1,2-Dibromoethane → 4-(4-(2-Bromoethoxy)-benzyl)-3-(2,4-dichlorophenyl)-7-methoxy-chromen-2-one

Participants

Reaction Steps

A mixture of 3-(2,4-dichlorophenyl)-4-(4-hydroxybenzyl)-7-methoxy-chromen-2-one (6.4 g, 15.0 mmol), 1,2-dibromoethane (12.9 mL, 149.8 mmol) and K2CO3 (4.14 g, 30 mmol) in acetone (65 mL) was stirred at reflux temperature for 20.5 h. An additional portion of K2CO3 (241.6 mg, 1.75 mmol) and 1,2-dibromoethane (3.2 mL, 37.5 mmol) was added at that time and once more 7.5 h later. Heating was continued for an additional 20 h, for a total reaction time of 48 h. The resultant mixture was cooled to room temperature and poured into CH2Cl2/H2O. The layers were separated, and the aqueous phase was extracted with CH2Cl2 (2×). The combined organic layers were washed with brine (2×) and dried (MgSO4), and the solvent was removed in vacuo. The resultant residue was purified using flash chromatography (300 g silica gel, 4.5:1:1→4:1:1→3:1:1 hexanes:CH2Cl2:AcOEt) to provide the title compound as a white solid (4.851 g, 61%) in addition to recovered starting material (2.054 g, 32%). 1H NMR (300 MHz, CDCl3) δ 7.50 (d, J=2.0 Hz, 1H), 7.44 (d, J=9.0 Hz, 1H), 7.26 (dd, J=2.0, 8.0 Hz, 1H), 7.12 (d, J=8.0 Hz, 1H), 6.98–6.91 (m, 2H), 6.88 (d, J=2.0 Hz, 1H), 6.79–6.74 (m, 3H), 4.23 (t, J=6.5 Hz, 2H), 4.04 (d, J=15.5 Hz, 1H), 3.87 (s, 3H), 3.78 (d, J=15.5 Hz, 1H), 3.61 (t, J=6.5 Hz, 2H); MS (ESI) m/z 532.7 (M+H)+; HPLC tR 8.38 min.

Provenance & Evidence