Pyridine → 2-(3,4,5-Trimethoxyphenyl)-2,3-dihydro-benzo[H]chromen-4-one

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Reaktionsschritte

A mixture of 1-hydroxy-2-acetonaphthone 1 (15 g, 81 mmol) and 3,4,5-trimethoxy-benzaldehyde 2 (17.66 g, 88 mmol) in 600 mL ethanol was treated with piperidine (40 mL) and pyridine (45 mL) and the dark solution was refluxed for 18 h. The reaction mixture was evaporated to dryness and the dark residue was dissolved in methylene chloride (600 mL). The solution was washed with 2×300 mL of water and 2×300 mL brine and dried with anhydrous MgSO4 after which it was filtered and evaporated to afford 60 g of crude material. This was purified via flash chromatography, eluting with methylene chloride (1 L), followed by the solvent mixture CH2Cl2: EtOAc (95:5) to obtain fractions containing pure product. These were evaporated to afford 11.4 g (39% yield) of pure SR 13177 as a yellow solid. TLC: Hexanes/EtOAc (7:3): Rf=0.26; 1H NMR (300 MHz, CDCl3): δ 3.00 (dd, J=16.69, 3.15, 1H, 3-H), 3.22 (dd, J=16.94, 13.28, 1H, 3-H), 3.92 and 3.94 (2s, 9H, OCH3), 5.66 (dd, J=13.31, 3.17, 1H, 2-H), 6.81 (s, 2H, 2′,6′-Ar—H), 7.46-7.95 (m, 5H, Ar—H), 8.36 (d, 1H, Ar—H); 13C (75 MHz, CDCl3): δ 44.27 (C-3), 56.35 (OCH3), 60.89 (OCH3), 80.62 (C-2), 103.49, 115.61, 121.47, 123.61, 124.91, 126.34, 127.94, 129.71, 134.4, 137.67, 153.68, 159.71, 191.42. Anal. calcd. for C22H20O5; C, 72.51; H, 5.53; Found: C, 72.35; H, 5.64.

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