[OH:1][C:2]1[C:11]2[C:6](=[CH:7][CH:8]=[CH:9][CH:10]=2)[C:5]([CH3:13])([CH3:12])[C:4](=[O:14])[C:3]=1C(OCC)=O.Cl>O1CCOCC1.C(OCC)(=O)C.O>[OH:1][C:2]1[C:11]2[C:6](=[CH:7][CH:8]=[CH:9][CH:10]=2)[C:5]([CH3:12])([CH3:13])[C:4](=[O:14])[CH:3]=1A solution of the product of Example 9E (2.25 g, 8.65 mmol) in dioxane (50 mL) was treated with 1 N HCl solution (60 mL) and the mixture was stirred at reflux for 6 hours, cooled to 25° C., diluted with ethyl acetate and water. The organic layer was washed with water (2×) and saturated sodium chloride solution (1×), dried (Na2SO4), filtered and concentrated in vacuo. The residue was triturated with ether and filtered. The solid was washed with 1:1 ether-hexane and dried to give the title compound (1.0 g, 61%). 1H NMR (300 MHz, DMSO-d6): δ 11.79, 11.59 (two s, 1 H), 7.91 (m, 1 H), 7.58 (m, 2 H), 7.38 (m, 1 H), 5.63 (s, 1 H), 1.48 (s, 3 H), 1.38 (s, 3 H).
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