A mixture of 1.02 g (1.66 mmol) of crude 2-((5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)-1-(cyclopropylmethyl)-2-oxo-3-(2-(triisopropylsilyloxy)ethyl)piperidin-3-yl)acetaldehyde (Example 69, Step B, mixture of diastereomers), 0.55 mL (6.6 mmol) of pyrrolidine, 880 mg (4.15 mmol) of sodium triacetoxyborohydride and 285 μL (4.98 mmol) of acetic acid was suspended in a mixture of 1,2-dichloroethane (36 mL) and DMF (12 mL). After being stirred at room temperature for 20 h, the reaction mixture was quenched with saturated aqueous sodium bicarbonate and extracted with DCM (3×). The combined organic layers were dried over Na2SO4, filtered and the filtrate was concentrated. The crude title compound (mixture of C-3 epimers) was used directly in the next step.
