Synlett 2007(20): 3107-3112  
DOI: 10.1055/s-2007-990922
LETTER
© Georg Thieme Verlag Stuttgart · New York

An Efficient and Convenient Protocol for the Synthesis of Novel 12-Aryl- or 12-Alkyl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-one Derivatives [1]

Biswanath Das*, Keetha Laxminarayana, Maddeboina Krishnaiah, Yallamalla Srinivas
Organic Chemistry Division I, Indian Institute of Chemical Technology, Hyderabad 500 007, India
Fax: +91(40)7160512; e-Mail: biswanathdas@yahoo.com;
Further Information

Publication History

Received 19 March 2007
Publication Date:
03 December 2007 (online)

Abstract

An efficient and direct procedure for the synthesis of novel 12-aryl- or 12-alkyl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-one derivatives has been described. The process employs a three-component condensation reaction in one-pot using 2-naphthol, aldehydes and cyclic 1,3-dicarbonyl compounds in the presence of a catalytic amount of NaHSO4·SiO2 in 1,2-dichloroethane under reflux.

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Part 130 in the series ‘Studies on novel synthetic methodologies’.

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Part 130 in the series ‘Studies on novel synthetic methodologies’.

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General Procedure for the Synthesis of 12-Aryl- or 12-Alkyl-8,9,10,12-tetrahydrobenzo[ a ]xanthen-11-one Derivatives: NaHSO4·SiO2 (100 mg) was added to a mixture of 2-naphthol (1.0 mmol), aldehyde (1.0 mmol) and dimedone (1.2 mmol) in DCE (5 mL). The mixture was stirred at reflux conditions and the reaction was monitored by TLC. After completion of the reaction, the mixture was filtered. The filtrate was concentrated and the residue was purified by column chromatography (silica gel, 3% EtOAc in hexane) to afford the pure 12-aryl- or 12-alkyl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-one derivative.
Spectral data of some representative products are given below:
Compound 3b: 1H NMR (200 MHz, CDCl3): δ = 7.86 (dd, J = 2.0, 8.0 Hz, 1 H), 7.75 (dd, J = 2.0, 8.0 Hz, 2 H), 7.11-7.46 (m, 7 H), 5.62 (s, 1 H), 2.63 (s, 2 H), 2.31 (d, J = 12.0 Hz, 1 H), 2.20 (d, J = 12.0 Hz, 1 H), 1.12 (s, 3 H), 0.91 (s, 3 H). 13C NMR (50 MHz, CDCl3): δ = 196.8, 164.0, 147.8, 143.3, 132.0, 131.5, 131.3, 129.8, 129.1, 128.5, 128.4, 127.1, 125.0, 123.5, 117.1, 117.0, 113.9, 50.9, 41.4, 34.2, 32.2, 29.3, 27.1. MS (FAB): m/z = 389, 391 [M + H]+·.
Compound 3g: 1H NMR (200 MHz, CDCl3): δ = 7.94 (dd, J = 2.0, 8.0 Hz, 1 H), 7.72 (dd, J = 2.0, 8.0 Hz, 2 H), 7.32-7.45 (m, 2 H), 7.29 (d, J = 8.0 Hz, 1 H), 7.14 (d, J = 8.0 Hz, 2 H), 6.55 (d, J = 8.0 Hz, 2 H), 5.59 (s, 1 H), 5.47 (s, 1 H), 2.58 (s, 2 H), 2.32 (d, J = 12.0 Hz, 1 H), 2.23 (d, J = 12.0 Hz, 1 H), 1.12 (s, 3 H), 1.01 (s, 3 H). 13C NMR (50 MHz, CDCl3): δ = 197.6, 164.8, 154.6, 148.1, 137.5, 131.1, 129.9, 129.9, 129.1, 128.8, 127.2, 125.0, 124.6, 117.5, 117.0, 115.2, 114.9, 50.7, 40.4, 33.2, 31.8, 29.1, 26.9. MS (FAB): m/z = 371 [M + H]+·.
Compound 3i: 1H NMR (200 MHz, CDCl3): δ = 7.92 (dd, J = 2.0, 8.0 Hz, 1 H), 7.74 (dt, J = 2.0, 8.0 Hz, 2 H), 7.42-7.55 (m, 2 H), 7.27 (d, J = 8.0 Hz, 1 H), 7.01 (d, J = 2.0 Hz, 1 H), 6.62 (d, J = 8.0 Hz, 1 H), 6.51 (dd, J = 2.0, 8.0 Hz, 1 H) 5.59 (s, 1 H), 5.28 (s, 1 H), 3.86 (s, 3 H), 2.52 (s, 2 H), 2.30 (d, J = 12.0 Hz, 1 H), 2.22 (d, J = 12.0 Hz, 1 H), 1.13 (s, 3 H), 0.99 (s, 3 H). 13C NMR (50 MHz, CDCl3): δ = 197.2, 164.6, 147.8, 146.2, 144.1, 137.4, 131.1, 128.8, 128.2, 127.0, 124.9, 124.2, 121.2, 118.0, 117.5, 114.6, 114.3, 110.9, 55.8, 50.5, 40.1, 34.2, 31.8, 29.7, 26.8. MS (FAB): m/z = 401 [M + H]+·. Compound 3l: 1H NMR (200 MHz, CDCl3): δ = 8.07 (d, J = 8.0 Hz, 1 H), 7.77 (d, J = 8.0 Hz, 1 H), 7.64 (d, J = 8.0 Hz, 1 H), 7.49 (t, J = 8.0 Hz, 1 H), 7.38 (t, J = 8.0 Hz, 1 H), 7.12 (d, J = 8.0 Hz, 1 H), 4.69 (t, J = 7.0 Hz, 1 H), 2.50 (s, 2 H), 2.38 (d, J = 12.0 Hz, 1 H), 2.29 (d, J = 12.0 Hz, 1 H), 1.78-1.89 (m, 2 H), 1.20 (s, 3 H), 1.12 (s, 3 H), 0.61 (t, J = 7.0 Hz, 3 H). 13C NMR (50 MHz, CDCl3): δ = 197.9, 166.1, 148.8, 131.2, 131.0, 128.2, 128.1, 126.4, 124.2, 123.1, 117.8, 115.2, 111.5, 50.8, 41.1, 31.5, 29.2, 28.8, 27.3, 9.1. MS (FAB): m/z = 307 [M + H]+·.
Compound 3o: 1H NMR (200 MHz, CDCl3): δ = 7.85 (dd, J = 2.0, 8.0 Hz, 1 H), 7.80 (d, J = 8.0 Hz, 2 H), 7.06-7.48 (m, 7 H), 5.64 (s, 1 H), 2.63-2.85 (m, 2 H), 2.31-2.42 (m, 2 H), 1.92-2.11 (m, 2 H). 13C NMR (50 MHz, CDCl3): δ = 197.0, 165.8, 147.8, 143.5, 132.0, 131.5, 131.2, 130.0, 129.1, 128.5, 128.4, 127.1, 125.0, 123.5, 117.0, 116.9, 115.1, 37.0, 34.1, 27.7, 20.3. MS (FAB): m/z = 361, 362 [M + H]+·.