[CH2:1]([N:3]([CH2:20][CH3:21])[C:4]([C:6]1[CH:19]=[CH:18][C:9](C(Cl)C2C=CC=CC=2)=[CH:8][CH:7]=1)=[O:5])[CH3:2].[I-].[Na+].C(N(C(C)C)CC)(C)C.C(N1C[C@@H](C)NC[C@@H]1C)C=C.C(N1C[C@H](C)NC[C@H]1C)C=C.C1(C)C=CC(C([C@@](C(O)=O)(O)[C@@](C(C2C=CC(C)=CC=2)=O)(O)C(O)=O)=O)=CC=1>C(#N)C>[CH2:20]([N:3]([CH2:1][CH3:2])[C:4](=[O:5])[C:6]1[CH:19]=[CH:18][CH:9]=[CH:8][CH:7]=1)[CH3:21]The crude 4-(N,N-diethylcarbamoyl)benzhydryl chloride (125 mmol) was dissolved in acetonitrile (300 mL). Sodium iodide (18.64 g, 125 mmol), diisopropylethylamine (32.65 mL, 187 mmol), and (+)-(2S,5R)-1-allyl-2,5-dimethylpiperazine (19.23 g, 125 mmol, prepared by the method described in Example 1 for (−)-(2R,5S)-1-allyl-2,5-dimethylpiperazine, but using di-p-toluoyl-L-tartaric acid as the resolving agent) were added. The mixture was stirred at reflux, under nitrogen, for 3 hours. The acetonitrile was removed under reduced pressure, the reaction mixture was poured into ethyl acetate (500 mL) and potassium carbonate solution (150 mL of a 2M aqueous solution), and shaken. The organic phase was separated, washed with water and brine, dried over solid potassium carbonate, and concentrated in vacuo to give 55.35 g (100% crude yield) of 4-((αR and αS)-α-((2R,5S)-4-allyl-2,5-dimethyl-1-piperazinyl)benzyl)-N,N-diethylbenzamide as a 1:1 mixture of isomers, epimeric at the benzhydryl carbon.
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