To a solution of (3R,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)piperidin-2-one (Example 42, Step A) (70 mg, 0.19 mmol) in 430 μL of DMF was added sodium hydride (60% suspension in mineral oil, 20 mg, 0.51 mmol) at 0° C. The reaction mixture was stirred at 0° C. for 15 min and after treatment with (bromomethyl)cyclobutane (66 μL, 0.58 mmol) the reaction mixture was heated to 70° C. for 15 h. The reaction mixture was cooled to room temperature, quenched with sat. aqueous NaHCO3 and extracted (2×EtOAc). The combined organic layers were washed with sat. aq. NaCl and NaHCO3-solutions, dried over Na2SO4, filtered and the filtrate was concentrated under reduced pressure. Purification of the residue by silica gel prep plate (25% EtOAc/hexanes) provided the title compound as a colorless solid.
