C([O:4][C:5]1[CH:19]=[CH:18][C:8]([O:9][C:10]([CH3:17])([CH3:16])[C:11]([O:13][CH2:14][CH3:15])=[O:12])=[C:7]([CH3:20])[CH:6]=1)(=O)C.[O-]CC.[Na+].Cl>C(O)C>[OH:4][C:5]1[CH:19]=[CH:18][C:8]([O:9][C:10]([CH3:17])([CH3:16])[C:11]([O:13][CH2:14][CH3:15])=[O:12])=[C:7]([CH3:20])[CH:6]=1A solution of ethyl 2-[4-(acetyloxy)-2-methylphenoxy]-2-methylpropanoate (intermediate 9, 40.8 g) in ethanol (280 ml) was treated with sodium ethoxide (12.9 g) at room temperature under nitrogen. The resulting solution was heated to 50° C. for 1 hour. 2M hydrochloric acid (95 ml) was added to the cooled reaction and the solution concentrated. The residue was dissolved in t-butylmethyl ether and the resulting solution washed with water followed by brine and then dried over sodium sulfate, filtered and the filtrate concentrated to give a brown oil. Further purification by Biotage® chromatography eluting initially with cyclohexane and then cyclohexane:ethyl acetate (5:1) gave the title compound as an orange oil.
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