[Na].[C:2]([C:5]1[O:6][CH:7]=[CH:8][CH:9]=1)(=[O:4])[CH3:3].[C:10](OCC)(=[O:16])[C:11]([O:13][CH2:14]C)=[O:12].OS(O)(=O)=O>CO>[O:6]1[CH:7]=[CH:8][CH:9]=[C:5]1[C:2](=[O:4])[CH2:3][C:10](=[O:16])[C:11]([O:13][CH3:14])=[O:12](see, e.g., Ghosh, A. K., et al., J Med Chem 2005, 48, 6767-71). To a stirred solution of MeOH (150 mL) at room temperature under nitrogen, freshly cut Na (1.81 g, 78.7 mmol) was added in pieces and with care. After all the sodium dissolved, a mixture of 2-acetylfuran (6 mL, 59.8 mmol) and diethyl oxalate (8.14 mL, 59.9 mmol) was added dropwise over a period of 3 min at room temperature. The resulting mixture was continued to stir. Brown precipitates formed after 20 min stir. The mixture was stirred for a total of 1 h. The reaction mixture was cooled to 0° C., and a mixture of concentrated H2SO4 and ice was added. Some solid precipitated at this point which was filtered off but was not the desired product by 1H NMR. The filterate was extracted with CH2Cl2 (50 mL×2). The combined organic layers were washed with brine, dried (Na2SO4), filtered, and concentrated under reduced pressure. The crude was recrystallized from hot iPrOH to give the title compound (4.15 g, 35%) as a dark brown solid. 1H NMR (400 MHz, CDCl3) δ 7.67-7.65 (m, 1H), 7.33 (d, J=3.6 Hz, 1H), 6.93 (s, 1H), 6.60 (dd, J=3.5, 1.5 Hz, 1H), 3.91 (s, 3H). 13C NMR (100 MHz, CDCl3) δ 181.01, 165.39, 162.43, 150.82, 147.73, 118.58, 113.14, 99.17, 53.18.
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