A 25 mL rb flask was charged with 1.111 g (2.97 mmol) of the product of Step B, 1.451 g (4.45 mmol) Cs2CO3, 10 mL DMF and finally 0.5 mL (3.71 mmol) of bromopinacolone. The reaction mixture was stirred at room temperature 1 h then partitioned between EtOAc and water. The organic layer was washed with water, brine, then dried (MgSO4), filtered and evaporated. The residue was purified on a silica gel flash chromatography column eluted with 0–20% EtOAc-hexane. Evaporation of the purified fractions and drying in vacuo afforded the title compound.
