Preparation of 1-Isopropyl-4-piperidone: Potassium carbonate (4.2 g, 31.1 mmol) was added into a solution of isopropylamine (2.1 mL, 3.3 mmol) in ethanol (10 mL) and the resulting mixture was heated at 75 °C. A solution of 1,1-dimethyl-4-oxopiperidinium iodide (4.0 g, 15.5 mmol) in water (5 mL) was added over a period of 30 minutes. The reaction mixture was stirred 1 hour at 75 °C, and then 12 hours at room temperature. The reaction mixture was concentrated under reduced pressure. The residue was taken up with water (25 mL) and extracted with dichloromethane (25 mL). The organic layer was dried (Na2SO4) and concentrated under vacuum. a colourless oil (1.5 g, 69 %). 1H NMR (DMSO-d6, 400 MHz): δ 2.89-2.83 (m, 1 H), 2.67 (t, J=5.9 Hz, 4H), 2.29 (t, J=5.9 Hz, 4H), 0.98 (d, J=6.5 Hz, 6H). LCMS (Method C): Mass found (M+ 142.2), Rt (min): 0.63, Area (%): 99.4 (Max. Chrom.).
