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Synlett 2010(17): 2597-2600  
DOI: 10.1055/s-0030-1258575
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Efficient Synthesis of 2,3,4-Trisubstituted Quinolines via Friedländer Annulation with Nanoporous Cage-Type Aluminosilicate AlKIT-5 Catalyst

S. Chauhana, R. Chakravartia, S. M. J. Zaidib, Salem S. Al-Deyabc, B. V. Subba Reddy*a,d, A. Vinu*a,d
a International Center for Materials Nanoarchitectonics, WPI Research Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
Fax: +81(29)8604706; e-Mail: vinu.ajayan@nims.go.jp;
b Department of Chemical Engineering, King Fahd University of Petroleum & Minerals, Dhahran-31261, Saudi Arabia
c Department of Chemistry, Petrochemicals Research Chair, Faculty of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
d NIMS-IICT Materials Research Center, Indian Institute of Chemical Technology, Hyderabad 500 007, India
Further Information

Publication History

Received 27 July 2010
Publication Date:
23 September 2010 (online)

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Abstract

2-Aminoaryl ketones undergo smooth Friedländer condensation/annulation with α-methyleneketones on the surface of nanoporous aluminosilicate catalyst to afford the corresponding quinoline derivatives in good yields with high selectivity due to its high surface area, large pore volume, and high acidity. The use of highly acidic and reusable AlKIT-5 catalyst makes the Friedländer annulation simple, convenient, and practical.

Key words

o-aminoaryl ketones - nanoporous catalysts - domino ­reactions - quinolines

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General Procedure A mixture of 2-aminoaryl ketone (1.0 mmol), α-methylene ketone (1.0 mmol), and AlKIT-5 (50 mg) in EtOH (5 mL) was stirred at 80 ˚C for the specified time (see Table  [¹] ). After completion of the reaction, as monitored by TLC, the catalyst was separated by filtration, and the residue was washed with EtOH (10 mL). The combined organic layers were concentrated under reduced pressure, and the crude product was purified by silica gel column chromatography using EtOAc-n-hexane (1:9) as eluent to afford the pure quinoline derivative.
Spectral Data for Selected Products
Ethyl 2-Methyl-4-phenylquinoline-3-carboxylate (3a) Solid, mp 98 ˚C. IR (KBr): ν = 3030, 2960, 1700, 1605, 1568, 1482, 905 cm-¹. ¹H NMR (200 MHz, CDCl3): δ = 0.95 (t, J = 7.0 Hz, 3 H), 2.80 (s, 3 H), 4.05 (q, J = 7.0 Hz, 2 H), 7.35-7.50 (m, 6 H), 7.55 (d, J = 8.1 Hz, 1 H), 7.70 (t, J = 7.9 Hz, 1 H), 8.05 (d, J = 8.1 Hz, 1 H). MS (EI): m/z = 291 [M]+, 85, 263, 246, 218, 176, 150.
3-Acetyl-2-methyl-4-phenylquinoline (3d) Solid, mp 115 ˚C. IR (KBr): ν = 3027, 2960, 1705, 1610, 1569, 1485, 705 cm-¹. ¹H NMR (200 MHz, CDCl3): δ = 1.95 (s, 3 H), 2.60 (s, 3 H), 7.25-7.30 (m, 2 H), 7.35 (t, J = 8.0 Hz, 1 H), 7.40-7.50 (m, 3 H), 7.55 (d, J = 8.2 Hz, 1 H), 7.65 (t, J = 8.0 Hz, 1 H), 8.00 (d, J = 8.2 Hz, 1 H). MS (EI): m/z = 261 [M]+, 246, 218, 176, 150, 43. 9-Phenyl-1,2,3,4-tetrahydroacridine (3e) Solid, mp 137 ˚C. IR (KBr): ν = 3057, 2945, 1609, 1575, 1480, 1210, 708 cm-¹. ¹H NMR (200 MHz, CDCl3): δ = 1.75-1.85 (m, 2 H), 1.95-2.05 (m, 2 H), 2.60 (t, J = 6.7 Hz, 2 H), 3.20 (t, J = 6.9 Hz, 2 H), 7.20-7.32 (m, 3 H), 7.40-7.60 (m, 5 H), 8.00 (d, J = 8.2 Hz, 1 H). MS (EI): m/z = 259 [M]+, 230, 182, 176, 57.

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Syntheses of AlKIT-5 Catalyst with Different n Si /n Al Ratio
The AlKIT-5 materials with different nSi/nAl ratios were synthesized using Pluronic F127 as the template in an acidic medium. In a typical synthesis, 5.0 g of F127 was dissolved in 3 g of HCl (35 wt%) and 240 g of distilled H2O. To this mixture, 24.0 g of TEOS and the required amount of the aluminium isopropoxide were added, and the resulting mixture was stirred for 24 h at 45 ˚C. Subsequently, the reaction mixture was heated for 24 h at 100 ˚C under static conditions for hydrothermal treatment. After hydrothermal treatment, the final solid product was filtered off and then dried at 100 ˚C without washing. The product was calcined at 540 ˚C for 10 h. The samples are denoted as AlKIT-5 (x)where x denotes the nSi/nAl ratio in the final product.
The molar gel composition of the reaction mixture was
SiO2/Al2O3/F127/HCl/H2O = 1.0:0.041-0.071:0.0035:0.25:116.6.