Reaction Steps
A mixture containing 4-bromo-5(H)furanone (0.274 g, 1.681 mmol), 4-trifluoromethoxyphenylboronic acid (0.417 g, 2.025 mmol), trans-dichlorobis(triphenylphosphine)palladium (II) (0.060 g, 8.548×10−2 mmol), tetrabutylammonium iodide (0.032 g, 8.663×10−2 mmol) and potassium fluoride (0.401 g, 6.902 mmol) in toluene (10 mL) and water (10 mL) were gently refluxed for 24 h under nitrogen before the reaction mixture was allowed to cool to room temperature. Brine (50 mL) was added and the product extracted with dichloromethane (3×20 mL). The organic fractions were combined, washed with brine (3×20 mL), dried over anhydrous magnesium sulfate and evaporated to dryness under reduced pressure to give a dark brown solid. The resulting solid was chromatographed (silica gel: eluent 100% dichloromethane) to give 4-(4′-trifluoromethoxyphenyl)furan-2(5H)-one 5 (0.354 g, 86%) as a pale yellow powder, m.p. 122-123° C. (ref. PDS-1-115). UV-Vis λmax (MeOH) 211(22865), 269(28180) nm; 1H NMR (CDCl3) δ 7.56 (dt, 2H, J=2.6 Hz, J=9.4 Hz, H2′, H6′), 7.32 (d, 2H, J=7.9 Hz, H3′, H5′), 6.38 (t, 1H, J=1.9 Hz, H3), 5.21 (d, 2H, J=1.9 Hz, H5); 13C NMR (CDCl3) δ 173.3 (C2), 162.2 (C4′), 151.4 (C4), 128.20 (C1′), 128.17 (C3), 121.4 (C2′, C6′), 120.3 (q, J=257.0 Hz, C4′-OCF3), 113.9 (C3′, C5′), 70.8 (C5); 19F NMR (CDCl3, 282 MHz) δ −58.19 (s, 3F, C4′-OCF3); IR (KBr) 3109, 3073, 3011, 2936, 1790, 1747, 1624, 1588, 1513, 1443, 1422, 1252, 1159, 1046, 1018, 989, 921, 893, 847, 804, 742, 705, 611, 556, 471 cm−1.
