A mixture of the above oxime (2.0 g, 11 mmol), (R)-1-(2-bromoethyl)-3-piperidinecarboxylic acid ethyl ester hydrobromide (3.94 g, 11 mmol), potassium carbonate (4.73 g, 34 mmol) and acetone (25 ml) was stirred at room temperature for 4 days. The mixture was filtered and the solvent was evaporated from the filtrate in vacuo. The residue was purified by column chromatography on silica gel (75 g, cyclohexane/ethyl acetate 3/1) to give 2.08 g of (R)-1-(2-(((2-phenyl-2-penten-1-ylidene)amino)oxy)ethyl)-3-piperidinecarboxylic acid ethyl ester.
