[I:1][C:2]1[CH:3]=[CH:4][CH:5]=[C:6]2[C:11]=1[CH:10]=[C:9]([OH:12])[CH:8]=[CH:7]2.C(=O)([O-])[O-].[Cs+].[Cs+].[CH2:19](Br)[C:20]1[CH:25]=[CH:24][CH:23]=[CH:22][CH:21]=1.CCOC(C)=O>CN(C=O)C.O>[CH2:19]([O:12][C:9]1[CH:8]=[CH:7][C:6]2[C:11](=[C:2]([I:1])[CH:3]=[CH:4][CH:5]=2)[CH:10]=1)[C:20]1[CH:25]=[CH:24][CH:23]=[CH:22][CH:21]=1
To a solution of the product from Step A (1.18 g, 4.37 mmol) in 20 mL of DMF was added cesium carbonate (2.48 g, 8.74 mmol) and benzyl bromide (0.52 mL, 4.37 mmol). After stirring overnight at room temperature, the reaction was poured into EtOAc and water, washed with 5% NaOH solution, water, 10% NaHSO3 solution and brine, dried over MgSO4, filtered, and concentrated in vacuo. The residue was purified by flash column chromatography on silica gel (5% EtOAc/hexane) to yield the desired product as a pink solid.
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