A solution of the product of Example 8 (2.0 g), piperidine (0.91 mL), and acetic acid (0.42 mL) in DCM (100 mL) was treated with sodium triacetoxyborohydride (1.95 g) at room temperature. After 16 h, the resulting mixture was treated with 10% aqueous sodium hydroxide (30 mL). The aqueous phase was extracted with DCM (2×300 mL). The combined organic phases were dried (magnesium sulfate) and concentrated under reduced pressure. The residue was diluted in DCM (100 mL) and passed through a pad of silica gel. The pad was washed with DCM (3×200 mL). The combined filtrate was concentrated under reduced pressure, giving the title compound as a brown oil (2.3 g).
