Diisopropylethylamine → N-(4-((S)-4-(4-chlorophenyl)-4-hydroxy-3,3-dimethylpiperidin-1-yl)-3-methyl-4-oxobutan-2-yl)benzamide

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Reaction Steps

To 3-benzamido-2-methylbutanoic acid (0.055 g, 0.249 mmol) in THF (2 mL) are sequentially added (S)-4-(4-chlorophenyl)-3,3-dimethylpiperidin-4-ol (WO 04/043965, 0.060 g, 0.249 mmol), N,N-diisopropylethylamine (0.087 mL, 0.497 mmol) and BOP (0.110 g, 0.249 mmol) at RT. The reaction mixture was stirred at RT for 70 h, and concentrated. The oily residue was dissolved in MeOH (2.0 mL) and subjected to preparative HPLC (Phenomex S10 30×100 mm; 10 min. gradient; solvent A=10% MeOH, 90% H2O, 0.1% TFA, solvent B=90% MeOH, 10% H2O, 0.1% TFA). Two fractions (diastereomer A and B) are collected and individually processed by concentrating and partitioning between dichloromethane (10 mL) and sat. aq. NaHCO3 (10 mL). The dichloromethane layer was dried over sodium sulfate and concentrated to yield: Diastereomer A: (0.042 g, 0.089 mmol, 35.9% yield) as a foamy solid. Retention time=3.23 min (YMC S5 Combi ODS 4.6×50 mm; 4 min. gradient; solvent A=10% MeOH, 90% H2O, 0.2% H3PO4, solvent B=90% MeOH, 10% H2O, 0.2% H3PO4. MS (ESI) m/z 443.11 (M+H)+; and Diastereomer B: (0.03 g, 0.064 mmol, 25.9% yield) as a foamy solid. Retention time=3.42 min (YMC S5 Combi ODS 4.6×50 mm; 4 min. gradient; solvent A=10% MeOH, 90% H2O, 0.2% H3PO4, solvent B=90% MeOH, 10% H2O, 0.2% H3PO4. MS (ESI) m/z 443.12 (M+H)+.

Provenance & Evidence