[CH2:1]=[C:2]([CH2:6][C:7]1[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=1)[C:3]([OH:5])=[O:4].C(=O)([O-])[O-].[K+].[K+].[CH2:19](Br)[C:20]1[CH:25]=[CH:24][CH:23]=[CH:22][CH:21]=1.C(OCC)(=O)C>CN(C)C=O>[CH2:1]=[C:2]([CH2:6][C:7]1[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=1)[C:3]([O:5][CH2:19][C:20]1[CH:25]=[CH:24][CH:23]=[CH:22][CH:21]=1)=[O:4]The title acid of Step 9 (5.2 g, 30 mmol) was dissolved in dimethylformamide (25 mL) and cooled to 0° C. To this potassium carbonate (5.7 g, 41.48 mmol) was added followed by benzyl bromide (5.7 g, 29.7 mmol). The mixture was stirred at room temperature overnight. The mixture was filtered and the filtrate was diluted with ethyl acetate, washed with 3 times of water, brine. The solution was dried (Na2SO4) and evaporated. The residue was purified by flash chromatography on silica gel, eluting with 90:10 heptane:ethyl acetate to give the pure title compound as colorless oil (4.5 g, 60% yield). 1H NMR: 300 MHz spectrum consistent with proposed structure. Anal: calcd. for C17H16O2 : C, 80.93; H, 6.39. Found: C, 80.69; H, 6.47.
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