The compound was purified by silica gel column chromatography (hexanes to 10% ethyl acetate in hexanes)
The compound was purified by silica gel column chromatography (hexanes to 10% ethyl acetate in hexanes). C was treated with potassium bis(trimethylsilyl)amide (KHMDS, 0.5 M, 1.5 mL, 0.75 mmol) and…