80 g (250 mmol) of (5R,6S)-5-(3-chlorophenyl)-6-(4-chlorophenyl)piperidin-2-one (Example 1, Step E) was added in portions over 20 minutes to a mixture of NaH (19.98 g, 500 mmol) in anhydrous DMF (400 mL) at 0° C. under nitrogen. After the addition was complete the ice bath was removed and the mixture was stirred at rt for 1 hour before cooling the solution to 0° C. To the cooled solution was added a solution of 1-(chloromethyl)-2,4-dimethoxybenzene (107 g, 575 mmol) in benzene and the reaction mixture was allowed to warm to rt. After 16 hours the reaction mixture was poured into ice water (2 L) and extracted with EtOAc (3×1 L). The organics were pooled, washed with water (3×1 L), sat. aq. NaCl solution (1 L), dried (MgSO4), filtered and concentrated in vacuo to provide a thick yellow oil. Purification on the Combiflash XL (flash column chromatography, Teledyne Isco, Lincoln, Nebr.) using four stacked 330 g columns and one 1.5 kg column and eluting with 35-40-45-50-55% EtOAc/hexanes provided a very pale yellow oil. This was dissolved in benzene and the solvent removed in vacuo and dried under vacuum for 2 days to provide the title compound as a white foam (105.8 g, 90%).
