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DOI: 10.1055/s-2004-829576
An Efficient One-Pot Synthesis of Pyrano- and Furoquinolines Employing Two Reusable Solid Acids as Heterogeneous Catalysts [1]
Publication History
Publication Date:
15 July 2004 (online)
Abstract
Two solid acids, Fe3+-K-10 montmorillonite clay and HY-zeolite have been employed efficiently for single-step synthesis of pyrano- or furoquinolines in high yields and high diastereoselectivities by coupling of three components: anilines, benzaldehydes and 3,4-dihydro-2H-pyran or 2,3-dihydrofuran. Both the heterogeneous catalysts are recoverable and recyclable.
Key words
Pyrano- and furoquinolines - solid acids - multicomponent coupling - diastereoselectivity
Part 41 in the series ‘Studies on Novel Synthetic Methodologies’.
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References
Part 41 in the series ‘Studies on Novel Synthetic Methodologies’.
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General Procedure for the Preparation of Pyrano- and Furoquinolines: To a solution of aniline (1 mmol), benzaldehyde (1 mmol) and 3,4-dihydro-2H-Pyran or 2,3-dihydrofuran (0.1 mL) in MeCN or CH2Cl2 (10 mL) Fe3+-K-10 clay or HY-zeolite (PQ Corporation, USA; 100 mg) was added. The mixture was stirred at r.t. with the first catalyst but refluxed with the second catalyst under N2 atmosphere. The reaction was monitored by TLC. After completion of the reaction, the mixture was filtered. The concentrated filtrate was subjected to column chromatography over silica gel and the column was eluted with hexane-EtOAc (20:1) to afford the pyrano- or furoquinolines. Both the catalyst, Fe3+-K-10 clay and HY-zeolite were recovered by washing the residue of filtration with MeCN and CH2Cl2, respectively, activated and recycled.
All the prepared compounds are known. The spectral data of some representative pyrano and furoquinolines are given below.
4b: solid, mp 146-147 °C. 1H NMR (200 MHz, CDCl3): δ = 7.32 (2 H, d, J = 8.0 Hz), 7.18 (1 H, d, J = 8.0 Hz), 7.04 (1 H, t, J = 8.0 Hz), 6.84 (2 H, d, J = 8.0 Hz), 6.64 (1 H, t, J = 8.0 Hz), 6.45 (1 H, d, J = 8.0 Hz), 4.64 (1 H, d, J = 10.0 Hz), 4.36 (1 H, d, J = 2.5 Hz), 4.06 (1 H, m), 3.97 (1 H, d, J = 3.0 Hz), 3.82 (3 H, s), 3.63 (1 H, t, J = 10.0 Hz), 2.02 (1 H, m), 1.82 (1 H, m), 1.64 (1 H, m), 1.44 (1 H, m), 1.28 (1 H, m). MS-FAB: m/z = 296 [M+ + 1].
5b: solid, mp 154-155 °C. 1H NMR (200 MHz, CDCl3): δ = 7.38 (1 H, d, J = 8.0 Hz), 7.30 (2 H, d, J = 8.0 Hz), 7.00 (1 H, m), 6.82 (2 H, d, J = 8.0 Hz), 6.77 (1 H, t, J = 8.0 Hz), 6.50 (1 H, d, J = 8.0 Hz), 5.26 (1 H, d, J = 3.0 Hz), 4.60 (1 H, d, J = 3.0 Hz), 3.84 (1 H, m), 3.82 (3 H, s), 3.58 (1 H, m), 3.22 (1 H, m), 2.04 (1 H, m), 1.58-1.30 (4 H, m). MS-FAB: m/z = 296 [M+ + 1].
4c: semi-solid. 1H NMR (200 MHz, CDCl3): δ = 7.32 (4 H, s), 7.16 (1 H, d, J = 8.0 Hz), 7.04 (1 H, t, J = 8.0 Hz), 6.68 (1 H, t, J = 8.0 Hz), 6.48 (1 H, d, J = 8.0 Hz), 4.67 (1 H, d, J = 10.0 Hz), 4.92 (1 H, d, J = 2.5 Hz), 4.05 (1 H, m), 3.95 (1 H, br s), 3.68 (1 H, t, J = 10.0 Hz), 2.01 (1 H, m), 1.80 (1 H, m), 1.63 (1 H, m), 1.44 (1 H, m), 1.22 (1 H, m). MS-FAB: m/z = 300 [M+ + 1].
5c: viscous. 1H NMR (200 MHz, CDCl3): δ = 7.38 (1 H, d, J = 8.0 Hz), 7.35 (4 H, s), 7.02 (1 H, t, J = 8.0 Hz), 6.74 (1 H, d, J = 8.0 Hz), 6.53 (1 H, d, J = 8.0 Hz), 5.24 (1 H, d, J = 8.0 Hz), 4.65 (1 H, d, J = 2.5 Hz), 3.72 (1 H, m), 3.55
(1 H, m), 3.40 (1 H, m), 2.08 (1 H, m), 1.57-1.32 (4 H, m). MS-FAB: m/z = 300 [M+ + 1].
4d: solid, mp 152-153 °C. 1H NMR (200 MHz, CDCl3): δ = 7.18 (1 H, d, J = 8.0 Hz), 7.04 (1 H, t, J = 8.0 Hz), 6.92 (1 H, d, J = 2.5 Hz), 6.84-6.62 (3 H, m), 6.46 (1 H, d, J = 8.0 Hz), 5.96 (2 H, s), 4.62 (1 H, d, J = 10.0 Hz), 4.36 (1 H, d, J = 3.5 Hz), 4.10 (1 H, m), 3.98 (1 H, br s), 3.70 (1 H, m), 2.02 (1 H, m), 1.85-1.22 (4 H, m). MS-FAB: m/z = 310 [M+ + 1].
5d: solid, mp 160-161 °C. 1H NMR (200 MHz, CDCl3): δ = 7.38 (1 H, d, J = 8.0 Hz), 7.04 (1 H, t, J = 8.0 Hz), 6.92-6.76 (4 H, m), 6.56 (1 H, d, J = 8.0 Hz), 5.96 (2 H, s), 5.24 (1 H, d, J = 6.0 Hz), 4.60 (1 H, d, J = 3.0 Hz), 3.78 (1 H, br s), 3.60-3.38 (2 H, m), 2.05 (1 H, m), 1.60-1.38 (4 H, m). MS-FAB: m/z = 310 [M+ + 1].
4m: solid, mp 147-148 °C. 1H NMR (200 MHz, CDCl3): δ = 7.35 (4 H, s), 7.14 (1 H, d, J = 8.0 Hz), 7.05 (1 H, t, J = 8.0 Hz), 6.64 (1 H, d, J = 8.0 Hz), 6.42 (1 H, d, J = 8.0 Hz), 4.58 (1 H, d, J = 5.0 Hz), 4.08 (1 H, m), 3.85-3.42 (3 H, m), 2.45 (1 H, m), 2.00 (1 H, m), 1.72 (1 H, m). MS-FAB: m/z = 286 [M+ + 1].
5m: solid, mp 152-153 °C. 1H NMR (200 MHz, CDCl3): δ = 7.40 (1 H, d, J = 8.0 Hz), 7.36 (4 H, s), 7.05 (1 H, t, J = 8.0 Hz), 6.68 (1 H, t, J = 8.0 Hz), 5.25 (1 H, d, J = 8.0 Hz), 4.65 (1 H, d, J = 3.0 Hz), 3.78 (1 H, br s), 3.62-3.40 (2 H, m), 2.18 (1 H, m), 1.62-1.50 (2 H, m). MS-FAB: m/z = 286 [M+ + 1].