Reaction Steps
To a solution of compound 6 (4.72 g, 0.02 mol) and 7 (8.52 g, 0.03 mol) in degassed pyridine (150 mL) were added K2CO3 (2.76 g, 0.02 mol) and Cu20 (286 mg, 0.002 mol). This reaction mixture was heated at reflux for 12 hours under a nitrogen atmosphere. After addition of additional Cu2O (286 mg, 0.002 mol) to the solution, heating was continued for 12 h. Pyridine was removed under reduced pressure and the residue was redissolved in EtOAc (300 mL). It was washed with water (100 mL) and brine (100 mL), dried (Na2SO4), and concentrated in vacuo. Chromatography on SiO2 (hexanes/EtOAc, 2: 1) gave 6.14 g (78%) of compound 9 as an oil. This oil was treated with TsOH (100 mg) in a mixture of acetone/water (7: 1, 50 mL) for 7 hours at room temperature. The reaction mixture was concentrated in vacuo and the residue was diluted with EtOAc (300 mL), washed with water (2×100 mL) and brine (100 mL), dried (Na2SO4), and concentrated in vacuo. Chromatography on SiO2 (hexanes/EtOAc, 1: 1) gave 5.44 g (100%) of compound 10 as a colorless solid: Mp 152-153 ° C; IR(neat) 2952, 1696, 1581, 1484, 1387, 1272, 1245, 1183, 1095, 980, 838, 821, 759 cm−1; 1H NMR δ7.59 (dd, 1 H, J =8.2, 0.8 Hz), 7.45 (dd, 1 H, J =8.2, 1.0Hz), 7.37 (q, 2 H, J =7.9Hz), 6.87 (dd, 1 H, J =7.6, 0.8 Hz), 6.81 (dd, 1 H, J =7.6, 0.8 Hz), 6.72 (d, 1 H, J=8.9 Hz), 6.67 (d, 1 H, J =9.1 Hz), 3.84 (s, 3 H),3.74 (s, 3 H), 3.05 (t, 2 H, J=6.2 Hz), 2.67 (t, 2 H, J =6.3 Hz), 2.11 (p, 2 H, J =6.4 Hz); 13C NMR δ197.9, 156.2, 155.4, 152.7, 149.3, 137.6,136.4, 126.7, 126.4, 124.1, 123.1, 121.7, 120.7, 118.8, 115.9, 110.1, 106.1, 56.3, 56.0, 40.9, 24.1, 22.5; MS (EI) m/z (rel intensity) 348 (M+, 100), 319 (7), 305 (10), 291 (14), 261 (8), 218 (7), 189 (12), 174 (24), 158 (45), 127 (34), 115 (29), 101 (10), 77 (15), 63 (8); HRMS (EI) Calcd for C22H20O4 348.1361, found 348.1361.
