[CH2:1]1[CH2:12][C:11]2[C:6](=[CH:7][CH:8]=[CH:9][CH:10]=2)[C:4](=[O:5])[CH2:3][CH2:2]1.[C:13](=O)([O:16]C)[O:14][CH3:15].[H-].[Na+].Cl>CO>[O:5]=[C:4]1[C:6]2[CH:7]=[CH:8][CH:9]=[CH:10][C:11]=2[CH2:12][CH2:1][CH2:2][CH:3]1[C:13]([O:14][CH3:15])=[O:16]A mixture of benzosuberone (8 g, 50 mmol) and neat dimethyl carbonate (45 mL) at ambient temperature under nitrogen was treated with sodium hydride (60% in mineral oil, 4 g, 100 mmol) in 0.1 mL of dry methanol, heated at 80° C. for 3 hours, cooled to ambient temperature, treated with 2 N hydrochloric acid (55 mL) and extracted with ethyl acetate. The organic layer was washed with brine, dried (magnesium sulfate) and concentrated to provide the title compound as an oil, as a 3:1 mixture of enol and keto forms of product determined by NMR spectroscopy. The NMR of the main enol form was: 1H NMR (CDCl3) δ 2.03-2.16 (m, 4H), 2.64 (m, 2H), 3.82 (s, 3H), 7.23 (m, 1H), 7.33 (m, 2H), 7.62 (m, 1H), 12.6 (br s, 1H); MS (ESI+) m/z 219 (M+H)−.
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