Reaction Steps
A solution of 6 (8.04 g, 2.2 mmol) in anhydrous DMF (150 mL) under Ar was treated with K2CO3 (5.65 g, 40.9 mmol), benzyl bromide (5.59 g, 32.7 mmol, 1.2 equiv) and BU4NI (402 mg, 1.1 mmol, 0.04 equiv). After stirring for 11 h at 25° C., the reaction mixture was poured into H2O (200 mL) and extracted with EtOAc (3×200 mL). The combined organic layers were washed with saturated aqueous NaCl, dried (MgSO4) and concentrated. The resulting solid was recrystallized from 5% EtOAc-hexane to afford 12 (8.36 g, 10.49 g theoretical, 80%) as white needles. An additional 2.13 g (20%) of 12 was obtained by chromatography (SiO2, 4×20 cm, 10% EtOAc-hexane) of the crystallization mother liquors: mp 105° C. (needles, hexane); 1H NMR (CDCl3, 250 MHz) δ8.19 (d, 1H, J=8.8 Hz), 8.10 (s, 1H), 8.05 (d, 1H, J=1.8 Hz), 7.61 (dd, 1H, J=1.9, 8.9 Hz), 7.50 (m, 6H), 5.28 (s, 2H), 4.45 (q, 2H, J=7.1 Hz), 1.46 (t, 3H, J=7.1 Hz); 13C NMR (CDCl3, 100 MHz) δ166.5, 154.7, 136.4, 134.7, 130.8, 130.7, 129.1, 128.7, 128.3, 127.6, 126.3, 124.2, 122.5, 121.5, 104.6, 70.4, 61.4, 14.4; IR (KBr) vmax 2986, 1716, 1589, 1578, 1406, 1369, 1331, 1279, 1238, 1098, 1025, 962, 892, 816, 767, 725, 691 cm-1 ; FABHRS (NBA) m/z 384.0370 (M+, C20H17BrO3 requires 384.0361).
