(−)-4-((αS)-α-((2R,5R)-4-Allyl-2,5-dimethyl-1-piperazinyl)-3-hydroxybenzyl)-N,N-diethylbenzamide (0.200 g, 0.46 mmol, Example 2) was dissolved in toluene (10 mL) and stirred for 4 hours under a hydrogen atmosphere. The solution was filtered through celite to give 0.182 g of crude product. The phenol was reprotected as follows to improve chromatographic resolution. A mixture of crude product (0.18 g), tert-butylchlorodimethylsilane (0.93 g), and imidazole (0.070 g) in 10 mL of acetonitrile was stirred overnight at room temperature. The reaction solution was poured into 100 mL of water and extracted with two 50 mL portions of dichloromethane. The combined extracts were dried over sodium sulfate and the solvent removed. The residue was purified on a column of silica gel with ethanol (0-4%) in dichloromethane to give 0.085 g of 4-((αS)-α-((2R,5R)-2,5-dimethyl-4-propyl-1-piperazinyl)-3-(tert-butyldimethylsilyloxy)benzyl)-N,N-diethylbenzamide as a light-brown solid.
