330.25): C, 69.10; H, 5.18; N, 4.24. Found: C,69.14; H, 5.19; N, 4.26.

4-(2,4-Dimethylphenyl)-8-brom-3a,4,5,9b-tetrahydro-3H-cyclopenta[c]Quinoline (1i)

Colorless crystals; mp 155�C; [from n-hexane=toluene (4:1)]; 1H NMR(400MHz, CDCl3 d): 1.78–1.84 (m, CH2, 1H), 2.34 (s, 3H), 2.36(s, 3H), 2.63–2.71 (m, 1H), 3.05 (m, 1H), 3.61 (m, 1H), 4.09 (d, 1H,J¼ 8.8Hz), 4.77 (d, 1H, J¼ 3Hz), 5.70 (m, 1H), 5.82 (m, 1H), 6.51(d, 1H), 7.02–7.47 (m, 5H). 13C NMR (100MHz, CDCl3 d): 21.41,31.77, 43.02, 46.66, 54.23, 112.11, 117.65, 125.95, 127.07, 129.25,131.57, 133.67, 136.79, 145.58. GC-MS (EI, 70 eV): 354 (Mþ). FTIR(KBr) n 3379, 1483. Anal. calcd. for C20H20NBr (354.28): C, 67.80;H, 5.69; N, 3.95. Found: C, 67.83; H, 5.70; N, 3.96.

4-(2,4-Dichlorophenyl)-8-brom-3a,4,5,9b-tetrahydro-3H-cyclopenta[c]Quinoline (1j)

Colorless crystals; mp 191�C [from toluene=n-hexane (1:1)]; 1H NMR(400MHz, CDCl3 d): 1.85–1.87 (m, 1H), 2.48–2.50 (m, 1H), 3.16–3.22(m, 1H), 3.59 (m, 1H), 4.20 (d, 1H, J¼ 8.6Hz), 4.80 (d, 1H, J¼ 3Hz),5.64 (m, 1H), 5.82 (m, 1H), 6.46–6.52 (m, 2H), 6.90–7.58 (m, 4H); 13CNMR (100MHz, CDCl3 d): 31.38, 40.51, 44.56, 53.66, 113.80, 116.89,126.15, 127.15, 128.20, 129.30, 131.20, 133.89, 137.20, 143.25. GC-MS(EI, 70 eV): 395 (Mþ). FTIR (KBr) n 3371, 1485. Anal. calcd. forC18H14NBrCl2 (395.12): C, 54.71; H, 3.57; N, 3.54. Found: C, 54.72;H, 3.58; N, 3.53.

4-Bromo-2-(8-brom-3a,4,5,9b-tetrahydro-3H-cyclopenta[c]quinolin-4-yl)Phenol (1k)

Colorless crystal, mp 177�C [from toluene=n-hexane (2:1)]; 1H NMR(400MHz, CDCl3 d): 1.97–2.07 (m, 1H), 2.54–2.61 (m,1H), 2.90–2.98(m, 1H), 3.72 (m, 1H), 4.09 (d, 1H, J¼ 8.9Hz), 4.61 (d, 1H, J¼ 3Hz),5.67 (m, 1H), 5.83 (m, 1H), 6.44–7.53 (m, 6H). 13C NMR (100MHz,CDCl3 d): 33.40, 46.70, 54.10, 64.80, 112.40, 125.90, 126.60,127.15, 127.35, 127.50, 128.10, 129.21, 131.18, 143.10. GC-MS (EI,70 eV): 421 (Mþ). FTIR (KBr) n 3645, 3379, 1484. Anal. calcd. forC18H15NBr2O (421.11): C, 51.34; H, 3.59; N, 3.32. Found: C, 51.36;H, 3.60; N, 3.33.

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8-Methyl-4-(naphthalen-2-Yl)-3a,4,5,9b-tetrahydro-3H-cyclopenta[c]Quinoline (1l)

Colorless crystals, mp 114�C [from toluene=n-hexane (3:1)]; 1H NMR(400MHz, CDCl3 d): 1.87–1.93 (m, 1H), 2.31 (s, 3H), 2.49–2.56 (m,1H), 2.98–3.12 (m, 1H), 3.88 (m, 1H), 4.10 (m, 1H, J¼ 3.2Hz), 4.58(d, 1H, J¼ 8.7Hz), 5.71 (m, 1H), 5.89 (m, 1H), 6.44–7.83 (m, 10H);13C NMR (100MHz, CDCl3 d): 19.95, 33.10, 47.70, 54.10, 64.80,112.40, 125.90, 126.60, 127.15, 127.35, 127.50, 128.10, 129.21, 131.18,143.10; GC-MS (EI, 70 eV): 313 (Mþ). FTIR (KBr) n 3385, 1519. Anal.calcd. for C23H23N (313.43): C, 88.14; H, 7.39; N, 4.47. Found: C, 88.12;H, 7.41; N, 4.47.

6-(2,4-Dimethylphenyl)-2-methyl-5,6,6a,7,8,10a-hexahydrophenanthridine (2a)

Colorless crystal; mp 103�C [from toluene=n-hexane (1:1)]; 1H NMR(400MHz, CDCl3 d): 1.35–1.43 (m, 1H), 1.69–1.74 (m, 1H), 1.89–1.94(m, 1H), 2.21 (m, 1H), 2.32 (s, 3H), 2.36 (s, 3H), 2.37 (s, 3H), 2.69(m, CH, 1H), 3.40 (m, CH, 1H), 4.18 (d, 1H, J¼ 8.7Hz), 4.71(d, 1H,J¼ 3Hz), 5.73 (m, 1H), 5.82 (m, 1H), 6.42–7.52 (m, 6H). 13C NMR(100MHz, CDCl3 d): 19.24, 20.25, 25.64, 44.42, 111.82, 119.80,125.55, 126.85, 127.39, 130.70, 134.38, 137.40, 140.13, 145.19; GC-MS(EI, 70 eV): 302 (Mþ); FTIR (KBr) n 3386, 1509. Anal. calcd. forC22H24N (301.43): C, 87.37; H, 7.99; N, 4.63. Found: C, 87.39; H,7.98; N, 4.65.

6-(2,4-Dichlorophenyl)-2-methyl-5,6,6a,7,8,10a-hexahydrophenanthridine (2b)

Colorless crystal; mp 139�C [from n-hexane=toluene (2:1)]; 1H NMR(400MHz, CDCl3 d): 1.36–1.47 (m, 1H), 1.78–1.88 (m, 1H), 1.94–2.01 (m, 1H), 2.14 (m, CH2, 1H), 2.35 (s, 3H), 3.42 (1H), 3.63 (1H),4.18 (d, 1H, J¼8.9Hz), 4.82 (d, 1H, J¼ 3.2Hz), 5.78 (m, 1H),5.89 (m, 1H), 6.45–7.39 (m, 6H). 13C NMR (100MHz, CDCl3 d):20.28, 25.40, 34.37, 55.03, 75.75, 114.39, 123.82, 124.27, 126.14,127.88, 129.31, 132.31, 132.49, 136.71, 136.88, 139.90; GC-MS (EI,70 eV): 344 (Mþ). FTIR (KBr) n 3327, 1504. Anal. calcd. forC20H19NCl2 (344.28): C, 69.77; H, 5.56; N, 4.06. Found: C, 69.79;H, 5.58; N, 4.07.

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6-(2,4-Dichlorophenyl)-2-brom-5,6,6a,7,8,10a-hexahydrophenanthridine (2c)

Colorless crystal; mp 182�C [from toluene=n-hexane (1:1)]; 1H NMR(400MHz, CDCl3 d): 1.30–1.37 (m, 1H), 1.79–1.88 (m, 1H), 1.92–1.98(m, 1H), 2.15–2.2 (m, 1H), 2.45 (m, 1H), 2.95–3.02 (m, 1H), 3.62(m, 1H), 4.12 (d, 1H, J¼ 8.9Hz), 4.9 (d, 1H, J¼ 3.1Hz), 5.74 (m, 1H),5.89 (m, 1H), 6.40–7.54 (m, 6H). 13C NMR (100MHz, CDCl3 d):24.39, 33.73, 35.75, 54.76, 75.99, 76.25, 109.48, 115.71, 125.83, 126.65,127.60, 128.28, 128.33, 130.54, 132.59, 136.23, 141.36. GC-MS (EI,70 eV): 409 (Mþ). FTIR (KBr) n 3379, 1487. Anal. calcd. forC19H16NBrCl2 (409.15): C, 55.77; H, 3.94; N, 3.42. Found: C, 55.78;H, 3.95; N, 3.43.

Recovery of the Catalyst: Typical Procedure

The precipitate filtered after workup of the reaction mixture wassuspended in H2O (2mL). The mixture was acidified with CF3SO3H,and the resulting solution was stored at 0�C for 24 h. The white preci-pitate formed was filtered, dried at 70�C for 5 h, and used for furtherreactions.

ACKNOWLEDGMENTS

We gratefully acknowledge financial support of this research by theScientific and Technical Research Council of Turkey (TUBITAK)(Project Number 105T421).

REFERENCES

1. Brisson, M.; Nguyen, T.; Vogt, A.; Yalowich, J.; Giorgianni, A.; Tobi, D.;Bahar, I.; Stephenson, C. R. J.; Wipf, P.; Lazo, J. Discovery and character-ization of novel small molecule inhibitors of human Cdc25B specificityphosphatase. Mol. Pharmacol. 2004, 66, 824–833.

2. Luo, S.; Zhu, L.; Taludar, A.; Zhang, G.; Mi, X.; Chjeng, J.; Wang, P. Recentadvances in rare-earth-metal triflate catalyzed organic synthesis in greenmedia. Mini-Rev. Org. Chem. 2005, 2, 546–564.

3. Mohan, C.; Bhargava, G.; Pannu, A. P. S.; Mahajan, M. An unprecedentedmethylene oxidation accompanying the aza-Diels–Alder reactions of acyclicunactivated alkenes: Synthesis of novel quinolin-3-one substituted pyrimidi-none derivatives. Tetrahedron Lett. 2007, 48, 1711–1713.

1740 K. Turhan, E. Pelit, and Z. Turgut

Dow

nloa

ded

by [

Ston

y B

rook

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vers

ity]

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26

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ober

201

4

4. Hermitage, S.; Jay, D. A.; Whiting, A. Evidence for the non-concerted [4þ 2]-cycloaddition of N-aryl imines when acting as both dienophiles and dienesunder Lewis acid–catalysed conditions. Tetrahedron Lett. 2002, 43,9633–9636.

5. Cheng, K.; Lin, L.; Chen, S.; Feng, X. A mild and efficient aza-Diels–Alderreaction of N-benzhydryl imines with trans-1-methoxy-2-methyl-3-trimethyl-siloxybuta-1,3-diene catalyzed by Yb(OTf)3. Tetrahedron 2005, 61,9594–9599.

6. Donaldson, L. R.; Haigh, D.; Hulme, A. N. A study of Heck cyclizationreactions to form phenanthridine ring systems. Tetrahedron 2008, 64(19),4468–4477.

7. Ramesh, E.; Raghunathan, R. Indium chloride–catalyzed Intramolecularcyclization of N-aryl Imines: Synthesis of pyrrolo[2,3-d]pyrimidine annulatedtetrahydroquinoline derivatives. Tetrahedron Lett. 2008, 49(16), 2583–2587.

8. Kobayashi, S.; Araki, M.; Ishitani, H.; Nagayama, S.; Hachiya, I. Activationof imines by rare earth metal triflates: Ln(OTf)3- or Sc(OTf)3- catalyzed reac-tions of imines with silyl enolates and Diels–Alder reactions of imines. Synlett1995, 233–234.

9. Kobayashi, S.; Nagayama, S. A new methodology for combinatorialsynthesis: Preparation of diverse quinoline derivatives using a novel polymer-supported scandium catalyst. J. Am. Chem. Soc. 1996, 118, 8977–8978.

10. Powell, D. A.; Batey, R. A. Lanthanide(III)-catalyzed multi-componentaza-Diels–Alder reaction of aliphatic N-arylaldimines with cyclopentadiene.Tetrahedron Lett. 2003, 44, 7569–7573.

11. Kouznetsov, V. V.; Bohorquez, A. R. R.; Stashenko, E. E. Three-componentimino Diels–Alder reaction with essential oil and seeds of anise: Generationof new tetrahydoquinolines. Tetrahedron Lett. 2007, 48, 8855–8860.

12. Aggarwal, A.; Lancaster, N. L.; Sethi, A. R.; Welton, T. The role hydrogenbonding in controlling the selectvity of Diels–Alder reactions in room-temperature ionic liquids. Green Chem. 2002, 4, 517–520.

13. Sarma, D.; Kumar, A. Rare earth metal triflates promoted Diels–Alderreactions in ionic liquids. Appl. Catal. A: Gen. 2008, 335, 1–6.

14. Zulfiqar, F.; Kitamuze, T. One-pot aza-Diels–Alder reactions in ionic liquids.Green Chem. 2000, 2(2), 137–139.

15. Tiwari, S.; Kumar, A. Diels–Alder reactions are faster in water than in ionicliquids at room temperature. Angew. Chem. 2006, 118, 4942–4943.

16. Kobayashi, S. Scandium triflate in organic synthesis. Eur. J. Org. Chem.1999, 15–27.

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