Reaction Steps
To a well-stirred solution of 3′,5′-dibenzyloxy-7-hydroxy-flavone, 22 (8 g, 17.8 mmol) in dry dimethyl formamide (200 mL) was added 50% sodium hydride (3 g, 125 mmol) at 0-5° C. and after 30 minutes, excess of epichlorohydrin (8.3 mL, 107 mmol) was added and stirred at room temperature for overnight. The reaction mixture was concentrated under reduced pressure, diluted with water and extracted with chloroform. The combined organic layers were dried over sodium sulphate, filtered and evaporated to dryness. The crude product was purified by column chromatography to afford 28. Yield 7.1 g (79%); mp 172-173° C.; MS (FAB) 507 (M++1); IR (KBr) 1640; 1H NMR (200 MHz, CDCl3) δ 8.13 (d, J=8.7 Hz, 1H), 7.47-7.34 (m, 10H), 7.11 (d, J=2.2 Hz, 2H), 7.00 (dd, J=10.9 Hz, 2.1 Hz, 1H), 6.97 (d, J=1.9 Hz, 1H), 6.77 (d, J=2.0 Hz, 1H), 6.69 (s, 3H), 5.10 (s, 4H), 4.38 (dd, J=11.1 Hz, 2.8 Hz, 1H), 4.04 (dd, J=11.1 Hz, 5.8 Hz, 1H), 3.41-3.40 (m, 1H), 2.95 (t, J=4.5 Hz, 4.5 Hz, 1H), 2.80 (dd, J=4.8 Hz, 2.6 Hz, 1H); 13C NMR δ 177.9, 163.8, 162.9, 160.7, 158.1, 136.7, 133.9, 129.1, 128.6, 127.9, 127.5, 118.2, 115.1, 108.1, 106.0, 105.4, 101.7, 70.8, 69.7, 50.2, 44.9.
