Lithium borohydride → (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-((S)-1-hydroxybutan-2-yl)piperidin-2-one

To a solution of 256 mg (0.54 mmol) of (S)-ethyl 2-((3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-2-oxopiperidin-1-yl)butanoate (Example 9, Step B) in Et2O (5.5 mL) was added lithium borohydride of 90% purity (17.6 mg, 0.809 mmol) at 0° C. After being stirred at 0° C. for 10 min, the reaction was quenched (ice cold 10% citric acid), extracted (2×EtOAc) and washed (sat. aq. NaCl solution). The combined organic layers were washed with sat. NaCl solution, dried over Na2SO4, filtered and the filtrate was concentrated under reduced pressure. Purification by chromatography on silica gel (eluent 30% to 50% EtOAc/Hexanes, a gradient elution) provided the title compound.